JP7772602B2 - Sheet for forming first protective film, method for manufacturing semiconductor device, and use of the sheet - Google Patents

Description

The present invention relates to a sheet for forming a first protective film, a method for manufacturing a semiconductor device, and use of the sheet.

Conventionally, when mounting high-pin count LSI packages used in MPUs, gate arrays, etc., on printed wiring boards, semiconductor chips with convex electrodes (hereinafter referred to as "bumps" in this specification) made of eutectic solder, high-temperature solder, gold, etc. on their connection pads have been used, and the so-called face-down flip-chip mounting method has been used, in which these bumps are brought face-to-face and into contact with corresponding terminals on the chip-mounting substrate, resulting in melt/diffusion bonding.

The semiconductor chips used in this mounting method are obtained, for example, by grinding or dicing the surface opposite the circuit surface (i.e., the bump-formed surface) of a semiconductor wafer having bumps formed on its circuit surface into individual pieces. In the process of obtaining such semiconductor chips, for example, a curable protective film-forming film is applied to the bump-formed surface of the semiconductor wafer to protect the bumps and the bumps, and this film is cured to form a protective film on the bump-formed surface. In this specification, such protective film-forming film and protective film may be referred to as the "first protective film" and "first protective film," respectively. In this case, the bumps on the bump-formed surface must penetrate the protective film-forming film (first protective film-forming film), with the tops of the bumps protruding from the protective film-forming film.

Figure 1 is a cross-sectional view that schematically illustrates an example of a state in which the protective film-forming film remains on the top of the bumps, as opposed to the above case. A conventional protective film-forming film 82 is attached to the surface 9a (bump-forming surface) of the semiconductor wafer 9 that has bumps 91. However, the tops 9101 of the bumps 91 do not protrude from the protective film-forming film 82, and the protective film-forming film 82 remains on the tops 910 of the bumps 91. While this example shows an example in which the entire surface 91a of the bumps 91 is covered with the protective film-forming film 82, this is only one example of how the protective film-forming film 82 remains. For example, in some cases, a portion of the surface 91a of the tops 910 of the bumps 91 may be exposed and not covered by the protective film-forming film 82. A semiconductor wafer with a protective film-forming film remaining on the tops of the bumps cannot be used for flip-chip mounting as is.

On the other hand, when attaching a protective film-forming film to the bump-forming surface, a protective film-forming sheet may be used in which a protective film-forming film, an adhesive layer, and a substrate are laminated in this order. In this specification, such a protective film-forming sheet may be referred to as a "first protective film-forming sheet." In this case, the adhesive layer and substrate are removed from the protective film-forming film after it has been attached to the bump-forming surface, and the protective film-forming film is cured.

One such protective film-forming sheet has been disclosed, which comprises, in this order, a substrate, an energy ray-curable adhesive layer, a buffer layer, and a curable protective film-forming film, in which the shear storage modulus of the protective film-forming film before curing and the tensile storage modulus of the adhesive layer after energy ray curing are set within specific ranges (see Patent Document 1). By using this protective film-forming sheet (first protective film-forming sheet), the adhesive layer and substrate can be easily removed from the protective film-forming film (first protective film-forming film) after it has been attached to the bump-forming surface, allowing for the successful formation of a protective film (first protective film) on the bump-forming surface. Furthermore, when the protective film-forming film is attached to the bump-forming surface, the buffer layer improves the bump protection effect.

International Publication No. 2020/189447

Meanwhile, in recent years, efforts have been made to apply the protective film-forming film in the protective film-forming sheet to the bump-forming surface at higher speeds than before in order to efficiently form a protective film on the bump-forming surface. However, when applying the protective film-forming film to the bump-forming surface, not only is the application itself difficult, but it also becomes difficult to cause the tops of the bumps to protrude from the protective film-forming film. Even if they do protrude, the protective film-forming film is likely to remain on the tops, including the tops of the bumps. If the protective film-forming film remains on the tops of the bumps, the protective film will remain attached to the tops of the bumps, making the semiconductor chip unsuitable for flip-chip mounting. In contrast, the protective film-forming sheet disclosed in Patent Document 1 is highly suitable for applying the protective film-forming film to the bump-forming surface, but is not intended for high-speed application.

The present invention aims to provide a protective film forming sheet that includes a protective film forming film for forming a protective film on a surface of a semiconductor wafer having bumps. The protective film forming film within the protective film forming sheet allows the tops of the bumps to protrude from the protective film forming film, even when the protective film forming sheet is attached to the surface of the semiconductor wafer at high speed, and prevents the protective film from remaining on the upper part, including the tops of the bumps.

In order to solve the above problems, the inventors have conducted extensive research and found that, while the elastic modulus of the pressure-sensitive adhesive layer and the elastic modulus of the buffer layer in conventional protective film-forming sheets are roughly equal, the lower the shear storage modulus (G _x ') of the intermediate release layer corresponding to the pressure-sensitive adhesive layer relative to the shear storage modulus (G _A ') of the buffer layer, the more the first protective film-forming film is prevented from remaining at the top of the bump and the top of the bump has the property of easily protruding, thereby achieving the object.

That is, the present invention provides a first protective film forming sheet for forming a first protective film on at least a surface of a semiconductor wafer having bumps, the first protective film forming sheet being constructed by laminating a first substrate, a buffer layer, an intermediate release layer, and a first protective film forming film in this order in the thickness direction, and the ratio (G _x '/G _A ') of the shear storage modulus (G _x ') of the intermediate release layer to the shear storage modulus (G _A ') of the buffer layer is less than 0.6.

In the sheet for forming a first protective film of the present invention, the intermediate release layer may contain an ethylene-vinyl acetate copolymer.
In the ethylene-vinyl acetate copolymer, the proportion of the amount of structural units derived from vinyl acetate relative to the total amount of structural units may be 16 to 40 mass %.
In the sheet for forming a first protective film of the present invention, the ethylene-vinyl acetate copolymer may have a weight average molecular weight of 200,000 or less.
In the sheet for forming a first protective film of the present invention, the intermediate release layer may have a shear storage modulus (G _x ') of 10,000 Pa or less.

The present invention also provides a method for manufacturing a semiconductor device using the first protective film-forming sheet, the manufacturing method including: a bonding step of bonding the first protective film-forming film in the first protective film-forming sheet to a surface of a semiconductor wafer having bumps, and causing tops of the bumps to protrude from the first protective film-forming film, thereby providing the first protective film-forming sheet on the semiconductor wafer;
a first protective film forming step of removing layers of the first protective film-forming sheet other than the first protective film-forming film from the first protective film-forming film after the attaching step, and further, if the first protective film-forming film is curable, curing the first protective film-forming film to form a first protective film, or, if the first protective film-forming film is non-curable, treating the first protective film-forming film after removing layers other than the first protective film-forming film as a first protective film, thereby forming the first protective film on the surface having the bumps;
a dividing step of dividing the semiconductor wafer into semiconductor chips after the first protective film forming step;
a cutting step of cutting the first protective film after the first protective film forming step;
The present invention provides a method for manufacturing a semiconductor device, the method comprising: a mounting step of flip-chip connecting the semiconductor chip with the first protective film, which is provided on the surface of the semiconductor chip having the bumps and which is obtained after the dividing step and the cutting step, and the tops of the bumps protruding from the first protective film, to a substrate at the tops of the bumps.
In the attaching step of the method for manufacturing a semiconductor device of the present invention, the first protective film-forming film may be attached to the surface of the semiconductor wafer having the bumps at an attachment speed of 4 mm/s or more.

The present invention also provides a use of a sheet for forming a first protective film on at least a surface of a semiconductor wafer having bumps, the use comprising:
The sheet is configured by laminating a first substrate, a buffer layer, an intermediate release layer, and a first protective film-forming film in this order in a thickness direction,
The present invention provides use of a sheet in which the ratio (G _x '/G _A ') of the shear storage modulus (G _x ') of the intermediate release layer to the shear storage modulus (G _A ') of the buffer layer is less than 0.6.

The present invention provides a protective film forming sheet that includes a protective film-forming film for forming a protective film on a surface of a semiconductor wafer that has bumps. Even when the protective film forming sheet is attached to the surface of the semiconductor wafer at high speed, the protective film-forming film within the sheet allows the tops of the bumps to protrude from the protective film-forming film, thereby preventing the protective film from remaining on the upper parts, including the tops of the bumps.

FIG. 10 is a cross-sectional view schematically showing an example of a state in which the protective film-forming film remains on the top of the bump. 1 is a cross-sectional view schematically illustrating an example of a first protective film-forming sheet according to an embodiment of the present invention. 3 is a cross-sectional view for schematically explaining an example of a method for manufacturing a semiconductor device when the first protective film forming sheet shown in FIG. 2 is used. FIG. 3 is a cross-sectional view for schematically explaining another example of a method for manufacturing a semiconductor device when the first protective film forming sheet shown in FIG. 2 is used. FIG.

◇First protective film forming sheet A first protective film forming sheet according to one embodiment of the present invention is a first protective film forming sheet for forming a first protective film on at least a surface of a semiconductor wafer having bumps, and the first protective film forming sheet is configured by laminating a first substrate, a buffer layer, an intermediate release layer, and a first protective film forming film in this order in the thickness direction, and the ratio (G _x '/G _A ') of the shear storage modulus (G _{x '} ) of the intermediate release layer to the shear storage modulus (G A ') of the buffer layer is less than 0.6.
Because the first protective film forming sheet of this embodiment has such a configuration, the protective film forming film contained therein can cause the tops of the bumps to protrude from the protective film forming film even when the sheet is attached to the bump-bearing surface of a semiconductor wafer at high speed, thereby preventing the protective film from remaining in the upper part, including the tops of the bumps.

In this specification, the shear storage modulus (G _x ') of the intermediate release layer refers to the shear storage modulus (G _x ') [Pa] measured using a shear viscosity measuring device on a disc-shaped test piece of the intermediate release layer under the conditions of a temperature of 90°C, a measurement frequency of 1 Hz, and a shear strain of 1%.

In this specification, the shear storage modulus (G _A ') of the buffer layer refers to the shear storage modulus (G _A ') [Pa] measured using a shear viscosity measuring device on a disk-shaped test piece of the buffer layer under the conditions of a temperature of 90°C, a measurement frequency of 1 Hz, and a shear strain of 1%.

For example, the shear storage modulus of an intermediate release layer or buffer layer can be determined by laminating multiple intermediate release layers or buffer layers to create a disc-shaped test piece with a diameter of 25 mm and a thickness of 400 μm, and then measuring the shear storage modulus of the test piece at a shear strain of 1% by increasing the generated shear strain stepwise from 0.01% to 10% using a shear viscosity measuring device (e.g., Anton Paar's MCR301) at a temperature of 90°C and a measurement frequency of 1 Hz.

The ratio (G _x '/G _A ') of the shear storage modulus (G _x ') of the intermediate release layer to the shear storage modulus (G _A ') of the buffer layer is determined by dividing the shear storage modulus (G _x ') [Pa] of the test piece of the intermediate release layer by the shear storage modulus (G _A ') [Pa] of the test piece of the buffer layer.

In the first protective film-forming sheet of this embodiment, the ratio (G _x '/G _A ') is 0.6 or less, preferably 0.4 or less, more preferably 0.3 or less, even more preferably 0.10 or less, and particularly preferably 0.05 or less. When the ratio (G _x '/G _A ') is equal to or less than the upper limit, both the high-speed application property of the first protective film-forming sheet and the bump penetration property of the first protective film-forming film are improved.

In the first protective film-forming sheet of this embodiment, the ratio (G _x '/G _A ') may be 0.00001 or more, or may be 0.0001 or more.

In the first protective film-forming sheet of this embodiment, the shear storage modulus (G _x ') of the intermediate release layer may be 50,000 Pa or less, preferably 10,000 Pa or less, more preferably 7,000 Pa or less, even more preferably 1,000 or less, and particularly preferably 300 or less. When the shear storage modulus (G _x ') of the intermediate release layer is the upper limit or less, it becomes easy to adjust the ratio (G _x '/G _A ') to 0.6 or less, and both the high-speed application property of the first protective film-forming sheet and the bump penetration property of the first protective film-forming film are improved.

In the first protective film-forming sheet of this embodiment, the shear storage modulus (G _x ') of the intermediate release layer may be 1 Pa or more, or may be 5 Pa or more.

In the first protective film-forming sheet of this embodiment, the shear storage modulus (G _A ') of the buffer layer is preferably 10,000 to 400,000 Pa, more preferably 50,000 to 300,000 Pa, and particularly preferably 100,000 to 200,000 Pa. When the shear storage modulus (G _A ') of the buffer layer is equal to or greater than the lower limit, the effect of the buffer layer is enhanced. When the shear storage modulus (G _A ') of the buffer layer is equal to or less than the upper limit, the buffer layer is prevented from becoming excessively hard.

In this specification, the surface of a semiconductor wafer or semiconductor chip that has bumps may be referred to as the "bump-forming surface." The surface of a semiconductor wafer or semiconductor chip opposite the bump-forming surface may be referred to as the "back surface."

In this specification, the protective film provided on the surface of the semiconductor wafer or semiconductor chip opposite to the surface on which bumps are formed (i.e., the back surface) is referred to as a "second protective film."
To provide a second protective film on the surface (back surface) opposite to the bump-forming surface of a semiconductor wafer or semiconductor chip, a second protective film-forming sheet is used, which is configured to include a second protective film-forming film for forming the second protective film. Examples of the second protective film-forming sheet include a sheet configured to include a dicing sheet and a second protective film-forming film provided on the dicing sheet. When the dicing sheet includes the same material as the first substrate, this substrate is referred to as a "second substrate."

The first protective film forming sheet of this embodiment can form a first protective film not only on the bump-forming surface of a semiconductor chip, but also on the side surfaces, as described below. In other words, the first protective film forming sheet of this embodiment can be used as a sheet for forming a first protective film at least on the bump-forming surface of a semiconductor wafer.

FIG. 2 is a cross-sectional view schematically illustrating an example of the first protective film-forming sheet of this embodiment.
In addition, the drawings used in the following explanation may show enlarged essential parts for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

The first protective film-forming sheet 1 shown here is configured to include a first substrate 11, a buffer layer 12 provided on one surface 11a of the first substrate 11, an intermediate release layer 13 provided on a surface 12a of the buffer layer 12 opposite the first substrate 11 side, and a first protective film-forming film 14 provided on a surface 13a (sometimes referred to as the "first surface" in this specification) of the intermediate release layer 13 opposite the buffer layer 12 side. That is, the first protective film-forming sheet 1 is configured by laminating the first substrate 11, the buffer layer 12, the intermediate release layer 13, and the first protective film-forming film 14 in this order in the thickness direction.
The first protective film forming sheet 1 further has a release film 15 provided on the side 14a opposite the intermediate release layer 13 side of the first protective film forming film 14 (sometimes referred to as the "first side" in this specification).

In the first protective film-forming sheet 1, the intermediate release layer 13 preferably contains ethylene-vinyl acetate copolymer (sometimes referred to as "EVA" in this specification).

The release film 15 is not particularly limited and may be a known film.
In the first protective film-forming sheet 1 , the release film 15 is an optional configuration, and the first protective film-forming sheet 1 does not necessarily have to include the release film 15 .

The first protective film forming sheet of this embodiment is not limited to that shown in Figure 2, and some of the configuration may be changed, deleted, or added to that shown in Figure 2 within the scope that does not impair the effects of the present invention.
For example, the first protective film-forming sheet of this embodiment may further include another layer that does not fall under any of the first substrate, buffer layer, intermediate release layer, first protective film-forming film, and release film. However, in a first protective film-forming sheet that does not include a release film, it is preferable that the first protective film-forming film is one of the outermost layers, that is, the layer that is arranged outermost in the stacking direction of each layer. Furthermore, in the first protective film-forming sheet of this embodiment, it is preferable that the first substrate and buffer layer are provided in direct contact, the buffer layer and intermediate release layer are provided in direct contact, and the intermediate release layer and first protective film-forming film are provided in direct contact.
Next, each layer constituting the first protective film-forming sheet of this embodiment will be described.

First Protective Film-Forming Film The first protective film-forming film may be curable or non-curable. For example, the first protective film-forming film may function as the first protective film by being cured, or may function as the first protective film in an uncured state.
The curable first protective film-forming film may be either thermosetting or energy ray-curable, or may have both thermosetting and energy ray-curable properties.

The first protective film-forming film is preferably curable, as this allows for the formation of a first protective film with higher protective capabilities.

In this specification, "energy rays" refers to electromagnetic waves or charged particle beams that have an energy quantum. Examples of energy rays include ultraviolet rays, radioactive rays, and electron beams. Ultraviolet rays can be irradiated using, for example, a high-pressure mercury lamp, a fusion lamp, a xenon lamp, a black light, or an LED lamp as an ultraviolet light source. Electron beams can be irradiated using those generated by an electron beam accelerator or the like.
In addition, in this specification, "energy ray curable" means a property of being cured by irradiation with energy rays, and "non-energy ray curable" means a property of not being cured even when irradiated with energy rays.
Moreover, "non-curable" means a property that does not cure by any means such as heating or irradiation with energy rays.

The first protective film-forming film contains a resin component, and may or may not contain components other than the resin component.

The first protective film-forming film is soft and has high conformability to uneven surfaces such as the bump-forming surface of a semiconductor wafer. As a result, the first protective film-forming film and the first protective film exhibit high adhesion to uneven surfaces such as the bump-forming surface of a semiconductor wafer, and the first protective film exhibits high adhesion to uneven surfaces such as the bump-forming surface of a semiconductor chip.

When the first protective film-forming film in the first protective film-forming sheet of this embodiment is attached to the bump-forming surface of a semiconductor wafer while being heated, the bumps on the bump-forming surface penetrate the first protective film-forming film, causing the tops of the bumps to protrude from the first protective film-forming film. The softened first protective film-forming film then spreads between the bumps to cover them, adheres to the bump-forming surface, and covers the surfaces of the bumps, particularly the surfaces in the vicinity of the bump-forming surface, embedding the bases of the bumps. In this state, the first protective film-forming film is suppressed from remaining above the bumps. If the first protective film-forming film is curable, the first protective film-forming film in this state (with the bases of the bumps embedded) subsequently hardens to finally form the first protective film. If the first protective film-forming film is non-curable, the first protective film-forming film in this state (with the bases of the bumps embedded) functions as the first protective film. And, naturally, adhesion of the first protective film to the upper part of the bump is suppressed. In particular, when the first protective film-forming sheet of this embodiment is used, even if the first protective film-forming film in the first protective film-forming sheet is attached to the bump-forming surface of the semiconductor wafer at high speed, the tops of the bumps protrude from the first protective film-forming film, and the first protective film is suppressed from remaining and adhering to the upper part of the bump. The reason why the first protective film-forming sheet of this embodiment has such excellent properties is that the first protective film-forming sheet is configured by laminating a first base material, a buffer layer, an intermediate release layer, and a first protective film-forming film in this order, and the ratio (G _x '/G _A ') of the shear storage modulus of the intermediate release layer (G _x ') to the shear storage modulus of the buffer layer (G _A ') is less than 0.6.

Whether or not the first protective film-forming film remains above the bumps on the bump-forming surface, and whether or not the first protective film is attached, can be confirmed, for example, by obtaining scanning electron microscope (SEM) image data of the above the bumps.

Regardless of whether the first protective film-forming film is curable or non-curable, and if it is curable, regardless of whether it is heat-curable or energy ray-curable, the first protective film-forming film may consist of one layer (single layer) or two or more layers. When the first protective film-forming film consists of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited.

In this specification, not only in the case of the first protective film-forming film, "multiple layers may be the same or different from one another" means "all layers may be the same, all layers may be different, or only some layers may be the same," and further, "multiple layers are different from one another" means "at least one of the constituent materials and thicknesses of each layer is different from one another."

Regardless of whether the first protective film-forming film is curable or non-curable, and if it is curable, regardless of whether it is thermosetting or energy ray-curable, the thickness of the first protective film-forming film is preferably 1 to 200 μm, more preferably 10 to 150 μm, and particularly preferably 20 to 130 μm. When the thickness of the first protective film-forming film is equal to or greater than the lower limit, the effect of the first protective film-forming film is enhanced. For example, when a protective film is formed using the first protective film-forming film, a protective film with higher protective ability can be formed. When the thickness of the first protective film-forming film is equal to or less than the upper limit, the first protective film is prevented from becoming excessively thick.

As will be described later, when the first protective film is formed not only on the bump-forming surface of the semiconductor chip but also on the side surfaces thereof, it is necessary to use a semiconductor wafer having grooves formed on the bump-forming surface. In this way, when the first protective film is formed on the side surfaces of the semiconductor chip as well, in addition to the same reasons as above, the thickness of the first protective film-forming film is preferably 2 to 200 μm, more preferably 30 to 150 μm, and particularly preferably 30 to 130 μm, in order to be able to sufficiently fill the grooves with the first protective film-forming film.
On the other hand, when the first protective film is formed on the bump-forming surface of the semiconductor chip but not on the side surfaces, a semiconductor wafer having no grooves on the bump-forming surface may be used. In this case, for the same reasons as above (the effect of the first protective film-forming film is enhanced; the first protective film is prevented from becoming excessively thick), the thickness of the first protective film-forming film is preferably 1 to 100 μm, more preferably 20 to 75 μm, and particularly preferably 35 to 55 μm.

In this specification, the "thickness of the first protective film-forming film" refers to the overall thickness of the first protective film-forming film. For example, the thickness of a first protective film-forming film consisting of multiple layers refers to the total thickness of all layers that make up the first protective film-forming film.

In this specification, "thickness" does not apply only to the first protective film-forming film, and unless otherwise specified, refers to the average thickness measured at five randomly selected points on the object, and can be obtained using a constant pressure thickness gauge in accordance with JIS K7130.

<<First protective film forming composition>>
The first protective film-forming film can be formed using a first protective film-forming composition containing its constituent materials. For example, the first protective film-forming film can be formed by applying the first protective film-forming composition to the surface to be formed and drying it as necessary. The ratio of the contents of the components that do not vaporize at room temperature in the first protective film-forming composition is usually the same as the ratio of the contents of the components in the first protective film-forming film. In this specification, "room temperature" means a temperature that is not particularly cooled or heated, i.e., an ordinary temperature, and examples thereof include a temperature of 15 to 25°C.

The thermosetting first protective film-forming film can be formed using a thermosetting first protective film-forming composition, the energy ray-curable first protective film-forming film can be formed using an energy ray-curable first protective film-forming composition, and the non-curable first protective film-forming film can be formed using a non-curable first protective film-forming composition.
In this specification, when the first protective film-forming film has both thermosetting and energy ray-curable properties, if the contribution of thermosetting of the first protective film-forming film is greater than the contribution of energy ray-curing in forming the first protective film, the first protective film-forming film is treated as thermosetting. Conversely, if the contribution of energy ray-curing of the first protective film is greater than the contribution of thermosetting in forming the first protective film, the first protective film-forming film is treated as energy ray-curable.

In the first protective film-forming film, the ratio of the total content of one or more of the components described below contained in the first protective film to the total mass of the first protective film-forming film does not exceed 100 mass %.
Similarly, in the composition for forming the first protective film, the ratio of the total content of one or more of the components described below contained in the composition for forming the first protective film to the total mass of the composition for forming the first protective film does not exceed 100 mass%.

The first protective film-forming composition may be applied by a known method, such as using various coaters such as an air knife coater, blade coater, bar coater, gravure coater, roll coater, roll knife coater, curtain coater, die coater, knife coater, screen coater, Meyer bar coater, or kiss coater.

Regardless of whether the first protective film-forming film is curable or non-curable, and if it is curable, regardless of whether it is heat-curable or energy ray-curable, the drying conditions for the first protective film-forming composition are not particularly limited. However, if the first protective film-forming composition contains a solvent, as described below, it is preferably dried by heating. A solvent-containing first protective film-forming composition is preferably dried by heating, for example, at 70 to 130°C for 10 seconds to 5 minutes. However, a thermosetting first protective film-forming composition is preferably dried by heating so as not to thermally cure the composition itself or the thermosetting first protective film-forming film formed from this composition.

The thermosetting first protective film-forming film, energy ray-curable first protective film-forming film, and non-curable first protective film-forming film are described in further detail below.

Thermosetting First Protective Film-Forming Film Examples of the thermosetting first protective film-forming film include those containing a polymer component (A), a thermosetting component (B), a curing accelerator (C), a filler (D), and an additive (I).

The curing conditions for curing the thermosetting first protective film-forming film to form the first protective film are not particularly limited, as long as the first protective film is cured to a degree that allows it to fully perform its function, and can be selected appropriately depending on the type of thermosetting first protective film-forming film, etc.
For example, the heating temperature during thermal curing of the thermosetting first protective film-forming film is preferably 100 to 200° C., and may be, for example, any one of 110 to 170° C. and 120 to 150° C. The heating time during thermal curing is preferably 0.5 to 5 hours, and may be, for example, any one of 0.5 to 4 hours and 1 to 3 hours.

<Thermosetting first protective film forming composition>
Examples of the composition for forming a thermosetting first protective film include a composition for forming a thermosetting first protective film (III) (sometimes simply referred to in this specification as "composition (III)") containing a polymer component (A), a thermosetting component (B), a curing accelerator (C), a filler (D), and an additive (I).

[Polymer component (A)]
The polymer component (A) is a polymer compound for imparting film-forming properties, flexibility, etc. to the thermosetting first protective film-forming film. In this specification, the polymer compound also includes products of polycondensation reactions.

The polymer component (A) contained in composition (III) and the thermosetting first protective film-forming film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

Examples of the polymer component (A) include polyvinyl acetal, acrylic resin, urethane resin, phenoxy resin, silicone resin, saturated polyester resin, and the like.
Among these, the polymer component (A) is preferably polyvinyl acetal.

The polyvinyl acetal in the polymer component (A) may be any known polyvinyl acetal.
Of these, preferred polyvinyl acetals include, for example, polyvinyl formal and polyvinyl butyral, with polyvinyl butyral being more preferred.
Examples of polyvinyl butyral include those having structural units represented by the following formulas (i)-1, (i)-2 and (i)-3.

(In the formula, l, m, and n each independently represent an integer of 1 or more.)

The weight-average molecular weight (Mw) of the polyvinyl acetal is preferably 5,000 to 200,000, and more preferably 8,000 to 100,000. Having the weight-average molecular weight of the polyvinyl acetal in this range enhances the effect of suppressing the thermosetting first protective film-forming film from remaining on the top of the bumps when the thermosetting first protective film-forming film is attached to the bump-forming surface.

In this specification, unless otherwise specified, "weight average molecular weight" refers to a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

The glass transition temperature (Tg) of the polyvinyl acetal is preferably 40 to 80°C, and more preferably 50 to 70°C. Having the Tg of the polyvinyl acetal in this range increases the effect of suppressing the thermosetting first protective film-forming film from remaining on the top of the bumps when the thermosetting first protective film-forming film is attached to the bump-forming surface.

The ratio of the three or more monomers that make up the polyvinyl acetal can be selected arbitrarily.

The acrylic resin in the polymer component (A) may be any known acrylic polymer.
The weight average molecular weight (Mw) of the acrylic resin is preferably 5,000 to 1,000,000, and more preferably 8,000 to 800,000. When the weight average molecular weight of the acrylic resin is in such a range, the effect of suppressing the thermosetting first protective film-forming film from remaining on the top of the bumps when the thermosetting first protective film-forming film is attached to the bump-forming surface is enhanced.

The glass transition temperature (Tg) of the acrylic resin is preferably -50 to 70°C, and more preferably -30 to 60°C. Having the acrylic resin's Tg in this range increases the effect of suppressing the thermosetting first protective film-forming film from remaining on the top of the bumps when the thermosetting first protective film-forming film is attached to the bump-forming surface.

When an acrylic resin has two or more structural units, the glass transition temperature (Tg) of the acrylic resin can be calculated using the Fox equation. The Tg of the monomer from which the structural units are derived can be the value listed in the Polymer Data Handbook or the Adhesive Handbook.

The acrylic resin may be made up of one type of monomer, or two or more types; if two or more types are used, the combination and ratio of these can be selected arbitrarily.

Examples of acrylic resins include polymers of one or more (meth)acrylic acid esters;
A copolymer of two or more monomers selected from (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, N-methylolacrylamide, and the like;
Examples include copolymers of one or more (meth)acrylic acid esters with one or more monomers selected from (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, N-methylolacrylamide, and the like.

In this specification, the term "(meth)acrylic acid" encompasses both "acrylic acid" and "methacrylic acid." The same applies to terms similar to (meth)acrylic acid; for example, "(meth)acrylate" encompasses both "acrylate" and "methacrylate," and "(meth)acryloyl group" encompasses both "acryloyl group" and "methacryloyl group."

Examples of the (meth)acrylic acid ester constituting the acrylic resin include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, p) (meth)acrylic acid alkyl esters in which the alkyl group constituting the alkyl ester has a chain structure and has 1 to 18 carbon atoms, such as isononyl acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (palmityl (meth)acrylate), heptadecyl (meth)acrylate, and octadecyl (meth)acrylate (stearyl (meth)acrylate);
(meth)acrylic acid cycloalkyl esters such as isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate;
(Meth)acrylic acid aralkyl esters such as benzyl (meth)acrylate;
(Meth)acrylic acid cycloalkenyl esters such as (meth)acrylic acid dicyclopentenyl ester;
(Meth)acrylic acid cycloalkenyloxyalkyl esters such as (meth)acrylic acid dicyclopentenyloxyethyl ester;
(Meth)acrylic acid imide;
glycidyl group-containing (meth)acrylic acid esters such as glycidyl (meth)acrylate;
hydroxyl group-containing (meth)acrylic acid esters such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate;
Examples include substituted amino group-containing (meth)acrylic acid esters such as N-methylaminoethyl (meth)acrylate. Here, the term "substituted amino group" refers to a group having a structure in which one or two hydrogen atoms of an amino group are substituted with a group other than a hydrogen atom.

The acrylic resin may have a functional group capable of bonding with other compounds, such as a vinyl group, a (meth)acryloyl group, an amino group, a hydroxyl group, a carboxy group, or an isocyanate group. The functional group of the acrylic resin may bond with other compounds via a crosslinking agent (F) described below, or may bond directly with other compounds without the crosslinking agent (F). Bonding of the acrylic resin with other compounds via the functional group tends to improve the reliability of, for example, a package obtained using the thermosetting first protective film-forming film.

In the composition (III), the ratio of the content of the polymer component (A) to the total content of all components other than the solvent is preferably 5 to 25 mass%, more preferably 5 to 15 mass%, regardless of the type of the polymer component (A).
This is equivalent to saying that the content ratio of polymer component (A) in the thermosetting first protective film-forming film to the total mass of the thermosetting first protective film-forming film is preferably 5 to 25 mass%, and more preferably 5 to 15 mass%, regardless of the type of polymer component (A).
This is based on the fact that in the process of removing the solvent from a solvent-containing resin composition to form a resin film, the amount of components other than the solvent usually does not change, and the content ratio of the components other than the solvent is the same between the resin composition and the resin film. Therefore, in this specification, not only in the case of the thermosetting first protective film-forming film, but also in the case of the resin film obtained by removing the solvent from the resin composition, the content of the components other than the solvent will be described only in the resin film.

Polymer component (A) may also be considered a thermosetting component (B). In this embodiment, when composition (III) contains components that fall under both polymer component (A) and thermosetting component (B), composition (III) is considered to contain polymer component (A) and thermosetting component (B).

[Thermosetting component (B)]
The thermosetting component (B) has thermosetting properties and is a component for thermally curing the thermosetting first protective film-forming film.

The thermosetting component (B) contained in composition (III) and the thermosetting first protective film-forming film may be one type or two or more types, and if there are two or more types, the combination and ratio thereof can be selected arbitrarily.

Examples of the thermosetting component (B) include epoxy-based thermosetting resins, thermosetting polyimide resins, and unsaturated polyester resins, with epoxy-based thermosetting resins being preferred.
In this specification, the term "thermosetting polyimide resin" is a general term for a polyimide precursor that forms a polyimide resin by thermal curing, and a thermosetting polyimide.

(epoxy thermosetting resin)
The epoxy thermosetting resin comprises an epoxy resin (B1) and a thermosetting agent (B2).
The epoxy-based thermosetting resin contained in composition (III) and the thermosetting first protective film-forming film may be one type only or two or more types, and if there are two or more types, the combination and ratio thereof can be selected arbitrarily.

Epoxy resin (B1)
Examples of the epoxy resin (B1) include known epoxy resins, such as bifunctional or higher functional epoxy compounds, including polyfunctional epoxy resins, biphenyl compounds, bisphenol A diglycidyl ether and its hydrogenated products, orthocresol novolac epoxy resins, dicyclopentadiene-type epoxy resins, biphenyl-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and phenylene skeleton-type epoxy resins.

The epoxy resin (B1) may be an epoxy resin having an unsaturated hydrocarbon group. Epoxy resins having an unsaturated hydrocarbon group have higher compatibility with acrylic resins than epoxy resins not having an unsaturated hydrocarbon group. Therefore, using an epoxy resin having an unsaturated hydrocarbon group tends to improve the reliability of a package obtained using, for example, the thermosetting first protective film-forming film.

Examples of epoxy resins having unsaturated hydrocarbon groups include compounds having a structure in which some of the epoxy groups of a polyfunctional epoxy resin are converted to groups having unsaturated hydrocarbon groups. Such compounds can be obtained, for example, by subjecting epoxy groups to an addition reaction with (meth)acrylic acid or a derivative thereof.
Furthermore, examples of epoxy resins having an unsaturated hydrocarbon group include compounds having a structure in which a group having an unsaturated hydrocarbon group is directly bonded to an aromatic ring or the like constituting the epoxy resin.
The unsaturated hydrocarbon group is a polymerizable unsaturated group, and specific examples thereof include an ethenyl group (vinyl group), a 2-propenyl group (allyl group), a (meth)acryloyl group, and a (meth)acrylamide group, with an acryloyl group being preferred.

The number average molecular weight of the epoxy resin (B1) is not particularly limited, but from the viewpoints of the curability of the thermosetting first protective film-forming film and the strength and heat resistance of the cured product of the thermosetting first protective film-forming film (e.g., the first protective film), it is preferably 300 to 30,000, more preferably 400 to 10,000, and particularly preferably 500 to 3,000.
The epoxy equivalent of the epoxy resin (B1) is preferably 100 to 1000 g/eq, more preferably 200 to 800 g/eq.

Epoxy resin (B1) may be used alone or in combination of two or more types. When two or more types are used in combination, the combination and ratio thereof can be selected arbitrarily.

Heat curing agent (B2)
The heat curing agent (B2) functions as a curing agent for the epoxy resin (B1).
The thermosetting agent (B2) may be, for example, a compound having two or more functional groups capable of reacting with an epoxy group in one molecule. Examples of the functional group include a phenolic hydroxyl group, an alcoholic hydroxyl group, an amino group, a carboxyl group, and an anhydride group of an acid group. A phenolic hydroxyl group, an amino group, or an anhydride group of an acid group is preferred, and a phenolic hydroxyl group or an amino group is more preferred.

Among the heat curing agents (B2), examples of phenolic curing agents having a phenolic hydroxyl group include polyfunctional phenolic resins, biphenols, novolac-type phenolic resins, dicyclopentadiene-type phenolic resins, and aralkyl-type phenolic resins.
Among the heat curing agents (B2), examples of amine-based curing agents having an amino group include dicyandiamide (hereinafter sometimes abbreviated as "DICY").

The heat curing agent (B2) may have an unsaturated hydrocarbon group.
Examples of the thermosetting agent (B2) having an unsaturated hydrocarbon group include a compound having a structure in which some of the hydroxyl groups of a phenolic resin are substituted with a group having an unsaturated hydrocarbon group, and a compound having a structure in which a group having an unsaturated hydrocarbon group is directly bonded to an aromatic ring of a phenolic resin.
The unsaturated hydrocarbon group in the heat curing agent (B2) is the same as the unsaturated hydrocarbon group in the epoxy resin having an unsaturated hydrocarbon group described above.

Of the thermosetting agents (B2), for example, the number average molecular weight of resin components such as polyfunctional phenolic resins, novolac-type phenolic resins, dicyclopentadiene-type phenolic resins, and aralkyl-type phenolic resins is preferably 300 to 30,000, more preferably 400 to 10,000, and particularly preferably 500 to 3,000.
Of the thermosetting agents (B2), the molecular weight of the non-resin components such as biphenol and dicyandiamide is not particularly limited, but is preferably 60 to 500, for example.

Thermal curing agents (B2) may be used singly or in combination of two or more types. When two or more types are used in combination, the combination and ratio thereof can be selected arbitrarily.

The content of the thermosetting agent (B2) in the thermosetting first protective film-forming film is preferably 0.1 to 500 parts by mass, more preferably 1 to 200 parts by mass, per 100 parts by mass of the epoxy resin (B1), and may be, for example, any of 5 to 150 parts by mass, 10 to 100 parts by mass, and 15 to 75 parts by mass. When the content of the thermosetting agent (B2) is equal to or greater than the lower limit, curing of the thermosetting first protective film-forming film proceeds more easily. When the content of the thermosetting agent (B2) is equal to or less than the upper limit, the moisture absorption rate of the thermosetting first protective film-forming film is reduced, thereby further improving the reliability of, for example, a package obtained using the thermosetting first protective film-forming film.

The content of the thermosetting component (B) in the thermosetting first protective film-forming film (for example, the total content of the epoxy resin (B1) and the thermosetting agent (B2)) is preferably 600 to 1000 parts by mass per 100 parts by mass of the content of the polymer component (A). When the content of the thermosetting component (B) is in this range, when the thermosetting first protective film-forming film is attached to the bump-forming surface, the effect of suppressing the thermosetting first protective film-forming film from remaining on the bumps is enhanced, and a hard first protective film can be formed.
Furthermore, in order to obtain such effects more significantly, the content of the thermosetting component (B) may be appropriately adjusted depending on the type of the polymer component (A).

For example, when the polymer component (A) is the polyvinyl acetal, the content of the thermosetting component (B) in the thermosetting first protective film-forming film is preferably 600 to 1,000 parts by mass, more preferably 600 to 900 parts by mass, and even more preferably 600 to 800 parts by mass, per 100 parts by mass of the polymer component (A).

[Curing accelerator (C)]
The curing accelerator (C) is a component for adjusting the curing rate of the composition (III).
Preferred curing accelerators (C) include, for example, tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles (imidazoles in which one or more hydrogen atoms are substituted with groups other than hydrogen atoms) such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole; organic phosphines (phosphines in which one or more hydrogen atoms are substituted with organic groups) such as tributylphosphine, diphenylphosphine, and triphenylphosphine; and tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate.

The curing accelerator (C) contained in the composition (III) and the thermosetting first protective film-forming film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

The content of the curing accelerator (C) in the thermosetting first protective film-forming film is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the thermosetting component (B). When the content of the curing accelerator (C) is at least the lower limit, the effects of using the curing accelerator (C) are more pronounced. When the content of the curing accelerator (C) is at most the upper limit, for example, the effect of suppressing the highly polar curing accelerator (C) from migrating and segregating to the adhesive interface with the adherend under high temperature and high humidity conditions is enhanced, thereby further improving the reliability of packages obtained using the thermosetting first protective film-forming film, for example.

[Filler (D)]
By adjusting the amounts of the composition (III) and the filler (D) in the thermosetting first protective film-forming film, the effect of suppressing the thermosetting first protective film-forming film from remaining on the bumps when the thermosetting first protective film-forming film is attached to the bump-forming surface can be adjusted. Furthermore, the thermal expansion coefficient of the cured product of the thermosetting first protective film-forming film (e.g., the first protective film) can be more easily adjusted. For example, by optimizing the thermal expansion coefficient of the first protective film for the object on which the first protective film is formed, the reliability of the package obtained using the thermosetting first protective film-forming film can be further improved. Furthermore, as described below, in order to form the first protective film not only on the bump-forming surface of the semiconductor chip but also on the side surfaces, the degree of filling of the first protective film into grooves provided on the bump-forming surface of the semiconductor wafer can be adjusted. In addition, by using a thermosetting first protective film-forming film containing filler (D), it is possible to reduce the moisture absorption rate of the cured product of the thermosetting first protective film-forming film (e.g., the first protective film) and improve the heat dissipation properties.

The filler (D) may be either an organic filler or an inorganic filler, but is preferably an inorganic filler.
Preferred inorganic fillers include, for example, powders of silica, alumina, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, boron nitride, and the like; beads obtained by spheronizing these inorganic fillers; surface-modified products of these inorganic fillers; single-crystal fibers of these inorganic fillers; and glass fibers.
Among these, the inorganic filler is preferably silica or alumina.

The filler (D) contained in the composition (III) and the thermosetting first protective film-forming film may be one type or two or more types, and if there are two or more types, the combination and ratio thereof can be selected arbitrarily.

The content of the filler (D) in the thermosetting first protective film-forming film relative to the total mass of the thermosetting first protective film-forming film is preferably 5 to 45 mass%, more preferably 5 to 40 mass%, and even more preferably 5 to 30 mass%. By having this range of content, when the thermosetting first protective film-forming film is attached to the bump-forming surface, the effect of suppressing the thermosetting first protective film-forming film from remaining on the bumps is enhanced, and the thermal expansion coefficient can be more easily adjusted. Furthermore, the resin can be prevented from seeping out of the wafer during attachment.

[Additive (I)]
By adjusting the type or amount of additive (I) in composition (III) and the thermosetting first protective film-forming film, the effect of suppressing the thermosetting first protective film-forming film from remaining on top of the bump when the thermosetting first protective film-forming film is attached to the bump-forming surface can be adjusted.
Among these, examples of the additive (I) that are preferable in terms of having a higher effect of suppressing the remaining of the thermosetting first protective film-forming film include rheology control agents, surfactants, silicone oils, etc.

More specifically, examples of the rheology control agent include polyhydroxycarboxylic acid esters, polycarboxylic acids, and polyamide resins.
Examples of the surfactant include modified siloxane and acrylic polymer.
Examples of the silicone oil include aralkyl-modified silicone oil and modified polydimethylsiloxane, and examples of the modifying group include aralkyl groups; polar groups such as hydroxy groups; and groups having an unsaturated bond such as vinyl groups and phenyl groups.

Additives (I) other than those mentioned above may also include various other general-purpose additives such as plasticizers, antistatic agents, antioxidants, gettering agents, ultraviolet absorbers, and tackifiers.

The additive (I) contained in the composition (III) and the thermosetting first protective film-forming film may be one type only, or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

The content of the additive (I) in the composition (III) and the thermosetting first protective film-forming film is not particularly limited, and can be adjusted appropriately depending on the type and purpose.
For example, when the purpose is to adjust the effect of suppressing the remaining of the above-mentioned thermosetting first protective film-forming film, the content ratio of additive (I) in the thermosetting first protective film-forming film relative to the total mass of the thermosetting first protective film-forming film is preferably 0.5 to 10 mass%, more preferably 0.5 to 7 mass%, and even more preferably 0.5 to 5 mass%.

[Coupling agent (E)]
The composition (III) and the thermosetting first protective film-forming film may contain a coupling agent (E). By using a coupling agent (E) having a functional group capable of reacting with an inorganic compound or an organic compound, the adhesiveness and adhesion of the thermosetting first protective film-forming film to an adherend can be improved. Furthermore, by using the coupling agent (E), the water resistance of the cured product of the thermosetting first protective film-forming film (e.g., the first protective film) is improved without impairing the heat resistance.

The coupling agent (E) is preferably a compound having a functional group capable of reacting with the functional group of the polymer component (A), the thermosetting component (B), etc., and is more preferably a silane coupling agent.
Preferred examples of the silane coupling agent include 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxymethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2- Examples thereof include bis(3-(aminoethylamino)propylmethyldiethoxysilane, 3-(phenylamino)propyltrimethoxysilane, 3-anilinopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(3-triethoxysilylpropyl)tetrasulfane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, and imidazole silane.

The coupling agent (E) contained in composition (III) and the thermosetting first protective film-forming film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

When a coupling agent (E) is used, the content of the coupling agent (E) in the thermosetting first protective film-forming film may be, for example, 0.03 to 20 parts by mass per 100 parts by mass of the total content of the polymer component (A) and the thermosetting component (B). When the content of the coupling agent (E) is at or above the lower limit, the effects of using the coupling agent (E), such as improved dispersibility of the filler (D) in the resin and improved adhesion of the thermosetting first protective film-forming film to the adherend, are more significantly obtained. When the content of the coupling agent (E) is at or below the upper limit, the generation of outgassing is further suppressed.

[Crosslinking agent (F)]
When the polymer component (A) has a functional group such as a vinyl group, (meth)acryloyl group, amino group, hydroxyl group, carboxy group, or isocyanate group that can bond with other compounds, the composition (III) and the thermosetting first protective film-forming film may contain a crosslinking agent (F). The crosslinking agent (F) is a component that bonds the functional group in the polymer component (A) with other compounds to crosslink the functional group, and by crosslinking in this manner, the initial adhesive strength and cohesive strength of the thermosetting first protective film-forming film can be adjusted.

Examples of the crosslinking agent (F) include organic polyvalent isocyanate compounds, organic polyvalent imine compounds, metal chelate crosslinking agents (crosslinking agents having a metal chelate structure), and aziridine crosslinking agents (crosslinking agents having an aziridinyl group).

Examples of the organic polyisocyanate compounds include aromatic polyisocyanate compounds, aliphatic polyisocyanate compounds, and alicyclic polyisocyanate compounds (hereinafter, these compounds may be collectively referred to as "aromatic polyisocyanate compounds, etc."); trimers, isocyanurates, and adducts of the aromatic polyisocyanate compounds; and isocyanate-terminated urethane prepolymers, which are reaction products of the aromatic polyisocyanate compounds, etc., with polyol compounds. The "adduct" refers to the reaction product of the aromatic polyisocyanate compound, aliphatic polyisocyanate compound, or alicyclic polyisocyanate compound with a low-molecular-weight active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, or castor oil. Examples of the adducts include the xylylene diisocyanate adduct of trimethylolpropane, as described below. In this specification, "isocyanate-terminated urethane prepolymer" refers to a prepolymer that has urethane bonds and an isocyanate group at the end of the molecule.

Specific examples of the organic polyisocyanate compound include 2,4-tolylene diisocyanate; 2,6-tolylene diisocyanate; 1,3-xylylene diisocyanate; 1,4-xylylene diisocyanate; diphenylmethane-4,4'-diisocyanate; diphenylmethane-2,4'-diisocyanate; 3-methyldiphenylmethane diisocyanate; hexamethylene diisocyanate; isophorone diisocyanate; dicyclohexylmethane-4,4'-diisocyanate; dicyclohexylmethane-2,4'-diisocyanate; compounds in which one or more of tolylene diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are added to all or some of the hydroxyl groups of a polyol such as trimethylolpropane; and lysine diisocyanate.

Examples of the organic polyvalent imine compound include N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, and N,N'-toluene-2,4-bis(1-aziridinecarboxamide)triethylenemelamine.

When an organic polyisocyanate compound is used as the crosslinking agent (F), it is preferable to use a hydroxyl group-containing polymer as the polymer component (A). When the crosslinking agent (F) has an isocyanate group and the polymer component (A) has a hydroxyl group, a crosslinked structure can be easily introduced into the thermosetting first protective film-forming film by the reaction between the crosslinking agent (F) and the polymer component (A).

The crosslinking agent (F) contained in the composition (III) and the thermosetting first protective film-forming film may be one type or two or more types, and if there are two or more types, the combination and ratio thereof can be selected arbitrarily.

When crosslinking agent (F) is used, the content of crosslinking agent (F) in composition (III) may be, for example, 0.01 to 20 parts by mass per 100 parts by mass of polymer component (A). When the content of crosslinking agent (F) is equal to or greater than the lower limit, the effect of using crosslinking agent (F) is more pronounced. When the content of crosslinking agent (F) is equal to or less than the upper limit, excessive use of crosslinking agent (F) is suppressed.

[Other ingredients]
The composition (III) and the thermosetting first protective film-forming film may contain other components that do not fall under any of the above-mentioned polymer component (A), thermosetting component (B), curing accelerator (C), filler (D), additive (I), coupling agent (E), and crosslinking agent (F), within a range that does not impair the effects of the present invention.
Examples of the other components include an energy ray curable resin and a photopolymerization initiator.

The other components contained in composition (III) and the thermosetting first protective film-forming film may be one type only or two or more types, and if there are two or more types, their combination and ratio can be selected arbitrarily.
The contents of the composition (III) and the other components in the thermosetting first protective film-forming film are not particularly limited and may be appropriately selected depending on the purpose.

[solvent]
Composition (III) preferably further contains a solvent, since composition (III) containing a solvent has good handleability.
The solvent is not particularly limited, but preferred examples include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutyl alcohol (2-methylpropan-1-ol), and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; and amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone.
The composition (III) may contain only one type of solvent, or two or more types of solvents. When two or more types of solvents are contained, the combination and ratio thereof can be selected arbitrarily.

A more preferred example of a solvent contained in composition (III) is methyl ethyl ketone, etc., as this allows the components contained in composition (III) to be mixed more uniformly.

The solvent content of composition (III) is not particularly limited and may be selected appropriately depending on, for example, the types of components other than the solvent.

An example of a preferred thermosetting first protective film-forming film, in terms of further enhancing the intended effects of the present invention (high-speed application ability of the first protective film-forming sheet described below and penetration ability of the first protective film-forming film), is one that contains a polymer component (A), a thermosetting component (B), a curing accelerator (C), a filler (D), and an additive (I), and in which the ratio of the total content of the polymer component (A), the thermosetting component (B), the curing accelerator (C), the filler (D), and the additive (I) relative to the total mass of the thermosetting first protective film-forming film is 85 mass% or more, preferably 90 mass% or more, and more preferably 95 mass% or more.
In view of the above, an example of a more preferred thermosetting first protective film-forming film is one that contains a polymer component (A), a thermosetting component (B), a curing accelerator (C), a filler (D), and an additive (I), wherein the polymer component (A) is polyvinyl acetal, the thermosetting component (B) is an epoxy resin (B1) and a thermosetting agent (B2), and the additive (I) is one or more selected from the group consisting of a rheology control agent, a surfactant, and a silicone oil, and the ratio of the total content of the polymer component (A), the thermosetting component (B), the curing accelerator (C), the filler (D), and the additive (I) to the total mass of the thermosetting first protective film-forming film in the thermosetting first protective film-forming film is 85 mass% or more, preferably 90 mass% or more, and more preferably 95 mass% or more.
The thickness of these thermosetting first protective film-forming films is preferably 2 to 7 times, and more preferably 3 to 6 times, the thickness of the intermediate release layer.

<Method for producing thermosetting composition for forming first protective film>
The thermosetting composition for forming the first protective film, such as composition (III), can be obtained by blending the components that constitute it.
The order of addition of the components when blending is not particularly limited, and two or more components may be added simultaneously.
The method for mixing the components during blending is not particularly limited, and may be appropriately selected from known methods such as a method of mixing by rotating a stirrer or stirring blades, a method of mixing using a mixer, or a method of mixing by applying ultrasound.
The temperature and time for adding and mixing each component are not particularly limited as long as the components do not deteriorate, and may be adjusted appropriately. A temperature of 15 to 30°C is preferred.

Energy Ray-Curable First Protective Film-Forming Film Examples of the energy ray-curable first protective film-forming film include those containing an energy ray-curable component (a), a filler, and an additive.

The curing conditions when curing the energy ray-curable first protective film-forming film to form the first protective film are not particularly limited, as long as the degree of curing is such that the first protective film can fully exhibit its function, and may be selected appropriately depending on the type of energy ray-curable first protective film-forming film, etc.
For example, the illuminance of the energy ray during curing of the energy ray-curable first protective film-forming film is preferably 180 to 280 mW/cm ^2. The amount of light of the energy ray during the curing is preferably 450 to 1000 mJ/cm ² .

<Energy ray-curable composition for forming first protective film>
Examples of the energy ray-curable composition for forming a first protective film include an energy ray-curable composition for forming a first protective film (IV) (sometimes simply referred to as "composition (IV)" in this specification) containing an energy ray-curable component (a), a filler, and an additive.

[Energy ray-curable component (a)]
The energy ray-curable component (a) is a component that is cured by irradiation with energy rays, and is also a component that imparts film-forming properties, flexibility, and the like to the energy ray-curable first protective film-forming film.
The energy ray-curable component (a) is preferably uncured and has adhesive properties, and more preferably uncured and has adhesive properties.

Examples of the energy ray-curable component (a) include a polymer (a1) having an energy ray-curable group and a weight-average molecular weight of 80,000 to 2,000,000, and a compound (a2) having an energy ray-curable group and a molecular weight of 100 to 80,000. The polymer (a1) may be at least partially crosslinked with a crosslinking agent, or may not be crosslinked.

(Polymer (a1) having an energy ray-curable group and a weight-average molecular weight of 80,000 to 2,000,000)
Examples of the polymer (a1) having an energy ray-curable group and a weight average molecular weight of 80,000 to 2,000,000 include an acrylic resin (a1-1) having a structure obtained by polymerizing an acrylic polymer (a11) having a functional group capable of reacting with a group possessed by another compound, and an energy ray-curable compound (a12) having a group reactive with the functional group and an energy ray-curable group such as an energy ray-curable double bond.

Examples of the functional group capable of reacting with a group possessed by another compound include a hydroxyl group, a carboxy group, an amino group, a substituted amino group (a group having a structure in which one or two hydrogen atoms of an amino group are substituted with a group other than a hydrogen atom), an epoxy group, etc. However, from the viewpoint of preventing corrosion of circuits such as semiconductor wafers and semiconductor chips, it is preferable that the functional group be a group other than a carboxy group.
Among these, the functional group is preferably a hydroxyl group.

Acrylic polymer (a11) having a functional group
Examples of the acrylic polymer (a11) having a functional group include those having a structure in which an acrylic monomer having the functional group and an acrylic monomer not having the functional group are copolymerized, and the acrylic polymer (a11) may have a structure in which, in addition to these monomers, a monomer other than the acrylic monomer (non-acrylic monomer) is further copolymerized.
The acrylic polymer (a11) may be a random copolymer or a block copolymer.

Examples of acrylic monomers having the functional group include hydroxyl group-containing monomers, carboxy group-containing monomers, amino group-containing monomers, substituted amino group-containing monomers, and epoxy group-containing monomers.

Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and non-(meth)acrylic unsaturated alcohols (unsaturated alcohols without a (meth)acryloyl skeleton) such as vinyl alcohol and allyl alcohol.

Examples of the carboxy group-containing monomer include ethylenically unsaturated monocarboxylic acids (monocarboxylic acids having an ethylenically unsaturated bond) such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids (dicarboxylic acids having an ethylenically unsaturated bond) such as fumaric acid, itaconic acid, maleic acid, and citraconic acid; anhydrides of the above ethylenically unsaturated dicarboxylic acids; and (meth)acrylic acid carboxyalkyl esters such as 2-carboxyethyl methacrylate.

The acrylic monomer having the functional group is preferably a hydroxyl group-containing monomer or a carboxyl group-containing monomer, and more preferably a hydroxyl group-containing monomer.

The acrylic monomer having the functional group that constitutes the acrylic polymer (a11) may be of one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

Examples of acrylic monomers not having the functional group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, and isopropyl (meth)acrylate. Examples include alkyl (meth)acrylate esters in which the alkyl group constituting the alkyl ester has a chain structure containing 1 to 18 carbon atoms, such as Sononyl, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (palmityl (meth)acrylate), heptadecyl (meth)acrylate, and octadecyl (meth)acrylate (stearyl (meth)acrylate).

Examples of acrylic monomers that do not have a functional group include (meth)acrylic acid esters containing an alkoxyalkyl group, such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate; (meth)acrylic acid esters with an aromatic group, including aryl (meth)acrylate esters such as phenyl (meth)acrylate; non-crosslinkable (meth)acrylamide and derivatives thereof; and (meth)acrylic acid esters with a non-crosslinkable tertiary amino group, such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate.

The acrylic monomer not having a functional group that constitutes the acrylic polymer (a11) may be of one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

Examples of the non-acrylic monomer include olefins such as ethylene and norbornene; vinyl acetate; and styrene.
The non-acrylic monomer constituting the acrylic polymer (a11) may be of only one kind or of two or more kinds, and when two or more kinds are used, the combination and ratio thereof can be selected arbitrarily.

In the acrylic polymer (a11), the proportion (content) of the structural units derived from the acrylic monomer having the functional group relative to the total amount of structural units constituting the acrylic polymer (a11) is preferably 0.1 to 50% by mass, more preferably 1 to 40% by mass, and particularly preferably 3 to 30% by mass. When the proportion is within this range, the content of energy ray-curable groups in the acrylic resin (a1-1) obtained by copolymerization of the acrylic polymer (a11) and the energy ray-curable compound (a12) makes it possible to easily adjust the degree of curing of the cured product (e.g., the first protective film) of the energy ray-curable first protective film-forming film within a preferred range.

The acrylic polymer (a11) constituting the acrylic resin (a1-1) may be of only one type, or may be of two or more types. When two or more types are used, the combination and ratio thereof can be selected arbitrarily.

In the energy ray-curable first protective film-forming film, the content of acrylic resin (a1-1) relative to the total mass of the energy ray-curable first protective film-forming film is preferably 1 to 40 mass%, more preferably 2 to 30 mass%, and particularly preferably 3 to 20 mass%.

Energy ray-curable compound (a12)
The energy ray-curable compound (a12) preferably has one or more groups selected from the group consisting of an isocyanate group, an epoxy group, and a carboxy group as a group reactive with the functional group of the acrylic polymer (a11), and more preferably has an isocyanate group as the group. For example, when the energy ray-curable compound (a12) has an isocyanate group as the group, the isocyanate group easily reacts with the hydroxyl group of the acrylic polymer (a11) having a hydroxyl group as the functional group.

The energy ray-curable compound (a12) preferably has 1 to 5, and more preferably 1 to 2, energy ray-curable groups per molecule.

Examples of the energy ray-curable compound (a12) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, and 1,1-(bisacryloyloxymethyl)ethyl isocyanate;
an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate;
Examples of the isocyanate include an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with a polyol compound and hydroxyethyl (meth)acrylate.
Among these, the energy ray-curable compound (a12) is preferably 2-methacryloyloxyethyl isocyanate.

The energy ray-curable compound (a12) constituting the acrylic resin (a1-1) may be one type or two or more types. When two or more types are used, the combination and ratio thereof can be selected arbitrarily.

In the acrylic resin (a1-1), the ratio of the content of the energy ray-curable groups derived from the energy ray-curable compound (a12) to the content of the functional groups derived from the acrylic polymer (a11) is preferably 20 to 120 mol%, more preferably 35 to 100 mol%, and particularly preferably 50 to 100 mol%. When the content ratio is within this range, the adhesive strength of the cured product (e.g., the first protective film) of the energy ray-curable first protective film-forming film is increased. Note that when the energy ray-curable compound (a12) is a monofunctional compound (having one such group per molecule), the upper limit of the content ratio is 100 mol%. However, when the energy ray-curable compound (a12) is a polyfunctional compound (having two or more such groups per molecule), the upper limit of the content ratio may exceed 100 mol%.

The weight average molecular weight (Mw) of the polymer (a1) is preferably 100,000 to 2,000,000, and more preferably 300,000 to 1,500,000.

When the polymer (a1) is at least partially crosslinked with a crosslinking agent, the polymer (a1) may be formed by polymerizing a monomer that does not fall under any of the above-mentioned monomers described as constituting the acrylic polymer (a11) and has a group reactive with the crosslinking agent, and crosslinking the group reactive with the crosslinking agent; or the polymer (a1) may be formed by crosslinking a group reactive with the functional group derived from the energy ray-curable compound (a12).

The polymer (a1) contained in composition (IV) and the energy ray-curable first protective film-forming film may be one type or two or more types, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

(Compound (a2) having an energy ray-curable group and a molecular weight of 100 to 80,000)
[0047] Examples of the energy ray-curable group in the compound (a2) having an energy ray-curable group and having a molecular weight of 100 to 80,000 include groups containing an energy ray-curable double bond, and preferred examples thereof include a (meth)acryloyl group and a vinyl group.

The compound (a2) is not particularly limited as long as it satisfies the above conditions, but examples include low-molecular-weight compounds having energy ray-curable groups, epoxy resins having energy ray-curable groups, and phenolic resins having energy ray-curable groups.

Among the compounds (a2), examples of the low molecular weight compound having an energy ray-curable group include polyfunctional monomers or oligomers, and acrylate compounds having a (meth)acryloyl group are preferred.
Examples of the acrylate compounds include 2-hydroxy-3-(meth)acryloyloxypropyl methacrylate, polyethylene glycol di(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, 2,2-bis[4-((meth)acryloxypolyethoxy)phenyl]propane, ethoxylated bisphenol A di(meth)acrylate, 2,2-bis[4-((meth)acryloxydiethoxy)phenyl]propane, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene, 2,2-bis[4-((meth)acryloxypolypropoxy)phenyl]propane, tricyclodecane dimethanol di(meth)acrylate, 1,10-decanediol ... bifunctional (meth)acrylates such as 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 2,2-bis[4-((meth)acryloxyethoxy)phenyl]propane, neopentyl glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, and 2-hydroxy-1,3-di(meth)acryloxypropane;
polyfunctional (meth)acrylates such as tris(2-(meth)acryloxyethyl)isocyanurate, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate, ethoxylated glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol poly(meth)acrylate, and dipentaerythritol hexa(meth)acrylate;
Examples include polyfunctional (meth)acrylate oligomers such as urethane (meth)acrylate oligomers.

Of the compounds (a2), examples of epoxy resins having energy ray-curable groups and phenolic resins having energy ray-curable groups that can be used include those described in paragraph 0043 of JP 2013-194102 A. Such resins also fall under the category of resins that constitute the thermosetting component described below, but in this embodiment they are treated as compound (a2).

The weight-average molecular weight of the compound (a2) is preferably 100 to 30,000, and more preferably 300 to 10,000.

The compound (a2) contained in composition (IV) and the energy ray-curable first protective film-forming film may be one type or two or more types, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

[Polymer (b) having no energy ray-curable group]
When the composition (IV) and the energy ray-curable first protective film-forming film contain the compound (a2) as the energy ray-curable component (a), it is preferable that they also contain a polymer (b) that does not have an energy ray-curable group.
The polymer (b) may be at least partially crosslinked with a crosslinking agent, or may not be crosslinked.

Examples of the polymer (b) having no energy ray-curable group include acrylic polymers, phenoxy resins, urethane resins, polyesters, rubber-based resins, and acrylic urethane resins.
Among these, the polymer (b) is preferably an acrylic polymer (hereinafter sometimes abbreviated as "acrylic polymer (b-1)").

The acrylic polymer (b-1) may be a known polymer, for example, a homopolymer of one type of acrylic monomer, a copolymer of two or more types of acrylic monomers, or a copolymer of one or more types of acrylic monomers and one or more types of monomers other than acrylic monomers (non-acrylic monomers).

Examples of the acrylic monomer that constitutes the acrylic polymer (b-1) include (meth)acrylic acid alkyl esters, (meth)acrylic acid esters having a cyclic skeleton, glycidyl group-containing (meth)acrylic acid esters, hydroxyl group-containing (meth)acrylic acid esters, and substituted amino group-containing (meth)acrylic acid esters. Here, the term "substituted amino group" is as described above.

The (meth)acrylic acid alkyl ester can be, for example, the same as the acrylic monomer not having a functional group (e.g., a (meth)acrylic acid alkyl ester in which the alkyl group constituting the alkyl ester has a chain structure containing 1 to 18 carbon atoms) that constitutes the acrylic polymer (a11) described above.

Examples of the (meth)acrylic acid ester having a cyclic skeleton include (meth)acrylic acid cycloalkyl esters such as isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate;
(Meth)acrylic acid aralkyl esters such as benzyl (meth)acrylate;
(Meth)acrylic acid cycloalkenyl esters such as (meth)acrylic acid dicyclopentenyl ester;
(Meth)acrylic acid cycloalkenyloxyalkyl esters such as (meth)acrylic acid dicyclopentenyloxyethyl ester are exemplified.

Examples of the glycidyl group-containing (meth)acrylic acid ester include glycidyl (meth)acrylate.
Examples of the hydroxyl group-containing (meth)acrylic acid ester include hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.
Examples of the substituted amino group-containing (meth)acrylic acid ester include N-methylaminoethyl (meth)acrylate.

Examples of the non-acrylic monomer that constitutes the acrylic polymer (b-1) include olefins such as ethylene and norbornene; vinyl acetate; and styrene.

The polymer (b) having no energy ray-curable group and at least a portion of which is crosslinked with a crosslinking agent may be, for example, a polymer in which a reactive functional group in the polymer (b) has reacted with a crosslinking agent.
The reactive functional group may be appropriately selected depending on the type of crosslinking agent, and is not particularly limited. For example, when the crosslinking agent is a polyisocyanate compound, examples of the reactive functional group include a hydroxyl group, a carboxyl group, an amino group, etc., and among these, a hydroxyl group, which has high reactivity with an isocyanate group, is preferred. When the crosslinking agent is an epoxy compound, examples of the reactive functional group include a carboxyl group, an amino group, an amide group, etc., and among these, a carboxyl group, which has high reactivity with an epoxy group, is preferred. However, from the viewpoint of preventing corrosion of the circuits of a semiconductor wafer or a semiconductor chip, it is preferable that the reactive functional group be a group other than a carboxyl group.

Examples of the polymer (b) having a reactive functional group but no energy ray-curable group include those obtained by polymerizing at least a monomer having the reactive functional group. In the case of acrylic polymer (b-1), it is sufficient to use one or both of the acrylic monomers and non-acrylic monomers listed as constituent monomers that have the reactive functional group. Examples of the polymer (b) having a hydroxyl group as a reactive functional group include those obtained by polymerizing a hydroxyl group-containing (meth)acrylic acid ester, and also those obtained by polymerizing a monomer having a structure in which one or more hydrogen atoms in the acrylic monomers or non-acrylic monomers listed above are substituted with the reactive functional group.

In the polymer (b) having a reactive functional group, the proportion (content) of the structural units derived from the monomer having a reactive functional group relative to the total amount of structural units constituting the polymer (b) is preferably 1 to 20% by mass, and more preferably 2 to 10% by mass. Having this proportion within this range ensures that the degree of crosslinking in the polymer (b) falls within a more preferable range.

The weight-average molecular weight (Mw) of polymer (b) not having an energy ray-curable group is preferably 10,000 to 2,000,000, and more preferably 100,000 to 1,500,000, in order to improve the film-forming properties of composition (IV).

The polymer (b) not having an energy ray-curable group contained in composition (IV) and the energy ray-curable first protective film-forming film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

Examples of composition (IV) include compositions containing either or both of the polymer (a1) and the compound (a2). When composition (IV) contains compound (a2), it preferably also contains polymer (b) that does not have an energy ray-curable group, and in this case, it is also preferable that composition (IV) further contains (a1). Alternatively, composition (IV) may not contain compound (a2), but may contain both polymer (a1) and polymer (b) that does not have an energy ray-curable group.

When composition (IV) contains the polymer (a1), the compound (a2), and the polymer (b) that does not have an energy ray-curable group, the content of the compound (a2) in composition (IV) is preferably 10 to 400 parts by mass, and more preferably 30 to 350 parts by mass, per 100 parts by mass of the total content of the polymer (a1) and the polymer (b) that does not have an energy ray-curable group.

In the energy ray-curable first protective film-forming film, the ratio of the total content of the energy ray-curable component (a) and the polymer (b) not having an energy ray-curable group to the total mass of the energy ray-curable first protective film-forming film is preferably 5 to 90 mass%, more preferably 10 to 80 mass%, and particularly preferably 20 to 70 mass%. Having this ratio within this range improves the energy ray curability of the energy ray-curable first protective film-forming film.

[Filling material]
By adjusting the amount of the filler in the composition (IV) and the energy ray-curable first protective film-forming film, when the energy ray-curable first protective film-forming film is attached to the bump-forming surface, the effect of suppressing the energy ray-curable first protective film-forming film from remaining on the top of the bumps can be adjusted. Furthermore, the thermal expansion coefficient of the cured product of the energy ray-curable first protective film-forming film (e.g., the first protective film) can be more easily adjusted. For example, by optimizing the thermal expansion coefficient of the first protective film for the object on which the first protective film is formed, the reliability of the package obtained using the energy ray-curable first protective film-forming film can be further improved. Furthermore, as described below, in order to form the first protective film not only on the bump-forming surface of the semiconductor chip but also on the side surfaces, when the first protective film is filled into grooves provided on the bump-forming surface of the semiconductor wafer, the degree of filling can be adjusted. Furthermore, by using an energy ray-curable first protective film-forming film containing a filler, it is possible to reduce the moisture absorption rate of the cured product of the energy ray-curable first protective film-forming film (e.g., the first protective film) and improve the heat dissipation properties.

The filler contained in composition (IV) and the energy ray-curable first protective film-forming film is the same as the filler (D) contained in composition (III) and the thermosetting first protective film-forming film described above.

The inclusion of the filler in composition (IV) and the energy ray-curable first protective film-forming film may be the same as the inclusion of filler (D) in composition (III) and the thermosetting first protective film-forming film.

The filler contained in composition (IV) and the energy ray-curable first protective film-forming film may be one type or two or more types, and if two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

The content of the filler in the energy ray-curable first protective film-forming film relative to the total mass of the energy ray-curable first protective film-forming film may be, for example, 5 to 45 mass %. By having this proportion within this range, when the energy ray-curable first protective film-forming film is attached to the bump-forming surface, the effect of suppressing the energy ray-curable first protective film from remaining on the top of the bumps is enhanced, and the thermal expansion coefficient can be more easily adjusted. Furthermore, as described below, when filling grooves provided on the bump-forming surface of the semiconductor wafer with the non-curable first protective film, the film can be sufficiently filled in order to form a first protective film not only on the bump-forming surface of the semiconductor chip but also on the side surfaces.

[Additives]
By adjusting the type or amount of additives in composition (IV) and the energy ray-curable first protective film-forming film, the effect of suppressing the energy ray-curable first protective film-forming film from remaining on the top of the bump when the energy ray-curable first protective film-forming film is attached to the bump-forming surface can be adjusted.

The additives contained in composition (IV) and the energy ray-curable first protective film-forming film are the same as the additives (I) contained in composition (III) and the heat-curable first protective film-forming film described above.
For example, preferred additives that can more easily adjust the effect of suppressing the remaining of the energy ray-curable first protective film-forming film include rheology control agents, surfactants, silicone oils, and the like.

The manner in which the additives are contained in composition (IV) and the energy ray-curable first protective film-forming film may be the same as the manner in which the additive (I) is contained in composition (III) and the thermosetting first protective film-forming film.

The additives contained in composition (IV) and the energy ray-curable first protective film-forming film may be one type only, or two or more types, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

The content of the additives in the composition (IV) and the energy ray-curable first protective film-forming film is not particularly limited, and can be adjusted appropriately depending on the type and purpose.
For example, when the purpose is to adjust the effect of suppressing the remaining of the energy ray-curable first protective film-forming film, the content ratio of the additive in the energy ray-curable first protective film-forming film relative to the total mass of the energy ray-curable first protective film-forming film may be, for example, 0.5 to 10 mass%.

[Other ingredients]
The composition (IV) and the energy ray-curable first protective film-forming film may contain other components that do not fall under any of the energy ray-curable component (a), the filler, the additive, and the polymer (b) that does not have an energy ray-curable group, within a range that does not impair the effects of the present invention.
Examples of the other components include a thermosetting component, a photopolymerization initiator, a coupling agent, a crosslinking agent, etc. For example, by using composition (IV) containing the energy ray-curable component (a) and the thermosetting component, the adhesive strength of the energy ray-curable first protective film-forming film to an adherend is improved by heating, and the strength of the cured product of this energy ray-curable first protective film-forming film (e.g., the first protective film) is also improved.

The thermosetting component, photopolymerization initiator, coupling agent, and crosslinking agent in composition (IV) may be the same as the thermosetting component (B), photopolymerization initiator, coupling agent (E), and crosslinking agent (F) in composition (III), respectively.

The other components contained in composition (IV) and the energy ray-curable first protective film-forming film may be one type only or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.
The contents of the composition (IV) and the other components in the energy ray-curable first protective film-forming film are not particularly limited and may be appropriately selected depending on the purpose.

[solvent]
Composition (IV) preferably further contains a solvent, since composition (IV) containing a solvent has good handleability.
Examples of the solvent contained in the composition (IV) include the same solvents as those contained in the composition (III) described above.
The composition (IV) may contain only one type of solvent, or two or more types of solvents. When two or more types of solvents are contained, the combination and ratio thereof can be selected arbitrarily.
The content of the solvent in the composition (IV) is not particularly limited and may be appropriately selected depending on, for example, the types of components other than the solvent.

An example of a preferable energy ray-curable first protective film-forming film, in terms of further enhancing the intended effects of the present invention (high-speed application ability of the first protective film-forming sheet described below and penetration ability of the first protective film-forming film), is one that contains an energy ray-curable component (a), a filler, and an additive, and in which the ratio of the total content of the energy ray-curable component (a), the filler, and the additive to the total mass of the energy ray-curable first protective film-forming film in the energy ray-curable first protective film-forming film is 85 mass% or more, preferably 90 mass% or more, and more preferably 95 mass% or more.
In view of the above, a more preferable example of the energy ray-curable first protective film-forming film is a film containing an energy ray-curable component (a), a polymer (b) having no energy ray-curable group, a filler, and an additive, wherein the energy ray-curable component (a) is one or both of a polymer (a1) having an energy ray-curable group and having a weight average molecular weight of 80,000 to 2,000,000, and a compound (a2) having an energy ray-curable group and having a molecular weight of 100 to 80,000, and the polymer (b) having no energy ray-curable group is an acrylic polymer, a phenoxy resin, a urethane resin, a polyester, a rubber-based the additive is one or more selected from the group consisting of a rheology control agent, a surfactant, and a silicone oil; and in the energy ray-curable first protective film-forming film, the ratio of the total content of the energy ray-curable component (a), the polymer (b) having no energy ray-curable group, the filler, and the additive relative to the total mass of the energy ray-curable first protective film-forming film is 85 mass% or more, preferably 90 mass% or more, and more preferably 95 mass% or more.
The thickness of the energy ray-curable first protective film-forming film is preferably 2 to 7 times, and more preferably 3 to 6 times, the thickness of the intermediate release layer.

<Method for producing energy ray-curable composition for forming first protective film>
The energy ray-curable composition for forming the first protective film, such as composition (IV), can be obtained by blending the components constituting the composition.
The energy ray-curable composition for forming the first protective film can be produced by the same method as the heat-curable composition for forming the first protective film described above, except that the types of ingredients used are different.

Non-Curable First Protective Film-Forming Film Examples of the non-curable first protective film-forming film include those containing a thermoplastic resin, a filler, and an additive.

<Non-curable first protective film forming composition (V)>
Examples of the non-curable first protective film-forming composition include a non-curable first protective film-forming composition (V) (sometimes abbreviated in this specification as simply "composition (V)") containing a thermoplastic resin, a filler, and an additive.

[Thermoplastic resin]
The thermoplastic resin is not particularly limited.
More specifically, examples of the thermoplastic resin include the same non-curable resins as those listed as components contained in the composition (III) above, such as polyvinyl acetal, acrylic resin, urethane resin, phenoxy resin, silicone resin, and saturated polyester resin.

The thermoplastic resin contained in composition (V) and the non-curable first protective film-forming film may be one type or two or more types, and if there are two or more types, the combination and ratio thereof can be selected arbitrarily.

The content of the thermoplastic resin in the non-curable first protective film-forming film is preferably 25 to 75 mass% relative to the total mass of the non-curable first protective film-forming film.

[Filling material]
The non-curable first protective film-forming film containing the filler exhibits the same effects as the thermosetting first protective film-forming film containing the filler (D).

The filler contained in composition (V) and the non-curable first protective film-forming film may be the same as the filler (D) contained in composition (III) and the thermosetting first protective film-forming film.

The filler contained in composition (V) and the non-curable first protective film-forming film may be one type or two or more types, and if there are two or more types, the combination and ratio thereof can be selected arbitrarily.

The ratio of the filler content in the non-curable first protective film-forming film to the total mass of the non-curable first protective film-forming film is preferably 15 to 70 mass%. By having this ratio in this range, similar to when composition (III) is used, when the non-curable first protective film-forming film is attached to the bump-forming surface, the effect of suppressing the non-curable first protective film-forming film from remaining on the bumps is enhanced, and it becomes easier to adjust the thermal expansion coefficients of the non-curable first protective film-forming film and the first protective film.

[Additives]
By adjusting the type or amount of additives in composition (V) and the non-curable first protective film-forming film, the effect of suppressing the non-curable first protective film-forming film from remaining on top of the bump when the non-curable first protective film-forming film is attached to the bump-forming surface can be adjusted.

The additives contained in the composition (V) and the non-curable first protective film-forming film are the same as the additives (I) contained in the composition (III) and the thermosetting first protective film-forming film described above.
For example, preferred additives that can more easily adjust the effect of suppressing the remaining of the non-curable first protective film-forming film include rheology control agents, surfactants, silicone oils, and the like.

The manner in which the additives in composition (V) and the non-curable first protective film-forming film are contained may be the same as the manner in which the additive (I) in composition (III) and the thermosetting first protective film-forming film is contained.

The additives contained in composition (V) and the non-curable first protective film-forming film may be one type only, or two or more types, and if there are two or more types, the combination and ratio thereof can be selected arbitrarily.

The content of the additives in the composition (V) and the non-curable first protective film-forming film is not particularly limited, and can be adjusted appropriately depending on the type and purpose.
For example, when the purpose is to adjust the effect of suppressing the remaining of the above-mentioned non-curable first protective film-forming film, the ratio of the content of the additive in the non-curable first protective film-forming film to the total mass of the non-curable first protective film-forming film may be, for example, 0.5 to 10 mass%.

[Other ingredients]
Composition (V) and the non-curable first protective film-forming film may contain other components that do not fall under any of the thermoplastic resins, fillers, and additives, as long as the effects of the present invention are not impaired.
The other components are not particularly limited and can be selected arbitrarily depending on the purpose.

The other components contained in composition (V) and the non-curable first protective film-forming film may be one type only or two or more types, and if there are two or more types, their combination and ratio can be selected arbitrarily.
The contents of the composition (V) and the other components in the non-curable first protective film-forming film are not particularly limited and may be appropriately selected depending on the purpose.

[solvent]
The composition (V) preferably further contains a solvent, since the composition (V) containing a solvent has good handleability.
Examples of the solvent contained in the composition (V) include the same solvents as those contained in the composition (III) described above.
The composition (V) may contain only one type of solvent, or two or more types of solvents. When two or more types of solvents are contained, the combination and ratio thereof can be selected arbitrarily.
The content of the solvent in the composition (V) is not particularly limited and may be appropriately selected depending on, for example, the types of components other than the solvent.

An example of a preferred non-curable first protective film-forming film, in terms of further enhancing the intended effects of the present invention (high-speed application ability of the first protective film-forming sheet described below and penetration ability of the first protective film-forming film), is one that contains a thermoplastic resin, a filler, and an additive, and in which the ratio of the total content of the thermoplastic resin, the filler, and the additive to the total mass of the non-curable first protective film-forming film is 85% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass or more.
In view of the above, an example of a more preferred non-curable first protective film-forming film is one that contains a thermoplastic resin, a filler, and an additive, wherein the thermoplastic resin is one or more selected from the group consisting of polyvinyl acetal, acrylic resin, urethane resin, phenoxy resin, silicone resin, and saturated polyester resin, and the additive is one or more selected from the group consisting of rheology control agents, surfactants, and silicone oils, and the ratio of the total content of the thermoplastic resin, the filler, and the additive in the non-curable first protective film-forming film to the total mass of the non-curable first protective film-forming film is 85 mass% or more, preferably 90 mass% or more, and more preferably 95 mass% or more.
The thickness of these non-curable first protective film-forming films is preferably 2 to 7 times, and more preferably 3 to 6 times, the thickness of the intermediate release layer.

<Method for producing non-curable first protective film-forming composition>
The non-curable first protective film-forming composition such as composition (V) can be obtained by blending the components that constitute the composition.
The non-curable composition for forming the first protective film can be produced by the same method as the thermosetting composition for forming the first protective film described above, except that the types of ingredients used are different.

Intermediate release layer When the ratio (G _x '/G _A ') of the shear storage modulus (G _x ') of the intermediate release layer to the shear storage modulus (G _A ') of the buffer layer is less than 0.6, the bump embeddability of the first protective film-forming film is improved when the first protective film-forming sheet is attached to the bump-forming surface of the semiconductor wafer. This improves both the high-speed attachment ability of the first protective film-forming sheet to the bump-forming surface of the semiconductor wafer and the bump penetration ability of the first protective film-forming film.

Furthermore, the intermediate release layer preferably contains ethylene-vinyl acetate copolymer (EVA). By containing EVA, the bump embedding ability of the first protective film-forming film is improved when the first protective film-forming sheet is attached to the bump-forming surface of the semiconductor wafer. This enables high-speed attachment of the first protective film-forming sheet to the bump-forming surface of the semiconductor wafer. In this specification, the property that enables high-speed attachment of the first protective film-forming sheet is sometimes referred to as "high-speed attachment ability."
Furthermore, since the intermediate release layer contains EVA, the buffer layer strongly presses the first protective film-forming film when the first protective film-forming sheet is attached to the bump-forming surface of the semiconductor wafer. This makes it possible to protrude the tops of the bumps from the first protective film-forming film, even when the first protective film-forming sheet is attached at high speed, and further suppress the first protective film-forming film from remaining above the bumps. In this specification, the property of the first protective film-forming film in the first protective film-forming sheet, which suppresses the first protective film-forming film from remaining above the bumps and makes it easy for the tops of the bumps to protrude, is sometimes referred to as "penetrability."
Because EVA has the property of softening moderately when heated, these effects, i.e., the effect that the first protective film-forming sheet has high-speed application ability and the first protective film-forming film has penetrability, are particularly pronounced when the first protective film-forming sheet is applied while being heated.

The first protective film-forming sheet of this embodiment is provided with an intermediate release layer, thereby exhibiting the above-mentioned excellent effects regardless of the type of first protective film-forming film.

The intermediate release layer preferably contains ethylene-vinyl acetate copolymer (EVA), and may contain only ethylene-vinyl acetate copolymer (in other words, it may be a layer made of ethylene-vinyl acetate copolymer), or it may contain ethylene-vinyl acetate copolymer and other components.

The intermediate release layer is in sheet or film form.

The intermediate release layer may be a single layer (single layer), or may be two or more layers. If there are multiple layers, these layers may be the same or different from each other, and there are no particular limitations on the combination of these layers.

The thickness of the intermediate release layer is preferably 5 to 30 μm, more preferably 6 to 25 μm, and particularly preferably 7 to 20 μm.
Here, "thickness of intermediate release layer" means the thickness of the entire intermediate release layer; for example, the thickness of an intermediate release layer consisting of multiple layers means the total thickness of all layers that make up the intermediate release layer.

<<Composition for forming intermediate release layer>>
The intermediate release layer can be formed using a composition for forming an intermediate release layer containing its constituent materials. For example, the intermediate release layer can be formed by applying the composition for forming an intermediate release layer to the surface on which the intermediate release layer is to be formed and drying it as necessary. A more specific method for forming the intermediate release layer will be described in detail later, along with methods for forming other layers. The ratio of the contents of the components that do not vaporize at room temperature in the composition for forming an intermediate release layer is usually the same as the ratio of the contents of the components in the intermediate release layer.

The composition of the intermediate release layer is not limited as long as it can be adjusted so that the ratio (G _x '/G _A ') is less than 0.6. In the intermediate release layer, the ratio of the total content of one or more components described below contained in the intermediate release layer to the total mass of the intermediate release layer does not exceed 100 mass%.
Similarly, in the composition for forming an intermediate release layer, the ratio of the total content of one or more of the components contained in the composition for forming an intermediate release layer, as described below, to the total mass of the composition for forming an intermediate release layer does not exceed 100 mass%.

The composition for forming the intermediate release layer can be applied in the same manner as the composition for forming the first protective film described above.
The drying conditions for the intermediate release layer-forming composition are not particularly limited. However, when the intermediate release layer-forming composition contains a solvent described below, it is preferable to heat-dry it. The solvent-containing intermediate release layer-forming composition is preferably heat-dried, for example, at 70 to 130°C for 10 seconds to 5 minutes.

<Composition for forming intermediate release layer (VII)>
Examples of compositions for forming intermediate release layers include composition (VII) for forming intermediate release layers containing ethylene-vinyl acetate copolymer (EVA) (sometimes referred to simply as "composition (VII)" in this specification).
The composition (VII) may contain an ethylene-vinyl acetate copolymer and other components.

In the ethylene-vinyl acetate copolymer, the ratio of the amount (parts by mass) of structural units derived from vinyl acetate to the total amount (parts by mass) of structural units (the total amount of all structural units constituting the ethylene-vinyl acetate copolymer; the same applies hereinafter) ([amount (parts by mass) of structural units derived from vinyl acetate constituting the ethylene-vinyl acetate copolymer]/[total amount (parts by mass) of all structural units constituting the ethylene-vinyl acetate copolymer]×100) is preferably 40% by mass or less, more preferably 37% by mass or less, and even more preferably 34% by mass or less, and may be, for example, either 30% by mass or less or 25% by mass or less. When this ratio is equal to or less than the upper limit, the handleability of composition (VII) is further improved, the shear storage modulus (G _x ') of the intermediate release layer can be adjusted to a smaller value, the ratio (G _x '/G _A ') can be adjusted to a smaller value, and the high-speed application ability of the first protective film-forming sheet and the penetrability of the first protective film-forming film are further improved.
In this specification, the ratio of the amount (parts by mass) of structural units derived from vinyl acetate to the total amount (parts by mass) of structural units in an ethylene-vinyl acetate copolymer is sometimes referred to as the "VA content."

In the ethylene-vinyl acetate copolymer, the ratio (VA content) of the amount (parts by mass) of structural units derived from vinyl acetate to the total amount (parts by mass) of structural units is preferably 40% by mass or less, more preferably 37% by mass or less, and even more preferably 34% by mass or less, and may be, for example, either 30% by mass or less or 25% by mass or less. Having this ratio below the upper limit further improves the handleability of composition (VII), making it easier to form the first protective film-forming film.

In an ethylene-vinyl acetate copolymer, the ratio of the amount (parts by mass) of structural units derived from vinyl acetate to the total amount (parts by mass) of structural units (VA content) can be adjusted appropriately within a range set by arbitrarily combining any of the above-mentioned lower limit values with any of the above-mentioned upper limit values. For example, the ratio is preferably 16 to 40% by mass, more preferably 17.5 to 37% by mass, and even more preferably 19 to 34% by mass. For example, it may be either 25 to 34% by mass or 30 to 34% by mass, or either 19 to 30% by mass or 19 to 25% by mass. However, these are just examples of the above-mentioned ratios.

The weight-average molecular weight of the ethylene-vinyl acetate copolymer is preferably 200,000 or less, more preferably 180,000 or less, and even more preferably 160,000 or less, and may be, for example, 100,000 or less or 60,000 or less. Having the weight-average molecular weight below the upper limit improves the high-speed application ability of the first protective film-forming sheet and the penetration ability of the first protective film-forming film.

The lower limit of the weight-average molecular weight of the ethylene-vinyl acetate copolymer is not particularly limited. For example, the weight-average molecular weight may be 5,000 or more, in order to improve the film-forming properties of composition (VII).

The weight-average molecular weight of the ethylene-vinyl acetate copolymer may be, for example, 5,000 to 200,000, 5,000 to 180,000, 5,000 to 160,000, 5,000 to 100,000, or 5,000 to 60,000. However, these are just examples of the weight-average molecular weight.

The ethylene-vinyl acetate copolymer is preferably the main component of the intermediate release layer, which improves the high-speed application property of the first protective film-forming sheet and the penetration property of the first protective film-forming film.
In particular, the ratio of the ethylene-vinyl acetate copolymer content in the intermediate release layer to the total mass of the intermediate release layer ([ethylene-vinyl acetate copolymer content (parts by mass) of intermediate release layer]/[total mass (parts by mass) of intermediate release layer]×100) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, any of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When the ratio is equal to or greater than the lower limit, the high-speed application ability of the first protective film-forming sheet and the penetration ability of the first protective film-forming film are further improved.
The proportion is 100% by mass or less.

[Other ingredients]
The other components contained in the composition (VII) and the intermediate release layer are not particularly limited and can be appropriately selected depending on the purpose.

The other components contained in composition (VII) and the intermediate release layer may be one type only, or two or more types. If there are two or more types, the combination and ratio of these can be selected arbitrarily.

Examples of the other components contained in composition (VII) and the intermediate release layer include non-polar resins such as ethylene polymers.
The ethylene-based polymer is a polymer having at least a structural unit derived from ethylene, and may be a homopolymer of ethylene or a copolymer of ethylene and another monomer.

Examples of the ethylene homopolymer (i.e., polyethylene) include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-catalyzed linear low-density polyethylene (mLLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE).

The non-polar resin, such as the ethylene polymer, may be an oil-based component, such as paraffin oil or paraffin wax.

An example of the other component contained in composition (VII) is a solvent. Composition (VII) containing a solvent has excellent handleability.

Examples of the solvent contained in composition (VII) include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutyl alcohol (2-methylpropan-1-ol), and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; and amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone.
The solvent contained in the composition (VII) may be one kind or two or more kinds, and when two or more kinds are contained, the combination and ratio thereof can be selected arbitrarily.

The content of the other components in composition (VII) and the intermediate release layer can be adjusted appropriately depending on the type of the other components.

When the other component is a component other than the solvent, the ratio of the content of the other component (component other than the solvent) in the intermediate release layer to the total mass of the intermediate release layer ([content of components other than the solvent in the intermediate release layer (parts by mass)] / [total mass of the intermediate release layer (parts by mass)] x 100) is preferably 20% by mass or less, more preferably 10% by mass or less, and may be, for example, 5% by mass or less, 3% by mass or less, or 1% by mass or less. When the ratio is less than the upper limit value, the high-speed application ability of the first protective film-forming sheet and the penetration ability of the first protective film-forming film are further improved.
When the other component is a component other than the solvent, the proportion is 0% by mass or more.

When the other component is a solvent, the ratio of the content of the other component (solvent) in composition (VII) to the total mass of composition (VII) ([solvent content (parts by mass) of composition (VII)] / [total mass (parts by mass) of composition (VII)] × 100) is preferably 5 to 50% by mass, and may be, for example, 5 to 35% by mass or 5 to 20% by mass. When this ratio is equal to or greater than the lower limit, the handleability of composition (VII) is further improved. When this ratio is equal to or less than the upper limit, the first protective film-forming film can be formed more efficiently.

<Modifications of intermediate release layer>
Up to this point, the intermediate release layer has been described as being formed using a composition for forming an intermediate release layer containing an ethylene-vinyl acetate copolymer (EVA), but in this embodiment, the intermediate release layer may be formed using a composition for forming an intermediate release layer containing another resin component such as an acrylic resin instead of the ethylene-vinyl acetate copolymer (EVA). Examples of the acrylic resin include the acrylic resin described above in the thermosetting composition for forming the first protective film, and the acrylic resin (a1-1) described above in the energy ray-curable composition for forming the first protective film.

An example of a preferred intermediate release layer, which further enhances the intended effects of the present invention (high-speed application of the first protective film-forming sheet and penetration of the first protective film-forming film), is one that contains an ethylene-vinyl acetate copolymer, in which the content of the ethylene-vinyl acetate copolymer in the intermediate release layer relative to the total weight of the intermediate release layer is 80% by weight or more, preferably 90% by weight or more, and in which the proportion of the amount of structural units derived from vinyl acetate in the ethylene-vinyl acetate copolymer relative to the total amount of structural units is 16 to 40% by weight, and the weight-average molecular weight of the ethylene-vinyl acetate copolymer is 200,000 or less.

<<Method of manufacturing composition for forming intermediate release layer>>
The composition for forming the intermediate release layer, such as composition (VII), can be obtained by blending the components that constitute it.
The composition for forming the intermediate release layer can be produced by the same method as the composition for forming the thermosetting first protective film described above, except that the types of ingredients used are different.

Buffer layer The buffer layer has a buffering effect against forces applied to the buffer layer and layers adjacent thereto. Here, the "layers adjacent thereto" include the intermediate release layer, the first protective film-forming film, and the first protective film.

The material of the buffer layer is not particularly limited, but is preferably resin.

A preferred buffer layer is one formed using a buffer layer-forming composition containing, for example, urethane (meth)acrylate.

The buffer layer may be a single layer (single layer), or may be two or more layers. If there are multiple layers, these layers may be the same or different, and there are no particular limitations on the combination of these layers.

The thickness of the buffer layer is preferably 150 to 1000 μm, more preferably 150 to 800 μm, even more preferably 200 to 600 μm, and particularly preferably 250 to 500 μm.
Here, the "thickness of the buffer layer" means the thickness of the entire buffer layer, and for example, the thickness of a buffer layer consisting of multiple layers means the total thickness of all layers that make up the buffer layer.

<<Buffer layer forming composition>>
The buffer layer can be formed using a buffer layer-forming composition containing materials for forming the buffer layer. For example, the buffer layer can be formed by applying the buffer layer-forming composition to the surface on which the buffer layer is to be formed and drying it as necessary. When the buffer layer-forming composition has energy ray curability as described below, it is preferable to further cure the applied buffer layer-forming composition with energy rays. A more specific method for forming the buffer layer will be described in detail later, along with methods for forming other layers.

In the buffer layer-forming composition, the total content of one or more of the components described below in the buffer layer-forming composition does not exceed 100% by mass relative to the total mass of the buffer layer-forming composition.

The buffer layer-forming composition can be applied in the same manner as the first protective film-forming composition described above.
The drying conditions for the buffer layer-forming composition are not particularly limited, and may be the same as the drying conditions for the intermediate release layer-forming composition described above, for example.

When the energy ray-curable buffer layer-forming composition is cured with energy rays, the illuminance of the energy rays is preferably 100 to 350 mW/ ^cm2 , and the light dose of the energy rays is preferably 200 to 1400 mJ/ ^cm2 . The energy ray-curing of the energy ray-curable buffer layer-forming composition may be carried out in one step, or may be carried out in two or more separate steps (via semi-curing). When the energy ray-curing is carried out in multiple steps, the light dose of the energy rays is preferably 200 to 1400 mJ/ ^cm2 in all steps, and the total light dose of all steps is preferably 200 to 1400 mJ/ ^cm2 .

<Buffer layer forming composition (VI)>
Examples of the buffer layer-forming composition include a buffer layer-forming composition (VI) (sometimes simply referred to as "composition (VI)" in this specification) containing a urethane (meth)acrylate (X).

[Urethane (meth)acrylate (X)]
The urethane (meth)acrylate (X) contained in the composition (VI) is a compound having at least a (meth)acryloyl group and a urethane bond, and has the property of polymerizing upon irradiation with energy rays. That is, the composition (VI) has energy ray curability. The number of (meth)acryloyl groups in the urethane (meth)acrylate (X) may be one, two, or three or more (that is, the urethane (meth)acrylate (X) may be monofunctional, bifunctional, or trifunctional or higher), but a monofunctional urethane (meth)acrylate (X) is preferred. The monofunctional urethane (meth)acrylate (X) does not contribute to the formation of a three-dimensional network structure in the polymerization structure, making it difficult for a three-dimensional network structure to be formed in the buffer layer. In this case, the first protective film-forming sheet is more likely to conform to the bump formation surface of the semiconductor wafer.

The urethane (meth)acrylate (X) contained in composition (VI) may be one type or two or more types, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

The urethane (meth)acrylate (X) may be, for example, a reaction product of a terminal isocyanate urethane prepolymer, which is a reaction product of a polyol compound (x1) and a polyisocyanate compound (x2), with a compound (x3) having a (meth)acryloyl group. Here, the term "terminal isocyanate urethane prepolymer" is as described above.

The polyol compound (x1) is not particularly limited as long as it is a compound having two or more hydroxyl groups in one molecule.
Examples of the polyol compound (x1) include alkylene diols, polyether polyols, polyester polyols, polycarbonate polyols, etc. Among these, the polyol compound (x1) is preferably a polyether polyol.

The polyol compound (x1) may be any of a difunctional diol, a trifunctional triol, and a tetrafunctional or higher polyol. From the viewpoints of availability, versatility, reactivity, and the like, a difunctional diol is preferred, and a polyether diol is more preferred.
Examples of the polyether diol include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

The polyester polyol can be obtained by polycondensation of a polyol component and a polybasic acid component. Examples of the polyol component include various alkanediols such as ethylene glycol, diethylene glycol, and butanediol (preferably alkanediols having 2 to 10 carbon atoms), and various glycols.
Examples of the polybasic acid component include components known as polybasic acid components of general polyesters. More specific examples of the polybasic acid component include aliphatic dibasic acids having 4 to 20 carbon atoms, such as adipic acid and sebacic acid; aromatic dibasic acids, such as terephthalic acid; aromatic polybasic acids, such as trimellitic acid; anhydrides of these dibasic acids or polybasic acids; derivatives of these dibasic acids or polybasic acids, dimer acids, and hydrogenated dimer acids.

The polycarbonate-type polyol is not particularly limited. Examples of the polycarbonate-type polyol include reaction products of glycols and alkylene carbonates.

Examples of the polyisocyanate compound (x2) include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

Examples of the compound (x3) having a (meth)acryloyl group include (meth)acrylates having a hydroxyl group, and examples thereof include the same hydroxyl group-containing (meth)acrylic acid esters as those exemplified above as components constituting the acrylic resin as the polymer component (A), which is a component contained in the composition (III).
Among these, the (meth)acrylate having a hydroxyl group is preferably a hydroxyalkyl (meth)acrylate.

The weight-average molecular weight of the urethane (meth)acrylate (X) is preferably 1,000 to 100,000, more preferably 3,000 to 80,000, and even more preferably 5,000 to 65,000. When the weight-average molecular weight is 1,000 or more, the polymer of the urethane (meth)acrylate (X) and the polymerizable monomer (Z) described below imparts appropriate hardness to the buffer layer.

The ratio of the content of urethane (meth)acrylate (X) to the total content of components other than the solvent in composition (VI) ([content of urethane (meth)acrylate (X) in composition (VI) (parts by mass)] / [total content of components other than the solvent in composition (VI) (parts by mass)] × 100) is preferably 10 to 70% by mass, more preferably 20 to 70% by mass, even more preferably 25 to 60% by mass, and particularly preferably 30 to 50% by mass. By having this ratio within this range, the effects obtained by providing a buffer layer in the first protective film-forming sheet are enhanced without compromising other effects.

[Other ingredients]
The composition (VI) may contain a urethane (meth)acrylate (X) and other components that do not fall under the category of the urethane (meth)acrylate (X).
Examples of the other components in the composition (VI) include a thiol group-containing compound (Y) and a polymerizable monomer (Z).

The other components contained in composition (VI) may be one kind or two or more kinds, and when there are two or more kinds, the combination and ratio thereof can be selected arbitrarily.
The composition (VI) may contain only one of the thiol group-containing compound (Y) and the polymerizable monomer (Z), but preferably contains both the thiol group-containing compound (Y) and the polymerizable monomer (Z).

(Thiol Group-Containing Compound (Y))
The thiol group-containing compound (Y) is not particularly limited as long as it is a compound having one or more thiol groups (—SH) in one molecule.

Examples of thiol group-containing compounds (Y) include nonyl mercaptan, 1-dodecanethiol, 1,2-ethanedithiol, 1,3-propanedithiol, triazine thiol, triazine dithiol, triazine trithiol, 1,2,3-propane trithiol, tetraethylene glycol bis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), Examples include pentaerythritol tetrakisthioglucarate, dipentaerythritol hexakis(3-mercaptopropionate), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,4-bis(3-mercaptobutyryloxy)butane, pentaerythritol tetrakis(3-mercaptobutyrate), 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, etc.

The thiol group-containing compound (Y) is preferably a polyfunctional thiol group-containing compound (a compound having two or more thiol groups in one molecule), and more preferably a tetrafunctional thiol group-containing compound (a compound having four thiol groups in one molecule).

The thiol group-containing compound (Y) contained in composition (VI) may be one type or two or more types, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

In composition (VI), the content of thiol group-containing compound (Y) relative to 100 parts by mass of the total content of urethane (meth)acrylate (X) and polymerizable monomer (Z) ([content (parts by mass) of thiol group-containing compound (Y) in composition (VI)] / [total content (parts by mass) of urethane (meth)acrylate (X) and polymerizable monomer (Z) in composition (VI)] × 100) is preferably 1 to 4.9 parts by mass, and more preferably 1.5 to 4.8 parts by mass.

(Polymerizable Monomer (Z))
From the viewpoint of improving the film-forming properties of the buffer layer, the composition (VI) preferably contains a polymerizable monomer (Z). The polymerizable monomer (Z) is a polymerizable compound other than the urethane (meth)acrylate (X) and is a compound that can be polymerized by irradiation with energy rays. However, the polymerizable monomer (Z) does not include a resin component. Here, the "resin component" refers to an oligomer or polymer having a repeating unit in its structure and a compound having a weight-average molecular weight of 1,000 or more.

The polymerizable monomer (Z) is preferably a compound having one or more (meth)acryloyl groups. Examples of such polymerizable monomers (Z) include (meth)acrylic acid alkyl esters in which the alkyl group constituting the alkyl ester has a chain structure containing 1 to 18 carbon atoms; (meth)acrylic acid esters having functional groups such as hydroxyl groups, amide groups, amino groups, or epoxy groups; (meth)acrylic acid esters having an alicyclic structure such as (meth)acrylic acid cycloalkyl esters; (meth)acrylic acid esters having an aromatic structure; (meth)acrylic acid esters having a heterocyclic structure; and vinyl compounds other than these.

Among the (meth)acrylic acid esters having a functional group, examples of the (meth)acrylic acid esters having a hydroxyl group include the same hydroxyl group-containing (meth)acrylic acid esters as those previously listed as constituting the acrylic resin as the polymer component (A), which is a component contained in the composition (III).
Examples of the (meth)acrylic acid ester having an alicyclic structure include isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, and adamantane (meth)acrylate.
Examples of the (meth)acrylic acid ester having an aromatic structure include phenylhydroxypropyl (meth)acrylate, benzyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate.
Examples of the (meth)acrylic acid ester having a heterocyclic structure include tetrahydrofurfuryl (meth)acrylate and morpholine (meth)acrylate.

The polymerizable monomer (Z) contained in composition (VI) may be one type or two or more types, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

Composition (VI) preferably contains, as the polymerizable monomer (Z), at least a (meth)acrylic acid ester having an alicyclic structure, more preferably both a (meth)acrylic acid ester having an alicyclic structure and a (meth)acrylic acid ester having a functional group, and even more preferably both isobornyl (meth)acrylate and a hydroxyalkyl (meth)acrylate.

The ratio of the content of polymerizable monomer (Z) to the total content of components other than the solvent in composition (VI) ([content of polymerizable monomer (Z) in composition (VI) (parts by mass)] / [total content of components other than the solvent in composition (VI) (parts by mass)] × 100) is preferably 20 to 80% by mass, more preferably 30 to 80% by mass, even more preferably 40 to 75% by mass, and particularly preferably 50 to 70% by mass. When the content is within this range, the mobility of the portion of the buffer layer having a structure formed by polymerizing polymerizable monomer (Z) is increased, which tends to make the buffer layer more flexible and allows the first protective film-forming sheet to more easily conform to the bump-forming surface of the semiconductor wafer.

The ratio of the content of the (meth)acrylic acid ester having an alicyclic structure to the total content of the polymerizable monomer (Z) in composition (VI) ([content (parts by mass) of the (meth)acrylic acid ester having an alicyclic structure in composition (VI)] / [total content (parts by mass) of the polymerizable monomer (Z) in composition (VI)] × 100) is preferably 52 to 87% by mass, more preferably 55 to 85% by mass, and even more preferably 60 to 80% by mass. Having this content within this range makes it easier for the first protective film-forming sheet to conform to the bump-forming surface of the semiconductor wafer.

The mass ratio of [content (parts by mass) of urethane (meth)acrylate (X) in composition (VI)]/[content (parts by mass) of polymerizable monomer (Z) in composition (VI)] is preferably 20/80 to 60/40, more preferably 30/70 to 50/50, and even more preferably 35/65 to 45/55. Having this mass ratio within this range makes it easier for the first protective film-forming sheet to conform to the bump-forming surface of the semiconductor wafer.

(Photopolymerization initiator)
The composition (VI) preferably further contains a photopolymerization initiator. The composition (VI) containing a photopolymerization initiator is more easily cured by irradiation with energy rays.

Examples of the photopolymerization initiator contained in composition (VI) include acetophenone, 2,2-diethoxybenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, Michler's ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl diphenylsulfide, tetramethylthiuram monosulfide, benzil dimethyl ketal, dibenzyl, diacetyl, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-ethylanthraquinone, and 2,2-dimethoxy-1,2-diphenylethane. Examples include low molecular weight polymerization initiators such as 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, diethylthioxanthone, isopropylthioxanthone, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; and oligomerized polymerization initiators such as oligo{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone}.

Composition (VI) may contain only one type of photopolymerization initiator, or two or more types. If two or more types are contained, the combination and ratio of these can be selected arbitrarily.

In composition (VI), the content of the photopolymerization initiator relative to the total content of the urethane (meth)acrylate (X) and polymerizable monomer (Z) (100 parts by mass) ([content of photopolymerization initiator in composition (VI) (parts by mass)] / [total content of urethane (meth)acrylate (X) and polymerizable monomer (Z) in composition (VI) (parts by mass)] × 100) is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass.

(Other additives)
Composition (VI) may contain other additives that do not fall under the components described above, as long as the effects of the present invention are not impaired.
Examples of the other additives include crosslinking agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, and dyes.

When composition (VI) contains the other additives, the content of the other additives relative to 100 parts by mass of the total content of the urethane (meth)acrylate (X) and polymerizable monomer (Z) in composition (VI) ([content (parts by mass) of other additives in composition (VI)] / [total content (parts by mass) of the urethane (meth)acrylate (X) and polymerizable monomer (Z) in composition (VI)] × 100) is preferably 0.01 to 6 parts by mass, and more preferably 0.1 to 3 parts by mass.

(Other resin components)
The composition (VI) may contain other resin components that do not fall under the category of the urethane (meth)acrylate (X) within the range that does not impair the effects of the present invention.

<Modifications of the buffer layer>
So far, the buffer layer has been described as being formed using a buffer layer-forming composition containing the urethane (meth)acrylate (X). However, in the present embodiment, the buffer layer may be formed using a buffer layer-forming composition containing another resin component, such as an olefin-based resin, instead of the urethane (meth)acrylate (X).

An example of a preferred buffer layer, in terms of further enhancing the intended effects of the present invention (high-speed application ability of the first protective film-forming sheet and penetration ability of the first protective film-forming film), is a buffer layer obtained using a buffer layer-forming composition (composition (VI)) containing a urethane (meth)acrylate (X), a thiol group-containing compound (Y), a polymerizable monomer (Z), a photopolymerization initiator, and a crosslinking agent, in which the ratio of the total content of the urethane (meth)acrylate (X), the thiol group-containing compound (Y), the polymerizable monomer (Z), the photopolymerization initiator, and the crosslinking agent to the total content of components other than the solvent in the buffer layer-forming composition is 85 mass% or more, preferably 90 mass% or more, and more preferably 95 mass% or more.
In view of the above, a more preferable example of the buffer layer is a buffer layer obtained using a buffer layer-forming composition (composition (VI)) containing a urethane (meth)acrylate (X), a thiol group-containing compound (Y), a polymerizable monomer (Z), a photopolymerization initiator, and a crosslinking agent, in which the urethane (meth)acrylate (X) is a reaction product of a terminal isocyanate urethane prepolymer, which is a reaction product of a polyol compound (x1) and a polyisocyanate compound (x2), and a compound (x3) having a (meth)acryloyl group, and the thiol group-containing compound (Y) is one molecule thereof. and the polymerizable monomer (Z) is a (meth)acrylic acid ester having an alicyclic structure and a (meth)acrylic acid ester having a functional group, and the proportion of the total content of the urethane (meth)acrylate (X), the thiol group-containing compound (Y), the polymerizable monomer (Z), the photopolymerization initiator, and the crosslinking agent relative to the total content of components other than the solvent in the buffer layer-forming composition is 85% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass or more.
These buffer layers are preferably obtained by curing the buffer layer-forming composition with energy rays.
The thickness of these buffer layers is preferably 10 to 70 times, and more preferably 30 to 50 times, the thickness of the intermediate release layer.

<<Method of manufacturing the buffer layer-forming composition>>
The buffer layer-forming composition such as composition (VI) can be obtained by blending the components that constitute it.
The buffer layer-forming composition can be produced by the same method as the thermosetting first protective film-forming composition described above, except that the types of ingredients used are different.

First Substrate The first substrate is in the form of a sheet or film, and examples of the constituent material thereof include various resins.
Examples of the resin include polyethylenes such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE); polyolefins other than polyethylene such as polypropylene, polybutene, polybutadiene, polymethylpentene, and norbornene resin; ethylene-based copolymers (copolymers obtained using ethylene as a monomer) such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, and ethylene-norbornene copolymer; and vinyl chloride-based resins (copolymers obtained using vinyl chloride as a monomer) such as polyvinyl chloride and vinyl chloride copolymer. Examples of the resins include: polystyrene; polycycloolefins; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalenedicarboxylate, and wholly aromatic polyesters in which all structural units have aromatic cyclic groups; copolymers of two or more of the above polyesters; poly(meth)acrylic acid esters; polyurethanes; polyurethane acrylates; polyimides; polyamides; polycarbonates; fluororesins; polyacetals; modified polyphenylene oxides; polyphenylene sulfides; polysulfones; and polyether ketones.
Further, examples of the resin include polymer alloys such as mixtures of the polyester and other resins. The polymer alloys of the polyester and other resins preferably contain a relatively small amount of resin other than polyester.
Examples of the resin include crosslinked resins in which one or more of the resins exemplified above are crosslinked; and modified resins such as ionomers using one or more of the resins exemplified above.

The resin constituting the first substrate may be one type only, or two or more types. If two or more types are used, the combination and ratio of these can be selected arbitrarily.

The first substrate may be a single layer (single layer), or may be two or more layers. If it is a multiple layer substrate, these layers may be the same or different from each other, and there are no particular limitations on the combination of these layers.

The thickness of the first substrate is preferably 5 to 1000 μm, more preferably 10 to 500 μm, even more preferably 15 to 300 μm, and particularly preferably 20 to 150 μm.
Here, "thickness of the first substrate" means the thickness of the entire first substrate, and for example, the thickness of a first substrate consisting of multiple layers means the total thickness of all layers that make up the first substrate.

The first substrate preferably has a high thickness precision, i.e., one with reduced thickness variation regardless of location. Among the above-mentioned constituent materials, examples of materials that can be used to form a first substrate with such high thickness precision include polyethylene, polyolefins other than polyethylene, polyethylene terephthalate, and ethylene-vinyl acetate copolymer.

In addition to the main constituent materials such as the resin, the first substrate may contain various known additives such as fillers, colorants, antistatic agents, antioxidants, organic lubricants, catalysts, and softeners (plasticizers).

The first substrate may be transparent or opaque, may be colored depending on the purpose, and may have other layers vapor-deposited thereon.
When the first protective film-forming film is energy ray curable, the first substrate is preferably one that transmits energy rays.

The first substrate can be manufactured by a known method. For example, a first substrate containing a resin can be manufactured by molding a resin composition containing the resin.

Manufacturing Method of the First Protective Film-Forming Sheet The first protective film-forming sheet can be manufactured by laminating the above-described layers in order so that they are in a corresponding positional relationship. The method of forming each layer is as described above.

For example, the first protective film-forming sheet can be produced by the following method.
That is, a buffer layer is formed on the first substrate by applying a buffer layer-forming composition (for example, the composition (VI)) to one surface of the first substrate and drying it as needed. If the buffer layer-forming composition is energy ray-curable, the applied buffer layer-forming composition is further cured with energy rays. This results in a first laminate sheet in which the first substrate and the buffer layer are laminated together. If necessary, a release film may be further provided on the exposed surface of the buffer layer in the first laminate sheet (the surface opposite to the first substrate side).
Separately, an intermediate release layer-forming composition (e.g., composition (VII)) is applied to a release film and dried as necessary to form an intermediate release layer on the release film. In this case, the intermediate release layer-forming composition is preferably applied to the release-treated surface of the release film.
Separately, a first protective film-forming composition (e.g., composition (III), composition (IV), or composition (V)) is applied to a release film and dried as necessary to form a first protective film-forming film on the release film. In this case, it is preferable that the first protective film-forming composition is applied to the release-treated surface of the release film.

Next, the exposed surface of the buffer layer of the first laminate sheet (the surface opposite the first substrate side) is bonded to the exposed surface of the intermediate release layer (the surface opposite the release film side). This results in a second laminate sheet composed of the first substrate, buffer layer, intermediate release layer, and release film stacked in this order in the thickness direction.

Next, the release film is removed from the second laminate sheet, and the resulting exposed surface of the intermediate release layer (the surface opposite the buffer layer side) is bonded to the exposed surface of the first protective film-forming film (the surface opposite the release film side). This results in a first protective film-forming sheet constructed by laminating the first substrate, buffer layer, intermediate release layer, first protective film-forming film, and release film in this order in the thickness direction. The release film provided on the first protective film-forming film in the first protective film-forming sheet can be removed at any stage from after the production of the first protective film-forming sheet to after use.

A first protective film-forming sheet having layers other than the layers described above can be produced by appropriately adding either or both of the steps of forming and laminating the other layers to the above-described manufacturing method so that the lamination positions of the other layers are appropriate.

◇Method for manufacturing a semiconductor device (method for using the sheet for forming a first protective film)
As described above, a semiconductor wafer with a first protective film can be manufactured by using the first protective film-forming sheet of this embodiment, applying the first protective film-forming film to the bump-forming surface of a semiconductor wafer, and then curing the first protective film as needed. The first protective film-forming sheet of this embodiment can be applied to the bump-forming surface of a semiconductor wafer at high speed. Furthermore, even when the first protective film-forming sheet is applied at high speed, the tops of the bumps can be protruded from the first protective film-forming film, thereby preventing the first protective film-forming film from remaining above the bumps. The semiconductor wafer with a first protective film can then be divided to manufacture semiconductor chips with a first protective film, each of which includes a semiconductor chip and a first protective film provided on the bump-forming surface of the semiconductor chip. At this time, because the first protective film-forming film is prevented from remaining on the bumps of the semiconductor wafer with the first protective film, adhesion of the first protective film is also prevented on the bumps of the resulting semiconductor chip with the first protective film. Furthermore, a semiconductor device can be manufactured by flip-chip connecting the semiconductor chip with the first protective film to a substrate at the bumps therein. At this time, because adhesion of the first protective film on the bumps of the semiconductor chip with the first protective film is prevented, electrical connection between the semiconductor chip and the substrate is not hindered. In other words, the sheet for forming a first protective film of this embodiment is suitable for manufacturing semiconductor devices.
A method for manufacturing a semiconductor device using the first protective film forming sheet will be described below.

A semiconductor device manufacturing method according to one embodiment of the present invention is a method for manufacturing a semiconductor device using a first protective film-forming sheet according to one embodiment of the present invention described above, and the manufacturing method includes a bonding step of bonding the first protective film-forming film in the first protective film-forming sheet to a surface of a semiconductor wafer having bumps (bump-forming surface) and causing the tops of the bumps to protrude from the first protective film-forming film, thereby providing the first protective film-forming sheet on the semiconductor wafer; and after the bonding step, removing layers of the first protective film-forming sheet other than the first protective film-forming film from the first protective film-forming film, and further, if the first protective film-forming film is curable, curing the first protective film-forming film to form a first protective film, and the first protective film-forming film If the film is non-curable, the method includes a first protective film forming step of forming the first protective film on the surface having the bumps (bump-forming surface) by treating the first protective film as a first protective film after removing layers other than the first protective film-forming film; a dividing step of dividing the semiconductor wafer to produce semiconductor chips after the first protective film forming step; a cutting step of cutting the first protective film after the first protective film forming step; and a mounting step of flip-chip connecting the semiconductor chip with the first protective film, which has the tops of the bumps protruding from the first protective film, to a substrate at the tops of the bumps, the semiconductor chips obtained after the dividing and cutting steps.

Among the methods for manufacturing a semiconductor device according to this embodiment, a manufacturing method in which the first protective film-forming film is curable (sometimes referred to herein as "manufacturing method (1)") includes a bonding step of bonding the first protective film-forming film in the first protective film-forming sheet to a surface of a semiconductor wafer having bumps (bump-forming surface) and causing the tops of the bumps to protrude from the first protective film-forming film, thereby providing the first protective film-forming sheet on the semiconductor wafer; and, after the bonding step, removing layers of the first protective film-forming sheet other than the first protective film-forming film from the first protective film-forming film, and further curing the first protective film-forming film. The method includes a first protective film forming step of forming a first protective film on the surface having the bumps (bump-forming surface) by dividing the semiconductor wafer after the first protective film forming step, a dividing step of producing semiconductor chips by dividing the semiconductor wafer after the first protective film forming step, a cutting step of cutting the first protective film after the first protective film forming step, and a mounting step of flip-chip connecting the semiconductor chip with the first protective film, which includes the semiconductor chip obtained after the dividing step and the cutting step, and the first protective film provided on the surface having the bumps of the semiconductor chip, with the tops of the bumps protruding from the first protective film, to a substrate at the tops of the bumps.

Among the methods for manufacturing a semiconductor device according to this embodiment, a manufacturing method in which the first protective film-forming film is non-curable (sometimes referred to in this specification as "manufacturing method (2)") includes a bonding step of bonding the first protective film-forming film in the first protective film-forming sheet to a surface of a semiconductor wafer having bumps (bump-forming surface) and causing the tops of the bumps to protrude from the first protective film-forming film, thereby providing the first protective film-forming sheet on the semiconductor wafer; and, after the bonding step, removing layers of the first protective film-forming sheet other than the first protective film-forming film from the first protective film-forming film, and further removing the first protective film-forming film after removing the layers other than the first protective film-forming film. The method includes a first protective film forming step of forming the first protective film on the surface having the bumps (bump-formed surface) by treating a protective film-forming film as a first protective film; a dividing step of dividing the semiconductor wafer after the first protective film forming step to produce semiconductor chips; a cutting step of cutting the first protective film after the first protective film forming step; and a mounting step of flip-chip connecting the semiconductor chip with the first protective film, which includes the semiconductor chip obtained after the dividing step and the cutting step, and the first protective film provided on the surface having the bumps of the semiconductor chip, with the tops of the bumps protruding from the first protective film, to a substrate at the tops of the bumps.

<<Manufacturing method (1)>>
The manufacturing method (1) will be described below.
FIG. 3 is a cross-sectional view for schematically explaining an example of the manufacturing method (1) when the first protective film-forming sheet 1 shown in FIG. 2 is used.
In FIG. 3 and subsequent figures, the same components as those shown in the figures already described are given the same reference numerals as in the figures already described, and detailed description thereof will be omitted.

<Attachment process>
In the bonding process of manufacturing method (1), as shown in Figures 3(a) to 3(b), the first protective film forming film 14 in the first protective film forming sheet 1 is bonded to the surface (bump forming surface) 9a of the semiconductor wafer 9 having bumps 91, and the tops 9101 of the bumps 91 are made to protrude from the first protective film forming film 14, thereby providing the first protective film forming sheet 1 on the semiconductor wafer 9.

In the attachment process, for example, as shown in Figure 3(a), the first protective film-forming sheet 1 is first positioned so that the first protective film-forming film 14 therein faces the bump-forming surface 9a of the semiconductor wafer 9.

The height of the bump 91 is not particularly limited, but is preferably 120 to 300 μm, more preferably 150 to 270 μm, and particularly preferably 180 to 240 μm. When the height of the bump 91 is equal to or greater than the lower limit, the function of the bump 91 can be further improved. When the height of the bump 91 is equal to or less than the upper limit, the effect of suppressing the first protective film-forming film 14 from remaining on the upper portion 910 of the bump 91 is further enhanced.
In this specification, the "height of a bump" means the height of the bump at the highest point from the bump formation surface.

The width of the bump 91 is not particularly limited, but is preferably 170 to 350 μm, more preferably 200 to 320 μm, and particularly preferably 230 to 290 μm. When the width of the bump 91 is equal to or greater than the lower limit, the function of the bump 91 can be further improved. When the width of the bump 91 is equal to or less than the upper limit, the effect of suppressing the first protective film-forming film 14 from remaining on the upper portion 910 of the bump 91 is enhanced.
In this specification, the "bump width" means the maximum length of a line segment obtained by connecting two different points on the bump surface when the bump is viewed in a plan view looking down on the bump from a direction perpendicular to the bump formation surface.

The distance between adjacent bumps 91 is not particularly limited, but is preferably 250 to 800 μm, more preferably 300 to 600 μm, and particularly preferably 350 to 500 μm. When the distance is equal to or greater than the lower limit, the function of the bumps 91 can be further improved. When the distance is equal to or less than the upper limit, the effect of suppressing the first protective film-forming film 14 from remaining on the upper portions 910 of the bumps 91 is further enhanced.
In this specification, the "distance between adjacent bumps" means the minimum distance between the surfaces of adjacent bumps.

Next, in the bonding step, the first protective film-forming film 14 is brought into contact with the bumps 91 on the semiconductor wafer 9, and the first protective film-forming sheet 1 is pressed against the semiconductor wafer 9. As a result, the first surface 14a of the first protective film-forming film 14 is pressed against the surfaces 91a of the bumps 91 and the bump-forming surface 9a of the semiconductor wafer 9, successively. At this time, by heating the first protective film-forming film 14, the first protective film-forming film 14 softens and spreads between the bumps 91 so as to cover the bumps 91, adheres to the bump-forming surface 9a, and covers the surfaces 91a of the bumps 91, particularly the surfaces 91a in the vicinity of the bump-forming surface 9a, thereby embedding the bases of the bumps 91.
As a result of the above, the first protective film-forming film 14 in the first protective film-forming sheet 1 is attached to the bump-forming surface 9a of the semiconductor wafer 9, as shown in FIG. 3(b).

As described above, the first protective film forming sheet 1 can be pressure-bonded (in other words, attached) to the semiconductor wafer 9 by any known method for pressing various sheets onto an object, such as a method using a roller laminator.

The heating temperature of the first protective film-forming sheet 1 (first protective film-forming film 14) when it is pressed (attached) to the semiconductor wafer 9 may be a temperature at which the thermosetting first protective film-forming film 14 does not harden at all or does not harden excessively, and may be, for example, 80 to 100°C.
However, the heating temperature is more preferably 85 to 95° C. in order to enhance the effect of suppressing the first protective film forming film 14 from remaining on the upper portion 910 of the bump 91 .

The pressure when the first protective film-forming sheet 1 (first protective film-forming film 14) is pressed (attached) to the semiconductor wafer 9 is not particularly limited, and may be, for example, 0.1 to 1.5 MPa.
However, in order to enhance the effect of suppressing the first protective film forming film 14 from remaining on the upper portion 910 of the bump 91, the pressure is more preferably 0.3 to 1 MPa.

The speed (application speed) when the first protective film-forming sheet 1 (first protective film-forming film 14) is applied to the semiconductor wafer 9 may be, for example, 3 mm/s or more, but is preferably 4 mm/s or more. That is, in the application process, the first protective film-forming film 14 is preferably applied to the bump-forming surface 9a of the semiconductor wafer 9 at an application speed of 4 mm/s or more. By applying the first protective film-forming film 14 at a high speed such as 4 mm/s or more, the above-mentioned effect of suppressing the first protective film-forming film 14 from remaining on the upper parts 910 of the bumps 91 is more pronounced. On the other hand, by setting the application speed to 20 mm/s or less, the above-mentioned effect of suppressing the first protective film-forming film 14 from remaining on the upper parts 910 of the bumps 91 is more stably achieved.

As described above, when the first protective film-forming sheet 1 is pressed (affixed) to the semiconductor wafer 9, the first protective film-forming film 14 and intermediate release layer 13 in the first protective film-forming sheet 1 are pressed through the buffer layer 12 and subjected to pressure from the bumps 91. Initially, the first surface 14a of the first protective film-forming film 14 and the first surface 13a of the intermediate release layer 13 are deformed into a concave shape. Then, as pressure is applied from the bumps 91 in this state, the first protective film-forming film 14 tears. Finally, when the first surface 14a of the first protective film-forming film 14 is pressed against the bump-forming surface 9a of the semiconductor wafer 9, the upper portion 910, including the apex 9101 of the bump 91, protrudes through the first protective film-forming film 14. Furthermore, when the intermediate release layer 13 contains an olefin-based thermoplastic resin such as EVA, the upper portion 910 of the bump 91 does not penetrate the intermediate release layer 13 in this final stage.

As shown in Figure 3(b), at the stage where the attachment process is completed, none or almost none of the first protective film-forming film 14 remains on the upper portion 910 including the top portion 9101 of the bump 91, and the remaining first protective film-forming film 14 is suppressed on the upper portion 910 of the bump 91. In this specification, unless otherwise specified, "almost no first protective film-forming film remains on the upper portion of the bump" means that although a small amount of the first protective film remains on the upper portion of the bump, the remaining amount is such that it does not interfere with the electrical connection between the semiconductor chip and the substrate when the semiconductor chip having this bump is flip-chip connected to the substrate.

After the attachment step in manufacturing method (1), if necessary, the surface (back surface) 9b of the semiconductor wafer 9 opposite the bump-forming surface 9a is ground, and then a second protective film-forming sheet (not shown) is attached to this back surface 9b.

<First protective film formation step>
After the bonding step of manufacturing method (1), in the first protective film forming step, first, as shown in FIG. 3( c), layers of the first protective film-forming sheet 1 other than the first protective film-forming film 14 are removed from the first protective film-forming film 14. In this specification, this step in the first protective film forming step may be referred to as the "removing step." More specifically, the layers removed here are the first substrate 11, the buffer layer 12, and the intermediate release layer 13. This results in a semiconductor wafer 914 with a first protective film-forming film, which is configured to include the semiconductor wafer 9 and the first protective film-forming film 14 provided on the bump-forming surface 9 a of the semiconductor wafer 9.
The layers other than the first protective film-forming film 14 can be removed from the first protective film-forming film 14 by a known method.

In the first protective film forming step of manufacturing method (1), the first protective film-forming film 14 is then cured to form the first protective film 14' on the bump-forming surface 9a, as shown in FIG. 3(d). In this specification, this step in the first protective film forming step is sometimes referred to as the "curing step." As a result, a first protective film-coated semiconductor wafer 914' is obtained, which includes the semiconductor wafer 9 and the first protective film 14' provided on the bump-forming surface 9a of the semiconductor wafer 9.
The first protective film-forming film 14 is curable, and in this step (the curing step), if the first protective film-forming film 14 is thermosetting, the first protective film-forming film 14 is cured by heating, and if the first protective film-forming film 14 is energy ray-curable, the first protective film-forming film 14 is cured by irradiating with energy rays. The heating conditions and energy ray irradiation conditions at this time are as described above.

<Dividing process, cutting process>
After the first protective film forming step in manufacturing method (1), the semiconductor wafer 9 is divided into semiconductor chips 90 in the dividing step, and the first protective film 14' is cut in the cutting step. Here, the first protective film 14' after cutting is newly assigned the reference symbol 140'.
By performing the dividing process and cutting process, a semiconductor chip 9140' with a first protective film is obtained, as shown in Figure 3(e), which is composed of a semiconductor chip 90 and a first protective film (sometimes simply referred to as the "first protective film" in this specification) 140' after cutting, which is provided on the bump formation surface (surface having bumps) 90a of the semiconductor chip 90.

The dividing and cutting steps can be carried out using known methods.

The order in which the dividing step and the cutting step are performed is not particularly limited, but it is preferable to perform the dividing step and the cutting step simultaneously, or to perform the dividing step and the cutting step in that order. When the dividing step and the cutting step are performed in this order, for example, the dividing step may be performed by a known dicing method, and then the cutting step may be performed immediately thereafter. Dicing can be performed by providing a dicing sheet (not shown) on the back surface 9b of the semiconductor wafer 9 (which may be the back surface after grinding).
In the cutting step, the first protective film 14' is cut along the planned or completed dividing points of the semiconductor wafer 9 (in other words, along the outer periphery of the semiconductor chip 90).

In the semiconductor chip 9140' with the first protective film, the tops 9101 of the bumps 91 protrude from the first protective film 140', and the first protective film is not or almost not attached to the upper parts 910, including the tops 9101, of the bumps 91, suppressing adhesion of the first protective film to the upper parts 910 of the bumps 91. Note that, in this specification, "almost no first protective film attached to the tops of the bumps" means, unless otherwise specified, that although a small amount of the first protective film is attached to the tops of the bumps, the amount is such that it does not interfere with electrical connection between the semiconductor chip and the substrate when the semiconductor chip with these bumps is flip-chip connected to the substrate.

<Mounting process>
In the mounting step of manufacturing method (1), the semiconductor chip 9140' with the first protective film, obtained after the dividing step and cutting step, in which the top portions 9101 of the bumps 91 protrude from the first protective film 140', is flip-chip connected to a substrate (not shown) at the top portions 9101 of the bumps 91. At this time, the semiconductor chip 9140' with the first protective film is connected to the circuit formation surface of the substrate.
Since the adhesion of the first protective film 140' to the upper portions 910 of the bumps 91 in the semiconductor chip 9140' with the first protective film is suppressed, the degree of electrical connection between the semiconductor chip 90 and the substrate is high in this step.

When the second protective film forming sheet is used, the semiconductor chip 9140' with the first protective film is picked up by separating it from the dicing sheet (not shown) in the second protective film forming sheet prior to flip-chip connection.
The semiconductor chip 9140' with the first protective film can be picked up by a known method.
When the second protective film forming sheet is used, the semiconductor chip 90 in the semiconductor chip 9140' with the first protective film has the second protective film after cutting on the rear surface 90b thereof (not shown).

If the second protective film-forming film in the second protective film-forming sheet is curable, the second protective film-forming film is cured at an appropriate time depending on its type to form the second protective film. The second protective film is then cut at an appropriate time depending on its type.

The second protective film-forming film can be cured in the same manner as the first protective film-forming film 14, and may be cured simultaneously with the first protective film-forming film 14 or separately from the first protective film-forming film 14.

The second protective film can be cut in the same manner as the first protective film.
The order in which the dividing step and the cutting of the second protective film are performed is not particularly limited, but it is preferable to perform the dividing step and the cutting of the second protective film simultaneously, or to perform the cutting of the second protective film after the dividing step. When the dividing step and the cutting of the second protective film are performed in this order, for example, the dividing step may be performed by a known dicing method, and then the cutting of the second protective film may be performed immediately and continuously thereafter.
The second protective film is cut along the planned or completed dividing points of the semiconductor wafer 9 (in other words, along the outer periphery of the semiconductor chip 90).

Then, using the circuit board thus obtained and already equipped with the semiconductor chip 90, a semiconductor package is produced according to a known method, and the desired semiconductor device can be manufactured using this semiconductor package (not shown).

<<Manufacturing method (2)>>
Next, the manufacturing method (2) will be described.
FIG. 4 is a cross-sectional view for schematically explaining an example of the manufacturing method (2) when the first protective film-forming sheet 1 shown in FIG. 2 is used.

In the bonding process of manufacturing method (2), as shown in Figures 4(a) to 4(b), the first protective film forming film 14 in the first protective film forming sheet 1 is bonded to the surface (bump forming surface) 9a of the semiconductor wafer 9 having bumps 91, and the tops 9101 of the bumps 91 are made to protrude from the first protective film forming film 14, thereby providing the first protective film forming sheet 1 on the semiconductor wafer 9.
The bonding step of manufacturing method (2) is the same as the bonding step of manufacturing method (1) except that the first protective film-forming film 14 in the first protective film-forming sheet 1 is non-curable rather than curable, and can be performed in the same manner as the bonding step of manufacturing method (1). Therefore, further detailed explanation of the bonding step of manufacturing method (2) will be omitted.

Even in manufacturing method (2), even if the first protective film-forming film 14 is attached to the bump-forming surface 9a of the semiconductor wafer 9 at high speed, as shown in FIG. 4(b), at the stage when the attachment process is completed, none or almost none of the first protective film-forming film 14 remains on the upper portion 910 including the top portion 9101 of the bump 91, and the remaining first protective film-forming film 14 is suppressed on the upper portion 910 of the bump 91.

After the above-mentioned attachment step in manufacturing method (2), if necessary, the surface (back surface) 9b of the semiconductor wafer 9 opposite the bump-forming surface 9a is ground, and then a second protective film formation sheet (not shown) is attached to this back surface 9b.

<First protective film formation step>
After the bonding step in manufacturing method (2), in the first protective film forming step, layers of the first protective film-forming sheet 1 other than the first protective film-forming film 14 are removed from the first protective film-forming film 14. In this specification, as in manufacturing method (1), this step in the first protective film forming step may be referred to as the "removing step." This step (the removing step) is the same as the removing step in manufacturing method (1) described above, except that the first protective film-forming film 14 in the first protective film-forming sheet 1 is non-curable rather than curable, and can be performed in the same manner as the removing step in manufacturing method (1). Therefore, further detailed explanation of the removing step in manufacturing method (2) will be omitted.

In the first protective film forming step of the manufacturing method (2), the non-curable first protective film-forming film 14 is treated as the first protective film after removing the layers other than the first protective film-forming film 14. As a result, a first protective film 14' is formed on the bump-forming surface 9a, as shown in FIG.
The non-curable first protective film-forming film 14 also functions as a protective film in its current state. Therefore, in this embodiment, the non-curable first protective film-forming film 14 is considered to be the first protective film 14′ after the intermediate release layer 13 is removed during use.
As a result, a semiconductor wafer 914' with a first protective film is obtained, similar to the case after the curing step in manufacturing method (1).

In manufacturing method (2), in the semiconductor chip 9140' with the first protective film, the tops 9101 of the bumps 91 protrude from the first protective film 140', and the first protective film is not or hardly adheres to the upper parts 910, including the tops 9101, of the bumps 91, thereby suppressing adhesion of the first protective film to the upper parts 910 of the bumps 91.

<Dividing process, cutting process>
After the first protective film forming step of the manufacturing method (1), the semiconductor wafer 9 is divided into semiconductor chips 90 in the dividing step, and the first protective film 14' is cut in the cutting step.
By carrying out the dividing step and cutting step, a semiconductor chip 9140' with a first protective film is obtained as shown in FIG. 4(d).

The dividing and cutting steps of manufacturing method (2) are the same as those of manufacturing method (1), except that the first protective film 14' is not a cured product of the first protective film-forming film 14, and can be performed in the same manner as the dividing and cutting steps of manufacturing method (1). Therefore, further detailed explanation of the dividing and cutting steps of manufacturing method (2) will be omitted.

<Mounting process>
In the mounting step of manufacturing method (2), the semiconductor chip 9140' with the first protective film, obtained after the dividing step and cutting step, in which the top portions 9101 of the bumps 91 protrude from the first protective film 140', is flip-chip connected to a substrate (not shown) at the top portions 9101 of the bumps 91. At this time, the semiconductor chip 9140' with the first protective film is connected to the circuit formation surface of the substrate.
Since the adhesion of the first protective film 140' to the upper portions 910 of the bumps 91 in the semiconductor chip 9140' with the first protective film is suppressed, the degree of electrical connection between the semiconductor chip 90 and the substrate is high in this step.

The mounting step of manufacturing method (2) is the same as the mounting step of manufacturing method (1), except that the first protective film 140' is not a cured product of the first protective film-forming film 14, and can be performed in the same manner as the mounting step of manufacturing method (1). Therefore, further detailed explanation of the mounting step of manufacturing method (2) will be omitted.

In manufacturing method (2), the same procedure as in manufacturing method (1) is followed: a semiconductor package is produced using a circuit board on which a semiconductor chip 90 has already been mounted, and the desired semiconductor device can be manufactured using this semiconductor package (not shown).

In both manufacturing method (1) and manufacturing method (2), the case where the first protective film-forming sheet 1 shown in FIG. 2 is used has been described here, but even when a first protective film-forming sheet of another embodiment is used, the first protective film-forming sheet will achieve the same effects as when the first protective film-forming sheet 1 is used.

<<Modification of the semiconductor device manufacturing method (method of using the first protective film forming sheet)>>
In the semiconductor device manufacturing method of this embodiment, a semiconductor wafer can be used in which grooves, which will be the dividing points of the semiconductor wafer when the semiconductor wafer is divided into individual semiconductor chips, are formed on the bump-forming surface. By using such a semiconductor wafer, semiconductor chips can be fabricated in which the first protective film is provided not only on the bump-forming surface but also on the side surfaces. Here, the side surfaces refer to the outer periphery of the semiconductor chip that is continuous with the bump-forming surface, and a semiconductor chip having a rectangular planar shape has four side surfaces. Furthermore, a semiconductor chip having a rectangular planar shape is provided with the first protective film on the bump-forming surface and the four side surfaces. Regardless of the planar shape of the semiconductor chip, a semiconductor chip whose side surfaces are also protected in this manner can achieve a higher protective effect provided by the first protective film.

A method for manufacturing a semiconductor device according to this embodiment in this case may be, for example, a method for manufacturing a semiconductor device using a first protective film-forming sheet according to one embodiment of the present invention described above, in which the manufacturing method includes a semiconductor wafer having a bump-bearing surface (bump-forming surface) on which grooves are formed to serve as dividing points for the semiconductor wafer, and a bonding step of bonding the first protective film-forming film in the first protective film-forming sheet to the bump-bearing surface of the semiconductor wafer, causing the tops of the bumps to protrude from the first protective film-forming film and filling the grooves with the first protective film-forming film, thereby providing the first protective film-forming sheet on the semiconductor wafer; and, after the bonding step, removing layers of the first protective film-forming sheet other than the first protective film-forming film from the first protective film-forming film, and, if the first protective film-forming film is curable, curing the first protective film to form a first protective film. If the first protective film-forming film is non-curable, The method for manufacturing a semiconductor device includes: a first protective film forming step of forming the first protective film on the bump-bearing surface (bump-forming surface) by treating the first protective film as a first protective film after removing layers other than the first protective film; a dividing step of grinding the surface (back surface) of the semiconductor wafer opposite the bump-bearing surface (bump-forming surface) after the first protective film forming step, bringing the ground surface to the grooves filled with the protective film (exposing the grooves on the opposite surface), and dividing the semiconductor wafer to produce a group of semiconductor chips integrated with the first protective film filled in the grooves; a cutting step of cutting the first protective film after the dividing step; and a mounting step of flip-chip connecting the semiconductor chips with the first protective film obtained after the dividing and cutting steps, which include the semiconductor chips and the first protective film provided on the bump-bearing surface and side surfaces of the semiconductor chips, and in which the tops of the bumps protrude from the first protective film, to a substrate at the tops of the bumps.

Among the variations of the semiconductor device manufacturing method of this embodiment, a manufacturing method in which the first protective film-forming film is curable (sometimes referred to in this specification as "manufacturing method (3)") includes the following steps: 1) using a semiconductor wafer having a surface (bump-forming surface) on which grooves are formed to form the dividing points of the semiconductor wafer; 2) attaching the first protective film-forming film in the first protective film-forming sheet to the surface (bump-forming surface) of the semiconductor wafer having the bumps, causing the tops of the bumps to protrude from the first protective film-forming film, and filling the grooves with the first protective film-forming film, thereby providing the first protective film-forming sheet on the semiconductor wafer; 3) removing, after the attaching step, layers of the first protective film-forming sheet other than the first protective film-forming film from the first protective film-forming film; and 4) curing the first protective film-forming film to form the first protective film-forming sheet. a first protective film forming step of forming the first protective film on the surface having the bumps (bump-forming surface) by forming a film thereon; a dividing step of grinding the surface (back surface) of the semiconductor wafer opposite the surface having the bumps (bump-forming surface) after the first protective film forming step, bringing the ground surface to the grooves filled with the first protective film (exposing the grooves on the opposite surface), and dividing the semiconductor wafer to produce a group of semiconductor chips integrated with the first protective film filled in the grooves; a cutting step of cutting the first protective film after the dividing step; and a mounting step of flip-chip connecting the semiconductor chips with the first protective film, obtained after the dividing and cutting steps, to a substrate at the tops of the bumps, the semiconductor chips having the first protective film and the first protective film provided on the surface and side surfaces having the bumps of the semiconductor chips.

Among the variations of the manufacturing method of the semiconductor device of this embodiment, a manufacturing method in which the first protective film-forming film is non-curable (sometimes referred to in this specification as "manufacturing method (4)") uses a semiconductor wafer having grooves formed on its bump-bearing surface (bump-forming surface) that will serve as dividing points for the semiconductor wafer, and includes the steps of: attaching the first protective film-forming film in the first protective film-forming sheet to the bump-bearing surface of the semiconductor wafer, causing the tops of the bumps to protrude from the first protective film-forming film, and filling the grooves with the first protective film-forming film, thereby providing the first protective film-forming sheet on the semiconductor wafer; and, after the attaching step, removing layers of the first protective film-forming sheet other than the first protective film-forming film from the first protective film-forming film, and removing the first protective film-forming film after removing the layers other than the first protective film-forming film. The method includes a first protective film forming step of forming the first protective film on the surface having the bumps (bump-forming surface) by treating a film as a first protective film; a dividing step of grinding the surface (back surface) of the semiconductor wafer opposite the surface having the bumps (bump-forming surface) after the first protective film forming step, bringing the ground surface to the grooves filled with the first protective film (exposing the grooves on the opposite surface), and dividing the semiconductor wafer to produce a group of semiconductor chips integrated with the first protective film filled in the grooves; a cutting step of cutting the first protective film after the dividing step; and a mounting step of flip-chip connecting the semiconductor chips with the first protective film, obtained after the dividing and cutting steps, to a substrate at the tops of the bumps, the semiconductor chips having the first protective film and the first protective film provided on the surface and side surfaces of the semiconductor chips having the bumps.

The bonding step in the above-mentioned modified examples (manufacturing method (3) and manufacturing method (4)) can be performed in the same manner as the bonding step in the manufacturing methods (manufacturing method (1) and manufacturing method (2)) that use a semiconductor wafer that does not have any grooves formed thereon, except that the semiconductor wafer that uses the above-mentioned grooves further has the grooves formed on its bump-forming surface.
The first protective film forming step in the above-described modified examples (manufacturing method (3) and manufacturing method (4)) can be performed in the same manner as the first protective film forming step in the manufacturing methods (manufacturing method (1) and manufacturing method (2)) that use a semiconductor wafer without grooves.
The dividing step of the above-mentioned modified examples (manufacturing method (3) and manufacturing method (4)) can be performed in the same manner as the dividing step of the manufacturing methods (manufacturing method (1) and manufacturing method (2)) that use semiconductor wafers without grooves, except that the method of dividing the semiconductor wafer is limited to the specific method of grinding the back surface of the semiconductor wafer.
The cutting step in the above-mentioned modified examples (manufacturing method (3) and manufacturing method (4)) can be performed, for example, by attaching a dicing sheet to the surface (back surface) of all semiconductor chips opposite to the surface having the bumps (bump-forming surface), and then cutting the first protective film filled in the grooves along the side surfaces of the semiconductor chips at a location near the center in the width direction of the groove. In this way, the first protective film is cut between the side surfaces of adjacent semiconductor chips, and semiconductor chips with the first protective film provided on these side surfaces are obtained. Cutting of the first protective film in this case can be performed by a known method.
The mounting step of the above-described modified examples (manufacturing method (3) and manufacturing method (4)) can be performed in the same manner as the mounting step of the manufacturing method (manufacturing method (1) and manufacturing method (2)) that uses a semiconductor wafer without grooves.

The present invention will be described in more detail below using specific examples. However, the present invention is not limited to the examples shown below.

<Materials for producing the composition for forming the first protective film>
The raw materials used in the production of the composition for forming the first protective film are shown below.
[Polymer component (A)]
(A)-1: Polyvinyl butyral having structural units represented by the following formulas (i)-1, (i)-2, and (i)-3 ("S-LEC BL-10" manufactured by Sekisui Chemical Co., Ltd., weight average molecular weight 25,000, glass transition temperature 59°C).

(wherein l ₁ is about 28, m ₁ is 1 to 3, and n ₁ is an integer from 68 to 74.)

[Epoxy resin (B1)]
(B1)-1: Liquid modified bisphenol A epoxy resin (manufactured by DIC Corporation, "Epiclon EXA-4850-150", molecular weight 900, epoxy equivalent 450 g/eq)
(B1)-2: Dicyclopentadiene-type epoxy resin (DIC Corporation, "Epicron HP-7200HH", epoxy equivalent: 254 to 264 g/eq)
[Thermal curing agent (B2)]
(B2)-1: O-cresol novolak resin (DIC Corporation, "Phenolite KA-1160")
[Curing accelerator (C)]
(C)-1: 2-phenyl-4,5-dihydroxymethylimidazole ("Curezol 2PHZ-PW" manufactured by Shikoku Chemicals Corporation)
[Filler (D)]
(D)-1: Spherical silica modified with epoxy groups ("Admanano YA050C-MKK" manufactured by Admatechs Co., Ltd., average particle size 50 nm)
[Additive (I)]
(I)-1: Surfactant (acrylic polymer, "BYK-361N" manufactured by BYK Corporation)
(I)-2: Silicone oil (aralkyl-modified silicone oil, "XF42-334" manufactured by Momentive Performance Materials Japan, Inc.)

[Example 1]
<<Production of Sheet for Forming First Protective Film>>
<Production of Thermosetting First Protective Film-Forming Composition>
Polymer component (A)-1 (100 parts by mass), epoxy resin (B1)-1 (290 parts by mass), epoxy resin (B1)-2 (220 parts by mass), (B2)-1 (160 parts by mass), curing accelerator (C)-1 (2 parts by mass), filler (D)-1 (200 parts by mass), additive (I)-1 (25 parts by mass), and additive (I)-2 (3 parts by mass) were dissolved or dispersed in methyl ethyl ketone and stirred at 23°C to obtain composition (III) as a thermosetting first protective film-forming composition having a total concentration of all components other than the solvent of 45% by mass. Note that the blending amounts of all components other than the solvent shown here are the blending amounts of the target product excluding the solvent.

<Production of first protective film-forming film>
A release film ("SP-PET381031" manufactured by Lintec Corporation, thickness 38 μm) made of polyethylene terephthalate, one side of which had been treated for release by silicone treatment, was used, and the composition (III) obtained above was applied to the release-treated surface, followed by heating and drying at 120°C for 2 minutes to form a first protective film-forming film having a thickness of 45 μm.

<Production of buffer layer-forming composition>
Monofunctional urethane acrylate (40 parts by mass), isobornyl acrylate (45 parts by mass), 2-hydroxypropyl acrylate (15 parts by mass), pentaerythritol tetrakis(3-mercaptobutyrate) ("KARENZMT (registered trademark) PE1" manufactured by Showa Denko K.K., secondary tetrafunctional thiol group-containing compound, solids concentration 100% by mass) (3.5 parts by mass), crosslinker (1.8 parts by mass), and photopolymerization initiator (2-hydroxy-2-methyl-1-phenyl-propan-1-one, "DAROCURE (registered trademark) 1173" manufactured by BASF, solids concentration 100% by mass) (1.0 part by mass) were blended to produce composition (VI).

<Formation of buffer layer>
A PET film (Cosmoshine (registered trademark) A4300 manufactured by Toyobo Co., Ltd., thickness 75 μm) was used as the first substrate, and the composition (VI) obtained above was applied to one side of this first substrate to form a coating film. The coating film was irradiated with ultraviolet light from the outside of its exposed surface (the side opposite the PET film side) to form a semi-cured coating film. At this time, a belt conveyor-type ultraviolet irradiation device (Eye Graphics Co., Ltd., ECS-401GGX) was used as the ultraviolet irradiation device, and a high-pressure mercury lamp (Eye Graphics Co., Ltd., H04-L41) was used as the ultraviolet light source, and ultraviolet light having a wavelength of 365 nm was irradiated under conditions of an illuminance of 120 mW/cm ² and a light quantity of 200 mJ/cm ^2. These irradiation conditions were determined using an ultraviolet integrating illuminometer (Eye Graphics Co., Ltd., UVPF-A1).
Next, the release-treated surface of the release film ("SP-PET381031" manufactured by Lintec Corporation, thickness 38 μm) was bonded to the exposed surface of the obtained semi-cured product to produce a laminate, and this laminate was irradiated with ultraviolet light from the outside, from the release film side, to completely cure the semi-cured product, thereby forming a buffer layer with a thickness of 400 μm. At this time, using the same ultraviolet irradiation device and ultraviolet source as above, ultraviolet light with a wavelength of 365 nm was irradiated under conditions of an illuminance of 330 mW/cm ² and a light quantity of 1200 mJ/cm ^2. These irradiation conditions were determined using the same ultraviolet integrating illuminometer as above.
As a result, a laminated sheet (corresponding to the first laminated sheet) was obtained in which the first substrate, the buffer layer, and the release film were laminated in this order in the thickness direction.

<Production of intermediate release layer forming composition>
Ethylene-vinyl acetate copolymer (EVA, weight average molecular weight 55,000, VA content 20% by mass) was dissolved in toluene at room temperature to prepare a toluene solution with a solids concentration of 12% by mass, which was designated as composition (VII).

<Formation of intermediate release layer>
The composition (VII) obtained above was applied to the release-treated surface of the release film ("SP-PET381031" manufactured by Lintec Corporation, thickness 38 μm), and the applied film was dried by heating at 100°C for 2 minutes to form an intermediate release layer having a thickness of 10 μm.

<Production of Sheet for Forming First Protective Film>
In the laminate sheet (first laminate sheet) provided with the buffer layer obtained above, the release film was removed, and the exposed surface of the intermediate release layer obtained above was bonded to the exposed surface of the buffer layer thus obtained, thereby obtaining a laminate sheet (corresponding to the second laminate sheet) further laminated with an intermediate release layer. Next, the release film was removed from the intermediate release layer (in the second laminate sheet) after this bonding, and the exposed surface of the first protective film-forming film obtained above was bonded to the exposed surface of the intermediate release layer thus obtained.
As a result of the above, a first protective film forming sheet was obtained, which was constructed by stacking a first substrate (thickness 75 μm), a buffer layer (thickness 400 μm), an intermediate release layer (thickness 10 μm) and a first protective film forming film (thickness 45 μm) in this order in the thickness direction.

<<Evaluation of the sheet for forming the first protective film>>
<Measurement of Shear Storage Modulus (G _x ') of Intermediate Release Layer>
The exposed surface (the surface opposite to the intermediate release layer side) of the first protective film-forming film in the first protective film-forming sheet obtained above was pressed against the mirror surface of an 8-inch diameter semiconductor mirror wafer, thereby attaching the first protective film-forming sheet to the mirror surface of the semiconductor mirror wafer. At this time, the attachment of the first protective film-forming sheet was performed while heating the first protective film-forming sheet using an attachment device (roller-type laminator, "RAD-3510 F/12" manufactured by Lintec Corporation) under conditions of a table temperature of 90°C, an attachment speed of 5 mm/s, an attachment pressure of 0.5 MPa, and a roller attachment height of -400 μm.

Next, the first protective film-forming film was left on the semiconductor mirror wafer, and the first substrate, buffer layer, and intermediate release layer were peeled off to obtain structure 2, which was composed of the first substrate, buffer layer, and intermediate release layer stacked together.

Thereafter, the intermediate release layer of Construct 2 was attached to the adhesive layer of an adhesive sheet (Adwill (registered trademark) D-210, manufactured by Lintec Corporation) which was formed by laminating an adhesive layer and a substrate.
Next, the structure 3 formed by laminating the first substrate and the buffer layer was peeled off to obtain a structure 4 formed by laminating the intermediate release layer, the adhesive layer and the substrate.

Furthermore, the adhesive layer and substrate of Construct 4 were peeled off, and multiple intermediate release layers alone were laminated to a thickness of 400 μm. These were then cut into circles with a diameter of 25 mm, yielding disk-shaped intermediate release layer test pieces with a diameter of 25 mm and a thickness of 400 μm.

The location where the test piece was to be placed on the shear viscosity measuring device (Anton Paar MCR301) was kept warm at 90°C in advance, and the test piece of the intermediate peel layer obtained above was placed on this location. The measuring jig was pressed against the top surface of the test piece to fix it in place.

Next, under conditions of a temperature of 90°C and a measurement frequency of 1 Hz, the generated shear strain was increased stepwise from 0.01% to 10%, and the shear storage modulus (G _x ') [Pa] of the test piece of the intermediate release layer at a shear strain of 1% was measured.

<Measurement of Shear Storage Modulus ( _GA ') of Buffer Layer>
The buffer layer of the structure 3 was cut into a circle having a diameter of 25 mm and peeled off from the first substrate to obtain a disk-shaped test piece of the buffer layer having a diameter of 25 mm and a thickness of 400 μm.

The location where the test piece was to be placed on the shear viscosity measuring device (Anton Paar MCR301) was preheated to 90°C, and the buffer layer test piece obtained above was placed on this location. The measuring jig was then pressed against the top surface of the test piece to secure it to the location.

Next, the generated shear strain was increased stepwise from 0.01% to 1000% under conditions of a temperature of 90°C and a measurement frequency of 1 Hz, and the shear storage modulus (G _A ') [Pa] of the test piece of the buffer layer at a shear strain of 1% was measured.

<Calculation of the ratio (G _{x '} /G _A ') of the shear storage modulus (G _x ') of the intermediate release layer to the shear storage modulus (G A ') of the buffer layer>
The ratio (G _x '/G A ') of the shear storage modulus (G _{x ') of the intermediate release layer to the shear storage modulus (G A} ') of the buffer layer was determined by dividing the value of the shear storage modulus (G _x ') [Pa] of the test piece of the intermediate release layer by the value of the shear storage modulus ( _{G A} ') [ _Pa ] of the test piece of the buffer layer.

<Evaluation of Bump Penetration of First Protective Film-Forming Film (Confirmation of Thickness of Adherent Material of First Protective Film on Top of Bump)>
The exposed surface (the surface opposite to the intermediate release layer) of the first protective film-forming film in the first protective film-forming sheet obtained above was pressed against the bump-forming surface of an 8-inch diameter semiconductor wafer having bumps, thereby attaching the first protective film-forming sheet to the bump-forming surface of the semiconductor wafer. The semiconductor wafer used had bumps with a height of 210 μm, a width of 250 μm, and a distance between bumps of 400 μm. The first protective film-forming sheet was attached while being heated using an attachment device (a roller-type laminator, manufactured by Lintec Corporation, model RAD-3510 F/12) under conditions of a table temperature of 90° C., an attachment speed of 5 mm/s, an attachment pressure of 0.5 MPa, and a roller attachment height of −400 μm.

Next, the back surface of the semiconductor wafer was ground using a grinding machine (DFG8760 manufactured by Disco) to reduce the thickness of the semiconductor wafer to 250 μm.
Next, using a multi-wafer mounter ("RAD-2700 F/12" manufactured by Lintec Corporation), the first substrate, the buffer layer, and the intermediate release layer were removed from the first protective film-forming film to expose the first protective film-forming film. Then, the first protective film-forming film was heated at 130°C for 4 hours to form a first protective film.

Next, a dicing sheet (dicing tape "Adwill D-686H" manufactured by Lintec Corporation) was attached to the back surface (ground surface) of the semiconductor wafer, and using a blade dicer ("DFD6362" manufactured by Disco Corporation) and a dicing blade ("ZH05-SD2000-N1-90CC" manufactured by Disco Corporation), the semiconductor wafer was divided into semiconductor chips measuring 6 mm x 6 mm at a blade rotation speed of 30,000 rpm and a blade feed speed of 30 mm/s, and at the same time, the first protective film was cut to the same size.
As a result of the above, a group of semiconductor chips with a first protective film was obtained, which was composed of a large number (plurality) of semiconductor chips with a first protective film, each of which had a semiconductor chip and a first protective film provided on the bump formation surface of the semiconductor chip, aligned and held on a dicing sheet.

From the group of semiconductor chips with first protective film obtained above, one location in the center and four locations near the periphery that are equally spaced from each other were selected, with the direction connecting the two locations near the periphery and the one location in the center being aligned with the direction in which the first protective film forming sheet was attached. One semiconductor chip with first protective film was taken out from each of these five locations, for a total of five.

Next, using a scanning electron microscope (SEM, Keyence Corporation "VE-9700"), the bump surfaces of these semiconductor chips with first protective film were observed from a direction forming a 60° angle with the direction perpendicular to the bump-forming surface of the semiconductor chip with first protective film, and the presence or absence of adhesion of the first protective film on the top of the bumps was confirmed. Each of these five semiconductor chips with first protective film contained eight bumps, meaning that the surfaces of a total of 40 bumps were observed. The reason for observing the bump surfaces of the semiconductor chips with first protective film from the direction forming the 60° angle described above is that this method makes it easiest to identify the first protective film remaining on the top of the bumps.

Next, each of these five semiconductor chips with the first protective film was sealed with epoxy resin, and the sealed chip was polished using an abrasive sheet until the cross section of the center of the bump inside became visible. The cross section was observed using a field emission scanning electron microscope (FE-SEM, Hitachi High-Technologies Corporation, S-4700), and the thickness of the first protective film deposits on the top of the bumps was measured, with the maximum value being used as the thickness of the deposits. The amount (thickness) of the first protective film deposits on the top of the bumps reflects the amount of remaining first protective film on the top of the bumps, and therefore serves as an indicator for evaluating the bump penetration ability of the first protective film-forming film. The results are shown in Table 1.

<<Production and Evaluation of Sheet for Forming First Protective Film>>
[Example 2]
A sheet for forming a first protective film was produced and evaluated in the same manner as in Example 1, except that an ethylene-vinyl acetate copolymer (EVA, weight average molecular weight 65,000, VA content 28% by mass) was used instead of an ethylene-vinyl acetate copolymer (EVA, weight average molecular weight 55,000, VA content 20% by mass) when producing the composition for forming an intermediate release layer (composition (VII)). The results are shown in Table 1.

[Example 3]
A sheet for forming a first protective film was produced and evaluated in the same manner as in Example 1, except that an ethylene-vinyl acetate copolymer (EVA, weight average molecular weight 150,000, VA content 32% by mass) was used instead of an ethylene-vinyl acetate copolymer (EVA, weight average molecular weight 55,000, VA content 20% by mass) when producing the composition for forming an intermediate release layer (composition (VII)). The results are shown in Table 1.

<<Production and Evaluation of Sheet for Forming First Protective Film>>
[Example 4]
<Production of intermediate release layer forming composition>
An energy ray-curable acrylic polymer (weight average molecular weight 750,000) was obtained by using an acrylic copolymer obtained by copolymerizing n-butyl acrylate (52 parts by mass), methyl methacrylate (20 parts by mass), and 4-hydroxybutyl acrylate (28 parts by mass), and adding 2-isocyanatoethyl methacrylate ("Karenz MOI (registered trademark)" manufactured by Showa Denko K.K.) to the acrylic copolymer so that the addition ratio relative to the hydroxyl groups (100 equivalents) of the structural units derived from 4-hydroxybutyl acrylate in the acrylic copolymer was 90 equivalents.

Methyl ethyl ketone was added to this acrylic polymer to prepare a liquid with an acrylic polymer concentration of 20% by mass, and this liquid was stirred for 30 minutes to prepare a solution composition (VII).

<Formation of intermediate release layer>
The release film ("SP-PET381031" manufactured by Lintec Corporation, thickness 38 μm) was used, and the composition (VII) obtained above was applied to the release-treated surface thereof, followed by heating and drying at 100°C for 2 minutes, thereby forming an intermediate release layer having a thickness of 10 μm.

<Production of Sheet for Forming First Protective Film>
A first protective film-forming sheet was produced in the same manner as in Example 1, except that the intermediate release layer was used.

<<Production of Sheet for Forming First Protective Film>>
[Comparative Example 1]
<Production of Pressure-Sensitive Adhesive Composition>
An acrylic copolymer obtained by copolymerizing 2-ethylhexyl acrylate (82 parts by mass) and 2-hydroxyethyl acrylate (18 parts by mass) was used, and 2-isocyanatoethyl methacrylate ("Karenz MOI (registered trademark)" manufactured by Showa Denko K.K.) was added to the acrylic copolymer so that the addition ratio relative to the hydroxyl groups (100 equivalents) of the structural units derived from 2-hydroxyethyl acrylate in the acrylic copolymer was 66 equivalents, thereby obtaining an acrylic polymer (weight average molecular weight 800,000).

To this acrylic polymer (100 parts by mass), 1-hydroxycyclohexyl phenyl ketone (photopolymerization initiator, BASF's "Irgacure® 184") (3 parts by mass) and trimethylolpropane adduct tolylene diisocyanate (crosslinking agent, Tosoh's "Coronate® L") (1.0 part by mass) were added, and a liquid was prepared using methyl ethyl ketone. This liquid was stirred for 30 minutes to prepare a pressure-sensitive adhesive composition in solution form with a solids concentration of 20% by mass.

The adhesive composition obtained above was applied to the release-treated surface of the release film ("SP-PET381031" manufactured by Lintec Corporation, thickness 38 μm) and then dried by heating at 120°C for 2 minutes to form an adhesive layer 10 μm thick.

A sheet for forming a first protective film was produced in the same manner as in Example 1, except that the adhesive layer obtained above was used instead of the intermediate release layer.

[Comparative Example 2]
<Production of Pressure-Sensitive Adhesive Composition>
An acrylic polymer (weight average molecular weight 800,000) was obtained by adding 2-isocyanatoethyl methacrylate ("Karenz MOI (registered trademark)" manufactured by Showa Denko K.K.) to an acrylic copolymer obtained by copolymerizing 2-ethylhexyl acrylate (80 parts by mass) and 2-hydroxyethyl acrylate (20 parts by mass) in an amount of 80 equivalents to the hydroxyl groups (100 equivalents) of the structural units derived from 2-hydroxyethyl acrylate in the acrylic copolymer.

To this acrylic polymer (100 parts by mass), 1-hydroxycyclohexyl phenyl ketone (photopolymerization initiator, BASF's "Irgacure® 184") (3 parts by mass) and trimethylolpropane adduct tolylene diisocyanate (crosslinking agent, Tosoh's "Coronate® L") (1.5 parts by mass) were added, and a liquid was prepared using methyl ethyl ketone. This liquid was stirred for 30 minutes to prepare a pressure-sensitive adhesive composition in solution form with a solids concentration of 20% by mass.

The adhesive composition obtained above was applied to the release-treated surface of the release film ("SP-PET381031" manufactured by Lintec Corporation, thickness 38 μm) and then dried by heating at 100°C for 2 minutes to form an adhesive layer 10 μm thick.

A sheet for forming a first protective film was produced in the same manner as in Example 1, except that the adhesive layer obtained above was used instead of the intermediate release layer.

<<Evaluation of the sheet for forming the first protective film>>
The sheets for forming a first protective film of Comparative Examples 1 and 2 obtained above were evaluated in the same manner as in Example 1. The results are shown in Table 1.

As is clear from the above results, in Examples 1 to 4, the first protective film-forming sheet was successfully applied to the bump-forming surface of the semiconductor wafer at an application speed of 5 mm/s using the first protective film-forming film therein, demonstrating high-speed application properties. Even when applied at such high speeds, the thickness of the first protective film deposits on the tops of the bumps was 0.7 μm or less (0.1 to 0.7 μm), preventing the first protective film from adhering to the tops of the bumps. In other words, in Examples 1 to 4, even when the first protective film-forming sheet was applied to the bump-forming surface of the semiconductor wafer at high speed, the tops of the bumps were able to protrude from the protective film-forming film, preventing the first protective film from remaining on the tops of the bumps. Thus, in Examples 1 to 4, both the high-speed application properties of the first protective film-forming sheet and the bump penetration properties of the first protective film-forming film were high.

The first protective film-forming sheets of Examples 1 to 3 had an intermediate release layer containing an ethylene-vinyl acetate copolymer. The first protective film-forming sheets of Examples 1 to 3 had a smaller ratio (G _x '/G _A ') and a thinner deposit of the first protective film on the top of the bump than the first protective film-forming sheet of Example 4 containing an acrylic polymer. The first protective film-forming sheets of Examples 1 to 3 had higher bump penetration properties for the first protective film-forming film than the first protective film-forming sheet of Example 4 containing an acrylic polymer.
From the results of Examples 1 to 3, it was confirmed that the bump penetration ability of the first protective film-forming film tends to increase as the VA content of the ethylene-vinyl acetate copolymer decreases and as the weight average molecular weight of the ethylene-vinyl acetate copolymer decreases.

In contrast, when the first protective film-forming sheet of Comparative Example 1 or 2 was applied at a bonding speed of 5 mm/s using the first protective film-forming film therein, the thickness of the deposit of the first protective film on the top of the bump was 1.5 μm or 1.3 μm, and the adhesion of the first protective film on the top of the bump was not suppressed. That is, in Comparative Examples 1 and 2, when the first protective film-forming sheet was applied to the bump-forming surface of the semiconductor wafer at a bonding speed of 5 mm/s, the remaining of the first protective film-forming film on the top of the bump was not suppressed. Thus, in Comparative Examples 1 and 2, the first protective film-forming sheet did not have high-speed bonding properties, and the bump penetration ability of the first protective film-forming film was also low.
The first protective film-forming sheets of Comparative Examples 1 and 2 were provided with a pressure-sensitive adhesive layer containing an acrylic polymer, rather than an intermediate release layer containing an ethylene-vinyl acetate copolymer.

The present invention can be used to manufacture semiconductor chips for use in flip-chip connection methods, such as semiconductor chips that have bumps and a protective film on the bump-forming surface.

1: First protective film forming sheet, 11: First substrate, 12: Buffer layer, 13: Intermediate release layer, 14: First protective film forming film, 14': First protective film, 140': First protective film after cutting, 9: Semiconductor wafer, 9a: Bump-forming surface of semiconductor wafer (surface having bumps on semiconductor wafer), 90: Semiconductor chip, 90a: Bump-forming surface of semiconductor chip (surface having bumps on semiconductor chip), 91: Bump, 9101: Top of bump, 9140': Semiconductor chip with first protective film

Claims (8)

A first protective film forming sheet for forming a first protective film on at least a surface of a semiconductor wafer having bumps,
The sheet is configured by laminating a first substrate, a buffer layer, an intermediate release layer, and a first protective film-forming film in this order in a thickness direction,
The first protective film-forming sheet, wherein the ratio (G _x '/G _A ') of the shear storage modulus (G _x ') of the intermediate release layer to the shear storage modulus (G _A ') of the buffer layer is less than 0.6. The sheet for forming a first protective film according to claim 1, wherein the intermediate release layer contains an ethylene-vinyl acetate copolymer. The sheet for forming a first protective film according to claim 2, wherein the proportion of structural units derived from vinyl acetate relative to the total amount of structural units in the ethylene-vinyl acetate copolymer is 16 to 40 mass%. The sheet for forming a first protective film according to claim 2 or 3, wherein the weight-average molecular weight of the ethylene-vinyl acetate copolymer is 200,000 or less. 5. The first protective film-forming sheet according to claim 1, wherein the intermediate release layer has a shear storage modulus (G _x ') of 10,000 Pa or less. A method for manufacturing a semiconductor device using the sheet for forming a first protective film according to any one of claims 1 to 5,
The manufacturing method includes a bonding step of bonding the first protective film-forming film in the first protective film-forming sheet to a surface of a semiconductor wafer having bumps, and causing tops of the bumps to protrude from the first protective film-forming film, thereby providing the first protective film-forming sheet on the semiconductor wafer;
a first protective film forming step of removing layers of the first protective film-forming sheet other than the first protective film-forming film from the first protective film-forming film after the attaching step, and further, if the first protective film-forming film is curable, curing the first protective film-forming film to form a first protective film, or, if the first protective film-forming film is non-curable, treating the first protective film-forming film after removing layers other than the first protective film-forming film as a first protective film, thereby forming the first protective film on the surface having the bumps;
a dividing step of dividing the semiconductor wafer into semiconductor chips after the first protective film forming step;
a cutting step of cutting the first protective film after the first protective film forming step;
a mounting step of flip-chip connecting the semiconductor chip with the first protective film, which is provided with the semiconductor chip obtained after the dividing step and the cutting step, and the first protective film provided on the surface of the semiconductor chip having the bumps, and in which the tops of the bumps protrude from the first protective film, to a substrate at the tops of the bumps. The method for manufacturing a semiconductor device according to claim 6, wherein, in the bonding step, the first protective film-forming film is bonded to the bump-bearing surface of the semiconductor wafer at a bonding speed of 4 mm/s or more. Use of a sheet for forming a first protective film on at least a bump-bearing surface of a semiconductor wafer, comprising:
The sheet is configured by laminating a first substrate, a buffer layer, an intermediate release layer, and a first protective film-forming film in this order in a thickness direction,
Use of a sheet, wherein the ratio (G _x '/G _A ') of the shear storage modulus (G _x ') of the intermediate release layer to the shear storage modulus (G _A ') of the buffer layer is less than 0.6.