JP7680233B2 - Protective film-forming film, composite sheet for protective film-forming film, and method for recycling wafer - Google Patents

Description

The present invention relates to a protective film forming film, a composite sheet for forming a protective film, and a method for recycling wafers.

Some wafers, such as semiconductor wafers and insulator wafers, have circuits formed on one surface (circuit surface) and further have protruding electrodes such as bumps on that surface (circuit surface). Such wafers are divided into chips, and the protruding electrodes are connected to connection pads on a circuit board, thereby mounting the chips on the circuit board.
In such wafers and chips, the surface opposite the circuit surface (back surface) may be protected with a protective film in order to prevent damage such as cracks.

To form such a protective film, a protective film-forming film for forming the protective film is attached to the back surface of the wafer. The protective film-forming film is laminated on a support sheet for supporting it, and may be used in the form of a composite sheet for forming a protective film, or may be used without being laminated on a support sheet (see Patent Document 1). The wafer with the protective film-forming film on its back surface is then processed into a chip with a protective film on its back surface (chip with protective film) through various subsequent processes. After being picked up, such a chip with protective film is mounted on a circuit board to form various board devices (e.g., semiconductor device).

When the protective film-forming film is applied to the back surface of the wafer, there is a possibility that an abnormality in application may occur, such as, for example, the application position of the protective film-forming film being misaligned, or the protective film-forming film being applied with a foreign object sandwiched between the back surface of the wafer and the application surface of the protective film-forming film. A wafer with such an abnormality in application is not suitable for use in a subsequent process. If a wafer with an abnormality in application is discarded, the manufacturing cost of a chip or a substrate device with a protective film increases because the wafer is expensive. Therefore, if it is possible to peel off the protective film-forming film from a wafer with an abnormality in application and then apply a separately prepared protective film to the back surface of the wafer again, it would be highly useful. In this field, for the purpose of re-application of such a protective film-forming film, a protective film-forming film that can be attached to the back surface of the wafer and then peeled off from the back surface to restore the back surface of the wafer to a state in which the protective film-forming film can be re-application has been studied. A protective film-forming film has been disclosed in which the surface roughness (Ra) of the surface that is attached to the wafer is equal to or greater than a certain value (see Patent Document 2).

International Publication No. 2015/111632 International Publication No. 2016/158727

The thickness of a wafer when in use is usually adjusted by grinding its back surface. The back surface of the wafer is first roughly ground using a grinder, for example, and then finish ground to achieve a high degree of smoothness. Recently, however, in order to shorten the grinding time, finish grinding has been omitted, and wafers with a rough ground surface are being used.

On such a rough ground surface (back surface), there are many recesses that are deep and large in size. When applying a protective film-forming film to the back surface of such a wafer, it is necessary to fully fill the recesses with the protective film-forming film. If this is not done, after forming a protective film from the protective film-forming film, the adhesive strength between the protective film and the wafer or chip will be low, and the reliability of the final substrate device may be low. Therefore, in order to avoid such problems, when applying a protective film-forming film to the rough back surface of a wafer, the temperature and pressure when applying the protective film-forming film are made higher than usual, and the speed is made slower, so that the recesses are fully filled with the protective film-forming film.

However, when an abnormality occurs when the protective film-forming film is applied in this manner, the protective film-forming film is sufficiently embedded in the recesses, making it difficult to peel the protective film-forming film from the wafer and making it difficult to reapply the protective film-forming film. The protective film-forming films disclosed in Patent Documents 1 and 2 are not intended to solve such problems.

The present invention aims to provide a protective film-forming film for forming a protective film on the back surface of a chip, which is attached to the back surface of a wafer before it is divided into chips, and which, when peeled from the back surface of the wafer for re-attachment, can be easily peeled off even if the back surface of the wafer is rough, and can restore the back surface of the wafer to a state in which the protective film-forming film can be re-attached; a composite sheet for forming a protective film that includes the protective film-forming film; and a method for regenerating a wafer using the protective film-forming film or the composite sheet for forming a protective film.

The present invention provides a protective film-forming film, in which a test piece which is a laminate of a plurality of the protective film-forming films is held at two points spaced 30 mm apart, and the test piece is pulled between the two points in a direction parallel to its surface at a speed of 1000 mm/min, and a tensile test is performed to measure the stress generated in the test piece and the strain of the test piece in the tensile direction, wherein the strain when the stress first reaches 0.1 N/ ^mm2 is 0.5% or more, and the strain when the stress first reaches 0.6 N/ ^mm2 is 200% or less.

In the protective film-forming film of the present invention, it is preferable that the test piece does not break until the strain reaches 350% in the tensile test.
The protective film-forming film of the present invention is preferably curable.
The protective film-forming film of the present invention is preferably thermosetting.

The present invention also provides a composite sheet for forming a protective film, comprising a support sheet and a protective film-forming film provided on one side of the support sheet, wherein the protective film-forming film is the protective film-forming film of the present invention described above.
The present invention also provides a method for regenerating a wafer, comprising attaching the protective film-forming film of the present invention described above, or the protective film-forming film in the composite sheet for forming a protective film of the present invention described above, to the rear surface of a wafer, and then peeling the protective film-forming film from the rear surface of the wafer to make the rear surface of the wafer in a state in which the protective film-forming film can be reattached, thereby regenerating the wafer.

According to the present invention, there are provided a protective film-forming film for forming a protective film on the back surface of a chip, which is attached to the back surface of a wafer before it is divided into chips, and which, when peeled from the back surface of the wafer for re-attachment, can be easily peeled even if the back surface of the wafer is rough, and can restore the back surface of the wafer to a state in which the protective film-forming film can be re-attached; a composite sheet for forming a protective film that includes the protective film-forming film; and a method for regenerating a wafer using the protective film-forming film or the composite sheet for forming a protective film.

1 is a cross-sectional view showing a schematic example of a protective film-forming film according to an embodiment of the present invention. 1 is a cross-sectional view showing a schematic example of a composite sheet for forming a protective film according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a schematic diagram of another example of a composite sheet for forming a protective film according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a schematic diagram of still another example of the composite sheet for forming a protective film according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing a schematic diagram of still another example of the composite sheet for forming a protective film according to one embodiment of the present invention. 1A to 1C are cross-sectional views for illustrating an example of a method for recycling a wafer and an example of a method for reattaching a protective film-forming film according to an embodiment of the present invention. 10A to 10C are cross-sectional views for illustrating a schematic diagram of another example of a method for recycling a wafer according to an embodiment of the present invention and an example of a method for reattaching a protective film-forming film.

◇Protective Film-Forming Film The protective film-forming film according to one embodiment of the present invention is a film used to provide a protective film on a chip to protect the chip. When a test piece, which is a laminate of multiple protective film-forming films, is held at two points spaced 30 mm apart, and the test piece is pulled between the two points in a direction parallel to its surface at a speed of 1000 mm/min, and a tensile test is performed to measure the stress generated in the test piece and the strain of the test piece in the tensile direction, the strain (sometimes abbreviated in this specification as "strain (0.1 N/mm ² )") when the stress first reaches 0.1 N/mm ² is 0.5% or more, and the strain (sometimes abbreviated in this specification as "strain (0.6 N/mm ² )") when the stress first reaches 0.6 N/mm ² is 200% or less.
The protective film-forming film of this embodiment can be laminated with a support sheet to form a composite sheet for forming a protective film, for example, as described below.

By using the protective film-forming film of this embodiment, or a composite sheet for forming a protective film comprising the same, a chip with a protective film can be manufactured, comprising a chip and a protective film provided on the back surface of the chip.
The chip with a protective film can be manufactured, for example, by attaching a protective film-forming film to the back surface of a wafer, forming a protective film by hardening the protective film-forming film, dividing the wafer into chips, and cutting the protective film along the outer periphery of the chip.

In this specification, the term "wafer" refers to a semiconductor wafer made of an elemental semiconductor such as silicon, germanium, or selenium, or a compound semiconductor such as GaAs, GaP, InP, CdTe, ZnSe, or SiC; or an insulating wafer made of an insulator such as sapphire, glass, lithium niobate, or lithium tantalate.
A circuit is formed on one surface of each of these wafers, and in this specification, the surface of the wafer on which the circuit is formed is referred to as the "circuit surface," and the surface of the wafer opposite to the circuit surface is referred to as the "back surface."
The wafer is divided into chips by dicing or other means. In this specification, as in the case of the wafer, the surface of the chip on which the circuit is formed is referred to as the "circuit surface," and the surface of the chip opposite the circuit surface is referred to as the "back surface."
It is preferable that both the circuit surface of the wafer and the circuit surface of the chip are provided with protruding electrodes such as bumps, pillars, etc. The protruding electrodes are preferably made of solder.

Furthermore, by using the chip with the protective film, a substrate device can be manufactured.
In this specification, the term "substrate device" refers to a device in which a chip with a protective film is flip-chip connected to a connection pad on a circuit board at a protruding electrode on the circuit surface of the chip. For example, when a semiconductor wafer is used as the wafer, a semiconductor device is an example of the substrate device.

The rough back surface (ground surface) of the wafer has many deep and large recesses. When attaching the protective film-forming film to the back surface of such a wafer, it is necessary to fully fill the recesses with the protective film-forming film. By attaching in this manner, after forming a protective film from the protective film-forming film, a high adhesive strength can be maintained between the protective film and the wafer or chip, and the reliability of the finally obtained substrate device is increased.
On the other hand, when the protective film-forming film is attached to the back surface of the wafer, there is a possibility that an attachment error may occur. A wafer with such an attachment error is inappropriate to use as it is, and if it is discarded, the manufacturing cost of chips and substrate devices with protective film increases because the wafer is expensive. Therefore, it is desirable to peel off the protective film-forming film from the wafer with the attachment error and attach the protective film-forming film again to the back surface of the wafer.
However, typically, when a protective film forming film is attached to the rough back surface of a wafer and the protective film forming film is sufficiently embedded in the recesses on the back surface, it can become difficult to peel the protective film off the wafer and difficult to re-attach the protective film.

In contrast, the protective film-forming film of this embodiment has the above-described distortion characteristics, and when peeled off from the back surface of the wafer for the purpose of re-attachment after being attached to the back surface of the wafer, it peels off normally and easily even if the back surface of the wafer is rough. Therefore, the protective film-forming film of this embodiment can regenerate the wafer by making the back surface of the wafer in a state in which the protective film-forming film can be re-attached. In this specification, the characteristic of the protective film-forming film that allows the wafer to be regenerated in this way is sometimes referred to as "suitability for wafer regeneration."

In this field, "recycling" a wafer is sometimes called "rework."

The protective film-forming film of this embodiment may function as a protective film by being cured, or may function as a protective film in an uncured state. The protective film-forming film that functions as a protective film in an uncured state can be considered to have formed a protective film, for example, when it is attached to the desired location on the wafer.

The protective film-forming film of the present embodiment may be either curable or non-curable.
The curable protective film-forming film of the present embodiment may be either thermosetting or energy ray curable, or may have both thermosetting and energy ray curable properties.
The protective film-forming film of the present embodiment may be non-energy ray curable.

In this specification, the term "energy rays" refers to electromagnetic waves or charged particle beams having an energy quantum, and examples thereof include ultraviolet rays, radiation, electron beams, etc. Ultraviolet rays can be irradiated by using, for example, a high-pressure mercury lamp, a fusion lamp, a xenon lamp, a black light, an LED lamp, etc. as an ultraviolet ray source. Electron beams can be irradiated by generating them using an electron beam accelerator, etc.
In this specification, "energy ray curable" means a property that is cured by irradiation with energy rays, and "non-energy ray curable" means a property that is not cured even when irradiated with energy rays.
In this specification, the term "non-curable" refers to a property that does not cure by any means, such as heating or irradiation with energy rays.

When the protective film-forming film is thermally cured to form a protective film, unlike the case of curing by irradiation with energy rays, the protective film-forming film can be sufficiently cured by heating even if it is thick, so that a protective film with high protective performance can be formed. In addition, by using a normal heating means such as a heating oven, a large number of protective film-forming films can be heated and thermally cured at the same time.
When the protective film-forming film is cured by irradiation with energy rays to form a protective film, unlike the case of thermal curing, the composite sheet for forming a protective film does not need to have heat resistance, and a wide range of composite sheets for forming a protective film can be formed. In addition, the composite sheet can be cured in a short time by irradiation with energy rays.
When the protective film-forming film is used as the protective film without being cured, the curing step can be omitted, and therefore a chip with a protective film can be manufactured by a simplified process.

In order to form a protective film with higher protective performance, the protective film-forming film is preferably curable, and more preferably thermosetting.

The protective film-forming film may consist of one layer (single layer) or may consist of two or more layers. When the protective film-forming film consists of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited.

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

The tensile test is carried out by laminating a plurality of the protective film-forming films to prepare a laminate, and using the laminate as a test piece. More specifically, the test piece is held at two points with an interval of 30 mm, and the test piece is pulled between the two points in a direction parallel to its surface (exposed surface of the outermost layer) at a speed of 1000 mm/min, and the stress generated in the test piece and the strain of the test piece in the tensile direction (direction connecting the two points) are measured.
Holding the test piece at two points 30 mm apart means that when a tensile test is performed, the length of the portion of the test piece that can be stretched in the tensile direction is 30 mm before the tensile test is performed, and this length is the length of the portion of the test piece that is subject to the tensile test.

As described above, when the test piece is held at two points with an interval of 30 mm, the length of the test piece in the tensile direction is taken as the reference, and the test piece is pulled to elongate by ΔL mm. The strain of the test piece is calculated by the following formula:
Strain of test piece (%) = ΔL (mm) / 30 (mm) x 100
It is calculated as follows.

The thickness of the test piece (laminate) is not particularly limited as long as it does not interfere with the performance of the tensile test and does not impair the measurement accuracy of the stress and strain.
Generally, the thickness of the test piece is preferably 190 to 210 μm, more preferably 195 to 205 μm, and particularly preferably 200 μm.

The test piece can be held at the two points using a holding means such as a known gripping tool.

The number of protective film-forming films constituting the test piece is not particularly limited as long as it is two or more, and can be arbitrarily selected depending on the thickness of each protective film-forming film.
For example, when preparing a test piece having a thickness of 200 μm, the test piece can be more easily prepared by using five protective film-forming films having a thickness of 40 μm. However, this is only an example, and the number and thickness of the protective film-forming films to be used are not limited to this.

The width of the test piece (the length in the direction perpendicular to the direction connecting the two points) is not particularly limited as long as it does not impair the accuracy of the tensile test, and may be, for example, 10 to 20 mm, and is particularly preferably 15 mm.

In the present invention, "when the stress first reaches 0.1 N/ ^mm2 " means when the above-mentioned tensile test is performed, the stress increases from the start of the test and the stress first reaches 0.1 N/ ^mm2 . Therefore, even if the test piece shows a yield phenomenon in the tensile test and the stress decreases to 0.1 N/ ^mm2 , this does not fall under "when the stress first reaches 0.1 N/ ^mm2 ". The same applies to "when the stress first reaches 0.6 N/mm2 ^" .

The strain (0.1 N/mm ² ) is 0.5% or more, and may be, for example, any of 0.7% or more, 1% or more, 1.3% or more, 1.7% or more, and 2% or more. When the strain (0.1 N/mm ² ) is equal to or more than the lower limit, even if the back surface of the wafer is rough, the protective film-forming film is peeled off normally and easily in the initial stage of peeling the protective film-forming film from the back surface of the wafer. For example, in this initial stage, excessive external force is not applied to the wafer, and damage to the wafer is suppressed. More specifically, even if the back surface of the wafer is rough and the protective film-forming film is embedded in a deep and large recess, in the initial stage of peeling the protective film-forming film from the back surface of the wafer, a starting point for extracting the protective film-forming film from the recess while deforming it with a small force can be created. This allows the protective film-forming film to start peeling off normally and easily from the back surface of the wafer. On the other hand, when the protective film-forming film is difficult to deform, it is difficult to create a starting point for pulling out the protective film-forming film from the recess. In addition, by making the strain (0.1 N/mm ² ) equal to or greater than the lower limit, unintended release of the fixed state of the wafer (e.g., the state of being adsorbed and fixed under vacuum conditions) is suppressed. In addition, unintended peeling of the peel tape, which is attached to the protective film-forming film for peeling the protective film, from the protective film-forming film is suppressed.

The upper limit of the strain (0.1 N/mm ² ) is not particularly limited. For example, in the initial stage of peeling the protective film-forming film from the back surface of the wafer, the strain (0.1 N/mm ² ) is preferably 3% or less in order to more easily peel the protective film-forming film.

The strain (0.1 N/mm ² ) can be appropriately adjusted within a range set by any combination of any of the above-mentioned lower limit values and upper limit values. For example, in one embodiment, the strain (0.1 N/mm ² ) may be any of 0.5 to 3%, 0.7 to 3%, 1 to 3%, 1.3 to 3%, 1.7 to 3%, and 2 to 3%.

The strain (0.6 N/mm ² ) is 200% or less, and may be, for example, any of 100% or less, 20% or less, 10% or less, 7% or less, and 5% or less. By the strain (0.6 N/mm ² ) being equal to or less than the upper limit, even if the back surface of the wafer is rough, the protective film-forming film is peeled off normally and easily in the later stage of peeling the protective film-forming film from the back surface of the wafer. For example, in this later stage, cohesive failure of the protective film-forming film is suppressed, and the protective film-forming film is suppressed from remaining on the back surface of the wafer. More specifically, even if the back surface of the wafer is rough and the protective film-forming film is embedded in a deep and large recess, in the initial stage of peeling the protective film-forming film from the back surface of the wafer, as described above, even if the protective film-forming film is deformed so as to create a starting point for extracting the protective film from the recess, in the later stage of peeling the protective film-forming film from the back surface of the wafer, the continuation of the deformation of the protective film-forming film can be suppressed. This allows the protective film-forming film to start peeling off from the back surface of the wafer normally and easily. On the other hand, if the continuation of the deformation of the protective film-forming film cannot be suppressed (the deformation continues), a part of the deformed protective film-forming film is likely to remain on the back surface of the wafer.

The lower limit of the strain (0.6 N/mm ² ) is not particularly limited. For example, in the later stage of peeling the protective film-forming film from the back surface of the wafer, the strain (0.6 N/mm ² ) is preferably 1% or more in order to more easily peel the protective film-forming film from the back surface of the wafer.

The strain (0.6 N/mm ² ) can be appropriately adjusted within a range set by any combination of the above-mentioned lower limit value and any of the upper limits. For example, in one embodiment, the strain (0.6 N/mm ² ) may be any of 1 to 200%, 1 to 100%, 1 to 20%, 1 to 10%, 1 to 7%, and 1 to 5%.

Since the strain (0.1 N/ ^mm2 ) is 0.5% or more and the strain (0.6 N/ ^mm2 ) is 200% or less, even if the rear surface of the wafer is rough, the protective film-forming film peels off normally and easily in both the initial and later stages of peeling when peeled off from the rear surface of the wafer. Therefore, the protective film-forming film is excellent in terms of suitability for wafer recycling.

The protective film-forming film preferably exhibits both any one of the numerical ranges of the strain (0.1 N/mm ² ) and any one of the numerical ranges of the strain (0.6 N/mm ² ).

However, in the protective film-forming film, the strain (0.6 N/mm ² ) is larger than the strain (0.1 N/mm ² ).

Both the strain (0.1 N/mm ² ) and the strain (0.6 N/mm ² ) can be adjusted by adjusting the types and contents of the components contained in the protective film-forming film.
For example, when the thermosetting protective film-forming film contains the polymer component (A) described later, the strain (0.1 N/mm ² ) and the strain (0.6 N/mm ² ) can be more easily adjusted by adjusting the type and amount of the structural unit of the polymer component (A). More specifically, for example, an acrylic resin having a certain amount or more of the alkyl group constituting the alkyl ester, which is a (meth)acrylic acid alkyl ester described later, having 6 or more carbon atoms and having a chain structure, as a structural unit, is used as the polymer component (A) and the content thereof is adjusted, so that the strain (0.1 N/mm ² ) and the strain (0.6 N/mm ² ) can be more easily adjusted. In addition, an acrylic resin having a certain amount or more of the structural unit derived from acrylonitrile described later is used as the polymer component (A) and the content thereof is adjusted, so that the strain (0.1 N/mm ² ) and the strain (0.6 N/mm ² ) can be more easily adjusted.
In addition, for example, when the energy ray-curable protective film-forming film contains a polymer (a1) having an energy ray-curable group and a weight average molecular weight of 80,000 to 2,000,000, or a polymer (b) not having an energy ray-curable group, the strain (0.1 N/mm 2 ) and the strain (0.6 N/mm ² ) can be adjusted by adjusting the type and content of these components (the polymer (a1) or the polymer (b)) in the same manner as when the above-mentioned thermosetting protective film-forming film contains the polymer component ( ^A ).
Furthermore, for example, when the non-curable protective film-forming film contains the thermoplastic resin described below, the strain (0.1 N/mm 2 ) and the strain (0.6 N/mm 2 ) can be adjusted by adjusting the type and content of the thermoplastic resin, in the same manner as when the above-mentioned thermosetting protective film-forming film contains the polymer component ^{( A} ).

The protective film-forming film is preferably one in which the test piece does not break until the strain reaches 350% in the tensile test (when the strain is in the range of more than 0% and 350% or less). Such a protective film-forming film is superior in terms of suitability for recycling wafers.

The surface roughness (Ra) of either one or both sides of the protective film-forming film is not particularly limited, but is preferably less than 300 nm, more preferably less than 100 nm, and may be, for example, any of less than 50 nm, less than 40 nm, and less than 38 nm. By bonding a surface of the protective film-forming film having such a surface roughness (Ra) to the back surface of the wafer, the recesses can be filled to a greater extent with the protective film-forming film even if the back surface of the wafer is rough. As a result, after forming a protective film from the protective film-forming film, a higher adhesive strength can be maintained between the protective film and the wafer or chip. Furthermore, the recyclability of the wafer is not impaired.

The lower limit of the surface roughness (Ra) of either one or both sides of the protective film-forming film is not particularly limited. For example, a protective film-forming film having a surface roughness (Ra) of 20 nm or more on either one or both sides can be formed more easily.

In this specification, the surface roughness (Ra) means the so-called arithmetic mean roughness determined in accordance with ANSI/ASME B46.1.
The surface roughness (Ra) of the protective film-forming film can be adjusted, for example, by adjusting the forming conditions of the protective film-forming film, the surface treatment conditions, etc. For example, the protective film-forming film is formed by applying a protective film-forming composition described later to the surface to be formed and drying it as necessary, thereby adjusting the surface condition such as the surface roughness (Ra) of the surface to be formed, thereby adjusting the surface roughness (Ra) of the protective film-forming film.

The thickness of the protective film-forming film is preferably 1 to 100 μm, and may be, for example, any of 3 to 80 μm, 5 to 60 μm, and 7 to 45 μm. When the thickness of the protective film-forming film is equal to or greater than the lower limit, a protective film with higher protective performance can be formed. When the thickness of the protective film-forming film is equal to or less than the upper limit, excessive thickness can be avoided.
Here, "thickness of the protective film-forming film" means the thickness of the entire protective film-forming film, for example, the thickness of a protective film-forming film consisting of multiple layers means the total thickness of all layers that constitute the protective film-forming film.

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

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

The protective film-forming composition may be applied by a known method, such as a method 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, Mayer bar coater, or kiss coater.

Regardless of whether the protective film-forming film is curable or non-curable, and in the case of curable, regardless of whether it is heat-curable or energy ray-curable, the drying conditions of the protective film-forming composition are not particularly limited. However, when the protective film-forming composition contains a solvent described below, it is preferable to heat-dry it. And, it is preferable to heat-dry the protective film-forming composition containing the solvent, for example, at 70 to 130°C for 10 seconds to 5 minutes. However, it is preferable to heat-dry the thermosetting protective film-forming composition so that the composition itself and the thermosetting protective film-forming film formed from this composition are not thermally cured.

The following describes the thermosetting protective film-forming film, the energy ray-curable protective film-forming film, and the non-curable protective film-forming film in turn.

Thermosetting protective film-forming film The curing conditions when the thermosetting protective film-forming film is attached to a desired location on a wafer and thermally cured to form a protective film are not particularly limited as long as the degree of curing is such that the protective film can fully perform its function, and may be appropriately selected depending on the type of thermosetting protective film-forming film.
For example, the heating temperature during thermal curing of the thermosetting protective film-forming film is preferably 100 to 200° C., and may be, for example, any one of 110 to 180° C. and 120 to 170° 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 3 hours and 1 to 2 hours.

A protective film-forming film at room temperature is heated to a temperature above room temperature and then cooled to room temperature to obtain a protective film-forming film after heating and cooling. When the hardness of the protective film-forming film after heating and cooling is compared with the hardness of the protective film-forming film before heating at the same temperature, if the protective film-forming film after heating and cooling is harder, then this protective film-forming film is thermosetting.

Preferred thermosetting protective film-forming films include, for example, those containing a polymer component (A) and a thermosetting component (B). The polymer component (A) is a component that can be considered to be formed by a polymerization reaction of a polymerizable compound. The thermosetting component (B) is a component that can undergo a curing (polymerization) reaction using heat as a reaction trigger. In this specification, polymerization reaction also includes polycondensation reaction.

<Thermosetting protective film forming composition (III)>
A preferred example of a composition for forming a thermosetting protective film includes a composition for forming a thermosetting protective film (III) (sometimes abbreviated herein as "composition (III)") containing the polymer component (A) and the thermosetting component (B).

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

The polymer component (A) contained in the composition (III) and the thermosetting 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 polymer component (A) include acrylic resin, urethane resin, phenoxy resin, silicone resin, saturated polyester resin, etc., with acrylic resin being preferred.

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 10,000 to 2,000,000, more preferably 100,000 to 1,500,000, further preferably 200,000 to 1,200,000, and particularly preferably 300,000 to 1,000,000. When the weight average molecular weight of the acrylic resin is equal to or greater than the lower limit, the shape stability (stability over time during storage) of the thermosetting protective film-forming film is improved. In addition, it becomes easier to adjust the strain (0.6 N/mm ² ) to an appropriate range. On the other hand, when the weight average molecular weight of the acrylic resin is equal to or less than the upper limit, the thermosetting protective film-forming film is more likely to follow the uneven surface of the adherend (for example, the rough back surface of a wafer). In addition, it becomes easier to adjust the strain (0.1 N/mm ² ) to an appropriate range.

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 acrylic resin is preferably −60 to 70° C., more preferably −50 to 50° C., even more preferably −50 to 20° C., and particularly preferably −50 to −5° C. When the Tg of the acrylic resin is equal to or higher than the lower limit, for example, the adhesion between the cured product of the protective film-forming film and the support sheet is suppressed, and the peelability of the support sheet is appropriately improved. In addition, it becomes easier to adjust the strain (0.6 N/mm ² ) to an appropriate range. On the other hand, when the Tg of the acrylic resin is equal to or lower than the upper limit, the adhesive strength between the thermosetting protective film-forming film and the cured product thereof and the adherend is improved. In addition, it becomes easier to adjust the strain (0.1 N/mm ² ) to an appropriate range.

When an acrylic resin has m types of structural units (m is an integer of 2 or more), and the m types of monomers from which these structural units are derived are each assigned a unique number from 1 to m, and named "monomer m", the glass transition temperature (Tg) of the acrylic resin can be calculated using the Fox formula shown below.

（式中、Ｔｇはアクリル樹脂のガラス転移温度であり；ｍは２以上の整数であり；Ｔｇ_ｋはモノマーｍのホモポリマーのガラス転移温度であり；Ｗ_ｋはアクリル樹脂における、モノマーｍから誘導された構成単位ｍの質量分率であり、ただし、Ｗ_ｋは下記式を満たす。）

(In the formula, Tg is the glass transition temperature of the acrylic resin; m is an integer of 2 or more; Tg _k is the glass transition temperature of a homopolymer of monomer m; and W _k is the mass fraction of structural unit m derived from monomer m in the acrylic resin, with the proviso that W _k satisfies the following formula.)

（式中、ｍ及びＷ_ｋは、前記と同じである。）

(In the formula, m and _Wk are the same as above.)

The Tg _k can be a value described in the Polymer Data Handbook, the Adhesive Handbook, the Polymer Handbook, etc. For example, the Tg _k of a homopolymer of methyl acrylate is 10° C., the Tg _k of a homopolymer of methyl methacrylate is 105° C., the Tg k of a homopolymer of 2-hydroxyethyl acrylate is −15° C., the Tg _k of a homopolymer of glycidyl methacrylate is 41° C., the Tg _k of a homopolymer of 2-ethylhexyl _acrylate is −70° C., the Tg _k of a homopolymer of acrylic acid is 103° C., and the Tg _k of a homopolymer of acrylonitrile is 97° C.

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

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, and ) (meth)acrylic acid alkyl esters in which the alkyl group constituting the alkyl ester has a chain structure having 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 of such esters include (meth)acrylic acid esters containing a substituted amino group, 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.

In this specification, "(meth)acrylic acid" is a concept that includes both "acrylic acid" and "methacrylic acid". The same applies to terms similar to (meth)acrylic acid; for example, "(meth)acryloyl group" is a concept that includes both "acryloyl group" and "methacryloyl group", and "(meth)acrylate" is a concept that includes both "acrylate" and "methacrylate".

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

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 carboxyl 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).

An example of a preferred acrylic resin is an acrylic resin having structural units derived from an alkyl (meth)acrylate, wherein the alkyl group constituting the alkyl ester in the alkyl (meth)acrylate has 6 or more carbon atoms, the alkyl group has a chain structure, and the proportion (content) of the structural units derived from the alkyl (meth)acrylate with respect to the total amount of structural units constituting the acrylic resin is 50 to 75 mass %.
In the acrylic resin, the alkyl group preferably has 6 to 18 carbon atoms, and more preferably has 7 to 13 carbon atoms.
The alkyl group may be either linear or branched.
It is preferable that the acrylic resin further has a structural unit derived from a hydroxyl group-containing (meth)acrylic ester, and the ratio (content) of the amount of the structural unit derived from the hydroxyl group-containing (meth)acrylic ester to the total amount of structural units constituting the acrylic resin is preferably 7 to 20 mass%.

Another example of a preferred acrylic resin is an acrylic resin having a structural unit derived from acrylonitrile, in which the ratio (content) of the amount of the structural unit derived from acrylonitrile to the total amount of the structural units constituting the acrylic resin is 15 to 45 mass%.
It is preferable that the acrylic resin further has a structural unit derived from a (meth)acrylic acid ester, and the ratio (content) of the amount of the structural unit derived from the (meth)acrylic acid ester to the total amount of the structural units constituting the acrylic resin is preferably 65 to 85 mass%.

In the present invention, as the polymer component (A), a thermoplastic resin other than an acrylic resin (hereinafter sometimes simply abbreviated as "thermoplastic resin") may be used alone without using an acrylic resin, or may be used in combination with an acrylic resin. By using the thermoplastic resin, the peelability of the protective film from the support sheet may be improved, and the thermosetting protective film-forming film may be more easily conformed to the uneven surface of the adherend (for example, the rough back surface of a wafer).

The weight average molecular weight of the thermoplastic resin is preferably 1,000 to 100,000, and more preferably 3,000 to 80,000.

The glass transition temperature (Tg) of the thermoplastic resin is preferably -30 to 150°C, and more preferably -20 to 120°C.

Examples of the thermoplastic resin include polyester, polyurethane, phenoxy resin, polybutene, polybutadiene, polystyrene, etc.

The thermoplastic resin contained in composition (III) and the thermosetting 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.

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 10 to 85 mass%, more preferably 15 to 70 mass%, regardless of the type of the polymer component (A), and may be, for example, any one of 15 to 55 mass% and 15 to 40 mass%, or any one of 25 to 70 mass% and 30 to 60 mass%.
This is equivalent to saying that the content ratio of the polymer component (A) in the thermosetting protective film-forming film to the total mass of the thermosetting protective film-forming film is preferably 10 to 85 mass%, and more preferably 15 to 70 mass%, regardless of the type of polymer component (A), and may be, for example, any one of 15 to 55 mass% and 15 to 40 mass%, or any one of 25 to 70 mass% and 30 to 60 mass%.
This is based on the fact that the amount of components other than the solvent does not usually change during the process of removing the solvent from the resin composition containing the solvent to form the resin film, 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 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 below.

The polymer component (A) may also be a thermosetting component (B). In the present invention, when the composition (III) contains a component that corresponds to both the polymer component (A) and the thermosetting component (B), the composition (III) is considered to contain the polymer component (A) and the thermosetting component (B).

[Thermosetting component (B)]
The thermosetting component (B) is a component for curing the thermosetting protective film-forming film.
The thermosetting component (B) contained in the composition (III) and the thermosetting protective film-forming film may be only one type, or may be two or more types, and when 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 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 the composition (III) and the thermosetting 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.

Epoxy resin (B1)
The epoxy resin (B1) may be any known epoxy resin, such as a polyfunctional epoxy resin, a biphenyl compound, bisphenol A diglycidyl ether and its hydrogenated product, orthocresol novolac epoxy resin, a dicyclopentadiene type epoxy resin, a biphenyl type epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a phenylene skeleton type epoxy resin.

As the epoxy resin (B1), an epoxy resin having an unsaturated hydrocarbon group may be used.

The number average molecular weight of the epoxy resin (B1) is not particularly limited, but from the viewpoints of the curability of the thermosetting protective film-forming film and the strength and heat resistance of the protective film, it is preferably 300 to 30,000, more preferably 300 to 10,000, and particularly preferably 300 to 3,000.
The epoxy equivalent of the epoxy resin (B1) is preferably from 100 to 1,000 g/eq, and more preferably from 150 to 950 g/eq.

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

Heat curing agent (B2)
The heat curing agent (B2) functions as a curing agent for the epoxy resin (B1).
The heat curing 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, and the like. The phenolic hydroxyl group, the amino group, or an anhydride group of an acid group is preferable, and the phenolic hydroxyl group or the amino group is more preferable.

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.

The heat curing agent (B2) may have an unsaturated hydrocarbon group.

When a phenol-based curing agent is used as the heat curing agent (B2), it is preferable that the heat curing agent (B2) has a high softening point or glass transition temperature in order to improve the peelability of the protective film from the support sheet.

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 agent (B2), the molecular weight of the non-resin components, such as biphenol and dicyandiamide, is not particularly limited, but is preferably, for example, 60 to 500.

The heat curing agent (B2) may be used alone or in combination of two or more kinds. When two or more kinds are used in combination, the combination and ratio of the two or more kinds can be selected arbitrarily.

In the composition (III) and the thermosetting protective film-forming film, the content of the thermosetting agent (B2) is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 50 parts by mass, and may be, for example, any of 0.5 to 25 parts by mass, 0.5 to 10 parts by mass, and 0.5 to 5 parts by mass, relative to 100 parts by mass of the epoxy resin (B1). When the content of the thermosetting agent (B2) is equal to or greater than the lower limit, the curing of the thermosetting protective film-forming film is more likely to proceed. When the content of the thermosetting agent (B2) is equal to or less than the upper limit, the moisture absorption rate of the thermosetting protective film-forming film is reduced, and the reliability of the package obtained using the protective film-forming film is further improved.

In the composition (III) and the thermosetting protective film-forming film, the content of the thermosetting component (B) (for example, the total content of the epoxy resin (B1) and the thermosetting agent (B2)) is preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass, even more preferably 25 to 50 parts by mass, and particularly preferably 30 to 45 parts by mass, relative to 100 parts by mass of the total content of the polymer component (A) and the thermosetting component (B). When the content of the thermosetting component (B) is in such a range, for example, the adhesion between the cured product of the protective film-forming film and the support sheet is suppressed, and the peelability of the support sheet is improved.

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

The curing accelerator (C) contained in the composition (III) and the thermosetting 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 the curing accelerator (C) is used, the content of the curing accelerator (C) in the composition (III) and the thermosetting protective film-forming film is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 7 parts by mass, relative to 100 parts by mass of the content of the thermosetting component (B). When the content of the curing accelerator (C) is equal to or greater than the lower limit, the effect of using the curing accelerator (C) is more pronounced. When the content of the curing accelerator (C) is equal to or less than the upper limit, for example, the effect of suppressing the highly polar curing accelerator (C) from migrating to the adhesive interface with the adherend and segregating in the thermosetting protective film-forming film under high temperature and high humidity conditions is enhanced. As a result, the reliability of the chip with the protective film obtained using the protective film-forming film is further improved.

[Filler (D)]
The composition (III) and the thermosetting protective film-forming film may contain a filler (D). By containing the filler (D) in the thermosetting protective film-forming film, the thermal expansion coefficient of the thermosetting protective film-forming film and the protective film can be easily adjusted, and by optimizing this thermal expansion coefficient for the object on which the protective film is formed, the reliability of the chip with the protective film obtained using the protective film-forming film is further improved. In addition, by containing the filler (D) in the thermosetting protective film-forming film, the moisture absorption rate of the protective film can be reduced and the heat dissipation can be improved.

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; glass fibers, and the like.
Among these, the inorganic filler is preferably silica or alumina, and more preferably silica.

The filler (D) contained in the composition (III) and the thermosetting 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 the filler (D) is used, the content ratio of the filler (D) in the thermosetting protective film-forming film with respect to the total mass of the thermosetting protective film-forming film is preferably 15 to 70 mass%, and may be, for example, any of 25 to 70 mass%, 35 to 70 mass%, 45 to 70 mass%, 50 to 70 mass%, and 55 to 70 mass%, or any of 15 to 60 mass% and 15 to 55 mass%. When the ratio is in such a range, the above-mentioned adjustment of the thermal expansion coefficient of the thermosetting protective film-forming film and the protective film becomes easier. On the other hand, when the ratio is equal to or more than the lower limit, it becomes easier to adjust the strain (0.6 N/mm ² ) to an appropriate range. Also, when the ratio is equal to or less than the upper limit, it becomes easier to adjust the strain (0.1 N/mm ² ) to an appropriate range.

[Coupling Agent (E)]
The composition (III) and the thermosetting 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 of the protective film formed from the thermosetting protective film-forming film to the adherend can be improved. In addition, by using the coupling agent (E), the water resistance of the 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 groups 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 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.

Preferred examples of the silane coupling agent include oligomer-type silane coupling agents having a plurality of alkoxysilyl groups in one molecule.
The oligomer type silane coupling agent is preferable in that it is difficult to volatilize and has a plurality of alkoxysilyl groups in one molecule, and therefore is effective in improving durability.
Examples of the oligomeric silane coupling agents include epoxy group-containing oligomeric silane coupling agents "X-41-1053", "X-41-1059A", "X-41-1056" and "X-40-2651" (all manufactured by Shin-Etsu Chemical Co., Ltd.); and mercapto group-containing oligomeric silane coupling agents "X-41-1818", "X-41-1810" and "X-41-1805" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

The coupling agent (E) contained in the composition (III) and the thermosetting 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 the coupling agent (E) is used, the content of the coupling agent (E) in the composition (III) and the thermosetting protective film-forming film is preferably 0.03 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and particularly preferably 0.1 to 2 parts by mass, relative to 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 in such a range, the chemical compatibility between the thermosetting protective film-forming film and the adherend can be slightly controlled, making it easier to adjust the adhesion and peelability. On the other hand, when the content of the coupling agent (E) is equal to or greater than 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 protective film-forming film to the adherend, can be more significantly obtained. When the content of the coupling agent (E) is equal to or less than the upper limit, the generation of outgassing is more suppressed.

[Crosslinking agent (F)]
When the polymer component (A) is one having a functional group such as a vinyl group, (meth)acryloyl group, amino group, hydroxyl group, carboxyl group, isocyanate group, etc., which can be bonded to other compounds, such as the above-mentioned acrylic resin, the composition (III) and the thermosetting protective film-forming film may contain a crosslinking agent (F). The crosslinking agent (F) is a component for bonding the functional group in the polymer component (A) to other compounds to crosslink them, and by crosslinking in this way, the adhesive strength and cohesive strength of the thermosetting protective film-forming film can be adjusted.

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

The crosslinking agent (F) contained in the composition (III) and the thermosetting 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 crosslinking agent (F) is used, the content of the crosslinking agent (F) in the composition (III) is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and particularly preferably 0.5 to 5 parts by mass, per 100 parts by mass of the polymer component (A). When the content of the crosslinking agent (F) is equal to or greater than the lower limit, the effect of using the crosslinking agent (F) is more pronounced. When the content of the crosslinking agent (F) is equal to or less than the upper limit, excessive use of the crosslinking agent (F) is suppressed.

[Energy ray curable resin (G)]
The composition (III) and the thermosetting protective film-forming film may contain an energy ray curable resin (G). By containing the energy ray curable resin (G), the thermosetting protective film-forming film can change its properties by irradiation with energy rays.

The energy ray curable resin (G) is an energy ray curable compound, or an oligomer or polymer that can be considered to have been synthesized from an energy ray curable compound.
The energy ray-curable compound includes, for example, a compound having at least one polymerizable double bond in the molecule, and is preferably an acrylate-based compound having a (meth)acryloyl group.

Examples of the acrylate-based compounds include trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. Examples of such compounds include (meth)acrylates containing a cyclic aliphatic skeleton; (meth)acrylates containing a cyclic aliphatic skeleton such as dicyclopentanyl di(meth)acrylate; polyalkylene glycol (meth)acrylates such as polyethylene glycol di(meth)acrylate; oligoester (meth)acrylates; urethane (meth)acrylate oligomers; epoxy-modified (meth)acrylates; polyether (meth)acrylates other than the above-mentioned polyalkylene glycol (meth)acrylates; and itaconic acid oligomers.

The weight average molecular weight of the energy ray curable compound is preferably 100 to 30,000, and more preferably 300 to 10,000.

The energy ray curable compound used in the synthesis of the oligomer or polymer may be one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

The energy ray curable resin (G) contained in the composition (III) and the thermosetting 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.

When an energy ray curable resin (G) is used, the content of the energy ray curable resin (G) in composition (III) relative to the total mass of composition (III) is preferably 1 to 30 mass%, more preferably 5 to 25 mass%, and particularly preferably 10 to 20 mass%.

[Photopolymerization initiator (H)]
When the composition (III) and the thermosetting protective film-forming film contain an energy ray curable resin (G), they may contain a photopolymerization initiator (H) in order to efficiently advance the polymerization reaction of the energy ray curable resin (G).

Examples of the photopolymerization initiator (H) in the composition (III) include benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, and benzoin dimethyl ketal; acetophenone compounds such as acetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one, and 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone; and bis(2,4,6-trimethylbenzoyl)phenyl phenyl ether. Examples of the compound include acylphosphine oxide compounds such as phosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; sulfide compounds such as benzyl phenyl sulfide and tetramethylthiuram monosulfide; α-ketol compounds such as 1-hydroxycyclohexyl phenyl ketone; azo compounds such as azobisisobutyronitrile; titanocene compounds such as titanocene; thioxanthone compounds such as thioxanthone; peroxide compounds; diketone compounds such as diacetyl; benzyl; dibenzyl; benzophenone; 2,4-diethylthioxanthone; 1,2-diphenylmethane; 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone; and quinone compounds such as 1-chloroanthraquinone and 2-chloroanthraquinone.
Examples of the photopolymerization initiator (H) include photosensitizers such as amines.

The photopolymerization initiator (H) contained in the composition (III) and the thermosetting 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 photopolymerization initiator (H) is used, the content of the photopolymerization initiator (H) in the composition (III) is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, and particularly preferably 2 to 5 parts by mass, per 100 parts by mass of the energy ray-curable resin (G).

[Colorant (I)]
The composition (III) and the thermosetting protective film-forming film preferably contain a colorant (I). By containing the colorant (I), the light transmittance of the thermosetting protective film-forming film and the protective film can be easily adjusted.

Examples of colorants (I) include known ones such as inorganic pigments, organic pigments, and organic dyes.

Examples of the organic pigments and organic dyes include aminium-based dyes, cyanine-based dyes, merocyanine-based dyes, croconium-based dyes, squalium-based dyes, azulenium-based dyes, polymethine-based dyes, naphthoquinone-based dyes, pyrylium-based dyes, phthalocyanine-based dyes, naphthalocyanine-based dyes, naphtholactam-based dyes, azo-based dyes, condensed azo-based dyes, indigo-based dyes, perinone-based dyes, perylene-based dyes, dioxazine-based dyes, quinacridone-based dyes, isoindolinone-based dyes, quinophthalone-based dyes, pyrrole-based dyes, thioindigo-based dyes, metal complex-based dyes (metal complex dyes), dithiol metal complex-based dyes, indolephenol-based dyes, triarylmethane-based dyes, anthraquinone-based dyes, naphthol-based dyes, azomethine-based dyes, benzimidazolone-based dyes, pyranthrone-based dyes, and threne-based dyes.

Examples of the inorganic pigments include carbon black, cobalt-based pigments, iron-based pigments, chromium-based pigments, titanium-based pigments, vanadium-based pigments, zirconium-based pigments, molybdenum-based pigments, ruthenium-based pigments, platinum-based pigments, ITO (indium tin oxide)-based pigments, and ATO (antimony tin oxide)-based pigments.

The colorant (I) contained in the composition (III) and the thermosetting 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 the colorant (I) is used, the content of the colorant (I) in the thermosetting protective film-forming film may be adjusted appropriately according to the purpose. For example, by adjusting the content of the colorant (I) in the thermosetting protective film-forming film and adjusting the light transmittance of the thermosetting protective film-forming film, the visibility of the print when laser printing is performed on the thermosetting protective film-forming film or the protective film can be adjusted. In addition, by adjusting the content of the colorant (I) in the thermosetting protective film-forming film, the design of the protective film can be improved and the grinding marks on the back surface of the wafer can be made less visible. In consideration of these points, the content ratio of the colorant (I) in the thermosetting protective film-forming film to the total mass of the thermosetting protective film-forming film is preferably 0.1 to 10 mass%, more preferably 0.1 to 7.5 mass%, and particularly preferably 0.1 to 5 mass%. When the ratio is equal to or greater than the lower limit, the effect of using the colorant (I) can be obtained more significantly. For example, when the thermosetting protective film-forming film is peeled off from the adherend, the presence or absence of the thermosetting protective film-forming film remaining on the adherend can be easily confirmed by visual inspection. By setting the ratio to the upper limit or less, excessive use of the colorant (I) is suppressed.

[General-purpose additives (J)]
The composition (III) and the thermosetting protective film-forming film may contain a general-purpose additive (J) within a range that does not impair the effects of the present invention.
The general-purpose additive (J) may be a known one and may be arbitrarily selected depending on the purpose, and is not particularly limited. Preferred examples thereof include plasticizers, antistatic agents, antioxidants, gettering agents, and ultraviolet absorbers.

The general-purpose additive (J) contained in the composition (III) and the thermosetting protective film-forming film may be only one type, or may be 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 composition (III) and the general-purpose additive (J) in the thermosetting protective film-forming film is not particularly limited and may be appropriately selected depending on the purpose.

[solvent]
It is preferable that the composition (III) further contains a solvent. The composition (III) containing a solvent has good handleability.
In this specification, unless otherwise specified, the term "solvent" is used as a concept that includes not only a substance that dissolves a target component, but also a dispersion medium that disperses the target component.

The solvent is not particularly limited, but preferred examples thereof 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 (III) may be only one type, or may be two or more types. When two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

More preferred examples of the solvent contained in composition (III) include methyl ethyl ketone, toluene, ethyl acetate, etc., which allow the components contained in composition (III) to be mixed more uniformly.

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

<Method for producing thermosetting protective film-forming composition (III)>
Composition (III) can be obtained by blending the respective components constituting composition (III).
The order of addition of the components 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 blade, a method of mixing using a mixer, a method of mixing by applying ultrasound, etc.
The temperature and time during addition and mixing of each component are not particularly limited as long as the components do not deteriorate, and may be adjusted appropriately. The temperature is preferably 15 to 30°C.

Energy Ray-Curable Protective Film-Forming Film The energy ray-curable protective film-forming film is attached to a desired location on a wafer and cured with energy rays to form a protective film. The curing conditions are not particularly limited as long as the protective film has a degree of curing that allows it to fully exhibit its functions, and may be appropriately selected depending on the type of energy ray-curable protective film-forming film.
For example, the illuminance of the energy ray during energy ray curing of the energy ray-curable protective film-forming film is preferably 120 to 280 mW/cm ^2. The amount of energy ray during the curing is preferably 100 to 1000 mJ/cm ² .

<Energy ray-curable protective film-forming composition (IV)>
A preferred example of the energy ray-curable protective film-forming composition is an energy ray-curable protective film-forming composition (IV) (sometimes abbreviated herein as "composition (IV)") containing the energy ray-curable component (a).

[Energy ray-curable component (a)]
The energy ray-curable component (a) is a component that is cured by irradiation with energy rays, and imparts film-forming properties, flexibility, and the like to the energy ray-curable protective film-forming film, and is also a component for forming a hard protective film after curing.
In the energy ray-curable protective film-forming film, the energy ray-curable component (a) is preferably uncured and has adhesive properties, and more preferably is 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 reacting an acrylic polymer (a11) having a functional group capable of reacting with a group possessed by another compound with 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 of a wafer, a chip, etc., it is preferable that the functional group is a group other than a carboxy group.
Of these, the functional group is preferably a hydroxyl group.

Acrylic polymer having a functional group (a11)
The acrylic polymer (a11) having a functional group can be, for example, a polymer obtained by copolymerizing an acrylic monomer having the functional group with an acrylic monomer not having the functional group. In addition to these monomers, the acrylic polymer may also be a polymer obtained by copolymerizing a monomer other than the acrylic monomer (a11) with a non-acrylic monomer.
The acrylic polymer (a11) may be a random copolymer or a block copolymer, and a known method can be used for the polymerization method.

Examples of the acrylic monomer having a functional group include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, a substituted amino group-containing monomer, and an epoxy group-containing monomer.

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; 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 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.

The acrylic monomer having the functional group constituting the acrylic polymer (a11) may be of only one type or of two or more types, and when it is of two or more types, the combination and ratio thereof can be selected arbitrarily.

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

In this specification, when a structure in which one or more hydrogen atoms in a certain specific compound are replaced with a group other than a hydrogen atom is assumed, the compound having such a replaced structure is referred to as a "derivative" of the above-mentioned specific compound.
In this specification, the term "group" includes not only an atomic group having a structure in which a plurality of atoms are bonded, but also a single atom.

The acrylic monomer not having a functional group constituting the acrylic polymer (a11) may be of only one type or of two or more types, and when it is of two or more types, 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. When the non-acrylic monomer is of two or more kinds, the combination and ratio thereof can be arbitrarily selected.

In the acrylic polymer (a11), the ratio (content) of the amount of the structural unit derived from the acrylic monomer having the functional group to the total amount of the structural units constituting the acrylic polymer (a11) is preferably 0.1 to 50 mass%, more preferably 1 to 40 mass%, and particularly preferably 3 to 30 mass%. When the ratio is in such a range, the acrylic resin (a1-1) obtained by copolymerization of the acrylic polymer (a11) and the energy ray curable compound (a12) is likely to have a suitable content of energy ray curable groups to form a protective film, and the degree of curing of the protective film can be adjusted to a preferred range.

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

In the energy ray-curable protective film-forming film, the content ratio of the acrylic resin (a1-1) relative to the total mass of the energy ray-curable protective film-forming film is preferably 1 to 70 mass%, more preferably 5 to 60 mass%, and particularly preferably 10 to 50 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 capable of reacting 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 reacts with the hydroxyl group of the acrylic polymer (a11) having a hydroxyl group as the functional group.

The number of the energy ray-curable groups that the energy ray-curable compound (a12) has in one molecule is not particularly limited and can be appropriately selected in consideration of the physical properties, such as the shrinkage rate, required for the intended protective film, for example.
For example, the energy ray-curable compound (a12) preferably has 1 to 5, and more preferably 1 to 3, energy ray-curable groups in one 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, and when there are two or more types, 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 group derived from the energy ray curable compound (a12) to the content of the functional group 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 in such a range, the adhesive strength of the cured product of the energy ray curable protective film forming film becomes greater. In addition, when the energy ray curable compound (a12) is a monofunctional compound (having one of the groups in one molecule), the upper limit of the content ratio is 100 mol%, but when the energy ray curable compound (a12) is a polyfunctional compound (having two or more of the groups in one 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.

The polymer (a1) contained in the composition (IV) and the energy ray-curable 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)
The energy ray-curable group in the compound (a2) having an energy ray-curable group and a molecular weight of 100 to 80,000 includes a group 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 thereof 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 low molecular weight compounds 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-based compound include the compounds described in paragraph 0195 of International Publication No. 2017-188197.

Of the compounds (a2), examples of the epoxy resin having an energy ray-curable group and the phenolic resin having an energy ray-curable group that can be used include those described in paragraph 0043 of JP 2013-194102 A. Although such resins also fall under the category of resins constituting the thermosetting component described below, they are treated as the compound (a2) in the composition (IV).

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 the composition (IV) and the energy ray-curable 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 protective film-forming film contain the compound (a2) as the energy ray curable component (a), they preferably further contain a polymer (b) having no energy ray curable group.

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)").

Examples of the acrylic polymer (b-1) include the same as the polymer component (A) described above. However, the acrylic polymer (b-1) does not have an energy ray-curable group.

When the polymer (b) has a functional group such as a glycidyl group, a hydroxyl group, a substituted amino group, a carboxy group, or an amino group, the polymer (b) may be crosslinked with a crosslinking agent.
The functional group may be appropriately selected depending on the type of the crosslinking agent, and is not particularly limited. For example, when the crosslinking agent is a polyisocyanate compound, the functional group may be a hydroxyl group, a carboxyl group, an amino group, etc., and among these, a hydroxyl group having high reactivity with an isocyanate group is preferred. When the crosslinking agent is an epoxy compound, the functional group may be a carboxyl group, an amino group, etc., and among these, a carboxyl group having high reactivity with an epoxy group is preferred. However, from the viewpoint of preventing corrosion of the circuits of the wafer or chip, the functional group is preferably a group other than a carboxyl group.

The polymer (b) not having an energy ray curable group contained in the composition (IV) and the energy ray curable 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 composition (IV) may contain either one or both of the polymer (a1) and the compound (a2). When the composition (IV) contains the compound (a2), it is preferable that the composition (IV) further contains a polymer (b) having no energy ray curable groups, and in this case, it is also preferable that the composition (IV) further contains the (a1). The composition (IV) may not contain the compound (a2), and may contain both the polymer (a1) and the polymer (b) having no energy ray curable groups.

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 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 protective film-forming film is preferably 5 to 90 mass%, more preferably 10 to 80 mass%, and particularly preferably 20 to 70 mass%. When the ratio is in such a range, the film-forming property, flexibility, and energy ray curability of the energy ray-curable protective film-forming film become better.

In addition to the energy ray-curable component (a), the composition (IV) may contain, depending on the purpose, one or more selected from the group consisting of a thermosetting component, a filler, a coupling agent, a crosslinking agent, a photopolymerization initiator, a colorant, and a general-purpose additive.

The thermosetting component, filler, coupling agent, crosslinking agent, photopolymerization initiator, colorant, and general-purpose additive in composition (IV) may be the same as the thermosetting component (B), filler (D), coupling agent (E), crosslinking agent (F), photopolymerization initiator (H), colorant (I), and general-purpose additive (J) in composition (III), respectively.
The energy ray-curable protective film-forming film containing these components exhibits the same effects as the heat-curable protective film-forming film containing these components.
In particular, since the photopolymerization initiator efficiently promotes the energy ray curing reaction, it is preferable that the energy ray curable protective film-forming film contains a photopolymerization initiator.

In composition (IV), the thermosetting component, filler, coupling agent, crosslinking agent, photopolymerization initiator, colorant, and general-purpose additive may each be used alone or in combination of two or more kinds. When two or more kinds are used in combination, the combination and ratio of these may be selected arbitrarily.

The contents of the thermosetting component, filler, coupling agent, crosslinking agent, photopolymerization initiator, colorant, and general-purpose additives in composition (IV) may be appropriately adjusted according to the purpose, and are not particularly limited.

Composition (IV) preferably further contains a solvent, since dilution improves its handling properties.
The solvent contained in the composition (IV) may be, for example, the same as the solvent in the composition (III).
The composition (IV) may contain only one type of solvent, or may contain two or more types of solvents.
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.

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

Non-curable Protective Film-Forming Film A preferred non-curable protective film-forming film is, for example, one that contains a thermoplastic resin and a filler.

<Non-curable protective film forming composition (V)>
A preferred example of a composition for forming a non-curable protective film includes, for example, a composition for forming a non-curable protective film (V) (sometimes abbreviated in this specification as simply "composition (V)") containing the above-mentioned thermoplastic resin and a filler.

[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 above-mentioned composition (III), such as acrylic resin, polyester, polyurethane, phenoxy resin, polybutene, polybutadiene, and polystyrene.

The thermoplastic resin contained in composition (V) and the non-curable 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.

In the non-curable protective film-forming film, the content ratio of the thermoplastic resin to the total mass of the non-curable protective film-forming film is preferably 25 to 75 mass%.

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

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

The filler contained in composition (V) and the non-curable 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 of the fillers can be selected arbitrarily.

In the non-curable protective film-forming film, the ratio of the filler content to the total mass of the non-curable protective film-forming film is preferably 25 to 75 mass%. By having the ratio in this range, it becomes easier to adjust the thermal expansion coefficient of the non-curable protective film-forming film and the protective film, as in the case of using composition (III).

The composition (V) may contain other components in addition to the thermoplastic resin and filler, depending on the purpose.
The other components are not particularly limited and can be selected arbitrarily depending on the purpose.
For example, by using the composition (V) containing the thermoplastic resin and the colorant, the non-curable protective film-forming film and protective film formed exhibit the same effects as those when the thermosetting protective film-forming film described above contains the colorant (I).

In composition (V), the other components may be used alone or in combination of two or more kinds. When two or more kinds are used in combination, the combination and ratio thereof may be selected arbitrarily.

The content of the other components in composition (V) may be adjusted appropriately depending on the purpose and is not particularly limited.

Composition (V) preferably further contains a solvent, since dilution improves its handleability.
Examples of the solvent contained in the composition (V) include the same solvents as those in the above-mentioned composition (III).
The composition (V) may contain only one type of solvent, or may contain two or more types of solvents.
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.

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

Example of protective film-forming film Fig. 1 is a cross-sectional view showing an example of a protective film-forming film according to the present embodiment. In addition, the drawings used in the following description may show the main parts enlarged for the sake of convenience in order to make the characteristics of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as the actual ones.

The protective film-forming film 13 shown here has a first release film 151 on one of its surfaces (sometimes referred to as the "first surface" in this specification) 13a, and a second release film 152 on the other surface (sometimes referred to as the "second surface" in this specification) 13b opposite the first surface 13a.
Such a protective film-forming film 13 is suitable for storage, for example, in a roll form.

When the tensile test is carried out using the protective film-forming film 13, the strain (0.1 N/mm ² ) is 0.5% or more, and the strain (0.6 N/mm ² ) is 200% or less.

The protective film forming film 13 can be formed using the protective film forming composition described above.

The first release film 151 and the second release film 152 may both be of known types.
The first release film 151 and the second release film 152 may be the same as each other, or may be different from each other, for example, in that the peeling forces required to peel them from the protective film-forming film 13 are different from each other.

In the protective film-forming film 13 shown in FIG. 1, either the first release film 151 or the second release film 152 is removed, and the resulting exposed surface becomes the surface to be attached to the back surface of the wafer (not shown). When using a support sheet or a dicing sheet (described later), the other remaining one of the first release film 151 and the second release film 152 is removed, and the resulting exposed surface of the protective film-forming film 13 becomes the surface to be attached to the support sheet or the dicing sheet.

In FIG. 1, an example is shown in which the release film is provided on both sides (first side 13a, second side 13b) of the protective film-forming film 13, but the release film may be provided on only one side of the protective film-forming film 13, i.e., only the first side 13a or only the second side 13b.

The protective film-forming film of this embodiment can be used in combination with a support sheet described below to form a composite sheet for forming a protective film, which can perform both protective film formation and dicing. Such a composite sheet for forming a protective film will be described below.

◇Composite sheet for forming a protective film A composite sheet for forming a protective film according to one embodiment of the present invention comprises a support sheet and a protective film-forming film provided on one side of the support sheet, and the protective film-forming film is the protective film-forming film according to one embodiment of the present invention described above.
The composite sheet for forming a protective film of this embodiment can be attached to the back surface of a wafer by the protective film-forming film therein. The protective film-forming film in the composite sheet for forming a protective film can be peeled off from the back surface of the wafer while the composite sheet for forming a protective film is still constituted, i.e., integral with the support sheet, for the purpose of re-attaching a separately prepared composite sheet for forming a protective film or a protective film-forming film. At this time, as explained above, the protective film-forming film in the composite sheet for forming a protective film can be peeled off normally and easily even if the back surface of the wafer is rough, and is excellent in terms of suitability for recycling the wafer.

In this specification, as long as the laminated structure of the support sheet and the cured product of the protective film-forming film is maintained even after the protective film-forming film has cured, this laminated structure is referred to as a "composite sheet for forming a protective film."

Below, each layer constituting the composite sheet for forming a protective film is described in detail.

The support sheet may be one layer (single layer) or two or more layers. When the support sheet is made of multiple layers, the constituent materials and thicknesses of these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention.

The support sheet may be either transparent or non-transparent, and may be colored depending on the purpose.
When the protective film-forming film has energy ray curing properties, the support sheet is preferably one that transmits energy rays.

Examples of the support sheet include those comprising a substrate and an adhesive layer provided on one side of the substrate; and those consisting of the substrate alone. When the support sheet comprises an adhesive layer, the adhesive layer is disposed between the substrate and the protective film-forming film in the composite sheet for forming a protective film.

When a support sheet having a substrate and a pressure-sensitive adhesive layer is used, the adhesion and peelability between the support sheet and the protective film-forming film in the composite sheet for forming a protective film can be easily adjusted.
When a support sheet consisting of only a substrate is used, the composite sheet for forming a protective film can be produced at low cost.

Examples of composite sheets for forming protective films according to this embodiment will be described below for each type of support sheet with reference to the drawings.

Example of Composite Sheet for Forming a Protective Film FIG. 2 is a cross-sectional view that illustrates an example of the composite sheet for forming a protective film according to the present embodiment.
In FIG. 2 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.

The composite sheet 101 for forming a protective film shown here is composed of a support sheet 10 and a protective film forming film 13 provided on one surface 10a (sometimes referred to as the "first surface" in this specification) of the support sheet 10.
The support sheet 10 is configured to include a base material 11 and an adhesive layer 12 provided on one surface (first surface) 11a of the base material 11. In the composite sheet 101 for forming a protective film, the adhesive layer 12 is disposed between the base material 11 and a protective film-forming film 13.
That is, the composite sheet for forming a protective film 101 is constructed by laminating a substrate 11, a pressure-sensitive adhesive layer 12, and a protective film-forming film 13 in this order in the thickness direction.
The first surface 10a of the support sheet 10 is the same as the surface 12a of the pressure-sensitive adhesive layer 12 opposite the substrate 11 side (sometimes referred to as the "first surface" in this specification).

The composite sheet for forming a protective film 101 further includes a jig adhesive layer 16 and a release film 15 on the protective film-forming film 13 .
In the composite sheet 101 for forming a protective film, the protective film-forming film 13 is laminated on the entire or almost entire surface of the first surface 12a of the adhesive layer 12, and the jig adhesive layer 16 is laminated on a part of the surface 13a of the protective film-forming film 13 opposite the adhesive layer 12 side (sometimes referred to as the "first surface" in this specification), i.e., on a region near the peripheral portion. Furthermore, a release film 15 is laminated on the region of the first surface 13a of the protective film-forming film 13 where the jig adhesive layer 16 is not laminated, and on the surface 16a of the jig adhesive layer 16 opposite the protective film-forming film 13 side (sometimes referred to as the "first surface" in this specification). A support sheet 10 is provided on the surface 13b of the protective film-forming film 13 opposite the first surface 13a (sometimes referred to as the "second surface" in this specification).

Not only in the case of the composite sheet for forming a protective film 101, but also in the composite sheet for forming a protective film of this embodiment, the release film (e.g., release film 15 shown in FIG. 2) is of any configuration, and the composite sheet for forming a protective film of this embodiment may or may not include a release film.

The jig adhesive layer 16 is used to fix the composite sheet for forming a protective film 101 to a jig such as a ring frame.
The jig adhesive layer 16 may have, for example, a single-layer structure containing an adhesive component or a pressure-sensitive adhesive component, or may have a multi-layer structure including a core sheet and layers containing an adhesive component or a pressure-sensitive adhesive component provided on both sides of the core sheet.

With the release film 15 removed, the composite sheet 101 for forming a protective film is used by attaching the back surface of a wafer to the first surface 13a of the protective film forming film 13, and then attaching the first surface 16a of the jig adhesive layer 16 to a jig such as a ring frame.

As described above, the protective film-forming film 13 has excellent suitability for regenerating the wafer, even if the back surface of the wafer is rough.

FIG. 3 is a cross-sectional view that illustrates another example of the composite sheet for forming a protective film according to the present embodiment.
The composite sheet 102 for forming a protective film shown here is the same as the composite sheet 101 for forming a protective film shown in Figure 2, except that the shape and size of the protective film-forming film are different and the jig adhesive layer is laminated to the first surface of the pressure-sensitive adhesive layer rather than the first surface of the protective film-forming film.

More specifically, in the composite sheet 102 for forming a protective film, the protective film-forming film 23 is laminated in a part of the first surface 12a of the adhesive layer 12, that is, in the central region in the width direction (left and right direction in FIG. 3) of the adhesive layer 12. Furthermore, in the region of the first surface 12a of the adhesive layer 12 where the protective film-forming film 23 is not laminated, the jig adhesive layer 16 is laminated so as to surround the protective film-forming film 23 from the outside in the width direction without contact. A release film 15 is laminated on the surface 23a (sometimes referred to as the "first surface" in this specification) of the protective film-forming film 23 opposite the adhesive layer 12 side and the first surface 16a of the jig adhesive layer 16. A support sheet 10 is provided on the surface 23b (sometimes referred to as the "second surface" in this specification) of the protective film-forming film 23 opposite the first surface 23a.

FIG. 4 is a cross-sectional view that illustrates a schematic diagram of still another example of the composite sheet for forming a protective film according to the present embodiment.
The composite sheet 103 for forming a protective film shown here is the same as the composite sheet 102 for forming a protective film shown in FIG.

FIG. 5 is a cross-sectional view that illustrates a schematic diagram of still another example of the composite sheet for forming a protective film according to the present embodiment.
The composite sheet 104 for forming a protective film shown here is the same as the composite sheet 101 for forming a protective film shown in FIG. 2, except that it is configured to include a support sheet 20 instead of the support sheet 10.

The support sheet 20 is composed of only a base material 11 .
That is, the protective film-forming composite sheet 104 is configured by laminating the substrate 11 and the protective film-forming film 13 in the thickness direction.
The surface 20 a of the support sheet 20 on the protective film-forming film 13 side is the same as the first surface 11 a of the substrate 11 .

The composite sheet for forming a protective film of this embodiment is not limited to that shown in Figures 1 to 5, and may have some of the configurations shown in Figures 1 to 5 changed or removed, or may have other configurations added to those described above, within the scope that does not impair the effects of the present invention.

Next, we will explain each layer that makes up the support sheet in more detail.

Substrate The substrate is in the form of a sheet or film, and examples of the constituent materials 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; vinyl chloride-based resins (copolymers obtained using vinyl chloride as a monomer) such as polyvinyl chloride and vinyl chloride copolymers. Examples of the polyester include polyesters such as poly(ethylene terephthalate), poly(ethylene 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.
The resin may also be a polymer alloy such as a mixture of the polyester and another resin. The polymer alloy of the polyester and another resin is preferably one in which the amount of the resin other than the polyester is relatively small.
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 is preferably polypropylene or polybutylene terephthalate, which has excellent heat resistance.

The resin constituting the base material 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.

The substrate may be made of one layer (single layer) or may be made of two or more layers. When made of multiple layers, these layers may be the same or different from each other, and the combination of these layers is not particularly limited.

The thickness of the substrate is preferably 50 to 300 μm, and more preferably 60 to 100 μm. By making the thickness of the substrate within such a range, the flexibility of the composite sheet for forming a protective film and the suitability for attachment to a wafer are further improved.
Here, the "thickness of the substrate" means the thickness of the entire substrate. For example, the thickness of a substrate consisting of multiple layers means the total thickness of all layers constituting the substrate.

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

The substrate may be either transparent or non-transparent, may be colored according to the purpose, and may have other layers vapor-deposited thereon.
When the protective film-forming film has energy ray curing properties, the substrate is preferably one that transmits energy rays.

In order to adjust the adhesion with a layer (e.g., an adhesive layer, a protective film-forming film, or the other layer) provided thereon, the substrate may be subjected to a surface treatment such as sandblasting, solvent treatment, etc. to create a rough surface; corona discharge treatment, electron beam irradiation treatment, plasma treatment, ozone/ultraviolet radiation treatment, flame treatment, chromic acid treatment, hot air treatment, etc.; lipophilic treatment; hydrophilic treatment, etc. In addition, the substrate may be subjected to a primer treatment on the surface.

The substrate may have adhesive properties on at least one surface by containing a specific range of components (e.g., resin, etc.).

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

Adhesive Layer The adhesive layer is in the form of a sheet or film and contains an adhesive.
Examples of the adhesive include adhesive resins such as acrylic resins, urethane resins, rubber-based resins, silicone resins, epoxy-based resins, polyvinyl ethers, polycarbonates, and ester-based resins.

The adhesive layer may consist of one layer (single layer) or may consist of two or more layers. When it consists of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 1 to 100 μm, more preferably 1 to 60 μm, and particularly preferably 1 to 30 μm.
Here, "the thickness of the adhesive layer" means the thickness of the entire adhesive layer, and for example, the thickness of an adhesive layer consisting of multiple layers means the total thickness of all layers that make up the adhesive layer.

The pressure-sensitive adhesive layer may be either transparent or non-transparent, and may be colored depending on the purpose.
When the protective film-forming film has energy ray curing properties, the pressure-sensitive adhesive layer is preferably one that transmits energy rays.

The adhesive layer may be either energy ray curable or non-energy ray curable. The physical properties of the energy ray curable adhesive layer can be adjusted before and after curing. For example, by curing the energy ray curable adhesive layer before picking up the chip with the protective film described below, the chip with the protective film can be picked up more easily.

In this specification, even after the energy ray-curable adhesive layer is cured with energy rays, as long as the laminated structure of the substrate and the cured product of the energy ray-curable adhesive layer is maintained, this laminated structure is referred to as a "support sheet."

The adhesive layer can be formed using an adhesive composition containing an adhesive. For example, the adhesive composition can be applied to the surface on which the adhesive layer is to be formed, and then dried as necessary to form the adhesive layer at the desired location. The ratio of the contents of the components in the adhesive composition that do not vaporize at room temperature is usually the same as the ratio of the contents of the components in the adhesive layer.

The adhesive composition can be applied and dried, for example, in the same manner as in the application and drying of the protective film-forming composition described above.

When the adhesive layer is energy ray curable, examples of the energy ray curable adhesive composition include adhesive composition (I-1) containing a non-energy ray curable adhesive resin (I-1a) (hereinafter sometimes abbreviated as "adhesive resin (I-1a)") and an energy ray curable compound; adhesive composition (I-2) containing an energy ray curable adhesive resin (I-2a) (hereinafter sometimes abbreviated as "adhesive resin (I-2a)") in which an unsaturated group has been introduced into the side chain of non-energy ray curable adhesive resin (I-1a); adhesive composition (I-3) containing the adhesive resin (I-2a) and an energy ray curable compound, etc.

When the adhesive layer is non-energy ray curable, examples of the non-energy ray curable adhesive composition include adhesive composition (I-4) containing the non-energy ray curable adhesive resin (I-1a).

[Non-energy ray curable adhesive resin (I-1a)]
The adhesive resin (I-1a) is preferably an acrylic resin.

The acrylic resin may, for example, be an acrylic polymer having at least a structural unit derived from an alkyl (meth)acrylate ester.
The (meth)acrylic acid alkyl ester may, for example, be one in which the alkyl group constituting the alkyl ester has 1 to 20 carbon atoms, and the alkyl group is preferably linear or branched.

The acrylic polymer preferably further contains a structural unit derived from a functional group-containing monomer in addition to the structural unit derived from an alkyl (meth)acrylate ester.
Examples of the functional group-containing monomer include those in which the functional group reacts with a crosslinking agent described below to become a crosslinking starting point.

Examples of the functional group-containing monomer include hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, and epoxy group-containing monomers.

The acrylic polymer may further contain a structural unit derived from another monomer, in addition to the structural unit derived from the alkyl (meth)acrylate ester and the structural unit derived from the functional group-containing monomer.
The other monomer is not particularly limited as long as it is copolymerizable with the (meth)acrylic acid alkyl ester and the like.
Examples of the other monomers include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

In the pressure-sensitive adhesive composition (I-1), pressure-sensitive adhesive composition (I-2), pressure-sensitive adhesive composition (I-3) and pressure-sensitive adhesive composition (I-4) (hereinafter, these pressure-sensitive adhesive compositions are collectively referred to as "pressure-sensitive adhesive compositions (I-1) to (I-4)"), the structural unit of the acrylic resin such as the acrylic polymer may be only one type or may be two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

In the acrylic polymer, the ratio of the amount of structural units derived from functional group-containing monomers to the total amount of structural units is preferably 1 to 35% by mass.

The adhesive resin (I-1a) contained in the adhesive composition (I-1) or the adhesive composition (I-4) may be one type or two or more types. When there are two or more types, the combination and ratio thereof can be selected arbitrarily.

In the adhesive layer formed from the adhesive composition (I-1) or the adhesive composition (I-4), the content of the adhesive resin (I-1a) relative to the total mass of the adhesive layer is preferably 5 to 99 mass%.

[Energy ray-curable adhesive resin (I-2a)]
The adhesive resin (I-2a) can be obtained, for example, by reacting a functional group in the adhesive resin (I-1a) with an unsaturated group-containing compound having an energy ray-polymerizable unsaturated group.

The unsaturated group-containing compound is a compound having, in addition to the energy ray-polymerizable unsaturated group, a group that can bond to the adhesive resin (I-1a) by reacting with a functional group in the adhesive resin (I-1a).
Examples of the energy ray-polymerizable unsaturated group include a (meth)acryloyl group, a vinyl group (ethenyl group), and an allyl group (2-propenyl group), and the like, with a (meth)acryloyl group being preferred.
Examples of the group capable of bonding to a functional group in the adhesive resin (I-1a) include an isocyanate group and a glycidyl group capable of bonding to a hydroxyl group or an amino group, and a hydroxyl group and an amino group capable of bonding to a carboxy group or an epoxy group.

Examples of the unsaturated group-containing compound include (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, and glycidyl (meth)acrylate.

The adhesive resin (I-2a) contained in the adhesive composition (I-2) or (I-3) 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.

In the adhesive layer formed from the adhesive composition (I-2) or (I-3), the content of the adhesive resin (I-2a) relative to the total mass of the adhesive layer is preferably 5 to 99 mass%.

[Energy ray curable compound]
The energy ray-curable compound contained in the pressure-sensitive adhesive composition (I-1) or (I-3) includes a monomer or oligomer having an energy ray-polymerizable unsaturated group and capable of being cured by irradiation with energy rays.

Of the energy ray-curable compounds, examples of the monomer include polyvalent (meth)acrylates such as trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol (meth)acrylate; urethane (meth)acrylate; polyester (meth)acrylate; polyether (meth)acrylate; and epoxy (meth)acrylate.
Among the energy ray-curable compounds, examples of the oligomer include oligomers which are polymers of the monomers exemplified above.

The pressure-sensitive adhesive composition (I-1) or (I-3) may contain only one type of energy ray-curable compound, or two or more types. When two or more types are contained, the combination and ratio of the compounds may be selected arbitrarily.

In the adhesive layer formed from the adhesive composition (I-1) or (I-3), the content of the energy ray curable compound relative to the total mass of the adhesive layer is preferably 1 to 95 mass%.

[Crosslinking agent]
When the acrylic polymer having a structural unit derived from a functional group-containing monomer in addition to a structural unit derived from a (meth)acrylic acid alkyl ester is used as the pressure-sensitive adhesive resin (I-1a), it is preferable that the pressure-sensitive adhesive composition (I-1) or (I-4) further contains a crosslinking agent.
In addition, when the adhesive resin (I-2a) is, for example, the acrylic polymer having a structural unit derived from a functional group-containing monomer similar to that in the adhesive resin (I-1a), the adhesive composition (I-2) or (I-3) may further contain a crosslinking agent.

The crosslinking agent, for example, reacts with the functional group to crosslink the adhesive resins (I-1a) together or the adhesive resins (I-2a) together.
Examples of the crosslinking agent include isocyanate-based crosslinking agents (crosslinking agents having an isocyanate group) such as tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, and adducts of these diisocyanates; epoxy-based crosslinking agents (crosslinking agents having a glycidyl group) such as ethylene glycol glycidyl ether; aziridine-based crosslinking agents (crosslinking agents having an aziridinyl group) such as hexa[1-(2-methyl)-aziridinyl]triphosphatriazine; metal chelate-based crosslinking agents (crosslinking agents having a metal chelate structure) such as aluminum chelate; and isocyanurate-based crosslinking agents (crosslinking agents having an isocyanuric acid skeleton).

The crosslinking agent contained in the pressure-sensitive adhesive compositions (I-1) to (I-4) may be one type or two or more types. When two or more types are contained, the combination and ratio of the crosslinking agents can be selected arbitrarily.

In the pressure-sensitive adhesive composition (I-1) or (I-4), the content of the crosslinking agent is preferably 0.01 to 50 parts by mass per 100 parts by mass of the pressure-sensitive adhesive resin (I-1a).
In the pressure-sensitive adhesive composition (I-2) or (I-3), the content of the crosslinking agent is preferably 0.01 to 50 parts by mass per 100 parts by mass of the pressure-sensitive adhesive resin (I-2a).

[Photopolymerization initiator]
The pressure-sensitive adhesive compositions (I-1), (I-2) and (I-3) (hereinafter collectively referred to as "pressure-sensitive adhesive compositions (I-1) to (I-3)") may further contain a photopolymerization initiator. The pressure-sensitive adhesive compositions (I-1) to (I-3) containing a photopolymerization initiator sufficiently undergo a curing reaction even when irradiated with relatively low-energy energy rays such as ultraviolet rays.

The photopolymerization initiator may be, for example, the same as the photopolymerization initiator (H) described above.

The photopolymerization initiators contained in the pressure-sensitive adhesive compositions (I-1) to (I-3) may be one type or two or more types. When two or more types are contained, the combination and ratio of the photopolymerization initiators can be selected arbitrarily.

In the pressure-sensitive adhesive composition (I-1), the content of the photopolymerization initiator is preferably 0.01 to 20 parts by mass relative to 100 parts by mass of the content of the energy ray-curable compound.
In the pressure-sensitive adhesive composition (I-2), the content of the photopolymerization initiator is preferably 0.01 to 20 parts by mass per 100 parts by mass of the pressure-sensitive adhesive resin (I-2a).
In the pressure-sensitive adhesive composition (I-3), the content of the photopolymerization initiator is preferably 0.01 to 20 parts by mass per 100 parts by mass of the total content of the pressure-sensitive adhesive resin (I-2a) and the energy ray-curable compound.

[Other additives]
The pressure-sensitive adhesive compositions (I-1) to (I-4) may contain other additives that do not fall under any of the above-mentioned components, within the scope that does not impair the effects of the present invention.
Examples of the other additives include known additives such as antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, colorants (pigments, dyes), sensitizers, tackifiers, reaction retarders, and crosslinking accelerators (catalysts).
The reaction retarder is, for example, a component that suppresses the progress of unintended crosslinking reactions in the pressure-sensitive adhesive compositions (I-1) to (I-4) during storage due to the action of a catalyst mixed in the pressure-sensitive adhesive compositions (I-1) to (I-4). Examples of the reaction retarder include those that form a chelate complex by chelating with a catalyst, and more specifically, those that have two or more carbonyl groups (-C(=O)-) in one molecule.

The other additives contained in the pressure-sensitive adhesive compositions (I-1) to (I-4) may be one type only, or two or more types. When there are two or more types, the combination and ratio of the additives can be selected arbitrarily.

The content of other additives in the pressure-sensitive adhesive compositions (I-1) to (I-4) is not particularly limited and may be selected appropriately depending on the type of additive.

[solvent]
The pressure-sensitive adhesive compositions (I-1) to (I-4) may contain a solvent. By containing a solvent, the pressure-sensitive adhesive compositions (I-1) to (I-4) have improved suitability for application to a surface to be coated.

The solvent is preferably an organic solvent, and examples of the organic solvent include ketones such as methyl ethyl ketone and acetone; esters (carboxylates) such as ethyl acetate; ethers such as tetrahydrofuran and dioxane; aliphatic hydrocarbons such as cyclohexane and n-hexane; aromatic hydrocarbons such as toluene and xylene; and alcohols such as 1-propanol and 2-propanol.

The adhesive compositions (I-1) to (I-4) may contain only one type of solvent, or two or more types. When two or more types are contained, the combination and ratio of the solvents can be selected arbitrarily.

The solvent content of the pressure-sensitive adhesive compositions (I-1) to (I-4) is not particularly limited and may be adjusted as appropriate.

Method for Producing the Pressure-Sensitive Adhesive Composition The pressure-sensitive adhesive composition can be produced in the same manner as in the case of the thermosetting protective film-forming composition described above, except that the types of ingredients used are different.

The composite sheet for forming a protective film can be produced by laminating the above-mentioned layers so that they are in a corresponding positional relationship, and adjusting the shape of some or all of the layers as necessary. The method for forming each layer is as described above.

For example, when a pressure-sensitive adhesive layer is laminated on a substrate during the production of a support sheet, the pressure-sensitive adhesive composition may be applied onto the substrate and dried as necessary.
The adhesive layer can also be laminated on the substrate by applying the adhesive composition onto the release film, drying it as necessary, forming an adhesive layer on the release film, and laminating the exposed surface of the adhesive layer to one surface of the substrate. In this case, the adhesive composition is preferably applied to the release-treated surface of the release film. In this case, the release film may be removed at any time during the manufacturing process or the use process of the composite sheet for forming a protective film.
Up to this point, the case where a pressure-sensitive adhesive layer is laminated on a substrate has been taken as an example, but the above-mentioned method can also be applied to, for example, the case where a layer other than the pressure-sensitive adhesive layer is laminated on a substrate.

On the other hand, for example, when a protective film-forming film is laminated on an adhesive layer already laminated on a substrate, a protective film-forming composition can be applied on the adhesive layer to directly form a protective film-forming film. A layer other than the protective film-forming film can also be laminated on the adhesive layer in a similar manner using a composition for forming this layer. In this way, when a new layer (hereinafter abbreviated as "second layer") is formed on any layer (hereinafter abbreviated as "first layer") already laminated on a substrate to form a continuous two-layer laminate structure (in other words, a laminate structure of the first layer and the second layer), a method of applying a composition for forming the second layer on the first layer and drying it as necessary can be applied.
However, it is preferable that the second layer is formed in advance on a release film using a composition for forming the second layer, and the exposed surface of the second layer opposite to the side in contact with the release film is bonded to the exposed surface of the first layer to form a continuous two-layer laminate structure. In this case, it is preferable that the composition is applied to the release-treated surface of the release film. The release film may be removed as necessary after the laminate structure is formed.
Here, we have given an example of laminating a protective film-forming film onto an adhesive layer, but the target laminate structure can be selected arbitrarily, for example, when laminating a layer (film) other than the protective film-forming film onto the adhesive layer.

In this way, all layers other than the substrate that make up the composite sheet for forming a protective film can be formed in advance on a release film and laminated by laminating them to the surface of the desired layer, so the composite sheet for forming a protective film can be manufactured by appropriately selecting the layers that will undergo this process as necessary.

The composite sheet for forming a protective film is usually stored with a release film attached to the surface of the outermost layer (e.g., the protective film-forming film) opposite the support sheet. Therefore, a composition for forming a layer constituting the outermost layer, such as a protective film-forming composition, is applied to this release film (preferably its release-treated surface) and dried as necessary to form a layer constituting the outermost layer on the release film, and the remaining layers are laminated on the exposed surface opposite the side in contact with the release film, and the release film is not removed and the laminated state is left in place to obtain a composite sheet for forming a protective film with a release film.

◇Wafer recycling method A wafer recycling method according to one embodiment of the present invention is a method for recycling a wafer by attaching the protective film-forming film or the protective film-forming film in the protective film-forming composite sheet according to one embodiment of the present invention described above to the back surface of a wafer, and then peeling the protective film-forming film from the back surface of the wafer to make the back surface of the wafer in a state in which the protective film-forming film can be reattached.
In the wafer recycling method of this embodiment, by using the protective film-forming film, the protective film-forming film can be normally and easily peeled off from the back surface of the wafer even if the back surface of the wafer is rough, so that the method is excellent in terms of suitability for wafer recycling.

Below, with reference to the drawings, we will explain in order a method for recycling a wafer when a protective film-forming film that is not part of a composite sheet for forming a protective film is attached to the rear surface of the wafer (sometimes referred to as "recycling method 1" in this specification), and a method for recycling a wafer when a protective film-forming film included in a composite sheet for forming a protective film is attached to the rear surface of the wafer (sometimes referred to as "recycling method 2" in this specification).

<<Playback method 1>>
6 is a cross-sectional view for explaining an example of a wafer recycling method and an example of a method for reattaching a protective film-forming film according to the present embodiment. Here, a recycling method 1 will be explained as a wafer recycling method, taking as an example a case where the protective film-forming film 13 shown in FIG. 1 is used.

In recycling method 1, as shown in FIG. 6(a), the protective film-forming film 13 is attached to the back surface 9b of the wafer 9. Here, the first release film 151 is removed from the protective film-forming film 13 with the release film, and the first surface 13a of the protective film-forming film 13 exposed thereby is attached to the back surface 9b of the wafer 9. In this embodiment, the second release film 152 may be removed from the protective film-forming film 13 with the release film, and the second surface 13b of the protective film-forming film 13 exposed thereby may be attached to the back surface 9b of the wafer 9 (not shown).

In recycling method 1, it is preferable that the rear surface 9b of the wafer 9 is a rough surface on which the recesses are present. When the rear surface 9b of the wafer 9 is rough, the effect of using the protective film-forming film 13 is significantly obtained.

The back surface 9b of the wafer 9 is preferably ground with a grinding wheel having a coarser specification than #2000, more preferably with a grinding wheel having a coarser specification than #1500, and even more preferably with a grinding wheel having a coarser specification than #1000. With such a wafer 9, the effect of using the protective film-forming film 13 is more pronounced.

The protective film forming film 13 can be attached to the wafer 9 by a known method, such as a method using a roll.

The conditions for attaching the protective film-forming film 13 to the wafer 9 are not particularly limited. When the back surface 9b of the wafer 9 is rough, in order to be able to fill the recesses more thoroughly with the protective film-forming film 13, it is preferable that the temperature of the protective film-forming film 13 during attachment (attachment temperature) is 20 to 100°C, the speed at which the protective film-forming film 13 is attached (attachment speed) is 0.1 to 2 m/min, and the pressure applied to the protective film-forming film 13 during attachment (attachment pressure) is 0.1 to 0.6 MPa.

In the regeneration method 1, the protective film-forming film 13 is then peeled off from the back surface 9b of the wafer 9 as shown in FIG. 6(d). To do so, for example, the second release film 152 is removed from the protective film-forming film 13 attached to the wafer 9. Then, as shown in FIG. 6(b), an adhesive tape 6 is attached to the second surface 13b of the protective film-forming film 13 exposed thereby, for peeling the resin film such as the protective film-forming film from the object to which it is attached. Next, as shown in FIG. 6(c), the laminate of the protective film-forming film 13 and the adhesive tape 6 is peeled off from the back surface 9b of the wafer 9. For example, if the adhesive tape 6 is curable and is soft in an uncured state and becomes hard when cured, the uncured adhesive tape 6 may be attached to the protective film-forming film 13, the adhesive tape 6 may then be cured, and the laminate of the protective film-forming film 13 and the cured product of the adhesive tape 6 may be peeled off from the back surface 9b of the wafer 9. In this way, the protective film-forming film 13 can be more easily peeled off from the rear surface 9b of the wafer 9. In FIG. 6, both the adhesive tape and its cured product are indicated with the reference numeral 6.

The adhesive tape 6 is not particularly limited as long as it has high adhesive strength to the protective film-forming film 13, and may be any known adhesive tape.

When the protective film-forming film 13 is attached to the back surface 9b of the wafer 9, there is a possibility that an abnormality in attachment may occur, such as, for example, the attachment position of the protective film-forming film 13 being shifted, or the protective film-forming film 13 being attached with a foreign object sandwiched between the back surface 9b of the wafer 9 and the attachment surface of the protective film-forming film 13 (first surface 13a in FIG. 6). In contrast, in the regeneration method 1, even if the back surface 9b of the wafer 9 is rough, the protective film-forming film 13 is peeled off from the back surface 9b of the wafer 9 without damaging the wafer 9, and without leaving a part of the protective film-forming film 13 on the back surface 9b of the wafer 9 in an amount that would deteriorate the suitability of the wafer 9 for subsequent use, and is peeled off normally and easily. Therefore, the protective film-forming film 13 can be regenerated by making the back surface 9b of the wafer 9 in a state where the protective film-forming film can be reattached.

When a portion of the protective film-forming film 13 remains on the back surface 9b of the wafer 9 after the protective film-forming film 13 has been peeled off, in an amount that does not impair the suitability of the wafer 9 for subsequent use, the remaining protective film-forming film 13 can be removed, for example, by a known method. More specifically, for example, the adhesive surface of the adhesive tape 6 or another adhesive tape can be attached to the area of the back surface 9b of the wafer 9 where the remaining protective film-forming film 13 exists, and then the adhesive tape can be peeled off from the back surface 9b of the wafer 9, so that the remaining protective film-forming film 13 can be transferred from the back surface 9b of the wafer 9 to the adhesive surface of the adhesive tape and removed.

After the wafer 9 has been regenerated by the regeneration method 1, for example, as shown in FIG. 6(e), a protective film-forming film 13 prepared separately from the one that was peeled off can be re-attached to the back surface 9b of the regenerated wafer 9. Here, the protective film-forming film 13 with the second release film 152 is re-attached as in the case of the initial attachment, but a protective film-forming film 13 with the first release film 151 may also be re-attached. Also, instead of the protective film-forming film 13 with the release film, the protective film-forming film in the composite sheet for forming a protective film may be re-attached to the back surface 9b of the wafer 9.

Reattachment of a protective film-forming film such as the protective film-forming film 13 to the wafer 9 can be performed, for example, in the same manner as the initial attachment of the protective film-forming film 13 to the wafer 9, as described above.

In this embodiment, by reattaching the protective film-forming film 13, a laminated film 501 is obtained that includes the wafer 9 and the protective film-forming film 13 provided on the rear surface 9b of the wafer 9. A similar laminated film can be obtained even when a protective film-forming film other than the protective film-forming film 13 is used. Furthermore, by using a laminated film such as the laminated film 501, the desired chip with a protective film can be manufactured.

<<Reproduction method 2>>
7 is a cross-sectional view for explaining another example of the wafer recycling method of the present embodiment and an example of a method for reattaching the protective film-forming film. Here, a recycling method 2 will be explained as a wafer recycling method by taking the case where the protective film-forming composite sheet 101 shown in FIG. 2 is used as an example.

In recycling method 2, as shown in FIG. 7(a), the protective film-forming film 13 in the protective film-forming composite sheet 101 is attached to the back surface 9b of the wafer 9. More specifically, the release film 15 is removed from the protective film-forming film 13, and the first surface 13a of the protective film-forming film 13 thus exposed is attached to the back surface 9b of the wafer 9. That is, the protective film-forming film 13 is attached by attaching the protective film-forming composite sheet 101.

In recycling method 2, it is also preferable that the rear surface 9b of the wafer 9 is a rough surface on which the recesses are present. When the rear surface 9b of the wafer 9 is rough, the effect of using the protective film-forming film 13 is significantly obtained.

The composite sheet for forming a protective film 101 can be attached to the wafer 9 in the same manner as the protective film-forming film 13 is attached to the wafer 9 in the recycling method 1.
The conditions for attaching the protective film-forming composite sheet 101 to the wafer 9 are not particularly limited, and may be the same as the conditions for attaching the protective film-forming film 13 to the wafer 9 in the recycling method 1.

In recycling method 2, the protective film-forming film 13 is then peeled off from the rear surface 9b of the wafer 9 as shown in FIG. 7(c). To do so, for example, as shown in FIG. 7(b), the protective film-forming film 13 is peeled off together with the support sheet 10, i.e., the protective film-forming composite sheet 101 is peeled off as is, from the rear surface 9b of the wafer 9.

When the protective film-forming film 13 in the composite sheet 101 for forming a protective film is attached to the back surface 9b of the wafer 9, there is a possibility that an attachment abnormality similar to that when the protective film-forming film 13 is attached to the back surface 9b of the wafer 9 in the recycling method 1 may occur. In contrast, even in the recycling method 2, even if the back surface 9b of the wafer 9 is rough, the protective film-forming film 13 is peeled off from the back surface 9b of the wafer 9 without damaging the wafer 9, and without leaving a part of the protective film-forming film 13 on the back surface 9b of the wafer 9 in an amount that would deteriorate the suitability of the wafer 9 for subsequent use, and is peeled off normally and easily. Therefore, the protective film-forming film 13 can be recycled by making the back surface 9b of the wafer 9 in a state where the protective film-forming film can be reattached.

If a portion of the protective film-forming film 13 remains on the back surface 9b of the wafer 9 after the protective film-forming film 13 has been peeled off, in an amount that does not impair the suitability of the wafer 9 for subsequent use, the remaining protective film-forming film 13 can be removed from the back surface 9b of the wafer 9 in the same manner as in the case of recycling method 1.

After the wafer 9 is regenerated by the regeneration method 2, for example, as shown in FIG. 7(d), the protective film-forming film 13 in the composite sheet 101 for forming a protective film, which is prepared separately from the one that was peeled off, can be re-attached to the back surface 9b of the regenerated wafer 9. Here, the case where the protective film-forming film 13 in the composite sheet 101 for forming a protective film is re-attached as in the case of the initial attachment is shown, but the protective film-forming film in the composite sheet for forming a protective film other than the composite sheet 101 for forming a protective film (for example, the composite sheet 102 for forming a protective film, the composite sheet 103 for forming a protective film, or the composite sheet 104 for forming a protective film shown in FIG. 3 to FIG. 5) may be re-attached. That is, the re-attachment of the protective film-forming film such as the protective film-forming film 13 is performed by attaching the composite sheet for forming a protective film such as the composite sheet 101 for forming a protective film.
In addition, instead of the protective film forming film 13 in the composite sheet 101 for forming a protective film, a protective film forming film 13 with a release film (e.g., a protective film forming film 13 with a second release film 152, or a protective film forming film 13 with a first release film 151) may be re-attached to the rear surface 9b of the wafer 9.

The reattachment of a protective film-forming film such as the protective film-forming film 13 in the composite sheet 101 for forming a protective film to the wafer 9 can be performed, for example, in the same manner as the initial attachment of the protective film-forming film 13 to the wafer 9 described above.

In this embodiment, by reattaching the protective film-forming film 13 in the composite sheet 101 for forming a protective film, a laminated composite sheet 401 is obtained in which the support sheet 10, the protective film-forming film 13, and the wafer 9 are laminated in this order in the thickness direction. A similar laminated composite sheet can be obtained even when a protective film-forming film other than the protective film-forming film 13 in the composite sheet 101 for forming a protective film is used. Furthermore, by using a laminated composite sheet such as the laminated composite sheet 401, the desired chip with a protective film can be manufactured.

◇ Method for manufacturing chips with protective film (method for using protective film-forming film and composite sheet for protective film-forming)
The protective film-forming film and the composite sheet for forming a protective film can be used for producing the chip with the protective film.

<<Manufacturing method 1>>
In a manufacturing method of a chip with a protective film in the case where a protective film-forming film that does not constitute a composite sheet for forming a protective film is attached to the rear surface of a wafer (sometimes referred to as "manufacturing method 1" in this specification), the protective film is formed from the protective film-forming film that does not constitute the composite sheet for forming a protective film, and when the protective film-forming film is curable, a cured product of the protective film-forming film is the protective film, and when the protective film-forming film is non-curable, the protective film-forming film after being attached to the rear surface of the wafer is the protective film, and the manufacturing method of the chip with a protective film includes a bonding step of bonding the protective film-forming film to the rear surface of the wafer to produce a first laminate in which the protective film-forming film or protective film is provided (laminated) on the rear surface of the wafer. and after the laminating step, a laminating step of laminating a dicing sheet on the surface of the protective film-forming film or protective film opposite the wafer side, or on the surface of the wafer opposite the protective film-forming film side or protective film side. After the laminating step, a dividing step of producing the chip by dividing (dicing) the wafer. After the laminating step, a cutting step of cutting the protective film-forming film or protective film. After the laminating step, a picking up step of separating the chip having the protective film-forming film or protective film after cutting from the dicing sheet and picking it up. In the case where the protective film-forming film is curable, the method for producing a chip with a protective film further includes a curing step of forming the protective film by curing the protective film-forming film after the laminating step.

The manufacturing method 1 may further include, between the attachment step and the pick-up step, a printing step of printing on the protective film-forming film or protective film in the first laminate by irradiating the protective film-forming film or protective film with laser light from the outside opposite the wafer side of the protective film-forming film or protective film, either directly or through the dicing sheet.

When the printing step is performed before the lamination step, it is preferable that the surface of the protective film-forming film or protective film that is the target for laminating the dicing sheet in the lamination step is the surface that has been printed in the printing step.
The dicing sheet may be a known one, and may be the same as the support sheet.
The lamination step can be carried out by a known method.

In this embodiment, it is preferable that after the lamination step, the division step and the cutting step are carried out simultaneously, or the division step is carried out before the cutting step.
In this embodiment, if the dividing of the wafer and the cutting of the protective film-forming film or protective film are performed consecutively by the same operation without interruption, regardless of the order, the dividing process and the cutting process are deemed to be performed simultaneously.

The dividing and cutting steps can be carried out by known methods depending on the order in which they are carried out.

When the cutting step is performed after the dividing step, particularly when the wafer is a semiconductor wafer, the wafer can be divided (in other words, diced) by, for example, stealth dicing (registered trademark) or laser dicing.
Stealth dicing (registered trademark) is a method as follows. That is, first, a planned division location is set inside the semiconductor wafer, and a laser beam is irradiated so as to converge on this location as a focal point, thereby forming a modified layer inside the semiconductor wafer. The modified layer of the semiconductor wafer is different from other locations of the semiconductor wafer, and is altered by the irradiation of the laser beam, and has a weaker strength. Therefore, when a force is applied to the semiconductor wafer, a crack extending in the direction of both sides of the semiconductor wafer occurs in the modified layer inside the semiconductor wafer, which becomes the starting point for dividing the semiconductor wafer. Next, a force is applied to the semiconductor wafer to divide the semiconductor wafer at the site of the modified layer, and semiconductor chips are produced.

When the cutting step is performed after the dividing step, the protective film-forming film or protective film can be cut, for example, by pulling the protective film-forming film or protective film in a direction parallel to the surface to which it is attached to the chip, that is, by expanding. The expanded protective film-forming film or protective film is cut along the outer periphery of the chip. Such cutting by expanding is preferably performed at a low temperature such as -20 to 5°C.

When the dividing step and the cutting step are performed simultaneously, the wafer can be divided and the protective film-forming film or protective film can be cut simultaneously by dicing such as blade dicing using a blade, laser dicing by laser irradiation, or water dicing by spraying water containing an abrasive.
In addition, by expanding a semiconductor wafer on which a modified layer has been formed by Stealth Dicing (registered trademark) and which has not been divided, together with a protective film-forming film or a protective film, in a manner similar to that described above, it is possible to simultaneously divide the semiconductor wafer and cut the protective film-forming film or protective film.

When the cutting process is performed before the dividing process, the protective film-forming film or protective film can be cut without dividing the wafer by using the same dicing techniques as described above, and the wafer can then be divided by breaking or using the same dicing techniques as described above.

In the pick-up process, the cut protective film-forming film or the chip with the protective film can be detached from the dicing sheet by a known method, such as using a vacuum collet as a detachment means.

The manufacturing method (1) may include, in addition to the steps of the attaching step, the curing step, the printing step, the laminating step, the dividing step, the cutting step, and the picking up step, other steps not corresponding to any of these steps.
The types of the other steps and the timing of carrying them out can be arbitrarily selected depending on the purpose, and are not particularly limited.

<<Manufacturing method 2>>
In a manufacturing method of a chip with a protective film in a composite sheet for forming a protective film, which is attached to the rear surface of a wafer (sometimes referred to as "manufacturing method 2" in this specification), the protective film is formed from the protective film-forming film in the composite sheet for forming a protective film. When the protective film-forming film is curable, the cured product of the protective film-forming film is the protective film. When the protective film-forming film is non-curable, the protective film-forming film after being attached to the rear surface of the wafer is the protective film. The manufacturing method of the chip with a protective film includes a bonding step of bonding the protective film-forming film in the composite sheet for forming a protective film to the rear surface of the wafer to prepare a second laminate in which the composite sheet for forming a protective film is provided (laminated) on the rear surface of the wafer, a division step of dividing the wafer after the bonding step to prepare the chip, and a cutting step of cutting the protective film-forming film or the protective film after the bonding step. and a pick-up process of separating the protective film-forming film or the chip provided with a protective film after cutting from the support sheet and picking it up, and if the protective film-forming film is curable, further comprising a curing process of forming the protective film by curing the protective film-forming film after the attachment process.

The manufacturing method 2 may further include, after the pasting step, a printing step of printing on the protective film-forming film or protective film in the composite sheet for forming a protective film in the second laminate by irradiating laser light from the outside of the composite sheet for forming a protective film on the support sheet side.

Manufacturing method 2 is the same as manufacturing method 1, except that a composite sheet for forming a protective film is used instead of a protective film-forming film that does not constitute a composite sheet for forming a protective film, and the lamination process is not performed. If necessary, other processes different from those in manufacturing method 1 may be added.

◇ Manufacturing method of substrate device (method of using chip with protective film)
After the chip with a protective film is obtained by the above-mentioned manufacturing method, a substrate device can be manufactured in the same manner as the conventional substrate device manufacturing method, except that the chip with a protective film is used in place of the conventional substrate device.

As a manufacturing method for such a substrate device, for example, there is a manufacturing method having a flip chip connection process in which the protruding electrodes on the chip with the protective film obtained using the protective film-forming film are brought into contact with the connection pads on the circuit board, thereby electrically connecting the protruding electrodes and the connection pads on the circuit board.

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

<Raw materials for resin production>
The full names of the raw materials for producing the resins, which are abbreviated in the present examples and comparative examples, are shown below.
MA: Methyl acrylate HEA: 2-hydroxyethyl acrylate 2EHA: 2-ethylhexyl acrylate GMA: Glycidyl methacrylate AAc: Acrylic acid MMA: Methyl methacrylate

<Materials for producing the protective film-forming composition>
The raw materials used in the production of the composition for forming a protective film are shown below.
[Polymer component (A)]
(A)-1: Acrylic polymer obtained by copolymerizing 2EHA (65 parts by mass), MA (14 parts by mass), GMA (5 parts by mass), AAc (1 part by mass) and HEA (15 parts by mass) (weight average molecular weight: 850,000, glass transition temperature: -49°C)
(A)-2: Acrylic polymer obtained by copolymerizing 2EHA (65 parts by mass), MMA (25 parts by mass) and HEA (10 parts by mass) (weight average molecular weight: 500,000, glass transition temperature: -38°C)
(A)-3: Acrylic copolymer ("Teisan Resin SG-P3" manufactured by Nagase Chemtex Corporation)
(A)-4: Acrylic polymer obtained by copolymerizing MA (87 parts by mass) and HEA (13 parts by mass) (weight average molecular weight: 500,000, glass transition temperature: 6° C.)
(A)-5: Acrylic polymer obtained by copolymerizing MA (97 parts by mass) and HEA (3 parts by mass) (weight average molecular weight: 500,000, glass transition temperature: 9° C.)
[Epoxy resin (B1)]
(B1)-1: Bisphenol A type epoxy resin ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 184 to 194 g/eq)
(B1)-2: Bisphenol A type epoxy resin ("jER834" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 230 to 270 g/eq)
(B1)-3: Dicyclopentadiene type epoxy resin (DIC Corporation, "Epicron HP-7200", epoxy equivalent: 254 to 264 g/eq)
(B1)-4: Dicyclopentadiene type epoxy resin ("XD-1000" manufactured by Nippon Kayaku Co., Ltd.), epoxy equivalent: 245 to 260 g/eq)
[Thermal curing agent (B2)]
(B2)-1: Dicyandiamide (thermally activated latent epoxy resin curing agent, "DICY7" manufactured by Mitsubishi Chemical Corporation)
[Curing Accelerator (C)]
(C)-1: 2-phenyl-4,5-dihydroxymethylimidazole ("Curesol 2PHZ" manufactured by Shikoku Chemical Industries, Ltd.)
[Filler (D)]
(D)-1: Silica filler ("SC2050MA" manufactured by Admatechs Co., Ltd., spherical silica filler surface-modified with an epoxy compound, average particle size 0.5 μm)
[Coupling Agent (E)]
(E)-1: Oligomeric silane coupling agent having an epoxy group, a methyl group, and a methoxy group ("X-41-1056" manufactured by Shin-Etsu Chemical Co., Ltd., epoxy equivalent: 280 g/eq)
[Colorant (I)]
(I)-1: Organic black pigment ("6377 Black" manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)

[Example 1]
<<Production of protective film-forming film>>
<Production of protective film-forming composition (III)-1>
Polymer component (A)-1 (25 parts by mass), epoxy resin (B1)-1 (10 parts by mass), epoxy resin (B1)-3 (5 parts by mass), heat curing agent (B2)-1 (0.1 parts by mass), curing accelerator (C)-1 (0.1 parts by mass), filler (D)-1 (57.5 parts by mass), coupling agent (E)-1 (0.3 parts by mass) and colorant (I)-1 (2 parts by mass) were dissolved or dispersed in methyl ethyl ketone and stirred at 23°C to obtain a thermosetting protective film-forming composition (III)-1 having a total concentration of all components other than the solvent of 60% by mass. The amounts of all components other than methyl ethyl ketone shown here are the amounts of the target product not including the solvent.

<Production of protective film-forming film>
A release film (second release film, "SP-PET502150" manufactured by Lintec Corporation, thickness 50 μm) made of polyethylene terephthalate film, one side of which had been subjected to a release treatment by silicone treatment, was used, and the protective film-forming composition (III)-1 obtained above was applied to the release-treated surface, followed by drying at 100°C for 2 minutes to produce a thermosetting protective film-forming film having a thickness of 40 μm.

Furthermore, the release-treated surface of a release film (first release film, "SP-PET381031" manufactured by Lintec Corporation, thickness 38 μm) was attached to the exposed surface of the obtained protective film-forming film on the side not provided with the second release film under conditions of an attachment speed of 2 m/min, an attachment temperature of 60°C, and an attachment pressure of 0.5 MPa, thereby obtaining a protective film-forming film with a release film, which is configured to include a protective film-forming film, a first release film provided on one side of the protective film-forming film, and a second release film provided on the other side of the protective film-forming film.

<<Evaluation of protective film-forming film>>
<Measurement of surface roughness (Ra)>
The first release film was removed from the protective film-forming film in the protective film-forming film with release film obtained above.Then, the exposed surface of the protective film-forming film (the surface to be attached to the wafer, the first surface) was measured for surface roughness (Ra) using an optical interference surface profiler ("WYKO NT1100" manufactured by Veeco Metrology Group) under the following measurement conditions in accordance with ANSI/ASME B46.1.The results are shown in Table 1.
[Measurement conditions]
Objective lens magnification: 10x Internal lens magnification: 1x Mode: PSI
Measurement area: 0.35mm ²

<Measurement of strain (0.1 N/mm ² ) and strain (0.6 N/mm ² )>
Using the five protective film-forming films with release films obtained above, the exposed surfaces of the protective film-forming films were sequentially bonded together while removing the first release film or the second release film, to produce a laminate consisting of the second release film, five protective film-forming films (total thickness 200 μm), and the second release film laminated in this order. Then, a piece having a width of 15 mm was cut out from this laminate.
Next, the two outermost second release films were removed from this piece to obtain a test piece.

A pair of grips (two pieces) were attached to the test piece (thickness 200 μm) obtained above with a gap of 30 mm between them to hold the test piece at two points. A tensile test was then performed using a precision universal testing machine (Shimadzu Corporation's "Autograph AG-IS"), in which the test piece was pulled between the two points by the grips in a direction parallel to the surface at a speed of 1000 mm/min. This tensile test was terminated when the strain of the test piece reached 350%. During this time, the strain (0.1 N/mm ² ) and the strain (0.6 N/mm ² ) were measured. The results are shown in Table 1.

<Evaluation of Wafer Reclaim Suitability>
A silicon wafer having a diameter of 200 mm and a thickness of 350 μm was prepared, the surface to which the protective film was attached (hereinafter referred to as the “rear surface”) being ground to #340, resulting in a rougher ground surface than usual.

A piece with a diameter 5 mm smaller than the diameter of the silicon wafer was cut out from the protective film-forming film with release film obtained above, and the first release film was removed from the protective film-forming film to expose one side of the protective film-forming film.

The exposed surface (first surface) of the protective film-forming film was then placed opposite the rear surface (ground surface) of the silicon wafer, and the protective film-forming film was attached to the rear surface of the silicon wafer using a roll at an attachment speed of 0.3 m/min and an attachment pressure of 0.3 MPa while being heated to 70°C. At this time, the protective film-forming film and the silicon wafer were aligned so as to be concentric.

Next, the second release film was removed from the protective film-forming film after application, and a peeling tape "D-841" (hereinafter referred to as "peeling tape" for convenience) manufactured by Lintec Corporation was applied to the entire exposed surface (the surface opposite to the surface applied to the silicon wafer, the second surface) of the protective film-forming film thus obtained using a squeegee. Then, the peeling tape was irradiated with ultraviolet light using an ultraviolet irradiation device under conditions of an illuminance of 230 mW/cm ² and a light quantity of 190 mJ/cm ² to harden the peeling tape.
Next, the laminate of the protective film-forming film and the peeling tape was peeled off from the rear surface of the silicon wafer, and the degree to which the protective film-forming film remained on the rear surface was confirmed.

Next, if even a small amount of the protective film-forming film remained on the back surface of the silicon wafer, the peeling tape ("D-841" manufactured by Lintec Corporation) was reattached to the relevant portion of the back surface, and the peeling tape was irradiated with ultraviolet light under the same conditions as above to harden the peeling tape. Then, an attempt was made to remove the remaining protective film-forming film from the back surface by peeling the peeling tape from the back surface of the silicon wafer. The extent to which the protective film-forming film remained on the back surface was then confirmed.

Next, the suitability of the protective film-forming film for regenerating the wafer was evaluated according to the following criteria. The results are shown in Table 1.
[Evaluation Criteria]
A: No residual protective film was found on the back surface of the wafer, and reapplication of the peeling tape was not necessary.
B1: Remnants of the protective film-forming film were found on the back surface of the wafer, but the area of the remnants was less than 10% of the total area of the back surface of the wafer, and the remnants could be completely removed by reapplying the peeling tape.
B2: Remnants of the protective film-forming film were found on the back surface of the wafer, and the area of the remnants was 10% or less of the total area of the back surface of the wafer, but the remnants could not be completely removed by the reapplied peeling tape.
C1: Remnants of the protective film-forming film were found on the back surface of the wafer, and the area of the remnants was more than 10% and less than 40% of the total area of the back surface of the wafer, but the remnants could be completely removed by reapplying the peeling tape.
C2: Remnants of the protective film-forming film were found on the back surface of the wafer, the area of the remnants was more than 10% and less than 40% of the total area of the back surface of the wafer, and the remnants could not be completely removed by reapplying the peeling tape.
D: Remaining protective film-forming film was found on the back surface of the wafer, and the area of this region was more than 40% and 80% or less of the total area of the back surface of the wafer.
E: Remaining protective film-forming film was observed on the back surface of the wafer, and the area of this region was more than 80% of the total area of the back surface of the wafer.

<<Production and evaluation of protective film-forming film>>
[Examples 2 to 7, Comparative Examples 1 to 3]
A protective film-forming film was produced and evaluated in the same manner as in Example 1, except that at least one of the types and amounts of the components was changed so that the components and amounts of the protective film-forming film were as shown in Table 1 or Table 2. The results are shown in Table 1 or Table 2.

As is clear from the above results, the regeneration suitability of the wafer of the protective film-forming film was good in Examples 1 to 7. And, in Examples 1 to 7, when evaluating the regeneration suitability of the wafer of the protective film-forming film, no damage to the silicon wafer was observed.
In Examples 1 to 7, the surface roughness (Ra) of the surface of the protective film-forming film to be attached to the wafer was 43 nm or less, and the unevenness was low. The strain of the test piece (0.1 N/mm ² ) was 0.7% or more, and the strain of the test piece (0.6 N/mm ² ) was 15.2% or less. The test pieces of Examples 1 to 7 did not break until the strain reached 350% (i.e., until the tensile test was completed).

In contrast, the recyclability of the wafer of the protective film-forming film was clearly poor in Comparative Examples 1 to 3. However, in Comparative Examples 1 to 3, no damage to the silicon wafer was observed when evaluating the recyclability of the wafer of the protective film-forming film.
In Comparative Examples 1 to 3, the surface roughness (Ra) of the surface of the protective film-forming film to be attached to the wafer was 42 nm or less, and the unevenness was low as in Examples 1 to 7. However, in Comparative Examples 1 and 2, the strain (0.1 N/mm ² ) of the test piece was 0.2% or less, and in Comparative Example 3, the strain (0.6 N/mm ² ) of the test piece was 330%. The test pieces of Comparative Examples 1 to 3 did not break until the strain reached 350%.

It was confirmed that all of the protective film-forming films of Examples 1 to 7 and Comparative Examples 1 to 3 were able to successfully form the desired protective film through thermal curing.

The present invention can be used in the manufacture of various substrate devices, including semiconductor devices.

10, 20 ... Support sheet; 10a, 20a ... One side (first side) of the support sheet;
11... Base material,
12... Adhesive layer,
13, 23... Protective film-forming film,
101, 102, 103, 104 ... Composite sheet for forming protective film,
9: Wafer, 9b: Back surface of wafer

Claims (8)

A protective film-forming film,
A protective film-forming film in which a test piece which is a laminate of multiple sheets of the protective film-forming film is held at two points spaced 30 mm apart, and the test piece is pulled between the two points in a direction parallel to its surface at a speed of 1000 mm/min, and a tensile test is performed to measure the stress generated in the test piece and the strain of the test piece in the tensile direction.When the stress first reaches 0.1 N/ ^mm2 , the strain is 0.5% or more, and when the stress first reaches 0.6 N/ ^mm2 , the strain is 200% or less, and the test piece does not break in the tensile test until the strain reaches 350% . A protective film-forming film,
A test piece which is a laminate of a plurality of the protective film-forming films is held at two points spaced 30 mm apart, and the test piece is pulled between the two points in a direction parallel to its surface at a speed of 1000 mm/min. When a tensile test is performed to measure the stress generated in the test piece and the strain of the test piece in the tensile direction, the strain is 0.5% or more when the stress first reaches 0.1 N/ ^mm2 , and the strain is 200% or less when the stress first reaches 0.6 N/ ^mm2 ,
The protective film-forming film has a first release film on one surface thereof and a second release film on the other surface opposite to the one surface thereof,
The protective film-forming film is used by removing either one of the first release film or the second release film, attaching the resulting exposed surface to the back surface of a wafer, and removing the other remaining one of the first release film and the second release film. The protective film-forming film according to claim 2 , wherein the test piece does not break in the tensile test until the strain reaches 350%. The protective film-forming film according to claim 1 , wherein the protective film-forming film is curable. The protective film-forming film according to claim 4 , wherein the protective film-forming film is thermosetting. A support sheet and a protective film-forming film provided on one surface of the support sheet,
A composite sheet for forming a protective film, wherein the protective film-forming film is the protective film-forming film according to any one of claims 1 to 5 . A composite sheet for forming a protective film, comprising a support sheet and a protective film-forming film provided on one surface of the support sheet,
A test piece which is a laminate of a plurality of the protective film-forming films is held at two points spaced 30 mm apart, and the test piece is pulled between the two points in a direction parallel to its surface at a speed of 1000 mm/min. When a tensile test is performed to measure the stress generated in the test piece and the strain of the test piece in the tensile direction, the strain is 0.5% or more when the stress first reaches 0.1 N/mm2, and the strain is 200% or less when the stress first reaches 0.6 N ^/ mm2 ^,
The protective film-forming film is curable,
The composite sheet for forming a protective film is intended to carry out the following steps: an attachment step of attaching the protective film-forming film in the composite sheet for forming a protective film to the back surface of a wafer; a curing step of forming a protective film by curing the protective film-forming film after the attachment step; a dividing step of producing chips by dividing the wafer after the attachment step; a cutting step of cutting the protective film-forming film or protective film after the attachment step; and a picking up step of separating the chips having the protective film-forming film or protective film after the cutting from the support sheet and picking them up . A method for regenerating a wafer, comprising: attaching a protective film-forming film according to any one of claims 1 to 5 , or a protective film-forming film in a composite sheet for forming a protective film according to claim 6 or 7 , to a rear surface of a wafer; peeling the protective film-forming film from the rear surface of the wafer; and leaving the rear surface of the wafer in a state in which the protective film-forming film can be reattached, thereby regenerating the wafer.

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