JP7766535B2 - Support sheet, method for manufacturing a workpiece, and method for picking up a workpiece - Google Patents

Description

The present invention relates to a support sheet, a method for manufacturing a workpiece, and a method for picking up a workpiece.

A support sheet is used when processing a workpiece such as a wafer to produce a workpiece such as a chip. A typical support sheet is composed of a base material and an adhesive layer provided on one side of the base material. The adhesive layer in the support sheet is, for example, attached to the workpiece to be processed, and the support sheet secures the workpiece during processing. When the processing is dicing, the support sheet functions as a dicing sheet. The resulting workpiece is finally separated from the support sheet, picked up, and used for its intended purpose. In this case, if the adhesive layer is energy ray curable, curing the adhesive layer with energy rays reduces the adhesive force between the cured product and the workpiece, making it easier to pick up the workpiece.

A protective film-forming film for forming a protective film on the workpiece may also be provided on the surface of the adhesive layer opposite the substrate side, thereby forming a composite sheet for forming a protective film. The protective film-forming film in the composite sheet for forming a protective film is, for example, attached to the workpiece to be processed, and the composite sheet for forming a protective film fixes the workpiece during processing and forms a protective film on the workpiece or workpiece product. The resulting workpiece product, still equipped with the protective film, is finally separated from the support sheet, picked up, and used for its intended purpose. As above, if the adhesive layer is energy ray-curable, curing the adhesive layer with energy rays makes it easier to pick up the workpiece product equipped with the protective film.

On the other hand, support sheets are sometimes heated with a workpiece or workpiece product attached to them. This heating is sometimes carried out, for example, to remove foreign matter, such as low-molecular-weight resin components, adhering to the surface of the workpiece. It may also be carried out to dry the workpiece product after washing with water to remove fine foreign matter that is generated during processing such as dicing the workpiece and adheres to the surface of the workpiece. These heating processes are usually carried out with an upper heating temperature of around 135°C. However, if the support sheet has insufficient heat resistance, heating a support sheet with a workpiece or workpiece product attached to it at such a temperature may ultimately make it impossible to pick up the workpiece product from the support sheet.

A support sheet (workpiece processing sheet) that is heat-resistant and suitable for heating has been disclosed, which includes a substrate and an adhesive layer, and in which the Young's modulus of the substrate at 23°C after heating at 120°C for 4 hours and the storage modulus E' of the substrate at 120°C are both specified within specific ranges (see Patent Document 1).

Japanese Patent Application Laid-Open No. 2021-119592

However, after the workpiece is attached and before the workpiece is picked up, the support sheet may be stretched in a direction parallel to its surface, a process known as expanding. For example, in Stealth Dicing (registered trademark), which will be described later, a modified layer is formed inside the semiconductor wafer, and the semiconductor wafer in this state is held on the support sheet. The support sheet is then expanded, dividing the semiconductor wafer at the modified layer to produce semiconductor chips.

For example, at the locations where the semiconductor wafer is to be divided into semiconductor chips, a groove is formed by cutting a notch in the thickness direction of the semiconductor wafer, a so-called half cut, and the semiconductor wafer in this state is held on a support sheet. The support sheet is then expanded, dividing the semiconductor wafer at the groove locations to produce semiconductor chips.

For example, a group of semiconductor chips formed by dividing a semiconductor wafer, in which many semiconductor chips are aligned, can be held on a support sheet, and the support sheet can be expanded to expand the support sheet between adjacent semiconductor chips, widening the distance between adjacent semiconductor chips, or the so-called kerf width, and making it easier to pick up the semiconductor chips from the support sheet.

Here, the expanding of the support sheet has been explained using the example of the workpiece being a semiconductor wafer and the workpiece being a semiconductor chip, but the application of the expanding of the support sheet is not limited to these workpieces and workpieces.

However, there is a problem in that when the support sheet is expanded after being heated to a temperature of approximately 135°C, the adhesive layer in the support sheet may crack. If the adhesive layer cracks, the edges and fragments of the adhesive layer caused by the crack will adhere to unintended areas, such as the surface of the workpiece, contaminating the workpiece. In contrast, the support sheet disclosed in Patent Document 1 is not intended to solve this problem.

The present invention aims to provide a support sheet comprising a substrate and an adhesive layer, wherein the adhesive layer is energy ray curable, and even when the support sheet is heated, cracking of the adhesive layer in the support sheet is suppressed when the support sheet is expanded, and the workpiece can be properly picked up from the support sheet.

In order to solve the above problems, the present invention employs the following configuration.
[1] A support sheet, the support sheet comprising a substrate and a pressure-sensitive adhesive layer provided on one surface of the substrate, the pressure-sensitive adhesive layer being energy ray curable, and a plurality of first test pieces of the pressure-sensitive adhesive layer having a thickness of less than 200 μm are heated at 130°C, and the plurality of first test pieces after heating are stacked to produce a second test piece having a thickness of 200±20 μm, and the second test piece is heated from -20°C to 150°C in a tensile mode under conditions of a frequency of 11 Hz, a temperature rise rate of 3°C/min, and a uniform temperature rise rate. When the storage modulus E' of the second test piece is measured, the storage modulus (E'231) when the temperature of the second test piece is 23°C is 1.5 MPa or less; and when the support sheet is attached to the mirror surface of a silicon mirror wafer by the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer after attachment is heated at 130°C, the pressure-sensitive adhesive layer after heating is energy ray-cured, and the adhesive strength (X1) between the energy ray-cured product of the pressure-sensitive adhesive layer and the silicon mirror wafer is measured, the adhesive strength (X1) is 400 mN/25 mm or less.
[2] The support sheet according to [1], wherein the pressure-sensitive adhesive layer contains an energy ray-curable compound and an energy ray-curable acrylic resin.
[3] The support sheet according to [1] or [2], wherein when the support sheet is attached to the surface of a stainless steel plate by the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer after attachment is heated at 130°C, and the adhesive strength (Y2) between the pressure-sensitive adhesive layer and the stainless steel plate after heating is measured, the adhesive strength (Y2) is 13,000 mN/25 mm or more.

[4] The support sheet according to any one of [1] to [3], wherein when the support sheet is attached to the surface of a stainless steel plate by the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer after attachment is heated at 130°C, the pressure-sensitive adhesive layer after heating is energy ray-cured, and the adhesive strength (Y1) between the energy ray-cured product of the pressure-sensitive adhesive layer and the stainless steel plate is measured, the adhesive strength (Y1) is 300 mN/25 mm or more.
[5] The support sheet according to any one of [1] to [4], wherein when the tan δ of the second test piece is measured while heating the second test piece from -20°C to 150°C under conditions of a frequency of 11 Hz, a temperature increase rate of 3°C/min, and a uniform temperature increase in tension mode, the temperature (P1) showing the peak of tan δ is 10°C or less.
[6] The support sheet according to any one of [1] to [5], wherein when the support sheet is attached to the mirror surface of a silicon mirror wafer by the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer after attachment is heated at 130°C, and the adhesive strength (X2) between the pressure-sensitive adhesive layer and the silicon mirror wafer after heating is measured, the adhesive strength (X2) is 13,000 mN/25 mm or more.

[7] A method for manufacturing a workpiece, the manufacturing method comprising: a bonding step of bonding the adhesive layer in the support sheet according to any one of [1] to [6] to a workpiece and a ring frame to fix a support sheet-attached workpiece, the workpiece including the support sheet and the support sheet provided on the workpiece, to the ring frame; a heating step of heating the adhesive layer in the support sheet fixed to the ring frame after the bonding step; and a modified layer for dividing the workpiece in the support sheet-attached workpiece after the bonding step, to produce a modified layer-formed workpiece, or a cut for dividing the workpiece in a partial region in the thickness direction of the workpiece in the support sheet-attached workpiece, to produce a semi-cut workpiece. a preparatory processing step of obtaining a preparatory processed body with a support sheet, which comprises the workpiece with the modified layer formed thereon or the semi-cut workpiece and the support sheet; a processing step of expanding the preparatory processed body with the support sheet fixed to the ring frame in a direction parallel to the surface of the support sheet after the preparatory processing step, thereby dividing the workpiece with the modified layer formed thereon at the location of the modified layer or dividing the semi-cut workpiece at the slits, thereby producing the workpiece; a curing step of curing the adhesive layer attached to the ring frame with energy rays after the heating step and the processing step; and a picking up step of separating the workpiece from the cured product of the adhesive layer and picking it up after the curing step.
[8] A method for picking up workpieces, the method comprising: a support sheet according to any one of [1] to [6]; and a workpiece group formed by arranging a plurality of workpieces produced by dividing a workpiece on a surface of the adhesive layer in the support sheet opposite to the substrate side, the adhesive layer in the support sheet being attached to a ring frame, and a bonding step of fixing the workpiece group with the support sheet to the ring frame; and a heating step of heating the workpiece group with the support sheet fixed to the ring frame after the bonding step. A method for picking up a workpiece, comprising: a heating step; an expanding step, after the attaching step, of expanding the group of workpieces with the support sheet attached to the ring frame in a direction parallel to the surface of the support sheet, thereby increasing the distance between adjacent workpieces in the group of workpieces; a curing step, after the heating step and the expanding step, of curing the adhesive layer attached to the ring frame with energy rays; and a picking up step, after the curing step, of separating the workpieces from the cured adhesive layer and picking them up.

The present invention provides a support sheet comprising a substrate and an adhesive layer, the adhesive layer being energy ray curable. Even when the support sheet is heated, cracking of the adhesive layer in the support sheet is suppressed when the support sheet is expanded, and the support sheet allows for normal pickup of a workpiece from the support sheet.

FIG. 1 is a cross-sectional view schematically illustrating an example of a support sheet according to an embodiment of the present invention. 1A to 1C are cross-sectional views for schematically explaining an example of a method for manufacturing a workpiece according to an embodiment of the present invention. 10A to 10C are cross-sectional views for schematically explaining another example of a method for manufacturing a workpiece according to an embodiment of the present invention. 1 is a cross-sectional view for schematically explaining an example of a method for picking up a workpiece according to an embodiment of the present invention.

Support Sheet A support sheet according to one embodiment of the present invention comprises a substrate and a pressure-sensitive adhesive layer provided on one surface of the substrate, the pressure-sensitive adhesive layer being energy ray curable, and a plurality of first test pieces of the pressure-sensitive adhesive layer having a thickness of less than 200 μm are heated at 130°C, and the heated plurality of first test pieces are stacked to produce a second test piece having a thickness of 200±20 μm, and the storage modulus E' of the second test piece is measured while the second test piece is heated from -20°C to 150°C in a tensile mode under conditions of a frequency of 11 Hz, a temperature rise rate of 3°C/min, and a uniform temperature rise rate. When measured, the storage modulus (E'231) when the temperature of the second test piece is 23°C is 1.5 MPa or less, and when the support sheet is attached to the mirror surface of a silicon mirror wafer by the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer after attachment is heated at 130°C, the pressure-sensitive adhesive layer after heating is energy ray-cured, and the adhesive strength (X1) (sometimes simply referred to in this specification as "adhesive strength (X1)") between the energy ray-cured product of the pressure-sensitive adhesive layer and the silicon mirror wafer is measured, the adhesive strength (X1) is 400 mN/25 mm or less.

The support sheet of this embodiment can be used, for example, in the manufacture of workpieces, as will be described later.
The support sheet of this embodiment can be laminated with a protective film-forming film, for example, as described below, to form a composite sheet for forming a protective film.

In the support sheet of this embodiment, the storage modulus (E'231) is 1.5 MPa or less, which prevents cracking of the adhesive layer in the support sheet when the support sheet is expanded, even after heating at high temperatures. This prevention of cracking of the adhesive layer also prevents adhesion of edges or fragments of the adhesive layer caused by cracks to unintended areas, such as the surface of the workpiece, thereby preventing contamination of the workpiece. Examples of heating in this case include heating to remove foreign matter, such as low-molecular-weight resin components, adhering to the surface of the workpiece. Examples of heating in this case include heating to dry the workpiece after washing with water to remove fine foreign matter that is generated during processing and adheres to the surface of the workpiece. The upper limit of the heating temperature during these heating processes is approximately 135°C.

In the support sheet of this embodiment, because the adhesive strength (X1) is 400 mN/25 mm or less, even after the support sheet with a workpiece or workpiece product attached thereto is heated at a high temperature, the workpiece product can be created from the workpiece on the support sheet, the adhesive layer in the support sheet is cured to form a cured support sheet, and the workpiece product can be successfully picked up from the cured support sheet, resulting in high pick-up properties. The heating used in this case can be the same as that described above.

In this specification, a support sheet after the adhesive layer has cured may be referred to as a "cured support sheet" to distinguish it from a support sheet in which the adhesive layer has not cured.

In this specification, "room temperature" means a temperature that is neither particularly cold nor hot, i.e., a normal temperature, such as a temperature between 18 and 28°C.

In this embodiment, examples of the workpiece include a wafer, a semiconductor device panel, etc.

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

The semiconductor device panel is handled during the semiconductor device manufacturing process, and a specific example is a configuration in which multiple semiconductor devices are arranged in a plane within a circular, rectangular, or other shaped area, using semiconductor devices in which one or more electronic components are encapsulated in a sealing resin.

In this embodiment, the workpiece is obtained by processing the workpiece. For example, if the workpiece is a wafer, the workpiece may be a chip, and if the workpiece is a semiconductor wafer, the workpiece may be a semiconductor chip.

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

Figure 1 is a cross-sectional view showing a schematic example of a support sheet according to one embodiment of the present invention. Note that the figures used in the following explanation may show enlarged essential parts for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional proportions of each component may not necessarily be the same as in reality.

The support sheet 1 shown here is configured to include a substrate 11 and an adhesive layer 12 provided on one surface 11a of the substrate 11. The support sheet 1 further includes a release film 13 provided on a surface 12a of the adhesive layer 12 opposite the substrate 11 side.
One surface 11a of the substrate 11 may be, for example, a matte surface, or may not be a matte surface (for example, a glossy surface with a small degree of unevenness).
The pressure-sensitive adhesive layer 12 is energy ray curable.
The second test piece is prepared using a plurality of pressure-sensitive adhesive layers 12 each having a thickness of less than 200 μm, and the storage modulus (E′231) measured is 1.5 MPa or less.
The adhesive strength (X1) measured using the support sheet 1 is 400 mN/25 mm or less.

In this specification, "matte surface" means a surface that has a relatively large degree of unevenness, is rough, has a relatively low gloss, and appears to have been matte-finished.

The support sheet of this embodiment is not limited to that shown in FIG. 1, and some of the configuration may be changed, deleted, or added to that shown in FIG. 1 as long as the effects of the present invention are not impaired.
For example, the support sheet 1 shown in FIG. 1 is provided with a release film 13, but in the support sheet of this embodiment, the release film is an optional configuration, and the support sheet of this embodiment does not necessarily have to be provided with a release film.
For example, the support sheet 1 shown in Figure 1 includes a substrate 11, a pressure-sensitive adhesive layer 12, and a release film 13, but the support sheet of this embodiment may also include other layers that do not fall under any of the following categories: substrate, pressure-sensitive adhesive layer, and release film. The other layers can be selected arbitrarily depending on the purpose and are not particularly limited. However, in the support sheet of this embodiment, it is preferable that the substrate and the pressure-sensitive adhesive layer are provided in direct contact with each other, and the pressure-sensitive adhesive layer and the release film are provided in direct contact with each other.

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

<<Adhesive Layer, Adhesive Composition (I)>>
The pressure-sensitive adhesive layer is in the form of a sheet or film, and is energy ray-curable. The physical properties of the pressure-sensitive adhesive layer before and after curing can be adjusted.

The adhesive layer may consist of one layer (single layer), or two or more layers. If it consists of multiple layers, these layers may be the same or different, and there are no particular restrictions on the combination of these layers.

In this specification, not just in the case of pressure-sensitive adhesive layers, "multiple layers may be the same or different" 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" means "at least one of the constituent materials and thicknesses of each layer is different from each other."

The thickness of the adhesive layer is not particularly limited, but is preferably 1 to 100 μm, more preferably 3 to 60 μm, even more preferably 5 to 30 μm, and particularly preferably 8 to 25 μm. When the thickness of the adhesive layer is within this range, when the adhesive layer is provided on the matte surface of the substrate, the adhesive layer can better embed the matte surface of the substrate, thereby improving the above-mentioned pick-up ability of the workpiece from the cured support sheet.
Here, "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.

In this specification, "thickness," not limited to the case of adhesive layers, refers to the average thickness measured at five randomly selected points on the object, unless otherwise specified, and can be obtained using a constant pressure thickness gauge in accordance with JIS K7130.

The adhesive layer can be formed using an adhesive composition containing the components that make up the adhesive layer. 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 in 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 same components in the adhesive layer.

In the pressure-sensitive adhesive layer, the proportion of the total content of one or more components described below contained in the pressure-sensitive adhesive layer relative to the total mass of the pressure-sensitive adhesive layer does not exceed 100 mass %.
Similarly, in the PSA composition, the proportion of the total content of one or more components described below in the PSA composition relative to the total mass of the PSA composition does not exceed 100 mass %.

The adhesive composition may be applied by a known method, such as using various coaters such as an air knife coater, blade coater, bar coater, gravure coater, roll coater, roll knife coater, curtain coater, die coater, knife coater, screen coater, Mayer bar coater, or kiss coater.

The drying conditions for the pressure-sensitive adhesive composition are not particularly limited. However, if the pressure-sensitive adhesive composition contains a solvent, as described below, it is preferable to heat-dry it. Furthermore, pressure-sensitive adhesive compositions containing a solvent are preferably heat-dried, for example, at 70 to 130°C for 10 seconds to 5 minutes.

When providing a pressure-sensitive adhesive layer on a substrate, for example, the pressure-sensitive adhesive composition may be coated on the substrate and dried as necessary. Alternatively, for example, the pressure-sensitive adhesive composition may be coated on a release film and dried as necessary to form a pressure-sensitive adhesive layer on the release film, and the exposed surface of this pressure-sensitive adhesive layer may be attached to one surface (e.g., a matte or glossy surface) of the substrate, thereby laminating the pressure-sensitive adhesive layer on the substrate. In this case, the release film may be removed at any time during the manufacturing process or use of the support sheet.

The pressure-sensitive adhesive layer preferably contains an energy ray-curable compound (α). By using a pressure-sensitive adhesive layer containing the energy ray-curable compound (α), it becomes easy to adjust both the storage modulus (E'231) and the adhesive strength (X1).
That is, a preferred pressure-sensitive adhesive composition is, for example, a pressure-sensitive adhesive composition (I) containing an energy ray-curable compound (α).

<Energy ray-curable compound (α)>
The energy ray-curable compound (α) is not particularly limited as long as it has energy ray-curability.
The viscosity of the energy ray-curable compound (α) at 23° C. is preferably 350 mPa s or less, and may be, for example, any one of 320 mPa s or less, 220 mPa s or less, 120 mPa s or less, and 60 mPa s or less. The lower the viscosity, the higher the embeddability of the pressure-sensitive adhesive layer on the matte surface of the substrate.
There is no particular limitation on the lower limit of the viscosity of the energy ray-curable compound (α) at 23° C. For example, an energy ray-curable compound (α) having a viscosity of 5 mPa·s or more is more easily available.
The viscosity of the energy ray-curable compound (α) at 23°C may be, for example, any one of 5 to 350 mPa·s, 5 to 320 mPa·s, 5 to 220 mPa·s, 5 to 120 mPa·s, and 5 to 60 mPa·s or less, although these are just examples of the viscosity.

The viscosity of the energy ray-curable compound (α) at 23°C can be measured, for example, using a single-cylinder B-type (Brookfield type) rotational viscometer.

Examples of the energy ray-curable compound (α) include a monomer or oligomer having an energy ray-polymerizable unsaturated group and capable of being cured by irradiation with energy rays.
One molecule of the energy ray-curable compound (α) has one or two or more, and may have three or more, energy ray-polymerizable unsaturated groups, but preferably has one or two.
An example of the energy ray polymerizable unsaturated group is a (meth)acryloyl group.

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

The energy ray-curable compound (α) is preferably a (meth)acrylic acid ester which may have a substituent. Examples of the substituted (meth)acrylic acid ester include compounds having a structure in which one or more carbon atoms in a hydrocarbon group derived from an alcohol (a hydrocarbon group bonded to an oxygen atom that does not constitute a carbonyl group in an oxycarbonyl group (—O—C(═O)—)) in the (meth)acrylic acid ester are substituted with a substituent together with the hydrogen atom bonded to this carbon atom (for example, in the unit —CH ₂ — or ═CH—). However, two adjacent carbon atoms are not substituted with a substituent.

The hydrocarbon group in the (meth)acrylic acid ester that is the energy ray-curable compound (α) may be linear, branched, or cyclic, and if cyclic, may be monocyclic or polycyclic. The hydrocarbon group may have both a chain structure (either a linear structure or a branched structure, or both) and a cyclic structure.

The hydrocarbon group may be either an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and the aliphatic hydrocarbon group may be either a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. In this specification, a hydrocarbon group that has only an aliphatic group and no aromatic cyclic group is an aliphatic hydrocarbon group, and a hydrocarbon group that has both an aliphatic group and an aromatic cyclic group or has only an aromatic cyclic group is an aromatic hydrocarbon group.

The hydrocarbon group preferably has a cyclic structure, i.e., is a cyclic hydrocarbon group, or is a hydrocarbon group having both a chain structure and a cyclic structure.

The hydrocarbon group is preferably an alkyl group, an alkylene group, or an aralkyl group (arylalkyl group).

The substituent may be an atomic group having a structure in which a plurality of atoms are bonded, or may be a single atom.
A preferred example of the substituent is an oxygen atom (—O—).

When the hydrocarbon group has the above-mentioned substituents, the number of substituents is adjusted appropriately depending on the type of hydrocarbon group, but typically, 1 to 4 substituents are preferred, and 1 to 3 substituents are more preferred.

The number of carbon atoms in the hydrocarbon group is preferably 3 to 20, and may be, for example, any one of 3 to 16, 3 to 12, and 3 to 8, any one of 4 to 20, 9 to 20, and 13 to 20, or any one of 4 to 16 and 9 to 14. However, these are just examples of the number of carbon atoms. Here, when the hydrocarbon group has the substituent, the "number of carbon atoms in the hydrocarbon group" means the number of carbon atoms in the hydrocarbon group before being substituted with the substituent.
For example, when a hydrocarbon group has only an oxygen atom (—O—) as a substituent, the number of carbon atoms in the hydrocarbon group means the number of carbon atoms in the hydrocarbon group when this oxygen atom is replaced with the original group, such as a methylene group (—CH ₂ —).

The hydrocarbon group is preferably a hydrocarbon group having a cyclic structure and optionally having an oxygen atom as a substituent; more preferably a hydrocarbon group having both a chain structure and a cyclic structure and optionally having an oxygen atom as a substituent; and even more preferably an aliphatic hydrocarbon group or aromatic hydrocarbon group which optionally have an oxygen atom as a substituent. It is more preferably an aromatic hydrocarbon group having both an aliphatic group having an oxygen atom as a substituent and an unsubstituted aromatic cyclic group (herein, the energy ray-curable compound (α) may be referred to as the "energy ray-curable compound (α1)"), an aliphatic hydrocarbon group having both an unsubstituted cyclic structure and an unsubstituted chain structure (herein, the energy ray-curable compound (α) may be referred to as the "energy ray-curable compound (α2)"), or an aliphatic hydrocarbon group having both a cyclic structure having an oxygen atom as a substituent and an unsubstituted chain structure (herein, the energy ray-curable compound (α) may be referred to as the "energy ray-curable compound (α3)"). By using such an energy ray-curable compound (α), when a pressure-sensitive adhesive layer is provided on the matte surface of the substrate, the pressure-sensitive adhesive layer can be more easily embedded into the matte surface of the substrate.

An example of the energy ray-curable compound (α1) is the energy ray-curable compound (α)-1 described later in the Examples.
An example of the energy ray-curable compound (α2) is the energy ray-curable compound (α)-2 described later in the Examples.
An example of the energy ray-curable compound (α3) is the energy ray-curable compound (α)-3 described later in the Examples.

The molecular weight of the energy ray-curable compound (α) is not particularly limited, but is preferably 500 or less. Use of such an energy ray-curable compound (α) improves the properties of the pressure-sensitive adhesive layer. For example, when a pressure-sensitive adhesive layer is provided on the matte surface of a substrate, the matte surface of the substrate is more easily embedded by the pressure-sensitive adhesive layer.

The molecular weight of the energy ray-curable compound (α) is preferably 100 to 500, more preferably 200 to 400, and may be, for example, any one of 200 to 310 and 200 to 280, or any one of 250 to 400 and 310 to 400, or may be 250 to 310. When the molecular weight is equal to or less than the upper limit, the properties of the pressure-sensitive adhesive layer (e.g., the embedding ability of the pressure-sensitive adhesive layer on the matte surface of the substrate) become better. When the molecular weight is equal to or more than the lower limit, the structure of the pressure-sensitive adhesive layer becomes more stable. However, these are examples of the molecular weight of the energy ray-curable compound (α).
Among the energy ray-curable compounds (α1), (α2), and (α3), those having any of the molecular weights shown here are particularly preferred energy ray-curable compounds (α).

The energy ray-curable compound (α) is preferably a (meth)acrylic acid ester which may have a structure in which one or more carbon atoms in a hydrocarbon group derived from an alcohol in the (meth)acrylic acid ester are substituted with a substituent together with the hydrogen atoms bonded to these carbon atoms, and the hydrocarbon group has a cyclic structure and has a molecular weight of 500 or less.
Such an energy ray-curable compound (α) is preferably one in which the hydrocarbon group is an alkyl group, an alkylene group, or an aralkyl group, and preferably one in which the substituent is an oxygen atom, and is preferably the energy ray-curable compound (α1), the energy ray-curable compound (α2), or the energy ray-curable compound (α3), and is preferably one having a molecular weight within any of the further limited numerical ranges described above, and more preferably one which simultaneously satisfies one or more of these four conditions.

The energy ray-curable compound (α) contained in the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) 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 pressure-sensitive adhesive composition (I), the content of the energy ray-curable compound (α) relative to the total content of all components other than the solvent is preferably 5% by mass or more, and may be 10% by mass or more, or 14% by mass or more, while the content is 100% by mass or less.
This content is synonymous with the fact that the content ratio of the energy ray-curable compound (α) in the pressure-sensitive adhesive layer relative to the total mass of the pressure-sensitive adhesive layer is preferably 5 mass% or more, and may be either 10 mass% or more or 14 mass% or more, and that the ratio is 100 mass% or less.
This is based on the fact that in the process of removing the solvent from a solvent-containing resin composition to form a resin film, the amount of components other than the solvent usually does not change, and the content ratio of the components other than the solvent between the resin composition and the resin film is the same. Therefore, in this specification, not only in the case of the pressure-sensitive adhesive layer, but also in the case of the resin film obtained by removing the solvent from the resin composition, the content of the components other than the solvent will be described only in the resin film.

<Energy ray-curable acrylic resin (Ia)>
It is more preferable that the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) further contain an energy ray-curable acrylic resin (also referred to in this specification as "energy ray-curable acrylic resin (Ia)"), that is, contain both an energy ray-curable compound and an energy ray-curable acrylic resin. By using a pressure-sensitive adhesive layer containing the energy ray-curable compound (α) and the energy ray-curable acrylic resin (Ia), it becomes easier to adjust both the storage modulus (E'231) and the adhesive strength (X1).

Examples of the energy ray-curable acrylic resin (Ia) include resins having a structure in which an unsaturated group is introduced into the side chain of a non-energy ray-curable acrylic resin.

[Non-energy ray curable acrylic resin]
Examples of the non-energy ray curable acrylic resin include acrylic polymers having structural units derived from alkyl (meth)acrylate esters and structural units derived from functional group-containing monomers.

Examples of the (meth)acrylic acid alkyl ester include those in which the alkyl group constituting the alkyl ester has 1 to 20 carbon atoms. The alkyl group constituting the alkyl ester may be linear, branched, or cyclic, but is preferably linear or branched.

Among the (meth)acrylic acid alkyl esters, examples in which the alkyl group is linear or branched 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, and n-octyl (meth)acrylate. Examples of suitable acrylates include acrylate, n-nonyl (meth)acrylate, isononyl (meth)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, octadecyl (meth)acrylate (stearyl (meth)acrylate), nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

Among the (meth)acrylic acid alkyl esters, examples in which the alkyl group is cyclic include isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate.

Of the above, from the viewpoint of further reducing the adhesive strength (X1), the (meth)acrylic acid alkyl ester is preferably 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, dodecyl acrylate (lauryl acrylate), or dodecyl methacrylate (lauryl methacrylate).

Examples of the functional group-containing monomer include those in which the functional group reacts with the crosslinking agent described below to become the initiation point for crosslinking, or those in which the functional group reacts with a group in the unsaturated group-containing compound described below that can bond (react) with the non-energy ray-curable acrylic resin, thereby enabling the introduction of an unsaturated group into the side chain of the acrylic polymer.

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.

Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and non-(meth)acrylic unsaturated alcohols (unsaturated alcohols not having a (meth)acryloyl skeleton) such as vinyl alcohol and allyl alcohol.
Among these, the hydroxyl group-containing monomer is preferably a hydroxyalkyl methacrylate, more preferably 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, or 2-hydroxybutyl methacrylate, from the viewpoint of further reducing the adhesive strength (X1).

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

Examples of the epoxy group-containing monomer include glycidyl group-containing (meth)acrylic acid esters such as glycidyl (meth)acrylate.

The functional group-containing monomer is preferably a hydroxyl group-containing monomer.

The non-energy ray-curable acrylic resin may contain structural units derived from other monomers that do not fall into either the structural units derived from (meth)acrylic acid alkyl esters or the structural units derived from the functional group-containing monomers.

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.

The non-energy ray-curable acrylic resin may contain only one type of structural unit derived from an alkyl (meth)acrylate ester, two or more types of structural units derived from the functional group-containing monomer, and two or more types of structural units derived from the other monomer. If there are two or more types, the combination and ratio of these may be selected arbitrarily.

In the non-energy ray-curable acrylic resin, the content of structural units derived from (meth)acrylic acid alkyl ester is preferably 65 to 99 mass% of the total amount of structural units.

In non-energy ray-curable acrylic resins, the content of structural units derived from functional group-containing monomers is preferably 1 to 35% by mass based on the total amount of structural units.

In the non-energy ray-curable acrylic resin, the content of the structural units derived from the other monomers is preferably 0 to 10% by mass relative to the total amount of structural units.

The energy ray-curable acrylic resin (Ia) can be obtained, for example, by reacting the functional group in the non-energy ray-curable acrylic resin with an unsaturated group-containing compound having an energy ray-polymerizable unsaturated group.

The unsaturated group-containing compound is a compound that has, in addition to the energy ray-polymerizable unsaturated group, a group that can bond to the non-energy ray-curable acrylic resin by reacting with a functional group in the non-energy ray-curable acrylic resin.
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), with a (meth)acryloyl group being preferred.
Examples of groups capable of bonding to the functional groups in the non-energy ray-curable acrylic resin include isocyanate groups and glycidyl groups capable of bonding to hydroxyl groups or amino groups, and hydroxyl groups and amino groups capable of bonding to carboxyl groups or epoxy groups.

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

When the energy ray-curable acrylic resin (Ia) is obtained by reacting the functional groups in the non-energy ray-curable acrylic resin with an unsaturated group-containing compound having an energy ray-polymerizable unsaturated group, the total number of moles of the unsaturated groups in the unsaturated group-containing compound relative to the total number of moles of the functional groups in the non-energy ray-curable acrylic resin may be 0.6 times or more or 0.75 times or more, preferably 0.8 times or more, more preferably 0.85 times or more, and even more preferably 0.9 times or more. The greater the total number of moles of the unsaturated groups, the smaller the adhesive strength (X1) and the higher the pick-up ability of the workpiece from the cured support sheet.
On the other hand, the total number of moles of the unsaturated groups in the unsaturated group-containing compound is preferably 1 or less times the total number of moles of the functional groups in the non-energy ray-curable acrylic resin.

The energy ray-curable acrylic resin (Ia) contained in the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) 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.

When the adhesive layer and adhesive composition (I) contain an energy ray-curable acrylic resin (Ia), the content of the energy ray-curable compound (α) in the adhesive layer relative to the total mass of the adhesive layer is preferably 5 to 50 mass%, and may be, for example, 5 to 35 mass%, 5 to 25 mass%, 10 to 50 mass%, 14 to 50 mass%, or 10 to 35 mass%. When this proportion is at or above the lower limit, the properties of the adhesive layer (e.g., the ability of the adhesive layer to embed the matte surface of the substrate) are improved. When this proportion is at or below the upper limit, the pickup properties, which allow the above-mentioned workpiece to be picked up from the support sheet without any problems, are improved.

When the adhesive layer and adhesive composition (I) contain an energy ray-curable acrylic resin (Ia), the content of the energy ray-curable acrylic resin (Ia) in the adhesive layer relative to the total mass of the adhesive layer is preferably 50 to 95% by mass, and may be, for example, 65 to 95% by mass, 75 to 95% by mass, 50 to 90% by mass, 50 to 86% by mass, or 65 to 90% by mass. When this proportion is equal to or greater than the lower limit, the pickup properties, which allow the workpiece to be picked up from the support sheet without any problems, are improved. When this proportion is equal to or less than the upper limit, the properties of the adhesive layer (e.g., the ability of the adhesive layer to embed the matte surface of the substrate) are improved.

<Other ingredients>
The pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) may contain other components that do not fall into either the energy ray-curable compound (α) or the energy ray-curable acrylic resin (Ia), as long as the effects of the present invention are not impaired.
Examples of the other components include a crosslinking agent (β), a photopolymerization initiator (γ), and additives.

The other components contained in the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) may be one type only, or two or more types. When there are two or more types, the combination and ratio of these can be selected arbitrarily.

[Crosslinking agent (β)]
When preparing the energy ray-curable acrylic resin (Ia), if any functional group in the non-energy ray-curable acrylic resin remains unreacted with the unsaturated group-containing compound, the energy ray-curable acrylic resin (Ia) will have this functional group. When such an energy ray-curable acrylic resin (Ia) is used, the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) may further contain a crosslinking agent (β). In the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) containing the crosslinking agent (β), the energy ray-curable acrylic resins (Ia) can be crosslinked to each other.

Examples of the crosslinking agent (β) 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).
Among these, the crosslinking agent (β) is preferably an adduct of hexamethylene diisocyanate or an isocyanurate-modified product of hexamethylene diisocyanate, from the viewpoint of making it easier to set the adhesive strength (X1) within the range described below.

The crosslinking agent (β) contained in the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) 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.

In order to make it easier to achieve both the storage modulus (E'231) and adhesive strength (X1) within the ranges described below, the content of the crosslinking agent (β) in the adhesive layer is preferably 0.1 to 7 parts by mass per 100 parts by mass of the energy ray-curable acrylic resin (Ia). For example, it may be any of 0.1 to 5 parts by mass, 0.1 to 3 parts by mass, 0.5 to 7 parts by mass, 1 to 7 parts by mass, and 3 to 7 parts by mass, or 0.5 to 5 parts by mass, and 1 to 3 parts by mass.

[Photopolymerization initiator (γ)]
The pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) may further contain a photopolymerization initiator (γ). The pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) containing the photopolymerization initiator (γ) undergo a sufficient curing reaction even when irradiated with relatively low-energy energy rays such as ultraviolet rays.

Examples of the photopolymerization initiator (γ) 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-phenyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylethan-1-one, and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one; bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2,4,6-trimethylbenzoyl acylphosphine oxide compounds such as phenyl diphenylphosphine 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.
As the photopolymerization initiator (γ), for example, a photosensitizer such as an amine can also be used.
Among these, the photopolymerization initiator (γ) is preferably 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one, from the viewpoint of making it easier to set the adhesive strength (X1) within the range described below.

The photopolymerization initiator (γ) contained in the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition (I) 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.

In the pressure-sensitive adhesive layer, the content of the photopolymerization initiator (γ) is preferably 0.5 to 5 parts by mass per 100 parts by mass of the total content of the energy ray-curable compound (α) and the energy ray-curable acrylic resin (Ia), regardless of whether the pressure-sensitive adhesive layer contains the energy ray-curable acrylic resin (Ia), and may be, for example, 1 to 4 parts by mass or 1.5 to 3.5 parts by mass.

[Additives]
Examples of the 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 an unintended crosslinking reaction in the PSA composition (I) during storage due to the action of a catalyst mixed in the PSA composition (I). Examples of the reaction retarder include those that form a chelate complex by chelating with the catalyst, and more specifically, components having two or more carbonyl groups (—C(═O)—) in one molecule.

The adhesive layer and adhesive composition (I) may contain only one type of additive, or two or more types. If two or more types are contained, the combination and ratio of these additives can be selected arbitrarily.

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

[solvent]
The PSA composition (I) may contain a solvent. When the PSA composition (I) contains a solvent, the suitability for application to a surface to be coated is improved.

The solvent is preferably an organic solvent, and examples of such organic solvents include ketones such as methyl ethyl ketone and acetone; esters (carboxylic acid esters) 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 pressure-sensitive adhesive composition (I) may contain only one type of solvent, or two or more types. If two or more types are contained, the combination and ratio of these solvents can be selected arbitrarily.

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

<One embodiment of pressure-sensitive adhesive layer>
An example of a preferred pressure-sensitive adhesive layer and pressure-sensitive adhesive composition (I) is one containing an energy ray-curable compound (α), an energy ray-curable acrylic resin (Ia), a crosslinking agent (β), and a photopolymerization initiator (γ).

<Method for producing pressure-sensitive adhesive composition (I)>
The pressure-sensitive adhesive composition (I) can be obtained by blending the energy ray-curable compound (α) and, if necessary, the energy ray-curable acrylic resin (Ia) and other components for constituting the pressure-sensitive adhesive composition (I).
The order of addition of the components when blending is not particularly limited, and two or more components may be added simultaneously.
The method for mixing the components during blending is not particularly limited, and may be appropriately selected from known methods such as a method of mixing by rotating a stirrer or stirring blades, a method of mixing using a mixer, or a method of mixing by applying ultrasound.
The temperature and time for adding and mixing each component are not particularly limited as long as the components do not deteriorate, and may be adjusted appropriately. A temperature of 15 to 30°C is preferred.

<<Base material>>
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; and vinyl chloride-based resins (copolymers obtained using vinyl chloride as a monomer) such as polyvinyl chloride and vinyl chloride copolymer. Examples of the polyester include polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalenedicarboxylate, and wholly aromatic polyesters in which all structural units have aromatic cyclic groups; copolymers of two or more of the above polyesters; poly(meth)acrylic acid esters; polyurethanes; polyurethane acrylates; polyimides; polyamides; polycarbonates; fluororesins; polyacetals; modified polyphenylene oxides; polyphenylene sulfides; polysulfones; and polyether ketones.
Further, examples of the resin include polymer alloys such as mixtures of the polyester and other resins. The polymer alloys of the polyester and other resins preferably contain a relatively small amount of resin other than polyester.
Examples of the resin include crosslinked resins in which one or more of the resins exemplified above are crosslinked; and modified resins such as ionomers using one or more of the resins exemplified above.

Among the above, polypropylene or polybutylene terephthalate is preferred as the resin that constitutes the substrate, as this increases the substrate's heat resistance at high temperatures (approximately 135°C) and flexibility.

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

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).

In the support sheet, since the adhesive layer is energy ray curable, the substrate is preferably one that allows energy rays to pass through, and is preferably transparent.

The substrate preferably has at least one matte surface, and both surfaces may be matte, or one surface may be matte and the other surface may be glossy with a small degree of unevenness.
In the support sheet, a pressure-sensitive adhesive layer may be provided on the matte surface of the substrate. When both surfaces of the substrate are matte surfaces, the pressure-sensitive adhesive layer may be provided on the matte surface having the greater surface roughness (Ra).

The matte surface of a substrate is a surface that has a roughness above a certain value and has a low gloss, making it clearly identifiable by its appearance. Substrates with at least one matte surface are commercially available, and can also be produced using known methods.

The surface roughness (Ra) of the matte surface of the substrate is preferably 0.05 μm or more, and may be, for example, 0.1 μm or more, 0.4 μm or more, or 0.7 μm or more. When the surface roughness is equal to or greater than the lower limit, when the composition of the adhesive layer is adjusted and an adhesive layer is provided on the matte surface of the substrate, the effect of high embedding ability of the adhesive layer on the matte surface of the substrate can be more significantly obtained. In addition, blocking of the substrate when the substrates are stored in a stacked state is more suppressed.
The upper limit of the surface roughness (Ra) of the matte surface of the substrate is not particularly limited. For example, the surface roughness is preferably 2 μm or less in order to prevent the surface from becoming excessively uneven.
The surface roughness (Ra) of the matte surface of the substrate may be, for example, any one of 0.05 to 2 μm, 0.1 to 2 μm, 0.4 to 2 μm, and 0.7 to 2 μm, although these are just examples of the surface roughness.

In this specification, "surface roughness (Ra)" is not limited to the matte surface of the substrate, but refers to the so-called arithmetic mean roughness determined in accordance with JIS B0601:2001.

The surface roughness (Ra) of the glossy surface of the substrate is preferably less than 0.05 μm, and may be, for example, 0.04 μm or less. When the surface roughness is in this range, the average light transmittance of the support sheet described below in the wavelength range of 400 to 800 nm becomes higher.
The lower limit of the surface roughness (Ra) of the glossy surface of the substrate is not particularly limited. For example, the surface roughness is preferably 0.01 μm or more in order to prevent blocking of the substrates when the substrates are stacked and stored.
The surface roughness (Ra) of the glossy surface of the substrate may be, for example, 0.01 μm or more and less than 0.05 μm, or 0.01 to 0.04 μm, although these are just examples of the surface roughness.

The surface roughness (Ra) of both sides of the substrate can be adjusted, for example, by changing the molding conditions of the substrate and the surface treatment conditions. Examples of surface treatment include roughening treatments such as sandblasting and solvent treatment, and smoothing treatments such as polishing.

The surface of the substrate may be subjected to oxidation treatments such as corona discharge treatment, electron beam irradiation treatment, plasma treatment, ozone/ultraviolet irradiation treatment, flame treatment, chromic acid treatment, and hot air treatment; lipophilic treatment; hydrophilic treatment; etc., in order to adjust the adhesion to the pressure-sensitive adhesive layer formed thereon. The surface of the substrate may also be treated with a primer.

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

The thickness of the substrate is preferably 50 to 300 μm, more preferably 60 to 100 μm. By having the thickness of the substrate in this range, the heat resistance (for example, about 135° C.), flexibility, and suitability for attachment to a workpiece of the support sheet are further improved.
Here, the "thickness of the substrate" means the thickness of the entire substrate, and for example, the thickness of a substrate consisting of multiple layers means the total thickness of all layers that make up the substrate.

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.

<<Release film>>
The release film may be a known one.
More specifically, the release film may be, for example, a release film substrate having one or both surfaces treated with a release agent. The release film substrate is preferably made of a polyethylene terephthalate film.
The release-treated surface can be formed by subjecting the surface of the substrate for the release film to a release treatment with a known release treating agent.
The thickness of the release film may be, for example, 2 to 300 μm, and preferably 20 to 100 μm.

Next, we will explain the physical properties of the support sheet (adhesive layer).

<Storage modulus (E'231)>
The storage modulus (E'231) is 1.5 MPa or less, preferably 1.2 MPa or less, and may be, for example, 0.9 MPa or less, 0.7 MPa or less, or 0.5 MPa or less. When the storage modulus (E'231) is the upper limit or less, the effect of suppressing cracking of the pressure-sensitive adhesive layer in the support sheet is increased when the support sheet is expanded, even after the support sheet is heated at a high temperature.
The lower limit of the storage modulus (E'231) is not particularly limited. For example, a pressure-sensitive adhesive layer having a storage modulus (E'231) of 0.2 MPa or more can be more easily formed.
The storage modulus (E'231) may be, for example, any one of 0.2 to 1.5 MPa, 0.2 to 1.2 MPa, 0.2 to 0.9 MPa, 0.2 to 0.7 MPa, and 0.2 to 0.5 MPa.

The storage modulus (E'231) can be measured, for example, by the following method.
That is, first, a plurality of pressure-sensitive adhesive layers each having a thickness of less than 200 μm are prepared, and these are used as first test pieces. Examples of the first test pieces include slices cut to a desired size from the pressure-sensitive adhesive layer to be measured.
Next, these first test pieces (adhesive layers) were heated at 130°C for 2 hours. These heated first test pieces were then laminated together in their thickness direction to produce a laminate with a thickness of 200±20 μm (i.e., 180 to 220 μm). Furthermore, a 4 mm wide piece was cut out from the laminate, which served as the second test piece.
Next, the second test piece is held at two locations spaced 20 mm apart, and in this state, the storage modulus E' of the second test piece is measured under the condition of a frequency of 11 Hz while the temperature of the second test piece is raised uniformly from -20°C to 150°C at a temperature rise rate of 3°C/min. Then, the storage modulus E' of the second test piece when the temperature is 23°C is adopted as the storage modulus (E'231).
The fact that the second test piece is held at two points with an interval of 20 mm means that the length of the portion of the second test piece to be measured for storage modulus E' is 20 mm.

The second test piece can be held at the two locations using, for example, a known holding means such as a gripping tool.

The number of first test pieces after heating that constitute the second test piece is not particularly limited as long as it is two or more pieces, and can be selected arbitrarily depending on the thickness of each first test piece (adhesive layer).
For example, five heated first test pieces each having a thickness of 40 μm can be used to prepare the second test piece having a thickness of 200 μm. Also, fourteen heated first test pieces each having a thickness of 15 μm can be used to prepare the second test piece having a thickness of 210 μm. However, these are merely examples, and the number and thickness of the first test pieces used are not limited to these.

<Tan δ Peak Temperature (P1)>
A plurality of first test pieces of the pressure-sensitive adhesive layer, each having a thickness of less than 200 μm, were heated at 130° C., and the heated plurality of first test pieces were laminated to prepare a second test piece having a thickness of 200 μm±20 μm. The storage modulus E′ and loss modulus E″ of the second test piece were measured while the second test piece was heated from −20° C. to 150° C. in a tensile mode under conditions of a frequency of 11 Hz, a temperature rise rate of 3° C./min, and a uniform temperature rise. When the loss tangent was calculated from these measured values, the temperature showing the peak of the loss tangent (sometimes referred to herein as the “peak temperature (P1)”) may be, for example, 12° C. or lower, but is preferably 10° C. or lower. By using such a support sheet, the effect of suppressing cracking of the pressure-sensitive adhesive layer in the support sheet is further enhanced when the support sheet is expanded, even after the support sheet has been heated at a high temperature.
In this specification, not only in the case of the second test piece, but also in any other case, the "loss tangent" is usually also referred to as the "loss factor" or "tan δ", and is the ratio between the storage modulus and the loss modulus (loss modulus/storage modulus), and in this specification, may be referred to as "tan δ".
The first test piece can be heated, for example, at 130° C. for 2 hours, and the width of the second test piece can be, for example, 4 mm.
When measuring the storage modulus E' and loss modulus E'' of the second test piece, the second test piece can be held at two points spaced apart by a distance of 20 mm, for example.

The tan δ peak temperature (P1) is more preferably 6° C. or lower, and may be, for example, either 2° C. or lower or −2° C. or lower. The lower the tan δ peak temperature (P1), the higher the effect of suppressing cracking of the pressure-sensitive adhesive layer in the support sheet.
The lower limit of the peak temperature (P1) of tan δ is not particularly limited. For example, a pressure-sensitive adhesive layer having a peak temperature (P1) of tan δ of −20° C. or higher can be more easily formed.
The peak temperature (P1) of tan δ may be, for example, any one of −20 to 12° C., −20 to 10° C., −20 to 6° C., −20 to 2° C., and −20 to −2° C. However, these are just examples of the peak temperature (P1) of tan δ.

The peak temperature (P1) of tan δ can be measured, for example, by the following method.
That is, when measuring the storage modulus E' of the above-mentioned second test piece, the loss modulus E'' is also measured at the same time, and the loss tangent is calculated from the measured values of the storage modulus E' and the loss modulus E'' at the same temperature, and the temperature showing the peak of the loss tangent is adopted as the peak temperature (P1) (°C) of tan δ.

<Storage modulus (E'232)>
A third test piece having a thickness of 200±20 μm is prepared by laminating a plurality of first test pieces of the pressure-sensitive adhesive layer each having a thickness of less than 200 μm, and the storage modulus E′ of the third test piece is measured while heating the third test piece from −20° C. to 150° C. under conditions of a frequency of 11 Hz, a temperature rise rate of 3° C./min, and a uniform temperature rise in tension mode. When the storage modulus E′ of the third test piece is measured, it is preferable that the storage modulus (E′232) when the temperature of the third test piece is 23° C. is 1.5 MPa or less. By using such a support sheet, even if the support sheet with a workpiece or workpiece attached is not heated at a high temperature, the effect of suppressing cracking of the pressure-sensitive adhesive layer in the support sheet is enhanced when the support sheet is expanded.
When measuring the storage modulus E' of the third test piece, for example, the third test piece can be held at two points spaced apart by a distance of 20 mm.

The storage modulus (E'232) is more preferably 1.2 MPa or less, and may be, for example, any one of 0.9 MPa or less, 0.7 MPa or less, and 0.5 MPa or less. When the storage modulus (E'232) is equal to or less than the upper limit, even if the support sheet is not heated at a high temperature, the effect of suppressing cracking of the pressure-sensitive adhesive layer in the support sheet when the support sheet is expanded is further enhanced.
The lower limit of the storage modulus (E'232) is not particularly limited. For example, a pressure-sensitive adhesive layer having a storage modulus (E'232) of 0.2 MPa or more can be more easily formed.
The storage modulus (E'232) may be, for example, any one of 0.2 to 1.5 MPa, 0.2 to 1.2 MPa, 0.2 to 0.9 MPa, 0.2 to 0.7 MPa, and 0.2 to 0.5 MPa.

The storage modulus (E'232) can be measured, for example, by the following method.
That is, first, a plurality of pressure-sensitive adhesive layers each having a thickness of less than 200 μm are prepared, and these are designated as first test pieces. These first test pieces are the same as the first test pieces used in measuring the storage modulus (E′231) described above.
Next, these first test pieces (adhesive layers) are laminated together in the thickness direction to prepare a third test piece having a thickness of 200±20 μm. The third test piece may be the same as the second test piece, except that the first test piece used to prepare the third test piece is not heated at 130° C.
Next, the third test piece is held at two locations with an interval of 20 mm, and in this state, the storage elastic modulus E' of the third test piece is measured under the condition of a frequency of 11 Hz while the temperature of the third test piece is raised uniformly from -20°C to 150°C at a temperature rise rate of 3°C/min. Then, the storage elastic modulus E' of the third test piece when the temperature is 23°C is adopted as the storage elastic modulus (E'232).
As in the case of the second test piece, the third test piece was held at two points 20 mm apart, which means that the length of the portion of the third test piece to be measured for the storage modulus E' was 20 mm.

The method for bonding (stacking) the first test pieces together when preparing the third test piece is the same as the method for bonding (stacking) the first test pieces together after heating when preparing the second test piece.
The storage modulus E' of the third test piece can be measured in the same manner as the storage modulus E' of the second test piece.

<Tan δ Peak Temperature (P2)>
A third test piece having a thickness of 200±20 μm was prepared by laminating a plurality of first test pieces of the pressure-sensitive adhesive layer each having a thickness of less than 200 μm, and the third test piece was measured for the storage modulus E′ and loss modulus E″ of the third test piece while heating the third test piece from −20° C. to 150° C. in a tensile mode under conditions of a frequency of 11 Hz, a temperature rise rate of 3° C./min, and a uniform temperature rise. When the loss tangent was calculated from these measured values, the temperature showing the peak of the loss tangent (sometimes referred to herein as the “peak temperature (P2)”) may be, for example, 12° C. or lower, but is preferably 10° C. or lower. By using such a support sheet, the effect of suppressing cracking of the pressure-sensitive adhesive layer in the support sheet is enhanced when the support sheet is expanded, even if the support sheet is not heated at a high temperature.
When measuring the storage modulus E' and loss modulus E'' of the third test piece, the third test piece can be held at two points with an interval of 20 mm, for example.

The tan δ peak temperature (P2) is more preferably 6° C. or lower, and may be, for example, either 2° C. or lower or −2° C. or lower. The lower the tan δ peak temperature (P2), the higher the effect of suppressing cracking of the pressure-sensitive adhesive layer in the support sheet.
There is no particular limitation on the lower limit of the peak temperature (P2) of tan δ. For example, a pressure-sensitive adhesive layer having a peak temperature (P2) of tan δ of −−20° C. or higher can be more easily formed.
The peak temperature (P2) of tan δ may be, for example, any one of −20 to 12° C., −20 to 10° C., −20 to 6° C., −20 to 2° C., and −20 to −2° C. However, these are just examples of the peak temperature (P2) of tan δ.

The peak temperature (P2) of tan δ can be measured, for example, by the following method.
That is, when measuring the storage modulus E' of the above-mentioned third test piece, the loss modulus E'' is also measured at the same time, and the loss tangent is calculated from the measured values of the storage modulus E' and the loss modulus E'' at the same temperature, and the temperature showing the peak of the loss tangent is adopted as the peak temperature (P2) (°C) of tan δ.

<Adhesive strength (X1)>
The adhesive strength (X1) is 400 mN/25 mm or less, preferably 340 mN/25 mm or less, and may be, for example, 280 mN/25 mm or less, 220 mN/25 mm or less, or 180 mN/25 mm or less. The smaller the adhesive strength (X1), the higher the pick-up ability, which allows the workpiece to be picked up from the cured support sheet without any problems.
The lower limit of the adhesive strength (X1) is not particularly limited. For example, a pressure-sensitive adhesive layer having an adhesive strength (X1) of 30 mN/25 mm or more can be more easily formed.
The adhesive strength (X1) may be, for example, any one of 30 to 400 mN/25 mm, 30 to 340 mN/25 mm, 30 to 280 mN/25 mm, 30 to 220 mN/25 mm, and 30 to 180 mN/25 mm or less, although these are just examples of the adhesive strength (X1).

The adhesive strength (X1) can be measured, for example, by the following method.
That is, first, a test piece having a width of 25 mm is cut out from a support sheet.
Next, the test piece (support sheet) is attached to the mirror surface of the silicon mirror wafer using the adhesive layer therein, to produce a silicon mirror wafer with the test piece attached. The attachment is preferably carried out at room temperature, at an attachment speed of 290 to 310 mm/min, and with an attachment pressure of 0.3 MPa using a laminating roller.
The resulting silicon mirror wafer with the test piece attached is then heated at 130° C. for 2 hours.
Next, the silicon mirror wafer with the test piece is allowed to cool to a temperature of 23°C, and then the adhesive layer in the cooled silicon mirror wafer with the test piece is irradiated with energy rays through the substrate under conditions of an illuminance of 230 mW/ ^cm2 and a light quantity of 200 mJ/ ^cm2 , thereby curing the adhesive layer in the test piece.
Next, the test piece is peeled from the silicon mirror wafer at room temperature at a peel rate of 300 mm/min. At this time, the test piece is peeled in its length direction so that the surface of the silicon mirror wafer to which the test piece was attached forms an angle of 180° with the surface of the test piece to which the silicon mirror wafer was attached, a so-called 180° peel. The load (peel force) during this 180° peel is measured, and the measurement length is set to 50 mm. The measurement values for the first 5 mm and the last 5 mm are excluded from the valid value. The average of these measurements is then used as the adhesive strength (X1) (mN/25 mm).
In this embodiment, such peel strength measurements may be performed on two or more test pieces (support sheets), and the average value of the obtained multiple measured values may be used as the adhesive strength (X1).

<Adhesive strength (X2)>
When the support sheet is attached to the mirror surface of a silicon mirror wafer by the adhesive layer, the adhesive layer after attachment is heated at 130° C., and the adhesive strength (X2) between the adhesive layer and the silicon mirror wafer after heating (sometimes simply referred to as “adhesive strength (X2)” in this specification) is measured, it is preferable that the adhesive strength (X2) is 13,000 mN/25 mm or more. By using such a support sheet, even after the support sheet with the workpiece or workpiece attached thereto is heated at a high temperature, peeling of the workpiece from the support sheet is suppressed even if a large force is applied to the workpiece due to processing the workpiece or handling of the workpiece or its surrounding objects.

Examples of the above-mentioned "workpiece processing" include the production of semiconductor chips by forming a modified layer inside a semiconductor wafer, holding the semiconductor wafer in this state on a support sheet, and expanding the support sheet to divide the semiconductor wafer at the modified layer. Other examples of workpiece processing include the production of semiconductor chips by forming a groove in the thickness direction of the semiconductor wafer at the location where the semiconductor wafer will be divided into semiconductor chips, known as half-cutting, and then holding the semiconductor wafer in this state on a support sheet and expanding the support sheet to divide the semiconductor wafer at the groove.

The above-mentioned "handling of the workpiece or its surroundings" can be exemplified by, for example, holding a group of semiconductor chips, in which many semiconductor chips are aligned, on a support sheet and expanding the support sheet to expand the support sheet between adjacent semiconductor chips and increase the distance between adjacent semiconductor chips, a process known as kerf width expansion. Even when a large force is applied to the workpiece, the workpiece is prevented from peeling off the support sheet, so even when the kerf width is expanded without processing the workpiece, peeling of the workpiece from the support sheet is naturally prevented.

The adhesive strength (X2) is more preferably 14,000 mN/25 mm or more, and may be, for example, 14,700 mN/25 mm or more, 15,400 mN/25 mm or more, or 16,100 mN/25 mm or more. The greater the adhesive strength (X2), the greater the effect of suppressing peeling of the workpiece from the support sheet.
The upper limit of the adhesive strength (X2) is not particularly limited. For example, a pressure-sensitive adhesive layer having an adhesive strength (X2) of 19000 mN/25 mm or less can be more easily formed.
The adhesive strength (X2) may be, for example, any one of 13,000 to 19,000 mN/25 mm, 14,000 to 19,000 mN/25 mm, 14,700 to 19,000 mN/25 mm, 15,400 to 19,000 mN/25 mm, and 16,100 to 19,000 mN/25 mm. However, these are just examples of the adhesive strength (X2).

The adhesive strength (X2) can be measured, for example, by the following method.
That is, a silicon mirror wafer with a test piece is prepared in the same manner as in measuring the adhesive strength (X1), heated at 130°C for 2 hours, and then allowed to cool to a temperature of 23°C.
Next, in an environment of 23°C, the test piece is peeled from the cooled silicon mirror wafer at a peel rate of 300 mm/min. At this time, the test piece is peeled in its length direction so that the surface of the silicon mirror wafer to which the test piece was attached forms an angle of 180° with the surface of the test piece to which the silicon mirror wafer was attached, a so-called 180° peel. The load (peel force) during this 180° peel is measured, and the measurement length is set to 50 mm. The measurement values for the first 5 mm and the last 5 mm are excluded from the valid value. The average of these measurements is then used as the adhesive strength (X2) (mN/25 mm).
In this embodiment, such peel strength measurements may be performed on two or more test pieces (support sheets), and the average value of the obtained multiple measured values may be used as the adhesive strength (X2).

<Adhesive strength (Y1)>
When the support sheet is attached to the surface of a stainless steel (SUS) plate by the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer after attachment is heated at 130°C, the pressure-sensitive adhesive layer after heating is cured with energy rays, and the adhesive strength (Y1) (sometimes simply referred to as "adhesive strength (Y1)" in this specification) between the energy-ray-cured product of the pressure-sensitive adhesive layer and the stainless steel plate is measured, it is preferable that the adhesive strength (Y1) is 300 mN/25 mm or more.
In the method for manufacturing a workpiece, described later, a workpiece with a support sheet, which includes a workpiece and a support sheet attached to the workpiece, is fixed to a ring frame. Then, in this state, a workpiece is produced from the workpiece, and the adhesive layer in the support sheet is cured with energy rays to form a cured support sheet. That is, after the adhesive layer is cured with energy rays, the workpiece with a support sheet can be produced as follows: a workpiece with a cured support sheet, which includes a workpiece and a cured support sheet attached to the workpiece; a workpiece with a cured support sheet, which includes a workpiece and a cured support sheet attached to the workpiece; etc. In this way, after the adhesive layer is cured with energy rays, a stack of the workpiece or workpiece and the cured support sheet is fixed to the ring frame.
Furthermore, by using a support sheet having an adhesive strength (Y1) of 300 mN/25 mm or more, even if the workpiece with the support sheet is further heated while fixed to the ring frame and then energy rays are irradiated to the contact area between the support sheet (adhesive layer) and the ring frame, peeling of the laminate of the workpiece or workpiece processed product and the hardened support sheet from the ring frame is suppressed.

The adhesive strength (Y1) is more preferably 400 mN/25 mm or more, and may be, for example, 500 mN/25 mm or more or 600 mN/25 mm or more. The greater the adhesive strength (Y1), the greater the effect of suppressing peeling of the laminate of the workpiece or workpiece product and the cured support sheet from the ring frame.
The upper limit of the adhesive strength (Y1) is not particularly limited. For example, a pressure-sensitive adhesive layer having an adhesive strength (Y1) of 2000 mN/25 mm or less can be more easily formed.
The adhesive strength (Y1) may be, for example, any one of 300 to 2000 mN/25 mm, 400 to 2000 mN/25 mm, 500 to 2000 mN/25 mm, and 600 to 2000 mN/25 mm, although these are just examples of the adhesive strength (Y1).

The adhesive strength (Y1) can be measured, for example, by the following method.
That is, first, a test piece having a width of 25 mm is cut out from a support sheet.
Next, this test piece (support sheet) is attached to one side of a 1000 μm thick SUS plate using the adhesive layer therein to prepare a SUS plate with a test piece attached. The attachment is preferably carried out at room temperature, at an attachment speed of 290 to 310 mm/min, and with an attachment pressure of 0.3 MPa using a laminating roller.
Next, the resulting SUS plate with the test piece attached is heated at 130° C. for 2 hours.
Next, the SUS plate with the test piece attached is allowed to cool to a temperature of 23°C, and then the pressure-sensitive adhesive layer in the cooled SUS plate with the test piece attached is irradiated with energy rays through the substrate under conditions of an illuminance of 230 mW/ ^cm2 and a light quantity of 200 mJ/ ^cm2 , thereby curing the pressure-sensitive adhesive layer in the test piece.
Next, the test piece was peeled from the SUS plate at room temperature at a peel rate of 300 mm/min. The test piece was peeled in the longitudinal direction so that the surface of the SUS plate to which the test piece was attached formed an angle of 180° with the surface of the test piece to which the SUS plate was attached, a so-called 180° peel. The load (peel force) at this 180° peel was measured, and the measurement length was set to 50 mm. The measured values at the first 5 mm and the last 5 mm were excluded from the effective value. The average of these measured values was then used as the adhesive strength (Y1) (mN/25 mm).
In this embodiment, such peel strength measurements may be performed on two or more test pieces (support sheets), and the average value of the obtained multiple measured values may be used as the adhesive strength (Y1).

<Adhesive strength (Y2)>
When the support sheet is attached to the surface of a stainless steel (SUS) plate by the adhesive layer, the adhesive layer after attachment is heated at 130° C., and the adhesive strength (Y2) between the adhesive layer and the stainless steel plate after heating (sometimes simply referred to as “adhesive strength (Y2)” in this specification) is measured, it is preferable that the adhesive strength (Y2) is 13,000 mN/25 mm or more. By using such a support sheet, even if a workpiece with a support sheet or a workpiece with a support sheet comprising a workpiece and a support sheet provided on the workpiece is further heated while fixed to a ring frame in a method for manufacturing a workpiece described later, peeling of the workpiece with a support sheet or the workpiece with a support sheet from the ring frame is suppressed.

The adhesive strength (Y2) is more preferably 14,000 mN/25 mm or more, and may be, for example, 15,000 mN/25 mm or more, 16,000 mN/25 mm or more, or 17,000 mN/25 mm or more. The greater the adhesive strength (Y2), the greater the effect of suppressing peeling of the workpiece with the support sheet or the workpiece processed with the support sheet from the ring frame.
The upper limit of the adhesive strength (Y2) is not particularly limited. For example, a pressure-sensitive adhesive layer having an adhesive strength (Y2) of 20,000 mN/25 mm or less can be more easily formed.
The adhesive strength (Y2) may be, for example, any one of 13,000 to 20,000 mN/25 mm, 14,000 to 20,000 mN/25 mm, 15,000 to 20,000 mN/25 mm, 16,000 to 20,000 mN/25 mm, and 17,000 to 20,000 mN/25 mm, although these are just examples of the adhesive strength (Y2).

The adhesive strength (Y2) can be measured, for example, by the following method.
That is, a SUS plate with a test piece is prepared in the same manner as in the measurement of adhesive strength (Y1), heated at 130°C for 2 hours, and then allowed to cool to a temperature of 23°C.
Next, the test piece was peeled from the cooled SUS plate at a peel rate of 300 mm/min in an environment of 23°C. At this time, the test piece was peeled in its length direction so that the surface of the SUS plate to which the test piece was attached formed an angle of 180° with the surface of the test piece to which the SUS plate was attached, a so-called 180° peel. The load (peel force) at this 180° peel was measured, and the measurement length was set to 50 mm. The measured values at the first 5 mm and the last 5 mm were excluded from the effective value. The average value of these measurements was then used as the adhesive strength (Y2) (mN/25 mm).
In this embodiment, such peel strength measurements may be performed on two or more test pieces (support sheets), and the average value of the obtained multiple measured values may be used as the adhesive strength (Y2).

<Method for adjusting adhesive strength of adhesive layer>
The various adhesive strengths of the pressure-sensitive adhesive layer described above, i.e., the adhesive strength (X1) between the energy ray-cured product of the pressure-sensitive adhesive layer after heating and the silicon mirror wafer; the adhesive strength (X2) between the energy ray-cured product of the pressure-sensitive adhesive layer after heating and the silicon mirror wafer; the adhesive strength (Y1) between the energy ray-cured product of the pressure-sensitive adhesive layer after heating and the SUS plate; and the adhesive strength (Y2) between the pressure-sensitive adhesive layer after heating and the SUS plate, can be adjusted by adjusting the types and contents of the components contained in the pressure-sensitive adhesive layer.

For example, the adhesive strength (X1) can be reduced by incorporating into the pressure-sensitive adhesive layer an energy ray-curable acrylic resin (Ia) having a structural unit derived from a functional group-containing monomer having a methacrylic group.
For example, by incorporating an energy ray-curable acrylic resin (Ia) having a relatively high glass transition temperature into the pressure-sensitive adhesive layer, the adhesive strength (X1) can be reduced.
For example, when a functional group (e.g., a hydroxyl group) in the acrylic polymer is reacted with a group in the unsaturated group-containing compound capable of bonding to the functional group (e.g., an isocyanate group in (meth)acryloyloxyethyl isocyanate), the total number of moles of groups in the unsaturated group-containing compound capable of bonding to the functional group is set to a relatively large amount (e.g., 0.75 times or more) relative to the total number of moles of the functional groups in the acrylic polymer to prepare an energy ray-curable acrylic resin (Ia), and the pressure-sensitive adhesive layer contains such energy ray-curable acrylic resin (Ia), thereby making it possible to reduce the adhesive strength (X1).

For example, when the pressure-sensitive adhesive layer contains the energy ray-curable compound (α), the adhesive strength (X2) can be made higher than when the pressure-sensitive adhesive layer does not contain the energy ray-curable compound (α), but the adhesive strength (X2) can be made even higher by adjusting the type of energy ray-curable compound (α).
For example, when using an energy ray-curable acrylic resin (Ia) obtained by reacting a functional group (e.g., a hydroxyl group) in the acrylic polymer with a group capable of bonding to the functional group in the unsaturated group-containing compound (e.g., an isocyanate group in (meth)acryloyloxyethyl isocyanate), the adhesive strength (X2) can be increased by incorporating into the pressure-sensitive adhesive layer an energy ray-curable acrylic resin (Ia) having a small amount of unreacted functional groups derived from the acrylic polymer (in other words, having a small amount of functional groups capable of reacting with the crosslinking agent (β)).
For example, by reducing the content of the crosslinking agent (β) in the pressure-sensitive adhesive layer, the adhesive strength (X2) can be increased.

For example, the adhesive strength (Y1) can be increased by incorporating an energy ray-curable acrylic resin (Ia) having a structural unit derived from a functional group-containing monomer having a methacrylic group into the adhesive layer.
For example, by incorporating a (meth)acrylic acid ester having an oxygen atom (—O—) as the substituent into the pressure-sensitive adhesive layer as the energy ray-curable compound (α), the adhesive strength (Y1) can be increased.
For example, when using an energy ray-curable acrylic resin (Ia) obtained by reacting a functional group (e.g., a hydroxyl group) in the acrylic polymer with a group capable of bonding to the functional group in the unsaturated group-containing compound (e.g., an isocyanate group in (meth)acryloyloxyethyl isocyanate), the adhesive strength (Y1) can be increased by incorporating into the pressure-sensitive adhesive layer an energy ray-curable acrylic resin (Ia) having a small amount of unreacted functional groups derived from the acrylic polymer (in other words, having a small amount of functional groups capable of reacting with the crosslinking agent (β)).
For example, by reducing the content of the crosslinking agent (β) in the pressure-sensitive adhesive layer, the adhesive strength (Y1) can be increased.

For example, when the pressure-sensitive adhesive layer contains the energy ray-curable compound (α), the adhesive strength (Y2) can be made higher than when the pressure-sensitive adhesive layer does not contain the energy ray-curable compound (α), but the adhesive strength (Y2) can be made even higher by adjusting the type of energy ray-curable compound (α).
For example, when using an energy ray-curable acrylic resin (Ia) obtained by reacting a functional group (e.g., a hydroxyl group) in the acrylic polymer with a group capable of bonding to the functional group in the unsaturated group-containing compound (e.g., an isocyanate group in (meth)acryloyloxyethyl isocyanate), the adhesive strength (Y2) can be increased by incorporating into the pressure-sensitive adhesive layer an energy ray-curable acrylic resin (Ia) having a small amount of unreacted functional groups derived from the acrylic polymer (in other words, having a small amount of functional groups capable of reacting with the crosslinking agent (β)).
For example, the adhesive strength (Y2) can be increased by reducing the content of the crosslinking agent (β) in the adhesive layer.

For example, in a pressure-sensitive adhesive layer containing an energy ray-curable compound (α), an energy ray-curable acrylic resin (Ia), and a crosslinking agent (β), by using a crosslinking agent (β) having a chain structure without a ring structure, the adhesive strength (Y2) tends to be higher and the adhesive strength (X1) tends to be lower than when a crosslinking agent (β) having a ring structure is used.
For example, in a pressure-sensitive adhesive layer containing an energy ray-curable compound (α), an energy ray-curable acrylic resin (Ia), and a crosslinking agent (β), by using a crosslinking agent (β) having a urethane bond, such as a trimethylolpropane adduct of diisocyanate, the adhesive strength (Y2) tends to be higher and the adhesive strength (X1) tends to be lower than when a crosslinking agent (β) not having a urethane bond is used.
For example, in a pressure-sensitive adhesive layer containing an energy ray-curable compound (α), an energy ray-curable acrylic resin (Ia), and a crosslinking agent (β), by reducing the content of the energy ray-curable compound (α), the adhesive strength (X1) can be made lower than when the content of the energy ray-curable compound (α) is increased.

<Average value of light transmittance (400 to 800 nm) of support sheet>
The average light transmittance (400 to 800 nm) of the support sheet is preferably 80% or more, and may be, for example, 82% or more or 84% or more. When the average light transmittance (400 to 800 nm) is equal to or greater than the lower limit, inspection accuracy is improved when inspecting the workpiece for damage such as cracks and chips (e.g., chipping) through the support sheet while the workpiece is held on the support sheet.
The upper limit of the average value of the light transmittance (400 to 800 nm) is not particularly limited. For example, a support sheet having an average value of the light transmittance (400 to 800 nm) of 95% or less can be more easily produced.
The average value of the light transmittance (400 to 800 nm) may be, for example, any one of 80 to 95%, 82 to 95%, and 84 to 95%, although these are just examples of the average value of the light transmittance (400 to 800 nm).
However, in this specification, unless otherwise specified, the light transmittance of the support sheet is not limited to the light transmittance in the wavelength range of 400 to 800 nm, but refers to the light transmittance of the support sheet in a state where no release film is provided.

The average light transmittance (400 to 800 nm) of the support sheet can be calculated, for example, by the following method.
That is, the support sheet is irradiated with light from outside the substrate side, and the light transmittance is measured by direct light reception without using an integrating sphere, and the light transmittance value T _n (where n is an integer from 400 to 800) is measured at wavelengths of n (nm) in 1 nm increments in the wavelength range of 400 to 800 nm. Then, all T _n values where n is 400 to 800 are added together, and the total value T _400-800 is calculated. The obtained T _400-800 is divided by the number of T _n measurements (i.e., 800-400+1=401) (T _400-800 /401), and the average light transmittance (400 to 800 nm) of the support sheet can be calculated.

The average light transmittance (400-800 nm) of the support sheet can be adjusted, for example, by adjusting the type and amount of components contained in the substrate and the roughness of both surfaces of the substrate (e.g., surface roughness (Ra)). The average light transmittance (400-800 nm) of the support sheet can also be adjusted by adjusting the type and amount of components contained in the pressure-sensitive adhesive layer.

<Example of support sheet>
In addition to the storage modulus (E'231) and adhesive strength (X1), the support sheet preferably has one or more properties selected from the group consisting of the peak temperature of tan δ (P1), the storage modulus (E'232), the peak temperature of tan δ (P2), adhesive strength (X2), adhesive strength (Y1), and adhesive strength (Y2) that fall within any of the above-mentioned numerical ranges.
That is, an example of a preferable support sheet is, for example, a sheet that satisfies the following condition (1-1):
(1-1) The storage modulus (E'231) of the second test piece prepared from the pressure-sensitive adhesive layer is 1.5 MPa or less.
and the following condition (1-2):
(1-2) The adhesive strength (X1) between the energy ray-cured adhesive layer after heating and the silicon mirror wafer is 400 mN/25 mm or less.
and satisfy the following conditions (1-3) to (1-8):
(1-3) The peak temperature (P1) of tan δ of the second test piece prepared from the pressure-sensitive adhesive layer is 10° C. or lower.
(1-4) The storage modulus (E'232) of the third test piece prepared from the pressure-sensitive adhesive layer is 1.5 MPa or less.
(1-5) The peak temperature (P2) of tan δ of the third test piece prepared from the pressure-sensitive adhesive layer is 10° C. or lower.
(1-6) The adhesive strength (X2) between the adhesive layer and the silicon mirror wafer after heating is 13,000 mN/25 mm or more.
(1-7) The adhesive strength (Y1) between the energy ray-cured adhesive layer after heating and a stainless steel plate is 300 mN/25 mm or more.
(1-8) The adhesive strength (Y2) between the pressure-sensitive adhesive layer and the SUS plate after heating is 13,000 mN/25 mm or more.
and a support sheet satisfying one or more of the following conditions:
A more preferable example of the support sheet is one that satisfies all of the above conditions (1-1) to (1-8).
In the support sheet exemplified here, it is particularly preferred that one or more selected from the group consisting of storage modulus (E'231), adhesive strength (X1), peak temperature of tan δ (P1), storage modulus (E'232), peak temperature of tan δ (P2), adhesive strength (X2), adhesive strength (Y1), and adhesive strength (Y2) are further limited to any of the numerical ranges described above.

The support sheet can be manufactured by laminating the above-mentioned constituent layers so that they are in a corresponding positional relationship, and adjusting the shapes of some or all of the layers as necessary. The method for forming each layer is as described above.
For example, the support sheet can be produced by applying the pressure-sensitive adhesive composition (I) to one surface (for example, a matte or glossy surface) of a substrate and drying it as necessary.

A support sheet can also be produced by applying the pressure-sensitive adhesive composition (I) to one side of a release film and drying it as necessary to form a pressure-sensitive adhesive layer on the release film, and then laminating the exposed surface of this pressure-sensitive adhesive layer to one side of a substrate (e.g., a matte or glossy surface). In this case, it is preferable to apply the pressure-sensitive adhesive composition (I) to the release-treated surface of the release film.

The pressure (application pressure) applied when adhering the pressure-sensitive adhesive layer to the substrate is preferably 0.2 to 0.6 MPa. By ensuring that the pressure is equal to or greater than the lower limit, the adhesive strength between the pressure-sensitive adhesive layer and the substrate can be sufficiently increased. Furthermore, when the pressure-sensitive adhesive layer is provided on the matte surface of the substrate by adjusting the composition of the pressure-sensitive adhesive layer, the adhesive layer can be more easily embedded into the matte surface of the substrate. By ensuring that the pressure is equal to or less than the upper limit, excessive pressure can be avoided.
The bonding of the pressure-sensitive adhesive layer to the substrate is preferably carried out under a temperature condition of, for example, 15° C. or higher, but may also be carried out at room temperature.

A support sheet having the other layer can be produced, for example, by applying a composition for forming the other layer to an appropriate location on the substrate or pressure-sensitive adhesive layer, drying as needed to form the other layer, and then laminating further required layers as needed. Alternatively, the support sheet can be produced by laminating a film-like other layer to an appropriate location on the substrate or pressure-sensitive adhesive layer to provide the other layer, and then laminating further required layers as needed.

Composite sheet for forming a protective film The support sheet can be laminated with a protective film-forming film to form a composite sheet for forming a protective film. That is, the composite sheet for forming a protective film includes the support sheet and a protective film-forming film provided on the surface of the support sheet opposite the substrate side of the pressure-sensitive adhesive layer. More specifically, the composite sheet for forming a protective film includes a substrate, a pressure-sensitive adhesive layer provided on one surface of the substrate, and a protective film-forming film provided on the surface of the pressure-sensitive adhesive layer opposite the substrate side. The composite sheet for forming a protective film may further include a release film provided on the surface of the protective film-forming film opposite the pressure-sensitive adhesive layer side.

<<Protective film forming film>>
The protective film-forming film is a film for forming a protective film at any location on the workpiece. By using the composite sheet for forming a protective film, a workpiece with a protective film can be manufactured, which includes a workpiece and a protective film provided at any location on the workpiece. For example, if the workpiece is a wafer, by using the composite sheet for forming a protective film, a chip with a protective film can be manufactured, which includes a chip and a protective film provided on the back surface of the chip.

The protective film-forming film may be curable or non-curable, that is, the protective film-forming film may function as a protective film by being cured, or may function as a protective film in an uncured state.
The curable protective film-forming film may be either thermosetting or energy ray-curable, or may have both thermosetting and energy ray-curable properties.

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, and there are no particular limitations on the combination of these multiple layers.

The thermosetting protective film-forming film may, for example, contain a polymer component (A) and a thermosetting component (B).
Examples of the polymer component (A) include acrylic resins, urethane resins, phenoxy resins, silicone resins, and saturated polyester resins.
Examples of the thermosetting component (B) include epoxy-based thermosetting resins, thermosetting polyimide resins, and unsaturated polyester resins.
In this specification, the term "thermosetting polyimide resin" is a general term for a polyimide precursor that forms a polyimide resin by thermal curing, and a thermosetting polyimide.
The epoxy thermosetting resin comprises an epoxy resin (B1) and a thermosetting agent (B2).

In addition to these components, the thermosetting protective film-forming film may further contain one or more selected from the group consisting of a curing accelerator (C), a filler (D), a coupling agent (E), a crosslinking agent (F), an energy ray-curable resin (G), a photopolymerization initiator (H), a colorant (I), and a general-purpose additive (J).

The energy ray-curable protective film-forming film may, for example, contain an energy ray-curable component (a).
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 energy ray-curable protective film-forming film preferably further contains a polymer (b) having no energy ray-curable group in addition to the energy ray-curable component (a).
Examples of the polymer (b) having no energy ray-curable group include acrylic resins, urethane resins, phenoxy resins, silicone resins, and saturated polyester resins.

In addition to the energy ray-curable component (a) and the polymer (b) that does not have an energy ray-curable group, the energy ray-curable protective film-forming film may further contain one or more components selected from the group consisting of colorants, thermosetting components, thermosetting agents, fillers, coupling agents, crosslinking agents, photopolymerization initiators, and general-purpose additives.

Examples of non-curable protective film-forming films include those containing a polymer component.
Examples of the polymer component include the same non-curable resins as the polymer component (A) listed as a component contained in the thermosetting protective film-forming film.

In addition to the polymer component, the non-curable protective film-forming film may further contain one or more additives selected from the group consisting of colorants, fillers, coupling agents, crosslinking agents, and general-purpose additives.

The thickness of the protective film-forming film is preferably 1 to 100 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 ability can be formed. When the thickness of the protective film-forming film is equal to or less than the upper limit, an excessive thickness of the protective film can be avoided.
Here, "thickness of the protective film-forming film" means the thickness of the entire protective film-forming film, and for example, the thickness of a protective film-forming film consisting of multiple layers means the total thickness of all layers that make up the protective film-forming film.

The protective film-forming film can be formed using a protective film-forming composition containing its constituent materials (a thermosetting protective film-forming composition for forming a thermosetting protective film-forming film, an energy ray-curable protective film-forming composition for forming an energy ray-curable protective film-forming film, or a non-curable protective film-forming composition for forming a non-curable protective film-forming film). 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.

[0033] The composite sheet for forming a protective film can be produced by laminating the aforementioned constituent layers so that they are in a corresponding positional relationship, and adjusting the shapes of some or all of the layers as necessary. The method for forming each layer is as described above.
For example, a protective film-forming composite sheet can be produced by applying a protective film-forming composition to one side of a release film and drying it as necessary to form a protective film-forming film on the release film, and then bonding the exposed surface of this protective film-forming film (the surface opposite the release film side) to the exposed surface of the pressure-sensitive adhesive layer in the support sheet (the surface opposite the substrate side).The protective film-forming composition is preferably applied to the release-treated surface of the release film.

◇Manufacturing method for workpieces (how to use support sheets)
The support sheet can be used in the manufacture of workpieces.
That is, a method for manufacturing a workpiece according to one embodiment of the present invention includes a bonding step of fixing a support sheet-attached workpiece, which includes the workpiece and the support sheet provided on the workpiece, to the ring frame by bonding the adhesive layer in the support sheet to the workpiece and a ring frame; a heating step of heating the adhesive layer in the support sheet fixed to the ring frame after the bonding step; and a modified layer for dividing the workpiece in the support sheet-attached workpiece to produce a modified layer-formed workpiece after the bonding step, or a slit for dividing the workpiece in the support sheet-attached workpiece in a partial region in the thickness direction of the workpiece to produce a semi-cut workpiece. The method includes a preliminary processing step of obtaining a pre-processed body with a support sheet, which comprises the workpiece with a modified layer formed thereon or the semi-cut workpiece and the support sheet; a processing step of expanding the pre-processed body with a support sheet fixed to the ring frame after the preliminary processing step in a direction parallel to the surface of the support sheet, thereby dividing the workpiece with a modified layer formed thereon at the location of the modified layer or dividing the semi-cut workpiece at the slits to produce the workpiece; a curing step of curing the adhesive layer attached to the ring frame with energy rays after the heating step and the processing step; and a pick-up step of separating the workpiece from the cured product of the adhesive layer and picking it up after the curing step.

When the workpiece is a semiconductor wafer, the manufacturing method of the workpiece, i.e., the manufacturing method of semiconductor chips, includes a bonding process in which the adhesive layer in the support sheet is bonded to the semiconductor wafer and a ring frame to fix a support sheet-attached semiconductor wafer, which includes the semiconductor wafer and the support sheet provided on the semiconductor wafer, to the ring frame; a heating process in which, after the bonding process, the adhesive layer in the support sheet fixed to the ring frame is heated; and, after the bonding process, a modified layer for dividing the semiconductor wafer is formed inside the semiconductor wafer in the support sheet-attached semiconductor wafer to produce a modified layer-formed semiconductor wafer, or a process in which a notch for dividing the semiconductor wafer is formed in a partial region in the thickness direction of the semiconductor wafer in the support sheet-attached semiconductor wafer to produce a semi-cut semiconductor wafer. a pre-processing step of producing a pre-processed semiconductor wafer from the modified layer-formed semiconductor wafer to obtain a pre-processed body with a support sheet, the pre-processed body including the modified layer-formed semiconductor wafer or the semi-cut semiconductor wafer and the support sheet; a processing step of expanding the pre-processed body with a support sheet, fixed to the ring frame, in a direction parallel to the surface of the support sheet after the pre-processing step, to divide the modified layer-formed semiconductor wafer at the site of the modified layer or to divide the semi-cut semiconductor wafer at the slits to produce the semiconductor chips; a curing step of curing the adhesive layer attached to the ring frame with energy rays after the heating step and processing step; and a pick-up step of detaching the semiconductor chip from the cured adhesive layer and picking it up after the curing step.

The order in which the heating step, pre-processing step, and processing step are performed after the bonding step can be freely selected depending on the purpose, except that the pre-processing step and processing step are performed in this order. For example, the heating step may be performed before the pre-processing step and processing step, or the pre-processing step and processing step may be performed before the heating step, or the pre-processing step may be performed before the heating step and processing step. For example, in the manufacturing method, a heating step can be performed to remove foreign matter, such as low-molecular-weight resin components, adhering to the surface of the workpiece by volatilization. In this case, the heating step can be performed either before or after the processing step. In addition, in the manufacturing method, a heating step can be performed to dry the workpiece after washing with water and removing fine foreign matter that is generated during processing, such as dividing the workpiece, or during pre-processing, such as forming the notches in the workpiece, and that is adhering to the surface of the workpiece. In this case, the heating step is performed after the processing step or pre-processing step. In the manufacturing method, the heating step for removing these foreign substances and the heating step for drying may be performed together, or these heating steps may be performed together.

<<Example of a manufacturing method for a workpiece>>
2 is a cross-sectional view for explaining an example of the manufacturing method when the workpiece is a semiconductor wafer. Here, the manufacturing method will be explained using the support sheet 1 shown in FIG.

<Attachment process>
In the attaching step, the pressure-sensitive adhesive layer 12 in the support sheet 1 is attached to the semiconductor wafer 9 (more specifically, the back surface 9b of the semiconductor wafer 9), which is the workpiece, and the ring frame 8, thereby fixing a support sheet-attached semiconductor wafer 109, which includes the semiconductor wafer 9 and the support sheet 1 provided on the back surface 9b of the semiconductor wafer 9, to the ring frame 8, as shown in Figure 2(a). The support sheet-attached semiconductor wafer 109 is the support sheet-attached workpiece.
The support sheet 1 is used after removing the release film 13. A surface 12a of the pressure-sensitive adhesive layer 12 opposite to the substrate 11 side is the same as one surface 1a of the support sheet 1 (the surface on the pressure-sensitive adhesive layer 12 side).
In FIG. 2, bumps and the like on the circuit surface 9a of the semiconductor wafer 9 are not shown.

In the attachment process, a region of the adhesive layer 12 near the center in the width direction is attached to the semiconductor wafer 9, and the region surrounding this attachment region to the semiconductor wafer 9 is attached to the ring frame 8.

The support sheet 1 (adhesive layer 12) can be attached to the semiconductor wafer 9 and the ring frame 8 at room temperature.
The speed at which the support sheet 1 (adhesive layer 12) is attached to the semiconductor wafer 9 and ring frame 8 is not particularly limited, but is preferably 200 to 400 mm/min.

<Heating process>
2(b), in the heating step after the laminating step, the adhesive layer 12 in the support sheet 1 fixed to the ring frame 8 is heated. In this case, the heating of the adhesive layer 12 is accompanied by the heating of the entire semiconductor wafer 109 with the support sheet, and this heating can remove, for example, foreign matter such as low-molecular-weight resin components adhering to the surface (e.g., circuit surface 9a) of the semiconductor wafer 9 by volatilization.

The temperature (heating temperature) at which the adhesive layer 12 (i.e., the adhesive layer 12 in the semiconductor wafer 109 with a support sheet) is heated is preferably 100 to 135°C. A heating temperature above the lower limit ensures sufficient heating effects. A heating temperature below the upper limit avoids excessive heating, thereby suppressing, for example, deterioration of the semiconductor wafer 109 with a support sheet.

When the adhesive strength (Y2) of the support sheet 1 is 13,000 mN/25 mm or more, peeling of the semiconductor wafer 109 with the support sheet from the ring frame 8 is suppressed even when the semiconductor wafer 109 with the support sheet is heated while fixed to the ring frame 8 during the heating process.

<Preliminary processing step>
After the bonding process and the heating process, in the preliminary processing process, as shown in Figure 2 (c), a modified layer 9d for dividing the semiconductor wafer 9 is formed inside the semiconductor wafer 9 in the semiconductor wafer 109 with the support sheet, thereby producing a semiconductor wafer 91 with a modified layer formed thereon, thereby obtaining a preliminary processed body 911A with the support sheet, which comprises the semiconductor wafer 91 with a modified layer formed thereon and the support sheet 1.
The modified layer-formed semiconductor wafer 91 is the same as the semiconductor wafer 9 except that a modified layer 9d is formed on the semiconductor wafer 91.
The modified layer-formed semiconductor wafer 91 is the modified layer-formed workpiece described above.
In FIG. 2C, reference numeral 91 a denotes the circuit surface of the semiconductor wafer 91 on which the modified layer has been formed, which corresponds to the circuit surface 9 a of the semiconductor wafer 9 .

The modified layer 9d can be formed by irradiating the semiconductor wafer 9 with laser light in a manner that focuses the laser light on the focal point, which is the position where the semiconductor wafer 9 will be divided, according to a known method.
The modified layer 9d has been altered and weakened in strength, unlike other portions of the modified-layer-formed semiconductor wafer 91. Therefore, when force is applied to the modified-layer-formed semiconductor wafer 91, cracks are generated in the modified layer 9d that extend in the direction of both surfaces of the modified-layer-formed semiconductor wafer 91, and these cracks become starting points for dividing (cutting) the modified-layer-formed semiconductor wafer 91 (semiconductor wafer 9).

<Processing process>
After the preliminary processing step, in the processing step, the support sheet-attached pre-processed body 911A fixed to the ring frame 8 is expanded in a direction parallel to the surface (one surface 1a) of the support sheet 1. In FIG. 2(c), this expansion direction is indicated by arrow I. Expanding the support sheet-attached pre-processed body 911A in this manner is equivalent to expanding the semiconductor wafer 9 in a direction parallel to its circuit surface 9a or back surface 9b. As a result, the modified layer-formed semiconductor wafer 91 (semiconductor wafer 9) is divided at the modified layer 9d, thereby producing semiconductor chips 90, which are workpieces, as shown in FIG. 2(d). Through the processing step, a support sheet-attached semiconductor chip group 901 is obtained, in which multiple semiconductor chips 90 are aligned and held on a single support sheet 1. This method of dividing a semiconductor wafer into semiconductor chips via the formation of a modified layer is known as Stealth Dicing (registered trademark). In this embodiment, dividing the semiconductor wafer 91 with the modified layer formed thereon is synonymous with dividing a semiconductor wafer by ordinary Stealth Dicing (registered trademark).

Reference numeral 90 a denotes a circuit surface of the semiconductor chip 90 that corresponds to the circuit surface 9 a of the semiconductor wafer 9 .
Reference numeral 90 b denotes the back surface of the semiconductor chip 90 , which corresponds to the back surface 9 b of the semiconductor wafer 9 .

In the processing step, the support sheet-attached pre-processed body 911A expands, applying force to the modified layer-formed semiconductor wafer 91 (semiconductor wafer 9), dividing the modified layer-formed semiconductor wafer 91 (semiconductor wafer 9) at the modified layer 9d, and producing semiconductor chips 90.

The pre-processed body 911A with support sheet can be expanded using known methods. For example, a table that can move up and down (movement in two directions, the direction in which the base material 11 and adhesive layer 12 in the support sheet 1 are stacked) is prepared, and the support sheet 1 (more specifically, the base material 11) in the pre-processed body 911A with support sheet is brought into contact with the surface of this table, and the pre-processed body 911A with support sheet is fixed on this table. Then, while the ring frame 8 remains fixed, the table is pushed upward (in the direction from the base material 11 in the support sheet 1 toward the adhesive layer 12), thereby expanding the pre-processed body 911A with support sheet.

When expanding the support sheet-attached pre-processed body 911A by pushing up the table in this way, the push-up speed is preferably 1 to 400 mm/s, the push-up height is preferably 5 to 35 mm, and the push-up holding time (in other words, the time the push-up height is held at its maximum) is preferably 0 to 2 minutes. By using these push-up conditions, cracking of the adhesive layer 12 can be highly suppressed, while the modified layer-formed semiconductor wafer 91 (semiconductor wafer 9) can be divided more accurately.

When the pre-processed body 911A with support sheet is expanded, if necessary, a fixing jig (for example, a grip ring manufactured by Technovision) may be attached to the expanded support sheet 1 to fix the expanded support sheet 1. Alternatively, after expanding the support sheet 1 using a heat-shrinkable base material 11, the heat-shrinkable properties of the base material 11 may be used to remove slack in the support sheet 1, and the support sheet 1 may be fixed in its expanded state without attaching a fixing jig.

In the processing step, the expansion of the pre-processed body 911A with support sheet can be carried out in a temperature environment of, for example, -10 to 40°C, and is preferably carried out at room temperature.

By having a storage modulus (E'231) of 1.5 MPa or less in the support sheet 1, cracking of the adhesive layer 12 in the support sheet 1 is suppressed when the support sheet 1 is expanded, even after the support sheet 1 with the semiconductor wafer 9 attached thereto (in other words, the semiconductor wafer 109 with the support sheet) is heated at a high temperature up to approximately 135°C in the heating step.

For example, when the tan δ peak temperature (P1) of the support sheet 1 is 10°C or less, cracking of the adhesive layer 12 in the support sheet 1 is further suppressed when the support sheet 1 is expanded, even after the support sheet 1 with the semiconductor wafer 9 attached thereto (in other words, the semiconductor wafer 109 with the support sheet) is heated at a high temperature.

For example, if the storage modulus (E'232) of the support sheet 1 is 1.5 MPa or less, cracking of the adhesive layer 12 in the support sheet 1 is further suppressed when the support sheet 1 is expanded, even if the support sheet 1 with the semiconductor wafer 9 attached thereto (in other words, the semiconductor wafer 109 with the support sheet) is not heated at a high temperature.

For example, when the tan δ peak temperature (P2) of the support sheet 1 is 10°C or less, cracking of the pressure-sensitive adhesive layer 12 in the support sheet 1 is further suppressed when the support sheet 1 is expanded, even if the support sheet 1 with the semiconductor wafer 9 attached thereto (in other words, the semiconductor wafer 109 with the support sheet) is not heated at a high temperature.

When the adhesive strength (X2) of the support sheet 1 is 13,000 mN/25 mm or greater, even after the support sheet 1 with the semiconductor wafer 9 attached (in other words, the semiconductor wafer 109 with the support sheet) is heated at a high temperature up to approximately 135°C in the heating step, peeling of the semiconductor chip 90 from the support sheet 1 (adhesive layer 12) is suppressed even when a large force is applied to the semiconductor chip 90 during the processing step, such as by dividing the semiconductor wafer 91 (semiconductor wafer 9) with the modified layer formed thereon or by washing the semiconductor chip 90 with water.

<Curing process>
After the heating step and the processing step, in the curing step, the adhesive layer 12 attached to the ring frame 8 is cured with energy rays, as shown in Fig. 2(e) . The curing step provides a group of semiconductor chips 901' with a cured support sheet, in which a plurality of semiconductor chips 90 are aligned and held on a single cured support sheet 1'.
The support sheet 1 becomes a cured support sheet 1' when the pressure-sensitive adhesive layer 12 is cured with energy rays to become an energy ray-cured product 12'.
The group of semiconductor chips with a cured support sheet 901' is a laminate of the workpiece and the cured support sheet (in other words, a workpiece with a cured support sheet) as described above, and is the same as the group of semiconductor chips with a support sheet 901 except that the adhesive layer 12 is the energy ray cured product 12'.

When the pressure-sensitive adhesive layer 12 is cured with energy rays (when the pressure-sensitive adhesive layer 12 is irradiated with energy rays), the illuminance of the energy rays is preferably 60 to 320 mW/ ^cm2 , and the light amount of the energy rays is preferably 100 to 1000 mJ/ ^cm2 .
The energy rays are preferably irradiated onto the pressure-sensitive adhesive layer 12 from outside the support sheet 1 through the substrate 11 (via the substrate 11).

When the adhesive strength (Y1) of the support sheet 1 is 300 mN/25 mm or more, the semiconductor wafer 109 with the support sheet is heated while fixed to the ring frame 8 during the heating process, and even if the contact portion of the support sheet 1 (adhesive layer 12) with the ring frame 8 is irradiated with energy rays during the curing process, peeling of the cured semiconductor chip group 901' with the support sheet from the ring frame 8 is suppressed.

<Pickup process>
After the curing step, in the pick-up step, as shown in Fig. 2(f), the semiconductor chip 90 can be removed from the group of semiconductor chips 901' with the cured support sheet by detaching and picking up the semiconductor chip 90 from the energy ray-cured product 12' of the pressure-sensitive adhesive layer in the cured support sheet 1'. Here, the pick-up direction is indicated by arrow P.

When the semiconductor chip 90 is picked up, peeling occurs between the back surface 90b of the semiconductor chip 90 and the surface 12a' of the energy ray-cured product 12' of the adhesive layer opposite the substrate 11. At this time, the adhesive strength between the energy ray-cured product 12' of the adhesive layer and the semiconductor chip 90 is smaller than the adhesive strength between the adhesive layer 12 and the semiconductor chip 90, so the semiconductor chip 90 is easily peeled from the energy ray-cured product 12' of the adhesive layer and can be easily picked up.
The surface 12a' opposite the substrate 11 side of the energy ray-cured adhesive layer 12' corresponds to the surface 12a opposite the substrate 11 side of the adhesive layer 12, and is the same as one surface 1a' of the cured support sheet 1' (the surface of the energy ray-cured adhesive layer 12' side).

The semiconductor chip 90 can be picked up by a known method. For example, a vacuum collet or the like can be used as the separation means 7 for separating the semiconductor chip 90 from the cured support sheet 1' (the energy ray-cured adhesive layer 12').

When the adhesive strength (X1) of the support sheet 1 is 400 mN/25 mm or less, even after the support sheet 1 with the semiconductor wafer 9 attached (in other words, the semiconductor wafer 109 with the support sheet) is heated at a high temperature of up to approximately 135°C in the heating step, after the semiconductor chip 90 is fabricated from the semiconductor wafer 9 on the support sheet 1, the semiconductor chip 90 can be picked up normally from the cured support sheet 1', resulting in high pickup properties.

<Other processes>
The manufacturing method may include a step other than the adhering step, the heating step, the preliminary processing step, the processing step, the curing step, and the pick-up step.
The type of the other steps, the number of the other steps, and the timing of performing the other steps can all be selected arbitrarily depending on the purpose, and are not particularly limited.

<<Another example of a manufacturing method for a workpiece>>
In the method for manufacturing a workpiece (hereinafter, sometimes referred to as "manufacturing method (1A)") described above with reference to FIGS. 2(a) to 2(f), a semiconductor wafer with a modified layer formed thereon is prepared in the preliminary processing step, and the semiconductor wafer with a modified layer formed thereon is divided at the modified layer in the processing step. However, in this embodiment, as described above, the preliminary processing step and the processing step can be performed by other methods. That is, in the preliminary processing step of this embodiment, a support sheet-attached pre-processed body including the semi-cut semiconductor wafer and the support sheet is obtained, and in the processing step, the semi-cut semiconductor wafer is divided at the slits to produce the semiconductor chips. Next, a method for manufacturing a workpiece in this case (hereinafter, sometimes referred to as "manufacturing method (1B)") will be described. FIG. 3 is a cross-sectional view for schematically illustrating an example of the manufacturing method in this case. Here, a manufacturing method using the support sheet 1 shown in FIG. 1 will be described.

<Attachment process, heating process>
The attaching step and the heating step of the manufacturing method (1B) are the same as the attaching step and the heating step of the manufacturing method (1A), as shown in Figures 3(a) and 3(b), respectively, and therefore detailed descriptions of the attaching step and the heating step of the manufacturing method (1B) will be omitted.
Also in FIG. 3, bumps and the like on the circuit surface 9a of the semiconductor wafer 9 are omitted from the illustration.

<Preliminary processing step>
After the bonding step of manufacturing method (1B), in the preliminary processing step, as shown in FIG. 3(c), a notch 9e for dividing the semiconductor wafer 9 is formed in a partial region in the thickness direction of the semiconductor wafer 9 in the semiconductor wafer 109 with support sheet, thereby producing a semi-cut semiconductor wafer 92, thereby obtaining a pre-processed body 911B with support sheet comprising the semi-cut semiconductor wafer 92 and the support sheet 1.
The semi-cut semiconductor wafer 92 is the same as the semiconductor wafer 9 except that a notch 9e is formed.
The semi-cut semiconductor wafer 92 is the semi-cut workpiece described above.
In FIG. 3C, reference numeral 92 a denotes the circuit surface of the semi-cut semiconductor wafer 92 , which corresponds to the circuit surface 9 a of the semiconductor wafer 9 .
Reference numeral 92 b denotes the back surface of the semi-cut semiconductor wafer 92 , which corresponds to the back surface 9 b of the semiconductor wafer 9 .

The notch 9e extends from the circuit surface 92a of the semi-cut semiconductor wafer 92 to the opposite back surface 92b, reaching a region partway through the thickness of the semi-cut semiconductor wafer 92 without reaching the back surface 92b.

The notches 9e can be formed in the semiconductor wafer 9 using known methods. For example, the notches 9e can be formed in the semiconductor wafer 9 using various dicing methods, such as blade dicing using a blade, laser dicing using laser irradiation, or water dicing using water containing an abrasive.

<Processing process>
After the preliminary processing step of manufacturing method (1B), in the processing step, the support sheet-attached preliminarily processed body 911B fixed to the ring frame 8 is expanded in a direction parallel to the surface (one surface 1a) of the support sheet 1. In FIG. 3(c), this expansion direction is indicated by arrow I. Expanding the support sheet-attached preliminarily processed body 911B in this manner is equivalent to expanding the semiconductor wafer 9 in a direction parallel to its circuit surface 9a or back surface 9b. As a result, the semi-cut semiconductor wafer 92 (semiconductor wafer 9) is divided along the notches 9e, thereby producing semiconductor chips 90, which are workpieces, as shown in FIG. 3(d). The processing step results in a support sheet-attached semiconductor chip group 902, in which multiple semiconductor chips 90 are aligned and held on a single support sheet 1. In this embodiment, dividing the semi-cut semiconductor wafer 92 is equivalent to dividing a semiconductor wafer with a normal half cut.

In the processing step of manufacturing method (1B), the expanding pre-processed body 911B with support sheet applies force to the semi-cut semiconductor wafer 92 (semiconductor wafer 9), dividing the semi-cut semiconductor wafer 92 (semiconductor wafer 9) at the notches 9e to produce semiconductor chips 90.

The pre-processed body 911B with support sheet can be expanded in the same manner as the pre-processed body 911A with support sheet in manufacturing method (1A).

The semiconductor chip group 902 with a support sheet obtained by manufacturing method (1B) is the same as the semiconductor chip group 901 with a support sheet obtained by manufacturing method (1A), except that the distance between adjacent semiconductor chips 90 may vary.

By having a storage modulus (E'231) of 1.5 MPa or less in the support sheet 1, cracking of the pressure-sensitive adhesive layer 12 in the support sheet 1 is suppressed when the support sheet 1 is expanded in the heating step of manufacturing method (1B), even after the support sheet 1 with the semiconductor wafer 9 attached thereto (in other words, the semiconductor wafer 109 with the support sheet) is heated at a high temperature up to a maximum of approximately 135°C.

For example, if the tan δ peak temperature (P1) of the support sheet 1 is 10°C or less, cracking of the pressure-sensitive adhesive layer 12 in the support sheet 1 is further suppressed when the support sheet 1 is expanded in manufacturing method (1B), even after the support sheet 1 with the semiconductor wafer 9 attached thereto (in other words, the semiconductor wafer 109 with the support sheet) is heated at a high temperature.

For example, if the storage modulus (E'232) of the support sheet 1 is 1.5 MPa or less, cracking of the adhesive layer 12 in the support sheet 1 is further suppressed when the support sheet 1 is expanded, even if the support sheet 1 with the semiconductor wafer 9 attached thereto (in other words, the semiconductor wafer 109 with the support sheet) is not heated at a high temperature.

For example, when the tan δ peak temperature (P2) of the support sheet 1 is 10°C or less, cracking of the pressure-sensitive adhesive layer 12 in the support sheet 1 is further suppressed when the support sheet 1 is expanded, even if the support sheet 1 with the semiconductor wafer 9 attached thereto (in other words, the semiconductor wafer 109 with the support sheet) is not heated at a high temperature.

When the adhesive strength (X2) of the support sheet 1 is 13,000 mN/25 mm or greater, even after the support sheet 1 with the semiconductor wafer 9 attached thereto (in other words, the semiconductor wafer 109 with the support sheet) is heated at a high temperature up to approximately 135°C in the heating step of manufacturing method (1B), peeling of the semiconductor chip 90 from the support sheet 1 (adhesive layer 12) is suppressed even when a large force is applied to the semiconductor chip 90 during the processing step of manufacturing method (1B), such as by dividing the semi-cut semiconductor wafer 92 (semiconductor wafer 9) or washing the semiconductor chip 90 with water.

<Curing process>
After the heating step and processing step of manufacturing method (1B), in the curing step, the adhesive layer 12 attached to the ring frame 8 is cured with energy rays, as shown in Fig. 3(e) . The curing step provides a group of semiconductor chips 902' with a cured support sheet, in which a plurality of semiconductor chips 90 are aligned and held on a single cured support sheet 1'.
The support sheet 1 becomes a cured support sheet 1' when the pressure-sensitive adhesive layer 12 is cured with energy rays to become an energy ray-cured product 12'.
The group of semiconductor chips with cured support sheet 902' is a laminate of the workpiece and the cured support sheet (in other words, a workpiece with a cured support sheet) as described above, and is the same as the group of semiconductor chips with support sheet 902, except that the pressure-sensitive adhesive layer 12 is an energy ray-cured product 12'. Furthermore, the group of semiconductor chips with cured support sheet 902' is the same as the group of semiconductor chips with cured support sheet 901' obtained by manufacturing method (1A), except that the distance between adjacent semiconductor chips 90 may differ.

In the curing step of manufacturing method (1B), the pressure-sensitive adhesive layer 12 can be cured with energy rays in the same manner as in the curing step of manufacturing method (1A).

When the adhesive strength (Y1) of the support sheet 1 is 300 mN/25 mm or more, the support sheet-attached semiconductor wafer 109 is heated while fixed to the ring frame 8 during the heating step of manufacturing method (1B), and even if the contact portion of the support sheet 1 (adhesive layer 12) with the ring frame 8 is irradiated with energy rays during the curing step of manufacturing method (1B), peeling of the cured support sheet-attached semiconductor chip group 902' from the ring frame 8 is suppressed.

<Pickup process>
In the pick-up step after the curing step of manufacturing method (1B), the semiconductor chip 90 can be removed from the group of semiconductor chips 902' with the cured support sheet by detaching and picking up the semiconductor chip 90 from the energy ray-cured product 12' of the pressure-sensitive adhesive layer in the cured support sheet 1', as shown in Figure 3(f). Here, the pick-up direction is indicated by arrow P.

In the pick-up step of manufacturing method (1B), the semiconductor chip 90 can be picked up in the same manner as in the pick-up step of manufacturing method (1A), and at this time, the semiconductor chip 90 is separated from the energy ray-cured product 12' of the adhesive layer in the cured support sheet 1' in the same manner as in the pick-up step of manufacturing method (1A).

When the adhesive strength (X1) of the support sheet 1 is 400 mN/25 mm or less, even after the support sheet 1 with the semiconductor wafer 9 attached (in other words, the semiconductor wafer 109 with the support sheet) is heated at a high temperature of up to approximately 135°C in the heating step of manufacturing method (1B), after the semiconductor chip 90 is fabricated from the semiconductor wafer 9 on the support sheet 1, the semiconductor chip 90 can be successfully picked up from the cured support sheet 1', resulting in high pickup properties.

<Other processes>
The manufacturing method (1B) may include other steps that do not fall under any of the adhering step, heating step, pre-processing step, processing step, curing step, and pick-up step.
The type of the other steps, the number of the other steps, and the timing of performing the other steps can all be selected arbitrarily depending on the purpose, and are not particularly limited.

Manufacturing method (1B) may be the same as manufacturing method (1A), except that in the preliminary processing step, a semi-cut semiconductor wafer 92 is produced instead of a semiconductor wafer 91 with a modified layer formed thereon, and in the processing step, instead of producing a group of semiconductor chips 901 with a support sheet using a semiconductor wafer 91 with a modified layer formed thereon, a group of semiconductor chips 902 with a support sheet is produced using a semi-cut semiconductor wafer 92.

<<Still another example of the method for manufacturing a workpiece>>
Up to this point, we have described a method for manufacturing a workpiece in which the adhering step, heating step, preliminary processing step, processing step, curing step, and pick-up step are performed in this order (manufacturing method (1A) and manufacturing method (1B)). However, the manufacturing method for a workpiece in this embodiment is not limited to these. For example, in the manufacturing method, the order of the heating step, preliminary processing step, and processing step may be reversed. However, since this most clearly demonstrates the effect of the present invention, that is, the cracking of the adhesive layer in the support sheet is suppressed when the support sheet is expanded even after heating at a high temperature, it is preferable to perform at least the heating step before the processing step. An example of a method for manufacturing such a workpiece is a manufacturing method in which the preliminary processing step is performed, and then the heating step and processing step are performed in this order.

Another example 1 of the method for manufacturing a workpiece
<Attachment process>
Among such methods for manufacturing a workpiece, in a manufacturing method in which the semiconductor wafer with the modified layer formed thereon is manufactured in the preliminary processing step (hereinafter, sometimes referred to as "manufacturing method (2A)"), a bonding step is first carried out. The bonding step in manufacturing method (2A) is the same as the bonding step in manufacturing method (1A).

<Preliminary processing step>
After the bonding step in manufacturing method (2A), in the pre-processing step, a modified layer for dividing the semiconductor wafer is formed inside the semiconductor wafer in the semiconductor wafer with support sheet to produce a modified-layer-formed semiconductor wafer, thereby obtaining a pre-processed body with support sheet that includes the semiconductor wafer with modified layer formed and the unheated support sheet. A pre-processed body with support sheet similar to that in manufacturing method (1A) is obtained, except that it has not been heated prior to the pre-processing step.
The preliminary processing step of manufacturing method (2A) may be the same as the preliminary processing step of manufacturing method (1A), except that a semiconductor wafer with a support sheet in which the support sheet (adhesive layer) is unheated is used instead of a semiconductor wafer with a heated support sheet (adhesive layer).

<Heating process>
After the preliminary processing step of the manufacturing method (2A), the pressure-sensitive adhesive layer in the support sheet fixed to the ring frame is heated in the heating step, and a pre-processed body with a support sheet similar to that in the manufacturing method (1A) is obtained by the heating step.
The heating step of manufacturing method (2A) may be the same as the heating step of manufacturing method (1A), except that a pre-processed body with a support sheet in which a modified layer is formed on a semiconductor wafer is used instead of a semiconductor wafer with a support sheet in which a modified layer is not formed on the semiconductor wafer.

In the case of manufacturing method (2A), if the adhesive strength (Y2) of the support sheet is 13,000 mN/25 mm or more, peeling of the pre-processed body with the support sheet from the ring frame is suppressed even when the pre-processed body with the support sheet is heated while fixed to the ring frame in the heating step.

<Processing process>
After the heating step of manufacturing method (2A), in the processing step, the preliminary processed body with the support sheet fixed to the ring frame is expanded in a direction parallel to the surface of the support sheet, thereby dividing the semiconductor wafer with the modified layer formed at the site of the modified layer to produce semiconductor chips. By the processing step, a group of semiconductor chips with the support sheet similar to that in manufacturing method (1A) is obtained.
The processing steps of the production method (2A) may be the same as the processing steps of the production method (1A).

In the case of manufacturing method (2A), by having a storage modulus (E'231) of 1.5 MPa or less in the support sheet, cracking of the adhesive layer in the support sheet is suppressed when the support sheet is expanded in the heating step, even after the support sheet with the semiconductor wafer attached (in other words, the pre-processed body with the support sheet) is heated at a high temperature up to approximately 135°C.

In the case of manufacturing method (2A), when the support sheet has a tan δ peak temperature (P1) of 10°C or less, cracking of the adhesive layer in the support sheet is further suppressed when the support sheet with a semiconductor wafer attached thereto (in other words, the pre-processed body with the support sheet) is expanded, even after heating at a high temperature up to approximately 135°C. Furthermore, when the storage modulus (E'232) is 1.5 MPa or less, or the tan δ peak temperature (P2) is 10°C or less, cracking of the adhesive layer in the support sheet is further suppressed when the support sheet with a semiconductor wafer attached thereto (in other words, the pre-processed body with the support sheet) is expanded, even when the support sheet is expanded without being heated at a high temperature.

In the case of manufacturing method (2A), when the adhesive strength (X2) of the support sheet is 13,000 mN/25 mm or greater, even after the support sheet with the semiconductor wafer attached (in other words, the pre-processed body with support sheet) is heated at a high temperature up to approximately 135°C, peeling of the semiconductor chip from the support sheet (adhesive layer) is suppressed, even if a large force is applied to the semiconductor chip during the processing step, such as by dividing the semiconductor wafer with the modified layer formed thereon (semiconductor wafer) or washing the semiconductor chip with water.

<Curing process>
After the heating step and processing step of manufacturing method (2A), the curing step can be carried out in the same manner as in manufacturing method (1A), and the curing step results in a group of semiconductor chips with a cured support sheet, similar to that in manufacturing method (1A).

In the case of manufacturing method (2A), if the adhesive strength (Y1) of the support sheet is 300 mN/25 mm or greater, the support sheet with the semiconductor wafer attached (in other words, the pre-processed body with support sheet) is heated while fixed to the ring frame in the heating step, and even if energy rays are irradiated to the contact area between the support sheet (adhesive layer) and the ring frame in the curing step, peeling of the group of semiconductor chips with the cured support sheet from the ring frame is suppressed.

<Pickup process>
After the curing step in manufacturing method (2A), the pick-up step can be carried out in the same manner as in manufacturing method (1A), and the target semiconductor chip can be taken out by the pick-up step, in the same manner as in manufacturing method (1A).

In the case of manufacturing method (2A), by setting the adhesive strength (X1) of the support sheet to 400 mN/25 mm or less, the semiconductor chip can be properly picked up from the hardened support sheet even after the support sheet with the semiconductor wafer attached thereto (in other words, the pre-processed body with the support sheet) is heated to a high temperature of up to approximately 135°C in the heating step, resulting in high pickup properties.

<Other processes>
The production method (2A) may include other steps similar to those in the production method (1A).
In the production method (2A), the type of the other step, the number of the other steps, and the timing of performing the other steps can all be selected arbitrarily depending on the purpose, and are not particularly limited.

Another example 2 of the method for manufacturing a workpiece
<Attachment process>
Among the other methods for manufacturing the workpiece described above, a manufacturing method in which the semi-cut semiconductor wafer is produced in the preliminary processing step (hereinafter, sometimes referred to as "manufacturing method (2B)") also first performs a bonding step. The bonding step in manufacturing method (2B) is the same as the bonding step in manufacturing method (1B).

<Preliminary processing step>
After the bonding step in manufacturing method (2B), in the pre-processing step, notches for dividing the semiconductor wafer are formed in a partial region in the thickness direction of the semiconductor wafer in the support sheet-attached semiconductor wafer to produce semi-cut semiconductor wafers, thereby obtaining a pre-processed body with support sheet that includes the semi-cut semiconductor wafer and the unheated support sheet. A pre-processed body with support sheet similar to that in manufacturing method (1B) is obtained, except that it has not been heated prior to the pre-processing step.
The preliminary processing step of manufacturing method (2B) may be the same as the preliminary processing step of manufacturing method (1B), except that a semiconductor wafer with a support sheet in which the support sheet (adhesive layer) is unheated is used instead of a semiconductor wafer with a heated support sheet (adhesive layer).

<Heating process>
After the preliminary processing step of manufacturing method (2B), the pressure-sensitive adhesive layer in the support sheet fixed to the ring frame is heated in the heating step, and a pre-processed body with a support sheet similar to that in manufacturing method (1B) is obtained by the heating step.
The heating step of manufacturing method (2B) may be the same as the heating step of manufacturing method (1B), except that a pre-processed body with a support sheet in which the notch is formed in the semiconductor wafer is used instead of a semiconductor wafer with a support sheet in which the notch is not formed in the semiconductor wafer.

In the case of manufacturing method (2B), if the adhesive strength (Y2) of the support sheet is 13,000 mN/25 mm or more, peeling of the pre-processed body with the support sheet from the ring frame is suppressed even when the pre-processed body with the support sheet is heated while fixed to the ring frame in the heating step.

<Processing process>
After the heating step of manufacturing method (2B), in the processing step, the pre-processed body with the support sheet fixed to the ring frame is expanded in a direction parallel to the surface of the support sheet, thereby dividing the semi-cut semiconductor wafer at the slits to produce semiconductor chips. By the processing step, a group of semiconductor chips with the support sheet similar to that in manufacturing method (1B) is obtained.
The processing steps of the production method (2B) may be the same as the processing steps of the production method (1B).

In the case of manufacturing method (2B), by having a storage modulus (E'231) of 1.5 MPa or less in the support sheet, cracking of the adhesive layer in the support sheet is suppressed when the support sheet is expanded in the heating step, even after the support sheet with the semiconductor wafer attached (in other words, the pre-processed body with the support sheet) is heated at a high temperature up to approximately 135°C.

In the case of manufacturing method (2B), when the support sheet has a tan δ peak temperature (P1) of 10°C or less, cracking of the adhesive layer in the support sheet is further suppressed when the support sheet with a semiconductor wafer attached thereto (in other words, the pre-processed body with the support sheet) is expanded, even after heating at a high temperature up to approximately 135°C. Furthermore, when the storage modulus (E'232) is 1.5 MPa or less, or the tan δ peak temperature (P2) is 10°C or less, cracking of the adhesive layer in the support sheet is further suppressed when the support sheet with a semiconductor wafer attached thereto (in other words, the pre-processed body with the support sheet) is expanded, even when the support sheet is expanded without heating at a high temperature up to approximately 135°C.

In the case of manufacturing method (2B), when the adhesive strength (X2) of the support sheet is 13,000 mN/25 mm or greater, even after the support sheet with the semiconductor wafer attached (in other words, the pre-processed body with support sheet) is heated at a high temperature up to approximately 135°C, peeling of the semiconductor chip from the support sheet (adhesive layer) is suppressed, even if a large force is applied to the semiconductor chip during the processing step, such as when dividing the semi-cut semiconductor wafer (semiconductor wafer) or washing the semiconductor chip with water.

<Curing process>
After the heating step and processing step of manufacturing method (2B), the curing step can be carried out in the same manner as in manufacturing method (1B), and the curing step results in a group of semiconductor chips with a cured support sheet, similar to that in manufacturing method (1B).

In the case of manufacturing method (2B), if the adhesive strength (Y1) of the support sheet is 300 mN/25 mm or greater, the support sheet with the semiconductor wafer attached (in other words, the pre-processed body with support sheet) is heated while fixed to the ring frame in the heating step, and even if energy rays are irradiated to the contact area between the support sheet (adhesive layer) and the ring frame in the curing step, peeling of the group of semiconductor chips with the cured support sheet from the ring frame is suppressed.

<Pickup process>
After the curing step in manufacturing method (2B), the pick-up step can be carried out in the same manner as in manufacturing method (1B), and the target semiconductor chip can be taken out by the pick-up step, in the same manner as in manufacturing method (1B).

In the case of manufacturing method (2B), by setting the adhesive strength (X1) of the support sheet to 400 mN/25 mm or less, the semiconductor chip can be properly picked up from the hardened support sheet even after the support sheet with the semiconductor wafer attached thereto (in other words, the pre-processed body with the support sheet) is heated to a high temperature of up to approximately 135°C in the heating step, resulting in high pickup properties.

<Other processes>
The production method (2B) may include other steps similar to those in the production method (1B).
In the production method (2B), the type of the other step, the number of the other steps, and the timing of performing the other steps can all be selected arbitrarily depending on the purpose, and are not particularly limited.

◇How to pick up the workpiece (how to use the support sheet)
The support sheet can be used to pick up a workpiece.
That is, a method for picking up workpieces according to one embodiment of the present invention includes the support sheet and a workpiece group formed by arranging a plurality of workpieces produced by dividing a workpiece on the surface of the adhesive layer in the support sheet opposite the substrate side, the workpiece group including the support sheet, the adhesive layer being attached to a ring frame to fix the workpiece group with the support sheet to the ring frame; a heating process after the attaching process for heating the workpiece group with the support sheet fixed to the ring frame; an expanding process after the attaching process for expanding the workpiece group with the support sheet fixed to the ring frame in a direction parallel to the surface of the support sheet, thereby increasing the distance between adjacent workpieces in the workpiece group; a curing process after the heating process and the expanding process for curing the adhesive layer attached to the ring frame with energy rays; and a picking up process after the curing process for separating the workpieces from the cured adhesive layer and picking them up.

A method for picking up a workpiece when the workpiece is a semiconductor wafer, i.e., a method for picking up semiconductor chips, includes a support sheet and a semiconductor chip group formed by arranging a plurality of semiconductor chips produced by dividing a semiconductor wafer on the surface of the adhesive layer in the support sheet opposite the substrate side, the adhesive layer being attached to a ring frame to fix the semiconductor chip group with the support sheet to the ring frame; and a method for picking up the semiconductor chip group with the support sheet fixed to the ring frame after the attachment step. an expanding step, after the attaching step, of expanding the semiconductor chip group with the support sheet fixed to the ring frame in a direction parallel to the surface of the support sheet to increase the distance between adjacent semiconductor chips in the semiconductor chip group; a curing step, after the heating step and the expanding step, of curing the adhesive layer attached to the ring frame with energy rays; and a pick-up step, after the curing step, of separating the semiconductor chip from the cured product of the adhesive layer and picking it up.

The order in which the heating and expanding steps are performed after the attaching step can be selected as desired depending on the purpose. The heating step may be performed before the expanding step, or the expanding step may be performed before the heating step. For example, in the pickup method, a heating step may be performed to remove foreign matter, such as low-molecular-weight resin components, adhering to the surface of the workpiece group by volatilization. In this case, the heating step may be performed either before or after the expanding step. In addition, in the pickup method, a heating step may be performed to dry the workpiece group after washing and removing fine foreign matter adhering to the surface of the workpiece group with water. In this case, the heating step may also be performed either before or after the expanding step. In the manufacturing method, the heating step for removing the foreign matter and the heating step for drying may be performed together, or these heating steps may be performed simultaneously.

<<Example of how to pick up a workpiece>>
4 is a cross-sectional view for explaining an example of the pickup method when the workpiece is a semiconductor wafer (i.e., the workpiece is a semiconductor chip). Here, the pickup method will be explained using the support sheet 1 shown in FIG.

<Attachment process>
4(a), the attachment step of the pickup method uses a support sheet-attached semiconductor chip group 903, which includes a support sheet 1 and a semiconductor chip group 903 configured by arranging a plurality of semiconductor chips 90 produced by dividing a semiconductor wafer on a surface 12a of the adhesive layer 12 in the support sheet 1 opposite the substrate 11. The adhesive layer 12 in the support sheet 1 (more specifically, the surface 12a of the adhesive layer 12 in the semiconductor chip group 903) is attached to a ring frame 8, thereby fixing the semiconductor chip group 903 to the ring frame 8. Note that the adhesive layer 12 in the semiconductor chip group 903 with support sheet has an area surrounding the semiconductor chip group attached to the ring frame 8. The semiconductor chip group 903 with support sheet is a group of workpieces with the support sheet.
Bumps and the like on the circuit surface 90a of the semiconductor chip 90 are not shown.

The adhesive layer 12 (support sheet 1) in the semiconductor chip group 903 with support sheet can be attached to the ring frame 8, for example, in the same manner as the support sheet 1 (adhesive layer 12) in the attachment step of the above-mentioned manufacturing method (1A).

The semiconductor chip group 903 with a support sheet can be manufactured by a known method. For example, a semiconductor wafer similar to the semiconductor wafer 9 shown in FIG. 2(a) or 3(a) is used, and a resin film such as backgrind tape is attached to its circuit surface (circuit surface 9a in the semiconductor wafer 9). The semiconductor wafer is then divided to produce a semiconductor chip group with a resin film, in which multiple semiconductor chips 90 are aligned and held on the resin film. Next, the adhesive layer 12 in the support sheet 1 is attached to the back surfaces 90b of all aligned semiconductor chips 90 in the semiconductor chip group with a resin film. This results in a semiconductor chip group 903 with a support sheet and a resin film.
In the attachment step, the resin film is removed from the semiconductor chip group 903 (more specifically, from the circuit surfaces 90a of all aligned semiconductor chips 90) and the surface 12a of the adhesive layer 12 opposite to the substrate 11 is attached to the ring frame 8. This allows the semiconductor chip group 903 with the support sheet to be fixed to the ring frame 8, as shown in FIG.

The semiconductor wafer on the resin film can be divided using known methods. For example, a so-called half cut is performed, in which a groove is formed by cutting a notch in the semiconductor wafer from the circuit surface of the semiconductor wafer before the resin film is applied to the back surface, up to a region halfway through the thickness of the semiconductor wafer. Next, the resin film is attached to the circuit surface of the semiconductor wafer after the groove is formed, and the back surface of the semiconductor wafer is ground until the ground surface (back surface) reaches the bottom of the groove (notch), thereby dividing the semiconductor wafer at the notch. This divides the semiconductor wafer, yielding a group of semiconductor chips with a resin film.

<Heating process>
After the attachment step of the pickup method, in the heating step, the adhesive layer 12 in the semiconductor chip group 903 with support sheet fixed to the ring frame 8 is heated, as shown in Figure 4(b). In this case, the heating of the adhesive layer 12 is accompanied by heating of the entire semiconductor chip group 903 with support sheet, and this heating can remove, by volatilization, foreign matter such as low-molecular-weight resin components adhering to the surface (e.g., circuit surface 90a) of the semiconductor chip 90. Furthermore, this heating can wash and remove foreign matter adhering to the surface of the semiconductor chip 90 with water, and then dry the semiconductor chip 90 (semiconductor chip group).

In the heating step of the pickup method, the adhesive layer 12 (i.e., the adhesive layer 12 in the semiconductor chip group 903 with support sheet) can be heated, for example, in the same manner as the adhesive layer 12 in the heating step of the above-mentioned manufacturing method (1A) (i.e., the adhesive layer 12 in the semiconductor wafer 109 with support sheet).

When the adhesive strength (Y2) of the support sheet 1 is 13,000 mN/25 mm or more, peeling of the semiconductor chip group 903 with the support sheet from the ring frame 8 is suppressed even when the semiconductor chip group 903 with the support sheet is heated while fixed to the ring frame 8 during the heating process.

<Expanding process>
After the bonding step and heating step of the pickup method, in the expanding step, as shown in FIG. 4(c), the semiconductor chip group 903 with support sheet fixed to the ring frame 8 is expanded in a direction parallel to the surface (one surface 1a) of the support sheet 1. In FIG. 4(c), the direction of this expansion is indicated by arrow I. This increases the distance (kerf width) between adjacent semiconductor chips 90 in the semiconductor chip group 903 with support sheet. The distance _W1 between adjacent semiconductor chips 90 before the expanding step shown in FIG. 4(a) and the distance _W2 between adjacent semiconductor chips 90 after the expanding step shown in FIG. 4(c) satisfy the relationship _W2 > _W1 .

When the semiconductor chip group 903 with support sheet is expanded, if necessary, a fixing jig (e.g., a grip ring manufactured by Technovision) may be attached to the expanded support sheet 1 to fix the expanded support sheet 1. Alternatively, after expanding the support sheet 1 using a heat-shrinkable base material 11, the heat-shrinkable properties of the base material 11 may be used to remove slack in the support sheet 1, and the support sheet 1 may be fixed in its expanded state without attaching a fixing jig.

In the expanding step of the pickup method, the semiconductor chip group 903 with support sheet (support sheet 1) can be expanded, for example, in the same manner as in the case of the pre-processed body 911A with support sheet (support sheet 1) in the processing step of the above-mentioned manufacturing method (1A).

By having a storage modulus (E'231) of 1.5 MPa or less in the support sheet 1, cracking of the adhesive layer 12 in the support sheet 1 is suppressed when the support sheet 1 is expanded, even after the support sheet 1 with the semiconductor chips 90 attached thereto (in other words, the group of semiconductor chips 903 with the support sheet) is heated at a high temperature up to approximately 135°C in the heating step of the pickup method.

For example, when the tan δ peak temperature (P1) of the support sheet 1 is 10°C or less, cracking of the adhesive layer 12 in the support sheet 1 is further suppressed when the support sheet 1 is expanded, even after the support sheet 1 with the semiconductor chips 90 attached thereto (in other words, the group of semiconductor chips 903 with the support sheet) is heated at a high temperature.

For example, if the storage modulus (E'232) of the support sheet 1 is 1.5 MPa or less, cracking of the adhesive layer 12 in the support sheet 1 is further suppressed when the support sheet 1 is expanded, even if the support sheet 1 with the semiconductor chips 90 attached (in other words, the group of semiconductor chips 903 with the support sheet) is not heated at a high temperature.

For example, when the tan δ peak temperature (P2) of the support sheet 1 is 10°C or less, cracking of the adhesive layer 12 in the support sheet 1 is further suppressed when the support sheet 1 is expanded, even if the support sheet 1 with the semiconductor chips 90 attached (in other words, the group of semiconductor chips 903 with the support sheet) is not heated at a high temperature.

When the adhesive strength (X2) of the support sheet 1 is 13,000 mN/25 mm or greater, even after the support sheet 1 with the semiconductor chips 90 attached (in other words, the group of semiconductor chips 903 with the support sheet) is heated at a high temperature up to approximately 135°C in the heating step of the pickup method, and even if a large force is applied to the semiconductor chips 90 in the expanding step, peeling of the semiconductor chips 90 from the support sheet 1 (adhesive layer 12) is suppressed.

<Curing process>
After the heating step and the expanding step of the pickup method, in the curing step, the adhesive layer 12 attached to the ring frame 8 is cured with energy rays, as shown in Fig. 4(d) . The curing step provides a group of semiconductor chips 903' with a cured support sheet, in which a plurality of semiconductor chips 90 are aligned and held on a single cured support sheet 1'.
The support sheet 1 becomes a cured support sheet 1' when the pressure-sensitive adhesive layer 12 is cured with energy rays to become an energy ray-cured product 12'.
The group of semiconductor chips with cured support sheet 903' is a laminate of the workpiece and the cured support sheet (in other words, a workpiece with a cured support sheet) as described above.

In the curing step of the pickup method, the adhesive layer 12 can be cured with energy rays, for example, in the same manner as the adhesive layer 12 in the curing step of the above-mentioned manufacturing method (1A).

When the adhesive strength (Y1) of the support sheet 1 is 300 mN/25 mm or more, the semiconductor chip group 903 with the support sheet is heated while fixed to the ring frame 8 during the heating step of the pickup method, and even if the contact portion of the support sheet 1 (adhesive layer 12) with the ring frame 8 is irradiated with energy rays during the curing step, peeling of the cured semiconductor chip group 903' with the support sheet from the ring frame 8 is suppressed.

<Pickup process>
In the pickup step after the curing step of the pickup method, the semiconductor chip 90 can be removed from the group of semiconductor chips 903' with the cured support sheet by detaching and picking up the semiconductor chip 90 from the energy ray-cured product 12' of the pressure-sensitive adhesive layer in the cured support sheet 1', as shown in Figure 4(e). Here, the pickup direction is indicated by arrow P.

In the pick-up step of the pick-up method, the semiconductor chip 90 can be picked up from the energy ray-cured product 12' of the adhesive layer, for example, in the same manner as in the case of the semiconductor chip 90 in the pick-up step of the above-mentioned manufacturing method (1A). The manner in which the semiconductor chip 90 is detached from the energy ray-cured product 12' of the adhesive layer and picked up is the same as in the pick-up step of the above-mentioned manufacturing method (1A).

When the adhesive strength (X1) of the support sheet 1 is 400 mN/25 mm or less, the support sheet 1 with the semiconductor chips 90 attached (in other words, the group of semiconductor chips 903 with the support sheet) is heated to a high temperature of approximately 135°C in the heating step of the pickup method, and the semiconductor chips 90 can be picked up normally from the cured support sheet 1', resulting in high pickup properties.

<Other processes>
The pick-up method may include another step that does not fall under any of the adhering step, the heating step, the expanding step, the curing step, and the pick-up step.
The type of the other step, the number of the other steps, and the timing of performing the other steps can all be selected arbitrarily depending on the purpose, and are not particularly limited.

<<Another example of how to pick up a workpiece>>
Up to this point, the workpiece pickup method has been described as a pickup method in which the adhering step, heating step, expanding step, curing step, and pickup step are performed in this order, but the workpiece pickup method of this embodiment is not limited to this. For example, in the pickup method, the heating step and the expanding step may be performed in the reverse order. However, it is preferable to perform the heating step before the expanding step, because this is the most effective way of suppressing cracking of the adhesive layer in the support sheet when the support sheet is expanded, even after the support sheet has been heated at a high temperature.

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

<Raw materials for resin production>
The full names of the raw materials for producing the resins, which are abbreviated in the examples and comparative examples, are shown below.
2EHA: 2-ethylhexyl acrylate 2EHMA: 2-ethylhexyl methacrylate HEA: 2-hydroxyethyl acrylate HEMA: 2-hydroxyethyl methacrylate MOI: 2-methacryloyloxyethyl isocyanate

<Materials for producing pressure-sensitive adhesive composition (I)>
In the present Examples and Comparative Examples, the raw materials used in producing the pressure-sensitive adhesive composition (I) are shown below.
The viscosity of the four types of crosslinking agents (β) at 23° C. was measured using a digital rotational viscometer "Viscoride Advance" manufactured by Viscotec.
[Energy ray-curable compound (α)]
(α)-1: 2-(2-phenoxyethoxy)ethyl acrylate, "AMP-20GY" manufactured by Shin-Nakamura Chemical Co., Ltd., viscosity at 23°C: 18 mPa·s, molecular weight: 236.1
(α)-2: "R-684" manufactured by Nippon Kayaku Co., Ltd., viscosity at 23°C: 180 mPa s, molecular weight: 304.4
(α)-3: (2-(1-(acryloyloxy)-2-methylpropan-2-yl)-5-ethyl-1,3-dioxan-5-yl)methyl acrylate, "A-DOG" manufactured by Shin-Nakamura Chemical Co., Ltd., viscosity at 23°C: 310 mPa s, molecular weight: 326.4)
[Crosslinking agent (β)]
(β)-1:1,6-Hexamethylene diisocyanate trimethylolpropane adduct ("Coronate HL" manufactured by Tosoh Corporation)
(β)-2: Isocyanurate-modified hexamethylene diisocyanate ("Coronate HX" manufactured by Tosoh Corporation)
[Photopolymerization initiator (γ)]
(γ)-1: 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one (Omnirad (registered trademark) 127, manufactured by IGM Resins)

The energy ray-curable compounds (α)-1 and (α)-3 are both acrylic acid esters having a substituent. In the energy ray-curable compound (α)-1, the hydrocarbon group derived from an alcohol has two substituents, and the hydrocarbon group has 12 carbon atoms. In the energy ray-curable compound (α)-3, the hydrocarbon group derived from an alcohol has two substituents, and the hydrocarbon group has 13 carbon atoms.
On the other hand, the energy ray-curable compound (α)-2 is an acrylic acid ester having no substituent. In the energy ray-curable compound (α)-2, the hydrocarbon group derived from alcohol has 12 carbon atoms.

[Example 1]
<<Manufacture of support sheet>>
<Production of Energy Ray-Curable Acrylic Resin (Ia)>
An MOI was added to acrylic polymer (1), and an addition reaction was carried out in an air stream at 50°C for 48 hours to obtain energy ray-curable acrylic resin (Ia)-1. The acrylic polymer (1) was a copolymer of 2EHA (35 parts by mass), 2EHMA (45 parts by mass), and HEMA (20 parts by mass). The amount of MOI used was such that the total number of moles of isocyanate groups in the MOI was 0.95 times the total number of moles of hydroxyl groups derived from HEMA in the acrylic polymer (1). The resulting energy ray-curable acrylic resin (Ia)-1 had a weight average molecular weight of 440,000 and a glass transition temperature of -26°C.

<Production of Pressure-Sensitive Adhesive Composition (I)>
An energy ray-curable pressure-sensitive adhesive composition (I)-1 was prepared containing an energy ray-curable acrylic resin (Ia)-1 (100 parts by mass), an energy ray-curable compound (α)-1 (15 parts by mass), a crosslinking agent (β)-1 (1.17 parts by mass), and a photopolymerization initiator (γ)-1 (3 parts by mass), and further containing methyl ethyl ketone as a solvent, with the total concentration of all components other than the solvent being 25% by mass. Note that the contents of all components other than methyl ethyl ketone shown here are the contents of the target product excluding the solvent.

<Formation of Pressure-Sensitive Adhesive Layer>
A release film (second release film) was used, one side of which was a polyethylene terephthalate film treated with silicone for release, and the pressure-sensitive adhesive composition (I)-1 obtained above was applied to the release-treated surface, followed by heating and drying at 100°C for 2 minutes to form an energy ray-curable pressure-sensitive adhesive layer having a thickness of 15 μm, giving a pressure-sensitive adhesive layer with a release film.

<Production of Support Sheet>
Next, at room temperature, a polypropylene film (manufactured by Diaplus Film Co., Ltd., thickness 80 μm) was attached as a substrate to the exposed surface of the pressure-sensitive adhesive layer at a bonding speed of 5 m/min and a pressure of 0.4 MPa. One side of this polypropylene film was a matte surface with a surface roughness (Ra) of 0.90 μm, and the other side was a slightly matte surface with a surface roughness (Ra) of 0.12 μm, and the pressure-sensitive adhesive layer was attached to the matte surface of this polypropylene film.
In this way, the desired support sheet was obtained.

<<Evaluation of Support Sheet>>
<Evaluation of the effect of suppressing cracking of the pressure-sensitive adhesive layer when the support sheet is expanded after heating>
(Silicon chip manufacturing)
An 8-inch silicon wafer (300 μm thick) with one side polished to #2000 was prepared. A region of the adhesive layer in the support sheet obtained above, closer to the center in the width direction, was attached to the silicon wafer, and a region surrounding the attachment region to the silicon wafer was attached to a ring frame. The adhesive layer was attached to the silicon wafer and ring frame at a temperature of 23°C (laminating roller temperature 23°C, silicon wafer temperature 23°C) at a bonding speed of 300 mm/min. This resulted in a silicon wafer with a support sheet, comprising a silicon wafer and a support sheet provided on one side of the silicon wafer, being fixed to the ring frame (bonding process).
Next, the silicon wafer with the support sheet fixed to the ring frame was placed in an oven and heated at 130° C. for 2 hours (heating step).
Next, the silicon wafer with the support sheet fixed to the ring frame was removed from the oven and allowed to cool to 23° C. Then, using a laser saw (DISCO Corporation, "DFL7360"), the silicon wafer was irradiated with laser light having a wavelength of 1064 nm from the outside, opposite the support sheet side, to form a mesh-like modified layer measuring 6 mm × 6 mm inside the silicon wafer (preliminary processing step).
Next, using a die separator ("DDS2300" manufactured by Disco Corporation), the silicon wafer with the support sheet was pushed up from the support sheet side under conditions of a temperature of 23°C, a table push-up speed of 200 mm/s, a table push-up height of 15 mm, and a table push-up hold (expand) time of 1 minute, thereby expanding the silicon wafer with the support sheet in a direction parallel to the surfaces of the silicon wafer and the support sheet, and the silicon wafer with the modified layer formed on the support sheet was divided at the site of the modified layer to produce multiple silicon chips measuring 6 mm x 6 mm (processing step).
In this manner, a group of silicon chips with a support sheet was produced, in which a plurality of silicon chips were aligned and held on a single support sheet.

(Evaluation of crack suppression effect of adhesive layer)
Of the silicon chip groups with support sheets, five regions were defined as observation regions: a central region including the center of the silicon chip group and four peripheral regions near the periphery of the silicon chip group equidistant from the center. The four peripheral regions were positioned so that when a line segment was connected between one peripheral region and another peripheral region furthest from the center, and a line segment was connected between the remaining two peripheral regions, both of these lines passed through the center and intersected perpendicularly. The presence or absence of cracks in the adhesive layer was observed using an optical microscope (KEYENCE Corporation's "VHX-7000"), and the crack suppression effect of the adhesive layer was evaluated according to the following criteria. Each of the five observation areas measured approximately 36 mm x 36 mm, and contained six silicon chips in each of two mutually perpendicular directions. The exposed surfaces of the adhesive layer between the silicon chips, in other words, five adhesive layer lines in each of the two mutually perpendicular directions, were observed using the optical microscope to determine whether or not the adhesive layer had cracks. The results are shown in Table 1.
(Evaluation criteria)
A: No cracks in the adhesive layer were observed in any of the five regions.
B: Cracks in the pressure-sensitive adhesive layer were observed in at least one of the five regions.

<Measurement of storage modulus (E'231) of second test piece of pressure-sensitive adhesive layer>
The 14 pressure-sensitive adhesive layers with release films obtained above (the pressure-sensitive adhesive layers corresponded to the first test pieces) were heated at 130°C for 2 hours and then allowed to cool to 23°C. Next, using these heated pressure-sensitive adhesive layers with release films, the exposed surfaces of the heated pressure-sensitive adhesive layers were sequentially bonded together while removing the release films, thereby producing a laminate with a thickness of 210 μm. Furthermore, a 4 mm wide piece was cut from the laminate, and this was used as the second test piece.
Next, the storage modulus E' of the second test piece was measured by a tensile method (tensile mode) using an automatic dynamic viscoelasticity measuring device ("Rheovibron DDV-01FP" manufactured by A&D Co., Ltd.) in a temperature range from -20°C to 150°C under the measurement conditions of a chuck distance of 20 mm, a frequency of 11 Hz, a temperature rise rate of 3°C/min, and a uniform temperature rise. Of these, the storage modulus (E'231) is shown in Table 1.

<Measurement of peak temperature (P1) of tan δ of second test piece of pressure-sensitive adhesive layer>
When the storage modulus (E'231) of the second test piece was measured, the peak temperature (P1) of tan δ of the second test piece was also measured. The results are shown in Table 1.

<Measurement of storage modulus (E'232) of third test piece of pressure-sensitive adhesive layer>
Using the 14 adhesive layers with release films obtained above (the adhesive layers correspond to the first test pieces), the exposed surfaces of the unheated adhesive layers were sequentially bonded together while removing the release films, thereby producing a third test piece with a thickness of 210 μm.
The storage modulus E' of the third test piece was measured in the same manner as in the case of the storage modulus (E'231), except that the third test piece was used instead of the second test piece. Among them, the storage modulus (E'232) is shown in Table 1.

<Measurement of peak temperature (P2) of tan δ of second test piece of pressure-sensitive adhesive layer>
When the storage modulus (E'232) of the second test piece was measured, the peak temperature (P2) of tan δ of the second test piece was also measured. The results are shown in Table 1.

<Measurement of adhesive strength (X1) between the energy ray-cured adhesive layer after heating and the silicon mirror wafer>
A test piece having a width of 25 mm was cut out from the support sheet obtained above.
The test piece was attached to the mirror surface of a silicon mirror wafer (thickness 650 nm) with the adhesive layer therein at a bonding temperature of 23°C (laminating roller temperature 23°C, silicon mirror wafer temperature 23°C), a bonding speed of 300 mm/min, and a bonding pressure of 0.3 MPa to obtain a silicon mirror wafer with the test piece attached. This silicon mirror wafer with the test piece attached was placed in an oven adjusted to 130°C and heated at this temperature (130°C) for 2 hours.
The silicon mirror wafer with the test piece attached was then removed from the oven and allowed to cool to a temperature of 23° C. Then, using an ultraviolet irradiation device ("RAD-2000UV" manufactured by Lintec Corporation), ultraviolet light was irradiated through the substrate onto the adhesive layer in the removed silicon mirror wafer with the test piece attached under conditions of an illuminance of 230 mW/cm ² and a light quantity of 200 mJ/cm ² , thereby UV-curing the adhesive layer in the test piece.

Next, the test piece was peeled from the silicon mirror wafer at a peeling rate of 300 mm/min in an environment of 23°C. The test piece was peeled in its length direction so that the surface of the silicon mirror wafer to which the test piece had been attached formed an angle of 180° with the surface of the test piece to which the silicon mirror wafer had been attached (a 180° peel was performed). The load (peel force) during this 180° peel was measured, and the measurement length was set to 50 mm. The measurement values for the first 5 mm and the last 5 mm were excluded from the valid value. The average of these measurements was used as the adhesive strength (mN/25 mm).
The adhesive strength was measured twice, and the average value was used as the adhesive strength (X1) (mN/25 mm) between the energy ray-cured adhesive layer and the silicon mirror wafer after heating. The results are shown in Table 1.

<Measurement of adhesive strength (X2) between adhesive layer and silicon mirror wafer after heating>
A silicon mirror wafer with a test piece was prepared in the same manner as in the measurement of the adhesive strength (X1) above, heated at 130°C for 2 hours, and then allowed to cool to a temperature of 23°C.
Next, the test piece was peeled from the cooled silicon mirror wafer at a peeling rate of 300 mm/min in an environment of 23°C. The test piece was peeled in its length direction so that the surface of the silicon mirror wafer to which the test piece had been attached formed an angle of 180° with the surface of the test piece to which the silicon mirror wafer had been attached (a 180° peel was performed). The load (peel force) during this 180° peel was measured, and the measurement length was set to 50 mm. The measurement values for the first 5 mm and the last 5 mm were excluded from the valid value. The average of these measurements was used as the adhesive strength (mN/25 mm).
The adhesive strength was measured twice, and the average value was used as the adhesive strength (X2) (mN/25 mm) between the adhesive layer and the silicon mirror wafer after heating. The results are shown in Table 1.

<Measurement of adhesive strength (Y1) between the energy ray-cured pressure-sensitive adhesive layer after heating and the SUS plate>
A SUS plate with a test piece was obtained in the same manner as in measuring the adhesive strength (X1) above, except that the test piece was attached to the #1200 polished surface of a SUS plate (manufactured by Paltec Co., Ltd., "SUS304 #1200HL, thickness 1000 μm, size 70 mm × 150 mm") instead of the mirror surface of the silicon mirror wafer.
Next, this SUS plate with the test piece was heated at 130°C for 2 hours in the same manner as in the case of the silicon mirror wafer with the test piece when measuring the adhesive strength (X1) above, and then allowed to cool until the temperature reached 23°C. The adhesive layer in the SUS plate with the test piece was then irradiated with ultraviolet light through the substrate, thereby curing the adhesive layer in the test piece with ultraviolet light.

Next, the test piece was peeled from the SUS plate at a peel rate of 300 mm/min in an environment of 23°C. The test piece was peeled in its length direction so that the surface of the SUS plate to which the test piece had been attached formed an angle of 180° with the surface of the test piece to which the SUS plate had been attached (180° peeling was performed). The load (peel force) at this 180° peeling was measured, and the measurement length was set to 50 mm. The measurement values at the first 5 mm and the last 5 mm were excluded from the effective value. The average of these measurements was used as the adhesive strength (mN/25 mm).
The adhesive strength was measured twice, and the average value was used as the adhesive strength (Y1) (mN/25 mm) between the energy ray-cured adhesive layer and the SUS plate after heating. The results are shown in Table 1.

<Measurement of adhesive strength (Y2) between pressure-sensitive adhesive layer and SUS plate after heating>
A SUS plate with a test piece was prepared in the same manner as in the measurement of the adhesive strength (Y1) above, heated at 130°C for 2 hours, and then allowed to cool to a temperature of 23°C.
Next, the test piece was peeled from the cooled SUS plate at a peel rate of 300 mm/min in an environment of 23°C. The test piece was peeled in its length direction so that the surface of the SUS plate to which the test piece had been attached formed an angle of 180° with the surface of the test piece to which the SUS plate had been attached (180° peeling was performed). The load (peel force) at this 180° peeling was measured, and the measurement length was set to 50 mm. The measurement values at the first 5 mm and the last 5 mm were excluded from the effective value. The average of these measurements was used as the adhesive strength (mN/25 mm).
The adhesive strength was measured twice, and the average value was used as the adhesive strength (Y2) (mN/25 mm) between the adhesive layer and the SUS plate after heating. The results are shown in Table 1.

<Calculation of the average light transmittance (400 to 800 nm) of the support sheet>
Using a UV-vis measurement device (Shimadzu Corporation, "UV-vis-NIR3600"), the support sheet obtained above was irradiated with light from the outside of the substrate side, and the light transmittance was measured by direct light reception without using an integrating sphere. The wavelength range of the measurement was 190 to 2000 nm. The light transmittance values were then summed up every 1 nm in the wavelength range of 400 to 800 nm in the visible light region, and the sum was divided by the number of summed light transmittance values (i.e., 800 - 400 + 1 = 401) to calculate the average light transmittance (400 to 800 nm) of the support sheet (%). The results are shown in Table 1.

<Evaluation of silicon chip pickup ability of support sheet>
(Manufacturing silicon chip groups with support sheets)
A group of silicon chips with a support sheet was prepared in the same manner as in the above "Evaluation of the effect of suppressing cracking of the adhesive layer," except that the size of the silicon chips was changed from 6 mm x 6 mm to 3 mm x 3 mm. In this group, multiple silicon chips each measuring 3 mm x 3 mm were aligned and held on a single support sheet.

(Evaluation of silicon chip pick-up ability of support sheet)
Next, using an ultraviolet irradiation device ("RAD-2000UV" manufactured by Lintec Corporation), ultraviolet light was irradiated onto the adhesive layer in the group of silicon chips with support sheet from the outside of the substrate side through the substrate at an illuminance of 230 mW/ ^cm2 and a light quantity of 200 mJ/ ^cm2 , thereby ultraviolet-curing the adhesive layer attached to the ring frame (curing process).
Next, using a pickup die bonding device (Canon Machinery's "BESTEM D-510"), the silicon chips in the group of silicon chips with the cured support sheet were picked up by separating them from the cured product of the adhesive layer under the following pickup conditions (pickup process). This pickup was performed on a total of 100 silicon chips in the group of silicon chips with the cured support sheet, in 10 rows in two orthogonal directions divided from the center and the area nearby the center of the silicon wafer before dicing, and one silicon chip was pushed up from the support sheet side with a single pin. The pickup properties of the support sheet were then evaluated according to the following criteria. The results are shown in Table 1.
(Pickup conditions)
Push-up speed: 5 mm/s
Expanded amount: 4 mm
Curvature radius of the pin tip: 0.75 mm
(Evaluation criteria)
A: All (100) silicon chips were picked up normally.
B: 1 to 4 silicon chips could not be picked up normally, but all the other silicon chips (96 to 99) could be picked up normally.
C: Five or more silicon chips could not be picked up normally.

[Example 2]
<<Production and Evaluation of Support Sheet>>
An energy ray-curable pressure-sensitive adhesive composition (I)-2 was prepared, which had the same composition as in Example 1, except that it contained energy ray-curable compound (α)-3 (10 parts by mass) instead of energy ray-curable compound (α)-1 (15 parts by mass) and that the content of crosslinking agent (β)-1 was 1.33 parts by mass instead of 1.17 parts by mass. Then, a support sheet was produced and evaluated in the same manner as in Example 1, except that this pressure-sensitive adhesive composition (I)-2 was used instead of pressure-sensitive adhesive composition (I)-1. The results are shown in Table 1.

[Example 3]
<<Production and Evaluation of Support Sheet>>
An energy ray-curable pressure-sensitive adhesive composition (I)-3 was prepared, which had the same composition as in Example 1, except that it contained energy ray-curable compound (α)-2 (10 parts by mass) instead of energy ray-curable compound (α)-1 (15 parts by mass) and that the content of crosslinking agent (β)-1 was 1.33 parts by mass instead of 1.17 parts by mass. Then, a support sheet was produced and evaluated in the same manner as in Example 1, except that this pressure-sensitive adhesive composition (I)-3 was used instead of pressure-sensitive adhesive composition (I)-1. The results are shown in Table 1.

[Example 4]
<<Manufacture of support sheet>>
<Production of Energy Ray-Curable Acrylic Resin (Ia)>
An MOI was added to the acrylic polymer (1), and an addition reaction was carried out in an air stream at 50°C for 48 hours to obtain an energy ray-curable acrylic resin (Ia)-2. The amount of MOI used was such that the total number of moles of isocyanate groups in the MOI was 0.785 times the total number of moles of hydroxyl groups derived from HEMA in the acrylic polymer (1). The resulting energy ray-curable acrylic resin (Ia)-2 had a weight average molecular weight of 500,000 and a glass transition temperature of -26°C.

<Production of Pressure-Sensitive Adhesive Composition (I)>
An energy ray-curable pressure-sensitive adhesive composition (I)-4 was prepared containing energy ray-curable acrylic resin (Ia)-2 (100 parts by mass), energy ray-curable compound (α)-1 (25 parts by mass), crosslinking agent (β)-2 (4.12 parts by mass), and photopolymerization initiator (γ)-1 (3 parts by mass), and further containing methyl ethyl ketone as a solvent, with the total concentration of all components other than the solvent being 25% by mass. Note that the contents of all components other than methyl ethyl ketone shown here are the contents of the target product excluding the solvent.

<Production of Support Sheet>
A support sheet was produced in the same manner as in Example 1, except that this adhesive composition (I)-4 was used instead of the adhesive composition (I)-1.

<<Evaluation of Support Sheet>>
The support sheet obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
<<Manufacture of support sheet>>
<Production of Pressure-Sensitive Adhesive Composition>
An energy ray-curable pressure-sensitive adhesive composition (R)-1 was prepared containing an energy ray-curable acrylic resin (Ia)-1 (100 parts by mass), a crosslinking agent (β)-1 (0.53 parts by mass), and a photopolymerization initiator (γ)-1 (3 parts by mass), and further containing methyl ethyl ketone as a solvent, with the total concentration of all components other than the solvent being 25% by mass. Note that the contents of all components other than methyl ethyl ketone shown here are the contents of the target product excluding the solvent.

<Production of Support Sheet>
A support sheet was produced in the same manner as in Example 1, except that this adhesive composition (R)-1 was used instead of the adhesive composition (I)-1.

<<Evaluation of Support Sheet>>
The support sheet obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
<<Manufacture of support sheet>>
<Production of Energy Ray-Curable Acrylic Resin (Ia)>
An MOI was added to acrylic polymer (2), and an addition reaction was carried out in an air stream at 50°C for 48 hours to obtain energy ray-curable acrylic resin (Ia)-3. The acrylic polymer (2) was a copolymer of 2EHA (35 parts by mass), 2EHMA (45 parts by mass), and HEA (20 parts by mass). The amount of MOI used was such that the total number of moles of isocyanate groups in the MOI was 0.7 times the total number of moles of hydroxyl groups derived from HEA in the acrylic polymer (2). The weight-average molecular weight of the obtained energy ray-curable acrylic resin (Ia)-3 was 880,000, and the glass transition temperature was -35°C.

<Production of Pressure-Sensitive Adhesive Composition>
An energy ray-curable pressure-sensitive adhesive composition (R)-2 was prepared containing an energy ray-curable acrylic resin (Ia)-3 (100 parts by mass), a crosslinking agent (β)-1 (9.26 parts by mass), and a photopolymerization initiator (γ)-1 (3 parts by mass), and further containing methyl ethyl ketone as a solvent, with the total concentration of all components other than the solvent being 25% by mass. Note that the contents of all components other than methyl ethyl ketone shown here are the contents of the target product excluding the solvent.

<Production of Support Sheet>
A support sheet was produced in the same manner as in Example 1, except that this adhesive composition (R)-2 was used instead of the adhesive composition (I)-1.

<<Evaluation of Support Sheet>>
The support sheet obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 1.

As is clear from the above results, in Examples 1 to 4, the storage modulus (E'231) was 1 MPa or less, and even after the support sheet with the silicon wafer attached was heated at 130°C for 2 hours, cracking of the adhesive layer in the support sheet was suppressed when the support sheet was expanded. In particular, in Examples 1 and 4, the storage modulus (E'231) was 0.76 MPa or less, and cracking of the adhesive layer was suppressed, thereby exhibiting particularly excellent properties.

In Examples 1 to 4, the tan δ peak temperature (P1) was 11.6°C or less, and in particular, in Examples 1 and 4, the tan δ peak temperature was 1.3°C or less.

In addition, in Examples 1 to 4, the adhesive strength (X1) was 350 mN/25 mm or less, and even after the support sheet with the silicon mirror wafer attached was heated at 130°C for two hours, almost all of the silicon chips were successfully picked up, demonstrating high pickup performance. In particular, in Examples 1 to 3, the adhesive strength (X1) was 200 mN/25 mm or less, demonstrating even higher pickup performance.

As such, the support sheets of Examples 1 to 4 had the desired properties.

In Examples 1 to 4, the pressure-sensitive adhesive composition (I) contained an energy ray-curable acrylic resin (Ia) and an energy ray-curable compound (α), and it was presumed that the above-mentioned properties were easily achieved. In particular, it was presumed that the energy ray-curable compound (α) had a structure within a specific range, which made it even easier to achieve the above-mentioned properties.

Furthermore, in Examples 1 to 4, the storage modulus (E'232) was 1.01 MPa or less, suggesting that cracking of the adhesive layer in the support sheet can be suppressed even when the support sheet with the silicon wafer attached is expanded without heating.

In Examples 1 to 4, the tan δ peak temperature (P2) was 10.7°C or less, and in Examples 1 and 4 in particular, the tan δ peak temperature was 0.1°C or less.

Furthermore, in Examples 1 to 3, the adhesive strength (Y2) was 15,600 mN/25 mm or more, which was sufficiently large, and even when the silicon wafer with the support sheet fixed to the ring frame was heated at a high temperature, peeling of the silicon wafer with the support sheet from the ring frame could be suppressed.
Furthermore, in Examples 1 to 3, the adhesive strength (X2) was 15,000 mN/25 mm or more, which was sufficiently large, and peeling of the silicon chip from the support sheet was suppressed even when a large force was applied to the silicon chip after heating the silicon wafer with the support sheet at a high temperature and then dividing the silicon wafer or washing the silicon chip with water after division.

In particular, in Examples 1 and 2, the adhesive strength (Y1) was significantly greater, at 470 mN/25 mm or more. It was estimated that the support sheets of Examples 1 and 2 could prevent the group of silicon chips with the cured support sheet from peeling from the ring frame, even if the support sheet-attached silicon wafer was fixed to a ring frame and heated, and the contact area between the support sheet (adhesive layer) and the ring frame was irradiated with energy rays.

Furthermore, in Examples 1 to 4, the average light transmittance (400 to 800 nm) of the support sheet was 80.1% or higher, which was sufficiently high, indicating that the matte surface of the substrate had a high embedding ability with the adhesive layer.

As such, the support sheets of Examples 1 to 3 were superior in unintended properties and were more preferable.

In contrast, in Comparative Examples 1 and 2, the storage modulus (E'231) was 2.47 MPa or more, and when the support sheet with the silicon wafer attached was heated at 130°C for 2 hours and then expanded, cracking of the adhesive layer in the support sheet was not suppressed.
No energy ray-curable compound (α) was used in Comparative Examples 1 and 2. Furthermore, in Comparative Example 1, the peak temperature (P1) of tan δ was 20.4°C.
In addition, in Comparative Example 2, the adhesive strength (X1) was large, and after the support sheet with the silicon mirror wafer attached was heated at 130°C for 2 hours, the silicon chip could not be picked up normally, and the pickup ability was poor.

Furthermore, in Comparative Example 1, the peak temperature (P2) of tan δ was 20.3°C, suggesting that cracking of the adhesive layer in the support sheet would not be suppressed even when the support sheet with the silicon wafer attached was expanded without heating.

Furthermore, in Comparative Example 1, the adhesive strength (Y1) and adhesive strength (Y2) were also insufficient, and it was presumed that this support sheet was also insufficient in its effect of suppressing peeling from the ring frame, whether in the form of a silicon wafer with a support sheet or a group of silicon chips with a cured support sheet.
Furthermore, in Comparative Example 2, the adhesive strength (X2) was small, and it was presumed that the effect of preventing the silicon chip from peeling off from the support sheet was low when a large force was applied to the silicon chip after heating the silicon wafer with the support sheet at a high temperature, such as by dividing the silicon mirror wafer or washing the silicon chip with water after division.
Furthermore, in Comparative Examples 1 and 2, the average light transmittance (400 to 800 nm) of the support sheet was 79.1% or less, which was insufficient, and it was presumed that the embedding ability of the adhesive layer on the matte surface of the substrate was low.

The present invention can be used in the manufacture of workpieces such as semiconductor chips.

1: Support sheet, 1a: One side of support sheet (side on the adhesive layer side), 11: Substrate, 11a: One side of substrate, 12: Adhesive layer, 12a: Side of adhesive layer opposite to the substrate side, 12': Energy ray cured product, 8: Ring frame, 9: Semiconductor wafer, 9d: Modified layer, 9e: Notch, 91: Semiconductor wafer with modified layer formed, 911A: Preliminary processed body with support sheet, 92: Semiconductor wafer partially cut, 911B: Preliminary processed body with support sheet, 90: Semiconductor chip, 903: Group of semiconductor chips with support sheet, 109: Semiconductor wafer with support sheet, I: Direction of expansion, W ₁ : Distance between adjacent semiconductor chips before expansion step, W ₂ : Distance between adjacent semiconductor chips after expansion step

Claims (8)

A support sheet,
The support sheet includes a substrate and a pressure-sensitive adhesive layer provided on one surface of the substrate,
the pressure-sensitive adhesive layer is energy ray-curable,
a plurality of first test pieces of the pressure-sensitive adhesive layer each having a thickness of less than 200 μm were heated at 130°C, and the heated plurality of first test pieces were laminated together to prepare a second test piece having a thickness of 200±20 μm; the storage modulus E' of the second test piece was measured while heating the second test piece from −20°C to 150°C in a tensile mode under conditions of a frequency of 11 Hz, a temperature rise rate of 3°C/min, and a uniform temperature rise; and the storage modulus E' of the second test piece was measured when the temperature of the second test piece was 23°C, the storage modulus (E'231) was 1.5 MPa or less;
The support sheet is attached to the mirror surface of a silicon mirror wafer by the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer after attachment is heated at 130°C, the pressure-sensitive adhesive layer after heating is energy ray-cured, and when the adhesive strength (X1) between the energy ray-cured product of the pressure-sensitive adhesive layer and the silicon mirror wafer is measured, the adhesive strength (X1) is 400 mN/25 mm or less. The support sheet according to claim 1, wherein the adhesive layer contains an energy ray-curable compound and an energy ray-curable acrylic resin. The support sheet according to claim 1 or 2, wherein when the support sheet is attached to the surface of a stainless steel plate using the adhesive layer, the adhesive layer after attachment is heated at 130°C, and the adhesive strength (Y2) between the adhesive layer and the stainless steel plate after heating is measured, the adhesive strength (Y2) is 13,000 mN/25 mm or more. The support sheet according to any one of claims 1 to 3, wherein the support sheet is attached to the surface of a stainless steel plate using the adhesive layer, the attached adhesive layer is heated at 130°C, the heated adhesive layer is energy ray-cured, and the adhesive strength (Y1) between the energy ray-cured adhesive layer and the stainless steel plate is measured; the adhesive strength (Y1) is 300 mN/25 mm or greater. The support sheet according to any one of claims 1 to 4, wherein when the tan δ of the second test piece is measured while the temperature of the second test piece is raised from -20°C to 150°C in a tensile mode under conditions of a frequency of 11 Hz, a temperature rise rate of 3°C/min, and a uniform temperature rise, the temperature (P1) showing the peak of tan δ is 10°C or less. The support sheet according to any one of claims 1 to 5, wherein when the support sheet is attached to the mirror surface of a silicon mirror wafer using the adhesive layer, the adhesive layer is heated at 130°C after attachment, and the adhesive strength (X2) between the adhesive layer and the silicon mirror wafer after heating is measured, the adhesive strength (X2) is 13,000 mN/25 mm or more. A method for manufacturing a workpiece, comprising:
The manufacturing method includes a bonding step of bonding the adhesive layer in the support sheet according to any one of claims 1 to 6 to the work and the ring frame to fix a work with a support sheet, the work including the support sheet provided on the work, to the ring frame;
a heating step of heating the pressure-sensitive adhesive layer in the support sheet fixed to the ring frame after the attaching step;
a preliminary processing step of forming a modified layer inside the workpiece with the support sheet after the attaching step to divide the workpiece, thereby producing a modified-layer-formed workpiece, or forming a notch in a partial area in the thickness direction of the workpiece with the support sheet to divide the workpiece, thereby producing a semi-cut workpiece, thereby obtaining a pre-processed body with a support sheet, which includes the modified-layer-formed workpiece or the semi-cut workpiece and the support sheet;
a processing step of, after the pre-processing step, expanding the pre-processed body with the support sheet fixed to the ring frame in a direction parallel to the surface of the support sheet, thereby dividing the workpiece with the modified layer formed thereon at the location of the modified layer, or dividing the half-cut workpiece at the slits, thereby producing the workpiece processed product;
a curing step of curing the pressure-sensitive adhesive layer attached to the ring frame with energy rays after the heating step and the processing step;
A method for manufacturing a workpiece, comprising, after the curing step, a pick-up step of separating the workpiece from the cured product of the adhesive layer and picking it up. A method for picking up a workpiece, comprising:
The pick-up method includes a support sheet according to any one of claims 1 to 6, and a workpiece group formed by aligning a plurality of workpieces produced by dividing a workpiece on a surface of the adhesive layer in the support sheet opposite to the substrate side, the adhesive layer in the support sheet, and includes a pasting step of pasting the adhesive layer in the support sheet to a ring frame to fix the workpiece group with the support sheet to the ring frame;
a heating step of heating the workpiece group with the support sheet fixed to the ring frame after the attaching step;
an expanding step of expanding the workpiece group with the support sheet fixed to the ring frame in a direction parallel to the surface of the support sheet after the attaching step, thereby increasing the distance between the workpieces adjacent to each other in the workpiece group;
a curing step of curing the pressure-sensitive adhesive layer attached to the ring frame with energy rays after the heating step and the expanding step;
A method for picking up a workpiece, comprising a pick-up step of, after the curing step, separating the workpiece from the cured product of the adhesive layer and picking it up.