JP7832028B2 - Method for manufacturing support sheets and workpieces - Google Patents

Description

This invention relates to a support sheet and a method for manufacturing a workpiece.

When processing workpieces such as wafers to manufacture processed products such as chips, a support sheet is used. A typical support sheet comprises a base material and an adhesive layer provided on one surface of the base material. The adhesive layer in the support sheet is, for example, attached to the workpiece being processed, and the support sheet holds the workpiece in place during processing. If the processing is dicing, the support sheet functions as a dicing sheet. The resulting processed product 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, energy-ray curing of the adhesive layer reduces the adhesive force between the cured product and the processed product, making it easier to pick up the processed product.

On the surface of the adhesive layer opposite the substrate side, a protective film-forming film may be provided to form a protective film on the workpiece, thus constituting a protective film-forming composite sheet. The protective film-forming film in the protective film-forming composite sheet is, for example, attached to the workpiece being processed. The protective film-forming composite sheet fixes the workpiece during processing and forms a protective film on the workpiece or workpiece. The resulting workpiece, with the protective film still attached, is finally pulled away from the support sheet, picked up, and used for its intended purpose. Similarly, if the adhesive layer is energy-ray curable, energy-ray curing of the adhesive layer facilitates the pickup of the workpiece with the protective film.

On the other hand, the support sheet may be heated while the workpiece or workpiece is attached. This heating may be performed, for example, to remove foreign matter such as low-molecular-weight resin components adhering to the surface of the workpiece. It may also be performed to wash away and remove fine foreign matter that has accumulated on the surface of the workpiece during processing such as dicing, and then to dry the workpiece. These heating processes are usually carried out with an upper limit of approximately 135°C. However, if the heat resistance of the support sheet is insufficient, heating the support sheet with the workpiece or workpiece attached at such a temperature could result in the workpiece becoming impossible to pick up from the support sheet. Furthermore, this heating of the support sheet may be performed while the support sheet is still fixed to the ring frame. In that case, at least a portion of the heated support sheet could detach from the ring frame.

A heat-resistant support sheet suitable for heating has been disclosed, comprising a base material and an adhesive layer, wherein the Young's modulus of the base material at 23°C and the storage modulus E' of the base material at 120°C are both defined within a specific range after heating at 120°C for 4 hours (see Patent Document 1).

Japanese Patent Publication No. 2021-119592

However, the support sheet disclosed in Patent Document 1 is not designed to be heated to an upper temperature limit of approximately 135°C. Furthermore, it is uncertain whether, under such conditions, the workpiece can be properly picked up from the support sheet, and whether the separation of the support sheet from the ring frame is suppressed.

The present invention aims to provide a support sheet comprising a base material and an adhesive layer, wherein the adhesive layer is energy-ray curable, enabling normal pickup of a workpiece or workpiece from the support sheet even when the support sheet is heated with the workpiece attached, and suppressing peeling of the support sheet from the ring frame even when the support sheet is heated while fixed to the ring frame.

To solve the above problems, the present invention adopts the following configuration.
[1] A support sheet comprising a base material and an adhesive layer provided on one surface of the base material, wherein the adhesive layer is energy-ray curable, and when the support sheet is attached to the surface of a stainless steel plate by the adhesive layer, the adhesive layer is heated at 130°C after attachment, and the adhesive force (Y2) between the heated adhesive layer and the stainless steel plate is measured, the adhesive force (Y2) is 13,000 mN/25 mm or more, and when the support sheet is attached to the mirror surface of a silicon mirror wafer by the adhesive layer, the adhesive layer is heated at 130°C after attachment, the adhesive layer is energy-ray cured after heating, and the adhesive force (X1) between the energy-ray cured adhesive layer and the silicon mirror wafer is measured, the adhesive force (X1) is 400 mN/25 mm or less.
[2] The support sheet according to [1], wherein the 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 the support sheet is attached to the surface of a stainless steel plate by the adhesive layer, the adhesive layer is heated at 130°C after attachment, the adhesive layer is energy-ray cured after heating, and the adhesive force (Y1) between the energy-ray cured product of the adhesive layer and the stainless steel plate is measured, and the adhesive force (Y1) is 300 mN/25 mm or more.
[4] The support sheet according to any one of [1] to [3], wherein the support sheet is attached to the mirror surface of a silicon mirror wafer by the adhesive layer, the adhesive layer is heated to 130°C after attachment, and the adhesive force (X2) between the heated adhesive layer and the silicon mirror wafer is measured, and the adhesive force (X2) is 13,000 mN/25 mm or more.

[5] The support sheet according to any one of [1] to [4], wherein the support sheet is attached to the mirror surface of a silicon mirror wafer by the adhesive layer, the silicon mirror wafer equipped with the support sheet is left standing for 30 minutes under a temperature of 23°C, and the adhesive force (X0) between the adhesive layer and the silicon mirror wafer is measured, and the adhesive force (X0) is 2000 mN/25 mm or more.
[6] A method for manufacturing a workpiece, the manufacturing method comprising: an attachment step of fixing a workpiece with a support sheet, comprising the workpiece and the support sheet provided on the workpiece, to the ring frame by attaching the adhesive layer in the support sheet described in any one of [1] to [5] to the workpiece and the ring frame; a heating step of heating the adhesive layer in the support sheet fixed to the ring frame after the attachment step; a processing step of manufacturing the workpiece by processing the workpiece in the workpiece with support sheet fixed to the ring frame after the attachment step; 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 pickup step of separating and picking up the workpiece from the cured adhesive layer after the curing step.

According to the present invention, a support sheet comprising a base material and an adhesive layer is provided, wherein the adhesive layer is energy-ray curable, enabling normal pickup of the workpiece from the support sheet even when the support sheet with the workpiece or workpiece attached is heated, and suppressing peeling of the support sheet from the ring frame even when the support sheet fixed to the ring frame is heated.

This is a schematic cross-sectional view showing an example of a support sheet according to one embodiment of the present invention. This is a schematic cross-sectional view illustrating an example of a method for manufacturing a workpiece with a protective film according to one embodiment of the present invention.

◇Support sheet A support sheet according to one embodiment of the present invention comprises a base material and an adhesive layer provided on one surface of the base material, wherein the adhesive layer is energy-ray curable, and when the support sheet is attached to the surface of a stainless steel plate by the adhesive layer, the adhesive layer is heated to 130°C after attachment, and the adhesive force (Y2) (in this specification, sometimes simply referred to as "adhesion force (Y2)") between the heated adhesive layer and the stainless steel plate is measured, the adhesive force (Y2) is 13,000 mN/25 mm or more, and when the support sheet is attached to the mirror surface of a silicon mirror wafer by the adhesive layer, the adhesive layer is heated to 130°C after attachment, the adhesive layer is energy-ray cured after heating, and the adhesive force (X1) (in this specification, sometimes simply referred to as "adhesion force (X1)") between the energy-ray cured product of the adhesive layer and the silicon mirror wafer is measured, the adhesive force (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 later, to form a composite sheet for forming a protective film.

The support sheet to which the workpiece or workpiece is attached may be heated to a high temperature while fixed to the ring frame. This heating may be performed, for example, to remove foreign matter such as low molecular weight resin components adhering to the surface of the workpiece. It may also be performed to wash away and remove fine foreign matter that has been generated during processing such as dicing of the workpiece and has adhered to the surface of the workpiece, and then to dry the workpiece. These heating processes are usually carried out with an upper limit of approximately 135°C.
The support sheet of this embodiment has an adhesive strength (Y2) of 13,000 mN/25 mm or more, which prevents it from peeling off the ring frame even when heated at high temperatures while fixed to the ring frame.

In the support sheet of this embodiment, the adhesive strength (X1) is 400 mN/25 mm or less. Therefore, even after heating the support sheet with the workpiece or workpiece attached at a high temperature, the workpiece can be fabricated from the workpiece on the support sheet, the adhesive layer in the support sheet hardens to form a cured support sheet, and the workpiece can be picked up normally from the cured support sheet, resulting in high pick-up efficiency. The purpose of heating the support sheet at a high temperature in this case is the same as described above.

In this specification, a support sheet after the adhesive layer has cured may be referred to as a "cured support sheet" in order to distinguish it from a support sheet before the adhesive layer has cured.

In this specification, "room temperature" refers to a temperature that is neither cooled nor heated, i.e., a normal temperature, such as 18-28°C.

In this embodiment, examples of workpieces include wafers and semiconductor device panels.

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

The aforementioned semiconductor device panel is handled during the manufacturing process of semiconductor devices. A specific example is a semiconductor device in which one or more electronic components are sealed with a sealing resin, and multiple such semiconductor devices are arranged planarly within a circular, rectangular, or other shaped region.

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

In this specification, "energy beam" means an electromagnetic wave or charged particle beam that has an energy quantum. Examples of energy beams include ultraviolet rays, radiation, and electron beams. Ultraviolet rays can be irradiated, for example, by using high-pressure mercury lamps, fusion lamps, xenon lamps, black lights, or LED lamps as ultraviolet light sources. Electron beams can be irradiated using those generated by electron accelerators, etc.
In this specification, "energy ray curable" means the property of hardening when irradiated with energy rays, and "non-energy ray curable" means the property of not hardening even when irradiated with energy rays.
In this specification, "non-curable" means the property of not curing by any means, such as heating or irradiation with energy rays.

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

The support sheet 1 shown herein comprises a base material 11 and an adhesive layer 12 provided on one surface 11a of the base material 11. The support sheet 1 further comprises a release film 13 provided on the surface 12a of the adhesive layer 12 opposite to the base material 11 side.
One surface 11a of the base material 11 may be, for example, a matte surface, or it may not be a matte surface (for example, a glossy surface with a low degree of unevenness).
The adhesive layer 12 is energy ray curable.
The adhesive strength (Y2) measured using the support sheet 1 is 13,000 mN/25 mm or more, and the adhesive strength (X1) is 400 mN/25 mm or less.

In this specification, "matte surface" refers to a surface that has a relatively high degree of unevenness, is rough, has a relatively low gloss, and appears to have a matte finish.

The support sheet of this embodiment is not limited to the one shown in Figure 1, and some components of the one shown in Figure 1 may be modified, deleted, or added, as long as the effects of the present invention are not impaired.
For example, the support sheet 1 shown in Figure 1 includes a release film 13, but in the support sheet of this embodiment, the release film can have any configuration, and the support sheet of this embodiment does not need to include a release film.
For example, the support sheet 1 shown in Figure 1 comprises a base material 11, an adhesive layer 12, and a release film 13. However, the support sheet of this embodiment may also comprise other layers that do not correspond to the base material, adhesive layer, or release film. The other layers can be arbitrarily selected according to the purpose and are not particularly limited. However, in the support sheet of this embodiment, it is preferable that the base material and the adhesive layer are in direct contact with each other, and that the adhesive layer and the release film are in direct contact with each other.

Next, the details of each layer constituting the support sheet of this embodiment will be described.

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

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

In this specification, not only in the case of adhesive layers, "multiple layers may be identical or different from one another" means "all layers may be identical, all layers may be different, or only some layers may be identical," and furthermore, "multiple layers are different from one another" means "at least one of the constituent materials and thickness of each layer is different from the 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, if the adhesive layer is provided on the matte surface of the substrate, the embedding ability of the adhesive layer on the matte surface of the substrate is improved, and the aforementioned pick-up ability of the workpiece from the cured support sheet is improved.
Here, "thickness of the adhesive layer" refers to the total thickness of the adhesive layer. For example, the thickness of an adhesive layer consisting of multiple layers refers to the total thickness of all the layers that make up the adhesive layer.

In this specification, "thickness," unless otherwise specified, refers to the average of the thicknesses measured at five randomly selected locations on the object, and can be obtained using a constant-pressure thickness measuring instrument in accordance with JIS K7130.

An adhesive layer can be formed using an adhesive composition containing the components necessary to form it. For example, an adhesive layer can be formed on the desired area by applying the adhesive composition to the surface to be coated and drying it as needed. The ratio of components that do not vaporize at room temperature in the adhesive composition is usually the same as the ratio of those components in the adhesive layer.

In the adhesive layer, the ratio of the total content of one or more of the following components in the adhesive layer to the total mass of the adhesive layer shall not exceed 100% by mass.
Similarly, in an adhesive composition, the ratio of the total content of one or more of the following components of the adhesive composition to the total mass of the adhesive composition shall not exceed 100% by mass.

The adhesive composition can be coated using known methods, such as air knife coaters, blade coaters, bar coaters, gravure coaters, roll coaters, roll knife coaters, curtain coaters, die coaters, knife coaters, screen coaters, Meyer bar coaters, and kiss coaters.

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

When providing an adhesive layer on a substrate, for example, the adhesive composition can be applied to the substrate and dried as necessary. Alternatively, for example, the adhesive composition can be applied to a release film and dried as necessary to form an adhesive layer on the release film. The exposed surface of this adhesive layer can then be bonded to one surface of the substrate (e.g., a matte or glossy surface) to laminate the adhesive layer onto the substrate. In this case, the release film can be removed at either the manufacturing or usage stage of the support sheet.

The adhesive layer preferably contains an energy-ray curable compound (α). By using an adhesive layer containing the energy-ray curable compound (α), it becomes easy to adjust both the adhesive strength (X1) and the adhesive strength (Y2).
In other words, a preferred adhesive composition is, for example, an 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-curable compound (α) at 23°C is preferably 350 mPa·s or less, and may be, for example, 320 mPa·s or less, 220 mPa·s or less, 120 mPa·s or less, or 60 mPa·s or less. The lower the viscosity, the better the embedding ability of the adhesive layer on the mat surface of the substrate.
The lower limit of the viscosity of the energy ray-curable compound (α) at 23°C is not particularly limited. For example, an energy ray-curable compound (α) with a viscosity of 5 mPa·s or more is more readily available.
The viscosity of the energy-ray curable compound (α) at 23°C may be, for example, 5 to 350 mPa·s, 5 to 320 mPa·s, 5 to 220 mPa·s, 5 to 120 mPa·s, or 5 to 60 mPa·s or less. However, these are just examples of the aforementioned viscosities.

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

Examples of energy-ray curable compounds (α) include monomers or oligomers having energy-ray polymerizable unsaturated groups that can be cured by irradiation with energy rays.
Each molecule of the energy-ray curable compound (α) has one or more of the energy-ray polymerizable unsaturated groups, and may have three or more, but it is preferable that it has one or two.
Examples of energy-ray polymerizable unsaturated groups include the (meth)acryloyl group.

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

The energy-ray curable compound (α) is preferably a (meth)acrylic acid ester which may have substituents. Examples of substituted (meth)acrylic acid esters include compounds having a structure in which one or more carbon atoms in an alcohol-derived hydrocarbon group (a hydrocarbon group bonded to an oxygen atom that does not constitute a carbonyl group in an oxycarbonyl group (-O-C(=O)-)) are substituted together with the hydrogen atoms bonded to these carbon atoms (for example, in units of _-CH2- , =CH-). However, two adjacent carbon atoms are not substituted with substituents.

The hydrocarbon group in the (meth)acrylic acid ester, which is the energy-ray curable compound (α), may be linear, branched, or cyclic, and if cyclic, it may be monocyclic or polycyclic. The hydrocarbon group may have both a linear structure (either linear or 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 having only an aliphatic group and no aromatic cyclic group is an aliphatic hydrocarbon group, and a hydrocarbon group having both an aliphatic group and an aromatic cyclic group, or having only an aromatic cyclic group, is an aromatic hydrocarbon group.

The hydrocarbon group is preferably a cyclic structure, that is, a cyclic hydrocarbon group, or 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 multiple atoms are bonded together, or it may be a single atom.
Preferred substituents include, for example, an oxygen atom (-O-).

When the hydrocarbon group has the substituents, the number of substituents is adjusted as appropriate depending on the type of hydrocarbon group, but is generally preferably 1 to 4, and more preferably 1 to 3.

The number of carbon atoms in the hydrocarbon group is preferably 3 to 20, for example, it may be any of 3 to 16, 3 to 12, and 3 to 8, or any of 4 to 20, 9 to 20, and 13 to 20, or any of 4 to 16 and 9 to 14. However, these are just examples of the number of carbon atoms. Here, "number of carbon atoms in the hydrocarbon group" means the number of carbon atoms in the hydrocarbon group before substitution with the substituent, if the hydrocarbon group has the substituent. For example, if the 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 pre-substituted group such as a methylene group ( _-CH2- ).

The hydrocarbon group is preferably a hydrocarbon group having a cyclic structure and which may have an oxygen atom as a substituent; more preferably a hydrocarbon group having both a chain-like structure and a cyclic structure and which may have an oxygen atom as a substituent; even more preferably an aliphatic hydrocarbon group or an aromatic hydrocarbon group which may have an oxygen atom as a substituent; even more preferably an aromatic hydrocarbon group having both an aliphatic group having an oxygen atom as a substituent and an aromatic cyclic group without a substituent (in this specification, the energy-ray curable compound (α) in this case may be referred to as "energy-ray curable compound (α1)"), or an aliphatic hydrocarbon group having both a cyclic structure without a substituent and a chain-like structure without a substituent (in this specification, the energy-ray curable compound (α) in this case may be referred to as "energy-ray curable compound (α2)"), or an aliphatic hydrocarbon group having both a cyclic structure having an oxygen atom as a substituent and a chain-like structure without a substituent (in this specification, the energy-ray curable compound (α) in this case may be referred to as "energy-ray curable compound (α3)"). By using such an energy-ray-curable compound (α), when an adhesive layer is applied to the mat surface of the substrate, the embedding ability of the adhesive layer on the mat surface of the substrate is improved.

An example of the energy ray curable compound (α1) is energy ray curable compound (α)-1, which will be described later in the examples.
An example of the energy ray curable compound (α2) is energy ray curable compound (α)-2, which will be described later in the examples.
An example of the energy ray curable compound (α3) is energy ray curable compound (α)-3, which will be 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. Using such an energy-ray curable compound (α) improves the properties of the adhesive layer. For example, when providing an adhesive layer on the matte surface of a substrate, the embedding ability of the adhesive layer on the matte surface of the substrate is improved.

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, 200 to 310 and 200 to 280, or 250 to 400 and 310 to 400, or 250 to 310. Having a molecular weight below the upper limit improves the properties of the adhesive layer (e.g., the embedding ability of the adhesive layer on the matte surface of the substrate). Having a molecular weight above the lower limit stabilizes the structure of the adhesive layer. However, these are just examples of molecular weights for the energy-ray-curable compound (α).
Energy ray curable compound (α1), energy ray curable compound (α2), and energy ray curable compound (α3) having any of the molecular weights shown herein are particularly preferred energy ray curable compound (α).

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

The energy-curable compound (α) contained in the adhesive layer and adhesive composition (I) may be one type or two or more types. If there are two or more types, their combination and ratio can be arbitrarily selected.

In the adhesive composition (I), the ratio of the energy ray curable compound (α) 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. On the other hand, the ratio is 100% by mass or less.
This is equivalent to stating that the ratio of the energy ray curable compound (α) content in the adhesive layer to the total mass of the adhesive layer is preferably 5% by mass or more, and may be 10% by mass or more, or 14% by mass or more, and that the ratio is 100% by 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 ratio of the contents of non-solvent components is the same in the resin composition and the resin film. Therefore, in this specification, not only in the case of an adhesive layer, but also thereafter, the content of non-solvent components will only be described in the resin film obtained by removing the solvent from the resin composition.

<Energy-ray curable acrylic resin (Ia)>
The adhesive layer and adhesive composition (I) further preferably contain an energy-ray curable acrylic resin (also referred to herein as "energy-ray curable acrylic resin (Ia)"), that is, it is more preferable that they contain both an energy-ray curable compound and an energy-ray curable acrylic resin. By using an adhesive layer containing an energy-ray curable compound (α) and an energy-ray curable acrylic resin (Ia), it becomes easier to adjust both the adhesive strength (X1) and the adhesive strength (Y2).

Examples of the energy-ray curable acrylic resin (Ia) include resins having a structure in which unsaturated groups are introduced into the side chains 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)acrylate 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 linear or branched is preferred.

Among the alkyl (meth)acrylate esters, those in which the alkyl group is linear or branched include, for example, 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 include n-nonyl methacrylate, isononyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate (lauryl methacrylate), tridecyl methacrylate, tetradecyl methacrylate (myristyl methacrylate), pentadecyl methacrylate, hexadecyl methacrylate (palmityl methacrylate), heptadecyl methacrylate, octadecyl methacrylate (stearyl methacrylate), nonadecyl methacrylate, and eicosyl methacrylate.

Among the alkyl (meth)acrylate esters mentioned above, examples of those in which the alkyl group is cyclic include isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate.

Among the above, the alkyl (meth)acrylate ester is preferably 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, dodecyl acrylate (lauryl acrylate), or dodecyl methacrylate (lauryl methacrylate) in that it can reduce the adhesive strength (X1).

Examples of the functional group-containing monomers include those in which the functional group reacts with a crosslinking agent (described later) to serve as a starting point for crosslinking, or those in which the functional group reacts with a group in an unsaturated group-containing compound (described later) that can bond (react) with a 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 monomers include hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, and the like.

Examples of the hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and non-(meth)acrylic unsaturated alcohols (unsaturated alcohols without a (meth)acryloyl skeleton) such as vinyl alcohol and allyl alcohol.
Among these, the hydroxyl group-containing monomer is preferably hydroxyalkyl methacrylate, and more preferably 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, or 2-hydroxybutyl methacrylate, in that it can reduce the adhesive force (X1).

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

Examples of the epoxy group-containing monomers 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.

Non-energy ray curable acrylic resins may have constituent units derived from other monomers that do not fall under either the (meth)acrylate alkyl ester-derived constituent units or the functional group-containing monomer-derived constituent units.

The other monomers mentioned above are not particularly limited as long as they can be copolymerized with alkyl (meth)acrylate esters, etc.
Examples of the other monomers mentioned above include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

The constituent units derived from alkyl (meth)acrylate, the constituent units derived from the functional group-containing monomer, and the constituent units derived from the other monomers in the non-energy ray-curable acrylic resin may each consist of only one type or two or more types. If there are two or more types, their combinations and ratios can be arbitrarily selected.

In non-energy ray curable acrylic resins, the content of constituent units derived from alkyl (meth)acrylate is preferably 65 to 99% by mass relative to the total amount of constituent units.

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

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

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

The aforementioned unsaturated group-containing compound is a compound that, in addition to the energy-ray polymerizable unsaturated group, has a group that can bond with 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), an allyl group (2-propenyl group), and the (meth)acryloyl group, with the (meth)acryloyl group being preferred.
Examples of groups that can bond with the functional groups in the non-energy ray curable acrylic resin include isocyanate groups and glycidyl groups that can bond with hydroxyl groups or amino groups, and hydroxyl groups and amino groups that can bond with carboxyl groups or epoxy groups.

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

When obtaining an energy-ray curable acrylic resin (Ia) by reacting the functional groups in a 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 unsaturated groups in the unsaturated group-containing compound relative to the total number of moles of functional groups in the non-energy-ray curable acrylic resin may be 0.6 times or more and 0.75 times or more, but is preferably 0.8 times or more, more preferably 0.85 times or more, and even more preferably 0.9 times or more. The larger the total number of moles of unsaturated groups, the lower the adhesive force (X1) can be, and the higher the pickability of the workpiece from the cured support sheet tends to be.
On the other hand, it is preferable that the total number of moles of unsaturated groups in the unsaturated group-containing compound is 1 or less relative to the total number of moles of functional groups in the non-energy ray curable acrylic resin.

The energy-curable acrylic resin (Ia) contained in the adhesive layer and adhesive composition (I) may be of one type or two or more types. If there are two or more types, their combination and ratio can be arbitrarily selected.

When the adhesive layer and adhesive composition (I) contain an energy-ray curable acrylic resin (Ia), the ratio of the energy-ray curable compound (α) to the total mass of the adhesive layer is preferably 5 to 50% by mass, for example, 5 to 35% by mass and 5 to 25% by mass, or 10 to 50% by mass and 14 to 50% by mass, or 10 to 35% by mass. A ratio above the lower limit results in better properties of the adhesive layer (e.g., embedding ability of the adhesive layer on the matte surface of the substrate). A ratio below the upper limit results in better pick-up performance, allowing the workpiece to be picked up from the support sheet without abnormalities.

When the adhesive layer and adhesive composition (I) contain an energy-ray curable acrylic resin (Ia), the ratio of the energy-ray curable acrylic resin (Ia) content to the total mass of the adhesive layer is preferably 50 to 95% by mass, for example, 65 to 95% by mass and 75 to 95% by mass, or 50 to 90% by mass and 50 to 86% by mass, or 65 to 90% by mass. A ratio above the lower limit improves the pick-up performance, allowing the workpiece to be picked up from the support sheet without abnormalities. A ratio below the upper limit improves the properties of the adhesive layer (for example, the embedding ability of the adhesive layer on the matte surface of the substrate).

<Other ingredients>
The adhesive layer and adhesive composition (I) may contain other components that do not fall under either the energy-ray curable compound (α) or the energy-ray curable acrylic resin (Ia), as long as they do not impair the effects of the present invention.
Other components mentioned above include, for example, crosslinking agents (β), photopolymerization initiators (γ), and additives.

The other components contained in the adhesive layer and adhesive composition (I) may be one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

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

Examples of crosslinking agents (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]triphosphotriazine; 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, as this makes it easier to set the adhesive strength (X1) within the range described later.

The crosslinking agent (β) contained in the adhesive layer and adhesive composition (I) may be one type or two or more types. If there are two or more types, their combination and ratio can be arbitrarily selected.

In the adhesive layer, the content of the crosslinking agent (β) 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 0.1 to 5 parts by mass and 0.1 to 3 parts by mass, or 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. Having the crosslinking agent (β) content within this range makes it easy to adjust both the adhesive strength (X1) and the adhesive strength (Y2).

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

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-phenylpropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one; and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyl Examples include acylphosphine oxide compounds such as diphenylphosphine oxide; sulfide compounds such as benzylphenyl sulfide and tetramethylthiuram monosulfide; α-ketol compounds such as 1-hydroxycyclohexylphenyl 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, photosensitizers such as amines 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, as it makes it easier to set the tackiness (X1) within the range described later.

The photopolymerization initiator (γ) contained in the adhesive layer and adhesive composition (I) may be one type or two or more types. If there are two or more types, their combination and ratio can be arbitrarily selected.

In the 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 adhesive layer contains energy-ray curable acrylic resin (Ia). For example, it may be 1 to 4 parts by mass or 1.5 to 3.5 parts by mass.

[Additives]
Examples of known additives include antistatic agents, antioxidants, 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 unintended crosslinking reaction that occurs in the adhesive composition (I) during storage due to the action of a catalyst mixed in the adhesive composition (I). Examples of reaction retarders include those that form a chelate complex by chelation 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 additive, or two or more additives. If there are two or more additives, their combination and ratio can be arbitrarily selected.

The content of additives in adhesive composition (I) is not particularly limited and may be appropriately selected depending on their type.

[solvent]
The adhesive composition (I) may contain a solvent. The presence of a solvent in the adhesive composition (I) improves its suitability for coating the surface to be coated.

The solvent is preferably an organic solvent. 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 adhesive composition (I) may contain only one solvent, or two or more solvents. If there are two or more solvents, their combination and ratio can be arbitrarily selected.

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

<One embodiment of the adhesive layer>
Examples of preferred adhesive layers and adhesive compositions (I) include those 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 manufacturing adhesive composition (I)>
The adhesive composition (I) is obtained by blending an energy-ray curable compound (α) with other components for constituting the adhesive composition (I), such as an energy-ray curable acrylic resin (Ia) if necessary.
There are no particular restrictions on the order in which each component is added during formulation, and two or more components may be added simultaneously.
The method of mixing each component during formulation is not particularly limited; it can be appropriately selected from known methods such as mixing by rotating a stirring bar or impeller, mixing using a mixer, or mixing by applying ultrasonic waves.
The temperature and time during the addition and mixing of each component are not particularly limited as long as the components do not deteriorate, and can be adjusted as appropriate, but the temperature is preferably between 15 and 30°C.

<<Base material>>
The substrate is in the form of a sheet or film, and its constituent materials include, for example, various resins.
The aforementioned resins include, for example, polyethylene 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 such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, and ethylene-norbornene copolymer (polymers obtained using ethylene as a monomer); and vinyl chloride-based resins such as polyvinyl chloride and vinyl chloride copolymer (obtained using vinyl chloride as a monomer). Examples include modified resins; polystyrene; polycycloolefins; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalenedicarboxylate, and all aromatic polyesters having aromatic cyclic groups as all constituent units; 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.
Furthermore, the resin may also include, for example, a polymer alloy such as a mixture of the polyester and other resins. In the polymer alloy of polyester and other resins, it is preferable that the amount of the resin other than polyester is relatively small.
Furthermore, examples of the resin include crosslinked resins obtained by crosslinking one or more of the resins exemplified so far; and modified resins such as ionomers using one or more of the resins exemplified so far.

Among the above, polypropylene or polybutylene terephthalate is preferred as the resin component of the base material because it provides higher heat resistance (around 135°C) and flexibility.

The resin constituting the base material may be of one type or two or more types. If there are two or more types, their combination and ratio can be arbitrarily selected.

The base material may contain various known additives other than the main constituent material such as the aforementioned resin, including fillers, colorants, antioxidants, organic lubricants, catalysts, and plasticizers.

In the aforementioned support sheet, since the adhesive layer is energy-ray curable, the substrate is preferably one that transmits energy rays and is preferably transparent.

In the substrate, it is preferable that at least one surface is a matte surface, and both surfaces may be matte surfaces, or one surface may be a matte surface and the other surface may be a glossy surface with a low degree of unevenness.
In the support sheet, an adhesive layer may be provided on the matte surface of the base material. If both sides of the base material are matte surfaces, the adhesive layer may be provided on the matte surface with the greater surface roughness (Ra).

The matte surface of a substrate is a surface with a roughness above a certain value and has low gloss, making it clearly identifiable by its appearance. Substrates with at least one matte surface are commercially available and can also be manufactured 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, the effect of high embedding ability of the adhesive layer on the matte surface of the substrate is more pronounced when the composition of the adhesive layer is adjusted and the adhesive layer is provided on the matte surface of the substrate. In addition, blocking of the substrates when they are stored stacked is further suppressed.
There is no particular upper limit to the surface roughness (Ra) of the matte surface of the substrate. For example, in order to prevent the surface from becoming excessively uneven, the surface roughness is preferably 2 μm or less.
The surface roughness (Ra) of the matte surface of the substrate may be, for example, 0.05 to 2 μm, 0.1 to 2 μm, 0.4 to 2 μm, and 0.7 to 2 μm. However, 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. Having the surface roughness within this range results in a higher average light transmittance of the support sheet described later in the 400-800 nm wavelength range.
The lower limit of the surface roughness (Ra) of the glossy surface of the substrate is not particularly limited. For example, in terms of suppressing blocking of the substrates when they are stored stacked, the surface roughness is preferably 0.01 μm or more.
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. However, these are just examples of the aforementioned surface roughness.

The surface roughness (Ra) of both sides of the substrate can be adjusted, for example, by the molding conditions of the substrate and the surface treatment conditions. Examples of surface treatments include sandblasting, solvent treatment, etc., to create unevenness, and polishing, etc., to smooth the surface.

The substrate may be subjected to surface treatments such as corona discharge treatment, electron beam irradiation treatment, plasma treatment, ozone/ultraviolet irradiation treatment, flame treatment, chromic acid treatment, hot air treatment, etc., as well as lipophilic treatment and hydrophilic treatment, in order to adjust its adhesion to the adhesive layer provided thereon. The surface of the substrate may also be primed.

The base material may consist of a single layer (one layer) or of two or more layers. If it consists of multiple layers, these layers may be identical or different, and the combination of these layers is not particularly limited.

The thickness of the base material is preferably 50 to 300 μm, and more preferably 60 to 100 μm. Having the base material thickness within this range improves the heat resistance (e.g., around 135°C), flexibility, and suitability for attachment to the workpiece of the support sheet.
Here, "substrate thickness" refers to the total thickness of the substrate. For example, the thickness of a substrate consisting of multiple layers refers to the total thickness of all the layers that make up the substrate.

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

<<Release film>>
The aforementioned release film may be one of known types.
More specifically, a release film may be one in which one or both sides of the release film substrate are release surfaces. The release film substrate is preferably a polyethylene terephthalate film.
The aforementioned release surface can be formed by peeling the surface of the substrate for the release film with a known release agent.
The thickness of the release film may be, for example, 2 to 300 μm, and is preferably 20 to 100 μm.

Next, the physical properties of the support sheet (adhesive layer) will be described.

<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 pickability, 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, an adhesive layer with an adhesive strength (X1) of 30 mN/25 mm or more can be formed more easily.
The adhesive strength (X1) may be, for example, 30 to 400 mN/25 mm, 30 to 340 mN/25 mm, 30 to 280 mN/25 mm, 30 to 220 mN/25 mm, or 30 to 180 mN/25 mm or less. However, these are just examples of adhesive strength (X1).

The adhesive strength (X1) can be measured, for example, by the method shown below.
Specifically, first, a test piece with a width of 25 mm is cut from the support sheet.
Next, the test piece (support sheet) is attached to the mirror surface of the silicon mirror wafer using the adhesive layer within it to produce a silicon mirror wafer with the test piece attached. This attachment is preferably carried out at room temperature, with an attachment speed of 290 to 310 mm/min and an attachment pressure of 0.3 MPa, using a laminating roller.
Next, the silicon mirror wafer with the test piece attached is heated at 130°C for 2 hours.
Next, the silicon mirror wafer with the test specimen attached is cooled to 23°C by air cooling. Then, under conditions of illuminance of 230 mW/ ^cm² and light intensity of 200 mJ/ ^cm² , the adhesive layer in the cooled silicon mirror wafer with the test specimen attached is irradiated with energy rays through the substrate to cure the adhesive layer in the test specimen.
Next, at room temperature, the test specimen is peeled from the silicon mirror wafer at a peeling speed of 300 mm/min. At this time, the test specimen is peeled in its longitudinal direction so that the side of the silicon mirror wafer to which the test specimen was attached and the side of the test specimen to which the silicon mirror wafer was attached form a 180° angle, a so-called 180° peeling procedure. The load (peeling force) at this 180° peeling is then measured, and the measurement length is set to 50 mm. The measurement values at the first 5 mm and the measurement values at the last 5 mm are excluded from the valid values. The average of these measurement values is then adopted as the adhesive strength (X1) (mN/25 mm).
In this embodiment, such peeling force measurements may be performed on two or more test pieces (support sheets), and the average value of the obtained multiple measurements may be adopted as the adhesive force (X1).

<Adhesive strength (X2)>
When the support sheet is attached to the mirror surface of a silicon mirror wafer by the adhesive layer, and the adhesive layer is heated to 130°C after attachment, the adhesive force (X2) between the heated adhesive layer and the silicon mirror wafer (sometimes simply referred to as "adhesion force (X2)" in this specification) is measured, it is preferable that the adhesive force (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 is heated to a high temperature, peeling of the workpiece from the support sheet is suppressed even when a large force is applied to the workpiece due to processing of the workpiece or washing of the workpiece.

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, an adhesive layer with an adhesive strength (X2) of 19,000 mN/25 mm or less can be formed more easily.
The adhesive strength (X2) may be, for example, 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 adhesive strength (X2).

The adhesive strength (X2) can be measured, for example, by the method shown below.
Specifically, a silicon mirror wafer with a test piece attached is prepared using the same method as when measuring the adhesive strength (X1), heated at 130°C for 2 hours, and then cooled by air until its temperature reaches 23°C.
Next, under conditions of 23°C, the test specimen is peeled off the cooled silicon mirror wafer at a peeling speed of 300 mm/min. At this time, the test specimen is peeled in its longitudinal direction, so as to be called 180° peeling, where the side of the silicon mirror wafer to which the test specimen was attached and the side of the test specimen to which the silicon mirror wafer was attached form a 180° angle. The load (peeling force) at this 180° peeling is then measured, and the measurement length is set to 50 mm. The measurement values at the first 5 mm and the measurement values at the last 5 mm are excluded from the valid values. The average of these measurement values is then adopted as the adhesive strength (X2) (mN/25 mm).
In this embodiment, such peeling force measurements may be performed on two or more test pieces (support sheets), and the average value of the multiple obtained measurements may be adopted as the adhesive force (X2).

<Adhesion (Y1)>
The support sheet is attached to the surface of a stainless steel (SUS) plate using the adhesive layer, the adhesive layer is heated to 130°C after attachment, the heated adhesive layer is cured by energy rays, and the adhesive force (Y1) between the energy-ray cured adhesive layer and the stainless steel plate (in this specification, this may simply be referred to as "adhesion force (Y1)") is measured, and it is preferable that the adhesive force (Y1) is 300 mN/25 mm or more.
In the method for manufacturing workpieces described later, a workpiece with a support sheet, comprising a workpiece and a support sheet provided on the workpiece, is fixed to a ring frame. In this state, a workpiece is manufactured from the workpiece, and the adhesive layer in the support sheet is cured by energy rays to become a cured support sheet. That is, after the energy ray curing of the adhesive layer, a cured support sheet workpiece, comprising a workpiece and a cured support sheet provided on the workpiece, or a cured support sheet workpiece, comprising a workpiece and a cured support sheet provided on the workpiece, can be obtained from the workpiece with a support sheet. In this way, after the energy ray curing of the adhesive layer, a laminate of the workpiece or workpiece and the cured support sheet is fixed to the ring frame.
Furthermore, by using a support sheet with 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 onto the contact portion of the support sheet (adhesive layer) with the ring frame, the peeling of the laminate of the workpiece or workpiece processed and the cured 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 the peeling of the laminate of the workpiece or workpiece processed material and the cured support sheet from the ring frame.
The upper limit of the adhesive strength (Y1) is not particularly limited. For example, an adhesive layer with an adhesive strength (Y1) of 2000 mN/25 mm or less can be formed more easily.
The adhesive strength (Y1) may be, for example, 300-2000 mN/25 mm, 400-2000 mN/25 mm, 500-2000 mN/25 mm, or 600-2000 mN/25 mm. However, these are just examples of adhesive strength (Y1).

The adhesive strength (Y1) can be measured, for example, by the method shown below.
Specifically, first, a test piece with a width of 25 mm is cut from the support sheet.
Next, the test piece (support sheet) is attached to one side of a SUS plate with a thickness of 1000 μm using the adhesive layer within it, thereby creating a SUS plate with a test piece attached. This attachment is preferably carried out at room temperature, with an attachment speed of 290 to 310 mm/min and an attachment pressure of 0.3 MPa, using a laminating roller.
Next, the SUS plate with the test specimen attached is heated at 130°C for 2 hours.
Next, the SUS plate with the test specimen attached is cooled to 23°C by air cooling. Then, under conditions of illuminance of 230 mW/ ^cm² and light intensity of 200 mJ/ ^cm² , the adhesive layer in the cooled SUS plate with the test specimen attached is irradiated with energy rays through the substrate to cure the adhesive layer in the test specimen.
Next, at room temperature, the test specimen is peeled from the SUS plate at a peeling speed of 300 mm/min. At this time, the test specimen is peeled in its longitudinal direction so that the side of the SUS plate to which the test specimen was attached and the side of the test specimen to which the SUS plate was attached form a 180° angle, a so-called 180° peel. The load (peeling force) at this 180° peel is then 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 values. The average of these measured values is then adopted as the adhesive strength (Y1) (mN/25 mm).
In this embodiment, such peeling force measurements may be performed on two or more test pieces (support sheets), and the average value of the multiple obtained measurements may be adopted as the adhesive force (Y1).

<Adhesion (Y2)>
When the support sheet is attached to the surface of a stainless steel (SUS) plate using the adhesive layer, and the adhesive layer is heated to 130°C after attachment, the adhesive force (Y2) between the heated adhesive layer and the stainless steel plate is measured, the adhesive force (Y2) is 13,000 mN/25 mm or more. By using such a support sheet, in the method for manufacturing workpieces described later, even if the workpiece with the support sheet, or the workpiece with the support sheet comprising a workpiece and a support sheet provided on the workpiece, is further heated while fixed to the ring frame, peeling of the workpiece with the support sheet or the workpiece with the support sheet from the ring frame is suppressed.

The adhesive strength (Y2) is 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 the 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, an adhesive layer with an adhesive strength (Y2) of 20,000 mN/25 mm or less can be formed more easily.
The adhesive strength (Y2) may be, for example, 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. However, these are just examples of adhesive strength (Y2).

The adhesive strength (Y2) can be measured, for example, by the method shown below.
Specifically, a SUS plate with a test specimen attached is prepared using the same method as when measuring the adhesive strength (Y1), heated at 130°C for 2 hours, and then cooled by air until its temperature reaches 23°C.
Next, under conditions of 23°C, the test specimen is peeled off the cooled SUS plate at a peeling speed of 300 mm/min. At this time, the test specimen is peeled in its longitudinal direction, so as to be called 180° peeling, where the side of the SUS plate to which the test specimen was attached and the side of the test specimen to which the SUS plate was attached form a 180° angle. The load (peeling force) at this 180° peeling is then 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 values. The average of these measured values is then adopted as the adhesive strength (Y2) (mN/25 mm).
In this embodiment, the peeling force may be measured on two or more test pieces (support sheets), and the average value of the multiple measured values obtained may be adopted as the adhesive force (Y2).

<Adhesive strength (X0)>
When the support sheet is attached to the mirror surface of a silicon mirror wafer by the adhesive layer, and the silicon mirror wafer equipped with the support sheet is left standing for 30 minutes at a temperature of 23°C, and the adhesive force (X0) between the adhesive layer and the silicon mirror wafer (sometimes simply referred to as "adhesion force (X0)" in this specification) is measured, it is preferable that the adhesive force (X0) is 2000 mN/25 mm or more. By using such a support sheet, even when a large force is applied to the workpiece or workpiece processed object while it is attached to the support sheet, such as during high-load processing of the workpiece (for example, high-speed dicing of a semiconductor wafer) or high-load water washing of the workpiece processed object (for example, high-pressure water washing of a semiconductor chip after dicing), peeling of the workpiece from the support sheet is suppressed.

The adhesive strength (X0) is more preferably 2500 mN/25 mm or more, and may be, for example, 3000 mN/25 mm or more, 3500 mN/25 mm or more, or 4000 mN/25 mm or more. The greater the adhesive strength (X0), the greater the effect of suppressing peeling of the workpiece from the support sheet.
The upper limit of the adhesive strength (X0) is not particularly limited. For example, in terms of balancing the adhesive strength (X0) with other physical properties of the adhesive layer, it is preferable that the adhesive strength (X0) is 6000 mN/25 mm or less.
The adhesive strength (X0) may be, for example, 2000-6000 mN/25 mm, 2500-6000 mN/25 mm, 3000-6000 mN/25 mm, 3500-6000 mN/25 mm, and 4000-6000 mN/25 mm. However, these are just examples of adhesive strength (X0).

The adhesive strength (X0) can be measured, for example, by the method shown below.
Specifically, first, a test piece with a width of 25 mm is cut from the support sheet.
Next, the test piece (support sheet) is attached to the mirror surface of the silicon mirror wafer using the adhesive layer within it to produce a silicon mirror wafer with the test piece attached. This attachment is preferably carried out at room temperature, with an attachment speed of 290 to 310 mm/min and an attachment pressure of 0.3 MPa, using a laminating roller.
Next, the silicon mirror wafer with the test piece attached is left to stand for 30 minutes under a temperature of 23°C.
Next, at room temperature, the test specimen is peeled from the silicon mirror wafer at a peeling speed of 300 mm/min. At this time, the test specimen is peeled in its longitudinal direction so that the side of the silicon mirror wafer to which the test specimen was attached and the side of the test specimen to which the silicon mirror wafer was attached form a 180° angle, a so-called 180° peeling procedure. The load (peeling force) at the time of this 180° peeling is then measured, and the measurement length is set to 50 mm. The measurement values at the first 5 mm and the measurement values at the last 5 mm are excluded from the valid values. The average of these measurement values is then adopted as the adhesive force (X0) (mN/25 mm).
In this embodiment, such peeling force measurements may be performed on two or more test pieces (support sheets), and the average value of the multiple obtained measurements may be adopted as the adhesive force (X0).

<Method for adjusting the adhesive strength of the adhesive layer>
The various adhesive forces of the adhesive layer described above, namely the adhesive force between the energy-ray cured product of the adhesive layer after heating and the silicon mirror wafer (X1); the adhesive force between the adhesive layer after heating and the silicon mirror wafer (X2); the adhesive force between the energy-ray cured product of the adhesive layer after heating and the SUS plate (Y1); the adhesive force between the adhesive layer after heating and the SUS plate (Y2); and the adhesive force between the adhesive layer and the silicon mirror wafer (X0), can be adjusted by adjusting the type and content of the components contained in the adhesive layer.

For example, by incorporating an energy-curable acrylic resin (Ia) having constituent units derived from a functional group-containing monomer having a methacrylic group into the adhesive layer, the adhesive strength (X1) can be reduced.
For example, by incorporating an energy-ray curable acrylic resin (Ia) with a relatively high glass transition temperature into the adhesive layer, the adhesive strength (X1) can be reduced.
For example, when reacting a functional group (e.g., a hydroxyl group) in the acrylic polymer with a group in the unsaturated group-containing compound that can bond to the functional group (e.g., an isocyanate group in (meth)acryloyloxyethyl isocyanate), an energy-ray curable acrylic resin (Ia) can be prepared by setting the total number of moles of the group in the unsaturated group-containing compound that can bond to the functional group to a relatively large amount (e.g., 0.75 times or more) relative to the total number of moles of the functional group in the acrylic polymer. By incorporating such an energy-ray curable acrylic resin (Ia) into the adhesive layer, the adhesive strength (X1) can be reduced.

For example, by including an energy-ray curable compound (α) in the adhesive layer, the adhesive strength (X2) can be increased compared to when the energy-ray curable compound (α) is not included. However, by adjusting the type of energy-ray curable compound (α), the adhesive strength (X2) can be further 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 (e.g., an isocyanate group in (meth)acryloyloxyethyl isocyanate) in the unsaturated group-containing compound that can bond with the functional group, the adhesive strength (X2) can be increased by incorporating an energy-ray curable acrylic resin (Ia) in the adhesive layer that has fewer unreacted functional groups derived from the acrylic polymer (in other words, fewer functional groups that can react with the crosslinking agent (β)).
For example, the adhesive strength (X2) can be increased by reducing the amount of crosslinking agent (β) in the adhesive layer.

For example, by incorporating an energy-curable acrylic resin (Ia) having constituent units derived from a functional group-containing monomer having a methacrylic group into the adhesive layer, the adhesive strength (Y1) can be increased.
For example, by including an (meth)acrylic acid ester having an oxygen atom (-O-) as a substituent in the adhesive layer as an 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 (e.g., an isocyanate group in (meth)acryloyloxyethyl isocyanate) in the unsaturated group-containing compound that can bond with the functional group, the adhesive strength (Y1) can be increased by incorporating an energy-ray curable acrylic resin (Ia) in the adhesive layer that has fewer unreacted functional groups derived from the acrylic polymer (in other words, fewer functional groups that can react with the crosslinking agent (β)).
For example, the adhesive strength (Y1) can be increased by reducing the amount of crosslinking agent (β) in the adhesive layer.

For example, by including an energy-ray curable compound (α) in the adhesive layer, the adhesive strength (Y2) can be increased compared to when the energy-ray curable compound (α) is not included. Furthermore, the adhesive strength (Y2) can be increased even further 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 (e.g., an isocyanate group in (meth)acryloyloxyethyl isocyanate) in the unsaturated group-containing compound that can bond with the functional group, the adhesive strength (Y2) can be increased by incorporating an energy-ray curable acrylic resin (Ia) in the adhesive layer that has fewer unreacted functional groups derived from the acrylic polymer (in other words, fewer functional groups that can react with the crosslinking agent (β)).
For example, the adhesive strength (Y2) can be increased by reducing the amount of crosslinking agent (β) in the adhesive layer.

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 (e.g., an isocyanate group in (meth)acryloyloxyethyl isocyanate) that can bond to the functional group in the unsaturated group-containing compound, the adhesive strength (X0) can be increased by incorporating an energy-ray curable acrylic resin (Ia) in the adhesive layer that has fewer unreacted functional groups derived from the acrylic polymer (in other words, fewer functional groups that can react with the crosslinking agent (β)).
For example, the adhesive strength (X0) can be increased by reducing the amount of crosslinking agent (β) in the adhesive layer.

For example, in an adhesive layer containing an energy-curable compound (α), an energy-curable acrylic resin (Ia), and a crosslinking agent (β), using a crosslinking agent (β) with a chain structure that does not have a ring structure tends to increase the adhesive strength (Y2) and decrease the adhesive strength (X1) compared to using one with a ring structure.
For example, in an adhesive layer containing an energy-curable compound (α), an energy-curable acrylic resin (Ia), and a crosslinking agent (β), using a crosslinking agent (β) that has urethane bonds, such as a diisocyanate trimethylolpropane adduct, tends to increase the adhesive strength (Y2) and decrease the adhesive strength (X1) compared to using one that does not have urethane bonds.
For example, in an adhesive layer containing an energy-ray curable compound (α), an energy-ray curable acrylic resin (Ia), and a crosslinking agent (β), reducing the content of the energy-ray curable compound (α) can lower the adhesive strength (X1) compared to when the content is increased.

<Average light transmittance of the support sheet (400-800 nm)>
The average value of the light transmittance (400-800 nm) of the support sheet is preferably 80% or higher, and may be, for example, 82% or higher, or 84% or higher. When the average value of the light transmittance (400-800 nm) is above the lower limit, the inspection accuracy is improved when inspecting for damage such as cracks or chips (e.g., chipping) in the workpiece through the support sheet while the workpiece is held on the support sheet.
The upper limit of the average value of the light transmittance (400-800 nm) is not particularly limited. For example, a support sheet having an average value of 95% or less of the light transmittance (400-800 nm) can be manufactured more easily.
The average value of the aforementioned light transmittance (400-800 nm) may be, for example, 80-95%, 82-95%, or 84-95%. However, these are just examples of average values for the aforementioned light transmittance (400-800 nm).
However, in this specification, unless otherwise specified, the light transmittance of the support sheet refers not only to the light transmittance in the wavelength range of 400 to 800 nm, but also to the light transmittance of the support sheet without the release film.

The average value of the light transmittance (400-800 nm) of the support sheet can be calculated, for example, by the method shown below.
Specifically, light is shone onto the support sheet from the outside of the substrate side, and the light transmittance is measured by direct light reception without using an integrating sphere. The value of light transmittance T _n (where n is an integer between 400 and 800) is measured at 1 nm intervals in the wavelength range of 400 to 800 nm for each wavelength n (nm). Then, all T _n values for n between 400 and 800 are added together to calculate the total value T _{400 - 800.} By dividing the obtained T _{400 - 800} by the number of T _n measurements (i.e., 800 - 400 + 1 = 401) (T _{400 - 800} / 401), the average value of the light transmittance of the support sheet (400 to 800 nm) can be calculated.

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

<Example of a support sheet>
In addition to the adhesive strength (Y2) and adhesive strength (X1), it is preferable that one or more types selected from the group consisting of adhesive strength (X2), adhesive strength (Y1), and adhesive strength (X0) of the support sheet are within any of the above numerical ranges.
In other words, an example of a preferred support sheet is, for example, the following condition (1-1):
(1-1) The adhesive strength (Y2) between the heated adhesive layer and the SUS plate is 13,000 mN/25 mm or more.
And the following conditions (1-2):
(1-2) The adhesive force (X1) between the energy ray cured product of the adhesive layer after heating and the silicon mirror wafer is 400 mN/25 mm or less.
And, satisfying the following conditions (1-3) to (1-5):
(1-3) The adhesive force (X2) between the heated adhesive layer and the silicon mirror wafer is 13,000 mN/25 mm or more.
(1-4) The adhesive force (Y1) between the energy ray cured product of the adhesive layer after heating and the SUS plate is 300 mN/25 mm or more.
(1-5) The adhesive force (X0) between the adhesive layer and the silicon mirror wafer is 2000 mN/25 mm or more.
A support sheet that satisfies one or more conditions selected from the group consisting of the following:
A more preferable example of a support sheet is, for instance, a support sheet that satisfies all of the above conditions (1-1) to (1-5).
In the support sheet illustrated here, it is particularly preferable that one or more of the adhesive strengths selected from the group consisting of adhesive strength (X1), adhesive strength (X2), adhesive strength (Y1), adhesive strength (Y2), and adhesive strength (X0) are further limited to one of the numerical ranges described above.

◇Method for Manufacturing the Support Sheet The support sheet can be manufactured by laminating the aforementioned layers that constitute it in corresponding positional relationships, and adjusting the shape of some or all of the layers as necessary. The method for forming each layer is as described above.
For example, a support sheet can be manufactured by coating one side of a substrate (e.g., a matte side or a glossy side) with the above-mentioned adhesive composition (I) and drying it as necessary.

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

The pressure applied when bonding the adhesive layer to the substrate (bonding pressure) is preferably 0.2 to 0.6 MPa. A pressure above the lower limit ensures sufficient adhesion between the adhesive layer and the substrate. Furthermore, by adjusting the composition of the adhesive layer and providing it on the matte surface of the substrate, the embedding ability of the adhesive layer on the matte surface of the substrate can be further enhanced. A pressure below the upper limit avoids excessive pressure.
The bonding of such an adhesive layer to the substrate is preferably carried out under temperature conditions of 15°C or higher, but may also be carried out at room temperature.

A support sheet having the aforementioned other layer can be manufactured, for example, by applying a composition for forming the other layer to a suitable location on the substrate or adhesive layer, drying it as necessary, thereby forming the other layer, and then laminating any further necessary layers as needed. Alternatively, it can be manufactured by laminating a film-like other layer to a suitable location on the substrate or adhesive layer, thereby providing the other layer, and then laminating any further necessary 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 comprises the support sheet and a protective film forming film provided on the side of the adhesive layer in the support sheet opposite to the substrate side. More specifically, the composite sheet for forming a protective film comprises a substrate, an adhesive layer provided on one side of the substrate, and a protective film forming film provided on the side of the adhesive layer opposite to the substrate side. The composite sheet for forming a protective film may further include a release film provided on the side of the protective film forming film opposite to the adhesive layer side.

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

The protective film forming film may be curable or non-curable. That is, the protective film forming film may function as a protective film upon curing, or it may function as a protective film in an uncured state.
The curable protective film may be either thermosetting or energy ray curable, or it may possess both thermosetting and energy ray curable properties.

The protective film may consist of a single layer or two or more layers. If the protective film consists of multiple layers, these layers may be identical or different, and the combination of these layers is not particularly limited.

Examples of thermosetting protective film-forming films include those containing a polymer component (A) and a thermosetting component (B).
Examples of polymer component (A) include acrylic resin, urethane resin, phenoxy resin, silicone resin, saturated polyester resin, and the like.
Examples of the thermosetting component (B) include epoxy-based thermosetting resins, thermosetting polyimide resins, and unsaturated polyester resins.
In this specification, thermosetting polyimide resin is a general term encompassing a polyimide precursor and a thermosetting polyimide, both of which form a polyimide resin through thermosetting.
The epoxy-based thermosetting resin comprises an epoxy resin (B1) and a thermosetting agent (B2).

In addition to these components, the thermosetting protective film may further contain one or more substances 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).

Examples of energy-ray curable protective film-forming films include those containing 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 preferably contains, in addition to the energy-ray curable component (a), a polymer (b) that does not have energy-ray curable groups.
Examples of polymers (b) that do not have energy-ray curable groups include acrylic resins, urethane resins, phenoxy resins, silicone resins, and saturated polyester resins.

The energy-ray curable protective film may contain, in addition to the energy-ray curable component (a) and the polymer (b) that does not have energy-ray curable groups, one or more substances 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-curing protective film-forming films include those containing polymer components.
Examples of the polymer component include polymer component (A) mentioned above as a component of the thermosetting protective film, similar to non-curable resins.

The non-curing protective film may further contain, in addition to the polymer component, one or more substances 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. A protective film with higher protective capacity can be formed if the thickness of the protective film-forming film is greater than or equal to the lower limit. A protective film with excessive thickness can be avoided if the thickness of the protective film-forming film is less than or equal to the upper limit.
Here, "thickness of protective film" refers to the total thickness of the protective film. For example, the thickness of a protective film consisting of multiple layers refers to the total thickness of all the layers that make up the protective film.

A 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, an energy-ray curable protective film-forming composition for forming an energy-ray curable protective film, and a non-curable protective film-forming composition for forming a non-curable protective film). For example, a protective film-forming film can be formed by coating the target surface with the protective film-forming composition and drying it as needed. The ratio of components that do not vaporize at room temperature in the protective film-forming composition is usually the same as the ratio of those components in the protective film-forming film.

◇Method for Manufacturing a Composite Sheet for Forming a Protective Film The composite sheet for forming a protective film can be manufactured by laminating the above-mentioned layers that constitute it in corresponding positional relationships, and adjusting the shape of some or all of the layers as necessary. The method for forming each layer is as described above.
For example, a protective film-forming composition can be applied to one side of a release film and dried as necessary to form a protective film on the release film. A composite sheet for forming a protective film can then be manufactured by bonding the exposed side of this protective film-forming film (the side opposite to the release film side) to the exposed side of the adhesive layer in the support sheet (the side opposite to the substrate side). It is preferable to apply the protective film-forming composition to the release treatment side of the release film.

◇Manufacturing method for workpieces (Method of using support sheets)
The support sheet can be used in the manufacture of workpieces.
In other words, a method for manufacturing a workpiece according to one embodiment of the present invention includes: an attachment step of fixing a workpiece with a support sheet, comprising the workpiece and the support sheet provided on the workpiece, to the ring frame by attaching the adhesive layer in the support sheet to the workpiece and the ring frame; a heating step of heating the adhesive layer in the support sheet fixed to the ring frame after the attachment step; a processing step of manufacturing the workpiece by processing the workpiece in the workpiece with support sheet fixed to the ring frame after the attachment step; 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 pickup step of separating and picking up the workpiece from the cured adhesive layer after the curing step.

A manufacturing method for a workpiece when the workpiece is a semiconductor wafer, i.e., a manufacturing method for a semiconductor chip, includes the following steps: an attachment step of fixing a semiconductor wafer with a support sheet, comprising the semiconductor wafer and the support sheet provided on the semiconductor wafer, to the ring frame by attaching the adhesive layer in the support sheet to the semiconductor wafer and the ring frame; a heating step of heating the adhesive layer in the support sheet fixed to the ring frame after the attachment step; a processing step of producing the semiconductor chip by dividing the semiconductor wafer in the semiconductor wafer with support sheet fixed to the ring frame after the attachment step; 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 pickup step of separating and picking up the semiconductor chip from the cured adhesive layer after the curing step.

The order in which the heating and processing steps are performed after the application step can be arbitrarily selected according to the purpose. For example, the heating step may be performed before the processing step, or the processing step may be performed before the heating step. For example, in the manufacturing method, the heating step may 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. Also, in the manufacturing method, after washing and removing fine foreign matter that is generated during processing such as dicing of the workpiece and adheres to the surface of the workpiece with water, the heating step may be performed to dry the workpiece. In this case, the heating step is performed after the processing step. Furthermore, in the manufacturing method, the heating step for removing these foreign matter and the heating step for drying may be performed together, or these heating steps may be performed in a single step.

<<An example of a manufacturing method for workpieces>>
Figure 2 is a schematic cross-sectional view illustrating an example of the manufacturing method when the workpiece is a semiconductor wafer. Here, we will describe the manufacturing method using the support sheet 1 shown in Figure 1.

<Application Process>
In the aforementioned attachment process, the 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) and the ring frame 8, thereby fixing the semiconductor wafer 109 with a support sheet, which comprises 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 semiconductor wafer 109 with a support sheet is the workpiece with a support sheet.
The support sheet 1 is used after removing the release film 13. The side 12a of the adhesive layer 12 opposite to the substrate 11 is the same as one side 1a of the support sheet 1 (the side facing the adhesive layer 12).
In Figure 2, bumps and other features on the circuit surface 9a of the semiconductor wafer 9 are omitted from the illustration.

In the bonding process, the central portion of the adhesive layer 12 in its width direction is bonded to the semiconductor wafer 9, and the surrounding portion is bonded to the ring frame 8.

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

<Heating process>
After the bonding step, in the heating step, as shown in Figure 2(b), the adhesive layer 12 in the support sheet 1 fixed to the ring frame 8 is heated. In this case, heating of the adhesive layer 12 is associated with heating the entire semiconductor wafer 109 with the support sheet attached, and this heating allows for the removal of foreign substances such as low molecular weight resin components adhering to the surface of the semiconductor wafer 9 (for example, the circuit surface 9a) by volatilization.

The heating temperature of the adhesive layer 12 (i.e., the adhesive layer 12 on the semiconductor wafer 109 with the support sheet) 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, suppressing, for example, the degradation of the semiconductor wafer 109 with the support sheet.

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

<Processing process>
After the bonding and heating steps, in the processing step, as shown in Figure 2(c), the semiconductor wafer 9 in the heated semiconductor wafer 109 with a support sheet fixed to the ring frame 8 is divided to produce a semiconductor chip 90, which is the workpiece. The processing step yields a semiconductor chip group 901 with a support sheet, in which multiple semiconductor chips 90 are aligned and held on a single support sheet 1.

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

The semiconductor wafer 9 can be divided by known methods. For example, the semiconductor wafer 9 can be divided by various dicing methods such as blade dicing using a blade, laser dicing using laser irradiation, or water dicing by spraying water containing an abrasive.
Furthermore, the semiconductor wafer 9 can also be divided by using a semiconductor wafer 9 that has a modified layer formed by stealth dicing (registered trademark) and has not been divided, and by expanding the semiconductor wafer 9 in a direction parallel to its circuit surface 9a or back surface 9b.

Stealth dicing (registered trademark) is a method described below. First, a section to be divided is designated within the semiconductor wafer. A laser beam is then focused onto this section, creating a modified layer within the wafer. Unlike other parts of the wafer, this modified layer is altered by the laser beam, resulting in reduced strength. Therefore, when force is applied to the wafer, cracks extending in both directions occur within the modified layer, becoming the starting point for the wafer's division (cutting). Next, force is applied to the wafer to divide it at the modified layer, thereby creating a semiconductor chip.

If the adhesive strength (X2) of the support sheet 1 is 13,000 mN/25 mm or more, then even after heating the support sheet 1 with the semiconductor wafer 9 attached (in other words, the semiconductor wafer 109 with the support sheet attached) at a high temperature with an upper limit of approximately 135°C during the heating process, peeling of the semiconductor chip 90 from the support sheet 1 (adhesive layer 12) will be suppressed, even if a large force is applied to the semiconductor chip 90 during the processing process, such as by splitting the semiconductor wafer 9 or washing the semiconductor chip 90 with water.

In the support sheet 1, if the adhesive force (X0) is 2000 mN/25 mm or more, even if a large force is applied to the semiconductor chip 90 during the processing step—for example, by rapidly dividing the semiconductor wafer 9 into small semiconductor chips 90, or by washing the small semiconductor chips 90, which have a lot of cutting debris attached, with high-pressure water—peeling of the semiconductor chip 90 from the support sheet 1 (adhesive layer 12) is suppressed.

<Curing process>
After the heating and processing steps, in the curing step, as shown in Figure 2(d), the adhesive layer 12 attached to the ring frame 8 is cured by energy rays. The curing step yields 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 adhesive layer 12 is cured by energy rays, becoming an energy ray cured product 12'.
The semiconductor chip group 901' with a cured support sheet is a laminate of the workpiece and the cured support sheet as described above (in other words, a workpiece with a cured support sheet), and is the same as the semiconductor chip group 901 with a support sheet, except that the adhesive layer 12 is its energy ray cured product 12'.

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

In the case of the support sheet 1, if the adhesive strength (Y1) is 300 mN/25 mm or more, even if the semiconductor wafer 109 with the support sheet is heated while fixed to the ring frame 8 during the heating process, and even if energy rays are irradiated to the contact portion of the support sheet 1 (adhesive layer 12) with the ring frame 8 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 process, in the pickup process, as shown in Figure 2(e), the semiconductor chip 90 can be separated and picked up from the energy ray cured product 12' of the adhesive layer in the cured support sheet 1', thereby allowing the target semiconductor chip 90 to be extracted from the group of semiconductor chips 901' with the cured support sheet. Here, the direction of pickup is indicated by arrow P.

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

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

In the support sheet 1, the adhesive strength (X1) is 400 mN/25 mm or less. Therefore, even after heating the support sheet 1 with the semiconductor wafer 9 attached (in other words, the semiconductor wafer 109 with the support sheet attached) at a high temperature with an upper limit of approximately 135°C during the heating process, the semiconductor chip 90 can be fabricated from the semiconductor wafer 9 on the support sheet 1, and the semiconductor chip 90 can be normally picked up from the cured support sheet 1', resulting in high pickability.

<Other processes>
The above manufacturing method may include other steps that do not fall under any of the following categories: the bonding step, the heating step, the processing step, the curing step, or the picking step.
The types of other processes, the number of other processes, and the timing of performing these other processes can all be arbitrarily selected according to the purpose and are not particularly limited.

<<Other examples of workpiece manufacturing methods>>
Up to this point, we have described a method for manufacturing a workpiece in which the bonding process, heating process, processing process, curing process, and pickup process are performed in that order (hereinafter sometimes referred to as "manufacturing method (1)"). However, the method for manufacturing a workpiece in this embodiment is not limited to this (manufacturing method (1)). For example, in the above manufacturing method, as described above, the order in which the heating process and processing process are performed may be reversed.

<Application Process>
In this method of manufacturing a workpiece (hereinafter sometimes referred to as "manufacturing method (2)"), first, an adhesive process is performed. The adhesive process in manufacturing method (2) is the same as the adhesive process in manufacturing method (1).

<Processing process>
In the processing step, following the bonding step in manufacturing method (2), a semiconductor chip, which is the workpiece, is produced by dividing the semiconductor wafer in the unheated semiconductor wafer with a support sheet fixed to the ring frame. The processing step yields a group of semiconductor chips with support sheets, which is the same as in manufacturing method (1), except that they are not heated.

In the support sheet, if the adhesive strength (X0) is 2000 mN/25 mm or more, even if a large force is applied to the semiconductor chip during the processing step—for example, by rapidly dividing the semiconductor wafer into small semiconductor chips, or by washing the resulting small semiconductor chips, which have a large amount of cutting debris attached, with high-pressure water—peeling of the semiconductor chip from the support sheet (adhesive layer) is suppressed.

<Heating process>
In the heating step, after the bonding and processing steps of manufacturing method (2), the adhesive layer in the support sheet fixed to the ring frame is heated. In this case, heating of the adhesive layer is associated with heating the entire semiconductor chip group with the support sheet. This heating allows for the removal of foreign matter, such as low molecular weight resin components adhering to the surface of the semiconductor chip (e.g., the circuit side), by volatilization. Furthermore, after washing and removing fine foreign matter generated during semiconductor wafer dicing and adhering to the surface of the semiconductor chip with water, the semiconductor chip can be dried by this heating. The heating step yields a semiconductor chip group with a support sheet similar to that of manufacturing method (1).

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

In the case of the support sheet, if the adhesive strength (X2) is 13,000 mN/25 mm or more, then in the heating process, even if a large force is applied to the semiconductor chip after heating the support sheet with the semiconductor chip attached (in other words, the group of semiconductor chips with the support sheet) at a high temperature with an upper limit of approximately 135°C, the peeling of the semiconductor chip from the support sheet (adhesive layer) is suppressed.

<Curing process>
After the heating step and processing step of manufacturing method (2), the curing step can be performed in the same manner as in manufacturing method (1), and the curing step yields a group of semiconductor chips with cured support sheets in the same manner as in manufacturing method (1).

In the case of the support sheet, if the adhesive strength (Y1) is 300 mN/25 mm or more, then during the heating process, the support sheet with the semiconductor chips attached (in other words, the group of semiconductor chips with the support sheet) is heated while fixed to the ring frame. Furthermore, even if energy rays are irradiated onto the contact portion of the support sheet (adhesive layer) with the ring frame during the curing process, peeling of the cured support sheet with semiconductor chips from the ring frame is suppressed.

<Pickup Process>
After the curing step in manufacturing method (2), the pickup step can be performed in the same manner as in manufacturing method (1), and the target semiconductor chip can be extracted by the pickup step in the same manner as in manufacturing method (1).

In the support sheet, if the adhesive strength (X1) is 400 mN/25 mm or less, even after heating the semiconductor chip group with the support sheet at a high temperature with an upper limit of approximately 135°C during the heating process, the semiconductor chips can be normally picked up from the cured support sheet, resulting in high pickability.

<Other processes>
Manufacturing method (2) may include other steps similar to those in manufacturing method (1).
In manufacturing method (2), the type of other process, the number of other processes, and the timing of performing the other processes can all be arbitrarily selected according to the purpose and are not particularly limited.

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

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

<Raw materials for the manufacture of adhesive composition (I)>
The raw materials used in the production of the adhesive composition (I) in this example and comparative example are as follows.
The viscosity of the four crosslinking agents (β) at 23°C was measured using a Viscotec digital rotational viscometer, "ViscoLead Advance".
[Energy ray curable compound (α)]
(α)-1:2-(2-phenoxyethoxy)ethyl acrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., "AMP-20GY", 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, manufactured by Shin Nakamura Chemical Industry Co., Ltd., "A-DOG", viscosity at 23°C 310 mPa·s, molecular weight 326.4)
[Crosslinking agent (β)]
(β)-1:1,6-hexamethylene diisocyanate trimethylolpropane adduct (Tosoh Corporation's "Coronate HL")
(β)-2: Isocyanurate modified form of hexamethylene diisocyanate (Tosoh Corporation's "Coronate HX")
[Photopolymerization initiator (γ)]
(γ)-1:2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one (Omnirad® 127, manufactured by IGM Resins)

Furthermore, both energy-ray curable compounds (α)-1 and (α)-3 are substituted acrylic acid esters. In energy-ray curable compound (α)-1, the hydrocarbon group derived from the alcohol has two substituents and the hydrocarbon group has 12 carbon atoms. In energy-ray curable compound (α)-3, the hydrocarbon group derived from the 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 without substituents. In the energy-ray curable compound (α)-2, the hydrocarbon group derived from the alcohol has 12 carbon atoms.

[Example 1]
<<Manufacturing of support sheets>>
<Manufacturing of energy-ray curable acrylic resin (Ia)>
An energy-ray curable acrylic resin (Ia)-1 was obtained by adding MOI to an acrylic polymer (1) and carrying out an addition reaction at 50°C for 48 hours in an air stream. The acrylic polymer (1) is 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 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 weight-average molecular weight of the obtained energy-ray curable acrylic resin (Ia)-1 was 440,000, and the glass transition temperature was -26°C.

<Manufacturing of adhesive composition (I)>
An energy-ray-curable 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 content of all components other than methyl ethyl ketone shown herein is the content of the target product excluding the solvent.

<Formation of the adhesive layer>
A release film (second release film) made of polyethylene terephthalate film, in which one side was peeled off by silicone treatment, was used. The adhesive composition (I)-1 obtained above was applied to the peeled-off surface, and the film was heated and dried at 100°C for 2 minutes to form an energy-ray curable adhesive layer with a thickness of 15 μm.

<Manufacturing of support sheets>
Next, at room temperature, a polypropylene film (manufactured by Dia Plus Film Co., Ltd., 80 μm thick) was bonded to the exposed surface of the adhesive layer at a bonding speed of 5 m/min and under 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 fine matte surface with a surface roughness (Ra) of 0.12 μm. The adhesive layer was then bonded to the matte surface of this polypropylene film.
Based on the above, the desired support sheet was obtained.

<<Evaluation of the support sheet>>
<Measurement of adhesive strength (X1) between the energy ray cured adhesive layer after heating and the silicon mirror wafer>
A test piece with a width of 25 mm was cut from the support sheet obtained above.
Under bonding temperature conditions of 23°C (laminating roller temperature 23°C, silicon mirror wafer temperature 23°C), with a bonding speed of 300 mm/min and a bonding pressure of 0.3 MPa, the test piece was bonded to the mirror surface of a silicon mirror wafer (thickness 650 nm) using the adhesive layer within it, thereby obtaining a silicon mirror wafer with the test piece attached. This silicon mirror wafer with the test piece attached was placed inside an oven heated to 130°C and heated at this temperature (130°C) for 2 hours.
Next, the silicon mirror wafer with the test specimen attached was removed from the oven and cooled to 23°C by air cooling. Then, using an ultraviolet irradiation device (Lintec RAD-2000UV), ultraviolet light was irradiated onto the adhesive layer in the removed silicon mirror wafer with the test specimen attached through the substrate under conditions of illuminance of 230 mW/ ^{cm² and} light intensity of 200 mJ/cm², thereby UV curing the adhesive layer in the test specimen.

Next, under conditions of 23°C, the test specimen was peeled from the silicon mirror wafer at a peeling speed of 300 mm/min. At this time, the test specimen was peeled in its longitudinal direction such that the surface of the silicon mirror wafer to which the test specimen was attached and the surface of the test specimen to which the silicon mirror wafer was attached formed an angle of 180° (180° peeling was performed). The load (peeling force) at the time of this 180° peeling was measured, and the measurement length was set to 50 mm. The measurement values for the first 5 mm and the measurement values for the last 5 mm were excluded from the valid values. The average of these measurement values was then adopted as the adhesive strength (mN/25 mm).
The adhesive strength was measured twice, and the average value was adopted as the adhesive strength (X1) (mN/25mm) between the energy-ray cured adhesive layer after heating and the silicon mirror wafer. The results are shown in Table 1.

<Measurement of adhesive strength (X2) between the adhesive layer and the silicon mirror wafer after heating>
A silicon mirror wafer with a test piece attached was prepared using the same method as when measuring the adhesive strength (X1) described above, heated at 130°C for 2 hours, and then cooled by air until its temperature reached 23°C.
Next, under conditions of 23°C, the test specimen was peeled off the cooled silicon mirror wafer at a peeling speed of 300 mm/min. At this time, the test specimen was peeled in its longitudinal direction such that the surface of the silicon mirror wafer to which the test specimen was attached and the surface of the test specimen to which the silicon mirror wafer was attached formed an angle of 180° (180° peeling was performed). The load (peeling force) at the time of this 180° peeling was measured, and the measurement length was set to 50 mm. The measurement values for the first 5 mm and the measurement values for the last 5 mm were excluded from the valid values. The average of these measurement values was then adopted as the adhesive strength (mN/25 mm).
The adhesive strength was measured twice, and the average value was adopted as the adhesive strength (X2) (mN/25mm) between the heated adhesive layer and the silicon mirror wafer. The results are shown in Table 1.

<Measurement of adhesive strength (Y1) between the energy-ray cured adhesive layer after heating and the SUS plate>
A SUS plate with a test piece attached was obtained in the same manner as when measuring the adhesive strength (X1) described above, except that the test piece was attached to the #1200 polished surface of a SUS plate (Paltec Co., Ltd. "SUS304 #1200HL, thickness 1000 μm, size 70 mm x 150 mm") instead of the mirror surface of the silicon mirror wafer.
Next, the SUS plate with the test specimen attached was heated at 130°C for 2 hours in the same manner as when measuring the adhesive strength (X1) with the silicon mirror wafer attached, then cooled to 23°C by air cooling, and the adhesive layer in the SUS plate with the test specimen was cured by ultraviolet light by irradiating it through the substrate.

Next, under conditions of 23°C, the test specimen was peeled from the SUS plate at a peeling speed of 300 mm/min. At this time, the test specimen was peeled in its longitudinal direction such that the surface of the SUS plate to which the test specimen was attached and the surface of the test specimen to which the SUS plate was attached formed an angle of 180° (180° peeling was performed). The load (peeling force) at the time of this 180° peeling was measured, and the measurement length was set to 50 mm. The measurement values for the first 5 mm and the measurement values for the last 5 mm were excluded from the valid values. The average of these measurement values was then adopted as the adhesive strength (mN/25 mm).
The adhesive strength was measured twice, and the average value was adopted as the adhesive strength (Y1) (mN/25mm) between the energy-ray cured adhesive layer after heating and the SUS plate. The results are shown in Table 1.

<Measurement of adhesive strength (Y2) between the adhesive layer and the SUS plate after heating>
Using the same method as when measuring the adhesive strength (Y1) described above, a SUS plate with a test piece attached was prepared, heated at 130°C for 2 hours, and then cooled by air until its temperature reached 23°C.
Next, under conditions of 23°C, the test specimen was peeled off the cooled SUS plate at a peeling speed of 300 mm/min. At this time, the test specimen was peeled in its longitudinal direction such that the surface of the SUS plate to which the test specimen was attached and the surface of the test specimen to which the SUS plate was attached formed an angle of 180° (180° peeling was performed). The load (peeling force) at the time of this 180° peeling was measured, and the measurement length was set to 50 mm. The measurement values for the first 5 mm and the measurement values for the last 5 mm were excluded from the valid values. The average of these measurement values was then adopted as the adhesive strength (mN/25 mm).
The adhesive strength was measured twice, and the average value was adopted as the adhesive strength (Y2) (mN/25mm) between the heated adhesive layer and the SUS plate. The results are shown in Table 1.

<Measurement of adhesive strength (X0) between the adhesive layer and the silicon mirror wafer>
A silicon mirror wafer with a test piece attached was prepared using the same method as when measuring the adhesive strength (X1) described above.
Next, the silicon mirror wafer with the test piece attached was left to stand for 30 minutes under a temperature of 23°C.
Next, under conditions of 23°C, the test specimen was peeled off the silicon mirror wafer after static storage at a peeling speed of 300 mm/min. At this time, the test specimen was peeled in its longitudinal direction such that the surface of the silicon mirror wafer to which the test specimen was attached and the surface of the test specimen to which the silicon mirror wafer was attached formed an angle of 180° (180° peeling was performed). The load (peeling force) at the time of this 180° peeling was measured, and the measurement length was set to 50 mm. The measurement values for the first 5 mm and the measurement values for the last 5 mm were excluded from the valid values. The average of these measurement values was then adopted as the adhesive strength (mN/25 mm).
The adhesive strength was measured twice, and the average value was adopted as the adhesive strength (X0) (mN/25mm) between the adhesive layer and the silicon mirror wafer. The results are shown in Table 1.

<Calculation of the average light transmittance (400-800 nm) of the support sheet>
Using a UV-vis measuring device (Shimadzu Corporation's "UV-vis-NIR3600"), the light transmittance of the support sheet obtained above was measured by irradiating it with light from the outside of the substrate side and receiving the light directly without using an integrating sphere. The wavelength range for this measurement was 190 to 2000 nm. The light transmittance values were then added up for every 1 nm in the visible light wavelength range of 400 to 800 nm, and the average value (%) of the light transmittance of the support sheet (400 to 800 nm) was calculated by dividing the sum by the number of added light transmittance values (i.e., 800 - 400 + 1 = 401). The results are shown in Table 1.

<Evaluation of the effect of suppressing the peeling of the support sheet from the ring frame after heating>
A 12-inch silicon wafer (500 μm thick) was prepared. Of the adhesive layer in the support sheet obtained above, the central region in the width direction was attached to this silicon wafer, and the region surrounding the area attached to the silicon wafer was attached to the ring frame. At this time, the adhesive layer was attached to the silicon wafer and ring frame under the following conditions: attachment temperature of 23°C (laminate roller temperature 23°C, silicon wafer temperature 23°C), attachment speed of 300 mm/min, and attachment pressure of 0.3 MPa. In this way, the silicon wafer with the support sheet, which consisted of the silicon wafer and the support sheet provided on one side of the silicon wafer, was fixed to the ring frame.
Next, the silicon wafer with the support sheet fixed to the ring frame was placed inside the oven. At this time, the silicon wafer with the support sheet fixed to the ring frame was positioned so that the exposed surface of the silicon wafer (the side opposite to the side with the support sheet) was horizontal, and in this state, it was heated at 130°C for 2 hours.

Next, the silicon wafer with the support sheet fixed to the ring frame was removed from the oven, and the presence or absence of delamination of the support sheet from the ring frame, and if delamination occurred, the degree of delamination, was visually checked from the substrate side of the support sheet. When the silicon wafer with the support sheet fixed to the ring frame is in the above arrangement, the support sheet delaminates from the inner circumference of the ring frame. Therefore, if delamination of the support sheet from the ring frame occurred, the delamination site with the maximum distance from the inner circumference of the ring frame to the edge of the delamination site of the support sheet was identified, i.e., the delamination site with the maximum delamination distance. In addition to the presence or absence of delamination, the effect of suppressing delamination of the support sheet from the ring frame after heating was evaluated according to the following criteria based on this maximum delamination distance. The results are shown in Table 1.
(Evaluation criteria)
A: There is no peeling of the support sheet from the ring frame, or if there is peeling, the maximum peeling distance is 2 mm or less, indicating a high level of peeling suppression effect.
B: There is delamination of the support sheet from the ring frame, and the maximum delamination distance is greater than 2 mm but less than or equal to 5 mm, indicating a low delamination suppression effect.
C: There is delamination of the support sheet from the ring frame, with a maximum delamination distance exceeding 5 mm, indicating a particularly low delamination suppression effect.

<Evaluation of the pickability of silicon chips on the support sheet>
(Manufacturing of silicon chip groups with support sheets)
An 8-inch silicon wafer (350 μm thick) with one side polished to #2000 grit was prepared. Of the adhesive layer in the support sheet obtained above, the central region in the width direction was attached to this silicon wafer, and the region surrounding the area attached to the silicon wafer was attached to the ring frame. At this time, the attachment of the adhesive layer to the silicon wafer and ring frame was performed under attachment temperature conditions of 23°C (laminate roller temperature 23°C, silicon wafer temperature 23°C), with an attachment speed of 300 mm/min and an attachment pressure of 0.3 MPa. In this way, the silicon wafer with the support sheet, which consisted of the silicon wafer and the support sheet provided on one side of the silicon wafer, was fixed to the ring frame (attachment process).
Next, the silicon wafer with the support sheet fixed to the ring frame was placed inside the oven and heated at 130°C for 2 hours (heating step). At this time, the silicon wafer with the support sheet fixed to the ring frame was positioned inside the oven so that the exposed surface of the silicon wafer (the side opposite to the side with the support sheet) was horizontal.

Next, the silicon wafer with the support sheet fixed to the ring frame was removed from the oven and cooled to 23°C by air cooling. Then, using a dicing device (DISCO "DFD6362"), multiple silicon chips measuring 3 mm x 3 mm were produced by dicing the silicon wafer within the silicon wafer with the support sheet fixed to the ring frame (processing step). At this time, a DISCO "ZH05-SD2000-N1-90 CC" was used as the dicing blade, with a blade rotation speed of 35,000 rpm, a blade feed rate of 30 mm/s, and a blade height of 0.06 mm. The blade was inserted into the silicon wafer with the support sheet from the silicon wafer side surface and cut to a depth of 20 μm from the adhesive layer side surface of the substrate.
Based on the above, a group of silicon chips with a support sheet was fabricated, in which multiple silicon chips are aligned and held on a single support sheet.

(Evaluation of the pickability of the silicon chip on the support sheet)
Next, using an ultraviolet irradiation device (Lintec RAD-2000UV), ultraviolet light was irradiated onto the adhesive layer in the group of silicone chips with support sheets from outside the substrate side, through the substrate, under conditions of illuminance 230 mW/ ^cm² and light intensity 200 mJ/ ^cm² , thereby UV curing the adhesive layer attached to the ring frame (curing process).
Next, using a pickup die bonding apparatus (Canon Machinery Co., Ltd. "BESTEM D-510"), the silicon chips from the group of silicon chips with cured support sheets were picked up by separating them from the cured adhesive layer under the following pickup conditions (pickup process). This pickup was performed on a total of 100 silicon chips from the group of silicon chips with cured support sheets, in areas of 10 rows in two orthogonal directions, divided from the center and its vicinity on the silicon wafer before dicing. Each silicon chip was picked up by pushing it up from the support sheet side with a single pin. The pickability of the support sheet was then evaluated according to the following criteria. The results are shown in Table 1.
(Pickup conditions)
Upward thrust speed: 5 mm/s
Expansion amount: 4 mm
Radius of curvature at the tip of the pin: 0.75 mm
(Evaluation criteria)
A: All (100) silicon chips were successfully picked up.
B: 1 to 4 silicon chips could not be picked up successfully, but all other silicon chips (96 to 99) were picked up successfully.
C: Failed to successfully pick up 5 or more silicon chips.

[Example 2]
<<Manufacturing and evaluation of support sheets>>
An energy-ray curable 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 the crosslinking agent (β)-1 content was 1.33 parts by mass instead of 1.17 parts by mass. Then, a support sheet was manufactured and evaluated in the same manner as in Example 1, except that adhesive composition (I)-2 was used instead of adhesive composition (I)-1. The results are shown in Table 1.

[Example 3]
<<Manufacturing and evaluation of support sheets>>
Energy-ray curable adhesive composition (I)-3 was prepared, having 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 the crosslinking agent (β)-1 content was 1.33 parts by mass instead of 1.17 parts by mass. Then, a support sheet was manufactured and evaluated in the same manner as in Example 1, except that adhesive composition (I)-3 was used instead of adhesive composition (I)-1. The results are shown in Table 1.

[Reference example 1]
<<Manufacturing of support sheets>>
<Manufacturing of energy-ray curable acrylic resin (Ia)>
An addition reaction was carried out in an air stream at 50°C for 48 hours by adding MOI to the acrylic polymer (1) to obtain an energy-ray curable acrylic resin (Ia)-2. The amount of MOI used was such that the total number of isocyanate groups in the MOI was 0.785 times the total number of hydroxyl groups derived from HEMA in the acrylic polymer (1). The weight-average molecular weight of the obtained energy-ray curable acrylic resin (Ia)-2 was 500,000, and the glass transition temperature was -26°C.

<Manufacturing of adhesive composition (I)>
An energy-ray-curable adhesive composition (R)-1 was prepared, containing an energy-ray-curable acrylic resin (Ia)-2 (100 parts by mass), an energy-ray-curable compound (α)-1 (25 parts by mass), a crosslinking agent (β)-2 (4.12 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 content of all components other than methyl ethyl ketone shown herein is the content of the target product excluding the solvent.

<Manufacturing of support sheets>
The support sheet was manufactured in the same manner as in Example 1, except that adhesive composition (R)-1 was used instead of adhesive composition (I)-1.

<<Evaluation of the support sheet>>
The support sheets obtained above were evaluated using the same method as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
<<Manufacturing of support sheets>>
<Manufacturing of adhesive compositions>
An energy-ray-curable adhesive composition (R)-2 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 content of components other than methyl ethyl ketone shown herein is the content of the target product excluding the solvent.

<Manufacturing of support sheets>
The support sheet was manufactured in the same manner as in Example 1, except that adhesive composition (R)-2 was used instead of adhesive composition (I)-1.

<<Evaluation of the support sheet>>
The support sheets obtained above were evaluated using the same method as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
<<Manufacturing of support sheets>>
<Manufacturing of energy-ray curable acrylic resin (Ia)>
Energy-ray curable acrylic resin (Ia)-3 was obtained by adding MOI to acrylic polymer (2) and carrying out an addition reaction at 50°C for 48 hours in an air stream. The acrylic polymer (2) is 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 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.

<Manufacturing of adhesive compositions>
An energy-ray-curable adhesive composition (R)-3 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 content of components other than methyl ethyl ketone shown herein is the content of the target product excluding the solvent.

<Manufacturing of support sheets>
The support sheet was manufactured in the same manner as in Example 1, except that adhesive composition (R)-3 was used instead of adhesive composition (I)-1.

<<Evaluation of the support sheet>>
The support sheets obtained above were evaluated using the same method as in Example 1. The results are shown in Table 1.

As is clear from the results above, in Examples 1 to 3, the adhesive force (Y2) was 15,600 mN/25 mm or more, which is sufficiently large. Reflecting this, even when the silicon wafer with the support sheet fixed to the ring frame was heated at a high temperature, the peeling of the support sheet from the ring frame was suppressed to a high degree, indicating a high peeling suppression effect.
Furthermore, in Examples 1 to 3, the adhesive strength (X1) was 200 mN/25 mm or less, and even after heating the support sheet with the silicon mirror wafer attached at 130°C for 2 hours, almost all of the silicon chips could be picked up normally, indicating high pick-up performance.
Thus, the support sheets of Examples 1 to 3 possessed the desired characteristics.

In Examples 1-3, the 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 could be easily achieved. In particular, it was presumed that the presence of a specific structural range in the energy-ray curable compound (α) further facilitated the achievement of these properties. Furthermore, in Examples 1-3, the presence of a specific structural range in the crosslinking agent (β) also facilitated the achievement of these properties even more.

Furthermore, in Examples 1 to 3, the adhesive force (X2) was 15,000 mN/25 mm or more, which was sufficiently large. Even when a large force was applied to the silicon chips during processes such as dicing the silicon mirror wafer or washing the silicon chips with water after heating the silicon wafer with the support sheet at a high temperature, the peeling of the silicon chips from the support sheet was suppressed.
Furthermore, in Examples 1 to 3, the adhesive force (X0) was 2900 mN/25 mm or more, which is sufficiently large. It was therefore inferred that even when a significantly large force is applied to the silicon chip, such as during high-speed dicing of the silicon mirror wafer or high-pressure water washing of the silicon chip after dicing, peeling of the silicon chip from the support sheet can be suppressed.

In particular, in Examples 1 and 2, the adhesive strength (Y1) was remarkably high, exceeding 470 mN/25 mm. It was hypothesized that even if energy rays were irradiated onto the contact area between the support sheet (adhesive layer) and the ring frame after the silicon wafer with the support sheet in Examples 1 and 2 was fixed to the ring frame and heated, the peeling of the cured support sheet-attached silicon chip group from the ring frame could be suppressed.

Furthermore, in Examples 1 to 3, the average light transmittance (400-800 nm) of the support sheet was 81.4% or higher, which was sufficiently high and exhibited desirable characteristics.

Thus, the support sheets of Examples 1-3 were preferable because they also exhibited superior properties beyond the intended purpose.

In contrast, in Reference Example 1, the adhesive strength (Y2) was low, and reflecting this, the effect of suppressing the peeling of the support sheet from the ring frame after heating the silicon wafer with the support sheet fixed to the ring frame at a high temperature was particularly low.
Furthermore, in Reference Example 1, the adhesive strength (X1) was 350 mN/25 mm, and the pickability of the silicon chip after heating the support sheet with the silicon mirror wafer attached at 130°C for 2 hours was inferior to that of Examples 1 to 3.

Furthermore, in Reference Example 1, the adhesive force (X2) was low, and it was inferred that 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 during dicing of the silicon mirror wafer or washing of the silicon chip after dicing, the peeling of the silicon chip from the support sheet could not be suppressed.
Furthermore, in Reference Example 1, the adhesive force (X0) was small, and it was inferred that even when a significantly large force was applied to the silicon chip, such as during high-speed dicing of the silicon mirror wafer or high-pressure water washing of the silicon chip after dicing, the peeling of the silicon chip from the support sheet could not be suppressed.

In Comparative Examples 1 and 2, the adhesive strength (Y2) was 12,000 mN/25 mm or less, which was low. Reflecting this, the effect of suppressing the peeling of the support sheet from the ring frame after heating the silicon wafer with the support sheet fixed to the ring frame at a high temperature was low.
In Comparative Examples 1 and 2, the energy ray-curable compound (α) was not used.

In addition, in Comparative Example 2, the adhesive strength (X1) was high, and after heating the support sheet with the silicon mirror wafer attached at 130°C for 2 hours, the silicon chip could not be picked up properly, indicating poor pick-up performance.

Furthermore, in Comparative Example 1, the adhesive strength (Y1) was also insufficient, and it was inferred that this support sheet was insufficient in suppressing peeling from the ring frame, even in the state of the silicone chip group with the cured support sheet attached.
Furthermore, in Comparative Example 2, the adhesive strength (X2) was low, and it was inferred that the effect of suppressing the peeling of the silicon chip 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 during dicing of the silicon mirror wafer or washing of the silicon chip after dicing.

This invention can be used in the manufacturing of workpieces such as semiconductor chips.

1...Support sheet, 11...Substrate, 11a...One side of the substrate, 12...Adhesive layer, 12'...Energy ray cured product, 8...Ring frame, 9...Semiconductor wafer, 90...Semiconductor chip, 109...Semiconductor wafer with support sheet

Claims (5)

It is a support sheet,
The support sheet comprises a base material and an adhesive layer provided on one surface of the base material.
The adhesive layer is energy ray curable,
The support sheet is attached to the surface of the stainless steel plate using the adhesive layer, the adhesive layer is heated to 130°C after attachment, and the adhesive force (Y2) between the heated adhesive layer and the stainless steel plate is measured, and the adhesive force (Y2) is 13,000 mN/25 mm or more.
The support sheet is attached to the mirror surface of the silicon mirror wafer by the adhesive layer, the adhesive layer is heated to 130°C after attachment, the heated adhesive layer is energy-ray cured, and the adhesive force (X1) between the energy-ray cured adhesive layer and the silicon mirror wafer is measured, and the adhesive force (X1) is 400 mN/25 mm or less.
A support sheet wherein the support sheet is attached to the mirror surface of a silicon mirror wafer by the adhesive layer, the adhesive layer is heated to 130°C after attachment, and the adhesive force (X2) between the heated adhesive layer and the silicon mirror wafer is measured, and the adhesive force (X2) is 13,000 mN/25 mm or more . 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 the support sheet is attached to the surface of a stainless steel plate using the adhesive layer, the adhesive layer is heated to 130°C after attachment, the adhesive layer is energy-ray cured after heating, and the adhesive force (Y1) between the energy-ray cured adhesive layer and the stainless steel plate is measured, and the adhesive force (Y1) is 300 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 mirror surface of a silicon mirror wafer by the adhesive layer, the silicon mirror wafer equipped with the support sheet is left standing for 30 minutes under a temperature of 23°C, and the adhesive force (X0) between the adhesive layer and the silicon mirror wafer is measured, and the adhesive force (X0) is 2000 mN/25 mm or more. A method for manufacturing a workpiece,
The manufacturing method includes a bonding step of fixing a workpiece with a support sheet, which comprises the workpiece and the support sheet provided on the workpiece, to the ring frame by bonding the adhesive layer in the support sheet according to any one of claims 1 to 4 to the workpiece and the ring frame,
After the aforementioned bonding step, a heating step is performed to heat the adhesive layer in the support sheet fixed to the ring frame,
A processing step is performed to produce the workpiece by processing the workpiece in the workpiece with the support sheet fixed to the ring frame, after the aforementioned bonding step.
After the heating step and processing step, a curing step is performed in which the adhesive layer attached to the ring frame is cured by energy rays.
A method for manufacturing a workpiece, comprising a pick-up step after the curing step, in which the workpiece is pulled away from the cured adhesive layer and picked up.