TW201819569A - Adhesive sheet for semiconductor processing - Google Patents

Abstract

The adhesive sheet for semiconductor processing of the present invention is based on an adhesive sheet for semiconductor processing including a substrate, an intermediate layer, and an adhesive layer, wherein the intermediate layer is composed of a non-energy-ray-curable acrylic polymer (A) and a weight average molecular weight. It is a layer formed by a composition for forming an intermediate layer of an energy-ray-curable acrylic polymer (B) of 50,000 to 250,000, and the aforementioned adhesive layer is energy-ray-curable, and the intermediate layer after energy-ray hardening and The difference in elastic coefficient in the adhesive layer is 20 MPa or less.

Description

Adhesive sheet for semiconductor processing

[0001] The present invention relates to an adhesive sheet for semiconductor processing, and more particularly to an adhesive sheet for semiconductor wafer surface protection used to protect the surface of a semiconductor wafer with bumps.

[0002] The thinning, miniaturization, and multifunctionalization of information terminal equipment are rapidly progressing. Semiconductor devices mounted on such devices also require thinning and high density, and thinning of semiconductor wafers is also expected. Conventionally, in order to meet this requirement, the back surface of a semiconductor wafer has been ground and thinned. Furthermore, in recent years, semiconductor wafers have formed bumps made of solder or the like on the surface of the wafer with a height of several tens to hundreds of μm. When such a semiconductor wafer with bumps is ground, a surface protection sheet is attached to the surface of the wafer forming the bumps in order to protect the bumps. [0003] As a surface protection sheet, conventionally, as disclosed in Patent Documents 1 and 2, an adhesive sheet is used in which an intermediate layer and an adhesive layer are sequentially provided on a substrate, for example. In Patent Documents 1 and 2, the intermediate layer adjusts the coefficient of elasticity or the gel content in order to suppress wafer contamination and improve followability to unevenness on the wafer surface of the adherend. Furthermore, Patent Documents 1 and 2 disclose that energy ray-curable oligomers can be blended into the adhesive layer, or carbon-carbon double bonds can be introduced into the polymer constituting the adhesive to become energy ray-curable. The surface protection sheet uses an energy ray-curable adhesive, and reduces the adhesion of the adhesive layer by irradiation with energy rays. Therefore, it is easy to peel off the semiconductor wafer after use. [Prior Art Literature] [Patent Literature] [0004] Patent Literature 1: Japanese Patent No. 4367769 Patent Literature 2: Japanese Patent No. 4369584

[Problems to be Solved by the Invention] [0005] However, the adhesive layer hardened by energy rays may have insufficient adhesion strength with the intermediate layer. As a result, when the surface protection sheet is peeled from the semiconductor wafer after the energy ray is hardened, interlayer peeling may occur between the intermediate layer and the adhesive layer. When interlayer peeling occurs, for example, when the surface protection sheet is peeled off, the adhesive may remain on the semiconductor wafer and cause the wafer contamination. The present invention was made in view of the above circumstances, and its object is to prevent interlayer peeling between the intermediate layer and the adhesive layer when the adhesive sheet for semiconductor processing is cured and peeled from the workpiece. [Means to Solve the Problem] 0006 [0006] As a result of active review by the present inventors, it was found that by setting both the intermediate layer and the adhesive layer to a specific formulation having energy ray hardening properties, and the energy of these The elastic coefficient difference after the wire hardening is set to a certain value or less, the above-mentioned problems can be solved, and the following inventions have been completed. The present invention provides the following (1) to (8). (1) An adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing including a substrate, an intermediate layer, and an adhesive layer in this order, wherein the intermediate layer is made of a non-energy-ray-curable acrylic polymer ( A) a layer formed with a composition for forming an intermediate layer of an energy-ray-curable acrylic polymer (B) having a weight-average molecular weight of 50,000 to 250,000, and the aforementioned adhesive layer is energy-ray-curable, The difference in elastic coefficient between the intermediate layer and the adhesive layer after energy ray hardening is 23 MPa or less. (2) The adhesive sheet for semiconductor processing according to the above (1), in the composition for forming the intermediate layer, the acrylic polymer (B) is less than 25 parts per 100 parts by mass of the acrylic polymer (A). Parts by mass. (3) The adhesive sheet for semiconductor processing as described in (1) or (2) above, wherein the weight average molecular weight of the acrylic polymer (A) is 300,000 to 1.5 million. (4) The adhesive sheet for semiconductor processing according to any one of (1) to (3), wherein the adhesive layer is formed of an adhesive composition containing an energy ray-curable acrylic polymer (C) . (5) The adhesive sheet for semiconductor processing according to the above (4), wherein the acrylic polymer (C) is obtained by reacting an acrylic copolymer (C0) with a polymerizable compound (Xc) having an energy ray polymerizable group. The reactant is an acrylic copolymer (C1), and the acrylic copolymer (C0) has a constituent unit derived from an alkyl (meth) acrylate (c1) having an alkyl number of 1 to 18, A constituent unit derived from a functional group-containing monomer (c2). (6) The adhesive sheet for semiconductor processing as described in (4) or (5) above, wherein the weight average molecular weight of the acrylic polymer (C) is 100,000 to 1.5 million. (7) The adhesive sheet for semiconductor processing according to any one of (4) to (6), wherein the composition for forming the intermediate layer contains 0.3 to 15 masses based on 100 mass parts of the acrylic polymer (A). Parts of the photopolymerization initiator, and the adhesive composition contains 0.5 to 15 parts by mass of the photopolymerization initiator with respect to 100 parts by mass of the acrylic polymer (C). (8) The adhesive sheet for semiconductor processing according to any one of (1) to (7) above, wherein the acrylic polymer (B) is a polymer of an acrylic copolymer (B0) and an energy ray polymerizable group. An acrylic copolymer (B1), which is a reactant formed by the reaction of an acidic compound (Xb), has an alkyl (meth) acrylic acid derived from an alkyl group and having 1 to 18 carbon atoms. The constituent unit of the ester (b1) and the constituent unit derived from the functional group-containing monomer (b2). [Inventive effect] [0007] The present invention can prevent interlayer peeling between the intermediate layer and the adhesive layer when the adhesive sheet for semiconductor processing is hardened by energy rays and peeled from the workpiece.

[0008] In the following description, the "weight average molecular weight (Mw)" is a polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method, and specifically a value measured based on the method described in the examples. In the description in this specification, for example, "(meth) acrylate" is used in terms of both "acrylate" and "methacrylate", and the same applies to other similar terms. [0009] Hereinafter, the present invention will be described in more detail using embodiments. The adhesive sheet for semiconductor processing of the present invention (hereinafter also simply referred to as "adhesive sheet") includes a substrate, an intermediate layer provided on one surface of the substrate, and an adhesive layer provided on the intermediate layer. In addition, the adhesive sheet may be further provided with a release material on the adhesive layer. The release material protects the adhesive layer, and is removed from the adhesive layer when the adhesive sheet is attached to the workpiece. The adhesive sheet may have a layer other than the above. For example, in order to improve the adhesion between the intermediate layer and the substrate, an easy-adhesion layer made of various curable resins or the like may be provided on one surface of the substrate. In addition, in order to prevent the adhesive sheet from being electrostatically charged, an antistatic layer containing a conventional antistatic agent may be provided on one surface of the substrate. [0010] The intermediate layer is composed of an acrylic polymer (A) containing a non-energy-ray-curable acrylic polymer and an energy-ray-curable acrylic polymer (B) having a weight average molecular weight of 50,000 to 250,000. The layer formed by the composition. The adhesive layer is a layer formed by an energy ray-curable adhesive composition. And the difference in elastic coefficient between the energy layer hardened intermediate layer and the energy ray hardened adhesive layer at 23 ° C is 20 MPa or less. The coefficient of elasticity at 23 ° C is a value of the storage elastic coefficient at 23 ° C when the storage elastic coefficient (frequency: 1Hz) of -30 to 200 ° C is measured by a viscoelasticity measuring device at a heating rate of 3 ° C / min. More specifically, it is a value measured based on the method described in an Example. In the present invention, the intermediate layer and the adhesive layer are both energy ray hardenable. Therefore, if the adhesive sheet attached to the adherend is irradiated with energy rays, the intermediate layer and the adhesive layer are hardened to reduce the adhesive force to the adherend, and can be easily peeled from the adherend. In addition, since the elastic coefficient of the intermediate layer and the adhesive layer is hardened after the energy ray hardens, the peeling of the adhesive sheet can prevent interlayer peeling between the intermediate layer and the adhesive layer. [0011] On the other hand, if the difference in the elastic coefficient exceeds 20 MPa, the interlayer strength between the intermediate layer and the adhesive layer becomes low when hardened by energy rays. Therefore, when the energy ray is hardened, when the adhesive sheet is peeled from the adherend, interlayer peeling easily occurs between the intermediate layer and the adhesive layer. From the viewpoint of improving the interlayer strength between the intermediate layer and the adhesive layer and more effectively suppressing interlayer peeling, the above-mentioned difference in elastic coefficient is preferably 15 MPa or less, more preferably 8 MPa or less. From the viewpoint of suppressing interlayer peeling, the lower the elastic coefficient difference, the better, but in order to make each of the intermediate layer and the adhesive layer have a desired function, the elastic coefficient difference is preferably 0.1 MPa or more, more preferably 0.5 MPa or more. [0012] The layers constituting the adhesive sheet are described in more detail below. <Intermediate layer> In an adhesive sheet, an intermediate layer is a layer provided between an adhesive layer and a base material. Although the intermediate layer can be formed directly on the substrate, as described above, when other layers such as an easy-adhesion layer and an antistatic layer are provided on the substrate, they are formed on the other layers. The intermediate layer is composed of the non-energy-ray-curable acrylic polymer (A) and the energy-ray-curable acrylic polymer (B) having a weight average molecular weight of 50,000 to 250,000 as described above. The layer formed by things. The acrylic polymer (A) may be simply referred to as "(A) component" below. The same goes for other ingredients. The intermediate layer exerts cohesive force by the component (A) and exhibits stress relaxation by the component (B) of a low molecular weight. The adhesive sheet having this intermediate layer has, for example, good followability to an adherend having unevenness, and the like, and has high retention performance to the adherend. Therefore, when a wafer or the like to which an adhesive sheet is attached is subjected to a grinding process, it is possible to prevent the wafer from being damaged or to prevent the grinding layer or the grinding water from infiltrating the wafer surface. [0013] The energy coefficient of the intermediate layer after hardening at 23 ° C is preferably 0.5 to 40 MPa, more preferably 1.0 to 30 MPa, and still more preferably 1.5 to 20 MPa. By having an elastic coefficient, the intermediate layer can fully function as an intermediate layer before energy ray irradiation, and also reduce the aforementioned elastic coefficient difference. In addition, by making the elastic coefficient in these ranges, it is easier to increase the interlayer strength. [0014] Although the elastic coefficient at 23 ° C of the intermediate layer after energy ray hardening is lower than the elastic coefficient at 23 ° C of the intermediate layer after energy ray hardening, it may also be higher. In addition, the coefficient of elasticity at 23 ° C after the energy ray hardening of the intermediate layer can be determined by, for example, the amount of the acrylic polymer (B) blended or the amount of the energy ray polymerizable group introduced into the acrylic polymer (B) (described later). The value of α) and so on. For example, when the blending amount of the acrylic polymer (B) or the amount of the energy ray polymerizable group is increased, the elastic modulus tends to be high. Further, it can be appropriately adjusted by the type and amount of the monomers constituting the acrylic polymer (A), the amount of the cross-linking agent blended in the intermediate layer, the amount of the photopolymerization initiator, and the like. [0015] The acrylic polymer (A) is a polymer having non-energy-ray-curable properties derived from a (meth) acrylate-based constituent unit. The acrylic polymer (A) is preferably an acrylic copolymer (A1) containing a constituent unit derived from an alkyl (meth) acrylate (a1) and a constituent unit derived from a functional group-containing monomer-(a2). More preferably, the acrylic copolymer (A1) is used. The copolymerization form of the acrylic copolymer (A1) is not particularly limited, and may be a block copolymer or a random copolymer. The content of the acrylic copolymer (A1) is preferably from 70 to 100% by mass, and more preferably from 80 to 100% by mass relative to the total amount of (A) components (100% by mass) contained in the composition for forming an intermediate layer. 100% by mass, more preferably 90 to 100% by mass, and even more preferably 100% by mass. [0016] As the alkyl (meth) acrylate (a1), an alkyl (meth) acrylate having 1 to 18 carbon atoms in the alkyl group is used. Specific examples are methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-amyl (meth) acrylate, (meth) acrylic acid N-hexyl, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, n-dodecyl (meth) acrylate Tridecyl ester, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. The alkyl (meth) acrylate (a1) may be used alone or in combination of two or more. [0017] The content of the constituent units derived from the alkyl (meth) acrylate (a1) in the acrylic copolymer (A1) is larger than the total constituent units (100% by mass) of the acrylic copolymer (A1). It is preferably 50 to 99.5% by mass, more preferably 60 to 99% by mass, still more preferably 70 to 97% by mass, and even more preferably 80 to 95% by mass. If the content is 50% by mass or more, the holding performance of the adhesive sheet is high, and the followability to an adherend having a large unevenness is likely to be good. Moreover, if it is 99.5% by mass or less, the constituent unit derived from the component (a2) can be maintained at a certain amount or more. [0018] The alkyl (meth) acrylate (a1), in the above, in order to make the elastic coefficient of the intermediate layer an appropriate value, it is preferably an alkyl (meth) acrylic acid having 1 to 8 carbon atoms in the alkyl group. The ester more preferably contains an alkyl (meth) acrylate having 4 to 8 carbon atoms in the alkyl group (hereinafter sometimes referred to as a monomer (Y)). As the monomer (Y), specifically, 2-ethylhexyl (meth) acrylate and n-butyl (meth) acrylate are preferred, and n-butyl (meth) acrylate is particularly preferred. Herein, the alkyl (meth) acrylate (a1) constituting the acrylic copolymer (A1) may be all of the monomer (Y) or a part of the monomer (Y). Specifically, the monomer (Y) is preferably 75 to 100% by mass, more preferably 80 to 100% by mass, and still more preferably 90 to 100% with respect to the total amount of the alkyl (meth) acrylate (a1). quality%. [0019] The functional group-containing monomer (a2) is a monomer having a functional group such as a hydroxyl group, a carboxyl group, an epoxy group, an amine group, a cyano group, a nitrogen atom-containing ring group, an alkoxysilyl group, and the like. As the functional group-containing monomer (a2), among the above, one or more selected from the group consisting of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and an epoxy group-containing monomer. [0020] Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic acid. 2-hydroxybutyl (hydroxy) (meth) acrylates such as 2-hydroxybutyl, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; unsaturated alcohols such as vinyl alcohol, allyl alcohol, etc. . Examples of the carboxyl group-containing monomer include (meth) acrylic acid, maleic acid, fumaric acid, and econic acid. [0021] Examples of the epoxy-group-containing monomer include epoxy-group-containing (meth) acrylates and non-acrylic epoxy-group-containing monomers. Examples of the epoxy-containing (meth) acrylate include, for example, glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, (3,4-epoxy) Cyclohexyl) methyl ester, 3-epoxycyclo-2-hydroxypropyl (meth) acrylate, and the like. Examples of the non-acrylic epoxy-group-containing monomer include glycidyl crotonic acid, allyl glycidyl ether, and the like. The functional group-containing monomer (a2) may be used alone or in combination of two or more. Among the functional group-containing monomers (a2), carboxyl group-containing monomers are more preferred, and (meth) acrylic acid is more preferred, and acrylic acid is more preferred. When a carboxyl group-containing monomer is used as the functional group-containing monomer (a2), the cohesive force of the intermediate layer is improved, and the retention performance and the like of the intermediate layer tend to be better. [0022] In the acrylic copolymer (A1), the content of the constituent unit derived from the functional group-containing monomer (a2) is preferably relative to the entire constituent unit (100% by mass) of the acrylic copolymer (A1). 0.5 to 40% by mass, more preferably 1 to 30% by mass, still more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass. When the content of the constituent unit derived from the (a2) component is 0.5% by mass or more, the cohesive force of the intermediate layer is high, and the compatibility with the (B) component is also easily improved. On the other hand, if the content is 40% by mass or less, it is possible to ensure that the constituent unit derived from the component (a1) is a certain amount or more. [0023] The acrylic copolymer (A1) may be a copolymer of an alkyl (meth) acrylate (a1) and a functional group-containing monomer (a2), but may also be a component (a1) or (a2) And copolymers of monomers (a3) other than these (a1) and (a2) components. Examples of the other monomer (a3) include cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentyl (meth) acrylate, and (meth) (Meth) acrylate, vinyl acetate, styrene, etc. having a cyclic structure, such as dicyclopentenyl acrylate, dicycloalkoxyethyl (meth) acrylate, and the like. The other monomers (a3) may be used singly or in combination of two or more kinds. In the acrylic copolymer (A1), the content of constituent units derived from other monomers (a3) is preferably 0 to 30 mass% relative to the total constituent units (100% by mass) of the acrylic copolymer (A1). It is more preferably 0 to 20% by mass, still more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass. [0024] The weight average molecular weight (Mw) of the acrylic copolymer (A) is preferably 300,000 to 1.5 million, more preferably 400,000 to 1.2 million, still more preferably 400,000 to 1.1 million, and even more preferably 45. Ten thousand to nine hundred thousand. By setting Mw to be equal to or less than these upper limits, the compatibility between the acrylic copolymer (A) and the acrylic polymer (B) becomes good. In addition, by setting Mw within the above range, it is easy to improve the holding performance of the adhesive sheet. The content of the acrylic copolymer (A) in the composition for forming the intermediate layer is preferably 60 to 99% by mass, and more preferably 70 to 97% relative to the total amount (100% by mass) of the composition for forming the intermediate layer. %, And more preferably 75 to 92% by mass. When the composition for forming an intermediate layer is diluted with a diluent such as an organic solvent to be described later, the total amount of the composition for forming an intermediate layer means the total amount of solids except for the diluent. The same applies to the adhesive composition described later. [Acrylic polymer (B)] The acrylic polymer (B) is an acrylic polymer having energy ray hardening property by introducing an energy ray polymerizable group. The acrylic polymer (B) has a weight average molecular weight (Mw) of 50,000 to 250,000. In the present invention, it is considered that by using the component (B) in the intermediate layer, when the energy ray is irradiated, the component (B) and the energy ray-hardened component in the adhesive layer react and bond. Therefore, it also complements the small difference in elasticity coefficients mentioned above, and improves the interlayer strength of the intermediate layer and the adhesive layer after energy ray hardening. [0026] When the Mw of the acrylic polymer (B) is less than 50,000, when the adhesive sheet is stored for a long period of time, a part of the component (B) will migrate into the adhesive layer, and the adhesive force of the adhesive sheet becomes unstable, and at the same time After the energy rays are irradiated, the adhesive layer may be excessively hardened. As a result, when the adhesive sheet is used after being stored for a long period of time, or when it is left in a state of being adhered to an adherend for a long period of time, there is a case where the interlayer strength between the intermediate layer and the adhesive layer after the irradiation of energy rays becomes insufficient . In addition, when the Mw of the component (B) exceeds 250,000, the interlayer strength of the intermediate layer and the adhesive layer after energy ray irradiation is also apt to decrease. Based on the above viewpoint, the weight average molecular weight (Mw) of the acrylic polymer (B) is preferably 60,000 to 220,000, more preferably 70,000 to 200,000, more preferably 80,000 to 180,000, and even more preferably 85,000 to 150,000. [0027] The acrylic polymer (B) is an acrylic polymer having a constitutional unit derived from a (meth) acrylate by introducing an energy ray polymerizable group. The energy ray polymerizable group of the acrylic polymer (B) is preferably introduced into a side chain of the acrylic polymer. The energy ray polymerizable group may be a group containing an energy ray polymerizable carbon-carbon double bond, and examples thereof include (meth) acrylfluorenyl, vinyl, and the like. Among them, (meth) acrylfluorenyl is preferred. . The acrylic polymer (B) preferably contains an acrylic copolymer having a constituent unit derived from an alkyl (meth) acrylate (b1) and a constituent unit derived from a functional group-containing monomer (b2). (B0) The acrylic copolymer (B1) reacted with the polymerizable compound (Xb) having an energy ray polymerizable group is more preferably made of the acrylic copolymer (B1). The copolymerization form of the acrylic copolymer (B0) is not particularly limited, and may be any of a block copolymer and a random copolymer. The content of the acrylic copolymer (B1) is preferably 70 to 100% by mass, and more preferably 90 to 100% by mass relative to the total amount of (B) components (100% by mass) contained in the composition for forming an intermediate layer. %, And more preferably 100% by mass. [0029] As the alkyl (meth) acrylate (b1), an alkyl (meth) acrylate having an alkyl group of 1 to 18 carbon atoms is used, and a specific example is exemplified as the component (a1) . These may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the constituent unit derived from the alkyl (meth) acrylate (b1) in the acrylic copolymer (B0) is preferably 50 relative to the total constituent unit (100% by mass) of the acrylic copolymer (B0). ~ 95 mass%, more preferably 55-90 mass%, still more preferably 60-85 mass%, and even more preferably 65-80 mass%. When the content is 50% by mass or more, the shape of the formed intermediate layer can be sufficiently maintained. Moreover, if it is 95 mass% or less, the structural unit derived from (b2) component which becomes a reaction point with a polymerizable compound (Xb) can ensure a fixed amount. [0030] The alkyl (meth) acrylate (b1) is the same as the component (a1), and is preferably an alkyl (meth) acrylate having a carbon number of 1 to 8 in the alkyl group, and further preferably contains a mono (Y) (that is, an alkyl (meth) acrylate having a carbon number of 4 to 8). Moreover, as a preferable compound of a monomer (Y), it is the same as said (a1), Especially preferably, it is n-butyl (meth) acrylate. Here, all of the alkyl (meth) acrylates (b1) contained in the acrylic copolymer (B0) may be a monomer (Y), but a part thereof is preferably a monomer (Y). The monomer (Y) is preferably 65 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 80 to 95% by mass with respect to the total amount of the alkyl acrylate (b1). [0031] The functional group-containing monomer (b2) is exemplified as the monomer having a functional group exemplified in the functional group-containing monomer (a2), and is preferably selected from the group consisting of a hydroxyl-containing monomer, a carboxyl-containing monomer, and One or more of epoxy monomers. As these specific compounds, the same compounds as those exemplified as the component (a2) can be exemplified. The functional group-containing monomer (b2) is preferably a hydroxyl group-containing monomer, and among them, various hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate are more preferred. By using a hydroxyalkyl (meth) acrylate, the acrylic copolymer (B0) and the polymerizable compound (Xb) can be easily reacted. [0032] The functional group-containing monomer (a2) used in the acrylic polymer (A) and the functional group-containing monomer (b2) used in the acrylic polymer (B) may be the same as each other. It can also be different, but preferably different. That is, for example, if the functional group-containing monomer (a2) is a carboxyl group-containing monomer, the functional group-containing monomer (b2) is preferably a hydroxyl group-containing monomer. As described above, if the functional groups are different from each other, for example, the acrylic polymer (B) can be preferentially cross-linked by a cross-linking agent to be described later, and the retention performance of the adhesive sheet and the like can be better. [0033] The content of the constituent units derived from the functional group-containing monomer (b2) in the acrylic copolymer (B0) is preferably 5 with respect to the total constituent units (100% by mass) of the acrylic copolymer (B0). ~ 50 mass%, more preferably 10 to 45 mass%, still more preferably 15 to 40 mass%, and even more preferably 20 to 35 mass%. If it is 5% by mass or more, a large number of reaction points with the polymerizable compound (Xb) can be ensured, and energy polymerizability can be easily introduced into the side chain. In addition, if it is 50% by mass or less, the shape of the formed intermediate layer can be sufficiently maintained. The acrylic copolymer (B0) may be a copolymer of an alkyl (meth) acrylate (b1) and a functional group-containing monomer (b2), and may also be a component (b1), a component (b2), and the Copolymers of monomers (b3) other than (b1) and (b2). Examples of the other monomer (b3) include those exemplified as the monomer (a3). The content of the constituent units derived from the other monomer (b3) in the acrylic copolymer (B0) is preferably 0 to 30 mass% relative to the total constituent units (100% by mass) of the acrylic copolymer (B0). , More preferably 0 to 20% by mass, still more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass. [0035] The polymerizable compound (Xb) is a substituent having an energy ray polymerizable group and a functional group in a constituent unit derived from the component (b2) in the acrylic copolymer (B0) (hereinafter also referred to simply as “ "Reactive substituent"). Examples of the energy ray polymerizable group include a (meth) acrylfluorenyl group and a vinyl group as described above, and a (meth) acrylfluorenyl group is preferred. The polymerizable compound (Xb) is preferably a compound having 1 to 5 energy ray polymerizable groups per molecule. The reactive substituent in the polymerizable compound (Xb) may be appropriately changed depending on the functional group of the functional group-containing monomer (b2). Examples include isocyanate groups, carboxyl groups, and epoxy groups. From the standpoint of the like, an isocyanate group is preferred. When the polymerizable compound (Xb) has an isocyanate group, for example, when the functional group of the functional group-containing monomer (b2) is a hydroxyl group, it can easily react with the acrylic copolymer (B0). [0036] Specific examples of the polymerizable compound (Xb) include (meth) acrylfluorenyloxyethyl isocyanate, m-isopropenyl-α, α-dimethylbenzyl isocyanate, (Meth) acryloyl cyanate, allyl isocyanate, glycidyl (meth) acrylate, (meth) acrylic acid, and the like. These polymerizable compounds (Xb) can be used individually or in combination of 2 or more types. Among these, from the viewpoint of a compound having a preferable isocyanate group as the reactive substituent and a proper distance between the main chain and the energy ray polymerizable group, an isocyanate (meth) acrylfluorenyloxyethyl group is preferred. ester. The polymerizable compound (Xb) is preferably 40 to 98 equivalents, and more preferably 50 to 95 equivalents of the total functional group (100 equivalents) derived from the functional group-containing monomer (b2) in the acrylic copolymer (B1). , And more preferably 60 to 90 equivalents, and even more preferably 70 to 85 equivalents to react with functional groups. [0037] The α value calculated from the following formula (1) is an index indicating the number of energy ray polymerizable groups possessed by the acrylic copolymer (B1). In the acrylic polymer (B1), the α value is preferably 5 to 40, more preferably 10 to 35, and even more preferably 15 to 30. By using the acrylic copolymer (B1) having such an α value in the blending amount described later, it is easy to adjust the elastic coefficient of the intermediate layer to a desired range. (In formula (1), [P _b ] Represents the content of the constituent unit derived from the functional group-containing monomer (b2) with respect to 100 parts by mass of the entire constituent unit of the acrylic copolymer (B0), [Q _b ] Represents 100 equivalents of the functional group derived from the functional group-containing monomer (b2) and the equivalent of the polymerizable compound (Xb) with respect to the acrylic copolymer (B0), [R _b ] Represents the number of energy ray polymerizable groups which the polymerizable compound (Xb) has). [0038] The content of the acrylic polymer (B) in the composition for forming an intermediate layer is preferably less than 25 parts by mass, more preferably 1 to 24 parts by mass, relative to 100 parts by mass of the acrylic polymer (A). , And more preferably 8 to 23 parts by mass. When the content of the component (B) is set to be relatively small as described above, the intermediate layer has an improved stress relaxation property and an intermediate layer with high unevenness followability. In addition, when the content of the acrylic polymer (B) is small, since the elastic coefficient of the intermediate layer after energy ray hardening does not become so high, the aforementioned difference in elastic coefficient can be reduced, and interlayer peeling can be easily prevented. [Crosslinking Agent] The composition for forming an intermediate layer preferably further contains a crosslinking agent. Examples of the cross-linking agent include an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an aziridine-based cross-linking agent, and a metal chelating agent-based cross-linking agent. Among these, an isocyanate-based cross-linking agent is preferred. When an isocyanate-based crosslinking agent is used, for example, when the component (B) has a hydroxyl group, the crosslinking agent preferentially crosslinks the acrylic polymer (B). The composition for forming an intermediate layer is crosslinked by a crosslinking agent by, for example, heating after coating. The intermediate layer is formed into a coating film by cross-linking an acrylic polymer, especially a low molecular weight acrylic polymer (B), etc., and it is easy to exert the function as an intermediate layer. The content of the crosslinking agent is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 7 parts by mass, and still more preferably 1 to 5 parts by mass, with respect to 100 parts by mass of the acrylic polymer (A). [0040] Examples of the isocyanate-based crosslinking agent include a polyisocyanate compound. Specific examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; isophorone diisocyanate, Cycloaliphatic polyisocyanates and the like such as hydrogenated diphenylmethane diisocyanate and the like. In addition, the ureton bodies and isocyanurate bodies are also exemplified, and the low molecular weight active hydrogen compounds containing ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil are also exemplified. Adducts of reactants and the like. These may be used individually by 1 type, and may be used in combination of 2 or more type. Among the above, a polyhydric alcohol (for example, trimethylolpropane) adduct of an aromatic polyisocyanate such as toluene diisocyanate is preferred. [0041] Examples of the epoxy-based crosslinking agent include 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-Tetra Glycidyl-m-xylylene diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl Amine, etc. These may be used individually by 1 type, and may be used in combination of 2 or more type. Examples of the metal chelate-based cross-linking agent include, for example, acetylacetone, ethyl, and the like on a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium, and the like.醯 Ethyl acetate, tris (2,4-glutarate), and other compounds. These may be used individually by 1 type, and may be used in combination of 2 or more type. Examples of the aziridine-based cross-linking agent include, for example, diphenylmethane-4,4'-bis (1-aziridinecarboxamide), trimethylolpropane tri-β-aziridinylpropionate, Tetramethylolmethane tri-β-aziridinylpropionate, toluene-2,4-bis (1-aziridinylcarbamidine), triethyl melamine, bis-m-xylylenediamine-1 -(2-methylaziridine), tri-1- (2-methylaziridine) phosphine, trimethylolpropane tri-β- (2-methylaziridine) propionate, hexa [ 1- (2-methyl) -aziridinyl] triphosphatriazine and the like. [Photopolymerization Initiator] The composition for forming an intermediate layer preferably further contains a photopolymerization initiator. Since the composition for forming an intermediate layer contains a photopolymerization initiator, it is easy to harden the composition for forming an intermediate layer using energy rays such as ultraviolet rays. Examples of the photopolymerization initiator include acetophenone, 2,2-diethoxybenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, Michler's ketone, benzoin, benzoin methyl ether, benzoin ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, Benzyldimethylacetal, biphenylhydrazone, biacetamidine, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-ethylanthraquinone, 2,2-dimethoxy-1,2-diphenyl Ethane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholine acetone-1, 2-benzyl-2 -Dimethylamino-1- (4-morpholinylphenyl) butanone-1, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, diethylthioxanthone, isopropyl Low molecular weight polymerization initiators such as thioxanthone, 2,4,6-trimethylbenzylidene diphenyl-phosphine oxide, oligomeric {2-hydroxy-2-methyl-1- [4- (1methylvinyl) phenyl] acetone} and other oligomerization polymerization initiators. These can be used alone or in combination of two or more. Among these, 1-hydroxycyclohexylphenyl ketone is preferable. The content of the photopolymerization initiator is usually 0.3 to 15 parts by mass based on 100 parts by mass of the acrylic polymer (A), but in order to sufficiently harden even a small amount of the acrylic polymer (B), The elasticity coefficient of the intermediate layer after hardening is easy to increase, and the content is more preferable, preferably 1 to 10 parts by mass, and more preferably 3 to 8 parts by mass. [0043] The composition for forming an intermediate layer may contain other additives as long as the effect of the present invention is not impaired. Examples of other additives include antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, and adhesion-imparting agents. When such additives are contained, the content of each additive is preferably 0.01 to 6 parts by mass, and more preferably 0.01 to 2 parts by mass, relative to 100 parts by mass of the acrylic polymer (A). In addition, the thickness of the intermediate layer may be appropriately selected according to, for example, the height of bumps formed on the surface of the wafer of the adherend, but it is preferably 10 to 800 μm, more preferably 15 to 600 μm, and even more preferably 20 to 500 μm. [0044] In the adhesive sheet, the adhesive layer is a layer formed on the intermediate layer, and the adhesive sheet is attached to the adherend through the adhesive layer. The adhesive layer is usually formed directly on the intermediate layer. The adhesive layer is an energy ray-hardenable layer as described above. Before the energy ray irradiation, the adhesive sheet can sufficiently maintain the high adhesion of the workpiece, but after the energy ray irradiation, the adhesive force is reduced due to the hardening of the adhesive layer, and it can be easily peeled from the wafer of the adherend. [0045] After the energy ray of the adhesive layer is hardened, the elastic coefficient at 23 ° C. is preferably 1 to 60 MPa, more preferably 1.5 to 30 MPa, and still more preferably 1.8 to 12 MPa. By making the elastic coefficient of the adhesive layer after energy ray hardening fall into this range, the above-mentioned difference in elastic coefficient can be reduced. In addition, it is easy to exhibit proper adhesion as an adhesive layer before energy ray irradiation. Furthermore, since the elastic coefficient is within these ranges, it is easier to increase the interlayer strength. [0046] The adhesive composition forming the adhesive layer contains, for example, an acrylic polymer, polyurethane, rubber-based polymer, polyolefin, polysiloxane, and the like as an adhesive capable of exhibiting adhesiveness to the adhesive layer. Ingredients (adhesive resin). Among these, an acrylic polymer is preferable. The adhesive composition forming the adhesive layer can also have energy ray hardening by blending an energy ray hardening compound different from the adhesive resin, but it is preferable that the above-mentioned adhesive resin itself has energy ray curing. When the adhesive resin itself has energy ray hardening property, an energy ray polymerizable group is introduced into the adhesive resin, but it is better to introduce an energy ray polymerizable group into the main chain or side chain of the adhesive resin. [0047] When an energy ray curable compound different from the adhesive resin is blended, a monomer or oligomer having an energy ray polymerizable group is used as the energy ray curable compound. The oligomer is an oligomer having a weight average molecular weight (Mw) of less than 10,000, and examples thereof include urethane (meth) acrylate. When the adhesive resin itself has energy ray curability, an energy ray curable compound other than the adhesive resin may be blended in the adhesive composition. [0048] A case where the energy ray-curable adhesive resin contained in the adhesive composition is an acrylic polymer (hereinafter also referred to as "acrylic polymer (C)") will be described in detail. [Acrylic polymer (C)] The acrylic polymer (C) is an acrylic polymer having an energy ray polymerizable group introduced therein and having a constituent unit derived from a (meth) acrylate. The energy ray polymerizable group is preferably introduced into the side chain of the acrylic polymer. The acrylic polymer (C) preferably contains an acrylic copolymer (C1) which is a reactant obtained by reacting the acrylic copolymer (C0) with a polymerizable compound (Xc) having an energy ray polymerizable group. The acrylic copolymer (C0) has a constituent unit derived from an alkyl (meth) acrylate (c1) and a constituent unit derived from a functional group-containing monomer (c2), and is more preferably an acrylic polymer (C ) Is made of the acrylic copolymer (C1). The copolymerization form of the acrylic copolymer (C0) is not particularly limited, and may be any of a block copolymer and a random copolymer. The content of the acrylic copolymer (C1) is preferably 70 to 100% by mass, and more preferably 80 to 100% by mass relative to the total amount (100% by mass) of the (C) component contained in the adhesive composition. , And more preferably 90 to 100% by mass, and even more preferably 100% by mass. [0049] As the alkyl (meth) acrylate (c1), an alkyl (meth) acrylate having an alkyl group of 1 to 18 carbon atoms is used, and as a specific example, an (a1) component is exemplified These can be used alone or in combination of two or more. The content of the constituent unit derived from the alkyl (meth) acrylate (c1) in the acrylic copolymer (C0) is higher than that of the acrylic copolymer (C0) from the viewpoint of improving the adhesion of the formed adhesive layer. The total constituent units (100% by mass) are preferably 50 to 99% by mass, more preferably 60 to 98% by mass, still more preferably 70 to 97% by mass, and even more preferably 80 to 96% by mass. [0050] The alkyl (meth) acrylate (c1) has the same components as (a1) and (b1), and is preferably an alkyl (meth) acrylate having 1 to 8 carbon atoms, and further preferably The alkyl (meth) acrylate (ie, monomer (Y)) having a carbon number of 4 to 8 is more preferable. The preferable compound to be used as the monomer (Y) is the same as the above (a1) and (b1), and particularly preferred is n-butyl (meth) acrylate. Among them, the alkyl (meth) acrylate (c1) may be all of the monomer (Y), but in order to adjust the adhesive property or elastic coefficient of the adhesive layer better, a part of the monomer (Y) is preferred. Specifically, the monomer (Y) is preferably 65 to 98% by mass, more preferably 70 to 95% by mass, and still more preferably 75 to 90% with respect to the total amount of the alkyl (meth) acrylate (c1). quality%. [0051] For example, the alkyl (meth) acrylate (c1) may contain ethyl (meth) acrylate in addition to the above-mentioned monomer (Y). If ethyl (meth) acrylate is used, the elastic coefficient of the adhesive layer is likely to be reduced even after the energy ray is hardened, and the difference in elastic coefficient from the intermediate layer is easily reduced. In addition, it is easy to adjust the adhesion performance of the adhesive layer to a desired one. The alkyl (meth) acrylate (c1) may contain methyl (meth) acrylate in addition to the monomers (Y) and ethyl (meth) acrylate. By containing methyl (meth) acrylate, it is easy to adjust the adhesive property of the adhesive layer to a desired one. [0052] The total amount of ethyl (meth) acrylate and methyl (meth) acrylate is preferably 2 to 35% by mass relative to the total amount of alkyl (meth) acrylate (c1), and more preferably 5 to 30% by mass, and more preferably 10 to 25% by mass. In addition, the ethyl (meth) acrylate is preferably 2 to 30% by mass, more preferably 5 to 25% by mass, and even more preferably 10 to 20, with respect to the total amount of the alkyl (meth) acrylate (c1). quality%. [0053] The functional group-containing monomer (c2) is exemplified as the monomer having a functional group as the functional group-containing monomer (a2). Specifically, it is preferably selected from a hydroxyl group-containing monomer, One or more of a carboxyl group-containing monomer and an epoxy group-containing monomer. As these specific compounds, the same compounds as those exemplified as the component (a2) can be exemplified. [0054] As the functional group-containing monomer (c2), among the above, a hydroxyl-containing monomer is more preferred, of which a hydroxyalkyl (meth) acrylate is more preferred, and a (meth) acrylic acid 2- Hydroxyethyl ester and 4-hydroxybutyl (meth) acrylate, particularly preferably 4-hydroxybutyl (meth) acrylate. By using a hydroxyalkyl (meth) acrylate as the (c2) component, the acrylic copolymer (C0) and the polymerizable compound (Xc) can be easily reacted. In addition, when 4-hydroxybutyl (meth) acrylate is used, the tensile strength of the intermediate layer is increased, and it is easy to prevent the paste from remaining. [0055] The content of the constituent units derived from the functional group-containing monomer (c2) in the acrylic copolymer (C0) is preferably relative to the total constituent units (100% by mass) of the acrylic copolymer (C0). 1 to 40% by mass, more preferably 2 to 30% by mass, still more preferably 3 to 25% by mass, and even more preferably 4 to 15% by mass. When the content is 1% by mass or more, a certain amount of a functional group that becomes a reaction point with the polymerizable compound (Xc) can be secured. Therefore, since the adhesive layer can be appropriately hardened by energy ray irradiation, the adhesive force after energy ray irradiation can be reduced. Furthermore, it is easy to increase the interlayer strength after the energy rays of the adhesive layer and the intermediate layer are irradiated. In addition, if the content is 40% by mass or less, a sufficient useful life can be ensured when the solution of the adhesive composition is applied to form an adhesive layer. The acrylic copolymer (C0) may be a copolymer of an alkyl (meth) acrylate (c1) and a functional group-containing monomer (c2), but it may also be a (c1) component or a (c2) component Copolymers with monomers (c3) other than these (c1) and (c2) ingredients. Examples of the other monomer (c3) include those exemplified as the monomer (a3). In the acrylic copolymer (C0), the content of constituent units derived from other monomers (c3) is preferably 0 to 30 mass% relative to the total constituent units (100% by mass) of the acrylic copolymer (C0). It is more preferably 0 to 20% by mass, still more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass. [0057] The polymerizable compound (Xc), similar to the polymerizable compound (Xb) described above, has an energy ray polymerizable group and can be included in the constituent unit derived from the component (c2) in the acrylic copolymer (C0). The compound having a functional group-reactive substituent (reactive substituent) is preferably a compound having 1 to 5 energy ray polymerizable groups per molecule. Specific examples of the reactive substituent and the energy ray polymerizable group are the same as those of the polymerizable compound (Xb). Therefore, the reactive substituent is preferably an isocyanate group, and the energy ray polymerizable group is preferably a (meth) acrylfluorenyl group. In addition, as the polymerizable compound (Xc), the same as those exemplified as the polymerizable compound (Xb) described above are preferred, and (meth) acrylfluorenyloxyethyl isocyanate is preferred. The polymerizable compound (Xc) can be used alone or in combination of two or more. The polymerizable compound (Xc) is preferably 30 to 98 equivalents, and more preferably 40 to 95 equivalents of the total functional groups (100 equivalents) derived from the functional group-containing monomer (c2) in the acrylic copolymer (C0). , And more preferably 50 to 92 equivalents, and even more preferably 80 to 92 equivalents to react with functional groups. [0058] The weight average molecular weight (Mw) of the acrylic copolymer (C) is preferably 100,000 to 1.5 million, more preferably 250,000 to 1 million, still more preferably 300,000 to 900,000, and even more preferably 35. Million to 800,000. By having this Mw, appropriate adhesiveness can be provided to an adhesive layer. The content of the acrylic copolymer (C) in the adhesive composition is preferably 70 to 99% by mass, more preferably 75 to 98% by mass relative to the total amount of the adhesive composition (100% by mass). It is more preferably 80 to 96% by mass. [0059] The β value calculated from the following formula (2) is an index indicating the number of energy ray polymerizable groups that the acrylic copolymer (C1) has. In the acrylic polymer (C1), the β value calculated from the following formula (2) is preferably 0.5 to 30, more preferably 1.0 to 20, still more preferably 1.2 to 15, and even more preferably 2 to 12. By making the adhesive layer contain the acrylic copolymer (C1) having these β values, it is easy to adjust the elastic coefficient of the adhesive layer to a desired range. (In formula (2), [P _c ] Represents the content of the constituent unit derived from the functional group-containing monomer (c2) with respect to 100 parts by mass of the entire constituent unit of the acrylic copolymer (C0), [Q _c ] Represents 100 equivalents of the functional group derived from the functional group-containing monomer (c2) and the equivalent of the polymerizable compound (Xc) to the acrylic copolymer (C0), [R _c ] Represents the number of energy ray polymerizable groups which the polymerizable compound (Xc) has). [Crosslinking Agent] The adhesive composition preferably further contains a crosslinking agent. The adhesive composition is crosslinked by a crosslinking agent by, for example, heating after coating. The pressure-sensitive adhesive layer cross-links the acrylic polymer (C) with a cross-linking agent to form a coating film appropriately, and easily functions as a pressure-sensitive adhesive layer. Examples of the crosslinking agent include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, and a chelating agent-based crosslinking agent. Among these, an isocyanate-based crosslinking agent is preferred. The crosslinking agent may be used alone or in combination of two or more kinds. In addition, specific examples of the isocyanate-based cross-linking agent are exemplified as cross-linking agents that can be used in the composition for forming an intermediate layer, and preferred compounds thereof are also the same. The content of the crosslinking agent is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 7 parts by mass, and still more preferably 0.3 to 4 parts by mass, with respect to 100 parts by mass of the acrylic polymer (C). [Photopolymerization Initiator] The adhesive composition preferably further contains a photopolymerization initiator. The photopolymerization initiator is exemplified as the photopolymerization initiator used in the above-mentioned composition for forming an intermediate layer. The photopolymerization initiator can be used alone or in combination of two or more. Among the above, 2,2-dimethoxy-1,2-diphenylethane-1-one and 1-hydroxycyclohexylphenyl ketone are preferred. The content of the photopolymerization initiator is usually 0.5 to 15 parts by mass, more preferably 1 to 12 parts by mass, and still more preferably 4.5 to 10 parts by mass based on 100 parts by mass of the acrylic polymer (C). When the content of the photopolymerization initiator is relatively high in this way, it is easy to increase the elastic coefficient of the adhesive layer after curing. [0062] The adhesive composition may contain other additives as long as the effect of the present invention is not impaired. Examples of the other additives include adhesion-imparting agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, and dyes. When these additives are contained, the content of each additive is preferably 0.01 to 6 parts by mass, and more preferably 0.01 to 2 parts by mass, relative to 100 parts by mass of the acrylic polymer (C). The thickness of the adhesive layer is preferably 1 to 100 μm, more preferably 1 to 75 μm, and even more preferably 3 to 50 μm. [0063] In addition, when the above-mentioned elastic coefficient of the adhesive layer is used, for example, when the acrylic polymer (C) is used, the acrylic polymer (C) can be introduced by the type and amount of the monomer constituting the acrylic polymer (C). The amount of the energy ray polymerizable group (value of β) is adjusted. For example, if the amount of the energy ray polymerizable group (the value of β) is increased, the elastic coefficient tends to be high. Moreover, it can adjust suitably by the quantity of the crosslinking agent, the quantity of a photoinitiator, etc. which are mix | blended with an adhesive agent layer. [0064] Based on the viewpoint of improving the coating property when an intermediate layer and an adhesive layer are formed on the surface of a substrate, a release material, etc., each of the composition for forming an intermediate layer and the adhesive composition may be further diluted with an organic solvent. It is used as a solution form of the intermediate layer-forming composition and the adhesive composition. Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. The organic solvent used may be an organic solvent used in the synthesis of the components (A) to (C), or one or more organic solvents other than the organic solvent used in the synthesis may be added. When the solution is in the form as described above, the solid content concentration of the solution is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, and still more preferably 15 to 50% by mass. [0065] <Substrate> The substrate used in the adhesive sheet is preferably a resin film from the viewpoint of improving the holding performance to the workpiece. Examples of the resin film include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, and ethylene-vinyl acetate copolymer. (EVA) film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, ethylene- (meth) acrylic copolymer film, ethylene- (methyl ) Acrylate copolymer film, polycarbonate-based film, polystyrene-based film, polyphenylene sulfide-based film, cycloolefin polymer-based film, polyurethane-based film, ionic polymer resin film, polyfluorene Imine-based film, fluororesin film, etc. [0066] The substrate may be a resin film having only one of the above-mentioned resins, or may be one having two or more. For example, it may be a single-layer film made of one kind of resin film, or a multi-layer film made by laminating a plurality of resin films. Moreover, the resin film may be such a crosslinked film. Among the above resin films, in order to further improve the holding performance of the workpiece, a polyethylene film, a polypropylene film, an ethylene-vinyl acetate copolymer (EVA) film, and a polyethylene terephthalate film are preferred. The resin film may contain a conventional filler, a colorant, an antistatic agent, an antioxidant, an organic lubricant, a catalyst, and the like. The resin film may be transparent, or may be colored as desired. The thickness of the substrate is preferably 10 to 500 μm, more preferably 15 to 300 μm, and still more preferably 20 to 200 μm. [0067] <Release Material> The wafer protection adhesive sheet of the present invention may further include a release material on the adhesive layer. Examples of the release material include a release sheet subjected to a double-sided release treatment, and a release sheet subjected to a single-side release treatment. Examples of such release sheets include those in which a release agent is applied to a substrate for a release material. Examples of the substrate for the release material include, for example, a resin film used as the substrate, and polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferred. Film, and polyolefin film such as polypropylene and polyethylene. Examples of the release agent include rubber-based elastomers such as silicone resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl resins, alkyd resins, and fluorine-based resins. Wait. The thickness of the release material is not particularly limited, but is preferably 10 to 200 μm, and more preferably 20 to 150 μm. [Manufacturing Method of Adhesive Sheet] The manufacturing method of the adhesive sheet for wafer protection of the present invention is not particularly limited, and it can be produced according to a conventional method. For example, it can be manufactured by preparing a base material with an intermediate layer provided with an intermediate layer on one surface of the base material, and further laminating an adhesive layer on the intermediate layer of the base material with the intermediate layer. The substrate with an intermediate layer can be produced by, for example, coating the composition for forming an intermediate layer or a solution thereof on one surface of the substrate, followed by heating and drying to form the intermediate layer. Alternatively, the composition for forming an intermediate layer or a solution thereof is coated on the release-treated surface of the release material, followed by heating and drying to form an intermediate layer on the release material, and bonding the intermediate layer to a base material to obtain an adhesive layer. Substrate of the middle layer. The release material may be peeled before the adhesive layer is laminated on the intermediate layer. [0069] The adhesive layer is formed by applying an adhesive composition or a solution thereof on a release-treated surface of a release material different from the release material used in the production of the intermediate layer, and heating and drying to form an adhesive layer. The adhesive layer of the material can be adhered to the intermediate layer. The release material can be peeled from the adhesive layer, or can be directly used as a release material provided on the adhesive layer. In addition, the adhesive layer can also be formed by directly coating the adhesive composition on the intermediate layer of the substrate with the intermediate layer, followed by heating and drying. In this case, the release material may be further bonded to the adhesive layer. [0070] Examples of the method for applying the composition for forming an intermediate layer, the adhesive composition, or a solution thereof on a substrate or a release material include, for example, a spin coating method, a spray coating method, a rod coating method, A doctor blade coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, and the like. When forming a thick intermediate layer, a solution of the composition for forming an intermediate layer may be applied on the release-treated surface of the release material and dried to form two or more intermediate layers, and the intermediate layers may be adhered to each other, or Multiple intermediate layers are sequentially laminated on the material to form an intermediate layer. The same applies to the adhesive layer. [Using Method of Adhesive Sheet] The adhesive sheet of the present invention is attached to various workpieces such as semiconductor wafers. When processing the workpiece, the user preferably applies the adhesive sheet to the surface of the workpiece having unevenness or protrusions. . Furthermore, it is better to adhere to the surface of a semiconductor wafer, especially to the surface of a wafer on which bumps are formed, and to use it as an adhesive sheet for protecting the surface of a semiconductor wafer. In addition, the adhesive sheet is better attached to the surface of the semiconductor wafer, and is used as a back surface abrasive tape for protecting the circuits formed on the surface of the wafer during subsequent wafer back grinding. When the adhesive sheet of the present invention has an intermediate layer, even if the wafer surface has a step difference due to bumps or the like, its embedding property is also good, so the wafer surface protection performance is good. [0072] The adhesive layer and the intermediate layer of the present invention are of an energy ray hardening type. Therefore, the adhesive sheet attached to the surface of a workpiece such as a semiconductor wafer is irradiated with energy rays to harden the energy rays, and then peeled off from the surface of the workpiece. Thereby, since the adhesive sheet is peeled after the adhesive force is reduced, its peelability is good. In addition, when the cured adhesive sheet is peeled off, as described above, interlayer peeling between the adhesive layer and the intermediate layer can be prevented, and paste residues are unlikely to occur on the wafer surface. Moreover, the use of an adhesive sheet is not limited to a back-grinding sheet, and it can also be used for other uses. For example, the adhesive sheet may be attached to the back of the wafer and used as a dicing sheet holding the wafer when dicing the wafer. In this case, the wafer may be a through-electrode or the like, or a protrusion or a bump with bumps or the like formed on the back surface of the wafer. Examples [0073] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. [0074] The measurement method and evaluation method in the present invention are as follows. [Weight average molecular weight (Mw)] A gel permeation chromatography device (product name "HLC-8220", manufactured by TOSOH Co., Ltd.) was used to measure under the following conditions, and the value measured in terms of standard polystyrene was used. (Measurement conditions) Column: "TSK protective column HLX-H", "TSK gel GMHXL (× 2)", "TSK gel G2000MHXL" (all manufactured by TOSOH Co., Ltd.) Column temperature: 40 ° C Developing solvent: Tetrahydrofuran flow rate: 1.0 mL / min [0075] [Measurement of elasticity coefficient] Using the composition for forming an intermediate layer and the adhesive composition used in each example and comparative example, polyethylene terephthalate was prepared on both sides (PET) is a 200 μm-thick intermediate layer and an adhesive layer made of a release film (manufactured by LINTEC Corporation, product name “SP-PET381031”, thickness: 38 μm). The intermediate layer having a thickness of 200 μm can be obtained by preparing a plurality of intermediate layers with a thickness of 50 μm formed on a release film in the same manner as in Examples and Comparative Examples, and sequentially laminating them. The same applies to the adhesive layer. Subsequently, an ultraviolet irradiation device (manufactured by LINTEC Co., Ltd., product name "RAD-2000m / 12") was used at an illumination intensity of 230 mW / cm. ² 500mJ / cm ² , The intermediate layer and the adhesive layer are irradiated with ultraviolet rays. Next, the intermediate layer and the adhesive layer hardened by ultraviolet rays were cut into a size of 4 mm × 50 mm as a sample for measuring viscoelasticity. Using this sample, a storage elasticity coefficient (frequency: 1 Hz) of -30 to 200 ° C was measured with a viscoelasticity measuring device (manufactured by ORIENTEC Corporation, product name "RHEOVIBRON") at a temperature rising rate of 3 ° C / minute (frequency: 1 Hz), The value of the storage elastic coefficient is set as the elastic coefficient after the energy ray of each layer is hardened. [Measurement of Interlayer Strength] A double-sided tape (LINTEC Corporation, trade name “TACKLINER”) was attached to a SUS board, and a cutting tape (LINTEC Corporation, product name “ADWILL D-510T” was attached thereto. ”), And on the adhesive surface of the dicing tape, the surface of the adhesive layer on the adhesive sheet is adhered to the adhesive surface of the dicing tape, and the examples and comparative examples produced and the release film is peeled off. Adhesive sheet (length 200mm, width 25mm). Subsequently, the produced sample was irradiated with UV (illuminance: 230 mW / cm) using RAD-2000m / 12 manufactured by LINTEC Corporation. ² , Light quantity: 500mJ / cm ² ), "AUTOGRAPH AG-IS 1kN" manufactured by Shimadzu Corporation was peeled at a peeling speed of 600 m / min and a peeling angle of 180 ° at 23 ° C and 50% RH, and the interlayer strength between the intermediate layer and the adhesive layer was measured. . [Example 1] [Production of base material A with intermediate layer] An acrylic copolymer (weight average) prepared by copolymerizing 91 parts by mass of n-butyl acrylate (BA) and 9 parts by mass of acrylic acid (AA) was prepared. (Molecular weight: 600,000) As the acrylic polymer (A). An acrylic copolymer prepared by copolymerizing 62 parts by mass of n-butyl acrylate (BA), 10 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (2HEA) was prepared. Acrylic copolymer (made by Showa Denko Corporation, product name "KARENZ MOI") obtained by adding a hydroxy (100 equivalent) addition ratio of 2HEA to 80 equivalents Weight average molecular weight: 100,000) was used as the acrylic polymer (B). To 100 parts by mass of the acrylic polymer (A) was added 13 parts by mass of the acrylic polymer (B), and trimethylolpropane was added as a cross-linking agent to toluene diisocyanate (manufactured by TOSOH Corporation, product name "CORONATE" L ") 2.2 parts by mass and 3.71 parts by mass of 1-hydroxycyclohexylphenyl ketone (manufactured by BASF, product name" Irgacure 184 ") as a photopolymerization initiator, adjusted to a solid content concentration of 37% by mass using toluene After stirring for 30 minutes, a solution of the composition for forming an intermediate layer was obtained. [0078] Next, a solution of the composition for forming the intermediate layer was applied to a PET-based release film (LINTEC Corporation, product name "SP-PET381031", thickness: 38 µm), heated at 100 ° C for 2 minutes, and dried to form an adhesive layer. Peel off the middle layer of the film. The thickness of the intermediate layer was 50 μm. Two sheets of the intermediate layer with the release film were prepared. Next, an intermediate layer side of an intermediate layer with a release film was bonded to an ethylene-vinyl acetate film (manufactured by Gunze Co., Ltd., product name "FUNCRARE LEB", 120 μm thick), and the intermediate layer was peeled off. Peeling film. Subsequently, another intermediate layer with a release film was further bonded to the intermediate layer laminated on the substrate. The thickness of the intermediate layer was 100 μm, and a substrate with an intermediate layer formed of a release material / interlayer / substrate was obtained.材 A. Material A. [Production of Adhesive Sheet] 70 parts by mass of n-butyl acrylate (BA), 15 parts by mass of ethyl acrylate (EA), 5 parts by mass of methyl methacrylate (MMA), and 4-hydroxybutyl acrylate were prepared. An acrylic copolymer obtained by copolymerizing 10 parts by mass of an ester (4HBA), and a hydroxy (100 equivalent) addition ratio to 4HBA is 90 equivalents. Co., Ltd., an acrylic copolymer (weight average molecular weight: 600,000) obtained under the product name "KARENZ MOI" was used as the acrylic polymer (C). To 100 parts by mass of acrylic polymer (C) was added 1.5 parts by mass of trimethylolpropane addition toluene diisocyanate (manufactured by TOSOH Corporation, product name "CORONATE L") as a cross-linking agent, and photopolymerization was started. 7.3 parts by mass of 2,2-dimethoxy-1,2-diphenylethane-1-one (manufactured by BASF, Irgacure 651), adjusted to a solid content concentration of 20% by mass using toluene, and carried out 30 Stir for a minute to obtain a solution of the adhesive composition. Next, the solution of the adhesive composition was applied to a PET-based release film (LINTEC Corporation, product name "SP-PET381031", thickness: 38 μm), heated at 90 ° C for 1 minute, and dried to prepare an adhesive having a thickness of 10 μm. Floor. The previously prepared release film on the substrate A with an intermediate layer was removed, and the exposed intermediate layer was adhered to the adhesive layer to obtain an adhesive sheet made of a release material / adhesive layer / intermediate layer / base material. [Example 2] (Production of base material B with intermediate layer) Aside from the addition of the acrylic polymer (B) to 23 parts by mass, it was carried out in the same manner as in Example 1 to produce a substrate with an intermediate layer.材 B。 Material B. (Production of Adhesive Sheet) Prepare acrylic acid obtained by copolymerizing 74 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 6 parts by mass of 2-hydroxyethyl acrylate (2HEA). Is a copolymer obtained by adding methacryloyloxyethyl isocyanate (manufactured by Showa Denko Corporation, product name "KARENZ MOI") so that the hydroxy (100 equivalent) addition ratio to 2HEA is 50 equivalents. An acrylic copolymer (weight average molecular weight: 600,000) was used as the acrylic polymer (C). To 100 parts by mass of the acrylic polymer (C), 0.5 part by mass of trimethylolpropane addition toluene diisocyanate (manufactured by TOSOH Co., Ltd., product name "CORONATE L") as a crosslinking agent was added as a photopolymerization agent. 6.0 parts by mass of 1-hydroxycyclohexylphenyl ketone (Irgacure 184, manufactured by BASF, Inc.) was adjusted to a solid content concentration of 20% by mass using toluene, and stirred for 30 minutes to obtain a solution of an adhesive composition. Next, an adhesive sheet was produced in the same manner as in Example 1 except that a solution of the adhesive composition was used and a substrate B with an intermediate layer was used instead of the substrate A with an intermediate layer. [Comparative Example 1] (Production of Adhesive Sheet) 52 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 2-hydroxyethyl acrylate (2HEA) 28 were prepared. Acrylic copolymer copolymerized by mass parts, and methacrylic acid methyl isocyanate (manufactured by Showa Denko Co., Ltd., product is added so that the addition ratio of hydroxyl group (100 equivalents) to 2HEA is 90 equivalents) An acrylic copolymer (weight average molecular weight: 600,000) obtained under the name "KARENZ MOI" was used as the acrylic polymer (C). To 100 parts by mass of the acrylic polymer (C), 0.5 part by mass of trimethylolpropane addition toluene diisocyanate (manufactured by TOSOH Co., Ltd., product name "CORONATE L") as a crosslinking agent was added as a photopolymerization agent. 1.4 parts by mass of 1-hydroxycyclohexylphenyl ketone ("Irgacure 184" manufactured by BASF Corporation) as the starting agent, adjusted to a solid content concentration of 20% by mass using toluene, and stirred for 30 minutes to obtain a solution of an adhesive composition. Using the obtained adhesive composition, an adhesive sheet was produced in the same manner as in Example 1. [Comparative Example 2] An intermediate layer-attached base material C was obtained in the same manner as the intermediate layer-attached base material A (Example), except that the addition amount of the acrylic polymer (B) was changed to 67 parts by mass. A surface protection sheet was produced in the same manner as in Example 2 except that the substrate C with an intermediate layer was used. [Comparative Example 3] An intermediate layer-attached base material D was obtained in the same manner as the intermediate layer-attached base material A (Example 1), except that the addition amount of the acrylic polymer (B) was changed to 107 parts by mass. A surface protection sheet was produced in the same manner as in Example 2 except that the substrate D with an intermediate layer was used. [0084] [0085] As can be understood from the above Examples 1 and 2, by setting the difference in elastic coefficient to be smaller than 20 MPa, the interlayer strength can be increased. Therefore, when the adhesive sheet for semiconductor processing is hardened and peeled from the workpiece, Prevents interlayer peeling between the intermediate layer and the adhesive layer. In contrast, in Comparative Examples 1 to 3, since the difference in elasticity coefficient is large, the interlayer strength becomes low. Therefore, when the adhesive sheet for semiconductor processing is hardened and peeled off from the workpiece, it is not possible to sufficiently prevent the occurrence between the intermediate layer and the adhesive layer. Delamination between layers.

Claims (8)

An adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing including a substrate, an intermediate layer, and an adhesive layer in this order, wherein the intermediate layer is made of an acrylic polymer (A) containing non-energy-ray-curable, A layer formed with a composition for forming an intermediate layer of an energy-ray-curable acrylic polymer (B) having a weight-average molecular weight of 50,000 to 250,000, and the adhesive layer is energy-ray-curable. The difference in elastic coefficient between the latter intermediate layer and the adhesive layer at 23 ° C is 20 MPa or less. The adhesive sheet for semiconductor processing according to claim 1, wherein in the composition for forming an intermediate layer, the acrylic polymer (B) is less than 25 parts by mass with respect to 100 parts by mass of the acrylic polymer (A). For example, the adhesive sheet for semiconductor processing of claim 1 or 2, wherein the weight average molecular weight of the acrylic polymer (A) is 300,000 to 1.5 million. The adhesive sheet for semiconductor processing according to claim 1 or 2, wherein the aforementioned adhesive layer is formed of an adhesive composition containing an energy ray-curable acrylic polymer (C). For example, the adhesive sheet for semiconductor processing according to claim 4, wherein the acrylic polymer (C) is a reactant obtained by reacting an acrylic copolymer (C0) with a polymerizable compound (Xc) having an energy ray polymerizable group. Acrylic copolymer (C1), the acrylic copolymer (C0) has a constituent unit derived from an alkyl (meth) acrylate (c1) having 1 to 18 carbon atoms, The constituent unit of the functional group monomer (c2). For example, the adhesive sheet for semiconductor processing of claim 4, wherein the weight average molecular weight of the acrylic polymer (C) is 100,000 to 1.5 million. The adhesive sheet for semiconductor processing according to claim 4, wherein the composition for forming the intermediate layer contains 0.3 to 15 parts by mass of a photopolymerization initiator relative to 100 parts by mass of the acrylic polymer (A), and the adhesive The composition is a photopolymerization initiator containing 0.5 to 15 parts by mass based on 100 parts by mass of the acrylic polymer (C). The adhesive sheet for semiconductor processing according to claim 1 or 2, wherein the acrylic polymer (B) is a reaction obtained by reacting the acrylic copolymer (B0) with a polymerizable compound (Xb) having an energy ray polymerizable group. The acrylic copolymer (B1) has a constituent unit derived from an alkyl (meth) acrylate (b1) having a carbon number of 1 to 18 derived from an alkyl group, and a source A constituent unit of the functional group-containing monomer (b2).