Method for manufacturing adhesive sheets for semiconductor processing and semiconductor devices

Abstract

To provide an adhesive sheet for semiconductor processing with excellent transportability after workpiece processing and a manufacturing method for a semiconductor device using the same.SOLUTION: The adhesive sheet for semiconductor processing has a surface coat layer, a buffer layer, a substrate, and an adhesive layer, in this order. The difference between the haze value after heat treatment under specified conditions and the haze value before the heat treatment [haze value after heat treatment - haze value before heat treatment] is 2.0% or less. The manufacturing method for a semiconductor device using the same is provided.SELECTED DRAWING: None

Description

[Technical Field] 【0001】 This invention relates to an adhesive sheet for semiconductor processing and a method for manufacturing a semiconductor device. [Background technology] 【0002】 As information terminal devices become thinner, smaller, and more multifunctional at an accelerating pace, the semiconductor devices installed in these devices are also required to be thinner and more densely packed. One method used to thin semiconductor devices has been to grind the back surface of the semiconductor wafer used in the semiconductor device. Back surface grinding of a semiconductor wafer is performed by attaching a semiconductor processing adhesive sheet for back surface grinding (hereinafter also called a "back grind sheet") to the surface of the semiconductor wafer, and protecting the surface of the semiconductor wafer with this sheet. The back grind sheet is peeled off and removed from the surface of the semiconductor wafer after back surface grinding. 【0003】 In recent years, pre-dicing and stealth pre-dicing methods have been put into practical use as grinding and dicing methods that can thin semiconductor chips while suppressing damage to them. The pre-dicing method is a method in which grooves of a predetermined depth are formed on the surface of a semiconductor wafer with a dicing blade or the like, and then the semiconductor wafer is ground from the back side down to the grooves to dicate it into semiconductor chips. The stealth pre-dicing method is a method in which a modified region is formed inside the semiconductor wafer by irradiation with laser light, and then the semiconductor wafer is ground from the back side, and the modified region is used as the starting point for splitting to dicate it into semiconductor chips. In these methods as well, a backgrind sheet is used to protect the surface of the semiconductor wafer. 【0004】 Along with the development of these thinning process technologies, adhesive sheets for semiconductor processing are also required to have functions that enable the thinning of semiconductor chips with good yield, and various studies are being conducted to address this. Patent Document 1 discloses an adhesive sheet for protecting the surface of a semiconductor wafer, applicable to a pre-dicing method or a stealth pre-dicing method, comprising a base film, an intermediate layer made of an adhesive and provided on at least one side of the base film, and an outermost adhesive layer provided on the outermost layer opposite the base film of the intermediate layer, wherein the intermediate layer is made of a material that hardens by a curing treatment after the adhesive sheet is formed. [Prior art documents] [Patent Documents] 【0005】 [Patent Document 1] Japanese Patent Publication No. 2015-56446 [Overview of the project] [Problems that the invention aims to solve] 【0006】 According to the adhesive sheet for protecting the surface of a semiconductor wafer described in Patent Document 1, it is possible to suppress kerf shift, which occurs when the original chip spacing is disrupted after the semiconductor wafer has been separated into individual chips, to suppress contamination of the semiconductor wafer by grinding debris, and to prevent adhesive residue from remaining on the chips when the surface protection tape is peeled off. 【0007】 Incidentally, adhesive sheets for semiconductor processing are sometimes equipped with a buffer layer to absorb vibrations, shocks, etc. that occur when processing workpieces such as semiconductor wafers, and to prevent damage to the workpieces. The buffer layer is made of a material that is more easily deformed than the base material and is located on the surface opposite to the adhesive layer of the base material. Therefore, it may be unintentionally damaged during the manufacturing of adhesive sheets for semiconductor processing or during workpiece processing. To prevent this, it is effective to form a surface coating layer on the surface of the buffer layer opposite to the base material. Furthermore, the surface coating layer may play a role not only in preventing damage to the buffer layer but also in suppressing the adhesion of grinding debris. For example, when grinding the back surface of a workpiece, the back grind sheet is fixed to a support device such as a chuck table. If grinding debris is present between the back grind sheet and the table of the support device, cracks may occur in the workpiece due to the impact when fixing the workpiece to the table, the pressure during back grinding, vibration, etc., starting from the area where the grinding debris is present. By providing a surface coating layer that suppresses the adhesion of grinding debris on the surface of the back grind sheet that is fixed to the support device, the occurrence of the above problem can be suppressed. 【0008】 However, according to the inventors' research, when a workpiece is attached to a semiconductor processing adhesive sheet having a surface coating layer, and a predetermined processing is performed with the surface coating layer fixed to a support device, it is sometimes impossible to lift the workpiece with the semiconductor processing adhesive sheet attached from the support device after processing, making it impossible to transport. This is thought to be due to the surface coating layer becoming excessively attached to the support device due to pressure, heat, etc., during the processing of the workpiece. 【0009】 This invention has been made in view of the above circumstances, and aims to provide an adhesive sheet for semiconductor processing that has excellent transportability after workpiece processing, and a method for manufacturing a semiconductor device using the semiconductor processing adhesive sheet. [Means for solving the problem] 【0010】 As a result of diligent research, the inventors of the present invention have found that the above problem can be solved by a semiconductor processing adhesive sheet having a surface coating layer, a buffer layer, a substrate, and an adhesive layer in that order, wherein the difference between the haze value after heat treatment under specific conditions and the haze value before heat treatment [haze value after heat treatment - haze value before heat treatment] is 2.0% or less, and have completed the present invention described below. 【0011】 In other words, the present invention relates to the following [1] to [9]. [1] The surface coating layer, buffer layer, substrate and adhesive layer are provided in this order. An adhesive sheet for semiconductor processing, wherein the difference between the haze value after heat treatment and the haze value before heat treatment [haze value after heat treatment - haze value before heat treatment] is 2.0% or less. (Conditions for heat treatment) A metal plate 1 having a polished surface is placed on a hot plate maintained at a temperature of 90°C with the polished surface facing upwards. A semiconductor processing adhesive sheet, having a release sheet attached to the adhesive layer, is placed on the polished surface of the metal plate 1 with the surface coating layer facing the polished surface. A metal plate 2 having a polished surface on the side in contact with the release sheet, and a weight are stacked in this order on the release sheet of the semiconductor processing adhesive sheet, thereby heating the semiconductor processing adhesive sheet at 90°C for 1 minute. The semiconductor processing adhesive sheet used in the heat treatment has a rectangular shape in plan view and dimensions of 5 cm x 5 cm in plan view. Both metal plate 1 and metal plate 2 are made of SUS304, have a rectangular shape in plan view, dimensions of 7 cm x 15 cm in plan view, a thickness of 0.5 mm, and a weight of 40 g. The polished surface is finished with 600 grit polishing. The weight has a cylindrical shape with a weight of 1 kg and a circular base with a diameter of 4 cm. Metal plate 1, the semiconductor processing adhesive sheet, and metal plate 2 are placed so that their four sides are parallel to each other, and metal plate 1, the semiconductor processing adhesive sheet, metal plate 2, and the weight are placed so that their respective center points coincide in plan view. [2] The semiconductor processing adhesive sheet according to [1] above, wherein the surface coating layer is an organic layer containing a resin component. [3] The semiconductor processing adhesive sheet according to [2] above, wherein the resin component is a thermoplastic resin. [4] The semiconductor processing adhesive sheet according to [3] above, wherein the thermoplastic resin is a polymer of a compound having one or more ethylenically unsaturated bonds. [5] The semiconductor processing adhesive sheet according to any of [1] to [4] above, wherein the thickness of the surface coating layer is 0.05 to 10 μm. [6] The semiconductor processing adhesive sheet according to any one of [1] to [5] above, wherein the buffer layer is a layer formed from a buffer layer-forming composition containing urethane (meth) acrylate. [7] The semiconductor processing adhesive sheet according to any one of [1] to [6] above, which is used for back grinding of a semiconductor wafer. [8] A step of attaching the semiconductor processing adhesive sheet according to any one of [1] to [7] above to the surface of a semiconductor wafer with the adhesive layer as the attachment surface, A step of grinding the back surface of the semiconductor wafer while fixing the surface coat layer side of the semiconductor processing adhesive sheet attached to the semiconductor wafer by a support device, A method for manufacturing a semiconductor device, comprising: [9] A dicing line formation step which is a step a of forming a groove on the surface of a semiconductor wafer, or a step b of forming a modified region inside the semiconductor wafer from the surface or back surface of the semiconductor wafer, After the step a, or before or after the step b, a sheet attachment step of attaching the semiconductor processing adhesive sheet according to any one of [1] to [7] above to the surface of the semiconductor wafer with the adhesive layer as the attachment surface, A grinding and singulation step of grinding the back surface of the semiconductor wafer while fixing the surface coat layer side of the semiconductor processing adhesive sheet attached to the semiconductor wafer by a support device, and singulating the semiconductor wafer into a plurality of semiconductor chips starting from the groove or the modified region, A method for manufacturing a semiconductor device, comprising: [Advantages of the Invention] 【0012】 According to the present invention, it is possible to provide a semiconductor processing adhesive sheet excellent in transportability after workpiece processing and a method for manufacturing a semiconductor device using the semiconductor processing adhesive sheet. [Embodiments for Carrying out the Invention] 【0013】 In this specification, for preferred numerical ranges, the lower and upper limits described step by step can be combined independently. For example, from the description "preferably 10 to 90, more preferably 30 to 60", it is also possible to combine the "preferred lower limit (10)" and the "more preferred upper limit (60)" to obtain "10 to 60". 【0014】 In this specification, the "active ingredient" refers to the component among the components contained in the target composition excluding the diluent solvent. 【0015】 In this specification, for example, "(meth)acrylic acid" means both "acrylic acid" and "methacrylic acid", and the same applies to other similar terms. 【0016】 In this specification, the "energy ray" means those having energy quanta among electromagnetic waves or charged particle beams, and examples thereof include ultraviolet rays, radiation, electron beams, etc. Ultraviolet rays can be irradiated, for example, by using an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, etc. as an ultraviolet ray source. Electron beams can be irradiated with those generated by an electron beam accelerator or the like. In this specification, "energy ray polymerizability" means the property of polymerizing by irradiating an energy ray. Also, "energy ray curability" means the property of curing by irradiating an energy ray, and "non-energy ray curability" means the property of not having energy ray curability. 【0017】 In this specification, the "surface" of a semiconductor wafer refers to the surface on which a circuit is formed, and the "back surface" refers to the surface on which no circuit is formed. 【0018】 The mechanism of action described in this specification is speculative and does not limit the mechanism by which the semiconductor processing adhesive sheet of the present invention exhibits its effects. 【0019】 [Adhesive Sheet for Semiconductor Processing] The semiconductor processing adhesive sheet of this embodiment (hereinafter also referred to as "adhesive sheet") has a surface coating layer, a buffer layer, a substrate, and an adhesive layer in this order, and the difference between the haze value after heat treatment under the above conditions and the haze value before heat treatment [haze value after heat treatment - haze value before heat treatment] (hereinafter also referred to as "haze difference before and after heat treatment") is 2.0% or less. 【0020】 The adhesive sheet of this embodiment is attached to the surface of a semiconductor device, which is a workpiece, and is used to perform a predetermined process on the semiconductor device while protecting the surface. After the predetermined process has been performed on the workpiece, the adhesive sheet of this embodiment is peeled off and removed from the semiconductor device. In this embodiment, "semiconductor device" refers to any device that can function by utilizing semiconductor properties, such as semiconductor wafers, semiconductor chips, electronic components including said semiconductor chips, and electronic devices equipped with said electronic components. Among these, the adhesive sheet of this embodiment is suitable for processing semiconductor wafers. 【0021】 The adhesive sheet of this embodiment exhibits excellent transportability after workpiece processing. The reason for this is not entirely clear, but it is presumed to be as follows. It is believed that conventional surface coating layers melt or deform due to heat, pressure, etc., during workpiece processing, resulting in excessive adhesion to the support device and thus reducing the transportability of the workpiece after processing. Based on the above estimation, the inventors conducted studies to suppress the deterioration of the surface coating layer due to heat, pressure, etc., and found that the difference in haze value before and after heat treatment under specific conditions can be used as an indicator of deterioration of the surface coating layer. That is, when the difference in haze before and after the above heat treatment is 2.0% or less, deformation and melting of the surface coating layer during workpiece processing are suppressed, and it is presumed that this prevents excessive adhesion to the support device, resulting in good transportability after workpiece processing. 【0022】 (Difference in haze before and after heat treatment of adhesive sheet) The adhesive sheet of this embodiment has a difference of 2.0% or less between the haze value after heat treatment and the haze value before heat treatment [haze value after heat treatment - haze value before heat treatment]. (Conditions for heat treatment) A metal plate 1 having a polished surface is placed on a hot plate maintained at a temperature of 90°C with the polished surface facing upwards. A semiconductor processing adhesive sheet, having a release sheet attached to the adhesive layer, is placed on the polished surface of the metal plate 1 with the surface coating layer facing the polished surface. A metal plate 2 having a polished surface on the side in contact with the release sheet, and a weight are stacked in this order on the release sheet of the semiconductor processing adhesive sheet, thereby heating the semiconductor processing adhesive sheet at 90°C for 1 minute. The semiconductor processing adhesive sheet used in the above heat treatment shall have a rectangular shape in plan view and dimensions of 5 cm x 5 cm in plan view. Both metal plate 1 and metal plate 2 shall be made of SUS304, have a rectangular shape in plan view, dimensions of 7 cm x 15 cm in plan view, a thickness of 0.5 mm, a weight of 40 g, and a surface finished by 600 grit polishing. The weight shall have a cylindrical shape with a weight of 1 kg and a circular base with a diameter of 4 cm. Metal plate 1, the semiconductor processing adhesive sheet, and metal plate 2 shall be placed so that their four sides are parallel to each other, and metal plate 1, the semiconductor processing adhesive sheet, metal plate 2, and the weight shall be placed so that their respective center points coincide in plan view. 【0023】 If the haze difference before and after the above heat treatment is 2.0% or less, the adhesive sheet of this embodiment will have excellent transportability after workpiece processing. From the viewpoint of improving the transportability after workpiece processing, the difference in haze before and after the above heat treatment is preferably 1.6% or less, more preferably 1.3% or less, and even more preferably 1.0% or less. Furthermore, the lower limit of the haze difference before and after the above heat treatment is not particularly limited, but it may be 0%, or from the viewpoint of ease of manufacture, it may be 0.1% or more, or 0.2% or more. The difference in haze before and after heat treatment can be measured by the method described in the examples. 【0024】 The haze value of the adhesive sheet of this embodiment before heat treatment under the above conditions is not particularly limited, but is preferably 4 to 10%. Furthermore, the haze value of the adhesive sheet of this embodiment after heat treatment under the above conditions is not particularly limited, but is preferably 4 to 12%, more preferably 4.5 to 10%, and even more preferably 5 to 9%. If the haze value before and after heat treatment falls within the above range, the appearance and energy ray transmittance of the adhesive sheet of this embodiment can be improved, and there is a tendency to gain greater freedom in material selection. 【0025】 The adhesive sheet of this embodiment may or may not have layers other than the surface coating layer, buffer layer, substrate, and adhesive layer. Examples of layers other than the surface coating layer, buffer layer, substrate, and adhesive layer include an intermediate layer provided between the substrate and the adhesive layer, and a release sheet provided on the side of the adhesive layer opposite to the substrate. The following describes each component that makes up the adhesive sheet of this embodiment. 【0026】 <Surface coating layer> The surface coating layer is a layer provided on the side opposite to the substrate of the buffer layer, and is fixed by a support device when processing semiconductor devices. 【0027】 The surface coating layer of the adhesive sheet in this embodiment may be an inorganic layer or an organic layer, but from the viewpoint of productivity and handling of the adhesive sheet, it is preferable that it be an organic layer, and more preferably an organic layer containing a resin component. 【0028】 (Resin components) As for the resin component, a thermoplastic resin is preferred from the viewpoint of reducing the amount of grinding debris adhering to it. The resin component may be used alone or in combination of two or more types. 【0029】 [Thermoplastic resin] As for the thermoplastic resin, from the viewpoint of further reducing the amount of grinding debris adhering to it, it is preferable that it be a polymer of a compound having one or more ethylenically unsaturated bonds (hereinafter also referred to as "polymer (1)"). In this embodiment, "ethylenically unsaturated bond" refers to a carbon-carbon double bond capable of addition reactions, and does not include double bonds in aromatic rings. 【0030】 The content of constituent units derived from compounds having one or more ethylenically unsaturated bonds in polymer (1) is not particularly limited, but is preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. When the content of constituent units derived from compounds having one or more ethylenically unsaturated bonds is above the above lower limit, the amount of grinding debris adhering tends to be further reduced. Furthermore, the content of constituent units derived from compounds having one or more ethylenically unsaturated bonds in polymer (1) may be 100% by mass, but may be 99.5% by mass or less, or 99% by mass or less, for example, in order to include constituent units derived from other monomers. 【0031】 Compounds having one or more ethylenically unsaturated bonds include, for example, styrene compounds such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, chlorostyrene, and methoxystyrene; linear monoolefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 5-methyl-1-hexene; linear non-conjugated dienes (non-conjugated diolefins) such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene; and conjugated dienes such as 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. (Conjugated diolefins); cyclic monoolefins such as cyclobutene, cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, cycloheptene, and cyclooctene; cyclic diolefins such as cyclohexadiene, methylcyclohexadiene, cyclooctadiene, methylcyclooctadiene, and phenylcyclooctadiene; polycyclic olefins such as norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, and tetracyclo[7.4.0.110,13.02,7]trideca-2,4,6,11-tetraene; monomers having an oxygen atom and an ethylenically unsaturated bond, such as maleic anhydride and vinyl acetate; monomers having a nitrogen atom and an ethylenically unsaturated bond, such as maleimide compounds and nitrile monomers. 【0032】 Among the above options, polymer (1) is preferably one that contains structural units derived from styrene compounds. Hereinafter, polymer (1) containing structural units derived from styrene compounds will be referred to as "styrene resin". 【0033】 The content of constituent units derived from styrene compounds in the styrene resin is not particularly limited, but is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more. When the content of constituent units derived from styrene compounds in the styrene-based resin is above the above lower limit, the heat resistance of the surface coating layer tends to be good. Furthermore, the content of constituent units derived from styrene compounds in the styrene resin is not particularly limited, but is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less. When the content of constituent units derived from styrene compounds in styrene resin is below the above upper limit, it tends to be easier to achieve a good balance between the amount of grinding debris adhering and heat resistance by introducing constituent units other than those derived from styrene compounds. 【0034】 Other structural units that the styrene resin may contain, besides those derived from styrene compounds, include, for example, structural units derived from compounds other than styrene compounds, such as those listed above as compounds having one or more ethylenically unsaturated bonds. Among these, it is more preferable that the styrene resin contains structural units derived from conjugated dienes. The constituent units derived from conjugated dienes include constituent units formed by addition polymerization of the above-mentioned conjugated dienes, and constituent units formed by hydrogenation of the constituent units formed by addition polymerization of the above-mentioned conjugated dienes. Examples of structural units formed by hydrogenating structural units formed by the addition polymerization of conjugated dienes include ethylene-propylene units formed by hydrogenating structural units formed by the addition polymerization of isoprene, and ethylene-butylene units formed by hydrogenating structural units formed by the addition polymerization of 1,3-butadiene. When a styrene-based resin contains structural units derived from a conjugated diene, the content of such units in the styrene-based resin is not particularly limited, but is preferably 20 to 50% by mass, more preferably 25 to 45% by mass, and even more preferably 30 to 40% by mass. When the content of structural units derived from conjugated dienes in the styrene-based resin is above the lower limit mentioned above, the amount of grinding debris adhering to the resin tends to be reduced. Conversely, when the content of structural units derived from conjugated dienes in the styrene-based resin is below the upper limit mentioned above, the transportability after workpiece processing tends to be improved. 【0035】 As for the styrene-based resin, from the viewpoint of the amount of grinding debris adhering to it and heat resistance, one or more selected from the group consisting of styrene-butadiene block copolymer, styrene-ethylene-propylene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer (hereinafter also referred to as "SEBS"), and styrene-ethylene-propylene-styrene block copolymer (hereinafter also referred to as "SEPS") is preferred, and one or more selected from the group consisting of styrene-ethylene-butylene-styrene block copolymer and styrene-ethylene-propylene-styrene block copolymer is more preferred. 【0036】 Examples of polymers other than styrene resins (1) include homopolymers such as polyethylene, polypropylene, and polybutadiene; binary copolymers such as ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylate copolymer, ethylene-tetracyclododecene copolymer, propylene-butene copolymer, propylene-maleic anhydride copolymer, propylene-vinyl acetate copolymer, propylene-(meth)acrylate copolymer, and propylene-tetracyclododecene copolymer; ethylene-maleic anhydride-vinyl acetate copolymer, ethylene-maleic anhydride-(meth)acrylate copolymer, and ethylene-vinyl acetate copolymer Examples include polypolymers such as ru-(meth)acrylate copolymer, propylene-maleic anhydride-vinyl acetate copolymer, propylene-maleic anhydride-(meth)acrylate copolymer, propylene-vinyl acetate-(meth)acrylate copolymer, ethylene-propylene-maleic anhydride copolymer, ethylene-propylene-vinyl acetate copolymer, ethylene-propylene-(meth)acrylate copolymer, ethylene-butene-maleic anhydride copolymer, ethylene-butene-vinyl acetate copolymer, ethylene-butene-(meth)acrylate copolymer, propylene-butene-maleic anhydride copolymer, propylene-butene-vinyl acetate copolymer, and propylene-butene-(meth)acrylate copolymer. 【0037】 The mass-average molecular weight (Mw) of the thermoplastic resin is not particularly limited, but is preferably 10,000 to 600,000, more preferably 15,000 to 500,000, and even more preferably 20,000 to 400,000. When the mass-average molecular weight (Mw) of the thermoplastic resin is above the lower limit mentioned above, the transportability after workpiece processing tends to be better. Conversely, when the mass-average molecular weight (Mw) of the thermoplastic resin is below the upper limit mentioned above, the solvent solubility of the thermoplastic resin improves, and the formation of a surface coating layer by application tends to be easier. In this embodiment, the mass-average molecular weight (Mw) refers to the value on a standard polystyrene basis measured by gel permeation chromatography (GPC), and specifically, the value measured by the method described in the example. 【0038】 The resin component content in the surface coating layer is not particularly limited, but is preferably 30 to 95% by mass, more preferably 40 to 90% by mass, and even more preferably 45 to 85% by mass, relative to the total amount (100% by mass) of the surface coating layer. When the resin component content is above the lower limit mentioned above, the transportability after workpiece processing tends to be better. Conversely, when the resin component content is below the upper limit mentioned above, it tends to be easier to achieve better adhesion between the buffer layer and the surface coating layer. 【0039】 (Hydrophobic treated silica) Preferably, the surface coating layer further contains hydrophobized silica along with the resin component. Because the surface coating layer contains hydrophobic silica, the adhesive sheet of this embodiment tends to have a reduced amount of grinding debris adhering to it. Hydrophobized silica may be used alone or in combination of two or more types. 【0040】 Examples of hydrophobized silica include raw silica that has been surface-treated with a hydrophobic treatment agent. The silica raw material to be hydrophobized may be, for example, wet-process silica produced by wet methods such as the precipitation method, gel method, or sol-gel method, or it may be dry-process silica such as fumed silica or fused silica. Among these, wet-process silica is preferred from the viewpoint of ease of hydrophobization, and precipitation-process silica is more preferred. 【0041】 Examples of hydrophobic treatment agents include organosilicon compounds, fatty acids, and fatty acid metal salts. Hydrophobic treatment agents may be used individually or in combination of two or more types. 【0042】 Methods for surface treating raw silica with a hydrophobic treatment agent include, for example, contacting the raw silica with the hydrophobic treatment agent in a solvent, contacting the raw silica with the vapor of the hydrophobic treatment agent transported by a carrier gas such as nitrogen, and directly contacting the raw silica with the undiluted hydrophobic treatment agent. 【0043】 The shape of the hydrophobized silica is not particularly limited, and examples include spherical, irregular, etc. Among these, an irregular shape is preferred from the viewpoint of further reducing the amount of grinding debris adhering to it. 【0044】 Examples of commercially available hydrophobic silica include the "AEROSIL® series" from Evonik, the "QSG series" from Shin-Etsu Chemical Co., Ltd., the "Nipsil® SS series" from Tosoh Silica Co., Ltd., and the "SYLOPHOBIC® series" from Fuji Silicia Chemical Co., Ltd. 【0045】 When the surface coating layer contains hydrophobically treated silica, the amount of hydrophobically treated silica in the surface coating layer is not particularly limited, but is preferably 1 to 150 parts by mass, more preferably 10 to 120 parts by mass, even more preferably 20 to 100 parts by mass, and even more preferably 30 to 90 parts by mass, per 100 parts by mass of the resin component. When the content of hydrophobically treated silica is above the lower limit mentioned above, the amount of grinding debris adhering tends to be further reduced. Conversely, when the content of hydrophobically treated silica is below the upper limit mentioned above, the film-forming properties of the surface coating layer tend to improve. 【0046】 The surface coating layer may contain components other than resin components and hydrophobized silica. For example, the surface coating layer is preferably a layer formed by irradiating a composition containing an energy-ray polymerizable polyfunctional compound and a photopolymerization initiator together with a resin component, from the viewpoint of improving adhesion with the buffer layer. In the following explanation, the composition used to form the surface coating layer may be referred to as the "surface coating layer forming composition." 【0047】 (Energy-ray polymerizable polyfunctional compound) Energy-ray polymerizable polyfunctional compounds are compounds having two or more energy-ray polymerizable functional groups. Energy-ray polymerizable polyfunctional compounds may be used individually or in combination of two or more. 【0048】 The number of energy-ray polymerizable functional groups in an energy-ray polymerizable polyfunctional compound is preferably 2 to 10, more preferably 3 to 8, and even more preferably 4 to 7. A preferred energy-ray polymerizable functional group in an energy-ray polymerizable polyfunctional compound is a (meth)acryloyl group. 【0049】 As the energy-ray polymerizable polyfunctional compound, polyfunctional (meth)acrylate monomers are preferred. Examples of polyfunctional (meth)acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, di(acryloxyethyl) isocyanurate, allylated cyclohexyl di(meth)acrylate, isocyanurate ethylene oxide-modified diacrylate, and other bifunctional (meth)acrylate monomers; trimethylolpropane tri(meth)acrylate, di Examples include pentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl) isocyanurate, bis(acryloxyethyl)hydroxyethyl isocyanurate, ethylene oxide-modified isocyanurate triacrylate, ε-caprolactone-modified tris(acryloxyethyl) isocyanurate, diglycerin tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate. Among these, dipentaerythritol hexa(meth)acrylate and dipentaerythritol penta(meth)acrylate are preferred, and dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate are more preferred. 【0050】 When the surface coating layer forming composition contains an energy-ray polymerizable polyfunctional compound, the amount of the energy-ray polymerizable polyfunctional compound is preferably 10 to 60 parts by mass, more preferably 14 to 40 parts by mass, and even more preferably 17 to 30 parts by mass, per 100 parts by mass of the resin component. When the content of the energy-ray polymerizable polyfunctional compound is above the lower limit, the surface coating layer tends to exhibit excellent adhesion to the buffer layer. Conversely, when the content of the energy-ray polymerizable polyfunctional compound is below the upper limit, it tends to be easier to achieve a good balance between adhesion to the buffer layer and transportability after workpiece processing. 【0051】 (Photopolymerization initiator) Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acyl phosphinoxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. More specifically, examples include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. The photopolymerization initiator may be used alone or in combination of two or more types. 【0052】 When a surface coating layer forming composition contains a photopolymerization initiator, the amount is not particularly limited, but from the viewpoint of ensuring that the energy ray polymerization reaction proceeds homogeneously and sufficiently, it is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass, per 100 parts by mass of the energy ray polymerizable polyfunctional compound. 【0053】 (Other ingredients) The surface coating layer may contain other components not mentioned above, as long as they do not impair the effects of the present invention. Examples of other components include resins other than those mentioned above; additives such as antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, and dyes; and so on. 【0054】 (Storage modulus E' of the surface coating layer at 90°C) The storage modulus E' of the surface coating layer at 90°C is not particularly limited, but is preferably 100 MPa or higher, more preferably 120 MPa or higher, even more preferably 150 MPa or higher, and even more preferably 170 MPa or higher. When the storage modulus E' of the surface coating layer at 90°C is above the lower limit of the above value, the transportability after workpiece processing tends to be better. Furthermore, the storage modulus E' of the surface coating layer at 90°C is not particularly limited, but is preferably 1,500 MPa or less, more preferably 1,000 MPa or less, even more preferably 800 MPa or less, and even more preferably 600 MPa or less. When the storage modulus E' of the surface coating layer at 90°C is below the above upper limit, it is easier to obtain an adhesive sheet with appropriate flexibility, and the adhesive sheet tends to have excellent handling properties. The storage modulus E' of the surface coating layer at 90°C can be measured by the method described in the examples. 【0055】 (Thickness of the surface coating layer) The thickness of the surface coating layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.2 to 7 μm, and even more preferably 1 to 4 μm. When the thickness of the surface coating layer is greater than or equal to the lower limit mentioned above, a uniform layer can be formed, and the transportability after workpiece processing tends to be better. Conversely, when the thickness of the surface coating layer is less than or equal to the upper limit mentioned above, the buffering effect of absorbing irregularities such as foreign matter on the chuck table tends to be more easily obtained. 【0056】 <Buffer layer> The buffer layer is a layer provided between the base material and the surface coating layer. It absorbs vibrations and shocks that occur during back grinding, preventing cracks from forming in the workpiece. Furthermore, by providing a buffer layer, it is possible to absorb irregularities such as foreign matter present on the table of the support device, thereby improving the support device's ability to hold the adhesive sheet. 【0057】 (Buffer layer forming composition) The buffer layer can be formed from a buffer layer-forming composition. From the viewpoint of obtaining physical properties suitable for a buffer layer, it is preferable that the buffer layer is a layer obtained by energy ray curing of a buffer layer-forming composition containing an energy ray polymerizable compound. The buffer layer forming composition preferably contains urethane (meth)acrylate (a1) as an energy-ray polymerizable compound. The inclusion of urethane (meth)acrylate (a1) in the buffer layer forming composition tends to allow the storage modulus of the buffer layer to be adjusted to a favorable range. Furthermore, from a similar viewpoint, the buffer layer forming composition more preferably contains, in addition to urethane (meth)acrylate (a1), one or more polymerizable compounds selected from the group consisting of polymerizable compounds having alicyclic or heterocyclic groups with 6 to 20 ring-forming atoms (a2) and polymerizable compounds having functional groups (a3). It is even more preferable that, in addition to urethane (meth)acrylate (a1), it contains polymerizable compounds having alicyclic or heterocyclic groups with 6 to 20 ring-forming atoms (a2) and polymerizable compounds having functional groups (a3). In this specification, the number of ring-forming atoms refers to the number of atoms that constitute the ring itself in a compound with a structure in which atoms are bonded in a ring. Atoms that do not constitute a ring (for example, hydrogen atoms bonded to atoms that constitute a ring), and atoms included in substituents when the ring is substituted by substituents, are not included in the number of ring-forming atoms. 【0058】 [Urethane (meth)acrylate (a1)] Urethane (meth)acrylate (a1) is a compound having a (meth)acryloyl group and a urethane bond, and has the property of polymerizing upon irradiation with energy rays. Urethane (meth)acrylate (a1) may be used alone or in combination of two or more types. 【0059】 The mass-average molecular weight (Mw) of urethane (meth)acrylate (a1) is not particularly limited, but is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, and even more preferably 3,000 to 20,000. 【0060】 The number of (meth)acryloyl groups in one molecule of urethane (meth)acrylate (a1) is not particularly limited, but is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. 【0061】 Urethane (meth)acrylate (a1) can be obtained, for example, by reacting a terminal isocyanate urethane prepolymer, which is obtained by reacting a polyol compound with a polyvalent isocyanate compound, with a (meth)acrylate having a hydroxyl group. 【0062】 The polyol compound is not particularly limited as long as it is a compound having two or more hydroxyl groups. Specific examples of polyol compounds include alkylenediols, polyether-type polyols, polyester-type polyols, and polycarbonate-type polyols. Among these, polyester-type polyols are preferred. The polyol compound may be a bifunctional diol, a trifunctional triol, or a polyol with four or more functions, but a bifunctional diol is preferred, and a polyester-type diol is more preferred. Polyol compounds may be used individually or in combination of two or more. 【0063】 Examples of polyvalent isocyanate compounds include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and ω,ω'-diisocyanate dimethylcyclohexane; and aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, and naphthalene-1,5-diisocyanate. Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferred. Polyvalent isocyanate compounds may be used individually or in combination of two or more. 【0064】 The (meth)acrylate having a hydroxyl group to be reacted with the terminal isocyanate urethane prepolymer is not particularly limited, as long as it is a compound having at least one molecule containing both a hydroxyl group and a (meth)acryloyl group. Examples of (meth)acrylates having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate; hydroxyl group-containing (meth)acrylamides such as N-methylol (meth)acrylamide; and reaction products obtained by reacting vinyl alcohol, vinyl phenol, or diglycidyl ester of bisphenol A with (meth)acrylic acid. Among these, hydroxyalkyl (meth)acrylates are preferred, and 2-hydroxyethyl (meth)acrylate is more preferred. The (meth)acrylates having a hydroxyl group may be used individually or in combination of two or more. 【0065】 The conditions for reacting the terminal isocyanate urethane prepolymer with the (meth)acrylate having a hydroxyl group are not particularly limited, but for example, the reaction can be carried out at 60-100°C for 1-4 hours in the presence of an organic solvent, catalyst, etc., which may be added as needed. 【0066】 The content of urethane (meth)acrylate (a1) in the buffer layer forming composition is not particularly limited, but is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and even more preferably 30 to 50% by mass, based on the total amount (100% by mass) of the active ingredients of the buffer layer forming composition. 【0067】 [Polymerizable compounds having alicyclic or heterocyclic groups with 6 to 20 ring-forming atoms (a2)] The film-forming properties of a buffer layer-forming composition tend to improve when it contains a polymerizable compound (a2) having an alicyclic or heterocyclic group with 6 to 20 ring-forming atoms (hereinafter also referred to as "polymerizable compound (a2) having an alicyclic or heterocyclic group"). Examples of atoms that form the ring structure of a heterocyclic group include carbon atoms, nitrogen atoms, oxygen atoms, and sulfur atoms. Polymerizable compounds (a2) having an alicyclic group or a heterocyclic group may be used individually or in combination of two or more. 【0068】 The polymerizable compound (a2) having an alicyclic or heterocyclic group is preferably a compound having a (meth)acryloyl group. The number of (meth)acryloyl groups in one molecule of a polymerizable compound (a2) having an alicyclic or heterocyclic group is not particularly limited, but is preferably one or more, more preferably one or two, and even more preferably one. 【0069】 The polymerizable compound (a2) having an alicyclic or heterocyclic group has 6 to 20 ring-forming atoms in the alicyclic or heterocyclic group, preferably 6 to 18, more preferably 6 to 16, and even more preferably 7 to 12. 【0070】 Examples of polymerizable compounds (a2) having an alicyclic or heterocyclic group include alicyclic group-containing (meth)acrylates such as isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, and adamantane (meth)acrylate; and heterocyclic group-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and morpholine (meth)acrylate. Among these, alicyclic group-containing (meth)acrylates are preferred, and isobornyl (meth)acrylate is more preferred. 【0071】 The content of polymerizable compounds (a2) having alicyclic or heterocyclic groups in the buffer layer forming composition is not particularly limited, but is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and even more preferably 30 to 50% by mass, based on the total amount (100% by mass) of the active ingredients of the buffer layer forming composition. 【0072】 [Polymerizable compounds having functional groups (a3)] The presence of a polymerizable compound (a3) ​​having a functional group in the buffer layer-forming composition tends to allow the viscosity of the buffer layer-forming composition to be adjusted to an appropriate range. Polymerizable compounds (a3) ​​having functional groups may be used individually or in combination of two or more. 【0073】 Examples of functional groups found in polymerizable compounds (a3) ​​include hydroxyl groups, epoxy groups, amide groups, and amino groups. The number of functional groups in one molecule of the polymerizable compound (a3) ​​having a functional group is one or more, preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. 【0074】 The polymerizable compound (a3) ​​having a functional group is preferably a compound having a (meth)acryloyl group together with the functional group. The number of (meth)acryloyl groups in one molecule of the polymerizable compound (a3) ​​having a functional group is not particularly limited, but is preferably one or more, more preferably one or two, and even more preferably one. 【0075】 Examples of polymerizable compounds having functional groups (a3) ​​include hydroxyl group-containing polymerizable compounds, epoxy group-containing polymerizable compounds, amide group-containing polymerizable compounds, amino group-containing polymerizable compounds, and the like. 【0076】 Examples of hydroxyl group-containing polymerizable compounds include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate; vinyl ether compounds such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether; and the like. 【0077】 Examples of epoxy group-containing polymerizable compounds include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether. 【0078】 Examples of polymerizable compounds containing amide groups include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, and N-vinylformamide. 【0079】 Examples of amino group-containing polymerizable compounds include amino group-containing (meth)acrylates such as primary amino group-containing (meth)acrylates, secondary amino group-containing (meth)acrylates, and tertiary amino group-containing (meth)acrylates. 【0080】 Among these, hydroxyl group-containing (meth)acrylates are preferred, and hydroxyl group-containing (meth)acrylates having an aromatic ring, such as 2-hydroxy-3-phenoxypropyl (meth)acrylate, are more preferred. 【0081】 The content of the polymerizable compound (a3) ​​having a functional group in the buffer layer forming composition is not particularly limited, but is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass, based on the total amount (100% by mass) of the active ingredients of the buffer layer forming composition. 【0082】 [Other polymerizable compounds] The buffer layer forming composition may contain other polymerizable compounds other than components (a1) to (a3), as long as the effects of the present invention are not impaired. Other polymerizable compounds include, for example, alkyl (meth)acrylates having alkyl groups with 1 to 20 carbon atoms; vinyl compounds such as styrene, N-vinylpyrrolidone, and N-vinylcaprolactam; and so on. Other polymerizable compounds may be used individually or in combination of two or more. The content of other polymerizable compounds in the buffer layer forming composition is not particularly limited, but is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 2% by mass, based on the total amount (100% by mass) of the active ingredients of the buffer layer forming composition. 【0083】 [Photopolymerization initiator] A buffer layer-forming composition containing an energy-ray polymerizable compound is preferably further containing a photopolymerization initiator, from the viewpoint of reducing the polymerization time and energy-ray irradiation dose. The photopolymerization initiator may be used alone or in combination of two or more types. 【0084】 Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acyl phosphinoxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. More specifically, examples include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. Among these, 1-hydroxycyclohexyl phenyl ketone is preferred. 【0085】 The content of the photopolymerization initiator in the buffer layer forming composition is not particularly limited, but from the viewpoint of ensuring that the energy ray curing reaction proceeds homogeneously and sufficiently, it is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass per 100 parts by mass of the energy ray polymerizable compound. 【0086】 (Other ingredients) The buffer layer forming composition may contain other components as long as they do not impair the effects of the present invention. Examples of other components include resin components other than the resins described above; and other additives such as antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, and dyes. 【0087】 (Young's modulus of the buffer layer) The Young's modulus of the buffer layer at 23°C is smaller than that of the substrate at 23°C, specifically, preferably less than 1,200 MPa, more preferably less than 1,000 MPa, and even more preferably less than 900 MPa. Furthermore, the Young's modulus of the buffer layer at 23°C is preferably 50 MPa or more, more preferably 100 MPa or more. When the Young's modulus of the buffer layer at 23°C is below the upper limit, the effect of absorbing vibrations and shocks generated during back grinding and the retention of the adhesive sheet tend to improve. Conversely, when the Young's modulus of the buffer layer at 23°C is above the lower limit, excessive deformation of the buffer layer during workpiece processing tends to be suppressed. The Young's modulus of the buffer layer at 23°C can be measured in accordance with JIS K 7127:1999 under conditions of a test speed of 200 mm / min. 【0088】 (Stress relaxation rate of the buffer layer) The stress relaxation rate of the buffer layer is not particularly limited, but is preferably 70-100%, more preferably 75-100%, and even more preferably 78-98%. When the stress relaxation rate of the buffer layer is within the above range, the effect of absorbing vibrations and shocks generated during backside grinding and the retention of the adhesive sheet tend to be higher. The stress relaxation rate of the buffer layer is determined by using a 200 μm thick buffer layer cut into a 15 mm x 140 mm specimen, gripping both ends of the specimen at 20 mm / min, and stretching it by 10% at a rate of 200 mm / min. The stress A (N / m) is measured in this specimen. 2 ), and stress B (N / m) 1 minute after extension cessation. 2 Using the value of ), it can be calculated from the following formula. Stress relaxation rate (%) = 100 × (AB) / A (%) 【0089】 (Thickness of the buffer layer) The thickness of the buffer layer is not particularly limited, but is preferably 5 to 70 μm, more preferably 7 to 50 μm, and even more preferably 10 to 40 μm. When the thickness of the buffer layer is greater than or equal to the lower limit mentioned above, the effect of absorbing vibrations and shocks generated during back grinding and the retention of the adhesive sheet tend to be higher. Conversely, when the thickness of the buffer layer is less than or equal to the upper limit mentioned above, the excessive deformation of the buffer layer during workpiece processing tends to be suppressed. 【0090】 <Adhesive layer> The adhesive layer is a layer provided on the side of the substrate opposite to the buffer layer, and is the layer that is attached to the workpiece. The adhesive layer is preferably formed from an energy-ray curable adhesive. By forming the adhesive layer from an energy-ray curable adhesive, the workpiece surface can be well protected by sufficient tackiness before energy-ray curing, and the peeling force is reduced after energy-ray curing, making it easy to peel off from the workpiece. 【0091】 Examples of energy-ray curable adhesives include the following X-type adhesive composition, Y-type adhesive composition, XY-type adhesive composition, etc. Type X adhesive composition: An energy-ray curable adhesive composition containing a non-energy-ray curable adhesive resin (hereinafter also referred to as "adhesive resin I") and an energy-ray curable compound other than the adhesive resin. Y-type adhesive composition: An energy-ray curable adhesive composition containing an energy-ray curable adhesive resin (hereinafter also referred to as "adhesive resin II") in which an unsaturated group is introduced into the side chain of a non-energy-ray curable adhesive resin, and which does not contain any energy-ray curable compounds other than the adhesive resin. XY-type adhesive composition: An energy-ray curable adhesive composition containing the above-mentioned energy-ray curable adhesive resin II and an energy-ray curable compound other than the adhesive resin. Among these, energy-ray curable adhesives are preferably XY-type adhesive compositions. By using an XY-type adhesive composition, it is possible to have sufficient tackiness before curing while significantly reducing the peeling force from the workpiece after curing. 【0092】 The adhesive forming the adhesive layer may be a layer formed from a non-energy-ray-curable adhesive that does not harden when irradiated with energy rays. Examples of non-energy ray curable adhesives include those containing adhesive resin I but not adhesive resin II or energy ray curable compounds. 【0093】 Next, we will explain in more detail each component that makes up the adhesive layer. In the following description, "adhesive resin" is used as a term referring to either or both of adhesive resin I and adhesive resin II. Furthermore, in the following description, when simply referred to as "adhesive composition," the concept includes X-type adhesive composition, Y-type adhesive composition, XY-type adhesive composition, and other adhesive compositions. 【0094】 Examples of adhesive resins include acrylic resins, urethane resins, rubber resins, and silicone resins. Among these, acrylic resins are preferred. 【0095】 (Acrylic resin) The acrylic resin preferably contains constituent units derived from alkyl (meth)acrylate. Examples of alkyl (meth)acrylates include alkyl (meth)acrylates in which the alkyl group has 1 to 20 carbon atoms. The alkyl group in the alkyl (meth)acrylate may be linear or branched. 【0096】 From the viewpoint of further improving the adhesive strength of the adhesive layer, it is preferable that the acrylic resin contains constituent units derived from alkyl (meth)acrylates in which the alkyl group has 4 or more carbon atoms. The constituent units derived from alkyl (meth)acrylates, in which the alkyl group has 4 or more carbon atoms, contained in the acrylic resin may be one type alone or two or more types. The alkyl(meth)acrylate having four or more carbon atoms in the alkyl group preferably has 4 to 12 carbon atoms, more preferably 4 to 8 carbon atoms, and even more preferably 4 to 6 carbon atoms. Examples of alkyl (meth)acrylates having four or more carbon atoms in the alkyl group include butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. Among these, butyl (meth)acrylate is preferred, and butyl acrylate is more preferred. When the acrylic resin contains constituent units derived from alkyl (meth)acrylate having four or more carbon atoms in the alkyl group, the content thereof is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, and even more preferably 45 to 60% by mass, in the acrylic resin, from the viewpoint of further improving the adhesive strength of the adhesive layer. 【0097】 From the viewpoint of improving the storage modulus G' and adhesive properties of the adhesive layer, it is preferable that the acrylic resin contains both structural units derived from alkyl (meth)acrylates having 4 or more carbon atoms in the alkyl group, and structural units derived from alkyl (meth)acrylates having 1 to 3 carbon atoms in the alkyl group. The constituent units derived from alkyl (meth)acrylates containing alkyl groups with 1 to 3 carbon atoms in the acrylic resin may be one type alone or two or more types. Examples of alkyl(meth)acrylates having 1 to 3 carbon atoms in the alkyl group include methyl(meth)acrylate, ethyl(meth)acrylate, isopropyl(meth)acrylate, and n-propyl(meth)acrylate. Among these, methyl(meth)acrylate and ethyl(meth)acrylate are preferred, methyl(meth)acrylate is more preferred, and methyl methacrylate is even more preferred. When the acrylic resin contains constituent units derived from alkyl (meth)acrylates having 1 to 3 carbon atoms in the alkyl group, the content of these units is preferably 1 to 35% by mass, more preferably 5 to 30% by mass, and even more preferably 15 to 25% by mass, in the acrylic resin. 【0098】 The acrylic resin preferably further contains constituent units derived from functional group-containing monomers. By containing structural units derived from functional group-containing monomers in acrylic resins, it is possible to introduce functional groups that act as crosslinking starting points that react with crosslinking agents, or functional groups that react with unsaturated group-containing compounds to introduce unsaturated groups into the side chains of the acrylic resin. The constituent units derived from functional group-containing monomers contained in the acrylic resin may be one type alone or two or more types. 【0099】 Examples of functional group-containing monomers include hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, and epoxy group-containing monomers. Among these, hydroxyl group-containing monomers and carboxyl group-containing monomers are preferred, and hydroxyl group-containing monomers are more preferred. Examples of hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates such as 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; unsaturated alcohols such as vinyl alcohol and allyl alcohol; and the like. Examples of monomers containing a carboxyl group include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, and citraconic acid, and their anhydrides; and 2-carboxyethyl methacrylate. 【0100】 When an acrylic resin contains constituent units derived from functional group-containing monomers, the content is not particularly limited, but is preferably 5 to 45% by mass, more preferably 15 to 40% by mass, and even more preferably 25 to 35% by mass in the acrylic resin. 【0101】 In addition to the above-mentioned structural units, the acrylic resin may also contain structural units derived from other monomers copolymerizable with acrylic monomers. The constituent units derived from other monomers contained in the acrylic resin may be one type alone or two or more types. Other monomers include, for example, styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide. 【0102】 The acrylic resin may also be modified by introducing unsaturated groups that are capable of energy ray polymerization in order to impart energy ray curability. Unsaturated groups can be introduced, for example, by reacting a functional group of an acrylic resin containing a structural unit derived from a functional group-containing monomer with a reactive substituent of a compound having a reactive substituent and an unsaturated group that are reactive with the functional group (hereinafter also referred to as an "unsaturated group-containing compound"). The unsaturated group-containing compound may be used alone or in combination of two or more types. Examples of unsaturated groups found in compounds containing unsaturated groups include (meth)acryloyl groups, vinyl groups, and allyl groups. Among these, (meth)acryloyl groups are preferred. Examples of reactive substituents found in unsaturated group-containing compounds include isocyanate groups and glycidyl groups. Examples of compounds containing unsaturated groups include (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, and glycidyl (meth)acrylate. 【0103】 When an acrylic resin containing structural units derived from functional group-containing monomers is reacted with an unsaturated group-containing compound, the ratio of functional groups that react with the unsaturated group-containing compound to the total number of functional groups in the acrylic resin is not particularly limited, but is preferably 60 to 98 mol%, more preferably 70 to 95 mol%, and even more preferably 80 to 93 mol%. When the ratio of functional groups that react with the unsaturated group-containing compound is within the above range, sufficient energy ray curability can be imparted to the acrylic resin, and the functional groups that did not react with the unsaturated group-containing compound can be reacted with the crosslinking agent to crosslink the acrylic resin. 【0104】 The mass-average molecular weight (Mw) of the acrylic resin is not particularly limited, but is preferably 300,000 to 1,500,000, more preferably 350,000 to 1,000,000, and even more preferably 400,000 to 600,000. When the mass-average molecular weight (Mw) of the acrylic resin is within the above range, the adhesive strength and cohesive strength of the adhesive layer tend to be better. 【0105】 (Energy ray curable compound) As the energy-ray curable compound contained in the X-type or XY-type adhesive composition, monomers or oligomers having an unsaturated group in the molecule and capable of being cured by energy-ray irradiation are preferred. Examples of energy-ray curable compounds include polyvalent (meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate; and oligomers such as urethane(meth)acrylate, polyester(meth)acrylate, polyether(meth)acrylate, and epoxy(meth)acrylate. Among these, urethane(meth)acrylate oligomers are preferred from the viewpoint of having a relatively high molecular weight and not easily reducing the elastic modulus of the adhesive layer. 【0106】 The molecular weight of the energy-ray-curable compound is not particularly limited, but is preferably 100 to 12,000, more preferably 200 to 10,000, even more preferably 400 to 8,000, and even more preferably 600 to 6,000. When the energy-ray-curable compound is an oligomer, the above molecular weight refers to the mass-average molecular weight (Mw). 【0107】 The content of the energy ray curable compound in the X-type adhesive composition is not particularly limited, but is preferably 40 to 200 parts by mass, more preferably 50 to 150 parts by mass, and even more preferably 60 to 90 parts by mass, per 100 parts by mass of adhesive resin. When the content of the energy-curable compound in the X-type adhesive composition is within the above range, there is a tendency for a good balance between the adhesive strength before energy irradiation and the peelability after energy irradiation. 【0108】 The content of the energy ray curable compound in the XY-type adhesive composition is not particularly limited, but is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 3 to 15 parts by mass, per 100 parts by mass of adhesive resin. When the content of the energy-ray-curable compound in the XY-type adhesive composition is within the above range, a good balance between the adhesive strength before energy irradiation and the peelability after energy irradiation tends to be achieved. Furthermore, because the adhesive resin in the XY-type adhesive composition is energy-ray-curable, even with a low content of the energy-ray-curable compound, the peelability after energy irradiation tends to be sufficiently reduced. 【0109】 (Crosslinking agent) The adhesive composition preferably further contains a crosslinking agent. A crosslinking agent, for example, crosslinks adhesive resins by reacting with functional groups derived from functional group-containing monomers present in the adhesive resin. The crosslinking agent may be used alone or in combination of two or more types. 【0110】 Examples of crosslinking agents include isocyanate-based crosslinking agents such as tolylene diisocyanate, hexamethylene diisocyanate, and their adducts; epoxy-based crosslinking agents such as ethylene glycol glycidyl ether; aziridine-based crosslinking agents such as hexa[1-(2-methyl)-aziridinyl]triphosphatriadin; and chelate-based crosslinking agents such as aluminum chelate. Among these, isocyanate-based crosslinking agents are preferred from the viewpoint of increasing cohesive force and improving adhesion, as well as from the viewpoint of availability. 【0111】 When the adhesive composition contains a crosslinking agent, the amount is not particularly limited, but from the viewpoint of allowing the crosslinking reaction to proceed appropriately, it is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 4 parts by mass per 100 parts by mass of adhesive resin. 【0112】 (Photopolymerization initiator) When the adhesive is an energy-ray curable adhesive, it is preferable that the adhesive composition further contains a photopolymerization initiator. The presence of a photopolymerization initiator in an energy-ray curable adhesive tends to allow the curing reaction to proceed sufficiently even with relatively low-energy energy rays such as ultraviolet light. The photopolymerization initiator may be used alone or in combination of two or more types. 【0113】 Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acyl phosphinoxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. More specifically, examples include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. 【0114】 When the adhesive composition contains a photopolymerization initiator, the amount is not particularly limited, but from the viewpoint of ensuring that the energy ray curing reaction proceeds homogeneously and sufficiently, it is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass per 100 parts by mass of adhesive resin. 【0115】 (Other additives) The adhesive composition may contain other additives as long as they do not impair the effects of the present invention. Examples of other additives include antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, dyes, and the like. 【0116】 (organic solvent) The adhesive composition may be diluted with an organic solvent to form a solution, from the viewpoint of further improving its applicability to substrates, release sheets, etc. Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. Organic solvents may be used individually or in combination of two or more. The organic solvent may be the same organic solvent used during the synthesis of the adhesive resin, or one or more organic solvents other than those used during the synthesis may be added. 【0117】 The storage modulus G' of the adhesive layer at 23°C is not particularly limited, but is preferably 0.05 to 0.5 MPa, more preferably 0.1 to 0.4 MPa, and even more preferably 0.12 to 0.3 MPa. When the storage modulus G' of the adhesive layer at 23°C is within the above range, an adhesive layer with excellent conformability to uneven surfaces can be obtained, even when the workpiece surface is uneven, and the workpiece surface tends to be better protected during processing. Furthermore, if the adhesive layer is formed from an energy-ray curable adhesive, the storage modulus G' of the adhesive layer refers to the storage modulus G' before curing by energy-ray irradiation. The storage modulus G' of the adhesive layer at 23°C can be measured using a viscoelasticity measuring device with a torsional shear method, using a 3mm thick adhesive layer cut into a circular shape with a diameter of 8mm as the test specimen, under the conditions of a frequency of 1Hz and a measurement temperature of 23°C. 【0118】 The thickness of the adhesive layer is not particularly limited, but is preferably 5 to 100 μm, more preferably 10 to 80 μm, and even more preferably 15 to 60 μm. When the thickness of the adhesive layer is greater than or equal to the lower limit mentioned above, excellent adhesion is obtained, and the surface of the workpiece tends to be better protected during processing. Conversely, when the thickness of the adhesive layer is less than or equal to the upper limit mentioned above, the generation of tape scraps when cutting the adhesive sheet is suppressed, and damage to the workpiece tends to be better prevented. 【0119】 <Base material> Examples of substrates include various resin films. Examples of resins constituting the resin films include polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE); polyolefins such as polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymer, and norbornene resin; ethylene copolymers such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, and ethylene-(meth)acrylic acid ester copolymer; polyvinyl chloride such as polyvinyl chloride and vinyl chloride copolymer; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and fully aromatic polyester; polyurethane, polyimide, polyamide, polycarbonate, fluororesin, polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether ketone, and acrylic polymers. The substrate may be a single-layer resin film made of one or more resins selected from these resins, or a laminated film made by laminating two or more of these resin films. Alternatively, it may be a modified film such as a crosslinked film or ionomer film of the above resins. Among these resin films, the base material is preferably one or more selected from polyester film, polyamide film, polyimide film, and biaxially oriented polypropylene film, with polyester film being more preferred and polyethylene terephthalate film being even more preferred. 【0120】 The Young's modulus of the substrate is not particularly limited, but is preferably 1,000 MPa or more, more preferably 1,800 to 30,000 MPa, and even more preferably 2,500 to 6,000 MPa. When the Young's modulus of the base material is above the lower limit, the vibration suppression effect during workpiece processing tends to improve. Conversely, when the Young's modulus of the base material is below the upper limit, the workability when attaching it to the workpiece and when peeling it off the workpiece tends to improve. The Young's modulus of the substrate can be measured in accordance with JIS K 7127:1999 under conditions of a test speed of 200 mm / min. 【0121】 The thickness of the substrate is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 100 μm, and even more preferably 30 to 70 μm. When the thickness of the base material is greater than or equal to the lower limit mentioned above, sufficient strength for functioning as a support for the adhesive sheet tends to be obtained. Conversely, when the thickness of the base material is less than or equal to the upper limit mentioned above, moderate flexibility is obtained, and handling tends to improve. Note that "base material thickness" refers to the total thickness of the base material. If the base material consists of multiple layers, it refers to the total thickness of all the layers that make up the base material. 【0122】 The base material may contain plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, catalysts, etc., to the extent that it does not impair the effects of the present invention. The substrate may be transparent or opaque, and may be colored or vapor-deposited as desired. The substrate may have surface treatment, such as corona treatment, applied to at least one surface, from the viewpoint of improving adhesion with other layers, or it may have a coating layer provided for the purpose of improving adhesion. 【0123】 <Release sheet> The adhesive sheet of this embodiment may have a release sheet attached to at least one of the surfaces of the adhesive layer and the surface of the surface coating layer. The release sheet protects the surface of the adhesive sheet by being peelably attached to the surface of the adhesive sheet before use, and is peeled off and removed when the adhesive sheet is used. The release sheet may be a release sheet that has been treated to peel on one side, or a release sheet that has been treated to peel on both sides. As for the release sheet, a release sheet in which a release agent is applied to a release sheet substrate is preferred. A resin film is preferred as the substrate for the release sheet, and examples of such resin films include polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film; polyolefin films such as polypropylene film and polyethylene film; and the like. Examples of release agents include rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins; and long-chain alkyl resins, alkyd resins, and fluororesins. The thickness of the release sheet is not particularly limited, but is preferably 5 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 50 μm. 【0124】 <Total thickness of adhesive sheet> The total thickness of the adhesive sheet in this embodiment is not particularly limited, but is preferably 30 to 300 μm, more preferably 40 to 220 μm, and even more preferably 45 to 160 μm. When the total thickness of the adhesive sheet is above the lower limit, the adhesive performance of the adhesive layer and the shock absorption performance of the buffer layer are appropriately maintained, and the adhesive sheet tends to fully perform its function as an adhesive sheet for semiconductor processing. Conversely, when the total thickness of the adhesive sheet is below the upper limit, the peeling force required when peeling the workpiece from the adhesive sheet tends to be reduced. In this embodiment, "total thickness of the adhesive sheet" refers to the thickness from the surface of the surface coating layer to the surface of the adhesive layer of the adhesive sheet, and if a release sheet is provided, the thickness of the release sheet is not included in the total thickness. 【0125】 <Method for manufacturing adhesive sheets> There are no particular limitations on the method for manufacturing the adhesive sheet of this embodiment, and it can be manufactured by known methods. The adhesive sheet of this embodiment can be manufactured, for example, by a method comprising the steps of forming an adhesive layer on one side of a substrate (hereinafter also referred to as the "adhesive layer formation step"), forming a buffer layer on the other side of the substrate (hereinafter also referred to as the "buffer layer formation step"), and forming a surface coating layer on the side of the buffer layer opposite to the substrate (hereinafter also referred to as the "surface coating layer formation step"). The order of these steps is not particularly limited, and they may be performed simultaneously if they can be performed at the same time. 【0126】 Methods for forming an adhesive layer, a buffer layer, or a surface coating layer include, for example, applying an adhesive composition, a buffer layer forming composition, or a surface coating layer forming composition to a predetermined position by a known method, and then, if necessary, performing energy ray irradiation, heat drying, or the like. 【0127】 Methods for applying adhesive compositions, buffer layer-forming compositions, or surface coating layer-forming compositions include, for example, spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating. 【0128】 The adhesive layer formation step may be, for example, a method of bonding an adhesive layer formed on a release sheet to the surface of a substrate, or a method of forming an adhesive layer by directly applying an adhesive composition to the surface of a substrate. In the buffer layer formation process, the buffer layer forming composition may be applied to a release sheet or applied directly to the surface of the substrate. When the buffer layer forming composition is applied to a release sheet, the layer formed from the buffer layer forming composition on the release sheet (hereinafter also referred to as the "buffer layer forming composition layer") is then attached to the surface of the substrate. The buffer layer forming composition layer on the release sheet may be the buffer layer itself, or, if the buffer layer forming composition is curable, it may be an uncured or semi-cured product of the curable buffer layer forming composition. When an uncured or semi-cured product of the buffer layer forming composition is formed on the substrate, the buffer layer forming composition is then subjected to a process to fully cure it. In the surface coating layer formation process, the surface coating layer formation composition may be applied to a release sheet or applied directly to the surface of the buffer layer. When the surface coating layer formation composition is applied to a release sheet, the layer formed from the surface coating layer formation composition on the release sheet (hereinafter also referred to as the "surface coating layer formation composition layer") is then attached to the surface of the buffer layer. The surface coating layer formation composition layer on the release sheet may be the surface coating layer itself, or, if the surface coating layer formation composition is curable, it may be an uncured or semi-cured product of the curable surface coating layer formation composition. When an uncured or semi-cured product of the surface coating layer formation composition is formed on the buffer layer, the surface coating layer formation composition is then subjected to a process to fully cure it. Alternatively, the buffer layer formation process and the surface coating layer formation process may involve first providing the surface coating layer and the buffer layer on the release sheet in that order, and then bonding the buffer layer to the surface of the substrate. 【0129】 When the buffer layer forming composition contains an energy ray polymerizable compound, the buffer layer forming step preferably includes a step of irradiating the buffer layer forming composition with energy rays. If the buffer layer forming composition contains an energy ray polymerizable compound, the curing treatment by energy ray irradiation may be performed in a single step or in multiple steps. When performing the curing treatment by energy ray irradiation in a single step, a coating film of the buffer layer forming composition may be formed on the substrate, and then the buffer layer forming composition may be completely cured by energy ray irradiation. Alternatively, the buffer layer forming composition may be completely cured on a release sheet, and then it may be bonded to the substrate. When the surface coating layer forming composition contains an energy ray polymerizable compound, the surface coating layer forming step preferably includes a step of irradiating the surface coating layer forming composition with energy rays. The timing of irradiating the surface coating layer forming composition with energy rays is not particularly limited and may be before or after laminating the surface coating layer forming composition onto the buffer layer or buffer layer forming composition layer. When curing the buffer layer forming composition in multiple steps, after forming a coating film of the buffer layer forming composition on the release sheet, the buffer layer forming composition may be partially cured on the release sheet without being completely cured, then bonded to a surface coating layer forming composition layer provided on the release sheet, and then completely cured by irradiating with energy rays again. If the surface coating layer forming composition contains an energy ray polymerizable compound, the surface coating layer forming composition may be cured simultaneously with the energy ray irradiation required to completely cure the buffer layer forming composition. In addition, ultraviolet light is preferred as the energy ray used for curing the buffer layer-forming composition and the surface coating layer-forming composition. When curing the buffer layer forming composition and the surface coating layer forming composition by irradiating them with energy rays, the buffer layer forming composition and the surface coating layer forming composition may be exposed to the outside, but it is preferable to irradiate them with energy rays when both sides are covered with materials such as release sheets and substrates and are not exposed to the outside. 【0130】 <Uses of adhesive sheets> Examples of workpiece processing performed with the adhesive sheet of this embodiment attached include backgrinding, where the adhesive sheet is attached to one side of a semiconductor device and the other side is ground; dicing, where the adhesive sheet is attached to one side of the semiconductor device and the semiconductor device is divided into individual pieces; semiconductor device transport; and semiconductor chip pickup. Among these, the adhesive sheet of this embodiment is particularly suitable for backgrinding, and is especially suitable for backgrinding, where the adhesive sheet of this embodiment is attached to the circuit formation surface of the semiconductor wafer and the back surface of the semiconductor wafer is ground. In particular, the adhesive sheet of this embodiment has the effect of suppressing the occurrence of cracks when thinning semiconductor wafers, and is therefore suitable for processes such as pre-dicing and stealth pre-dicing. 【0131】 [Manufacturing method for semiconductor devices] The method for manufacturing a semiconductor device according to this embodiment is: The semiconductor processing adhesive sheet of this embodiment is attached to the surface of a semiconductor wafer with the adhesive layer as the attachment surface, The process involves grinding the back surface of the semiconductor wafer while the surface coating layer side of the semiconductor processing adhesive sheet attached to the semiconductor wafer is fixed by a support device, This is a method for manufacturing a semiconductor device, which includes [a specific component]. 【0132】 Furthermore, the method for manufacturing the semiconductor device of this embodiment is A division line formation step, which is a step of forming grooves on the surface of a semiconductor wafer, or a step of forming a modified region inside the semiconductor wafer from the surface or back surface of the semiconductor wafer, After step a, or before or after step b, a sheet application step is performed in which the semiconductor processing adhesive sheet of this embodiment is applied to the surface of the semiconductor wafer with the adhesive layer as the application surface. A grinding and fragmentation step is performed in which, with the surface coating layer side of the semiconductor processing adhesive sheet attached to the semiconductor wafer fixed by a support device, the back surface of the semiconductor wafer is ground to fragment it into a plurality of semiconductor chips starting from the groove or the modified region. It is preferable that the method for manufacturing a semiconductor device includes the following. Furthermore, the semiconductor device manufacturing method of this embodiment may include a peeling step, after the grinding and individualization steps, in which the semiconductor processing adhesive sheet of this embodiment is peeled off from the plurality of semiconductor chips. Furthermore, the method for manufacturing a semiconductor device having step a above corresponds to a pre-dicing method, and the method for manufacturing a semiconductor device having step b above corresponds to a stealth pre-dicing method. 【0133】 Examples of semiconductor wafers used in the manufacturing method of this embodiment include silicon wafers, gallium arsenide wafers, gallium nitride wafers, silicon carbide wafers, glass wafers, and sapphire wafers. Among these, silicon wafers are preferred. Circuits such as wiring, capacitors, diodes, and transistors are typically formed on the surface of semiconductor wafers. These circuits can be formed by conventionally known methods, such as etching and lift-off methods. The thickness of a semiconductor wafer before grinding is not particularly limited, but is usually between 500 and 1,000 μm. The following describes in detail each step of the manufacturing method for the semiconductor device according to this embodiment. 【0134】 <Process for forming planned division lines> The division line formation process is a process of forming grooves on the surface of a semiconductor wafer, or a process of forming a modified region inside the semiconductor wafer from the surface or back surface of the semiconductor wafer. 【0135】 Step a is a process of forming grooves on the surface of the semiconductor wafer, and is performed before the adhesive sheet is attached to the surface of the semiconductor wafer. The grooves formed on the surface of the semiconductor wafer in step a are shallower than the thickness of the semiconductor wafer. After step a, the semiconductor wafer is back-ground until it reaches the grooves formed in step a, and is divided into multiple semiconductor chips. Therefore, in step a, the grooves are formed along the division lines when the semiconductor wafer is divided and separated into individual semiconductor chips. Groove formation can be performed by dicing using conventionally known wafer dicing equipment, etc. 【0136】 Step b is a step of forming a modified region inside the semiconductor wafer from the surface or back surface of the semiconductor wafer, and may be performed before or after attaching the adhesive sheet to the surface of the semiconductor wafer. In step b, the modified region is formed inside the semiconductor wafer by irradiation with a laser focused on the interior of the semiconductor wafer. This modified region is a brittle part of the semiconductor wafer that is broken down by back grinding, which thins the semiconductor wafer or by the force applied during grinding, and serves as the starting point for fragmentation into semiconductor chips. Therefore, the modified region is formed along the division line when the semiconductor wafer is divided and fragmented into semiconductor chips. Laser irradiation may be performed from either the front or back side of the semiconductor wafer. If step b is performed after the sheet attachment process, the laser may be irradiated onto the semiconductor wafer via the adhesive sheet. 【0137】 <Sheet application process> The sheet application process is a process in which an adhesive sheet is applied to the surface of a semiconductor wafer, with the adhesive layer facing the application surface, after process a, or before or after process b. The method of attaching the adhesive sheet is not particularly limited; for example, conventionally known methods such as using a laminator can be applied. 【0138】 <Grinding and framing process> The grinding and fragmentation process involves grinding the back surface of a semiconductor wafer while the surface coating layer side of an adhesive sheet attached to the semiconductor wafer is fixed by a support device, thereby fragmenting the wafer into multiple semiconductor chips starting from the grooves or modified regions. A semiconductor wafer to which an adhesive sheet has been attached and to which grooves or modified regions have been formed is fixed by a support device on the surface coating layer side of the adhesive sheet. The support device is not particularly limited, but a device that holds the object to be fixed by suction, such as a chuck table, is preferred. 【0139】 Next, the back surface of the fixed semiconductor wafer is ground to separate the semiconductor wafer into multiple semiconductor chips. Backside grinding involves grinding the semiconductor wafer until the grinding surface reaches at least the bottom of the groove, provided that grooves have been formed in the semiconductor wafer by step a. This backside grinding transforms the grooves into cuts that penetrate the wafer, dividing the semiconductor wafer into individual semiconductor chips. On the other hand, if a modified region is formed on the semiconductor wafer by process b, the grinding surface may reach the modified region, but it does not have to reach the modified region strictly. That is, grinding should be done up to a position close to the modified region so that the semiconductor wafer is broken down into individual semiconductor chips, starting from the modified region. For example, after grinding up to a position close to the modified region without breaking the semiconductor wafer into individual chips, a pickup tape may be attached to the semiconductor wafer, and the semiconductor wafer may be broken down into individual chips by stretching the pickup tape. 【0140】 The shape of the individual semiconductor chips may be rectangular, or it may be an elongated shape such as a rectangle. The thickness of the individual semiconductor chips is not particularly limited, but is preferably 5 to 100 μm, more preferably 7 to 70 μm, and even more preferably 10 to 45 μm. The chip size of the individual semiconductor chips is not particularly limited, but is preferably 50 mm 2 Less than, more preferably 30 mm 2 Less than 10 mm, more preferably 10 mm 2 It is less than. 【0141】 <Peeling process> The peeling process is a step in which adhesive sheets are peeled off from multiple semiconductor chips after the grinding and individualization processes. When the adhesive layer of an adhesive sheet is formed from an energy-ray curable adhesive, the adhesive is cured by irradiating it with energy rays to reduce the peeling force of the adhesive layer before the adhesive sheet is peeled off. Furthermore, when peeling off the adhesive sheet, a pickup tape may be used. The pickup tape is, for example, composed of an adhesive sheet having a base material and an adhesive layer provided on one side of the base material. When using pickup tape, first, the pickup tape is attached to the back side of the individual semiconductor wafers, and its position and orientation are adjusted so that it can be picked up. At this time, it is preferable to also attach the ring frame, which is placed on the outer periphery of the semiconductor wafer, to the pickup tape, and fix the outer edge of the pickup tape to the ring frame. Next, the adhesive sheet is peeled off from the multiple semiconductor chips fixed on the pickup tape. Subsequently, multiple semiconductor chips on the pickup tape may be picked up and then fixed onto a substrate or the like to manufacture a semiconductor device. [Examples] 【0142】 The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The methods for measuring and evaluating various physical properties are as follows. 【0143】 [Mass average molecular weight (Mw)] The mass-average molecular weight (Mw) was measured using a gel permeation chromatograph (manufactured by Tosoh Corporation, product name "HLC-8220") under the following conditions and determined on a standard polystyrene basis. (Measurement conditions) • Columns: "TSK guard column HXL-H", "TSK gel GMHXL (x2)", "TSK gel G2000HXL" (all manufactured by Tosoh Corporation) Column temperature: 40°C • Developing solvent: tetrahydrofuran ·Flow rate: 1.0mL / min 【0144】 [Measuring the thickness of adhesive sheets, etc.] The total thickness of the adhesive sheet, the thickness of each layer, and the thickness of the test specimens made from them were measured using a constant-pressure thickness measuring instrument (manufactured by Teclock Co., Ltd., product name "PG-02"). Ten arbitrary points were measured, and the average value was calculated. The total thickness of the adhesive sheet is calculated by measuring the thickness of the adhesive sheet with the release liner and subtracting the thickness of the release liner from that thickness. Furthermore, the thickness of the buffer layer is the value obtained by subtracting the thickness of the base material from the thickness of the base material with the buffer layer attached. Furthermore, the thickness of the surface coating layer is the value obtained by subtracting the thickness of the release sheet from the thickness of the surface coating layer with the release sheet attached. Furthermore, the thickness of the adhesive layer is the total thickness of the adhesive sheet minus the thickness of the surface coating layer, buffer layer, and substrate. 【0145】 [Method for measuring the storage modulus E' of the surface coating layer at 90°C] The surface coating layer-forming compositions prepared in the examples and comparative examples were applied to the release surface of a release sheet (Lintec Corporation, product name "SP-PET381031") using a Meyer bar so that the thickness of the formed surface coating layer would be 35 μm. The sheets were then heated and dried to form a surface coating layer-forming composition layer on the release sheet. For the surface coating layer-forming composition layer, an illuminance of 160 mW / cm² is applied. 2 , irradiation amount 500mJ / cm 2 By irradiating with ultraviolet light under these conditions, the surface coating layer forming composition was cured, and a surface coating layer with a release sheet was prepared. The release sheet was peeled off from the surface coating layer with the release sheet obtained above, and the surface coating layer was cut into test specimens with a width of 4 mm in plan view and a length equal to the distance between the chucks of the measuring device of 30 mm. The storage modulus E' of the surface coating layer at 90°C was measured using the following apparatus and measurement conditions with these test specimens. Measuring device: "LeoVibron DDV-01FP" manufactured by A&D Co., Ltd. Frequency: 1Hz Measurement temperature range: -10 to 120°C Heating rate: 3°C / min 【0146】 [Measurement of haze difference before and after heat treatment] Test specimens were prepared by cutting out rectangular pieces measuring 5 cm x 5 cm in plan view from the adhesive sheets with release liner on both sides prepared in the examples and comparative examples, and by peeling off only the release liner on the surface coating layer side to expose the surface coating layer. Furthermore, metal plates 1 and 2 were prepared, both made of SUS304 stainless steel, with a rectangular shape in plan view, dimensions of 7cm x 15cm in plan view, a thickness of 0.5mm, a weight of 40g, and a surface finished with 600-grit polishing. A cylindrical weight was also prepared, weighing 1kg and with a circular base of 4cm in diameter. Metal plate 1 was placed on a hot plate maintained at a temperature of 90°C with the polished surface facing upward. The test specimen was then placed on the polished surface of metal plate 1, with the surface coating layer facing the polished surface of metal plate 1. Furthermore, metal plate 2, which has a polished surface on the side in contact with the release sheet, and a weight were stacked in this order on the release sheet of the test specimen placed on metal plate 1, and the test specimen was heated at 90°C for 1 minute. Metal plate 1, the test specimen, and metal plate 2 were placed so that their four sides were parallel to each other. Also, metal plate 1, the test specimen, metal plate 2, and the weight were placed so that their respective center points coincided in a plan view. The release sheet on the surface coating layer side of the test specimen after the heat treatment was peeled off to obtain the heat-treated adhesive sheet. The haze value of the adhesive sheet was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH-5000") in accordance with JIS K 7136:2000. In addition, the haze value of the adhesive sheet before heat treatment was measured separately using the same method as described above, and the difference between the haze value after heat treatment and the haze value before heat treatment [haze value after heat treatment - haze value before heat treatment] was calculated. 【0147】 [Evaluation of the amount of grinding debris adhering to the surface coating layer] A test specimen was prepared by cutting an adhesive sheet with release sheets on both sides, manufactured in the examples and comparative examples, into a 5 cm square in plan view, and peeling off the release sheet on the surface coating layer side to expose the surface coating layer. The test specimen was suspended by fixing any one of its four corners and immersed in grinding water containing 2% by mass of silicon wafer grinding debris for 10 minutes. The test specimen was removed from the grinding water and allowed to dry at 23°C for 24 hours while still suspended. The surface coating layer of the test specimen was then visually inspected, and the amount of grinding debris attached was evaluated according to the following criteria. In the following evaluation criteria, "grinding debris attachment area" refers to island-shaped areas of grinding debris attachment formed by the drying of droplets of grinding water that adhered to the surface coating layer. A: There is one area on the surface coating layer where grinding debris is attached, or there is no grinding debris attached to the area that can be identified as a grinding debris attachment site. B: There are 2 to 5 areas on the surface coating layer where grinding debris is attached. C: There are six or more areas on the surface coating layer where grinding debris is attached, but the entire surface coating layer is not covered with grinding debris. D: Grinding debris is adhering to the entire surface coating layer. 【0148】 [Evaluation of transportability] The release sheet on the adhesive layer side of the adhesive sheets prepared in the examples and comparative examples, which had release sheets on both sides, was peeled off, and the exposed adhesive layer was used as the attachment surface to be attached to a silicon mirror wafer (12 inches in diameter, 50 μm thick, dry polished finish) to prepare a silicon mirror wafer with an adhesive sheet (hereinafter also referred to as "wafer with adhesive sheet"). The wafer with the adhesive sheet attached was peeled off the release sheet from the surface coating layer and placed on a heating table with the surface coating layer facing the contact surface, and heated at 80°C for 3 minutes. Then, the suction surface of a transport arm equipped with a suction mechanism was placed on the silicon mirror wafer side of the wafer with the adhesive sheet attached, and a test was conducted to see if the wafer with the adhesive sheet attached could be lifted from the heating table while the wafer with the adhesive sheet attached was suction-adhered to the suction surface, and the transportability was evaluated according to the following criteria. A: The conveyor arm was able to lift the wafer with the adhesive sheet attached from the heating table. B: The wafer with the adhesive sheet stuck to the heating table, and the transport arm was unable to lift the wafer with the adhesive sheet from the heating table. 【0149】 [Preparation of urethane acrylate oligomers used in buffer layers] Manufacturing Example 1 A terminal isocyanate urethane prepolymer obtained by reacting a polyester diol with isophorone diisocyanate was reacted with 2-hydroxyethyl acrylate to obtain a bifunctional urethane acrylate oligomer with a mass-average molecular weight (Mw) of 5,000. 【0150】 [Preparation of energy-curable acrylic resin for use in the adhesive layer] Manufacturing Example 2 An acrylic polymer was obtained by copolymerizing 52 parts by mass of n-butyl acrylate, 20 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate. Next, 2-methacryloyloxyethyl isocyanate was reacted to the acrylic polymer so as to add to 90 mol% of the total hydroxyl groups, thereby obtaining an energy-ray curable acrylic resin with a mass-average molecular weight (Mw) of 500,000. 【0151】 [Manufacturing of adhesive sheets] Examples 1-4, Comparative Examples 1-2 Next, adhesive sheets were manufactured using the method described below. Note that all amounts of each component mentioned in the following explanation refer to the amounts of the active ingredients. 【0152】 (1) Preparation of the base material A polyethylene terephthalate film with a thickness of 50 μm (Young's modulus: 2,500 MPa) was prepared as the base material. 【0153】 (2) Preparation of composition for forming surface coating layer Each component shown in Table 1 was dissolved in toluene to an active ingredient concentration of 10% by mass to form a surface coating layer. 【0154】 (3) Preparation of the Composition for Forming the Buffer Layer 40 parts by mass of the urethane acrylate - based oligomer obtained in Production Example 1, 40 parts by mass of isobornyl acrylate, 20 parts by mass of 2 - hydroxy - 3 - phenoxypropyl acrylate, 2.0 parts by mass of 1 - hydroxycyclohexyl phenyl ketone as a photoinitiator, and 0.2 parts by mass of a phthalocyanine - based pigment were blended to prepare a composition for forming the buffer layer. 【0155】 (4) Preparation of the Adhesive Composition 100 parts by mass of the energy - ray - curable acrylic resin obtained in Production Example 2, 6 parts by mass of polyfunctional urethane acrylate (manufactured by Mitsubishi Chemical Corporation, trade name "Shikou UT - 4332", mass - average molecular weight (Mw) 4,700) as an energy - ray - curable compound, 0.375 parts by mass of an isocyanate - based cross - linking agent (manufactured by Tosoh Corporation, trade name "Coronate L"), and 1 part by mass of bis(2,4,6 - trimethylbenzoyl)phenylphosphine oxide as a photoinitiator were blended and diluted with an organic solvent to prepare an adhesive composition. 【0156】 (5) Production of the Adhesive Sheet On one surface of the substrate shown above, the composition for forming the buffer layer obtained above was applied so that the thickness of the formed buffer layer would be 20 μm, and then the composition for forming the buffer layer was semi - cured by irradiating ultraviolet rays under the conditions of an illuminance of 30 mW / cm 2 and an irradiation dose of 60 mJ / cm 2 to form a layer in which the composition for forming the buffer layer was semi - cured on one surface of the substrate. Also, on the release - treated surface of a release sheet (manufactured by Lintec Corporation, trade name "SP - PET381031"), the composition for forming the surface coat layer obtained above was applied with a Meyer bar so that the thickness of the formed surface coat layer would be 2 μm, and then it was dried by heating to form a layer of the composition for forming the surface coat layer on the release sheet. After laminating the layer of the composition for forming the surface coat layer on the release sheet and the layer in which the composition for forming the buffer layer on one surface of the substrate was semi - cured, under the conditions of an illuminance of 160 mW / cm 2 and an irradiation dose of 500 mJ / cm 2By irradiating with ultraviolet light under these conditions, the buffer layer-forming composition and the surface coating layer-forming composition were cured, and a laminate having the buffer layer and the surface coating layer in that order was obtained on one surface of the substrate. Furthermore, the adhesive composition obtained above was applied to the release surface of a release sheet (Lintec Corporation, product name "SP-PET381031") so that the thickness after drying was 20 μm, and then heated and dried to produce a release sheet with an adhesive layer. By attaching the adhesive layer of the release sheet with the adhesive layer to the side of the substrate of the laminate that does not have a buffer layer, an adhesive sheet is obtained having release sheets on both sides and having a surface coating layer, a buffer layer, a substrate, and an adhesive layer in this order. 【0157】 Table 1 shows the evaluation results of the adhesive sheets obtained in each example and comparative example. 【0158】 [Table 1] 【0159】 • S2104: Hydrogenated styrene-based thermoplastic elastomer (SEPS), styrene content: 65% by mass, manufactured by Kuraray Co., Ltd., product name "Septon (registered trademark) 2104" • H1043: Hydrogenated styrene-based thermoplastic elastomer (SEBS), styrene content: 67% by mass, manufactured by Asahi Kasei Corporation, product name "ToughTec (registered trademark) H1043" • S2006: Hydrogenated styrene-based thermoplastic elastomer (SEPS), styrene content: 35% by mass, manufactured by Kuraray Co., Ltd., product name "Septon (registered trademark) 2006" • PMA-L: Propylene-butene-maleic anhydride copolymer, maleic anhydride modification rate: 1.5% by mass, mass-average molecular weight (Mw): 75,000, manufactured by Toyobo Co., Ltd., product name "Toyo Tack (registered trademark) PMA-L" 【0160】 • Energy-ray polymerizable polyfunctional compound: A mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate, manufactured by Nippon Kayaku Co., Ltd., trade name "KAYARAD DPHA" • Photopolymerization initiator: 2-hydroxy-2-methyl-1-phenylpropanone, manufactured by IGM Resins BV, trade name "Omnirad1173" • Hydrophobic silica: Hydrophobized amorphous silica precipitated by precipitation. 【0161】 Table 1 shows that the adhesive sheets of Examples 1-4, which had a haze difference of 2.0% or less before and after heat treatment, exhibited excellent transportability after workpiece processing. On the other hand, the adhesive sheets of Comparative Examples 1 and 2, which had a haze difference exceeding 2.0% before and after heat treatment, showed poor transportability after workpiece processing.

Claims

[Claim 1] The surface coating layer, buffer layer, substrate, and adhesive layer are provided in this order. An adhesive sheet for semiconductor processing in which the difference between the haze value after heat treatment and the haze value before heat treatment [haze value after heat treatment - haze value before heat treatment] is 0.9% or less. (Conditions for heat treatment) A metal plate 1 having a polished surface is placed on a hot plate maintained at a temperature of 90°C with the polished surface facing upwards. A semiconductor processing adhesive sheet, which has a release sheet attached to the adhesive layer, is placed on the polished surface of the metal plate 1 with the surface coating layer facing the polished surface. A metal plate 2 having a polished surface on the side in contact with the release sheet, and a weight are stacked in this order on the release sheet of the semiconductor processing adhesive sheet, and the semiconductor processing adhesive sheet is heated at 90°C for 1 minute. The semiconductor processing adhesive sheet used in the heat treatment has a rectangular shape in plan view and dimensions of 5 cm x 5 cm in plan view. Both metal plate 1 and metal plate 2 are made of SUS304, have a rectangular shape in plan view, dimensions of 7 cm x 15 cm in plan view, a thickness of 0.5 mm, and a weight of 40 g. The polished surface has a surface finish achieved by 600 grit polishing. The weight has a cylindrical shape with a weight of 1 kg and a circular base with a diameter of 4 cm. The metal plate 1, the adhesive sheet for semiconductor processing, and the metal plate 2 are placed so that their four sides are parallel to each other, and the metal plate 1, the adhesive sheet for semiconductor processing, the metal plate 2, and the weight are placed so that their respective center points coincide in a plan view. [Claim 2] The semiconductor processing adhesive sheet according to claim 1, wherein the surface coating layer is an organic layer containing a resin component. [Claim 3] The adhesive sheet for semiconductor processing according to claim 2, wherein the resin component is a thermoplastic resin. [Claim 4] The semiconductor processing adhesive sheet according to claim 3, wherein the thermoplastic resin is a polymer of a compound having one or more ethylenically unsaturated bonds. [Claim 5] The semiconductor processing adhesive sheet according to any one of claims 1 to 4, wherein the thickness of the surface coating layer is 0.05 to 10 μm. [Claim 6] The semiconductor processing adhesive sheet according to any one of claims 1 to 4, wherein the buffer layer is a layer formed from a buffer layer forming composition containing urethane (meth)acrylate. [Claim 7] A semiconductor processing adhesive sheet according to any one of claims 1 to 4, used for backside grinding of semiconductor wafers. [Claim 8] A step of attaching a semiconductor processing adhesive sheet according to any one of claims 1 to 4 to the surface of a semiconductor wafer with the adhesive layer as the attachment surface, The process involves grinding the back surface of the semiconductor wafer while the surface coating layer side of the semiconductor processing adhesive sheet attached to the semiconductor wafer is fixed by a support device, A method for manufacturing a semiconductor device, including the method described above. [Claim 9] A division line formation step, which is a step of forming grooves on the surface of a semiconductor wafer, or a step of forming a modified region inside the semiconductor wafer from the surface or back surface of the semiconductor wafer, A sheet application step is performed, after step a, or before or after step b, by applying the semiconductor processing adhesive sheet according to any one of claims 1 to 4 to the surface of the semiconductor wafer with the adhesive layer as the application surface. A grinding and fragmentation step is performed in which, with the surface coating layer side of the semiconductor processing adhesive sheet attached to the semiconductor wafer fixed by a support device, the back surface of the semiconductor wafer is ground to fragment it into a plurality of semiconductor chips starting from the groove or the modified region. A method for manufacturing a semiconductor device, including the method described above.

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