Manufacturing method of adhesive wafers and semiconductor devices for semiconductor processing

Abstract

The present invention relates to an adhesive sheet for semiconductor processing and a method for manufacturing a semiconductor device using the adhesive sheet for semiconductor processing. The adhesive sheet for semiconductor processing has a surface coating, a buffer layer, a substrate and an adhesive layer in sequence, wherein the aforementioned surface coating has a static friction coefficient of 0.70 or less for SUS304.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an adhesive film for semiconductor processing and a semiconductor device. [Previous Technology]

[0002] With the rapid advancement of the thinning, miniaturization, and multi-functionality of information terminal machines, semiconductor devices mounted on these machines are also required to be thinner and denser. One method for thinning semiconductor devices is to polish the back side of the semiconductor wafer used in the semiconductor device. Back side polishing of the semiconductor wafer is performed by attaching an adhesive sheet (hereinafter also referred to as a "back side polishing sheet") to the surface of the semiconductor wafer, with the sheet protecting the surface of the semiconductor wafer. The back side polishing sheet is peeled off from the surface of the semiconductor wafer after back side polishing.

[0003] In recent years, methods for grinding and monolithic wafer fabrication that suppress damage to semiconductor wafers while simultaneously achieving thinning and miniaturization have been employed, including pre-grinding dicing and stealth pre-grinding dicing. Pre-grinding dicing involves creating grooves of a specific depth on the surface of a semiconductor wafer using a cutting blade or similar tool, and then grinding the semiconductor wafer from the back side to the grooves, thereby monolithicizing the semiconductor wafer. Stealth pre-grinding dicing involves forming a modified region inside the semiconductor wafer by laser irradiation, then grinding the semiconductor wafer from the back side, using the modified region as a dicing starting point to cut and monolithize it into a semiconductor wafer. In these methods, a back-side grinding sheet is used to protect the surface of the semiconductor wafer.

[0004] With the development of such thinning process technologies, various reviews have been conducted regarding the ability of back-side polishing sheets to achieve high yield and thinning of semiconductor wafers. Patent Document 1 discloses an adhesive sheet for protecting the surface of a semiconductor wafer, applicable to pre-grinding dicing or stealth pre-grinding dicing methods. This adhesive sheet is characterized by having a substrate film, an intermediate layer formed of an adhesive on at least one side of the substrate film, and an outermost adhesive layer on the opposite side of the intermediate layer. The intermediate layer is formed of a material hardened by a hardening process after the adhesive sheet is formed. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2015-56446 [Summary of the Invention]

[0006] [The problem the invention aims to solve]

[0007] According to the adhesive sheet for surface protection of semiconductor wafers in Patent Document 1, after the semiconductor wafer is monolithically converted into a wafer, it can suppress the curling displacement caused by the collapse of the original wafer spacing and suppress the contamination caused by the grinding debris of the semiconductor wafer. It can also prevent residual paste on the wafer when peeling off the surface protective tape.

[0008] Furthermore, during back-side grinding, the back-side grinding sheet attached to the semiconductor wafer is fixed on the side opposite to the side attached to the semiconductor wafer (hereinafter also referred to as the "back side") by a support device such as a jig stage. Then, the semiconductor wafer, which is fixed on the stage of the support device by the back-side grinding sheet, is ground on the back side while cooling water is supplied to the grinding surface to remove the heat and grinding debris generated during grinding.

[0009] During back-side grinding, if there are grinding debris between the back-side grinding wafer and the stage of the support device, cracks may occur on the semiconductor wafer or semiconductor chip, starting from the area where the grinding debris is present, due to the impact when fixing the semiconductor wafer to the stage, the pressure and vibration during back-side grinding, etc. Since the grinding debris adheres to the back side of the back-side grinding wafer in a state containing cooling water, it is necessary to reduce the amount of grinding debris adhering to the back side of the back-side grinding wafer in order to suppress cracking.

[0010] Furthermore, during the polishing of semiconductor wafers, although cooling water is provided to remove the frictional heat generated during polishing, it is difficult to completely remove the frictional heat, causing the temperature of the back polishing wafer on the semiconductor wafer to rise to some extent. That is, during the polishing of semiconductor wafers, the back polishing wafer is heated for a certain period of time while under pressure against the support device such as the fixture stage, resulting in excessive adhesion between the back polishing wafer and the support device. After polishing, the semiconductor wafer must be lifted from the support device by a transfer arm or the like and transported to the next step. If the back polishing wafer is excessively adhered to the support device, lifting may fail, and transport may be impossible. This problem tends to be particularly pronounced when using a back polishing wafer with reduced back polishing debris adhesion.

[0011] The adhesive sheet for protecting the surface of a semiconductor wafer in Patent Document 1 has not yet adequately met the requirements of reducing the amount of polishing debris adhering to the back side of the back polishing sheet and improving transportability.

[0012] This invention was made in view of the above circumstances, and its object is to provide an adhesive wafer for semiconductor processing with reduced grinding debris adhesion and excellent transportability, and a method for manufacturing a semiconductor device using the adhesive wafer for semiconductor processing. [Means for solving the problem]

[0013] As a result of active review, the inventors discovered that the above-mentioned problems can be solved by using an adhesive sheet for semiconductor processing that sequentially has a surface coating, a buffer layer, a substrate and an adhesive layer having a static friction coefficient within a specific range, and thus the following invention was completed.

[0014] That is, the present invention relates to the following [1] to

[11] . [1] An adhesive sheet for semiconductor processing, which sequentially comprises a surface coating, a buffer layer, a substrate and an adhesive layer, wherein the static friction coefficient of the aforementioned surface coating relative to SUS304 is 0.70 or less. [2] The adhesive sheet for semiconductor processing as described in [1], wherein the aforementioned surface coating is a layer formed by a surface coating forming composition containing a resin component and a lubrication improving component. [3] The adhesive sheet for semiconductor processing as described in [2], wherein the aforementioned resin component has a heteroatom content of 7% by mass or less. [4] The adhesive sheet for semiconductor processing as described in [2] or [3], wherein the content of the aforementioned resin component in the aforementioned surface coating forming composition is 50 to 99% by mass relative to the total amount (100% by mass) of the effective components in the aforementioned surface coating forming composition. [5] The adhesive sheet for semiconductor processing of any one of [2] to [4] above, wherein the content of the aforementioned slip improvement component is 30% by mass or more of heteroatoms. [6] The adhesive sheet for semiconductor processing of any one of [2] to [5] above, wherein the content of the aforementioned slip improvement component in the aforementioned surface coating forming composition is 0.1 to 30% by mass relative to the total amount (100% by mass) of the effective components in the aforementioned surface coating forming composition. [7] The adhesive sheet for semiconductor processing of any one of [1] to [6] above, wherein the thickness of the aforementioned surface coating is 0.05 to 10 μm. [8] The adhesive sheet for semiconductor processing of any one of [1] to [7] above, wherein the aforementioned buffer layer is formed by a buffer layer forming composition containing urethane (meth)acrylate. [9] The adhesive sheet for semiconductor processing of any one of [1] to [8] above, which is used for back-side grinding of semiconductor wafers.

[10] A method for manufacturing a semiconductor device includes the following steps: attaching a semiconductor processing adhesive sheet of any one of [1] to [9] to the surface of a semiconductor wafer using the aforementioned adhesive layer as the attachment surface; and grinding the back side of the semiconductor wafer while the aforementioned surface coating side of the semiconductor processing adhesive sheet attached to the aforementioned semiconductor wafer is fixed by a support device.

[11] The semiconductor device manufacturing method of

[10] above includes the following steps: a step of forming a predetermined dividing line: step a of forming a groove on the surface of a semiconductor wafer, or step b of forming a modified region inside the semiconductor wafer from the surface or back side of the semiconductor wafer; a wafer attaching step: after step a above, or before or after step b above, using the aforementioned adhesive layer as the attaching surface, attaching a semiconductor processing adhesive wafer as described in any one of [1] to [9] above to the surface of the semiconductor wafer; a grinding and monolithization step: with the surface coating side of the semiconductor processing adhesive wafer attached to the semiconductor wafer fixed by a support device, grinding the back side of the semiconductor wafer, and using the aforementioned groove or modified region as the starting point, monolithizing the semiconductor wafer into a plurality of semiconductor wafers. [Effects of the Invention].

[0015] According to the present invention, a semiconductor processing adhesive film with reduced grinding debris adhesion and excellent transportability can be provided, and a method for manufacturing a semiconductor device using the semiconductor processing adhesive film can be provided.

Implementation Method

[0016] In this specification, the lower limit and upper limit of the preferred numerical range can be combined independently. For example, based on the statement "preferably 10~90, more preferably 30~60", the "preferable lower limit (10)" and the "more preferably upper limit (60)" can be combined to become "10~60".

[0017] In this specification, for example, "(meth)acrylic acid" means both "acrylic acid" and "methacrylic acid", and other similar terms are the same.

[0018] In this specification, "energy line" refers to something that possesses energy quanta in electromagnetic waves or charged particle beams, such as ultraviolet light, radiation, and electron beams. Ultraviolet light can be irradiated using, for example, electrodeless lamps, high-pressure mercury lamps, metal halide lamps, UV-LEDs, etc. Electron beams can be irradiated by electron beam accelerators, etc. In this specification, "energy line aggregation property" means the property of aggregation by irradiation of energy lines. "Energy line hardening property" means the property of hardening by irradiation of energy lines, and "non-energy line hardening property" means the property of not possessing energy line hardening property.

[0019] In this specification, the “surface” of a semiconductor wafer refers to the side on which a circuit is formed, and the “back side” refers to the side on which no circuit is formed.

[0020] The mechanism of action described in this specification is speculative and is not limited to the mechanism by which the semiconductor processing adhesive film of the present invention achieves its effect.

[0021] [Adhesive Sheet for Semiconductor Processing] The adhesive sheet for semiconductor processing (hereinafter also referred to as "adhesive sheet") of this embodiment sequentially comprises a surface coating, a buffer layer, a substrate, and an adhesive layer, wherein the static friction coefficient of the aforementioned surface coating relative to SUS304 is 0.70 or less. The adhesive sheet of this embodiment is used to adhere to the surface of a semiconductor device of a workpiece, protecting the surface while performing specific processing on the semiconductor device. After performing the predetermined processing on the workpiece, the adhesive sheet of this embodiment is peeled off from the semiconductor device. In this embodiment, the term "semiconductor device" refers to a general device that can perform functions by utilizing the characteristics of semiconductors, such as semiconductor wafers, semiconductor chips, electronic components containing semiconductor chips, and electronic machines containing electronic components. Among these, the adhesive sheet of this embodiment is suitable for the processing of semiconductor wafers.

[0022] The adhesive sheet of this embodiment may have layers other than a surface coating, a buffer layer, a substrate, and an adhesive layer, or it may not have any of these layers. Examples of layers other than the substrate and the adhesive layer include, for example, an intermediate layer disposed between the substrate and the adhesive layer, or a release sheet disposed on the side of the adhesive layer opposite to the substrate. Hereinafter, the components constituting the adhesive sheet of this embodiment will be described in sequence.

[0023] <Surface Coating> The surface coating is a layer disposed on the side opposite to the substrate of the buffer layer, and is a layer that is fixed by the support device during the processing of the half-body device.

[0024] (Coefficient of Static Friction) The surface coating of the adhesive sheet in this embodiment has a static friction coefficient of 0.70 or less relative to SUS304. By having a surface coating with a static friction coefficient of 0.70 or less relative to SUS304, the adhesive sheet in this embodiment can reduce the amount of grinding debris and has excellent transportability. Although the reason is not yet clear, it is speculated that a surface coating with a static friction coefficient of 0.70 or less is less likely to adhere to water containing grinding debris and can suppress excessive adhesion to support devices, etc. Based on the above viewpoint, the surface coating of the adhesive sheet in this embodiment preferably has a static friction coefficient of 0.60 or less relative to SUS304, and more preferably 0.50 or less. On the other hand, the lower limit of the static friction coefficient of the surface coating of the adhesive sheet in this embodiment relative to SUS304 is not particularly limited, but based on the viewpoint of ease of manufacture, it may be 0.01 or more, 0.10 or more, or 0.20 or more. Furthermore, the static friction coefficient of the surface coating relative to SUS304 is a value determined according to JIS K 7125:1999, specifically, it can be determined by the method described in the examples.

[0025] The surface coating of the adhesive sheet in this embodiment is preferably formed from a surface coating forming composition containing resin components and slip-improving components.

[0026] (Resin Component) As the resin component, it is preferable to be a thermoplastic resin, and more preferably a polyolefin resin, based on the viewpoint of reducing the amount of grinding debris adhering.

[0027] [Polyolefin resin] The composition for forming a surface coating tends to further reduce the amount of abrasive debris adhering to the surface coating of the adhesive sheet of this embodiment by containing a polyolefin resin.

[0028] Polyolefin resins are resins polymerized from monomers containing at least an olefin. Here, "polyolefin resin" in this embodiment refers to a resin formed by the polymerization of all olefins, or a resin formed by copolymerizing an olefin with monomers other than olefins, meaning any resin containing 50% by mass or more of constituent units derived from olefins. Furthermore, "olefin" in this embodiment refers to an unsaturated hydrocarbon having ethylene unsaturated bonds; compounds containing heteroatoms are not included in the "olefin" of this embodiment. Also, in this specification, "heteroatoms" refers to all atoms other than carbon and hydrogen atoms. Furthermore, in the following description, groups containing ethylene unsaturated bonds are sometimes simply referred to as "unsaturated groups." A single polyolefin resin may be used alone, or two or more may be used in combination.

[0029] The content of olefin-derived constituent units in the polyolefin resin is not particularly limited, but it is preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. If the content of olefin-derived constituent units in the polyolefin resin is at or above the above-mentioned lower limit, there is a tendency to further reduce the amount of abrasive debris adhesion. Furthermore, the content of olefin-derived constituent units in the polyolefin resin can be 100% by mass, but for example, in order to include constituent units of monomers other than olefins for the purpose of improving solvent solubility, it can be 99.5% by mass or less, or 99% by mass or less.

[0030] Examples of olefins constituting polyolefin resins include, for example, chain olefins, cyclic olefins, and aromatic vinyl compounds. One type of olefin constituting a polyolefin resin may be used alone, or two or more types may be used in combination.

[0031] Examples of chain olefins include, for example, 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, 5-methyl-1-hexene, and other chain monoolefins; chain non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene; and chain 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. Among these, chain olefins having 2 to 6 carbon atoms are preferred, and ethylene and propylene are more preferred.

[0032] Examples of cyclic olefins include cyclic monoolefins such as cyclobutene, cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, cycloheptene, and cyclooctene; cyclic dienes such as cyclohexadiene, methylcyclohexadiene, cyclooctadiene, methylcyclooctadiene, and phenylcyclooctadiene; and polycyclic olefins such as norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, and tetracyclo[7.4.0.110,13.02,7]tetradecane-2,4,6,11-tetraene. Among these, tetracyclododecene is preferred from the viewpoint of improving solvent solubility and facilitating the formation of a surface coating through coating.

[0033] Examples of aromatic vinyl compounds include, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, etc.

[0034] Examples of monomers other than olefins that can copolymerize with olefins include monomers having oxygen atoms and ethylene unsaturated bonds, monomers having nitrogen atoms and ethylene unsaturated bonds, etc. A single monomer other than an olefin may be used alone, or two or more may be used in combination.

[0035] Monomers having oxygen atoms and vinyl unsaturated bonds include, for example, anhydrides such as maleic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, phenylmaleic anhydride, and diphenylmaleic anhydride; maleic acids such as maleic acid, methylmaleic acid, dimethyl maleate, diethyl maleate, dibutyl maleate, and monomethyl maleate; (meth)acrylic acid and (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cycloalkyl (meth)acrylate with 3 to 20 carbon atoms, benzyl (meth)acrylate, and isobornyl (meth)acrylate; vinyl ester compounds such as vinyl acetate and vinyl propionate; etc. Among these, based on the viewpoint of improving solvent solubility and facilitating the formation of surface coatings by coating, acid anhydrides and vinyl ester compounds are preferred, maleic anhydride and vinyl acetate are more preferred, and maleic anhydride is even more preferred.

[0036] Examples of monomers having a nitrogen atom and an ethylene-like unsaturated bond include, for example, maleimide compounds and their derivatives, nitrile monomers, etc. Examples of maleimide compounds and their derivatives include, for example, maleimide; N-alkyl-substituted maleimides such as N-methylmaleimide and N-ethylmaleimide; N-aryl-substituted maleimides such as N-phenylmaleimide; etc. Examples of nitrile monomers include, for example, propionitrile and methylpropionitrile.

[0037] Among the above constituent units, based on the viewpoint of further reducing the amount of abrasive debris, the polyolefin resin preferably contains constituent units derived from chain olefins having 2 to 6 carbon atoms (hereinafter also referred to as "chain olefin constituent units (A)"), and more preferably contains one or more types selected from the group consisting of constituent units derived from ethylene and constituent units derived from propylene.

[0038] As a polyolefin resin, based on the viewpoint of improving solvent solubility and making it easier to form a surface coating by coating, it is preferable to contain a chain olefin constituent unit (A) and a constituent unit derived from a monomer having an oxygen atom and an ethylene unsaturated bond (hereinafter also referred to as "oxygen-containing constituent unit (B)"), or to contain a chain olefin constituent unit (A) and a constituent unit derived from an aromatic vinyl compound (hereinafter also referred to as "aromatic vinyl compound constituent unit (C)").

[0039] When the polyolefin resin contains chain olefin constituent units (A) and oxygen-containing constituent units (B), the content of chain olefin constituent units (A) in the polyolefin resin (A) is not particularly limited, but is preferably 80-99.5% by mass, more preferably 90-99% by mass, and even more preferably 95-98.8% by mass. When the polyolefin resin contains chain olefin constituent units (A) and oxygen-containing constituent units (B), the content of oxygen-containing constituent units (B) in the polyolefin resin is not particularly limited, but is preferably 0.5-20% by mass, more preferably 1-10% by mass, and even more preferably 1.2-5% by mass. If the content of chain olefin constituent units (A) and oxygen-containing constituent units (B) is within the above range, there is a tendency to obtain good solvent solubility while reducing the amount of grinding debris adhesion.

[0040] Examples of polyolefin resins containing chain-like olefinic units (A) and oxygen-containing units (B) include, for example, ethylene-maleic anhydride copolymers, ethylene-vinyl acetate copolymers, ethylene-(meth)acrylate copolymers, propylene-maleic anhydride copolymers, propylene-vinyl acetate copolymers, and propylene-(meth)acrylate copolymers; ethylene-maleic anhydride-vinyl acetate copolymers, ethylene-maleic anhydride-(meth)acrylate copolymers, ethylene-vinyl acetate-(meth)acrylate copolymers, propylene-maleic anhydride-vinyl acetate copolymers, and propylene-maleic anhydride-vinyl acetate copolymers. Multi-component polymers including vinyl acetate copolymers, propylene-maleic anhydride-(meth)acrylate copolymers, propylene-vinyl acetate-(meth)acrylate copolymers, ethylene-propylene-maleic anhydride copolymers, ethylene-propylene-vinyl acetate copolymers, ethylene-propylene-(meth)acrylate copolymers, ethylene-butene-maleic anhydride copolymers, ethylene-butene-vinyl acetate copolymers, ethylene-butene-(meth)acrylate copolymers, propylene-butene-maleic anhydride copolymers, propylene-butene-vinyl acetate copolymers, and propylene-butene-(meth)acrylate copolymers; etc. Among these, propylene-butene-maleic anhydride copolymers are preferred, based on the viewpoint of further reducing the amount of grinding debris adhering and improving solvent solubility for easier formation of surface coatings through coating.

[0041] When the polyolefin resin contains chain olefin constituent units (A) and aromatic vinyl compound constituent units (C), the content of chain olefin constituent units (A) in the polyolefin resin is not particularly limited, but is preferably 5-60% by mass, more preferably 10-50% by mass, and even more preferably 20-40% by mass. When the polyolefin resin contains chain olefin constituent units (A) and aromatic vinyl compound constituent units (C), the content of aromatic vinyl compound constituent units in the polyolefin resin is not particularly limited, but is preferably 40-95% by mass, more preferably 50-90% by mass, and even more preferably 60-80% by mass. If the content of chain olefin constituent units (A) and aromatic vinyl compound constituent units (C) is within the above range, there is a tendency to obtain good solvent solubility and further reduce the amount of grinding debris adhesion.

[0042] Examples of polyolefin resins containing chain olefin constituent units (A) and aromatic vinyl compound constituent units (C) include, for example, hydrogenated styrene-butadiene-styrene block copolymers and hydrogenated styrene-isoprene-styrene block copolymers. Examples of hydrogenated styrene-butadiene-styrene block copolymers include SEBS, in which the carbon-carbon double bonds in the butadiene block are completely hydrogenated, and SBBS, in which the carbon-carbon double bonds at the 1,2-bond sites in the butadiene block are partially hydrogenated. Among these, SEBS is preferred.

[0043] As a polyolefin resin, it may be any resin other than those described above, as long as it can form a surface coating. Examples of polyolefin resins other than those described above include polyethylene, polypropylene, polybutadiene, ethylene-propylene copolymer, ethylene-butene copolymer, propylene-butene copolymer, etc., which are polyolefin resins composed only of chain olefin constituent units (A); polystyrene, etc., which are polyolefin resins composed only of aromatic vinyl compound constituent units (C); etc.

[0044] The composition for forming the surface coating may contain resins other than polyolefin resins, or may not contain them. The content of polyolefin resin in the resin composition is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and even more preferably 98 to 100% by mass, based on the viewpoints of further reducing the amount of grinding debris adhering and further improving transportability.

[0045] [Heteroatom Content of Resin Components] The heteroatom content in the resin components is not particularly limited, but it is preferably 7% by mass or less, more preferably 0.2 to 4% by mass, and even more preferably 0.5 to 1% by mass. If the heteroatom content in the resin components is below the above-mentioned upper limit, there is a tendency to further reduce the amount of grinding debris adhering. Furthermore, if the heteroatom content in the resin components is above the above-mentioned lower limit, there is a tendency to increase the solvent solubility of the resin components and make it easier to form a surface coating using the resin components.

[0046] [Solvent Solubility of Resin Components] From the viewpoint of easily forming a surface coating by coating, the resin component preferably has solubility in organic solvents. Specifically, at 23°C, the resin component preferably dissolves at least 1% by mass for toluene, more preferably at least 5% by mass, and even more preferably at least 8% by mass.

[0047] [Content of Resin Component] The content of resin component in the composition for forming a surface coating is preferably 50-99% by mass, more preferably 60-90% by mass, and even more preferably 70-85% by mass, relative to the total amount of effective components (100% by mass) of the composition for forming a surface coating. If the content of resin component is above or above the lower limit mentioned above, there is a tendency to further reduce the amount of grinding debris adhering. Furthermore, if the content of resin component is below the upper limit mentioned above, there is a tendency to easily obtain improved transportability by adding slip-improving components. Also, in this embodiment, the effective components of the composition for forming a surface coating refer to the components contained in the composition for forming a surface coating after removing components such as organic solvents that are removed during the formation of the surface coating.

[0048] (Slip property improving component) The slip property improving component contained in the composition for forming the surface coating is a component added to reduce the static friction coefficient of the surface coating. As a slip property improving component, it is preferable to be a compound with low surface free energy, such as a resin having hydrocarbon groups in the side chain, or a resin containing fluorine atoms in the main chain or side chain. Specifically, examples include, for example, polysiloxane compounds and fluororesins, among which, from the viewpoint of processability, polysiloxane compounds are preferred.

[0049] [Polysiloxane] There are no particular limitations on the polysiloxane as long as it is a polymer containing a polydiorganosiloxane structure. Examples of polydiorganosiloxane structures contained in a polysiloxane include those having repeating units represented by the following general formula (1).

[0050] (In the formula, each R is an independent hydrocarbon group with 1 to 6 carbon atoms, and * indicates the bonding site).

[0051] The hydrocarbon group represented by R, having 1 to 6 carbon atoms, preferably has 1 to 4 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of hydrocarbon groups represented by R, having 1 to 6 carbon atoms, include alkyl groups having 1 to 5 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tributyl, and n-pentyl; phenyl; etc. Among these, methyl is preferred.

[0052] Polysiloxanes may also have reactive functional groups. When polysiloxanes have reactive functional groups, reactions can occur between polysiloxanes or between polysiloxanes and other components, making it difficult for polysiloxanes to bleed out of the surface coating. Examples of reactive functional groups include, for example, functional groups containing vinyl, (meth)acrylyl, or other vinyl unsaturated bonds; glycidyl, amino, carboxyl, thiol, hydroxyl, etc. Among these, functional groups containing vinyl unsaturated groups are preferred, and (meth)acrylyl groups are even more preferred. In this specification, "vinyl unsaturated bond" means a carbon-carbon double bond that can undergo addition reactions, excluding double bonds of aromatic rings. Also, (meth)acrylyl can also form (meth)acryloxy groups. When a polysiloxane compound has reactive functional groups, the polysiloxane compound may have reactive functional groups at the ends or on the side chains, but it is preferred that it has reactive functional groups at the ends. When a polysiloxane compound has reactive functional groups at the ends, the polysiloxane compound may have reactive functional groups at one end or at both ends, but it is preferred that it has reactive functional groups at both ends. When a polysiloxane compound has reactive functional groups, the equivalent amount of reactive functional groups is not particularly limited, but it is preferably 500~10,000 g / mol, more preferably 1,000~7,000 g / mol, and even more preferably 1,500~5,000 g / mol.

[0053] The polysiloxane compound may be a linear polymer or a branched polymer, but is preferably a linear polymer. That is, the polysiloxane compound is preferably a linear polymer with reactive functional groups at both ends. Examples of such polysiloxane compounds are compounds represented by the following formula (2).

[0054] (In the formula, R is as described in the general formula (1) above. X is a divalent aliphatic hydrocarbon group with 1 to 5 carbon atoms, and Y is a reactive functional group).

[0055] The preferred state of R and the preferred state of the reactive functional group represented by Y are as described above. The divalent aliphatic hydrocarbon group with 1 to 5 carbon atoms represented by X are, for example, alkyl groups such as methyldiyl, ethane-1,2-diyl, ethane-1,1-diyl, n-propane-1,3-diyl, n-propane-1,2-diyl, 1,4-n-butyl, 1,2-tert-butyl, and 1,5-pentyl.

[0056] The mass average molecular weight (Mw) of the polysiloxane is not particularly limited, but is preferably 1,000 to 20,000, more preferably 2,000 to 17,000, and even more preferably 3,000 to 15,000. If the mass average molecular weight (Mw) of the polysiloxane is above the lower limit mentioned above, the surface segregation of the polysiloxane is suppressed, and there is a tendency for the film-forming properties of the composition for forming surface coatings to be better, thereby having a tendency for better transportability. Furthermore, if the mass average molecular weight (Mw) of the polysiloxane is below the upper limit mentioned above, there is a tendency for better processability.

[0057] The lubrication improvement component may contain lubrication improvement components other than polysiloxane, or it may not contain them. The content of polysiloxane in the lubrication improvement component is preferably 90-100% by mass, more preferably 95-100% by mass, and even more preferably 98-100% by mass, based on the viewpoints of further reducing the amount of grinding debris adhesion and further improving transportability.

[0058] [Heteroatom content of the slippage improvement component] The heteroatom content in the slippage improvement component is not particularly limited, but it is preferably 30% by mass or more, more preferably 40 to 80% by mass, and even more preferably 50 to 70% by mass.

[0059] [Content of Slip Improvement Component] The content of the slip improvement component in the composition for forming the surface coating is preferably 0.1 to 30% by mass, more preferably 0.3 to 20% by mass, and even more preferably 0.5 to 10% by mass, relative to the total amount of effective components (100% by mass) of the composition for forming the surface coating. When the content of the slip improvement component is below the above-mentioned lower limit, there is a tendency to further reduce the amount of grinding debris adhesion and improve transportability. Furthermore, when the content of the slip improvement component is below the above-mentioned upper limit, there is a tendency to improve the adhesion between the buffer layer and the surface coating.

[0060] (Energy-line polymerizable multifunctional compound) The composition for forming the surface coating preferably contains an energy-line polymerizable multifunctional compound. By containing an energy-line polymerizable multifunctional compound, the composition for forming the surface coating tends to improve the adhesion between the surface coating and the buffer layer of the adhesive sheet of this embodiment.

[0061] The energy-line polymerizable polyfunctional compound is a compound having two or more energy-line polymerizable functional groups. The number of energy-line polymerizable functional groups in the energy-line polymerizable polyfunctional compound is preferably 2 to 10, more preferably 3 to 8, and even more preferably 4 to 7. The energy-line polymerizable functional group in the energy-line polymerizable polyfunctional compound is preferably (meth)acrylonitrile.

[0062] As a polymerizable multifunctional compound, a multifunctional (meth)acrylate monomer is preferred. Examples of multifunctional (meth)acrylate monomers include, for example, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol dimethacrylate, neopentyl glycol adipate dimethacrylate, hydroxypentanoic acid neopentyl glycol dimethacrylate, dicyclopentyl dimethacrylate, caprolactone-modified dicyclopentenyl dimethacrylate, ethylene oxide-modified dimethacrylate phosphate, di(acryloxyethyl) isocyanurate, allylated cyclohexyl dimethacrylate, isocyanuric acid ethylene oxide-modified dimethacrylate, etc., which are difunctional (meth)acrylate monomers; trihydroxy Methylpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, tri(acryloxyethyl)isocyanurate, bis(acryloxyethyl)hydroxyethyl isocyanurate, ethylene oxide modified isocyanurate triacrylate, ε-caprolactone modified tri(acryloxyethyl)isocyanurate, diglycerol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, propionic acid modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone modified dipentaerythritol hexa(meth)acrylate, etc. Among these, dipentaerythritol hexa(meth)acrylate and dipentaerythritol penta(meth)acrylate are preferred, and dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate are even more preferred.

[0063] The content of the energy-line polymerizable polyfunctional compound in the composition for forming the surface coating is preferably 1 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 20% by mass, relative to the total amount of effective components (100% by mass) of the composition for forming the surface coating. If the content of the energy-line polymerizable polyfunctional compound is above or above the aforementioned lower limit, there is a tendency for excellent adhesion between the surface coating and the buffer layer. Furthermore, if the content of the energy-line polymerizable polyfunctional compound is below the aforementioned upper limit, there is a tendency for reducing the amount of grinding debris and improving transportability by adding resin components and lubrication-improving components.

[0064] When the composition for forming the surface coating contains a resin component and a polymerizable polyfunctional compound, the content of the polymerizable polyfunctional compound is preferably 10 to 60 parts by mass relative to 100 parts by mass of the resin component, more preferably 14 to 40 parts by mass, and even more preferably 17 to 30 parts by mass. If the content of the polymerizable polyfunctional compound is above or below the aforementioned lower limit, there is a tendency for excellent adhesion between the surface coating and the buffer layer. Furthermore, if the content of the polymerizable polyfunctional compound is below the aforementioned upper limit, there is a tendency for reducing the amount of grinding debris and improving transportability by adding the resin component and the lubricity-improving component.

[0065] (Photopolymerization initiator) When the composition for forming a surface coating contains a polyfunctional compound with energy line polymerizability, the composition for forming a surface coating preferably contains a photopolymerization initiator. One photopolymerization initiator may be used alone, or two or more may be used in combination.

[0066] Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, phosphine oxide compounds, dicene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. More specifically, examples include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, biacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, etc.

[0067] When the composition for forming the surface coating contains a photopolymerization initiator, its content is not particularly limited, but based on the viewpoint of making the energy line polymerization reaction homogeneous and sufficient, it is preferably 0.01 to 10 parts by mass relative to 100 parts by mass of the energy line polymerizable polyfunctional compound, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass.

[0068] (Other Components) The surface coating may contain other components without impairing the effects of the present invention. Examples of such other components include, for example, resins other than those described above; additives such as antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, and dyes; etc.

[0069] (Contact Angle) The static contact angle (hereinafter also referred to as "water contact angle") of water with the surface coating of the adhesive sheet of this embodiment at 23°C is preferably 85° or higher. When the water contact angle of the surface coating is 85° or higher, water containing abrasive particles is difficult to adhere to the surface coating, thus tending to further reduce the amount of abrasive particles adhering. Based on the viewpoint of further reducing the amount of abrasive particles adhering, the water contact angle of the surface coating is preferably 90° or higher, more preferably 95° or higher, and even more preferably 98° or higher. The upper limit of the water contact angle of the surface coating is not particularly limited, but based on the viewpoint of ease of manufacturing, it may be 150° or lower, or even 110° or lower. Furthermore, the water contact angle of the surface coating is a value measured according to JIS R 3257:1999, and specifically, it can be measured by the method described in the embodiments.

[0070] The thickness of the surface coating is not particularly limited, but it is preferably 0.05~10μm, more preferably 0.2~7μm, and even more preferably 1~4μm. If the thickness of the surface coating is above the lower limit mentioned above, a uniform layer can be formed, which tends to further reduce the amount of grinding debris adhering and improve transportability. Furthermore, if the thickness of the surface coating is below the upper limit mentioned above, it tends to easily obtain a buffer layer effect that absorbs foreign objects and other unevenness on the fixture platform.

[0071] <Buffer Layer> The buffer layer is a layer disposed between the substrate and the surface coating. It is responsible for absorbing vibrations and impacts generated during back-side grinding, preventing cracks from forming on the workpiece. In addition, by providing a buffer layer, unevenness or irregularities such as foreign objects present on the support platform can also be absorbed, and the support device can also improve the retention of the adhesive sheet.

[0072] (Composition for forming a buffer layer) The buffer layer may be formed from a composition for forming a buffer layer. From the viewpoint of obtaining suitable physical properties for the buffer layer, the buffer layer is preferably a layer in which the composition for forming a buffer layer containing an energy-line polymerizable compound is subjected to energy-line hardening. The composition for forming a buffer layer preferably contains urethane (meth)acrylate (a1) as an energy-line polymerizable compound. By containing urethane (meth)acrylate (a1), the composition for forming a buffer layer tends to adjust the storage elastic modulus, etc., of the buffer layer to a favorable range. Furthermore, based on the same viewpoint, the composition for forming the buffer layer preferably contains, in addition to urethane (meth)acrylate (a1), one or more polymeric compounds selected from the group consisting of alicyclic or heterocyclic groups having 6 to 20 ring-forming atoms (a2) and polymeric compounds having functional groups (a3). More preferably, in addition to urethane (meth)acrylate (a1), it also contains polymeric compounds (a2) having 6 to 20 alicyclic or heterocyclic groups and polymeric compounds having functional groups (a3). Also, in this specification, the term "ring-forming atom number" refers to the number of atoms constituting the ring itself in a compound with a cyclic bond structure. Atoms that do not constitute the ring (e.g., hydrogen atoms bonded to the atoms constituting the ring) and atoms contained in substituents when the ring is substituted are not included in the ring-forming atom number.

[0073] [Aminocarbamate (meth)acrylate (a1)] Aminocarbamate (meth)acrylate (a1) is a compound having (meth)acrylic and aminocarbamate bonds, and has the property of being polymerized by energy beam irradiation. Aminocarbamate (meth)acrylate (a1) can be used alone or in combination with two or more.

[0074] The mass average molecular weight (Mw) of the 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. Furthermore, in this embodiment, the mass average molecular weight (Mw) refers to the value converted from standard polystyrene determined by gel permeation chromatography (GPC), specifically the value determined by the method described in the examples.

[0075] The number of (meth)acrylic acid groups in one molecule of carbamate (meth)acrylate (a1) is not particularly limited, but it is preferred to have 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0076] Aminocarbamate (meth)acrylate (a1) can be obtained by reacting a terminal isocyanate aminocarbamate prepolymer obtained by reacting a polyol compound with a polyisocyanate compound, for example, with a (meth)acrylate having hydroxyl groups.

[0077] The polyol compound is not particularly limited to any compound having two or more hydroxyl groups. Specific examples of polyol compounds include alkyl glycols, polyether polyols, polyester polyols, and polycarbonate polyols. Among these, polyester polyols are preferred. The polyol compound can be any of a difunctional diol, a trifunctional triol, or a polyol with four or more functions, preferably a difunctional diol, and more preferably a polyester diol. A single polyol compound can be used alone, or two or more compounds can be used in combination.

[0078] Examples of polyisocyanate compounds include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and ω,ω'-diisocyanate-dimethylcyclohexane; and aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, betoluidine diisocyanate, tetramethylene xylene diisocyanate, and naphthalene-1,5-diisocyanate. Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylene diisocyanate are preferred. Polyisocyanate compounds can be used alone or in combination of two or more.

[0079] The (meth)acrylate having hydroxyl groups that reacts with the terminal isocyanate carbamate prepolymer is not particularly limited as long as it is a compound having both a hydroxyl group and a (meth)acrylic group in at least one molecule. Examples of (meth)acrylates having hydroxyl groups include, for example, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, etc.; hydroxyl-containing (meth)acrylic acid such as N-hydroxymethyl (meth)acrylic acid; reactants obtained by reacting (meth)acrylate with vinyl alcohol, vinylphenol, or bisphenol A diglycidyl ester; etc. Of these, hydroxyalkyl (meth)acrylate is preferred, and 2-hydroxyethyl (meth)acrylate is more preferred. A single hydroxyl-containing (meth)acrylate may be used alone, or two or more may be used in combination.

[0080] The conditions for reacting the terminal isocyanate urethane prepolymer with a (meth)acrylate having hydroxyl groups are not particularly limited, but for example, the conditions can be set to react at 60 to 100°C for 1 to 4 hours in the presence of an organic solvent, catalyst, etc., which may be added as needed.

[0081] The content of urethane (meth)acrylate (a1) in the composition for forming the buffer layer is not particularly limited, but it is preferably 10-70% by mass, more preferably 20-60% by mass, and even more preferably 30-50% by mass, relative to the total amount of effective components (100% by mass) of the composition for forming the buffer layer. In this embodiment, the effective components of the composition for forming the buffer layer refer to the components remaining after removing organic solvents and other components that are removed during the formation of the buffer layer from the components contained in the composition for forming the buffer layer.

[0082] [A polymeric compound (a2) having 6 to 20 alicyclic or heterocyclic groups forming rings] The composition for forming a buffer layer tends to improve the film-forming properties of the composition by containing a polymeric compound (a2) having 6 to 20 alicyclic or heterocyclic groups forming rings (hereinafter referred to as "polymeric compound (a2) having alicyclic or heterocyclic groups"). Examples of atoms forming the ring structure of the heterocyclic group include, for example, carbon atoms, nitrogen atoms, oxygen atoms, sulfur atoms, etc. One type of polymeric compound (a2) having alicyclic or heterocyclic groups may be used alone, or two or more may be used in combination.

[0083] The polymerizable compound (a2) having an alicyclic or heterocyclic group is preferably a compound having a (meth)acrylic group. The number of (meth)acrylic groups in one molecule of the polymerizable compound (a2) having an alicyclic or heterocyclic group is not particularly limited, but it is preferably one or more, more preferably one or two, and even more preferably one.

[0084] The polymeric compound (a2) having an alicyclic or heterocyclic group has 6 to 20 ring-forming atoms in the alicyclic or heterocyclic group, more preferably 6 to 18, even more preferably 6 to 16, and still more preferably 7 to 12.

[0085] Examples of polymerizable compounds (a2) having alicyclic or heterocyclic groups include isobornyl methacrylate, dicyclopentenyl methacrylate, dicyclopentyl methacrylate, dicyclopentenoxy methacrylate, cyclohexyl methacrylate, adamantane methacrylate, and other alicyclic (meth)acrylates; tetrahydrofurfuryl methacrylate, morpholine methacrylate, and other heterocyclic (meth)acrylates; etc. Among these, alicyclic (meth)acrylates are preferred, and isobornyl methacrylate is more preferred.

[0086] The content of polymeric compound (a2) having alicyclic or heterocyclic groups in the composition for forming a buffer layer is not particularly limited, but it is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and even more preferably 30 to 50% by mass, relative to the total amount of effective components (100% by mass) of the composition for forming a buffer layer.

[0087] [Polymerizable compound with functional group (a3)] The composition for forming a buffer layer tends to adjust the viscosity of the composition for forming a buffer layer to a suitable range by containing a polymerizable compound with functional group (a3). One polymerizable compound with functional group (a3) ​​may be used alone or two or more may be used in combination.

[0088] Examples of functional groups in the polymeric compound (a3) ​​include hydroxyl, epoxy, amide, and amino groups. The polymeric compound (a3) ​​has one or more functional groups per molecule, preferably one to three, more preferably one or two, and even more preferably one.

[0089] The polymeric compound (a3) ​​having a functional group is preferably a compound having a (meth)acrylic group together with the functional group. The number of (meth)acrylic groups in one molecule of the polymeric compound (a3) ​​having a functional group is not particularly limited, but it is preferably one or more, more preferably one or two, and even more preferably one.

[0090] Examples of polymeric compounds having functional groups (a3) ​​include, for example, polymeric compounds containing hydroxyl groups, polymeric compounds containing epoxy groups, polymeric compounds containing amide groups, and polymeric compounds containing amine groups.

[0091] Examples of hydroxyl-containing polymeric compounds include hydroxyl-containing (meth)acrylates such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, and 2-hydroxy-3-phenoxypropyl methacrylate; vinyl ether compounds such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether; etc.

[0092] Examples of epoxy-containing polymeric compounds include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether, etc.

[0093] Examples of polymeric compounds containing amide groups include (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-hydroxymethylpropane (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and N-vinylmethylamine.

[0094] Examples of amino-containing polymeric compounds include (meth)acrylates containing primary amino groups, (meth)acrylates containing secondary amino groups, (meth)acrylates containing tertiary amino groups, and so on.

[0095] Among these, hydroxyl-containing (meth)acrylates are preferred, and hydroxyl-containing (meth)acrylates with aromatic rings, such as 2-hydroxy-3-phenoxypropyl (meth)acrylate, are even more preferred.

[0096] The content of the polymeric compound (a3) ​​with functional groups in the composition for forming the buffer layer is not particularly limited, but it is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass relative to the total amount of active ingredients (100% by mass) of the composition for forming the buffer layer.

[0097] [Other Polymerizable Compounds] The composition for forming the buffer layer may contain other polymerizable compounds besides components (a1) to (a3) ​​without impairing the effects of the present invention. Examples of other polymerizable compounds include, for example, alkyl (meth)acrylates having alkyl groups having 1 to 20 carbon atoms; vinyl compounds such as styrene, N-vinylpyrrolidone, and N-vinylcaprolactam; etc. One of the other polymerizable compounds may be used alone, or two or more may be used in combination. The content of other polymerizable compounds in the composition for forming the buffer layer is not particularly limited, but it is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 2% by mass, relative to the total amount of active ingredients (100% by mass) of the composition for forming the buffer layer.

[0098] [Photopolymerization Initiator] A composition for forming a buffer layer containing an energy-line polymerizable compound, preferably containing a photopolymerization initiator based on the viewpoint of reducing polymerization time and energy line irradiation. One photopolymerization initiator may be used alone, or two or more may be used in combination.

[0099] Examples of photopolymerization initiators include, for example, benzoin compounds, acetophenone compounds, phosphine oxide compounds, titanoceramsite compounds, thioxanthone compounds, peroxide compounds, and further, photosensitizers such as amines and quinones. More specifically, examples include, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, biacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, etc. Among these, 1-hydroxycyclohexylphenyl ketone is preferred.

[0100] The content of photopolymerization initiator in the composition for forming the buffer layer is not particularly limited, but based on the viewpoint of making the energy line hardening reaction homogeneous and sufficient, it is preferably 0.05 to 15 parts by mass relative to 100 parts by mass of the energy line polymerizable compound, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass.

[0101] (Other Components) Without impairing the effects of the present invention, the composition for forming the buffer layer may contain other components. Examples of such other components include resin components other than the resins described above; antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, dyes, and other additives; etc. The content of other resin components in the composition for forming the buffer layer is not particularly limited, but it is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 2% by mass, relative to the total effective components (100% by mass) of the composition for forming the buffer layer. The content of other additives in the composition for forming the buffer layer is not particularly limited, but for each, it is preferably 0 to 6% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.1 to 3% by mass, relative to the total effective components (100% by mass) of the composition for forming the buffer layer.

[0102] (Young's modulus of the buffer layer) The Young's modulus of the buffer layer at 23°C is less than that of the substrate at 23°C. Specifically, it is preferably not 1,200 MPa, and more preferably 900 MPa or less. Furthermore, the Young's modulus of the buffer layer at 23°C is preferably 50 MPa or more, and more preferably 100 MPa or more. If the Young's modulus of the buffer layer at 23°C is below the above-mentioned upper limit, it tends to absorb vibrations and impacts generated during back-side grinding and improve the retention of the adhesive sheet. Furthermore, if the Young's modulus of the buffer layer at 23°C is above the above-mentioned lower limit, it tends to suppress excessive deformation of the buffer layer during workpiece processing. Moreover, the Young's modulus of the buffer layer at 23°C can be measured according to JIS K 7127:1999 at a test speed of 200 mm / min.

[0103] (Stress Relief Rate of Buffer Layer) The stress relief rate of the buffer layer is not particularly limited, but it is preferably 70~100%, more preferably 75~100%, and even more preferably 78~98%. If the stress relief rate of the buffer layer is within the above range, it tends to absorb vibrations and impacts generated during back-side grinding and has a higher retention of the adhesive sheet. The stress relief rate of the buffer layer is calculated by cutting a 15mm×140mm piece from a 200μm thick buffer layer as a test piece, holding the two ends of the test piece by 20mm, and stretching it by 10% at 200mm / min. The stress A (N / m2) and the stress B (N / m2) after stopping the stretching for 1 minute are calculated by the following formula: Stress Relief Rate (%) = 100×(AB) / A (%)

[0104] (Buffer layer thickness) The thickness of the buffer layer is not particularly limited, but it is preferably 5~70μm, more preferably 7~50μm, and even more preferably 10~40μm. If the thickness of the buffer layer is above the lower limit mentioned above, it tends to absorb vibrations and impacts generated during back-side grinding and improve the retention of the adhesive sheet. Furthermore, if the thickness of the buffer layer is below the upper limit mentioned above, it tends to suppress excessive deformation of the buffer layer during workpiece processing.

[0105] <Adhesive Layer> The adhesive layer is a layer disposed on the side of the substrate opposite to the buffer layer, and is attached to the workpiece. Preferably, the adhesive layer is formed of a line-curing adhesive. By forming the adhesive layer with a line-curing adhesive, sufficient adhesion can effectively protect the workpiece surface before line curing, and the peel force is reduced after line curing, allowing for easy peeling from the workpiece.

[0106] Examples of energy line curing adhesives include, for example, the X-type adhesive composition, Y-type adhesive composition, and XY-type adhesive composition described below. X-type adhesive composition: An energy line curing adhesive composition containing a non-energy line curing adhesive resin (hereinafter also referred to as "adhesive resin I") and an energy line curing compound other than an adhesive resin. Y-type adhesive composition: An energy line curing adhesive resin (hereinafter also referred to as "adhesive resin II") containing an unsaturated group introduced into the side chain of a non-energy line curing adhesive resin, and not containing an energy line curing compound other than an adhesive resin. XY-type adhesive composition: An energy line curing adhesive composition containing the aforementioned energy line curing adhesive resin II and an energy line curing compound other than an adhesive resin. Among these, the energy line curing adhesive is preferably an XY-type adhesive composition. By using an XY type adhesive composition, it has sufficient adhesion before curing, and on the other hand, it tends to significantly reduce the peeling force on the workpiece after curing.

[0107] The adhesive forming the adhesive layer may be a layer formed by a non-energy-line-curable adhesive that does not harden even when irradiated with an energy line. Examples of non-energy-line-curable adhesives include those containing adhesive resin I, but not adhesive resin II or energy-line-curable compounds.

[0108] Next, the components constituting the adhesive layer will be described in more detail. In the following description, "adhesive resin" refers to one or both of adhesive resin I and / or adhesive resin II. Furthermore, in the following description, when referred to only as "adhesive composition," the concept also includes type X adhesive composition, type Y adhesive composition, type XY adhesive composition, and other adhesive compositions.

[0109] Examples of adhesive resins include acrylic resins, urethane resins, rubber resins, and polysiloxane resins. Among these, acrylic resins are preferred.

[0110] (Acrylic Resin) The acrylic resin preferably contains a constituent unit derived from (meth)acrylate. Examples of (meth)acrylates include (meth)acrylates with alkyl groups having 1 to 20 carbon atoms. The alkyl groups in the (meth)acrylate can be linear or branched.

[0111] From the viewpoint of further improving the adhesion of the adhesive layer, acrylic resins preferably contain (meth)acrylate alkyl units with 4 or more carbon atoms derived from alkyl groups. The (meth)acrylate alkyl units with 4 or more carbon atoms derived from alkyl groups contained in the acrylic resin can be one type or two or more types. The number of carbon atoms in the alkyl group of the (meth)acrylate alkyl group with 4 or more carbon atoms is preferably 4 to 12, more preferably 4 to 8, and even more preferably 4 to 6. Examples of (meth)acrylate alkyl groups with 4 or more carbon atoms 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 even more preferred. When an acrylic resin contains alkyl (meth)acrylate constituents with 4 or more carbon atoms derived from alkyl groups, from the viewpoint of further improving the adhesion of the adhesive layer, its content in the acrylic resin is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, and even more preferably 45 to 60% by mass.

[0112] Acrylic resins, based on the viewpoint of improving the storage modulus G' of the adhesive layer and its adhesive properties, preferably contain (meth)acrylate units with 1 to 3 carbon atoms derived from alkyl groups, together with (meth)acrylate units with 4 or more carbon atoms derived from alkyl groups. The (meth)acrylate units with 1 to 3 carbon atoms derived from alkyl groups in the acrylic resin can be a single type or two or more types. Examples of (meth)acrylate units with 1 to 3 carbon atoms derived from alkyl groups include, for example, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, and n-propyl methacrylate. Among these, methyl methacrylate and ethyl methacrylate are preferred, more preferably methyl methacrylate, and even more preferably methyl methacrylate. When an acrylic resin contains a (meth)acrylate alkyl ester with 1 to 3 carbon atoms derived from an alkyl group, the content of the alkyl ester in the acrylic resin is preferably 1 to 35% by mass, more preferably 5 to 30% by mass, and even more preferably 15 to 25% by mass.

[0113] Acrylic resins preferably contain constituent units derived from functionalized monomers. By containing constituent units derived from functionalized monomers, functional groups that can serve as crosslinking initiation points for reactions with crosslinking agents, or functional groups that can react with compounds containing unsaturated groups to introduce unsaturated groups into the side chains of the acrylic resin, can be incorporated into the acrylic resin. The constituent units derived from functionalized monomers contained in the acrylic resin can be one or more types.

[0114] Examples of functionalized monomers include, for example, hydroxyl-containing monomers, carboxyl-containing monomers, amino-containing monomers, and epoxy-containing monomers. Among these, hydroxyl-containing monomers and carboxyl-containing monomers are preferred, and hydroxyl-containing monomers are even more preferred. Examples of hydroxyl-containing monomers include, for example, hydroxyalkyl esters of (meth)acrylate such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl methacrylate, and 4-hydroxybutyl methacrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol; etc. Examples of carboxyl-containing monomers include, for example, vinyl unsaturated monocarboxylic acids such as (meth)acrylate and crotonic acid; vinyl unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, and citraconic acid and their anhydrides; 2-carboxyethyl methacrylate; etc.

[0115] When acrylic resins contain constituent units derived from functional group monomers, their content is not particularly limited, but in acrylic resins, it is preferably 5 to 45% by mass, more preferably 15 to 40% by mass, and even more preferably 25 to 35% by mass.

[0116] Acrylic resins, in addition to the constituent units described above, may also contain constituent units derived from other monomers that can copolymerize with acrylic monomers. The constituent units derived from other monomers contained in acrylic resins may be one or more individual types. Examples of other monomers include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, propionitrile, acrylamide, etc.

[0117] Acrylic resins, and furthermore, to impart energy line curing properties, may be introduced with unsaturated groups possessing energy line polymerization properties. The unsaturated group can be introduced, for example, by reacting a functional group of an acrylic resin containing a constituent unit derived from a functional group monomer with a reactive substituent and an unsaturated group of a compound (hereinafter referred to as "the compound containing the unsaturated group") having a reactive substituent that is reactive with the functional group. The compound containing the unsaturated group may be used alone or in combination with two or more. Examples of unsaturated groups in the compound containing the unsaturated group include (meth)acrylyl, vinyl, allyl, etc. Among these, (meth)acrylyl is preferred. Examples of reactive substituents in the compound containing the unsaturated group include isocyanate groups, glycidyl groups, etc. Examples of compounds containing unsaturated groups include, for example, methacryloxyethyl isocyanate, methacrylyl isocyanate, and glycidyl methacrylate.

[0118] When an acrylic resin containing constituent units derived from functionalized monomers reacts with a compound containing unsaturated groups, the ratio of functional groups reacting with the compound containing unsaturated groups to the total number of functional groups in the acrylic resin is not particularly limited, but is preferably 60-98 mol%, more preferably 70-95 mol%, and even more preferably 80-93 mol%. If the ratio of functional groups reacting with the compound containing unsaturated groups is within the above range, the acrylic resin can be endowed with sufficient energy line curing properties, and the functional groups that do not react with the compound containing unsaturated groups can react with a crosslinking agent to crosslink the acrylic resin.

[0119] The average molecular weight (Mw) of the acrylic resin is not particularly limited, but it 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. If the average molecular weight (Mw) of the acrylic resin is within the above range, there is a tendency for better adhesion and cohesion of the adhesive layer.

[0120] (Energy-line curing compound) The energy-line curing compound contained in the composition of X-type or XY-type adhesives is preferably a monomer or oligomer having an unsaturated group within the molecule, which can be cured by energy-line irradiation. Examples of energy-line curing compounds include poly(meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate; oligomers such as urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and epoxy (meth)acrylate; etc. Among these, urethane (meth)acrylate oligomers are preferred because their relatively high molecular weight makes it difficult to reduce the elastic modulus of the adhesive layer.

[0121] The molecular weight of the energy line hardening 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 still more preferably 600 to 6,000. Furthermore, when the energy line hardening compound is an oligomer, the above molecular weight refers to the mass average molecular weight (Mw).

[0122] The content of the energy-curing compound in the X-type adhesive composition is not particularly limited, but it is preferably 40 to 200 parts by weight relative to 100 parts by weight of the adhesive resin, more preferably 50 to 150 parts by weight, and even more preferably 60 to 90 parts by weight. If the content of the energy-curing compound in the X-type adhesive composition is within the above range, it tends to achieve a good balance between the adhesiveness before energy-line irradiation and the peelability after energy-line irradiation.

[0123] The content of the energy-curing compound in the XY type adhesive composition is not particularly limited, but it is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 3 to 15 parts by weight relative to 100 parts by weight of the adhesive resin. If the content of the energy-curing compound in the XY type adhesive composition is within the above range, it tends to achieve a good balance between the adhesive force before energy beam irradiation and the peel strength after energy beam irradiation. Furthermore, since the adhesive resin in the XY type adhesive composition is energy-curing, even if the content of the energy-curing compound is low, it still tends to sufficiently reduce the peel strength after energy beam irradiation.

[0124] (Crosslinking agent) The adhesive composition preferably contains a crosslinking agent. The crosslinking agent is, for example, that crosslinks the adhesive resins by reacting with functional groups derived from functional monomers of the adhesive resin. One type of crosslinking agent may be used alone, or two or more may be used in combination.

[0125] Examples of crosslinking agents include isocyanate-based crosslinking agents such as toluene 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]triphosphine triazine; chelating crosslinking agents such as aluminum chelating agents; etc. Among these, isocyanate-based crosslinking agents are preferred from the viewpoint of improving cohesive strength and further improving adhesiveness.

[0126] When the adhesive composition contains a crosslinking agent, its content is not particularly limited, but based on the viewpoint of moderately carrying out the crosslinking reaction, it is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 7 parts by weight, and even more preferably 0.05 to 4 parts by weight, relative to 100 parts by weight of adhesive resin.

[0127] (Photopolymerization Initiator) When the adhesive is an energy-line curing adhesive, the adhesive composition is preferably to contain a photopolymerization initiator. Because the energy-line curing adhesive contains a photopolymerization initiator, even with relatively low-energy energy lines such as ultraviolet light, the curing reaction of the energy-line curing adhesive tends to proceed sufficiently. One photopolymerization initiator can be used alone, or two or more can be used in combination.

[0128] Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, phosphine oxide compounds, titanoceramsite compounds, thioxanone compounds, peroxide compounds, and photosensitizers such as amines and quinones. More specifically, examples include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, biacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, etc.

[0129] When the energy line hardening adhesive contains a photopolymerization initiator, its content is not particularly limited, but based on the viewpoint of making the energy line hardening reaction homogeneous and sufficient, it is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 7 parts by weight, and even more preferably 0.05 to 5 parts by weight, relative to 100 parts by weight of adhesive resin.

[0130] (Other Additives) Without impairing the effects of the present invention, the adhesive composition may contain other additives. Examples of such other additives include, for example, antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, dyes, etc. The content of other additives in the adhesive composition is not particularly limited, but for each, it is preferably 0 to 6% by mass relative to the total amount (100% by mass) of the effective components of the adhesive composition, more preferably 0.01 to 5% by mass, and even more preferably 0.1 to 3% by mass. In this embodiment, the effective components of the adhesive composition refer to the components remaining after removing organic solvents and other components that are removed during the process of forming the adhesive layer from the components contained in the adhesive composition.

[0131] (Organic Solvent) Based on the viewpoint of improving the coatability of the adhesive composition to substrates and release films, it can also be diluted with an organic solvent to form a solution. Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, etc. One organic solvent can be used alone, or two or more can be used in combination. The organic solvent used in the synthesis of the adhesive resin can be used directly, or one or more organic solvents other than those used in the synthesis can be added.

[0132] The storage elastic modulus G' of the adhesive layer at 23°C is not particularly limited, but it is preferably 0.05~0.5MPa, more preferably 0.1~0.4MPa, and even more preferably 0.12~0.3MPa. If the storage elastic modulus G' of the adhesive layer at 23°C is within the above range, then even when the workpiece surface has unevenness, an adhesive layer with excellent conformability to the uneven shape can be obtained, and it tends to better protect the workpiece surface during processing. Furthermore, the storage elastic modulus G' of the adhesive layer, when the adhesive layer is formed by energy line curing adhesive, refers to the storage elastic modulus G' before curing by energy line irradiation. The storage modulus of elasticity G' of the adhesive layer at 23°C can be determined by cutting a 3mm thick adhesive layer into a circular piece with a diameter of 8mm as a test piece, and using the torsional shear method of a viscoelasticity measuring device at a frequency of 1Hz and a measurement temperature of 23°C.

[0133] 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. If the thickness of the adhesive layer is above or above the lower limit mentioned above, it tends to obtain excellent adhesion and better protect the surface of the workpiece during processing. Furthermore, if the thickness of the adhesive layer is below the upper limit mentioned above, the occurrence of tape debris when the adhesive sheet is cut is suppressed, and workpiece breakage can be better prevented.

[0134] <Substrate> Examples of substrates include various resin films. Examples of resins constituting 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 copolymer; polyvinyl chloride such as polyvinyl chloride and ethylene chloride copolymer; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and fully aromatic polyesters; polyurethane, polyimide, polyamide, polycarbonate, fluoropolymer, polyacetal, modified polyphenylene ether, polyphenylene sulfide, polyurethane, polyetherketone, and acrylic polymers. The substrate can be a single-layer film made of one or more resins selected from the aforementioned resins, or a laminated film made by stacking two or more resins. Furthermore, it can also be a modified film such as a cross-linked film or an ionomer film of the aforementioned resins. Among these resin films, the substrate is preferably selected from one or more of polyacrylate films, polyamide films, polyimide films, and biaxially stretched polypropylene films, more preferably a polyester film, and even more preferably a polyethylene terephthalate film.

[0135] The Young's modulus of the substrate is not particularly limited, but it is preferably 1,000 MPa or higher, more preferably 1,800 to 30,000 MPa, and even more preferably 2,500 to 6,000 MPa. If the Young's modulus of the substrate is above the lower limit mentioned above, the vibration suppression effect during workpiece processing tends to be further improved. Furthermore, if the Young's modulus of the substrate is below the upper limit mentioned above, the workability when attached to the workpiece and the workability when peeled off from the workpiece tends to be good. The Young's modulus of the substrate was determined according to JIS K 7127:1999, under the condition of a test speed of 200 mm / min.

[0136] The thickness of the substrate is not particularly limited, but it is preferably 10 to 200 μm, more preferably 25 to 100 μm, and even more preferably 30 to 70 μm. If the substrate thickness is below the lower limit mentioned above, it tends to obtain sufficient strength to function as a support for the adhesive sheet. Furthermore, if the substrate thickness is below the upper limit mentioned above, it tends to obtain moderate flexibility and improved processability. Also, the term "substrate thickness" refers to the overall thickness of the substrate, and if the substrate is composed of multiple layers, it refers to the total thickness of all layers constituting the substrate.

[0137] Without impairing the effects of the present invention, the substrate may contain plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, catalysts, etc. The substrate may be transparent or opaque, and may be colored or vapor-deposited as needed. From the viewpoint of improving adhesion to other layers, the substrate may also have a surface treatment such as corona treatment on at least one side, or a coating may be provided to improve adhesion.

[0138] <Release Sheet> In this embodiment, the adhesive sheet can also be attached to at least one of the surface of the adhesive layer and the surface coating. The release sheet protects the surface of the adhesive sheet by being peelably attached to it before use, and is peeled off when the adhesive sheet is used. The release sheet can be a release sheet that has undergone single-sided peeling treatment or a release sheet that has undergone double-sided peeling treatment. An example of a release sheet is a release sheet on a release sheet substrate coated with a release agent. As the substrate for the release sheet, a resin film is preferred. 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; etc. Examples of release agents include rubber-based elastomers such as polysiloxane resins, olefin resins, isoprene resins, and butadiene resins; long-chain alkyl resins, alkyd resins, and fluorinated resins. The thickness of the release film is not particularly limited, but is preferably 5–200 μm, more preferably 10–100 μm, and even more preferably 20–50 μm.

[0139] The total thickness of the adhesive sheet in this embodiment is not particularly limited, but is preferably 30-300 μm, more preferably 40-220 μm, and even more preferably 45-160 μm. If the total thickness of the adhesive sheet is above the lower limit mentioned above, the adhesive properties of the adhesive layer and the impact absorption properties of the buffer layer can be appropriately maintained, and the function of the adhesive sheet for semiconductor processing can be fully utilized. Furthermore, if the total thickness of the adhesive sheet is below the upper limit mentioned above, the peeling force when the self-adhesive sheet is peeled off the workpiece can be reduced. In this embodiment, the "total thickness of the adhesive sheet" refers to the thickness from the surface of the surface coating of the self-adhesive sheet to the surface of the adhesive layer. When a peeling sheet is provided, the thickness of the peeling sheet is not included in the total thickness.

[0140] <Method for Manufacturing Adhesive Sheet> The method for manufacturing the adhesive sheet of this embodiment is not particularly limited, and it can be manufactured by conventional methods. The adhesive sheet of this embodiment can be manufactured by, for example, a method having the following steps: a step of forming an adhesive layer on one side of a substrate (hereinafter also referred to as the "adhesive layer forming step"); a step of forming a buffer layer on the other side of the substrate (hereinafter also referred to as the "buffer layer forming step"); and a step of forming a surface coating on the side of the buffer layer opposite to the substrate (hereinafter also referred to as the "surface coating forming step"). Furthermore, the order of these steps is not particularly limited, and they can be performed simultaneously when possible.

[0141] As a method for forming an adhesive layer, a buffer layer or a surface coating, for example, after applying an adhesive composition, a buffer layer forming composition or a surface coating coating liquid to a specific location by conventional methods, an energy beam irradiation or heating drying is performed as necessary.

[0142] Examples of methods for using coating adhesive composition, buffer layer forming composition or surface coating liquid include spin coating, spray coating, bar coating, knife coating, roller coating, doctor blade coating, die coating, gravure coating, etc.

[0143] The adhesive layer forming step can be, for example, a method of attaching an adhesive layer formed on a release sheet to a substrate surface, or a method of forming an adhesive layer by directly applying an adhesive composition to the substrate surface. In the buffer layer forming step, a buffer layer forming composition can be applied to a release sheet or directly to the substrate surface. When the buffer layer forming composition is applied to the release sheet, the layer formed by 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 substrate surface. The buffer layer forming composition layer on the release sheet can be the buffer layer itself, or, if the buffer layer forming composition is curable, it can be an uncured or semi-cured form of a curable buffer layer forming composition. When an uncured or semi-cured form of the buffer layer forming composition is formed on the substrate, a process to completely cure the buffer layer forming composition is subsequently performed. In the surface coating formation step, the surface coating liquid can be applied to the release sheet or directly to the surface of the buffer layer. When applying the surface coating liquid to the release sheet, the layer formed by the surface coating forming composition (hereinafter also referred to as the "surface coating forming composition layer") on the release sheet is subsequently attached to the surface of the buffer layer. The surface coating forming composition layer on the release sheet can be the surface coating itself, or, if the surface coating forming composition is curable, it can be an uncured or semi-cured portion of the curable surface coating forming composition. When an uncured or semi-cured portion of the surface coating forming composition is formed on the buffer layer, a process to completely cure the surface coating forming composition is subsequently performed. Furthermore, the buffer layer formation step and the surface coating formation step can be a method in which the surface coating and the buffer layer are sequentially applied to the release sheet, and then the buffer layer is attached to the surface of the substrate.

[0144] When the composition for forming the buffer layer contains an energy-line polymerizable compound, the buffer layer forming step preferably includes the step of irradiating the composition for forming the buffer layer with an energy line. When the composition for forming the buffer layer contains an energy-line polymerizable compound, the curing process by energy line irradiation can be performed in one step or in multiple steps. When the curing process by energy line irradiation is performed in one step, after forming a coating film of the composition for forming the buffer layer on the substrate, the composition for forming the buffer layer can be completely cured by energy line irradiation, or the composition for forming the buffer layer can be completely cured on a release film and then bonded to the substrate. When the composition for forming the surface coating contains an energy-line polymerizable compound, the surface coating forming step preferably includes the step of irradiating the composition for forming the surface coating with an energy line. There is no particular limitation on the timing of irradiating the composition for forming the surface coating with an energy line; it can be performed either before or after the surface coating is deposited on the buffer layer or the buffer layer. When the curing process of the buffer layer forming composition is performed in multiple stages, after forming a coating film of the buffer layer forming composition on a release sheet, the buffer layer forming composition is not fully cured on the release sheet, but rather cured to a semi-cured state. Then, a surface coating forming composition layer is attached to the release sheet, and then the buffer layer forming composition is fully cured again by irradiation with energy rays. When the surface coating forming composition contains an energy-polymerizable compound, the surface coating forming composition can be cured simultaneously by irradiation with energy rays. The energy rays used for the curing process of the buffer layer forming composition and the surface coating forming composition are preferably ultraviolet rays. When the buffer layer forming composition and the surface coating forming composition are irradiated with energy rays for curing, the buffer layer forming composition and the surface coating forming composition may be exposed to the outside, but it is preferable that both sides are covered by components such as release sheets and substrates to prevent exposure to the outside when irradiated with energy rays.

[0145] <Applications of the Adhesive Sheet> Examples of workpiece processing performed with the adhesive sheet of this embodiment attached include back-side grinding with one side of a semiconductor device attached, dicing of a semiconductor device with the adhesive sheet attached to one side of the semiconductor device, semiconductor device transport, and semiconductor wafer picking. In these applications, the adhesive sheet of this embodiment is suitable for back-side grinding, specifically for grinding the back side of a semiconductor wafer with the adhesive sheet of this embodiment attached to the circuit forming surface of the semiconductor wafer. In particular, the adhesive sheet of this embodiment has the effect of suppressing crack formation when thinning semiconductor wafers, making it suitable for processes such as pre-grinding dicing and stealth pre-grinding dicing.

[0146] [Semiconductor Device Manufacturing Method] The semiconductor device manufacturing method of this embodiment includes the following steps: attaching the semiconductor processing adhesive sheet of this embodiment to the surface of a semiconductor wafer using the aforementioned adhesive layer as the attachment surface; and grinding the back side of the semiconductor wafer while the aforementioned surface coating side of the semiconductor processing adhesive sheet attached to the aforementioned semiconductor wafer is fixed by a support device.

[0147] Furthermore, the manufacturing method of the semiconductor device of this embodiment preferably includes the following steps: a step of forming a predetermined dividing line: step a of forming a trench on the surface of a semiconductor wafer, or step b of forming a modified region inside the semiconductor wafer from the surface or back side of the semiconductor wafer; a wafer attachment step: after step a, or before or after step b, using the aforementioned adhesive layer as the attachment surface, attaching the semiconductor processing adhesive wafer of this embodiment to the surface of the semiconductor wafer; and a grinding and monolithization step: with the surface coating side of the semiconductor processing adhesive wafer attached to the semiconductor wafer fixed by a support device, grinding the back side of the semiconductor wafer, and using the aforementioned trench or modified region as a starting point, monolithizing the semiconductor wafer into a plurality of semiconductor wafers. In addition, the manufacturing method of the semiconductor device of this embodiment may also include a peeling step of peeling off the semiconductor processing adhesive wafer of this embodiment from the plurality of semiconductor wafers after the grinding and monolithization step. Furthermore, the manufacturing method of the semiconductor device having step a above is equivalent to the pre-grinding dicing process, and the manufacturing method of the semiconductor device having step b above is equivalent to the stealth pre-grinding dicing process.

[0148] 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 the semiconductor wafer. These circuits can be formed, for example, by conventional methods such as etching or stripping. The thickness of the semiconductor wafer before polishing is not particularly limited, and is typically 500 to 1,000 μm. Hereinafter, each step of the manufacturing method of the semiconductor device of this embodiment will be described in detail.

[0149] <Separation Predetermined Line Formation Step> The separation predetermined line formation step is step a, which forms a trench on the surface of the semiconductor wafer, or step b, which forms a modified region inside the semiconductor wafer from the surface or back side of the semiconductor wafer.

[0150] Step a is the step of forming trenches on the surface of a semiconductor wafer, and is performed before attaching the adhesive sheet to the surface of the semiconductor wafer. The trenches formed on the surface of the semiconductor wafer in step a are shallower than the thickness of the semiconductor wafer. After step a, the back side of the semiconductor wafer is ground into the trenches formed in step a, and divided into a plurality of semiconductor wafers. Therefore, in step a, the trenches are formed along the dividing lines when the semiconductor wafer is divided into monolithic semiconductor wafers. The trenches can be formed by cutting using conventional wafer dicing equipment or the like.

[0151] Step b is a step of forming a modified region inside the semiconductor wafer from the surface or back side of the semiconductor wafer. This step can be performed before or after attaching the adhesive sheet to the surface of the semiconductor wafer. The modified region in step b is formed inside the semiconductor wafer by laser irradiation focused on the interior of the semiconductor wafer. This modified region is a region in the semiconductor wafer that has become embrittled, thinned due to back-side grinding, or damaged by the force applied during grinding, becoming the starting point for monolithizing the semiconductor wafer into a semiconductor wafer. Therefore, the modified region is formed along the dividing line when the semiconductor wafer is diced and monolithized into a semiconductor wafer. Laser irradiation can be performed from the surface side of the semiconductor wafer or from the back side. When step b is performed after the sheet attachment step, the laser can be irradiated onto the semiconductor wafer through the adhesive sheet.

[0152] <Wafer Attachment Step> The wafer attachment step is a step performed after step a, or before or after step b, in which an adhesive wafer is attached to the surface of a semiconductor wafer with an adhesive layer as the attachment surface. The method of attaching the adhesive wafer is not particularly limited, and conventional methods such as using a laminator can be applied.

[0153] <Grinding and Monolithization Step> The grinding and monolithization step involves grinding the back side of the semiconductor wafer, starting from the aforementioned groove or modified region, to monolithize it into multiple semiconductor wafers, while the surface coating side of the adhesive sheet attached to the semiconductor wafer is fixed by a support device. The semiconductor wafer with the adhesive sheet attached and the groove or modified region formed is fixed by a support device on the surface coating side of the adhesive sheet. There are no particular limitations on the support device, but it is preferable to use a device such as a clamping stage to adsorb and hold the object.

[0154] Next, the back side of the fixed semiconductor wafer is ground to monolithically divide the semiconductor wafer into multiple semiconductor wafers. During back-side grinding, when a groove is formed on the semiconductor wafer in step a, the semiconductor wafer is ground at least from the grinding surface to the bottom of the groove. Through this back-side grinding, the groove becomes a cut through the wafer, and the semiconductor wafer is divided using the cut, monolithically dividing it into individual semiconductor wafers. On the other hand, in the case where a modification region is formed on the semiconductor wafer in step b, the grinding surface can reach the modification region, but strictly speaking, it may not reach the modification region. That is, the semiconductor wafer is destroyed and monolithically divided into semiconductor wafers starting from the modification region, and grinding is performed until the position is close to the modification region. For example, the semiconductor wafer may not be monolithically divided; after grinding to the position close to the modification region, a pick-up tape may be attached to the semiconductor wafer, and the semiconductor wafer may be monolithically divided by extending the pick-up tape.

[0155] The shape of the monolithized semiconductor wafer can be square or rectangular and other elongated shapes. The thickness of the monolithized semiconductor wafer is not particularly limited, but is preferably 5~100μm, more preferably 7~70μm, and even more preferably 10~45μm. The wafer size of the monolithized semiconductor wafer is not particularly limited, but is preferably not more than 50mm², more preferably not more than 30mm², and even more preferably not more than 10mm².

[0156] <Removal Step> The removal step is a step performed after the grinding and monolithization steps to remove adhesive films from multiple semiconductor wafers. When the adhesive layer of the adhesive film is formed by an energy line curing adhesive, the adhesive is hardened by irradiation with an energy line, reducing the peeling force of the adhesive layer, and then the adhesive film is removed. Furthermore, a pick-up tape can be used when removing the adhesive film. The pick-up tape, for example, is composed of an adhesive film having a substrate and an adhesive layer disposed on one side of the substrate. When using the pick-up tape, firstly, the pick-up tape is attached to the back side of the monolithized semiconductor wafer, and the position and orientation are aligned in a pickable manner. At this time, the ring frame disposed on the outer periphery of the semiconductor wafer is also attached to the pick-up tape, preferably fixing the outer periphery of the pick-up tape to the ring frame. Next, the adhesive films are removed from the multiple semiconductor wafers fixed to the pick-up tape. Subsequently, after picking up a plurality of semiconductor wafers located on the pick-up tape, they are fixed onto a substrate or the like to manufacture a semiconductor device. [Example]

[0157] The present invention will be described in more detail below based on embodiments, but the present invention is not limited to these embodiments. Methods for measuring and evaluating various physical properties are as follows.

[0158] [Mass Average Molecular Weight (Mw)] The mass average molecular weight (Mw) was determined using a gel permeation chromatography apparatus (manufactured by TOSOH Corporation, product name "HLC-8220") under the following conditions, and converted to standard polystyrene. (Determination conditions) • Column: "TSK Protective Column HXL-H", "TSK Gel GMHXL (×2)", "TSK Gel G2000HXL" (all manufactured by TOSOH Corporation) • Column temperature: 40℃ • Developing solvent: tetrahydrofuran • Flow rate: 1.0 mL / min

[0159] [Thickness Measurement of Adhesive Sheets, etc.] The total thickness and thickness of each layer of the adhesive sheet are measured using a constant pressure thickness gauge (manufactured by Teclock Co., Ltd., trade name "PG-02"). The thickness of the test piece prepared by these measurements is then determined. At this time, 10 arbitrary points are measured, and the average value is calculated. Furthermore, the total thickness of the adhesive sheet is the value obtained by subtracting the thickness of the release liner from the thickness of the adhesive sheet with the release liner attached. The thickness of the buffer layer is the value obtained by subtracting the thickness of the substrate with the buffer layer attached. The thickness of the surface coating is the value obtained by subtracting the thickness of the release liner from the thickness of the surface coating with the release liner attached. The thickness of the adhesive layer is the value obtained by subtracting the thicknesses of the surface coating, buffer layer, and substrate from the total thickness of the adhesive sheet.

[0160] [Determination of Static Friction Coefficient] The static friction coefficient of the surface coating of the adhesive sheet was determined according to JIS K 7125:1999 in the following order. The adhesive sheets manufactured in the examples and comparative examples were cut into 63mm × 63mm pieces, and the peeled sheet with the surface coating removed was used as a sliding sheet. A weight (mass 1,000g) having the same shape as the sliding sheet was attached to the adhesive layer of the sliding sheet with the weight as the attachment surface, and then placed on a SUS304#600 steel plate with the surface coating of the sliding sheet as the contact surface. Next, the weight was stretched horizontally at a speed of 100mm / min, and the static friction coefficient was calculated from the maximum load during the stretching. The test was conducted at 23°C and 50%RH.

[0161] [Determination of Water Contact Angle of Surface Coating] The water contact angle of the surface coating was determined according to JIS R 3257:1999. Specifically, the peeling sheet on the surface coating side of the adhesive sheet manufactured in the examples and comparative examples was peeled off, and the static contact angle when pure water was dropped onto the exposed surface coating was measured using a fully automated contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., product name "DM-701") under the following conditions: • Measurement temperature: 23°C • Droplet volume of pure water: 2 μl • Measurement time: 1 second after dropping • Image analysis method: θ / 2 method

[0162] [Evaluation of the amount of grinding debris adhering to the surface coating] The adhesive sheets manufactured in the examples and comparative examples were cut into 5cm squares, and the peeling sheet with the surface coating peeled off was used to prepare test pieces to expose the surface coating. The test piece was fixed at any one of the four corners and suspended, and immersed in polishing water containing 2% by mass silicon wafer polishing debris for 1 minute. The test piece was removed from the polishing water and dried in a suspended state at 23°C for 24 hours. The surface coating of the test piece was then visually observed, and the amount of grinding debris adhering was evaluated according to the following criteria. In the following evaluation criteria, "grinding debris adhering area" refers to the island-shaped grinding debris adhering to the surface coating, formed by the drying of the polishing water droplets. A: There is one grinding debris adhering area on the surface coating, or no grinding debris adhering to the extent that can be identified as a grinding debris adhering area. B: There are two or more grinding debris adhering areas on the surface coating.

[0163] [Evaluation of Transportability] The adhesive sheets manufactured in the Examples and Comparative Examples were attached to a silicon mirror wafer (12 inches in diameter, 50 μm thick, dry polished) with the adhesive layer as the attachment surface to create a silicon mirror wafer with an adhesive sheet (hereinafter also referred to as "wafer with an adhesive sheet"). The wafer from which the surface coating of the wafer with the adhesive sheet was peeled off was placed on a heating stage with the surface coating as the contact surface and heated at 80°C for 3 minutes. Subsequently, the adsorption surface of the transport arm with the adsorption surface of the adsorption mechanism was placed on the silicon mirror wafer side of the wafer with the adhesive sheet, and the wafer with the adhesive sheet was adsorbed and suctioned on the adsorption surface. The ability of the wafer with the adhesive sheet to be pulled up from the heating stage was tested, and the transportability was evaluated according to the following criteria. A: The wafer with the adhesive sheet can be pulled up from the heating stage using the transport arm. B: The wafer with the attached film is tightly attached to the heating stage, and it is impossible to use the transfer arm to pull the wafer with the attached film off the heating stage.

[0164] [Preparation of urethane acrylate oligomers for use in buffer layers] Manufacturing Example 1: A terminal isocyanate urethane prepolymer obtained by reacting polyester diol with isophorone diisocyanate was reacted with 2-hydroxyethyl acrylate to obtain a difunctional urethane acrylate oligomer with a mass average molecular weight (Mw) of 5,000.

[0165] [Preparation of Energy Line Curable Acrylic Resin for Adhesive Layer] Manufacturing Example 2: An acrylic polymer was obtained by copolymerizing 52 parts by weight of n-butyl acrylate, 20 parts by weight of methyl methacrylate, and 28 parts by weight of 2-hydroxyethyl acrylate. Next, the acrylic polymer was reacted with 2-methacryloyloxyethyl isocyanate to add 90 moles of the total hydroxyl groups of the acrylic polymer, thereby obtaining an energy line curable acrylic resin with a weight average molecular weight (Mw) of 500,000.

[0166] [Manufacturing of Adhesive Sheets] Examples 1-10, Comparative Example 1 Next, adhesive sheets were manufactured by the method described below. Furthermore, the amounts of each component described below refer entirely to the amounts of the active ingredient.

[0167] (1) Preparation of substrate As a substrate, a polyethylene terephthalate film with a thickness of 50 μm (Young's modulus: 2,500 MPa) was prepared.

[0168] (2) Preparation of the composition for forming a surface coating: The composition for forming a surface coating is prepared by dissolving the components shown in Table 1 in toluene at an effective component concentration of 10% by mass.

[0169] (3) Preparation and formulation of the composition for buffer layer formation: 40 parts by weight of urethane acrylate oligomer, 40 parts by weight of isobornyl acrylate, 20 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate, 2.0 parts by weight of 1-hydroxycyclohexylphenyl ketone as a photopolymerization initiator, and 0.2 parts by weight of phthalocyanine pigment were prepared to form the composition for buffer layer formation.

[0170] (4) Preparation and formulation of adhesive composition 100 parts by weight of the energy line curable acrylic resin obtained in Example 2, 6 parts by weight of the polyfunctional amino carbamate acrylate of the energy line curable compound (manufactured by Mitsubishi Chemical Co., Ltd., trade name "Shiko UT-4332", mass average molecular weight (Mw) 4,700), 0.375 parts by weight of the isocyanate crosslinking agent (manufactured by TOSOH Co., Ltd., trade name "Coronate L") and 1 part by weight of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator, were diluted with an organic solvent to prepare the adhesive composition.

[0171] (5) The adhesive sheet is formed on one side of the substrate shown above. The buffer layer forming composition obtained above is coated with the buffer layer forming composition to form a buffer layer thickness of 13 μm. The buffer layer forming composition is semi-cured by irradiation with ultraviolet light under the conditions of 30 mW / cm2 irradiation and 60 mJ / cm2 irradiation, and a layer of buffer layer forming composition semi-cured is formed on one side of the substrate. Furthermore, on the release treatment surface of the release sheet (manufactured by LINTEC Co., Ltd., trade name "SP-PET381031"), the surface coating forming composition obtained above is coated with a Maya rod to a thickness of 2 μm after drying, and then heated and dried to form a surface coating with the release sheet attached. After bonding the surface coating of the release sheet with a semi-cured layer of the buffer layer forming composition formed on one side of the substrate, the substrate is irradiated with ultraviolet light at an illuminance of 160 mW / cm² and an irradiation dose of 500 mJ / cm² to cure the buffer layer forming composition and the surface coating forming composition, thereby obtaining a laminate having a buffer layer and a surface coating sequentially on one side of the substrate. Furthermore, the obtained adhesive composition is coated onto the release-treated surface of the release sheet (manufactured by LINTEC Co., Ltd., trade name "SP-PET381031") to a thickness of 20 μm after drying, 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 without a buffer layer, an adhesive sheet having a surface coating, a buffer layer, a substrate, and an adhesive layer sequentially is obtained.

[0172] The evaluation results of the adhesive sheets obtained using the various embodiments and comparative examples are shown in Table 1.

[0173]

[0174] •H1043: Hydrogenated styrene-based thermoplastic elastomer (SEBS), styrene content: 67% by mass, manufactured by Asahi Kasei Corporation, trade name "Suftec (registered trademark) H1043" •PMA-L: Propylene-butene-maleic anhydride copolymer, maleic anhydride modification rate: 1.5% by mass, average molecular weight (Mw): 75,000, manufactured by Toyobo Corporation, trade name "Toyotac (registered trademark) PMA-L"

[0175] • X-22-164B: A polydimethylsiloxane compound with methacryloxy groups at both ends, with a mass average molecular weight (Mw) of 5,000. Manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-22-164B". • X-22-164E: A polydimethylsiloxane compound with methacryloxy groups at both ends, with a mass average molecular weight (Mw) of 13,000. Manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-22-164E".

[0176] • Energy-line 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"

[0177] As can be seen from Table 1, the adhesive sheets of Examples 1 to 10, which have a surface coating with a static friction coefficient of 0.70 or less, exhibit excellent transportability, and the amount of grinding debris adhering to them can be sufficiently reduced. On the other hand, the adhesive sheet of Comparative Example 1, which has a surface coating with a static friction coefficient of more than 0.70, has poor transportability, and the amount of grinding debris adhering to it is greater than that of the adhesive sheets of Examples 1 to 10.

Claims

1. An adhesive sheet for semiconductor processing, comprising, in sequence, a surface coating, a buffer layer, a substrate, and an adhesive layer, wherein the surface coating has a static friction coefficient of 0.70 or less relative to SUS304, the surface coating is formed from a surface coating forming composition containing a resin component and a lubrication improving component, wherein the resin component has a heteroatom content of 7% by mass or less, and the lubrication improving component has a heteroatom content of 30% by mass or more.

2. The adhesive sheet for semiconductor processing as claimed in claim 1, wherein the content of the aforementioned resin component in the aforementioned surface coating forming composition is 50 to 99% by mass relative to the total amount (100% by mass) of the effective components in the aforementioned surface coating forming composition.

3. The adhesive sheet for semiconductor processing as claimed in claim 1 or 2, wherein the content of the aforementioned slip-improving component in the aforementioned surface coating forming composition is 0.1 to 30% by mass relative to the total amount (100% by mass) of the effective components in the aforementioned surface coating forming composition.

4. The adhesive sheet for semiconductor processing as claimed in claim 1 or 2, wherein the thickness of the aforementioned surface coating is 0.05~10μm.

5. The adhesive sheet for semiconductor processing as claimed in claim 1 or 2, wherein the aforementioned buffer layer is formed from a buffer layer forming composition containing urethane (meth)acrylate.

6. The adhesive sheet for semiconductor processing, as described in claim 1 or 2, is used for back-side grinding of semiconductor wafers.

7. A method for manufacturing a semiconductor device, comprising the following steps: attaching a semiconductor processing adhesive sheet, as claimed in any one of claims 1 to 6, to the surface of a semiconductor wafer using the aforementioned adhesive layer as the attachment surface; and grinding the back side of the semiconductor wafer while the aforementioned surface coating side of the semiconductor processing adhesive sheet attached to the aforementioned semiconductor wafer is fixed by a support device.

8. A method for manufacturing a semiconductor device as claimed in claim 7, comprising the following steps: a step of forming a predetermined dividing line: step a of forming a trench on the surface of a semiconductor wafer, or step b of forming a modified region inside the semiconductor wafer from the surface or back side of the semiconductor wafer; a wafer attaching step: after step a, or before or after step b, using the aforementioned adhesive layer as the attaching surface, attaching a semiconductor processing adhesive wafer as claimed in any one of claims 1 to 6 to the surface of the semiconductor wafer; a grinding and monolithization step: with the surface coating side of the semiconductor processing adhesive wafer attached to the semiconductor wafer fixed by a support device, grinding the back side of the semiconductor wafer, and using the aforementioned trench or modified region as a starting point, monolithizing the semiconductor wafer into a plurality of semiconductor wafers.