Workpiece machining sheet and manufacturing method for the finished workpiece

Abstract

[Problem] To provide a workpiece processing sheet that allows for easy separation of workpieces even after heat treatment. [Solution] A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, wherein the adhesive layer is composed of an active energy-curable adhesive containing a hindered amine stabilizer.

Description

Technical Field

[0001] This invention relates to a workpiece processing wafer suitable for processing workpieces such as semiconductor wafers, and a method for manufacturing a finished workpiece using this workpiece processing wafer. In particular, it relates to a workpiece processing wafer suitable for use in a workpiece processing method that includes a step of heating the workpiece processing wafer in a state where a workpiece has been laminated before or after processing, and a method for manufacturing a finished workpiece using this workpiece processing wafer. Prior Technology

[0002] Generally, a semiconductor device manufacturing method includes a dicing step of individually wafering (dicing) a semiconductor wafer, which serves as a workpiece, on a workpiece processing wafer to obtain a plurality of semiconductor wafers, and a picking step of individually removing (picking up) the plurality of semiconductor wafers from the processing wafer. The aforementioned workpiece processing wafer typically has a substrate and an adhesive layer disposed on one side of the substrate, and the workpiece is deposited on the side of the adhesive layer opposite to the substrate (hereinafter sometimes referred to as the "adhesive surface").

[0003] In recent years, there has been an increasing trend of heat treatment on workpieces, either before or after processing, in a state of lamination on a workpiece processing sheet. For example, treatments such as vapor deposition, sputtering, or baking for dehumidification may be performed on the workpiece on the processing sheet, and heating tests may be conducted to confirm reliability under high-temperature environments. In such heat-assisted processing, problems may occur such as deformation of the workpiece processing sheet due to heating or melting and adhesion between the workpiece processing sheet and the equipment. Therefore, the study examined the application of predetermined heat resistance to workpiece processing sheets supplied for heat-assisted processing.

[0004] As an example of a heat-resistant adhesive sheet, Patent Document 1 discloses a sheet having an adhesive layer (adhesive resin layer) whose gel fraction before and after heating meets predetermined conditions. Furthermore, Patent Document 2 discloses a sheet having an adhesive layer with a specific range of rigidity (the product of nanoindentation modulus and thickness at 25°C). [Previous Technical Documents] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent No. 6546378 [Patent Document 2] Japanese Patent No. 6887766 Summary of the Invention

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

[0007] In addition, when the workpiece processing sheet is subjected to the above-mentioned heat treatment, there is a problem that the adhesion to the workpiece increases, making it difficult to separate the workpiece processing sheet from the workpiece.

[0008] Generally speaking, in workpiece processing sheets, an adhesive layer is formed by curing an adhesive with active energy rays. This adhesive layer is cured by irradiating it with active energy rays, which reduces the adhesion to the workpiece and makes the separation of the workpiece easier.

[0009] Workpiece processing sheets using such active energy ray-curable adhesives can reduce adhesion to the workpiece to a certain extent, even under the aforementioned heat treatment. However, conventional workpiece processing sheets, even when using active energy ray-curable adhesives, could not reduce adhesion sufficiently to allow for easy separation of the heat-treated workpiece.

[0010] The present invention was made in view of the actual situation, and its object is to provide a workpiece processing sheet that allows for easy separation of workpieces even after heat treatment. [Methods used to solve problems]

[0011] To achieve the above objectives, the first embodiment of the present invention provides a workpiece processing sheet, which is a workpiece processing sheet having a substrate and an adhesive layer laminated on one side of the substrate, characterized in that the adhesive layer is composed of an active energy ray curable adhesive containing a hindered amine stabilizer (Invention 1).

[0012] In the workpiece processing sheet of the above-mentioned invention (Invention 1), the adhesive layer is composed of an active energy ray curable adhesive containing a hindered amine stabilizer. Even after heat treatment, the adhesive layer can be well cured by irradiation with active energy rays, thereby significantly reducing the adhesive force. Therefore, the above-mentioned workpiece processing sheet can easily separate the workpiece even after heat treatment.

[0013] In the above invention (Invention 1), it is preferred that the hindered amine stabilizer is an N-alkyl hindered amine stabilizer (Invention 2).

[0014] In the above inventions (Inventions 1 and 2), it is preferred that the above-mentioned active energy ray curable adhesive is formed from an adhesive composition containing an acrylic polymer with active energy ray curable groups introduced into the side chain and the above-mentioned hindered amine stabilizer (Invention 3).

[0015] In the above inventions (Inventions 1 to 3), it is preferred that the workpiece processing sheet is used in a workpiece processing method (Invention 4) which includes the step of heating the workpiece processing sheet while the workpiece before or after processing is deposited on the side opposite to the substrate of the adhesive layer.

[0016] The second embodiment of the present invention provides a method for manufacturing a finished workpiece, characterized by comprising: a bonding step, wherein the workpiece is bonded to the surface opposite to the substrate of the adhesive layer of the workpiece processing sheet (Inventions 1-4); a heating step, wherein the workpiece is subjected to a heating process while bonded to the workpiece processing sheet; and a cutting step, wherein the workpiece subjected to the heating process is cut on the workpiece processing sheet to obtain a finished workpiece (Invention 5) formed by individually sheeting the workpiece. [Invention Benefits]

[0017] The workpiece processing sheet of the present invention can easily separate workpieces even after heat treatment. Simple Explanation of the Diagram

[0018] none Implementation

[0019] [The form in which the invention is carried out]

[0020] The embodiments of the present invention will be described below. The workpiece processing sheet of this embodiment has a substrate and an adhesive layer laminated on one side of the substrate. Furthermore, the adhesive layer is composed of an active energy-curable adhesive containing a hindered amine stabilizer.

[0021] In the workpiece processing sheet of this embodiment, the adhesive layer is composed of an active energy ray curable adhesive, which can be cured by irradiation with active energy rays, thereby reducing the adhesion to the workpiece. Therefore, when it is desired to separate the workpiece processing sheet of this embodiment from the workpiece, it is possible to suppress workpiece damage and prevent a portion of the adhesive constituting the adhesive layer from adhering to the workpiece (residual adhesive), thus enabling easy separation.

[0022] Furthermore, in the workpiece processing sheet of this embodiment, the aforementioned active energy ray curable adhesive contains a hindered amine stabilizer, so that even when the workpiece processing sheet is heated (in particular, even when the workpiece processing sheet is heated while the workpiece is stacked), it can be easily separated from the workpiece as described above by irradiation with active energy rays.

[0023] Previously, it was known that when a workpiece processing sheet was heated while workpieces were stacked, the adhesion to the workpieces would increase, making it difficult to separate the workpieces. Furthermore, the inventors of this invention have confirmed that even if the adhesive layer of the workpiece processing sheet is composed of an active energy ray-curable adhesive, after heat treatment, not only does the adhesion increase, but the curing of the adhesive layer caused by active energy ray irradiation (and the accompanying decrease in adhesion) itself becomes difficult to occur.

[0024] However, in the workpiece processing sheet of this embodiment, even after heat treatment, the adhesive layer cured by irradiation with active energy rays can still be effectively cured (and the accompanying reduction in adhesion). The reasons for this are envisioned below. However, the reasons are not limited to the following, nor are other reasons excluded.

[0025] When an active energy ray-curable adhesive is heated, it is believed that thermal decomposition (including various removal reactions such as depolymerization) and oxidation (including the formation of peroxides) occur in the polymers and additives constituting the adhesive, and furthermore, active free radicals are generated. These active free radicals are believed to cause further polymer decomposition and oxidation, and may lead to modification or deactivation of sites that play an important role in active energy ray curing (especially carbon-carbon double bonds), or thermal polymerization. However, in the workpiece processing sheet of this embodiment, as described above, hindered amine stabilizers and stabilizing free radicals generated in the hindered amine stabilizer system can capture active free radicals and growth ends generated at high temperatures, thereby deactivating them and preventing the aforementioned modification of the active energy ray-curable adhesive.

[0026] In particular, hindered amine stabilizers, after capturing (binding with) free radicals, undergo a reaction that re-cleaves the free radical portion, thus regenerating into hindered amine stabilizers. Therefore, hindered amine stabilizers can continuously exert their stabilizing effect. Furthermore, previously used hindered phenolic compounds do not undergo this regeneration process.

[0027] Furthermore, based on the above-described effects, in the workpiece processing sheet of this embodiment, even when the adhesive layer is cured by irradiation with active energy rays and then subjected to heat treatment, excessive increase in adhesion can be suppressed, and the workpiece can be separated well.

[0028] 1. Substrate The substrate of this embodiment is not particularly limited as long as it performs the desired function when used as a workpiece processing sheet. In particular, it is preferred that the substrate in this embodiment is made of resin. Specific examples of such resins include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin resins such as polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymers, and norbornene resins; ethylene-vinyl acetate copolymers; ethylene-(meth)acrylate copolymers, ethylene-(meth)acrylate copolymers, and other ethylene-(meth)acrylate copolymers; polyvinyl chloride copolymers; (meth)acrylate copolymers; polyurethane; polyimide; polystyrene; polycarbonate; and fluoropolymers. Furthermore, the resin constituting the substrate can be a crosslinked resin of the aforementioned resin, or a modified resin such as an ionomer of the aforementioned resin. Also, in this specification, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the term "polymer" in this specification also includes the concept of "copolymer."

[0029] In this embodiment, the substrate can be a single-layer film formed from the aforementioned resin, or it can be a laminated film formed by stacking multiple such films. In this laminated film, the materials constituting each layer can be of the same type or different types.

[0030] Furthermore, in this embodiment, the substrate may have an oligomer sealing layer on one or both sides of the film formed from the aforementioned resin. The oligomer sealing layer refers to a layer used to suppress the release of low-molecular-weight components (oligomers) contained within the resin to the outside of the substrate when the substrate is heated. Such oligomers include residues of raw materials, solvents, etc., used in the manufacture of the resin, modifiers, decomposition products of the resin itself, residues of solvents used in the manufacture of the substrate, and their reactants. These typically volatilize or diffuse upon heating and are easily released from the substrate to the outside. By providing the oligomer sealing layer, the movement and adhesion of these oligomers towards the adhesive layer, workpiece, device, etc., can be prevented, thus preventing adverse effects caused by the oligomers.

[0031] The aforementioned oligomer sealing layer can be, for example, a cured film formed by curing an oligomer sealing layer composition containing an epoxy compound, a polyester compound, and a polyfunctional amino compound. Furthermore, from the viewpoint of promoting the aforementioned curing reaction, this oligomer sealing layer composition may further contain an acidic catalyst.

[0032] Furthermore, the substrate may also contain various additives such as flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers. The content of these additives is not particularly limited, but is preferably within the range necessary for the substrate to perform its desired function.

[0033] To improve adhesion to the adhesive layer, surface treatments such as primer treatment, corona treatment, and plasma treatment can be applied to the surface of the substrate with the adhesive layer.

[0034] The thickness of the substrate can be appropriately set according to the application method of the workpiece processing sheet. For example, it is preferable to be below 200 μm, especially below 150 μm. Furthermore, the thickness of the substrate is preferably above 10 μm, especially above 25 μm.

[0035] 2. Adhesive layer In this embodiment, the adhesive layer, as described above, is composed of an active energy-curable adhesive containing a hindered amine stabilizer.

[0036] Specific examples of the aforementioned adhesives are not particularly limited, and can include acrylic adhesives, rubber adhesives, silicone adhesives, polyurethane adhesives, polyester adhesives, polyvinyl ether adhesives, etc. However, from the viewpoint that it is easy to form an active energy line curing adhesive and easy to achieve the desired adhesive force, acrylic adhesives are preferred.

[0037] Furthermore, the aforementioned active energy ray-curable adhesive can be a polymer with active energy ray curability as the main component, or it can be a mixture of an active energy ray non-curable polymer (a polymer without active energy ray curability) and monomers and / or oligomers having at least one active energy ray curable group as the main component. Alternatively, the active energy ray-curable adhesive can also be a mixture of a polymer with active energy ray curability and monomers and / or oligomers having at least one active energy ray curable group. From the viewpoint of suppressing the adverse effects of excessive increase in adhesion even after heat treatment, and facilitating good workpiece separation due to low adhesion reduction caused by the use of a triggering agent, the active energy ray-curable adhesive in this embodiment is preferably a polymer with active energy ray curability (especially an acrylic polymer with active energy ray curability) as the main component.

[0038] The aforementioned acrylic polymer with active energy-curable properties is preferably an acrylic polymer (hereinafter sometimes referred to as "active energy-curable polymer (A)") with functional groups (active energy-curable groups) introduced into its side chains. In this case, the active energy-curable adhesive in this embodiment is preferably formed from an adhesive composition containing an acrylic polymer ("active energy-curable polymer (A)") with active energy-curable groups introduced into its side chains and a hindered amine stabilizer.

[0039] (1) Active energy line curable polymer (A) The aforementioned active energy radiation-curable polymer (A) is preferably obtained by reacting an acrylic copolymer (a1) having a functional group monomer unit with an unsaturated group compound (a2) having a functional group bonded to the functional group.

[0040] As the aforementioned functionalized monomer, it is preferred to be a monomer with polymerizable double bonds and functional groups such as hydroxyl, carboxyl, amino, amide, benzyl, glycidyl, etc., which are polymerizable within the molecule. Among them, it is preferred to use a monomer containing hydroxyl as a functional group (hydroxyl-containing monomer).

[0041] Examples of hydroxyl-containing monomers include, for instance, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, with at least one of 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate being preferred. Furthermore, these monomers can be used alone or in combination of two or more.

[0042] Examples of the aforementioned carboxyl-containing monomers include, for instance, vinyl unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These can be used alone or in combination of two or more.

[0043] Examples of the aforementioned amine-containing monomers include, for instance, (meth)acrylate aminoethyl ester and (meth)acrylate n-butylaminoethyl ester. These can be used alone or in combination of two or more.

[0044] The (meth)acrylate polymer (a1) preferably contains 5% by mass or more of structural units derived from the aforementioned functionalized monomers, particularly 10% by mass or more. Furthermore, the (meth)acrylate polymer (a1) preferably contains 40% by mass or less of structural units derived from the aforementioned functionalized monomers, particularly 35% by mass or less. By containing functionalized monomers within the aforementioned range, the desired active energy radiation-curable polymer (A) can be readily formed in the (meth)acrylate polymer (a1).

[0045] From the viewpoint of easily forming an adhesive with the desired properties, it is preferable that the (meth)acrylate polymer (a1) contains an alkyl (meth)acrylate as a monomer unit constituting the (meth)acrylate polymer (a1). As this alkyl (meth)acrylate, it is preferable that the alkyl (meth)acrylate has 1 to 18 carbon atoms, and particularly preferably that the alkyl (meth)acrylate has 1 to 8 carbon atoms.

[0046] Specific examples of the aforementioned alkyl methacrylates include, for instance, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, n-decyl methacrylate, n-dodecyl methacrylate, myristyl acrylate, palmityl methacrylate, stearyl methacrylate, etc. These can be used alone or in combination of two or more. Among the aforementioned alkyl methacrylates, 2-ethylhexyl methacrylate is preferred, and particularly 2-ethylhexyl acrylate is preferred.

[0047] The (meth)acrylate polymer (a1) preferably contains 20% by mass or more of structural units derived from the aforementioned alkyl (meth)acrylate, particularly 40% by mass or more. Furthermore, the (meth)acrylate polymer (a1) preferably contains 95% by mass or less of structural units derived from the aforementioned alkyl (meth)acrylate, particularly 85% by mass or less. By including alkyl (meth)acrylates within the aforementioned range in the (meth)acrylate polymer (a1), the workpiece processing sheet 1 becomes easier to achieve the desired adhesive strength.

[0048] The (meth)acrylate polymer (a1) is preferably free of nitrogen-containing monomers as monomer units constituting the (meth)acrylate polymer (a1). This allows for better retention of the workpiece on the workpiece processing sheet during processing, and makes it easier to suppress excessive increases in adhesion to the workpiece when the workpiece processing sheet is heated. Examples of nitrogen-containing monomers include monomers with amino groups, monomers with amide groups, and monomers with nitrogen-containing heterocycles, with monomers with nitrogen-containing heterocycles being preferred.

[0049] Examples of monomers containing nitrogen-containing heterocycles include, for example, N-(meth)acrylamide morpholine, N-vinyl-2-pyrrolidone, N-(meth)acrylamide pyrrolidone, N-(meth)acrylamide piperidine, N-(meth)acrylamide pyrrolidone, N-(meth)acrylamide aziridine, aziridine ethyl methacrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimazole, N-vinylcarbazole, N-vinylphthalimide, etc., among which N-(meth)acrylamide morpholine is preferred, especially N-acrylamide morpholine.

[0050] The (meth)acrylate polymer (a1) preferably contains 3% by mass or more of structural units derived from the aforementioned nitrogen-containing monomers, particularly 5% by mass or more, and even more 8% by mass or more. Furthermore, the (meth)acrylate polymer (a1) preferably contains 12% by mass or less of structural units derived from the aforementioned nitrogen-containing monomers, particularly 11% by mass or less, and even more 10% by mass or less. By including nitrogen-containing monomers within the aforementioned range in the (meth)acrylate polymer (a1), the workpiece can be held more effectively on the workpiece processing sheet during processing, and excessive increase in adhesion to the workpiece is more easily suppressed when the workpiece processing sheet is heated.

[0051] In addition to the functional monomers, alkyl methacrylates and nitrogen-containing monomers mentioned above, (meth)acrylate polymer (a1) may also contain other monomers as monomer units constituting (meth)acrylate polymer (a1).

[0052] Other monomers mentioned above include, for example, alkoxyalkyl-containing (meth)acrylates such as methoxymethyl methacrylate, methoxyethyl methacrylate, ethoxymethyl methacrylate, and ethoxyethyl methacrylate; (meth)acrylates with aliphatic rings such as cyclohexyl methacrylate; (meth)acrylates with aromatic rings such as phenyl methacrylate; non-crosslinked acrylamides such as methacrylamide and N,N-dimethyl(meth)acrylamide; (meth)acrylates with tertiary amino groups such as N,N-dimethylaminoethyl methacrylate and N,N-dimethylaminopropyl methacrylate; vinyl acetate; and styrene.

[0053] The polymeric form of (meth)acrylate polymer (a1) can be a random copolymer or a block copolymer. Furthermore, there are no particular limitations on the polymerization method; polymerization can be carried out by common polymerization methods, such as solution polymerization.

[0054] By reacting a (meth)acrylic acid copolymer (a1) having the above-mentioned functional group monomer unit with a compound (a2) having an unsaturated group having a functional group bonded to the above functional group, an active energy radiation curable polymer (A) can be obtained.

[0055] The functional groups of the compound containing unsaturated groups (a2) can be appropriately selected based on the type of functional groups of the monomer units containing functional groups in the (meth)acrylic acid copolymer (a1). For example, if the functional group of the (meth)acrylic acid copolymer (a1) is hydroxyl, amino, or carboxyl, then isocyanate, epoxy, or aziridinyl groups are preferred as functional groups in the compound containing unsaturated groups (a2); if the functional group of the (meth)acrylic acid copolymer (a1) is glyoxypropyl, then amino, carboxyl, or aziridinyl groups are preferred as functional groups in the compound containing unsaturated groups (a2).

[0056] Furthermore, in the aforementioned compound (a2) containing unsaturated groups, each molecule contains at least one energy-ray polymerizable carbon-carbon double bond, preferably one to six energy-ray polymerizable carbon-carbon double bonds, and even more preferably one to four energy-ray polymerizable carbon-carbon double bonds. Specific examples of such compounds (a2) containing unsaturated groups include, for instance, 2-methylpropenyloxyethyl isocyanate, 2-propenyloxyethyl isocyanate, 2-(2-methylpropenyloxyethyloxy)ethyl isocyanate, 1,1-(bispropenyloxymethyl)ethyl isocyanate, and meta-isopropenyl-α,α-dimethylbenzyl isocyanate. Isocyanate, methacrylic isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; acrylonitrile monoisocyanate compounds obtained by reacting diisocyanate compounds or polyisocyanate compounds with hydroxyethyl methacrylate; acrylonitrile monoisocyanate compounds obtained by reacting diisocyanate compounds or polyisocyanate compounds, polyol compounds, with hydroxyethyl methacrylate; glycidyl methacrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl methacrylate, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, etc.

[0057] Relative to the mole number of the functionalized monomers in the aforementioned (meth)acrylate polymer (a1), the aforementioned compound containing unsaturated groups (a2) is preferably used at a proportion of 50 moles or more, particularly preferably at a proportion of 60 moles or more, and even more preferably at a proportion of 70 moles or more. Furthermore, relative to the mole number of the functionalized monomers in the aforementioned (meth)acrylate polymer (a1), the aforementioned compound containing unsaturated groups (a2) is preferably used at a proportion of 95 moles or less, particularly preferably at a proportion of 93 moles or less, and even more preferably at a proportion of 90 moles or less.

[0058] In the reaction of (meth)acrylate polymer (a1) with a compound containing unsaturated groups (a2), the reaction temperature, pressure, solvent, time, presence or absence of a catalyst, and type of catalyst can be appropriately selected based on the combination of functional groups possessed by the (meth)acrylate polymer (a1) and the compound containing unsaturated groups (a2). In this way, the functional groups present in the (meth)acrylate polymer (a1) react with the functional groups in the compound containing unsaturated groups (a2), causing the unsaturated groups to be introduced into the side chains of the (meth)acrylate polymer (a1), thereby obtaining an active energy-curable polymer (A).

[0059] The weight-average molecular weight (Mw) of the obtained active energy radiation-curable polymer (A) is preferably 10,000 or more, especially 150,000 or more, and even more preferably 200,000 or more. Furthermore, this weight-average molecular weight (Mw) is preferably 1.5 million or less, especially 1 million or less.

[0060] (2) Hindered amine stabilizers In this specification, the term "hindered amine stabilizer" refers to a stabilizer having one or more amine skeletons in its molecule. In this embodiment, there is no particular limitation as long as the hindered amine stabilizer has such a structure.

[0061] Furthermore, generally speaking, hindered amine stabilizers include N-alkyl-type hindered amine stabilizers, which have one or more alkyl groups bonded to the nitrogen atom of the 2,2,6,6-tetramethylpiperidine skeleton in the molecule, and NH-type hindered amine stabilizers, which have one or more hydrogen atoms bonded to the nitrogen atom of the 2,2,6,6-tetramethylpiperidine skeleton in the molecule. In the workpiece processing sheet of this embodiment, good results can be obtained even if any of these compounds are used. However, from the viewpoint of easily reducing the adhesion to the workpiece after heating and irradiation with active energy rays, it is preferable to use N-alkyl-type hindered amine stabilizers.

[0062] Specific examples of alkyl groups in the above-mentioned N-alkyl type hindered amine stabilizers include methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, n-octyl, etc. Among them, methyl is preferred from the viewpoint that it can easily reduce the adhesion to the workpiece after heating and irradiation by active energy rays.

[0063] Specific examples of hindered amine stabilizers include p,p'-dioctyl diphenylamine, phenyl-α-naphthylamine, poly(2,2,4-trimethyl-1,2-dihydroquinoline), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N,N'-diphenyl-p-phenylenediamine, N,N'-di-β-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N,N'-diallyl-p-phenylenediamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, p,p-toluenesulfonyl diphenylamine, N-phenyl-N'-(3-methacryloxy-2-hydroxypropyl)-p-phenylenediamine, N-( 1-Methylheptyl)-N'-phenyl-p-phenylenediamine, N,N'-di-di-secondary butyl-p-phenylenediamine, N-phenyl-N'-1,3-dimethylbutyl-p-phenylenediamine, alkylated diphenylamine, dimethyl-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate of succinate, poly[[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidinyl)imino]], N,N' -bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-6-chloro-1,3,5 - Triazine condensate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-n-butylmalonic acid bis(1,2,2,6,6-pentamethyl-4-piperidinyl), bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, tetra(1,2,2,6,6-pentamethyl-4-piperidinyl) 1,2,3,4-butanetetracarboxylate, tetra(2,2,6,6-tetramethyl-4-piperidinyl) 1,2,3,4-butanetetracarboxylate, 1,2,3,4-butanetetracarboxylic acid and 1, Mixed esters of 2,2,6,6-pentamethyl-4-piperidinol and 1-tridecyl alcohol, mixed esters of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 1-tridecyl alcohol, mixed esters of 1,2,3,4-butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxellaspiro[5.5]undecane, mixed esters of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxellaspiro[5.5].[5] Mixed esters of undecane, (2,2,6,6-tetramethylene-4-piperidinyl)-2-propylcarbamate, (1,2,2,6,6-pentamethyl-4-piperidinyl)-2-propylcarbamate, etc.

[0064] In the above specific examples, it is preferred to use at least one of tetra(2,2,6,6-tetramethyl-4-piperidinyl)1,2,3,4-butanetetracarboxylate as an N-alkyl hindered amine stabilizer, a mixed ester of 1,2,3,4-butanetetracarboxylic acid as an N-alkyl hindered amine stabilizer, 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, and tetra(1,2,2,6,6-pentamethyl-4-piperidinyl)1,2,3,4-butanetetracarboxylate as an NH-type hindered amine stabilizer.

[0065] Furthermore, the molar mass of the hindered amine stabilizer is preferably 200 g / mol or higher, particularly 600 g / mol or higher, and even more preferably 1000 g / mol or higher. Moreover, this molar mass is preferably 10000 g / mol or lower, particularly 5000 g / mol or lower, and even more preferably 3000 g / mol or lower. By achieving these ranges in the molar mass of the hindered amine stabilizer, it becomes easier to effectively reduce the adhesion to the workpiece after heating and irradiation with active energy rays.

[0066] The content of the hindered amine stabilizer in the above-mentioned adhesive composition is preferably 0.1 parts by weight or more, particularly 0.5 parts by weight or more, and further preferably 1.0 parts by weight or more, relative to 100 parts by weight of the acrylic polymer ("active energy ray curable polymer (A)") with active energy ray curable groups introduced into its side chain. Furthermore, this content is preferably 30 parts by weight or less, particularly 20 parts by weight or less, and further preferably 15 parts by weight or less. By setting the content of the hindered amine stabilizer within these ranges, it becomes easier to effectively reduce the adhesion to the workpiece after heating and irradiation with active energy rays.

[0067] (3) Crosslinking agent The adhesive composition described above preferably contains a crosslinking agent. By including a crosslinking agent in the adhesive composition, the active energy radiation-curable polymer (A) can crosslink in the adhesive layer to form a good three-dimensional network structure. This improves the cohesive strength of the resulting adhesive and effectively suppresses the formation of residual adhesive in the workpiece separated from the workpiece processing sheet after active energy radiation irradiation. Furthermore, when the adhesive composition contains a crosslinking agent, it is preferable that the active energy radiation-curable polymer (A) contains the aforementioned functionalized monomer as a monomer unit constituting the polymer; particularly preferably, the active energy radiation-curable polymer (A) contains a functionalized monomer with a functional group that has a high reactivity with the crosslinking agent used as a monomer unit constituting the polymer.

[0068] Specific examples of the aforementioned crosslinking agents include, for instance, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. These crosslinking agents can be selected based on the functional groups of the monomers containing functional groups derived from acrylic copolymers. Furthermore, these crosslinking agents can be used alone or in combination of two or more.

[0069] Isocyanate-based crosslinking agents include at least polyisocyanate compounds. Examples of polyisocyanate compounds include, for instance, aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and phenylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; as well as their biuret bodies, isocyanurate bodies, and adducts as reaction products with low molecular weight compounds containing active hydrogen, such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, the isocyanurate body of hexamethylene diisocyanate is preferred, especially the isocyanurate-type trimer of 1,6-hexamethylene diisocyanate.

[0070] When the above-mentioned adhesive composition contains a crosslinking agent, the content of the crosslinking agent in the adhesive composition is preferably 0.1 parts by mass or more, particularly 0.5 parts by mass or more, and further preferably 3 parts by mass or more, relative to 100 parts by mass of the active energy ray curable adhesive (A). Furthermore, the above content is preferably 20 parts by mass or less, particularly 5 parts by mass or less. By making the content of the crosslinking agent 0.1 parts by mass or more, the cohesive strength of the adhesive layer after irradiation with active energy rays can be easily improved, thereby effectively suppressing residual adhesive. Furthermore, by making the content of the crosslinking agent 20 parts by mass or less, the degree of crosslinking becomes appropriate, and the adhesive layer easily exhibits the desired adhesive strength.

[0071] (4) Photopolymerization initiator In this embodiment, the adhesive composition preferably contains a photopolymerization initiator. By including a photopolymerization initiator in the adhesive composition, the polymerization and curing period and the amount of light irradiation required for curing the adhesive layer by irradiation with active energy rays can be reduced.

[0072] Specific examples of photopolymerization initiators include diphenyl ketone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin benzoate methyl, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexylphenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzil, dibenzyl, diacetyl, and β-chloroanthraquinone. The photopolymerization initiators include anthraquinone, (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazole-N,N-diethyl dithiocarbamate, oligo(2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]acetone), and 2,2-dimethoxy-1,2-diphenylethane-1-one. Among these, 1-hydroxycyclohexylphenyl ketone is preferred. One of the above photopolymerization initiators can be used alone, or two or more can be used in combination.

[0073] When the above-mentioned adhesive composition contains a photopolymerization initiator, the content of the photopolymerization initiator in the adhesive composition is preferably 0.1 parts by mass or more, and particularly preferably 1 part by mass or more, relative to 100 parts by mass of the active energy line curable polymer (A). Furthermore, the above content is preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less. By making the content of the photopolymerization initiator within the above range, the adhesive layer can be cured with good adhesion efficiency by irradiation with active energy rays, thereby effectively reducing the adhesion of the workpiece sheet to the adhered object.

[0074] (5) Other ingredients The adhesive composition described above may include desired additives, such as silane coupling agents, antistatic agents, tackifiers, antioxidants, softeners, fillers, and refractive index modifiers, without impairing the aforementioned effects of the workpiece processing sheet of this embodiment.

[0075] (6) Method for preparing adhesive composition The adhesive composition in this embodiment can be manufactured by mixing the obtained active energy ray-curable polymer (A), a hindered amine stabilizer, a crosslinking agent as needed, a photopolymerization initiator, and necessary additives. A diluent can be added as needed to obtain a coating liquid of the adhesive composition.

[0076] As diluents, the following can be used: aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and ceroxox solvents such as ethyl ceroxox.

[0077] The concentration and viscosity of the coating solution prepared in this way are not particularly limited as long as they are within the range suitable for coating, and can be appropriately selected according to the situation. For example, the adhesive composition can be diluted to a concentration of 10% by mass or more and 60% by mass or less. Furthermore, the addition of diluents such as solvents is not necessary when obtaining the coating solution; if the viscosity of the adhesive composition is suitable for coating, diluents may not be added. In this case, the adhesive compound P becomes a coating solution in which the polymerization solvent of the acrylic copolymer (a1) is directly used as the diluent.

[0078] (7) Thickness of adhesive layer In this embodiment, the thickness of the adhesive layer is preferably 1 μm or more, particularly 3 μm or more, and further preferably 5 μm or more. By making the adhesive layer thickness 1 μm or more, the workpiece processing wafer can easily achieve good adhesion, and wafer scattering can be easily suppressed. Furthermore, this thickness is preferably 50 μm or less, particularly 30 μm or less, and further preferably 20 μm or less. By making the adhesive layer thickness 50 μm or less, the workpiece can be easily separated.

[0079] 3. Other structures In the workpiece processing sheet of this embodiment, in order to protect the surface (adhesive surface) until the workpiece is attached to the side opposite to the substrate of the adhesive layer, a release sheet can be laminated on this surface.

[0080] The structure of the release sheet is arbitrary, and examples include plastic films that are peeled off using release agents. Specific examples of plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, silicone-based, fluorine-based, long-chain alkyl, and rubber-based agents can be used, with silicone-based agents being preferred due to their low cost and stable performance.

[0081] The thickness of the aforementioned stripping sheet is not particularly limited; for example, it can be above 16 μm or below 250 μm.

[0082] Furthermore, in the workpiece processing sheet of this embodiment, an adhesive layer can be deposited on the side of the adhesive layer opposite to the substrate. In this case, the workpiece processing sheet of this embodiment can be used as a cutting and die bonding sheet. In this sheet, a workpiece is attached to the side of the adhesive layer opposite to the substrate, and the adhesive layer and the workpiece are cut together, thereby obtaining individually wafers with adhesive layers. With these individually wafers, the wafer can be easily fixed to the object on which the wafer is mounted. As the material constituting the adhesive layer, it is preferable to use a material containing thermoplastic resin and low molecular weight thermosetting adhesive components, or a material containing B-stage (semi-cured) thermosetting adhesive components, etc.

[0083] Furthermore, in the workpiece processing sheet of this embodiment, a protective film forming layer may also be deposited on the adhesive surface of the adhesive layer. In this case, the workpiece processing sheet of this embodiment can be used as a sheet for both protective film formation and cutting. In such a sheet, a workpiece is attached to the surface of the protective film forming layer opposite to the adhesive layer, and the protective film forming layer and the workpiece are cut together, thereby obtaining individually wafers with protective film forming layers deposited on them. Preferably, the workpiece is a workpiece with circuits formed on one side, in which case the protective film forming layer is usually deposited on the surface opposite to the surface where the circuits are formed. The individually wafer-sized protective film forming layer, by curing it for a predetermined time, can form a protective film with sufficient durability on the wafer. The protective film forming layer is preferably formed from an uncured curable adhesive.

[0084] 4. Physical properties of workpiece machining sheets The adhesion of the workpiece processing wafer to the silicon wafer (the mirror surface of a mirror-finished silicon wafer, hereinafter the same) before heating and irradiation with active energy rays in this embodiment is preferably 200 mN / 25 mm or more, particularly 800 mN / 25 mm or more, and even more preferably 2000 mN / 25 mm or more. By achieving an adhesion of 200 mN / 25 mm or more, the workpiece can be easily and well fixed to the workpiece processing wafer, and the unexpected workpiece (especially individual wafer-finished workpieces) falling off (especially wafer scattering) can be easily prevented and suppressed. Furthermore, the upper limit of the above-mentioned adhesion is not particularly limited; for example, it is preferably 30000 mN / 25 mm or less, particularly 25000 mN / 25 mm or less, and even more preferably 22000 mN / 25 mm or less.

[0085] Furthermore, in this embodiment, the adhesion of the workpiece processing sheet to the silicon wafer before heating and after irradiation with active energy rays is preferably 1500 mN / 25 mm or less, particularly 600 mN / 25 mm or less, and even more preferably 200 mN / 25 mm or less. In the workpiece processing sheet of this embodiment, since the adhesive layer is composed of an active energy ray-curable adhesive, the adhesion described above can be easily achieved after irradiation with active energy rays. Therefore, by making the adhesion below 1500 mN / 25 mm, the workpiece can be easily separated from the workpiece processing sheet. Furthermore, the adhesion is preferably 10 mN / 25 mm or more, particularly 25 mN / 25 mm or more, and even more preferably 35 mN / 25 mm or more. This makes it easier to suppress workpiece separation and detachment that occurs unexpectedly during the irradiation with active energy rays.

[0086] Furthermore, the adhesion of the workpiece processing wafer of this embodiment to the silicon wafer (the mirror surface of the mirror-finished silicon wafer, hereinafter the same) after heating and before irradiation with active energy rays is preferably 200 mN / 25 mm or more, particularly 800 mN / 25 mm or more, and even more preferably 8000 mN / 25 mm or more. By achieving an adhesion of 200 mN / 25 mm or more, the workpiece can be easily and well fixed to the workpiece processing wafer, and the unexpected workpiece (especially individual wafer-finished workpieces) falling off (especially wafer scattering) can be easily prevented and suppressed. Also, the aforementioned adhesion is preferably 30000 mN / 25 mm or less, particularly 25000 mN / 25 mm or less, and even more preferably 15000 mN / 25 mm or less. By making the aforementioned adhesive force below 30,000 mN / 25mm, the adhesive force after heating and irradiation with active energy rays can be easily adjusted to the range described later.

[0087] Furthermore, in this embodiment, the adhesion of the workpiece processing sheet to the silicon wafer after heating and irradiation with active energy rays is preferably 1500 mN / 25 mm or less, more preferably 1000 mN / 25 mm or less, particularly preferably 600 mN / 25 mm or less, and even more preferably 200 mN / 25 mm or less. In the workpiece processing sheet of this embodiment, since the adhesive layer is composed of an active energy ray-curable adhesive containing a hindered amine stabilizer, the adhesion after irradiation with active energy rays can be easily reduced to the above-mentioned range even after heating. Therefore, by making the adhesion 1500 mN / 25 mm or less, the workpiece can be easily separated from the workpiece processing sheet. Furthermore, the adhesion 10 mN / 25 mm or more is preferred, particularly preferably 25 mN / 25 mm or more, and even more preferably 35 mN / 25 mm or more. This makes it easier to suppress the separation and detachment of workpieces that occur unexpectedly after irradiation with active energy rays.

[0088] Furthermore, the details of the method for measuring adhesion described above are as described in the experimental examples described later.

[0089] 5. Manufacturing method of workpiece machining sheet The manufacturing method of the workpiece processing sheet in this embodiment is not particularly limited, but it is preferred to manufacture it by laminating an adhesive layer on one side of a substrate.

[0090] The adhesive layer can be applied to one side of the substrate using known methods. For example, it is preferable to transfer the adhesive layer formed on the release liner to one side of the substrate. In this case, a coating liquid containing an adhesive composition constituting the adhesive layer and a solvent or dispersion medium added as needed is prepared and applied to the release surface (hereinafter sometimes referred to as the "release surface") of the release liner using a mold coater, curtain coater, sprayer, slot coater, doctor blade coater, sprayer, etc., to form a coating film, and the coating film is dried to form the adhesive layer. The coating liquid is not particularly limited in nature as long as it can be applied. Sometimes it contains components for forming the adhesive layer as a solute, and sometimes it contains components for forming the adhesive layer as a dispersion. The release liner in this laminate can be used as a processing material for peeling, or it can be used to protect the adhesive surface of the adhesive layer before attaching a workpiece processing sheet to the adhered body.

[0091] When the coating liquid used to form the adhesive layer contains a crosslinking agent, by changing the aforementioned drying conditions (temperature, time, etc.) or by using a separately set heat treatment, the crosslinking reaction between the active energy radiation-curable polymer (A) and the crosslinking agent in the coating film can proceed, thereby forming a crosslinked structure with a desired density in the adhesive layer. To ensure that this crosslinking reaction proceeds sufficiently, after the adhesive layer is deposited on the substrate using the above method, the resulting workpiece sheet can be cured, for example, by standing for several days in an environment of 23°C and 50% relative humidity.

[0092] Instead of transferring the adhesive layer formed on the release liner to one side of the substrate as described above, the adhesive layer can be formed directly on the substrate. In this case, the adhesive layer is formed by applying the coating liquid used to form the adhesive layer to one side of the substrate to form a coating film and allowing the coating film to dry.

[0093] 6. How to use the workpiece machining disc The workpiece processing sheet of this embodiment can be appropriately used for processing workpieces such as semiconductor wafers. In this case, after attaching the adhesive surface of the workpiece processing sheet of this embodiment to the workpiece, workpiece processing can be performed on the workpiece processing sheet. According to this processing, the workpiece processing sheet of this embodiment can be used as a back-grinding sheet, a dicing sheet, an extension sheet, a pick-up sheet, etc. Here, specific examples of workpieces can be listed, such as semiconductor components such as semiconductor wafers and semiconductor packages; glass components such as glass plates.

[0094] As described above, the workpiece processing sheet of this embodiment can effectively reduce its adhesion to the workpiece even after heat treatment by irradiation with active energy rays. This allows for easy separation of the workpiece. Therefore, the workpiece processing sheet of this embodiment is particularly suitable for use in workpiece processing methods that include the step of heating the workpiece processing sheet while the workpiece, before or after processing, is deposited on the adhesion surface.

[0095] For example, the workpiece processing sheet of this embodiment is particularly suitable for use in the following method for manufacturing a finished workpiece, which includes: a bonding step, in which a workpiece is bonded to the surface opposite to the substrate of the adhesive layer of the workpiece processing sheet; a heating step, in which the workpiece is subjected to a heating process while bonded to the workpiece processing sheet; and a cutting step, in which the workpiece subjected to the heating process is cut on the workpiece processing sheet to obtain a finished workpiece formed by individually sheeting the workpiece.

[0096] Furthermore, in the above-described method for manufacturing a finished workpiece, the finished workpiece obtained by the cutting step can be appropriately separated from the workpiece processing sheet. For example, the above-described manufacturing method preferably includes an active energy irradiation step of irradiating an adhesive layer in the workpiece processing sheet to which the finished workpiece is attached with active energy rays, thereby hardening the adhesive layer; and a pickup step of picking up the finished workpiece from the workpiece processing sheet having the hardened adhesive layer.

[0097] The bonding step, cutting step, active energy ray irradiation step, and pickup step described above can each be performed using known methods. Furthermore, the heating step described above is not particularly limited; for example, the workpiece can be treated with vapor deposition, sputtering, baking, etc., before or after processing, or a heating test can be conducted to confirm reliability in a high-temperature environment.

[0098] The heating conditions in the above heating step can be appropriately set according to the purpose of heating. For example, the heating temperature is preferably 80°C or higher, especially 100°C or higher, and further preferably 110°C or higher. Furthermore, this temperature is preferably 300°C or lower, especially 270°C or lower, and further preferably 200°C or lower. The heating time is preferably 10 minutes or more, especially 30 minutes or more, or further preferably 120 minutes or more. Furthermore, this time is preferably 25 hours or less, especially 10 hours or less, and further preferably 5 hours or less. As for the heating device, a device suitable for the heating purpose can be used, such as an oven, a heated work surface, etc.

[0099] The embodiments described above are provided for ease of understanding of the present invention and are not intended to limit the invention. Therefore, the elements disclosed in the above embodiments are intended to include all design changes and equivalents that fall within the scope of the present invention.

[0100] For example, other film layers can be provided between the substrate and the adhesive layer, or on the surface of the substrate opposite to the adhesive layer. [Example]

[0101] The invention will be described in more detail below by way of examples, but the scope of the invention is not limited to these examples.

[0102] [Example 1] (1) Fabrication of the substrate 100 parts by weight of bisphenol A type epoxy compound (manufactured by DIC Corporation, product name "EPICLON H-360", weight average molecular weight: 25000), 10.7 parts by weight of polyester compound (manufactured by Toyobo Corporation, product name "VYLON GK680", quantity average molecular weight 6000, glass transfer temperature: 10°C), and 28.5 parts by weight of hexamethoxymethyl melamine (manufactured by Japan Cytec Industries Corporation, product name "CYMEL 303"), which will be used as a polyfunctional amine compound, were mixed in a mixed solvent of toluene and methyl ethyl ketone in a mixing ratio (mass%) of 50:50 to obtain a solution with a solid content concentration of 3%. Furthermore, 1.45 parts by weight of p-toluenesulfonic acid, as an acidic catalyst, were added to this solution and mixed to obtain a coating liquid for an oligomeric sealing layer composition.

[0103] The coating solution of the oligomeric sealing layer composition prepared in step (1) is uniformly coated onto one side of a polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., product name "Lumirror T-60", thickness: 75 μm) using a rod coating method. The resulting coating is then cured in an oven to form a first oligomeric sealing layer with a thickness of 135 nm.

[0104] Furthermore, similarly as described above, a coating liquid of the oligomer sealing layer composition is applied to the side of the PET film opposite to the first oligomer sealing layer, and the resulting coating is cured to form a second oligomer sealing layer with a thickness of 135 nm.

[0105] Through the above operations, a substrate with oligomer sealing layers formed on both sides of the PET film is obtained.

[0106] (2) Preparation of adhesive composition A (meth)acrylate polymer was obtained by solution polymerization of 60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of N-acryloylmorpholine, and 30 parts by mass of 2-hydroxyethyl acrylate. The weight-average molecular weight of this (meth)acrylate polymer was determined by the method described later, and the result was 500,000.

[0107] The obtained (meth)acrylate polymer was reacted with methacryloxyethyl isocyanate (MOI) at a concentration of 90 moles relative to the 2-hydroxyethyl acrylate constituting the (meth)acrylate polymer, to obtain an acrylic polymer with active energy-curable groups introduced into its side chains (active energy-curable polymer). The weight-average molecular weight (Mw) of this active energy-curable polymer was determined by the method described later, and the result was 500,000.

[0108] 100 parts by weight of the obtained active energy line curable polymer, 3.0 parts by weight of 1-hydroxycyclohexylphenyl ketone (manufactured by IGM Resins, product name "Omnirad 184") as a photopolymerization initiator, 4.5 parts by weight of isocyanurate trimer of 1,6-hexamethylene diisocyanate (manufactured by Tosoh, product name "Coronate HX") as a crosslinking agent, and 0.5 parts by weight of tetra(2,2,6,6-tetramethyl-4-piperidinyl)1,2,3,4-butanetetracarboxylate (manufactured by ADEKA, product name "ADK STAB LA-52", N-methyl hindered amine stabilizer) as a hindered amine stabilizer were mixed in a solvent to obtain a coating liquid of adhesive composition (solids concentration 30% by weight).

[0109] (3) Formation of adhesive layer The release surface of a release sheet (manufactured by LINTEC Corporation; product name "SP-PET381031") formed by forming a silicone-based release agent layer on one side of a polyethylene terephthalate film with a thickness of 38 μm is coated with a coating liquid of the adhesive composition obtained in step (2) above, and dried by heating, thereby obtaining a laminate with an adhesive layer of 10 μm thickness formed on the release sheet.

[0110] (4) Fabrication of adhesive sheet After applying corona treatment to one side of the substrate obtained in step (1) above, the corona-treated surface is bonded to the adhesive layer side of the laminate obtained in step (3) above, and then stored in a light-shielding state at 23°C and 50% for 10 days. This yields a sheet for workpiece processing.

[0111] (5) Determination of the weight average molecular weight (Mw) of (meth)acrylate copolymers The weight-average molecular weight (Mw) of the above-mentioned (meth)acrylate copolymer is the weight-average molecular weight converted from polystyrene determined by gel permeation chromatography (GPC) under the following conditions (GPC determination). <Measurement Conditions> GPC measuring device: Tosoh Corporation, HLC-8320 GPC tubing (passing through in the following order): Manufactured by Tosoh Corporation TSK gel super HH TSK gel super HM-H TSK gel super H2000 Determination solvent: tetrahydrofuran Measurement temperature: 40℃

[0112] [Examples 2-7] The content of the crosslinking agent was changed according to Table 1, and the type and content of the hindered amine stabilizer were also changed. Otherwise, the workpiece processing sheet was obtained in the same manner as in Example 1.

[0113] [Comparative Example 1] Without using hindered amine stabilizers, the workpiece processing sheet was obtained in the same manner as in Example 1.

[0114] [Comparative Example 2] Instead of using hindered amine stabilizers, 0.5 parts by weight of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (manufactured by ADEKA Corporation, product name "ADK STAB AO-50"), which is a hindered phenol stabilizer, were used. Otherwise, the workpiece processing sheet was obtained in the same manner as in Example 1.

[0115] [Experimental Example] (Determination of Adhesion) The workpiece processing sheet manufactured in the examples and comparative examples was cut into short strips 25 mm wide. The release sheet was peeled off from the obtained short strips of workpiece processing sheet, and the adhesive surface of the exposed adhesive layer was attached to the mirror surface of the mirror-finished silicon wafer using a 2 kg rubber roller at 23°C and 50% relative humidity, and used as a sample for measurement.

[0116] For the obtained test samples, after being attached to silicon wafers for 20 minutes, the workpiece processing sheet was peeled off using a universal tensile testing machine (Orientec, product name "TENSILON UTM-4-100") at 23°C, a peeling speed of 300 mm / min, and a peeling angle of 180°. The adhesion to the silicon wafer (N / 25mm) was measured using the 180° peeling method according to JIS Z0237:2009. The adhesion obtained here is defined as the adhesion before heating and before UV irradiation (before heating - before UV irradiation). The results are shown in Table 1.

[0117] Furthermore, for the test samples obtained in the same manner as described above, after being attached to the silicon wafer for 20 minutes, they were subjected to ultraviolet (UV) irradiation using a UV irradiation device (manufactured by Lintec Corporation, product name "RAD-2000m / 12") at 23°C and 50% relative humidity (light source: high-pressure mercury lamp, illuminance: 230 mW / cm², light intensity: 190 mJ / cm²). For the test samples after UV irradiation, the workpiece processing sheet was peeled off from the silicon wafer in the same manner as described above, and the adhesion to the silicon wafer (mN / 25mm) was measured. The adhesion obtained thereby is defined as the adhesion before heating and after UV irradiation (before heating - after UV irradiation). The results are shown in Table 1.

[0118] Furthermore, the test sample, obtained in the same manner as described above, was wrapped in aluminum foil and heated in an oven at 170°C for 1 hour. After heating, the test sample was removed from the oven and allowed to cool at room temperature for 5 minutes. The adhesion to the silicon wafer (mN / 25mm) was then measured in the same manner as described above. The adhesion obtained in this way is defined as the adhesion after heating and before UV irradiation (after heating - before UV irradiation). The results are shown in Table 1.

[0119] Furthermore, the test sample obtained in the same manner as described above was wrapped in aluminum foil and heated in an oven at 170°C for 1 hour. After heating, the test sample was removed from the oven and allowed to cool at room temperature for 5 minutes before being subjected to ultraviolet irradiation under the same conditions as described above. For the test sample after ultraviolet irradiation, the adhesion force (mN / 25mm) to the silicon wafer was measured by peeling the workpiece processing sheet from the silicon wafer in the same manner as described above. The adhesion force obtained thereby is defined as the adhesion force after heating and after UV irradiation (after heating - after UV irradiation). The results are shown in Table 1.

[0120] Furthermore, the details of the abbreviations, etc., recorded in Table 1 are as follows. LA-52: Tetramethyl-4-piperidinyl)1,2,3,4-butanetetracarboxylate (manufactured by ADEKA, product name "ADK STAB LA-52", N-methyl hindered amine stabilizer) LA-63P: A mixed esterification of 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol, and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (manufactured by ADEKA, product name "ADK STAB LA-63P", N-methyl hindered amine stabilizer) LA-57: Tetra(1,2,2,6,6-pentamethyl-4-piperidinyl)1,2,3,4-butanetetracarboxylate (manufactured by ADEKA, product name "ADK STAB LA-57", NH-type hindered amine stabilizer) AO-50: Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (manufactured by ADEKA, product name "ADK STAB AO-50")

[0121] Table 1 Crosslinking agent content (parts by weight) Hindered amine system Stabilizer Hindered phenolic stabilizers Adhesion (mN / 25mm) type content (parts by weight) type content (parts by weight) Before heating - before UV Before heating - after UV After heating - before UV After heating - after UV Example 1 4.5 LA-52 0.5 - - 4800 30 11200 590 Example 2 4.5 LA-63P 0.5 - - 4500 30 9200 160 Example 3 1.5 LA-63P 1 - - 7500 40 10500 260 Example 4 0.9 LA-63P 1 - - 9400 40 12000 270 Example 5 0.9 LA-63P 5 - - 9500 40 11000 110 Example 6 0.9 LA-63P 10 - - 9800 40 11000 100 Example 7 4.5 LA-57 0.5 - - 4600 40 10650 1100 Comparative Example 1 4.5 - - - - 4500 40 11400 5650 Comparative Example 2 4.5 - - AO-50 0.5 4400 30 10700 4600

[0122] As shown in Table 1, the workpiece processing sheets of the embodiments can effectively reduce adhesion by ultraviolet irradiation without heating. Furthermore, even when heated, the adhesion can be sufficiently reduced by ultraviolet irradiation. On the other hand, the workpiece processing sheets of Comparative Example 1 (which did not use hindered amine stabilizers) and Comparative Example 2 (which used hindered phenol stabilizers instead of hindered amine stabilizers) can reduce adhesion by ultraviolet irradiation in the same manner as the embodiments without heating. However, when heated, even with ultraviolet irradiation, the adhesion cannot be sufficiently reduced. [Industrial applicability]

[0123] The workpiece processing wafer of the present invention is suitable for processing workpieces such as semiconductor wafers, and in particular, it is suitable for processing methods of workpieces that include the step of heating the workpiece processing wafer in a state of stacking workpieces before or after processing.

[0124] none

Claims

1. A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, characterized in that the adhesive layer is composed of an active energy radiation curable adhesive containing a hindered amine stabilizer, wherein the active energy radiation curable adhesive is formed of an adhesive composition comprising an acrylic polymer having active energy radiation curable groups introduced into its side chains and the hindered amine stabilizer.

2. A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, characterized in that the adhesive layer is composed of an active energy ray curable adhesive containing a hindered amine stabilizer, and the workpiece processing sheet can be cured by irradiation with active energy rays, thereby reducing the adhesion to the workpiece.

3. For the workpiece processing sheet as requested in item 1 or 2, wherein the hindered amine stabilizer is an N-alkyl hindered amine stabilizer.

4. The workpiece processing sheet as claimed in claim 1 or 2, wherein the workpiece processing sheet is used in a workpiece processing method comprising the step of heating the workpiece processing sheet while the workpiece before or after processing is deposited on the side opposite to the substrate of the adhesive layer.

5. A method for manufacturing a finished workpiece, characterized by comprising: a bonding step, wherein the workpiece is bonded to the surface opposite to the substrate of the adhesive layer of a workpiece processing sheet as claimed in claim 1 or 2; a heating step, wherein the workpiece is subjected to a heating process while bonded to the workpiece processing sheet; and a cutting step, wherein the workpiece subjected to the heating process is cut on the workpiece processing sheet to obtain a finished workpiece formed by individually sheeting the workpiece.