Adhesive composition, adhesive tape, method for processing semiconductor wafer, and method for manufacturing semiconductor device

Abstract

The purpose of the present invention is to provide a pressure-sensitive adhesive composition which is capable of achieving both excellent embedding properties in unevenness and excellent peeling properties. Another purpose of the present invention is to provide an adhesive tape having an adhesive layer containing the adhesive composition. The purpose of the present invention is also to provide a method for processing a semiconductor wafer and a method for manufacturing a semiconductor device using the adhesive tape. The present invention relates to an adhesive composition containing a (meth) acrylic copolymer, the (meth) acrylic copolymer containing a structural unit derived from n-heptyl (meth) acrylate, and the (meth) acrylic copolymer having a carbon-carbon double bond in a side chain.

Description

Technical Field

[0001] The present invention relates to an adhesive composition. Further, the present invention relates to an adhesive tape having an adhesive layer containing the adhesive composition. Furthermore, the present invention relates to a method for processing a semiconductor wafer and a method for manufacturing a semiconductor device using the adhesive tape. Background Art

[0002] Conventionally, when fixing components in electronic components, vehicles, houses, and building materials, an adhesive tape having an adhesive layer containing an adhesive composition has been widely used (for example, Patent Documents 1 to 3). Specifically, for example, an adhesive tape is used to bond a cover plate for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to bond a touch panel module and a display panel module.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-052050

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2015-021067

[0007] Patent Document 3: Japanese Patent Application Laid-Open No. 2015-120876 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] Conventionally, as an adhesive composition having excellent adhesive strength, an acrylic adhesive containing a (meth)acrylic copolymer has been widely used. As the acrylic monomer constituting the (meth)acrylic copolymer, for example, (meth)acrylic acid alkyl esters such as butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate can be used.

[0010] For an adhesive composition and an adhesive tape used for temporarily fixing electronic components such as semiconductors, since there are uneven surfaces on the surface of a temporarily fixed bump wafer or the like, excellent embedding property for unevenness is required. In addition, at the same time, it is necessary to be able to peel from the temporarily fixed electronic component while suppressing the generation of residual glue (residue), and thus excellent peeling performance is also required.

[0011] However, when using an acrylic adhesive containing a (meth)acrylic copolymer, where the (meth)acrylic copolymer uses butyl (meth)acrylate as the main component of the raw material, the embedding property for unevenness is insufficient. On the other hand, when using an acrylic adhesive containing a (meth)acrylic copolymer, where the (meth)acrylic copolymer uses 2-ethylhexyl (meth)acrylate as the main component of the raw material, although the embedding property for unevenness is excellent, there are problems such as being easily torn during peeling and being prone to residual glue in the temporarily fixed electronic components.

[0012] An object of the present invention is to provide an adhesive composition capable of achieving both excellent embedding property for unevenness and excellent peeling performance. In addition, an object of the present invention is to provide an adhesive tape having an adhesive layer containing the adhesive composition. Furthermore, an object of the present invention is to provide a method for processing a semiconductor wafer and a method for manufacturing a semiconductor device using the adhesive tape.

[0013] Means for solving the problems

[0014] The present disclosure 1 relates to an adhesive composition containing a (meth)acrylic copolymer, the (meth)acrylic copolymer including a structural unit derived from n-heptyl (meth)acrylate, and the (meth)acrylic copolymer having a carbon-carbon double bond in the side chain.

[0015] The present disclosure 2 relates to the adhesive composition of the present disclosure 1, wherein the content ratio of the structural unit derived from n-heptyl (meth)acrylate in the (meth)acrylic copolymer is 15% by mass or more.

[0016] The present disclosure 3 relates to the adhesive composition of the present disclosure 1 or 2, wherein the carbon-carbon double bond equivalent of the (meth)acrylic copolymer is 0.05 meq / g or more.

[0017] The present disclosure 4 relates to the adhesive composition of the present disclosure 1, 2 or 3, wherein the (meth)acrylic copolymer includes a structural unit derived from a monomer containing a polar functional group.

[0018] The present disclosure 5 relates to the adhesive composition of the present disclosure 4, wherein the total content ratio of the structural units derived from the monomers containing a polar functional group in the (meth)acrylic copolymer is 0.01% by mass or more and 30% by mass or less.

[0019] The present disclosure 6 relates to the adhesive composition of the present disclosure 4 or 5, wherein the acid value of the (meth)acrylic copolymer is 10 mgKOH / g or less.

[0020] The present disclosure 7 relates to the adhesive composition of the present disclosure 4, 5 or 6, wherein the hydroxyl value of the above-mentioned (meth)acrylic copolymer is 5 mgKOH / g or more and 100 mgKOH / g or less.

[0021] The present disclosure 8 relates to the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6 or 7, wherein the weight average molecular weight of the above-mentioned (meth)acrylic copolymer is 200,000 or more and 2,000,000 or less.

[0022] The present disclosure 9 relates to the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7 or 8, which further contains a photoinitiator.

[0023] The present disclosure 10 relates to the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8 or 9, which further contains an inorganic filler.

[0024] The present disclosure 11 relates to the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, which further contains a polyfunctional oligomer or a polyfunctional monomer.

[0025] The present disclosure 12 relates to the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, which further contains a gas generating agent.

[0026] The present disclosure 13 relates to the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, which further contains a tackifier.

[0027] The present disclosure 14 relates to an adhesive tape, which has an adhesive layer containing the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13.

[0028] The present disclosure 15 relates to the adhesive tape of the present disclosure 14, wherein the content rate of bio-derived carbon in the above-mentioned adhesive layer is 10% or more.

[0029] The present disclosure 16 relates to the adhesive tape of the present disclosure 14 or 15, wherein the gel fraction of the above-mentioned adhesive layer is 10 mass% or more and 90 mass% or less, and the gel fraction of the adhesive layer after heating at 150 °C for 1 hour or the gel fraction after irradiating light with any wavelength in the range of 280 nm or more and 405 nm or less so that the cumulative light amount reaches 1000 mJ / cm 2 above is 90 mass% or more.

[0030] The present disclosure 17 relates to the adhesive tape of the present disclosure 14, 15 or 16, wherein the shear storage modulus of the above-mentioned adhesive layer at 23 °C is 1.2×10 5less than Pa, the tensile storage modulus at 23°C after heating the above adhesive layer at 150°C for 1 hour or the tensile storage modulus at 23°C after irradiating light with an arbitrary wavelength in the range of 280 nm or more and 405 nm or less in such a manner that the cumulative light amount reaches 1000 mJ / cm 2 or more is 1.0×10 6 Pa or more.

[0031] The adhesive tape of the present disclosure 18 relates to the adhesive tape of the present disclosure 14, 15, 16 or 17, and its 180° peel strength against SUS is 0.3 N / 25 mm or more. The 180° peel strength against SUS after heating the adhesive tape at 150°C for 1 hour or irradiating light with an arbitrary wavelength in the range of 280 nm or more and 405 nm or less in such a manner that the cumulative light amount reaches 1000 mJ / cm 2 or more is 0.3 N / 25 mm or less.

[0032] The adhesive tape of the present disclosure 19 relates to the adhesive tape of the present disclosure 14, 15, 16, 17 or 18, and is used for temporary fixation of a semiconductor wafer.

[0033] The present disclosure 20 relates to a method for processing a semiconductor wafer, which has the following steps: temporarily fixing the semiconductor wafer to a support using the adhesive tape of the present disclosure 19, and peeling off the adhesive tape after curing the above adhesive layer by light or heat.

[0034] The present disclosure 21 relates to a method for manufacturing a semiconductor device, which has the following steps: temporarily fixing the semiconductor wafer to a support using the adhesive tape of the present disclosure 19, and peeling off the adhesive tape after curing the above adhesive layer by light or heat.

[0035] Hereinafter, the present invention will be described in detail.

[0036] The present inventors have found that in an adhesive composition containing a (meth)acrylic copolymer, by using a (meth)acrylic copolymer containing a structural unit derived from n-heptyl (meth)acrylate as the (meth)acrylic copolymer, the embedding property and peeling performance of the adhesive composition against unevenness are improved. In addition, the present inventors have focused on the fact that the adhesive strength of the adhesive composition is significantly reduced and the peeling performance is improved by curing the (meth)acrylic copolymer, and have studied: by introducing a carbon-carbon double bond into the side chain of the (meth)acrylic copolymer containing a structural unit derived from n-heptyl (meth)acrylate, the (meth)acrylic copolymer can be made into a structure that can be cured by light irradiation, heating, etc., and further improve the peeling performance of the adhesive composition.

[0037] As a result, it was found that an adhesive composition capable of achieving excellent embedding properties for unevenness and excellent peeling properties could be obtained, and thus the present invention was completed.

[0038] The adhesive composition of the present invention contains a (meth)acrylic copolymer.

[0039] The above (meth)acrylic copolymer contains a structural unit derived from n-heptyl (meth)acrylate.

[0040] n-Heptyl (meth)acrylate can lower the glass transition temperature (Tg) of the polymer and improve flexibility. Therefore, by making the above (meth)acrylic copolymer contain a structural unit derived from n-heptyl (meth)acrylate, the adhesive composition of the present invention has excellent embedding properties for unevenness, can suppress the generation of residual glue, and is easily peeled from the uneven surface, and has excellent peeling properties.

[0041] It should be noted that in this specification, "(meth)acrylic acid" means acrylic acid or methacrylic acid, and "(meth)acrylate" means acrylate or methacrylate.

[0042] In recent years, the depletion of oil resources and the emission of carbon dioxide caused by the combustion of oil-derived products have been regarded as problems. Therefore, attempts have been made to save oil resources by using bio-derived materials instead of oil-derived materials.

[0043] Therefore, the above n-heptyl (meth)acrylate preferably contains bio-based carbon. By making the above n-heptyl (meth)acrylate contain bio-based carbon, the content rate of bio-based carbon in the adhesive layer containing the adhesive composition of the present invention described later is increased, and the environmental load caused by the adhesive tape having the adhesive layer can be further reduced.

[0044] It should be noted that in this specification, "containing bio-based carbon" means that the bio-based carbon content rate of the compound measured by ASTM D6866-22 is 1% or more.

[0045] When the n-heptyl (meth)acrylate in the above structural unit derived from n-heptyl (meth)acrylate contains bio-based carbon, the n-heptyl (meth)acrylate is preferably synthesized by the esterification of n-heptanol as a bio-derived material and (meth)acrylic acid. In addition, it is also preferably synthesized by the transesterification reaction of the above n-heptanol as a bio-derived material and (meth)acrylate.

[0046] The above n-heptanol as a bio-derived material can be obtained inexpensively and easily, for example, by cracking a material collected from animals and plants (for example, ricinoleic acid derived from castor oil) as a raw material.

[0047] The preferred lower limit of the content ratio of the structural unit derived from n-heptyl (meth)acrylate in the above-mentioned (meth)acrylic acid copolymer is 15% by mass. By making the content ratio of the structural unit derived from n-heptyl (meth)acrylate 15% by mass or more, the softness of the adhesive composition of the present invention is improved, so the embedding property for unevenness is more excellent, and the generation of residual glue can be suppressed and it can be more easily peeled off from the uneven surface. In addition, by making the content ratio of the structural unit derived from n-heptyl (meth)acrylate containing bio-based carbon 15% by mass or more, the content rate of bio-based carbon in the adhesive layer of the adhesive tape described later can be further increased. The more preferred lower limit of the content ratio of the structural unit derived from n-heptyl (meth)acrylate is 35% by mass, and the further preferred lower limit is 50% by mass.

[0048] In addition, the upper limit of the content ratio of the structural unit derived from n-heptyl (meth)acrylate is not particularly limited. The above-mentioned (meth)acrylic acid copolymer preferably contains a structural unit derived from a monomer containing a polar functional group, a structural unit derived from an unsaturated compound containing a functional group, etc. described later. Therefore, the preferred upper limit is 98% by mass. The more preferred upper limit of the content ratio of the structural unit derived from n-heptyl (meth)acrylate is 95% by mass, and the further preferred upper limit is 90% by mass.

[0049] The above-mentioned (meth)acrylic acid copolymer has a carbon-carbon double bond in the side chain.

[0050] By making the above-mentioned (meth)acrylic acid copolymer have a carbon-carbon double bond in the side chain, the adhesive strength of the adhesive composition of the present invention can be greatly reduced through curing based on heating, light irradiation, etc., and when peeling the adhesive composition of the present invention, it can be easily peeled off. Therefore, the peeling performance of the adhesive composition of the present invention is excellent.

[0051] It should be noted that in this specification, the "side chain" refers to the branched structural part extending from the main chain when the longest chain in the above-mentioned (meth)acrylic acid copolymer is used as the main chain.

[0052] In addition, in this specification, the "carbon-carbon double bond" does not include the carbon-carbon double bond constituting the aromatic ring.

[0053] As a method for introducing a carbon-carbon double bond into the side chain of the above-mentioned (meth)acrylic acid copolymer, for example, a method of reacting a (meth)acrylic acid polymer without a carbon-carbon double bond obtained by copolymerizing the above-mentioned n-heptyl (meth)acrylate, a monomer containing a polar functional group described later, and other monomers described later with a compound having a functional group capable of reacting with a carboxyl group, a hydroxyl group, etc. in the polymer and a carbon-carbon double bond (hereinafter, also referred to as "unsaturated compound containing a functional group").

[0054] As the unsaturated compound containing a functional group, for example, according to the functional group in the above-mentioned (meth)acrylic polymer without an introduced carbon-carbon double bond, the same compounds as the monomers containing a polar functional group described later can be cited. For example, when the functional group in the above-mentioned (meth)acrylic polymer without an introduced carbon-carbon double bond is a carboxyl group, monomers containing an epoxy group, monomers containing an isocyanate group, etc. can be used. When the functional group in the above-mentioned (meth)acrylic polymer without an introduced carbon-carbon double bond is a hydroxyl group, monomers containing an isocyanate group, etc. can be used. When the functional group in the above-mentioned (meth)acrylic polymer without an introduced carbon-carbon double bond is an epoxy group, monomers containing a carboxyl group, monomers containing an amide group such as acrylamide, etc. can be used. When the functional group in the above-mentioned (meth)acrylic polymer without an introduced carbon-carbon double bond is an amino group, monomers containing an epoxy group can be used.

[0055] In addition, as the unsaturated compound containing a functional group, specifically, for example, 2-methacryloyloxyethyl isocyanate (MOI), 2-acryloyloxyethyl isocyanate (AOI), 1,1-(bisacryloxymethyl)ethyl isocyanate (BEI), etc. can also be cited.

[0056] The preferable lower limit of the content ratio of the structural unit derived from the unsaturated compound containing a functional group in the above-mentioned (meth)acrylic copolymer is 0.1% by mass, and the preferable upper limit is 25% by mass. By making the content ratio of the structural unit derived from the unsaturated compound containing a functional group 0.1% by mass or more, the adhesive composition of the present invention can be sufficiently cured when cured, and thus the peeling performance of the adhesive composition of the present invention is more excellent. By making the content ratio of the structural unit derived from the unsaturated compound containing a functional group 25% by mass or less, the adhesive composition of the present invention can maintain appropriate softness even after curing, can suppress the generation of residual glue, and is more easily peeled from the uneven surface. The more preferable lower limit of the content ratio of the structural unit derived from the unsaturated compound containing a functional group is 0.5% by mass, and the more preferable upper limit is 20% by mass.

[0057] The above-mentioned (meth)acrylic copolymer preferably further contains a structural unit derived from a monomer containing a polar functional group. By including a structural unit derived from a monomer containing a polar functional group in the above-mentioned (meth)acrylic copolymer, the cohesion of the adhesive composition of the present invention becomes greater, the generation of residual glue can be suppressed, and it can be more easily peeled off from the uneven surface. In addition, when the adhesive composition of the present invention contains a crosslinking agent described later, during peeling, the functional group from the structural unit derived from the monomer containing a polar functional group reacts with the crosslinking agent by irradiation with light, heating, etc., thereby reducing the adhesive force of the adhesive composition of the present invention, and the peeling performance of the adhesive composition of the present invention is more excellent.

[0058] Examples of the structural unit derived from the monomer containing a polar functional group include: a structural unit derived from a monomer containing a carboxyl group, a structural unit derived from a monomer containing a hydroxyl group, a structural unit derived from a monomer containing an epoxy group, a structural unit derived from a monomer containing an isocyanate group, a structural unit derived from a monomer containing an amino group, etc. Among them, from the viewpoint of further improving the cohesion of the adhesive composition, the above-mentioned (meth)acrylic copolymer preferably contains at least one selected from the structural unit derived from a monomer containing a carboxyl group and the structural unit derived from a monomer containing a hydroxyl group.

[0059] Examples of the above-mentioned monomer containing a carboxyl group include acrylic acid, methacrylic acid, etc.

[0060] Examples of the above-mentioned monomer containing a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, etc.

[0061] Examples of the above-mentioned monomer containing an epoxy group include glycidyl acrylate, glycidyl methacrylate, etc.

[0062] Examples of the above-mentioned monomer containing an isocyanate group include 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, etc.

[0063] Examples of the above-mentioned monomer containing an amino group include 2-aminoethyl acrylate, 2-aminoethyl methacrylate, etc.

[0064] The lower limit of the total content ratio of the structural units derived from the monomers containing polar functional groups in the above-mentioned (meth)acrylic copolymer is preferably 0.01% by mass, and the upper limit is preferably 30% by mass. By making the total content ratio of the structural units derived from the monomers containing polar functional groups 0.01% by mass or more, the cohesive force of the adhesive composition of the present invention becomes greater, the generation of residual glue can be suppressed, and it can be more easily peeled off from the uneven surface. In addition, when the adhesive composition of the present invention contains a crosslinking agent described later, at the time of peeling, by reacting the functional groups from the structural units derived from the monomers containing polar functional groups with the crosslinking agent by irradiation with light, heating, etc., the adhesive force of the adhesive composition of the present invention can be reduced, and the peeling performance of the adhesive composition of the present invention is more excellent. By making the total content ratio of the structural units derived from the monomers containing polar functional groups 30% by mass or less, the adhesive composition of the present invention does not become too hard, has more excellent embedding property for unevenness, and has sufficient initial adhesive force. The more preferable lower limit of the total content ratio of the structural units derived from the monomers containing polar functional groups is 0.1% by mass, the more preferable upper limit is 28% by mass, the further preferable lower limit is 1% by mass, and the further preferable upper limit is 25% by mass.

[0065] It should be noted that the above-mentioned monomers containing polar functional groups can be used alone or in combination of two or more.

[0066] The above-mentioned (meth)acrylic copolymer may contain structural units derived from other monomers in addition to the structural units derived from n-heptyl (meth)acrylate and the structural units derived from the monomers containing polar functional groups.

[0067] Examples of the above-mentioned other monomers include (meth)acrylic acid alkyl esters other than the above-mentioned n-heptyl (meth)acrylate.

[0068] Examples of the above-mentioned (meth)acrylic acid alkyl esters include: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, the ester of 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)-1-octanol and (meth)acrylic acid, the ester of an alcohol having 1 or 2 methyl groups on the straight-chain main chain and having 18 carbon atoms in total and (meth)acrylic acid, docosyl (meth)acrylate, eicosyl (meth)acrylate, etc.

[0069] It should be noted that these alkyl (meth)acrylates can be used alone or in combination of two or more.

[0070] In addition, as the above-mentioned other monomers, for example, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, polypropylene glycol mono(meth)acrylate, etc. can also be cited. In addition, as the above-mentioned other monomers, for example, vinyl carboxylates such as vinyl acetate and various monomers used in conventional acrylic polymers such as styrene can also be used.

[0071] It should be noted that these other monomers can be used alone or in combination of two or more.

[0072] As a method for producing the above-mentioned (meth)acrylic copolymer, for example, a method can be cited in which a monomer mixture containing the above-mentioned n-heptyl (meth)acrylate and the above-mentioned monomer containing a polar functional group is subjected to a radical reaction in the presence of a polymerization initiator and copolymerized, and then the obtained (meth)acrylic polymer not introduced with a carbon-carbon double bond is reacted with an unsaturated compound containing a functional group.

[0073] As a method for subjecting the above-mentioned monomer mixture to a radical reaction, that is, a polymerization method, a conventionally well-known method can be used. For example, solution polymerization (boiling point polymerization or isothermal polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, etc. can be cited.

[0074] As a polymerization initiator for producing the above-mentioned (meth)acrylic copolymer, for example, organic peroxides, azo compounds, etc. can be cited.

[0075] As the above-mentioned organic peroxides, for example, 1,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane, tert-hexyl perpivalate, tert-butyl perpivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, tert-hexyl 2-ethylhexanoate peroxide, tert-butyl 2-ethylhexanoate peroxide, tert-butyl peroxyisobutyrate, tert-butyl 3,5,5-trimethylhexanoate peroxide, tert-butyl laurate peroxide, etc. can be cited.

[0076] As the above-mentioned azo compounds, for example, azobisisobutyronitrile, azodicyclohexanecarbonitrile, etc. can be cited.

[0077] It should be noted that these polymerization initiators can be used alone or in combination of two or more.

[0078] Further, in the case where the above-mentioned free radical reaction is living radical polymerization, examples of the above-mentioned polymerization initiator include organotellurium polymerization initiators. The above-mentioned organotellurium polymerization initiator is not particularly limited as long as it is an organotellurium polymerization initiator commonly used in living radical polymerization, and examples thereof include organotellurium compounds and organotellurium halide compounds. It should be noted that in living radical polymerization, in addition to the above-mentioned organotellurium polymerization initiator, for the purpose of accelerating the polymerization rate, the above-mentioned azo compound can also be used as a polymerization initiator for producing the above-mentioned (meth)acrylic copolymer.

[0079] The preferred lower limit of the carbon-carbon double bond equivalent of the above-mentioned (meth)acrylic copolymer is 0.05 meq / g. By making the carbon-carbon double bond equivalent of the above-mentioned (meth)acrylic copolymer 0.05 meq / g or more, the peelability of the adhesive composition of the present invention is more excellent. The more preferred lower limit of the carbon-carbon double bond equivalent of the above-mentioned (meth)acrylic copolymer is 0.06 meq / g, and the further preferred lower limit is 0.075 meq / g.

[0080] The preferred upper limit of the carbon-carbon double bond equivalent of the above-mentioned (meth)acrylic copolymer is 3.5 meq / g. By making the carbon-carbon double bond equivalent of the above-mentioned (meth)acrylic copolymer 3.5 meq / g or less, the adhesive composition of the present invention can maintain appropriate softness after curing, can inhibit the generation of residual glue, and is more easily peeled from the uneven surface. The more preferred upper limit of the carbon-carbon double bond equivalent of the above-mentioned (meth)acrylic copolymer is 2.0 meq / g.

[0081] It should be noted that in this specification, the "carbon-carbon double bond equivalent of the (meth)acrylic copolymer" refers to the milliequivalent (meq / g) of the carbon-carbon double bond per 1 g of the (meth)acrylic copolymer.

[0082] The preferred upper limit of the acid value of the above-mentioned (meth)acrylic copolymer is 10 mgKOH / g. By making the acid value of the above-mentioned (meth)acrylic copolymer 10 mgKOH / g or less, the adhesive composition of the present invention will not become too hard, has better embedding property for unevenness, and has sufficient initial adhesiveness. The more preferred upper limit of the acid value of the above-mentioned (meth)acrylic copolymer is 9 mgKOH / g, and the further preferred upper limit is 8 mgKOH / g.

[0083] In addition, the lower limit of the acid value of the above-mentioned (meth)acrylic copolymer is not particularly limited and can be 0 mgKOH / g.

[0084] It should be noted that the acid value is an index indicating the content of carboxyl groups in a certain amount of sample. The hydroxyl value of the above-mentioned (meth)acrylic copolymer is the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of the above-mentioned (meth)acrylic copolymer, and can be calculated by measurement based on the potentiometric titration method specified in JIS K 0070:1992.

[0085] The preferred lower limit of the hydroxyl value of the above-mentioned (meth)acrylic copolymer is 5 mgKOH / g, and the preferred upper limit is 100 mgKOH / g. By making the hydroxyl value of the above-mentioned (meth)acrylic copolymer 5 mgKOH / g or more, the cohesion of the adhesive composition of the present invention becomes greater, so that the generation of residual glue can be suppressed and it can be easily peeled off from the uneven surface. In addition, when the adhesive composition of the present invention contains a crosslinking agent described later, at the time of peeling, by reacting the functional group derived from the structural unit of the monomer containing a polar functional group with the crosslinking agent by irradiation with light, heating, etc., the adhesive strength of the adhesive composition of the present invention can be reduced, and the peeling performance of the adhesive composition of the present invention is more excellent. By making the hydroxyl value of the above-mentioned (meth)acrylic copolymer 100 mgKOH / g or less, the adhesive composition of the present invention does not become too hard, has more excellent embedability into unevenness, and has sufficient initial adhesive strength. The more preferred lower limit of the hydroxyl value of the above-mentioned (meth)acrylic copolymer is 7 mgKOH / g, the more preferred upper limit is 95 mgKOH / g, the further preferred lower limit is 9 mgKOH / g, and the further preferred upper limit is 90 mgKOH / g.

[0086] It should be noted that the hydroxyl value is an index indicating the content of hydroxy groups in a certain amount of sample. The hydroxyl value of the above-mentioned (meth)acrylic copolymer is the number of milligrams of potassium hydroxide required to neutralize acetic acid bonded to the hydroxyl group after acetylating 1 g of the above-mentioned (meth)acrylic copolymer, and can be calculated by measurement based on the potentiometric titration method specified in JIS K 0070:1992.

[0087] The preferred lower limit of the weight-average molecular weight (Mw) of the above-mentioned (meth)acrylic copolymer is 200,000, and the preferred upper limit is 2,000,000. By making the weight-average molecular weight (Mw) of the above-mentioned (meth)acrylic copolymer 200,000 or more, the adhesive composition of the present invention has sufficient initial adhesiveness. By making the weight-average molecular weight (Mw) of the above-mentioned (meth)acrylic copolymer 2,000,000 or less, the adhesive composition of the present invention does not become too hard, has better embedding property for unevenness, and has sufficient initial adhesiveness. The more preferred lower limit of the weight-average molecular weight (Mw) of the above-mentioned (meth)acrylic copolymer is 250,000, the more preferred upper limit is 1,800,000, the further preferred lower limit is 300,000, and the further preferred upper limit is 1,500,000.

[0088] It should be noted that the weight-average molecular weight of the above-mentioned (meth)acrylic copolymer can be determined, for example, by conversion with standard polystyrene by GPC (Gel Permeation Chromatography) method. More specifically, for example, "2690 Separations Module" manufactured by Waters Corporation can be used as the measuring device, "GPC KF-806L" manufactured by Showa Denko KK can be used as the column, ethyl acetate can be used as the solvent, and the measurement can be carried out under the conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C.

[0089] The glass transition temperature (Tg) of the above-mentioned (meth)acrylic copolymer is not particularly limited, and the preferred upper limit is -20°C. By making the glass transition temperature (Tg) of the above-mentioned (meth)acrylic copolymer -20°C or lower, the followability of the adhesive layer containing the adhesive composition of the present invention to unevenness is improved, and thus the adhesiveness to a rough surface becomes higher in particular. The more preferred upper limit of the glass transition temperature (Tg) of the above-mentioned (meth)acrylic copolymer is -30°C, the further preferred upper limit is -40°C, and the further more preferred upper limit is -50°C. The lower limit of the glass transition temperature (Tg) of the above-mentioned acrylic copolymer is not particularly limited, and is usually -90°C or higher. From the viewpoint of preventing residual glue on the uneven surface, the preferred lower limit is -80°C.

[0090] The glass transition temperature (Tg) of the above-mentioned (meth)acrylic copolymer can be determined, for example, by differential scanning calorimetry.

[0091] The adhesive composition of the present invention preferably further contains a polymerization initiator.

[0092] By including a polymerization initiator in the adhesive composition of the present invention, the carbon-carbon double bond in the side chain of the above (meth)acrylic copolymer reacts with the polymerization initiator, whereby the adhesive composition of the present invention cures and the adhesive strength decreases, and thus the peeling performance is more excellent.

[0093] The above polymerization initiator may be a photoinitiator or a thermal polymerization initiator. Among them, from the viewpoints of suppressing the increase in adhesion of the adhesive composition of the present invention at high temperatures and suppressing the generation of outgassing, the adhesive composition of the present invention preferably contains a photoinitiator.

[0094] Examples of the above photoinitiator include photoinitiators activated by irradiation with light having a wavelength of 250 to 800 nm. Examples of such photoinitiators include: acetophenone derivatives such as methoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; benzoin ether compounds such as benzoin propyl ether and benzoin isobutyl ether; ketal derivative compounds such as benzil dimethyl ketal and acetophenone diethyl ketal; phosphine oxide derivative compounds such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; bis(η5-cyclopentadienyl)titanocene derivative compounds; benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethylphenyl propane, 2-benzyl-2-(dimethylamino)-4'-morpholinophenyl butanone and other free radical photoinitiators.

[0095] It should be noted that these photoinitiators may be used alone or in combination of two or more.

[0096] Examples of the above thermal polymerization initiator include thermal polymerization initiators that decompose by heat to generate active free radicals that initiate polymerization and curing, such as: dicumyl peroxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate (original text: t-butyl peroxybenzoyl), tert-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxy-2-ethylhexanoate, etc.

[0097] It should be noted that these thermal polymerization initiators may be used alone or in combination of two or more.

[0098] With respect to 100 parts by mass of the above (meth)acrylic copolymer, the preferred lower limit of the content of the above polymerization initiator is 0.1 part by mass. By making the content of the above polymerization initiator 0.1 part by mass or more, the adhesive composition of the present invention can be sufficiently cured when cured, and thus the peelability of the adhesive composition of the present invention is more excellent. The more preferred lower limit of the content of the above polymerization initiator is 0.5 part by mass, and the further preferred lower limit is 1 part by mass.

[0099] In addition, the upper limit of the content of the above polymerization initiator is not particularly limited. From the viewpoint of poor appearance caused by precipitation of the above polymerization initiator, with respect to 100 parts by mass of the above (meth)acrylic copolymer, the preferred upper limit of the content of the above polymerization initiator is 20 parts by mass. The more preferred upper limit is 15 parts by mass, and the further preferred upper limit is 10 parts by mass.

[0100] The adhesive composition of the present invention preferably further contains an inorganic filler.

[0101] By making the adhesive composition of the present invention contain an inorganic filler, the cohesive force of the adhesive composition of the present invention becomes greater. Therefore, even if additives with different polarities are mixed in the above (meth)acrylic copolymer, they will not separate, and the adhesive composition of the present invention can be made more uniform. In addition, since the tensile strength of the adhesive composition of the present invention is significantly improved, even after chemical solution treatment and high-temperature treatment, the adhesive composition will not break due to the stress during peeling, the generation of residual glue can be suppressed, and peeling is easier. Furthermore, the generation of residual glue can be suppressed and peeling from the uneven surface is easier, and the peelability is more excellent.

[0102] Examples of the above inorganic filler include: silica nano-fillers such as fumed silica, fused silica, and colloidal silica, alumina nano-fillers, zirconia fillers, carbon nano-fillers, glass fillers, titanium dioxide fillers, zinc oxide fillers, etc. Among them, from the aspects of being easy to adjust the amount of hydroxyl groups on the surface, easy to control the moisture content at the same time, obtaining a substance with a sufficiently small primary particle size, and easier to adjust the average particle size of the inorganic filler described below to an appropriate range, fine particles of fumed silica and fine particles of fused silica are preferred, and fine particles of fumed silica are more preferred.

[0103] The preferred lower limit of the average particle size of the above inorganic filler is 0.05 μm, and the preferred upper limit is 3 μm. By making the average particle size of the above inorganic filler within the above range, the above inorganic filler is finely dispersed in the adhesive composition of the present invention, and thus the adhesive composition can be made more uniform.

[0104] It should be noted that the average particle size described above is obtained, for example, by observing any 50 inorganic fillers using an electron microscope or an optical microscope and calculating the average value of the particle sizes of the respective inorganic fillers, or by performing a laser diffraction particle size distribution measurement.

[0105] With respect to 100 parts by mass of the above (meth)acrylic copolymer, the preferable lower limit of the content of the above inorganic filler is 1 part by mass, and the preferable upper limit is 40 parts by mass. By making the content of the above inorganic filler within the above range, the cohesive force of the adhesive composition of the present invention becomes greater, the generation of residual glue can be suppressed, and it is easier to peel off from the uneven surface.

[0106] The adhesive composition of the present invention preferably further contains a polyfunctional oligomer or a polyfunctional monomer. By making the adhesive composition of the present invention contain the above polyfunctional oligomer or polyfunctional monomer, the three-dimensional network formation of the above adhesive composition caused by light irradiation or heat load occurs efficiently, and the peelability of the adhesive composition of the present invention is more excellent.

[0107] It should be noted that in the present specification, the "polyfunctional oligomer or polyfunctional monomer" refers to a compound having two or more functional groups having a carbon-carbon unsaturated bond in the molecule and a weight-average molecular weight of 50,000 or less. In addition, in the present specification, the carbon-carbon unsaturated bond of the "functional group having a carbon-carbon unsaturated bond" possessed by the polyfunctional oligomer or polyfunctional monomer does not include the carbon-carbon double bond constituting the aromatic ring.

[0108] In addition, the weight-average molecular weight of the above polyfunctional oligomer or polyfunctional monomer can be determined by the GPC measurement method in the same manner as the weight-average molecular weight of the above acrylic copolymer.

[0109] Examples of the above functional group having a carbon-carbon unsaturated bond include a vinyl group, a (meth)acryloyl group, an allyl group, a maleimide group, etc. Among them, from the viewpoint of a fast reaction rate based on light and heat, a vinyl group is preferable.

[0110] Examples of the above polyfunctional oligomer or polyfunctional monomer include: (meth)acrylate having the above functional group having a carbon-carbon unsaturated bond, a (meth)acrylic copolymer obtained by copolymerizing the (meth)acrylate having the functional group having a carbon-carbon unsaturated bond (wherein, a substance having a structural unit derived from n-heptyl (meth)acrylate and having a carbon-carbon double bond in the side chain is excluded), an organosilicon compound having the above functional group having a carbon-carbon unsaturated bond, a fluorine compound having the above functional group having a carbon-carbon unsaturated bond, etc.

[0111] By making the adhesive composition of the present invention contain a (meth)acrylate having the functional group with a carbon-carbon unsaturated bond as described above and a (meth)acrylic copolymer obtained by copolymerizing the (meth)acrylate having the functional group with a carbon-carbon unsaturated bond as described above, the photocurability and thermosetting properties of the adhesive composition of the present invention are further improved, and the peeling performance of the adhesive composition of the present invention is more excellent.

[0112] Regarding the (meth)acrylate having the functional group with a carbon-carbon unsaturated bond as described above and the (meth)acrylic copolymer obtained by copolymerizing the (meth)acrylate having the functional group with a carbon-carbon unsaturated bond as described above, from the viewpoint of making the three-dimensional networking of the adhesive layer based on heating or light irradiation more efficient, the preferred lower limit of the number of the functional groups with a carbon-carbon unsaturated bond is 2, and the preferred upper limit is 20.

[0113] Examples of the (meth)acrylate having the functional group with a carbon-carbon unsaturated bond as described above and the (meth)acrylic copolymer obtained by copolymerizing the (meth)acrylate having the functional group with a carbon-carbon unsaturated bond as described above include: trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxy penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol diacrylate, EBECRYL524, EBECRYL436 (both manufactured by DAICEL-ALLNEX Co., Ltd.) and other polyester acrylates, UN-5500, UN-5590 (both manufactured by Negami Kogyo Co., Ltd.), UA-160TM, UA-122P (both manufactured by Shin-Nakamura Chemical Co., Ltd.) and other urethane acrylates, and (meth)acrylic copolymers obtained by copolymerizing these (meth)acrylates.

[0114] It should be noted that these (meth)acrylates having a carbon-carbon unsaturated bond and the (meth)acrylic copolymers obtained by copolymerizing the (meth)acrylates having a carbon-carbon unsaturated bond can be used alone or in combination of two or more.

[0115] By including a silicone compound having the functional group with a carbon-carbon unsaturated bond and a fluorine compound having the functional group with a carbon-carbon unsaturated bond in the adhesive composition of the present invention, the silicone compound or the fluorine compound exudes at the interface of the adherend, so that the generation of residual adhesive can be suppressed and peeling can be more easily performed. It should be noted that the adhesive composition of the present invention may contain both the silicone compound having the functional group with a carbon-carbon unsaturated bond and the fluorine compound having the functional group with a carbon-carbon unsaturated bond.

[0116] The silicone compound having the carbon-carbon unsaturated bond or the fluorine compound having the carbon-carbon unsaturated bond preferably further has a functional group capable of crosslinking with the (meth)acrylic copolymer. By making the silicone compound having the functional group with a carbon-carbon unsaturated bond or the fluorine compound having the functional group with a carbon-carbon unsaturated bond have a functional group capable of crosslinking with the (meth)acrylic copolymer, it can react more efficiently with the (meth)acrylic copolymer by using a crosslinking agent or light irradiation. As a result, it is easier to enter into the (meth)acrylic copolymer, and the contamination caused by the attachment of the silicone compound or the fluorine compound to the adherend is further suppressed.

[0117] As the functional group capable of crosslinking with the (meth)acrylic copolymer, it is appropriately selected according to the functional group contained in the (meth)acrylic copolymer, and examples thereof include a carboxyl group, a hydroxyl group, an amide group, an isocyanate group, an epoxy group, and the like.

[0118] In the silicone compound having the functional group with a carbon-carbon unsaturated bond or the fluorine compound having the functional group with a carbon-carbon unsaturated bond, the preferred lower limit of the total number of the functional group with a carbon-carbon unsaturated bond and the functional group capable of crosslinking with the (meth)acrylic copolymer is 2, and the preferred upper limit is 12. By making the total number of the functional group with a carbon-carbon unsaturated bond and the functional group capable of crosslinking with the (meth)acrylic copolymer be 2 or more, the contamination caused by the attachment of the silicone compound or the fluorine compound to the adherend is further suppressed. By making the total number of the functional group with a carbon-carbon unsaturated bond and the functional group capable of crosslinking with the (meth)acrylic copolymer be 12 or less, the three-dimensional network formation of the adhesive composition of the present invention by light irradiation or heating will be more efficient. The more preferred upper limit of the total number of the functional group with a carbon-carbon unsaturated bond and the functional group capable of crosslinking with the (meth)acrylic copolymer is 4, and the most preferred total number of the functional group with a carbon-carbon unsaturated bond and the functional group capable of crosslinking with the (meth)acrylic copolymer is 2.

[0119] Examples of the organosilicon compound having the functional group with a carbon-carbon unsaturated bond as described above include organosilicon (meth)acrylate, organosilicon di(meth)acrylate, and (meth)acrylic copolymers copolymerized therefrom (excluding substances having n-heptyl (meth)acrylate in the structural unit and a carbon-carbon double bond in the side chain).

[0120] Examples of commercially available products among the organosilicon compounds having the functional group with a carbon-carbon unsaturated bond as described above include: X-22-164, X-22-164AS, X-22-164A, X-22-164B, X-22-164C, X-22-164E, X-22-174DX, X-22-2426, X-22-2475 (all manufactured by Shin-Etsu Chemical Co., Ltd.), organosilicon compounds having a methacryloyl group such as MAC-SQ TM-100, MACSQSI-20, MAC-SQHDM (all manufactured by Toagosei Co., Ltd.), organosilicon compounds having an acryloyl group such as EBECRYL350, EBECRYL1360 (all manufactured by DAICEL-ALLNEX Co., Ltd.), AC-SQ TA-100, AC-SQ SI-20 (all manufactured by Toagosei Co., Ltd.), etc.

[0121] Examples of the fluorine compound having a carbon-carbon unsaturated bond as described above include (meth)acrylic copolymers having a structural unit derived from fluorinated (meth)acrylate (excluding substances having n-heptyl (meth)acrylate in the structural unit and a carbon-carbon double bond in the side chain).

[0122] Examples of the fluorinated (meth)acrylate as described above include methyl 2-fluoracrylate, ethyl 2-(perfluorobutyl)acrylate, etc.

[0123] With respect to 100 parts by mass of the above (meth)acrylic copolymer, the preferred lower limit of the content of the above polyfunctional oligomer or polyfunctional monomer is 1 part by mass, and the preferred upper limit is 50 parts by mass. By making the content of the above polyfunctional oligomer or polyfunctional monomer within the above range, the peelability of the adhesive composition of the present invention is more excellent. The more preferred lower limit of the content of the above polyfunctional oligomer or polyfunctional monomer is 2 parts by mass, and the more preferred upper limit is 40 parts by mass.

[0124] The adhesive composition of the present invention preferably further contains a gas generating agent. By making the adhesive composition of the present invention contain the above gas generating agent, gas can be generated on the bonding surface by light irradiation or heating, and thus the peelability of the adhesive composition of the present invention is more excellent.

[0125] The above-mentioned gas generating agent is not particularly limited, and a gas generating agent that generates gas by light (such as ultraviolet rays, laser, etc.), heat, electromagnetic waves, or electron beams is preferred. Among them, from the viewpoints of suppressing the excessive adhesion of the adhesive composition of the present invention at high temperatures and suppressing the generation of outgassing, a gas generating agent that generates gas by light is preferred. The above-mentioned gas generating agent is not particularly limited, and for example, azo compounds, azide compounds, carboxylic acid compounds, tetrazole compounds, etc. are suitably used.

[0126] Examples of the above-mentioned azo compounds include: 2,2'-azobis-(N-butyl-2-methylpropanamide), 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propanamide}, 2,2'-azobis{2-methyl-N-[2-(1-hydroxybutyl)]propanamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propanamide], 2-azobis[N-(2-propenyl)-2-methylpropanamide], 2,2'-azobis(N-butyl-2-methylpropanamide), 2,2'-azobis(N-cyclohexyl-2-methylpropanamide), 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 2,2'-azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane] dihydrochloride, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis(2-methylpropamidine) hydrochloride, 2,2'-azobis(2-aminopropane) dihydrochloride, 2,2'-azobis[N-(2-carboxyacyl)-2-methyl-propamidine], 2,2'-azobis{2-[N-(2-carboxyethyl)amidine]propane}, 2,2'-azobis(2-methylpropaneamidoxime), 2,2'-azobis(2-methylpropionic acid) dimethyl ester, 2,2'-azodiisobutyric acid dimethyl ester, 4,4'-azobis(4-cyanocarbonic acid), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2,4,4-trimethylpentane), etc.

[0127] Examples of the above azide compounds include: 3-azidomethyl-3-methyloxetane, terephthalic azide, p-tert-butylbenzoyl azide, glycidyl azide polymers obtained by ring-opening polymerization of 3-azidomethyl-3-methyloxetane, and other polymers having an azide group.

[0128] Examples of the above carboxylic acid compounds include: phenylacetic acid, diphenylacetic acid, triphenylacetic acid, or their salts.

[0129] Examples of the above tetrazole compounds include: 1H-tetrazole, 5-phenyl-1H-tetrazole, 5,5-azobis-1H-tetrazole, or their salts.

[0130] With respect to 100 parts by mass of the above (meth)acrylic copolymer, the preferred lower limit of the content of the above gas generator is 5 parts by mass, and the preferred upper limit is 50 parts by mass. By making the content of the above gas generator 5 parts by mass or more, a gas sufficient for peeling the adhesive composition of the present invention can be generated from the above gas generator. By making the content of the above gas generator 50 parts by mass or less, the compatibility of the above gas generator with other components in the adhesive composition of the present invention is more excellent, and the adhesive composition of the present invention has sufficient initial adhesiveness. The more preferred lower limit of the content of the above gas generator is 10 parts by mass, and the more preferred upper limit is 30 parts by mass.

[0131] The adhesive composition of the present invention preferably further contains a tackifier. By making the adhesive composition of the present invention contain a tackifier, it has sufficient initial adhesiveness.

[0132] Examples of the above tackifiers include: rosin-based resins, rosin ester-based resins, hydrogenated rosin-based resins, hydrogenated rosin ester-based resins, terpene-based resins, terpene phenol-based resins, coumarone-indene-based resins, alicyclic saturated hydrocarbon-based resins, C5 petroleum resins, C9 petroleum resins, C5-C9 copolymerized petroleum resins, etc.

[0133] It should be noted that these tackifiers can be used alone or in combination of two or more.

[0134] With respect to 100 parts by mass of the above (meth)acrylic copolymer, the preferred lower limit of the content of the above tackifier is 5 parts by mass, and the preferred upper limit is 60 parts by mass. By making the content of the above tackifier 5 parts by mass or more, the adhesive composition of the present invention has sufficient initial adhesiveness. By making the content of the above tackifier 60 parts by mass or less, the adhesiveness of the adhesive composition of the present invention does not become too high, and the peeling performance is more excellent.

[0135] In the case where the above-mentioned (meth)acrylic copolymer contains the structural unit derived from the monomer containing a polar functional group, the adhesive composition of the present invention preferably contains a crosslinking agent. By making the adhesive composition of the present invention contain a crosslinking agent, the polar functional group derived from the structural unit of the monomer containing a polar functional group reacts with the crosslinking agent, whereby the adhesive force is significantly reduced. As a result, the peelability of the adhesive composition of the present invention is more excellent.

[0136] Examples of the above-mentioned crosslinking agent include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, metal chelate type crosslinking agents, and the like. Among them, from the viewpoints of fast reaction rate and further improvement of the cohesion of the adhesive composition of the present invention, isocyanate-based crosslinking agents are preferred.

[0137] With respect to 100 parts by mass of the above-mentioned (meth)acrylic copolymer, the lower limit of the content of the above-mentioned crosslinking agent is preferably 0.05 part by mass, and the upper limit is preferably 10 parts by mass. By making the content of the above-mentioned crosslinking agent within the above range, in the adhesive tape described later, the gel fraction of the adhesive layer containing the adhesive composition of the present invention is moderately adjusted, and an adhesive tape having sufficient initial adhesiveness is obtained.

[0138] The adhesive composition of the present invention may further contain known additives such as plasticizers, surfactants, and waxes. These additives can be used alone or in combination of two or more.

[0139] As a method for producing the adhesive composition of the present invention, for example, there can be mentioned a method of mixing the above-mentioned (meth)acrylic copolymer and, if necessary, the above-mentioned polymerization initiator, the above-mentioned inorganic filler, the above-mentioned polyfunctional oligomer or polyfunctional monomer, the above-mentioned gas generator, the above-mentioned crosslinking agent, the above-mentioned known additives, and the like.

[0140] An adhesive tape having an adhesive layer containing the adhesive composition of the present invention is also one of the present inventions.

[0141] The adhesive tape of the present invention can achieve both excellent embedding property for unevenness and excellent peelability.

[0142] The thickness of the above-mentioned adhesive layer is not particularly limited. The lower limit of the thickness is preferably 5 μm, and the upper limit is preferably 300 μm. By making the thickness of the above-mentioned adhesive layer within the above range, the flexibility of the above-mentioned adhesive layer is more excellent, and the adhesive tape of the present invention can achieve both more excellent embedding property for unevenness and more excellent peelability. The more preferred lower limit of the thickness of the above-mentioned adhesive layer is 20 μm, the more preferred upper limit is 200 μm, and the further preferred lower limit is 35 μm, and the further preferred upper limit is 150 μm.

[0143] The preferred lower limit of the content rate of bio-derived carbon in the above-mentioned adhesive layer is 10%. By making the content rate of bio-derived carbon in the above-mentioned adhesive layer 10% or more, the adhesive tape of the present invention is excellent from the viewpoints of saving petroleum resources and reducing carbon dioxide emissions, and can further reduce the environmental load. The more preferred lower limit of the content rate of bio-derived carbon in the above-mentioned adhesive layer is 25%, and the further preferred lower limit is 40%.

[0144] In addition, the upper limit of the content rate of bio-derived carbon in the above-mentioned adhesive layer is not particularly limited and may be 100%.

[0145] It should be noted that bio-derived carbon contains a certain proportion of radioactive isotopes (C-14), while carbon derived from petroleum contains almost no C-14. Therefore, the content rate of the above-mentioned bio-derived carbon can be calculated by measuring the concentration of C-14 contained in the adhesive layer. Specifically, it can be measured according to ASTM D6866-22, which is a standard used in many bioplastic industries.

[0146] The preferred lower limit of the gel fraction of the above-mentioned adhesive layer is 10% by mass, and the preferred upper limit is 90% by mass. By making the gel fraction of the above-mentioned adhesive layer 10% by mass or more, the embedding property of the adhesive tape of the present invention into unevenness is further improved. By making the gel fraction of the above-mentioned adhesive layer 90% by mass or less, the adhesive composition of the present invention has sufficient initial adhesiveness. The more preferred lower limit of the gel fraction of the above-mentioned adhesive layer is 20% by mass, the more preferred upper limit is 80% by mass, the further preferred lower limit is 30% by mass, and the further preferred upper limit is 70% by mass.

[0147] It should be noted that the gel fraction of the adhesive layer can be measured by the following method.

[0148] Only take out the adhesive layer W from the obtained adhesive tape 0 (g), immerse it in 50 mL of ethyl acetate, and shake it with a shaker at a temperature of 23 degrees and 200 rpm for 24 hours. After shaking, use a metal mesh (mesh #200, W 1 (g)) to separate the ethyl acetate and the adhesive layer swollen by absorbing ethyl acetate, and dry the separated adhesive layer at 110 °C for 1 hour. Measure the mass W 2 (g) of the dried adhesive layer containing the metal mesh, and use the following formula to measure the gel fraction (mass%) of the adhesive layer.

[0149] Gel fraction (mass%) = 100 × (W 2 - W 1 ) / W 0

[0150] (W 0 : the initial mass of the adhesive layer, W 1 : the initial mass of the metal mesh, W 2 : the mass of the adhesive layer containing the metal mesh after drying)

[0151] The gel fraction of the above adhesive layer after heating at 150 °C for 1 hour or after irradiating light with any wavelength in the range of 280 nm or more and 405 nm or less so that the cumulative light amount reaches 1000 mJ / cm 2 The preferred lower limit of the gel fraction after the above is irradiated with light with any wavelength in the range of 280 nm or more and 405 nm or less (hereinafter, sometimes also referred to as "the gel fraction after curing of the adhesive layer") is 90% by mass. By making the gel fraction of the above cured adhesive layer 90% by mass or more, the peeling performance of the adhesive tape of the present invention is more excellent. The more preferred lower limit of the gel fraction after curing of the above adhesive layer is 92% by mass, and the further preferred lower limit is 95% by mass.

[0152] It should be noted that the gel fraction of the above adhesive layer after curing can be measured by the following method: after heating at 150 °C for 1 hour or irradiating light with any wavelength in the range of 280 nm or more and 405 nm or less so that the cumulative light amount reaches 1000 mJ / cm 2 The above adhesive layer is cured by the above method, and then measured by the same method as the gel fraction of the above adhesive layer.

[0153] The preferred upper limit of the shear storage modulus of the above adhesive layer at 23 °C is 1.2×10 5 Pa. By making the shear storage modulus of the above adhesive layer at 23 °C 1.2×10 5 Pa or less, the above adhesive layer will not become too hard, and the embedding property of the adhesive tape of the present invention to unevenness is more excellent. The more preferred upper limit of the shear storage modulus of the above adhesive layer at 23 °C is 1.1×10 5 Pa, and the further preferred upper limit is 1.0×10 5 Pa.

[0154] The lower limit of the shear storage modulus of the above adhesive layer at 23 °C is not particularly limited. From the viewpoint that the adhesive tape of the present invention has sufficient initial adhesiveness, the preferred lower limit is 0.1×10 5 Pa, and the more preferred lower limit is 0.3×10 5 Pa.

[0155] It should be noted that the shear storage modulus of the above adhesive layer at 23°C can be measured, for example, by the following method: using a viscoelastic spectrometer (manufactured by IT Measurement Control Co., Ltd., "DVA-200") etc., performing dynamic viscoelastic measurement under the conditions of shear direction, frequency 10 Hz, heating rate 10°C / min, and temperature range -50°C to 300°C, etc.

[0156] In addition, when the thickness of the above adhesive layer is less than 200 μm, the adhesive layer for measurement is formed by overlapping the above adhesive layer so that the thickness becomes 200 μm or more. For the obtained adhesive layer for measurement, the shear storage modulus is measured as described above.

[0157] The tensile storage modulus of the above adhesive layer at 23°C after heating at 150°C for 1 hour or the tensile storage modulus at 23°C after irradiating light with any wavelength in the range of 280 nm or more and 405 nm or less in such a way that the cumulative light amount reaches 1000 mJ / cm 2 (hereinafter, sometimes also referred to as "the tensile storage modulus of the adhesive layer after curing at 23°C"). The preferred lower limit is 1.0×10 6 Pa. By making the tensile storage modulus of the adhesive layer after curing the above adhesive layer at 23°C be 1.0×10 6 Pa or more, the peelability of the adhesive tape of the present invention is more excellent. The more preferred lower limit of the tensile storage modulus of the adhesive layer after curing at 23°C is 5.0×10 6 Pa, and the further preferred lower limit is 1.0×10 7 Pa.

[0158] In addition, the preferred upper limit of the tensile storage modulus of the adhesive layer after curing at 23°C is not particularly limited, and the upper limit is about 4.0×10 7 Pa.

[0159] It should be noted that the tensile storage modulus of the above adhesive layer after curing at 23°C can be measured by the following method: heating at 150°C for 1 hour or irradiating light with any wavelength in the range of 280 nm or more and 405 nm or less in such a way that the cumulative light amount reaches 1000 mJ / cm 2 to cure the above adhesive layer, and then using a viscoelastic spectrometer (manufactured by IT Measurement Control Co., Ltd., "DVA-200") etc., performing dynamic viscoelastic measurement under the conditions of tensile direction, frequency 10 Hz, heating rate 10°C / min, and temperature range -5°C to 300°C, etc., to perform the measurement.

[0160] It should be noted that when the thickness of the above adhesive layer is less than 400 μm, the adhesive layer for measurement is formed by overlapping the above adhesive layer so that the thickness becomes 400 μm or more. For the obtained adhesive layer for measurement, the tensile storage modulus is measured as described above.

[0161] It should be noted that when the adhesive tape of the present invention has a substrate, for the adhesive layer for measuring the shear storage modulus at 23°C of the above adhesive layer and the tensile storage modulus at 23°C after curing of the above adhesive layer, the adhesive layer obtained by removing the substrate from the adhesive tape and separating only the adhesive layer is used to produce the adhesive layer for measurement, and the measurement is carried out. As a method for removing the substrate, in order to avoid modification of the adhesive layer, there is no particular limitation as long as treatments using solvents, treatments accompanied by chemical reactions, treatments at high temperatures, etc. are avoided. As a specific method, it is possible to select: a method in which after the adhesive layers are adhered to each other, an appropriate temperature and peeling speed are selected, and the substrate layer is separated from the adhesive layer by peeling to remove the substrate; or a method of physically grinding the substrate. In addition, a sheet composed only of the adhesive layer prepared separately can also be used to produce the adhesive layer for measurement.

[0162] The method for adjusting the gel fraction of the above adhesive layer, the gel fraction after curing of the above adhesive layer, the shear storage modulus at 23°C of the above adhesive layer, and the tensile storage modulus at 23°C after curing of the above adhesive layer to the above range is not particularly limited. For example, there can be mentioned: a method of adjusting the composition of the monomers constituting the above (meth)acrylic copolymer, the weight average molecular weight (Mw) of the above (meth)acrylic copolymer, the carbon-carbon double bond equivalent, the hydroxyl value, the acid value, etc.

[0163] The adhesive tape of the present invention can be a non-supported tape without a substrate or a supported tape with a substrate.

[0164] When the adhesive tape of the present invention is a supported tape with a substrate, it can be a single-sided adhesive tape having the above adhesive layer on one side of the substrate or a double-sided adhesive tape having the above adhesive layer on both sides of the substrate.

[0165] The above substrate is not particularly limited, and a substrate that transmits or allows light to pass through is preferred. For example, there can be mentioned: sheets formed of transparent resins such as acrylic acid, olefins, polycarbonates, vinyl chloride, ABS, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), nylon, urethane, polyamide, polyether, polyketone, polyether ether ketone, etc., sheets having a mesh-like structure, sheets with holes, etc.

[0166] From the viewpoint of increasing the content ratio of bio-derived carbon in the entire adhesive tape, the above substrate is preferably a bio-derived substrate.

[0167] As the above-described bio-derived base materials, for example, the following can be mentioned: films and non-woven fabrics containing polyesters (PES) such as plant-derived polyethylene terephthalate (PET), polyethylene furandicarboxylate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS). In addition, the following can also be mentioned: films and non-woven fabrics containing plant-derived polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetyl cellulose (TAC), cellulose, polyamide (PA), etc.

[0168] In addition, from the viewpoint of reducing the environmental load by reducing the use amount of new petroleum resources and suppressing the carbon dioxide emission amount, a base material using recycled resources can be used. As a method for recycling resources, for example, the following methods can be mentioned: recycling waste such as packaging containers, household appliances, automobiles, building materials, and foods, and waste generated in the manufacturing process, and using the extracted materials as raw materials again through cleaning, decontamination, or decomposition based on heating or fermentation. As a base material using recycled resources, for example, the following can be mentioned: films and non-woven fabrics formed of PET, PBT, PE, PP, PA, etc., using as a raw material a substance obtained by re-resinifying recycled plastics. In addition, the recycled waste can be burned and used as heat energy related to the manufacture of the base material and its raw materials, and the oil contained in the above-mentioned recycled waste can be mixed into petroleum, fractionated, purified, and the obtained product can be used as a raw material.

[0169] The thickness of the above-described base material is not particularly limited, and the preferred lower limit is 12 μm, and the preferred upper limit is 200 μm. By making the thickness of the above-described base material within the above range, an adhesive tape having excellent processability can be produced, which exhibits high flexibility capable of closely adhering and conforming to the shape of the adherend while having an appropriate stiffness. The more preferred lower limit of the thickness of the above-described base material is 25 μm, and the more preferred upper limit is 125 μm.

[0170] The method for manufacturing the adhesive tape of the present invention is not particularly limited, and it can be manufactured by a conventionally known manufacturing method. For example, in the case of a double-sided adhesive tape, the following methods can be mentioned, etc.

[0171] First, a solvent is added to a (meth)acrylic copolymer and, if necessary, a crosslinking agent, etc., to prepare a solution of adhesive A. The solution of adhesive A is applied to the surface of the base material, and the solvent in the solution is completely dried and removed to form an adhesive layer A. Next, a release film is overlapped on the formed adhesive layer A with its release-treated surface facing the adhesive layer A.

[0172] Next, a solution of Adhesive B prepared in the same manner as described above is coated on the release surface of a release film different from the above-mentioned release film, and the solvent in the solution is completely dried and removed, thereby producing a laminated film having an adhesive layer B formed on the surface of the release film. The obtained laminated film is overlapped on the back surface of the substrate having the adhesive layer A with the adhesive layer B facing the back surface of the substrate to produce a laminate. Then, by pressing the above laminate using a rubber roller or the like, a double-sided adhesive tape having adhesive layers on both sides of the substrate and the surfaces of the adhesive layers covered with release films can be obtained.

[0173] Alternatively, two sets of laminated films can be produced in the same manner, and these laminated films are overlapped on both sides of the substrate with the adhesive layers of the laminated films facing the substrate to produce a laminate, and the laminate is pressed using a rubber roller or the like, thereby obtaining a double-sided adhesive tape having adhesive layers on both sides of the substrate and the surfaces of the adhesive layers covered with release films.

[0174] The preferred lower limit of the 180° peel strength of the adhesive tape of the present invention with respect to SUS is 0.3 N / 25 mm. By making the 180° peel strength of the adhesive tape of the present invention with respect to SUS 0.3 N / 25 mm or more, the adhesive tape of the present invention has sufficient initial adhesiveness. The more preferred lower limit of the 180° peel strength of the adhesive tape of the present invention with respect to SUS is 0.5 N / 25 mm, and the further preferred lower limit is 1.0 N / 25 mm.

[0175] In addition, the upper limit of the 180° peel strength of the adhesive tape of the present invention with respect to SUS is not particularly limited, and about 20 N / 25 mm is a preferred upper limit from the viewpoint of the processability of the adhesive tape.

[0176] It should be noted that the 180° peel strength of the adhesive tape of the present invention with respect to SUS can be measured, for example, by a method of conducting a tensile test under the conditions of 23°C, a peel rate of 300 mm / min, and a peel angle of 180° in accordance with JIS Z0237.

[0177] The 180° peel strength of the adhesive tape after heating at 150°C for 1 hour with respect to SUS or to make the cumulative light amount reach 1000 mJ / cm 2The preferred upper limit of the 180° peel strength of the adhesive tape on SUS after irradiation with light of any wavelength in the range of 280 nm or more and 405 nm or less in the above-described manner (hereinafter, sometimes also referred to as "the 180° peel strength of the adhesive tape on SUS after curing") is 0.3 N / 25 mm. By making the 180° peel strength of the adhesive tape on SUS after curing 0.3 N / 25 mm or less, the peel performance of the adhesive tape is more excellent. The more preferred upper limit of the 180° peel strength of the adhesive tape on SUS after curing is 0.25 N / 25 mm, and the further preferred upper limit is 0.20 N / 25 mm.

[0178] It should be noted that the 180° peel strength of the adhesive tape on SUS after curing can be measured by the following method: In the measurement of the 180° peel strength of the adhesive tape of the present invention on SUS, before the tensile test, it is heated at 150 °C for 1 hour, or irradiated with light of any wavelength in the range of 280 nm or more and 405 nm or less in the above-described manner so that the cumulative light amount reaches 1000 mJ / cm 2 above, and then the adhesive tape of the present invention is cured, and a tensile test is performed to measure it.

[0179] The method for adjusting the 180° peel strength of the adhesive tape of the present invention on SUS and the 180° peel strength of the adhesive tape on SUS after curing to the above range is not particularly limited. For example, methods such as adjusting the composition of the monomers constituting the above (meth)acrylic copolymer, the weight average molecular weight (Mw) of the above (meth)acrylic copolymer, the carbon-carbon double bond equivalent, the hydroxyl value, the acid value, etc. can be cited.

[0180] Since the adhesive tape of the present invention has excellent embedding property and peel performance for unevenness, it is preferably used for temporarily fixing an object having an uneven surface. Among them, in the manufacture of electronic components, it is more preferably used for temporarily fixing a semiconductor wafer, and more preferably used for temporarily fixing a bump wafer having an uneven surface.

[0181] A method for processing a semiconductor wafer having the following steps is also one of the present inventions. The steps are: temporarily fixing a semiconductor wafer to a support using the adhesive tape of the present invention, and peeling the adhesive tape after curing the adhesive layer by light or heat.

[0182] By using the adhesive tape of the present invention in the method for processing a semiconductor wafer of the present invention, the processing quality of the manufactured electronic components can be further improved even in the case of a semiconductor wafer having an uneven surface.

[0183] As the above-mentioned support, for example, glass, quartz, sapphire, copper plate, organic substrate, FR4 substrate, silicon substrate, etc. can be cited. Among them, a support with excellent ultraviolet transmittance is preferred, and glass, quartz, and sapphire are preferred. Since the ultraviolet transmittance of the above-mentioned support is excellent, in the method for processing a semiconductor wafer of the present invention, before peeling the cured adhesive tape of the present invention from the semiconductor wafer, the adhesive tape is irradiated with laser or ultraviolet light from the support side to peel the support, whereby the adhesive tape of the present invention can be peeled more easily.

[0184] In the processing method of the present invention, as the method for curing the above-mentioned adhesive layer using light, for example, a method of irradiating light with a wavelength of 280 nm or more and 405 nm or less in such a manner that the cumulative light amount reaches 1000 mJ / cm 2 or more can be cited.

[0185] As the method for curing the adhesive tape of the present invention using heat, for example, a method of heating at a temperature of 100°C or more and 200°C or less for 10 minutes or more and 2 hours or less can be cited.

[0186] The semiconductor wafer used in the method for processing a semiconductor wafer of the present invention is not particularly limited, and the method for processing a semiconductor wafer of the present invention can be used for the processing of all semiconductor wafers used in ordinary electronic components. Regarding the method for processing a semiconductor wafer of the present invention, even in the case of a semiconductor wafer having unevenness on the surface where electrodes, circuits, etc. are formed, it is possible to suppress the peeling of the adhesive tape in the cleaning process, thinning process, cutting process, etc., and it is possible to suppress the generation of residual glue after curing the adhesive tape and easily peel it from the surface of the semiconductor wafer.

[0187] A method for manufacturing a semiconductor device having the following steps is also one of the present inventions, and the steps are: temporarily fixing a semiconductor wafer to a support using the adhesive tape of the present invention, and peeling the adhesive tape after curing the above-mentioned adhesive layer using light or heat.

[0188] According to the method for manufacturing a semiconductor device of the present invention, even in the case of a semiconductor device having an uneven surface, the processing quality of the manufactured semiconductor device is further improved, the yield during production can be increased, and thus the manufacturing efficiency of the semiconductor device can be further improved.

[0189] The method for manufacturing a semiconductor device of the present invention can be used, for example, in manufacturing processes of semiconductor devices such as a film forming process, an etching process, a cleaning process, a thinning process, a cutting process, a bumping process, a reflow process, an annealing process, an ashing process, etc.

[0190] Advantages of the Invention

[0191] According to the present invention, an adhesive composition capable of achieving both excellent embedding properties for irregularities and excellent peeling properties can be provided. Further, according to the present invention, an adhesive tape having an adhesive layer containing the adhesive composition can be provided. In addition, according to the present invention, a method for processing a semiconductor wafer and a method for manufacturing a semiconductor device using the adhesive tape can be provided. Detailed Embodiments

[0192] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0193] <n-Heptyl acrylate containing bio-derived carbon>

[0194] Ricinoelaidic acid derived from castor oil was cracked to obtain a mixture containing undecylenic acid and heptanol. Next, it was separated from undecylenic acid by distillation, whereby n-heptanol containing bio-derived carbon was obtained. By esterifying n-heptanol containing bio-derived carbon with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), n-heptyl acrylate containing bio-derived carbon was prepared.

[0195] (Example 1)

[0196] (1) Preparation of (meth)acrylic copolymer

[0197] A reactor equipped with a thermometer, a stirrer, and a condenser was prepared. 78.2 parts by mass of n-heptyl acrylate containing bio-derived carbon prepared by the above method as an (alkyl) acrylate monomer, 19.8 parts by mass of 2-hydroxyethyl acrylate as a functional group-containing monomer, 1.0 part by mass of acrylic acid, and 80 parts by mass of ethyl acetate were added to the reactor, and then the reactor was heated to start reflux. Next, 0.01 part by mass of 1,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane as a polymerization initiator was added to the reactor, and polymerization was initiated under reflux. Next, 0.01 part by mass of 1,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane was added also 1 hour and 2 hours after the start of polymerization. Further, 0.05 part by mass of tert-hexyl perpivalate was added 4 hours after the start of polymerization, and the polymerization reaction was continued. Then, 8 hours after the start of polymerization, ethyl acetate was added to the reactor, and it was cooled while diluting, whereby an ethyl acetate solution containing a (meth)acrylic polymer into which a carbon-carbon double bond was not introduced was obtained. To the obtained ethyl acetate solution containing a (meth)acrylic polymer into which a carbon-carbon double bond was not introduced, 1.0 part by mass of 2-isocyanatoethyl methacrylate as a functional group-containing unsaturated compound was added and reacted to obtain a solution of (meth)acrylic copolymer A (hydroxyl value: 90 mgKOH / g, acid value: 7.0 mgKOH / g, carbon-carbon double bond equivalent: 0.075 meq / g).

[0198] It should be noted that the hydroxyl value and acid value of the (meth)acrylic acid copolymer A were measured by the potentiometric titration method specified in JIS K 0070:1992.

[0199] For the obtained (meth)acrylic acid copolymer A, using the "2690 Separations Module" manufactured by Waters Corporation as the measuring device, "GPC KF-806L" manufactured by Showa Denko K.K. as the column, and ethyl acetate as the solvent, the weight-average molecular weight was measured under the conditions of a sample flow rate of 1 mL / min and a column temperature of 40 °C. As a result, the weight-average molecular weight was 900,000.

[0200] (2) Manufacture of the adhesive composition and the adhesive tape

[0201] To the solution of the obtained (meth)acrylic acid copolymer A, 0.2 parts by mass of an isocyanate-based crosslinking agent ("Coronate L-45K" manufactured by Synthetic Chemical Industry Co., Ltd.) and 1.0 part by mass of a photopolymerization initiator ("Omnirad 369E" manufactured by IGM Resins) were added per 100 parts by mass of the (meth)acrylic acid copolymer, and then mixed to obtain an ethyl acetate solution of the adhesive composition.

[0202] The ethyl acetate solution of the obtained adhesive composition was applied with a doctor blade onto the release-treated surface of a polyethylene terephthalate (PET) film having a thickness of 50 μm so that the thickness of the adhesive layer after drying would be 30 μm, and then dried at 110 °C for 5 minutes to form an adhesive layer. Then, the obtained adhesive layer was laminated onto a substrate of a polyethylene naphthalate (PEN) film having a thickness of 25 μm and allowed to cure at 40 °C for 5 days to obtain an adhesive tape having an adhesive layer on one side of the substrate.

[0203] (3) Content ratio of bio-based carbon in the adhesive layer

[0204] For the obtained adhesive layer, the content ratio of bio-based carbon was measured in accordance with ASTM D6866-22. The results are shown in Table 2.

[0205] (4) Measurement of the gel fraction of the adhesive layer

[0206] On the release-treated surface of a polyethylene terephthalate (PET) film with a thickness of 50 μm that has undergone a release treatment, an ethyl acetate solution of the obtained adhesive composition was applied with a doctor blade so that the thickness of the adhesive layer after drying would be 30 μm, and then it was laminated onto the release-treated surface of a polyethylene terephthalate (PET) film with a thickness of 50 μm that has undergone a release treatment. It was left to cure at 40 °C for 5 days to obtain an adhesive tape for gel fraction measurement. The obtained adhesive tape for gel fraction measurement was cut into a shape of 5 cm in length and 5 cm in width and used as a sample for evaluation.

[0207] Only the adhesive layer W was taken out from the obtained sample for evaluation. 0 (g), immersed in 50 mL of ethyl acetate, and shaken for 24 hours with a shaker under the conditions of a temperature of 23 °C and 200 rpm. After shaking, a metal mesh (mesh size #200, W 1 (g)) was used to separate the ethyl acetate and the adhesive layer that had swelled by absorbing the ethyl acetate. The separated adhesive layer was dried at 110 °C for 1 hour. The mass W 2 (g) of the dried adhesive layer containing the metal mesh was measured, and the gel fraction (mass %) of the adhesive layer was measured using the following formula. The results are shown in Table 2.

[0208] Gel fraction (mass %) = 100 × (W 2 - W 1 ) / W 0

[0209] (W 0 : Initial mass of the adhesive layer, W 1 : Initial mass of the metal mesh, W 2 : Mass of the dried adhesive layer containing the metal mesh)

[0210] (5) Measurement of the gel fraction of the adhesive layer after curing

[0211] The adhesive tape for gel fraction measurement obtained in the same manner as in the above-mentioned "(4) Measurement of the gel fraction of the adhesive layer" was cut into a shape of 5 cm in length and 5 cm in width, and then irradiated with light having a wavelength of 405 nm using an ultra-high pressure mercury lamp so that the cumulative light amount would reach 2500 mJ / cm 2 to cure the adhesive layer, and a sample for evaluation was prepared.

[0212] For the obtained sample for evaluation, the gel fraction (mass %) was measured by the same method as in the above-mentioned "(4) Measurement of the gel fraction of the adhesive layer" to obtain the gel fraction (mass %) of the adhesive layer after curing. The results are shown in Table 2.

[0213] (6) Measurement of the shear storage modulus of the adhesive layer at 23 °C

[0214] On the release-treated surface of a polyethylene terephthalate (PET) film with a thickness of 50 μm that has undergone release treatment, an ethyl acetate solution of the adhesive composition obtained was applied with a doctor blade so that the thickness of the adhesive layer after drying would be 50 μm, and then it was adhered to the release-treated surface of a polyethylene terephthalate (PET) film with a thickness of 50 μm that has undergone release treatment. It was left to cure at 40 °C for 5 days to obtain an adhesive tape for measuring the shear storage modulus. For the adhesive layer of the obtained adhesive tape for measuring the shear storage modulus, they were overlapped so that the thickness would be 400 μm or more to produce a sample for evaluation.

[0215] For the sample for evaluation, a dynamic viscoelastic spectrum was measured using a viscoelastic spectrometer (manufactured by IT Measurement Control Co., Ltd., "DVA-200") under the conditions of a heating rate of 10 °C / min in a simple heating mode, the shear direction, a frequency of 10 Hz, and a temperature range of -50 °C to 300 °C. From this, the shear storage modulus (Pa) at 23 °C of the adhesive layer was obtained. The results are shown in Table 2.

[0216] (7) Measurement of the tensile storage modulus at 23 °C after curing of the adhesive layer

[0217] For the adhesive layer of the adhesive tape for measuring the shear storage modulus obtained in the same manner as in the above-mentioned "(6) Measurement of the shear storage modulus at 23 °C of the adhesive layer", after overlapping them so that the thickness would be 400 μm or more, a super-high-pressure mercury lamp was used to irradiate light with a wavelength of 405 nm so that the cumulative light amount would reach 2500 mJ / cm 2 to cure the adhesive layer and produce a sample for evaluation.

[0218] For the produced sample for evaluation, a dynamic viscoelastic spectrum was measured using a viscoelastic spectrometer (manufactured by IT Measurement Control Co., Ltd., "DVA-200") under the conditions of a heating rate of 10 °C / min in a simple heating mode, the tensile direction, a frequency of 10 Hz, and a temperature range of -50 °C to 300 °C. From this, the tensile storage modulus (Pa) at 23 °C after curing of the adhesive layer was obtained. The results are shown in Table 2.

[0219] (8) Measurement of the 180° peel strength of the adhesive tape from SUS

[0220] The adhesive tape obtained in the above-mentioned "(2) Manufacture of adhesive composition and adhesive tape" was cut into a flat rectangle with a width of 25 mm and a length of 100 mm, and a 2-kg rubber roller was reciprocated once at a speed of 300 mm / min, and thus it was adhered to a SUS plate (SUS304 plate that had been cleaned with ethanol and dried). Then, it was cured at 23°C and 50% RH for 20 minutes to produce a test sample. For the obtained test sample, according to JIS Z0237, a tensile test was carried out under the conditions of 23°C, 50% RH, a tensile speed of 300 mm / min, and a peeling angle of 180°, and the 180° peeling force (N / 25 mm) of the adhesive tape on SUS was measured. The results are shown in Table 2.

[0221] (9)Measurement of 180° peeling force of the adhesive tape on SUS after curing

[0222] By the same method as in the above-mentioned "(8) Measurement of 180° peeling force of the adhesive tape on SUS", after the adhesive tape obtained in the above-mentioned "(2) Manufacture of adhesive composition and adhesive tape" was adhered to a SUS plate (SUS304 plate that had been cleaned with ethanol and dried), it was cured at 23°C and 50% RH for 20 minutes. Further, a super-high-pressure mercury lamp was used to irradiate the adhesive tape adhered to the SUS plate with light having a wavelength of 405 nm in such a way that the cumulative light amount reached 2500 mJ / cm 2 to cure the adhesive tape and produce a test sample. For the obtained test sample, according to JIS Z0237, a tensile test was carried out under the conditions of 23°C, 50% RH, a tensile speed of 300 mm / min, and a peeling angle of 180°, and the 180° peeling force (N / 25 mm) of the adhesive tape on SUS after curing was measured. The results are shown in Table 2.

[0223] <Evaluation>

[0224] The following evaluation was carried out on the adhesive tape obtained in the above-mentioned "(2) Manufacture of adhesive composition and adhesive tape". The results are shown in Table 2.

[0225] (1)Concavo-convex embedding property

[0226] The obtained adhesive tape was cut into a circle with a diameter of 20 cm, and after being attached to the side with unevenness of a silicon wafer with a diameter of 20 cm, a thickness of about 750 μm, and a height difference of about 10 μm in a vacuum, it was left standing for 1 hour under the conditions of 23°C and 50% RH to produce a measurement sample. It should be noted that the silicon wafer with unevenness was produced by forming a cut of about 10 μm on the surface of the wafer (Φ8 inches, thickness 725 μm) using a cutting device (manufactured by DISCO Corporation, "DFD6360").

[0227] The wafer surface of the measurement sample was observed using an optical microscope (manufactured by KEYENCE Corporation, "VHX-970F", magnification 10x), and the embedding property of the adhesive tape into unevenness (unevenness embedding property) was evaluated according to the following criteria.

[0228] · ◎: No voids were confirmed between the wafer and the adhesive tape.

[0229] · ○: The size of the voids between the wafer and the adhesive tape is less than 5% of the total area of the bonding surface.

[0230] · ×: The size of the voids between the wafer and the adhesive tape is 5% or more of the total area of the bonding surface.

[0231] (2) Peelability

[0232] (2-1) Residue

[0233] The adhesive tape used in the evaluation of the above "(embedding property of unevenness)" was irradiated with light of wavelength 405 nm in such a way that the cumulative light amount reached 2500 mJ / cm 2 to cure the adhesive tape. The cured adhesive tape was peeled off from the silicon wafer with height difference using a peeling tape. The surface of the silicon wafer with height difference from which the adhesive tape was peeled was observed using an optical microscope (manufactured by KEYENCE Corporation, "VHX-970F", magnification 10x), and the residue was evaluated according to the following criteria to determine the peelability of the adhesive tape.

[0234] · ◎: No residue was present on the wafer surface.

[0235] · ○: The residue on the wafer surface is less than 5% of the total area of the bonding surface.

[0236] · ×: The residue on the wafer surface is 5% or more of the total area of the bonding surface.

[0237] (2-2) Wafer cracking

[0238] The obtained adhesive tape was cut into a circle with a diameter of 20 cm and attached in a vacuum to the side with height difference of a silicon wafer with height difference of a circuit (unevenness) having a diameter of 20 cm, a thickness of about 750 μm, and a height difference of about 10 μm produced by the same method as the above "(embedding property of unevenness)". Further, the side of the silicon wafer with height difference without height difference to which the adhesive tape was attached was ground and polished, and the thickness of the silicon wafer with height difference was ground to 50 μm to prepare a measurement sample.

[0239] In such a way that the cumulative light amount reached 2500 mJ / cm 2The adhesive tape of the prepared measurement sample was irradiated with light having a wavelength of 405 nm to cure the adhesive tape. The cured adhesive tape was peeled off using a peeling tape, and the wafer breakage of the silicon wafer with the tape height difference from which the adhesive tape was peeled was observed visually. The same operation was performed on 5 measurement samples, and the peeling performance of the adhesive tape was evaluated according to the following criteria.

[0240] ·◎: 0 out of 5 silicon wafers with the tape height difference of breakage

[0241] ·○: 1 out of 5 silicon wafers with the tape height difference of breakage

[0242] ·×: 2 or more out of 5 silicon wafers with the tape height difference of breakage

[0243] (Examples 2 to 12 and 14 to 17, Comparative Examples 1 to 5)

[0244] In the above-mentioned "(1) Preparation of (meth)acrylic copolymer", the composition was changed as shown in Table 1, and in the above-mentioned "(2) Production of adhesive composition and adhesive tape", the composition of the adhesive composition was changed as shown in Tables 2 to 4. Except for this, the operations were the same as in Example 1 to prepare the (meth)acrylic copolymer, the adhesive composition and the adhesive tape. For the (meth)acrylic copolymer, the adhesive layer and the adhesive tape, the operations were the same as in Example 1 to conduct the measurement and evaluation. The results are shown in Tables 1 to 4.

[0245] (Example 13)

[0246] In the above-mentioned "(1) Preparation of (meth)acrylic copolymer", the composition was changed as shown in Table 1, and in the above-mentioned "(2) Production of adhesive composition and adhesive tape", the composition of the adhesive composition was changed as shown in Table 3. The substrate was changed from a PEN film with a thickness of 25 μm to a PET film with a thickness of 25 μm. Except for this, the operations were the same as in Example 1 to prepare the (meth)acrylic copolymer, the adhesive composition and the adhesive tape. For the (meth)acrylic copolymer, the adhesive layer and the adhesive tape, the operations were the same as in Example 1 to conduct the measurement and evaluation. The results are shown in Tables 1 and 3.

[0247] (Example 18)

[0248] In the above-mentioned “(1) Preparation of (meth)acrylic acid copolymer”, the composition was changed as shown in Table 1, and in the above-mentioned “(2) Production of adhesive composition and adhesive tape”, the composition of the adhesive composition was changed as shown in Table 3. In addition, in the above-mentioned “(5) Measurement of gel fraction after curing of adhesive layer”, “(7) Measurement of tensile storage modulus at 23°C after curing of adhesive layer”, “(9) Measurement of 180° peel strength of adhesive tape after curing against SUS”, “(2-1) Residue” and “(2-2) Wafer cracking” measurement and evaluation, instead of using an ultra-high pressure mercury lamp to irradiate light with a wavelength of 405 nm so that the cumulative light amount reaches 2500 mJ / cm 2 , a heat treatment at 150°C for 10 minutes was carried out to cure the adhesive layer. Except for this, the operations were the same as in Example 1 to prepare the (meth)acrylic acid copolymer, produce the adhesive composition and adhesive tape, and the (meth)acrylic acid copolymer, adhesive layer and adhesive tape were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 3.

[0249] It should be noted that the abbreviations of the respective materials in Table 1 represent the following compounds.

[0250] ·HPA: n-heptyl acrylate

[0251] ·2-EHA: 2-ethylhexyl acrylate

[0252] ·BA: n-butyl acrylate

[0253] ·HEA: 2-hydroxyethyl acrylate

[0254] ·AAc: acrylic acid

[0255] ·MOI: 2-isocyanatoethyl methacrylate

[0256] In addition, the abbreviations of the materials of the substrates in Tables 2 to 4 represent the following materials.

[0257] ·PEN: polyethylene naphthalate

[0258] ·PET: polyethylene terephthalate

[0259] [Table 1]

[0260]

[0261] [Table 2]

[0262]

[0263] [Table 3]

[0264]

[0265] [Table 4]

[0266]

[0267] Industrial Applicability

[0268] According to the present invention, it is possible to provide an adhesive composition capable of achieving both excellent embedding properties for unevenness and excellent peeling properties. Further, according to the present invention, it is possible to provide an adhesive tape having an adhesive layer containing the adhesive composition. In addition, according to the present invention, it is possible to provide a method for processing a semiconductor wafer and a method for manufacturing a semiconductor device using the adhesive tape.

Claims

1. An adhesive composition, characterized in that Contains (meth)acrylic acid copolymer, The (meth)acrylic copolymer comprises a structural unit derived from n-heptyl (meth)acrylate, The (meth)acrylic copolymer has a carbon-carbon double bond in a side chain.

2. The adhesive composition according to claim 1, wherein The content ratio of the structural unit derived from n-heptyl (meth)acrylate in the (meth)acrylic copolymer is 15% by mass or more.

3. The adhesive composition according to claim 1 or 2, wherein The (meth)acrylic copolymer has a carbon-carbon double bond equivalent of 0.05 meq / g or more.

4. The adhesive composition according to claim 1, 2 or 3, wherein The (meth)acrylic copolymer includes a structural unit derived from a monomer containing a polar functional group.

5. The adhesive composition according to claim 4, wherein The total content ratio of the structural units derived from the polar functional group-containing monomer in the (meth)acrylic copolymer is 0.01 mass % or more and 30 mass % or less.

6. The adhesive composition according to claim 4 or 5, wherein The (meth)acrylic copolymer has an acid value of 10 mgKOH / g or less.

7. The adhesive composition according to claim 4, 5 or 6, wherein The (meth)acrylic copolymer has a hydroxyl value of 5 mgKOH / g or more and 100 mgKOH / g or less.

8. The adhesive composition according to claim 1, 2, 3, 4, 5, 6 or 7, wherein The (meth)acrylic copolymer has a weight average molecular weight of 200,000 to 2,000,000.

9. The adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7 or 8, further comprising a photopolymerization initiator.

10. The adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, further comprising an inorganic filler.

11. The adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, further comprising a multifunctional oligomer or a multifunctional monomer.

12. The adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, further comprising a gas generating agent.

13. The adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, further comprising a tackifier.

14. An adhesive tape comprising an adhesive layer comprising the adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13.

15. The adhesive tape according to claim 14, wherein The content of biogenic carbon in the adhesive layer is 10% or more.

16. The adhesive tape according to claim 14 or 15, wherein The gel fraction of the adhesive layer is 10% by mass or more and 90% by mass or less, The gel fraction of the adhesive layer after heating at 150° C. for 1 hour or the accumulated light intensity reaches 1000 mJ / cm 2 The gel fraction after irradiation with light of any wavelength within a range of 280 nm to 405 nm in the above manner is 90 mass % or more.

17. The adhesive tape according to claim 14, 15 or 16, wherein: The shear storage modulus of the adhesive layer at 23°C is 1.2×10 5 Below Pa, The tensile storage modulus of the adhesive layer at 23°C after heating at 150°C for 1 hour or the ... 2 The tensile storage modulus at 23°C after irradiation with light of any wavelength in the range of 280 nm to 405 nm in the above manner was 1.0×10 6 Pa or above.

18. The adhesive tape according to claim 14, 15, 16 or 17, wherein the 180° peeling force to SUS is 0.3 N / 25 mm or more. The 180° peel strength of the adhesive tape to SUS after heating at 150°C for 1 hour or when the accumulated light intensity reaches 1000 mJ / cm 2 The 180° peel strength to SUS after irradiation with light of any wavelength in the range of 280 nm to 405 nm in the above manner was 0.3 N / 25 mm or less.

19. The adhesive tape according to claim 14, 15, 16, 17 or 18, which is used for temporary fixing of a semiconductor wafer. 20 . A method for processing a semiconductor wafer, comprising the steps of temporarily fixing a semiconductor wafer to a support using the adhesive tape according to claim 19 , and peeling off the adhesive tape after curing the adhesive layer by light or heat. 21 . A method for manufacturing a semiconductor device, comprising the steps of temporarily fixing a semiconductor wafer to a support using the adhesive tape according to claim 19 , and peeling off the adhesive tape after curing the adhesive layer by light or heat.

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