Adhesive tape for wafer fabrication and wafer fabrication methods

Abstract

The present invention provides a wafer processing adhesive tape that, even when used in wafer processing steps involving the use of support components, allows for the proper retention of the wafer after dissolving the adhesive on the support components attached to the wafer with a solvent, peeling off the support components, or washing away any residual adhesive on the wafer, and prevents low yield due to wafer contamination. The wafer processing adhesive tape of the present invention is formed by laminating at least a substrate film, a first adhesive layer, and a second adhesive layer in this order. The first adhesive layer is formed by an adhesive composition comprising an acrylic polymer or a polyester polymer as a base polymer, wherein the glass transition temperature of the base polymer is -20°C or higher.

Description

Technical Field

[0001] This invention relates to an adhesive tape for wafer processing used in wafer dicing. More specifically, it relates to an adhesive tape for wafer processing used in wafer processing methods that include a wafer cleaning step using a solvent. Prior Technology

[0002] On the back side of a wafer formed by thin-film fabrication wiring patterns, to protect the patterned surface and secure the wafer itself, a protective tape is typically applied to the patterned surface before thin-film processing such as grinding and lapping is performed. This protective tape is generally made by coating an acrylic adhesive onto a substrate composed of a plastic film. However, in recent years, with the miniaturization and thinning of IC cards and mobile phones, the thickness of chips has been required to be below 50μm. Using the traditional protective tape method, the tape alone cannot support the wafer. Warping of the wafer after lapping or bending during wafer cassette storage makes wafer handling and automation of processing and transportation difficult.

[0003] To address this issue, a proposed method involves bonding a glass substrate, ceramic substrate, or silicon wafer substrate to the wafer using an adhesive to provide support (see, for example, Patent Document 1). This significantly improves wafer processability and enables automated transport by using support components made of glass, ceramic, or silicon wafer substrates. Furthermore, the support components can also be used to support the wafer between the back-side wiring and bump formation steps.

[0004] When using support members, the step of peeling the support members off the wafer becomes necessary during wafer processing. Generally, the peeling of support members is achieved by dissolving the adhesive with a solvent and then washing. In addition to the methods mentioned above, other methods for peeling the wafer off the support members include heating to soften the adhesive, allowing the support member to slide and peel off, or using laser light to decompose the adhesive. Even when using these methods, adhesive or its decomposition products may remain on the wafer surface after peeling off the support members. Therefore, to remove these residues, the wafer may be immersed in an organic solvent for washing, or the wafer may be washed by blowing organic solvent onto it while rotating it.

[0005] Then, the wafer is transferred to the dicing step to be cut into individual wafers. In general, the dicing step uses wafer processing adhesive tape that is used to laminate an adhesive layer onto a substrate film (see, for example, Patent Document 2). [Previous Technical Documents] [Patent Literature]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2006-135272 [Patent Document 2] Japanese Patent Application Publication No. 2007-100064 Summary of the Invention

[0007] [The problem the invention aims to solve] However, as mentioned above, when the wafer thickness is below 50 μm, wafer processing becomes extremely difficult due to warping after grinding or deflection during wafer casing. It is common practice to apply wafer processing adhesive tape to the ground surface of the wafer after grinding and polishing on the back side, before peeling off the support components, and then support and fix it to the ring frame. Accordingly, the adhesive used during support component peeling is dissolved or washed away using solvents, and the wafer is then adhered to the wafer using wafer processing adhesive tape, which requires high solvent resistance.

[0008] However, conventional wafer processing adhesive tapes, such as those described in Patent Document 2, have insufficient solvent resistance, which reduces the adhesion of the adhesive layer and fails to adequately hold the wafer. Furthermore, the adhesive layer of the wafer processing adhesive tape can dissolve in solvents, contaminating the wafer and reducing yield.

[0009] Therefore, the present invention aims to provide a wafer processing adhesive tape that, even when used in wafer processing steps involving the use of a support member, allows for the proper retention of the wafer after dissolving the adhesive on the wafer with a solvent and peeling off the support member, or after washing away any residual adhesive on the wafer, and prevents low yield due to wafer contamination. [Methods used to solve problems]

[0010] In order to achieve the above-mentioned objectives, the inventors, through repeated and diligent research, discovered that the glass transition temperature of the substrate polymer of the adhesive layer is related to its solvent resistance. This invention is based on this discovery.

[0011] That is, the wafer processing adhesive tape of the present invention is a wafer processing adhesive tape formed by laminating a substrate film, a first adhesive layer, and a second adhesive layer in this order. The first adhesive layer is formed by an adhesive composition containing an acrylic polymer or a polyester polymer as the base polymer, and the glass transfer temperature of the base polymer is above -20°C.

[0012] The aforementioned adhesive tape for wafer processing is preferably made of a polyolefin resin as the substrate film.

[0013] Furthermore, the adhesive tape for wafer processing is preferably made of a substrate film with a thickness of 70~350μm.

[0014] Furthermore, the adhesive tape for wafer processing is preferably prepared such that 1 ml of p-menthane is dropped onto the surface of the aforementioned second adhesive layer and the residual solvent content after standing for 30 minutes is less than 1% m / m.

[0015] Furthermore, the aforementioned adhesive tape for wafer processing preferably has a higher storage elasticity of the first adhesive layer than that of the second adhesive layer.

[0016] Furthermore, the aforementioned adhesive tape for wafer processing is preferably used in wafer processing methods that include a cleaning step involving a wafer with a solvent. [Invention Effects]

[0017] According to the present invention, even when using a wafer processing step that uses a support member, the adhesive on which the support member is attached to the wafer is dissolved in a solvent and the support member is peeled off, or the residual adhesive on the wafer is washed off, so that the wafer is properly maintained and the low yield caused by wafer contamination can be prevented. Implementation

[0018] The embodiments of the present invention will be described in detail below.

[0019] The wafer processing adhesive tape of an embodiment of the present invention is formed by laminating at least one side of a substrate film in the order of at least a first adhesive layer and a second adhesive layer.

[0020] Preferably, the substrate film, the first adhesive layer, and the second adhesive layer are cut (pre-cut) into shapes corresponding to the rings used when wafer fabrication. Furthermore, the wafer processing adhesive tape of the present invention can also be cut into wafer segments, or it can be formed by winding a plurality of elongated diaphragms cut into wafer segments into a roller shape.

[0021] The following is a detailed description of each component of the adhesive tape for wafer processing according to this embodiment.

[0022] (Substrate film) Regarding the resins constituting the substrate film, for example, polypropylene, high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene-propylene copolymer, propylene copolymer, ethylene-propylene-diene copolymer sulfurized, polybutene, polybutadiene, polymethylpentene, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid methyl copolymer, ethylene-(meth)acrylic acid ethyl ester copolymer, ethylene-(meth)acrylic acid butyl ester copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl chloride-vinyl acetate copolymer, polyurethane, polyamide, ionomers, nitrile rubber, butyl rubber, styrene-isoprene rubber, styrene-butadiene rubber, natural rubber and its water additives or modifiers, etc.

[0023] The substrate film is preferably made of a polyolefin resin because it exhibits excellent tensile strength during expansion. Examples of polyolefin resins include individual polymers or copolymers or mixtures of α-olefins such as polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, and ionomers.

[0024] Especially when using ionomer-based thin films, uniform physical properties can be obtained relative to the feed direction and width direction of the substrate film. Accordingly, in the case of expansion and segmentation, the spacing between individual wafers can be made more uniform.

[0025] Furthermore, the substrate film is not limited to a single layer, but can also be a multilayer structure of two or more resins laminated together, or it can be a composite of two or more layers of one type of resin. From the viewpoint that the lamination of one type of resin enhances the properties of each resin, it is preferable that the lamination of two or more resins compensates for the deficiencies of each resin.

[0026] Methods for manufacturing multi-layered substrate films include conventional methods such as extrusion and lamination. When using lamination, an adhesive can be placed between the layers. Conventional adhesives can also be used.

[0027] The thickness of the substrate film is preferably 70~350μm. More preferably 250~300μm. When it is 350μm or more, there is a risk that the wafer may not be able to be picked up from the wafer processing adhesive tape. When it is thinner than 70μm, there is a risk that the wafer processing adhesive tape may break during expansion.

[0028] To improve adhesion, the surface in contact with the first adhesive layer of the substrate film may be treated with corona treatment or a primer.

[0029] (First adhesive layer) The adhesive composition forming the first adhesive layer may be one or more of various rubber-like polymers, including acrylic polymers, rubber polymers, polyester polymers, carbamate polymers, polyether polymers, polysiloxane polymers, polyamide polymers, fluoropolymers, etc., which are known in the field of adhesives, but it must contain at least an acrylic polymer or a polyester polymer as the base polymer.

[0030] The term "acrylic polymer" refers to a polymer in which the monomer units constituting the polymer include monomer units derived from a monomer having at least one (meth)acrylic group in one molecule. Hereinafter, a monomer having at least one (meth)acrylic group in one molecule will also be referred to as an "acrylic monomer." Accordingly, the acrylic polymer defined in this specification is a polymer containing monomer units derived from acrylic monomers. As a typical example of an acrylic polymer, an acrylic polymer in which the proportion of acrylic monomers in the total monomer composition used in the synthesis of the acrylic polymer is more than 50% by weight can be listed. Furthermore, the term "(meth)acrylic" is inclusive, referring to both acrylonitrile and methacrylic. Similarly, the term "(meth)acrylate" is inclusive, referring to both acrylate and methacrylate, and the term "(meth)acrylic" is inclusive, referring to both acrylonitrile and methacrylic.

[0031] The term "polyester polymer" refers to polymers obtained by polycondensation of dicarboxylic acids and diols, which contain repeating ester bonds in their main chain.

[0032] The glass transition temperature of the base polymer constituting the first adhesive is -20°C or higher. Here, glass transition temperature refers to the glass transition temperature measured by DSC (Differential Scanning Calorimeter) at a heating rate of 0.1°C / min. If the glass transition temperature is -20°C or higher, the solvent resistance is sufficient. When peeling the support component from the wafer, and dissolving and cleaning the adhesive with a solvent, the stress applied to the adhesive layer due to wrinkles in the substrate film prevents the adhesive layer from weakening, thus effectively maintaining the wafer. Furthermore, since the first adhesive layer retains the second adhesive layer even when the second adhesive layer is dissolved in a solvent, the second adhesive layer is prevented from detaching, contaminating the wafer, and causing low yield. The glass transition temperature of the base polymer constituting the adhesive is preferably greater than -15°C and less than 1°C, and even more preferably greater than -10°C and less than 1°C.

[0033] The first adhesive layer is preferably a radiation-cured type that hardens upon irradiation. As the adhesive component constituting the first adhesive layer of the radiation-cured type, a polymer constituting the adhesive and a radiation-polymerizable compound can be used together, or a polymer constituting the adhesive can be incorporated with a radiation-polymerizable functional group (preferably an ethylene-unsaturated group). Since it promotes polymerization under radiation, it is preferable to include a photopolymerization initiator. Furthermore, the inclusion of a crosslinking agent is also preferable. By incorporating a monomer having a functional group capable of reacting with a crosslinking agent into the polymer constituting the adhesive, the film hardness or gel fraction can be adjusted. Furthermore, additives or additives other than those mentioned above may also be included if necessary. The following provides a more detailed explanation.

[0034] Examples of acrylic polymers include those that use one or more of the following monomer components: alkyl methacrylates (e.g., methyl esters, ethyl esters, propyl esters, isopropyl esters, butyl esters, isobutyl esters, S-butyl esters, T-butyl esters, pentyl esters, isopentyl esters, hexyl esters, heptyl esters, octyl esters, 2-ethylhexyl esters, isooctyl esters, nonyl esters, decyl esters, isodecanyl esters, undecyl esters, dodecyl esters, tridecyl esters, tetradecyl esters, hexadecyl esters, octadecyl esters, eicosyl esters, etc., in the form of straight-chain or branched-chain alkyl esters with 1 to 30 carbon atoms, especially 4 to 18 carbon atoms) and cycloalkyl methacrylates (e.g., cyclopentyl esters, cyclohexyl esters, etc.). Note that the term "(meth)acrylate" refers to acrylates and / or methacrylates, and has the same meaning as "(methyl)" in this invention.

[0035] Acrylic polymers aim to improve cohesiveness, heat resistance, etc., and may, if necessary, include units corresponding to other monomer components that can be copolymerized with the aforementioned alkyl or cycloalkyl methacrylates. Examples of such monomer components include, for instance, carboxyl-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; anhydride monomers such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and 10-hydroxyethyl (meth)acrylate. Monomers containing hydroxyl groups, such as hydroxydecyl ester, 12-hydroxylaurate (meth)acrylate, and (4-hydroxymethylcyclohexyl)meth(meth)acrylate; monomers containing sulfonic acid groups, such as styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropane sulfonic acid, (meth)acrylamide propane sulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloxynaphthalene sulfonic acid; monomers containing phosphate groups, such as 2-hydroxyethylacrylamide phosphate; acrylamide, acrylonitrile, etc. One or more of these copolymerizable monomers may be used. Preferably, the amount of these copolymerizable monomers used is less than 40% by weight of the total monomer composition.

[0036] Furthermore, since acrylic polymers undergo crosslinking, multifunctional monomers may be included as copolymerizing monomers if necessary. Examples of such multifunctional monomers include hexanediol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, pentaerythritol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexamethacrylate, epoxy methacrylate, polyester methacrylate, and urethane methacrylate. One or more of these multifunctional monomers may be used. From the perspective of adhesive properties, the amount of multifunctional monomer used is preferably 30% by weight or less of the total monomer composition.

[0037] The preparation of acrylic polymers can be carried out by appropriate methods such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization for mixtures of one or more component monomers.

[0038] Furthermore, to control the crosslinking density of the first adhesive layer, appropriate external crosslinking agents can be used for crosslinking treatment, such as polyfunctional isocyanate compounds, polyfunctional epoxy compounds, melamine compounds, metal salt compounds, metal chelating agent compounds, amine resin compounds, or peroxides. Alternatively, appropriate methods can be employed, such as mixing low-molecular-weight compounds with two or more carbon-carbon double bonds and crosslinking them through radiation irradiation. When using an external crosslinking agent, its amount is appropriately determined by balancing it with the base polymer to be crosslinked, and further, by its intended use as an adhesive. Generally, it is preferable to blend about 20 parts by weight or less, or even 0.1 to 20 parts by weight, relative to 100 parts by weight of the aforementioned base polymer. Additionally, from the viewpoint of preventing degradation, various adhesive additives, anti-aging agents, etc., can be used in the adhesive as needed, in addition to the aforementioned components.

[0039] As the adhesive constituting the first adhesive layer, a radiation-curing adhesive is suitable. Examples of radiation-curing adhesives include the aforementioned adhesives, and additive-type radiation-curing adhesives incorporating radiation-curing monomeric components or radiation-curing oligomeric components.

[0040] Examples of radiohardening monomeric components that can be incorporated include urethane (meth)acrylates, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butanediol di(meth)acrylate. One or more of these monomeric components may be used in combination.

[0041] Furthermore, the radiation-curing oligomer components can include various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, with a molecular weight range of approximately 100 to 30,000 being suitable. The amount of radiation-curing monomer or oligomer components incorporated can be appropriately determined according to the type of the first adhesive layer, thereby reducing the adhesive strength of the first adhesive layer. Generally, relative to 100 parts by weight of the base polymer such as acrylic polymer constituting the adhesive, it is, for example, 5 to 500 parts by weight, preferably 70 to 150 parts by weight.

[0042] Furthermore, in addition to the aforementioned additive-type radiation-curing adhesives, intrinsic radiation-curing adhesives, in which radiation-curing groups are incorporated into the polymer side chains or main chains or at the ends of the main chains, can also be used as the base polymer. Intrinsic radiation-curing adhesives are preferable because they do not require or contain many low-molecular-weight oligomer components, and therefore, over time, these oligomer components do not migrate into the adhesive, forming a stable first adhesive layer.

[0043] The base polymer for incorporating radiation-curing groups is not particularly limited to those having carbon-carbon double bonds and adhesive properties. Preferably, an acrylic polymer is used as the basic backbone. Examples of acrylic polymers exemplified above can be cited as examples of the basic backbone of an acrylic polymer.

[0044] There are no particular limitations on the methods for introducing radiocuring groups into acrylic polymers. Although various methods can be used, it is relatively easy to introduce radiocuring groups into the polymer side chains in terms of molecular design. For example, one method is to first copolymerize a monomer with a functional group into the acrylic polymer, and then directly maintain the radiocuring property of the carbon-carbon double bond by condensation or addition reactions with a compound that has a functional group that can react with this functional group and a carbon-carbon double bond.

[0045] Examples of combinations of these functional groups include carboxylic acid groups and epoxy groups, carboxylic acid groups and aziridinyl groups, and hydroxyl groups and isocyanate groups. Among these combinations of functional groups, the combination of hydroxyl and isocyanate groups is suitable due to the ease of reaction tracing. Furthermore, if the combination of these functional groups results in the formation of the aforementioned acrylic polymer having a carbon-carbon double bond, the functional group can be on either side of the acrylic polymer or the aforementioned compound. However, the preferred combination is one where the acrylic polymer has a hydroxyl group and the aforementioned compound has an isocyanate group. In this case, examples of isocyanate compounds having a carbon-carbon double bond include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Also, the acrylic polymer is produced by copolymerizing the aforementioned monomers containing hydroxyl groups or ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0046] While intrinsic radiation-curing adhesives can be made solely from the aforementioned base polymers (especially acrylic polymers) containing carbon-carbon double bonds, they can also be incorporated with photopolymerizable compounds, such as the aforementioned radiation-curing monomeric or oligomeric components, to a degree that does not degrade their properties. The amount of this photopolymerizable compound incorporated is typically in the range of 30 parts by weight or less per 100 parts by weight of the base polymer, preferably in the range of 0 to 10 parts by weight.

[0047] In radiation-curing adhesives, it is preferable to contain a photopolymerization initiator when curing by ultraviolet light or the like.

[0048] Among the aforementioned acrylic polymers, especially (meth)acrylate copolymers with radiation-hardening groups introduced into the side chains, more specifically, preferably (meth)acrylate copolymers comprising an acrylate represented by CH2=CHCOOR (where R is an alkyl group with 4 to 18 carbon atoms), a monomer containing hydroxyl groups, and an isocyanate compound having a free radical reactive carbon-carbon double bond within the molecule.

[0049] The preferred carbon-carbon double bond content is 1.2~1.8 meq / g. Regarding the double bond content, the amount of carbon-carbon double bonds contained in approximately 10g of heated and dried adhesive can be quantitatively determined by the gravimetric method of bromine addition reaction in a vacuum and in the dark.

[0050] The above-mentioned (meth)acrylate copolymer may contain units corresponding to other monomer components, if necessary.

[0051] Examples of isocyanate compounds containing double bonds include methacrylamide isocyanate, acrylamide isocyanate, 2-methacryloxyethyl isocyanate, 2-acryloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Two or more isocyanate compounds containing double bonds can be used alone or in combination.

[0052] Furthermore, in radiation-curing adhesives, external crosslinking agents can be appropriately used to adjust the adhesion before or after radiation irradiation. Specific methods of external crosslinking include adding so-called crosslinking agents such as polyisocyanate compounds, epoxy compounds, aziridine compounds, and melamine-based crosslinking agents to induce a reaction. When using an external crosslinking agent, its amount is appropriately determined by balancing it with the base polymer to be crosslinked, and further by its intended use as an adhesive. Generally, the amount of external crosslinking agent used is 20 parts by weight or less (preferably 0.1 to 10 parts by weight) relative to 100 parts by weight of the aforementioned base polymer. Furthermore, in addition to the aforementioned components, various known adhesive additives, anti-aging agents, foaming agents, etc., can be incorporated into radiation-curing adhesives as needed.

[0053] The polyester used in polyester-based polymers is preferably a polyester obtained by condensation polymerization of a carboxylic acid component with two or more functions and a diol component, wherein the weight average molecular weight of the aforementioned polyester is 8,500 to 50,000. Furthermore, the aforementioned polyester preferably contains at least a carboxylic acid component with two or more functions, wherein the aforementioned carboxylic acid component is a dicarboxylic acid component having two carboxyl groups in the molecule.

[0054] While there are no particular limitations on the aforementioned dicarboxylic acids, examples include sebacic acid derived from castor oil or dimer acids derived from oleic acid, erucic acid, etc. Other examples include adipic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecenylsuccinic anhydride, fumaric acid, succinic acid, dodecanoic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, itaconic acid, citraconic acid, etc. (aliphatic or alicyclic dicarboxylic acids), or terephthalic acid, isophthalic acid, phthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, etc. Dimer acids, in particular, have low glass transfer temperatures, allowing for the design of flexible adhesives, thus exhibiting good wetting properties and becoming a preferred option. Furthermore, dimer acids are useful because they are derived from non-petroleum materials (plant-based raw materials), which is environmentally friendly. These can be used alone or in combination of two or more.

[0055] Furthermore, the aforementioned polyester contains a diol component, which preferably contains at least two hydroxyl groups (hydroxyl groups) in the molecule. Aliphatic diols or polyether diols are preferred.

[0056] As for the aforementioned aliphatic diols, aliphatic diols having an alkyl group having 3 to 10 carbon atoms are particularly preferred. While there are no particular limitations on the aliphatic diols having an alkyl group having 3 to 10 carbon atoms, specific examples include 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentanediol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,5-pentanediol, 2-ethyl-2-butylpropanediol, 1,9-nonanediol, 2-methyloctanediol, 1,10-decanediol, 1,4-cyclohexanediethanol, and 1,2-cyclohexanediethanol. These can be used individually or in combination of two or more.

[0057] Furthermore, while there are no particular limitations on the aforementioned polyether glycols, polyether glycols with hydroxyl groups at both ends are preferred. The number average molecular weight (Mn) of the polyether glycol with hydroxyl groups at both ends is not particularly limited; specifically, polytetramethylene ether glycol or polytrimethylene ether glycol, polyalkylene ether glycols, 1-20 moles of a copolymer of 3-methyltetrahydrofuran and tetrahydrofuran (e.g., "PTG-L1000," "PTG-L2000," "PTG-L3500," etc. manufactured by Hodogaya Chemical Co., Ltd.), or a copolymer of neopentyl glycol and tetrahydrofuran are preferred. One or more of these can be used.

[0058] The aforementioned polyester-based polycondensation carboxylic acid component and glycol component are obtained. The molar ratio (OH / COOH) of the carboxyl group of the carboxylic acid component to the hydroxyl group of the glycol component is preferably 1 or more, more preferably 1.02 to 3, even more preferably 1.04 to 2.60, and particularly preferably 1.06 to 2.40. If the aforementioned molar ratio is less than 1, there is a risk that the polymerized polyester (polymer) ends with carboxyl groups, making rapid cross-linking by a cross-linking agent (e.g., an isocyanate-based cross-linking agent) impossible, and also, there is a risk that the adhesive layer's retaining force (cohesive force) may not be sufficiently obtained.

[0059] Alternatively, other components besides the aforementioned carboxylic acid components or diol components can be polymerized, or added after polymerization.

[0060] The synthesis method of the aforementioned polyester is not particularly limited and can use any known polymerization method. Furthermore, the polymerization (condensation polymerization) of the carboxylic acid component and the diol component can be carried out using a solvent, or under reduced pressure without solvent, or using conventionally known methods.

[0061] When a polyester polymer is used as the base polymer, the adhesive composition of the first adhesive layer preferably contains, along with the aforementioned polyester polymer, a fatty acid ester with a molecular weight (molar molecular weight: g / molar) of 200 to 700 without functional groups. Examples of fatty acid esters include isopropyl myristate, isopropyl palmitate, methyl linoleate, adipate, sebate, and phthalate, which are dicarboxylic acid esters. One or more of these can be used. The amount of fatty acid ester incorporated is preferably 10 to 150 parts by weight relative to 100 parts by weight of the aforementioned polyester polymer, more preferably 20 to 150 parts by weight, even more preferably 30 to 140 parts by weight, and still more preferably 40 to 130 parts by weight.

[0062] Furthermore, the adhesive composition, together with the aforementioned polyester polymer, contains a crosslinking agent. The crosslinking agent is not particularly limited and can be any known agent, such as isocyanate-based crosslinking agents (e.g., polyvalent isocyanurates or polyfunctional isocyanate compounds), polyfunctional melamine compounds, polyfunctional epoxy compounds, polyfunctional oxazoline compounds, polyfunctional aziridine compounds, metal chelating agents, etc. One or more of these can be used.

[0063] In particular, isocyanate-based crosslinking agents using polyisocyanates or polyfunctional isocyanates, as previously known, are preferred. Examples of polyisocyanates include polyisocyanates of hexamethylene diisocyanate. As for polyfunctional isocyanate compounds, compounds having at least two or more isocyanate groups in the molecule are preferred, more preferably three or more, but there are no particular limitations. Specifically, examples include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

[0064] The thickness of the first adhesive layer is preferably 5 μm to 70 μm, more preferably 5 μm to 30 μm, and even more preferably 5 μm to 15 μm. If the adhesive layer is thinner than 5 μm, there is a risk that sufficient adhesive force may not be achieved. On the other hand, if the adhesive layer is thicker than 70 μm, there is a risk that the force during expansion may not be sufficiently transmitted to the wafer, making it impossible to cleave the wafer into wafers.

[0065] The method for forming the first adhesive layer on the substrate film is not particularly limited. For example, in addition to coating the substrate film with the adhesive composition as described above and drying it, the adhesive layer coated on the diaphragm can be bonded to the substrate film and then transferred to the substrate film to form the adhesive layer.

[0066] (Second adhesive layer) The adhesive composition forming the second adhesive layer, as the base polymer, may be one or more of various rubber-like polymers including acrylic polymers, rubber polymers, polyester polymers, carbamate polymers, polyether polymers, polysiloxane polymers, polyamide polymers, fluoropolymers, etc., which are known in the field of adhesives.

[0067] The second adhesive layer is preferably a radiation-cured type that hardens upon irradiation. As an adhesive component constituting the second adhesive layer in the radiation-cured type, a polymer constituting the adhesive and a radiation-polymerizable compound can be used together, or a polymer constituting the adhesive can be incorporated with a radiation-polymerizable functional group (preferably an ethylene-unsaturated group). To promote polymerization under radiation, a photopolymerization initiator is preferably included. Furthermore, a crosslinking agent is also preferred. By incorporating a monomer having a functional group capable of reacting with the crosslinking agent into the polymer constituting the adhesive, the film hardness or gel fraction can be adjusted. Furthermore, additives or additives other than those mentioned above may be included if necessary. The following provides a more detailed explanation.

[0068] Examples of acrylic polymers include those that use one or more of the following monomer components: alkyl methacrylates (e.g., methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, S-butyl acrylate, T-butyl acrylate, pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, nonyl acrylate, decyl acrylate, isodecanyl acrylate, undecyl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, hexadecyl acrylate, octadecyl acrylate, eicosyl acrylate, etc., in the form of straight-chain or branched-chain alkyl esters with 1 to 30 carbon atoms, especially 4 to 18 carbon atoms) and cycloalkyl methacrylates (e.g., cyclopentyl acrylate, cyclohexyl acrylate, etc.). Note that the term "(meth)acrylate" refers to acrylates and / or methacrylates, and has the same meaning as "(methyl)" in this invention.

[0069] Acrylic polymers aim to improve cohesiveness, heat resistance, etc., and may, if necessary, include units corresponding to other monomer components that can be copolymerized with the aforementioned alkyl or cycloalkyl methacrylates. Examples of such monomer components include, for instance, carboxyl-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; anhydride monomers such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and 10-hydroxyethyl (meth)acrylate. Monomers containing hydroxyl groups, such as hydroxydecyl ester, 12-hydroxylaurate (meth)acrylate, and (4-hydroxymethylcyclohexyl)meth(meth)acrylate; monomers containing sulfonic acid groups, such as styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropane sulfonic acid, (meth)acrylamide propane sulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloxynaphthalene sulfonic acid; monomers containing phosphate groups, such as 2-hydroxyethylacrylamide phosphate; acrylamide, acrylonitrile, etc. One or more of these copolymerizable monomers may be used. Preferably, the amount of these copolymerizable monomers used is less than 40% by weight of the total monomer composition.

[0070] Furthermore, since acrylic polymers undergo crosslinking, multifunctional monomers may be included as copolymerizing monomers if necessary. Examples of such multifunctional monomers include hexanediol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, pentaerythritol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexamethacrylate, epoxy methacrylate, polyester methacrylate, and urethane methacrylate. One or more of these multifunctional monomers may be used. From the perspective of adhesive properties, the amount of multifunctional monomer used is preferably 30% by weight or less of the total monomer composition.

[0071] The preparation of acrylic polymers can be carried out by appropriate methods such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization for mixtures of one or more component monomers.

[0072] Furthermore, to control the crosslinking density of the second adhesive layer, appropriate external crosslinking agents can be used for crosslinking treatment, such as polyfunctional isocyanate compounds, polyfunctional epoxy compounds, melamine compounds, metal salt compounds, metal chelating agent compounds, amine resin compounds, or peroxides. Alternatively, appropriate methods can be employed, such as mixing low-molecular-weight compounds with two or more carbon-carbon double bonds and crosslinking them through radiation irradiation. When using an external crosslinking agent, its amount is determined appropriately based on the balance with the base polymer to be crosslinked and the intended use as an adhesive. Generally, it is preferable to blend approximately 20 parts by weight or less, or even 0.1 to 20 parts by weight, relative to 100 parts by weight of the aforementioned base polymer. Additionally, from the viewpoint of preventing degradation, various adhesive additives, anti-aging agents, etc., can be used in the adhesive as needed, in addition to the aforementioned components.

[0073] As the adhesive constituting the second adhesive layer, a radiation-curing adhesive is suitable. Examples of radiation-curing adhesives include the aforementioned adhesives, and additive-type radiation-curing adhesives incorporating radiation-curing monomeric components or radiation-curing oligomeric components.

[0074] Examples of radiohardening monomeric components that can be incorporated include urethane (meth)acrylates, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butanediol di(meth)acrylate. One or more of these monomeric components may be used in combination.

[0075] Furthermore, the radiation-curing oligomer components can include various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, with a molecular weight range of approximately 100 to 30,000 being suitable. The amount of radiation-curing monomer or oligomer components incorporated can be appropriately determined according to the type of the first adhesive layer to reduce the adhesive force of the first adhesive layer. Generally, relative to 100 parts by weight of the base polymer such as acrylic polymer constituting the adhesive, it is, for example, 5 to 500 parts by weight, preferably about 70 to 150 parts by weight.

[0076] Furthermore, in addition to the aforementioned additive-type radiation-curing adhesives, intrinsic radiation-curing adhesives, in which radiation-curing groups are incorporated into the polymer side chains or main chains or at the ends of the main chains, can also be used as the base polymer. Intrinsic radiation-curing adhesives are preferable because they do not require or contain many low-molecular-weight oligomer components, and therefore, over time, these oligomer components do not migrate into the adhesive, forming a stable first adhesive layer.

[0077] The base polymer for incorporating radiation-curing groups is not particularly limited to those having carbon-carbon double bonds and adhesive properties. Preferably, an acrylic polymer is used as the basic backbone. Examples of acrylic polymers exemplified above can be cited as examples of the basic backbone of an acrylic polymer.

[0078] There are no particular limitations on the methods for introducing radiocuring groups into acrylic polymers. Although various methods can be used, introducing radiocuring groups into the polymer side chains is easier in terms of molecular design. For example, one method can be listed whereby, after copolymerizing a monomer with a functional group into the acrylic polymer, a compound with a functional group that can react with this functional group and a carbon-carbon double bond is directly subjected to a condensation or addition reaction to maintain the radiocuring property of the carbon-carbon double bond.

[0079] Examples of combinations of these functional groups include carboxylic acid groups and epoxy groups, carboxylic acid groups and aziridinyl groups, and hydroxyl groups and isocyanate groups. Among these combinations of functional groups, the combination of hydroxyl and isocyanate groups is suitable due to the ease of reaction tracing. Furthermore, if the combination of these functional groups results in the formation of the aforementioned acrylic polymer having a carbon-carbon double bond, the functional group can be on either side of the acrylic polymer or the aforementioned compound. However, the preferred combination is one where the acrylic polymer has a hydroxyl group and the aforementioned compound has an isocyanate group. In this case, examples of isocyanate compounds having a carbon-carbon double bond include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Also, the acrylic polymer is produced by copolymerizing the aforementioned monomers containing hydroxyl groups or ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0080] While intrinsic radiation-curing adhesives can be made solely from the aforementioned base polymers (especially acrylic polymers) containing carbon-carbon double bonds, they can also be incorporated with photopolymerizable compounds, such as the aforementioned radiation-curing monomeric or oligomeric components, to a degree that does not degrade their properties. The amount of this photopolymerizable compound incorporated is typically in the range of 30 parts by weight or less per 100 parts by weight of the base polymer, preferably in the range of 0 to 10 parts by weight.

[0081] In radiation-curing adhesives, it is preferable to contain a photopolymerization initiator when curing by ultraviolet light or the like.

[0082] Among the aforementioned acrylic polymers, especially (meth)acrylate copolymers with radiation-hardening groups introduced into the side chains, more specifically, preferably (meth)acrylate copolymers comprising an acrylate represented by CH2=CHCOOR (where R is an alkyl group with 4 to 18 carbon atoms), a monomer containing hydroxyl groups, and an isocyanate compound having a free radical reactive carbon-carbon double bond within the molecule.

[0083] The preferred carbon-carbon double bond content is 1.2~1.8 meq / g. Regarding the double bond content, the amount of carbon-carbon double bonds contained in approximately 10g of heated and dried adhesive can be quantitatively determined by the gravimetric method of bromine addition reaction in a vacuum and in the dark.

[0084] The above-mentioned (meth)acrylate copolymer may contain units corresponding to other monomer components, if necessary.

[0085] Examples of isocyanate compounds containing double bonds include methacrylamide isocyanate, acrylamide isocyanate, 2-methacryloxyethyl isocyanate, 2-acryloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Two or more isocyanate compounds containing double bonds can be used alone or in combination.

[0086] Furthermore, in radiation-curing adhesives, external crosslinking agents can be appropriately used to adjust the adhesion before or after radiation irradiation. Specific methods of external crosslinking include adding so-called crosslinking agents such as polyisocyanate compounds, epoxy compounds, aziridine compounds, and melamine-based crosslinking agents to induce a reaction. When using an external crosslinking agent, its amount is appropriately determined by balancing it with the base polymer to be crosslinked, and further by its intended use as an adhesive. Generally, the amount of external crosslinking agent used is 20 parts by weight or less (preferably 0.1 to 10 parts by weight) relative to 100 parts by weight of the aforementioned base polymer. Furthermore, in addition to the aforementioned components, various known adhesive additives, anti-aging agents, foaming agents, etc., can be incorporated into radiation-curing adhesives as needed.

[0087] Furthermore, although wafer processing adhesive tape is applied to the milled surface of the wafer after back-side grinding and polishing but before the support components are removed, there is a problem that peeling off the wafer processing adhesive tape becomes difficult when it is applied to the wafer surface immediately after back-side grinding before the oxide film is formed. Therefore, even when applying it to the wafer surface immediately after back-side grinding before the oxide film is formed, it is preferable to add polypropylene oxide to the adhesive of the second adhesive layer to facilitate peeling.

[0088] There are no particular limitations on the polypropylene oxide used; it can be appropriately selected from conventional polypropylene oxides. The number-average molecular weight of the polypropylene oxide is preferably greater than 3000 and less than 10000, more preferably 4000-10000. If the number-average molecular weight of the polypropylene oxide is too high, the affinity between the polypropylene oxide and the aforementioned acrylic polymer (X) deteriorates, resulting in contamination of the adherend. If the number-average molecular weight of the polypropylene oxide is too low, the water resistance of the adhesive layer becomes insufficient, and cutting water swells the adhesive layer, resulting in a meandering cut line.

[0089] From the perspective of wafer contamination, polyoxypropylene-glycerol ethers with a number average molecular weight greater than 3000 and below 10000, preferably between 4000 and 10000, are preferable. By using polyoxypropylene-glycerol ethers with a number average molecular weight in this range, the number of hydroxyl groups within the polyoxypropylene molecule increases from 2 to 3. Therefore, through reaction with crosslinking agents such as polyisocyanates, the possibility of incorporating polyoxypropylene into the crosslinked structure is increased, and the movement of polyoxypropylene to the wafer interface can reduce wafer surface contamination.

[0090] Examples of polypropylene oxides with a number average molecular weight greater than 3000 but less than 10000 include UNIOL D-4000 (number average molecular weight 4000) (trade name, manufactured by Nippon Yuko Co., Ltd.), PREMINOL S4007 (number average molecular weight 5000) (trade name, manufactured by Asahi Glass Co., Ltd.), and PREMINOL S4011 (number average molecular weight 10000) (trade name, manufactured by Asahi Glass Co., Ltd.). Examples of polypropylene-glycerol ethers with a number average molecular weight greater than 3000 but less than 10000 include UNIOL TG-4000 (number average molecular weight 4000) (trade name, manufactured by Nippon Yuko Co., Ltd.), PREMINOL S3006 (number average molecular weight 5000) (trade name, manufactured by Asahi Glass Co., Ltd.), and PREMINOL S3011 (number average molecular weight 10000) (trade name, manufactured by Asahi Glass Co., Ltd.), but these are not limited to these types.

[0091] The amount of polypropylene oxide used for wafers with a number average molecular weight greater than 3000 and less than 10000 can be appropriately selected from a range of 0.1 to 3.0 parts by mass relative to 100 parts by mass of the substrate polymer, preferably 0.5 to 2.0 parts by mass. If the amount of polypropylene oxide is too low, the unstable wafer grinding surface, where the natural oxide film has not fully formed, makes it difficult to efficiently pick up thin semiconductor wafers from large-diameter wafers when using adhesive tape for wafer processing. If the amount of polypropylene oxide is too high, the adhesion before radiation curing becomes insufficient, leading to wafer tip peeling during dicing and the adhesion of cutting dust to the back of the wafer.

[0092] Furthermore, in this invention, when the process is defined as "laminating in the order of substrate film, first adhesive layer, and second adhesive layer," it also includes a configuration where other layers are further laminated between the first adhesive layer and the second adhesive layer. In this case, the adhesive layer in contact with the substrate film is composed of the aforementioned first adhesive layer, and the adhesive layer bonded to the semiconductor wafer is composed of the aforementioned second adhesive layer.

[0093] The thickness of the second adhesive layer is preferably 5 μm to 30 μm, more preferably 5 μm to 20 μm. If the adhesive layer is thinner than 5 μm, there is a risk that sufficient adhesion may not be achieved. On the other hand, if the adhesive layer is thicker than 30 μm, there is a risk of adhesive residue adhering to the semiconductor wafer.

[0094] The method of forming the second adhesive layer on the first adhesive layer or other layers is not particularly limited. By coating the adhesive composition of the second adhesive layer onto a release liner (e.g., a plastic film or sheet coated with a release agent), forming the second adhesive layer, and then laminating it onto the first adhesive layer or other layers disposed on the substrate film, an adhesive tape for wafer processing can be obtained.

[0095] The storage elasticity G' of the first adhesive layer is preferably higher than that of the second adhesive layer. The storage elasticity G' is determined by repeatedly preparing multiple adhesive layers formed on a known release film, performing two-layer lamination, peeling off a single-sided release film, and further laminating one layer to create a test piece with a thickness of 1-2 mm. The test piece is then measured using a dynamic viscoelasticity tester at 23°C and a frequency of 1 Hz. Furthermore, the storage elasticity is measured with respect to the adhesive layer before radiation exposure.

[0096] The storage elastic modulus G' of the first adhesive layer is preferably 5×10⁴ Pa to 100×10⁴ Pa, more preferably 5×10⁴ to 80×10⁴ Pa, and even more preferably 10×10⁴ to 70×10⁴ Pa. If the storage elastic modulus G' of the first adhesive layer is 30×10⁴ Pa or higher, the solvent resistance is sufficient. When the support component is peeled off from the wafer, and the adhesive is dissolved and cleaned with a solvent, the stress applied to the adhesive layer by the wrinkles generated in the substrate film can prevent the adhesion of the adhesive layer from weakening, thus effectively maintaining the wafer. Furthermore, even if the second adhesive layer is dissolved in a solvent, the first adhesive layer retains the second adhesive layer, thus preventing the second adhesive layer from falling off, contaminating the wafer, and causing low yield.

[0097] The storage elasticity G' of the second adhesive layer is preferably 5×10⁴ Pa to 40×10⁴ Pa, more preferably 5×10⁴ to 20×10⁴ Pa, and even more preferably 5×10⁴ to 10×10⁴ Pa. When the storage elasticity G' of the second adhesive layer is higher than 10×10⁴ Pa, there is a risk that the ability to follow the steps on a wafer with surface steps will be insufficient, and the wafer may not be able to be adequately maintained.

[0098] For wafer processing adhesive tape, it is preferable that after applying 1 ml of p-menthane to the surface of the second adhesive layer and allowing it to stand for 30 minutes, the residual solvent content is less than 1% (m / m). If the residual solvent content is less than 1% (m / m), when the adhesive used to bond the support member to the wafer is dissolved in the solvent, or when the support member is peeled off and the residual adhesive on the wafer is washed away, wrinkles are generated on the substrate film of the wafer processing adhesive tape, applying stress to the adhesive layer. This prevents the adhesive layer from becoming weak and ensures adequate wafer retention. Furthermore, even if the second adhesive layer of the wafer processing adhesive tape is dissolved in the solvent, the first adhesive layer retains the second adhesive layer, thus preventing the second adhesive layer from detaching, contaminating the wafer, and causing low yield.

[0099] <Determination of Residual Solvent Content> After the adhesive tape for wafer fabrication is prepared (after tape formation), it is cut into 40 mm square pieces. The release liner is peeled off, 1 mL of p-menthane is added, and the mixture is allowed to stand for 30 minutes. Then, the solvent is discarded, and the mixture is dried at room temperature for 30 minutes. 1.0 g of the cut adhesive layer sample is immersed in 10 mL of acetone. The supernatant is analyzed by gas chromatography-mass spectrometry (GC-MS) under the following conditions. [Analysis Conditions] Injection volume: 1μL Tubing string: db-1 0.25mm × 30m Inj: 200℃ (after holding at 40℃ for 4 minutes, increase the temperature to 200℃ at a rate of 20℃ / min) He flow rate: 1.0 mL / min

[0100] In order to keep the residual solvent content below 1% and m / m, the glass transfer temperature of the base polymer of the second adhesive layer can be set to above -20°C.

[0101] For wafer fabrication adhesive tapes, if necessary until they are put into practical use, a synthetic resin film, typically used as a separator, can be attached to the adhesive layer side to protect the adhesive layer. Examples of materials for the synthetic resin film include synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate, or paper. To improve peelability from the adhesive layer, the surface of the synthetic resin film may be treated with release treatments such as polysiloxane treatment, long-chain alkyl treatment, or fluorine treatment, if necessary. The thickness of the synthetic resin film is typically 10–100 μm, preferably around 25–50 μm.

[0102] (Through the dissolution of the adhesive by the solvent and the cleaning of the wafer) When peeling the wafer from the support member, wafer processing adhesive tape and a ring are attached to the side of the support member that is not attached to the wafer. Then, the wafer and support member supported by the wafer processing adhesive tape and ring are immersed in an organic solvent to dissolve the adhesive that holds the support member to the wafer, peel off the support member, and wash the surface of the wafer where the adhesive is attached. In addition to the methods described above, to peel the wafer from the support member, there are also methods such as heating to soften the adhesive and allowing the support member to slide for peeling, or using laser light to decompose the adhesive for peeling. Even when using these methods, adhesive or its decomposition products may remain on the wafer surface after peeling off the support member. Therefore, to remove these residues, the wafer supported by the wafer processing adhesive tape and ring may be immersed in an organic solvent for washing, or the wafer may be washed by blowing organic solvent onto it while rotating it.

[0103] The adhesive tape for electronic components invented in this case includes the following forms.

[0104] [1] An adhesive tape for wafer processing, comprising at least a substrate film, a first adhesive layer, and a second adhesive layer laminated in this order, characterized in that... The first adhesive layer is formed by an adhesive composition comprising an acrylic polymer or a polyester polymer as the base polymer. The glass transfer temperature of the base polymer is above -20°C.

[0105] [2] As described in [1], the adhesive tape for wafer processing, wherein the substrate film is composed of polyolefin resin.

[0106] [3] The adhesive tape for wafer processing as described in [1] or [2], wherein the thickness of the substrate film is 70~350μm.

[0107] [4] The wafer processing adhesive tape described in any of [1] to [3], wherein 1 ml of p-menthane is dropped onto the surface of the second adhesive layer and the residual solvent content after standing for 30 minutes is less than 1%, m / m.

[0108] [5] As described in any of [1] to [4], the adhesive tape for wafer processing has a higher storage elasticity than the storage elasticity of the second adhesive layer.

[0109] [6] The wafer processing adhesive tape described in any of [1] to [5] is used in a wafer processing method that includes a cleaning step of the wafer by means of a solvent.

[0110] Next, the present invention will be further described in detail with reference to embodiments. Although the present invention will be described below by way of embodiments, the present invention is not limited to these embodiments.

[0111] (1) Fabrication of substrate film <Substrate Film 1> The substrate film 1 was made by using an ethylene-vinyl acetate copolymer (trade name "NUC-3660" manufactured by NUC Corporation), melting it at 140°C, and forming it with a thickness of 80 μm using an extruder. <Substrate Film 2> Ethylene-methacrylate-(2-methyl-propyl acrylate)-Zn++ ionomer resin (manufactured by Mitsui & DuPont Polychemicals Co., Ltd., trade name "HIMILAN AM7316") was melted at 140°C and shaped using an extruder to a thickness of 350 μm to form a substrate film 2. <Substrate Film 3> Polypropylene (manufactured by Prime Polymer Co., Ltd., trade name "F227D") was melted at 140°C and shaped using an extruder to a thickness of 70 μm to form a substrate film 3.

[0112] (2) Preparation of adhesive <Adhesive 1> An acrylic copolymer composed of ethyl acrylate (81 wt%), methacrylic acid (1 wt%), and 2-hydroxyethyl acrylate (18 wt%) was prepared. Then, 2-methacryloxyethyl isocyanate was added, causing the terminal OH group of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer to react with the NCO group of the 2-methacryloxyethyl isocyanate, resulting in an acrylic polymer as a base polymer. This base polymer has residues of a (meth)acrylic monomer portion bonded to the repeating unit of the main chain, containing a group with a radioactive carbon-carbon double bond. The glass transition temperature of this acrylic polymer, measured by differential scanning calorimetry (DSC), was -20°C. For every 100 parts by weight of the acrylic polymer, 2 parts by weight of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "CORONATE L") and 1.5 parts by weight of a photopolymerization initiator (manufactured by BASF Corporation, trade name "Irgacure 184") were added and mixed to obtain an acrylic adhesive 1.

[0113] <Adhesive 2> As the base polymer, an adhesive comprising a polyester polymer was prepared, namely Nichigo-POLYESTER (registered trademark) S-0097S55EO manufactured by Mitsubishi Chemical Corporation. The glass transition temperature of the polyester polymer as the base polymer was 1°C. 3 parts by weight of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "CORONATE L") were added to 100 parts by weight of the polyester polymer and mixed to obtain polyester adhesive 2.

[0114] <Adhesive 3> An acrylic copolymer composed of 2-ethylhexyl acrylate (69 wt%), methyl methacrylate (10 wt%), 2-hydroxyethyl acrylate (20 wt%), and methacrylic acid (1 wt%) was prepared. Then, 2-methacryloxyethyl isocyanate was added, causing the terminal OH group of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer to react with the NCO group of the 2-methacryloxyethyl isocyanate, yielding an acrylic polymer as the base polymer. This polymer has residues of a (meth)acrylic monomer portion bonded to the repeating unit of the main chain, containing a group containing a radiation-hardening carbon-carbon double bond. The glass transition temperature of this acrylic polymer, measured using a differential scanning calorimeter (DSC), was -50°C. To obtain polyester adhesive 3, 2 parts by weight of polyisocyanate compound (manufactured by Tosoh Corporation, trade name "CORONATE L") and 1.5 parts by weight of photopolymerization initiator (manufactured by BASF Corporation, trade name "Irgacure 184") were added to 100 parts by weight of acrylic polymer.

[0115] <Adhesive 4> An acrylic copolymer composed of 2-ethylhexyl acrylate (78 wt%), methacrylic acid (1 wt%), and 2-hydroxyethyl acrylate (21 wt%) was prepared. Then, 2-methacryloxyethyl isocyanate was added, causing the terminal OH groups of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer to react with the NCO groups of 2-methacryloxyethyl isocyanate, resulting in an acrylic polymer as a base polymer having residues of (meth)acrylic monomers bonded to the repeating units of the main chain, containing groups with radioactive carbon-carbon double bonds. The glass transition temperature of this acrylic polymer, measured by differential scanning calorimetry (DSC), was -64°C. For every 100 parts by weight of the acrylic polymer, 2 parts by weight of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "CORONATE L") and 1.5 parts by weight of a photopolymerization initiator (manufactured by BASF Corporation, trade name "Irgacure 184") were added and mixed to obtain a polyester-based adhesive 4.

[0116] <Adhesive 5> An acrylic copolymer composed of butyl acrylate (70 wt%), methacrylic acid (1 wt%), and 2-hydroxyethyl acrylate (29 wt%) was prepared. Then, 2-methacryloxyethyl isocyanate was added, causing the terminal OH groups of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer to react with the NCO groups of 2-methacryloxyethyl isocyanate, resulting in an acrylic polymer as a base polymer having residues of (meth)acrylic monomers bonded to the repeating units of the main chain containing radioactive carbon-carbon double bonds. The glass transition temperature of this acrylic polymer, measured by differential scanning calorimetry (DSC), was -45°C. For every 100 parts by weight of the acrylic polymer, 2 parts by weight of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "CORONATE L") and 1.5 parts by weight of a photopolymerization initiator (manufactured by BASF Corporation, trade name "Irgacure 184") were added and mixed to obtain a polyester-based adhesive 5.

[0117] <Adhesive 6> An acrylic copolymer composed of 62 wt% methacrylate, 6 wt% acrylic acid, 4 wt% 2-hydroxyethyl acrylate, and 28 wt% 2-ethylhexyl acrylate was prepared to obtain an acrylic polymer as the base polymer. The glass transition temperature of this acrylic polymer, measured by differential scanning calorimetry (DSC), was -10°C. 2 parts by weight of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "CORONATE L") were mixed with 100 parts by weight of the acrylic polymer to obtain a polyester adhesive 6.

[0118] <Adhesive 7> An acrylic copolymer composed of methyl methacrylate (25 wt%), 2-ethylhexyl acrylate (54 wt%), methacrylic acid (1 wt%), and 2-hydroxyethyl acrylate (20 wt%) was prepared. Then, 2-methacryloxyethyl isocyanate was added, causing the terminal OH group of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer to react with the NCO group of the 2-methacryloxyethyl isocyanate, yielding an acrylic polymer as the base polymer. This polymer has residues of a (meth)acrylic monomer portion bonded to the repeating unit of the main chain, containing a group with a radioactive carbon-carbon double bond. The glass transition temperature of this acrylic polymer, measured by differential scanning calorimetry (DSC), was -30°C. To obtain polyester adhesive 7, 4 parts by weight of polyisocyanate compound (manufactured by Tosoh Corporation, trade name "CORONATE L") and 1.5 parts by weight of photopolymerization initiator (manufactured by BASF Corporation, trade name "Irgacure 184") were added to 100 parts by weight of acrylic polymer.

[0119] (3) Fabrication of adhesive tape for wafer fabrication <Example 1> Adhesive 1 was dissolved in ethyl acetate, and the stirred adhesive composition was coated onto a release liner made of polyethylene terephthalate film after demolding to a thickness of 10 μm after drying. After drying at 110°C for 3 minutes, it was bonded to substrate film 1 to form a first adhesive layer on the substrate film. Adhesive 4 was dissolved in ethyl acetate, and the stirred adhesive composition was coated onto a release liner made of polyethylene terephthalate film after demolding to a thickness of 10 μm after drying. After drying at 110°C for 3 minutes, a second adhesive layer was obtained. Then, the release liner was peeled off from the first adhesive layer, and the second adhesive layer was laminated onto the first adhesive layer to produce the wafer processing adhesive tape of Example 1.

[0120] <Examples 2-9, Comparative Examples 1-5> Except for the substrate film and adhesive layer being combined as described in Tables 1 and 2, the wafer processing adhesive tapes of Examples 2-9 and Comparative Examples 1-5 were made by the same method as in Example 1.

[0121] <Determination of Residual Solvent Content> After the adhesive tape for wafer fabrication was prepared (after tape formation), it was cut into 40 mm square pieces. The release liner was peeled off, 1 mL of p-menthane was added, and the mixture was allowed to stand for 30 minutes. Then, the solvent was discarded, and the mixture was dried at room temperature for 30 minutes. 1.0 g of the cut adhesive layer sample was then immersed in 10 mL of acetone. The supernatant was analyzed by gas chromatography-mass spectrometry (GC-MS) under the following conditions. The results are shown in Tables 1 and 2. [Analysis Conditions] Injection volume: 1μL Tubing string: db-1 0.25mm × 30m Inj: 200℃ (after holding at 40℃ for 4 minutes, increase the temperature to 200℃ at a rate of 20℃ / min) He flow rate: 1.0 mL / min

[0122] <Determination of Storage Elasticity> The storage elasticity of the first and second adhesive layers of the relevant examples and comparative examples was determined as follows: 100 sheets were prepared on a release film, and the adhesive was applied to a thickness of 20 μm after drying. The sheets were dried at 110°C for 3 minutes to form an adhesive layer. The release film was then peeled off, and the layers were laminated to a thickness of 2.0 mm. Test pieces were then punched with an 8 mm diameter die. These test pieces were then fed into a dynamic viscoelasticity tester (manufactured by Rheometric Corporation), and the storage elasticity G' was measured at 23°C and a frequency of 1 Hz. The results are shown in Tables 1 and 2.

[0123] <Soluble Resistance Assessment> On an 8-inch wafer, the wafer processing adhesive tape of the relevant embodiments and comparative examples was attached and fixed to a ring holder. While p-menthane was blown onto the wafer side as an organic solvent, the wafer was rotated at 2000 rpm for rotary cleaning. After cleaning and drying, the adhesive layer in the areas of the wafer where the wafer processing dicing tape was not attached was observed. Products in which the first adhesive layer remained intact and no detachment was observed was considered good and evaluated as ○. Products in which the second adhesive layer dissolved or swelled, detached from the first adhesive layer, or caused wrinkles on the substrate film were considered defective and evaluated as ×. The results are shown in Tables 1 and 2.

[0124]

[0125]

[0126] As shown in Table 1, since the wafer processing adhesive tape of the relevant embodiment is laminated on the substrate film in the order of first adhesive layer and second adhesive layer, the first adhesive layer is a base polymer, which is formed by adhesive composition containing acrylic polymer or polyester polymer. The glass transfer temperature of the base polymer is above -20°C, and the solvent resistance evaluation results are excellent.

[0127] On the other hand, as shown in Table 2, the adhesive tape for wafer processing in the comparative example has a lower glass transfer temperature of the base polymer of the first adhesive layer than -20°C, resulting in a deterioration in solvent resistance.

Claims

1. An adhesive tape for wafer processing, which is formed by laminating at least a substrate film, a first adhesive layer, and a second adhesive layer in this order, characterized in that the first adhesive layer is formed by an adhesive composition comprising an acrylic polymer or a polyester polymer as a base polymer, the glass transition temperature of the base polymer is above -20°C, and the storage elasticity of the first adhesive layer is higher than that of the second adhesive layer.

2. As in claim 1, the adhesive tape for wafer fabrication, wherein, The aforementioned substrate film is made of polyolefin resin.

3. The adhesive tape for wafer fabrication as described in claim 1 or claim 2, wherein, The thickness of the aforementioned substrate film is 70~350μm.

4. The adhesive tape for wafer processing as described in Request 1 or Request 2, wherein, 1 ml of p-menthane was dropped onto the surface of the aforementioned second adhesive layer, and after standing for 30 minutes, the residual solvent content was less than 1%, m / m.

5. A processing method including a cleaning step of the wafer with a solvent, wherein the wafer processing adhesive tape as described in claim 1 or claim 2 is used.