Adhesive tape for wafer fabrication and wafer fabrication methods

Abstract

The present invention provides a wafer processing adhesive tape that allows for the dissolution of adhesives used to attach support components to wafers using a solvent, and the removal of support components or washing away residual adhesives from wafers, while also properly maintaining wafers, preventing low yields due to wafer contamination, and enabling good transmission of wafer processing tape for laser marking using laser light to cleave wafers or inspect the condition of wafers. This invention relates to an adhesive tape for wafer processing, which is composed of a substrate film and at least one adhesive layer formed on the substrate film. The adhesive layer is characterized by being formed by an adhesive composition containing an acrylic polymer or a polyester polymer as the base polymer. The glass transition temperature of the base polymer is -45°C or higher, and the parallel line transmittance when light in the wavelength region of 1064 nm is incident from the substrate film side is 90% 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 a wafer processing method that includes a wafer cleaning step using a solvent. [Previous Technology]

[0002] On the back side of a wafer formed by thin-film fabrication wiring patterns, in order to protect the patterned surface and fix the wafer itself, a protective tape is generally applied to the patterned surface, followed by thin-film processing such as grinding and lapping. Such protective tape is generally made by coating an acrylic adhesive onto a substrate composed of a plastic film. However, in recent years, with the thinning and miniaturization of IC cards and mobile phones, the thickness of chips has been required to be below 50μm. Using the conventional 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 difficult, hindering automation of handling and transportation.

[0003] Regarding this problem, a proposed method is to provide support to the wafer by bonding it to a glass substrate, ceramic substrate, or silicon wafer substrate using an adhesive (see, for example, Patent Document 1). In this way, by using support components such as glass substrates, ceramic substrates, or silicon wafer substrates, the wafer's processability is greatly improved, and automated transportation becomes possible. Furthermore, the support components can also be used to support the wafer between the back-side wiring and bump formation steps.

[0004] When processing wafers using support members, the step of peeling the support members off the wafer becomes necessary. Generally, the peeling off of the support members is achieved by dissolving the adhesive with a solvent and then washing. In addition to the methods described above, to peel the wafer off the support members, there are also methods such as heating to soften the adhesive, causing the support members to slide and peel off, or using laser light to decompose the adhesive and peel off the support members. Even when using these methods, since adhesive or its decomposition products may remain on the wafer surface after peeling off the support members, in order to remove these residues, there are cases where the wafer is immersed in an organic solvent to wash it, or the wafer is washed by blowing organic solvent onto it while rotating it.

[0005] Then, the wafer is transferred to the dicing step, where it is cut into individual wafers. In the dicing step, generally, a wafer processing adhesive tape is used to laminate an adhesive layer onto a substrate film (see, for example, Patent Document 2). [Prior Art Documents] [Patent Documents]

[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] [Problem to be Solved by the Invention] However, as mentioned above, when the thickness of the wafer is 50 μm or less, wafer processing becomes very difficult due to warping after grinding or deflection during wafer casing. It is common practice to attach wafer processing adhesive tape to the ground surface of the wafer after grinding / polishing the back side of the wafer and before peeling off the support members, thus supporting and fixing it to the ring frame. Accordingly, the adhesive used during peeling off the support members is dissolved or washed away by solvent, and the wafer processing adhesive tape is applied while the wafer is attached to the wafer, seeking high solvent resistance in the wafer processing adhesive tape.

[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] Furthermore, when wafers are chipped into wafers, wafer processing tape is used to fix the wafers, and they are diced using a rotating blade or laser light. In recent years, a method has also been used where a weak point called a modifier layer is created inside the wafer using laser light. By fixing the wafer with the modifier layer in place with wafer processing tape, the wafer processing tape is stretched and expanded, and the wafer is diced from the modifier layer as a starting point for chipping. Thus, when the modifier layer is formed inside the wafer using laser light, when it becomes difficult for the laser light from the side of the wafer processing tape not attached to the wafer, i.e., the circuit surface, to penetrate the circuit pattern, the laser light is irradiated through the wafer processing tape from the side attached to the wafer processing tape.

[0010] Furthermore, in recent years, in order to confirm the quality after processing, the condition of the wafer, such as cracks and gaps, is visually confirmed from the surface of the wafer bonding tape.

[0011] Furthermore, in recent years, a semiconductor device manufacturing method using a mounting method known as the face-down method has been developed. In this method, when mounting a wafer with a circuit surface formed by electrodes such as bumps, the circuit surface side of the wafer is bonded to a wafer mounting portion such as a lead frame. Accordingly, a structure is formed in which the back side of the wafer, where no circuit is formed, is exposed.

[0012] Therefore, in order to protect the chip, a hard organic film (hereinafter referred to as "protective film") is often formed on the back side. In order to indicate the product number of the chip, etc., the protective film is printed. As a marking method, laser marking is a common method that involves irradiating the protective film with laser light to scratch off the surface of the protective film and forming text, etc.

[0013] When marking with laser light, if the surface to be marked is flat, the laser light loses its focal point, resulting in poor marking performance. However, as wafers become thinner, wafer warping occurs, making it impossible to maintain a constant distance between the laser light source and the printing area. This makes it difficult to concentrate the laser light, reducing marking performance and making printing impossible.

[0014] Therefore, a method is proposed to attach the protective film side of the wafer to the wafer processing tape and mark it by irradiating laser light from the wafer processing tape side.

[0015] However, in the conventional wafer processing adhesive tape described in Patent Document 2, there is a problem that the transparency is not sufficient, making it difficult to use laser light to cleave wafers or inspect the condition of wafers and perform laser marking.

[0016] Therefore, the present invention aims to provide a wafer processing adhesive tape that, even in wafer processing steps using a support member, allows for proper wafer retention after dissolving the adhesive adhering to the wafer with a solvent, peeling off the support member, or washing away residual adhesive on the wafer, preventing low yield due to wafer contamination, and enabling good laser marking using laser light for wafer processing tape, wafer dicing, or inspection of wafer condition. [Means for Solving the Problem]

[0017] In order to achieve the above-mentioned objectives, the inventors, through repeated efforts in research, discovered that the glass transition temperature of the substrate polymer of the adhesive layer is related to its solvent resistance. This invention was made based on this discovery.

[0018] That is, the wafer processing adhesive tape of the present invention is a wafer processing adhesive tape composed of a substrate film and an adhesive layer formed on the substrate film. The adhesive layer is characterized in that the aforementioned adhesive layer is formed by an adhesive composition containing an acrylic polymer or a polyester polymer as the base polymer. The glass transition temperature of the aforementioned base polymer is -45°C or higher, and the parallel line transmittance when light is incident from the substrate film side in the wavelength region of 1064nm is 90% or higher.

[0019] Preferably, the aforementioned adhesive tape for wafer processing is made of polyolefin resin.

[0020] 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 adhesive layer and the residual solvent content after standing for 30 minutes is less than 1%, m / m.

[0021] 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. [Effects of the Invention]

[0022] 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 adhesive remaining on the wafer is washed off, the wafer is properly maintained and the low yield caused by wafer contamination can be prevented.

Implementation Method

[0023] Hereinafter, the embodiments of the present invention will be described in detail.

[0024] The wafer processing adhesive tape of an embodiment of the present invention is attached to at least one side of a substrate film to form at least one adhesive layer.

[0025] Preferably, the substrate film and adhesive layer are cut (pre-cut) into shapes corresponding to the ring frames 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.

[0026] Hereinafter, the constituent elements of the adhesive tape for wafer processing of this embodiment will be described in detail.

[0027] (Substrate Film) Regarding the resin 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 copolymer, ethylene-(meth)acrylic acid butyl copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl chloride-vinyl acetate copolymer, polyurethane, polyamide, ionomer, nitrile rubber, butyl rubber, styrene-isoprene rubber, styrene-butadiene rubber, natural rubber and its water additives or modifiers, etc.

[0028] 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.

[0029] In particular, when using a substrate film with ionomers, 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 uniform.

[0030] Furthermore, the substrate film is not limited to a single layer, but may also be a multilayer structure of two or more resins laminated together, or may 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 types of resin compensates for the deficiencies of each resin.

[0031] The manufacturing method of the multilayer substrate film can be the conventional extrusion method, lamination method, etc. When using the lamination method, an adhesive can be placed between the layers. The adhesive can be a conventional adhesive.

[0032] As described above, when using laser light to cleave wafers, inspect the condition of chips, or perform laser marking through wafer processing tape, the wafer processing tape needs to have sufficient transmittance of visible or near-infrared light. Therefore, the thickness of the substrate film is preferably less than 100 μm. When it is 100 μm or more, the transmittance of parallel lines of the wafer processing tape is low. Furthermore, the substrate film is preferably 80 μm or more. When it is thinner than 80 μm, there is a risk of the adhesive film breaking during expansion.

[0033] In order to improve adhesion, the surface in contact with the first adhesive layer of the substrate film may be treated with corona treatment or primer.

[0034] (Adhesive layer) The adhesive composition forming the 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 includes at least an acrylic polymer or a polyester polymer as the base polymer.

[0035] 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 in this specification is defined as 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, meaning both acrylonitrile and methacrylic. Similarly, the term "(meth)acrylate" is inclusive, meaning both acrylate and methacrylate, and the term "(meth)acrylic" is inclusive, meaning both acrylonitrile and methacrylic.

[0036] The term "polyester polymer" refers to a polymer obtained by polycondensation of dicarboxylic acid and diol, which has repeating units of ester bonds in the main chain.

[0037] The glass transition temperature of the base polymer constituting the adhesive is -45°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 -45°C or higher, the solvent resistance is sufficient. When peeling the support component from the wafer, and when 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 becoming weak, thus ensuring adequate wafer retention. Furthermore, it prevents the adhesive layer from dissolving in solvents, contaminating the wafer, and reducing yield. The glass transition temperature of the base polymer constituting the adhesive is preferably above -30°C and below 1°C, and even more preferably above -25°C and below 1°C. When the glass transition temperature exceeds 1°C, wafer retention is poor.

[0038] The adhesive layer is preferably a radiation-cured type that is cured by irradiation. As the adhesive component constituting the radiation-cured adhesive layer, 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, it is also preferable to include a crosslinking agent. By incorporating a monomer having a functional group that can react 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 also be included if necessary. The following will provide a more detailed explanation.

[0039] Examples of acrylic polymers include acrylic polymers in which one or more of the following monomer components are used: (meth)acrylates (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., having alkyl groups with 1 to 30 carbon atoms, especially straight-chain or branched-chain alkyl esters with 4 to 18 carbon atoms) and (meth)acrylates (e.g., cyclopentyl esters, cyclohexyl esters, etc.). Furthermore, the term (meth)acrylate refers to acrylates and / or methacrylates, and has the same meaning as (methyl) in the present invention.

[0040] Acrylic polymers aim to improve cohesiveness, heat resistance, etc., and may, if necessary, contain 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.

[0041] Furthermore, since the acrylic polymer undergoes crosslinking, it may also include multifunctional monomers as copolymerizing monomer components if necessary. Examples of such multifunctional monomers include hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and urethane (meth)acrylate. 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 content.

[0042] The preparation of acrylic polymers can be carried out by applying appropriate methods such as solution polymerization, emulsion polymerization, block polymerization or suspension polymerization to a mixture of one or more component monomers.

[0043] Furthermore, in order to control the crosslinking density of the adhesive layer and improve pick-up properties, appropriate external crosslinking agents such as polyfunctional isocyanate compounds, polyfunctional epoxy compounds, melamine compounds, metal salt compounds, metal chelating agent compounds, amine resin compounds, or peroxides can be used for crosslinking treatment, or appropriate methods such as mixing low molecular weight compounds with two or more carbon-carbon double bonds and crosslinking treatment by irradiation with radiation can be employed. 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 relative to 100 parts by weight of the aforementioned base polymer, and more preferably 0.1 parts by weight to 20 parts by weight. Also, from the viewpoint of preventing degradation, various adhesive additives such as adhesive enhancers and anti-aging agents can be used in the adhesive as necessary, in addition to the aforementioned components.

[0044] The adhesive constituting the adhesive layer is preferably a radiation-curing adhesive. 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.

[0045] 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.

[0046] Furthermore, the radiation-curing oligomer component can include various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, with a molecular weight in the range of approximately 100 to 30,000 being suitable. The amount of radiation-curing monomer or oligomer component incorporated can be appropriately determined to reduce the adhesive strength of the adhesive layer 3, depending on the type of adhesive layer 3 mentioned above. Generally, it is approximately 5 to 500 parts by weight, preferably 70 to 150 parts by weight, relative to 100 parts by weight of the base polymer such as acrylic polymer constituting the adhesive.

[0047] Furthermore, in addition to the aforementioned additive-type radiation-curing adhesives, intrinsic radiation-curing adhesives, in which radiation-curing groups are introduced 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 oligomer components with low molecular weight components, and therefore, over time, the oligomer components do not migrate into the adhesive, thus forming a stable first adhesive layer.

[0048] The base polymer to which the radiation-curing group is introduced may not be particularly limited to those having carbon-carbon double bonds and adhesive properties. As such a base polymer, it is preferable to use an acrylic polymer as the basic backbone. As the basic backbone of an acrylic polymer, the acrylic polymers exemplified above can be cited.

[0049] There are no particular limitations on the method of introducing radiation-curing groups into acrylic polymers. Although various methods can be used, introducing radiation-curing 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 with the acrylic polymer, a compound having 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 radiation-curing property of the carbon-carbon double bond.

[0050] Examples of combinations of these functional groups include carboxylic acid group and epoxy group, carboxylic acid group and aziridinyl group, hydroxyl group and isocyanate group, etc. Among these combinations of functional groups, the combination of hydroxyl group and isocyanate group 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 and the aforementioned compound, but the preferred combination is the case 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 methacrylic acid isocyanate, 2-methacrylic acid oxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Furthermore, as an acrylic polymer, it is used to copolymerize the monomers containing hydroxyl groups as exemplified above, or ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0051] While intrinsic radiation-curing adhesives can be made using the aforementioned base polymers (especially acrylic polymers) with carbon-carbon double bonds alone, 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 the properties. The amount of such photopolymerizable compound incorporating is typically in the range of 30 parts by weight or less relative to 100 parts by weight of the base polymer, preferably in the range of 0 to 10 parts by weight.

[0052] In the case of radiation-curing adhesives that are cured by ultraviolet light, it is preferable to contain a photopolymerization initiator.

[0053] Among the above-mentioned acrylic polymers, in particular (meth)acrylate copolymers with radiation-hardening groups introduced into the side chains, more specifically, are 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 in the molecule.

[0054] The amount of carbon-carbon double bonds is preferably 1.2 to 1.8 meq / g. Regarding the amount of double bonds, the amount of carbon-carbon double bonds contained in about 10g of the heated and dried adhesive can be quantitatively determined by the gravimetric method of bromine addition reaction in a vacuum and in the dark.

[0055] The above-mentioned (meth)acrylate copolymer may contain units corresponding to other monomer components if necessary.

[0056] 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 may be used alone or in combination.

[0057] Furthermore, in radiation-curing adhesives, external crosslinking agents may be appropriately used to adjust the adhesion before or after radiation irradiation. Specific methods for 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 radiation-curing adhesives, in addition to the aforementioned components, various conventionally known adhesive-improving agents, anti-aging agents, foaming agents, and other additives may be incorporated as needed.

[0058] The polyester used in polyester 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.

[0059] As for the aforementioned dicarboxylic acids, there are no particular limitations, but 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., which are 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. In particular, dimer acids have low glass transition temperatures, allowing for the design of flexible adhesives and exhibiting good wetting properties, making them a superior option. Furthermore, dimer acids are derived from non-petroleum materials (plant-based raw materials), making them environmentally friendly. These can be used individually or in combination of two or more.

[0060] Furthermore, the aforementioned polyester contains a diol component, and preferably, the diol component contains at least two hydroxyl groups (hydroxyl groups) in the molecule. Aliphatic diols or polyether diols are preferred.

[0061] The aforementioned aliphatic diol is preferably an aliphatic diol having an alkyl group having 3 to 10 carbon atoms. While there is no particular limitation on the aliphatic diol having an alkyl group having 3 to 10 carbon atoms, 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 in one or in combination of two or more.

[0062] Furthermore, while there are no particular limitations on the aforementioned polyether glycol, it is preferable to use a polyether glycol with hydroxyl groups at both ends. The number average molecular weight (Mn) of the polyether glycol with hydroxyl groups at both ends is not particularly limited. Specifically, it is preferable to use 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. One or more of these can be used.

[0063] The aforementioned polyester-based polycondensation carboxylic acid component and diol component are obtained. The molar ratio (OH / COOH) of the carboxyl group of the carboxylic acid component and the hydroxyl group of the diol 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. When the aforementioned molar ratio is less than 1, there is a risk that the ends of the polymerized polyester (polymer) will become carboxyl groups, and then cross-linking by a cross-linking agent (e.g., an isocyanate-based cross-linking agent) may not be able to proceed rapidly. Furthermore, there is a risk that the retention force (cohesion) of the adhesive layer may not be sufficiently obtained.

[0064] Alternatively, other components besides the aforementioned carboxylic acid components or diol components may be polymerized, or added after polymerization.

[0065] The method for synthesizing the aforementioned polyester is not particularly limited, and known polymerization methods may be used. Furthermore, the polymerization (condensation polymerization) reaction of the carboxylic acid component and the diol component may be carried out using a solvent, or under reduced pressure without solvent, or using conventionally known methods.

[0066] When a polyester polymer is used as the base polymer, the adhesive composition of the first adhesive layer is preferably a fatty acid ester with a molecular weight (molar molecular weight: g / molar) of 200 to 700 without functional groups, together with the aforementioned polyester polymer. Examples of fatty acid esters include isopropyl myristate, isopropyl palmitate, and methyl linoleate. Dibasic esters such as adipate, sebate, and phthalate can also be used. One or more of these can be used. The amount of fatty acid ester incorporated is preferably 20 to 150 parts by weight relative to 100 parts by weight of the aforementioned polyester polymer, more preferably 30 to 140 parts by weight, and even more preferably 40 to 130 parts by weight.

[0067] 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.

[0068] In particular, it is preferable to use isocyanate-based crosslinking agents such as polyvalent isocyanurates or polyfunctional isocyanates that are known in the past. Examples of polyvalent isocyanurates include polyisocyanates of hexamethylene diisocyanate. As for polyfunctional isocyanate compounds, it is preferable to have compounds having at least two or more isocyanate groups in the molecule, more preferably three or more, but there are no particular limitations. Specifically, examples include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, etc.

[0069] Furthermore, although wafer processing adhesive tape is applied to the milled surface of the wafer after back-side grinding and polishing and before the support member is 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 to facilitate peeling.

[0070] 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 to 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 cutting line.

[0071] 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 crosslinking structure is increased, and the movement of polyoxypropylene to the wafer interface can reduce wafer surface contamination.

[0072] Examples of polypropylene oxide with a number average molecular weight greater than 3000 and 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 ether with a number average molecular weight greater than 3000 and 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 are not limited to these.

[0073] The amount of polypropylene oxide used, which has 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 used is too small, the wafer grinding surface is unstable in a state where the natural oxide film has not fully formed. When adhesive tape for wafer processing is applied, it is not possible to efficiently pick up thin semiconductor wafers from large-diameter wafers. If the amount of polypropylene oxide used is too large, the adhesion before radiation curing becomes insufficient. During dicing, the wafer ends peel off, and cutting dust adheres to the back of the wafer.

[0074] Furthermore, the adhesive layer may also be composed of multiple laminated layers. When multiple layers are present, the adhesive described above can be used for all layers, but for at least one layer, the adhesive described above is sufficient. Among the multiple adhesive layers, if only one layer is composed of the adhesive described above, it is preferable to use the adhesive described above for the layer in contact with the substrate film. For the layer composed of only the adhesive described above, when the support member is peeled off from the wafer using the adhesive described above, and the adhesive is dissolved and cleaned with a solvent, the stress applied to the adhesive layer due to the wrinkles generated on the substrate film can prevent the adhesion of the adhesive layer from weakening, thus ensuring sufficient wafer retention. Furthermore, even if the second adhesive layer is dissolved in a solvent, since the first adhesive layer retains the second adhesive layer, it can prevent the second adhesive layer from falling off, contaminating the wafer, and causing low yield.

[0075] The thickness of the adhesive layer is preferably 5 μm to 70 μm, more preferably 8 μm to 50 μm, and even more preferably 10 μm to 30 μm. When the adhesive layer is thinner than 5 μm, there is a risk that sufficient adhesive force may not be achieved. On the other hand, when 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. Furthermore, when the adhesive layer is thicker than 30 μm, there is a risk that the parallel line transmittance of the adhesive tape used for wafer processing may be reduced.

[0076] The method of forming an adhesive layer on a substrate film is not particularly limited. In addition to forming it by 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 can be transferred to the substrate film to form the adhesive layer.

[0077] Preferably, when 1 ml of p-menthane is dropped onto the surface of the adhesive layer and allowed to stand for 30 minutes, the residual solvent content is 1% or less (m / m). If the residual solvent content is 1% or less (m / m), when the adhesive used to bond the support component to the wafer is dissolved with solvent, or when the support component is peeled off and the residual adhesive on the wafer is washed away, the wrinkles generated on the substrate film of the adhesive tape for wafer processing apply stress to the adhesive layer, which can prevent the adhesive layer from becoming weak and can fully hold the wafer. Furthermore, it can prevent the adhesive layer of the adhesive tape for wafer processing from dissolving in solvent, contaminating the wafer, and causing low yield.

[0078] After the adhesive tape for wafer processing is prepared (after tape formation), it is cut into 40mm square pieces. The release liner is peeled off, 1mL 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. 1.0g of the cut adhesive layer sample is immersed in 10mL of acetone. The supernatant is analyzed by gas chromatography-mass spectrometry (GC-MS) under the following conditions. [Analytical Conditions] Injection volume: 1μL Column: db-1 0.25mm×30m Inj: 200℃ (held at 40℃ for 4 minutes, then increased to 200℃ at 20℃ / min) He flow rate: 1.0mL / min

[0079] In order to set the residual solvent amount to 1% or less, the glass transfer temperature of the substrate polymer of the adhesive layer can be set to -45°C or higher.

[0080] The adhesive tape for wafer processing preferably has a parallel line transmittance of 90% or more when incident from the light substrate film side in the 1064nm wavelength region. If the parallel line transmittance is 90% or more when incident from the light substrate film side in the 1064nm wavelength region, when irradiated with laser light of wavelength 1064nm, the highly linear laser light will pass through the adhesive tape with high transmittance. Furthermore, a parallel line transmittance of 90% or more when incident from the light substrate film side in the 400-600nm wavelength region is also preferable, and more preferably, a parallel line transmittance of 90% or more when incident from the light substrate film side in the 400-1400nm wavelength region. If the linear transmittance of a substrate film in the wavelength region of 400–1400 nm is 90% or higher, when laser light of the visible or infrared wavelength region is irradiated through wafer processing adhesive tape, the high linearity of the laser light allows for high transmittance through the wafer processing adhesive tape. Therefore, laser light can be used appropriately through the wafer processing tape for wafer dicing, inspecting wafer condition, or laser marking. The linear transmittance was measured according to JIS K 7361-1:1999.

[0081] Furthermore, for wafer processing adhesive tapes, if necessary until they are put into practical use, a synthetic resin film, typically used as a separator, may be attached to the adhesive layer side to protect the adhesive layer. Examples of materials constituting 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, if necessary, undergo a peeling treatment such as polysiloxane treatment, long-chain alkyl treatment, or fluorine treatment. The thickness of the synthetic resin film is typically 10–100 μm, preferably around 25–50 μm.

[0082] (Dissolving the adhesive in the solvent and cleaning the wafer) When peeling the wafer from the support member, 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 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 clean the side of the wafer from the adhesive. In addition to the above methods, to peel the wafer from the support member, there are also methods such as heating to soften the adhesive and sliding the support member for peeling, or using laser light to decompose the adhesive and peel off the support member. Even when using such methods, there may be adhesive residues or their decomposition products remaining on the wafer surface after the support members are peeled off. Therefore, in order to remove such residues, the wafer supported by the wafer processing adhesive tape and ring holder may be immersed in an organic solvent to clean the wafer, or the wafer may be cleaned by blowing organic solvent onto it while rotating it.

[0083] The adhesive tape for electronic components invented in this case includes the following forms.

[0084] [1] An adhesive tape for wafer processing, comprising a substrate film and an adhesive layer formed on the substrate film, characterized in that the 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 -45°C or higher, and the parallel line transmittance when light is incident from the substrate film side in the wavelength region of 1064 nm is 90% or higher.

[0085] [2] The wafer processing adhesive tape described in [1] wherein the substrate film is composed of polyolefin resin.

[0086] [3] The wafer processing adhesive tape as described in [1] or [2], wherein the thickness of the substrate film is less than 100 μm.

[0087] [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 adhesive layer and left to stand for 30 minutes, and the amount of residual solvent is less than 1%, m / m.

[0088] [5] The wafer processing adhesive tape described in any of [1] to [4] is used in a wafer processing method that includes a cleaning step of the wafer by means of a solvent.

[0089] Next, the present invention will be further described in detail with reference to embodiments. Although the present invention will be described hereby by way of embodiments, the present invention is not limited to these embodiments.

[0090] (1) Formation of the substrate film <Substrate film 1> Ethylene-vinyl acetate copolymer (manufactured by NUC Corporation, trade name "NUC-3660") is melted at 140°C and formed using an extruder to a thickness of 80 μm to form substrate film 1. <Substrate film 2> Ethylene-methacrylate-(2-methyl-propyl acrylate)-Zn++ ionomer resin (manufactured by Mitsui-DuPont Polychemicals Corporation, trade name "HIMILAN AM7316") is melted at 140°C and formed using an extruder to a thickness of 100 μm to form substrate film 2. <Substrate film 3> Polypropylene (manufactured by Prime Polymer Corporation, trade name "F227D") is melted at 140°C and formed using an extruder to a thickness of 70 μm to form substrate film 3.

[0091] (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, and the OH group at the end of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer reacted with the NCO group of 2-methacryloxyethyl isocyanate to obtain an acrylic polymer as the base polymer, in which residues of (meth)acrylic monomers with groups containing radioactive carbon-carbon double bonds are bonded relative to the repeating units of the main chain. The glass transition temperature of this acrylic polymer was -20°C when measured by differential scanning calorimeter (DSC). To obtain acrylic adhesive 1, 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.

[0092] <Adhesive 2> As the base polymer, an adhesive comprising a polyester polymer is prepared, namely Nichigo-POLYESTER (registered trademark) S-0097S55EO manufactured by Mitsubishi Chemical Corporation. Also, the glass transition temperature of the polyester polymer in the base polymer is 1°C. 3 parts by weight of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "CORONATE L") are added to 100 parts by weight of the polyester polymer and mixed to obtain polyester adhesive 2.

[0093] <Adhesive 3> 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, and the OH group at the end of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer reacted with the NCO group of 2-methacryloxyethyl isocyanate to obtain a polymer (a) in which residues of a (meth)acrylic monomer portion containing a group containing a radiohardening carbon-carbon double bond are bonded relative to the repeating unit of the main chain. The glass transfer temperature was -45°C when measured by differential scanning calorimeter (DSC). 2 parts by mass of polyisocyanate compound (manufactured by Tosoh Corporation, trade name "CORONATE L") and 1.5 parts by mass of photopolymerization initiator (manufactured by BASF Corporation, trade name "Irgacure 184") were added relative to 100 parts by mass of (a) and mixed to obtain acrylic adhesive 3.

[0094] <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, and the terminal OH group of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer reacted with the NCO group of 2-methacryloxyethyl isocyanate to obtain a polymer (a) having residues of a (meth)acrylic monomer portion bonded to the repeating unit of the main chain with a group containing a radiation-hardening carbon-carbon double bond. The glass transfer temperature, measured by differential scanning calorimeter (DSC), was -64°C. Compared to (a) 100 parts by weight, 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 and mixed to obtain acrylic adhesive 4.

[0095] <Adhesive 5> 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, and the terminal OH group of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer reacted with the NCO group of 2-methacryloxyethyl isocyanate to obtain an acrylic polymer as a base polymer in which residues of a (meth)acrylic monomer portion having a group containing a radioactive carbon-carbon double bond are bonded relative to the repeating unit of the main chain. The glass transition temperature of this acrylic polymer, measured by differential scanning calorimetry (DSC), was -50°C. To obtain acrylic adhesive 6, 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.

[0096] (3) Preparation of adhesive tape for wafer processing <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 being dried to a thickness of 10 μm. After drying at 110°C for 3 minutes, it was bonded to the substrate film 1 to form an adhesive layer on the substrate film, thus forming the adhesive tape for wafer processing of Example 1.

[0097] <Examples 2-5, Comparative Examples 1 and 2> Except that the substrate film and adhesive layer are combined as described in Table 1, the adhesive tapes of Examples 2-5 and Comparative Examples 1 and 2 are made by the same method as in Example 1.

[0098] <Example 6> 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 the substrate film 1 to form an 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. It was dried at 110°C for 3 minutes to obtain a second adhesive layer. Then, the release liner was peeled off from the adhesive layer, and a second adhesive layer was laminated onto the adhesive layer to form the adhesive tape of Example 6.

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

[0100] <Determination of Parallel Line Transmittance> Light was incident on the substrate film side of the wafer processing adhesive tape of the relevant examples and comparative examples, and the transmittance of parallel rays was measured. The measurement was performed using a Shimadzu UV-3101 spectrophotometer, according to JIS K 7361-1:1999, in the range of 400 to 1400 nm, and the transmittance of parallel lines at 1064 nm was determined. The results are shown in Table 1.

[0101] <Evaluation of Solvent Resistance> On an 8-inch wafer, the wafer processing adhesive tape of the relevant examples and comparative examples was attached and fixed to a ring holder. While blowing p-menthane as an organic solvent from the wafer side, the wafer was rotated at 2000 rpm to perform rotational 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. Those where no dissolution or swelling of the adhesive was observed were considered good products and evaluated as ○, while those where dissolution or swelling of the adhesive was observed were considered defective products and evaluated as ×. The results are shown in Table 1.

[0102] <Evaluation of Wafer Separability> An 8-inch diameter, 50μm thick, ground wafer was bonded to the wafer processing adhesive tape of the relevant embodiments and comparative examples. An 8-inch frame was used as the ring holder. This was set in a laser processing apparatus ML200 manufactured by Tokyo Seimitsu Co., Ltd., and laser light was incident from the side of the wafer processing adhesive tape with the focus concentrated inside the wafer, forming a modified region by multiphoton absorption along a predetermined cutting line of 5mm × 5mm, which is the wafer size. Then, using the expansion device attached to the laser processing apparatus ML200, the adhesive sheet was stretched with a stretch amount of 20mm and an expansion speed of 10mm / s, and the wafer slitting step was performed. The laser processing conditions are as follows. After the wafer slitting step, the separability was visually observed. Wafers that were well-separated were classified as excellent (◎), wafers that were partially unseparated but had no practical problems were classified as good (○), and unseparated wafers were classified as defective (×). The results are shown in Table 1.

[0103] [Laser] Light source: Semiconductor laser excitation Nd:YAG laser wavelength: 1064nm laser beam cross-sectional area: 3.14×10-8cm2 Oscillation mode: Q-switched Pulse repetition frequency: 100kHz Pulse width: 30ns Output: 20μJ / pulse Laser light quality: TEM0040 Polarization characteristics: Linear polarization

[0104] [Light-collecting lens] Magnification: 50x; NA: 0.55; Transmittance relative to laser wavelength: 60%

[0105] [Moving speed of the stage for mounting the substrate] Moving speed: 100 mm / second

[0106] <Evaluation of Laser Marking Quality> An 8-inch diameter wafer was bonded to the wafer processing adhesive tape of the relevant embodiments and comparative examples. From the wafer processing adhesive tape side, a laser marking device (Keyence MD-H9800 laser engraving machine) was used to mark the wafer using laser light (YAG laser). The marking was performed by continuously forming dots with a diameter of 50 μm and a depth of 15 μm using laser light. As a comparison, the same marking was performed on the same wafer without using the wafer processing adhesive tape. Compared to the comparison, those with no deterioration in the visibility of the markings were considered good products and evaluated as ○, while those with deteriorated visibility were considered defective products and evaluated as ×. The results are shown in Table 1.

[0107]

[0108] As shown in Table 1, since the adhesive tape for wafer processing in the relevant embodiments is formed by an adhesive composition containing an acrylic polymer or a polyester polymer as the base polymer, and the glass transition temperature of the base polymer is -45°C or higher, the solvent resistance evaluation is excellent. Furthermore, since the parallel line transmittance is 90% or higher when light is incident from the substrate film side in the 1064nm wavelength region, the wafer separation and laser marking performance evaluations are excellent.

[0109] On the other hand, the adhesive tape for wafer processing in the comparative example has an adhesive layer formed by an adhesive composition containing an acrylic polymer or a polyester polymer as the base polymer. The glass transition temperature of the base polymer is lower than -45°C, so the solvent resistance is deteriorated.

Claims

1. An adhesive tape for wafer processing, comprising a substrate film and at least one adhesive layer formed on the substrate film, characterized in that the adhesive layer is formed by an adhesive composition comprising an acrylic polymer or a polyester polymer as a base polymer; after 1 ml of p-menthane is dropped onto the surface of the adhesive layer and allowed to stand for 30 minutes, the residual solvent content is 1% or less (m / m); the glass transition temperature of the base polymer is -45°C or higher; and the parallel line transmittance when light in the wavelength region of 1064 nm is incident from the substrate film side is 90% or higher.

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 less than 100 μm.

4. A wafer 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.