Adhesive tape for wafer processing

Abstract

Even after dissolving the adhesive that had bonded the support member to the wafer using a solvent to peel off the support member or clean the adhesive remaining on the wafer, the wafer can be properly held, preventing a decrease in yield due to wafer contamination, and can be satisfactorily divided into wafers using a laser beam, inspected for chip conditions, or laser marked through a wafer processing tape. Provided is a wafer processing adhesive tape that enables such operations. 【Solution means】 A wafer processing adhesive tape comprising a base film and at least one adhesive layer formed on the base film, wherein the adhesive layer is formed of an adhesive layer composition containing 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 in the wavelength region of 1064 nm is incident from the base film side is 90% or higher.

Description

Technical Field

[0001] The present invention relates to an adhesive tape for wafer processing used for dicing a wafer. More specifically, the present invention relates to an adhesive tape for wafer processing used in a wafer processing method including a step of cleaning a wafer with a solvent.

Background Art

[0002] When thinning the back surface of a wafer on which a wiring pattern is formed, in order to protect the pattern surface of the wafer and fix the wafer itself, after attaching a protective tape to the pattern surface, thinning processes such as polishing and grinding are generally performed on the back surface. As such a protective tape, one in which an acrylic adhesive or the like is applied on a base material made of a plastic film is generally used. However, in recent years, due to the thinning and miniaturization of IC cards and mobile phones, the thickness of chips has been required to be at a level of 50 μm or less. In the process using a conventional protective tape, the wafer cannot be supported only by the protective tape, and warping of the wafer after grinding, bending when storing the wafer in a wafer cassette, etc. make it difficult to handle the wafer and complicate the automation of handling and transportation.

[0003] In response to this problem, a method has been proposed in which a glass substrate, a ceramic substrate, a silicon wafer substrate, or the like is bonded to a wafer via an adhesive to impart supportability to the wafer (see, for example, Patent Document 1). By using a support member such as a glass substrate, a ceramic substrate, or a silicon wafer substrate in this way, the handleability of the wafer is greatly improved and automation of transportation becomes possible. In addition, the support member can also be used to support the wafer while the wafer is being subjected to the back surface wiring and bump formation processes.

[0004] When handling a wafer using a support member, a step of peeling the support member from the wafer is required. The peeling of the support member is generally performed by dissolving an adhesive using a solvent and then cleaning. In addition to the above method, to peel the wafer from the support member, there are also methods such as heating to soften the adhesive and sliding the support member to peel it, or decomposing the adhesive by laser light irradiation to peel the support member. Even when these methods are used, adhesive or its decomposition products may remain on the wafer surface after peeling the support member. Therefore, in order to remove these residues, the wafer is immersed in an organic solvent to clean the wafer, or the wafer is rotated while spraying an organic solvent onto the wafer to clean the wafer.

[0005] Thereafter, the wafer is transferred to a dicing process and cut into individual chips. In the dicing process, generally, an adhesive tape for wafer processing with an adhesive layer laminated on a base film is used (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, as described above, when the thickness of the wafer becomes 50 μm or less, handling the wafer alone becomes extremely difficult due to warping of the wafer after grinding or bending when storing the wafer in a wafer cassette. Therefore, prior to peeling the support member after back grinding and polishing of the wafer, it is common practice to attach a wafer processing adhesive tape to the ground surface of the wafer and support and fix it to a ring frame. Accordingly, dissolution and cleaning with a solvent of the adhesive performed during peeling of the support member are carried out with the wafer attached to the wafer processing adhesive tape, and high solvent resistance is required for the wafer processing adhesive tape.

[0008] However, with a normal wafer processing adhesive tape such as the one described in Patent Document 2, the solvent resistance is insufficient, and there is a problem that the adhesive strength of the adhesive layer of the wafer processing adhesive tape decreases and the wafer cannot be sufficiently held. There is also a problem that the adhesive layer of the wafer processing adhesive tape dissolves in the solvent, contaminates the wafer, and the yield decreases.

[0009] When singulating the wafer into chips, the wafer is fixed using a wafer processing tape and divided by a rotating blade or laser light. In recent years, a method has also been used in which a fragile portion called a modified layer is provided inside the wafer by laser light, the wafer provided with the modified layer is fixed with a wafer processing tape, and the wafer processing tape is tension-expanded to divide the wafer starting from the modified layer and singulate it. When forming a modified layer by laser light inside the wafer in this way, when laser light irradiation from the surface of the wafer where the wafer processing tape is not attached, that is, the circuit surface, is difficult due to the circuit pattern, laser light is irradiated through the wafer processing tape from the surface on the side where the wafer processing tape is attached.

[0010] In recent years, for quality confirmation after processing, the state of cracks and chips in the chips is visually confirmed from the surface to which the wafer processing tape is attached.

[0011] Furthermore, in recent years, a method for manufacturing a semiconductor device using an implementation method called the face-down method has been carried out. In this method, when mounting a chip having a circuit surface on which electrodes such as bumps are formed, the circuit surface side of the chip is joined to a chip mounting portion such as a lead frame. Therefore, a structure is formed in which the back surface side of the chip where no circuit is formed is exposed.

[0012] For this reason, on the back surface side, in order to protect the chip, a hard organic film (hereinafter referred to as "protective film") is often formed. The protective film is printed in order to display the part number etc. of the chip. As a marking method, a laser marking method in which laser light is irradiated on the protective film to scrape off the surface of the protective film to form characters etc. has become widespread.

[0013] When performing marking with laser light, if the surface to be marked is not flat, the focus of the laser light will not be achieved, and good markability cannot be obtained. However, as a result of the thinning of the wafer, the wafer warps, the distance between the laser light source and the printing portion is not constant, it becomes difficult to focus the laser light, the markability deteriorates, and there is a problem that printing cannot be performed.

[0014] Therefore, a method has been proposed in which the protective film side of the wafer is attached to a wafer processing tape, and laser light is irradiated from the wafer processing tape side for marking.

[0015] However, in a normal wafer processing adhesive tape such as the wafer processing adhesive tape described in Patent Document 2, the transparency is insufficient, and it is difficult to divide the wafer using laser light, inspect the state of the chip, or perform laser marking through the wafer processing tape well.

[0016] Therefore, even when used in a wafer processing step using a support member, the present invention dissolves the adhesive bonding the support member to the wafer using a solvent to peel off the support member, or after cleaning the adhesive remaining on the wafer, can appropriately hold the wafer, prevent a reduction in yield due to wafer contamination, and can satisfactorily divide the wafer using laser light, inspect the state of chips, or perform laser marking through a wafer processing tape. An object of the present invention is to provide an adhesive tape for wafer processing that can achieve these functions.

Means for Solving the Problems

[0017] As a result of intensive research to achieve the above object, the present inventors have found that the glass transition temperature of the base polymer of the adhesive layer is related to solvent resistance. The present invention is based on this finding.

[0018] That is, the adhesive tape for wafer processing according to the present invention is an adhesive tape for wafer processing comprising a base film and at least one adhesive layer formed on the base film, wherein the adhesive layer is formed of an adhesive layer composition containing 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 in the wavelength region of 1064 nm is incident from the base film side is 90% or higher.

[0019] Preferably, the base film of the adhesive tape for wafer processing is composed of a polyolefin resin.

[0020] Also, preferably, in the adhesive tape for wafer processing, the amount of residual solvent after dropping 1 ml of p-menthane on the surface of the adhesive layer and allowing it to stand for 30 minutes is 1% m / m or less.

[0021] Also, preferably, the adhesive tape for wafer processing is used in a wafer processing method including a step of cleaning the wafer with a solvent.

Effects of the Invention

[0022] According to the present invention, even when used in a wafer processing step using a support member, the adhesive that bonded the support member to the wafer is dissolved using a solvent, the support member is peeled off, or after washing the adhesive remaining on the wafer, the wafer can be properly held and a decrease in yield due to wafer contamination can be prevented.

Embodiment for Carrying Out the Invention

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

[0024] The adhesive tape for wafer processing according to an embodiment of the present invention has at least one adhesive layer formed on at least one side of a base film.

[0025] Note that the base film and the adhesive layer are preferably cut (pre-cut) into a shape corresponding to a ring frame used when singulating wafers. Further, the adhesive tape for wafer processing of the present invention may be in a form cut for each wafer, or may be in a form in which a plurality of long separators cut for each wafer are wound into a roll.

[0026] Hereinafter, each component of the adhesive tape for wafer processing of the present embodiment will be described in detail.

[0027] (Base Film) Regarding the resin constituting the base 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 vulcanizate, 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-added or modified products, etc. may be used.

[0028] Among them, since the base film exhibits excellent stretchability during expansion, it is preferably made of a polyolefin resin. Examples of the polyolefin resin include homopolymers or copolymers 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, ionomer, or mixtures thereof.

[0029] In particular, in the case of a base film using an ionomer, uniform physical properties can be obtained with respect to the feeding direction and the width direction of the base film. Therefore, when splitting occurs during expansion, the chip intervals of the individual pieces can be made uniform.

[0030] Note that the base film is not limited to a single layer, and may have a multi-layer structure in which two or more resins are laminated, or one type of resin may be laminated in two or more layers. Lamination of one type of resin is preferable from the viewpoint that each characteristic is more enhanced and expressed, and lamination of two or more types of resins is preferable in that each defect is compensated.

[0031] As a method for manufacturing a multi-layer base film, conventionally known extrusion methods, lamination methods, etc. can be used. When using the lamination method, an adhesive may be interposed between the layers. As the adhesive, conventionally known adhesives can be used.

[0032] As described above, when splitting a wafer, inspecting the state of chips, or performing laser marking through a wafer processing tape using laser light, the wafer processing tape is required to have the performance of sufficiently transmitting visible light or near-infrared light. Therefore, the thickness of the base film is preferably less than 100 μm. If it is 100 μm or more, the parallel line transmittance of the wafer processing tape decreases. Also, the base film is preferably 80 μm or more. If it is thinner than 80 μm, there is a risk that the adhesive sheet will break during expansion.

[0033] The surface of the base film in contact with the adhesive layer may be subjected to corona treatment or treatment with a primer or the like in order to improve adhesion.

[0034] (Adhesive layer) The adhesive composition for forming the adhesive layer may contain one or more of various rubber-like polymers such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine polymers known in the field of adhesives, but at least as a base polymer, it contains an acrylic polymer or a polyester polymer.

[0035] The "acrylic polymer" refers to a polymer containing monomer units derived from a monomer having at least one (meth)acryloyl group in one molecule as a monomer unit constituting the polymer. Hereinafter, a monomer having at least one (meth)acryloyl group in one molecule is also referred to as an "acrylic monomer". Therefore, the acrylic polymer in this specification is defined as a polymer containing monomer units derived from acrylic monomers. As a typical example of the acrylic polymer, an acrylic polymer in which the proportion of acrylic monomers among all monomer components used for the synthesis of the acrylic polymer is more than 50% by weight can be mentioned. Also, "(meth)acryloyl" means comprehensively referring to acryloyl and methacryloyl. Similarly, "(meth)acrylate" means comprehensively referring to acrylate and methacrylate, and "(meth)acrylic" means comprehensively referring to acrylic and methacrylic, respectively.

[0036] The "polyester-based polymer" refers to a polymer obtained by polycondensation of a dicarboxylic acid and a diol and having repeating units containing an ester bond in the main chain.

[0037] The base polymer constituting the adhesive has a glass transition temperature of -45°C or higher. Here, the 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 the support member is peeled from the wafer and the adhesive is dissolved and washed using a solvent, wrinkles are generated in the base film, stress is applied to the adhesive layer, and it is possible to prevent the adhesive force of the adhesive layer from decreasing, and the wafer can be sufficiently held. Further, it is possible to prevent the adhesive layer from being dissolved by the solvent, contaminating the wafer, and reducing the yield. The glass transition temperature of the base polymer constituting the adhesive is more preferably more than -30°C and 1°C or less, and even more preferably more than -25°C and 1°C or less. If the glass transition temperature exceeds 1°C, the holding property of the wafer decreases.

[0038] The adhesive layer is preferably a radiation-curable type that cures by irradiation with radiation. As the adhesive composition constituting the radiation-curable adhesive layer, a polymer constituting the adhesive and a radiation-polymerizable compound can be used in combination, or a polymer in which a functional group (preferably an ethylenically unsaturated group) polymerizable by radiation is incorporated into the polymer constituting the adhesive can be used. In order to promote polymerization by radiation, it is preferably included a photoinitiator. It is also preferable to contain a crosslinking agent. By incorporating a monomer having a functional group capable of reacting with the crosslinking agent into the polymer constituting the adhesive, the film hardness and gel fraction can be adjusted. Furthermore, if necessary, additives and additives other than the above can also be contained. This will be described in more detail below.

[0039] Examples of acrylic polymers include (meth)acrylic acid alkyl esters (e.g., methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester, isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester, tridecyl ester, tetradecyl ester, hexadecyl ester, octadecyl ester, eicosyl ester, etc., alkyl esters having 1 to 30 carbon atoms, particularly linear or branched alkyl esters having 4 to 18 carbon atoms) and (meth)acrylic acid cycloalkyl esters (e.g., cyclopentyl ester, cyclohexyl ester, etc.) of one or more of these as monomer components. Here, (meth)acrylic acid ester means acrylic acid ester and / or methacrylic acid ester, and (meth) in the present invention has the same meaning in all cases.

[0040] The acrylic polymer may contain units corresponding to other monomer components copolymerizable with the alkyl (meth)acrylate or cycloalkyl ester, if necessary, for the purpose of modifying cohesion, heat resistance, etc. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid; acid anhydride monomers such as maleic anhydride, itaconic anhydride; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid; phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate; acrylamide, acrylonitrile, and the like. These copolymerizable monomer components can be used singly or in combination of two or more. The amount of these copolymerizable monomers used is preferably 40% by weight or less of the total monomer components.

[0041] Furthermore, since the acrylic polymer is crosslinked, a polyfunctional monomer or the like can also be included as a monomer component for copolymerization as needed. Examples of such polyfunctional monomers include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene 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, urethane (meth)acrylate, and the like. One or more of these polyfunctional monomers can also be used. From the viewpoint of adhesion characteristics and the like, the amount of the polyfunctional monomer used is preferably 30% by weight or less of the total monomer components.

[0042] The preparation of the acrylic polymer can be carried out, for example, by applying an appropriate method such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, or a suspension polymerization method to a mixture of one or more component monomers.

[0043] In addition, in order to control the crosslinking density of the adhesive layer and improve the pick-up property, for example, an appropriate external crosslinking agent such as a polyfunctional isocyanate-based compound, a polyfunctional epoxy-based compound, a melamine-based compound, a metal salt-based compound, a metal chelate-based compound, an amino resin-based compound, or a peroxide is used for crosslinking treatment, or a low-molecular compound having two or more carbon-carbon double bonds is mixed and crosslinked by irradiation with radiation or the like. An appropriate method can be adopted. When using an external crosslinking agent, its amount used is appropriately determined according to the balance with the base polymer to be crosslinked and further according to the use purpose as an adhesive. Generally, it is preferably blended in an amount of about 20 parts by weight or less, more preferably 0.1 part by weight to 20 parts by weight, based on 100 parts by weight of the base polymer. In addition, from the viewpoint of preventing deterioration and the like, additives such as various tackifiers and anti-aging agents may be used as needed in addition to the above components in the adhesive.

[0044] As the adhesive constituting the adhesive layer, a radiation-curable adhesive is preferable. Examples of the radiation-curable adhesive include an additive-type radiation-curable adhesive in which a radiation-curable monomer component or a radiation-curable oligomer component is blended with the aforementioned adhesive.

[0045] Examples of the radiation-curable monomer component to be blended include, for example, urethane (meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxy penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, and the like. These monomer components can be used alone or in combination of two or more.

[0046] In addition, examples of the radiation-curable oligomer component include various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, and those having a molecular weight in the range of about 100 to 30,000 are suitable. The blending amounts of the radiation-curable monomer component and the oligomer component can be appropriately determined according to the type of the adhesive layer 3 so as to be able to reduce the adhesive force of the adhesive layer 3. Generally, it is, for example, 5 parts by weight to 500 parts by weight, preferably about 70 parts by weight to 150 parts by weight, based on 100 parts by weight of a base polymer such as an acrylic polymer constituting the adhesive.

[0047] In addition, examples of the radiation-curable adhesive include, in addition to the additive-type radiation-curable adhesive, an inherent-type radiation-curable adhesive in which a radiation-curable group is introduced into the polymer side chain, main chain, or main chain end as a base polymer. The inherent-type radiation-curable adhesive is preferable because it does not need to contain, or contains little, an oligomer component or the like which is a low-molecular component, and thus can form an adhesive layer 3 having a stable layer structure without the oligomer component or the like moving in the adhesive over time.

[0048] As the base polymer into which the radiation-curable group is introduced, those having a carbon-carbon double bond and adhesiveness can be used without particular limitation. As such a base polymer, those having an acrylic polymer as a basic skeleton are preferable. Examples of the basic skeleton of the acrylic polymer include the acrylic polymers exemplified above.

[0049] The method for introducing the radiation-curable group into the acrylic polymer is not particularly limited, and various methods can be adopted. However, it is easy in terms of molecular design to introduce the radiation-curable group into the polymer side chain. For example, after copolymerizing a monomer having a functional group with an acrylic polymer in advance, a compound having a functional group capable of reacting with this functional group and a carbon-carbon double bond is subjected to a condensation or addition reaction while maintaining the radiation curability of the carbon-carbon double bond.

[0050] Examples of combinations of these functional groups include a carboxylic acid group and an epoxy group, a carboxylic acid group and an aziridyl group, a hydroxyl group and an isocyanate group, etc. Among these combinations of functional groups, a combination of a hydroxyl group and an isocyanate group is preferable because of the ease of reaction tracking. Further, as long as it is a combination that generates the acrylic polymer having the carbon-carbon double bond by the combination of these functional groups, the functional group may be on either side of the acrylic polymer and the compound. In the above-preferred combination, it is preferable that the acrylic polymer has a hydroxyl group and the compound has an isocyanate group. In this case, examples of the isocyanate compound having a carbon-carbon double bond include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, etc. Further, as the acrylic polymer, those copolymerized with the above-exemplified hydroxyl group-containing monomers, ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether are used.

[0051] The internal radiation-curable adhesive can use the base polymer having the carbon-carbon double bond (especially an acrylic polymer) alone, but it is also possible to blend a photopolymerizable compound such as the radiation-curable monomer component or oligomer component to such an extent that the properties are not deteriorated. The blending amount of the photopolymerizable compound is usually in the range of 30 parts by weight or less, preferably in the range of 0 to 10 parts by weight, based on 100 parts by weight of the base polymer.

[0052] It is preferable that the radiation-curable adhesive contains a photoinitiator when it is cured by ultraviolet rays or the like.

[0053] Among the above acrylic polymers, in particular, a (meth)acrylate copolymer in which a radiation-curable group is introduced into the side chain, more specifically, an acrylate represented by CH2=CHCOOR (wherein R is an alkyl group having 4 to 18 carbon atoms), a hydroxyl group-containing monomer, and an isocyanate compound having a radical-reactive carbon-carbon double bond in the molecule is preferably used.

[0054] The amount of the carbon-carbon double bond is preferably 1.2 to 1.8 meq / g. Regarding the amount of the double bond, the amount of the carbon-carbon double bond contained in about 10 g of the heat-dried adhesive can be quantitatively measured by the weight addition method by the bromine addition reaction in a dark place in a vacuum.

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

[0056] Examples of the double bond-containing isocyanate compound include methacryloyl isocyanate, acryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, and the like. The double bond-containing isocyanate compound can be used alone or in combination of two or more.

[0057] In addition, for radiation-curable adhesives, an external crosslinking agent can be appropriately used to adjust the adhesive strength before radiation irradiation and after radiation irradiation. Specific means of the external crosslinking method include a method of adding and reacting a so-called crosslinking agent such as a polyisocyanate compound, an epoxy compound, an aziridine compound, or a melamine-based crosslinking agent. When using an external crosslinking agent, its usage amount is appropriately determined according to the balance with the base polymer to be crosslinked and further according to the usage purpose as an adhesive. Generally, the usage amount of the external crosslinking agent is 20 parts by weight or less (preferably 0.1 part by weight to 10 parts by weight) based on 100 parts by weight of the base polymer. Furthermore, if necessary, additives such as various conventionally known tackifiers, antioxidants, and foaming agents may be blended in the radiation-curable adhesive in addition to the above components.

[0058] The polyester used for the polyester-based polymer is a polyester obtained by polycondensing a dicarboxylic acid component having two or more functional groups and a diol component, and the weight average molecular weight of the polyester is preferably 8,500 to 50,000. Further, the polyester preferably contains at least a dicarboxylic acid component having two or more functional groups, and the dicarboxylic acid component is preferably a dicarboxylic acid component having two carboxyl groups in the molecule.

[0059] The dicarboxylic acid is not particularly limited, and examples thereof include sebacic acid derived from castor oil, 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, dodecenyl succinic anhydride, fumaric acid, succinic acid, dodecanedioic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, itaconic acid, citraconic acid and other aliphatic and alicyclic dicarboxylic acids, and terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid and the like. Among them, in particular, dimer acid has a low glass transition temperature, can be used to design a flexible adhesive, can exhibit good wetting properties, and is a preferred embodiment. In addition, since dimer acid is a non-petroleum-derived material (plant-derived raw material), it can be environmentally friendly and is useful. These can be used alone or in combination of two or more.

[0060] Further, the polyester contains a diol component, and as the diol component, it is preferably contained at least one having two hydroxyl groups in the molecule. Among them, it is preferable to use aliphatic diols, polyether glycols, etc.

[0061] As the aliphatic diol, an aliphatic diol having an alkylene group with 3 to 10 carbon atoms is particularly preferred. The aliphatic diol having an alkylene group with 3 to 10 carbon atoms is not particularly limited, but specifically, 1,2-propylene glycol, 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, neopentyl glycol, 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-cyclohexanedimethanol, 1,2-cyclohexanedimethanol and other aliphatic glycols can be mentioned. These can be used alone or in combination of two or more.

[0062] In addition, the polyether glycol is not particularly limited, but it is preferable to use a polyether glycol having hydroxyl groups at both ends. As the polyether glycol having hydroxyl groups at both ends, the number average molecular weight (Mn) of the polyether glycol is not particularly limited. Specifically, polyalkylene ether glycols such as polytetramethylene ether glycol, polytrimethylene ether glycol, etc., a copolymer polyether polyol of 3-methyltetrahydrofuran and tetrahydrofuran with 1 to 20 mol% (for example, "PTG-L1000", "PTG-L2000", "PTG-L3500", etc. manufactured by Hodogaya Chemical Co., Ltd.), or a copolymer polyether glycol of neopentyl glycol and tetrahydrofuran are preferable. These can be used alone or in combination of two or more.

[0063] The polyester can be obtained by polycondensing a carboxylic acid component and a diol component. The molar ratio (OH / COOH) of the carboxyl group of the carboxylic acid component to the hydroxyl group of the diol component is preferably 1 or more, more preferably 1.02 to 3, still more preferably 1.04 to 2.60, and particularly preferably 1.06 to 2.40. When the molar ratio is less than 1, the terminal of the polyester (polymer) after polymerization becomes a carboxyl group, and there is a risk that crosslinking with a crosslinking agent (for example, an isocyanate-based crosslinking agent) cannot be carried out promptly, and there is also a risk that the holding force (cohesive force) of the adhesive layer cannot be sufficiently obtained.

[0064] In addition, it is also possible to polymerize or add other components other than the carboxylic acid component and the diol component after polymerization.

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

[0066] When a polyester-based polymer is used as the base polymer, the adhesive composition of the first adhesive layer preferably contains a fatty acid ester having no functional group and a molecular weight (molar molecular weight: g / mol) of 200 to 700 together with the polyester-based polymer. Examples of the fatty acid ester include isopropyl myristate, isopropyl palmitate, methyl linoleate, and dibasic acid esters such as adipic acid ester, sebacic acid ester, and phthalic acid ester. These can be used alone or in combination of two or more. The blending amount of the fatty acid ester is 10 to 150 parts by weight, preferably 20 to 150 parts by weight, more preferably 30 to 140 parts by weight, and still more preferably 40 to 130 parts by weight based on 100 parts by weight of the polyester-based polymer.

[0067] In addition, the adhesive composition contains a crosslinking agent together with the polyester-based polymer. The crosslinking agent is not particularly limited, and conventionally known ones can be used. For example, isocyanate-based crosslinking agents such as polyvalent isocyanurates and polyfunctional isocyanate compounds, polyfunctional melamine compounds, polyfunctional epoxy compounds, polyfunctional oxazoline compounds, polyfunctional aziridine compounds, metal chelate compounds, etc. can be used. These can be used alone or in combination of two or more.

[0068] In particular, it is preferable to use a conventionally known isocyanate-based crosslinking agent such as polyvalent isocyanurate or polyfunctional isocyanate. Examples of the polyvalent isocyanurate include a polyisocyanurate of hexamethylene diisocyanate. The polyfunctional isocyanate compound is preferably a compound having at least two or more isocyanate groups in the molecule, more preferably three or more, and is not particularly limited. Specifically, aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, etc. can be mentioned.

[0069] Also, prior to the peeling of the support member after the back grinding and polishing of the wafer, a wafer processing adhesive tape is bonded to the polished surface of the wafer. However, when it is bonded to the wafer surface before the formation of the oxide film immediately after the back grinding, there is a problem that the subsequent peeling of the wafer processing adhesive tape becomes difficult. Therefore, in order to make the peeling easy even when it is bonded to the wafer surface before the formation of the oxide film immediately after the back grinding, it is preferable to add polypropylene oxide to the adhesive.

[0070] The polypropylene oxide is not particularly limited and can be appropriately selected from conventional polypropylene oxides. The number average molecular weight of the polypropylene oxide is preferably greater than 3000 and not more than 10000, more preferably 4000 to 10000. If the number average molecular weight of the polypropylene oxide is too large, the affinity between the polypropylene oxide and the acrylic polymer (X) will be poor, resulting in contamination of the adherend. If the number average molecular weight of the polypropylene oxide is too small, the water resistance of the adhesive layer will be insufficient, the adhesive layer will swell due to cutting water, and the meandering of the dicing line will occur.

[0071] From the perspective of contamination to the wafer, polyoxypropylene-glyceryl ether having a number average molecular weight greater than 3000 and not more than 10000, more preferably 4000 to 10000, is preferred. By using polyoxypropylene-glyceryl ether having a number average molecular weight in this range, the number of hydroxyl groups in the polypropylene oxide molecule increases from 2 to 3. Therefore, the probability of incorporating polypropylene oxide into the crosslinked structure by reaction with a crosslinking agent such as polyisocyanate increases, and the migration of polypropylene oxide to the wafer interface and the contamination of the wafer surface can be reduced.

[0072] Examples of the polypropylene oxide having a number average molecular weight greater than 3000 and not more than 10000 include Uniol D-4000 (number average molecular weight 4000) ((trade name), manufactured by NOF Corporation), Preminol S4007 (number average molecular weight 5000) ((trade name), manufactured by Asahi Glass Co., Ltd.), Preminol S4011 (number average molecular weight 10000) ((trade name), manufactured by Asahi Glass Co., Ltd.), and the like. Examples of the polyoxypropylene-glyceryl ether having a number average molecular weight greater than 3000 and not more than 10000 include Uniol TG-4000 (number average molecular weight 4000) ((trade name), manufactured by NOF Corporation)), Preminol S3006 (number average molecular weight 5000) ((trade name), manufactured by Asahi Glass Co., Ltd.), Preminol S3011 (number average molecular weight 10000) ((trade name), manufactured by Asahi Glass Co., Ltd.), and the like, but are not limited thereto.

[0073] As for the compounding quantity of polypropylene oxide having a number average molecular weight of more than 3000 and not more than 10000, it can be appropriately selected from the range of 0.1 to 3.0 parts by mass, preferably 0.5 to 2.0 parts by mass with respect to 100 parts by mass of the base polymer. If the compounding quantity of polypropylene oxide is too small, when a wafer processing adhesive tape is bonded to an unstable wafer polishing surface where the natural oxide film is not formed entirely, it is impossible to efficiently pick up a thin semiconductor chip from a large-diameter wafer. If the compounding quantity of polypropylene oxide is too large, the adhesiveness before radiation curing becomes insufficient, the tip of the chip peels off during dicing, and cutting dust adheres to the back surface of the chip.

[0074] Note that the adhesive layer may have a structure in which a plurality of layers are laminated. When having a plurality of layers, the above-described adhesive may be used for all layers, but it is sufficient to use the above-described adhesive for at least one layer. Among the plurality of adhesive layers, when only one layer is composed of the above-described adhesive, it is preferable to use the above-described adhesive for the layer in contact with the base film. By using only one layer composed of the above-described adhesive and using the above-described adhesive for the layer in contact with the base film, when peeling the support member from the wafer, when the adhesive is dissolved and washed with a solvent, wrinkles are generated in the base film, stress is applied to the adhesive layer, and it is possible to prevent the adhesive force of the adhesive layer from decreasing and to hold the wafer sufficiently. Further, even if the second adhesive layer is dissolved in a solvent, since the first adhesive layer holds the second adhesive layer, it is possible to prevent the second adhesive layer from falling off and contaminating the wafer and reducing the yield.

[0075] The thickness of the adhesive layer is preferably 5 μm or more and 70 μm or less, more preferably 8 μm or more and 50 μm or less, and still more preferably 10 μm or more and 30 μm or less. If the adhesive layer is thinner than 5 μm, there is a possibility that sufficient adhesive force cannot be exhibited. On the other hand, if the adhesive layer is thicker than 70 μm, the force during expansion may not be sufficiently transmitted to the wafer, and there is a possibility that the wafer cannot be divided into chips. Further, if the adhesive layer is thicker than 30 μm, the parallel line transmittance of the wafer processing adhesive tape may decrease.

[0076] The method for forming the adhesive layer on the base film is not particularly limited. For example, in addition to applying and drying the above-mentioned adhesive composition on the base film by a commonly used coating method, it can also be produced by transferring the adhesive layer applied on the separator to the base film by laminating it with the base film.

[0077] For the adhesive tape for wafer processing, it is preferable that the amount of residual solvent after dropping 1 ml of p-menthane on the surface of the adhesive layer and allowing it to stand for 30 minutes is 1% (m / m) or less. If the amount of residual solvent is 1% (m / m) or less, when the adhesive that bonded the support member to the wafer is dissolved using a solvent and the support member is peeled off, and the adhesive remaining on the wafer is washed, wrinkles may occur in the base film of the adhesive tape for wafer processing, causing stress on the adhesive layer, resulting in a decrease in the adhesive strength of the adhesive layer and preventing the wafer from being sufficiently held. In addition, it is possible to prevent the adhesive layer of the adhesive tape for wafer processing from being dissolved by the solvent, contaminating the wafer, and reducing the yield.

[0078] After producing the adhesive tape for wafer processing (after taping), cut it into a 40 mm square, peel off the release liner, drop 1 mL of p-menthane, allow it to stand for 30 minutes, then discard the solvent, dry it at room temperature for 30 minutes, and immerse 1.0 g of the cut adhesive layer sample in 10 mL of acetone. The supernatant is measured under the following conditions by gas chromatography-mass spectrometry (GC-MS). [Analysis Conditions] Injection volume: 1 μL Column: db-1 0.25 mm × 30 m Inj: 200 °C (held at 40 °C for 4 minutes, then heated to 200 °C at 20 °C / min) He flow rate: 1.0 mL / min

[0079] To make the amount of residual solvent 1% (m / m) or less, it is advisable to set the glass transition temperature of the base polymer of the adhesive layer to -45 °C or higher.

[0080] The adhesive tape for wafer processing preferably has a parallel transmittance of 90% or more when light in the wavelength range of 1064 nm is incident from the substrate film side. If the parallel transmittance of light in the wavelength range of 1064 nm when incident from the substrate film side is 90% or more, when the wafer processing adhesive tape is irradiated with laser light having a wavelength of 1064 nm, the laser light with high straightness transmits through the wafer processing adhesive tape with a high transmittance. Also preferably, the parallel transmittance of light in the wavelength range of 400 to 600 nm when incident from the substrate film side is 90% or more, and more preferably, the parallel transmittance of light in the wavelength range of 400 to 1400 nm when incident from the substrate film side is 90% or more. If the parallel transmittance of light in the wavelength range of 400 to 1400 nm when incident from the substrate film side is 90% or more, when the wafer processing adhesive tape is irradiated with laser light having a wavelength in the visible region or the infrared region, the laser light with high straightness transmits through the wafer processing adhesive tape with a high transmittance. Therefore, appropriately, the wafer can be divided, the state of the chip can be inspected, or laser marking can be performed using laser light through the wafer processing tape. The parallel transmittance is measured in accordance with JIS K 7361-1:1999.

[0081] Incidentally, the adhesive tape for wafer processing may, if necessary, have a synthetic resin film, which is usually used as a separator to protect the adhesive layer, attached to the adhesive layer side until it is put into practical use. Examples of the constituent material of the synthetic resin film include synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate, and paper. The surface of the synthetic resin film may be subjected to a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment, if necessary, to enhance the releasability from the adhesive layer. The thickness of the synthetic resin film is usually about 10 to 100 μm, preferably about 25 to 50 μm.

[0082] (Step of dissolving the adhesive with a solvent and cleaning the wafer) When peeling the wafer from the support member, a wafer processing adhesive tape and a ring frame are attached to the surface of the wafer where the support member is not attached. Then, the wafer and the support member supported by the wafer processing adhesive tape and the ring frame are immersed in an organic solvent to dissolve the adhesive that has attached the support member to the wafer, peel off the support member, and clean the surface of the wafer where the adhesive has adhered. In addition to the above method, in order to peel the wafer from the support member, there are also methods such as heating to soften the adhesive and sliding the support member to peel it off, and decomposing the adhesive by laser light irradiation to peel the support member. Even when these methods are used, adhesives or their decomposition products may remain on the wafer surface after peeling the support member. Therefore, in order to remove these residues, the wafer supported by the wafer processing adhesive tape and the ring frame is immersed in an organic solvent to clean the wafer, or the wafer is rotated while spraying the organic solvent onto the wafer to clean the wafer.

[0083] The adhesive tape for electronic components according to the present invention includes the following aspects.

[0084] [1] A wafer processing adhesive tape comprising a base film and at least one adhesive layer formed on the base film, The adhesive layer is formed of an adhesive composition containing an acrylic polymer or a polyester polymer as a base polymer, The glass transition temperature of the base polymer is -45°C or higher, A wafer processing adhesive tape characterized in that the parallel line transmittance when light in the wavelength region of 1064 nm is incident from the base film side is 90% or higher.

[0085] [2] The wafer processing adhesive tape according to [1], wherein the base film is composed of a polyolefin resin.

[0086] [3] The wafer processing adhesive tape according to [1] or [2], wherein the thickness of the base film is less than 100 μm.

[0087] [4] The adhesive tape for wafer processing according to any one of [1] to [3], wherein the amount of residual solvent after dropping 1 ml of p-menthane on the surface of the adhesive layer and allowing it to stand for 30 minutes is 1% or less, m / m.

[0088] [5] The adhesive tape for wafer processing according to any one of [1] to [4], which is used in a method for processing a wafer including a step of cleaning the wafer with a solvent.

[0089] Next, the present invention will be described in more detail based on examples. Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to these examples.

[0090] (1) Preparation of base film <Base film 1> An ethylene-vinyl acetate copolymer (manufactured by NUC Corporation, trade name "NUC-3660") was used, melted at 140°C, and formed into a base film 1 with a thickness of 80 μm using an extruder. <Base film 2> An ethylene-methacrylic acid-(2-methyl-propyl acrylate)-Zn++ ionomer resin (manufactured by Mitsui DuPont Polychemical Co., Ltd., trade name "Hymilan AM7316") was melted at 140°C and formed into a base film 2 with a thickness of 100 μm using an extruder. <Base film 3> Polypropylene (manufactured by Prime Polymer Co., Ltd., trade name "F227D") was melted at 140°C and formed into a base film 3 with a thickness of 70 μm using an extruder.

[0091] (2) Preparation of adhesive <Adhesive 1> An acrylic copolymer consisting of ethyl acrylate (81 wt%), methacrylic acid (1 wt%), and 2-hydroxyethyl acrylate (18 wt%) was prepared. Then, 2-methacryloyloxyethyl isocyanate was added to react the OH groups at the ends of the 2-hydroxyethyl acrylate side chains of this acrylic copolymer with the NCO groups of 2-methacryloyloxyethyl isocyanate, and a residue having a (meth)acrylic monomer part with a radiation-curable carbon-carbon double bond-containing group was bonded to the repeating unit of the main chain to obtain an acrylic polymer as a base polymer. When the glass transition temperature of this acrylic polymer was measured by a differential scanning calorimeter (DSC), it was -20°C. To 100 parts by mass of the acrylic polymer, 2 parts by mass of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "Coronate L") and 1.5 parts by mass of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 184") were added and mixed to obtain an acrylic pressure-sensitive adhesive 1.

[0092] <Pressure-sensitive adhesive 2> Nichigo polyester (registered trademark) S-0097S55EO, manufactured by Mitsubishi Chemical Corporation, which is a pressure-sensitive adhesive containing a polyester-based polymer as a base polymer, was prepared. The glass transition temperature of the polyester-based polymer as the base polymer is 1°C. To 100 parts by mass of the polyester-based polymer, 3 parts by mass of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "Coronate L") was added and mixed to obtain a polyester-based pressure-sensitive adhesive 2.

[0093] <Pressure-sensitive adhesive 3> An acrylic copolymer consisting of butyl acrylate (70 wt%), methacrylic acid (1 wt%), and 2-hydroxyethyl acrylate (29 wt%) was prepared. Then, 2-methacryloyloxyethyl isocyanate was added to react the OH group at the terminal of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer with the NCO group of 2-methacryloyloxyethyl isocyanate, thereby bonding a residue having a (meth)acrylic monomer part with a radiation-curable carbon-carbon double bond-containing group to the repeating unit of the main chain to obtain a polymer (a). When the glass transition temperature was measured by a differential scanning calorimeter (DSC), it was -45°C. To 100 parts by mass of (a), 2 parts by mass of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "Coronate L") and 1.5 parts by mass of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 184") were added and mixed to obtain an acrylic adhesive 3.

[0094] <Adhesive 4> An acrylic copolymer consisting of 2-ethylhexyl acrylate (78 wt%), methacrylic acid (1 wt%), and 2-hydroxyethyl acrylate (21 wt%) was prepared. Then, 2-methacryloyloxyethyl isocyanate was added to react the OH group at the terminal of the 2-hydroxyethyl acrylate side chain of this acrylic copolymer with the NCO group of 2-methacryloyloxyethyl isocyanate, thereby bonding a residue having a (meth)acrylic monomer part with a radiation-curable carbon-carbon double bond-containing group to the repeating unit of the main chain to obtain a polymer (a). When the glass transition temperature was measured by a differential scanning calorimeter (DSC), it was -64°C. To 100 parts by mass of (a), 2 parts by mass of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "Coronate L") and 1.5 parts by mass of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 184") were added and mixed to obtain an acrylic adhesive 4.

[0095] <Adhesive 5> An acrylic copolymer consisting of 2-ethylhexyl acrylate (69 wt%), methyl methacrylate (10 wt%), 2-hydroxyethyl acrylate (20 wt%), and methacrylic acid (1 wt%) was prepared. Subsequently, 2-methacryloyloxyethyl isocyanate was added to react the OH groups at the terminals of the 2-hydroxyethyl acrylate side chains of this acrylic copolymer with the NCO groups of 2-methacryloyloxyethyl isocyanate, thereby bonding a residue having a (meth)acrylic monomer part with a radiation-curable carbon-carbon double bond-containing group to the repeating unit of the main chain, and an acrylic polymer was obtained as a base polymer. When the glass transition temperature of this acrylic polymer was measured by a differential scanning calorimeter (DSC), it was -50°C. To 100 parts by mass of the acrylic polymer, 2 parts by mass of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "Coronate L") and 1.5 parts by mass of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 184") were added and mixed to obtain an acrylic adhesive 6.

[0096] (3) Preparation of an Adhesive Tape for Wafer Processing <Example 1> The adhesive composition obtained by dissolving and stirring Adhesive 1 in ethyl acetate was coated on a release liner made of a polyethylene terephthalate film subjected to a release treatment so that the thickness after drying would be 10 μm, dried at 110°C for 3 minutes, and then laminated with Substrate Film 1 to prepare an adhesive tape for wafer processing according to Example 1 in which an adhesive layer was formed on the substrate film.

[0097] <Examples 2 to 5, Comparative Examples 1 and 2> Adhesive tapes according to Examples 2 to 5 and Comparative Examples 1 and 2 were prepared by the same method as in Example 1, except that the substrate film and the adhesive were combined as described in Table 1.

[0098] <Example 6> The pressure-sensitive adhesive composition obtained by dissolving the pressure-sensitive adhesive 1 in ethyl acetate and stirring it was applied to a release liner made of a polyethylene terephthalate film subjected to a release treatment so that the thickness after drying would be 10 μm, dried at 110°C for 3 minutes, and then laminated to the base film 1 to form a pressure-sensitive adhesive layer on the base film. Further, the pressure-sensitive adhesive composition obtained by dissolving the pressure-sensitive adhesive 4 in ethyl acetate and stirring it was applied to a release liner made of a polyethylene terephthalate film subjected to a release treatment so that the thickness after drying would be 10 μm, dried at 110°C for 3 minutes to obtain a second pressure-sensitive adhesive layer. Thereafter, the release liner was peeled off from the pressure-sensitive adhesive layer, and the second pressure-sensitive adhesive layer was laminated on the pressure-sensitive adhesive layer to prepare a pressure-sensitive adhesive tape according to Example 6.

[0099] <Measurement of Residual Solvent Amount> After the production of the pressure-sensitive adhesive tape for wafer processing (after taping), it was cut into a 40 mm square, the release liner was peeled off, 1 mL of p-menthane was dropped, and it was allowed to stand for 30 minutes. Thereafter, the solvent was discarded, dried at room temperature for 30 minutes, and 1.0 g of the cut pressure-sensitive adhesive layer sample was immersed in 10 mL of acetone. The supernatant was measured under the following conditions by gas chromatography-mass spectrometry (GC-MS). The results are shown in Tables 1 and 2. [Analysis Conditions] Injection volume: 1 μL Column: db-1 0.25 mm × 30 m Inj: 200°C (held at 40°C for 4 minutes and then heated to 200°C at 20°C / min) He flow rate: 1.0 mL / min

[0100] <Measurement of Parallel Light Transmittance> Light was made incident from the base film side of the pressure-sensitive adhesive tape for wafer processing according to the Examples and Comparative Examples, and the parallel light transmittance was measured. The measurement was carried out in the range of 400 to 1400 nm in accordance with JIS K 7361-1:1999 using a UV-3101 spectrophotometer manufactured by Shimadzu Corporation to obtain the parallel light transmittance at 1064 nm. The results are shown in Table 1.

[0101] <Evaluation of Solvent Resistance> An 8-inch wafer was bonded with the adhesive tapes for wafer processing according to the examples and comparative examples, fixed to a ring frame, and then spin-cleaned at 2000 rpm while blowing p-menthane as an organic solvent from the wafer side. After the cleaning and drying were completed, the adhesive layer in the area where the dicing tape for wafer processing was not adhered to the wafer was observed. Those in which no dissolution or swelling of the adhesive was observed were evaluated as good products with ○, and those in which dissolution or swelling of the adhesive was observed were evaluated as defective products with ×. The results are shown in Table 1.

[0102] <Evaluation of Wafer Divisibility> A ground wafer with a diameter of 8 inches and a thickness of 50 μm was bonded with the adhesive tapes for wafer processing according to the examples and comparative examples. An 8-inch frame was used as the ring frame. This was installed in a laser processing apparatus ML200 manufactured by Tokyo Seimitsu Co., Ltd., and laser light was incident from the side of the adhesive tape for wafer processing so that the focal point was aligned inside the wafer, and a modified region was formed by multi-photon absorption along the cutting planned line where the chip size was 5 mm × 5 mm. Then, using the expand device attached to the laser processing apparatus ML200, the adhesive sheet was stretched at a pull-down amount of 20 mm and an expand speed of 10 mm / s, and the wafer division process was carried out. The laser processing conditions are as follows. After the wafer division process, the divisibility was visually observed. Those in which the wafer was divided well were evaluated as excellent products with ◎, those in which the division was partially incomplete but there was no practical problem were evaluated as good products with ○, and those in which the wafer was not divided were evaluated as defective products with ×. The results are shown in Table 1.

[0103] [Laser] Light source: Semiconductor laser-excited Nd:YAG laser Wavelength: 1064 nm Laser light spot cross-sectional area: 3.14×10 -8 cm 2 Oscillation mode: Q-switch pulse Repetition frequency: 100 kHz Pulse width: 30 ns Output: 20 μJ / pulse Laser light quality: TEM0040 Polarization characteristic: Linear polarization

[0104] [Lens for light collection] Magnification: 50x NA: 0.55 Transmittance with respect to the laser light wavelength: 60 percent

[0105] [Moving speed of the mounting table on which the substrate is placed] Moving speed: 100 mm / sec

[0106] <Evaluation of laser marking property> An 8-inch diameter wafer was bonded with the wafer processing adhesive tape according to the examples and comparative examples. From the side of the wafer processing adhesive tape, printing was performed on the wafer using a laser marking device (Laser Marker MD-H9800 manufactured by Keyence Corporation) with laser light (YAG laser). The printing was performed by continuously forming dots with a diameter of 50 μm and a depth of 15 μm by the laser light. Also, as a comparison target, the same printing was performed on the same wafer without using the wafer processing adhesive tape. Compared with the comparison target, those with no deterioration in the visibility of the imprint were evaluated as good products with ○, and those with deteriorated visibility were evaluated as defective products with ×. The results are shown in Table 1.

[0107]

Table 1

[0108] As shown in Table 1, the wafer processing adhesive tape according to the examples was formed of an adhesive composition in which the adhesive layer contains an acrylic polymer or a polyester polymer as a base polymer, and since the glass transition temperature of the base polymer is -45°C or higher, excellent results were obtained in the evaluation of solvent resistance. Also, since the parallel line transmittance when light is incident from the substrate film side in the wavelength region of 1064 nm is 90% or higher, excellent results were obtained in the evaluation of wafer breakability and laser marking property.

[0109] On the other hand, the adhesive tape for wafer processing according to the comparative example was formed of an adhesive composition in which the adhesive layer contains an acrylic polymer or a polyester polymer as a base polymer, and since the glass transition temperature of the base polymer was lower than -45°C, the result was inferior in the evaluation of solvent resistance.

Claims

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

2. 2. The adhesive tape for wafer processing according to claim 1, wherein the base film is made of a polyolefin resin.

3. 3. The adhesive tape for wafer processing according to claim 1, wherein the thickness of the base film is less than 100 μm.

4. An adhesive tape for wafer processing as described in claim 1 or claim 2, characterized in that it is used in a wafer processing method including a wafer cleaning step using a solvent.

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