Semiconductor processing sheet

Abstract

Provided is a semiconductor processing sheet which has excellent adhesion to a semiconductor wafer and from which a protective layer and an adhesive layer can be easily released. A semiconductor processing sheet according to an embodiment of the present invention comprises, in the following order, a substrate, an adhesive layer composed of an ultraviolet-curable adhesive, and a protective layer containing a hydrophilic polymer, wherein the tensile storage elastic modulus of the adhesive layer after ultraviolet irradiation is 1.0×105 Pa to 1.0×108 Pa.

Description

Semiconductor processing sheets

[0001] The present invention relates to a semiconductor processing sheet.

[0002] Semiconductor chips are used in a variety of applications, including personal computers, smartphones, and automobiles. Semiconductor chips are typically manufactured by thinning a semiconductor wafer in a back-grinding process and then dicing it into small pieces. In the semiconductor chip processing process, an adhesive sheet is used to protect the semiconductor wafer surface during processing. A method has also been proposed in which a tape made by laminating an adhesive sheet used in the back-grinding process and a water-soluble film onto a semiconductor wafer, followed by peeling off only the adhesive sheet and laminating the water-soluble film on the semiconductor wafer surface, followed by a dicing process, etc. (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-43723

[0004] However, if the adhesion between the water-soluble film and the adhesive layer is high, it becomes difficult to leave the water-soluble protective film on the semiconductor wafer surface after the back-grinding process, making it difficult to adequately protect the semiconductor wafer surface during the dicing process. In recent years, large-scale integrated circuits (LSIs) have become increasingly miniaturized and highly functional, resulting in more complex wafer surface structures. In order to produce an adhesive sheet that can adequately adhere to complex wafer surfaces, a more flexible adhesive is used. When a flexible adhesive is used, adhesion to the water-soluble film also increases, making it even more difficult to peel the water-soluble film from the adhesive sheet. The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a semiconductor processing sheet that has excellent adhesion to the semiconductor wafer and allows the protective layer and adhesive layer to be easily peeled off.

[0005] 1. A semiconductor processing sheet according to an embodiment of the present invention includes a substrate, a pressure-sensitive adhesive layer made of an ultraviolet-curable pressure-sensitive adhesive, and a protective layer containing a hydrophilic polymer, in this order, and the pressure-sensitive adhesive layer has a tensile storage modulus of 1.0 × 10 after ultraviolet irradiation. ５ Pa ~ 1.0 x 10 ８Pa. 2. In the semiconductor processing sheet described in 1 above, the difference between the contact angle of the pressure-sensitive adhesive layer with water and the contact angle of the protective layer with water after ultraviolet irradiation may exceed 30°. 3. In the semiconductor processing sheet described in 1 or 2 above, the ultraviolet-curable pressure-sensitive adhesive may contain a polymer into which a polymerizable carbon-carbon double bond has been introduced. 4. In the semiconductor processing sheet described in any one of 1 to 3 above, the T-peel strength between the pressure-sensitive adhesive layer and the protective layer after ultraviolet irradiation may be 0.5 N / 50 mm or less.

[0006] According to an embodiment of the present invention, a semiconductor processing sheet is provided which has excellent adhesion to a semiconductor wafer and allows the protective layer and adhesive layer to be easily peeled off.

[0007] 3A is a schematic cross-sectional view of a semiconductor processing sheet according to one embodiment of the present invention; FIG. 3B is a schematic cross-sectional view of a step of stacking a semiconductor processing sheet according to an embodiment of the present invention and a semiconductor wafer; FIG. 3C is a schematic cross-sectional view showing the stacked state of a semiconductor processing sheet according to an embodiment of the present invention and a thinned semiconductor wafer; FIG. 3D is a schematic cross-sectional view illustrating a step of fixing a thinned semiconductor wafer to a dicing tape; FIG. 3E is a schematic schematic view illustrating a step of peeling the base material and adhesive layer of a semiconductor processing sheet according to an embodiment of the present invention from a semiconductor wafer; FIG. 3F is a schematic schematic view illustrating a cutting step of a protective layer; FIG. 3G is a schematic schematic view illustrating a state after laser irradiation of the protective layer; FIG. 3H is a schematic schematic view illustrating a step of dividing a semiconductor wafer; FIG. 3I is a schematic schematic view illustrating an example of a protective layer removal step; FIG. 3J is a schematic schematic view illustrating a recovery step of diced semiconductor wafers; FIG. 3J is a schematic schematic view illustrating a step of forming grooves in a semiconductor wafer for dividing the semiconductor wafer; FIG. 3A is a schematic schematic view illustrating a step of stacking a semiconductor wafer processing sheet according to an embodiment of the present invention on the semiconductor wafer with grooves formed thereon; FIG. 3B is a schematic schematic view illustrating a state after the semiconductor wafer of FIG. 3B has been thinned. 1 is a schematic diagram illustrating a process of laminating a thinned semiconductor wafer to a dicing tape; 2 is a schematic diagram illustrating a process of peeling a substrate and an adhesive layer of a semiconductor processing sheet according to an embodiment of the present invention from a semiconductor wafer; 3 is a schematic diagram illustrating a semiconductor wafer subjected to an expanding process; 4 is a schematic diagram illustrating an example of a protective layer removing process;

[0008] A. Overview of the Semiconductor Processing Sheet The semiconductor processing sheet according to an embodiment of the present invention comprises a substrate, a pressure-sensitive adhesive layer made of an ultraviolet-curable pressure-sensitive adhesive, and a protective layer containing a hydrophilic polymer, in this order, and the pressure-sensitive adhesive layer has a tensile storage modulus of 1.0 × 10 after ultraviolet irradiation. ５ Pa ~ 1.0 x 10 ８ Pa. Such a semiconductor processing sheet can provide a semiconductor processing sheet that has excellent adhesion to the semiconductor wafer and allows the protective layer and adhesive layer to be easily peeled off. The semiconductor processing sheet of an embodiment of the present invention can be used in the same manner as backgrinding tape commonly used in semiconductor wafer processing processes, and can properly support the semiconductor wafer in the backgrinding process. Usually, the backgrinding tape is peeled off after the thinned semiconductor wafer is replaced with another adhesive sheet such as dicing tape. In the semiconductor processing sheet of an embodiment of the present invention, the substrate and adhesive layer are peeled off from the semiconductor wafer after the backgrinding process, and the protective layer remains on the surface of the semiconductor wafer as the adherend. As described above, the tensile storage modulus of the adhesive layer after ultraviolet irradiation is 1.0 × 10 ５ Pa ~ 1.0 x 10 ８ Pa. With a semiconductor processing sheet having such an adhesive layer, the adhesive layer and the protective layer can be easily peeled off. As a result, the protective layer can be maintained in sufficient adhesion to the semiconductor wafer surface, and the semiconductor wafer surface can be properly protected in subsequent processes. Furthermore, the semiconductor processing sheet of the embodiment of the present invention can easily peel off the adhesive layer and the protective layer even when a softer adhesive is used as the adhesive constituting the adhesive layer. Therefore, a semiconductor processing sheet can be provided that has adhesion to a semiconductor wafer surface having a complex surface structure, which was previously difficult, and in which the adhesive layer and the protective layer can be easily peeled off.

[0009] 1 is a schematic cross-sectional view of a semiconductor processing sheet according to one embodiment of the present invention. The illustrated semiconductor processing sheet 100 includes, in this order, a substrate 10, an adhesive layer 20, and a protective layer 30. The semiconductor processing sheet 100 is used, for example, by bonding the protective layer 30 to a semiconductor wafer as an adherend so that the protective layer 30 comes into contact with the semiconductor wafer. Although not shown, in practice, a release liner is attached to the protective layer 30 to protect it until use.

[0010] Semiconductor processing sheet 100 may further include any appropriate layer (not shown). For example, semiconductor processing sheet 100 may have an intermediate layer between substrate 10 and adhesive layer 20. If an intermediate layer is included, adhesion to the adherend may be further improved, and conformability to the unevenness of the adherend surface may also be improved. Semiconductor processing sheet 100 may also have an antistatic layer. If an antistatic layer is included, peeling charge can be suppressed when peeling off the semiconductor processing sheet. The antistatic layer may be arranged in any appropriate position.

[0011] The difference between the water contact angle of the pressure-sensitive adhesive layer 20 and the water contact angle of the protective layer 30 after UV irradiation is preferably greater than 30°, more preferably 32° or greater, and more preferably 35° or greater. If the difference between the water contact angle of the pressure-sensitive adhesive layer 20 and the water contact angle of the protective layer 30 after UV irradiation is within the above range, a semiconductor processing sheet can be provided that has excellent adhesion to a semiconductor wafer and allows the protective layer and the pressure-sensitive adhesive layer to be easily peeled off. The greater the difference between the water contact angle of the pressure-sensitive adhesive layer 20 and the water contact angle of the protective layer 30 after UV irradiation, the more preferable it is, for example, below the measurement limit (e.g., 115.2° or less). In this specification, the water contact angle refers to the contact angle measured in accordance with JIS R 3257.

[0012] The thickness of the semiconductor processing sheet can be set to any appropriate value, preferably 50 μm to 1000 μm, more preferably 100 μm to 300 μm.

[0013] B. Substrate The substrate may be made of any appropriate resin. Specific examples of resins constituting the substrate include polyester-based resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN); polyolefin-based resins such as ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, polyethylene, polypropylene, and ethylene-propylene copolymer; polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, celluloses, fluorine-based resins, polyethers, polystyrene-based resins such as polystyrene; polycarbonate; and polyethersulfone.

[0014] The substrate 10 may further contain other components as long as the effects of the present invention are not impaired. Examples of other components include antioxidants, ultraviolet absorbers, light stabilizers, and heat stabilizers. The types and amounts of other components can be any appropriate amount depending on the purpose.

[0015] In one embodiment, the substrate 10 may have an antistatic function. If the substrate has an antistatic function, it can suppress the generation of static electricity when the tape is peeled off, thereby suppressing static-induced circuit destruction and adhesion of foreign matter. The substrate may have an antistatic function by forming the substrate using a resin containing an antistatic agent, or by forming an antistatic layer by applying a composition containing an antistatic component such as a conductive polymer, an organic or inorganic conductive material, and an antistatic agent to any appropriate film. When the substrate has an antistatic layer, it is preferable that an intermediate layer be laminated on the surface on which the antistatic layer is formed.

[0016] When the substrate 10 has an antistatic function, the surface resistance of the substrate is, for example, 1.0×10 ２ Ω / □ to 1.0 x 10 １３ Ω / □, preferably 1.0×10 ６ Ω / □ to 1.0 x 10 １２ Ω / □, and more preferably 1.0×10 ７Ω / □ to 1.0 x 10 １１ Ω / □. By having the surface resistance value in the above range, the generation of static electricity when peeling the adhesive layer and the protective layer can be suppressed, and the destruction of the circuit due to static electricity and the adhesion of foreign matter can be prevented. When a substrate having an antistatic function is used as the substrate, the surface resistance value of the obtained semiconductor processing sheet can be, for example, 1.0 × 10 ６ Ω / □ to 1.0 x 10 １２ It can be Ω / □.

[0017] The thickness of the substrate can be set to any appropriate value, and is preferably 10 μm to 200 μm, and more preferably 20 μm to 150 μm.

[0018] C. Adhesive Layer The adhesive layer 20 is a layer composed of an ultraviolet-curable adhesive. The adhesive layer 20 typically contains an ultraviolet-curable adhesive and a photopolymerization initiator. If the adhesive layer 20 is composed of an ultraviolet-curable adhesive, a semiconductor processing sheet can be obtained that has an adhesive layer that has excellent adhesion to the semiconductor wafer as an adherend before ultraviolet irradiation and that can be easily peeled from the protective layer after ultraviolet irradiation.

[0019] C-1. UV-Curable Pressure-Sensitive Adhesive Any suitable pressure-sensitive adhesive can be used as the UV-curable pressure-sensitive adhesive. For example, the pressure-sensitive adhesive may be an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a polyvinyl ether pressure-sensitive adhesive, or other suitable pressure-sensitive adhesive to which a UV-curable monomer and / or oligomer has been added, or may be an adhesive using a polymer having a polymerizable carbon-carbon double bond introduced into the side chain and / or terminal as the base polymer. Preferably, an adhesive using a polymer having a polymerizable carbon-carbon double bond introduced into the side chain and / or terminal as the base polymer is used, and more preferably, an adhesive using a polymer having a polymerizable carbon-carbon double bond introduced into the side chain is used.

[0020] When using a pressure-sensitive adhesive containing a polymer having a polymerizable carbon-carbon double bond introduced into the side chain and / or terminal, a polymer having a polymerizable carbon-carbon double bond introduced into the side chain and / or terminal and having adhesive properties is used as the base polymer. Examples of such polymers include polymers having a polymerizable carbon-carbon double bond introduced into a resin such as an acrylic resin, a vinyl alkyl ether resin, a silicone resin, a polyester resin, a polyamide resin, a urethane resin, or a styrene-diene block copolymer. Preferably, an acrylic resin having a polymerizable carbon-carbon double bond introduced into the acrylic resin is used. The use of an acrylic resin facilitates adjustment of the storage modulus and tensile modulus of the UV-curable pressure-sensitive adhesive layer, and also allows for the production of a semiconductor processing sheet with an excellent balance between adhesive strength and releasability. Furthermore, contamination of semiconductor wafers by components derived from the pressure-sensitive adhesive can be reduced.

[0021] The monomer composition used in the polymerization of the base polymer may contain any appropriate monomer. The monomer component preferably contains a (meth)acrylic monomer having a side chain with 8 or more carbon atoms. Any appropriate monomer can be used as the (meth)acrylic monomer having a side chain with 8 or more carbon atoms. Examples include 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, and dodecyl (meth)acrylate. Only one type of (meth)acrylic monomer having a side chain with 8 or more carbon atoms may be used, or two or more types may be used in combination. In this specification, "(meth)acrylic" refers to acrylic and / or methacrylic.

[0022] The monomer composition may contain any other appropriate monomer in addition to the (meth)acrylic monomer having 8 or more carbon atoms. Examples of other monomers include esters of acrylic acid or methacrylic acid having a linear or branched alkyl group having 30 or less carbon atoms; carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; 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, 10-hydroxydecyl (meth)acrylate, and the like. Examples of functional group-containing monomers include hydroxyl group-containing monomers such as 12-hydroxylauryl acrylate, (4-hydroxymethylcyclohexyl)-methyl acrylate, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether; sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and phosphate group-containing monomers such as 2-hydroxyethylacryloylphosphate. The inclusion of a functional group-containing monomer allows for the production of an acrylic resin in which polymerizable carbon-carbon double bonds are easily introduced. The content of the functional group-containing monomer can be adjusted to any appropriate range. The content of the functional group-containing monomer is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 12 mol% or more. The content of the functional group-containing monomer is, for example, 40 mol% or less. If the content of the functional group-containing monomer is too high, the polarity becomes high and the adhesive strength of the adhesive layer may become too high.A hydroxyl group-containing monomer is preferably used as the functional group-containing monomer.

[0023] A polyfunctional monomer may be used as another monomer. The use of a polyfunctional monomer can enhance the cohesive strength, heat resistance, adhesiveness, etc. of the adhesive. Furthermore, the UV-curable adhesive layer contains fewer low-molecular-weight components, resulting in a semiconductor processing sheet that is less likely to contaminate semiconductor wafers. Examples of polyfunctional monomers include hexanediol (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, and urethane (meth)acrylate. The polyfunctional monomer can be used in any appropriate content ratio.

[0024] The weight-average molecular weight of the base polymer (e.g., (meth)acrylic resin) is preferably 150,000 or more, more preferably 200,000 or more, and even more preferably 250,000 or more. The weight-average molecular weight of the base polymer is, for example, less than 1,000,000. Within this range, bleeding of low molecular weight components can be prevented, and a low-contamination semiconductor processing sheet can be obtained. The molecular weight distribution (weight-average molecular weight / number-average molecular weight) of the (meth)acrylic resin is preferably 1 to 20, more preferably 3 to 10. By using a (meth)acrylic resin with a narrow molecular weight distribution, bleeding of low molecular weight components can be prevented, and a low-contamination semiconductor processing sheet can be obtained. The weight-average molecular weight and number-average molecular weight can be determined by gel permeation chromatography (solvent: tetrahydrofuran, polystyrene equivalent).

[0025] A polymer having a polymerizable carbon-carbon double bond introduced into its side chain and / or terminal can be obtained by any appropriate method. For example, it can be obtained by reacting (e.g., condensation reaction, addition reaction) a resin obtained by any appropriate polymerization method with a compound having a polymerizable carbon-carbon double bond. Specifically, when an acrylic resin is used, an acrylic resin (copolymer) having structural units derived from a monomer having any appropriate functional group is polymerized in any appropriate solvent, and then the functional group of the acrylic resin is reacted with a compound having a polymerizable carbon-carbon double bond that can react with the functional group to obtain an acrylic resin having a polymerizable carbon-carbon double bond. The amount of the compound having a polymerizable carbon-carbon double bond to be reacted is preferably 4 to 30 parts by weight, more preferably 4 to 20 parts by weight, per 100 parts by weight of the base polymer (acrylic resin). Any appropriate solvent can be used, including, for example, various organic solvents such as ethyl acetate, methyl methyl ketone, and toluene.

[0026] When reacting a resin with a compound having a polymerizable carbon-carbon double bond as described above, it is preferable that the resin and the compound having a polymerizable carbon-carbon double bond each have a functional group capable of reacting with each other. Examples of functional group combinations include a carboxyl group / epoxy group, a carboxyl group / aziridine group, and a hydroxyl group / isocyanate group. Among these functional group combinations, the combination of a hydroxyl group and an isocyanate group is preferred because it allows for easy reaction tracking.

[0027] Examples of compounds having a polymerizable carbon-carbon double bond include 2-isocyanatoethyl methacrylate, methacryloisocyanate, 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), and m-isopropenyl-α,α-dimethylbenzyl isocyanate.

[0028] When using a pressure-sensitive adhesive containing an ultraviolet-curable monomer and / or oligomer, any suitable monomer or oligomer can be used as the ultraviolet-curable monomer and oligomer. Examples of ultraviolet-curable monomers include urethane (meth)acrylate, 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. Examples of ultraviolet-curable oligomers include urethane-based oligomers, polyether-based oligomers, polyester-based oligomers, polycarbonate-based oligomers, and polybutadiene-based oligomers. Oligomers with a molecular weight of approximately 100 to 30,000 are preferably used. The monomers and oligomers may be used alone or in combination of two or more.

[0029] The monomer and / or oligomer may be used in any appropriate amount depending on the type of PSA used. For example, the amount is preferably 100 parts by weight or less, and more preferably 5 to 50 parts by weight, per 100 parts by weight of the base polymer constituting the PSA. The monomer and / or oligomer may not be present.

[0030] C-2. Photopolymerization Initiator Any appropriate initiator can be used as the photopolymerization initiator. Examples of the photopolymerization initiator include acylphosphine oxide photoinitiators such as ethyl 2,4,6-trimethylbenzylphenylphosphinate and (2,4,6-trimethylbenzoyl)phenylphosphine oxide; α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenylketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and benzyl dimethyl ketal. aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphonates; and α-hydroxyacetophenones such as 2-hydroxy-1-(4-(4-(2-hydroxy)-2-methylpropionyl)benzyl)phenyl-2-methylpropane-1. Preferably, 2,2-dimethoxy-2-phenylacetophenone and 2-hydroxy-1-(4-(4-(2-hydroxy)-2-methylpropionyl)benzyl)phenyl-2-methylpropane-1 can be used. The photopolymerization initiator may be used alone or in combination of two or more.

[0031] As the photopolymerization initiator, commercially available products may be used, for example, Omnirad 127 and Omnirad 651, both of which are trade names of IGM Resins.

[0032] The photopolymerization initiator is used in any appropriate amount. The content of the photopolymerization initiator is preferably 0.5 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, relative to 100 parts by weight of the ultraviolet-curable pressure-sensitive adhesive. If the content of the photopolymerization initiator is less than 0.5 parts by weight, there is a risk that the pressure-sensitive adhesive will not cure sufficiently upon ultraviolet irradiation. If the content of the photopolymerization initiator exceeds 10 parts by weight, there is a risk that the storage stability of the pressure-sensitive adhesive will decrease.

[0033] C-3. Additives The pressure-sensitive adhesive layer-forming composition may contain any appropriate additives as needed. Examples of the additives include crosslinkers, catalysts (e.g., platinum catalysts), tackifiers, plasticizers, pigments, dyes, fillers, antioxidants, conductive materials, UV absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, solvents, etc.

[0034] In one embodiment, the pressure-sensitive adhesive layer-forming composition further contains a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, and chelate-based crosslinking agents. The content of the crosslinking agent is preferably 0.01 to 10 parts by weight, more preferably 0.02 to 5 parts by weight, and even more preferably 0.025 to 0.5 parts by weight, relative to 100 parts by weight of the base polymer contained in the UV-curable pressure-sensitive adhesive. The flexibility of the pressure-sensitive adhesive layer can be controlled by the content of the crosslinking agent. If the content of the crosslinking agent is less than 0.01 parts by weight, the pressure-sensitive adhesive may become sol-like, making it impossible to form a pressure-sensitive adhesive layer. If the content of the crosslinking agent is more than 10 parts by weight, the semiconductor processing sheet may not be able to sufficiently embed the irregularities. Furthermore, peeling the protective layer from the pressure-sensitive adhesive layer may be difficult.

[0035] In one embodiment, an isocyanate-based crosslinking agent is preferably used. Isocyanate-based crosslinking agents are preferred because they can react with a variety of functional groups. Particularly preferably, a crosslinking agent having three or more isocyanate groups is used. By using an isocyanate-based crosslinking agent as the crosslinking agent and setting the content of the crosslinking agent within the above range, a pressure-sensitive adhesive layer can be formed that has excellent releasability and significantly less adhesive residue even after heating.

[0036] The thickness of the pressure-sensitive adhesive layer can be set to any appropriate value. The thickness of the pressure-sensitive adhesive layer is preferably 1 μm to 500 μm, more preferably 10 μm to 300 μm, and even more preferably 45 μm to 250 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, sufficient adhesion to the semiconductor wafer can be exerted.

[0037] The tensile storage modulus of the pressure-sensitive adhesive layer after ultraviolet irradiation was 1.0 × 10 ５ Pa ~ 1.0 x 10 ８ Pa, preferably 1.0×10 ６ Pa ~ 1.0 x 10 ８ Pa, and more preferably 1.0×10 ７ Pa ~ 1.0 x 10 ８ Pa. If the tensile storage modulus of the pressure-sensitive adhesive layer after UV irradiation is within the above range, the protective layer and the pressure-sensitive adhesive layer can be easily peeled off. If the tensile modulus of the pressure-sensitive adhesive layer after UV irradiation is too high, the pressure-sensitive adhesive layer may crack after UV irradiation. In this specification, the storage modulus of the pressure-sensitive adhesive layer after UV irradiation refers to a value measured by the following method. A pressure-sensitive adhesive layer is formed on a release liner using the pressure-sensitive adhesive that constitutes the pressure-sensitive adhesive layer so as to have a thickness of 0.6 mm to 0.7 mm. Next, the pressure-sensitive adhesive layer is irradiated with UV rays so as to achieve an integrated light dose of 1000 mJ. Thereafter, the storage modulus refers to a value measured using a dynamic viscoelasticity (DMA) measuring device (for example, TA Instruments Japan, product name "RSA-G2") under the following conditions: measurement mode: tension, gap: 20 mm, heating rate: 5°C / min, temperature range: -30°C to 150°C.

[0038] The contact angle of the pressure-sensitive adhesive layer with water after UV irradiation can be set to any appropriate value so that the difference with the contact angle of the protective layer with water exceeds 30°. The contact angle of the pressure-sensitive adhesive layer with water after UV irradiation is, for example, 85° or more, preferably 90° or more, and more preferably 95° or more. The larger the contact angle of the pressure-sensitive adhesive layer with water after UV irradiation, the more preferable it is, and the contact angle of the pressure-sensitive adhesive layer with water after UV irradiation is, for example, below the measurement limit (e.g., 115.2° or less). If the contact angle of the pressure-sensitive adhesive layer with water after UV irradiation is within the above range, the pressure-sensitive adhesive layer and the protective layer can be easily peeled off. In this specification, the contact angle of the pressure-sensitive adhesive layer with water after UV irradiation refers to a value measured in accordance with JIS R 3257 after using a laminate of a substrate and a pressure-sensitive adhesive layer and irradiating the pressure-sensitive adhesive layer with UV light to an integrated light amount of 1000 mJ.

[0039] D. Protective Layer The protective layer 30 is a layer containing a hydrophilic polymer. If the protective layer contains a hydrophilic polymer, the protective layer remaining on the semiconductor wafer can be easily removed from the surface of the semiconductor wafer after any appropriate processing step, for example, by contacting the protective layer with water. Furthermore, hydrophilic polymers usually have hydrophilic groups. If the hydrophilic polymer contained in the protective layer 30 has hydrophilic groups, adhesion to the semiconductor wafer surface, which is the adherend, can be improved.

[0040] The hydrophilic polymer may be any suitable polymer as long as it has hydrophilic properties. For example, a polymer having a hydrophilic group may be used. The hydrophilic group may be any suitable functional group. Specific examples include a hydroxy group, a carboxy group, a sulfonic acid group, a pyrrolidone group, and a polyoxyethylene group. If the hydrophilic polymer has the above-mentioned hydrophilic group (particularly a hydroxy group) in the molecule, the protective layer may adhere more sufficiently to the surface of the semiconductor wafer as the adherend. The hydrophilic polymer may contain only one type of hydrophilic group, or two or more types.

[0041] The hydrophilic polymer may be water-soluble. Specifically, the hydrophilic polymer may have such water solubility that a thin film (thickness of 50 μm or less) of the hydrophilic polymer is completely dissolved when immersed in water at 40° C. If the hydrophilic polymer is water-soluble, the protective layer 30 can be easily removed from the semiconductor wafer surface by, for example, contacting the protective layer with water.

[0042] Specific examples of hydrophilic polymers include polyvinyl alcohol (PVA) obtained by hydrolyzing a portion of the ester bond in a vinyl acetate polymer, polyvinylpyrrolidone (PVP), water-soluble polyester polymers (PES) having sulfonic acid groups or carboxyl groups in the molecule, and polyethylene oxide (PEO) copolymers. Water-soluble polyester polymers and polyethylene oxide copolymers are preferred. These hydrophilic polymers can be easily removed from the surface of the adherend by contacting them with water after the dicing process. Only one hydrophilic polymer may be used, or two or more may be used in combination.

[0043] The water-soluble polyester polymer is a copolymer obtained by a condensation reaction of, for example, a polycarboxylic acid component consisting of a polycarboxylic acid such as a dicarboxylic acid or its reactive derivative, a polyol component consisting of a polyol such as a diol or its ester derivative, and a water-soluble component, and has solubility in water.

[0044] The polycarboxylic acid may be any suitable polycarboxylic acid, including aromatic polycarboxylic acids and aliphatic polycarboxylic acids. Specific examples include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-biphenyletherdicarboxylic acid, 4,4'-biphenylmethanedicarboxylic acid, 4,4'-biphenylsulfonedicarboxylic acid, 4,4'-biphenylisopropylidenedicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, 2,5-anthracenedicarboxylic acid, 2,6-anthracenedicarboxylic acid, 4,4'-p-terphenylenedicarboxylic acid, and 2,5-pyridinedicarboxylic acid. Substituted versions of these compounds (e.g., alkyl group-substituted compounds such as 5-methylisophthalic acid) and reactive derivatives (e.g., alkyl ester derivatives such as dimethyl terephthalate and diethyl terephthalate) may also be used. The polycarboxylic acids may be used alone or in combination of two or more.

[0045] Any appropriate polyol can be used as the polyol component. Examples include aliphatic diols such as ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, and 2,2-dimethyl-1,3-propanediol; alicyclic diols such as 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, cyclohexanediol, and trans- or cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol; and aromatic diols such as p-xylenediol, bisphenol A, tetrabromobisphenol A, and tetrabromobisphenol A-bis(2-hydroxyethyl ether). Substituted versions of these polyols may also be used. The polyol component may be used alone or in combination of two or more.

[0046] As the polyol component, one or more long-chain diols having a molecular weight of 400 to 6000, such as polyethylene glycol, poly-1,3-propylene glycol, polytetramethylene glycol, etc. may be used in combination with the above polyol component.

[0047] The water-solubility-imparting component may be any appropriate component capable of imparting the hydrophilic group to the polyester polymer. Examples include dicarboxylic acids having a metal sulfonate group, polyethylene glycol, etc. Examples of dicarboxylic acids having a metal sulfonate group include alkali metal salts such as sodium and potassium of 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfonaphthalene-2,6-dicarboxylic acid, etc., or ester-forming derivatives thereof.

[0048] The weight-average molecular weight Mw of the water-soluble polyester polymer is preferably 5,000 or more, more preferably 7,000 or more, and even more preferably 10,000 or more. The weight-average molecular weight Mw of the water-soluble polyester polymer is preferably 40,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and particularly preferably 15,000 or less. When the weight-average molecular weight Mw of the water-soluble polyester polymer is within the above range, the protective layer can be easily formed into a film, and the protective layer can have better irregularity-burying properties. Furthermore, the protective layer can more effectively prevent fine foreign matter from adhering to the surface to be protected of the adherend. Furthermore, the protective layer can be more easily removed by a liquid containing water. In this specification, the weight-average molecular weight refers to the weight-average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC).

[0049] As the water-soluble polyester resin, commercially available products may be used, such as "Pluscoat Z-221," "Pluscoat Z-592," and "Pluscoat Z-730" manufactured by GOO Chemical Industry Co., Ltd.

[0050] Any appropriate copolymer can be used as the polyethylene oxide copolymer. For example, copolymers of polyethylene oxide with polypropylene oxide, polytrimethylene oxide, polybutylene oxide, polytetramethylene oxide, etc., such as copolymers of polyethylene oxide structural units (oxyethylene groups) and polypropylene oxide structural units (oxypropylene groups), can be mentioned. The copolymer may be a block copolymer, a random copolymer, or a graft copolymer. Preferably, a copolymer of ethylene oxide and propylene oxide is used. A copolymer of ethylene oxide and propylene oxide can further improve adhesion to the adherend, which is a semiconductor wafer.

[0051] The weight-average molecular weight Mw of the polyethylene oxide copolymer is preferably 200,000 or less. A weight-average molecular weight within the above range can have a sufficiently low softening point, improving the adhesion of the protective layer to the surface of the adherend to be protected. Furthermore, the protective layer can be removed more efficiently in a shorter time from the surface of the adherend to be protected using a liquid containing water. The weight-average molecular weight Mw may be, for example, 50,000 or more. In this specification, the weight-average molecular weight refers to the weight-average molecular weight measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0052] In one embodiment, the protective layer preferably uses a combination of a water-soluble polyester polymer and a polyethylene oxide copolymer, which can achieve both embedding of irregularities and adhesion to the surface of an adherend (e.g., a semiconductor wafer).

[0053] When a water-soluble polyester polymer and a polyethylene oxide copolymer are used in combination, their contents may be adjusted to any appropriate ratio. In this embodiment, the content of the water-soluble polyester polymer is preferably 50 wt% to 95 wt%, more preferably 60 wt% to 90 wt%, and even more preferably 70 wt% to 80 wt%, relative to 100 wt% of the total hydrophilic polymers used to form the protective layer. Furthermore, in this embodiment, the content of the polyethylene oxide copolymer is preferably 5 wt% to 50 wt%, more preferably 10 wt% to 40 wt%, and even more preferably 20 wt% to 30 wt%, relative to 100 wt% of the total hydrophilic polymers used to form the protective layer. When the content is within the above range, both the ability to embed irregularities and adhesion to the surface of the adherend (e.g., a semiconductor wafer) can be achieved.

[0054] The protective layer may contain any appropriate component other than the hydrophilic polymer. Examples include a solvent, a surfactant, and an ion generating agent (ion generating compound). The solvent may be water or an organic solvent. The organic solvent is preferably a relatively volatile organic solvent, such as ethanol or methanol.

[0055] Any appropriate compound can be used as the ion-generating compound. Examples include acid generators such as photoacid generators or thermal acid generators, and base generators such as photobase generators or thermal base generators. If the ion-generating compound is a photoacid generator, photobase generator, thermal acid generator, or thermal base generator, sufficient acid or base can be generated by heat treatment or irradiation with active energy rays such as ultraviolet light. As a result, the hydrophilicity of the protective layer can be further improved. As a result, the protective layer can be more easily removed from the surface to be protected by contact with water. Note that one compound may function as both a photoacid generator and a thermal acid generator.

[0056] The ion-generating compound is used in any appropriate amount. The amount of the ion-generating compound is preferably 1 part by weight or more, more preferably 3 parts by weight or more, per 100 parts by weight of the total hydrophilic polymer. The amount of the ion-generating compound is preferably 10 parts by weight or less, more preferably 8 parts by weight or less, per 100 parts by weight of the total hydrophilic polymer.

[0057] The thickness of the protective layer 30 can be set to any appropriate value. The thickness of the protective layer is, for example, 1 μm to 100 μm. The thickness of the protective layer is preferably 3 μm or more, and more preferably 5 μm or more. The thickness of the protective layer is preferably 40 μm or less. The protective layer 30 may be a single layer or a laminate of two or more layers. When the protective layer is a laminate, the above thickness refers to the total thickness of the laminate.

[0058] The contact angle of the protective layer 30 with water can be set to any appropriate value so that the difference with the contact angle of the pressure-sensitive adhesive layer with water after UV irradiation is more than 30° and less than 80°. The contact angle of the protective layer with water is, for example, 30° or more, preferably 35° or more, and more preferably 40° or more. The contact angle of the protective layer with water is, for example, 70° or less. If the contact angle of the protective layer with water is within the above range, the pressure-sensitive adhesive layer and the protective layer can be easily peeled off. In this specification, the contact angle of the protective layer with water refers to a value measured in accordance with JIS R 3257.

[0059] E. Method for Producing a Semiconductor Processing Sheet The semiconductor processing sheet 100 can be produced by any suitable method. For example, the semiconductor processing sheet 100 can be produced by applying an ultraviolet-curable adhesive that constitutes the adhesive layer 20 to the substrate 10 to form the adhesive layer 20, and then laminating the protective layer 30, which has been separately formed on any suitable release liner, to the adhesive 20. The adhesive layer 20 can also be produced by forming the adhesive layer 20 on any suitable release liner and then transferring the adhesive layer to the substrate 10.

[0060] F. Manufacturing of Semiconductor Chips Using a Semiconductor Processing Sheet The semiconductor processing sheet of an embodiment of the present invention is used in the manufacturing process of semiconductor chips. Semiconductor chip manufacturing typically involves thinning a semiconductor wafer (backgrinding process) and dicing the thinned semiconductor wafer into pieces of any suitable size (dicing process). As described above, the semiconductor processing sheet 100 of an embodiment of the present invention can be used in the same manner as backgrinding tape used in the semiconductor wafer processing process. Specifically, after the protective layer 30 of the semiconductor processing sheet 100 is attached to the circuit side of the semiconductor wafer, the side of the semiconductor wafer not covered with the semiconductor processing sheet 100 is ground and thinned. Next, the substrate 10 and adhesive layer 20 are peeled from the thinned semiconductor wafer. As described above, the semiconductor processing sheet of an embodiment of the present invention allows for easy peeling of the adhesive layer 20 and protective layer 30. Therefore, the protective layer 30 can be maintained in close contact with the circuit side of the semiconductor wafer. The semiconductor wafer with the protective layer 30 laminated on the circuit side is then subjected to the dicing process. During the dicing process, foreign matter such as debris may be generated when the semiconductor wafer is diced into small pieces. By using the semiconductor processing sheet according to the embodiment of the present invention, it is possible to prevent foreign matter from adhering to the circuit surface of the semiconductor wafer during the dicing process. Furthermore, since the protective layer 30 contains a hydrophilic polymer, it can be easily removed from the semiconductor wafer surface by contacting it with water. Below, an example of a method for manufacturing semiconductor chips using the semiconductor processing sheet according to the embodiment of the present invention is specifically described.

[0061] FIG. 2A is a schematic cross-sectional view of the process of laminating a semiconductor processing sheet and a semiconductor wafer according to an embodiment of the present invention. The semiconductor processing sheet 100 is laminated with an optional release liner (not shown) to protect the protective layer 30 until normal use. First, the release liner is peeled off from the semiconductor processing sheet 100, and the protective layer 30 is bonded to the surface (circuit surface) of the semiconductor wafer 200 to be protected. The bonding can be performed at any appropriate temperature. The protective layer 30 containing a hydrophilic polymer can have sufficient adhesion to the semiconductor wafer surface. Therefore, the semiconductor processing sheet 100 and the semiconductor wafer 200 are laminated in a state of sufficient adhesion via the protective layer 30. If necessary, the semiconductor processing sheet 100 and the semiconductor wafer 200 may be laminated together by applying pressure after they are laminated.

[0062] After the semiconductor processing sheet 100 and the semiconductor wafer 200 are stacked, the semiconductor wafer 200 is then subjected to a thinning process. Figure 2B is a schematic cross-sectional view showing the stacked state of the semiconductor processing sheet and the thinned semiconductor wafer according to an embodiment of the present invention. As shown in Figure 2A, after the semiconductor processing sheet 100 and the semiconductor wafer 200 are stacked, the surface of the semiconductor wafer 200 that is not in contact with the semiconductor processing sheet 100 is ground and thinned. By thinning, the semiconductor wafer 200 is ground to a predetermined thickness. Any appropriate grinding method can be used. For example, back grinding using a grinding wheel or etching processing may be used.

[0063] Next, a dicing tape 300 is attached to the ground surface of the thinned semiconductor wafer 200. FIG. 2C is a schematic cross-sectional view illustrating the process of fixing the thinned semiconductor wafer to the dicing tape. The dicing tape 300 is laminated on the ground surface of the thinned semiconductor wafer 200. By supporting and fixing the semiconductor wafer 200 to the dicing tape 300, chip flying can be suppressed in the subsequent dicing process. Although not shown, the semiconductor wafer 200 is typically supported and fixed to the dicing tape 300 via a ring frame. The dicing tape 300 typically has a substrate 50 and an adhesive layer 40. The semiconductor wafer 200 can be supported and fixed to the dicing tape 300 via the adhesive layer 40 of the dicing tape 300.

[0064] Next, the substrate 10 and adhesive layer 20 of the semiconductor processing sheet 100 are peeled off from the semiconductor wafer 200 fixed to the dicing tape 300. FIG. 2D is a schematic diagram illustrating the process of peeling off the substrate and adhesive layer of the semiconductor processing sheet of an embodiment of the present invention from the semiconductor wafer. As described above, the adhesive layer 20 is made of an ultraviolet-curable adhesive. Therefore, the adhesive strength can be reduced by irradiating the adhesive layer 20 with ultraviolet light. The tensile storage modulus of the adhesive layer after ultraviolet light irradiation is 1.0 × 10 ５ Pa ~ 1.0 x 10 ８ Pa. If the tensile storage modulus is within the above range, the adhesive layer 20 and the protective layer 30 can be easily peeled off. UV irradiation can be performed by any appropriate method. For example, as shown in FIG. 2D , the adhesive strength of the adhesive layer 20 can be reduced by irradiating the semiconductor processing sheet 100 with UV light from the substrate 10 side using any appropriate light source 400. The UV irradiation amount (integrated light amount) can be set to any appropriate value. After reducing the adhesive strength of the adhesive layer 20, the substrate 10 and the adhesive layer 20 can be peeled off from the protective layer 30 by any appropriate method. As described above, the protective layer 30 can have sufficient adhesion to the surface of the semiconductor wafer 200 and can maintain adhesion to the surface of the semiconductor wafer 200 even after the substrate 10 and the adhesive layer 20 are peeled off.

[0065] Next, the semiconductor wafer 200 is diced. Dividing can be performed by any appropriate method. In one embodiment, the protective layer 30 is cut along the intended cutting areas of the semiconductor wafer 200 before dicing. FIG. 2E is a schematic diagram illustrating the protective layer cutting process. In the illustrated example, a laser 501 is irradiated onto the protective layer 30 from a laser irradiation means 500. By irradiating the protective layer 30 with the laser along the intended cutting areas, grooves are formed in the protective layer 30 (laser grooving). FIG. 2F is a schematic diagram illustrating the state after irradiating the protective layer with a laser. Grooves 502 are formed in the laser-irradiated portions of the protective layer 30. The surface of the semiconductor wafer 200 can be exposed from the grooves 502. By exposing the surface of the semiconductor wafer 200, the exposed semiconductor wafer surface can be cut in the subsequent dicing process, making cutting easier. Furthermore, if the protective layer 30 is laminated on the surface of the semiconductor wafer 200, contamination of the semiconductor wafer surface due to debris melted by the laser can be suppressed, even when laser grooving is performed. Although laser grooving has been specifically described in the illustrated example, cutting with a blade (blade grooving) may also be used. The conditions for laser grooving and blade grooving may be set to any appropriate conditions depending on the type of protective layer, etc.

[0066] Next, the semiconductor wafer is diced into pieces of any suitable size. Figure 2G is a schematic diagram illustrating the semiconductor wafer dicing process. As described above, the surface of the semiconductor wafer 200 exposed from the grooves 502 is cut into pieces by any suitable cutting means. In the illustrated example, a method of dicing using a blade 600 is described, but dicing may also be performed by irradiating a laser.

[0067] In one embodiment, the semiconductor wafer 200 may be diced by etching it by irradiating plasma onto the surface of the semiconductor wafer 200 exposed from the grooves 502 from the side where the protective layer 30 is formed (hereinafter, also referred to as plasma dicing). Plasma dicing can be performed by any appropriate method, and can be performed using, for example, a plasma etching device. Specific conditions for plasma dicing include SF ６ A fluorine-based gas such as fluorine-containing gas may be introduced, and the etching rate may be set to a condition selected from the range of 0.5 μm / sec to 10 μm / sec.

[0068] Next, the protective layer 30 is removed from the surface of the semiconductor wafer 200. As described above, since the protective layer 30 contains a hydrophilic polymer, it can be easily removed from the surface of the semiconductor wafer 200 by contacting it with water. Any appropriate method can be used for contacting with water. FIG. 2H is a schematic diagram showing an example of the protective layer removal step. In the illustrated example, water 700 is sprayed onto the protective layer 30 from above to remove the protective layer 30. Any appropriate method can be used for contacting the protective layer with water. For example, as shown in the illustrated example, a method of spraying water onto the collection of diced semiconductor wafers, a method of applying water to the collection of diced semiconductor wafers, or a method of immersing the collection of diced semiconductor wafers in water can be used. After the protective layer 30 is removed, the water is removed from the wafer surface by any appropriate method, such as drying.

[0069] The diced semiconductor wafers (semiconductor chips) are then recovered (picked up) by any appropriate method. Fig. 2I is a schematic diagram of the recovery process for diced semiconductor wafers. The diced semiconductor wafers 201 are pushed up from the dicing tape 300 side by pins 900, and are then sucked and recovered from the semiconductor wafer 200 side by a collet 800.

[0070] The above specifically describes a method for manufacturing semiconductor chips including grooving, but the semiconductor processing sheet of an embodiment of the present invention is not limited to this manufacturing method and can be used in any appropriate manufacturing method.

[0071] In another embodiment, semiconductor chips can be fabricated by the following method. FIG. 3A is a schematic diagram illustrating a process of forming grooves in a semiconductor wafer for dividing the semiconductor wafer. First, any appropriate adhesive tape 1000 for semiconductor wafer processing is attached to the surface of the semiconductor wafer 200 opposite the surface to be protected (circuit surface). Next, grooves for dividing the semiconductor wafer 200 into small pieces are formed on the surface of the semiconductor wafer 200 to which the adhesive tape 1000 for semiconductor wafer processing is not attached. The grooves can be formed by any appropriate method. For example, the grooves can be formed using a blade. The grooves can be formed in the thickness direction of the semiconductor wafer 200 and can be formed so as not to penetrate the semiconductor wafer 200.

[0072] 3B is a schematic diagram illustrating the process of laminating the semiconductor wafer processing sheet 100 of an embodiment of the present invention onto the semiconductor wafer 200 having grooves formed thereon in FIG. The semiconductor wafer processing sheet 100 is then bonded to the grooved surface (circuit surface) of the semiconductor wafer 200 having grooves formed thereon. The semiconductor wafer processing sheet 100 is bonded so that the protective layer 30 contacts the grooved surface of the semiconductor wafer 200. The semiconductor wafer processing adhesive tape 1000 can be peeled off from the semiconductor wafer 200 after the semiconductor wafer processing sheet 100 has been laminated on the semiconductor wafer 200.

[0073] 3C is a schematic diagram illustrating the state of the semiconductor wafer of FIG. 3B after being thinned. The semiconductor wafer 200 bonded to the semiconductor wafer processing sheet 100 is thinned by grinding the surface on which the semiconductor wafer processing sheet 100 is not laminated (back-grinding process). The thinning method is as described above. In the back-grinding process, the semiconductor wafer 200 is ground to a predetermined thickness and thinned.

[0074] 3D is a schematic diagram illustrating the process of bonding the thinned semiconductor wafer to a dicing tape. The thinned semiconductor wafer 200 is then bonded to a dicing tape 300. In this embodiment, the surface of the thinned semiconductor wafer 200 ground in the back-grinding process is bonded to a die bond sheet 310 on the dicing tape 300 (mounting process).

[0075] 3E is a schematic diagram illustrating the process of peeling the substrate and adhesive layer of the semiconductor processing sheet according to an embodiment of the present invention from the semiconductor wafer. After the thinned semiconductor wafer 200 and the dicing tape 300 are bonded together, the substrate 10 and adhesive layer 20 of the semiconductor wafer processing sheet 100 are peeled from the semiconductor wafer 200. As described above, the adhesive layer 20 is made of an ultraviolet-curable adhesive. Therefore, the adhesive strength can be reduced by irradiating the adhesive layer 20 with ultraviolet light. The tensile storage modulus of the adhesive layer after ultraviolet light irradiation is 1.0 × 10 ５ Pa ~ 1.0 x 10 ８ Pa. If the tensile storage modulus is within the above range, the adhesive layer 20 and the protective layer 30 can be easily peeled off. UV irradiation can be performed by any appropriate method. For example, as shown in FIG. 3E, the adhesive strength of the adhesive layer 20 can be reduced by irradiating the semiconductor processing sheet 100 with UV light from the substrate 10 side using any appropriate light source 400. The UV irradiation amount (integrated light amount) can be set to any appropriate value. After reducing the adhesive strength of the adhesive layer 20, the substrate 10 and the adhesive layer 20 can be peeled off from the protective layer 30 by any appropriate method. As described above, the protective layer 30 can have sufficient adhesion to the surface of the semiconductor wafer 200 and can maintain adhesion to the surface of the semiconductor wafer 200 even after the substrate 10 and the adhesive layer 20 are peeled off.

[0076] Next, the laminate of the protective layer 30, the semiconductor wafer 200, and the dicing tape 300 is subjected to an expanding process. FIG. 3F is a schematic diagram illustrating a semiconductor wafer subjected to the expanding process. As shown in the figure, with the semiconductor wafer 200 attached to the die bond sheet 310 on the dicing tape 300, the dicing tape 300 is stretched in the planar direction so as to increase the surface area of ​​the dicing tape 300. As a result, the laminate of the semiconductor wafer 200 and the protective layer 30 is divided into small pieces along the grooves formed in the above process, and the spacing between adjacent semiconductor chips formed by the small pieces is widened in the planar direction. Specifically, a push-up member 1100 provided in the expanding device is pushed up from below the dicing tape 300, stretching the dicing tape 300 so that it expands in the planar direction. As a result, the laminate of the semiconductor wafer 200 and the protective layer 30 is diced under specific temperature conditions. The temperature conditions may be set to any appropriate conditions. For example, the low-temperature expanding process can be performed at a temperature between -20°C and 0°C. The expanded state is released by lowering the push-up member 1100 (this is the low-temperature expanding process). When performing the low-temperature expanding process, the protective layer 30 needs to be broken into small pieces. The protective layer 30 can be broken well in the low-temperature expanding process.

[0077] Furthermore, in the expanding step, the dicing tape 300 may be stretched again under higher temperature conditions (for example, 10° C. or higher and 25° C. or lower) so as to increase the surface area of ​​the dicing tape 300. This allows adjacent diced semiconductor chips to be separated in the surface direction of the dicing tape 300, further increasing the kerf (gap) (room temperature expanding step).

[0078] As described above, in the expanding process, semiconductor chips are produced by dicing the semiconductor wafer 200 in a state in which the semiconductor wafer 200 and the protective layer 30 are stacked together. During dicing, foreign matter such as fragments may be generated as the semiconductor wafer 200 is cleaved, but the protective layer 30 protects the circuit surface of the semiconductor chip, making it possible to prevent foreign matter from adhering to the circuit surface.

[0079] Next, the protective layer 30 is removed from the surface of the semiconductor wafer 200. As described above, since the protective layer 30 contains a hydrophilic polymer, it can be easily removed from the surface of the semiconductor wafer 200 by contacting it with water. Any appropriate method can be used for contacting with water. FIG. 3G is a schematic diagram showing an example of the protective layer removal process. In the illustrated example, water 700 is sprayed onto the protective layer 30 from above to remove the protective layer 30. Any appropriate method can be used for contacting the protective layer with water. For example, as shown in the illustrated example, a method of spraying water onto the collection of diced semiconductor wafers, a method of applying water to the collection of diced semiconductor wafers, or a method of immersing the collection of diced semiconductor wafers in water can be used. After the protective layer 30 is removed, the water is removed from the wafer surface by any appropriate method, such as drying.

[0080] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Test and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" are by weight.

[0081] Example 1 1. Preparation of a Laminate of a Pressure-Sensitive Adhesive Layer and a Substrate Monomers were placed in a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer at the molar ratios shown in Table 1. 0.2 parts by weight of azobisisobutyronitrile (AIBN) was used as a thermal polymerization initiator relative to 100 parts by weight of the total monomers. Ethyl acetate was then added, and the concentration of the monomer component was adjusted to a predetermined concentration (e.g., 36% by mass). The mixture was reacted in a nitrogen stream under the conditions shown in Table 1, and then aged under the conditions shown in Table 1 to obtain a solution containing an acrylic copolymer intermediate. 2-Methacryloyloxyethyl isocyanate (hereinafter also referred to as MOI) was added to the resulting solution at the molar ratio shown in Table 1. Furthermore, 0.07% by weight of dibutyltin dilaurate was added as a reaction catalyst relative to 100 parts by weight of the acrylic copolymer. An addition reaction (urethanization reaction) was then carried out under the conditions shown in Table 1 to obtain an acrylic copolymer (base polymer). Next, 5 parts by weight of a photopolymerization initiator (manufactured by IGM, product name "Omnirad 127") and the amount of crosslinker (polyisocyanate compound manufactured by Mitsui Chemicals, Inc., product name "Takenate D-101A") listed in Table 1 were added to 100 parts by weight (solid content) of the acrylic copolymer and mixed to obtain a pressure-sensitive adhesive composition. The obtained pressure-sensitive adhesive layer composition was applied to a release sheet and dried by heating at 120°C for 2 minutes to form a pressure-sensitive adhesive layer with a thickness of 30 μm. Thereafter, the primer-treated surface of a substrate (PET film, 100 μm thick, manufactured by Toray Industries, Inc., product name "Lumirror (registered trademark)") was bonded at room temperature using a laminator to the side of the pressure-sensitive adhesive layer prepared on the release sheet that was not in contact with the release sheet. The mixture was then left to stand at 50°C for 24 hours to obtain a laminate of the substrate and pressure-sensitive adhesive layer.

[0082] 2. Preparation of Protective Layer A water-soluble polyester resin (manufactured by GOO Chemical Industry Co., Ltd., product name "PLASCOAT Z-221") and a polyethylene oxide copolymer (manufactured by MEISEI Chemical Industry Co., Ltd., product name "ALKOX EP1010N") were added in the weight ratios shown in Table 1, and the mixture was heated to 60°C to prepare an aqueous solution with a total concentration of 20% by weight. The obtained aqueous solution was applied using an applicator to the release-treated surface of a release liner a (PET film, thickness 50 μm) that had been subjected to a silicone release treatment so that the thickness after drying was 2 μm, forming a protective layer. The resulting solution was then dried at 130°C for 2 minutes. Thereafter, a release liner b (PET film, thickness 25 μm) that had been subjected to a silicone release treatment was bonded to the side of the protective layer to which release liner a was not bonded, to prepare a protective sheet comprising a protective layer sandwiched between two release liners.

[0083] 3. Preparation of semiconductor processing sheet Release liner b was peeled from the obtained protective sheet, and the surface of the protective sheet from which release liner b had been peeled was laminated to the pressure-sensitive adhesive layer of a laminate of a substrate and a pressure-sensitive adhesive layer, and the laminate of the substrate and the pressure-sensitive adhesive layer and the protective layer were bonded together using a laminating roll under conditions of 40°C and a bonding speed of 10 mm / sec.

[0084]

[0085] Examples 2 to 8 Semiconductor processing sheets were obtained in the same manner as in Example 1, except that the composition of the adhesive composition and the composition of the protective layer were changed as shown in Table 1.

[0086] Comparative Examples 1 to 5 Semiconductor processing sheets were obtained in the same manner as in the Examples, except that the adhesive composition and the protective layer composition were changed as shown in Table 1.

[0087] The following evaluations were performed using the semiconductor processing sheets obtained in the Examples and Comparative Examples. The results are shown in Table 2. (1) Contact Angle Release liner b was peeled off from the protective sheet used to prepare the semiconductor processing sheets of the Examples and Comparative Examples. Next, the contact angle with water of the surface from which the release liner was peeled off (protective layer) was measured at 25°C using a fully automatic contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., product name "DM-500") in accordance with JIS R3257, with 1 μL of water. The measurement was performed five times, and the average value of the five measurements was used. Separately, the adhesive layer of the laminate of the substrate and adhesive layer used to prepare the semiconductor processing sheets of the Examples and Comparative Examples was irradiated with ultraviolet light using a high-pressure mercury lamp (manufactured by Nitto Seiki Co., Ltd., product name "UM-810") so that the accumulated light intensity was 1000 mJ. Next, the contact angle of the pressure-sensitive adhesive layer after ultraviolet irradiation with 1 μL of water was measured at 25° C. using a fully automatic contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., product name "DM-500") in accordance with JIS R3257. The measurement was performed five times, and the average value of the five measured values ​​was used.

[0088] (2) Tensile Storage Modulus The pressure-sensitive adhesive used in the Examples and Comparative Examples was applied to a release liner to a thickness of 0.6 mm to 0.7 mm to form a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer was then irradiated with ultraviolet light to an integrated light dose of 1000 mJ. Measurements were then performed using a dynamic mechanical analysis (DMA) measuring device (manufactured by TA Instruments Japan, product name "RSA-G2") under the following conditions: measurement mode: tension, gap: 20 mm, heating rate: 5°C / min, temperature range: -30°C to 150°C.

[0089] (3) Shear storage modulus before UV irradiation Each pressure-sensitive adhesive layer-forming composition was laminated to a thickness of 1 mm on a release liner (thickness 38 μm, manufactured by Mitsubishi Plastics, Inc., product name: MRF) to prepare a sample. This sample was measured using an ARES rheometer (manufactured by Waters) under conditions of a heating rate of 5°C / min, a frequency of 1 Hz, and a measurement temperature of 0°C to 100°C.

[0090] (4) T-Peel Test The peel force was measured using a T-peel test. Measurement samples were prepared as follows. The PET release liner (release liner a) was peeled from the semiconductor processing sheets obtained in the Examples and Comparative Examples to expose the water-soluble protective film surface. A backing tape (manufactured by Nitto Denko Corporation, product name "ELP BT315") was attached to the exposed surface. Next, a high-pressure mercury lamp (manufactured by Nitto Seiki Co., Ltd., product name "UM-810") was used to irradiate ultraviolet light from the base layer side with an integrated light intensity of 1000 mJ to cure the adhesive layer. Thereafter, a sample of the adhesive layer measuring 50 mm wide x 120 mm long was cut out to prepare a measurement sample. A T-peel test was performed on the prepared measurement sample using a tensile tester (manufactured by Shimadzu Corporation, product name "AUTOGRAPH AGX-V"). The test conditions were a temperature of 25°C and a tensile speed of 300 mm / min.

[0091] (5) Embedding Test The semiconductor processing sheets (230 cm x 400 cm) obtained in the examples and comparative examples were attached to wafers (8 inches, bump height 15 μm, diameter 10 μm, pitch 100 μm) using a tape attachment device (manufactured by Nitto Seiki Co., Ltd., product name: DR-3000III). Attachment was performed under the following conditions: Environment: 23°C, relative humidity 50% Roller pressure: 0.40 MPa Roller speed: 3 mm / sec Table temperature: 70°C After attachment, the attachment state of the semiconductor processing sheet and wafer was observed using a laser microscope (magnification: 100x). An evaluation was made for five randomly selected bumps, with those with no air around three or more bumps (those with a distance between bubbles of 5 μm or more) being rated as ◯ (good), those with some air (those with a distance between bubbles of more than 0 and less than 5 μm) being △ (fair), and those with a lot of air (those with bubbles connected between bumps) being × (room for improvement). The results were judged by observing five randomly selected bumps.

[0092]

[0093] The semiconductor processing sheet of the present invention can be suitably used in semiconductor processing steps.

[0094] 10: Substrate 20: Pressure-sensitive adhesive layer 30: Protective layer 100: Semiconductor processing sheet

Claims

1. A substrate, a pressure-sensitive adhesive layer made of an ultraviolet-curable pressure-sensitive adhesive, and a protective layer containing a hydrophilic polymer, in this order, wherein the tensile storage modulus of the pressure-sensitive adhesive layer after ultraviolet irradiation is 1.0 × 10 ５ Pa ~ 1.0 x 10 ８ A semiconductor processing sheet.

2. The semiconductor processing sheet according to claim 1, wherein the difference between the contact angle with water of the adhesive layer and the contact angle with water of the protective layer after ultraviolet irradiation exceeds 30°.

3. The semiconductor processing sheet according to claim 1, wherein the ultraviolet-curable adhesive contains a polymer into which a polymerizable carbon-carbon double bond has been introduced.

4. The semiconductor processing sheet according to claim 1, wherein the T-peel strength between the adhesive layer and the protective layer after ultraviolet irradiation is 0.5 N / 50 mm or less.

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