Semiconductor wafer surface protection tape

Abstract

To provide a semiconductor wafer surface protection tape that exhibits excellent conformability to unevenness on a semiconductor wafer having high bumps, and can effectively suppress both the occurrence of warpage and blade contamination.SOLUTION: A semiconductor wafer surface protection tape (1) includes a base layer 2, a resin layer A (3), a resin layer B (4), and an adhesive layer 5, in this order, and the storage modulus of the resin layer A at 23°C is 1.0×103 to 1.0×105 Pa, and the thickness of the resin layer A is 3 to 55 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tape for protecting the surface of a semiconductor wafer. [Background technology]

[0002] 2. Description of the Related Art In the processing of electronic components such as semiconductor wafers, tapes having an adhesive layer on the adhesive surface that adheres to the electronic components are used for surface protection. For example, in the processing of semiconductor wafers, after a pattern is formed on the surface of the semiconductor wafer, the backside of the semiconductor wafer is ground and polished to a predetermined thickness (so-called backside grinding and polishing). At this time, in order to protect the surface of the semiconductor wafer, a semiconductor wafer surface protection tape is attached to the surface of the semiconductor wafer, and the backside of the semiconductor wafer is ground in this state.

[0003] In recent years, with the trend toward thinner packaging and smaller chip mounting areas, a mounting method known as flip-chip mounting has come into use. Flip-chip mounting electrically connects the chip surface to the substrate without using wires, using ball-shaped or cylindrical bumps formed on the surface of the semiconductor wafer. Depending on the bump formation method, these bumps can have a bump height (unevenness of the semiconductor wafer surface) of over 100 μm. Semiconductor wafer surface protection tapes that are bonded to semiconductor wafers with such large surface unevenness require high conformability to uneven surfaces.

[0004] In order to achieve conformability to the irregularities of a semiconductor wafer with bumps having a height exceeding 100 μm (hereinafter referred to as "high bumps"), for example, Patent Document 1 describes a tape for electronic components that includes, in this order, a base film, a resin layer, and an adhesive layer, and describes that by setting the storage modulus of the resin layer to 200,000 Pa or less at any temperature between 60°C and 80°C, the tape for electronic components can sufficiently conform to the irregularities of the semiconductor wafer surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-174063 Summary of the Invention [Problem to be solved by the invention]

[0006] Typically, wafers with circuit patterns formed on them are thinned to a thickness of around 200 to 350 μm in the backgrinding process. Because of their thinness, thin wafers after backgrinding are prone to curvature (hereafter referred to as warpage). This warpage can cause the thin wafer to fall during transport or to come into contact with the tray when being placed in the tray, resulting in damage. Therefore, thin wafers after backgrinding are required to have warpage below the standard (usually 5 to 10 mm or less). Furthermore, the warpage of the thin-film wafer can also be caused by the semiconductor wafer surface protection tape applied to the circuit pattern surface of the semiconductor wafer during backgrinding. For example, when applying a semiconductor wafer surface protection tape to the circuit pattern surface of a semiconductor wafer with high bumps, the semiconductor wafer surface protection tape is typically heated to approximately 40 to 70°C. This heating softens the resin layer (intermediate resin layer) located in the middle of the tape's laminated structure, allowing the tape to adequately conform to the gaps between the bumps. However, the tape expands during the heat lamination process and then shrinks when the temperature drops to room temperature (approximately 25°C) after lamination, subjecting the thin-film wafer to various internal stresses. Furthermore, applying tension to the semiconductor wafer surface protection tape during the heat lamination process to prevent it from warping also contributes to increasing the internal stress in the thin-film wafer. These internal stresses caused by the application of the semiconductor wafer surface protection tape tend to exacerbate warpage. According to the inventors' investigations, it has been found that in tapes such as those described in Patent Document 1, in which the resin layer disposed between the base film and the pressure-sensitive adhesive layer has a storage modulus of 200,000 Pa or less at any temperature between 60°C and 80°C in order to achieve sufficient conformability to the irregularities, the tape exhibits good conformability to the irregularities of semiconductor wafers having high bumps, but can cause significant warpage of about 10 mm.Further investigations have also revealed that incorporating a resin layer for alleviating internal stress in part of the laminated structure of the tape in order to suppress warpage creates a new problem of blade contamination during circle cutting of semiconductor wafers to which the semiconductor wafer surface protection tape has been applied. Therefore, an object of the present invention is to solve the above problems and to provide a tape for protecting the surface of a semiconductor wafer that exhibits excellent conformability to the irregularities of a semiconductor wafer having high bumps and can effectively suppress both the occurrence of warpage and blade contamination. [Means for solving the problem]

[0007] The above-mentioned problems of the present invention have been solved by the following means. <1> The film includes a base layer, a resin layer A, a resin layer B, and a pressure-sensitive adhesive layer in this order, The storage modulus of the resin layer A at 23°C is 1.0 × 10 3 ~1.0×10 5 1. A surface-protecting tape for semiconductor wafers, comprising: a resin layer A having a thickness of 3 to 55 μm; <2> The melting point of the base material layer is 80°C or higher. <1> 10. The tape for protecting a semiconductor wafer surface according to claim 9. <3> The thickness of the resin layer B is 200 μm or more, and the storage modulus of the resin layer B at 70° C. is 3.0×10 6 Pa or less, <1> or <2> 10. The tape for protecting a semiconductor wafer surface according to claim 9. <4> The resin layer A is a layer containing an acrylic adhesive or a polyester adhesive. <1> ~ <3> 10. The tape for protecting a semiconductor wafer surface according to claim 9. <5> The resin layer A contains an antistatic agent, and the antistatic agent is an ionic liquid. <1> ~ <4> 10. The tape for protecting a semiconductor wafer surface according to claim 9. [Effects of the Invention]

[0008] The semiconductor wafer surface protecting tape of the present invention exhibits excellent conformability to irregularities on semiconductor wafers having high bumps, and can effectively suppress both the occurrence of warpage and blade contamination. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one embodiment of the tape for protecting a semiconductor wafer surface of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the present invention, the front surface of a semiconductor wafer refers to the surface of the semiconductor wafer having irregularities, i.e., the surface on which an integrated circuit (circuit pattern) is formed. The surface opposite to the front surface is referred to as the back surface. In the present invention, the unevenness difference refers to the distance from the highest part of a convex part to the wafer surface or the distance from the deepest part of a concave part to the semiconductor wafer surface. For example, when metal electrodes (bumps) are formed on a semiconductor wafer, the highest part is the top of the highest bump, and the distance from there to the semiconductor wafer surface, i.e., the height of the bump, is the unevenness difference. Alternatively, when scribe lines (dicing lines) are formed on a semiconductor wafer, the deepest part is the deepest position of the scribe lines, and the distance from there to the semiconductor wafer surface is the unevenness difference. In the present invention, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In the present invention, the term "(meth)acrylic" is used to mean either or both of "acrylic" and "methacrylic".

[0011] [Semiconductor wafer surface protection tape] The surface protection tape for semiconductor wafers of the present invention comprises a base layer, a resin layer A, a resin layer B, and a pressure-sensitive adhesive layer in this order, and the storage modulus of the resin layer A at 23° C. is 1.0×10 3 ~1.0×10 5 Pa, and the thickness of the resin layer A is 3 to 55 μm. The semiconductor wafer surface protection tape of the present invention has a laminated structure of a base layer, a resin layer B, and a pressure-sensitive adhesive layer, and by providing a resin layer A having a storage modulus at 23°C and a thickness within the above-mentioned specific ranges between the base layer and the resin layer B, it is possible to achieve excellent conformability to the irregularities of semiconductor wafers having high bumps, and also to effectively suppress both the occurrence of warpage and blade contamination. A preferred embodiment of the semiconductor wafer surface protecting tape of the present invention will be described below.

[0012] As shown in Fig. 1, the semiconductor wafer surface protection tape (1) of the present invention is an integrated tape in which a resin layer A (3), a resin layer B (4), and a pressure-sensitive adhesive layer (5) are laminated in this order on a base layer (2). The semiconductor wafer surface protection tape (1) may further include a release film (not shown in Fig. 1) on the pressure-sensitive adhesive layer (5) to protect the pressure-sensitive adhesive layer (5). The semiconductor wafer surface protection tape (1) of the present invention may also be in the form of a roll of a laminate of the base layer (2), the resin layer A (3), the resin layer B (4), the pressure-sensitive adhesive layer (5), and the release film.

[0013] (base material layer) The resin (in the present invention, the term "resin" includes elastomers) constituting the substrate layer (2) used in the semiconductor wafer surface protection tape (1) of the present invention is not particularly limited, and plastics, rubbers, etc. that are commonly used as materials constituting substrate films in the technical field to which the present invention pertains can be used. Note that the substrate layer (2) differs from the resin layer A (3) described below in that it has a storage modulus at 23°C of 1.0 x 10 3 ~1.0×10 5 It is outside the range of Pa. Examples of resins that can be used to form the base layer (2) include polyolefin resins made of homopolymers or copolymers of monomers containing ethylenically unsaturated groups, such as polyethylenes such as low-density polyethylene, polypropylene, ethylene-propylene copolymers, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl acrylate copolymers, ethylene-acrylic acid copolymers, and ionomers; engineering plastics such as polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate resins, polyurethane resins, and polymethyl methacrylate resins; synthetic rubbers such as styrene-ethylene-butene or pentene copolymers; and thermoplastic elastomers such as polyamide-polyol copolymers. The resin constituting the substrate layer (2) may be one of the above resins or a combination of two or more of them. The substrate layer (2) may be a single layer or multiple layers. In addition to the resin, the substrate layer (2) may contain additives such as colorants and antioxidants as needed, provided that the additives do not affect the physical properties. The resin constituting the substrate layer (2) is preferably a polyolefin resin or a polyester resin.

[0014] The melting point of the substrate layer (2) is usually 80°C or higher, preferably 80 to 280°C, more preferably 100 to 280°C, even more preferably 170 to 280°C, particularly preferably 230 to 270°C, and most preferably 250 to 270°C. When the melting point of the base material layer (2) is 80°C or higher, the base material layer (2) can be prevented from melting and fusing to equipment, etc., depending on the temperature environment when the semiconductor wafer surface protection tape (1) of the present invention is applied to electronic components, when the electronic components are processed in a laminated state, etc. For example, when the semiconductor wafer surface protection tape is heated to about 40 to 70°C and laminated to the circuit pattern surface of a semiconductor wafer having a high level difference, fusing to the lamination roller or chuck table can be prevented. Furthermore, if the melting point of the base layer (2) is 170° C. or higher, warping can be further prevented. In addition, when the substrate layer (2) is a multi-layered structure, the above-mentioned "melting point of the substrate layer" means the melting point of the layer that constitutes the outermost layer on the opposite side of the primer layer (3) among the layers that constitute the substrate layer. The melting point is a value measured by a DSC (differential scanning calorimeter) method at a heating rate of 10°C / min based on JIS (Japanese Industrial Standards) K 7121 (1987) Method for Measuring Transition Temperature of Plastics.

[0015] The thickness of the substrate layer (2) is not particularly limited, but is preferably, for example, 30 to 150 μm, more preferably 40 to 120 μm, and even more preferably 50 to 100 μm. When the base layer (2) is a multi-layered structure, the "thickness of the base layer (2)" means the total thickness of all layers constituting the base layer (2).

[0016] The surface of the base layer (2) on which the resin layer A (3) is provided may be appropriately subjected to treatment such as corona treatment or provision of a primer layer in order to improve adhesion to the resin layer A (3).

[0017] (Resin layer A) The resin layer A (3) used in the semiconductor wafer surface protection tape (1) of the present invention has a storage modulus of 1.0 × 10 at 23°C. 3 ~1.0×10 5There are no particular limitations as long as the storage modulus at 23°C and the thickness are within the above-mentioned specific ranges for the resin layer A (3), so that the semiconductor wafer surface protection tape (1) of the present invention can achieve both anti-warping performance and suppression of blade contamination. The resin layer A(3) can be, for example, a layer containing an acrylic adhesive or a polyester adhesive, and is preferred. The acrylic pressure-sensitive adhesive has the same definition as the acrylic pressure-sensitive adhesive in the pressure-sensitive adhesive layer described below.

[0018] Examples of the (meth)acrylic acid ester copolymer that constitutes the acrylic pressure-sensitive adhesive include a (meth)acrylic acid ester copolymer that is composed of structural units derived from at least two of a (meth)acrylic acid ester monomer, a (meth)acrylic acid ester monomer substituted with a functional group such as a hydroxy group, and (meth)acrylic acid. Examples of the (meth)acrylic acid ester monomer include (meth)acrylic acid cycloalkyl ester, (meth)acrylic acid benzyl ester, and (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 18 carbon atoms (preferably 1 to 12, more preferably 1 to 8, and even more preferably 1 to 4). Furthermore, examples of the (meth)acrylic acid ester monomer substituted with a functional group such as a hydroxy group include (meth)acrylic acid ester monomers in which a cycloalkyl group, a benzyl group, or an alkyl group constituting the ester in the above-mentioned (meth)acrylic acid ester is substituted with a hydroxy group, and hydroxyalkyl (meth)acrylates are preferred, such as 2-hydroxyethyl (meth)acrylate.

[0019] The acrylic adhesive used in the resin layer A(3) preferably contains a crosslinking agent selected from polyisocyanate compounds, polyepoxy compounds, polyaziridine compounds, chelate compounds, etc., and more preferably a polyisocyanate compound. The polyvalent isocyanate compound is not particularly limited, and examples thereof include aromatic isocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylether diisocyanate, 4,4'-[2,2-bis(4-phenoxyphenyl)propane]diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate, lysine triisocyanate, etc. Commercially available crosslinking agents can also be used, such as Coronate L (manufactured by Tosoh Corporation). Examples of polyepoxy compounds include epoxy resins, such as ethylene glycol diglycidyl ether, terephthalic acid diglycidyl ester acrylate, and anilines in which two glycidyl groups are substituted on the N atom. TETRAD-X (trade name, manufactured by Mitsubishi Chemical Corporation) can also be used. An example of the anilines is N,N'-tetraglycidyl-m-phenylenediamine. Examples of polyvalent aziridine compounds include tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, tris[1-(2-methyl)-aziridinyl]phosphine oxide, hexa[1-(2-methyl)-aziridinyl]triphosphatriazine, etc. Examples of chelate compounds include ethyl acetoacetate aluminum diisopropylate, aluminum tris(ethyl acetoacetate), etc.

[0020] The amount of the crosslinking agent added is preferably 0.2 to 1.4 parts by mass, more preferably 0.20 to 1.2 parts by mass, still more preferably 0.25 to 1.0 part by mass, and particularly preferably 0.25 to 0.8 parts by mass, per 100 parts by mass of the (meth)acrylic acid ester copolymer.

[0021] The polyester adhesive may be a copolymer made of a copolymerization component containing a polycarboxylic acid and a polyol. Examples of the polycarboxylic acid include dicarboxylic acids and trivalent or higher polycarboxylic acids. Examples of the polyol component include dihydric alcohols and trivalent or higher polyhydric alcohols. Commercially available polyester adhesives may be used, such as Nichigo Polyester LP (trade name) manufactured by Mitsubishi Chemical Corporation.

[0022] The adhesive contained in the resin layer A(3) may be one of the above adhesives or a combination of two or more of them. The resin layer A(3) may be a single layer or multiple layers. In addition to the adhesive, the resin layer A(3) may contain additives such as colorants and antioxidants as needed, provided that the additives do not affect the physical properties.

[0023] The storage modulus of the resin layer A(3) at 23°C is 1.0 × 10 3 ~1.0×10 5 Pa, 8.0 x 10 3 ~1.0×10 5 From the viewpoint of further preventing warpage, it is more preferable that the thickness is 2.0×10 4 ~8.0×10 4 Pa is more preferred. When the resin layer A(3) is a multi-layered layer, the "storage modulus at 23°C" means the storage modulus at 23°C measured for the entire resin layer A(3) which is a multi-layered layer. The storage modulus of the resin layer A(3) at 23° C. is a value measured using a dynamic viscoelasticity measuring device under the conditions described in the Examples. The storage modulus can be adjusted to a desired value by adjusting the amount of curing agent in the resin layer A(3), the molecular weight of the polymer, the content of comonomer, the glass transition point of the polymer, the addition of additives such as plasticizers, etc.

[0024] The thickness of the resin layer A(3) is 3 to 55 μm, preferably 5 to 55 μm, more preferably 10 to 50 μm, and from the viewpoint of further preventing warping, further preferably 15 to 50 μm, particularly preferably 20 to 50 μm. When the resin layer A(3) is a multi-layered layer, the "thickness of the resin layer A(3)" means the total thickness of all layers constituting the resin layer A(3).

[0025] From the viewpoint of imparting excellent antistatic properties to the semiconductor wafer surface protection tape (1) of the present invention, it is preferable that the resin layer A (3) contains an antistatic agent. The antistatic agent contained in the resin layer A (3) is not particularly limited, and any antistatic agent commonly used in semiconductor wafer surface protection tapes can be used, as long as the semiconductor wafer surface protection tape (1) of the present invention can exhibit antistatic performance. In particular, when the antistatic agent is an ionic liquid, it is possible to exhibit excellent antistatic performance on both the substrate layer (2) and the pressure-sensitive adhesive layer (5) of the semiconductor wafer surface protection tape (1) of the present invention, which is preferable. In the present invention, the term "ionic liquid" refers to a compound that is a salt composed of an anion and a cation and has a melting point of 30 to 80°C. The ionic liquid may be a quaternary ammonium salt type ionic liquid containing an acryloyl group.

[0026] Examples of the cations constituting the ionic liquid include nitrogen-containing onium cations such as pyridinium cation, imidazolium cation, pyrimidinium cation, pyrazolium cation, pyrrolidinium cation, and ammonium cation; phosphonium cation, and sulfonium cation. Examples of the anions constituting the ionic liquid include hexafluorophosphate ion (PF6 - ), thiocyanate ion (SCN - ), alkylbenzenesulfonate ion (RC6H4SO3 - ), perchlorate ion (ClO4 - ), tetrafluoroborate ion (BF4 -) and other inorganic or organic anions. Ionic liquids include compounds having the above cations and anions. The ionic liquid is preferably solid at room temperature (30°C), and by selecting the chain length of the alkyl group, the position and number of the substituents, etc., it is possible to obtain an ionic liquid with a melting point of 30 to 80°C. The cation constituting the ionic liquid is preferably a quaternary nitrogen-containing onium cation, and examples thereof include quaternary pyridinium cations such as 1-alkylpyridinium ions (carbon atoms at positions 2 to 6 may be substituted or unsubstituted), quaternary imidazolium cations such as 1,3-dialkylimidazolium ions (carbon atoms at positions 2, 4, and 5 may be substituted or unsubstituted), and acyclic quaternary ammonium cations such as tetraalkylammonium ions. The melting point of the ionic liquid is preferably 30 to 49°C.

[0027] Examples of quaternary ammonium salt-type ionic liquids containing an acryloyl group include those in which the cation constituting the ionic liquid is a ((meth)acryloyloxyalkyl)trialkylammonium ion [RN + -C n H 2n -OC(=O)CQ=CH2, where Q=H or CH3, R=alkyl], and the anion constituting the ionic liquid is a hexafluorophosphate ion (PF6 - ), thiocyanate ion (SCN - ), organic sulfonate ions (RSO3 - ), perchlorate ion (ClO4 - ), tetrafluoroborate ion (BF4 - ), F-containing imide ions (R F 2N - ) and other inorganic or organic anions. F-containing imide ions (R F 2N - ) in R FExamples of the fluorine-containing imide ion include perfluoroalkanesulfonyl groups such as trifluoromethanesulfonyl and pentafluoroethanesulfonyl groups, and fluorosulfonyl groups. Examples of the fluorine-containing imide ion include bis(fluorosulfonyl)imide ion [(FSO2)2N - ], bis(trifluoromethanesulfonyl)imide ion [(CF3SO2)2N - ], bis(pentafluoroethanesulfonyl)imide ion [(C2F5SO2)2N - ] and the like.

[0028] Specific preferred examples of the ionic liquid include 1-octylpyridinium hexafluorophosphate, 1-nonylpyridinium hexafluorophosphate, 2-methyl-1-dodecylpyridinium hexafluorophosphate, 1-octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecylpyridinium dodecylbenzenesulfonate, and 4-methyl-1-octylpyridinium hexafluorophosphate. Specific examples of the quaternary ammonium salt type ionic liquid containing an acryloyl group include ((meth)acryloyloxymethyl)trimethylammonium hexafluorophosphate [(CH3)3N + CH2OC(=O)CQ=CH2·PF6 - , where Q=H or CH3], ethyl(2-(meth)acryloylethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide salt [(CH3)3N + (CH2)2OC(=O)CQ=CH2·(CF3SO2)2N - , where Q=H or CH3], ((meth)acryloyloxymethyl)trimethylammonium bis(fluorosulfonyl)imide salt [(CH3)3N + CH2OC(=O)CQ=CH2·(FSO2)2N - , where Q=H or CH3).

[0029] The content of the antistatic agent in the resin layer A(3) is usually 0.5 to 15 mass % to exhibit antistatic properties, preferably 0.5 to 10 mass %, more preferably 0.5 to 7 mass %, and even more preferably 0.5 to 5 mass %.

[0030] (Resin layer B) The resin layer B (4) used in the semiconductor wafer surface protection tape (1) of the present invention is an intermediate resin layer that improves conformability to the irregularities of an electronic component when the semiconductor wafer surface protection tape (1) of the present invention is bonded to the electronic component. The resin layer B (4) differs from the resin layer A (3) in that it has a storage modulus of 1.0 × 10 at 23°C. 3 ~1.0×10 5 It is outside the range of Pa. Since the resin layer B(4) is not intended to be adhesive, it is preferably non-adhesive. Non-adhesive means a state where there is no stickiness at room temperature (25°C).

[0031] Examples of resins (including rubbers and elastomers) constituting the resin layer B(4) include resins made of ethylene-based copolymers, i.e., copolymers of ethylene with at least one comonomer selected from radically polymerizable acid comonomers, acrylic acid ester comonomers, methacrylic acid ester comonomers, and carboxylic acid vinyl ester comonomers; resins made of homopolymers or copolymers of monomers (α-olefins) containing ethylenically unsaturated groups, such as ionomers (excluding the above-mentioned resins made of ethylene-based copolymers); resins made of polyethylene (e.g., low-density polyethylene); and thermoplastic elastomers, such as olefin-based thermoplastic elastomers, having polyolefins such as polyethylene, polypropylene, polybutene-1, and poly-4-methylpentene-1 as hard segments and rubber components such as ethylene-propylene copolymers as soft segments. The resin layer B(4) may contain one or more of these resins alone or in combination. The resin layer B(4) may also have two or more layers.

[0032] Specific examples of the radically polymerizable acid comonomer include α,β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, and itaconic acid, or anhydrides thereof, and unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, vinylacetic acid, and pentenoic acid, and among these, maleic anhydride, acrylic acid, and methacrylic acid are preferred. Specific examples of the acrylic acid ester comonomer include methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate, with methyl acrylate, ethyl acrylate, and butyl acrylate being preferred.

[0033] Specific examples of the methacrylic acid ester comonomer include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate, with methyl methacrylate and ethyl methacrylate being preferred. Specific examples of the vinyl carboxylic acid ester comonomer include vinyl formate, vinyl acetate, vinyl propionate, and vinyl butyrate, with vinyl acetate being preferred.

[0034] Specific examples of ethylene-based copolymers include binary copolymers such as ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-maleic anhydride copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, and ethylene-vinyl acetate copolymer. Examples of ternary copolymers include ethylene-acrylic acid-methyl acrylate copolymer, ethylene-acrylic acid-ethyl acrylate copolymer, ethylene-acrylic acid-vinyl acetate copolymer, ethylene-methacrylic acid-methyl methacrylate copolymer, ethylene-methacrylic acid-ethyl methacrylate copolymer, ethylene-methacrylic acid-vinyl acetate copolymer, ethylene-maleic anhydride-methyl acrylate copolymer, ethylene-maleic anhydride-ethyl acrylate copolymer, ethylene-maleic anhydride-methyl methacrylate copolymer, ethylene-maleic anhydride-ethyl methacrylate copolymer, and ethylene-maleic anhydride-vinyl acetate copolymer. Further, quaternary or higher multi-component copolymers obtained by combining the above-mentioned comonomers may also be used. Among the above copolymers, particularly preferred are ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-maleic anhydride-methyl acrylate copolymer, ethylene-maleic anhydride-ethyl acrylate copolymer, ethylene-maleic anhydride-methyl methacrylate copolymer, and ethylene-maleic anhydride-ethyl methacrylate copolymer, and more preferred are ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, and ethylene-butyl acrylate copolymer.

[0035] In the total mass of ethylene and comonomer used in the synthesis of the ethylene copolymer, the proportion of the comonomer is preferably from 10% by mass to 50% by mass, more preferably from 15% by mass to 40% by mass.

[0036] The resin constituting the resin layer B(4) may be one of the above resins or a combination of two or more of them. The resin layer B(4) may be a single layer or multiple layers.

[0037] The storage modulus of the resin layer B(4) at 70°C is 6.0 × 10 6From the viewpoint of further preventing warpage and further improving conformability to irregularities, the hardness can be set to 3.0×10 6 Pa or less, and 1.0 × 10 3 ~3.0×10 6 Pa, more preferably 1.0×10 3 ~1.0×10 6 More preferably, it is 1.0×10 Pa. 4 ~5.0×10 5 Pa is particularly preferred. When the storage modulus at 70° C. of the resin layer B(4) is within the above preferred range, conformability to the uneven surface of electrical components such as semiconductor wafers can be reliably ensured. In addition, when the resin layer B(4) is a multi-layered structure, the above-mentioned "storage modulus of the resin layer B at 70°C" means the "storage modulus of the resin layer B at 70°C" for each layer constituting the resin layer B(4). That is, when the storage modulus of the resin layer B(4) at 70°C is 6.0 × 10 6 When the storage modulus is "less than 6.0 x 10 Pa," it means that each layer constituting the resin layer B(4) has a storage modulus of 6.0 x 10 Pa or less at 70 °C. 6 This means that the pressure is less than or equal to Pa. The storage modulus at 70°C is a value measured using a dynamic viscoelasticity measuring device under the conditions described in the Examples. The storage modulus can be adjusted to a desired value by adjusting the amount of curing agent in the resin layer B(4), the molecular weight of the polymer, the content of comonomer, the glass transition point of the polymer, the addition of additives such as plasticizers, etc.

[0038] The thickness of the resin layer B (4) is preferably equal to or greater than the unevenness of the surface of an electronic component, such as a semiconductor wafer, to which the semiconductor wafer surface protection tape (1) of the present invention is bonded. From the perspective of application to semiconductor wafers with bumps with large unevenness, the thickness is preferably 200 μm or greater, and more preferably 200 to 400 μm. Taking a semiconductor wafer as an example, if the thickness is thinner than the unevenness of the semiconductor wafer, the adhesive layer 5 will not adhere sufficiently to the semiconductor wafer, resulting in dust intrusion and wafer cracking. The thickness of the resin layer B (4) used in the semiconductor wafer surface protection tape (1) of the present invention is preferably 10 μm to 30 μm thicker than the unevenness of the electronic component, such as a semiconductor wafer. If the resin layer B (4) is too thick, the thickness accuracy of the semiconductor wafer may deteriorate and manufacturing costs may increase. Furthermore, since an error of about 10 μm occurs when manufacturing the bump portion of a bumped semiconductor wafer, a thickness of 10 μm in addition to the average bump height allows for ample tracking. When the resin layer B(4) is a multi-layered layer, the "thickness of the resin layer B(4)" means the total thickness of all layers constituting the resin layer B(4).

[0039] The resin layer B(4) has a thickness of 200 μm or more and a storage modulus at 70° C. of 3.0×10 6 When the viscosity is less than or equal to 1 Pa, the ability to conform to unevenness can be more reliably ensured even if the unevenness of the adherend surface is large, which is preferable.

[0040] The surface of the resin layer B(4) on which the pressure-sensitive adhesive layer (5) is provided may be appropriately treated by corona treatment, by providing a primer layer, or the like in order to improve adhesion to the pressure-sensitive adhesive layer (5). The surface of the resin layer B(4) on which the resin layer A(3) is provided may also be appropriately treated by corona treatment, by providing a primer layer, or the like.

[0041] (Adhesive layer) The adhesive layer (5) used in the semiconductor wafer surface protection tape (1) of the present invention may be any layer containing an adhesive, and may be formed using, for example, an adhesive composition. When the semiconductor wafer surface protection tape (1) of the present invention is attached to an electronic component, the adhesive layer (5) is attached to the uneven surface of the electronic component. The adhesive that constitutes the adhesive layer (5) is preferably an acrylic adhesive. In the present invention, the term "acrylic pressure-sensitive adhesive" refers to a pressure-sensitive adhesive containing a copolymer having a (meth)acrylic acid ester as a constituent component (hereinafter referred to as "(meth)acrylic acid ester copolymer") as a main component polymer (pressure-sensitive adhesive base polymer). In addition to the (meth)acrylic acid ester copolymer, the pressure-sensitive adhesive may contain a crosslinking agent, which will be described later. Here, "containing a (meth)acrylic acid ester copolymer as a main component" means that the content of the (meth)acrylic acid ester copolymer among the polymers or resins that make up the base resin of the adhesive is at least 50% by mass, and preferably 80% by mass or more (100% by mass or less).

[0042] The adhesive constituting the adhesive layer (5) may be a radiation-curable adhesive that is cured by irradiation with radiation, or a non-radiation-curable adhesive that is not cured by irradiation with radiation. As the radiation-curable adhesive, for example, the radiation-curable adhesives described in

[0035] to

[0076] of WO 2018 / 181240 and the radiation-curable adhesives described in

[0031] to

[0050] of JP 2022 / 109374 A can be preferably used.

[0043] The non-radiation-curable pressure-sensitive adhesive is preferably a non-radiation-curable acrylic pressure-sensitive adhesive, and examples of the pressure-sensitive adhesive base polymer in the non-radiation-curable acrylic pressure-sensitive adhesive include a (meth)acrylic acid ester monomer or a (meth)acrylic acid ester copolymer composed of structural units derived from a (meth)acrylic acid ester monomer and (meth)acrylic acid. Here, examples of the (meth)acrylic acid ester monomer that can be used include the (meth)acrylic acid ester monomer used in the primer layer (3) described above and (meth)acrylic acid ester monomers substituted with functional groups such as hydroxyl groups.

[0044] The non-radiation curable adhesive composition may optionally contain a crosslinking agent. The crosslinking agent is a compound selected from polyisocyanate compounds, melamine-formaldehyde resins, and epoxy resins, and may be used alone or in combination of two or more. The crosslinked structure formed as a result of the reaction with the (meth)acrylic copolymer can improve the cohesive strength of the adhesive after application. The polyisocyanate compound is not particularly limited, and for example, the polyisocyanate compound used in the primer layer (3) described above can be used. Specifically, commercially available products such as Coronate L (trade name, manufactured by Tosoh Corporation) can be used. Furthermore, commercially available products such as Nikalac MX-45 (manufactured by Sanwa Chemical Co., Ltd.) and Melan (trade name, manufactured by Hitachi Chemical Co., Ltd.) can be used as the melamine-formaldehyde resin. Furthermore, the epoxy resin such as TETRAD-X (trade name, manufactured by Mitsubishi Chemical Corporation) can be used.

[0045] The amount of crosslinking agent added can be adjusted appropriately to obtain the desired adhesive properties relative to 100 parts by mass of the adhesive base polymer; for example, it is preferably 0.1 to 20 parts by mass, and more preferably 0.1 to 5 parts by mass.

[0046] In addition, the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer (5) may contain, as necessary, a release agent, a tackifier, an adhesion adjuster, a surfactant, or other modifiers, etc. Furthermore, it may contain an inorganic compound filler.

[0047] The thickness of the pressure-sensitive adhesive layer (5) can be, for example, 3 to 150 μm, and preferably 5 to 150 μm. The semiconductor wafer surface protection tape (1) of the present invention may be configured so that the resin layer A (3) contains an antistatic agent, thereby providing a semiconductor wafer surface protection tape with antistatic properties. In this case, even if the pressure-sensitive adhesive layer (5) is made thicker than 100 μm in order to improve the ability of the semiconductor wafer surface protection tape (1) to embed irregularities into the wafer surface, excellent antistatic properties can be achieved.

[0048] (Release film) In the semiconductor wafer surface protection tape (1) of the present invention, a release film is provided on the adhesive layer (5) as needed. The release film, also called a separator, release layer, or release liner, is provided for the purpose of protecting the adhesive layer (5) and smoothing the adhesive layer (5). Examples of materials for the release film include synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate, as well as paper. The surface of the release film may be subjected to a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment as needed to enhance releasability from the adhesive layer (5). Furthermore, if needed, an ultraviolet protection treatment may be applied to prevent the adhesive layer (5) from reacting due to unintended exposure to ultraviolet light, such as environmental ultraviolet light. The thickness of the release film is typically 10 to 100 μm, preferably 25 to 50 μm.

[0049] (Method of manufacturing the semiconductor wafer surface protection tape of the present invention) The method for producing the semiconductor wafer surface protection tape of the present invention is not particularly limited, and it can be produced by a conventional method. The base material layer (2) and the resin layer B (4) can be produced by conventional methods such as extrusion, inflation, casting, etc. Alternatively, a multi-layer base material layer (2) and a multi-layer resin layer B (4) can be produced by laminating an independently produced film with another film using an adhesive or the like. The resin layer A (3) and the pressure-sensitive adhesive layer (5) can be formed by applying a composition for forming the resin layer A (3) (resin layer A-forming composition) or a composition for forming the pressure-sensitive adhesive layer (5) (pressure-sensitive adhesive composition) to a release film or film-like substrate layer (2) or resin layer B (4) and drying the applied composition. The obtained resin layer A (3) and pressure-sensitive adhesive layer (5) can be laminated as layers constituting the semiconductor wafer surface protection tape of the present invention by laminating or transferring them with other layers in accordance with the laminate structure to be incorporated into the semiconductor wafer surface protection tape of the present invention. The method for producing the semiconductor wafer surface protecting tape of the present invention includes the following methods, but the method for producing the semiconductor wafer surface protecting tape of the present invention is not limited to the following methods. A composition for forming a resin layer A is applied onto a film-like base layer (2) and dried, and then a film-like resin layer B (4) is laminated to the layer obtained by applying and drying the composition for forming a resin layer A, thereby obtaining an adhesive film 1. Separately from the laminating film 1, a pressure-sensitive adhesive composition is applied to the release-treated surface of a release film and dried to prepare a pressure-sensitive adhesive layer (5). Thereafter, the obtained adhesive layer (5) is bonded to the surface of the resin layer B (4) of the adhesive film 1, and the adhesive layer (5) is transferred to obtain a tape for protecting the surface of a semiconductor wafer. The release film used to prepare the pressure-sensitive adhesive layer (5) may remain attached to the semiconductor wafer surface protection tape, but when using the semiconductor wafer surface protection tape of the present invention, the release film is first peeled off from the pressure-sensitive adhesive layer (5).

[0050] (Uses of the semiconductor wafer surface protection tape of the present invention) The semiconductor wafer surface protection tape of the present invention can be suitably used as a surface protection adhesive tape for semiconductor processing, which is attached to the uneven surface side of a semiconductor wafer in a semiconductor chip manufacturing method in which the semiconductor wafer is diced into chips by back grinding, and can be suitably used in particular for semiconductor wafers with large unevenness differences, as it exhibits excellent unevenness followability.

[0051] [Semiconductor wafer processing method] A method for processing a semiconductor wafer using the semiconductor wafer surface protecting tape of the present invention will be described below.

[0052] The semiconductor wafer surface protection tape (1) of the present invention may be used in any step of the semiconductor wafer processing process, such as a semiconductor wafer back grinding step, a dicing step, and a dicing die bonding step.

[0053] The semiconductor wafer surface protection tape (1) of the present invention can be applied to the surface of a semiconductor wafer having a difference in unevenness of 20 μm or more (height of bumps (electrodes) or depth of scribe lines), and is preferably applied to semiconductor wafers having a difference in unevenness of 200 μm or more, more preferably 200 to 400 μm. In particular, as described in the examples below, the semiconductor wafer surface protection tape (1) of the present invention can exhibit good unevenness followability even on semiconductor wafers having a difference in unevenness of more than 100 μm. The types of bumps and electrodes on the semiconductor wafer are not particularly limited. For example, the bumps can exhibit good conformability to bumps formed by any of the plating bump method, screen printing method, and ball mounting method.

[0054] The arrangement density (high density) of the bumps on the surface of the semiconductor wafer is not particularly limited. For example, it can be applied to a pitch (distance from the apex of a bump in the height direction to the apex of the next bump in the height direction) of 0.5 to 3 times or less, preferably 1 to 2 times or less, of the height of the bumps. It can also be used for semiconductor wafers with bumps arranged uniformly over the entire surface.

[0055] The thickness of the semiconductor wafer before back grinding is not particularly limited, and may be, for example, 500 to 800 μm. Furthermore, the thickness of the semiconductor wafer after back grinding using the semiconductor wafer surface protection tape (1) of the present invention can be adjusted to a desired thickness, for example, 20 to 500 μm, preferably 50 to 250 μm, more preferably 80 to 250 μm. By using the semiconductor wafer surface protection tape (1) of the present invention, warpage of the tape-attached semiconductor wafer after thin film grinding can be suppressed.

[0056] The method for processing a semiconductor wafer using the semiconductor wafer surface protection tape (1) of the present invention preferably includes a step of laminating the semiconductor wafer surface protection tape (1) of the present invention to a semiconductor wafer, and then irradiating the semiconductor wafer surface protection tape with radiation (preferably ultraviolet light) to peel off the semiconductor wafer surface protection tape.

[0057] For example, first, the adhesive layer (5) of the semiconductor wafer surface protection tape (1) of the present invention is attached to the circuit pattern surface (surface) of a semiconductor wafer. Next, the side of the semiconductor wafer opposite the circuit pattern is ground until the thickness of the semiconductor wafer reaches a predetermined thickness, for example, 10 to 200 μm. Thereafter, the semiconductor wafer surface protection tape is placed on a heating and adsorption stage with the adhesive side facing down, and in this state, a dicing die bonding film may be attached to the ground side of the semiconductor wafer. After the dicing step, a heat seal type (thermal fusion type) or adhesive type release tape is adhered to the back surface of the base layer (2) of the semiconductor wafer surface protection tape (1), and the semiconductor wafer surface protection tape (1) is peeled off from the semiconductor wafer. When peeling off the semiconductor wafer surface protection tape (1), it is preferable that the adhesive layer (5) has been cured by irradiation with radiation (preferably ultraviolet light) to reduce its adhesive strength. [Example]

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0059] <Base material layer> (Film 1) As film 1, a polyethylene terephthalate (PET) film having a thickness of 50 μm and having been subjected to a corona treatment on one side was prepared. (Film 2) As film 2, a polyethylene naphthalate (PEN) film having a thickness of 50 μm and having been subjected to a corona treatment on one side was prepared. (Film 3) As film 3, a polypropylene (PP) film having a thickness of 50 μm and having been subjected to a corona treatment on one side was prepared. (Film 4) A low density polyethylene resin (LDPE) having a melting point of 105° C. was extruded to form a film having a thickness of 100 μm, and one side of the obtained film was subjected to a corona treatment, thereby obtaining Film 4.

[0060] <Composition for forming resin layer A> (Preparation of Resin Composition A1) Resin composition A1 was obtained by adding and mixing 0.7 parts by mass of Coronate L (trade name, manufactured by Tosoh Corporation) to 100 parts by mass of a copolymer consisting of 80 parts by mass of ethyl acrylate, 15 parts by mass of 2-hydroxyethyl acrylate, and 5 parts by mass of methacrylic acid. (Preparation of Resin Composition A2) Resin composition A2 was obtained by adding 1.0 part by mass of Coronate L (trade name, manufactured by Tosoh Corporation) to 100 parts by mass of a copolymer consisting of 80 parts by mass of ethyl acrylate, 15 parts by mass of 2-hydroxyethyl acrylate, and 5 parts by mass of methacrylic acid and mixing them. (Preparation of Resin Composition A3) Resin composition A3 was obtained by adding 0.3 parts by mass of Coronate L (trade name, manufactured by Tosoh Corporation) to 100 parts by mass of a copolymer consisting of 80 parts by mass of ethyl acrylate, 15 parts by mass of 2-hydroxyethyl acrylate, and 5 parts by mass of methacrylic acid and mixing them. (Preparation of Resin Composition A4) Resin composition A4 was obtained by adding and mixing 0.5 parts by mass of Coronate L (trade name, manufactured by Tosoh Corporation) to 100 parts by mass of a polyester-based adhesive (manufactured by Mitsubishi Chemical Corporation, trade name: Nichigo Polyester LP-011S50EO). (Preparation of Resin Composition A5) Resin composition A5 was obtained by adding 0.15 parts by mass of Coronate L (trade name, manufactured by Tosoh Corporation) to 100 parts by mass of a copolymer consisting of 80 parts by mass of ethyl acrylate, 15 parts by mass of 2-hydroxyethyl acrylate, and 5 parts by mass of methacrylic acid and mixing them. (Preparation of Resin Composition A6) Resin composition A6 was obtained by adding and mixing 1.5 parts by mass of Coronate L (trade name, manufactured by Tosoh Corporation) to 100 parts by mass of a copolymer consisting of 80 parts by mass of ethyl acrylate, 15 parts by mass of 2-hydroxyethyl acrylate, and 5 parts by mass of methacrylic acid.

[0061] <Resin layer B> (Film B1) The melting point is 59°C, and the storage modulus at 70°C is 1.4 x 10 5 Ethylene-vinyl acetate copolymer (EVA) Pa was extruded to a thickness of 350 μm to form a film, and both sides of the obtained film were subjected to corona treatment to obtain film B1. (Film B2) The melting point is 51°C, and the storage modulus at 70°C is 8.5 x 10 4 An olefin-based thermoplastic elastomer (TPO) of Pa was extruded to a thickness of 350 μm to form a film, and both surfaces of the obtained film were subjected to a corona treatment to obtain a film B2. (Film B3) The melting point is 56°C, and the storage modulus at 70°C is 2.8 x 10 6 The poly-α-olefin Pa was extruded to a thickness of 350 μm to form a film, and both surfaces of the obtained film were subjected to corona treatment to obtain film B3. (Film B4) The melting point is 64°C, and the storage modulus at 70°C is 3.2 x 10 6Ethylene-vinyl acetate copolymer (EVA) Pa was extruded to a thickness of 350 μm to form a film, and both sides of the obtained film were subjected to corona treatment to obtain film B4.

[0062] <Adhesive composition> A pressure-sensitive adhesive composition was obtained by adding 1.0 part by mass of Coronate L (trade name, manufactured by Tosoh Corporation) to 100 parts by mass of a copolymer consisting of 70 parts by mass of butyl acrylate, 28 parts by mass of 2-hydroxyethyl acrylate, and 2 parts by mass of methacrylic acid and mixing them.

[0063] <Production of tape for protecting semiconductor wafer surfaces> Example 1 Resin composition A1 was applied to the corona-treated surface of film 1 as the base layer so that the film thickness after drying would be 30 μm, and then dried. Immediately after drying, film B1 as the resin layer B was bonded to the applied film to obtain laminated film 1. Separately from the above-mentioned adhesive film 1, a pressure-sensitive adhesive composition was applied to the release-treated surface of a 40 μm-thick polypropylene (PP) separator (also referred to as a release film) that had been subjected to a release treatment on one side, so that the film thickness after drying would be 10 μm, and the adhesive composition was dried to obtain a pressure-sensitive adhesive layer. Thereafter, the pressure-sensitive adhesive layer was transferred by bonding it to the surface side of the resin layer B of the above-mentioned adhesive film 1, and the semiconductor wafer surface protection tape of Example 1 was obtained. The semiconductor wafer surface protection tape (1) of Example 1 obtained in this manner has a structure in which a base layer (2), a resin layer A (3), a resin layer B (4), and an adhesive layer (5) are laminated in this order, as shown in FIG. 1, and a release film (not shown in FIG. 1) is further laminated on the adhesive layer (5).

[0064] <Examples 2 to 12 and Comparative Examples 1 to 4> The semiconductor wafer surface protection tapes of Examples 2 to 12 and Comparative Examples 1 to 4 were produced in the same manner as in the production of the semiconductor wafer surface protection tape of Example 1 above, except that the configuration of at least one of the base layer (2), resin layer A (3), and resin layer B (4) was changed to the configurations described in Tables 1-1 and 1-2 below. The semiconductor wafer surface protection tapes (1) of Examples 2 to 12 obtained in this manner have a structure in which a base layer (2), a resin layer A (3), a resin layer B (4), and a pressure-sensitive adhesive layer (5) are laminated in this order, and a release film (not shown in FIG. 1) is further laminated on the pressure-sensitive adhesive layer (5), as shown in Fig. 1. The semiconductor wafer surface protection tapes of Comparative Examples 1 to 4 have a structure in which a base layer (2), a resin layer A (3), a resin layer B (4), and a pressure-sensitive adhesive layer (5) are laminated in this order, and a release film is further laminated on the pressure-sensitive adhesive layer (5).

[0065] <Comparative Example 5> The ethylene-vinyl acetate copolymer (EVA) used to produce film B1 was extruded to a thickness of 350 μm onto the corona-treated surface of film 1 as the base layer to form resin layer B, and corona treatment was applied to the surface on the resin layer B side to obtain laminated film 2. Separately from the above-mentioned adhesive film 2, a pressure-sensitive adhesive composition was applied to the release-treated surface of a 40 μm-thick polypropylene (PP) separator that had been subjected to one-side release treatment so that the film thickness after drying would be 10 μm, and then dried to obtain a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer was then transferred by bonding it to the surface side of the resin layer B of the above-mentioned adhesive film 2, thereby obtaining a semiconductor wafer surface protection tape of Comparative Example 5. The semiconductor wafer surface protection tape of Comparative Example 5 obtained in this manner has a structure in which a base layer (2), a resin layer B (4) and an adhesive layer (5) are laminated in this order, and a release film is further laminated on top of the adhesive layer (5).

[0066] [1. Evaluation method for warp prevention performance] A semiconductor wafer surface protection tape was laminated to an 8-inch diameter bare wafer using a BG (back grind) tape laminator (manufactured by Lintec Corporation, product name: RAD3510F / 8) at a lamination table temperature of 70°C, a roller temperature of 65°C, a roll pressure of 0.3 MPa, and a roll speed of 3 mm / sec, and then a circle cut was performed. The bare wafer's surface opposite the tape-attached surface was then ground using a grinder / polisher (Disco Corporation, product name: DGP8760) until the bare wafer's thickness was reduced to 200 μm. The resulting ground bare wafer with the semiconductor wafer surface protection tape was stored at 23°C and 50% humidity. 24 hours after grinding (storage), the bare wafer with the semiconductor wafer surface protection tape was placed on a precision inspection surface plate with a flatness of Class 1 conforming to the precision top plate of JIS (Japanese Industrial Standards) B 7513 (1992), with the semiconductor wafer surface protection tape facing up. Measurements were performed using the surface plate as the zero point, with 17 equally spaced measurement points around the circumference of the wafer. The warpage (distance) from the zero point to each measurement point was measured using a long rod. The maximum warpage was used to evaluate the warpage prevention performance based on the following criteria. - Anti-warping performance - ◎: Maximum warpage ≦3.0mm 〇: 3.0mm<Maximum warpage<8.0mm ×: Maximum warpage ≥ 8.0 mm

[0067] [2. Evaluation method for unevenness tracking] The semiconductor wafer surface protection tape prepared above was laminated to the bump-bearing side of an 8-inch diameter semiconductor wafer having solder ball-shaped bumps with a ball width of approximately 230 μm, with a height (distance from the surface of the semiconductor wafer substrate to the highest point of the bump) of 200 μm and a pitch (distance between the tops of the bumps) of 400 μm, using a BG (back grind) tape laminator (manufactured by Lintec Corporation, product name: RAD3510F / 8) at a lamination table temperature of 70°C, a roller temperature of 65°C, a roll pressure of 0.3 MPa, and a roll speed of 3 mm / sec, and then circle cut. The thickness of the semiconductor wafer to which the semiconductor wafer surface protection tape was attached was measured using a spindle-type dial gauge (manufactured by Mitutoyo Corporation) from the surface of the semiconductor wafer that did not have bumps (starting point) to the surface of the base layer (2) of the semiconductor wafer surface protection tape that was not in contact with the resin layer A (3) (ending point), with the measuring probe of the dial gauge facing the semiconductor wafer surface protection tape side. Specifically, the thickness at the center of the semiconductor wafer (the center of the circle) was measured as α, and the thickness at the edge of the semiconductor wafer, where there were no bumps, was measured as β. If conformability is insufficient, a gap will form between the semiconductor wafer surface protection tape and the semiconductor wafer, resulting in a larger α. Those that satisfied α-β≦60μm were evaluated as having good conformability and given a rating of "Good," those that satisfied 60μm<α-β≦85μm were evaluated as having good conformability and given a rating of "△," and those that satisfied 85μm<α-β were evaluated as "Poor."

[0068] [3. Evaluation method for blade contamination suppression] A semiconductor wafer surface protection tape was laminated to an 8-inch diameter bare wafer using a BG (back grind) tape laminator (manufactured by Lintec Corporation, product name: RAD3510F / 8) at a lamination table temperature of 70°C, a roller temperature of 65°C, a roll pressure of 0.3 MPa, and a roll speed of 3 mm / sec, and then a circle cut was performed. The same blade was used without any cleaning process, and the above operation was repeated 10 times. After that, the blade was visually inspected, and if there was no contamination, the blade contamination control was evaluated as "Good", and if there was contamination, it was evaluated as "Poor".

[0069] (Melting point of base layer) The melting point of the substrate layer was measured at a heating rate of 10°C / min using a high-sensitivity differential scanning calorimeter (manufactured by Hitachi High-Tech Science Corporation, product name: DSC7000X) based on JIS (Japanese Industrial Standards) K7121 (1987) Plastic Transition Temperature Measurement Method.

[0070] (Storage modulus of resin layer A and resin layer B) The storage modulus of the resin layer A (3) at 23°C and the storage modulus of the resin layer B (4) at 70°C were measured using a dynamic viscoelasticity measuring device (manufactured by Thermo Fisher Scientific, trade name: HAAKE MARS iQ rheometer) by the following method. Specifically, a measurement sample with a thickness of 1000 μm was prepared using the resin constituting each resin layer, and the sample was heated from 0°C to 100°C at a rate of 10°C / min while applying a shear strain with a frequency of 1 Hz, and the storage modulus of resin layer A (3) at 23°C and the storage modulus of resin layer B (4) at 70°C were measured. In the tables, the storage modulus at 23°C is simply referred to as "modulus at 23°C," and the storage modulus at 70°C is simply referred to as "modulus at 70°C."

[0071] (Thickness of each layer) The thickness of each layer was measured on a surface plate using a spindle-type dial gauge (manufactured by Mitutoyo Corporation).

[0072] [Table 1-1]

[0073] [Table 1-2]

[0074] The films listed in the columns for resin layer B and substrate layer, and the resin compositions listed in the column for resin layer A are as described at the beginning of each example. (Resin layer B) EVA: Ethylene-vinyl acetate copolymer TPO: Thermoplastic olefin elastomer (base material layer) PET: Polyethylene terephthalate PEN: Polyethylene naphthalate PP: Polypropylene LDPE: Low-density polyethylene "-": indicates that resin layer A is not present.

[0075] The results in Table 1 reveal the following: In the surface protection tape for semiconductor wafers of Comparative Example 1, the storage modulus of resin layer A at 23°C was 9.6 × 10 2 The storage modulus of the resin layer A at 23°C was 1.5 × 10 5 The tape for protecting a semiconductor wafer surface of Comparative Example 2 was not a tape for protecting a semiconductor wafer of the present invention in that the tape had a surface roughness Pa greater than the specified value of the present invention. The tape for protecting a semiconductor wafer of Comparative Example 2 was not able to sufficiently prevent warpage. Furthermore, the semiconductor wafer surface protective tape of Comparative Example 3 is not a semiconductor wafer surface protective tape of the present invention in that the thickness of resin layer A is 1 μm, which is thinner than the specified thickness of the present invention. The semiconductor wafer surface protective tape of Comparative Example 3 was not able to sufficiently prevent warpage. Furthermore, the semiconductor wafer surface protective tape of Comparative Example 4 is not a semiconductor wafer surface protective tape of the present invention in that the thickness of resin layer A is 60 μm, which is thicker than the specified thickness of the present invention. The semiconductor wafer surface protective tape of Comparative Example 4 caused blade contamination. Furthermore, the semiconductor wafer surface protecting tape of Comparative Example 5 is not the semiconductor wafer surface protecting tape of the present invention in that it does not have resin layer A between resin layer B and base layer, and the semiconductor wafer surface protecting tape of Comparative Example 5 was not able to sufficiently prevent warpage. In contrast, Examples 1 to 12, which are semiconductor wafer surface protection tapes defined in the present invention, exhibited excellent conformability to the irregularities of semiconductor wafers having high bumps, and were able to effectively suppress both the occurrence of warpage and blade contamination. [Explanation of symbols]

[0076] 1. Tape for protecting semiconductor wafer surfaces 2 Base material layer 3 Resin layer A 4 Resin layer B 5. Adhesive layer

Claims

1. The sheet includes a base layer, a resin layer A, a resin layer B, and a pressure-sensitive adhesive layer in this order, The storage modulus of the resin layer A at 23°C is 1.0 × 10 ３ ~1.0 x 10 ５ Pa, wherein the thickness of the resin layer A is 3 to 55 μm.

2. 2. The tape for protecting a semiconductor wafer surface according to claim 1, wherein the melting point of the base layer is 80° C. or higher.

3. The thickness of the resin layer B is 200 μm or more, and the storage modulus of the resin layer B at 70° C. is 3.0×10 ６ 2. The semiconductor wafer surface protecting tape according to claim 1, wherein the surface tension is 0.05 Pa or less.

4. 4. The semiconductor wafer surface protecting tape according to claim 1, wherein the resin layer A is a layer containing an acrylic adhesive or a polyester adhesive.

5. 5. The semiconductor wafer surface protecting tape according to claim 4, wherein the resin layer A contains an antistatic agent, and the antistatic agent is an ionic liquid.

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