Tape for protecting semiconductor wafer surface

Abstract

A tape for protecting a semiconductor wafer surface that is characterized by including a substrate layer, a resin layer A, a resin layer B, and an adhesive layer in the order given, wherein 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.

Description

Semiconductor wafer surface protection tape

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

[0002] In the processing of electronic components such as semiconductor wafers, tapes having an adhesive layer on the adhesive surface to which the electronic components are attached 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, so-called backside grinding and polishing is performed, in which the backside of the semiconductor wafer is ground and polished to a predetermined thickness. In this process, a semiconductor wafer surface protection tape is attached to the surface of the semiconductor wafer to protect 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 been adopted. 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, some of these bumps have a bump height (unevenness of the semiconductor wafer surface) of more than 100 μm. Semiconductor wafer surface protection tapes that are applied to semiconductor wafers with such large surface unevenness require high conformability to uneven surfaces.

[0004] In order to achieve conformability to the irregularities on a semiconductor wafer for bumps with 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 a pressure-sensitive 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 on the surface of a semiconductor wafer.

[0005] Japanese Patent Application Laid-Open No. 2020-174063

[0006] Typically, wafers with circuit patterns formed thereon are thinned to a thickness of approximately 200 to 350 μm during the backgrinding process. Due to their thinness, thin-film wafers after backgrinding are prone to curvature (hereinafter referred to as warpage). This warpage can cause the thin-film wafer to fall during transport or to come into contact with the transport tray when being placed in the tray, resulting in breakage. Therefore, it is necessary to keep the warpage of thin-film wafers after backgrinding below the standard (usually 5 to 10 mm or less). Furthermore, the warpage of thin-film wafers can also be caused by the semiconductor wafer surface protection tape that is 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 and then shrinks when the temperature drops to room temperature (approximately 25°C) after lamination, resulting in various internal stresses on the thin-film wafer. Furthermore, applying tension to the semiconductor wafer surface protection tape during the heat lamination to prevent it from bending also contributes to increasing the internal stress on the thin-film wafer. These internal stresses caused by lamination of the semiconductor wafer surface protection tape tend to exacerbate warpage. According to the inventor's research, a tape such as that described in Patent Document 1, which uses a resin layer disposed between the base film and the pressure-sensitive adhesive layer with a storage modulus of 200,000 Pa or less at temperatures between 60°C and 80°C to achieve sufficient conformability to the uneven surface of a semiconductor wafer with high bumps, has been found to exhibit good conformability to the uneven surface of the wafer, but may experience significant warpage of approximately 10 mm. Furthermore, as a result of further investigation, it was discovered that if a resin layer for alleviating internal stress is incorporated into part of the laminated structure of the tape in order to suppress the occurrence of warping, a new problem arises in that the blade becomes contaminated when circle cutting a semiconductor wafer to which the semiconductor wafer surface protection tape is attached.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.

[0007] The above-mentioned problems of the present invention have been solved by the following means: <1> A pressure-sensitive adhesive sheet including a base layer, a resin layer A, a resin layer B, and a pressure-sensitive adhesive layer in this order, wherein the storage modulus of the resin layer A at 23°C is 1.0 × 10 ３ ~1.0 x 10 ５ <2> The semiconductor wafer surface protection tape according to <1>, wherein the melting point of the base layer is 80°C or higher. <3> The resin layer B has a thickness of 200 μm or higher, and the storage modulus of the resin layer B at 70°C is 3.0 × 10 ６ The semiconductor wafer surface protection tape according to <1> or <2>, characterized in that the viscosity of the surface of the semiconductor wafer is 100 Pa or less. <4> The semiconductor wafer surface protection tape according to any one of <1> to <3>, characterized in that the resin layer A is a layer containing an acrylic pressure-sensitive adhesive or a polyester pressure-sensitive adhesive. <5> The semiconductor wafer surface protection tape according to any one of <1> to <4>, characterized in that the resin layer A contains an antistatic agent, and the antistatic agent is an ionic liquid.

[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.

[0009] FIG. 1 is a schematic cross-sectional view showing one embodiment of the semiconductor wafer surface protection tape of the present invention.

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

[0011] [Semiconductor wafer surface protection tape] The semiconductor wafer surface protection tape 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 resin layer A has a storage modulus at 23°C of 1.0 × 10 ３ ~1.0 x 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, as well as to effectively suppress both the occurrence of warpage and blade contamination. Preferred embodiments of the semiconductor wafer surface protection tape of the present invention are described below.

[0012] As shown in Figure 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 Figure 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 can also be in the form of a laminate of the base layer (2), resin layer A (3), resin layer B (4), pressure-sensitive adhesive layer (5), and release film wound into a roll.

[0013] (Base layer) The resin (in the present invention, the term "resin" includes elastomers) constituting the base 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 base films in the technical field to which the present invention belongs can be used. Note that the base 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 x 10 ５The viscosity is outside the range of Pa. Examples of resins constituting the base layer (2) include polyolefin resins composed of homopolymers or copolymers of monomers containing ethylenically unsaturated groups, such as polyethylene (e.g., low-density polyethylene), polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, and ionomers; polyester resins (e.g., polyethylene terephthalate and polyethylene naphthalate), polycarbonate resin, polyurethane resin, and engineering plastics (e.g., polymethyl methacrylate resin); synthetic rubbers (e.g., styrene-ethylene-butene or pentene copolymer); and thermoplastic elastomers (e.g., polyamide-polyol copolymer). The resin constituting the base layer (2) may be one of the above resins, or a combination of two or more of them. The base layer (2) may be a single layer or multiple layers. In addition to the above resins, the base layer (2) may contain additives such as colorants and antioxidants, as needed, to the extent that the physical properties are not affected. 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 typically 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 substrate layer (2) is 80°C or higher, the substrate layer (2) can be prevented from melting and fusing to devices, etc., due to the temperature environment during application of the semiconductor wafer surface protection tape (1) of the present invention to electronic components, or during processing of the electronic components in the applied state. For example, when the semiconductor wafer surface protection tape is heated to approximately 40 to 70°C and applied to the circuit pattern surface of a semiconductor wafer with high steps, fusing to the lamination roller or chuck table can be prevented. Furthermore, when the melting point of the substrate layer (2) is 170°C or higher, warping can be further prevented. When the substrate layer (2) is a multi-layer structure, the "melting point of the substrate layer" refers to the melting point of the outermost layer of the substrate layer opposite the primer layer (3). The melting point is a value measured by a DSC (differential scanning calorimeter) method at a heating rate of 10°C / min in accordance with JIS (Japanese Industrial Standards) K 7121 (1987) Method for measuring transition temperatures of plastics.

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

[0016] The surface of the substrate 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 x 10 ５There are no particular limitations on the resin layer A (3) as long as it has a storage modulus at 23°C and a thickness of 3 to 55 μm. When the resin layer A (3) is a resin layer having a storage modulus at 23°C and a thickness within the above-mentioned specific ranges, the semiconductor wafer surface protection tape (1) of the present invention can achieve both anti-warping performance and blade contamination suppression. The resin layer A (3) can be, for example, a layer containing an acrylic adhesive or a polyester adhesive, and is preferred. The definition of acrylic adhesive is synonymous with the acrylic adhesive in the adhesive layer described below.

[0018] Examples of the (meth)acrylic acid ester copolymer constituting the acrylic pressure-sensitive adhesive include (meth)acrylic acid ester copolymers 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 a cycloalkyl (meth)acrylic acid ester, a benzyl (meth)acrylic acid ester, and a (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). Examples of the (meth)acrylic acid ester monomer substituted with a functional group such as a hydroxy group include a (meth)acrylic acid ester monomer in which the cycloalkyl group, benzyl group, or alkyl group constituting the ester in the (meth)acrylic acid ester is substituted with a hydroxy group. 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 polyisocyanate compound is not particularly limited, and examples thereof include aromatic isocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4'-[2,2-bis(4-phenoxyphenyl)propane]diisocyanate, as well as hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate, and lysine triisocyanate. Commercially available crosslinking agents can also be used, such as Coronate L (manufactured by Tosoh Corporation). Examples of polyvalent epoxy 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. Examples of anilines include 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, and hexa[1-(2-methyl)-aziridinyl]triphosphatriazine. Examples of chelate compounds include ethyl acetoacetate aluminum diisopropylate and aluminum tris(ethyl acetoacetate).

[0020] The amount of the crosslinking agent to be blended is preferably 0.2 to 1.4 parts by mass, more preferably 0.20 to 1.2 parts by mass, even 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 polycarboxylic acids with a valence of three or more. Examples of the polyol component include dihydric alcohols and polyhydric alcohols with a valence of three or more. 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 above adhesives, the resin layer A (3) may contain additives such as colorants and antioxidants, as needed, within the range that does not affect the physical properties.

[0023] The storage modulus of the resin layer A(3) at 23°C is 1.0 x 10 ３ ~1.0 x 10 ５ Pa, 8.0 × 10 ３ ~1.0 x 10 ５ From the viewpoint of further preventing warpage, it is more preferable that the viscosity is 2.0×10 ４ ~8.0 x 10 ４ It is more preferable that the storage modulus is 23 ° C. Pa. In addition, when the resin layer A (3) is a multilayer, the above "storage modulus at 23 ° C." means the storage modulus at 23 ° C. measured as a whole of the multilayer resin layer A (3). 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 the 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 above "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 performance 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 antistatic agents commonly used in semiconductor wafer surface protection tape applications 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, excellent antistatic performance can be exhibited 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, and this is preferable. In the present invention, "ionic liquid" refers to a salt composed of an anion and a cation and a compound having 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 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 anions constituting the ionic liquid include hexafluorophosphate ion (PF ６ － ), thiocyanate ion (SCN － ), alkylbenzenesulfonate ion (RC ６ H ４ SO ３ － ), perchlorate ion (ClO ４ － ), tetrafluoroborate ion (BF ４ －) and other inorganic or organic anions. Examples of ionic liquids include compounds having the above-mentioned cations and anions. Ionic liquids are preferably solid at room temperature (30°C), and by selecting the chain length of the alkyl group, the position and number of substituents, and the like, it is possible to obtain ionic liquids with melting points 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 [R ３ N ＋ -C ｎ H ２ｎ -OC(=O)CQ=CH ２ , where Q=H or CH ３ , R = alkyl)], and the anion constituting the ionic liquid is a hexafluorophosphate ion (PF ６ － ), thiocyanate ion (SCN － ), organic sulfonate ions (RSO ３ － ), perchlorate ion (ClO ４ － ), tetrafluoroborate ion (BF ４ － ), F-containing imide ion (R Ｆ ２ N － ) and other inorganic or organic anions. Ｆ ２ N － ) in R ＦExamples of the F-containing imide ion include perfluoroalkanesulfonyl groups such as trifluoromethanesulfonyl and pentafluoroethanesulfonyl groups, and fluorosulfonyl groups. Examples of the F-containing imide ion include bis(fluorosulfonyl)imide ions [(FSO ２ ) ２ N － ], bis(trifluoromethanesulfonyl)imide ion [(CF ３ SO ２ ) ２ N － ], bis(pentafluoroethanesulfonyl)imide ion [(C ２ F ５ SO ２ ) ２ N － ] and the like.

[0028] Preferred specific 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 ionic liquid containing an acryloyl group include ((meth)acryloyloxymethyl)trimethylammonium hexafluorophosphate [(CH ３ ) ３ N ＋ CH ２ OC(=O)CQ=CH ２ ・PF ６ － , where Q=H or CH ３ ], ethyl(2-(meth)acryloylethyl)trimethylammonium=bis(trifluoromethanesulfonyl)imide salt [(CH ３ ) ３ N ＋ (CH ２ ) ２ OC(=O)CQ=CH ２ ・(CF ３ SO ２ )２ N － , where Q=H or CH ３ ], ((meth)acryloyloxymethyl)trimethylammonium bis(fluorosulfonyl)imide salt [(CH ３ ) ３ N ＋ CH ２ OC(=O)CQ=CH ２ ・(FSO ２ ) ２ N － , where Q=H or CH ３ ] etc.

[0029] The content of the antistatic agent in the resin layer A(3) is usually 0.5 to 15% by mass, which is sufficient to exhibit antistatic properties, and is preferably 0.5 to 10% by mass, more preferably 0.5 to 7% by mass, and even more preferably 0.5 to 5% by 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 electronic components when the semiconductor wafer surface protection tape (1) of the present invention is attached to the electronic components. Note that, unlike the resin layer A (3), the resin layer B (4) has a storage modulus at 23°C of 1.0 × 10 ３ ~1.0 x 10 ５ The viscosity 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, which are copolymers of ethylene with at least one comonomer selected from the group consisting of a radically polymerizable acid comonomer, an acrylic acid ester comonomer, a methacrylic acid ester comonomer, and a carboxylic acid vinyl ester comonomer; 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 of these resins alone or in combination of two or more. 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 or anhydrides thereof, such as maleic acid, fumaric acid, citraconic acid, and itaconic acid, and unsaturated monocarboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, vinylacetic acid, and pentenoic acid, with maleic anhydride, acrylic acid, and methacrylic acid being 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 carboxylic acid vinyl 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. 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-methyl methacrylate copolymer, ethylene-maleic anhydride-methyl methacrylate copolymer, and ethylene-maleic anhydride-vinyl acetate copolymer. Furthermore, quaternary or higher multi-component copolymers combining the above-mentioned comonomers are also included. 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] The proportion of the comonomer in the total mass of ethylene and the comonomer used in the synthesis of the ethylene copolymer is preferably 10% by mass to 50% by mass, more preferably 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 ６ From the viewpoint of further preventing warpage and further improving conformability to irregularities, the viscosity of the sheet is preferably 3.0 × 10 ６ Pa or less, and ３ ~3.0 x 10 ６ Pa, more preferably 1.0 × 10 ３ ~1.0 x 10 ６ Pa, more preferably 1.0 × 10 ４ ~5.0 x 10 ５ It is particularly preferable that the storage modulus at 70°C of the resin layer B(4) is within the above-mentioned preferred range, it is possible to reliably ensure conformability to the uneven surface of an electrical component such as a semiconductor wafer. When the resin layer B(4) is a multi-layered layer, the above "storage modulus at 70°C of the resin layer B" means the "storage modulus at 70°C of the resin layer B" for each layer constituting the resin layer B(4). That is, the storage modulus at 70°C of the resin layer B(4) is 6.0 x 10 ６ When the storage modulus is "not more 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 storage modulus at 70°C is equal to or less than 100 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 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, a thickness of 200 μm or more is preferred, and a thickness of 200 to 400 μm is more preferred. 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 0.05 Pa or less, the ability to conform to irregularities can be more reliably ensured even if the irregularities on the adherend surface are 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. An acrylic adhesive is preferably used as the adhesive constituting the adhesive layer (5). In the present invention, the term "acrylic adhesive" refers to an adhesive containing a copolymer having a (meth)acrylic acid ester as a constituent component (hereinafter referred to as "(meth)acrylic acid ester copolymer") as the main polymer (adhesive base polymer). In addition to the (meth)acrylic acid ester copolymer, the adhesive may also contain a crosslinking agent, as described below. Here, "containing a (meth)acrylic acid ester copolymer as the main component" means that the content of the (meth)acrylic acid ester copolymer in the polymer or resin constituting the base resin of the adhesive is at least 50% by mass, 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 cures upon irradiation with radiation, or a non-radiation-curable adhesive that does not cure upon irradiation with radiation. Examples of the radiation-curable adhesive include the radiation-curable adhesives described in paragraphs

[0035] to

[0076] of International Publication No. 2018 / 181240 and the radiation-curable adhesives described in paragraphs

[0031] to

[0050] of JP-A No. 2022 / 109374.

[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 a structural unit 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 a (meth)acrylic acid ester monomer substituted with a functional group such as a hydroxyl group.

[0044] The non-radiation-curable pressure-sensitive 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 pressure-sensitive adhesive after application. The polyisocyanate compound is not particularly limited, and for example, the polyisocyanate compounds used in the aforementioned primer layer (3) can be used. Specific examples of commercially available products include Coronate L (product name, manufactured by Tosoh Corporation). Specific examples of commercially available melamine-formaldehyde resins include Nikalac MX-45 (manufactured by Sanwa Chemical Co., Ltd.) and Melan (product name, manufactured by Hitachi Chemical Co., Ltd.). Furthermore, examples of epoxy resins that can be used include TETRAD-X (product name, manufactured by Mitsubishi Chemical Corporation).

[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, a viscosity 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, preferably 5 to 150 μm. The semiconductor wafer surface protection tape (1) of the present invention can also be configured such that the resin layer A (3) contains an antistatic agent, resulting in a semiconductor wafer surface protection tape with antistatic properties. In this case, even when the pressure-sensitive adhesive layer (5) is made thicker than 100 μm, excellent antistatic properties can be exhibited in order to improve the ability of the semiconductor wafer surface protection tape (1) to embed irregularities into the wafer surface.

[0048] (Release Film) In the semiconductor wafer surface protection tape (1) of the present invention, a release film is optionally provided on the adhesive layer (5). The release film, also known as 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 necessary, 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 for Manufacturing the Semiconductor Wafer Surface Protection Tape of the Present Invention) The method for manufacturing the semiconductor wafer surface protection tape of the present invention is not particularly limited and can be produced by conventional methods. The base layer (2) and resin layer B (4) can be produced by conventional methods such as extrusion, inflation, and casting. Alternatively, an independently formed film can be bonded to another film with an adhesive or the like to form a multi-layer base layer (2) and a multi-layer resin layer B (4). The resin layer A (3) and 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 adhesive layer (5) (adhesive composition) to a release film or film-like base layer (2) or resin layer B (4) and drying the composition. The obtained resin layer A (3) and adhesive layer (5) can be laminated as layers constituting the semiconductor wafer surface protection tape of the present invention by laminating or transferring other layers in accordance with the laminate structure to be incorporated into the semiconductor wafer surface protection tape of the present invention. Examples of methods for manufacturing the semiconductor wafer surface protection tape of the present invention include the following methods. However, the method for producing the semiconductor wafer surface protection tape of the present invention is not limited to the following. After applying a resin layer A-forming composition to a film-like base layer (2) and drying it, a film-like resin layer B (4) is laminated to the layer obtained by applying and drying the resin layer A-forming composition, thereby obtaining an adhesive film 1. Separately from the adhesive film 1, a pressure-sensitive adhesive composition is applied to the release-treated surface of a release film and dried to produce an adhesive layer (5). The resulting adhesive layer (5) is then laminated to the surface of the resin layer B (4) of the adhesive film 1, and the adhesive layer (5) is transferred to obtain a semiconductor wafer surface protection tape. The release film used to prepare the adhesive layer (5) may remain attached to the semiconductor wafer surface protection tape. However, when using the semiconductor wafer surface protection tape of the present invention, the release film is peeled off from the adhesive layer (5) before use.

[0050] (Uses of the Tape for Protecting a Semiconductor Wafer Surface of the Present Invention) The tape for protecting a semiconductor wafer surface 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 singulated into chips by back-grinding, and can be suitably used in particular for semiconductor wafers with a large difference in unevenness, as it exhibits excellent unevenness-following ability.

[0051] [Method for Processing a Semiconductor Wafer] A method for processing a semiconductor wafer using the semiconductor wafer surface protection 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 (height of bumps (electrodes) or depth of scribe lines) of 20 μm or more, 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 conformability to unevenness 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, with regard to bumps, good conformability to unevenness can be exhibited for 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 bumps with 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, 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 backgrinding is not particularly limited, and may be, for example, 500 to 800 μm. Furthermore, the thickness of the semiconductor wafer after backgrinding using the semiconductor wafer surface protection tape (1) of the present invention can also be adjusted to a desired thickness, for example, 20 to 500 μm, preferably 50 to 250 μm, and more preferably 80 to 250 μm. By using the semiconductor wafer surface protection tape (1) of the present invention, warping 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 protective tape (1) of the present invention preferably includes a step of laminating the semiconductor wafer surface protective tape (1) of the present invention to a semiconductor wafer, and then irradiating the semiconductor wafer surface protective tape with radiation (preferably ultraviolet light) to peel off the semiconductor wafer surface protective tape.

[0057] For example, the semiconductor wafer surface protection tape (1) of the present invention is first laminated to the circuit pattern surface (surface) of a semiconductor wafer with the adhesive layer (5) facing the surface. Next, the side of the semiconductor wafer opposite the circuit pattern is ground until the semiconductor wafer reaches a predetermined thickness, for example, 10 to 200 μm. The semiconductor wafer surface protection tape is then placed on a heated suction table with the adhesive side facing down, and in this state, a dicing / die bonding film may be laminated to the ground surface side of the semiconductor wafer. After the dicing process, 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 then peeled off from the semiconductor wafer. When peeling off the semiconductor wafer surface protection tape (1), it is preferable that the adhesive layer (5) be cured by irradiation with radiation (preferably ultraviolet light) to reduce its adhesive strength.

[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] <Substrate Layer> (Film 1) A 50 μm thick polyethylene terephthalate (PET) film that had been corona-treated on one side was prepared as Film 1. (Film 2) A 50 μm thick polyethylene naphthalate (PEN) film that had been corona-treated on one side was prepared as Film 2. (Film 3) A 50 μm thick polypropylene (PP) film that had been corona-treated on one side was prepared as Film 3. (Film 4) A low-density polyethylene resin (LDPE) with a melting point of 105°C was extruded to a thickness of 100 μm to form a film, and one side of the resulting film was corona-treated to obtain Film 4.

[0060] <Composition for forming resin layer A> (Preparation of resin composition A1) 0.7 parts by mass of Coronate L (trade name, manufactured by Tosoh Corporation) was added 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 mixed to obtain resin composition A1. (Preparation of resin composition A2) 1.0 part by mass of Coronate L (trade name, manufactured by Tosoh Corporation) was added 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 mixed to obtain resin composition A2. (Preparation of resin composition A3) 0.3 parts by mass of Coronate L (trade name, manufactured by Tosoh Corporation) was added 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 mixed to obtain resin composition A3. (Preparation of Resin Composition A4) 0.5 parts by mass of Coronate L (product name, manufactured by Tosoh Corporation) was added to 100 parts by mass of a polyester-based adhesive (manufactured by Mitsubishi Chemical Corporation, product name: Nichigo Polyester LP-011S50EO) and mixed to obtain resin composition A4. (Preparation of Resin Composition A5) 0.15 parts by mass of Coronate L (product name, manufactured by Tosoh Corporation) was added 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 mixed to obtain resin composition A5. (Preparation of Resin Composition A6) 1.5 parts by mass of Coronate L (product name, manufactured by Tosoh Corporation) was added 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 mixed to obtain resin composition A6.

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

[0062] <Adhesive Composition> 1.0 part by mass of Coronate L (trade name, manufactured by Tosoh Corporation) was added to and mixed with 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 to obtain a pressure-sensitive adhesive composition.

[0063] <Preparation of Semiconductor Wafer Surface Protection Tape> (Example 1) Resin composition A1 was applied to the corona-treated surface of film 1 as a base layer so that the film thickness after drying would be 30 μm, and then dried. Immediately after drying, film B1 as resin layer B was laminated to obtain laminated film 1. Separately from the laminated 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 then dried to obtain a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer was then transferred by laminating it to the surface of resin layer B of the laminated film 1, thereby obtaining the semiconductor wafer surface protection tape of Example 1. The semiconductor wafer surface protection tape (1) of Example 1 obtained in this manner has a structure in which, as shown in FIG. 1, 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).

[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 prepared in the same manner as in the preparation of the semiconductor wafer surface protection tape of Example 1, except that the configuration of at least one of the base material 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 the base material layer (2), resin layer A (3), resin layer B (4), and 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). The semiconductor wafer surface protection tapes of Comparative Examples 1 to 4 have a structure in which the base material layer (2), resin layer A (3), resin layer B (4), and adhesive layer (5) are laminated in this order, and a release film is further laminated on the adhesive layer (5).

[0065] Comparative Example 5: The ethylene-vinyl acetate copolymer (EVA) used in preparing film B1 was extruded to a thickness of 350 μm onto the corona-treated surface of film 1 serving as a base layer to form resin layer B, and the surface of the resin layer B side was subjected to corona treatment to obtain adhesive film 2. Separately from the 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 a release treatment on one side so that the film thickness after drying would be 10 μm, and the composition was dried to obtain an adhesive layer. The adhesive layer was then transferred by bonding it to the surface of resin layer B of adhesive film 2, thereby obtaining the semiconductor wafer surface protection tape of Comparative Example 5. The semiconductor wafer surface protection tape of Comparative Example 5 obtained in this manner had a structure in which a base layer (2), resin layer B (4), and adhesive layer (5) were laminated in this order, with a release film further laminated on the adhesive layer (5).

[0066] [1. Evaluation method for warpage prevention performance] A semiconductor wafer surface protection tape was bonded 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, followed by circle cutting. Thereafter, the surface of the bare wafer opposite to the tape-bonded surface was ground using a grinder / polisher (manufactured by Disco Corporation, product name: DGP8760) until the thickness of the bare wafer was 200 μm, and the resulting ground bare wafer with the semiconductor wafer surface protection tape was stored under conditions of 23°C and 50% humidity. The bare wafer with the semiconductor wafer surface protection tape 24 hours after grinding (storage) 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. The measurement was performed by setting the surface plate as the zero point, obtaining 17 measurement points at equal intervals around the circumference of the wafer, and measuring the warpage (distance) from the zero point to the measurement points using a long length. The maximum value of the measured warpage was used to evaluate the warpage prevention performance based on the following criteria. - Warpage prevention performance - ◎: Maximum warpage≦3.0 mm ○: 3.0 mm<maximum warpage<8.0 mm ×: Maximum warpage≧8.0 mm

[0067] [2. Evaluation method for conformability to irregularities] 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 on its surface at 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 circle cutting was then performed. The thickness of a semiconductor wafer to which the semiconductor wafer surface protection tape was applied 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 dial gauge's measuring probe facing the semiconductor wafer surface protection tape. 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, which is the portion that did not have bumps, was measured as β. Insufficient conformability results in a large α due to the formation of a gap between the semiconductor wafer surface protection tape and the semiconductor wafer. A measurement that satisfied α-β≦60 μm was evaluated as having good conformability and marked with a "good"; a measurement that satisfied 60 μm<α-β≦85 μm was evaluated as having good conformability and marked with a "good"; and a measurement that satisfied 85 μm<α-β was evaluated as an "unsatisfactory";

[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 a circle cut was performed. The same blade was used without cleaning, and the above operation was repeated 10 times. After that, the blade was visually observed, and the absence of contamination was evaluated as good blade contamination suppression, with a rating of "◯", and the presence of contamination was evaluated as "×".

[0069] (Melting Point of Base Material Layer) The melting point of the base material 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) Method for measuring transition temperature of plastics.

[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. That is, a measurement sample having a thickness of 1000 μm was prepared using the resin constituting each resin layer, and the temperature was raised from 0 ° C. to 100 ° C. at a heating rate of 10 ° C. / min while applying a shear strain of 1 Hz frequency, and 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. In the table, the storage modulus at 23 ° C. is simply referred to as "elastic modulus at 23 ° C.," and the storage modulus at 70 ° C. is simply referred to as "elastic modulus at 70 ° C.," respectively.

[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]

[0073]

[0074] The films listed in the columns for resin layer B and base 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: olefin-based thermoplastic elastomer (Base 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 semiconductor wafer surface protection tape of Comparative Example 1, the storage modulus of the resin layer A at 23° C. was 9.6×10 ２The semiconductor wafer surface protective tape of Comparative Example 1 had a blade contamination. The semiconductor wafer surface protective tape of Comparative Example 2 had a storage modulus of 1.5 × 10 at 23°C of resin layer A. ５ The semiconductor wafer surface protective tape of Comparative Example 2 was not a semiconductor wafer surface protective tape of the present invention in that the surface tension (Pa) was greater than the specified value of the present invention. The semiconductor wafer surface protective tape of Comparative Example 2 was not able to sufficiently prevent warping. The semiconductor wafer surface protective tape of Comparative Example 3 was not a semiconductor wafer surface protective tape of the present invention in that the thickness of the resin layer A was 1 μm, which was thinner than the specified value of the present invention. The semiconductor wafer surface protective tape of Comparative Example 3 was not a semiconductor wafer surface protective tape of the present invention in that the thickness of the resin layer A was 60 μm, which was thicker than the specified value of the present invention. The semiconductor wafer surface protective tape of Comparative Example 4 ... suffered from blade contamination. The semiconductor wafer surface protective tape of Comparative Example 5 was not a semiconductor wafer surface protective tape of the present invention in that it did not have the resin layer A between the resin layer B and the base layer. The semiconductor wafer surface protective tape of Comparative Example 5 was not a semiconductor wafer surface protective tape of the present invention in that it did not have the resin layer A between the resin layer B and the base layer. The semiconductor wafer surface protective tape of Comparative Example 5 was not a semiconductor wafer surface protective tape of the present invention in that it did not have the resin layer A between the resin layer B and the base layer. 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.

[0076] While the present invention has been described in connection with embodiments thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be construed broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0077] This application claims priority based on Japanese Patent Application No. 2024-054432, filed on March 28, 2024, the contents of which are incorporated herein by reference as part of the present specification.

[0078] REFERENCE SIGNS LIST 1 Semiconductor wafer surface protection tape 2 Base layer 3 Resin layer A 4 Resin layer B 5 Pressure-sensitive adhesive layer

Claims

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

2. The semiconductor wafer surface protection tape 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 3. The semiconductor wafer surface protecting tape according to claim 1, wherein the surface tension is 0.05 Pa or less.

4. The semiconductor wafer surface protection tape according to any one of claims 1 to 3, wherein the resin layer A is a layer containing an acrylic adhesive or a polyester adhesive.

5. The semiconductor wafer surface protection tape according to any one of claims 1 to 4, wherein the resin layer A contains an antistatic agent, and the antistatic agent is an ionic liquid.

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