Liquid surface protective material for semiconductor wafer processing, protective film formed from the liquid surface protective material for semiconductor wafer processing, and method for processing a semiconductor wafer.

Abstract

To provide a liquid surface protection material for semiconductor wafer processing that has superior embedding properties for a semiconductor wafer surface, and can prevent an adhesive from being left on the semiconductor wafer surface (a residue from sticking on a surface protection member) after peeling.SOLUTION: A liquid surface protection material for semiconductor wafer processing includes acrylic emulsion resin. A protection film is formed of the liquid surface protection material for semiconductor wafer processing. A processing method for semiconductor wafer includes: applying the liquid surface protection material for semiconductor wafer processing on the surface of a semiconductor wafer where a circuit pattern is formed to form the protection film; grinding a surface of the semiconductor wafer where the protection film is not formed; and peeling the protection film away.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid surface protective material for semiconductor wafer processing, a protective film formed from the liquid surface protective material for semiconductor wafer processing, and a method for processing semiconductor wafers. [Background technology]

[0002] Semiconductor wafers are subjected to processing processes such as backgrinding with the circuit-formed surface protected by a protective material. Adhesive tape is a typical protective material for semiconductor wafers (for example, Patent Document 1). In recent years, the circuit surfaces of semiconductor wafers have become more complex, and adhesive tape may not be able to adequately fill in the irregularities of the circuit surface. If the filling is insufficient, water may penetrate between the adhesive layer of the adhesive tape and the surface of the semiconductor wafer, potentially causing chip breakage and cracking. In addition, foreign matter may adhere to the areas where the filling is insufficient.

[0003] As a method for protecting the circuit surface of semiconductor wafers other than adhesive tape, a method has been proposed in which a liquid composition is applied to form a protective film (for example, Patent Documents 2-6). However, after removal of the protective film formed by these methods, residue may adhere to the circuit surface, potentially causing contamination of the circuit surface by the protective film. Furthermore, the removal process may require the use of solvents, which can increase the environmental burden. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-185641 [Patent Document 2] Japanese Patent Application Publication No. 10-120965 [Patent Document 3] Japanese Patent Publication No. 2000-315668 [Patent Document 4] Japanese Patent Publication No. 2014-212179 [Patent Document 5] Japanese Patent Publication No. 2011-23272 [Patent Document 6] Japanese Patent Publication No. 2014-19889 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention was made to solve the above-mentioned conventional problems, and its objective is to provide a liquid surface protective material for semiconductor wafer processing that has excellent embedding properties on the semiconductor wafer surface and can suppress adhesive residue (adhesion of residue of surface protective material) on the semiconductor wafer surface after peeling. [Means for solving the problem]

[0006] 1. The liquid surface protective material for semiconductor wafer processing according to the embodiment of the present invention contains an acrylic emulsion resin. 2. In the liquid surface protective material for semiconductor wafer processing described in item 1 above, the acid value of the acrylic emulsion resin may be 10 mg / KOH or less. 3. In the liquid surface protective material for semiconductor wafer processing described in 1 or 2 above, the SP value of the acrylic emulsion resin is 9 (cal / cm²). 3 ) 1 / 2 ~11 (cal / cm 3 ) 1 / 2 That's fine. 4. In the liquid surface protective material for semiconductor wafer processing described in any of items 1 to 3 above, the BH viscosity may be 0.1 Pa·s to 10 Pa·s. 5. In another aspect of the embodiment of the present invention, a protective film is provided. This protective film is formed using the liquid surface protective material for semiconductor wafer processing described in any of 1 to 4 above. 6. In the protective film described in item 5 above, the tensile modulus at 23°C may be 0.1 GPa to 1.1 GPa. 7. In the protective film described in item 5 or 6 above, the adhesive strength to the silicon wafer may be 1.0 N / 25 mm or less. 8. In yet another aspect of the embodiments of the present invention, a method for processing a semiconductor wafer is provided. This method for processing a semiconductor wafer includes applying a liquid surface protective material for semiconductor wafer processing described in any of 1 to 4 above to a surface on which a circuit pattern is formed on a semiconductor wafer to form a protective film, grinding the surface on which the protective film is not formed on the semiconductor wafer, and peeling off the protective film. [Effects of the Invention]

[0007] According to embodiments of the present invention, a liquid surface protective material for semiconductor wafer processing is provided that exhibits excellent embedding properties on the semiconductor wafer surface (more specifically, the circuit surface) and can suppress adhesive residue (adhesion of residue of the surface protective member) on the semiconductor wafer surface after the protective film has been peeled off. Furthermore, the protective film formed using the liquid surface protective material for semiconductor wafer processing according to embodiments of the present invention can be peeled off and does not require a solvent removal process. Therefore, the environmental burden due to the use of solvents can be reduced. In addition, adhesive residue (adhesion of residue of the surface protective member) on the semiconductor wafer surface after peeling can also be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view of a semiconductor wafer and a protective film in a semiconductor wafer processing step according to an embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view of a semiconductor wafer and a protective film in a semiconductor wafer processing step according to another embodiment of the present invention. [Figure 3] This is a schematic cross-sectional view of a semiconductor wafer and a protective film in a semiconductor wafer processing step according to yet another embodiment of the present invention. [Modes for carrying out the invention]

[0009] A. Liquid surface protective material for semiconductor wafer processing A liquid surface protective material for semiconductor wafer processing (hereinafter also referred to as liquid surface protective material) according to an embodiment of the present invention contains an acrylic emulsion resin. The liquid surface protective material according to an embodiment of the present invention is used, for example, by being applied to a circuit surface of a semiconductor wafer. The shape of the circuit surface of a semiconductor wafer has become more complex, and in order to appropriately protect the circuit surface in the processing step of a semiconductor wafer, a surface protective material with more excellent embedding property is required. Since the surface protective material according to an embodiment of the present invention is liquid, it can be excellent in embedding property on the surface (more specifically, the circuit surface) of a semiconductor wafer even when the circuit surface of the semiconductor wafer has a complex shape. In addition, the protective film formed by the liquid surface protective material according to an embodiment of the present invention can be easily removed by peeling. Therefore, a dissolution and removal step using a solvent is not required, and the environmental load caused by the solvent can be reduced. Furthermore, adhesive residue (adhesion of residues of the surface protective member) on the surface of the semiconductor wafer can also be suppressed.

[0010] The BH viscosity of the liquid surface protective material according to an embodiment of the present invention is preferably 0.1 Pa·s to 10 Pa·s, more preferably 0.2 Pa·s to 5 Pa·s, still more preferably 0.3 Pa·s to 3 Pa·s, and particularly preferably 0.5 Pa·s to 2 Pa·s. When the BH viscosity is within the above range, the liquid surface protective material can be favorably applied to the surface of a semiconductor wafer. The BH viscosity can be adjusted to any appropriate value according to the application method. In the present specification, BH viscosity refers to a viscosity measured with a BH viscometer under conditions of 30°C and 2 rpm. Any appropriate rotor can be used for measurement depending on the viscosity, for example, a No. 2 rotor can be used.

[0011] A-1. Acrylic emulsion resin As the acrylic emulsion resin, a resin obtained by emulsion polymerization of any appropriate monomer component can be used. As described above, the liquid surface protective material according to the embodiment of the present invention includes an acrylic emulsion resin. The liquid surface protective material containing an acrylic emulsion resin forms a protective film on the surface of a semiconductor wafer by being dried after application. This protective film appropriately protects the surface of the semiconductor wafer during the processing step of the semiconductor wafer, and can be peeled and removed without being dissolved using a solvent after use. Furthermore, adhesive residue (adhesion of residues of the surface protective member) on the surface of the semiconductor wafer after peeling can also be suppressed. Acrylic emulsions have a wide variety of monomers, and by selecting the type of monomers to be copolymerized, a liquid surface protective material capable of forming a protective film having appropriate physical properties can be obtained.

[0012] The acid value of the acrylic emulsion resin is preferably 10 mg KOH / g or less, more preferably 0 mg KOH / g to 8 mg KOH / g, still more preferably 0 mg KOH / g to 5 mg KOH / g, and particularly preferably 0 mg KOH / g to 3 mg KOH / g. When the acid value of the acrylic emulsion resin falls within the above range, the peeling workability of the protective film formed by the liquid surface protective material (for example, suppression of tearing and chipping of the protective film during peeling) is improved, and the protective film can be easily peeled from the surface of the semiconductor wafer. In the present specification, the acid value of an acrylic emulsion resin refers to a value measured in accordance with the potentiometric titration method specified in JIS K0070:1992.

[0013] The SP value of the acrylic emulsion resin is preferably 9 (cal / cm 3 ) 1 / 2 to 11 (cal / cm 3 ) 1 / 2 , more preferably 9 (cal / cm 3 ) 1 / 2 to 10.8 (cal / cm 3 ) 1 / 2 , and still more preferably 9 (cal / cm 3 ) 1 / 2 to 10.5 (cal / cm 3 ) 1 / 2If the SP value is within the above range, it is possible to suppress the occurrence of peeling defects due to excessive adhesion of the protective film formed by the liquid surface protective material to the semiconductor wafer surface, and the adhesion of residue of the surface protective material to the semiconductor wafer surface. In this specification, the SP value refers to the value of the solubility parameter calculated from the basic structure of the compound using the method proposed by Fedors.

[0014] The glass transition temperature (Tg) of the acrylic emulsion resin can be set to any appropriate value. Preferably, the glass transition temperature of the acrylic emulsion resin is -30°C to 30°C, more preferably -25°C to 25°C, and even more preferably -20°C to 20°C. If the Tg of the acrylic emulsion resin is within the above range, the adhesion of the protective film formed by the liquid surface protective material to the semiconductor wafer is improved, providing a liquid surface protective material with superior embedding properties. In this specification, the glass transition temperature of the acrylic emulsion resin refers to the theoretical value calculated by Fox's formula from the monomer units and their proportions that constitute each resin (polymer). The theoretical glass transition temperature obtained from Fox's formula may coincide with the measured glass transition temperature obtained by methods such as differential scanning calorimetry (DSC) or dynamic viscoelasticity measurement. If a theoretical value cannot be calculated, the measured glass transition temperature can be used.

[0015] Fox's equation, as shown below, is a relationship between the Tg of an acrylic polymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the acrylic polymer. 1 / Tg = Σ(Wi / Tgi) (In the formula, Tg represents the glass transition temperature of the acrylic polymer (unit: K), Wi represents the weight fraction of monomer i in the acrylic polymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the monomer i homopolymer (unit: K)).

[0016] The glass transition temperature of the homopolymer used to calculate Tg can be any value found in any appropriate source. For example, for the monomers listed below, the following values ​​are used as the glass transition temperatures of the homopolymers of those monomers. n-butyl acrylate -55℃ Acrylonitrile 97℃ Methyl methacrylate 105℃ Acrylic acid 106℃ Vinyl acetate 32℃

[0017] For the glass transition temperatures of monomer homopolymers other than those exemplified above, you can use the values ​​listed in, for example, the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989). If multiple values ​​are listed, use the highest value.

[0018] For monomers whose homopolymer glass transition temperature is not listed in the Polymer Handbook, the value obtained by the measurement method described in Japanese Patent Publication No. 2007-51271 (measured glass transition temperature) can be used. Specifically, 100 parts by weight of monomer, 0.2 parts by weight of azobisisobutyronitrile, and 200 parts by weight of ethyl acetate as a polymerization solvent are added to a reactor equipped with a thermometer, stirrer, nitrogen inlet tube, and reflux condenser, and the mixture is stirred for 1 hour while circulating nitrogen gas. After removing oxygen from the polymerization system in this way, the temperature is raised to 63°C and the reaction is carried out for 10 hours. Then, it is cooled to room temperature to obtain a homopolymer solution with a solid content of 33% by weight. Next, this homopolymer solution is cast onto a release liner and dried to produce a test sample (sheet-like homopolymer) with a thickness of approximately 2 mm. This test sample is punched out into a 7.9 mm diameter disc shape, sandwiched between parallel plates, and measured using a viscoelasticity tester (ARES, Rheometrics) in shear mode while applying a shear strain at a frequency of 1 Hz, within a temperature range of -70°C to 150°C and a heating rate of 5°C / min. The peak top temperature of tanδ is defined as the Tg of the homopolymer.

[0019] A-1-1. Monomer composition As described above, acrylic emulsion resins are obtained by emulsion polymerization of any suitable monomer composition. The monomer composition comprises (meth)acrylic monomers and / or any suitable monomer copolymerizable with (meth)acrylic monomers. The monomer component may consist of only one monomer or a combination of two or more monomers. In this specification, (meth)acrylic means acrylic and / or methacrylic.

[0020] Typically, the monomer composition preferably contains a (meth)acryloyl group-containing monomer. The (meth)acryloyl group-containing monomer may be used alone or in combination of two or more types. The content of the (meth)acryloyl group-containing monomer is preferably 40 parts by weight or more, more preferably 60 parts by weight or more, even more preferably 65 parts by weight or more, and particularly preferably 70 parts by weight or more, out of 100 parts by weight of the total monomer components. The (meth)acryloyl group-containing monomer is, for example, 95 parts by weight or less out of 100 parts by weight of the total monomer components. If the content of the (meth)acryloyl group-containing monomer is within the above range, the protective film formed by the liquid surface protective material can be peeled off, and furthermore, adhesive residue (adhesion of residue of the surface protective member) on the semiconductor wafer surface can also be suppressed.

[0021] Any suitable (meth)acryloyl group-containing monomer can be used as the (meth)acryloyl group-containing monomer. Preferably, alkyl (meth)acrylate is used as the (meth)acryloyl group-containing monomer. By adjusting the type and / or content ratio of the alkyl (meth)acrylate used, the storage modulus of the liquid surface protective material, the SP value of the acrylic emulsion resin, and the tensile properties of the formed protective film can be adjusted to any suitable value. Alkyl (meth)acrylate may be used alone or in combination of two or more types.

[0022] Any suitable alkyl (meth)acrylate can be used as the alkyl (meth)acrylate. Specifically, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, (meth) Examples include alkyl (meth)acrylates having an alkyl group with 1 to 20 carbon atoms, such as decyl acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate (hereinafter also referred to as C1-C20 alkyl (meth)acrylates).

[0023] The monomer composition preferably contains alkyl (meth)acrylates having C4 to C20 alkyl groups (C4 to C20 alkyl (meth)acrylates), more preferably alkyl (meth)acrylates having C4 to C14 alkyl groups, and even more preferably alkyl (meth)acrylates having C4 to C9 alkyl groups. Using these alkyl (meth)acrylates makes it easy to peel off protective films formed using liquid surface protective materials. Furthermore, it can also suppress adhesive residue (adhesion of residue of surface protective material) on the semiconductor wafer surface after peeling. Specifically, the monomer composition preferably contains n-butyl acrylate (BA) and / or 2-ethylhexyl acrylate (2EHA), more preferably BA. Only one type of C4 to C20 alkyl (meth)acrylate may be used, or two or more types may be used in combination.

[0024] In the monomer composition, C4-C20 alkyl (meth)acrylates can be used in any appropriate proportion. The content of C4-C20 alkyl (meth)acrylates is preferably 40 parts by weight or more, more preferably 60 parts by weight or more, and even more preferably 65 parts by weight or more, out of 100 parts by weight of the total monomer components. If the content of C4-C20 alkyl (meth)acrylates is within the above range, the protective film formed using the liquid surface protective material can be easily peeled off. In addition, the adhesive force to the semiconductor wafer surface can be adjusted to an appropriate value, and damage to the semiconductor wafer surface during peeling can be suppressed.

[0025] The monomer composition preferably further comprises nitrogen atom-containing monomers. Any suitable nitrogen atom-containing monomer can be used as the nitrogen atom-containing monomer. Specifically, cyano group-containing monomers such as acrylonitrile, methacrylonitrile, and 2-cyanoethyl (meth)acrylate; amide group-containing monomers such as (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and diacetone (meth)acrylamide; aminoethyl (meth)acrylate, N,N Examples include amino group-containing monomers such as dimethylaminoethyl (meth)acrylate and t-butylaminoethyl (meth)acrylate; and monomers having nitrogen atom-containing rings such as N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, and N-(meth)acryloylmorpholine. The nitrogen atom-containing monomer is preferably a cyano group-containing monomer, and more preferably acrylonitrile. By using an acrylic emulsion resin obtained using a monomer composition containing these nitrogen atom-containing monomers, protective films formed using liquid surface protective materials can be easily peeled off, and damage to the semiconductor wafer surface can be suppressed. In addition, the Tg and SP values ​​of the obtained acrylic emulsion resin can be well adjusted to any desired value. Nitrogen atom-containing monomers may be used individually or in combination of two or more types.

[0026] In the monomer composition, nitrogen atom-containing monomers can be used in any appropriate proportion. The nitrogen atom-containing monomer is preferably 10 parts by weight or more, more preferably 15 parts by weight or more, even more preferably 20 parts by weight or more, and particularly preferably 25 parts by weight or more, out of 100 parts by weight of the total monomer components. If the content of nitrogen atom-containing monomers is within the above range, the protective film formed using the liquid surface protective material can be easily peeled off. Furthermore, adhesive residue (adhesion of residue of the surface protective member) on the semiconductor wafer surface after peeling can also be reduced. The content of nitrogen atom-containing monomers is preferably 50 parts by weight or less out of 100 parts by weight of the total monomer components.

[0027] The monomer composition further preferably comprises an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms (C1 to C3 alkyl (meth)acrylate). Using a monomer composition further comprising these alkyl (meth)acrylates allows for easy removal of protective films formed using liquid surface protective materials, thereby suppressing damage to the semiconductor wafer surface. Preferably, methyl methacrylate (MMA) and ethyl methacrylate are used as the C1 to C3 alkyl (meth)acrylate. Only one type of C1 to C3 alkyl (meth)acrylate may be used, or two or more types may be used in combination.

[0028] In the monomer composition, C1-C3 alkyl (meth)acrylates can be used in any appropriate proportion. The content of C1-C3 alkyl (meth)acrylates is preferably 6 parts by weight or more, more preferably 8 parts by weight or more, even more preferably 10 parts by weight or more, and particularly preferably 15 parts by weight or more, out of 100 parts by weight of the total monomer components. If the content of C1-C3 alkyl (meth)acrylates is within the above range, the protective film formed using the liquid surface protective material can be easily peeled off, and damage to the semiconductor wafer surface during peeling can be suppressed. The content of C1-C3 alkyl (meth)acrylates is, for example, 50 parts by weight or less out of 100 parts by weight of the total monomer components.

[0029] The monomer composition may further contain any other suitable monomer components. Examples of other monomer compositions include, specifically, carboxyl group-containing monomers such as acrylic acid (AA), methacrylic acid (MAA), carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and hydroxyl group (OH group)-containing monomers such as polypropylene glycol mono(meth)acrylate; and anhydrous magnesium Examples of functional group-containing monomers include: acid anhydride group-containing monomers such as leic acid and itaconic anhydride; epoxy group-containing monomers such as glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether; keto group-containing monomers such as diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetacetate, and vinyl acetacetate; and alkoxysilyl group-containing monomers such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane. When functional group-containing monomers are further included, the cohesive force of the acrylic emulsion resin can be increased. Furthermore, the tensile properties of the formed protective film and the SP value of the acrylic emulsion resin can be adjusted to any appropriate value.

[0030] The monomer composition may further contain other copolymer components other than the monomers mentioned above for purposes such as improving cohesiveness. Examples of other copolymer components include vinyl ester monomers such as vinyl acetate (VAc), vinyl propionate, and vinyl laurate; aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), and vinyltoluene; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, and isobornyl (meth)acrylate; and aromatic rings such as aryl (meth)acrylate (e.g., phenyl (meth)acrylate), aryloxyalkyl (meth)acrylate (e.g., phenoxyethyl (meth)acrylate), and arylalkyl (meth)acrylate (e.g., benzyl (meth)acrylate). Examples include (meth)acrylate-containing monomers; olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine atom-containing monomers such as vinyl chloride and vinylidene chloride; alkoxy group-containing monomers such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and ethyl carbitol (meth)acrylate; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether; and polyfunctional monomers having two or more (e.g., three or more) polymerizable functional groups (e.g., (meth)acryloyl groups) in one molecule, such as 1,6-hexanediol di(meth)acrylate and trimethylolpropane tri(meth)acrylate.

[0031] The above-mentioned other monomer components and other copolymer components are used in any appropriate proportion. For example, in a monomer composition, the total amount of the above-mentioned C4-C20 alkyl (meth)acrylate, nitrogen atom-containing monomer, and C1-C3 alkyl (meth)acrylate is 100 parts by weight.

[0032] A-1-2. Synthesis of acrylic emulsion resins Acrylic emulsion resins are obtained by emulsion polymerization of the above monomer composition. The monomer supply method in emulsion polymerization may be a batch supply method in which all monomer raw materials are supplied at once, a continuous supply (dropping) method, or a divided supply (dropping) method. Alternatively, some or all of the monomer components may be mixed with water and an emulsifier in advance to create an emulsion, and the resulting emulsion may be supplied to the polymerization vessel.

[0033] The polymerization temperature can be set to any appropriate value depending on the type of monomer and solvent used, the type of polymerization initiator, etc. For example, the polymerization temperature is 20°C or higher, preferably 40°C or higher, and more preferably 50°C or higher. Alternatively, the polymerization temperature is preferably 95°C or lower, and more preferably 85°C or lower.

[0034] Any suitable initiator can be used as a polymerization initiator. Examples include azo polymerization initiators, peroxide initiators, redox initiators using a combination of peroxide and reducing agent, and substituted ethane initiators. Specifically, these include 2,2'-azobisisobutyronitrile, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, and 2,2'-azobis(N, Azo initiators such as N'-dimethylene isobutylamidine) dihydrochloride; persulfates such as potassium persulfate and ammonium persulfate; benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, di-n-octanoyl peroxide, di(4-methylbenzoyl) peroxide, t-butyl peroxybenzoate, t-butyl peroxyisobutyrate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di(2-ethylhexyl) peroxydicarbonate, di(4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, t-butyl peroxyneodecanoate, 1,1,3, Examples of peroxide initiators include 3-tetramethylbutylperoxy-2-ethylhexanoate, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclododecane, 1,1-bis(t-hexylperoxy)cyclohexane, and hydrogen peroxide; and redox initiators such as combinations of peroxides with ascorbic acid (e.g., hydrogen peroxide solution and ascorbic acid), combinations of peroxides with iron(II) salts (e.g., hydrogen peroxide solution and iron(II) salt), and combinations of persulfates with sodium bisulfite.

[0035] The polymerization initiator is used in any appropriate amount. For example, it is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 3 parts by weight, and even more preferably 0.01 to 2 parts by weight, per 100 parts by weight of the total monomer components.

[0036] Emulsion polymerization is usually carried out in the presence of an emulsifier. Any suitable emulsifier can be used. Anionic emulsifiers, nonionic emulsifiers, etc., can be used. One type of emulsifier may be used alone, or two or more types may be used in combination.

[0037] Examples of anionic emulsifiers include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, and sodium polyoxyethylene alkyl sulfosuccinate. Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene polyoxypropylene block polymers. In addition, emulsifiers having reactive functional groups (reactive emulsifiers) may be used as emulsifiers. Examples of reactive emulsifiers include radical polymerizable emulsifiers, which have a structure in which radical polymerizable functional groups such as propenyl groups and allyl ether groups are introduced into the above-mentioned anionic or nonionic emulsifiers.

[0038] The emulsifier is used in any appropriate amount. Preferably, the amount of emulsifier is 0.2 parts by weight or more, more preferably 0.5 parts by weight or more, even more preferably 1.0 part by weight or more, and particularly preferably 1.5 parts by weight or more, based on 100 parts by weight of the total monomer components. From the viewpoint of suppressing foaming during emulsion polymerization and in the composition containing the obtained emulsion, the amount of emulsifier used is usually preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and even more preferably 3 parts by weight or less, based on 100 parts by weight of the total monomer components.

[0039] Emulsion polymerization may be carried out in the presence of a protective colloid. Examples of protective colloids include polyvinyl alcohol-based polymers such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and modified polyvinyl alcohol; cellulose derivatives such as hydroxyethylcellulose, hydroxypropylcellulose, and carboxymethylcellulose salts; and natural polysaccharides such as guar gum. One type of protective colloid may be used alone, or two or more types may be used in combination.

[0040] The degree of saponification of partially saponified polyvinyl alcohol is, for example, less than 95 mol%, preferably less than 92 mol%, and more preferably less than 90 mol%. From the viewpoint of emulsion stability, the degree of saponification of partially saponified polyvinyl alcohol is preferably 65 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 85 mol% or more. As described above, fully saponified polyvinyl alcohol may also be used.

[0041] Examples of modified polyvinyl alcohols include anionic modified polyvinyl alcohol, in which anionic groups such as carboxyl groups and / or sulfonic acid groups are introduced; and cationic modified polyvinyl alcohol, in which cationic groups such as quaternary ammonium salts are introduced. The degree of saponification of the modified polyvinyl alcohol is, for example, less than 98 mol%, preferably less than 95 mol%, more preferably less than 92 mol%, and even more preferably less than 90 mol%. Furthermore, the degree of saponification of the modified polyvinyl alcohol is, for example, 55 mol% or more, preferably 65 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 85 mol% or more, from the viewpoint of emulsion stability, etc.

[0042] The protective colloid is used in any appropriate amount. The protective colloid content is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, and even more preferably 0.7 parts by weight or more, per 100 parts by weight of the total monomer components. Alternatively, the protective colloid content is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, even more preferably 3 parts by weight or less, and particularly preferably 2 parts by weight or less, per 100 parts by weight of the total monomer components. The protective colloid may be used in combination with the emulsifier, or it may be used alone without the emulsifier. Preferably, the emulsifier and protective colloid are used in combination. For example, emulsion polymerization can be carried out by placing water and protective colloid in a polymerization container, and supplying an emulsion to the polymerization container, which is obtained by pre-mixing part or all of the monomer composition with water and the emulsifier. Furthermore, when using an anionic protective colloid (e.g., anionic modified polyvinyl alcohol) in combination with an emulsifier, it is preferable to use at least one emulsifier selected from the group consisting of anionic emulsifiers and nonionic emulsifiers, from the viewpoint of polymerization stability and other factors.

[0043] Furthermore, any suitable chain transfer agent may be used during polymerization. Examples of chain transfer agents include mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, and thioglycolic acid. Chain transfer agents that do not contain sulfur atoms (non-sulfur chain transfer agents) may also be used. Specific examples of non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as α-pinene and terpinolene; styrenes such as α-methylstyrene and α-methylstyrene dimer; compounds having a benzylidenyl group such as dibenzylideneacetone, cinnamyl alcohol, and cinnamyl aldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; olefins such as 2,3-dimethyl-2-butene and 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; and benzyl hydrogens such as diphenylbenzene and triphenylbenzene. The chain transfer agent may be used alone or in combination of two or more types. When a chain transfer agent is used, its content is, for example, 0.01 parts by weight to 1 part by weight per 100 parts by weight of the total monomer components.

[0044] A-2. Additives Liquid surface protectants for semiconductor wafer processing may further contain any suitable additives as needed. Examples of additives include catalysts (e.g., platinum catalysts), tackifiers, plasticizers, pigments, dyes, fillers, antioxidants, conductive agents, UV absorbers, light stabilizers, release modifiers, softeners, flame retardants, solvents, leveling agents, film-forming aids, thickeners, thixotropes, and defoamers. Additives are used in any appropriate amount depending on the purpose.

[0045] A-3. Method for manufacturing liquid surface protective material for semiconductor wafer processing Liquid surface protective materials for semiconductor wafer processing can be manufactured by any suitable method. For example, an acrylic emulsion resin and any additive may be added to any suitable solvent and mixed, or an additive may be added to a solution obtained by emulsion polymerization of the acrylic emulsion resin and mixed. Alternatively, the acrylic emulsion resin may be used as is. Furthermore, the acrylic emulsion resin may be adjusted to a pH of about 6-8 by adding, for example, aqueous ammonia, or a liquid surface protective material may be used after adjusting the resin concentration by adding any suitable solvent.

[0046] Any suitable solvent can be used as the solvent. Preferably, an aqueous solvent is used. In this specification, an aqueous solvent means water or a mixed solvent having water as the main component (a component containing more than 50% by weight). As the solvent other than water that constitutes this mixed solvent, an organic solvent that can be homogeneously mixed with water can be used. Specifically, examples include lower alcohols. Only one organic solvent that can be homogeneously mixed with water may be used, or two or more may be used in combination. The aqueous solvent has a water content of, for example, 90% by weight or more, preferably 95% to 100% by weight.

[0047] B.Protective film The protective film in the embodiment of the present invention is formed using the liquid surface protective material for semiconductor wafer processing described in Section A above. The protective film is formed, for example, by applying the liquid surface protective material to the surface of a semiconductor wafer by any suitable method and then drying it.

[0048] The thickness of the protective film is set to any appropriate value. For example, the thickness can be set to match the height of the protrusions on the surface of the semiconductor wafer on which the protective film is formed. The thickness of the protective film is, for example, 50 μm to 500 μm, preferably 100 μm to 300 μm, and more preferably 100 μm to 200 μm. If the thickness of the protective film is within the above range, the semiconductor wafer surface (e.g., the circuit surface) can be adequately protected during the semiconductor wafer processing process. Furthermore, after processing the semiconductor wafer, the protective film can be easily peeled off without breaking.

[0049] The tensile modulus of the protective film at 23°C is preferably 0.1 GPa to 1.1 GPa, more preferably 0.12 GPa to 1.0 GPa, and even more preferably 0.13 GPa to 0.95 GPa. If the tensile modulus of the protective film at 23°C is within the above range, the protective film can be peeled off using a tape peeling device used for peeling adhesive tape. In this specification, the modulus of the protective film at 23°C refers to the value measured by the following method. A protective film (film) with a thickness of 100 μm is cut to a size of 100 mm in length and 25 mm in width, and pulled using a precision universal testing machine (manufactured by Shimadzu Corporation, device name "Autograph AG-IS") with a chuck distance of 50 mm and a tensile speed of 300 mm / min, and the stress change until the film undergoes plastic deformation is recorded to obtain a stress-strain curve. The tensile modulus is determined by linear regression of the curve between two specified strains ε1=1 and ε2=2. The above measurements are performed using three test pieces cut from different locations, and the average value of these measurements is taken as the tensile modulus. The above measurements are performed at 23°C and 50% RH in accordance with JIS K 7161.

[0050] The adhesive strength of the protective film to the silicon wafer is preferably 1.0 N / 25 mm or less, more preferably 0.8 N / 25 mm or less, even more preferably 0.3 N / 25 mm or less, and particularly preferably 0.1 N / 25 mm or less. The adhesive strength to the silicon wafer is, for example, 0.08 N / 25 mm or more. If the adhesive strength to the silicon wafer is within the above range, the semiconductor wafer surface can be adequately protected during the semiconductor wafer processing process, and after the processing process, it can be easily peeled off without damaging the semiconductor wafer surface. In this specification, the adhesive strength to the silicon wafer refers to the adhesive strength measured by the following method. A liquid surface protective material is applied to a mirror wafer (manufactured by Shin-Etsu Chemical Co., Ltd.) with a wet coating thickness of 200 μm and a length of 100 mm or more, and after drying at 80°C for 5 minutes, a protective film with a thickness of approximately 100 μm is formed. Then, it is left to stand at 23°C for 30 minutes. Next, a 180° peel test is performed at 23°C and 50%RH in an atmosphere with a tensile speed of 300 mm / min to measure the adhesive strength.

[0051] The adhesive strength of the protective film to the silicon wafer after immersion in water is preferably 0.7 N / 25 mm or less, more preferably 0.3 N / 25 mm or less, even more preferably 0.2 N / 25 mm or less, and particularly preferably 0.15 N / 25 mm or less. The adhesive strength to the silicon wafer after immersion in water is, for example, 0.05 N / 25 mm or more. If the adhesive strength to the silicon wafer after immersion in water is within the above range, it can be suitably used in semiconductor wafer processing steps. In this specification, the adhesive strength to the silicon wafer after immersion in water refers to the adhesive strength measured by the following method. A liquid surface protective material is applied to a mirror wafer (manufactured by Shin-Etsu Chemical Co., Ltd.) to a wet coating thickness of 200 μm and a length of 100 mm or more, and after drying at 80°C for 5 minutes, a protective film with a thickness of approximately 100 μm is formed. The silicon wafer with the protective film formed on it is immersed in water at 23°C and left for 30 minutes. Next, a 180° peel test is performed at 23°C and 50%RH in an atmosphere with a tensile speed of 300 mm / min to measure the adhesive strength.

[0052] C. Method for processing semiconductor wafers The semiconductor wafer processing method according to an embodiment of the present invention includes: applying a liquid surface protective material for semiconductor wafer processing to the surface of a semiconductor wafer on which a circuit pattern is formed to form a protective film; grinding the surface of the semiconductor wafer on which the protective film is not formed; and peeling off the protective film. As described above, the liquid surface protective material has excellent embedding properties on the semiconductor wafer surface. Therefore, gaps are less likely to form between the semiconductor wafer and the protective film, which can suppress the occurrence of chipping of the semiconductor wafer due to water intrusion into the gaps, and the adhesion of foreign matter. Furthermore, as described above, the protective film formed using the liquid surface protective material does not need to be dissolved and removed with a solvent, and can be peeled off using a peeling device such as those used for peeling adhesive tape. Therefore, the environmental burden due to the use of solvents can be reduced. In addition, adhesive residue (adhesion of residue of the surface protective member) on the semiconductor wafer surface can be suppressed after peeling.

[0053] Figures 1 to 3 are schematic cross-sectional views of a semiconductor wafer and protective film in a semiconductor wafer processing process according to an embodiment of the present invention. In Figures 1 to 3, (a) shows the protective film 100 and semiconductor wafer 200 after the protective film formation process, (b) shows the protective film 100 and semiconductor wafer 200 after the back surface grinding process, and (c) shows the protective film 100 and semiconductor wafer 200 after peeling and removal. In the semiconductor wafer processing method according to an embodiment of the present invention, the protective film 100 is formed so as to be in contact with the semiconductor wafer 200. As described above, the protective film 100 formed using a liquid surface protective material has excellent embedding properties on the semiconductor wafer surface. Therefore, for example, it can be well embedded even on the surface of a semiconductor wafer with high bump protrusions and a semiconductor wafer with densely formed bumps.

[0054] C-1. Formation of protective film The protective film can be formed by any suitable method. For example, it can be formed by applying the liquid surface protective material described in item A above to the surface on which the circuit pattern is formed on the semiconductor wafer by any suitable method and then drying it.

[0055] The protective film 100 may be formed by applying a liquid surface protective material to fill the protrusions of the bumps on the semiconductor wafer 200, as shown in Figure 1(a), or, as shown in Figures 2(a) and 3(a), a liquid surface protective material may be applied to the semiconductor wafer 200 to form the protective film 100, and then an adhesive sheet 300 may be further bonded to the protective film 100 so that the adhesive layer 320 is in contact with it.

[0056] Examples of coating methods include spin coating, spray coating, ribbon coating, curtain coating, roller coating, brush coating, bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, and screen printing. Spin coating, curtain coating, and spray coating are preferred. By using these methods, the ability to fill in irregularities on the semiconductor wafer surface can be further improved.

[0057] Any suitable drying method can be used. Examples include natural drying, forced-air drying, reduced-pressure drying, and heat drying. Heat drying is preferred. When heat drying is performed, the heating temperature is, for example, 30°C to 100°C. The drying time is, for example, 1 minute to 60 minutes.

[0058] In embodiments where the adhesive sheet 300 is further bonded (embodiments in Figures 2 and 3), the protective film 100 may be formed to have a thickness greater than or equal to the height of the bump's protrusion (Figure 2(a)), or to have a thickness less than the height of the bump's protrusion (Figure 3(a)). As shown in Figures 2(a) and 3(a), when the liquid surface protective material and the adhesive sheet are used in combination, the thickness of the surface protective material can be reduced, and the working time (e.g., the drying time of the protective film) can be shortened. In addition, the TTV (Total Thickness Variation) of the semiconductor wafer can be improved in the back grinding process described later. Furthermore, in the embodiments of Figures 2(a) and 3(a), the portion of the semiconductor wafer surface where the protective film is not formed may be thinly covered with the liquid surface protective material in the coating process (not shown because the thickness is thin). In this embodiment, the portion of the adhesive layer 320 of the adhesive sheet 300 that is in direct contact with the semiconductor wafer 200 is reduced, and adhesive residue of the adhesive layer 320 on the semiconductor wafer 200 can be suppressed. Furthermore, the liquid surface protective material that thinly coats the surface of the semiconductor wafer can be peeled off from the semiconductor wafer surface together with the protective film 100 and / or adhesive sheet 300 in a peeling process described later.

[0059] The adhesive sheet 300 typically comprises a base material 310 and an adhesive layer 320. As the adhesive sheet, for example, any suitable backgrind tape can be used. Specifically, a backgrind tape capable of filling the height of protrusions not embedded in the protective film 100 can be used. Preferably, the adhesive sheet has an adhesive strength of 2N / 25mm or more as measured by a 180° peel test against the protective film 100. If the adhesive strength against the protective film 100 is within the above range, the semiconductor wafer can be properly held in the back grinding process, and in the peeling and removal process, the liquid surface protective material can be peeled off without leaving any adhesive residue.

[0060] C-2. Backside grinding Back grinding of semiconductor wafers can be performed by any suitable method (Figures 1(b), 2(b), and 3(b)). Back grinding is performed on the side of the semiconductor wafer where no circuits are formed (the side where no protective film is formed). Back grinding is generally performed while cooling with water. As described above, protective films formed using liquid surface protective materials have excellent embedding properties. Therefore, it is possible to suppress water intrusion between the semiconductor wafer and the protective film during back grinding, thereby suppressing the occurrence of lifting of the protective film and cracking of the semiconductor wafer.

[0061] C-3. Peeling and Removal After back grinding, the protective film can be peeled off from the semiconductor wafer at any appropriate stage (Figures 1(c), 2(c), and 3(c)). As described above, the protective film formed using the liquid surface protective material can be peeled off, eliminating the need to dissolve and remove the protective film with solvents such as organic solvents. Therefore, the environmental burden due to solvent use can be reduced. Furthermore, the protective film can be peeled off using a peeling device used for peeling off adhesive tape. For this reason, it can be used directly in semiconductor wafer manufacturing lines that use adhesive tape such as back grinding tape. [Examples]

[0062] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, unless otherwise specified, "parts" and "%" are based on weight.

[0063] [Synthesis Example 1] Synthesis of Acrylic Emulsion Resin In a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer, 50 parts by weight of deionized water and 1 part by weight of anionically modified polyvinyl alcohol (manufactured by Mitsubishi Chemical Corporation, trade name "Gosenex L-3266") were added and dissolved at room temperature while introducing nitrogen gas, and the temperature was raised to 60°C. Next, 0.1 parts by weight of polymerization initiator (2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate; Wako Pure Chemical Industries, Ltd., trade name "VA-057") was added to the reaction vessel. Separately, using a homomixer, a monomer composition consisting of 65 parts by weight of n-butyl acrylate (BA), 25 parts by weight of acrylonitrile (AN), and 10 parts by weight of methyl methacrylate (MMA), 0.05 parts by weight of a chain transfer agent (n-lauryl mercaptan), and 2 parts by weight of an emulsifier (polyoxyethylene sodium lauryl sulfate; manufactured by Kao Corporation, trade name "Latemul E118B") were added to 40 parts by weight of ion-exchanged water and mixed while purging with nitrogen to obtain a monomer emulsion. The obtained monomer emulsion was added to a reaction vessel over 3 hours and carried out an emulsion polymerization reaction. The resulting reaction mixture was aged for another 3 hours while maintaining the temperature. Then, after cooling to room temperature, 10% ammonium water was added to adjust the pH to 7.5 to obtain an acrylic emulsion resin.

[0064] [Synthesis Examples 2-5] Synthesis of Acrylic Emulsion Resins An acrylic emulsion resin was obtained in the same manner as in Synthesis Example 1, except that the monomer composition was changed as shown in Table 1.

[0065] [Examples 1-5] The acrylic emulsion resins obtained in Synthesis Examples 1-5 were used directly as liquid surface protective materials, and the following evaluations were performed.

[0066] (Comparative example) A water-soluble resin (manufactured by Nippon Vitro Vinegar Co., Ltd., product name "JC-25") was dissolved in water to a resin concentration of 20% by weight to obtain a liquid surface protective material.

[0067] <Rating> The following evaluations were performed using the liquid surface protective materials obtained in the examples and comparative examples. The results are shown in Table 1. 1. Tensile modulus A liquid surface protective material was applied to the peeled surface of a support material to create a 100 μm thick film. The obtained film was cut to a size of 100 mm in length and 25 mm in width to form test specimens. The test specimens were pulled using a precision universal testing machine (Shimadzu Corporation, machine name "Autograph AG-IS") with a chuck distance of 50 mm and a tensile speed of 300 mm / min. The stress change until the test specimen underwent plastic deformation was recorded, and a stress-strain curve was obtained. The tensile modulus was determined by linear regression of the curve between two specified strains ε1=1 and ε2=2. The above measurements were performed using three test specimens cut from different locations, and the average value was taken as the tensile modulus of the test specimen. The above measurements were performed at 23°C and 50% RH in accordance with JIS K 7161.

[0068] 2. Adhesive strength A liquid surface protective material was applied to the surface of a dummy wafer (manufactured by Shin-Etsu Chemical Co., Ltd.) to a width of 25 mm and a thickness of 200 μm, and dried to form a protective film. The wafer was then left to stand at 23°C for 30 minutes. Next, a 180° peel test was performed at 23°C and 50% RH under a tensile speed of 300 mm / min, and the adhesive strength was measured. Similarly, a liquid surface protective material was applied to the surface of a dummy wafer (manufactured by Shin-Etsu Chemical Co., Ltd.) to a width of 25 mm and a thickness of 200 μm, and dried to form a protective film. The dummy wafer with the protective film was immersed in water at 23°C and left for 30 minutes. Then, a 180° peel test was performed at 23°C and a 50% RH atmosphere at a tensile speed of 300 mm / min, and the adhesive strength was measured.

[0069] 3. Implantability A liquid surface protective material was applied to the surface of a silicon mirror wafer (8-inch, bump height 75 μm, diameter 90 μm, pitch 200 μm) to form a 200 μm thick protective film. The wafer with the protective film was observed from the side using a laser microscope (magnification: 100x) to check the adhesion between the protective film and the wafer. A dummy wafer with the protective film was also imaged from the side where the protective film was formed, and the image was binarized (8-bit grayscale, brightness: 0-255, threshold: 114) using image analysis software (Image J (free software)). Five bumps were arbitrarily selected, and the number of dots used to display each bump was measured. Images with an average number of dots of 600 or less were evaluated as ○ (good), and those with an average number of dots exceeding 600 were evaluated as × (poor). Note that the image of only bumps without a protective film has 220 dots. When a protective film is formed, the number of dots is greater than 220. An average dot count of 600 or less indicates excellent ability to fill in surface irregularities on the wafer.

[0070] 4. Adhesive residue (residue of surface protective material) and solder removal The silicon wafers used for the above adhesive strength evaluation were observed with a laser microscope after the protective film was removed. A good result (○) was given if there was no adhesive residue (protective film residue) on the bumps, while a poor result (×) was given if there was adhesive residue (protective film residue) on the bumps. Similarly, a good result (○) was given if no solder residue was observed on the semiconductor wafer surface, while a poor result (×) was given if solder residue was visible.

[0071] 5. Peelability A protective film was formed on a silicon wafer by applying a surface protective material to a dry thickness of 100 μm. The formed protective film was peeled off the silicon wafer by hand. Films that could be peeled off without tearing were marked with ○ (good), and those that broke midway were marked with × (bad).

[0072] [Table 1]

[0073] The liquid surface protective material for semiconductor wafer processing according to the embodiment of the present invention exhibited excellent embedding properties. Furthermore, the protective film formed by applying the liquid surface protective material was removable, and the adhesion of residue from the protective film was suppressed. [Industrial applicability]

[0074] The liquid surface protective material for semiconductor wafer processing according to the embodiment of the present invention can be suitably used in the semiconductor wafer processing process. [Explanation of Symbols]

[0075] 100 Protective film 200 semiconductor wafers 300 adhesive sheets 310 Base material 320 Adhesive layer

Claims

1. A liquid surface protective material for semiconductor wafer processing, containing an acrylic emulsion resin.

2. The liquid surface protective material for semiconductor wafer processing according to claim 1, wherein the acid value of the acrylic emulsion resin is 10 mg / KOH or less.

3. The SP value of the aforementioned acrylic emulsion resin is 9 (cal / cm²). ３ ) １／２ ~11(cal / cm ３ ) １／２ The liquid surface protective material for semiconductor wafer processing according to claim 1.

4. A liquid surface protective material for semiconductor wafer processing according to claim 1, wherein the BH viscosity is 0.1 Pa·s to 10 Pa·s.

5. A protective film formed using the liquid surface protective material for semiconductor wafer processing described in any one of claims 1 to 4.

6. The protective film according to claim 5, wherein the tensile modulus at 23°C is 0.1 GPa to 1.1 GPa.

7. The protective film according to claim 5, wherein the adhesive force to the silicon wafer is 1.0 N / 25 mm or less.

8. A liquid surface protective material for semiconductor wafer processing according to any one of claims 1 to 4 is applied to the surface of a semiconductor wafer on which a circuit pattern is formed to form a protective film. Grinding the surface of the semiconductor wafer where no protective film is formed, A method for processing a semiconductor wafer, comprising peeling off the protective film.

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