KR101485612B1 - A protective film for semi-conductor wafer - Google Patents

Abstract

An object of the present invention is to provide a protective film which is easily cut by a dicer and does not cause chipping of a wafer.

A protective film for a semiconductor wafer, comprising a base film and a protective film formed on the base film, wherein the protective film comprises (A) at least one selected from the group consisting of a phenoxy resin, a polyimide resin and a (B) an epoxy resin in an amount of 5 to 200 parts by mass, (C) a filler in an amount of 100 to 400 parts by mass, and (D) an epoxy resin curing catalyst in an amount of 100 parts by mass, 10 to 100 parts by mass of silica is silica having a theoretical value of less than 7.2 占^10-7 mol / m2 of the silicone rubber fine particles coated with polyorganosilsesquioxane resin and / or the lipophilic group on the surface.

Description

TECHNICAL FIELD [0001] The present invention relates to a protective film for semiconductor wafers,

TECHNICAL FIELD The present invention relates to a protective film for a wafer for preventing the back surface of a wafer from being damaged when the semiconductor wafer is diced. More specifically, the present invention relates to a protective film for a wafer which contains a specific filler, .

In order to reduce the mounting area of the semiconductor chip, a flip chip connection method is used. In this connection method, a circuit and a connection bump are formed on the surface, a semiconductor chip is obtained by dicing the wafer, the surface of the chip is connected to the substrate and then the resin is sealed to protect the semiconductor chip .

There has been known a sheet for forming a protective film for a chip which prevents wafers from being damaged (hereinafter referred to as " chipping ") due to vibration of rotating blades in the dicing step and acts as a sealing film instead of resin sealing (see Patent Document 1 , Patent Document 2).

[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2002-280329

[Patent Document 2] Japanese Patent Application Laid-Open No. 2004-260190

The protective film for chips is used by bonding to the back surface of the wafer. Therefore, in the dicing step, this protective film is finally cut by the rotating blade. However, since the resin component contained in this protective film has stretchability, it is not easily cut, and the rotary blade is clogged to cause the rotary blade to vibrate, thereby further damaging the wafer. Therefore, it is an object of the present invention to provide a protective film excellent in cutting characteristics without such a problem.

A protective film for semiconductor wafers comprising a base film and a protective film formed on the base film,

The protective film

(A) 100 parts by mass of at least one member selected from the group consisting of a phenoxy resin, a polyimide resin and a (meth) acrylic resin,

(B) 5 to 200 parts by mass of an epoxy resin,

(C) 100 to 400 parts by mass of a filler, and

(D) an epoxy resin curing catalyst,

10 to 100 parts by mass of the filler (C) is silica having a theoretical value of less than 7.2 占^10-7 mol / m2 of the silicone rubber fine particles coated with the polyorganosilsesquioxane resin and / or the lipophilic group on the surface, The theoretical value is the molar amount of this lipophilic group of the silane coupling agent imparted to this surface, relative to the total filler surface area calculated on the assumption that the filler is a sphere, by using the average particle diameter of the filler determined by laser diffraction It is a feature film.

The protective film of the present invention contains a predetermined amount of silica fine particles coated with a polyorganosilsesquioxane resin and / or silica having an amount of the theoretical lipophilic group on the surface of less than 7.2 10 ^-7 mol / Therefore, chipping of the rotating blade can be prevented, and chipping of the wafer can be prevented.

BEST MODE FOR CARRYING OUT THE INVENTION

(A) at least one member selected from the group consisting of a phenoxy resin, a polyimide resin and a (meth) acrylic resin

The phenoxy resin is a resin derived from epichlorohydrin and bisphenol A or F or the like. Preferably, the weight average molecular weight in terms of polystyrene measured by GPC is 10,000 to 200,000, more preferably 20,000 to 100,000, and most preferably 30,000 to 80,000. When the weight average molecular weight is less than the lower limit value, it is difficult to form a film. On the other hand, when the weight average molecular weight is larger than the upper limit value, it is difficult to obtain sufficient flexibility along the surface irregularities of the substrate having a fine circuit pattern.

Examples of the phenoxy resin include those sold under the trade names PKHC, PKHH, and PKHJ (all available from Tomoe Chemical Industries, Ltd.), bisphenol A and bisphenol F mixed type products marketed under the trade names Epicoat 4250, Epicoat 4275 and Epicoat 1255HX30 (All available from Nippon Kayaku), Epikote 5580BPX40 (all manufactured by Nippon Kayaku Co., Ltd.) using brominated epoxy and YP-50, YP-50S, YP-55 and YP- (All available from Japan Epoxy Resins Co., Ltd.), which are commercially available under trade names JER E1256, E4250, E4275, YX6954BH30, and YL7290BH30. In view of having the above-mentioned weight average molecular weight, JER E1256 is preferably used. The phenoxy-terminated polymer has an epoxy group at the terminal, which reacts with the component (B) described later.

As the polyimide resin, those containing the following repeating units can be used.

...(4)

...(4)

Wherein X is a tetravalent organic group containing an aromatic ring or an aliphatic ring, Y is a divalent organic group, and q is an integer of 1 to 300.

Preferably, the weight average molecular weight in terms of polystyrene measured by GPC is 10,000 to 200,000, more preferably 20,000 to 100,000, and most preferably 30,000 to 80,000. When the weight average molecular weight is less than the lower limit value, it is difficult to form a film. On the other hand, when the weight average molecular weight is larger than the upper limit value, it is difficult to obtain sufficient flexibility along the surface irregularities of the substrate having a fine circuit pattern.

The polyimide silicone resin can be obtained by dehydrating and ring-closing a polyamic acid resin having the following repeating unit by a conventional method.

Wherein X, Y, and q are as defined above.

The polyamic acid solution represented by the above formula is represented by the following chemical formula 5

...(5)

... (5)

(Provided that X has the same meaning as defined above)

Tetracarboxylic acid dianhydride represented by the following formula

H ₂ NY-NH ₂ (6)

(Provided that Y has the same meaning as defined above)

In an organic solvent in a nearly equimolar manner according to a conventional method.

Here, examples of the tetracarboxylic dianhydride represented by the above formula (5) include the following, and these may be used in combination.

The diaminosiloxane compound represented by the following formula (1) is preferably used in an amount of 1 to 80 mol%, more preferably 1 to 60 mol%, based on the diamine represented by the formula (6) It is preferable from the viewpoint of flexibility, low elasticity and flexibility.

...(1)

...(One)

Wherein R ¹ is independently a divalent organic group having a carbon number of 3-9 together, R ² and R ³ are groups each independently selected from unsubstituted or the carbon atoms of the optionally substituted 1-81 hydrocarbon, m is 1 to Lt; / RTI >

As the divalent organic group of said number of 3-9 carbon atoms, for example _{- (CH 2) 3 -,} - (CH 2) 4 -, -CH 2 CH (CH 3) -, - (CH 2) 6 -, - ( CH ₂ ) ₈ -, and the like,

An oxyalkylene group such as an arylene group, an alkylene-arylene group, - (CH ₂ ) ₃ -O- or - (CH ₂ ) ₄ -O-,

An oxyalkylene group represented by any one of the following formulas

A divalent hydrocarbon group which may contain an ether bond, such as an oxyalkylene-arylene group, and the like.

Examples of R ² or R ³ include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, An alkenyl group such as a propenyl group, an isopropenyl group, a butenyl group, an isobutenyl group or a hexenyl group, an aryl group such as a phenyl group, a tolyl group or a xylyl group, an aralkyl group such as a benzyl group or a phenylethyl group, A halogen atom such as fluorine, bromine, chlorine or the like, such as a chloromethyl group, a bromoethyl group or a halogen such as a 3,3,3-trifluoropropyl group A substituted alkyl group and the like, among which a methyl group and a phenyl group are preferable. A combination of two or more diaminosiloxane compounds can also be used.

Examples of the diamine represented by the above formula (6) other than the diaminosiloxane compound represented by the formula (1) include p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, (4-aminophenyl) propane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, 1,4-bis (3- Benzene, 1,4-bis (p-aminophenylsulfonyl) benzene, 1,4-bis (m-aminophenylsulfonyl) benzene, Bis (p-aminophenylthio) benzene, 1,4-bis (m-aminophenylthioether) benzene, 2,2- Bis [3-chloro-4- (4-aminophenoxy) phenyl] propane, 1,1-bis Bis [3-chloro-4- (4-aminophenoxy) phenyl] ethane, 1,1- 4-aminophenoxy) piperazine ] Ethane, 1,1-bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] ethane, bis [4- 4- (4-aminophenoxy) phenyl] methane, bis [3-chloro-4- Aromatic diamine-containing diamines such as methane, bis [4- (4-aminophenoxy) phenyl] sulfone and 2,2-bis [4- (4-aminophenoxy) phenyl] perfluoropropane. , Preferably p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 1,4-bis (3-aminophenoxy) Benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2- Aminophenoxy) phenyl] propane and the like.

Preferably, the polyimide resin has a phenolic hydroxyl group in view of adhesiveness. This phenolic hydroxyl group can be provided by using a compound having a phenolic hydroxyl group as a diamine compound, and examples of the diamine include those having the following structures.

Wherein R ⁴ independently represents a hydrogen atom or a halogen atom such as fluorine, bromine or iodine, or an unsubstituted or substituted carbon atom having 1 to 8 carbon atoms such as an alkyl group, an alkenyl group, an alkynyl group, a trifluoromethyl group, The substituent attached to each aromatic ring may be different, and n is an integer of 0 to 5. Each of A and B may be a single kind, or a combination of two or more kinds. R is a hydrogen atom, a halogen atom or an unsubstituted or substituted monovalent hydrocarbon group.

Examples of the unsubstituted or substituted monovalent hydrocarbon groups of 1 to 8 carbon atoms include the same ones exemplified above for R ² and R ³ and alkynyl groups such as an ethynyl group, a propynyl group, a butynyl group, and a hexynyl group. .

Examples of the diamine having another phenolic hydroxyl group include the following.

R in the above formula is an unsubstituted or halogen-substituted monovalent hydrocarbon group such as a hydrogen atom, a halogen atom such as fluorine, bromine or iodine, an alkyl group having 1 to 8 carbon atoms, an alkenyl group, an alkynyl group, a trifluoromethyl group, , The substituent attached to each aromatic ring may be different, and X is a single bond, a methylene group or a propylene group.

Among the diamine compounds having a phenolic hydroxyl group, diamine compounds represented by the following formula (2) are particularly preferred.

...(2)

...(2)

Wherein R < ⁴ > is as defined above.

The blending amount of the diamine compound having a phenolic hydroxyl group is preferably 5 to 60 mass%, particularly 10 to 40 mass%, based on the total amount of the diamine compound. When a polyimide silicone resin having the blending amount within this range is used, a composition capable of forming a flexible adhesive layer with high adhesive strength can be obtained.

Further, a monoamine having a phenolic hydroxyl group may be used for the introduction of the phenolic hydroxyl group, and examples thereof include a monoamine having the following structure.

In the above formula, R ⁴ is as defined above, and the substituent attached to each aromatic ring may be different. D may be used alone, or two or more of them may be used in combination. P is an integer of 1 to 3;

When a monoamine having a phenolic hydroxyl group is used, the compounding amount is 1 to 10 mol% based on the total amount of the diamine compound.

The polyamic acid solution can be synthesized by dissolving each of the starting materials described above in a solvent in an inert atmosphere and reacting at 80 ° C or lower, preferably 0 to 40 ° C. The objective polyimide resin can be synthesized by raising the temperature of the obtained polyamic acid resin to 100 to 200 캜, preferably 150 to 200 캜, by dehydration ring closure of the acid amide portion of the polyamic acid resin.

The solvent may not be completely soluble in the starting material as long as it is inert to the obtained polyamic acid. Examples of the solvent include tetrahydrofuran, 1,4-dioxane, cyclopentanone, cyclohexanone, gamma -butyrolactone, N-methylpyrrolidone, N, N-dimethylacetamide, Dimethylsulfoxide, and is preferably an aprotic polar solvent, particularly preferably N-methylpyrrolidone, cyclohexanone and gamma -butyrolactone. These solvents may be used alone or in combination of two or more.

In order to facilitate the dehydration ring-closing, it is preferable to use an azeotropic dehydrating agent such as toluene or xylene. Further, dehydration ring closure may be carried out at a low temperature using a mixed acetic anhydride / pyridine solution.

In order to adjust the molecular weight of the polyamic acid and the polyimide resin, a dicarboxylic acid anhydride such as maleic anhydride and phthalic anhydride, and / or an aniline, n-butylamine and a monoamine having a phenolic hydroxyl group as mentioned above May be added. However, the addition amount of the dicarboxylic acid anhydride is usually 0 to 2 parts by mass per 100 parts by mass of the tetracarboxylic acid anhydride, and the amount of the monoamine to be added is usually 0 to 2 parts by mass per 100 parts by mass of the diamine.

Examples of the (meth) acrylic resin include (meth) acrylic acid ester monomers and (meth) acrylic acid ester copolymers composed of constitutional units derived from (meth) acrylic acid derivatives. The (meth) acrylic acid ester monomer is preferably a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 18 carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, Butyl and the like. Examples of the (meth) acrylic acid derivatives include (meth) acrylic acid, glycidyl (meth) acrylate, and hydroxyethyl (meth) acrylate.

By introducing a glycidyl group into the (meth) acrylic resin by copolymerizing glycidyl methacrylate or the like, the compatibility with the epoxy resin as the thermosetting adhesive component described later is improved, and the Tg after curing is increased to improve the heat resistance . Further, by introducing a hydroxyl group into the acrylic polymer with hydroxyethyl acrylate or the like, it is easy to control the adhesion to the chip and the adhesive property.

The weight average molecular weight of the (meth) acrylic resin is preferably 100,000 or more, and more preferably 150,000 to 1,000,000. Further, the glass transition temperature of the (meth) acrylic resin is preferably 20 ° C or lower, more preferably -70 ° C to 0 ° C, and has adhesiveness at room temperature (23 ° C).

(B) Epoxy resin

The epoxy equivalent of the epoxy resin is preferably 50 to 5000 g / eq, more preferably 100 to 500 g / eq. Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins; Glycidyl ethers of phenols such as resorcinol, phenyl novolac, and cresol novolak; Glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; Glycidyl ethers of carboxylic acids such as phthalic acid, isophthalic acid and tetrahydrophthalic acid; Glycidyl type or alkyl glycidyl type epoxy resins in which aniline is substituted with a glycidyl group in which active hydrogen bonded to nitrogen atoms such as isocyanurate is substituted; Vinylcyclohexane diepoxide, 3,4-epoxycyclohexylmethyl-3,4-dicyclohexanecarboxylate, 2- (3,4-epoxy) cyclohexyl-5,5-spiro (3,4- ) Cyclohexane-m-dioxane, and the like, there may be mentioned so-called alicyclic epoxides into which an epoxy is introduced by, for example, oxidizing carbon-carbon double bonds in the molecule. Other epoxy resins having a biphenyl skeleton, a dicyclohexadiene skeleton, and a naphthalene skeleton may be used.

Among them, bisphenol A type epoxy resin, bisphenol F type epoxy resin, o-cresol novolak type epoxy resin and phenol novolak type epoxy resin are preferably used. Two or more of these epoxy resins may be used in combination.

(B) The epoxy resin is blended in an amount of 5 to 200 parts by weight, preferably 10 to 200 parts by weight, more preferably 50 to 150 parts by weight, per 100 parts by weight of the component (A). When the component (A) and the component (B) are blended at such a ratio, an appropriate viscosity is exhibited before curing, a bonding operation to the wafer can be performed stably, and a protective film excellent in strength after curing can be obtained.

(C) filler

Examples of the filler include inorganic fillers such as crosslinked spherical dimethylpolysiloxane fine powder having a structure in which conductive particles such as silica, alumina, titanium oxide, carbon black and silver particles and silicone resin powder such as dimethylpolysiloxane are crosslinked (Japanese Patent Laid- 3-93834), a cross-linked spherical polymethylsilsesquioxane fine powder (JP-A-3-47848), a powder obtained by coating a cross-linked spherical polysiloxane rubber surface with polymethylsilsesquioxane particles ( Japanese Patent Application Laid-Open No. 7-196815, Japanese Patent Application Laid-open No. 9-20631).

The blending amount of the filler is 100 to 400 parts by mass, preferably 150 to 350 parts by mass, and more preferably 150 to 300 parts by mass based on 100 parts by mass of the component (A). When the blending amount is less than the above lower limit value, it is difficult to achieve a low water absorption property, a low linear expansion property, etc. for the purpose of blending the filler. On the other hand, when the upper limit is exceeded, the viscosity of the composition for forming a protective layer is increased, and the fluidity when applied to a film substrate becomes poor.

(C) filler, wherein 10 to 100 parts by mass, is preferably 20 to 70 parts by weight poly Organic of theory pro phonograph of the silicone rubber particles and / or surface coated with the nosil silsesquioxane resin 7.2 × 10 ^-7 mol / M2, more preferably less than 3.6 x 10 < ^-7 > mol / m2. This theoretical value is the molar amount of this lipophilic group of the silane coupling agent imparted to this surface to the total filler surface area calculated on the assumption that the filler is a sphere using the average particle diameter of the filler obtained by laser diffraction . The lipophilic group is, for example, a glycidoxymethyl group when the silane coupling agent is glycidoxymethyltrimethoxysilane. This molar amount can be determined from the molar amount of the amount of the silane coupling agent physically adsorbed or chemically bonded to the surface of the filler by the surface treatment.

By containing such fine particles and / or silica, the cutting property of the protective film is remarkably improved. When the blending amount is less than the above lower limit value, it is difficult to realize the cutting property of the chipping protecting film at the time of dicing. On the other hand, if the upper limit is exceeded, the viscosity of the composition for forming a protective film is increased to deteriorate the fluidity when applied to a film substrate. Further, when the protective film is adhered to the wafer due to insufficient adhesion to the wafer, a higher temperature is required, and peeling from the wafer occurs, thereby decreasing the reliability of the protective film.

(C) Theoretical Surface The silica having an amount of the lipophilic group of less than 7.2 × 10 ^-7 mol / m 2 can be prepared by adjusting the degree of surface treatment. It is also possible to use those which are not substantially subjected to surface treatment.

As the silica, fused silica and crystalline silica are used. The average particle diameter of the silica is preferably 0.1 to 10 mu m, more preferably 0.5 to 7 mu m. When the average particle diameter of the silica is within this range, good smoothness of the surface of the applied adhesive layer can be obtained. In recent years, the thickness of the adhesive layer is often required to be in the range of 15 to 50 占 퐉. However, if the average particle diameter of the silica is within the above range, even if secondary aggregated particles are present, it is easy to satisfy the requirement.

The silicone rubber fine particles whose surface is coated with a polyorganosilsesquioxane resin can be produced by the method described in the above-mentioned publications (Japanese Patent Application Laid-Open Nos. 7-196815 and 9-20631) or by the silicone composite powder KMP600 series (Shin-Etsu Chemical Co., Ltd.) can be used. Preferably, KMP 600 is used in terms of particle diameter.

The balance of the (C) filler is preferably an inorganic filler, more preferably silica, most preferably silica produced by the deflagration method. This silica is easily wetted by the resin component and is surface-treated according to a regular method. As the surface treatment agent, a silane-based (silane coupling agent) is preferable because of its versatility and cost merit. As the silane coupling agent, examples of the alkoxysilane include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane,? -Glycidoxyethyltrimethoxysilane,? -Glycidoxyethyltriethoxysilane,? -Glycidoxyethyltrimethoxysilane,? -Glycidoxyethyltriethoxysilane,? -Glycidoxypropyltrimethoxysilane,? -Glycidoxypropyltriethoxysilane,? -Glycidoxypropyl tri Methoxysilane,? -Glycidoxypropyl-glycidoxypropyltriethoxysilane,? -Glycidoxypropyltrimethoxysilane,? -Glycidoxypropylmethyldiethoxysilane,? -Glycidoxybutyltrimethoxysilane, Glycidoxybutyltrimethoxysilane,? -Glycidoxybutyltrimethoxysilane,? -Glycidoxybutyltrimethoxysilane,? -Glycidoxybutyltrimethoxysilane,? -Glycidoxybutyltrimethoxysilane,? -Glycidoxybutyltrimethoxysilane, Methyl-butyl triethoxysilane, 隆 -glycidoxybutyltrimethoxysilane, 隆- (3,4-epoxycyclohexyl) methyltrimethoxysilane, (3,4-epoxycyclohexyl) methyltriethoxysilane,? - (3,4-epoxycyclohexyl) ethyl (3,4-epoxycyclohexyl) ethyltriethoxysilane,? - (3,4-epoxycyclohexyl) ethyltripropoxysilane,? - (3,4-epoxycyclohexyl) (3,4-epoxycyclohexyl) ethyltriphenoxysilane, γ- (3,4-epoxycyclohexyl) propyltrimethoxysilane, γ- (3,4-epoxycyclohexyl) ethyltripropoxysilane, ) Trialkoxysilane such as propyl triethoxysilane,? - (3,4-epoxycyclohexyl) butyl trimethoxysilane and? - (3,4-epoxycyclohexyl) butyl trimethoxysilane, N- (Aminoethyl)? -Aminopropyltrimethoxysilane, N -? - (aminoethyl)? -Aminopropylmethyldiethoxysilane,? -Aminopropyltrimethoxysilane, N-phenyl- Methoxy silane, trime Sicily reel profile nadic acid anhydride, γ- mercaptopropyl trimethoxysilane, γ- stayed in the mercapto propyl triethoxysilane is preferably used.

(D) Epoxy resin curing catalyst

As the curing catalyst, a type which is heated and cured, that is, a so-called latent active latent epoxy resin curing agent is preferable. Examples thereof include dicyandiamide, imidazole compounds, various onium salts, dibasic acid dihydrazide compounds and the like, or a combination of two or more of them may be used. The amount of this curing catalyst may be an effective amount as a catalyst, but is usually 0.1 to 20 parts by weight, preferably 1 to 12 parts by weight, based on 100 parts by weight of the epoxy resin.

Other ingredients

In addition to the above-mentioned components, the protective film of the present invention may contain a curing agent for epoxy resin and various additives. Examples of the curing agent include phenol resins such as condensates of phenols such as alkylphenol, polyhydric phenol and naphthol with aldehydes and the like, and phenol novolak resins, o-cresol novolak resins, p-cresol novolak resins , t-butylphenol novolak resin, dicyclopentadiene cresol resin, polyparabinyl phenol resin, bisphenol A type novolac resin, bisphenol F type novolak resin, or modified materials thereof.

As additives, pigments and dyes can be exemplified. When the protective film of the present invention is colored by blending them, laser mark performance is improved. A silane coupling agent may also be added for the purpose of improving adhesion and adhesion between the protective film and the back surface of the chip. Other additives such as flame retardants and antistatic agents may also be added.

The protective film can be obtained by applying a composition obtained by mixing the above components on a base film to a thickness of 5 to 100 mu m, preferably 10 to 60 mu m by a known method such as a gravure coater. The above-mentioned composition can be applied by dispersing it in a solvent such as cyclohexanone, if necessary.

As the base film, a polyethylene film, a polypropylene film, a polyvinyl chloride film, a polyethylene terephthalate film, a polyimide film and the like are used. When the base film is peeled off after curing the protective film, a polyethylene terephthalate film or a polyimide film having excellent heat resistance is preferably used. At this time, a releasing layer may be formed between the base film and the protective film by coating the surface of the base film with a silicone resin or the like.

The film thickness of the substrate is 5 to 200 mu m, preferably 10 to 150 mu m, particularly preferably 20 to 100 mu m or so.

The protective film is used, for example, in the following manner.

(1) A step of bonding a protective film of a protective film to the back surface of a semiconductor wafer having a circuit formed on its surface

(2) Step of peeling off the base film of the protective film

(3) a step of curing the protective film by heating

(4) Dicing the semiconductor wafer and the protective film

Here, steps (2) and (3) may be reversed.

The dicing can be performed according to a regular method using a dicing sheet. A semiconductor chip having a protective film on the back surface can be obtained by dicing. The chip is picked up by a general means such as a collet and placed on a substrate. By using the protective film of the present invention, minute damage is not easily generated on the chip cut surface, and the semiconductor device can be manufactured with high yield.

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the following examples.

Preparation of composition for forming protective layer

Component (A) in a mass part shown in Table 1 was dissolved in about 50 parts by mass of cyclohexanone. The obtained solution and other components shown in Table 1 were mixed to obtain a composition having a solid content of about 70% by weight.

The components shown in Table 1 are as follows.

(A) Component

Phenoxy resin-based polymer: Mw about 60,000, JER 1256 (manufactured by Japan Epoxy Resins Co., Ltd.)

Polyimide resin: The synthesis method will be described later.

Acrylic resin: 55 parts by weight of butyl acrylate, 15 parts by weight of methyl methacrylate, 20 parts by weight of glycidyl methacrylate and 15 parts by weight of 2-hydroxyethyl acrylate (weight average molecular weight: 900,000, glass transition temperature: ° C)

Component (B)

Epoxy resin: RE310S (manufactured by Nippon Kayaku Co., Ltd.), viscosity at 25 占 폚 of 15 Pa.s

(C) Component

Silica: SE2050, average particle diameter 0.5 mu m, maximum particle diameter 5 mu m, KBM-403 treated product, manufactured by Admatechs Co.

Silicon fine particles coated with polyorganosilsesquioxane resin: KMP600), manufactured by Shin-Etsu Chemical Industry Co., Ltd.

Silica: SO-E3, average particle diameter 1.0 mu m, specific surface area 3.6 m < 2 > / g, surface untreated product, manufactured by Admatechs Co.

(D) Component

Dicyandiamide (DICY-7): manufactured by Japan Epoxy Resin Co., Ltd.

Synthesis of polyimide silicone resin

(KF-8010, manufactured by Shin-Etsu Chemical Co., Ltd.) (49.01 parts by mass) represented by the following chemical formula was added to a 1-liter separable flask equipped with a 25-ml water content determining device, a thermometer and a stirrer, , And 100 parts by mass of 2-methylpyrrolidone as a reaction solvent were introduced and stirred at 80 DEG C to disperse the diamine. To this was added dropwise a solution of 42.68 parts by mass of 6FDA (2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane) as an acid anhydride and 100 parts by mass of 2-methylpyrrolidone, followed by stirring at room temperature for 2 hours An acid anhydride-rich amic acid oligomer was synthesized.

Next,

, 8.31 parts by mass of a diamine having a phenolic hydroxyl group (HAB, manufactured by Wakayama Seika), and 100 parts by mass of 2-methylpyrrolidone were placed in a 25-ml water-containing autoclave equipped with a cap connected with a reflux condenser, a thermometer and a stirrer The resulting mixture was poured into a 1 liter separable flask, dispersed, and the acid anhydride-rich amic acid oligomer was added dropwise thereto, followed by stirring at room temperature for 16 hours to synthesize a polyamic acid solution. Thereafter, 25 ml of xylene was added, and then the temperature was raised and refluxed at about 180 캜 for 2 hours. Xylene was removed at 180 占 폚 while removing the effluent accumulated in the water quantitative analyzer, confirming that a predetermined amount of water was accumulated in the water quantitative analyzer and that the water was not visible. After completion of the reaction, the reaction solution obtained in a large excess of methanol was added dropwise to precipitate a polymer, which was then dried under reduced pressure to obtain a polyimide resin having a phenolic hydroxyl group in the skeleton.

The infrared absorption spectrum of the obtained polyimide resin was measured. As a result, the absorption based on the polyamic acid showing that there was an unreacted functional group was not observed, the absorption based on the imide group was confirmed at 1780 cm ^-1 and 1720 cm ^-1 , cm < ^{-1 &} gt ;, based on the phenolic hydroxyl groups. The weight average molecular weight of the obtained resin in terms of polystyrene was 55,000 and the functional equivalent was 760 g / eq.

Preparation of protective film

The composition for forming the protective layer was coated on a PET film having a thickness of 38 mu m covered with a silicone release agent and dried by heating at 110 DEG C for 10 minutes to form a protective layer having a thickness of 25 mu m.

Chipping test

The obtained protective film was polished by # 2000 using a Techno Vision FM-114 at 70 占 폚 to a silicon wafer (8-inch unbaked wafer, thickness: 75 占 퐉, DAG-810 manufactured by Disco Corporation) Thick wafer). This silicon wafer was diced into chips each having a size of 10 mm x 10 mm with the following conditions, and eight chip microphotographs of the obtained chips were taken, and chipping was determined to be present if chipping was 25 mu m or more in the cross-sectional direction. The results are shown in Table 1.

Dicing conditions

Device: DISCO Daiji DAD-341

Cutting method: single

Number of rotations: 0000 rpm

Blade speed: 50 mm / sec

The thickness of the dicing film was 85 占 퐉, the thickness of the dicing film was 15 占 퐉

Shear adhesion

The protective film was adhered to the back surface of a silicon wafer having a diameter of 8 inches in the same manner as described above, cut into chips each having a size of 3 mm x 3 mm, and then picked up to obtain a silicon wafer having a size of 10 mm x 10 mm The laminate obtained by hot pressing under the conditions of 170 DEG C and 0.63 MPa for 1 second was heated at 175 DEG C for 4 hours to cure the protective layer to prepare a test piece. Shear adhesion (MPa) was measured at a speed of 200 μm / sec and a height of 50 μm using Dage 4000 manufactured by Dage. The results are shown in Table 1.

Shear bond strength after moist heat treatment

The test piece obtained in the same manner as described above was held for 168 hours under the condition of 85 占 폚 / 60% RH, and IR reflow at 260 占 폚 was performed three times, and the shear adhesive force was measured in the same manner as described above. The results are shown in Table 1.

The protective film of the first comparative example contains only a filler having a surface lipophilic group higher than that of the present invention. This protective film had a poor cutting property and chipping occurred. In the protective film of the first reference example, the surface lipophilic group contained only the silica which was within the range of the present invention and was not surface-treated, and there was no chipping, but the adhesion to the wafer was poor. On the other hand, the protective film of the examples had good adhesiveness, and chipping of the wafer was well prevented.

[Industrial Availability]

The protective film of the present invention can improve the yield of a silicon chip and is useful for manufacturing a semiconductor device.

Claims (5)

A protective film for semiconductor wafers comprising a base film and a protective film formed on the base film, The protective film (A) 100 parts by mass of at least one selected from the group consisting of a phenoxy resin, a polyimide resin and a (meth) acrylic resin, (B) 5 to 200 parts by mass of an epoxy resin, (C) 100 to 400 parts by mass of a filler, and (D) an epoxy resin curing catalyst, Characterized in that 10 to 100 parts by mass of the filler (C) is a silicone rubber fine particle coated with a polyorganosilsesquioxane resin. The film according to claim 1, wherein (A) the polyimide resin is a polyimide silicone resin having a phenolic hydroxyl group, and (B) the epoxy resin is a bisphenol A type epoxy resin or a bisphenol F type epoxy resin. The film according to claim 1 or 2, wherein the (C) filler comprises silica rubber fine particles coated with a polyorganosilsesquioxane resin and silica. The film according to claim 3, wherein the silica is prepared by a blowing method. The film according to claim 3, wherein the silica is surface-treated with a silane coupling agent.