JP2008000858A - Adhesive film back surface grinding of semiconductor wafer and back surface grinding method of semiconductor wafer using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive film for back surface grinding of a semiconductor wafer capable of preventing breakage and contamination of the wafer due to intrusion of water and grinding chips between a wafer surface and an adhesive layer in grinding a back surface of the semiconductor wafer, not breaking the wafer in peeling it and not causing contamination of the wafer surface and a back surface grinding method of the semiconductor wafer using it. <P>SOLUTION: This adhesive film for back surface grinding has the adhesive layer formed by using coating liquid for the adhesive layer containing specific quantity of (1) an acrylic acid alkyl ester system adhesive polymer having a functional group reactive with a cross linking agent, (2) specific cross linking agent a main skeleton of which is an alkylene glycol polymer the number of carbon of an alkylene group of which is 2 to 4, having at least two pieces of glycidyl groups on its terminal and weight average molar weight of which is 1,000 to 5,000 and (3) other cross linking agents as essential components. Additionally, the back surface grinding method uses the adhesive film for back surface grinding. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an adhesive film for back grinding of a semiconductor wafer and a back surface grinding method of a semiconductor wafer using the same. Specifically, in the manufacturing process of a semiconductor integrated circuit, in order to prevent damage and contamination of the semiconductor wafer when grinding the back surface of the semiconductor wafer, the surface on the side where the integrated circuit of the semiconductor wafer is incorporated (hereinafter, as appropriate, The present invention relates to an adhesive film for grinding a back surface of a semiconductor wafer that is directly attached to an “surface” of a wafer via an adhesive layer, and a method for grinding a back surface of a semiconductor wafer using the adhesive film.

  Usually, a semiconductor integrated circuit is obtained by slicing a high-purity silicon single crystal or the like into a wafer, and then incorporating the integrated circuit into one surface of the wafer by ion implantation, etching, or the like, and further, the other surface of the wafer (hereinafter referred to as appropriate) The wafer is manufactured by a method of grinding a wafer “back surface”) by grinding, polishing, lapping or the like to reduce the thickness of the wafer to about 100 to 600 μm and then dicing into chips. In these processes, an adhesive film for grinding a back surface of a semiconductor wafer is used in order to prevent damage and contamination of the semiconductor wafer when the back surface of the wafer is ground. Specifically, an adhesive film for grinding a back surface of a semiconductor wafer is directly attached to the wafer surface via the adhesive layer to protect the wafer surface, and then the back surface of the wafer is ground. After the grinding is completed, the adhesive film is peeled off from the wafer surface.

When grinding a backside of a conventional semiconductor wafer with a semiconductor wafer with an integrated circuit built into the periphery of the wafer, that is, a semiconductor wafer with a scribe line reaching the outermost periphery of the wafer. In this case, water enters between the wafer surface and the pressure-sensitive adhesive layer through the concave portion caused by the scribe line, and as a result, the wafer is damaged or grinding waste enters with the water and the wafer surface is There was sometimes contamination.
In order to prevent this problem, means for increasing the thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film and improving the adhesion between the concave portion of the wafer surface and the pressure-sensitive adhesive layer has been adopted. However, when this means is used, the adhesive force of the adhesive film to the wafer surface is greater than the strength of the wafer, and depending on various conditions such as the thickness and surface shape of the wafer, the adhesive film may be When peeling from the wafer, a peeling trouble may occur with the automatic peeling machine, and sometimes the wafer may be completely damaged.

  As means for solving such a problem, for example, in Patent Document 1 below, when polishing the back surface of a semiconductor wafer, a semiconductor that attaches a pressure-sensitive adhesive film to the surface of the wafer and peels off the adhesive film after polishing. In a method for protecting a wafer, a pressure-sensitive adhesive film comprises a light-transmitting support and a pressure-sensitive adhesive layer having a property of being cured by light irradiation and being three-dimensionally reticulated on the support, and after polishing. A method for protecting a semiconductor wafer is disclosed in which the adhesive film is irradiated with light before the adhesive film is peeled off.

  Since the method for protecting a semiconductor wafer disclosed in Patent Document 1 can reduce the adhesive force of the adhesive film to the wafer surface by irradiating light before peeling, the problem of workability and wafer breakage at the time of peeling is considered. Therefore, the adhesion to the wafer surface at the time of back surface grinding can be sufficiently increased, and the above-described problem of water and grinding dust intrusion between the wafer surface and the adhesive layer is solved.

  However, when the adhesive film disclosed in Patent Document 1 is used, it is necessary to irradiate light after the back surface grinding until the adhesive film is peeled from the wafer surface. There is a problem that the apparatus has to be introduced and the apparatus becomes large and complicated, or the process becomes complicated and workability is lowered. There is also a problem that the working environment is deteriorated by ozone generated by light irradiation. Furthermore, depending on various conditions such as the surface shape of the wafer, light irradiation intensity, and time, a problem of adhesive residue may occur on the wafer surface after peeling due to poor curing of the pressure-sensitive adhesive layer. In order to prevent this problem, it is necessary to fill the inside of the light irradiation device with an inert gas such as nitrogen, which raises the manufacturing cost and increases the process size and complexity.

  Patent Document 2 listed below is a semiconductor wafer comprising a support sheet provided with a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer having a gel fraction of 40% or more and containing a water-soluble polymer. In this case, it is described that the pressure-sensitive adhesive layer preferably contains polypropylene glycol having a molecular weight of 5000 or less as a water-soluble polymer.

  The protective member (adhesive film) of the semiconductor wafer disclosed in Patent Document 2 contains the water-soluble polymer in the pressure-sensitive adhesive layer (adhesive layer), thereby peeling the protective member from the circuit pattern forming surface and the like. Later, it is described that even if it is directly washed with water without pre-washing with an organic solvent, it can be washed sufficiently finely, and therefore pre-washing with an organic solvent can be omitted. In addition, it prevents water from entering the adhesive interface during backside polishing, etc., prevents contamination of the circuit pattern formation surface by polishing debris, prevents wafer damage due to peeling, and prevents cracking of the polished wafer during peeling. In addition, it is also described that the water-soluble polymer adhered to the semiconductor wafer by bleed can be easily washed with water.

  However, when the protective member for a semiconductor wafer disclosed in Patent Document 2 is used for grinding the back surface of a semiconductor wafer, the protective member may be removed from the wafer depending on various conditions such as the surface shape of the wafer, the back surface grinding conditions, and the peeling conditions. When peeling, a part of the pressure-sensitive adhesive layer remains on the wafer surface due to cohesive failure (hereinafter, referred to as adhesive residue), and the wafer surface may be contaminated. The adhesive residue due to this cohesive failure may not be completely removed even by washing with water. If it occurs in the electrode part of the circuit, bonding failure will occur during bonding, and if it occurs in other parts, packaging will occur. Defects sometimes occurred.

  In recent years, with the demand for technological innovation and cost reduction in the semiconductor industry, semiconductor wafers tend to have larger diameters and thinner layers year by year. In particular, the thickness of semiconductor wafers after back grinding is becoming increasingly thinner due to increasing demand for semiconductor chips that are required to be thin, such as thin packaging and smart card applications. is there. Since the time required for grinding the back surface increases with the area of the wafer, it is considered that the problem of wafer breakage / contamination due to the ingress of water and grinding debris during grinding becomes more likely as the wafer becomes larger in diameter. Furthermore, considering that the strength of the wafer itself decreases as the thickness of the wafer decreases, the above-mentioned problem of damage to the wafer during peeling is expected to become more serious as the wafer becomes thinner. Is done.

  In addition, due to the diversification of semiconductor wafer surfaces in recent years, there are an increasing number of wafers having a surface shape in which a part of the adhesive is likely to remain. For example, as a wafer having a chip suitable for a smart card application, a wafer having a protruding high bump electrode having a height of 5 to 100 μm has been produced. When grinding the back surface of a semiconductor wafer having such a protruding high bump electrode on the surface, when peeling the adhesive film from the ground wafer, a part of the adhesive remains on the surface of the wafer (hereinafter, This is sometimes referred to as “glue residue”.) The wafer surface may be contaminated. Contamination due to the adhesive residue often occurs around the high bump electrode. In such a case, it is difficult to remove the contamination even by post-treatment such as cleaning, which may be a particularly serious problem. Contamination due to adhesive residue generated around the high bump electrode may be insufficiently removed by washing even when the semiconductor wafer protection member disclosed in Patent Document 2 is used.

In addition, in the adhesive film for back grinding of semiconductor wafers, a relatively low molecular weight alkylene glycol polymer is incorporated into the adhesive layer in consideration of control of the adhesive force to the wafer, ease of decontamination by washing with water, etc. There is a technique of adding (see, for example, Patent Document 3). However, if the pressure-sensitive adhesive layer contains an alkylene glycol polymer as described above, the alkylene glycol polymer bleeds out of the pressure-sensitive adhesive layer, which may cause contamination of the wafer surface, which can be further improved. It was sought after.
JP 60-189938 A JP-A-5-335288 Japanese Patent Laid-Open No. 11-31525

  An object of the present invention is to prevent damage and contamination of a wafer due to the ingress of water and grinding debris between the wafer surface and an adhesive layer when grinding the back surface of a semiconductor wafer, and peeling. An object of the present invention is to provide an adhesive film for grinding a back surface of a semiconductor wafer that sometimes does not damage the wafer and does not cause contamination of the wafer surface, and a method for grinding the back surface of a semiconductor wafer using the same.

  As a result of intensive studies in view of the above problems, the present inventors have developed a pressure-sensitive adhesive layer having a specific composition containing a specific alkylene glycol polymer having at least two glycidyl groups in one molecule as an essential component. It has been found that the object can be achieved by an adhesive film for backside grinding of a semiconductor wafer, and the present invention has been completed.

That is, the means for solving the problems are as follows.
<1> An adhesive film for grinding a back surface of a semiconductor wafer that is adhered to a circuit-forming surface when grinding the back surface of a semiconductor wafer, wherein the back surface of the semiconductor wafer is ground on one surface of a base film. A pressure-sensitive adhesive film for grinding a back surface of a semiconductor wafer to be adhered to the circuit-forming surface, on the one surface of a base film, the following (A) component and the following (C) component total 100 parts by mass ( (B) It is formed by using a coating solution for an adhesive layer containing 0.5 to 20 parts by mass of the component and 0.5 to 10 parts by mass of the following (C) component with respect to 100 parts by mass of the following (A) component. An adhesive film for grinding a back surface of a semiconductor wafer, comprising an adhesive layer.
(I): Acrylic acid alkyl ester-based pressure-sensitive adhesive polymer having a functional group capable of reacting with a crosslinking agent (b): An alkylene glycol polymer having 2 to 4 carbon atoms of an alkylene group as a main skeleton, and at least two at the end A crosslinking agent having a glycidyl group and having a weight average molecular weight in the range of 1000 to 5000 (c): other crosslinking agent having a molecular structure different from that of the component (b)

  <2> The back surface of a semiconductor wafer, wherein the adhesive film according to claim 1 is attached to a circuit forming surface of a semiconductor wafer, the back surface of the semiconductor wafer is ground, and the adhesive film is peeled off after the grinding is finished. Grinding method.

According to the present invention, when grinding the back surface of a semiconductor wafer, it is possible to prevent damage and contamination of the wafer due to penetration of water and grinding debris between the wafer surface and the pressure-sensitive adhesive layer, and peeling. A pressure-sensitive adhesive film for grinding a back surface of a semiconductor wafer that sometimes does not damage the wafer and does not cause contamination of the wafer surface, and a method for grinding a back surface of a semiconductor wafer using the same can be provided.
Specifically, according to the present invention, when the back surface of a semiconductor wafer is ground, damage to the wafer and contamination of the wafer surface caused by water and grinding debris entering between the wafer surface and the adhesive layer are prevented. Does not happen. Since the adhesive force is in an appropriate range, the wafer is not damaged when the adhesive film is peeled off from the wafer, and there is no need to newly install equipment such as a light irradiation device in the process. Furthermore, since no adhesive residue or bleed-out of low molecular components from the adhesive layer occurs after the adhesive film is peeled from the wafer, the surface of the semiconductor wafer is not contaminated.

  Hereinafter, the adhesive film for back surface grinding of a semiconductor wafer of the present invention and the back surface grinding method of the semiconductor wafer using the same will be described in detail.

[Adhesive film for backside grinding of semiconductor wafers]
The adhesive film for grinding a back surface of a semiconductor wafer according to the present invention (hereinafter sometimes simply referred to as “adhesive film”) is attached to the circuit forming surface of the back surface of the semiconductor wafer when the back surface of the semiconductor wafer is ground. It is a pressure-sensitive adhesive film for grinding, and the following (b) component 0.5 to 20 parts by mass with respect to 100 parts by mass of the following (A) component and the following (C) component on one surface of the base film, (A) It has the adhesive layer formed using the coating liquid for adhesive layers containing 0.5-10 mass parts of the following (iii) component with respect to 100 mass parts of components.
(I): Acrylic acid alkyl ester-based pressure-sensitive adhesive polymer having a functional group capable of reacting with a crosslinking agent (b): An alkylene glycol polymer having 2 to 4 carbon atoms of an alkylene group as a main skeleton, and at least two at the end A crosslinking agent having a glycidyl group and having a weight average molecular weight in the range of 1000 to 5000 (c): other crosslinking agent having a molecular structure different from that of the component (b)

The pressure-sensitive adhesive film of the present invention has a pressure-sensitive adhesive layer on one surface of a base film, and is usually constituted by sticking a release film on the pressure-sensitive adhesive layer.
Hereinafter, each component of the adhesive film of this invention is demonstrated in detail.

  The pressure-sensitive adhesive layer according to the present invention has, on one surface of a base film, 0.5 to 20 parts by mass of the component (b) with respect to 100 parts by mass of the sum of the component (b) and the component (c), It is the layer formed using the coating liquid for adhesive layers containing the said (ha) component 0.5-10 mass parts with respect to 100 mass parts of said (I) component. The coating liquid for the pressure-sensitive adhesive layer may contain optional components other than these as desired. The pressure-sensitive adhesive layer coating solution is prepared as a solution or emulsion solution containing the above essential components and optional components.

<(I) component>
The pressure-sensitive adhesive layer coating liquid according to the present invention comprises (a) an acrylic acid alkyl ester pressure-sensitive adhesive polymer having a functional group capable of reacting with a crosslinking agent (hereinafter, appropriately referred to as “pressure-sensitive adhesive polymer”) as an essential component. contains.

  The pressure-sensitive adhesive polymer according to the present invention is a polymer obtained by copolymerizing a monomer mixture containing a comonomer having a functional group capable of reacting with a cross-linking agent using an alkyl acrylate ester and / or an alkyl methacrylate ester as a main monomer. Preferably there is.

Examples of the main monomer used for copolymerization of the pressure-sensitive adhesive polymer include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, and 2-ethylhexyl acrylate. These may be used alone or in combination of two or more.
It is preferable that the usage amount of the main monomer is usually contained in the range of 60 to 99% by mass in the total amount of all monomers used as raw materials for the pressure-sensitive adhesive polymer.

Comonomers having a functional group capable of reacting with a crosslinking agent to be copolymerized with the main monomer include acrylic acid, methacrylic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, maleic acid, itaconic acid monoalkyl ester, and mesacone. Acid monoalkyl ester, citraconic acid monoalkyl ester, fumaric acid monoalkyl ester, maleic acid monoalkyl ester, acrylic acid-2-hydroxyethyl, methacrylic acid-2-hydroxyethyl, acrylamide, methacrylamide, tert-butylaminoethyl acrylate And tertiary-butylaminoethyl methacrylate.
One of these comonomers may be copolymerized with the above main monomer, or two or more thereof may be copolymerized.
It is preferable that the usage-amount of the comonomer which has a functional group which can react with a crosslinking agent is normally contained in the range of 1-40 mass% in the total amount of all the monomers used as the raw material of an adhesive polymer.

  The pressure-sensitive adhesive polymer according to the present invention includes a specific comonomer having properties as a surfactant in addition to the above-described main monomer and a comonomer having a functional group capable of reacting with a crosslinking agent (hereinafter referred to as “polymerizable surfactant” as appropriate). May be copolymerized. The polymerizable surfactant has a property of copolymerizing with a main monomer and a comonomer, and also has an action as an emulsifier when emulsion polymerization is performed. In the case of using a pressure-sensitive adhesive polymer that is emulsion-polymerized using a polymerizable surfactant, the surface of the wafer is usually not contaminated by the surfactant. Even when slight contamination caused by the pressure-sensitive adhesive layer occurs, it can be easily removed by washing the wafer surface with water.

  Examples of the polymerizable surfactant that can be used in the present invention include, for example, those obtained by introducing a polymerizable 1-propenyl group into the benzene ring of polyoxyethylene nonylphenyl ether [for example, manufactured by Daiichi Kogyo Seiyaku Co., Ltd .; Aqualon RN-10, RN-20, RN-30, RN-50, etc.], a polyoxyethylene nonylphenyl ether sulfate ester ammonium salt having a polymerizable 1-propenyl group introduced into the benzene ring [ For example, manufactured by Daiichi Kogyo Seiyaku Co., Ltd .; Aqualon HS-10, HS-20, etc.] and sulfosuccinic acid diester type having a polymerizable double bond in the molecule [for example, manufactured by Kao Corporation Latemul S-120A, S-180A, etc.].

  Furthermore, if necessary, a self-crosslinkable functional group such as glycidyl acrylate, glycidyl methacrylate, isocyanate ethyl acrylate, isocyanate ethyl methacrylate, 2- (1-aziridinyl) ethyl acrylate, 2- (1-aziridinyl) ethyl methacrylate, etc. Monomers with polymerizable double bonds such as vinyl acetate, acrylonitrile and styrene, and polyfunctional monomers such as divinylbenzene, vinyl acrylate, vinyl methacrylate, allyl acrylate and allyl methacrylate. Polymerization may be performed.

  As a method for polymerizing the pressure-sensitive adhesive polymer, various known methods such as a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method can be adopted. However, to the molecular weight of the pressure-sensitive adhesive polymer and the cohesive strength of the pressure-sensitive adhesive. It is necessary to consider the effects of Among these polymerization methods, the emulsion polymerization method is preferable in view of obtaining a high molecular weight polymer, environmental contamination in the coating and drying steps, coating properties, and the like.

  The polymerization reaction mechanism of the pressure-sensitive adhesive polymer includes radical polymerization, anionic polymerization, cationic polymerization, etc., but the production cost of the pressure-sensitive adhesive, the influence of the functional group of the monomer and the influence of ions on the surface of the semiconductor wafer, etc. are considered. In this case, the polymerization is preferably performed by radical polymerization.

  Examples of radical polymerization initiators that can be used for polymerization by radical polymerization reaction include benzoyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, di-tertiary-butyl peroxide, di-tertiary-amyl peroxide, etc. Organic peroxides, inorganic peroxides such as ammonium persulfate, potassium persulfate, sodium persulfate, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 4 , 4′-azobis-4-cyanovaleric acid, and the like.

  In the case of polymerization by emulsion polymerization, among these radical polymerization initiators, inorganic peroxides such as water-soluble ammonium persulfate, potassium persulfate, and sodium persulfate, and also water-soluble 4,4′-azobis- An azo compound having a carboxyl group in the molecule such as 4-cyanovaleric acid is preferred. Considering the influence of ions on the surface of the semiconductor wafer, azo compounds having a carboxyl group in the molecule such as ammonium persulfate and 4,4'-azobis-4-cyanovaleric acid are more preferable. An azo compound having a carboxyl group in the molecule such as 4,4'-azobis-4-cyanovaleric acid is particularly preferred.

<(B) component>
The coating solution for the pressure-sensitive adhesive layer according to the present invention comprises (b) an alkylene glycol polymer having 2 to 4 carbon atoms of an alkylene group as a main skeleton, has at least two glycidyl groups at its ends, and has a weight average. A crosslinking agent having a molecular weight in the range of 1000 to 5000 (hereinafter referred to as “specific crosslinking agent” as appropriate) is contained as an essential component.

  The pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive layer coating solution containing the specific crosslinking agent has improved adhesion between the pressure-sensitive adhesive layer and the wafer surface, and the wafer surface and the pressure-sensitive adhesive layer are ground when the wafer back surface is ground. In addition, there is an effect of preventing water intrusion (hereinafter referred to as water resistance), and the wafer is not damaged when peeling the adhesive film from the wafer surface. In the case of a wafer having the same, contamination to the periphery of the high bump electrode) does not occur.

  One of the characteristics of the specific crosslinking agent is that the specific crosslinking agent has at least two glycidyl groups at the end of the molecular structure, and the functional group capable of reacting with the crosslinking agent possessed by the glycidyl group and the pressure-sensitive adhesive polymer. As a result of the cross-linking reaction, the specific cross-linking agent is fixed in the pressure-sensitive adhesive layer, so that the specific cross-linking agent does not bleed out from the pressure-sensitive adhesive layer. For this reason, the pressure-sensitive adhesive film of the present invention can effectively suppress not only contamination of the wafer surface due to adhesive residue but also contamination of the wafer surface due to bleeding out.

It is sufficient that at least two glycidyl groups in the specific cross-linking agent are introduced at the end of the molecular structure of the specific cross-linking agent. From the viewpoint of improving the efficiency of the cross-linking reaction and maintaining the flexible properties of the obtained pressure-sensitive adhesive after cross-linking. Preferably has at least one glycidyl group at each of both ends of the main chain.
The number of glycidyl groups in the specific crosslinking agent can be confirmed as an epoxy equivalent by the perchloric acid method.

  Examples of the method for introducing a glycidyl group in the specific crosslinking agent include a method of synthesizing by a known technique using polyalkylene glycol and epichlorohydrin.

  Moreover, the specific crosslinking agent has limited the weight average molecular weight to the specific range mentioned later. Although the detailed reason is not clear, by setting the molecular weight of the specific cross-linking agent within this range, the water resistance during grinding of the wafer back surface is improved and the wafer surface (especially in the case of a wafer having a high bump electrode, the high bump is used). There is an effect of reducing contamination due to the pressure-sensitive adhesive layer around the electrode).

  Here, in the present invention, the alkylene glycol polymer includes those called poly (oxyalkylene) glycol, polyoxyalkylene ether and polyalkylene oxide, and the polymer main chain has a polyether structure. Say. The alkylene glycol polymer is composed of a metal alkoxide, an organic metal compound, an inorganic metal salt, an alkali metal hydroxide, a third alcohol, polyhydric alcohols such as alcohol, ethylene glycol, glycerin and pentaerythritol as an initiator. In the presence of a catalyst such as an amine compound or an acid, it is synthesized by a method of polymerizing by ring-opening addition of a cyclic ether such as ethylene oxide or propylene oxide. Furthermore, it includes a polyether having a structure in which the hydrogen atom of the hydroxyl group at the terminal of the polymer is substituted with an alkyl group [in this case, the molecular weight of the obtained polymer is the molecular weight of the polymer before substitution with the alkyl group (the number of hydroxyl groups and functional groups). Estimated from conversion).

  Specific examples of the alkylene glycol polymer constituting the main skeleton of the specific crosslinking agent include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, and polytetramethylene glycol. These may be used alone or in combination of two or more. Further, among these, polyethylene glycol and polypropylene glycol are preferable in consideration of raw material acquisition, production cost, and the like.

  In the present invention, the weight average molecular weight of the specific crosslinking agent contained in the pressure-sensitive adhesive layer is 1000 to 5000, and more preferably 1000 to 3000. Considering that the contamination on the wafer surface tends to decrease as the molecular weight increases, it is preferable that the molecular weight is high. However, if the molecular weight is higher than this range, the production of the alkylene glycol polymer tends to be difficult. is there. If the molecular weight is lower than this range, contamination due to the pressure-sensitive adhesive layer tends to occur on the wafer surface (especially in the case of a wafer having a high bump electrode).

  In addition, the weight average molecular weight in the present invention is a value measured by gel permeation chromatography (GPC) method using polystyrene as a standard substance.

As content of the specific crosslinking agent in the coating liquid for adhesive layers, it is preferable that it is 0.5-20 mass parts with respect to 100 mass parts of said (ii) adhesive polymer and (c) crosslinking agent mentioned later. 1.0 to 15 parts by mass is more preferable, and 2.0 to 15 parts by mass is particularly preferable.
If the content of the specific cross-linking agent is low, the water resistance decreases, and water enters between the wafer surface and the pressure-sensitive adhesive layer during backside grinding, resulting in damage to the wafer or backside grinding debris. It tends to cause contamination. Further, if the content is large, contamination due to the pressure-sensitive adhesive layer may occur on the wafer surface.

<(C) Other cross-linking agents>
In the present invention, in addition to the above-mentioned pressure-sensitive adhesive polymer and specific cross-linking agent, other cross-linking agent having a molecular structure different from that of the specific cross-linking agent (hereinafter referred to as “other cross-linking agent” as appropriate) is contained.
The other crosslinking agent that can be used in the present invention is preferably a crosslinking agent having two or more crosslinking-reactive functional groups in one molecule, and is reacted with the functional group of the pressure-sensitive adhesive polymer to cause adhesion and aggregation. The power can be adjusted. Other cross-linking agents include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, resorcin diglycidyl ether, etc. Compounds, tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylolpropane toluene diisocyanate triadduct, isocyanate compounds such as polyisocyanate, trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri- β-aziridinylpropionate, N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxyl ), N, N′-hexamethylene-1,6-bis (1-aziridinecarboxamide), N, N′-toluene-2,4-bis (1-aziridinecarboxamide), trimethylolpropane-tri- Examples include aziridine compounds such as β- (2-methylaziridine) propionate, and melamine compounds such as hexamethoxymethylolmelamine.

These other crosslinking agents may be used alone or in combination of two or more.
Among other cross-linking agents, epoxy-based cross-linking agents have a slow cross-linking reaction, and if the reaction does not proceed sufficiently, the cohesive force of the pressure-sensitive adhesive layer becomes low, and depending on the shape of the semiconductor wafer surface, it can be attributed to the pressure-sensitive adhesive layer. Contamination may occur. Therefore, an aziridine-based compound that has a property as an amine when it contains a catalyst such as an amine as appropriate, or a monomer having a catalytic functional amine-based functional group is copolymerized with a pressure-sensitive adhesive polymer or a crosslinking agent is used. It is preferable to use a crosslinking agent in combination.

  It is preferable that the content of the other cross-linking agent is usually within a range in which the number of functional groups in the cross-linking agent does not exceed the number of functional groups in the pressure-sensitive adhesive polymer. However, when a functional group is newly generated by the cross-linking reaction or when the cross-linking reaction is slow, it may be contained excessively as necessary.

  The preferable content of the other cross-linking agent in the present invention is 0.5 to 10 parts by mass and preferably 0.5 to 7 parts by mass with respect to 100 parts by mass of the (B) pressure-sensitive adhesive polymer. When the content of the other cross-linking agent is less than 0.5 parts by mass, the cohesive force of the pressure-sensitive adhesive layer becomes insufficient, and the pressure-sensitive adhesive is applied to the wafer surface (particularly around the high bump electrode in the case of a wafer having a high bump electrode). It becomes easy to generate adhesive residue due to the layer, the adhesive strength is out of the scope of the present invention and becomes high, and when the adhesive film is peeled from the wafer surface, a peeling trouble occurs with the automatic peeling machine, or the wafer is completely removed. Or may be damaged. If the amount is too large, the adhesive force between the pressure-sensitive adhesive layer and the wafer surface is weakened, and water and grinding debris may enter during grinding, resulting in damage to the wafer and contamination of the wafer surface by the grinding debris.

  The coating solution for the pressure-sensitive adhesive layer includes the rosin-based and terpene resin-based coatings in order to adjust the adhesive properties in addition to the above-mentioned (a) pressure-sensitive adhesive polymer, (b) specific crosslinking agent, and (c) other crosslinking agent. An optional component such as a tackifier and various surfactants may be appropriately contained to such an extent that the effects of the present invention are not affected.

  Further, when the pressure-sensitive adhesive polymer is an emulsion liquid, a film-forming auxiliary such as diethylene glycol monoalkyl ether may be appropriately added to such an extent that the object of the present invention is not affected. Considering that diethylene glycol monoalkyl ether and its derivatives used as film-forming aids may cause contamination of the wafer surface in such a large amount that cleaning becomes impossible when contained in a large amount in the pressure-sensitive adhesive layer. In this case, it is preferable to use a material that volatilizes at the drying temperature after the pressure-sensitive adhesive coating, and to reduce the residual amount in the pressure-sensitive adhesive layer.

  In preparing the coating solution for the pressure-sensitive adhesive layer, when the pressure-sensitive adhesive polymer is an emulsion liquid, in order to facilitate the dispersion of the specific crosslinking agent in the coating solution for the pressure-sensitive adhesive layer, After dissolving the alkylene glycol polymer in a film-forming aid such as alkyl ether in advance, it is added to the pressure-sensitive adhesive polymer emulsion liquid, or a surfactant is used in combination as appropriate so as not to affect the purpose of the present invention. It is preferable.

The pressure-sensitive adhesive layer according to the present invention is an essential component, (b) a solution containing a pressure-sensitive adhesive polymer, (b) a specific cross-linking agent, (c) other cross-linking agent, and optional components added as necessary. Alternatively, a pressure-sensitive adhesive layer coating solution composed of an emulsion liquid can be prepared, and the pressure-sensitive adhesive layer coating solution can be used to form the coating solution by the following method i) or ii).
i) A method of forming a pressure-sensitive adhesive layer by cloth-drying the pressure-sensitive adhesive layer coating solution on one surface of a base film ii) A pressure-sensitive adhesive layer on one surface of a release film to be stuck on the pressure-sensitive adhesive layer A method of forming a pressure-sensitive adhesive layer by applying and drying a coating liquid and then transferring the pressure-sensitive adhesive layer onto a substrate film

  When the pressure-sensitive adhesive layer is formed by the above method i), it is preferable to attach a release film to the surface of the formed pressure-sensitive adhesive layer in order to protect it from contamination caused by the environment.

Whether the pressure-sensitive adhesive layer is formed by any of the methods i) and ii) is determined in consideration of the heat resistance of the base film and the release film and the contamination of the semiconductor wafer surface.
For example, when the heat resistance of the release film is superior to that of the base film, it is preferable to transfer to the base film after providing an adhesive layer on the surface of the release film. When the heat resistance of the release film is the same as that of the base film or the base film is superior, it is preferable to provide an adhesive layer on the surface of the base film and attach the release film to the surface.

  In consideration of the fact that the adhesive film for backside grinding of semiconductor wafers is attached to the surface of the semiconductor wafer through the surface of the adhesive layer exposed when the release film is peeled off, it prevents contamination of the semiconductor wafer surface by the adhesive layer. In order to achieve this, a release film having good heat resistance is used, and a pressure-sensitive adhesive coating solution is applied to the surface and dried to form a pressure-sensitive adhesive layer, which is then transferred to a substrate film (ii) Method) is preferred.

  As the base film in the present invention, a film obtained by molding a synthetic resin into a film is used. The base film may be a single layer or a laminate. The thickness of the base film is preferably 10 μm to 500 μm. More preferably, it is 70-500 micrometers. As the raw material resin for the base film, polyethylene (PE), polypropylene (PP), ethylene vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, polyvinyl chloride (PVC) , Synthetic resins such as polyamide and polyethylene terephthalate (PET). Among these, considering the protection performance of the wafer during back grinding, a raw material resin having a Shore D type hardness of 40 or less as defined in ASTM-D-2240-86 or JIS K-7215-1986 is particularly preferred. preferable. When these resins are molded into a film, stabilizers, lubricants, antioxidants, pigments, antiblocking agents, plasticizers, and the like may be added as necessary. When various additives such as a stabilizer are added at the time of molding the base film, the additive may move to the pressure-sensitive adhesive layer to change the characteristics of the pressure-sensitive adhesive or contaminate the wafer surface. In such a case, it is preferable to provide a barrier layer between the base film and the pressure-sensitive adhesive layer.

  In addition, when protecting the surface of a semiconductor wafer using an adhesive film for grinding the back surface of a semiconductor wafer even during an etching process using an etching solution applied after grinding the back surface of the semiconductor wafer, the chemical resistance is excellent. It is preferred to use a substrate film. For example, a chemical resistant film such as polypropylene is laminated on the surface of the base film opposite to the side on which the adhesive layer is provided.

  In order to improve the adhesive force between the base film and the pressure-sensitive adhesive layer, it is preferable that the surface of the base film on which the pressure-sensitive adhesive layer is provided is previously subjected to corona treatment or chemical treatment. Moreover, you may apply | coat a primer between a base film and an adhesive layer.

  The base film used in the present invention should be selected from those produced by known techniques such as a calendar method, a T-die extrusion method, and an inflation method in consideration of productivity, thickness accuracy of the obtained film, and the like. Can do.

  Examples of the release film that can be used in the present invention include synthetic resin films such as polypropylene and polyethylene terephthalate. It is preferable that the surface is subjected to silicone treatment or the like as necessary. The thickness of a peeling film is 10-200 micrometers normally, Preferably it is 30-100 micrometers.

As a method of applying the adhesive coating solution to one surface of the base film or the release film, conventionally known coating methods such as a roll coater method, a reverse roll coater method, a gravure roll method, a bar coat method, a comma coater method, a die coater Can be adopted.
Although there is no restriction | limiting in particular in the drying conditions of the apply | coated adhesive layer, Generally, it is preferable to dry for 10 seconds-10 minutes in the temperature range of 80-200 degreeC, and 15 seconds-5 at 80-170 degreeC. It is further preferred to dry for a minute.

  In order to sufficiently promote the cross-linking reaction between the specific cross-linking agent and the other cross-linking agent and the pressure-sensitive adhesive polymer, after the drying of the coating solution for the pressure-sensitive adhesive layer is completed, the pressure-sensitive adhesive film for back grinding of the semiconductor wafer is 40-80. You may heat at 5 degreeC about 5 to 300 hours.

  The thickness of the pressure-sensitive adhesive layer in the present invention is preferably in the range of 5 to 100 μm, and more preferably in the range of 10 to 70 μm. If the thickness of the pressure-sensitive adhesive layer is reduced, the water resistance will be poor and water will penetrate between the wafer surface and the pressure-sensitive adhesive layer during backside grinding, causing damage to the wafer or contamination of the wafer surface by grinding debris. There is a tendency. When the thickness is increased, it may be difficult to produce an adhesive film, or the productivity may be affected and the manufacturing cost may be increased.

  The adhesive strength of the adhesive film for backside grinding of a semiconductor wafer of the present invention can be adjusted as appropriate in consideration of the grinding conditions of the wafer surface, the diameter of the wafer, the thickness of the wafer after grinding, etc. If the adhesive strength is too low, The film tends to be difficult to attach to the surface, or water may penetrate between the wafer surface and the adhesive layer during backside grinding, causing damage to the wafer or contamination of the wafer surface by grinding debris, etc. is there. Also, if the adhesive strength is too high, when the adhesive film is peeled off from the wafer surface after backside grinding, peeling trouble may occur, such as an automatic peeling machine, and the wafer may be damaged. is there. Usually, it is preferably 0.4 to 400 N / 25 mm, more preferably 0.5 to 3.5 N / 25 mm, in terms of adhesive strength to the SUS304-BA plate.

  In the production of the adhesive film for back grinding of a semiconductor wafer of the present invention, from the viewpoint of preventing contamination of the surface of the semiconductor wafer, the production environment of all raw materials such as a base film, a release film and an adhesive main agent, adhesive application The preparation, storage, application and drying environment of the liquid is preferably maintained at a cleanness of class 1,000 or less as defined in US Federal Standard 209b.

[Semiconductor wafer backside grinding method]
Next, the back surface grinding method of the semiconductor wafer of this invention is demonstrated.
The method for grinding a back surface of a semiconductor wafer according to the present invention is characterized by using the above-mentioned pressure-sensitive adhesive film for grinding a back surface of a semiconductor wafer according to the present invention when grinding the back surface of the semiconductor wafer.

  As the details, first, the release film is peeled from the adhesive layer of the adhesive film of the present invention, the surface of the adhesive layer is exposed, and the integrated circuit of the semiconductor wafer is incorporated through the adhesive layer. Adhere to the surface. Next, the semiconductor wafer is fixed to the chuck table or the like of the grinding machine via the base film layer of the adhesive film, and the back surface of the semiconductor wafer is ground. After the grinding is finished, the adhesive film is peeled off. After the back surface grinding is completed, a chemical etching process may be performed before the adhesive film is peeled off. If necessary, after the adhesive film is peeled off, the surface of the semiconductor wafer is subjected to treatment such as water washing and plasma washing.

  In such a back surface grinding operation, the thickness of the semiconductor wafer before grinding is usually 500 μm to 1000 μm, but is usually ground to about 100 μm to 600 μm depending on the type of the semiconductor chip. The thickness of the semiconductor wafer before grinding is appropriately determined depending on the diameter and type of the semiconductor wafer, and the thickness after grinding is appropriately determined depending on the size of the chip to be obtained, the type of circuit, and the like.

  The operation of adhering the adhesive film to the semiconductor wafer may be performed manually, but is generally performed by an apparatus called an automatic pasting machine to which a roll-shaped adhesive film is attached. As such an automatic pasting machine, for example, there are ATM-1000B manufactured by Takatori Co., Ltd., ATM-1100, STL series manufactured by Teikoku Seiki Co., Ltd., and the like.

  As the back surface grinding method, a known grinding method such as a through-feed method or an in-feed method is employed. In each case, the grinding is performed while water is cooled on a semiconductor wafer and a grindstone. After the back grinding, chemical etching is performed as necessary. Chemical etching is performed on an etching solution selected from the group consisting of an acidic aqueous solution composed of a single or mixed solution of hydrofluoric acid, nitric acid, sulfuric acid, acetic acid and the like, or an alkaline aqueous solution such as a potassium hydroxide aqueous solution and a sodium hydroxide aqueous solution. It is performed by a method such as immersing a semiconductor wafer with the adhesive film attached. The etching is performed for the purpose of removing strain generated on the back surface of the semiconductor wafer, further thinning the wafer, removing an oxide film, etc., pretreatment when forming electrodes on the back surface, and the like. The etching solution is appropriately selected according to the above purpose.

  After the backside grinding and chemical etching are completed, the adhesive film is peeled off from the wafer surface. This series of operations may be performed manually, but is generally performed by a device called an automatic peeling machine. As such an automatic peeling machine, there are ATRM-2000B manufactured by Takatori Co., Ltd., ATRM-2100 manufactured by Takatori Co., Ltd., and STP series manufactured by Teikoku Seiki Co., Ltd.

  The wafer surface after peeling off the adhesive film is cleaned as necessary. Examples of the cleaning method include wet cleaning such as water cleaning and solvent cleaning, and dry cleaning such as plasma cleaning. In the case of wet cleaning, ultrasonic cleaning may be used in combination. These cleaning methods are appropriately selected depending on the contamination state of the wafer surface.

  According to the present invention, when the back surface of a semiconductor wafer is ground, the wafer surface caused by water entering between the wafer surface and the pressure-sensitive adhesive layer during grinding is also caused by grinding dust entering. No pollution occurs. Since the adhesive force is in an appropriate range, the wafer is not damaged when the adhesive film is peeled off from the surface of the semiconductor wafer, and there is no need to newly introduce equipment such as a light irradiation device into the process. Furthermore, since there is no adhesive residue after peeling off the adhesive film from the wafer, the surface of the semiconductor wafer is not contaminated.

  The semiconductor wafer to which the adhesive film for semiconductor wafer back grinding and the semiconductor wafer back grinding method using the semiconductor wafer of the present invention can be applied is not only a silicon wafer, but also germanium, gallium-arsenic, gallium-phosphorus, gallium-arsenic-aluminum, etc. A wafer is mentioned.

Hereinafter, the present invention will be described in more detail with reference to examples. In all the examples and comparative examples shown below, the preparation and application of the adhesive coating solution in an environment maintained at a cleanness of class 1,000 or less as defined in the US Federal Standard 209b, and the semiconductor silicon wafer Back grinding was performed.
The present invention is not limited to these examples. Various characteristic values shown in the examples were measured by the following methods.

(1) Adhesive strength (N / 25mm)
Except for the conditions specified below, all measurements were performed according to JIS Z-0237-1991 (2000 version). In an atmosphere of 23 ° C., the adhesive film obtained in Example or Comparative Example was attached to the surface of a 5 × 20 cm SUS304-BA plate (JIS G-4305-1991) through the adhesive layer. Left for 1 hour. One end of the sample was clamped, the peeling angle was 180 degrees, and the peeling speed was 300 mm / min. The stress at the time of peeling the sample from the surface of the SUS304-BA plate was measured and converted to an adhesive strength of N / 25 mm.

(2) Practical evaluation A semiconductor silicon wafer (diameter: 200 mm, thickness: 600 μm, scribe line width: 100 μm, scribe line depth: 5 μm) in which a 100 mm ² integrated circuit having a high bump electrode with a height of 8 μm is embedded to the periphery. The adhesive film obtained in the example or the comparative example was attached to the surface of), and the back surface of the semiconductor silicon wafer was ground while cooling with water using a grinder to a thickness of about 200 μm. .
Back surface grinding was performed on 10 semiconductor silicon wafers for each adhesive film, and the following evaluations <1> to <3> were performed.
Further, the following <4> was evaluated for wafer contamination.

<1> Status of wafer damage during backside grinding After grinding of the backside of the semiconductor silicon wafer, the status of damage to the semiconductor silicon wafer was evaluated by the number of damaged pieces.

<2> Water penetration during backside grinding For semiconductor silicon wafers that were not damaged by grinding, visually inspected whether water had entered between the front surface and the adhesive film, and the number of water intrusions evaluated.

<3> Damaged state of wafer during peeling of adhesive film After completion of observation of water intrusion, surface protective tape peeling machine {manufactured by Takatori Co., Ltd., MODEL: ATRM-2000B; peeling tape used: Highland Mark Filament Tape No. 897 [manufactured by Sumitomo 3M Co., Ltd.]} was peeled off, and the damage state at the time of peeling of the adhesive film was evaluated by the number of damaged pieces.

<4> Wafer contamination evaluation (ESCA measurement)
The contamination property of the silicon mirror wafer chip surface was evaluated by ESCA (ESCA-3200, manufactured by Shimadzu Corp.).
With the adhesive film for the sample attached to the entire surface of the silicon mirror wafer (diameter: 4 inches, thickness: 600 μm) to which no foreign matter has adhered via the adhesive layer, the temperature is 23 ± 2 ° C., relative humidity After leaving in an atmosphere adjusted to 50 ± 5% for 60 minutes, the adhesive film was peeled off from the silicon mirror wafer using a grinding machine [manufactured by DISCO Corporation, model: DFG-82IF / 8], and then diamond glass The silicon mirror wafer was cut into 1 cm square using a cutter (Inoue Seieido Co., Ltd.). Five samples were randomly collected from the cut 1 cm square silicon mirror wafers, and the ESCA analysis was performed on the surfaces under the following conditions to obtain the C / Si ratio (average value of five). The contamination state of the chip surface due to was measured.
<ESCA measurement conditions>
X-ray source: Mg—Kα ray (1252.0 eV), X-ray output: 300 W, measurement vacuum degree: 2 × 10 ⁻⁷ Pa or less, C / Si ratio; (carbon peak area) / (silicon peak area) .
<C / Si ratio evaluation method>
The C / Si ratio on the surface of the silicon mirror wafer before adhering the adhesive film is 0.10 (blank value).
As an evaluation standard, a chip surface having a C / Si ratio of about 0.10 to 0.20 on the surface of the silicon mirror wafer chip after the adhesive film is attached is evaluated as “good” as no contamination. A chip surface exceeding 1 was evaluated as “poor” as being contaminated.

[Example 1]
(Preparation of base film)
An ethylene-vinyl acetate copolymer resin having a Shore D hardness of 35 was formed into a film having a thickness of 200 μm using a T-die extruder. At this time, the corona treatment was applied to the side on which the pressure-sensitive adhesive layer was formed. The thickness variation of the obtained film was within ± 1.5%.

(Synthesis of adhesive main agent)
In deionized water, in the presence of polyoxyethylene nonylphenyl ether (surfactant), 82 parts by weight of butyl acrylate, 12 parts by weight of methyl methacrylate, 3% by weight of 2-hydroxyethyl methacrylate, 2% by weight of acrylic acid Then, the copolymer was copolymerized with 1 weight of acrylic acid amide by a conventional method to obtain a pressure-sensitive adhesive polymer emulsion (pressure-sensitive adhesive main agent) containing 40% by mass of pressure-sensitive adhesive polymer A as a solid content.

(Synthesis of specific crosslinking agent (1))
A specific crosslinking agent (1) (having an epoxy-based terminal functional group at both ends) by condensation reaction of polypropylene glycol having a weight average molecular weight of 3000 (trade name “MN-3050”, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) and epichlorohydrin. Thus, polypropylene glycol having a weight average molecular weight of 3000 was obtained.

(Preparation of coating solution for adhesive layer)
To 100 parts by mass of the resulting adhesive main component (adhesive polymer concentration 40% by mass), 1.0 part by mass of an aziridine-based crosslinking agent [Nippon Shokubai Chemical Co., Ltd., Chemite PZ-33], specific crosslinking agent (1 ) 10 parts by mass was added to obtain an adhesive coating solution.

(Preparation of adhesive film)
The obtained coating solution for pressure-sensitive adhesive layers was applied to a polypropylene film (release film, thickness: 50 μm) using a roll coater, and dried at 120 ° C. for 5 minutes to provide a pressure-sensitive adhesive layer having a thickness of 40 μm. The corona-treated surface of the above-mentioned ethylene-vinyl acetate copolymer film (base film) was bonded to this and pressed to transfer the pressure-sensitive adhesive layer. After the transfer, the film was heated at 60 ° C. for 48 hours, and then cooled to room temperature to produce an adhesive film for grinding a semiconductor wafer back surface.

(Evaluation of adhesive film)
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 1.0 N / 25 mm.
No wafers were damaged during grinding, and no water intrusion was observed between the wafer and the adhesive film after grinding. None of the wafers were damaged during the peeling of the adhesive film.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.17, and it was observed that the contamination was “good”.
The obtained results are shown in Table 1.

[Example 2]
In the preparation of the coating solution for the pressure-sensitive adhesive layer of Example 1, instead of 10 parts by mass of the specific crosslinking agent (1), the specific crosslinking agent (2) (Epiol E-1000, manufactured by NOF Corporation) A pressure-sensitive adhesive film for grinding a semiconductor wafer back surface was produced in the same manner as in Example 1 except that 15 parts by mass of polyethylene glycol having a weight average molecular weight of 1500 having a terminal functional group was used.
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 0.8 N / 25 mm.
No wafers were damaged during grinding, and no water intrusion was observed between the wafer and the adhesive film after grinding. None of the wafers were damaged during the peeling of the adhesive film.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.18, and it was observed that the contamination was “good”.
The obtained results are shown in Table 1.

[Example 3]
In the preparation of the coating solution for the pressure-sensitive adhesive layer of Example 1, 7 parts by mass of an epoxy-based crosslinking agent (Denacol EX-614, manufactured by Nagase Kasei Kogyo Co., Ltd.) was used instead of 1.0 part by mass of the aziridine-based crosslinking agent. Except that, an adhesive film for grinding a semiconductor wafer back surface was produced in the same manner as in Example 1.
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 1.8 N / 25 mm.
No wafers were damaged during grinding, and no water intrusion was observed between the wafer and the adhesive film after grinding. None of the wafers were damaged during the peeling of the adhesive film.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.17, and it was observed that the contamination was “good”.
The obtained results are shown in Table 1.

[Example 4]
In the preparation of the coating solution for the pressure-sensitive adhesive layer in Example 1, the semiconductor wafer was all manufactured in the same manner as in Example 1 except that the amount of the aziridine-based crosslinking agent was changed from 1.0 part by mass to 0.5 part by mass. An adhesive film for back grinding was produced.
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 2.5 N / 25 mm.
No wafers were damaged during grinding, and no water intrusion was observed between the wafer and the adhesive film after grinding. None of the wafers were damaged during the peeling of the adhesive film.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.18, and it was observed that the contamination was “good”.
The obtained results are shown in Table 1.

[Comparative Example 1]
In the preparation of the coating solution for the pressure-sensitive adhesive layer in Example 1, a semiconductor wafer back grinding pressure-sensitive adhesive film was produced in the same manner as in Example 1 except that the specific crosslinking agent (1) was not used.
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 3.5 N / 25 mm.
No wafers were damaged during grinding, and no water intrusion was observed between the wafer and the adhesive film after grinding. Five wafers were damaged during the peeling of the adhesive film.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.15, and it was observed that the contamination was “good”.
The obtained results are shown in Table 2.

[Comparative Example 2]
In the preparation of the coating solution for the pressure-sensitive adhesive layer of Example 1, 1.0 part by mass of the specific crosslinking agent (1) was compared with the comparative crosslinking agent (1) (polypropylene glycol having hydroxy groups at both ends and having a weight average molecular weight of 3000. ) An adhesive film for grinding a semiconductor wafer back surface was manufactured in the same manner as in Example 1 except that the content was changed to 10 parts by mass.
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 1.2 N / 25 mm.
No wafers were damaged during grinding, and no water intrusion was observed between the wafer and the adhesive film after grinding. None of the wafers were damaged during the peeling of the adhesive film.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.4, and it was observed that the contamination was “poor”.
The obtained results are shown in Table 2.

[Comparative Example 3]
In the preparation of the coating solution for the pressure-sensitive adhesive layer of Example 1, the specific cross-linking agent (2) (with an epoxy-based terminal functional group (glycidyl group)) instead of 10 parts by mass of the specific cross-linking agent (1) Except for using 10 parts by mass of polypropylene glycol having a molecular weight of 300, an adhesive film for grinding a semiconductor wafer back surface was produced in the same manner as in Example 1.
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 3.2 N / 25 mm.
No wafers were damaged during grinding, and no water intrusion was observed between the wafer and the adhesive film after grinding. Three wafers were damaged during the peeling of the adhesive film.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.35, and it was observed that the contamination was “poor”.
The obtained results are shown in Table 2.

[Comparative Example 4]
In the preparation of the coating solution for the pressure-sensitive adhesive layer of Example 1, the semiconductor wafer was all manufactured in the same manner as in Example 1 except that the amount of the aziridine-based crosslinking agent was changed from 1.0 part by weight to 0.1 part by weight. An adhesive film for back grinding was produced.
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 4.5 N / 25 mm.
No wafers were damaged during grinding, and no water intrusion was observed between the wafer and the adhesive film after grinding. Five wafers were damaged during the peeling of the adhesive film.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.61, and it was observed that the contamination was “bad”.
The obtained results are shown in Table 2.

[Comparative Example 5]
In the preparation of the coating solution for the pressure-sensitive adhesive layer of Example 1, the semiconductor was prepared in the same manner as in Example 1 except that 18 parts by mass of the epoxy-based crosslinking agent was used instead of 1.0 part by mass of the aziridine-based crosslinking agent. An adhesive film for wafer back grinding was produced.
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 0.5 N / 25 mm.
Two wafers were damaged during grinding due to water intrusion. After the grinding, water intrusion was observed on all the eight wafers that were not damaged.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.15, and it was observed that the contamination was “good”.
The obtained results are shown in Table 2.

[Comparative Example 6]
In the preparation of the coating solution for the pressure-sensitive adhesive layer of Example 1, the semiconductor wafer back surface grinding was performed in the same manner as in Example 1 except that the amount of the specific crosslinking agent (1) used was changed from 10 parts by mass to 25 parts by mass. An adhesive film was produced.
About the obtained adhesive film, adhesive force (N / 25mm) was measured by the said method, and also practical evaluation was performed.
The adhesive force of the obtained adhesive film was 0.3 N / 25 mm.
Three wafers were damaged during grinding due to water intrusion. After the grinding, water intrusion was observed on all nine wafers that were not damaged.
The C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.13, and it was observed that the contamination was “poor”.
The obtained results are shown in Table 2.

[Comparative Example 7]
In the preparation of the coating solution for the pressure-sensitive adhesive layer of Example 1, the cross-linking agent for comparison (2) (epoxy terminal functional group (glycidyl group) having a weight average molecular weight instead of 10 parts by mass of the specific cross-linking agent (1) A coating solution for the pressure-sensitive adhesive layer was prepared in the same manner as in Example 1 except that 10 parts by mass of (10000 polypropylene glycol) was used.
However, for Comparative Example 7, the viscosity of the coating solution for the adhesive layer after preparation was as high as 1000 m · Pas or more, and could not be applied on the corona-treated surface of the EVA film as in Example 1 with a roll coater. The target film for processing a semiconductor wafer could not be obtained.
The obtained results are shown in Table 2.

以上のように、実施例の粘着フィルムは、半導体ウエハの裏面を研削するに際し、裏面の研削応力に起因する研削中のウエハ破損が起こらないばかりでなく、ウエハ表面と粘着剤層との間に水及び研削屑が浸入することに起因するウエハの破損及びウエハ表面の汚染も起こらない。また、粘着力が適正な範囲にあるため、粘着フィルムをウエハから剥離する際のウエハの破損が起こらず、光照射装置等の設備を新たに導入する必要もない。さらに、粘着フィルムをウエハから剥離した後における糊残りや、粘着剤層からのブリードアウトもないので、半導体ウエハの表面を汚染することがない。

As described above, when the back surface of the semiconductor wafer is ground, the pressure-sensitive adhesive film according to the embodiment not only causes the wafer damage during grinding due to the grinding stress on the back surface, but also between the wafer surface and the pressure-sensitive adhesive layer. There is no wafer breakage and no contamination of the wafer surface due to the ingress of water and grinding debris. Further, since the adhesive strength is in an appropriate range, the wafer is not damaged when the adhesive film is peeled off from the wafer, and it is not necessary to newly introduce equipment such as a light irradiation device. Furthermore, since there is no adhesive residue after peeling the adhesive film from the wafer and no bleed out from the adhesive layer, the surface of the semiconductor wafer is not contaminated.

Claims (2)

An adhesive film for grinding a back surface of a semiconductor wafer, which is adhered to the circuit forming surface when grinding the back surface of a semiconductor wafer, comprising the following components (a) and (c) A pressure-sensitive adhesive containing 0.5 to 20 parts by mass of the following component (b) with respect to 100 parts by mass of the total, and 0.5 to 10 parts by mass of the component (c) with respect to 100 parts by mass of the component (b) below. A pressure-sensitive adhesive film for grinding a back surface of a semiconductor wafer, comprising a pressure-sensitive adhesive layer formed using a layer coating solution.
(I): Acrylic acid alkyl ester-based pressure-sensitive adhesive polymer having a functional group capable of reacting with a crosslinking agent (b): An alkylene glycol polymer having 2 to 4 carbon atoms of an alkylene group as a main skeleton, and at least two at the end A crosslinking agent having a glycidyl group and having a weight average molecular weight in the range of 1000 to 5000 (c): other crosslinking agent having a molecular structure different from that of the component (b)   A method for grinding a back surface of a semiconductor wafer, comprising sticking the pressure-sensitive adhesive film according to claim 1 on a circuit forming surface of a semiconductor wafer, grinding the back surface of the semiconductor wafer, and peeling the pressure-sensitive adhesive film after completion of the grinding.