JP6121003B2 - Semiconductor wafer surface protecting adhesive film, semiconductor wafer protecting method using adhesive film, and semiconductor device manufacturing method - Google Patents

Description

  The present invention relates to an adhesive film for protecting a surface of a semiconductor wafer, a method for protecting a semiconductor wafer using the adhesive film, and a method for manufacturing a semiconductor device. Specifically, in the process of manufacturing a semiconductor integrated circuit, when a semiconductor non-circuit-formed surface (hereinafter referred to as a wafer back surface) is ground to thin the semiconductor wafer, the semiconductor wafer is prevented from being damaged or contaminated. In addition, a semiconductor wafer surface protecting pressure-sensitive adhesive film adhered so that a pressure-sensitive adhesive layer is in contact with a circuit forming surface (hereinafter referred to as a wafer surface) of a semiconductor wafer, and a method for protecting a semiconductor wafer and a method for manufacturing a semiconductor device using the same About.

  Usually, after slicing a high-purity silicon single crystal or the like into a wafer, a semiconductor device incorporates an integrated circuit by ion implantation, etching or the like, and further, grinding, wrapping, and wrapping the back surface of the wafer after the integrated circuit is incorporated. It is manufactured by a method of dicing into chips after passing through a back surface grinding process for thinning the wafer by mechanical grinding by means such as polishing. Conventionally, during these processes, when the back surface of a wafer is ground, an adhesive film for protecting the surface of a semiconductor wafer is used in order to prevent damage and contamination of the semiconductor wafer.

  Specifically, a semiconductor wafer surface protecting adhesive film is adhered to the wafer surface via the adhesive layer to protect the wafer surface, and then the wafer back surface is mechanically ground. After grinding, chemical processing on the back surface of the wafer may be continued as necessary. After these back surface treatment steps are completed, the adhesive film is peeled off from the wafer surface.

  One of the performances required for such an adhesive film for protecting the surface of a semiconductor wafer is the invasion prevention performance of cooling water (hereinafter referred to as grinding water) used when grinding the back surface of the wafer. On the wafer surface, there is a recess recessed in a groove shape from the outermost periphery of the wafer due to a coating layer such as polyimide, a deposited film such as a silicon oxide film and a silicon nitride film, and a scribe line (dicing street). Usually, the depth of the recessed part recessed in the groove shape is about 2 μm to 20 μm. When grinding the back surface of the wafer where the concave portion existing on the wafer surface reaches the outermost peripheral portion of the wafer, if the adhesive layer is not sufficiently adhered to the concave portion, the grinding water enters through the concave portion. Sometimes. Once the grinding water enters between the wafer surface and the adhesive film through the recess, the adhesive layer peels off from the wafer surface due to the invading grinding water, and the penetration of the grinding water between the wafer surface and the adhesive layer accelerates. And the entire surface of the integrated circuit tends to be contaminated by grinding debris that has entered with the grinding water. In the worst case, the adhesive film for surface protection may be peeled off during back surface grinding due to the ingress of grinding water, resulting in damage to the wafer.

  In order to prevent such a 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 is taken. 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 wafer thickness and surface shape, the adhesive film is removed from the wafer surface after back grinding. When peeling, an automatic peeling machine may cause a peeling trouble to deteriorate workability, and sometimes the wafer is completely damaged. In addition, depending on the type of wafer, the depth of the recess exceeds 20 μm, and in order to cope with such a wafer, if the thickness of the adhesive layer is further increased, the production of an adhesive film However, it is difficult to provide an inexpensive pressure-sensitive adhesive film, which is not a realistic solution.

As a means for solving such a problem, for example, the minimum value (G′min) of the storage elastic modulus (G ′) at 50 to 100 ° C. of the pressure-sensitive adhesive layer (B) is 0.07 to 5 MPa, and the intermediate layer The storage elastic modulus at 50 ° C. of at least one layer (C) is 0.001 MPa or more and less than 0.07 MPa, and the thickness (tb, unit: μm) of the pressure-sensitive adhesive layer (B) and the storage elastic modulus are set as follows. An adhesive film for protecting a semiconductor wafer surface is disclosed in which the total thickness (tc, unit: μm) of the intermediate layer (C) has a relationship of Formula (1): tc ≧ 3tb (for example, (See Kaikai 2003-173994).

  The pressure-sensitive adhesive film disclosed in Japanese Patent Application Laid-Open No. 2003-173994 can follow unevenness with a projection height as high as 200 μm, such as a flip-chip mounted bump electrode, and is said to have excellent adhesion.

  In addition, the pressure-sensitive adhesive layer has a functional group capable of reacting with a crosslinking agent, and the temperature at which the dynamic viscoelasticity tan δ is maximized is −50 to 5 ° C. 10 to 100 parts by weight of the polymer (B) having a functional group capable of reacting and the temperature at which the tan δ of dynamic viscoelasticity is maximized exceeds 5 ° C. and is 50 ° C. or less, and the polymer (A) and (B) 0.1 to 10 parts by weight of a crosslinking agent (C) having two or more crosslinking reactive functional groups in one molecule with respect to 100 parts by weight of the total amount, and the thickness of the pressure-sensitive adhesive layer is 5 to 50 μm An adhesive film for protecting a semiconductor wafer surface is disclosed (for example, see JP-A-2004-6746).

  The pressure-sensitive adhesive film disclosed in Japanese Patent Application Laid-Open No. 2004-6746 is said to have excellent adhesion, damage prevention, and non-contamination.

  In recent years, there has been an increasing demand for thinner layers for semiconductor integrated circuit chips such as for portable information terminals and IC cards. The semiconductor wafer used for the above applications is generally thinned to 200 μm or less by back surface grinding, and in some cases, the back surface is ground to about 50 μm. For this reason, it can be said that the risk of contamination and breakage of the wafer is further increased under grinding conditions in which the wafer is thinned to 200 μm or less.

In addition, along with higher performance of chips and technological innovation in semiconductor manufacturing processes, the shape of the surface of integrated circuits tends to become more complex, and some recesses on the wafer surface have a depth exceeding 20 μm. Yes. Some of them reach up to about 50 μm. Therefore, the adhesive film for protecting a semiconductor wafer surface is required to have excellent adhesion to a wafer surface having irregularities.
On the other hand, there are various process conditions for peeling an adhesive film from a wafer, and it is also required to exhibit good peelability in a wide peel speed range.

  Under such circumstances, in order to more effectively suppress damage and contamination of the semiconductor wafer, the problem of the present invention is to maintain adhesion to the wafer surface while maintaining non-contamination on the wafer surface. An object of the present invention is to provide an adhesive film for protecting a surface of a semiconductor wafer that is excellent and has excellent releasability when peeled from a semiconductor wafer, a method for protecting a semiconductor wafer using the same, and a method for manufacturing a semiconductor device.

  Means for solving the above problems are as follows.

<1> a base film;
Having a pressure-sensitive adhesive layer on one surface of the base film,
The pressure-sensitive adhesive layer has a polymer (A) having a maximum dynamic viscoelasticity tan δ (Ta) exceeding 0 ° C. and a temperature (Tb) at which the dynamic viscoelastic tan δ is maximum 0 ° C. or less. The polymer (B) is a mass ratio (A / B): 57/43 to 90/10,
The polymer (A) contains 22 mass% to 30 mass% of structural units derived from acrylonitrile or methacrylonitrile,
An adhesive film for protecting the surface of a semiconductor wafer having an adhesive strength of 1.0 N / 25 mm or more at a peeling speed of 10 mm / min.

<2> The adhesive film for protecting a semiconductor wafer surface according to <1>, wherein an adhesive force at a peeling rate of 10 mm / min to 1000 mm / min is 4.0 N / 25 mm or less.

<3> The semiconductor wafer surface according to <1> or <2>, wherein the base film includes at least one layer selected from an ethylene-vinyl acetate copolymer layer, a polyolefin layer, and a polyester layer. Protective adhesive film.

<4> a first polymerization step in which a first polymerization material containing a raw material monomer for forming one of the polymer (A) and the polymer (B) is supplied to a reaction vessel to start polymerization; ,
After the first polymerization step, a second polymerization material containing a raw material monomer for forming the other of the polymer (A) and the polymer (B) is further supplied to the reaction vessel for polymerization. <1> to <3>, wherein the pressure-sensitive adhesive layer is formed using a liquid containing the polymer (A) and the polymer (B) obtained by a method comprising a second polymerization step. The adhesive film for semiconductor wafer surface protection of any one of these.

<5> The above <1> to <3, wherein the pressure-sensitive adhesive layer is formed using a mixed liquid obtained by mixing a liquid containing the polymer (A) and a liquid containing the polymer (B). > The adhesive film for semiconductor wafer surface protection of any one of>.

<6> An attaching step of attaching the adhesive layer in the adhesive film for protecting a semiconductor wafer surface according to any one of <1> to <5> to a circuit forming surface of the semiconductor wafer; and
A grinding step of grinding a circuit non-formed surface in the semiconductor wafer to which the adhesive film for protecting the surface of the semiconductor wafer is attached;
A peeling step of peeling the semiconductor wafer surface protecting adhesive film from the semiconductor wafer;
A method for protecting a semiconductor wafer, comprising:

<7> An attaching step of attaching the adhesive layer in the adhesive film for protecting a semiconductor wafer surface according to any one of <1> to <5> to a circuit forming surface of the semiconductor wafer; and
A grinding step of grinding a circuit non-formed surface in the semiconductor wafer to which the adhesive film for protecting the surface of the semiconductor wafer is attached;
A peeling step of peeling the semiconductor wafer surface protecting adhesive film from the semiconductor wafer;
A method for manufacturing a semiconductor device, comprising:

  According to the present invention, while maintaining non-contamination on the surface of the semiconductor wafer, the semiconductor wafer has excellent adhesion even when time passes after being attached to the wafer surface, and also has excellent releasability when peeling from the semiconductor wafer. An adhesive film for surface protection, a method for protecting a semiconductor wafer using the same, and a method for manufacturing a semiconductor device can be provided. Since the adhesive film for protecting a semiconductor wafer surface of the present invention has adhesion and easy peelability, it can be suitably used for a semiconductor wafer having a more complicated surface shape.

Hereinafter, the present invention will be described in detail.
The pressure-sensitive adhesive film for protecting a semiconductor wafer surface of the present invention (hereinafter sometimes abbreviated as pressure-sensitive adhesive film) has a base film and a pressure-sensitive adhesive layer on one surface of the base film, and the pressure-sensitive adhesive layer A polymer (A) having a temperature (Ta) at which tan δ of dynamic viscoelasticity is maximum exceeds 0 ° C. and a polymer having a temperature (Tb) at which tan δ of dynamic viscoelasticity is maximum of 0 ° C. or less. (B) is contained in a mass ratio (A / B): 57/43 to 90/10, and the polymer (A) contains 22% by mass to 30% by mass of a structural unit derived from acrylonitrile or methacrylonitrile. Including. The adhesive film for protecting a semiconductor wafer surface of the present invention having such a configuration has an adhesive strength of 1.0 N / 25 mm or more at a peeling speed of 10 mm / min.
In addition, the adhesive layer should just have on the at least one surface of a base film, and may have it on both surfaces.

  By adopting such a configuration, while maintaining non-contamination on the wafer surface, even when time has elapsed after being attached to the wafer surface, there is no lifting from the wafer surface, excellent adhesion, and peeling from the semiconductor wafer. A pressure-sensitive adhesive film having excellent peelability can be obtained. Since the adhesive film of the present invention is sufficiently adhered when adhered to a semiconductor wafer, it can extremely effectively prevent contamination of the semiconductor wafer surface and damage to the semiconductor wafer due to ingress of grinding water and grinding debris. Can do. Moreover, when peeling the adhesive film of this invention, it can peel with moderate adhesive force and can prevent damage to a semiconductor wafer. Although it is not certain about the relationship between the above-described configuration of the present invention and the effects achieved by adopting them, it is estimated as follows.

  Of the at least two types of polymers contained in the pressure-sensitive adhesive layer, the polymer (B) having a maximum dynamic viscoelasticity tan δ of 0 ° C. or lower is suitable for the pressure-sensitive adhesive layer. And has excellent adhesion to the recesses present on the wafer surface. In addition, the polymer (A) having a temperature at which tan δ of dynamic viscoelasticity exceeds 0 ° C. is contained in a mass ratio (A / B): 57/43 to 90/10 with respect to the polymer (B). Then, the peelability is improved while maintaining the adhesion. This is considered because the toughness is improved by containing the polymer (A) in the above range.

  In addition, the temperature (Ta) and (Tb) at which the dynamic viscoelasticity tan δ of the polymers (A) and (B) in the present invention is maximized means a value measured according to the method described in Examples described later. .

  Moreover, when the polymer (A) contains 22% by mass or more of a structural unit derived from acrylonitrile or methacrylonitrile, the peelability is excellent, and when it is 30% by mass or less, the toughness is moderately suppressed and the adhesiveness is excellent.

  The pressure-sensitive adhesive film for protecting a semiconductor wafer surface of the present invention is produced by forming a pressure-sensitive adhesive layer on at least one surface of a base film. Usually, from the viewpoint of preventing contamination, a release film called a separator is stuck on the surface of the pressure-sensitive adhesive layer until it is used immediately after being manufactured. From the viewpoint of preventing contamination of the wafer surface with the pressure-sensitive adhesive layer, a pressure-sensitive adhesive coating solution is applied to one side of the release film and dried to form a pressure-sensitive adhesive layer. A method of transferring to at least one side is preferable.

  As the base film of the adhesive film for protecting a semiconductor wafer surface of the present invention, a film obtained by molding a synthetic resin into a film is preferably used.

  Examples of the raw material resin used for the base film include polyolefins such as polyethylene, polypropylene, polybutene, and ethylene-α-olefin copolymers, polymethylpentene, ethylene-vinyl acetate copolymer (EVA), and ethylene-ethyl acrylate. Copolymer, ethylene-acrylic acid ester-maleic anhydride copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-methacrylic acid copolymer, ionomer resin, ethylene-propylene copolymer, butadiene elastomer, styrene- Thermoplastic elastomers such as isoprene elastomers, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyamide resins, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene Polyesters such as polybutylene terephthalate (PBT), polyimide, polyether sulfone (PES), polyether ether ketone (PEEK), polycarbonate, polyurethane, acrylic resin, fluorine-based resins, cellulose-based resin.

  Among these raw material resins, ethylene-vinyl acetate copolymer, low density polyethylene, polypropylene, ethylene-α-olefin copolymer (3 to 8 carbon atoms of α-olefin), polyethylene terephthalate, polyethylene naphthalate, and the like are preferable. An ethylene-vinyl acetate copolymer is more preferable. More preferably, it is an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of about 5% by mass to 50% by mass.

  The base film may be a single layer or a laminate of two or more layers. The base film preferably includes at least one layer selected from an ethylene-vinyl acetate copolymer layer, a polyolefin layer, and a polyester layer. Examples of the polyolefin layer include polyethylene, polypropylene, and an ethylene-α-olefin copolymer (α-olefin having 3 to 8 carbon atoms). Examples of the polyester layer include polyethylene terephthalate and polyethylene naphthalate. Among them, it is preferable to include at least one layer selected from an ethylene-vinyl acetate copolymer layer, a polypropylene layer, a polyethylene terephthalate layer, and a polyethylene naphthalate layer, and more preferably to include an ethylene-vinyl acetate copolymer layer. preferable. Further, the base film may be a thermoplastic resin molded or processed, and may be a cured curable resin after film formation.

  When the base film is a laminate of two or more films, a typical method for laminating a synthetic resin molded into a film is to extrude the synthetic resin with a T-die extruder. And a method of laminating with one surface of a synthetic resin film prepared in advance. In order to increase the adhesion between each layer of these synthetic resin films, the surface on the side where each synthetic resin film is laminated is subjected to an easy adhesion treatment such as corona discharge treatment or chemical treatment, or an adhesive layer between the two layers. May be provided.

  When the base film is a single layer, the synthetic resin is formed into a film by a method such as calendering, T-die extrusion, inflation, casting, etc. The thickness can be appropriately selected in consideration of the productivity and the thickness accuracy of the obtained film.

  When the base film is thin, the property of maintaining the form of the adhesive film tends to be inferior, and the workability when handling the adhesive film may be deteriorated accordingly. When the thickness is increased, the productivity of the base film is affected and the manufacturing cost is increased. From this viewpoint, the total thickness of the base film is preferably 10 μm to 300 μm, and more preferably 50 μm to 200 μm.

  In order to improve the adhesive force between the base film and the pressure-sensitive adhesive layer, it is preferable to perform corona discharge treatment or chemical treatment in advance on the surface of the base film on which the pressure-sensitive adhesive layer is provided. For the same purpose, an undercoat layer may be formed between the base film and the pressure-sensitive adhesive layer.

  Examples of the release film include synthetic resin films such as polyethylene film, polypropylene film, polyethylene terephthalate film (hereinafter referred to as PET film). It is preferable that the surface is subjected to a release treatment such as silicone treatment as necessary. The thickness of the release film is usually about 10 μm to 1000 μm.

  The pressure-sensitive adhesive layer of the semiconductor wafer surface protecting pressure-sensitive adhesive film of the present invention has, as its basic component, a polymer (A) having a temperature (Ta) at which tan δ of dynamic viscoelasticity reaches a maximum of 0 ° C. and a dynamic viscosity. A polymer (B) having a temperature (Tb) at which elastic tan δ is maximized is 0 ° C. or less. Each of the polymer (A) and the polymer (B) preferably has a functional group capable of reacting with a crosslinking agent. The pressure-sensitive adhesive layer preferably further contains a cross-linking agent (C) having two or more cross-linking reactive functional groups in one molecule for controlling the cohesive force and the pressure-sensitive adhesive force.

  In order to achieve the object of the present invention to improve both the adhesion when a time has elapsed from pasting to the wafer surface and the releasability from the semiconductor wafer while maintaining non-contamination on the wafer surface. In the pressure-sensitive adhesive layer of the semiconductor wafer surface protecting pressure-sensitive adhesive film, the polymer (A) is contained in a mass ratio (A / B): 57/43 to 90/10 with respect to the polymer (B). The mass ratio (A / B) is more preferably 60/40 to 90/10, still more preferably 65/35 to 85/15, and most preferably 66/34 to 80/20. When the content of the polymer (A) is increased, the adhesiveness of the pressure-sensitive adhesive layer to the wafer surface is lowered, and the grinding water is liable to enter the recesses on the wafer surface, which may lead to contamination and breakage of the semiconductor wafer. When there is little content of a polymer (A), the peelability from a semiconductor wafer falls. In addition, the pressure-sensitive adhesive layer lacks the toughness, and the pressure-sensitive adhesive layer cannot withstand the load that causes the adhesive film to peel off the pressure-sensitive adhesive film on the pressure-sensitive adhesive layer. May also cause contamination and breakage of the semiconductor wafer.

  Examples of the polymer (A) and the polymer (B) include natural rubber, synthetic rubber, silicone polymer, and acrylic polymer. Both the polymer (A) and the polymer (B) are acrylic heavy. It is preferably a coalescence. As the acrylic polymer, a copolymer containing a structural unit derived from an alkyl acrylate ester as a main component is preferable.

  The acrylic acid alkyl ester preferably includes an acrylic acid alkyl ester, a methacrylic acid alkyl ester, and a mixture thereof as a main monomer. Examples of the alkyl acrylate and alkyl methacrylate include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, methacrylic acid Examples include 2-ethylhexyl and octyl acrylate. These may be used alone or in combination of two or more.

  The polymer (A) contains 22% by mass to 30% by mass and preferably 24% by mass to 30% by mass of a structural unit derived from acrylonitrile or methacrylonitrile. When the structural unit derived from acrylonitrile or methacrylonitrile is 22% by mass or more, the peelability is excellent, and when it is 30% by mass or less, the toughness is moderately suppressed and the adhesion is excellent. Among them, it is more preferable to use acrylonitrile in the above range because the contamination tends to be good.

  The polymer (A) and the polymer (B) preferably have a functional group capable of reacting with a crosslinking agent. Examples of the functional group capable of reacting with the crosslinking agent include a hydroxyl group, a carboxyl group, an epoxy group, and an amino group. As a method for introducing functional groups capable of reacting with these crosslinking agents into the polymer (A) or the polymer (B), these functional groups are used when polymerizing the polymer (A) or the polymer (B). In general, a method of copolymerizing a comonomer having the following formula is used.

  Examples of the comonomer having a functional group include acrylic acid, methacrylic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, maleic acid, itaconic acid monoalkyl ester, mesaconic acid monoalkyl ester, citraconic acid monoalkyl ester, and fumaric acid. Acid monoalkyl ester, maleic acid monoalkyl ester, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, n-butylaminoethyl Examples include acrylate and n-butylaminoethyl methacrylate.

  One of these comonomers may be copolymerized with an acrylic acid alkyl ester, or two or more may be copolymerized. The use amount (copolymerization amount) of the comonomer having a functional group capable of reacting with the cross-linking agent is 1% by mass to 40% by mass in the total amount of all monomers used as a raw material for the polymer (A) or the polymer (B). % Is preferred.

  In the present invention, in addition to the comonomer having a functional group capable of reacting with the alkyl ester of the polymer (A) and the polymer (B) and the crosslinking agent, the specific comonomer having a property as a surfactant. (Hereinafter referred to as a polymerizable surfactant) may be copolymerized. The polymerizable surfactant has a property of copolymerizing with an acrylic acid alkyl ester and a comonomer having a functional group, and has an action as an emulsifier when emulsion polymerization is performed. In the case of using a pressure-sensitive adhesive polymer obtained by emulsion polymerization using a polymerizable surfactant, the surface of the wafer is usually not contaminated by the surfactant. Even when slight contamination due to the pressure-sensitive adhesive layer occurs, it can be easily removed by washing the wafer surface with water.

  Examples of such polymerizable surfactants include, for example, those obtained by introducing a polymerizable 1-propenyl group into the benzene ring of polyoxyethylene nonylphenyl ether [Daiichi Kogyo Seiyaku Co., Ltd .; trade name: Aqualon RN-10, RN-20, RN-30, RN-50, etc.], a polyoxyethylene nonylphenyl ether sulfate ester ammonium salt introduced with a polymerizable 1-propenyl group in the benzene ring Manufactured by Ichi Kogyo Seiyaku Co., Ltd .; trade names: Aqualon HS-10, HS-20, etc.] and sulfosuccinic acid diesters having a polymerizable double bond in the molecule [produced by Kao Corporation; : Latemulu S-120A, S-180A, etc.].

  If necessary, self-crosslinking properties such as isocyanate ethyl acrylate, isocyanate ethyl methacrylate, 2- (1-aziridinyl) ethyl acrylate, 2- (1-aziridinyl) ethyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide, etc. Monomers with functional groups, monomers with polymerizable double bonds such as vinyl acetate and styrene, divinylbenzene, vinyl acrylate, vinyl methacrylate, allyl acrylate, allyl methacrylate, and other typical commercial products For example, both ends are diacrylate or dimethacrylate, and the structure of the main chain is a propylene glycol type [manufactured by NOF Corporation, trade names: PDP-200, PDP-400, ADP-200, ADP-400] , Tetramethylene glycol [Manufactured by NOF Corporation, trade names: ADT-250, ADT-850] and mixed types thereof [manufactured by NOF Corporation, trade names: ADET-1800, ADPT-4000] A functional monomer or the like may be copolymerized.

  When such a monomer having a self-crosslinking property, a monomer having a polymerizable double bond, or a multifunctional monomer is copolymerized, the amount used is 0.1% by mass to 30% in all monomers. It is preferable that it is mass%. More preferably, it is 0.1 mass%-5 mass%.

  Examples of the polymerization reaction mechanism when polymerizing the polymer (A) and the polymer (B) include radical polymerization, anionic polymerization, and cationic polymerization. In consideration of the production cost of the pressure-sensitive adhesive, the influence of the functional group of the monomer, the influence of ions on the surface of the semiconductor wafer, and the like, the polymerization is preferably performed by radical polymerization. When polymerizing by radical polymerization reaction, organic compounds such as benzoyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide are used as radical polymerization initiators. Inorganic peroxides such as peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 4,4 And azo compounds such as' -azobis-4-cyanovaleric acid.

  Moreover, when polymerizing a polymer (A) and a polymer (B) by radical polymerization reaction, you may add a chain transfer agent as needed for the purpose of adjusting the molecular weight of an adhesive polymer. Examples of the chain transfer agent include conventional chain transfer agents such as mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan. The amount of the chain transfer agent used is about 0.01 parts by mass to 1.0 parts by mass, and more preferably 0.05 parts by mass to 0.8 parts by mass with respect to 100 parts by mass of the total amount of monomers.

  As a polymerization method of the polymer (A) and the polymer (B), a known polymerization method such as an emulsion polymerization method, a suspension polymerization method, or a solution polymerization method can be appropriately selected and used. In particular, considering the prevention of contamination of the pressure-sensitive adhesive layer on the wafer surface, it is preferable to employ an emulsion polymerization method that provides a high molecular weight copolymer.

  In the case where the polymer (A) and the polymer (B) are polymerized by an emulsion polymerization method, among the above-mentioned radical polymerization initiators, inorganic peroxidation such as water-soluble ammonium persulfate, potassium persulfate, sodium persulfate, etc. An azo compound having a carboxyl group in the molecule such as water-soluble 4,4′-azobis-4-cyanovaleric acid is preferred. Considering the influence of ions on the wafer surface, 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.

  The polymer (A) and the polymer (B) may be (1) polymerized separately and then mixed, or (2) by a series of polymerization steps in one reaction vessel, You may obtain a polymer (A) and a polymer (B) collectively.

  As the method of (1), for example, the polymer (A) is polymerized to prepare a liquid containing the polymer (A), and the polymer (B) is separately polymerized to obtain the polymer (B). The method of preparing the liquid containing this and preparing the liquid mixture which mixed these is mentioned.

  In the case of the method (2), the polymer (A) and the polymer (B) may be present separately in the liquid, or may be entangled with each other (or attached). Specifically, in the method (2), the first polymerization material containing the raw material monomer for forming one of the polymer (A) and the polymer (B) is supplied to the reaction vessel to initiate the polymerization. After the first polymerization step and the first polymerization step, a second polymerization material containing a raw material monomer for forming the other of the polymer (A) and the polymer (B) is further supplied to the reaction vessel. And a second polymerization step for polymerization.

  In the method (2), except for carrying out in a series of polymerization steps in one reaction vessel, for example, a known raw material monomer supply method, polymerization conditions (polymerization) are carried out in the same manner as the conventional general emulsion polymerization. Temperature, polymerization time, polymerization pressure, etc.) and materials used (polymerization initiator, surfactant, etc.) can be appropriately employed. For example, as the raw material monomer supply method, any of a batch charging method, a continuous supply (dropping) method, a divided supply (dropping) method, and the like that supply all the monomer raw materials to the polymerization vessel at once can be employed. A part or all of the monomer raw material may be preliminarily mixed with water and emulsified, and the emulsion may be supplied into the reaction vessel.

  As a method for supplying the polymerization initiator, any of a batch charging method, a continuous supply method, a divided supply method, etc. in which substantially all of the polymerization initiator to be used is put in the reaction vessel before the supply of the monomer raw material is started. It is.

  The supply method of the first polymerization material and the supply method of the second polymerization material may be the same or different. The monomer raw materials in the first polymerization material and the second polymerization material are supplied to the reaction vessel so that the mass ratio of the obtained polymer (A) / polymer (B) is 57/43 to 90/10. The

  In the first polymerization step and the second polymerization step, conventionally known various chain transfer agents can be used as necessary. The chain transfer agent may be added in both the first polymerization step and the second polymerization step, or may be added only in one polymerization step. In the present invention, it is preferable to add a chain transfer agent in the first polymerization step. In general, when the amount of the chain transfer agent used is increased under the same conditions, the molecular weight of the resulting polymer is decreased, so that the adhesion is increased but the contamination is liable to deteriorate.

Below, the preferable one aspect | mode of a 1st polymerization process and a 2nd polymerization process is given.
A monomer raw material for forming the polymer (A) as the first polymerization material is supplied into the reaction vessel for polymerization, and then the monomer raw material for forming the polymer (B) as the second polymerization material Is preferably supplied into the reaction vessel for polymerization.

  Both the polymer (A) and the polymer (B) are preferably acrylic polymers. The polymer (A) preferably uses an alkyl acrylate ester as a main monomer and acrylonitrile or methacrylonitrile as a comonomer.

The polymer (A) preferably uses an acrylic acid alkyl ester as a main monomer and contains 22% by mass to 30% by mass of a structural unit derived from acrylonitrile or methacrylonitrile as a comonomer, more preferably acrylic acid as the main monomer. An alkyl ester is used and contains 24 % by mass to 30 % by mass of a structural unit derived from acrylonitrile or methacrylonitrile as a comonomer.

  The polymer (B) is not particularly limited as long as the temperature (Tb) at which the tan δ of dynamic viscoelasticity is maximum is 0 ° C. or less, but an alkyl acrylate can be used as the main monomer. Moreover, acrylonitrile or methacrylonitrile can also be used as a comonomer which comprises a polymer (B). Among these, acrylonitrile is more preferable because it tends to have better contamination.

  When acrylonitrile or methacrylonitrile is used as the comonomer constituting the polymer (B), the structural unit derived from acrylonitrile or methacrylonitrile is 1 part by mass to 20 parts by mass in 100 parts by mass of the polymer (B). It is preferably 5 parts by mass to 20 parts by mass, more preferably 5 parts by mass to 15 parts by mass.

The amount of the chain transfer agent used in the first polymerization step is preferably 90% by mass or more of the total amount of the chain transfer agent, more preferably 95% by mass or more, and more preferably 99% by mass or more. preferable.

  Next, a method of controlling the temperatures (Ta) and (Tb) at which the dynamic viscoelasticity tan δ (hereinafter, simply referred to as tan δ) becomes maximum in the polymer (A) and the polymer (B) will be described.

  The temperatures (Ta) and (Tb) at which tan δ is maximized are (a) the type and amount of the main monomer constituting the polymer (A) and the polymer (B), and (b) the functionality capable of reacting with the crosslinking agent. It can adjust with the kind and usage-amount of the comonomer which has group.

  First, (i) the type and amount of the main monomer constituting the polymer (A) and the polymer (B), when an alkyl alkyl acrylate is used as the main monomer, the carbon of the alkyl group as the main monomer If the number is 3 to 8, the higher the number of carbon atoms in the alkyl group, the lower the temperature at which tan δ is maximum. If the number of carbon atoms in the alkyl group is 9 or more, the number of carbon atoms in the alkyl group As the number increases, the temperature at which tan δ is highest tends to increase. Further, when methacrylic acid esters are used as the main monomer, the temperature at which tan δ is maximized tends to increase. In any case, the greater the amount of these main monomers used, the greater the effect on the temperature at which tan δ is maximized.

  Therefore, in order to obtain a polymer (B) in which the temperature (Ta) at which tan δ is maximized is in a relatively low temperature range of 0 ° C. or lower, n-butyl acrylate, 2-ethylhexyl acrylate, acrylic It is preferable to use many alkyl acrylates having 4 to 8 carbon atoms in the alkyl group, such as octyl acid. Further, in order to obtain a polymer (A) in which the temperature (Tb) at which tan δ is maximized is in a relatively high temperature range exceeding 0 ° C., methyl acrylate, ethyl acrylate, n-butyl acrylate and the like are mainly used. In addition, it is preferable to use many alkyl acrylates having 2 to 4 carbon atoms in the alkyl group and alkyl methacrylates.

  (B) Regarding the type and amount (copolymerization amount) of a comonomer having a functional group capable of reacting with a crosslinking agent, among those usually used as a comonomer, for example, acrylic acid, methacrylic acid, itaconic acid, etc. When using those having a carboxyl group, those having an amide group such as acrylamide, methacrylamide, N-methylolacrylamide, and methacrylic esters such as glycidyl methacrylate and 2-hydroxyethyl methacrylate, Generally, there is a tendency to shift the temperature at which tan δ is maximum to the high temperature side, and the tendency increases as the amount used (copolymerization amount) increases.

  Accordingly, in order to obtain a polymer (B) in which the temperature (Ta) at which tan δ is maximized is in a relatively low temperature range of 0 ° C. or less, there is a tendency to shift the temperature at which tan δ is maximized to the high temperature side. It is preferable to relatively reduce the amount of a certain comonomer added within the above range. In order to obtain a polymer (A) in which the temperature (Tb) at which tan δ is maximized is in a relatively high temperature range exceeding 0 ° C., it is preferable that the amount of comonomer added is relatively large within the above range. .

  As the crosslinking agent (C) having two or more crosslinking reactive functional groups in one molecule used in the present invention, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, Epoxy crosslinking agents such as glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, resorcin diglycidyl ether, trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinyl Propionate, N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide), N, N′-hexamethylene-1,6-bis (1-aziridinecarboxamide), N, N ′ -Toluene-2 , 4-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β- (2-methylaziridine) propionate and other aziridine-based crosslinking agents, tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylolpropane in toluene diisocyanate 3 addition And isocyanate-based crosslinking agents such as polyisocyanates. These crosslinking agents may be used individually by 1 type, and may use 2 or more types together.

  In addition, when the pressure-sensitive adhesive is an aqueous pressure-sensitive adhesive such as an aqueous solution or an emulsion using water, the crosslinking reaction with the pressure-sensitive adhesive polymer is fast because the isocyanate-based cross-linking agent has a fast deactivation rate due to side reaction with water. May not progress sufficiently. Therefore, in this case, it is preferable to use an aziridine-based or epoxy-based crosslinking agent among the above-mentioned crosslinking agents.

  In the present invention, the content of the crosslinking agent (C) having two or more crosslinking reactive functional groups in one molecule is 0.1% relative to 100 parts by mass of the total amount of the polymer (A) and the polymer (B). It is preferable that it is 10 mass parts. If the content of the cross-linking agent is less than 0.1 parts by mass, the cohesive force of the pressure-sensitive adhesive layer becomes insufficient, and the wafer surface may be contaminated. If the content of the cross-linking agent exceeds 10 parts by mass, the adhesiveness of the adhesive layer to the recesses on the wafer surface decreases, and the semiconductor wafer breaks due to the ingress of water and grinding debris during grinding of the wafer back surface. May contaminate the wafer surface.

In the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer in the present invention, in addition to the polymer (A) and the polymer (B), a crosslinking agent (C) having two or more crosslinking reactive functional groups in one molecule, In order to adjust the adhesive properties, rosin-based and terpene resin-based tackifiers, various surfactants, and the like may be appropriately contained. Further, when the polymer (A), and polymer (B) is prepared as an emulsion solution may contain appropriate to the extent that does not affect the coalescent and diethylene glycol monobutyl ether for the purposes of the present invention.

  The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film for protecting a semiconductor wafer surface may affect the adhesion to the recesses on the wafer surface, the adhesive force, and the like. When the thickness of the pressure-sensitive adhesive layer is reduced, the adhesion to the recesses on the wafer surface may be insufficient, and grinding water may enter through the recesses and contaminate the wafer surface. When the thickness is increased, the adhesion to the concave portion of the wafer surface is improved, but the adhesive force is increased, and the workability during peeling may be reduced. From this viewpoint, the thickness of the pressure-sensitive adhesive layer is preferably 5 μm to 200 μm. More preferably, it is 10 micrometers-100 micrometers.

  In the present invention, when the pressure-sensitive adhesive layer is formed on one surface of the base film, the pressure-sensitive adhesive is used as a solution or an emulsion liquid (hereinafter collectively referred to as a pressure-sensitive adhesive coating liquid), a roll coater, a comma A method of forming a pressure-sensitive adhesive layer by sequentially applying and drying in accordance with a known method such as a coater, a die coater, a Mayer bar coater, a reverse roll coater, or a gravure coater can be used. At this time, in order to protect the applied pressure-sensitive adhesive layer from contamination caused by the environment, it is preferable to attach a release film to the surface of the applied pressure-sensitive adhesive layer. Alternatively, a pressure-sensitive adhesive coating solution is applied to one surface of the release film according to the above-described known method and dried to form a pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive layer is formed into a base material using a conventional method such as a dry laminating method. A method of transferring to a film (hereinafter referred to as a transfer method) may be used.

  There is no particular limitation on the drying conditions for drying the pressure-sensitive adhesive coating solution, but in general, drying is preferably performed for 10 seconds to 10 minutes in a temperature range of 80 ° C to 300 ° C. More preferably, it is dried for 15 seconds to 10 minutes in a temperature range of 80 ° C to 200 ° C. In the present invention, in order to sufficiently promote the crosslinking reaction between the crosslinking agent and the alkyl acrylate copolymer, after the drying of the pressure-sensitive adhesive coating liquid is completed, the pressure-sensitive adhesive film for protecting the semiconductor wafer surface is formed. You may heat at 40 to 80 degreeC for about 5 to 300 hours.

  The adhesive strength at a peeling speed of 10 mm / min to 1000 mm / min is preferably 4.0 N / 25 mm or less, more preferably 3.0 N / 25 mm or less, and further preferably 2.5 N / 25 mm or less. preferable. When the adhesive strength is in the above range, the peeling workability when peeling from the semiconductor wafer is excellent. If the adhesive force is too high, the peeling workability is lowered, and the semiconductor wafer may be damaged during peeling.

Next, a method for protecting a semiconductor wafer in the present invention will be described. The method for protecting a semiconductor wafer according to the present invention includes an attaching step of attaching the adhesive layer in the adhesive film for protecting a semiconductor wafer surface of the present invention to a circuit forming surface of the semiconductor wafer, and for protecting the surface of the semiconductor wafer. A grinding step of grinding a non-circuit-formed surface of the semiconductor wafer to which the adhesive film has been attached; and a peeling step of peeling the semiconductor wafer surface protecting adhesive film from the semiconductor wafer.

  The details are as follows. First, the release film is peeled off from the adhesive layer of the semiconductor wafer surface protecting adhesive film (hereinafter referred to as an adhesive film) to expose the surface of the adhesive layer, and the adhesive layer is in contact with the adhesive film. Is attached to the wafer surface. Next, the semiconductor wafer is fixed to the chuck table or the like of the grinding machine through the base film layer of the adhesive film, and the back surface of the wafer is ground. After the grinding is finished, the adhesive film is peeled off. After grinding the back surface of the wafer, before the adhesive film is peeled off, the back surface of the wafer may be processed by a chemical solution such as chemical etching or polishing. Moreover, after peeling an adhesive film as needed, cleaning processes, such as water washing and plasma washing, are given with respect to the wafer surface.

  In operations such as grinding of the wafer back surface and chemical treatment in such a series of steps, the thickness of the semiconductor wafer before the back surface grinding is usually 500 μm to 1000 μm, depending on the type of the semiconductor chip, etc. Usually, it is thinned by grinding to a thickness of about 200 μm to 600 μm, and sometimes to a thickness of about 20 μm. When the thickness of the semiconductor wafer is reduced to 200 μm or less, the process of treating the back surface with a chemical solution is a back surface grinding process in order to improve the strength of the semiconductor wafer by removing the crushed layer generated on the back surface of the wafer by mechanical grinding. In some cases, this is followed by. 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 in general, it is performed using an apparatus called an automatic applicator to which an adhesive film wound in a roll shape is attached. As such an automatic pasting machine, for example, Takatori Co., Ltd., model: ATM-1000B, ATM-1100, Teikoku Seiki Co., Ltd., model: STL series, Nitto Seiki Co., Ltd., model: DR- 8500II etc. are mentioned.

  Usually, the temperature at the time of sticking an adhesive film on the surface of a semiconductor wafer is carried out at a room temperature of around 25 ° C. However, when an adhesive film is pasted on the wafer surface using an automatic pasting machine equipped with a function for raising the temperature of the semiconductor wafer, the semiconductor wafer is kept at a predetermined temperature (usually, before the adhesive film is pasted). A method of raising the temperature to about 40 ° C. to 90 ° C. is used.

  There is no particular limitation on the method for grinding the back surface of the wafer, and a known grinding method such as a through-feed method or an in-feed method is employed. The grinding is preferably performed while cooling the semiconductor wafer and the grindstone with water. As a grinding machine for grinding the back surface of a wafer, for example, manufactured by DISCO Corporation, model: DFG-860, manufactured by Okamoto Machine Tool Co., Ltd., model: SVG-502MKII8, manufactured by Tokyo Seimitsu Co., Ltd., model: polish grinder PG200 etc. are mentioned.

  After grinding of the wafer back surface, chemical treatment, and the like are completed, the adhesive film is peeled off from the wafer surface. Although the operation of peeling the adhesive film from the wafer surface may be performed manually, it is generally performed using an apparatus called an automatic peeling machine. As such an automatic peeling machine, Takatori Co., Ltd., Model: ATRM-2000B, ATRM-2100, Teikoku Seiki Co., Ltd., Model: STP Series, Nitto Seiki Co., Ltd., Model: HR-8500II Etc. Moreover, as an adhesive tape called a peeling tape used when the semiconductor wafer surface protecting adhesive film is peeled from the wafer surface by the automatic peeling machine, for example, Sumitomo 3M Co., Ltd. Highland Mark Filament Tape No. 897 or the like can be used.

  The temperature at which the pressure-sensitive adhesive film for protecting a semiconductor wafer surface is peeled off from the wafer surface is usually performed at a room temperature of about 25 ° C., but if the automatic peeling machine has a function of heating the wafer, You may peel an adhesive film in the state which heated up the semiconductor wafer to predetermined temperature (usually about 40 to 90 degreeC).

  The wafer surface after peeling 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.

  The semiconductor wafer to which the method for protecting a semiconductor wafer of the present invention can be applied is not limited to a silicon wafer, but includes semiconductor wafers such as germanium, gallium-arsenic, gallium-phosphorus, and gallium-arsenic-aluminum.

In addition, the semiconductor device manufacturing method of the present invention includes a bonding step of bonding so that the adhesive layer in the adhesive film for protecting a semiconductor wafer surface of the present invention is in contact with the circuit forming surface of the semiconductor wafer, and the surface of the semiconductor wafer. A grinding step of grinding a non-circuit-formed surface of the semiconductor wafer to which the protective adhesive film is attached; and a peeling step of peeling the semiconductor wafer surface protective adhesive film from the semiconductor wafer. The sticking step, grinding step, and peeling step in the method for manufacturing a semiconductor device are the same as the above-described method for protecting a semiconductor wafer. Other optional chemical processing, cleaning, and the like are the same as the above-described method for protecting a semiconductor wafer.

  Hereinafter, the present invention will be described in more detail with reference to examples. In all examples and comparative examples shown below, preparation of an adhesive coating solution, coating drying, and X-ray photoelectron were performed in an environment maintained at a cleanness of class 1,000 or less as defined in the US Federal Standard 209b. Spectroscopic analysis (hereinafter abbreviated as ESCA) was performed. The present invention is not limited to these examples. In addition, the measurement and evaluation of various characteristic values shown in Examples and Comparative Examples were performed by the following methods.

1. Temperature [Tmax] (° C) at which tan δ of the dynamic viscoelasticity of the polymer is maximized
PET film with a silicone treatment applied to one surface under the same conditions as the coating conditions (drying temperature, drying time, etc.) for producing each pressure-sensitive adhesive layer in Examples and Comparative Examples [Mitsui Chemicals Tosero Co., Ltd. Manufactured, trade name: SP-PET] on the release treatment surface side, each polymer emulsion liquid is applied and dried to form a polymer layer having a thickness of 50 μm to 60 μm after drying. The obtained polymer layers are sequentially overlapped to obtain a polymer film sample having a thickness of about 1 mm. From this film-like sample, a width of about 10 mm and a length of about 50 mm are cut out to make a sample.

  The storage elastic modulus of the obtained sample was measured at a frequency of 1 Hz in a temperature range of −50 ° C. to 100 ° C. using a dynamic viscoelasticity measuring apparatus [manufactured by TA Instruments, model: RSA-III]. To do. Specifically, the sample is set in a dynamic viscoelasticity measuring apparatus via an attachment at 25 ° C., and tan δ of dynamic viscoelasticity is measured while the temperature is increased at a temperature increase rate of 5 ° C./min. After the measurement is completed, the temperature [Tmax] at which tan δ is maximized is read from the obtained tan δ-temperature curve at −50 ° C. to 100 ° C.

  In addition, about the polymer of Examples 1-6, 8 and Comparative Examples 1-3, the sample emulsion liquid for measuring tan (delta) of dynamic viscoelasticity was prepared separately. Specifically, the process was performed until the first aging step, and the obtained emulsion was used as a measurement sample for the first stage polymer. In addition, only the second stage process was performed separately, and the resulting emulsion was used as a measurement sample for the second stage polymer.

  In Examples 1 to 6, 8 and Comparative Examples 1 to 3, all of the first-stage polymers have a Tmax exceeding 0 ° C, and all of the second-stage polymers have a Tmax of 0 ° C or less. there were. Further, the acrylic polymer A1 obtained in Example 7 had a Tmax exceeding 0 ° C, and the acrylic polymer B1 had a Tmax of 0 ° C or less. The acrylic polymer obtained in Comparative Example 4 had a Tmax exceeding 0 ° C. Furthermore, the acrylic polymer obtained in Comparative Example 5 had a Tmax of 0 ° C. or lower.

2. Adhesive strength measurement Except for the conditions specified below, all measurements were performed according to the method specified in JIS Z0237-1991. In an atmosphere of 23 ° C., the surface protective adhesive films obtained in Examples and Comparative Examples are attached to the surface of a 5 cm × 20 cm SUS304-BA plate (JIS G4305-1991 regulation) through the adhesive layer. Leave for 1 hour. After being left, one end of the adhesive film was pinched, the stress at the time of peeling from the surface of the SUS304-BA plate at a peeling angle of 180 degrees and a predetermined peeling speed was measured with a tensile tester, and converted to N / 25 mm.

3. Adhesion evaluation The following semiconductor silicon wafer in which an integrated circuit was incorporated was evaluated.
Wafer 1: diameter 100 mm, thickness 725 μm, scribe line; depth 10 μm, width 400 μm
Wafer 2: diameter 100 mm, thickness 725 μm, scribe line: depth 5 μm, width 400 μm

  The surface protective adhesive film obtained in Examples and Comparative Examples was attached to the surface of the silicon wafer through the adhesive layer, and observed from the substrate side with an optical microscope at 5 magnifications, 23 ° C. Pictures were taken after standing for 24 hours in an atmosphere prepared at ± 2 ° C. and relative humidity 50 ± 5%. When the ratio of the area of the adhesive layer attached to the scribe line to the total area of the scribe line is used as an index of adhesion, and the adhesive area ratio of the adhesive layer to the scribe line is 80% or more, the adhesiveness is excellent. evaluated.

4). Contamination evaluation (ESCA measurement)
The contamination property of the silicon mirror wafer chip surface was evaluated with an X-ray photoelectron spectroscopy analyzer (manufactured by Shimadzu Corporation, trade name: ESCA-3200). The surface protective adhesive films obtained in the examples and comparative examples were bonded to the entire surface of a silicon mirror wafer (diameter: 100 mm, thickness: 600 μm) to which no foreign matter had adhered via the adhesive layer. After leaving for 1 hour in an atmosphere adjusted to 2 ° C and relative humidity 50 ± 5%, peel off the adhesive film for surface protection from the silicon mirror wafer, and then cut the silicon mirror wafer into 1 cm square using a diamond glass cutter. To do. By randomly collecting 5 pieces from the cut 1cm square silicon mirror wafer, and analyzing the surface by ESCA under the following conditions, and obtaining the C / Si ratio (average value of 5 pieces) Then, the state of contamination of the chip surface with organic substances 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 applying the surface protective adhesive film is 0.10 (blank value). Therefore, it was evaluated that there was no contamination when the C / Si ratio on the surface of the silicon mirror wafer after peeling off the surface protective adhesive film was 0.10 to 0.50, and that there was contamination when the C / Si ratio was more than that.

[Example 1]
<Preparation of base film>
An ethylene-vinyl acetate copolymer resin [manufactured by Mitsui DuPont Polychemical Co., Ltd., trade name: EVAFLEX V5961, vinyl acetate unit content 9 mass%] is produced to a thickness of 90 μm using a T-die extruder. The film was coated and subjected to corona treatment on the side to which the adhesive was applied. The thickness variation of the obtained film was within ± 1.5%.

<Preparation of adhesive main agent>
“Parts” and “%” in the following Examples and Comparative Examples represent “parts by mass” and “% by mass” unless otherwise specified.

A polymerization vessel equipped with a stirrer, reflux condenser, thermometer and nitrogen gas inlet is charged with 500 parts of deionized water and purged with nitrogen gas, heated to 70 ° C. to 72 ° C., and then excess as a polymerization initiator. sulfate ammonium double um (hereinafter polymerization initiator (1) and abbreviated) 5 parts (number of moles of added average of ethylene oxide: 20) polyoxyethylene nonylphenyl ether as a water-soluble monomer benzene sulfate ammonium salt 0.15 parts of a compound having a polymerizable 1-propenyl group added to a ring [Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10] (hereinafter abbreviated as water-soluble monomer (1)) Put in.

  Next, as a first step, the polymer described in [Table 1] is added under stirring of 230 parts of deionized water, 10 parts of a polymerization initiator (1), and 3.4 parts of a water-soluble monomer (1). A emulsion prepared by adding 700 parts of a monomer mixture for forming A) and 3.2 parts of n-dodecyl mercaptan as an additive is continuously added to the polymerization vessel over 5 hours and allowed to react. After completion of the addition, aging was further performed for 1 hour.

  Next, as a second stage, a polymer of 88% 2-ethylhexyl acrylate, 10% acrylonitrile and 2% acrylic acid is prepared in advance with stirring of 135 parts deionized water and 1.5 parts water-soluble monomer (1). The emulsion prepared by adding 300 parts of the monomer mixture for forming (B) is continuously added to the polymerization vessel over 2 hours to react, and after completion of the addition, aging is further performed for 2 hours, An acrylic resin emulsion was obtained. This was neutralized with 10% aqueous ammonia (pH = 7.0) to obtain an acrylic polymer (adhesive main agent) having a solid content of 53.5%.

<Preparation of adhesive coating solution>
After adding 0.5 parts of an epoxy-based cross-linking agent [manufactured by Nagase ChemteX Corporation, trade name: Denacol EX-614B] and 2 parts of diethylene glycol monobutyl ether to 100 parts of the obtained adhesive main agent, 10% aqueous ammonia was added. In addition, an adhesive coating solution was obtained with a viscosity of 3000 mPa · s to 5000 mPa · s.

<Production of adhesive film>
Using a lip coater, the pressure-sensitive adhesive coating solution was applied to a polypropylene film (release film, thickness 50 μm) and dried at 90 ° C. for 10 minutes to provide a pressure-sensitive adhesive layer having a thickness of 80 μm. The pressure-sensitive adhesive was laminated on the base film by laminating and pressing the corona-treated side of the aforementioned ethylene-vinyl acetate copolymer film (base film). After lamination, the film was heated at 40 ° C. for 120 hours, and then cooled to room temperature to prepare a surface protective adhesive film. The measurement and evaluation results of various characteristic values are shown in [Table 2].

[Examples 2, 3, 5, 6, 8]
In the production of the pressure-sensitive adhesive main agent, Example 1 and Example 1 were changed except that the monomer mixture for producing the first emulsion was changed as described in each Example column of [Table 1]. Similarly, an adhesive film for surface protection was produced. The measurement and evaluation results of various characteristic values are shown in [Table 2].

[Example 4]
Use an ethylene-vinyl acetate copolymer resin [Mitsui / DuPont Polychemical Co., Ltd., trade name: EVAFLEX V5961, vinyl acetate unit content 9%] formed on a base film at 160 μm, and an adhesive layer Was prepared in the same manner as in Example 3 except that the thickness was 45 μm (drying time: 5 minutes). The measurement and evaluation results of various characteristic values are shown in [Table 2].

[Example 7]
A polymerization vessel equipped with a stirrer, reflux condenser, thermometer and nitrogen gas inlet is charged with 500 parts of deionized water and purged with nitrogen gas, heated to 70 ° C. to 72 ° C., and then excess as a polymerization initiator. sulfate ammonium double um (hereinafter polymerization initiator (1) and abbreviated) 5 parts (number of moles of added average of ethylene oxide: 20) polyoxyethylene nonylphenyl ether as a water-soluble monomer benzene sulfate ammonium salt 0.15 parts of a compound having a polymerizable 1-propenyl group added to a ring [Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10] (hereinafter abbreviated as water-soluble monomer (1)) Put in.

  Next, the polymer (A) described in Example 3 of [Table 1] under agitation of 365 parts deionized water, 10 parts polymerization initiator (1) and 4.85 parts water-soluble monomer (1) in advance. An emulsion prepared by adding 1000 parts of a monomer mixture for forming a mixture and 4.5 parts of n-dodecyl mercaptan as an additive was continuously added to the above polymerization vessel over 7 hours and reacted, and after the addition was completed Further, aging was performed for 3 hours to obtain an acrylic resin emulsion. This was neutralized with 10% aqueous ammonia (pH = 7.0) to obtain an acrylic polymer A1 (adhesive main agent) having a solid content of 53.5%.

Next, in a polymerization vessel equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet, 500 parts of deionized water is added and the nitrogen gas is replaced. as ammonium persulfate two um (hereinafter polymerization initiator abbreviated as (1)) 5 parts (number of moles of added average of ethylene oxide: 20) polyoxyethylene nonylphenyl ether as a water-soluble monomer sulfate ammonium salt Compound in which a polymerizable 1-propenyl group was added to the benzene ring of [Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10] (hereinafter abbreviated as water-soluble monomer (1)) 0.15 Insert a part.

  Next, under stirring of 365 parts deionized water, 10 parts polymerization initiator (1) and 4.85 parts water-soluble monomer (1), 88% 2-ethylhexyl acrylate, 10% acrylonitrile and acrylic acid 2 An emulsion prepared by adding 1000 parts of a monomer mixture for forming a polymer (B) is continuously added to the polymerization vessel over 7 hours and allowed to react. And an acrylic resin emulsion was obtained. This was neutralized with 10% aqueous ammonia (pH = 7.0) to obtain an acrylic polymer B1 (adhesive main agent) having a solid content of 53.5%.

  A surface-protective pressure-sensitive adhesive film is produced in the same manner as in Example 1 except that a mixture of acrylic polymer A1 and acrylic polymer B1 at the same ratio 70/30 as in Example 3 is used as the adhesive main agent. did. The measurement and evaluation results of various characteristic values are shown in [Table 2].

[Comparative Examples 1-3]
In the preparation of the pressure-sensitive adhesive main agent, the monomer mixture for preparing the emulsion of the first-stage polymer (A) was changed as described in the respective comparative examples in [Table 1]. A surface protecting adhesive film was prepared in the same manner as in Example 1 except for the above. The measurement and evaluation results of various characteristic values are shown in [Table 3].

[Comparative Example 4]
A polymerization vessel equipped with a stirrer, reflux condenser, thermometer and nitrogen gas inlet is charged with 500 parts of deionized water and purged with nitrogen gas, heated to 70 ° C. to 72 ° C., and then excess as a polymerization initiator. sulfate ammonium double um (hereinafter polymerization initiator (1) and abbreviated) 5 parts (number of moles of added average of ethylene oxide: 20) polyoxyethylene nonylphenyl ether as a water-soluble monomer benzene sulfate ammonium salt 0.15 parts of a compound having a polymerizable 1-propenyl group added to a ring [Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10] (hereinafter abbreviated as water-soluble monomer (1)) Put in.

  Next, the first and second stages used in Example 3 were previously stirred with 365 parts deionized water, 10 parts polymerization initiator (1) and 4.85 parts water-soluble monomer (1). An emulsion prepared by adding 1000 parts of all the constituent monomer mixtures of the eye and 3.2 parts of n-dodecyl mercaptan as an additive was continuously added to the polymerization vessel over 7 hours to react, and after completion of the addition Further, aging was performed for 3 hours to obtain an acrylic resin emulsion. This was neutralized with 10% aqueous ammonia (pH = 7.0) to obtain an acrylic polymer (adhesive main agent) having a solid content of 53.5%. A surface protective adhesive film was prepared in the same manner as in Example 1 except that the acrylic polymer was used as the adhesive main agent. The measurement and evaluation results of various characteristic values are shown in [Table 3].

[Comparative Example 5]
A polymerization vessel equipped with a stirrer, reflux condenser, thermometer, and nitrogen gas inlet was charged with 135 parts of deionized water and purged with nitrogen gas, and the temperature was raised to 70 ° C to 72 ° C. , 4'-azobis-4-cyanovaleric acid [manufactured by Otsuka Chemical Co., Ltd., trade name: ACVA] 0.5 part, 2-ethylhexyl acrylate 94 parts, methacrylic acid 2 parts, acrylamide 1 part, n-dodecyl 0.1 part of mercaptan, polyoxyethylene nonylphenyl ether (average number of moles of ethylene oxide added: about 20) as a water-soluble monomer A polymerizable 1-propenyl group was added to the benzene ring of sulfate ammonium salt. 0.75 parts of the compound [Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10] is added. The mixture was reacted for 9 hours to obtain an acrylic resin emulsion. This was neutralized with 14% aqueous ammonia (pH = 7.0) to obtain an acrylic polymer having a solid content of 40.0%.

  To 100 parts of the acrylic polymer, 10% aqueous ammonia is added to adjust the pH to 9.3, 0.5 part of an epoxy crosslinking agent [manufactured by Nagase ChemteX Corporation, trade name: Denacol EX-614] and ethylene glycol monobutyl ether. 5 parts was added and the coating liquid A was obtained.

  In addition, a polymerization vessel equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet is charged with 135 parts of deionized water and purged with nitrogen gas, and the temperature is raised to 70 ° C. to 72 ° C., followed by a polymerization initiator. 4,4′-azobis-4-cyanovaleric acid [manufactured by Otsuka Chemical Co., Ltd., trade name: ACVA] 0.5 part, butyl acrylate 74.25 parts, methyl methacrylate 13 parts, methacrylic acid-2 -9 parts of hydroxyethyl, 2 parts of methacrylic acid, 1 part of acrylamide, 0.1 part of n-dodecyl mercaptan, polyoxyethylene nonylphenyl ether as water-soluble monomer (average value of added moles of ethylene oxide: about 20) Compound in which polymerizable 1-propenyl group is added to the benzene ring of sulfate ammonium salt [Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10] Put a .75 parts. This was reacted for 9 hours at 70 ° C. with stirring to obtain an acrylic resin emulsion. This was neutralized with 14% aqueous ammonia (pH = 7.0) to obtain an acrylic polymer having a solid content of 40.0%.

  To 100 parts of the acrylic polymer, 10% ammonia water was added to adjust the pH to 9.3, 4.0 parts of an aziridine-based crosslinking agent [manufactured by Nippon Shokubai Co., Ltd., trade name: Chemite PZ-33] and ethylene glycol monobutyl ether 5 The coating liquid B was obtained by adding a part.

  Using a lip coater, the coating liquid A was applied to a polypropylene film (release film, thickness 50 μm) and dried at 90 ° C. for 5 minutes to provide a pressure-sensitive adhesive layer having a thickness of 40 μm. The intermediate film was obtained by laminating and pressing the corona-treated side of the ethylene-vinyl acetate copolymer film (base film) described above.

  Next, the coating liquid B was apply | coated to the polypropylene film (release film, thickness 50 micrometers) using the lip coater, and it dried at 90 degreeC for 2 minutes, and provided the 10-micrometer-thick adhesive layer. This was obtained by laminating and pressing a polypropylene film (release film, thickness 50 μm) peeled off from the aforementioned intermediate film, and laminating the pressure-sensitive adhesive on the base film. After lamination, the film was heated at 40 ° C. for 72 hours, and then cooled to room temperature to prepare a surface protective adhesive film. The measurement and evaluation results of various characteristic values are shown in [Table 3].

(Abbreviation)
n-BA: n-butyl acrylate AN: acrylonitrile AA: acrylic acid AM: acrylamide 2EHA: 2-ethylhexyl acrylate

The entire disclosure of Japanese application 2014-027013 is incorporated herein by reference.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims (6)

A base film;
Having a pressure-sensitive adhesive layer on one surface of the base film,
The pressure-sensitive adhesive layer has a polymer (A) having a maximum dynamic viscoelasticity tan δ (Ta) exceeding 0 ° C. and a temperature (Tb) at which the dynamic viscoelastic tan δ is maximum 0 ° C. or less. The polymer (B) is a mass ratio (A / B): 57/43 to 90/10,
The polymer (A) contains 22 mass% to 30 mass% of structural units derived from acrylonitrile or methacrylonitrile,
A pressure-sensitive adhesive film for protecting a semiconductor wafer , having an adhesive strength at a peeling speed of 10 mm / min of 1.0 N / 25 mm or more and an adhesive strength at a peeling speed of 10 mm / min to 1000 mm / min of 4.0 N / 25 mm or less . The pressure-sensitive adhesive film for protecting a semiconductor wafer according to claim 1 , wherein the base film comprises at least one layer selected from an ethylene-vinyl acetate copolymer layer, a polyolefin layer, and a polyester layer. A first polymerization step of starting polymerization by supplying a first polymerization material containing a raw material monomer for forming one of the polymer (A) and the polymer (B) to a reaction vessel;
After the first polymerization step, a second polymerization material containing a raw material monomer for forming the other of the polymer (A) and the polymer (B) is further supplied to the reaction vessel for polymerization. the pressure-sensitive adhesive layer is formed using a solution containing the polymer obtained by a method comprising second and polymerization step, the (a) and the polymer (B), in claim 1 or claim 2 The adhesive film for semiconductor wafer surface protection of description. The said adhesive layer is formed using the liquid mixture which mixed the liquid containing the said polymer (A), and the liquid containing the said polymer (B), The Claim 1 or Claim 2 formed. Adhesive film for semiconductor wafer surface protection. The sticking process of sticking so that the adhesive layer in the adhesive film for semiconductor wafer surface protection according to any one of claims 1 to 4 may contact the circuit formation surface of the semiconductor wafer,
A grinding step of grinding a circuit non-formed surface in the semiconductor wafer to which the adhesive film for protecting the surface of the semiconductor wafer is attached;
A peeling step of peeling the semiconductor wafer surface protecting adhesive film from the semiconductor wafer;
A method for protecting a semiconductor wafer, comprising: The sticking process of sticking so that the adhesive layer in the adhesive film for semiconductor wafer surface protection according to any one of claims 1 to 4 may contact the circuit formation surface of the semiconductor wafer,
A grinding step of grinding a circuit non-formed surface in the semiconductor wafer to which the adhesive film for protecting the surface of the semiconductor wafer is attached;
A peeling step of peeling the semiconductor wafer surface protecting adhesive film from the semiconductor wafer;
A method for manufacturing a semiconductor device, comprising: