JP4875414B2 - Adhesive film for semiconductor wafer back grinding and semiconductor wafer back grinding method using the same - Google Patents

Description

  The present invention relates to an adhesive film for back surface 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, appropriately, The present invention relates to an adhesive film for grinding a back surface of a semiconductor wafer that is directly bonded to a “front surface” of the wafer via an adhesive layer, and a back surface grinding method for 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 on one side of the wafer by ion implantation, etching, etc., and further, the other side of the wafer (hereinafter referred to as appropriate) It 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 grinding is completed, the adhesive film is peeled off from the wafer surface.

When grinding an adhesive film for grinding a back surface of a conventional semiconductor wafer to a semiconductor wafer in which an integrated circuit is incorporated to the periphery of the wafer, that is, a semiconductor wafer having a scribe line reaching the outermost periphery of the wafer. In this case, water penetrates between the wafer surface and the adhesive layer through the recess caused by the scribe line. 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 is employed. 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, When peeling from the wafer, 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 the following Patent Document 1, in polishing the back surface of a semiconductor wafer, a semiconductor which 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 is composed of a light-transmitting support and a pressure-sensitive adhesive layer having a property of being cured by light irradiation provided on the support to form a three-dimensional network. 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.

  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 with light before peeling. Therefore, the adhesion to the wafer surface at the time of back surface grinding can be sufficiently increased, and the above-mentioned 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 off 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.

In addition, a protective member for a semiconductor wafer is proposed in which a pressure sensitive adhesive layer is provided on a support sheet, the pressure sensitive adhesive layer has a gel fraction of 40% or more, and contains a water-soluble polymer. In this case, it is described that the pressure-sensitive adhesive layer preferably contains polypropylene glycol having a weight average molecular weight of 5000 or less as a water-soluble polymer.
The protective member (adhesive film) of the semiconductor wafer disclosed herein contains a water-soluble polymer in the pressure-sensitive adhesive layer (adhesive layer), and after peeling the protective member from the circuit pattern forming surface, etc. It is described that even if it is washed directly 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. Furthermore, 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 attached to the semiconductor wafer by bleed can be easily washed with water.

  However, when the semiconductor wafer protection member disclosed in Patent Document 2 is used for grinding the back surface of a semiconductor wafer, the protection member may be removed from the wafer depending on various conditions such as the wafer surface shape, back grinding conditions, and peeling conditions. When peeling, a part of the pressure-sensitive adhesive layer remains on the wafer surface due to cohesive failure (hereinafter, a phenomenon in which a part of the pressure-sensitive adhesive remains on the wafer surface is referred to as “adhesive residue” as appropriate) There was sometimes contamination. 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 packaging demand and demand for semiconductor chips that are required to be thin, such as 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 intrusion of water and grinding debris during grinding becomes more likely as the wafer diameter increases. Furthermore, considering that the strength of the wafer itself decreases as the thickness of the wafer decreases, the above-described 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 the surface of semiconductor wafers in recent years, there are an increasing number of wafers having a surface shape in which a part of the adhesive tends 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 wafer surface, Could 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 water 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 contained in the adhesive layer in consideration of control of the adhesive force to the wafer, ease of contamination removal by washing with water, etc. There is a technique of adding (see, for example, Patent Document 3). However, when the pressure-sensitive adhesive layer contains an alkylene glycol polymer as described above, the alkylene glycol polymer bleeds out from the pressure-sensitive adhesive layer, which may cause contamination of the wafer surface, and further improvement is achieved. 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 penetration of water and grinding debris between the wafer surface and an adhesive layer when grinding the back surface of a semiconductor wafer, and peeling To provide a pressure-sensitive adhesive film for semiconductor wafer back-grinding that can be easily peeled without damaging the wafer and that does not cause contamination of the wafer surface, and a method for back-grinding a semiconductor wafer using the same. is there.

  As a result of intensive studies in view of the above problems, the present inventors use an acrylic pressure-sensitive adhesive polymer and a diol type polypropylene glycol, and use a monomer unit having an isocyanate functional group for the preparation of the acrylic polymer. The inventors have found that the object can be achieved by an adhesive film for grinding a back surface of a semiconductor wafer having an adhesive layer having a specific composition obtained in this way, and have completed the present invention.

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, and (A) an acrylic pressure-sensitive adhesive polymer on one surface of a base film, And (B) 0.1-30 mass parts of crosslinking agents which have two or more functional groups in 1 molecule with respect to 100 mass parts of this (A) acrylic adhesive polymer, (C) Weight average molecular weight 1000-1000. And (A) an acrylic pressure-sensitive adhesive polymer having a pressure-sensitive adhesive layer formed using a coating solution for pressure-sensitive adhesive layers, which contains 1 to 20 parts by mass of a diol type polyalkylene glycol having both terminal functional groups of 5000 However, 60% by mass to 98% by mass of (A-1) (meth) acrylic acid alkyl ester monomer unit and (A-2) 1% of monomer unit having a functional group capable of reacting with a crosslinking agent in the total amount of monomers. % -30 mass % And (A-3) a polymer prepared from a monomer composition containing 1% by mass to 10% by mass of a monomer unit having an isocyanate functional group capable of reacting with a terminal diol group of polypropylene glycol. Adhesive film for backside grinding of semiconductor wafers.

  <2> The back surface of a semiconductor wafer, wherein the adhesive film according to <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.

Here, if the preferable aspect of the said adhesive film for semiconductor back surface grinding is described, in the adhesive layer, the monomer which has the (A-3) isocyanate functional group which comprises the said (A) acrylic adhesive polymer, and (C) A mode in which both terminal functional groups having a weight average molecular weight of 1000 to 5000 have a urethane bond group formed by the reaction of a diol type polyalkylene glycol can be mentioned.
The (A-1) (meth) acrylic acid alkyl ester monomer unit is a (meth) acrylic acid alkyl ester unit having an alkyl group having 1 to 12 carbon atoms, and the (A-2) crosslinking agent. The monomer unit having a functional group capable of reacting with is at least one monomer unit selected from acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylamide, and methacrylamide It is preferable that the crosslinking reactive functional group present in the molecule of (B) the crosslinking agent is at least one functional group selected from the group consisting of an epoxy group, an isocyanate group, an aziridine group and a melamine group.

Furthermore, the (A) acrylic pressure-sensitive adhesive polymer is 85% by mass to 98% by mass of the (A-1) monomer unit and 1% by mass to 20% by mass of the (A-2) monomer unit in the total amount of monomers. A preferred embodiment is an acrylic pressure-sensitive adhesive polymer prepared from a monomer composition containing 2 to 10% by mass of the monomer unit (A-3).
Here, the thickness of the base film used for the adhesive film is appropriately selected according to the purpose, but is preferably 10 to 500 μm.

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 intrusion of water and grinding debris between the wafer surface and the pressure-sensitive adhesive layer, and peeling. To provide a pressure-sensitive adhesive film for semiconductor wafer back-grinding, which can be easily peeled without damaging the wafer, and does not cause contamination of the wafer surface, and a method for back-grinding a semiconductor wafer using the same Can do.
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 pressure-sensitive adhesive layer. Does not happen. Since the adhesive force is in an appropriate range, the wafer is not damaged when the adhesive film is peeled from the wafer, and there is no need to newly introduce 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 backside grinding of a semiconductor wafer of the present invention and the backside grinding method of a 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 a back surface of a semiconductor wafer that is adhered to a circuit forming surface when grinding the back surface of the semiconductor wafer. It is a pressure-sensitive adhesive film for grinding, and (B) functionalized in one molecule with respect to 100 parts by mass of (A) acrylic pressure-sensitive adhesive polymer and (A) acrylic pressure-sensitive adhesive polymer on one surface of the base film. Formed by using a coating solution for pressure-sensitive adhesive layer comprising 0.1 to 30 parts by mass of a crosslinking agent having two or more groups and (C) 1 to 20 parts by mass of a diol type polypropylene glycol having a weight average molecular weight of 1000 to 5000 The (A) acrylic pressure-sensitive adhesive polymer has 60% by mass to 98% by mass of (A-1) (meth) acrylic acid alkyl ester monomer units in the total amount of monomers. (A-2) 1% by mass to 30% by mass of a monomer unit having a functional group capable of reacting with a crosslinking agent, and (A-3) a monomer unit having an isocyanate functional group capable of reacting with a terminal diol group of polypropylene glycol. It is a polymer prepared by a monomer composition containing 1% by mass to 10% by mass.

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 comprises (B) one molecule on one surface of a base film with respect to (A) the acrylic pressure-sensitive adhesive polymer and 100 parts by weight of the (A) acrylic pressure-sensitive adhesive polymer. A pressure-sensitive adhesive comprising 0.1 to 30 parts by mass of a crosslinking agent having two or more functional groups, and (C) 1 to 20 parts by mass of a diol-type polyalkylene glycol in which both terminal functional groups having a weight average molecular weight of 1000 to 5000 are included. It is the layer formed using the coating liquid for agent layers. 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.

<(A) Acrylic adhesive polymer>
The coating solution for pressure-sensitive adhesive layers according to the present invention contains (A) an acrylic pressure-sensitive adhesive polymer (hereinafter, appropriately referred to as “pressure-sensitive adhesive polymer”) as an essential component.
The (A) pressure-sensitive adhesive polymer according to the present invention includes (A-1) an acrylic acid alkyl ester and / or methacrylic acid alkyl ester as a main monomer, and (A-2) a comonomer having a functional group capable of reacting with a crosslinking agent. And (A-3) a polymer obtained by copolymerizing a monomer mixture containing a monomer unit having an isocyanate functional group capable of reacting with a terminal diol group of polypropylene glycol.

[(A-1) (meth) acrylic acid alkyl ester monomer]
(A) As a main monomer used for copolymerization formation of a pressure-sensitive adhesive polymer, a monomer selected from the group consisting of alkyl acrylates and alkyl methacrylates is preferable, and has a C 1-12 alkyl group (meta It is more preferable that it is an acrylic acid alkyl ester unit.
Specific examples 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.
In addition, in this specification, when referring to both or both of acrylic and methacryl, it may be described as “(meth) acryl”.
It is preferable that the amount of the (meth) acrylic acid alkyl ester monomer used as the main monomer is included in the range of 60% by mass to 98% by mass in the total amount of all monomers used as the raw material of the pressure-sensitive adhesive polymer. More preferably, it is the range of 70 mass%-98 mass%.

[(A-2) Monomer having functional group capable of reacting with crosslinking agent]
Examples of the comonomer having a functional group capable of reacting with the crosslinking agent (A-2) that can be copolymerized with the monomer (A-1) include acrylic acid, methacrylic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, maleic acid. Acid, itaconic acid monoalkyl ester, mesaconic 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, tert-butylaminoethyl methacrylate, and the like. Acrylic acid, methacrylic acid, -2-hydroxyethyl acrylate, -2-hydroxyethyl methacrylate, acrylamide, and the like And more preferably at least one monomer unit selected from methacrylamide.
One of these comonomers may be copolymerized with the monomer (A-1), or two or more thereof may be copolymerized.
The amount of the comonomer having a functional group capable of reacting with the crosslinking agent is preferably contained in a range of usually 1% by mass to 30% by mass in the total amount of all monomers used as the raw material of the pressure-sensitive adhesive polymer. More preferably, it is the range of 1 mass%-20 mass%.

[(A-3) Monomer having isocyanate functional group capable of reacting with terminal diol group of polyalkylene glycol]
In the present invention, in the formation of the (A) pressure-sensitive adhesive polymer, in addition to the (A-1) monomer and (A-2) monomer, (A-3) a monomer capable of reacting with a terminal diol group of polyalkylene glycol. Use units. By adding this monomer unit, (A) coexisting with the pressure-sensitive adhesive polymer to achieve easy peeling (C) terminal diol group of polyalkylene glycol, and (A) isocyanate functional group present in the pressure-sensitive adhesive polymer Can form a cross-linking reaction and effectively suppress bleeding of polyalkylene glycol.

Such a monomer is not particularly limited as long as it is an acrylate ester-based monomer having an isocyanate functional group. (A) Affinity with the main monomer constituting the pressure-sensitive adhesive polymer and physical properties of the resulting polymer are considered. Those having a —N═C═O group (isocyanate functional group) at any part of the (meth) acrylic acid-based monomer such as (meth) acrylic acid derivative isocyanate are preferable.
Specific examples include 2-methacryloyl-oxy-ethyl isocyanate, 2-acryloyl-oxy-ethyl isocyanate, 1,1-bisacryloyl-oxy-ethyl isocyanate, and the like.
(A-3) A monomer may use only 1 type or may use 2 or more types together.
Moreover, it is preferable that (A-3) monomer is contained in the range of 1 mass%-10 mass% among all the monomers which comprise (A) adhesive polymer, It is the range of 2 mass%-10 mass%. It is more preferable.

  In addition to the monomers (A-1) to (A-3) described above, the pressure-sensitive adhesive polymer according to the present invention is a specific comonomer having properties as a surfactant (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 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.

[Other monomers that can be included in the adhesive polymer]
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.].

  Further, if necessary, monomers having a self-crosslinkable functional group such as glycidyl acrylate, glycidyl methacrylate, 2- (1-aziridinyl) ethyl acrylate, 2- (1-aziridinyl) ethyl methacrylate, vinyl acetate, acrylonitrile A monomer having a polymerizable double bond such as styrene, or a polyfunctional monomer such as divinylbenzene, vinyl acrylate, vinyl methacrylate, allyl acrylate, or allyl methacrylate may be copolymerized.

  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 considering the production cost of the pressure-sensitive adhesive, the influence of the functional group of the monomer and the influence of ions on the semiconductor wafer surface, etc. For example, the polymerization is preferably performed by radical polymerization.

  Benzoyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide, etc. as radical polymerization initiators that can be used for polymerization by radical polymerization reaction 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) Crosslinking agent having two or more functional groups in one molecule>
In the present invention, together with the above-mentioned (A) pressure-sensitive adhesive polymer, (B) a crosslinking agent having two or more functional groups in one molecule is contained.
The crosslinking agent (B) 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 derived from the monomer (A-2) in the pressure-sensitive adhesive polymer. The functional group capable of reacting with the cross-linking agent and the cross-linking reactive functional group of (B) the cross-linking agent form a cross-linked structure, thereby achieving fixation of the pressure-sensitive adhesive layer and adjusting various physical properties in the pressure-sensitive adhesive layer. .

(B) The crosslinking reactive functional group present in the molecule of the crosslinking agent is preferably at least one functional group selected from the group consisting of an epoxy group, an isocyanate group, an aziridine group and a melamine group.
Examples of the crosslinking agent having such a functional group and that can be suitably used in the present invention include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, and glycerol polyglycidyl ether. , Epoxy compounds such as neopentyl glycol diglycidyl ether, resorcin diglycidyl ether, tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate triadduct of trimethylolpropane, isocyanate compounds such as polyisocyanate, trimethylolpropane-tri -Β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, N, N′-diphe Lumethane-4,4′-bis (1-aziridinecarboxamide), N, N′-hexamethylene-1,6-bis (1-aziridinecarboxamide), N, N′-toluene-2,4-bis ( 1-aziridinecarboxamide), aziridine compounds such as trimethylolpropane-tri-β- (2-methylaziridine) propionate, and melamine compounds such as hexamethoxymethylolmelamine.

These crosslinking agents may be used alone or in combination of two or more.
Among cross-linking agents, epoxy-based cross-linking agents have a slow cross-linking reaction rate, and if the reaction does not proceed sufficiently, the cohesive force of the pressure-sensitive adhesive layer is reduced, and depending on the shape of the semiconductor wafer surface, contamination caused by the pressure-sensitive adhesive layer 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.

(B) It is preferable to contain content of a crosslinking agent normally in the range which the number of functional groups in a crosslinking agent does not become larger than the number of functional groups in an 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 crosslinking agent in the present invention is preferably 0.1 to 30 parts by mass, and preferably 0.2 to 15 parts by mass with respect to 100 parts by mass of the (A) pressure-sensitive adhesive polymer. Particularly preferred. When the content of the cross-linking agent is within the above range, sufficient cohesive force of the pressure-sensitive adhesive layer is achieved, and adhesive residue resulting from the pressure-sensitive adhesive layer on the wafer surface (especially in the case of a wafer having a high bump electrode) When the adhesive film is peeled from the wafer surface, it is possible to prevent the occurrence of troubles such as peeling trouble with the automatic peeling machine or damage to the wafer. Therefore, water and grinding debris enter during grinding, and the wafer is not damaged and the wafer surface is not contaminated by the grinding debris.

<(C) Diol type polypropylene glycol having a weight average molecular weight of 1000 to 5000>
The coating solution for the pressure-sensitive adhesive layer according to the present invention includes (A) the acrylic pressure-sensitive adhesive polymer and (B) the crosslinking agent, and (C) a diol type polypropylene glycol having a weight average molecular weight of 1000 to 5000 as an essential component. contains.
Thus, by using polypropylene glycol having a hydrophilic functional group in the molecule and having a predetermined molecular weight for the adhesive layer, an appropriate adhesive force can be achieved, and the wafer surface, the adhesive layer, It was possible to achieve both excellent adhesion and easy peelability at the time of peeling.

The (C) specific polypropylene glycol added to the pressure-sensitive adhesive layer is preferably a diol type, but a triol type can also be used in combination.
The weight average molecular weight of the polyalkylene glycol is preferably 1000 to 5000, more preferably 1000 to 5000, from the viewpoint that uniform dispersion is possible in the acrylic resin emulsion-type pressure-sensitive adhesive and stability over time is excellent. It is in the range of 3000.
Within this molecular weight range, (C) scattering over time during application of specific polypropylene glycol and storage of semiconductor wafer processing films is suppressed, and appropriate adhesive strength is maintained. Is also easy to uniformly disperse.
In addition, the weight average molecular weight of the specific polypropylene glycol in the present invention is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard substance.

  About addition amount, it is preferable that it is 1-20 mass parts with respect to 100 mass parts of (A) adhesive polymers, and it is further more preferable that it is 3-15 mass parts. Within this content range, it is possible to achieve moderate tackiness, that is, tackiness that can achieve both good adhesion to the wafer and easy peelability after use. When the content is excessively large, the adhesive force is remarkably lowered, and further, the cohesive force of the adhesive is lowered, which may cause the adhesive residue on the wafer surface.

In addition to the above-described essential components (A) to (C), the adhesive layer coating liquid in the present invention may be used in combination with other known additives as long as the scope of the present invention is not impaired. For example, a carbitol-based or cellsolve-based water-soluble organic solvent may be added as a film-forming aid depending on the purpose.
Further, in order to adjust the adhesive properties, optional components such as rosin-based and terpene resin-based tackifiers, various surfactants and the like may be appropriately contained so as not to affect the effects of the present invention.

  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 it cannot be cleaned when contained in a large amount in the 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 pressure-sensitive adhesive layer coating liquid, when the pressure-sensitive adhesive polymer is an emulsion liquid, in order to facilitate the dispersion of the component (C) in the pressure-sensitive adhesive layer coating liquid, the diethylene glycol is used. The component (C) is previously dissolved in a film-forming aid such as monoalkyl ether, and then added to the pressure-sensitive adhesive polymer emulsion liquid, or a surfactant is appropriately used in combination so as not to affect the purpose of the present invention. Is preferred.

The pressure-sensitive adhesive layer according to the present invention is an essential component, which includes (A) a pressure-sensitive adhesive polymer, (B) a cross-linking agent, (C) a specific molecular weight polypropylene glycol, and an optional component 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 applying and drying a 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 Method of transferring the pressure-sensitive adhesive layer onto the substrate film after applying and drying the coating solution and forming the pressure-sensitive adhesive layer When the pressure-sensitive adhesive layer is formed by the method i) above, contamination caused by the environment In order to protect from the above, it is preferable to stick a release film on the surface of the formed pressure-sensitive adhesive layer.

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.

  Taking into consideration that the adhesive film for grinding the back surface of semiconductor wafers is attached to the surface of the semiconductor wafer via the surface of the adhesive layer exposed when the release film is peeled off, it prevents contamination of the semiconductor wafer surface with 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.

<Base film>
As the base film in the present invention, a synthetic resin formed 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 70 to 500 μm. 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, in consideration of the protection performance of the wafer during back grinding, a raw material resin having a Shore D hardness of 40 or less as defined in ASTM-D-2240-86 or JIS K-7215-1986 is particularly preferable. 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 with 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 crosslinking reaction between the (B) crosslinking agent and the (A) pressure-sensitive adhesive polymer, after drying of the pressure-sensitive adhesive layer coating liquid is completed, the pressure-sensitive adhesive film for back grinding of the semiconductor wafer is 40 to 80 ° C. The heating step of heating for about 5 to 300 hours may be performed.

  The thickness of the pressure-sensitive adhesive layer in the present invention is preferably in the range of 3 to 100 μm, more preferably in the range of 5 to 100 μm, and further 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, resulting in damage to the wafer or contamination of the wafer surface with grinding debris. There is a tendency. If 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., but if the adhesive strength is too low, the wafer surface The film tends to be difficult to attach to the surface, water may penetrate between the wafer surface and the adhesive layer during backside grinding, the wafer may be damaged, and the wafer surface may be contaminated by grinding debris. is there. Also, if the adhesive strength is too high, when the adhesive film is peeled from the wafer surface after backside grinding, the peeling workability may be degraded, such as an automatic peeling machine, and the wafer may be damaged. is there. Usually, it is preferably 0.4 to 4.0 N / 25 mm, more preferably 0.5 to 3.5 N / 25 mm, in terms of adhesive strength to a SUS304-BA plate.

  In the production of an 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 back 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-described 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 a treatment such as water washing or plasma washing.

In such 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 sticking 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, 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 carried out by a method such as immersing a semiconductor wafer with an 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 completion of back grinding and chemical etching, 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 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 grinding the back surface of a semiconductor wafer, wafer damage caused by water entering between the wafer surface and the adhesive layer during grinding is also caused by grinding dust entering. No pollution occurs. Since the adhesive strength is in the proper range, even when peeling the adhesive film from the surface of the semiconductor wafer, it can be easily peeled without damaging the wafer, and equipment such as a light irradiation device is newly introduced into the process. There is no need. 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 same 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 (2000 version). In an atmosphere of 23 ° C., the adhesive films obtained in Examples or Comparative Examples were attached to the surface of a 5 × 20 cm SUS304-BA board (JIS G-4305-1991) via the adhesive layer. And 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 by using a grinder, so that the thickness was 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> Damage of wafer during backside grinding After grinding of the backside of the semiconductor silicon wafer, the breakage of the semiconductor silicon wafer was evaluated by the number of damaged pieces.
<2> Water ingress during backside grinding For semiconductor silicon wafers that were not damaged by grinding, visually inspected whether water entered from between the front surface and the adhesive film, and the number of water intrusions evaluated.
<3> Wafer breakage during peeling of adhesive film After observation of water intrusion, surface protective tape peeling machine {manufactured by Nitto Seiki Co., Ltd., MODEL: HR-8500; used peeling tape: 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> Evaluation of wafer contamination (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 (manufactured by Inoue Seiei). 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%.

((A) Synthesis of adhesive polymer)
(A-1) 80% by mass of butyl acrylate and (A-1) 8% by mass of methyl methacrylate, (A-2) 3% by mass of 2-hydroxyethyl methacrylate, (A-2) 2% by mass of acrylic acid, (A-3) 7% by mass of methacryloyl-oxy-ethylisocyanate were prepared, and these were copolymerized in a conventional manner in ethyl acetate to obtain an acrylic having a number average molecular weight of 500,000 A pressure-sensitive adhesive polymer solution containing 50% by mass of the system copolymer as a solid content was obtained.

(Preparation of adhesive coating solution)
To 100 parts by mass of the resulting pressure-sensitive adhesive main agent solution ((A) pressure-sensitive adhesive polymer concentration 40% by mass), 1.0 mass of (B) aziridine-based cross-linking agent [manufactured by Nippon Shokubai Chemical Industry Co., Ltd., Chemite PZ-33] And (C) 10 parts by mass of diol-type polypropylene glycol having a weight average molecular weight of 3000 were added to obtain a pressure-sensitive 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 semiconductor wafer back grinding.

(Evaluation of adhesive film)
1. Adhesive force About the obtained adhesive film, the adhesive force (N / 25mm) was measured by the said method. The adhesive force of the obtained adhesive film was 1.2 N / 25 mm.
2. Practical evaluation The obtained adhesive film is a semiconductor silicon wafer (diameter: 200 mm, thickness: 600 μm, scribe line width: 100 μm, scribe line of a 100 mm ² integrated circuit having a high bump electrode having a height of 8 μm. It was attached to the surface (integrated circuit side) having a depth of 5 μm.
<2-1> Status of wafer breakage during backside grinding Using a grinder, the backside of the semiconductor silicon wafer was ground until the thickness after grinding was about 200 μm while cooling with water. The same operation was performed on 10 similar wafers. When the presence or absence of damage was confirmed according to the evaluation method, no wafers were damaged during grinding.
<2-2> Water penetration during backside grinding After grinding, water penetration was not observed between the wafer and the adhesive film.

<2-3> Damaged state of wafer when peeling adhesive film From these 10 wafers, surface protective tape peeling machine {manufactured by Nitto Seiki Co., Ltd., MODEL: HR-8500; used peeling tape: Highland Mark Filament Tape No . The adhesive film was peeled off using 897 [manufactured by Sumitomo 3M Co., Ltd.]}. None of the wafers were damaged during the peeling of the adhesive film.
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.
<2-4> Evaluation of contamination status by ESCA The C / Si value of ESCA, which is an index of the contamination property of the wafer surface, was 0.17, and it was observed that the contamination property 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, (C) polyethylene glycol having a weight average molecular weight of 1000 was used instead of polypropylene glycol having a weight average molecular weight of 3000, and the addition amount was 15 parts by mass. Except for the above, 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 strength of the adhesive film was 1.0 N / 25 mm.
About this adhesive film, it evaluated by the method similar to Example 1 using the semiconductor silicon wafer similar to Example 1. FIG. 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. Contamination due to an adhesive or the like was not observed on the surface of the semiconductor silicon wafer after the surface was washed with water.
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, (B) an epoxy-based crosslinking agent (manufactured by Nagase Kasei Kogyo Co., Ltd., Denacol EX-611) instead of 1.0 part by mass of (B) aziridine-based crosslinking agent. ) Was used, and an adhesive film for grinding a semiconductor wafer back surface was produced in the same manner as in Example 1 except that the addition amount was 5 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 2.5 N / 25 mm.
About this adhesive film, it evaluated by the method similar to Example 1 using the semiconductor silicon wafer similar to Example 1. FIG. 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. Contamination due to an adhesive or the like was not observed on the surface of the semiconductor silicon wafer after the surface was washed with water.
The obtained results are shown in Table 1.

[Example 4]
In the preparation of the coating solution for the pressure-sensitive adhesive layer of Example 1, (C) Semiconductor wafer back surface grinding in the same manner as in Example 1 except that the addition amount of polypropylene glycol having a weight average molecular weight of 3000 was 20 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 0.8 N / 25 mm.
About this adhesive film, it evaluated by the method similar to Example 1 using the semiconductor silicon wafer similar to Example 1. FIG. 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. Contamination due to an adhesive or the like was not observed on the surface of the semiconductor silicon wafer after the surface was washed with water.
The obtained results are shown in Table 1.

[Example 5]
In the preparation of the pressure-sensitive adhesive coating solution of Example 1, (C) polyethylene glycol having a weight average molecular weight of 4500 was used instead of (C) polypropylene glycol having a weight average molecular weight of 3000, and the addition amount was 5 parts by mass. Produced a pressure-sensitive adhesive film for semiconductor wafer back grinding 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 2.5 N / 25 mm.
About this adhesive film, it evaluated by the method similar to Example 1 using the semiconductor silicon wafer similar to Example 1. FIG. 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. Contamination due to an adhesive or the like was not observed on the surface of the semiconductor silicon wafer after the surface was washed with water.
The obtained results are shown in Table 1.

[Comparative Example 1]
In the polymerization of the pressure-sensitive adhesive polymer of Example 1, all were the same as Example 1 except that (A-1) methyl methacrylate was 15 parts by mass and (A-3) methacryloyl-oxy-ethyl isocyanate was not used. The adhesive film for semiconductor wafer back surface grinding was manufactured by this method.
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. Moreover, it was observed that the C / Si value of ESCA, which is an index of contamination on the wafer surface, was as large as 0.25, indicating that the contamination was poor.
The obtained results are shown in Table 2.

[Comparative Example 2]
In the preparation of the pressure-sensitive adhesive coating solution of Example 1, (C) a polypropylene wafer was prepared by the same method as in Example 1 except that polypropylene glycol 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 2.5 N / 25 mm.
About this adhesive film, it evaluated by the method similar to Example 1 using the semiconductor silicon wafer similar to Example 1. FIG. There were 3 wafers damaged during grinding, but 3 wafers were damaged during peeling of the adhesive film. Moreover, it was observed that the C / Si value of ESCA, which is an index of contamination on the wafer surface, was 0.23, indicating that the contamination was poor.
The obtained results are shown in Table 2.

[Comparative Example 3]
In the preparation of the pressure-sensitive adhesive coating liquid of Example 1, a semiconductor wafer back grinding pressure-sensitive adhesive film was produced in the same manner as in Example 1 except that (B) an aziridine-based crosslinking agent 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 2.0 N / 25 mm.
About this adhesive film, it evaluated by the method similar to Example 1 using the semiconductor silicon wafer similar to Example 1. FIG. No wafers were damaged during grinding, and no water intrusion was observed between the wafer and the adhesive film after grinding. One wafer was 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 pressure-sensitive adhesive coating solution of Example 1, (C) instead of polypropylene glycol having a weight average molecular weight of 3000, polyethylene glycol having a weight average molecular weight of 500 outside the scope of the present invention was used, and the addition amount was 20 mass. Except for the part, a pressure-sensitive 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 0.4 N / 25 mm.
With respect to this adhesive film, two wafers were damaged due to water ingress during grinding evaluated by the same method as in Example 1 using the same semiconductor silicon wafer as in Example 1. After completion of grinding, water penetration was observed for 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 0.18, and it was observed that the contamination was good.
The obtained results are shown in Table 2.

[Comparative Example 5]
In the preparation of the pressure-sensitive adhesive coating solution of Example 1, (C) instead of polypropylene glycol having a weight average molecular weight of 3000, polypropylene glycol having a weight average molecular weight of 10,000 outside the scope of the present invention was used, and the addition amount was 5 mass. Except for the part, a pressure-sensitive adhesive film for grinding a semiconductor wafer back surface was produced in the same manner as in Example 1.
However, since the viscosity after blending was as high as 1000 cps or more and could not be applied to the corona-treated surface of the EVA film similar to Example 1 with a roll coater, the intended semiconductor wafer processing film could not be obtained. .

  As described above, in the adhesive film of the example, when grinding the back surface of the semiconductor wafer, not only the wafer breakage during grinding due to the grinding stress of the back surface does not occur, but also between the wafer surface and the 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 can be easily peeled off. 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 adhered to a circuit forming surface when grinding the back surface of a semiconductor wafer, wherein (A) an acrylic pressure-sensitive adhesive polymer, and Both (A) 0.1-30 mass parts of crosslinking agents which have two or more functional groups in 1 molecule, and (C) weight average molecular weight 1000-5000 with respect to 100 mass parts of (A) acrylic adhesive polymers. And a pressure-sensitive adhesive layer formed using a coating solution for a pressure-sensitive adhesive layer containing 1 to 20 parts by mass of a diol-type polyalkylene glycol, and the (A) acrylic pressure-sensitive adhesive polymer is a monomer In the total amount, (A-1) (meth) acrylic acid alkyl ester monomer unit is 10% by mass to 98% by mass, and (A-2) monomer unit having a functional group capable of reacting with a crosslinking agent is 1% by mass to 30%. Mass%, and (A-3) A polymer prepared by a monomer composition containing 1% by mass to 10% by mass of an acrylate monomer unit having an isocyanate functional group capable of reacting with a terminal diol group of polyalkylene glycol. A pressure-sensitive adhesive film for grinding a back surface of a semiconductor wafer.   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.