JP2008001822A - Method for processing semiconductor wafer, adhesive film for processing the semiconductor wafer used for the same and method for producing the adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive film for processing a semiconductor film capable of suppressing the change with time of physical properties of the film and also suppressing the contamination to a material to be adhered (the semiconductor wafer), and a method for processing the semiconductor wafer by using the same. <P>SOLUTION: This adhesive film for processing the semiconductor wafer used for protecting a circuit on processing the semiconductor wafer is provided by having a substrate film and an adhesive layer arranged on at least one side surface of the substrate film. The adhesive layer is constituted by using an adhesive polymer having a functional group capable of reacting with a cross-linking agent by a radical polymerization caused by an energy beam irradiation and a cross-linking agent having ≥1 cross-linking reactive functional group, and containing a cross-linked polymer cross-linked by the energy beam irradiation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for processing a semiconductor wafer and an adhesive film for processing a semiconductor wafer used in the method for processing a semiconductor wafer. More specifically, a semiconductor wafer processing method for protecting a semiconductor wafer in processing on a circuit non-forming surface such as grinding and grinding of a circuit non-forming surface of a semiconductor wafer, and an adhesive film for processing a semiconductor wafer used in the processing method, And it is related with the manufacturing method of the adhesive film for semiconductor wafer processing.

  A method for processing a semiconductor wafer includes an adhesive film attaching step of attaching an adhesive film for protecting the surface of a semiconductor wafer to a circuit forming surface (hereinafter referred to as a semiconductor wafer surface) of the semiconductor wafer, and a circuit non-forming surface of the semiconductor wafer (hereinafter referred to as a semiconductor). Wafer back surface processing step for performing processing such as cutting and polishing on the wafer back surface), peeling step for peeling the adhesive film, dicing step for dividing and cutting the semiconductor wafer into chips, die bonding step for bonding the divided semiconductor chips to the lead frame After passing through, a semiconductor wafer is obtained by performing a process such as a molding process for sealing a semiconductor chip with resin for external protection.

  Conventionally, as a pressure-sensitive adhesive film for protecting the surface of a semiconductor wafer, a pressure-sensitive adhesive film in which a pressure-sensitive adhesive layer is applied to one surface of a resin film base has been mainstream, and has been generally used in the manufacturing process of the semiconductor wafer. . In this case, the main characteristics of the adhesive film for protecting a semiconductor wafer include absorption of polishing stress when the back surface of the semiconductor wafer is mechanically ground after the adhesive film is pasted (preventing damage to the semiconductor wafer), and optimal for peeling the adhesive film. Peeling force (does not damage the ground semiconductor wafer), suppression of transfer to the surface of the semiconductor wafer after peeling of the adhesive film, and the like. Various such adhesive films for protecting the surface of a semiconductor wafer have been proposed (for example, Patent Documents 1 to 3).

  In general, the cohesive strength of acrylic pressure-sensitive adhesive is introduced into the pressure-sensitive adhesive layer constituting such a pressure-sensitive adhesive film, and a reactive functional group such as an isocyanate group is introduced into the pressure-sensitive adhesive layer. In order to improve the formation by adding a compound having two or more groups and reacting the functional groups with each other, a hydroxyl group, a carboxyl group, an amino group, and an epoxy group are used in the acrylic adhesive polymer.

  However, in this method, the physical properties of the film such as the adhesive strength and the elastic modulus of the pressure-sensitive adhesive are caused by the difference in the reaction rate specific to the functional group and the bond after the reaction is broken by hydrolysis. May change over time.

  In addition, there is a technique that uses a solvent-free pressure-sensitive adhesive for the pressure-sensitive adhesive layer for the purpose of protecting uneven circuits (Patent Document 4), but this technique requires the main polymer to be dissolved in a polymerizable monomer. It is necessary to select a main polymer having a relatively low molecular weight (for example, weight average molecular weight Mw: 5000 to 50000), and a large amount of monomer for dissolving the polymer is required. For this reason, a low molecular weight polymer or an unreacted monomer adheres to the adherend when attached to the adherend, causing contamination of the circuit.

Japanese Patent Application Laid-Open No. 61-10242 JP 61-043677 A JP-A-62-271451 JP 2005-1554 A

  An object of the present invention in consideration of the above-mentioned problems is an adhesive film for processing a semiconductor wafer, which can suppress changes in physical properties of the film over time, and can suppress contamination of an adherend (semiconductor wafer), and its production. The present invention provides a method and a method for processing a semiconductor wafer using the method.

As a result of intensive studies, the present inventors have found that the above-described problems can be solved by the following configuration, and have completed the present invention. That is, the configuration of the present invention is as follows.
<1> A semiconductor wafer processing adhesive film used for circuit protection during processing of a semiconductor wafer,
Having a base film and an adhesive layer disposed on at least one side of the base film,
The pressure-sensitive adhesive layer uses a pressure-sensitive adhesive polymer having a functional group capable of reacting with a cross-linking agent by radical polymerization by energy ray irradiation, and a cross-linking agent having at least one cross-linking reactive functional group capable of cross-linking with the functional group. , Comprising a crosslinked polymer that is crosslinked by irradiation with the energy beam,
An adhesive film for processing semiconductor wafers.

  <2> The adhesive film for semiconductor wafer processing according to <1>, wherein the adhesive polymer is an acrylic resin having a radical polymerizable carbon-carbon double bond.

  <3> At least one of the crosslinking agents is a crosslinking agent having one or more crosslinking reactive functional groups capable of crosslinking reaction with the radical polymerizable carbon-carbon double bond. It is the adhesive film for semiconductor wafer processing of description.

  <4> At least one of the cross-linking agents is a cross-linking agent having polyalkylene glycol as a main skeleton and having at least one carbon-carbon double bond as the cross-linking reactive functional group. <1> A semiconductor wafer processing adhesive film according to <1>.

<5> An adhesive film attaching step of attaching the adhesive layer surface of the adhesive film for semiconductor wafer processing according to any one of <1> to <4> to a circuit forming surface of the semiconductor wafer;
A wafer processing step for processing a non-circuit-formed surface of the semiconductor wafer;
A method for processing a semiconductor wafer having

<6> A cross-link having one or more functional groups capable of cross-linking reaction with a functional group capable of reacting with a cross-linking agent by radical polymerization upon irradiation with energy rays on one side of a base film or a release film. Forming a coating film by applying a coating solution containing an agent;
Irradiating the surface of the coating with energy rays to cause a crosslinking reaction between the adhesive polymer and the crosslinking agent, and curing the coating;
It is a manufacturing method of the adhesive film for semiconductor wafer processing characterized by having.

  ADVANTAGE OF THE INVENTION According to this invention, while suppressing the time-dependent change of a film physical property, the adhesive film for semiconductor wafer processing which can suppress the contamination to a to-be-adhered body (semiconductor wafer), and the processing of a semiconductor wafer using the same A method can be provided.

  Hereinafter, the present invention will be described in detail.

<Semiconductor wafer processing adhesive film>
First, the adhesive film for processing a semiconductor wafer of the present invention (hereinafter sometimes simply referred to as “adhesive film”) will be described.

  The pressure-sensitive adhesive film of the present invention comprises a pressure-sensitive adhesive polymer having a functional group capable of reacting with a cross-linking agent by radical polymerization upon irradiation with energy rays, and a cross-linking agent having at least one cross-linking reactive functional group capable of cross-linking with the functional group. Used, it has a pressure-sensitive adhesive layer comprising a cross-linked polymer that is cross-linked by irradiation with energy rays. By having such a pressure-sensitive adhesive layer, it is possible to suppress changes over time in film physical properties and to suppress contamination of the adherend (semiconductor wafer). The reason is presumed as follows.

  In general, since the crosslinked structure formed by radical polymerization reaction is a strong covalent bond, the atmosphere is more than the crosslinked structure caused by the interaction formed by the functional group such as a hydroxyl group and an epoxy crosslinking agent. This is presumably because of being excellent in stability over time. In addition, since the pressure-sensitive adhesive layer is formed by crosslinking using a crosslinking agent polymer having a relatively high molecular weight, it is presumed that contamination of the adherend (semiconductor wafer) can be suppressed.

  In the present invention, a compound having one crosslinking-reactive functional group, which usually has a linear (straight chain) structure and cannot take a crosslinked structure upon polymerization, is also referred to as a crosslinking agent. A crosslinking structure can be formed by the reaction of the crosslinking reactive group of the crosslinking agent with a functional group of the pressure-sensitive adhesive polymer (for example, a carbon-carbon double bond).

Hereinafter, the present invention will be further described in detail.
The pressure-sensitive adhesive film of the present invention is used in the semiconductor wafer processing method of the present invention, and has a base film and a pressure-sensitive adhesive layer disposed on at least one side of the base film.

  The pressure-sensitive adhesive layer used here is affixed to the circuit forming surface of the wafer during the processing of the semiconductor wafer, and is intended to protect the semiconductor circuit from various contamination and damage due to stress during the back surface processing.

  The pressure-sensitive adhesive film of the present invention is usually attached to an integrated circuit formation surface (hereinafter referred to as a surface) of a semiconductor wafer via a pressure-sensitive adhesive layer in a room temperature around room temperature, i.e., about 18 to 30 ° C., for example. Thereafter, the surface of the semiconductor wafer where the integrated circuit is not formed (hereinafter referred to as the back surface) is processed, and then the semiconductor wafer surface protecting adhesive film is peeled off and used in the semiconductor wafer back surface processing step.

  The pressure-sensitive adhesive film of the present invention is manufactured by forming a base film and then forming a pressure-sensitive adhesive layer on one side thereof. Usually, a release film is attached to the surface of the pressure-sensitive adhesive layer to prevent contamination of the surface of the pressure-sensitive adhesive layer and adhesion to an undesired member, thereby protecting the pressure-sensitive adhesive layer.

  As a method for forming the pressure-sensitive adhesive layer on the surface of the base film, a known method can be arbitrarily applied. For example, the pressure-sensitive adhesive layer is formed by applying and drying a pressure-sensitive adhesive coating solution on one side of the release film. Thereafter, a method of transferring the obtained pressure-sensitive adhesive layer to one side of the base film may be applied, and a method of forming a pressure-sensitive adhesive layer by directly applying a pressure-sensitive adhesive coating solution to one side of the base film and drying it. You can also take Even when the pressure-sensitive adhesive layer is formed by the latter method, it is preferable to stick a release film on the surface of the pressure-sensitive adhesive layer in order to protect it from contamination caused by the environment. Even when the pressure-sensitive adhesive layer is formed by any method, in use, the release film is peeled off, and the pressure-sensitive adhesive layer is attached to the circuit surface for use.

  Whether to apply the adhesive coating solution on one side of the base film or release film can be determined in consideration of the heat resistance of the base film and release film and the non-contamination property of the semiconductor wafer surface. From the viewpoint of preventing contamination of the surface of the semiconductor wafer by the layer, a method of using a release film having good heat resistance and applying an adhesive coating solution to the surface and drying to form an adhesive layer is preferable.

The base film used for forming the pressure-sensitive adhesive film of the present invention can be properly used depending on the production process of the semiconductor wafer, such as polyolefin single layer, polyester single layer or lamination of polyolefin and polyester. For example, in the case of a laminated type of polyester and polyolefin, in semiconductor wafer grinding processing, the thinner the silicon portion, the more the semiconductor wafer becomes crystalline due to the crystallinity of the semiconductor wafer itself, the shrinkage of the polyimide film, the stress of bump attachment, etc. There is also concern about the problem of warping, and the amount of warpage of the semiconductor wafer can be reduced by balancing the thickness and rigidity of the polyester and polyolefin.
The base film is not limited to the above, but polyethylene, ethylene-vinyl acetate copolymer, ethylene-alkyl acrylate copolymer (the alkyl group has 1 to 4 carbon atoms), ethylene-α-olefin. A single layer film or laminated film of a resin selected from copolymers, propylene-α-olefin copolymers, polyolefins such as polypropylene, polyesters such as polyethylene terephthalate and polyester naphthalate can be preferably used.

  The thickness of the base film can be selected according to the purpose. However, in the semiconductor wafer back surface processing step, for example, in order to perform grinding or polishing treatment, the thickness of the base film is taken into consideration when it is introduced into a grinding apparatus. Is preferably 1000 μm or less, and more preferably 700 μm or less. In addition, considering the workability of the semiconductor wafer manufacturing process including adhesion and peeling of the sheet without impairing the adhesiveness of the pressure-sensitive adhesive layer formed on the surface, when using polyester for the base film material, The thickness is preferably 5 to 100 μm, more preferably 20 to 100 μm. Moreover, when using polyolefin, it is preferable that thickness is 10-400 micrometers, More preferably, it is 30-300 micrometers.

Also, in the wafer processing step, an optimal base film configuration when an etching process using a chemical solution or the like, or a heat-resistant process is used, uses a polyester single layer film having chemical resistance and heat resistance, or A polyester / polyolefin two-layer structure film in which it is laminated on the outermost layer can be preferably exemplified.
Furthermore, the base film having specific physical properties described in JP-A-2004-6630 previously proposed by the applicant of the present application can also be preferably used for the adhesive film of the present invention.

  Typical methods for producing the base film include a T-die extrusion method, an inflation method, a calendar method, and the like. Moreover, when manufacturing a multilayer film, the method of laminating | stacking with the laminated | multilayer film prepared previously is mentioned, extruding one resin with an extruder. In order to increase the adhesive force between the layers of these multilayer films, a new adhesive layer may be provided between them, or corona discharge treatment or chemical treatment may be performed. The surface on which the pressure-sensitive adhesive layer is provided is preferably subjected to corona discharge treatment or chemical treatment.

  The pressure-sensitive adhesive layer used in the pressure-sensitive adhesive film according to the present invention includes a cross-linked polymer obtained by cross-linking by irradiation with energy rays using a pressure-sensitive adhesive polymer and a cross-linking agent. For example, 0.1-30 weight part of crosslinking agents are used for an adhesive layer with respect to 100 weight part of adhesive polymers, for example.

  The pressure-sensitive adhesive polymer has a functional group capable of reacting with a crosslinking agent by radical polymerization upon irradiation with energy rays. Examples of the functional group include carbon-carbon double bonds (radical polymerizable double bonds) such as an acryl group, a methacryl group, an allyl group, and a styryl group. A carbon-carbon double bond (radical polymerizable double bond) is preferable because the bond strength when crosslinked with a crosslinking agent is high, decomposition reaction hardly occurs, and deterioration of characteristics over time can be effectively suppressed. .

  As a method for introducing the functional group into the pressure-sensitive adhesive polymer (acrylic resin), a method in which a comonomer having a functional group is copolymerized at the time of polymerization, or an adhesive polymer having a functional group such as a hydroxyl group or a glycidyl group is used. A method is generally used in which a monomer having a carbon-carbon double bond such as methacrylic acid or acrylic acid is introduced into the functional group after the polymerization. The use amount (copolymerization amount) of the comonomer having a functional group capable of reacting with the cross-linking agent is included in the total amount of all monomers used as the raw material of the pressure-sensitive adhesive polymer within a range of 1 to 40% by weight. preferable. By using a monomer mixture having such a composition, a polymer containing comonomer units having almost the same composition can be obtained.

  Examples of the pressure-sensitive adhesive polymer include acrylic resins, silicone resins, rubber resins, and the like. From the viewpoint of contamination, acrylic resins are preferable.

  From the above points, it is particularly preferable that the pressure-sensitive adhesive polymer is an acrylic resin having a radical polymerizable carbon-carbon double bond.

  Here, as for the main monomer which comprises acrylic resin, what contains acrylic acid alkylester and methacrylic acid alkylester is preferable. Examples of the alkyl acrylate ester and the alkyl methacrylate ester include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, and 2-ethylhexyl acrylate. These may be used alone or in combination of two or more. It is preferable that the usage-amount of a main monomer is contained in the range of 60 to 99 weight% in the total amount of all the monomers used as the raw material of an adhesive polymer. By using a monomer mixture having such a composition, an alkyl acrylate unit, a methacrylic acid alkyl ester unit, or a polymer containing these mixed units having substantially the same composition can be obtained.

  In addition to the comonomer unit having a functional group capable of reacting with the main monomer and the crosslinking agent, a specific comonomer having a property as a surfactant (hereinafter referred to as a polymerizable surfactant) is copolymerized in the adhesive polymer. May be. The polymerizable surfactant has the property of copolymerizing with the main monomer and comonomer, and even if contamination due to the pressure-sensitive adhesive layer occurs on the wafer surface, it can be easily removed by washing with water. Become.

  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.].

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

  Examples of the polymerization reaction mechanism of the pressure-sensitive adhesive polymer include radical polymerization, anionic polymerization, and cationic polymerization. From the viewpoint of reducing 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, it is preferable to perform polymerization by applying a radical polymerization reaction mechanism.

  The radical polymerization initiator used for polymerization by radical polymerization reaction includes benzoyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide. Organic peroxides such as ammonium persulfate, potassium persulfate, sodium persulfate, and other inorganic peroxides, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, And azo compounds such as 4,4′-azobis-4-cyanovaleric acid.

  Examples of the polymerization method of the pressure-sensitive adhesive polymer include an emulsion polymerization method, a suspension polymerization method, and a solution polymerization method. Among these, the solution polymerization method is preferable. By the solution polymerization method, the molecular weight of the pressure-sensitive adhesive polymer can be increased, and the cohesive force (crosslinking density) of the polymer itself can be improved. Further, when the pressure-sensitive adhesive polymer is obtained by the solution polymerization method, since the pressure-sensitive adhesive polymer is already dissolved in the solution, there is an advantage that a small amount of a crosslinking agent is added.

  Here, the weight average molecular weight of the pressure-sensitive adhesive polymer is preferably 100,000 to 1,000,000, more preferably 150,000 to 400,000, and still more preferably 250,000 to 350,000. When the weight average molecular weight is in the above range, the adherend (semiconductor wafer) can be more effectively improved and properties such as adhesiveness can be improved.

  On the other hand, the crosslinking agent having one or more crosslinking-reactive functional groups is a radically polymerizable crosslinking agent. Here, the number of crosslinking reactive functional groups is not particularly limited, but for example, it is preferably 4 or less from the viewpoint of imparting flexibility.

  Examples of the crosslinkable reactive functional group include a carbon-carbon double bond (radical polymerizable double bond), and since the suitable functional group of the adhesive polymer is a radical polymerizable carbon-carbon double bond, A cross-linking reactive functional group capable of cross-linking with a carbon-carbon double bond is preferable. As such a cross-linking reactive functional group, a carbon-carbon double bond (from the viewpoint of high bond strength when cross-linked with a pressure-sensitive adhesive polymer, hardly causing a decomposition reaction, and effectively suppressing deterioration of properties with time) A radically polymerizable double bond) is preferred.

  The cross-linking agent preferably has polyalkylene glycol as the main skeleton. By having the polyalkylene glycol in the main skeleton, flexibility can be imparted to the resulting crosslinked polymer, that is, the pressure-sensitive adhesive layer.

  From the above points, 1) at least one crosslinking agent is a crosslinking agent having at least one crosslinking reactive functional group capable of crosslinking reaction with the radically polymerizable carbon-carbon double bond of the adhesive polymer, or 2) polyalkylene. A crosslinking agent having glycol as the main skeleton and having at least one carbon-carbon double bond is preferred.

  Specific examples of such 1) cross-linking agents include, for example, methyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, isobornyl. Examples include methacrylate, styrene, and vinyl acetate.

  Specific examples of the crosslinking agent 2) include butoxyethylene glycol methacrylate, methoxytriethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, polyethylene glycol-type methacrylate, methoxypolypropylene glycol acrylate, and the like.

  The content of the crosslinking agent is preferably 0.1 to 30 parts by weight, and more preferably 0.5 to 25 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive polymer. 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 contamination of the wafer surface is suppressed, and sufficient adhesive force between the pressure-sensitive adhesive layer and the wafer surface is obtained. Intrusion of water and grinding debris in the wafer, damage to the wafer due to it, and contamination of the wafer surface due to the grinding debris can be effectively suppressed.

  The pressure-sensitive adhesive layer includes a cross-linked polymer obtained by cross-linking the pressure-sensitive adhesive polymer and the cross-linking agent by energy ray irradiation. In order to initiate the cross-linking reaction, a photoinitiator is usually used. . The photoinitiator is selected according to the type of energy beam to be irradiated. For example, when the energy ray to be irradiated is ultraviolet, photoinitiators include, for example, energy-irradiated benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyldiphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyro Nitrile, dibenzyl, diacetyl, β-chloranthraquinone and the like can be mentioned. Of course, it is not limited to these.

  The addition amount of such a photoinitiator is preferably 1 to 20 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive polymer.

  In addition to the pressure-sensitive adhesive polymer and the crosslinking agent, various additives can be used in combination in the pressure-sensitive adhesive layer depending on the purpose. For example, for the purpose of adjusting the adhesive properties, rosin-based, terpene resin-based tackifiers, various surfactants, and the like may be appropriately contained. Further, when the pressure-sensitive adhesive polymer is an emulsion liquid, a film increasing aid such as diethylene glycol monobutyl ether may be appropriately added within a range not impairing the effects of the present invention.

  The thickness of the pressure-sensitive adhesive layer is preferably 1 to 100 μm from the viewpoint of suppressing contamination due to the pressure-sensitive adhesive remaining on the surface of the semiconductor wafer and not causing a decrease in the sufficient adhesive force and workability during peeling. .

  In addition, the adhesive strength of the adhesive layer, that is, the adhesive strength of the adhesive film, affects both the wafer back surface grinding and chemical treatment, and the workability when peeling from the wafer. In consideration of wafer protection during wafer back-grinding and chemical processing (preventing ingress of grinding water, grinding scraps, chemicals, etc.), adherends conform to the method specified in JIS Z-0237. As an adhesive strength measured using a SUS304-BA plate under conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees, it is preferably 10 to 700 g / 25 mm. More preferably, it is 10-500 g / 25mm.

  In order to form the pressure-sensitive adhesive layer on one surface of the base film, for example, it is performed as follows. First, a coating solution containing each of the above materials (adhesive polymer, crosslinking agent, photoinitiator, etc.) is applied on a base film or a release film on a roll coater, comma coater, die coater, Mayer bar coater, reverse roll coater, It is applied and dried according to a known method such as a gravure coater. Then, when the coating film of an adhesive layer is formed in a peeling film, the said coating film is transcribe | transferred to a base film.

  Although there is no restriction | limiting in particular in the drying conditions at the time of drying, Generally, it is preferable to dry for 10 second-10 minutes in the temperature range of 80-300 degreeC. More preferably, it is dried for 15 seconds to 5 minutes in a temperature range of 80 to 200 ° C. In the present invention, in order to sufficiently accelerate the crosslinking reaction between the crosslinking agent and the pressure-sensitive adhesive polymer, after the drying of the pressure-sensitive adhesive coating solution is completed, the pressure-sensitive adhesive film is heated at 40 to 80 ° C. for about 5 to 300 hours. Also good.

  And an energy ray is irradiated with respect to the dried coating film, a crosslinked polymer is formed, and an adhesive layer is obtained.

  Here, ultraviolet rays are preferably used as the energy rays to be irradiated. That is, it is preferable to use an ultraviolet curable material for the pressure-sensitive adhesive layer.

Examples of the ultraviolet light source include a high-pressure mercury lamp, a metal halide lamp, and a black light. Moreover, it is preferable that it is 0.1-40 mW / cm < ² >, and, as for the irradiation intensity | strength of the ultraviolet-ray to irradiate, it is more preferable that it is 1-20 mW / cm < ² >. Moreover, it is preferable that irradiation time is 0.1 to 10 minutes, and 0.1 to 2 minutes is more preferable. By causing the cross-linking reaction within such a range, an efficient cross-linking reaction can be realized in a short time.

  The structure of the pressure-sensitive adhesive film according to the present invention and the manufacturing method are as described above. From the viewpoint of preventing contamination of the surface of the semiconductor wafer, the manufacturing environment for all raw materials and materials, such as a base film, a release film, and a pressure-sensitive adhesive layer, The adjustment, storage, coating and drying environment of the pressure-sensitive adhesive coating solution and the water-soluble resin layer forming coating solution are preferably maintained at a clean level of class 1,000 or less as defined in US Federal Standard 209b.

<Semiconductor wafer processing method>
Next, the semiconductor wafer processing method using the semiconductor wafer processing adhesive film of the present invention will be described in the order of steps.

  The processing method of the semiconductor wafer using this adhesive film is as follows: (1) an adhesive film attaching step of attaching the adhesive layer surface of the adhesive film for semiconductor wafer processing of the present invention to the circuit forming surface of the semiconductor wafer; And a wafer processing step for processing a circuit non-formed surface of the semiconductor wafer.

  First, (1) an adhesive film adhering step for adhering the adhesive layer surface of the adhesive film for processing a semiconductor wafer of the present invention to a circuit forming surface of a semiconductor wafer will be described.

  In the adhering step, the release film is usually peeled off from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film in an atmosphere controlled at a temperature near room temperature (18 to 30 ° C.), and the surface of the pressure-sensitive adhesive layer is exposed. An adhesive film is attached to the surface of the semiconductor wafer via

  The adhering step may be performed in a pressure range of 0.3 to 0.5 MPa under a temperature condition of 40 to 70 ° C. in consideration of adhesion of the adhesive layer to the circuit forming surface having irregularities on the surface of the semiconductor wafer. preferable.

  Under these conditions, the semiconductor wafer adheres to the surface of the semiconductor wafer without generating voids, and the thickness unevenness of the pressure-sensitive adhesive layer does not occur. As for the conditions in this attaching step, it is preferable to appropriately select the optimum combination of the temperature condition and the pressure region depending on the thickness of the adhesive layer, the step shape on the semiconductor wafer on the side where the adhesive film is attached, the arrangement, and the like.

  The operation of attaching the semiconductor wafer surface protective sheet to the surface of the semiconductor wafer may be performed manually, but is generally performed by an apparatus referred to as an automatic attaching machine to which a roll-shaped semiconductor wafer surface protective sheet is attached. Examples of such an automatic pasting machine include Takatori Co., Ltd., model: ATM-1000B, ATM-1100, TEAM-100, Nitto Seiki Co., Ltd., model: 8500 series.

Next, (2) a wafer processing process for processing the non-circuit-formed surface of the semiconductor wafer will be described.
In the adhesive film attaching step, the semiconductor wafer attached with the adhesive film is fixed to a fixing member of an apparatus according to a processing step such as a chuck table of a grinding machine through a base film layer of the adhesive film, Thus, the non-circuit-formed surface of the semiconductor wafer is processed according to the purpose. The treatment method performed here is generally at least one selected from grinding, polishing, chemical etching, and physical etching, but is not limited thereto. Further, a plurality of these processes can be performed according to the purpose.

  As a mechanical back surface grinding method for a semiconductor wafer, a known grinding method such as a through-feed method or an in-feed method is employed. Normally, in any method, grinding is performed while supplying water to the semiconductor wafer and the grindstone and cooling. Only mechanical grinding using such a grindstone can be performed.

  As an example of performing a plurality of treatments, for example, a wet treatment using a mixed acid or the like is first performed for the purpose of performing a grinding treatment to reduce the thickness of the base material to a desired thin layer, and removing and crushing the crushed layer formed in the grinding treatment. An etching method (chemical etching), a plasma etching method (physical etching), a polishing method (polishing process), or the like may be performed.

  Chemical etching includes a chemical treatment, a backside polishing called CMP, and chemical etching, which can be performed physically by plasma. For example, the chemical solution treatment uses an etching solution selected from the group consisting of acidic aqueous solutions such as hydrofluoric acid, nitric acid, sulfuric acid, and acetic acid alone or as a mixture, alkaline aqueous solutions such as aqueous potassium hydroxide and aqueous sodium hydroxide, and the like. . Among chemical treatment methods, there are a method in which a wafer is immersed in a chemical solution (dipping method), a method in which a chemical solution is selectively brought into contact with the back surface while rotating the wafer back surface (spin etching method), and the like.

  When the semiconductor wafer is made thinner or when it is desired to maintain the strength of the chip, it is preferable to carry out a step of removing the crushed layer generated on the back surface of the wafer by etching or polishing.

  The thickness of the semiconductor wafer before processing is appropriately determined depending on the diameter and type of the semiconductor wafer, and the thickness of the semiconductor wafer after processing of the semiconductor wafer back surface is appropriately determined depending on the size of the chip to be obtained, the type of circuit, and the like.

After passing through each of the above steps, other steps are performed as necessary to peel off the adhesive film.
The operation of peeling the adhesive film from the wafer surface may be performed manually, but is generally performed by an apparatus called an automatic peeling machine. In the automatic peeling machine, the thinly processed wafer is fixed to the vacuum chuck table, and the adhesive film is peeled off. When peeling the adhesive film, it is important to heat the adhesive film through the chuck table. As the heating temperature, a suitable temperature can be selected in the temperature range of 50 to 90 ° C. according to the resin to be used. Moreover, you may perform peeling of an adhesive film in the state fixed to the dicing tape etc.

  As an automatic peeling machine, Takatori Co., Ltd., Model: ATRM-2000B, ATRM-2100, Nitto Seiki Co., Ltd., Model: HR-8500II), Teikoku Seiki Co., Ltd., Model: STP series, etc. is there.

  Although the semiconductor wafer is processed as described above, the semiconductor wafer applied to the present invention is not particularly limited, and not only a general silicon wafer but also germanium, gallium-arsenic, gallium-phosphorus, gallium-arsenic-aluminum. It can be applied to any of the wafers.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples. The various characteristic values shown in the examples were measured by the following methods.
[Example 1]
-Production of UV curable adhesive polymer-
48 parts by weight of ethyl acrylate, 27 parts by weight of 2-ethylhexyl acrylate, 20 parts by weight of methyl acrylate, 5 parts by weight of glycidyl methacrylate and 0.2 part of benzoyl peroxide as a polymerization initiator were mixed, 65 parts by weight of toluene, While stirring, the mixture was added dropwise to a nitrogen-substituted flask containing 50 parts by weight of ethyl acetate at 80 ° C. over 5 hours, and the mixture was further stirred for 5 hours to be reacted. After completion of the reaction, the reaction mixture was cooled, 25 parts by weight of xylene, 2.5 parts by weight of acrylic acid and 1.5 parts by weight of tetradecylbenzylammonium chloride were added, and reacted at 80 ° C. for 36 hours while blowing air, to be radically polymerizable. A main component solution of an adhesive polymer made of an acrylic resin having a carbon-carbon double bond (weight average molecular weight: 300,000) was obtained (solid content: 38 wt%).

-Production of adhesive film-
To 100 parts by weight of the resulting adhesive polymer main agent solution, 25 parts by weight of ethoxydiethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Acrylate EC-A) as a crosslinking agent, photoinitiator (manufactured by Ciba Specialty Chemicals Co., Ltd .: Irgacure 651) ) 7 parts by weight was added to obtain an adhesive layer coating solution.

  The adhesive coating solution was applied with a comma coater on the easy-peeling surface of a 38 μm thick PET film (peeling film) that had been easily peeled (silicone treatment) on one side, and then dried at 120 ° C. for 2 minutes to obtain a thickness. A 20 μm adhesive layer coating was provided. The adhesive layer side surface of the release film provided with the coating film of the above-mentioned adhesive layer is stuck on one surface of a 75 μm-thick base PET film that has been subjected to easy adhesion treatment by corona discharge treatment on both sides and pressed. Then, the coating film of the pressure-sensitive adhesive layer was transferred.

Thereafter, ultraviolet rays were irradiated (light source: high-pressure mercury lamp, irradiation intensity: 12 mW / cm ² , time: 1 minute), and the coating film of the pressure-sensitive adhesive layer was cured with ultraviolet rays to form a pressure-sensitive adhesive layer. The change over time of the adhesive strength of the adhesive film thus obtained was confirmed. The results are shown in Table 1.

[Example 2]
To 100 parts by weight of the pressure-sensitive adhesive polymer base solution obtained in Example 1, 15 parts by weight of ethoxydiethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Acrylate EC-A) as a crosslinking agent, isobornyl acrylate (Kyoeisha Chemical ( Product name: Light acrylate IB-XA) 10 parts by weight and photoinitiator (Ciba Specialty Chemicals Co., Ltd .: Irgacure 651) 7 parts by weight were added to obtain an adhesive coating solution. Except for this, an adhesive film was obtained in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
-Preparation of adhesive emulsion-
148 parts by weight of deionized water in a polymerization reactor, 2 parts by weight of ammonium salt of polyoxyethylene nonylphenyl ether sulfate (manufactured by Nippon Emulsifier Co., Ltd., trade name: Newcol-560SF, 50% by weight aqueous solution) as an anionic surfactant (1 part by weight as a pure surfactant), 4,4′-azobis-4-cyanovaleric acid [manufactured by Otsuka Chemical Co., Ltd., trade name: ACVA] as a polymerization initiator, acrylic acid 74 parts by weight of butyl, 14 parts by weight of methyl methacrylate, 9 parts by weight of 2-hydroxyethyl methacrylate, 2 parts by weight of methacrylic acid and 1 part by weight of acrylamide were added, and emulsion polymerization was carried out at 70 ° C. for 9 hours with stirring. An acrylic resin water emulsion was obtained. This was neutralized with 14% by weight ammonia water to obtain an adhesive polymer (main agent) emulsion having a solid content of about 40% by weight.

-Production of adhesive film-
100 parts by weight of the resulting pressure-sensitive adhesive main agent emulsion (pressure-sensitive polymer concentration of about 40% by weight) was collected, and 0.65 parts by weight of an epoxy-based crosslinking agent [manufactured by Nagase ChemteX, EX-614], and a film-forming aid. 5 parts by weight of diethylene glycol monobutyl ether was added to obtain an adhesive coating solution. The adhesive coating solution was applied with a comma coater on the easy-peeling surface of a 38 μm thick PET film (peeling film) that had been easily peeled (silicone treatment) on one side, and then dried at 120 ° C. for 2 minutes to obtain a thickness. A 20 μm pressure-sensitive adhesive layer was provided. The adhesive layer-side surface of the release film provided with the above-mentioned adhesive layer is bonded to one surface of a 75 μm-thick base PET film that has been subjected to easy-adhesion treatment by corona discharge treatment on both sides, and is adhered by pressing. The agent layer was transferred.

  After the transfer, the film was heated at 60 ° C. for 72 hours, and then cooled to room temperature to obtain an adhesive film for wafer processing. The change with time of the adhesive strength of the adhesive film thus obtained was carried out in the same manner as in Example 1. The results are listed in Table 1.

[Comparative Example 2]
100 parts by weight of the pressure-sensitive adhesive main agent emulsion obtained in Comparative Example 1 (pressure-sensitive adhesive polymer concentration of about 40% by weight) was collected, and further adjusted to pH 9.3 by adding 14% by weight aqueous ammonia. Next, 2 parts by weight of an aziridine-based cross-linking agent [Nippon Shokubai Chemical Co., Ltd., Chemite PZ-33] and 5 parts by weight of diethylene glycol monobutyl ether as a film-forming aid were added to obtain a pressure-sensitive adhesive coating solution. Except for this, an adhesive film was prepared and evaluated in the same manner as in Comparative Example 1. The results obtained are listed in Table 1.

The evaluation method is as follows.
<Adhesive strength (g / 25 mm) characteristics>
According to the method defined in JIS Z-0237-1991. At 23 ° C., the sample is adhered to the surface of a SUS-BA plate having a width of 5 cm and a length of 20 cm through the pressure-sensitive adhesive layer of the sample (adhesive film), and left for 1 hour. Holding one end of the sample, peeling angle 180 °, peeling speed 300 mm / min. Then, the stress at the time of peeling the sample from the SUS-BA plate is measured and converted to g / 25 mm.

<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 evaluation criteria, a chip having a C / Si ratio of about 0.10 to 0.30 on the surface of the silicon mirror wafer chip after sticking the adhesive film is evaluated as “good”, and a chip exceeding that The surface is evaluated as “poor” due to contamination.

<Flexibility evaluation>
Affix the tape to a wafer with a groove with a height of 10 μm and a width of 400 μm. Observe the lift (degree of air intrusion) immediately after sticking and after 20 minutes. If it does not lift, the flexibility is good. If there is a lift, the flexibility is determined as “defective”.

  From the above results, in the adhesive film of this example, the adhesive strength of the film does not change greatly even after storage for 3 months, and the change in physical properties over time is suppressed, and the adhesive to the adherend (semiconductor wafer). It can be seen that no contamination due to the layer occurs.

  In particular, an acrylic pressure-sensitive adhesive polymer having a radically polymerizable double bond obtained by solution polymerization using a carbon-carbon bond, which is a stronger bond and hardly undergoes a decomposition reaction, and at least a functional group capable of reacting with the double bond In order to provide sufficient flexibility even after crosslinking, at least one kind of radically polymerizable compound having a polyalkylene glycol having the effect of imparting flexibility as a main skeleton is used as a crosslinking agent, By UV irradiation at the time of coating the adhesive, acrylic adhesive polymer and cross-linking agent are bonded by radical polymerization to form a pressure-sensitive adhesive layer with improved cross-linking density, thereby having flexibility and suppressing contamination. It can also be seen that changes in film properties over time can be suppressed.

Claims (6)

A semiconductor wafer processing adhesive film used for circuit protection when processing a semiconductor wafer,
Having a base film and an adhesive layer disposed on at least one side of the base film,
The pressure-sensitive adhesive layer uses a pressure-sensitive adhesive polymer having a functional group capable of reacting with a cross-linking agent by radical polymerization by energy ray irradiation, and a cross-linking agent having at least one cross-linking reactive functional group capable of cross-linking with the functional group. A pressure-sensitive adhesive film for processing a semiconductor wafer comprising a cross-linked polymer that is cross-linked by irradiation with energy rays.   The adhesive film for semiconductor wafer processing according to claim 1, wherein the adhesive polymer is an acrylic resin having a radical polymerizable carbon-carbon double bond.   3. The semiconductor according to claim 2, wherein at least one of the crosslinking agents is a crosslinking agent having at least one crosslinking reactive functional group capable of crosslinking reaction with the radical polymerizable carbon-carbon double bond. Adhesive film for wafer processing.   2. The crosslinking agent according to claim 1, wherein at least one of the crosslinking agents is a crosslinking agent having polyalkylene glycol as a main skeleton and having at least one carbon-carbon double bond as a crosslinking reactive functional group. Adhesive film for semiconductor wafer processing. The adhesive film sticking process which sticks the adhesive layer side of the adhesive film for semiconductor wafer processing of any one of Claims 1-4 to the circuit formation side of a semiconductor wafer,
A wafer processing step for processing a non-circuit-formed surface of the semiconductor wafer;
A method for processing a semiconductor wafer comprising: Containing a pressure-sensitive adhesive polymer having a functional group capable of reacting with a crosslinking agent by radical polymerization upon irradiation with energy rays and a crosslinking agent having at least one functional group capable of undergoing a crosslinking reaction with the functional group on one side of a base film or a release film Applying a coating liquid to form a coating film;
Irradiating the surface of the coating with energy rays to cause a crosslinking reaction between the adhesive polymer and the crosslinking agent, and curing the coating;
The manufacturing method of the adhesive film for semiconductor wafer processing characterized by having.