JP2011216735A - Adhesive tape for wafer processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tape for wafer processing, by which a wafer warpage after a process of polishing the backside of a wafer is small, and adhesion of melted base material resin film to a chuck table is reduced in each heating process after termination of the polishing process, and that is less likely torn at the time of peeling from the wafer after the heating process.SOLUTION: In an adhesive tape for wafer processing having an adhesive agent layer formed on a base material resin film, the base material resin film is configured by at least two layers of polyester resin composition. At least one layer is configured by a resin composition whose main component is a polyethylene naphthalate.

Description

  The present invention relates to a wafer processing adhesive tape used for processing a wafer in manufacturing a semiconductor device such as a silicon wafer, and is used for wafer processing used for fixing a wafer or the like and performing back surface grinding. It relates to an adhesive tape. In particular, the present invention relates to an adhesive tape for wafer processing having excellent heat resistance that can be used in a semiconductor device processing step including a plasma etching step after back grinding, a back metalizing step, or a heating step such as a die bonding film bonding step.

For semiconductor wafers, a process for affixing a semiconductor wafer surface protection adhesive tape to the pattern surface of the semiconductor wafer, a process for grinding the back surface of the semiconductor wafer, a process for mounting the wafer on a dicing tape, and peeling the surface protection adhesive tape from the semiconductor wafer. After the process, it is divided into semiconductor chips in a dicing process. The divided semiconductor chips are bonded to the lead frame in a die bonding process, and sealed with a resin for external protection in a molding process.
In particular, in the manufacture of discrete devices, a semiconductor wafer is introduced into a vacuum chamber with a surface protective adhesive tape bonded to the semiconductor wafer surface after grinding the semiconductor wafer back surface, and metal deposition or sputtering is performed on the semiconductor wafer back surface for the purpose of electrode formation. A back metallizing process is performed. In this step, heat is generated by metal vapor deposition or sputtering. Therefore, when a semiconductor wafer with a surface protecting adhesive tape is introduced into the apparatus, the surface protecting adhesive tape is required to have heat resistance.

With the recent progress of high-density mounting technology, the wafer has been made thinner, and accordingly, the demand for the thickness accuracy of the surface protecting adhesive tape is increasing. In addition, with the thinning of semiconductor wafers, during the heating process such as plasma etching, die bonding film bonding, back metallizing (metal deposition / sputtering), the surface protection adhesive tape is thermally melted and contracted, and the semiconductor wafer Problems such as breakage and poor peeling of the adhesive tape for surface protection are mentioned.
Discrete devices that perform back metallization have thicker wafers and slower progress in thinning than memory devices. However, in recent years, a method of thinning to 50 μm level is desired because of device characteristics.

  As a heat-resistant adhesive tape for surface protection, an adhesive tape in which a polyethylene terephthalate film is laminated via an energy ray curable resin composition and then the energy ray curable resin composition is cured has been proposed (Patent Document 1). reference). The inventor bonded the adhesive tape described in Patent Document 1 to a wafer, grounded the back surface of the wafer, and then measured the warpage of the wafer after heating. As a result, it was found that the adhesive tape described in Patent Document 1 has a small warpage after grinding the back surface of the wafer, but cannot sufficiently prevent the warpage of the wafer when the wafer is heated.

JP 2004-256595 A

  The problem of the present invention is that the wafer warpage after the wafer back grinding process is small, and the base resin film does not melt and adhere to the chuck table in various heating processes after the grinding process is finished, and is peeled off from the wafer after the heating process. It is an object of the present invention to provide a wafer processing tape that is not easily torn during the process.

  As a result of intensive studies to solve the above problems, the present inventors have been able to suppress shrinkage in the heating process by using a base resin film having a specific laminated structure, and after the heating process, the tape peeling I found it difficult to tear. The present invention has been made based on this finding.

That is, the present invention provides the following wafer processing tape.
<1> An adhesive tape for wafer processing in which an adhesive layer is formed on a base resin film, wherein the base resin film is composed of at least two layers of a polyester resin composition, and at least one layer is polyethylene naphthalate A pressure-sensitive adhesive tape for wafer processing, characterized in that it is composed of a resin composition containing as a main component.
<2> The wafer processing pressure-sensitive adhesive tape according to <1>, wherein the at least two base resin films are formed through an epoxy adhesive layer having a thickness of 1 to 10 μm.
<3> The adhesive tape for wafer processing according to <1> or <2>, wherein an intermediate resin layer is formed between the base resin film and the adhesive layer.
<4> The adhesive tape for wafer processing according to any one of <1> to <3>, wherein the polyester resin composition is a resin composition mainly composed of polyethylene naphthalate or polyethylene terephthalate.
<5> The adhesive tape for wafer processing according to any one of <1> to <4>, wherein the base resin film has a thickness of 5 to 38 μm.
<6> The adhesive tape for wafer processing according to any one of <3> to <5>, wherein the resin composition constituting the intermediate resin layer contains an acrylic resin as a main component.
<7> The adhesive tape for wafer processing according to any one of <1> to <6>, wherein the resin composition constituting the adhesive layer contains an acrylic resin as a main component.
<8> The adhesive tape for wafer processing according to any one of <1> to <7>, wherein the resin composition constituting the adhesive layer is radiation curable.

The pressure-sensitive adhesive tape for wafer processing of the present invention can be used particularly as a pressure-sensitive adhesive tape for surface protection used when being bonded to a semiconductor wafer and subjected to back surface grinding. By using the wafer processing pressure-sensitive adhesive tape of the present invention, high wafer in-plane processing accuracy can be obtained, and when bonded to a wafer, warpage of the wafer can be corrected and reduced.
In addition, the thermal dimensional stability of the tape is high even in heating processes such as stress relief by plasma etching, die bonding film bonding, and back metalizing process, and wafer damage caused by tape shrinkage can be significantly reduced. . Furthermore, it is possible to provide an adhesive tape for wafer processing that is difficult to tear when peeled from the wafer after the heating step.

It is sectional drawing shown typically about one embodiment of the adhesive tape for wafer processing of this invention. It is sectional drawing shown typically about another embodiment of the adhesive tape for wafer processing of this invention. It is sectional drawing which shows typically the state by which the adhesive tape for wafer processing of this invention was bonded by the wafer surface.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the wafer processing tape 100 of the present invention has an adhesive layer 20 formed on a base resin film 10 composed of at least two layers (1 and 2). As shown in FIG. 3, the wafer processing pressure-sensitive adhesive tape 100 of the present invention is bonded to the surface of the circuit surface 300 formed on the wafer 200, the wafer back surface is ground, and a thin film wafer (not shown). ).

1. Base resin film The base resin film is composed of at least two layers, all of which are composed of a polyester resin composition, and at least one of them is a resin composition containing polyethylene naphthalate as a main component. It consists of Here, the main component means 80% by mass or more of the resin components in the resin composition. The resin that can be blended in addition to polyethylene naphthalate is selected so as not to impair the spirit of the present invention. As what can be used, at least 1 sort (s) chosen from the group which consists of a polyethylene terephthalate, a polyphenylene sulfide, a polyetherimide, and a polyimide can be mix | blended, for example. The resin component in the resin composition containing polyethylene naphthalate as the main component is preferably polyethylene naphthalate from the viewpoint of compatibility between the resins.
In the laminated film, the polyester resin composition is preferably composed mainly of polyethylene naphthalate or polyethylene terephthalate. Thereby, the tear strength can be increased while maintaining the heat resistance.
The base resin film is composed of at least two layers, and each layer is composed of a polyester resin composition, and at the same time, at least one layer is composed of a resin composition containing polyethylene naphthalate as a main component, thereby heating step In addition, it is possible to reduce the tearing of the adhesive tape for wafer processing when peeling from the wafer after the heating process is completed.

When the base resin film of the present invention is formed into at least two layers by extrusion processing, delamination is likely to occur due to insufficient adhesion between the two layers. Therefore, two or more layers are formed by laminating the formed film via an adhesive layer. It is preferable to use what was made for the base resin film. As the adhesive layer, an epoxy adhesive layer having a thickness of 1 to 10 μm is preferably used.
By setting the thickness of the epoxy adhesive layer to 1 to 10 μm, it is possible to join two or more films without affecting the wafer processability and heat resistance. The thickness of the epoxy adhesive layer is more preferably 1 to 8 μm, and particularly preferably 1 to 5 μm. If the thickness of the epoxy adhesive layer is too thin, the adhesive force between the films is insufficient, and if it is too thick, the grindability of the wafer deteriorates.

The total thickness of the base resin film of the pressure-sensitive adhesive tape for wafer processing according to the present invention is mechanical transmission characteristics (tensile strength and elongation), heat shrinkage, and radiation transmission when using a radiation curable adhesive layer. From a viewpoint of property, it is preferably 10 to 100 μm, particularly preferably 10 to 38 μm. By setting the thickness of the base resin film within this range, a tape having a small shrinkage stress during heating and cooling can be obtained. If the thickness of the base resin film is too thin, the mechanical strength is insufficient, and if it is too thick, the shrinkage rate and shrinkage stress during heating / cooling increase.
Each thickness of the laminated | stacked base resin film can be selected suitably. Each thickness is preferably 5 to 38 μm, and more preferably 5 to 25 μm.
When using a radiation-curable pressure-sensitive adhesive resin composition as the pressure-sensitive adhesive layer, it is preferable to use a radiation transparent material as the base resin film. Here, the term “radiation” refers to, for example, light such as ultraviolet rays, ionizing radiation such as laser light, or electron beam, and these are hereinafter collectively referred to as radiation.
The base resin film preferably has a Vicat softening point (JIS K 7206, load: 50 N, heating rate: 50 ° C./h, specimen size: 10 mm × 10 mm × 4 mm) of 120 ° C. or higher, 150 ° C. More preferably.
When an intermediate resin layer to be described later is provided on the base resin film, corona treatment or primer layer treatment is applied to the base resin film on the intermediate resin layer side in order to improve adhesion with the intermediate resin layer 5. You may give suitably.
Moreover, effects, such as blocking prevention, can be acquired by carrying out the surface processing or the lubricant coating of the outermost layer surface of a base-material resin film.

2. Intermediate Resin Layer As shown in FIG. 2, the wafer processing tape 100 of the present invention has an intermediate resin layer between the base resin film 10 and the adhesive layer 20 made of at least two resin films (1 and 2). 30 is formed.
The intermediate resin layer constituting the wafer processing pressure-sensitive adhesive tape 1 of the present invention preferably has a higher elastic modulus than the pressure-sensitive adhesive layer. The storage elastic modulus at 80 ° C. of the intermediate resin layer is preferably larger than the storage elastic modulus at 80 ° C. of the pressure-sensitive adhesive layer. The glass transition point (Tg) of the intermediate resin layer is preferably −20 ° C. to 100 ° C., more preferably 0 ° C. to 50 ° C. in order to give rigidity at room temperature as an adhesive tape for wafer processing. The intermediate resin layer can be provided, for example, by applying an intermediate resin layer composition containing an adhesive component and a curing component onto the base resin film and then curing the composition. For the intermediate resin layer composition, it is preferable to use a material that gradually cures by leaving it to stand at room temperature for about one week and has an elastic modulus in a preferable range. As a method of hardening the intermediate resin layer, the glass transition point (Tg) of the adhesive component used in the intermediate resin layer composition is increased, and a large amount of the curing component added to the intermediate resin layer composition is blended. Although methods, such as adding an inorganic compound filler to a resin layer composition, are mentioned, it is not limited to these.
Moreover, the material which hardens | cures by radiation irradiation may be used for the intermediate resin layer composition, and you may make it harden | cure by radiation irradiation and may adjust the hardness of an intermediate resin layer. The thickness of the intermediate resin layer is preferably 20 to 200 μm, more preferably 30 to 100 μm, from the viewpoint of cushioning in the back grinding process of the wafer and outgas suppression in the heating process. What is -60 micrometers is still more preferable. If the thickness of the intermediate resin layer is too thin, cushioning properties during the grinding process are reduced, and if the thickness of the intermediate resin layer is too thick, the effect of reducing the outgas generation amount in the heating process may be reduced. The intermediate resin layer may have a structure in which a plurality of layers are stacked.

As the adhesive component of the intermediate resin layer composition, various conventional adhesives having good compatibility with the isocyanurate type isocyanate curing agent can be used as appropriate. In the present invention, from the viewpoint of heat resistance and outgas suppression, a resin composition containing an acrylic resin as a main component is particularly preferable. “Acrylic resin as the main component” means that 70% or more of the base resin is composed of an acrylic polymer.
Examples of the acrylic polymer include (meth) acrylic acid ester copolymers composed of structural units derived from (meth) acrylic acid ester monomers and (meth) acrylic acid derivatives. Here, examples of the (meth) acrylic acid ester monomer include (meth) acrylic acid cycloalkyl ester, (meth) acrylic acid benzyl ester, and (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl group. Used. In particular, n-butyl methacrylate (n-BMA) is preferable from the viewpoint of improving flexibility due to an increase in the distance between cross-linking points when a cross-linking agent described later is used. Moreover, as a (meth) acrylic acid derivative, the hydroxyethyl acrylate which has a hydroxyl group can be mentioned, for example. As the resin component other than the acrylic polymer, a resin component having good compatibility with the acrylic adhesive component and causing no problem in adhesiveness can be blended.

An isocyanurate type isocyanate can be included as a curing component of the intermediate resin layer composition. Isocyanurate type isocyanates may be used alone or in combination of two or more. Further, if necessary, a curing agent other than the isocyanurate type isocyanate can be further added. The isocyanurate type isocyanate in the present invention is a compound represented by the following general formula (I). Here, R ₁ , R ₂ and R ₃ in the formula (I) are each independently an organic group such as an alkyl group, for example, but any atom or organic group can be used as long as the heat resistance is not impaired. Can be used. As the isocyanurate type isocyanate, specifically, Duranate (registered trademark) TKA-100 (manufactured by Asahi Kasei Chemicals Corporation) or the like can be used as a commercially available product. The isocyanurate type isocyanate is produced, for example, by polymerizing diisocyanate. Examples of such diisocyanates include hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 2,4′-dicyclohexylmethane diisocyanate, lysine diisocyanate, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 '-[2,2-bis (4-phenoxyphenyl) propane] diisocyanate, and the like. .

  The basic skeleton represented by the formula (I) is a case where the diisocyanate having one isocyanurate ring is a trimer, but the isocyanurate type isocyanate includes a pentamer having two isocyanurate rings, A heptamer having three nurate rings may be included.

  These curing components act as cross-linking agents, and the intermediate resin layer has a three-dimensional network structure due to the cross-linking structure formed as a result of reaction with a component having a functional group that can be incorporated into the cross-linking, such as an adhesive component such as an acrylic resin. It becomes difficult to soften even when the temperature rises during processing. Since the isocyanurate type isocyanate has a ring structure with high heat resistance, the intermediate resin layer after curing using the isocyanate and the unreacted cured component itself are decomposed by heat at the time of wafer processing, and the wafer is contaminated. It can suppress generating as outgas.

  The preferred blending amount of the isocyanurate type isocyanate curing agent in the present invention is the isocyanurate type isocyanate curing of the curing component of the intermediate resin layer composition from the viewpoint of suppressing outgassing due to an increase in the crosslinking point of the intermediate resin layer composition after curing. The mixing ratio of the total number of moles (β) of all hydroxyl groups (OH) contained in the adhesive component of the intermediate resin layer composition to the total number of moles (α) of isocyanate groups (NCO) of the agent is 0.5 ≦ α / β ≦ 5.0, preferably 0.8 ≦ α / β ≦ 2.0, and more preferably 1.0 ≦ α / β ≦ 1.5. If α / β is too small, there are many uncrosslinked portions of the adhesive component in the composition after curing, and it tends to decompose during heating, which is likely to cause outgassing. On the other hand, if α / β is too large, the curing agent remaining without reacting with the base polymer may be caused by the generation of gas such as urea due to the reaction with moisture in the air or the curing agent itself may be contaminated. It can be a cause.

  Further, by providing the intermediate resin layer with radiation curability, preferably using an ultraviolet curable resin, the resin can be cured and shrunk by radiation curing after the grinding step to improve heat resistance and then sent to the heating step. In order to impart radiation curability, for example, an acrylate oligomer having a photopolymerizable carbon-carbon double bond may be added to the intermediate resin layer. As these oligomers, low molecular weight compounds having at least two photopolymerizable carbon-carbon double bonds in a molecule that can be three-dimensionally reticulated by light irradiation are widely used. Specifically, trimethylolpropane triacrylate, Tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6 hexanediol diacrylate, polyethylene glycol di Acrylate and oligoester acrylate are widely applicable. In addition to the above acrylate compounds, urethane acrylate oligomers can also be used. The urethane acrylate oligomer includes a polyol compound such as polyester type or polyether type and a polyvalent isocyanate compound (for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diene). A terminal isocyanate urethane prepolymer obtained by reacting isocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc.) with an acrylate or methacrylate having a hydroxyl group (for example, 2-hydroxyethyl) Acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, etc.) It was obtained.

  When the intermediate resin layer is cured by radiation, a photopolymerizable initiator can be further added to the intermediate resin layer. For example, isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, benzylmethyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethylphenylpropane, or the like can be used in combination as a photopolymerizable initiator. By adding one or more of these to the intermediate resin layer, the polymerization reaction can proceed efficiently. Furthermore, a tackifier, a tackifier, a surfactant, or other modifiers can be blended in the intermediate resin layer as necessary.

3. Adhesive Layer As shown in FIG. 1, an adhesive layer 20 is formed on a base resin film 10 to produce an adhesive tape 100 for wafer processing of the present invention. Further, as shown in FIG. 2, the intermediate resin layer 30 is formed on the base resin film 10, and the adhesive layer 20 is further formed, whereby the adhesive tape 100 for wafer processing of the present invention is manufactured.
When the intermediate resin layer is formed, the pressure-sensitive adhesive layer can be produced by forming the intermediate resin layer on the base resin film and then applying the pressure-sensitive adhesive. The pressure-sensitive adhesive layer is preferably one that does not cause wafer cracking during the grinding process and has such adhesiveness that the circuit surface is not contaminated by dust intrusion during grinding. Furthermore, since there is a risk of wafer cracking due to UV curing shrinkage of the adhesive as the wafer is thinned, the shrinkage after UV curing is small, the gas generated by the heating process is small, and the heating process is passed. Those whose adhesive strength is sufficiently lowered even after irradiation with ultraviolet rays are preferable. For example, a polymer (a) in which a residue having a (meth) acrylic monomer portion having a radiation-curable carbon-carbon double bond-containing group is bonded to a repeating unit of a main chain as a base resin, An acrylic pressure-sensitive adhesive using a resin composition containing a compound (b) selected from isocyanates, melamine / formaldehyde resins, and epoxy resins can be used.
A preferable introduction amount of the radiation curable carbon-carbon double bond in the polymer (a) is an iodine value of 0.5 to 20, more preferably 0.8 to 10. If the iodine value is within this range, the effect of reducing the adhesive strength after irradiation can be obtained, the compound (a) itself is stable, and the production becomes easy. The polymer (a) preferably has a glass transition point (Tg) of −70 ° C. to 0 ° C. When the glass transition point (Tg) is −70 ° C. or higher, the glass has a sufficient heat resistance against the heat accompanying radiation irradiation.

The polymer (a) may be produced by any method. For example, as the polymer (a), an acrylic copolymer and / or a methacrylic copolymer having a radiation curable carbon-carbon double bond with respect to a repeating unit of the main chain and having a functional group. The thing obtained by making (a1) and the compound (a2) which has a functional group which can react with this functional group react is mentioned. Further, an acrylic copolymer and / or a methacrylic copolymer having a functional group is defined as (a1 ′), which has a radiation-curable carbon-carbon double bond and can react with the functional group of (a1 ′). A compound having a group may be (a2 ′), and these may be reacted to obtain a polymer (a).
The acrylic copolymer and / or methacrylic copolymer (a1) having a radiation curable carbon-carbon double bond and a functional group with respect to the repeating unit of the main chain is, for example, radiation curing. Monomer (a1-1) such as acrylic acid alkyl ester and / or methacrylic acid alkyl ester having a functional carbon-carbon double bond and monomer (a1-2) having a functional group Obtainable.

  Examples of the monomer (a1-1) include (meth) acrylic acid alkyl esters having 6 to 12 carbon atoms in the alkyl ester alkyl group (for example, hexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2- Ethyl hexyl acrylate, dodecyl acrylate, decyl acrylate). In addition, (meth) acrylic acid alkyl ester having 5 or less carbon atoms in the alkyl group of the alkyl ester (for example, pentyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl acrylate, methyl acrylate, or similar methacrylates) Can be mentioned.

As the monomer (a1-1), the glass transition point tends to be lower as the alkyl ester of the alkyl ester having a larger carbon number of (meth) acrylic acid alkyl ester is used. Therefore, the polymer (a) having a desired glass transition point can be obtained by appropriately selecting the carbon number of the alkyl group of the alkyl ester of the monomer (a1-1).
In addition to the glass transition point, a low molecular compound having a carbon-carbon double bond such as vinyl acetate, styrene or acrylonitrile is added to (a1-1) for the purpose of improving compatibility with other components and various performances. A polymer (a) can be obtained. The blending amount of these low molecular compounds is preferably 5% by mass or less of the monomer (a1-1).

  Examples of the functional group that the monomer (a1-2) has include a carboxyl group, a hydroxyl group, an amino group, a cyclic acid anhydride group, an epoxy group, and an isocyanate group. Specific examples of the monomer (a1-2) include, for example, acrylic acid, methacrylic acid, cinnamic acid, itaconic acid, fumaric acid, phthalic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, Glycol monoacrylates, glycol monomethacrylates, N-methylolacrylamide, N-methylolmethacrylamide, allyl alcohol, N-alkylaminoethyl acrylates, N-alkylaminoethyl methacrylates, acrylamides, methacrylamides, maleic anhydride Itaconic anhydride, fumaric anhydride, phthalic anhydride, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and some isocyanate groups of polyisocyanate compounds are hydroxyl groups or carbohydrates. Sill group and a radiation-curable carbon - can enumerate such as those urethanization a monomer having a carbon-carbon double bond.

When the functional group (a2) is a carboxyl group or a cyclic acid anhydride group, examples of the functional group (a1) include a hydroxyl group, an epoxy group, and an isocyanate group. When the functional group (a2) is a hydroxyl group, examples of the functional group (a1) include a cyclic acid anhydride group and an isocyanate group. When the functional group (a2) is an amino group, examples of the functional group (a1) include an epoxy group and an isocyanate group. When the functional group of (a2) is an epoxy group, examples of the functional group of (a1) include a carboxyl group, a cyclic acid anhydride group, and an amino group.
As specific examples, those similar to those listed in the specific examples of the monomer (a1-2) can be listed.

In the reaction of (a1) and (a2), by leaving an unreacted functional group, the acid value or the hydroxyl value can be suitably set within a range as described later.
The polymer (a) containing as a constituent unit a (meth) acrylic monomer having one or more radiation-curable carbon-carbon double bond-containing groups with respect to the repeating unit of the main chain is a solution in various solvents It can be obtained by polymerization. As the organic solvent in the case of solution polymerization, a ketone, ester, alcohol, or aromatic solvent can be used. In general, it is preferable to use a solvent having a boiling point of 60 to 120 ° C. as a good solvent for an acrylic polymer. For example, toluene, ethyl acetate, isopropyl alcohol, benzene, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, and the like can be used. As the polymerization initiator, radical generators such as azobis compounds such as α, α′-azobisisobutylnitrile and organic peroxide compounds such as benzoyl peroxide can be used. At this time, if necessary, a catalyst and a polymerization inhibitor can be used in combination, and the polymer (a) having a desired molecular weight can be obtained by adjusting the polymerization temperature and the polymerization time. In terms of adjusting the molecular weight, it is preferable to use a mercaptan or carbon tetrachloride solvent. The synthesis of the polymer (a) is not limited to solution polymerization, and other methods such as bulk polymerization and suspension polymerization may be used.

  The molecular weight of the polymer (a) is preferably about 300,000 to 1,500,000. If it is less than 300,000, wafer surface contamination due to low molecular weight components tends to occur. In order to prevent this contamination as much as possible, the molecular weight is preferably 400,000 or more. Further, if the molecular weight exceeds 1,500,000, there is a possibility of gelation during synthesis and coating. In addition, it is preferable for the polymer (a) to have an OH group having a hydroxyl value of 5 to 100 because the risk of tape peeling failure can be further reduced by reducing the adhesive strength after irradiation. The iodine value was calculated based on the Wijs method, and the molecular weight was obtained by dissolving 1% solution obtained in tetrahydrofuran with gel permeation chromatography (trade name: 150-C ALC / manufactured by Waters). The value measured by GPC) is calculated as a polystyrene-reduced mass average molecular weight. The hydroxyl value is calculated by the FT-IR method, and the acid value is calculated in accordance with 11.1 of JIS K 5407.

  Next, the compound (b) which is another component of the pressure-sensitive adhesive layer will be described. The compound (b) is a compound selected from polyisocyanates, melamine / formaldehyde resins, and epoxy resins, and can be used alone or in combination of two or more. This compound (b) acts as a cross-linking agent, and improves the cohesive strength of the pressure-sensitive adhesive mainly composed of the compounds (a) and (b) after the application of the pressure-sensitive adhesive by the cross-linked structure resulting from the reaction with the polymer (a). can do. Polyisocyanates are not particularly limited, and examples thereof include hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and 2,4′-dicyclohexylmethane diisocyanate. Lysine diisocyanate, lysine triisocyanate, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenyl ether diisocyanate, 4,4 ′-[2,2-bis (4-phenoxyphenyl) propane ] Diisocyanate etc. can be mentioned, Specifically, Coronate L (made by Nippon Polyurethane Co., Ltd.) etc. can be used as a commercial item. Further, as the melamine / formaldehyde resin, specifically, Nicalac MX-45 (manufactured by Sanwa Chemical Co., Ltd.), Melan (manufactured by Hitachi Chemical Co., Ltd.), etc. can be used as commercial products. Furthermore, TETRAD-X (made by Mitsubishi Chemical Corporation) etc. can be used as an epoxy resin. In the present invention, it is particularly preferable to use polyisocyanates. As addition amount of (b), it is preferable to set it as 0.1-10 mass parts with respect to 100 mass parts of polymers (a), and it is more preferable to set it as 0.4-3 mass parts. If the added amount of (b) is too small, the effect of improving the cohesive force may not be sufficient. If the added amount of (b) is too large, the curing reaction proceeds rapidly during the blending and coating operations of the pressure-sensitive adhesive, and the crosslinked structure. May be formed, and workability may be impaired.

  Moreover, in this invention, it is preferable that the photoinitiator (c) is contained in the adhesive layer. The photopolymerization initiator (c) contained in the pressure-sensitive adhesive layer is not particularly limited as long as it reacts with radiation transmitted through the base material and the intermediate resin layer, and a conventionally known photopolymerization initiator (c) can be used. For example, benzophenones such as benzophenone, 4,4′-dimethylaminobenzophenone, 4,4′-diethylaminobenzophenone and 4,4′-dichlorobenzophenone, acetophenones such as acetophenone and diethoxyacetophenone, 2-ethylanthraquinone, t- Examples include anthraquinones such as butylanthraquinone, 2-chlorothioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzyl, 2,4,5-triallylimidazole dimer (rophine dimer), and acridine compounds. These can be used alone or in combination of two or more. As addition amount of (c), it is preferable to set it as 0.1-10 mass parts with respect to 100 mass parts of polymers (a), and it is more preferable to set it as 0.2-5 mass parts.

  Furthermore, the intermediate resin layer and the pressure-sensitive adhesive layer used in the present invention can be blended with a tackifier, a tackiness modifier, a surfactant, or other modifiers, if necessary. Moreover, you may add an inorganic compound filler suitably. The adhesive layer preferably has a thickness of 5 to 100 μm, more preferably 5 to 50 μm, and still more preferably 10 to 30 μm. Further, the total thickness of the intermediate resin layer and the pressure-sensitive adhesive layer is preferably 25 to 200 μm. The pressure-sensitive adhesive layer may have a structure in which a plurality of layers are laminated.

4). Release Film The release film is also called a separator, a release layer, or a release liner, and is provided as necessary for the purpose of protecting the adhesive layer and for the purpose of smoothing the adhesive. Examples of the constituent material of the release film include synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate, and paper. The surface of the release film may be subjected to release treatment such as silicone treatment, long-chain alkyl treatment, fluorine treatment, etc., as necessary, in order to enhance the peelability from the pressure-sensitive adhesive layer. If necessary, an ultraviolet ray prevention treatment may be performed so that the pressure-sensitive adhesive layer does not react with environmental ultraviolet rays. The thickness of a peeling film is 10-100 micrometers normally, Preferably it is 25-5 micrometers.

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to these examples.
An intermediate resin layer composition and a pressure-sensitive adhesive resin composition were prepared as described below, and a wafer processing pressure-sensitive adhesive tape was prepared based on the production method of the example, and the test and evaluation were performed.

[Preparation of intermediate resin layer composition]
[Intermediate resin layer composition 1A]
100 parts by mass of acrylic resin (n-butyl methacrylate) (weight average molecular weight: 200,000, glass transition temperature: 20 ° C.), isocyanurate type isocyanate (manufactured by Asahi Kasei Chemicals Corporation, trade name: TKA-100) as NCO It mixed so that it might become /OH=1.0, and the intermediate resin layer composition 1A was obtained.

[Preparation of adhesive layer resin composition]
[Adhesive layer resin composition 2A]
In 400 g of toluene as a solvent, 128 g of n-butyl acrylate, 307 g of 2-ethylhexyl acrylate, 67 g of methyl methacrylate, 1.5 g of methacrylic acid, and a mixed solution of benzoyl peroxide as a polymerization initiator are appropriately adjusted in a dropping amount, and reacted. The solution of the compound (a1) having a functional group was obtained by adjusting the temperature and the reaction time. Next, 2.5 g of 2-hydroxyethyl methacrylate separately synthesized from methacrylic acid and ethylene glycol was added to the polymer solution as the compound (a2) having an ultraviolet curable carbon-carbon double bond and a functional group, and the reaction temperature and Of the polymer (a) in which the reaction time is adjusted and a residue having a (meth) acrylic monomer part having a radiation-curable carbon-carbon double bond-containing group is bonded to the repeating unit of the main chain A solution was obtained. The weight average molecular weight of the polymer (a) was 800,000. The weight average molecular weight was calculated by converting a 1% solution obtained by dissolving in tetrahydrofuran by gel permeation chromatography (trade name: 150-C ALC / GPC, manufactured by Waters) in terms of polystyrene. It is. The iodine value calculated by the Wijs method was 10.
Subsequently, Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) as a polyisocyanate (b) is added to 100 parts by mass of the polymer (a) in the polymer (a) solution, and SPEEDCURE is used as a photopolymerization initiator. 0.3 parts by mass of TPO (manufactured by DKSH Japan Ltd.) and SPEEDCURE
3.0 parts by mass of BKL (manufactured by DKSH Japan Co., Ltd.), 0.1 part by mass of methoquinone as a polymerization inhibitor, and 150 parts by mass of ethyl acetate as a solvent are added to and mixed with the compound (a) solution, and UV curable. 2A of the adhesive layer resin composition was prepared.

[Creation of base resin film]
[Base resin film 3A]
A polyethylene naphthalate (PEN) film having a thickness of 12.5 μm and a polyethylene terephthalate (PET) film having a thickness of 12.5 μm were laminated with an epoxy adhesive layer having a thickness of 5 μm to obtain a base resin film 3A.
[Base film 3B]
A polyethylene naphthalate (PEN) film having a thickness of 12.5 μm and a polyethylene terephthalate (PET) film having a thickness of 16 μm were laminated with an epoxy adhesive layer having a thickness of 5 μm to obtain a base resin film 3B.
[Base film 3C]
A polyethylene naphthalate (PEN) film having a thickness of 12.5 μm and a polyethylene terephthalate (PET) film having a thickness of 25 μm were laminated with an epoxy adhesive layer having a thickness of 5 μm to obtain a base resin film 3C.
[Base film 3D]
A 25 μm thick polyethylene naphthalate (PEN) film and a 12.5 μm thick polyethylene terephthalate (PET) film were laminated with a 5 μm thick epoxy adhesive layer to obtain a base resin film 3D.
[Base film 3E]
Each layer obtained by laminating a polyethylene terephthalate (PET) film having a thickness of 12.5 μm, a polyethylene naphthalate (PEN) film having a thickness of 12.5 μm, and a polyethylene terephthalate (PET) film having a thickness of 12.5 μm in this order, respectively. The base resin film 3E was obtained by laminating with an epoxy adhesive layer having a thickness of 5 μm.
[Base film 3F]
A polyethylene terephthalate (PET) film having a thickness of 12.5 μm and a polyethylene terephthalate (PET) film having a thickness of 12.5 μm were laminated with an epoxy adhesive layer having a thickness of 5 μm to obtain a base resin film 3F.

[Example 1]
The intermediate resin layer composition 1A was applied to the PET film of the base resin film 3A and dried to form an intermediate resin layer having a thickness of 50 μm after drying. Further, the pressure-sensitive adhesive layer resin composition 2A was applied on the intermediate resin layer and dried to form a pressure-sensitive adhesive layer having a thickness of 30 μm after drying, thereby obtaining a pressure-sensitive adhesive tape for wafer processing having a total thickness of 110 μm. .
[Example 2]
The intermediate resin layer composition 1A was applied to the PET film of the base resin film 3B and dried to form an intermediate resin layer having a thickness of 50 μm after drying. Otherwise, a wafer processing adhesive tape was obtained in the same manner as in Example 1.
[Example 3]
The intermediate resin layer composition 1A was applied to the PET film of the base resin film 3C and dried to form an intermediate resin layer having a thickness of 50 μm after drying. Otherwise, a wafer processing adhesive tape was obtained in the same manner as in Example 1.
[Example 4]
The intermediate resin layer composition 1A was applied to the PET film of the base resin film 3D and dried to form an intermediate resin layer having a thickness of 50 μm after drying. Otherwise, a wafer processing adhesive tape was obtained in the same manner as in Example 1.
[Example 5]
The intermediate resin layer composition 1A was applied to the PET film of the base resin film 3E and dried to form an intermediate resin layer having a thickness of 50 μm after drying. Otherwise, a wafer processing adhesive tape was obtained in the same manner as in Example 1.

[Comparative Example 1]
A wafer processing adhesive tape was obtained in the same manner as in Example 1, except that a polyethylene naphthalate (PEN) single layer film having a thickness of 25 μm was used as the base resin film.
[Comparative Example 2]
A pressure-sensitive adhesive tape for semiconductor wafer processing was obtained in the same manner as in Example 1, except that a single-layer film of polyethylene terephthalate (PET) having a thickness of 25 μm was used as the base resin film.
[Comparative Example 3]
1 A of intermediate resin layer compositions were apply | coated to the said base resin film 3F, it was made to dry, and the intermediate resin layer whose film thickness after drying is 50 micrometers was formed. Otherwise, a wafer processing adhesive tape was obtained in the same manner as in Example 1.

[Test and evaluation]
About the adhesive tape for semiconductor wafer processing of Examples 1-5 and Comparative Examples 1-2, the test and evaluation were performed as follows.
[Warpage of wafer after grinding 50μm]
Using a full auto grinder DFG8540 (trade name) manufactured by DISCO, an 8 inch diameter silicon bare wafer bonded with an adhesive tape for wafer processing was ground to a thickness of 50 μm. Thereafter, the wafer was placed on a horizontal plane, and the maximum height of the peripheral edge of the wafer was defined as wafer warpage. When the wafer warpage was 10 mm or less, the wafer warpage was determined to be acceptable, and the wafer warpage exceeding 10 mm was determined to be unacceptable.
[TTV]
Using a full auto grinder DFG8540 (trade name) manufactured by DISCO, an 8 inch diameter silicon bare wafer bonded with an adhesive tape for wafer processing was ground to a thickness of 50 μm. Then, the ultraviolet-ray was irradiated with the intensity | strength of 500 mJ / cm < ² >, and the adhesive tape for wafer processing was peeled. The thickness variation in the wafer surface after the adhesive tape was peeled was measured and used as TTV (Total Thickness Variation). A case where the TTV was 5 μm or less was determined to be acceptable, and a case where the TTV exceeded 5 μm was determined to be unacceptable.
[Warpage of wafer after heating]
Using a full auto grinder DFG8540 (trade name) manufactured by DISCO, an 8 inch diameter silicon bare wafer bonded with a wafer processing adhesive tape was ground to a thickness of 100 μm. Then, the wafer with which the wafer processing adhesive tape was bonded on the hotplate heated at 180 degreeC was mounted, and it cooled rapidly. Thereafter, the wafer was placed on a horizontal plane, and the maximum height of the peripheral edge of the wafer was defined as the wafer warp after heating. When the wafer warp after heating was 20 mm or less, it was judged as acceptable, and when it exceeded 20 mm, it was judged as unacceptable.
[Tear strength]
A test piece having a length of 63 mm and a width of 75 mm was cut out from the wafer processing pressure-sensitive adhesive tape, and a tear having a length of 20 mm from the end was formed at a position of 37.5 mm in the width direction. Using this test piece, JIS
By the method based on K7128-2, using a tensile tester, the tensile strength was taken as the tensile strength when the sample was pulled in the length direction and was torn.

  Table 1 summarizes the structures and evaluation results of the wafer processing pressure-sensitive adhesive tapes of Examples and Comparative Examples.

As shown in Table 1, the wafer processing pressure-sensitive adhesive tape in which the base resin film is composed of at least two layers of polyester and at least one layer is composed of polyethylene naphthalate are both warped of the wafer after 50 grinding. The warpage of the wafer after heating was small, and the tear strength was acceptable.
On the other hand, as can be seen from Table 2, in Comparative Example 1 in which the base resin film is composed of a single layer of polyethylene naphthalate, the tear strength is unacceptable and a problem occurs when the tape is peeled from the wafer. Recognize. In Comparative Example 2 composed of a single layer of polyethylene terephthalate, the warpage of the wafer after heating is large. For this reason, it turns out that it is difficult to use the adhesive tape for wafer processing of the comparative example 2 at the process which passes through a heating process. Furthermore, in the base resin film comparative example 3 in which polyethylene terephthalates are laminated, it can be seen that the warpage of the wafer, in particular, the warpage of the wafer after heating is large.

1, 2 Resin film 10 Base resin film 20 Adhesive layer 30 Intermediate resin layer 100 Adhesive tape for wafer processing 200 Wafer 300 Circuit

Claims (8)

  A pressure-sensitive adhesive tape for wafer processing, wherein a pressure-sensitive adhesive layer is formed on a base resin film, wherein the base resin film is composed of at least two layers of a polyester resin composition, and at least one layer is mainly composed of polyethylene naphthalate A pressure-sensitive adhesive tape for wafer processing, comprising: a resin composition as described above.   The pressure-sensitive adhesive tape for wafer processing according to claim 1, wherein at least two layers of the base resin film are formed through an epoxy adhesive layer having a thickness of 1 to 10 μm.   The adhesive tape for wafer processing according to claim 1 or 2, wherein an intermediate resin layer is formed between the base resin film and the adhesive layer.   The pressure-sensitive adhesive tape for wafer processing according to any one of claims 1 to 3, wherein the polyester resin composition is a resin composition mainly composed of polyethylene naphthalate or polyethylene terephthalate.   The adhesive tape for wafer processing according to any one of claims 1 to 4, wherein the base resin film has a thickness of 5 to 38 µm.   The pressure-sensitive adhesive tape for wafer processing according to any one of claims 3 to 5, wherein the resin composition constituting the intermediate resin layer contains an acrylic resin as a main component.   The pressure-sensitive adhesive tape for wafer processing according to any one of claims 1 to 6, wherein the resin composition constituting the pressure-sensitive adhesive layer contains an acrylic resin as a main component.   The pressure-sensitive adhesive tape for wafer processing according to any one of claims 1 to 7, wherein the resin composition constituting the pressure-sensitive adhesive layer is radiation curable.

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