JPH05175332A - Adhesive sheet for semiconductor wafer - Google Patents

Abstract

PURPOSE:To improve the yield in dicing and pickup processes by stacking a mold release substrate and a resin film through an adhesive layer and specifying the centerline average roughness of the exposed face of the mold release substrate. CONSTITUTION:For example, a rough machined layer in which the centerline average roughness of the exposed face of a mold release substrate is within the range from 0. 05 to 10mum is formed on one side of a biaxially oriented polyethylene terephthalate film. Then, a mold release layer is formed on the opposed face of the rough machined layer of the film. After an adhesive composition is applied on the mold release face of the mold release substrate and is dried, a resin film is stuck on the applied face and roll winding is performed and an adhesive sheet for sticking of a semiconductor wafer is obtained. The adhesive sheet obtained by the above is stuck on the semiconductor wafer in a dicing process, and a poor cutting does not occur. Further, the high yield can be obtained in a pickup process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive sheet for adhering a semiconductor wafer.

[0002]

2. Description of the Related Art Semiconductor wafers such as silicon and gallium arsenide are manufactured in a large diameter state, cut into small pieces (dicing) into element pieces, and then transferred to a pickup step and a mounting step. There is. In a dicing process of a semiconductor wafer, the wafer is pressure-sensitive adhesively fixed on an adhesive sheet and cut into a predetermined size.

Generally, the pressure-sensitive adhesive sheet used for such an application comprises applying a pressure-sensitive adhesive composition to the release surface of a releasable substrate,
After drying, a resin film is attached to the surface of the pressure-sensitive adhesive layer and provided in a rolled state. However, since the slipperiness between the releasable base material and the resin film is poor, the air layer is nonuniformly accumulated in the roll, the resin film is deformed over time, and the thickness of the pressure-sensitive adhesive layer is nonuniform. As a result, cutting defects occur in the dicing process, which interferes with the pickup process, and improvements have been demanded.

[0004]

Means for Solving the Problems The inventors of the present invention have made extensive studies in view of the above problems, and as a result, an adhesive sheet having a certain specific structure is suitable as an adhesive sheet for wafer sticking, and yield in the dicing step and the pickup step is improved. The present inventors have completed the present invention by discovering that it significantly increases. That is,
The gist of the present invention is a sheet obtained by laminating a releasable base material and a resin film via an adhesive layer, wherein the center line average roughness (Ra) of the exposed surface of the releasable base material is 0.05-10
The pressure-sensitive adhesive sheet for sticking a semiconductor wafer is characterized by having a thickness of μm.

The present invention will be described in detail below. The base material of the releasable substrate in the present invention includes high-density base paper such as glassine paper; clay-coated paper, kraft paper, high-quality paper, woven cloth, nonwoven cloth, synthetic paper and the like, polyethylene, polyester,
Polylaminate base paper laminated with polypropylene and the like; plastic films such as polyethylene, polypropylene, polyester polycarbonate, polyimide, polyamide, polyaramid, polyphenylene sulfide, etc. are mentioned, but a plastic film that does not generate paper dust is preferable. Above all, a polyester film is preferable in terms of mechanical strength, dimensional stability, heat resistance, price, and the like.

The term "polyester" as used herein means an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid or naphthalenecarboxylic acid or an ester thereof with ethylene glycol, diethylene glycol, 1,4-butanediol,
It is a polyester produced by polycondensing glycols such as neopentyl glycol and 1,4-cyclohexanedimethanol.

The polyester composed of these acid component and glycol component can be produced by any method commonly used. For example, a transesterification reaction is carried out between a lower alkyl ester of an aromatic dicarboxylic acid and a glycol, or an aromatic dicarboxylic acid and a glycol are directly esterified to give a bisglycol ester of a substantially aromatic dicarboxylic acid. Or a low polymer thereof is formed and then polycondensed at a temperature of 240 ° C. or higher under reduced pressure. At this time, ordinary catalysts, stabilizers, various additives and the like can be optionally used.

Typical examples of such polyesters include poly (ethylene terephthalate), poly (ethylene naphthalate) and poly (1,4-cyclohexylene dimethylene terephthalate). The polyester may be a homopolymer or a mixture of these polyesters. In addition, polyester film contains various stabilizers, UV absorbers, lubricants,
Pigments, antioxidants, plasticizers, antistatic agents and the like may be added.

The mold-releasing substrate used in the present invention is usually coated on one surface with a compound having a mold-releasing property such as silicone or fluorine and dried and cured to form a mold-releasing layer. Preferred as such a release agent is a silicone compound that is cured by heat or an active energy ray, and when a plastic film such as a polyester film is used as a base material, it is possible to prevent the plastic film from being deformed by heat. For these reasons, it is particularly preferable to use a silicone compound that cures with active energy rays.

The center average roughness (Ra) of the exposed surface of the releasable substrate is in the range of 0.05 to 10 μm, preferably 0.1 to 3 μm. Ra is 0.05μ
If it is less than m, blocking with the resin film occurs and R
When a exceeds 10 μm, uneven marks are transferred to the resin film and the flatness is deteriorated. As a roughening means, a particle kneading method, an embossing method, a sandblasting method, an etching method,
There are electric discharge machining methods, coating methods and the like. When a plastic film such as a polyester film is used as the substrate, the coating method is preferably used because the surface roughening treatment can be easily performed. In the sand blast method, when roughening the plastic film, fine powder is sprayed on the film surface, but the shavings or fine powder of the film remains on the film surface, which causes contamination in the adhesive sheet manufacturing process described above. I have a concern.

The coating method is as follows. For example, particles of silica or the like are mixed with a binder such as polyester resin in an appropriate amount, and an organic solvent is added to the mixture to prepare a coating solution having an appropriate viscosity.
It is a method of forming this coating liquid on a releasable substrate by a gravure coater, a reverse coater, a wire bar coater or the like. Examples of the particles include, in addition to silica, inorganic particles such as alumina, calcium carbonate, and titanium oxide, and organic particles such as silicone resin, fluororesin, and benzoguanamine resin.

As the binder, in addition to the polyester resin, for example, acrylic resin, polyvinyl butyral resin, polyurethane resin, phenoxy resin, epoxy resin, polyvinyl chloride resin, radical polymerizable double bond may be used. The compound etc. which are contained are mentioned. Further, the coating liquid may contain conductive powder, antistatic agent, defoaming agent, coating property improving agent, thickener, particle dispersion stabilizing resin and the like, if necessary.

Further, a cross-linking agent may be blended in order to improve the abrasion resistance of the coating film, but a compound containing two or more (meth) acryloyl groups in one molecule is cross-linked by an active energy ray. It is preferably cured. If the abrasion resistance of the coating film is insufficient, shavings of the coating film may cause contamination in the above-mentioned pressure-sensitive adhesive sheet manufacturing process.

Two or more (meta) s in one molecule as used herein
Examples of the compound containing an acryloyl group include 2
Examples thereof include compounds obtained by reacting one or more polyhydric alcohols or derivatives thereof with a compound having a group capable of reacting with these compounds, or a compound having an acryloyl group or a methacryloyl group. As a concrete example,
Examples thereof include compounds obtained by reacting a polyhydric alcohol with (meth) acrylic acid, a halide thereof or a lower alkyl ester thereof. Examples of the polyhydric alcohol here include ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, tetraethylene glycol, trimethylolpropane, pentaglycerol, pentaerythritol, dipentaerythritol, glycerin, diglycerin and the like. .. As a particularly preferred compound obtained from these alcohols and (meth) acrylic acid, a group connecting each (meth) acryloyloxy group has 20 or less carbon atoms, preferably 10 or less carbon atoms and 0 or 1 ether group. It is a hydrocarbon group which has, for example, trimethylolpropane tri (meth) acrylate, pentaglycerol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexane (meth) acrylate, ethylene glycol di (meth). ) Acrylate, propylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate and the like.

If desired, monomers and photopolymerizable oligomers copolymerizable with the compound may be used. Specific examples of the copolymerizable monomers include acrylic acid, methacrylic acid, crotonic acid or their carboxylic acids and alcohols such as methanol, ethanol, propanol, butanol, isopropanol, hexanol, 2-ethylhexanol, cyclohexanol, Ester compounds with benzyl alcohol, stearyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, glycerin, etc., glycidyl (meth) acrylate, allyl glycidyl ether, acrylonitrile, methacrylonitrile, vinyl acetate, styrene, α-methylstyrene, α-chloro. Styrene, (meth) acrylamide, N-methylol acrylamide, N-butoxymethyl (meth) acrylamide,
Examples thereof include unsaturated polyester dimethacrylate, vinyltriethoxysilane, vinyltrimethoxysilane, acryloyloxypropyltriethoxysilane, methacryloyloxypropyltriethoxysilane, acryloyloxypropyltrimethoxysilane and methacryloyloxytrimethoxysilane.

Specific examples of the photopolymerizable oligomer include epoxy (meth) acrylate, epoxidized oil (meth) acrylate, urethane acrylate, polyester (meth) acrylate and polyether (meth).
Examples thereof include acrylate, silicone (meth) acrylate, polybutadiene (meth) acrylate, polystyryl (meth) acrylate, and phosphazene (meth) acrylate.

In addition to a compound containing two or more (meth) acryloyl groups in one molecule, a suitable initiator (polymerization initiator, photosensitizer, etc.) is contained. There are various initiators, for example, 2,2-ethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, dibenzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, p-chlorobenzophenone, p-
Methoxybenzophenone, Michler's ketone, acetophenone, 2-chlorothioxanthone, anthraquinone, phenyl disulfide, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone and the like can be mentioned, and these can be used alone or in combination. Can be used. The amount of these initiators used is preferably in the range of 0.05 to 5 parts by weight with respect to 100 parts by weight of the coating film forming material.

Examples of photosensitizers include tertiary amines such as triethylamine, triethanolamine and 2-dimethylaminoethanol, alkylphosphine such as triphenylphosphine and thioethers such as β-thiodiglycol. Etc. These photosensitizers may be used either individually or in combination of two or more. The amount used is preferably in the range of 0.05 to 5 parts by weight with respect to 100 parts by weight of the coating film forming material.

The above-mentioned composition comprising a compound containing two or more (meth) acryloyl groups in one molecule is applied to a base material by a suitable means, irradiated with active energy rays to be crosslinked and cured, and a coating layer. To form. Such active energy rays include ultraviolet rays, visible rays, electron rays, X-rays, α
Rays, β rays, and γ rays can be used. The active energy ray is usually irradiated from the coating layer, but in order to enhance the adhesion to the base material, a reflection plate capable of reflecting the active energy ray is provided on the base material surface side, or the active energy ray is applied from the base material surface side. May be irradiated.

In the releasable substrate of the present invention, a release layer may be provided after the roughening treatment, or a roughening treatment may be performed after the release layer is provided. Good. If necessary, an easy adhesion layer, an antistatic layer, or the like may be provided between the base material and each layer, or an easy adhesion treatment such as corona treatment may be performed. As the adhesive used in the sheet of the present invention, conventionally known ones such as rubber-based or acrylic-based adhesives are widely used, but acrylic-based adhesives are preferable, and specifically,
It is an acrylic polymer selected from homopolymers and copolymers containing an acrylic ester as a main constituent monomer unit, a copolymer with other functional monomers, and a mixture of these polymers. For example, as the acrylic acid ester of the monomer, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, etc., and the above-mentioned methacrylic acid may be used. The thing replaced with acrylic acid can also be used preferably. In order to prevent the adhesive from adhering to the back surface of the wafer, it is preferable to use a low-adhesive adhesive.

By including an active energy ray-polymerizable compound in the pressure-sensitive adhesive layer as described above, the adhesive force is lowered by irradiating the pressure-sensitive adhesive layer with active energy rays after cutting and separating the wafer. You can Examples of such active energy ray-polymerizable compounds include those disclosed in JP-A-60-196956 and JP-A-60-2.
A low molecular weight compound having at least two photopolymerizable carbon-carbon double bonds in a molecule capable of being three-dimensionally reticulated by light irradiation as disclosed in Japanese Patent No. 23139 is widely used. Methylolpropane acrylate, tetramethylolmethane tetraacrylate,
Pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate or 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, commercially available oligos Ester acrylate or the like is used.

Further, as the active energy ray-polymerizable compound, a urethane acrylate oligomer may be used in addition to the acrylate compound as described above.
In the present invention, the pressure-sensitive adhesive layer may contain an elastic polymer, a tackifier, a polymerization initiator, a polymerization inhibitor, a filler, an antiaging agent, a colorant and the like, if necessary. The resin film used for the pressure-sensitive adhesive sheet of the present invention is preferably flexible and stretches about 5 to 25% in one direction during dicing, and examples thereof include a resin film containing a plasticizer such as vinyl chloride and vinyl chloride. Vinylidene chloride copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-acrylic acid ester copolymers, polyvinylidene chloride, acetyl cellulose, polyesters and the like are used.

The plasticizer is not particularly limited, but for example, phthalic acid diester type, phosphoric acid ester type, fatty acid diester type, polyester type, epoxy type and chlorine type plasticizers are used. When the resin film contains a plasticizer, a barrier layer may be provided between the resin film and the adhesive layer in order to prevent the plasticizer from migrating to the adhesive layer.

[0024]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples and the comparative examples, "part" means "part by weight". The evaluations of Examples and Comparative Examples are as follows.

(1) Center line average roughness (Ra) The average roughness was measured as follows using a surface roughness measuring device (SE-3F) manufactured by Kosaka Laboratory Ltd. That is, a portion having a reference length L (2.5 mm) is extracted from the film sectional curve in the direction of the center line, and the center line of the extracted portion is taken as the x-axis, and the direction of longitudinal magnification is taken as the y-axis. When represented by x), the value given by the following formula is represented by [μm]. The center line average roughness is obtained by obtaining a sectional curve of 10 sample film surfaces,
The average value of the center line average roughness of the extracted portion obtained from these cross-section curves was shown. The tip radius of the stylus is 2μ
m, load 30 mmg, cut-off value 0.08 m
m.

[0026]

[Equation 1]

(2) Sliding property On a smooth glass plate, a resin film cut out to a width of 15 mm and a length of 150 mm is overlaid with a surface of the releasable base material of the same size, on which a release layer is not provided, Rubber plate and 1
A load of 00 g was placed, and the frictional force when the film was moved at a traveling speed of 20 mm / min was measured to calculate a dynamic friction coefficient, which was used as an index of slipperiness.

(3) Abrasion resistance The surface of the release-resistant substrate on which the release layer is not provided is rubbed with a nail,
The surface condition was observed. The evaluation criteria are as follows. ○: Almost no change. Δ: Slightly scratched. X: Strong scratches remain.

(4) Winding characteristics The appearance of the roll surface and end surface of the pressure-sensitive adhesive sheet when wound up in a roll was judged according to the following criteria. ○: The roll surface has almost no dents or wrinkles and the end faces are evenly aligned. Δ: The roll surface has some dents or the end faces are slightly uneven. ×: The roll surface has large dents. Or the chrysanthemum pattern on the end face

(5) Flatness The pressure-sensitive adhesive sheet rolled up in a roll was left at 40 ° C. for 48 hours, cut into a size of 300 mm × 1000 mm and placed on a horizontal plate, and the flatness was evaluated according to the following criteria. ○: Good flatness with almost no slack or dents. Δ: A slight slack or dent is observed. X: Large slack and dent.

Example 1 A coating solution having the following composition was applied to one side of a biaxially stretched polyethylene terephthalate film having a thickness of 38 μm by a gravure coater, dried and then irradiated with a high pressure mercury lamp having an energy of 120 W / cm for an irradiation distance of 150 mm. At about 15 seconds, a curing reaction was performed to form a roughened layer having a thickness of 2 μm.

[0032]

[Table 1] (Composition of coating liquid) Dipentaerythritol hexaacrylate 70 parts Bisphenol A type epoxy acrylate 20 parts Urethane acrylate 10 parts 1-Hydroxycyclohexyl phenyl ketone 5 parts Silica particles (Fuji Devison Chemical Co., Ltd. Cyloid 244) 8 parts Methyl ethyl ketone 50 Parts Toluene 50 parts Isopropyl alcohol 100 parts The coating solution having the following composition was applied to the opposite surface of the roughened layer of the film by a gravure coater and dried, and then 120 W
Irradiation distance of 150 using a high-pressure mercury lamp with energy of / cm
Irradiate for about 10 seconds in mm to carry out curing reaction and thickness 0.2
A μm release layer was formed.

[0033]

[Table 2] (Composition of coating liquid) UV-curable silicone resin (X-62-5040A, X-62-5040B manufactured by Shin-Etsu Chemical Co., Ltd. compounding ratio X-62-5040A: X-62-5040B = 100: 5) 105 parts Methyl ethyl ketone 1000 parts Toluene 1000 parts The following pressure-sensitive adhesive layer was formed on the release layer surface of the obtained releasable substrate so that the thickness was 10 μm, and 100 parts of polyvinyl chloride having an average degree of polymerization of 1300 was plasticized. A vinyl chloride resin film consisting of 35 parts of dioctyl phthalate as an agent and an appropriate amount of a stabilizer was laminated on the surface of the pressure-sensitive adhesive layer and bonded to form a roll-like pressure-sensitive adhesive sheet.

[0034]

[Table 3] (Adhesive layer composition) Acrylic adhesive (copolymer of n-butyl acrylate and acrylic acid) 100 parts Urethane acrylate oligomer (molecular weight 3000 to 10000) 100 parts Diisocyanate curing agent 25 parts p-Chloro Benzophenone 10 parts The release base material of the prepared pressure-sensitive adhesive sheet was peeled off, a 6-inch diameter silicon wafer was attached to the pressure-sensitive adhesive layer surface, and cut into 6 mm x 6 mm with a dicing saw. Next, ultraviolet rays (high pressure mercury lamp 80 W / cm,
After irradiating the irradiation distance of 100 mm) for 1 second, the adhesive sheet was stretched by 10% and picked up, the chips were smoothly processed without contacting each other, and chips did not crack or chip, resulting in dicing property. Was good.

Comparative Example 1 Example 1 is the same as Example 1 except that the roughening layer is not provided.
An adhesive sheet was prepared in the same manner as in. The obtained sheet had poor slipperiness between the releasable substrate surface and the resin film surface, when it was wound into a roll, a large dent occurred, and the flatness of the pressure-sensitive adhesive sheet was poor. Further, in the pickup step after the dicing step, chips were frequently cracked or chipped, resulting in poor dicing properties.

Example 2 Same as Example 1 except that the coating solution composition of the roughening layer in the releasable substrate was changed as follows and the thickness of the roughening layer was 4 μm. I made an adhesive sheet.

[0037]

(Table 4) (Composition of coating liquid) Dipentaerythritol hexaacrylate 70 parts Bisphenol A type epoxy acrylate 20 parts Urethane acrylate 10 parts 1-Hydroxycyclohexyl phenyl ketone 5 parts Silica particles (Syroid 72 manufactured by Fuji Devison Chemical Co., Ltd.) 10 parts Methyl ethyl ketone 40 Part Toluene 40 parts Isopropyl alcohol 80 parts

Example 3 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 2 except that the composition of the coating solution for the roughened layer on the releasable substrate was changed as follows and no ultraviolet irradiation was performed. did.

[0039]

(Table 5) Composition of coating liquid Polyester resin (Polyester TP-236 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 100 parts Silica particles (Cyroid 72 manufactured by Fuji Devison Chemical Co., Ltd.) 10 parts Methyl ethyl ketone 60 parts Toluene 60 parts Isopropyl alcohol 40 parts

Example 4 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 3 except that the composition of the coating liquid for the roughened layer in the releasable substrate was changed as follows.

[0041]

[Table 6] (Composition of coating liquid) Acrylic resin ("Takelac UA-906" manufactured by Takeda Chemical Industries, Ltd.) (solid content: 50 wt%) 100 parts Isocyanate ("Takenate D-110N" manufactured by Takeda Chemical Industries, Ltd.) (solid) Min 75 wt%) 10 parts Silica particles (Fuji Devison Chemical Co., Ltd. Syloid 72) 10 parts Methyl ethyl ketone 20 parts Toluene 20 parts Isopropyl alcohol 10 parts

Example 5 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the surface roughening treatment was performed by sandblasting instead of providing the surface roughening layer by coating in Example 1. The results obtained are summarized in Table 1.

[0043]

[Table 7]

[0044]

The pressure-sensitive adhesive sheet of the present invention is useful as a pressure-sensitive adhesive sheet for sticking semiconductor wafers, and has a high industrial value.

Claims (1)

[Claims] 1. A sheet obtained by laminating a releasable base material and a resin film via an adhesive layer, wherein the exposed surface of the releasable base material has a center line average roughness (Ra) of 0. .05-10μ
m is a pressure-sensitive adhesive sheet for adhering a semiconductor wafer.