JPH05175331A - Adhesive sheet for dicing of semiconductor wafer - Google Patents

Abstract

PURPOSE:To provide an adhesive sheet for preventing circuits formed on the surface of a wafer from damage due to static electricity caused by cutting water or cleaning water jetted under high pressure when the semiconductor wafer is diced or cleaned. CONSTITUTION:An adhesive sheet for a semiconductor wafer includes an adhesive layer on a surface substrate made of a layer consisting of at least internal plasticized polyvinyl chloride film with a low electrical resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive sheet for wafer dicing, which is used when a semiconductor wafer such as silicon or gallium arsenide is diced into chips, and is particularly used for high-pressure cutting during dicing or cleaning. The present invention relates to a pressure-sensitive adhesive sheet for semiconductor wafer dicing, which can prevent the circuit on the surface of a wafer chip from being destroyed or altered by static electricity generated by water or cleaning water.

[0002]

2. Description of the Related Art In order to separate a semiconductor wafer such as silicon or gallium arsenide into wafer chips, the semiconductor wafer is previously attached and fixed to an adhesive sheet, and then dicing, washing, drying, expanding, picking up and mounting steps are performed. However, during the dicing, cleaning and drying steps, the wafer chips are detached and scattered, and in the pickup step, on the contrary, the wafer chips are not peeled off from the adhesive sheet. In addition, pickup has become more difficult as the degree of integration increases and the area of wafer chips increases in recent years.

In order to solve these problems, UV-curable pressure-sensitive adhesive sheets have come to be used, but these pressure-sensitive adhesive sheets have a high electric resistance value, and cutting water and cleaning water used during dicing and cleaning. There is a problem that the static electricity generated by this cannot be removed. On the other hand, a method of adding an additive that suppresses the generation of static electricity to cutting water or cleaning water, and attaching a static eliminator to a dicing device to remove the generated static electricity is also used, but Not enough effect, or
The circuit on the surface of the wafer chip is destroyed or altered to adversely affect the wafer chip.

[0004]

The conventional UV-curable pressure-sensitive adhesive sheet has a high electric resistance value of the polyolefin or its composite film used as the surface base material, and also has a high electrical resistance of the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer. Acrylic adhesives and UV-curable compounds, which are the main components, also have high electric resistance values. Therefore, when cutting water for dicing and cleaning water for cleaning are jetted under high pressure, static electricity is generated on a semiconductor wafer such as silicon or gallium arsenide, which makes it difficult to remove it. There is a problem of destroying or altering the quality. In order to solve such a problem, the present invention provides an ultraviolet-curable pressure-sensitive adhesive sheet characterized by enabling quick removal of static electricity generated by cutting water during dicing or cleaning water during cleaning. To do.

[0005]

In the present invention, in order to solve the above problems, as a result of intensive studies, the inventors have found that the adhesive sheet as described below is effective and completed the present invention. That is, the pressure-sensitive adhesive sheet of the present invention is a semiconductor wafer in which a surface substrate to which ultraviolet rays are transmitted is a layer made of an internally plasticized polyvinyl chloride film having at least a low electric resistance value, and a pressure-sensitive adhesive is formed on the substrate surface. It is an adhesive sheet for dicing. Furthermore, the present invention is a pressure-sensitive adhesive sheet for semiconductor wafer dicing, which is formed of a material having a low specific electric resistance value as the pressure-sensitive adhesive.

Up to now, there have been many descriptions about the UV-curable pressure-sensitive adhesive sheet in which the UV-curable pressure-sensitive adhesive layer is formed by using the polyolefin film, polyvinyl chloride and its copolymer film, but like the present invention, the electric resistance UV curable with low electric resistance by using a surface base material with low value and compounding UV curable adhesive, UV polymerizable compound, sensitizer, and if necessary tackifier, plasticizer, etc. on the surface. There is no description of a pressure-sensitive adhesive sheet provided with a mold pressure-sensitive adhesive layer and capable of removing static electricity generated during dicing or cleaning.

Here, the internally plasticized polyvinyl chloride film used as the surface substrate means polyvinyl chloride and dibutyl phthalate (DBP) or dioctyl phthalate (DO).
P) is a film obtained from polyvinyl chloride that has been plasticized by copolymerizing vinyl chloride with another monomer without adding a plasticizer such as P), and has a low electric resistance value. , For example, a copolymer obtained by copolymerizing a monomer which can be copolymerized with vinyl chloride, particularly vinyl chloride-vinyl acetate, vinyl chloride-higher alkyl vinyl ether, vinyl chloride-ethylene vinyl acetate, vinyl chloride-acrylate, chloride Examples thereof include films of copolymers such as vinyl-ethylene and vinyl chloride-propylene. This internally plasticized polyvinyl chloride film can be blended with other compounding agents known per se as long as the electrical resistance value can be maintained at a low value.

The surface substrate in the present invention is composed of the above-mentioned internally plasticized polyvinyl chloride film, but is not limited to the film, and is composed of a layer of the film layer and another compound having a low electric resistance value. Other layers may be formed, for example, as long as they do not impair the ultraviolet ray transmittance and electric characteristics intended by the present invention.

The thickness of the internally plasticized polyvinyl chloride film is 30 to 200 microns, preferably 6
0 to 120 microns is good. If the thickness is less than 30 μm, the rotary blade will cut through the film layer during polydicing. On the other hand, if it exceeds 200 microns, it will not be sufficiently expanded at the time of expanding and picking up will be difficult.

Next, as the UV-curable pressure-sensitive adhesive, a resin obtained by graft-polymerizing a vinyl chloride monomer onto an ethylene-vinyl acetate copolymer is blended with a UV-polymerizable prepolymer and / or a UV-polymerizable monomer. It contains a sensitizer to improve the ultraviolet curing reaction. In addition, a tackifier and a plasticizer may be used to adjust the adhesive force before and after irradiation with ultraviolet rays, if necessary. The resin obtained by graft-polymerizing a vinyl chloride monomer to the ethylene-vinyl acetate copolymer referred to herein is an ethylene-vinyl acetate copolymer containing 50 to 40 parts by weight of ethylene and 70 to 40 parts by weight of vinyl acetate. An example is one in which vinyl chloride monomer is graft-polymerized at a ratio of 50 to 25 parts by weight with respect to 75 parts by weight.

Next, as the UV-polymerizable prepolymer, there are polyester monoacrylate, polyester diacrylate, polyester triacrylate, epoxy acrylate, polyurethane acrylate, polyether acrylate, melamine acrylate, alkyd acrylate, silicon acrylate, etc. Is isodecyl acrylate, stearyl acrylate, lauryl acrylate, 1,3-butanediol diacrylate, 1,4 butanediol diacrylate, polyethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, etc. Can be mentioned.

The UV-polymerizable monomers include monofunctional monomers such as 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and tetrahydrofurfuryl acrylate, and the bifunctional monomers include: There are dicyclobontanyl diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, polyethylene glycol diacrylate and the like.
Examples of trifunctional or higher functional monomers include trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, and dipentaerythritol hexaacrylate.

These UV-polymerizable prepolymers and / or
Alternatively, the amount of the UV-polymerizable monomer is 1 to 500 parts by weight based on 100 parts by weight of a resin obtained by graft-polymerizing a vinyl chloride monomer on an ethylene-vinyl acetate copolymer,
It is preferably 50 to 150 parts by weight. When it exceeds this range, when the adhesive layer is irradiated with ultraviolet rays, the adhesive layer becomes hard and brittle, and expansion becomes difficult.

As the sensitizer, benzoin, benzoin ethyl ether, benzoin isopropyl ether, diphenyl sulfide, anthracene, benzophenone, α-chloroanthraquinone, diphenyl disulfide, diacetyl, hexachlorobutadiene, pentachlorobutadiene, octachloro. Butene, 1-chloromethylnaphthalene and the like can be mentioned, and they are mixed in an amount of 0.1 to 5% by weight, preferably 0.1 to 3% by weight.

Further, as the tackifier used if necessary, a resin obtained by graft-polymerizing an ethylene-vinyl acetate copolymer with a vinyl chloride monomer, or a resin having compatibility with a plasticizer is known. Any of the above may be used, but specifically, glycerin ester rosin,
One or more of rosin and modified rosin derivatives such as pentaerythritol rosin, terpene modified products such as terpene phenol, and phenolic resins such as alkylphenol and modified phenol are used. The compounding amount thereof is a resin 100 obtained by graft-polymerizing an ethylene-vinyl acetate copolymer with a vinyl chloride monomer.
1 to 100 parts by weight, preferably 5 to 30 parts by weight, relative to parts by weight. If the tackifier is 100 parts by weight or more, the adhesive force will not be appropriately reduced even if the pressure-sensitive adhesive layer is irradiated with ultraviolet rays.

As the plasticizer, those generally used as a plasticizer for polyvinyl chloride can be used. Specifically, phthalate ester compounds such as 2-ethylhexyl phthalate and butyl phthalate, and adipine are used. 2-ethylhexyl acid, aliphatic dibasic acid ester such as butyl adipate, inorganic acid ester such as tributyl phosphate, triphenyl phosphate, tricresyl phosphate, polyester,
Epoxy type, other 1 or 2 such as chlorinated paraffin
More than one species is used. The compounding amount is 1 to 50 with respect to 100 parts by weight of a resin obtained by graft-polymerizing a vinyl chloride monomer on an ethylene-vinyl acetate copolymer.
Parts by weight, preferably 5 to 20 parts by weight. When the amount of the plasticizer is 50 parts by weight or more, it is compatible with the UV-polymerizable compound. Therefore, even if the pressure-sensitive adhesive layer is irradiated with ultraviolet rays, the pressure-sensitive adhesive layer is not cured and the adhesive strength is difficult to reduce. It is to transfer and contaminate the surface.

The pressure-sensitive adhesive sheet for wafer dicing according to the present invention comprises a layer of the above-mentioned UV-curable pressure-sensitive adhesive formed on a surface substrate having at least the above-mentioned internal plasticized polyvinyl chloride film as one layer by a known method. It can be manufactured by forming it using. For example, an ultraviolet-polymerizable prepolymer and / or an ultraviolet-polymerizable monomer and a sensitizer are added to a resin obtained by graft-polymerizing an ethylene-vinyl acetate copolymer with a vinyl chloride monomer, and if necessary, a tackifier, a plasticizer The mixture containing the agent is made into a solution with a known organic solvent, and applied to the surface base material by a conventional method.
An adhesive layer is formed by drying to obtain an adhesive sheet for semiconductor wafer dicing. Preferred organic solvents include toluene, ethyl acetate, tetrahydrofuran, methyl ethyl ketone and the like. When workability is difficult due to the softening or swelling of the film due to the diluent or heat during drying, an adhesive is applied on the release sheet and dried, followed by internal plasticization. You may stick a polyvinyl chloride film. The thickness of this UV-curable pressure-sensitive adhesive layer is preferably 3 to 50 μm.

An example of the method of using the thus obtained adhesive sheet for semiconductor wafer dicing will be described. First,
The semiconductor wafer is adhesively fixed to the adhesive surface of the adhesive sheet for wafer dicing. In this case, the ultraviolet curable pressure sensitive adhesive of the present invention can fix a semiconductor wafer with an adhesive force of 120 to 1000 g / 25 mm.

Next, a dicing saw is used to completely cut the elements formed on the surface of the semiconductor wafer in a grid pattern vertically and horizontally. At this time, since frictional heat is generated when the rotary blade of the dicing saw cuts the wafer, cutting water is ejected to cool or clean the wafer chip and the rotary blade. Further, in the next cleaning step, high-pressure ultrapure water is jetted to clean dirt and chips generated when the wafer is cut. At this time, static electricity is easily generated due to friction between the wafer surface and ultrapure water, but static electricity can be quickly eliminated by using the adhesive sheet for wafer dicing of the present invention.

The present invention will be described below based on examples, but the present invention is not limited to these examples.

Example 1 Resin obtained by graft-polymerizing a vinyl chloride monomer to an ethylene-vinyl acetate copolymer Sumigraft (Sumitomo Chemical) ^{* 1} 100 parts by weight UV-curable compound Polyester oligomer (Dainichiseika) 100 parts by weight Sensitizer benzophenone 3 parts by weight Tackifier Ester gum 20 parts by weight Plasticizer Dioctyl phthalate 10 parts by weight * 1 Resin obtained by graft-polymerizing vinyl chloride monomer on ethylene-vinyl acetate copolymer is ethylene-vinyl acetate containing 55% by weight of ethylene. It is a graft polymer of 50% by weight of a copolymer and 50% by weight of a vinyl chloride monomer.

An ultraviolet curable adhesive having the above composition was dissolved in a 1: 1 mixed solvent of toluene and ethyl acetate to prepare an adhesive solution, which was coated with a silicone resin and had a thickness of 50 μm. The film is applied onto the film using an applicator so that the thickness after drying is 10 μm, and dried at 100 ° C. for 2 minutes. After drying, the above-mentioned pressure-sensitive adhesive is attached to the surface of an internally plasticized polyvinyl chloride film (thickness 100 μm).

Using the pressure-sensitive adhesive sheet for wafer dicing thus obtained, the volume resistance value and surface resistance value of the pressure-sensitive adhesive coated surface were measured by a super insulation resistance meter, and the results are shown in the test result table.

[0023]

Comparative Example 1 Acrylic adhesive 100 parts by weight UV curable compound Polyester oligomer (Dainichiseika) 100 parts by weight Crosslinking agent (Coronate L) 20 parts by weight Sensitizer (benzophenone) 3 parts by weight The curable pressure sensitive adhesive was prepared in the same manner as in Example 1 except that the organic solvent was used to prepare a pressure sensitive adhesive solution, which was coated, dried, and dried.
It was stuck to 0 micron in the same manner as in Example 1. Using the pressure-sensitive adhesive sheet for wafer dicing thus obtained, the same test as in Example 1 was conducted, and the results are shown in the test result table.

[0024]

【Test results】 Note. The surface resistance value is the value measured on the adhesive surface of the adhesive tape. As is clear from the above results, in Example 1, both the volume resistance value and the surface resistance value were considerably lower than those in Comparative Example 1, and it is suitable for use as the adhesive sheet for semiconductor wafer dicing intended by the present invention. Will be understood.

[0025]

When the pressure-sensitive adhesive sheet for wafer dicing according to the present invention is used, even when static electricity is generated in cutting water or cleaning water jetted at high pressure during dicing of a semiconductor wafer or during a cleaning process, the pressure-sensitive adhesive layer and surface substrate Since the material film layer has a low volume resistance value and a low surface resistance value, it is possible to prevent the electric charge from being immediately removed and destroying or degrading the circuit on the wafer surface, which is an excellent effect.

Claims (3)

[Claims] 1. A pressure-sensitive adhesive sheet for semiconductor wafer dicing, comprising a surface substrate that transmits ultraviolet rays and a pressure-sensitive adhesive, wherein the surface substrate is a layer made of at least an internally plasticized polyvinyl chloride film having a low electric resistance value. An adhesive sheet for semiconductor wafer dicing, which is characterized in that 2. The adhesive comprises a resin prepared by graft-polymerizing an ethylene-vinyl acetate copolymer with a vinyl chloride monomer, an ultraviolet-reactive prepolymer and / or an ultraviolet-reactive monomer, and a sensitizer. The pressure-sensitive adhesive sheet for semiconductor wafer dicing according to claim 1, wherein the pressure-sensitive adhesive sheet is an ultraviolet-curable pressure-sensitive adhesive layer whose adhesive force is reduced by irradiation with ultraviolet rays. 3. The pressure-sensitive adhesive sheet for semiconductor wafer dicing according to claim 2, wherein the pressure-sensitive adhesive further contains a tackifier or a plasticizer.