JPH10242086A - Semiconductor wafer holding sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent or greatly suppress breaks of cut faces by dicing to greatly improve the chip yield, by attaching an adhesive layer having a storage elastic modulus in specified range at specified temps. SOLUTION: An adhesive layer having a storage elastic modulus of 3×10<6> -1×10<10> dyn/cm<2> at 0-10 deg.C is attached to a support sheet to form a semiconductor wafer hold sheet. The storage elastic modulus is measured in a range of 0-10 at a frequency of 1Hz by feeding the adhesive layer of 0.5mm thick to a dynamic viscoelasticity meter (viscoelastic spectrometer), the adhesive layer is made of a rubber adhesive made of natural or synthetic rubber or acrylic adhesive, and the support sheet of the adhesive layer is a polyethylene, polyester, polycarbonate or other plastic sheet of 10-300μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer holding sheet suitable for fixing and holding a wafer when dicing a semiconductor wafer into chips.

[0002]

2. Description of the Related Art A semiconductor wafer on which a predetermined circuit pattern such as an IC is formed is polished on the back side to, for example, 0.1 to 0.2 mm.
After being thinned to a thickness of about 4 mm, dicing is performed to a predetermined chip size through a rotary blade such as a method of rotating a blade of metal particles at a high speed. The wafer is fixedly held by a holding sheet provided with a part of the holding sheet thickness (5 to 20).
Generally, a method of cutting the wafer down to about μm) to completely cut the wafer is employed.

However, in the conventional holding sheet, there is a problem that a chip of several μm to several mm is formed on a cut surface of a chip formed by shock or vibration during dicing. Such chipping is greater in compound semiconductors such as gallium arsenide.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor wafer holding sheet in which a cut surface is less likely to be chipped when dicing a semiconductor wafer.

[0005]

According to the present invention, there is provided a support sheet having an adhesive layer having a storage elastic modulus in a range of 0 to 10 ° C. in a range of 3 × 10 ⁶ to 1 × 10 ¹⁰ dyn / cm ^2. A feature of the present invention is to provide a semiconductor wafer holding sheet.

[0006]

According to the present invention, by fixing and holding the semiconductor wafer through the adhesive layer having the above storage elastic modulus, chipping of the cut surface during dicing can be prevented or largely suppressed, and the chip yield can be greatly improved. it can. That is, it is considered that chipping of the cut surface is based on a decrease in cutting ability due to clogging of the rotary blade and severe vibration of the chip, but clogging of the rotary blade by setting the storage elastic modulus of the adhesive layer to the above range. And vibration of the chip can be suppressed.

Therefore, it is considered from the above that the storage elastic modulus of the pressure-sensitive adhesive layer at a relatively low temperature of 0 to 10 ° C. is correlated with a high-speed deformation behavior region during dicing. The above storage elastic modulus was measured by supplying an adhesive layer having a thickness of 0.5 mm and a diameter of 8 mm to a dynamic viscoelasticity measuring machine (manufactured by Rheometric Co., viscoelastic spectrometer) at 0 to 10 ° C. at a frequency of 1 Hz.
Based on the measured value (storage modulus).

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The semiconductor wafer holding sheet of the present invention has a storage elastic modulus of 3 × 10 ⁶ in the range of 0 to 10 ° C.
An adhesive layer in the range of ^１1 × 10 ¹⁰ dyn / cm ² is attached to the support sheet, and the semiconductor wafer is adhered and held through the adhesive layer.

The adhesive layer may be any one that satisfies the above storage modulus. Therefore, for forming the adhesive layer, for example, a rubber-based adhesive using natural rubber or synthetic rubber, poly (meth)
Appropriate adhesives such as acrylic adhesives using copolymers of alkyl acrylates or alkyl (meth) acrylates with other monomers, and other polyurethane adhesives, polyester adhesives, and polycarbonate adhesives An agent may be used, and may be one that is cured by energy rays such as ultraviolet rays.

Incidentally, the preparation of the pressure-sensitive adhesive satisfying the above-mentioned storage elastic modulus uses a high polymer having the above-mentioned high storage elastic modulus as a main polymer serving as a skeleton of the pressure-sensitive adhesive layer and has, for example, two or more carbon-carbon double bonds. A method of blending a low-molecular compound, a (photo) polymerization initiator, a plasticizer, a tackifier, a relatively low-molecular-weight additive that may be used in a pressure-sensitive adhesive such as a vulcanizing agent, or a pressure-sensitive adhesive layer, It can be carried out by a method of increasing the crosslink density of the main polymer or oligomer serving as the skeleton.

The crosslinking density of the pressure-sensitive adhesive layer can be controlled, for example, by appropriately controlling a polyfunctional isocyanate compound, an epoxy compound, a melamine compound, a metal salt compound, a metal chelate compound, an amino resin compound or a peroxide. An appropriate method such as a method of performing a cross-linking treatment via a cross-linking agent, a method of mixing a low-molecular compound having two or more carbon-carbon double bonds, and performing a cross-linking treatment by irradiation with energy rays or the like can be used.

The pressure-sensitive adhesive layer preferably has a higher storage elastic modulus in the range of 0 to 10 ° C. in order to prevent chipping of the chip cut surface.
It is preferable that the storage elastic modulus at a temperature of not lower than ℃ is lower. The pressure-sensitive adhesive layer, which is preferable from the viewpoint of preventing chipping of chip cutting surface and compatibility with holding and holding the wafer, has a storage elastic modulus of 4 × 10 ⁶ dyn / cm ² or more in the range of 0 to 10 ° C., and particularly 1 × 10 ^7. ~ 1 × 10
¹⁰ dyn / cm ² , storage elastic modulus at 20 ° C. or more is 3 × 10 ⁶ d
yn / cm ² or less, especially 1 × 10 ^{6 to} 3 × 10 ⁵ dyn / cm ² .

The holding sheet of the present invention can be formed, for example, according to a method of forming a pressure-sensitive adhesive tape such as a method of applying a pressure-sensitive adhesive to a support sheet and heat-treating the same. Although the thickness of the adhesive layer may be determined as appropriate, it is more preferable that the thickness of the adhesive layer be 1 in order to prevent chipping of the cut surface of the chip and to keep the wafer fixed and compatible.
A thickness of の 50 μm, preferably 2-30 μm, especially 5-15 μm is preferred.

The adhesive force of the adhesive layer at room temperature (90 ° peel value, 90 ° peel value,
2000g / 20mm based on a peeling speed of 300mm / min)
Hereinafter, especially 0.1 to 1000 g / 20 mm, particularly 1 to 800 g
g / 20 mm is preferred.

As the support sheet for supporting the adhesive layer, an appropriate one may be used. In general, for example, polypropylene, polyester, polycarbonate, polyethylene, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / ethyl acrylate copolymer It is made of a suitable plastic such as propylene copolymer or polyvinyl chloride and has a thickness of 1
A sheet of 0 to 300 μm or the like is used.

Further, as the support sheet, a resin sheet or the like to which heat shrinkage is imparted by a stretching treatment or the like can be used. According to the heat-shrinkable support sheet, the support sheet can be thermally contracted after dicing, so that the bonding surface with the chip can be reduced, and the chip can be easily collected. In order to facilitate chip collection, for example, as an adhesive layer having a composition containing a curing agent, a foaming agent, and the like, the adhesive force is increased by a method of performing a curing treatment via an energy beam or the like after dicing or a method of performing a foaming treatment via a heat treatment or the like. It can also be achieved by a method or the like that can be reduced.

The adhesive layer of the holding sheet is preferably covered and protected by a separator, a release liner, or the like until the adhesive layer adheres to the semiconductor wafer from the viewpoint of preventing contamination during storage and distribution. The separator and the like can be obtained by a method in which a flexible thin sheet made of paper, a plastic film, or the like is provided with a surface coat of a release agent as necessary.

The holding sheet of the present invention can be preferably used for fixing and holding the semiconductor wafer in various processes for processing the semiconductor wafer such as a dicing process and a back surface polishing process. In this case, the holding sheet can be used in an appropriate form such as a shape corresponding to the planar shape of the wafer or a continuous sheet.

Further, the holding sheet may have an antistatic function for the purpose of preventing static electricity from being generated at the time of bonding or peeling of the sheet, and the circuit being broken by the electrification of the semiconductor wafer. The provision of antistatic ability is achieved by adding an antistatic agent or a conductive agent to the support sheet or the adhesive layer,
An appropriate method such as attaching a conductive layer made of a charge transfer complex, a metal film, or the like to the support sheet can be performed, and a method that does not easily generate impurity ions that may deteriorate the semiconductor wafer is preferable.

[0020]

【Example】

Example 1 An acrylic copolymer having a number average molecular weight of 300,000 obtained by copolymerizing 70 parts of methyl acrylate (parts by weight, the same applies hereinafter), 30 parts of butyl acrylate, and 5 parts of acrylic acid in a conventional manner in toluene. Was added to a solution containing 70 parts of a urethane oligomer and 5 parts of a polyfunctional isocyanate compound per 100 parts of the acrylic copolymer to prepare an acrylic pressure-sensitive adhesive, which was used to prepare a 70 μm thick polyvinyl chloride film. Coated on one side and heated at 130 ° C for 3 minutes, thickness 15μm
A holding sheet having a pressure-sensitive adhesive layer was obtained.

Example 2 A solution containing a polyester having a number average molecular weight of 580,000 obtained by copolymerizing 80 parts of polycarbonate diol, 20 parts of adipic acid and 0.5 part of dibutyltin oxide in toluene was mixed with 100 parts of the polyester. A holding sheet was obtained in the same manner as in Example 1 except that a polyester-based pressure-sensitive adhesive prepared by adding 5 parts of a polyfunctional isocyanate compound was used.

Example 3 A solution containing an acrylic copolymer having a number average molecular weight of 500,000 obtained by copolymerizing 90 parts of butyl acrylate, 5 parts of acrylonitrile, and 5 parts of acrylic acid in toluene was added to the acrylic copolymer. An acrylic pressure-sensitive adhesive was prepared by adding 50 parts of a polyfunctional acrylic monomer, 5 parts of a polyfunctional isocyanate compound, and 5 parts of a photopolymerization initiator per 100 parts of the copolymer, and then preparing an acrylic pressure-sensitive adhesive having a thickness of 70 μm. After coating on one side of the film and heating at 130 ° C. for 3 minutes to form an adhesive layer having a thickness of 15 μm, it was left under a high-pressure mercury lamp of 80 W / cm ² for 60 seconds to be subjected to ultraviolet treatment, and the holding sheet was treated. Obtained.

Example 4 A solution containing an acrylic copolymer having a number average molecular weight of 500,000 obtained by copolymerizing 90 parts of butyl acrylate, 5 parts of acrylonitrile, and 5 parts of acrylic acid in toluene was added to the acrylic copolymer. An acrylic pressure-sensitive adhesive was prepared by adding 10 parts of a urethane oligomer, 5 parts of a polyfunctional isocyanate compound, and 5 parts of a photopolymerization initiator per 100 parts of a copolymer, and then preparing one side of a 70 μm-thick polyvinyl chloride film. And heated at 130 ° C. for 3 minutes to form an adhesive layer having a thickness of 15 μm, which was then dried under a high pressure mercury lamp of 80 W / cm ² for 10 minutes.
After standing for 2 seconds, ultraviolet treatment was performed to obtain a holding sheet.

Comparative Example 1 A solution containing an acrylic copolymer having a number average molecular weight of 500,000 obtained by copolymerizing 90 parts of butyl acrylate, 5 parts of acrylonitrile and 5 parts of acrylic acid in toluene was added to the acrylic copolymer. A holding sheet was obtained in the same manner as in Example 1 except that an acrylic pressure-sensitive adhesive prepared by adding 100 parts of a urethane oligomer and 5 parts of a polyfunctional isocyanate compound per 100 parts of a copolymer was used.

COMPARATIVE EXAMPLE 2 A solution containing an acrylic copolymer having a number average molecular weight of 300,000 obtained by copolymerizing 90 parts of butyl acrylate and 10 parts of acrylic acid in toluene was added to the acrylic copolymer 1
A holding sheet was obtained according to Example 1, except that an acrylic pressure-sensitive adhesive prepared by adding 30 parts of a plasticizer and 5 parts of a polyfunctional isocyanate compound per 00 parts was used.

Evaluation Test A semiconductor wafer having a diameter of 4 inches, on which a circuit pattern was formed, was polished on the back surface to a thickness of 0.25 mm, and was adhered and fixed with the holding sheets obtained in Examples and Comparative Examples, and then diced. Using a device (manufactured by Disco, 2S / 8), the dicing speed is 100 mm / sec, the number of rotations of a dicing blade (manufactured by Disco, 2050HFDD) is 40,000 rpm, and the cutting depth of the holding sheet is 30 μm. 3mm
Cut into chips.

Next, the cut surface of the obtained chip was observed,
A chip having a chip or crack of 75 μm or more in the depth direction was determined to be defective, and the yield of a non-defective article was examined. The results are shown in the following table. The table also shows the storage elastic modulus of the adhesive layer at 0 ° C. and 10 ° C.

Claims (2)

[Claims] 1. A semiconductor wafer comprising an adhesive layer having a storage elastic modulus in a range of 0 to 10 ° C. in a range of 3 × 10 ⁶ to 1 × 10 ¹⁰ dyn / cm ² attached to a support sheet. Holding sheet. 2. The method according to claim 1, wherein the thickness of the adhesive layer is 1 to 1.
A semiconductor wafer holding sheet having a thickness of 50 μm.