JP2002060708A - Adhesive sheet for processing semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive sheet for processing a semiconductor wafer capable of exhibiting excellent expandability with slight impurities and excellent in chipping resistance characteristics when the semiconductor wafer is processed. SOLUTION: This adhesive sheet for processing the semiconductor wafer is characterized in that a film substrate is composed of a mixture of 30-70 pts.wt. of polypropylene with 70-30 pts.wt. of a block copolymer comprising (A) a polystyrene block represented by general formula (1) and (B) a vinylpolyisoprene block represented by general formula (2) in the adhesive sheet for processing the semiconductor wafer obtained by coating the top surface of a film substrate having transmissivity for ultraviolet rays and/or electron rays with an adhesive mass layer composed of a base polymer, a radiation polymerizable compound and a radiation polymerizing polymerization initiator.

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 processing a semiconductor wafer such as silicon or gallium arsenide, which is used for processing a semiconductor wafer, and is free from generation of impurities such as chlorine ions during processing. The present invention relates to an adhesive sheet for processing a wafer.

[0002]

2. Description of the Related Art Conventionally, as a sheet for processing a semiconductor wafer, which is used for attaching a semiconductor chip to a semiconductor wafer, performing dicing, expanding, and the like, and then picking up and mounting the semiconductor chip at the same time, the sheet is transparent to ultraviolet rays and / or electron beams. Using a pressure-sensitive adhesive sheet coated with a pressure-sensitive adhesive layer that undergoes a polymerization and curing reaction by ultraviolet rays and / or electron beams on a base material having an adhesive property, irradiating the pressure-sensitive adhesive layer with ultraviolet rays and / or electron beams after dicing, There is known a method of subjecting a semiconductor chip to a polymerization and curing reaction to reduce the adhesive force and pick up a semiconductor chip. In order to solve this problem, those using flexible polyvinyl chloride (PVC) as a base film have already been put into practical use.However, recent incineration is difficult due to environmental problems, and polyvinyl chloride resin is a chlorine-based resin. In addition, a stabilizer or a plasticizer made of a metal compound such as lead may migrate to the adhesive layer and cause the surface of the semiconductor wafer to be contaminated. In order to solve such a problem, use of a base material mainly composed of polyolefin has been studied. (For example, see JP-A-62-69)
640, JP-A-62-121781, JP-A-1-249877, JP-A-1-252684)

[0003] However, the above-mentioned patents have not sufficiently examined the stress and elongation characteristics required at the time of expansion.

Japanese Patent Application Laid-Open No. Hei 5-235150 discloses that stress / elongation at the time of expansion using an ethylene / acrylic acid copolymer, an ethylene / methacrylic acid copolymer or an ethylene / acrylic acid ester copolymer as a base material. Although the characteristics have been evaluated, the chipping characteristics such as chipping of the wafer during pickup have not been studied.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure-sensitive adhesive sheet for processing semiconductor wafers, which exhibits excellent expandability with little impurities in processing semiconductor wafers and has excellent chipping resistance.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to ultraviolet and / or ultraviolet radiation.
Or on a film substrate surface having transparency to electron beams,
A pressure-sensitive adhesive comprising a base polymer, a radiation-polymerizable compound and a radiation-polymerizable polymerization initiator is applied, and in a pressure-sensitive adhesive sheet for processing a semiconductor wafer formed by forming a pressure-sensitive adhesive layer, the film base is made of 30 to 70 parts by weight of polypropylene. , General formula
A semiconductor wafer comprising a mixture of a polystyrene block (A) represented by (1) and 70 to 30 parts by weight of a block copolymer comprising a vinyl polyisoprene block (B) represented by general formula (2). Adhesive sheet for processing,
Preferably, the film substrate has a tensile strength at 10% elongation of 10 to 125 kg / cm ² and an elongation of 18% after 20% elongation.
When the stress was released after holding for 0 seconds, the restoration rate of the substrate length was 7
5% or more of the pressure-sensitive adhesive sheet for processing a semiconductor wafer.

[0007]

Embedded image (In the formula (1), n is an integer of 2 or more)

[0008]

Embedded image (In the formula (2), n is an integer of 2 or more)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
As the substrate used in the present invention, 30 to 70 parts by weight,
Preferably 40 to 60 parts by weight of a polypropylene resin (P
P), 70 to 30 parts by weight, preferably 60 to 40 parts by weight, of a polystyrene block (A) represented by the general formula (1) and a vinyl polyisoprene block represented by the general formula (2)
It is a mixture with the block copolymer comprising (B). The tensile strength at 10% elongation of the film substrate used in the present invention is 10 to 125 kg / cm ² , and the tensile strength after 20% elongation is 18 kg / cm ^2.
When the stress was released after holding for 0 seconds, the restoration rate of the substrate length was 7
It is preferably at least 5%. If the 10% tensile strength is less than 10 kg / cm ² , handling becomes difficult due to being too soft, and chipping property is poor, and chipping of the wafer is present on the sheet after chip pickup. On the other hand, if it exceeds 125 kg / cm ² , it is too hard to extend and it becomes difficult to expand. If the elastic recovery is less than 75%,
There is a problem in that the amount of tarmi after expansion increases, and cannot be stored in a wafer box when the wafer is transferred to the next step, or the stored wafers come into contact with each other to cause contamination.

In the present invention, the pressure-sensitive adhesive layer provided on the substrate only needs to undergo a polymerization and curing reaction by ultraviolet rays and / or electron beams, and the pressure-sensitive adhesive layer includes a base polymer, a radiation-polymerizable compound, and a radiation-polymerizable compound. Contains a polymerization initiator and the like.

The pressure-sensitive adhesive of the present invention contains rosin resin, terpene resin, coumarone resin, phenol resin, styrene resin, aliphatic petroleum resin, aromatic petroleum resin, and aliphatic aromatic resin in order to increase cohesion. A tackifier such as a polymerized petroleum resin may be added. However, they desirably do not contain a plasticizer such as is added to vinyl chloride resins.

The radiation polymerizable compound mixture has a sufficient adhesive force to the semiconductor wafer before the curing reaction by ultraviolet rays and / or electron beams, and the adhesive force is reduced after the curing reaction, so that the semiconductor wafer (chip) Can be easily picked up, and 5000
It is preferable to mix a polyfunctional acrylate monomer having a molecular weight of at least 1,000 and a molecular weight of 1,000 or less, or two or more acrylate monomers.

By using a polyfunctional urethane acrylate having a molecular weight of 5,000 or more, a sufficient cohesive force can be imparted to the pressure-sensitive adhesive layer before the curing reaction. There is no danger of peeling and falling off. Moreover, the adhesive strength can be stabilized even when exposed for a long time under a fluorescent lamp, and the adhesive layer after the curing reaction can be given a sufficient cohesive force,
Chipping and chip scattering during dicing can be suppressed

On the other hand, if only a polyfunctional urethane acrylate having a molecular weight of 5,000 or more is used, the viscosity is so high that it is difficult to handle, and the adhesive strength after curing is not sufficiently reduced, making it difficult to pick up a chip. When a polyfunctional acrylate monomer having a molecular weight of 1,000 or less is used in combination to adjust this, the balance of adhesive properties becomes suitable.

The polyfunctional urethane acrylate in the radiation polymerizable compound used in the present invention is a compound synthesized from diisocyanate, polyol and hydroxy (meth) acrylate, and is preferably a urethane acrylate having two acryloyl groups. is there.

The polyfunctional acrylate monomer in the radiation polymerizable compound includes, for example, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate,
Examples thereof include dipentaerythritol monohydroxypentaacrylate and dipentaerythritol hexaacrylate.

In the present invention, the thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably about 5 to 35 μm. In the present invention, the pressure-sensitive adhesive layer is formed on the base material, and in order to produce a pressure-sensitive adhesive paper for processing a semiconductor wafer, the components constituting the pressure-sensitive adhesive layer are used as they are or in a solution with an appropriate organic solvent, and then coated. Alternatively, it can be obtained by applying the composition on a substrate by spraying or the like, and drying it by, for example, heat treatment at 80 to 100 ° C. for about 30 seconds to 10 minutes.

A known method can be used to use the pressure-sensitive adhesive sheet for processing a semiconductor wafer of the present invention. For example, after the pressure-sensitive adhesive sheet for processing a semiconductor wafer is attached to a semiconductor wafer and fixed, the semiconductor wafer is rotated with a rotary round blade. Is cut into element pieces (hereinafter referred to as chips). Thereafter, ultraviolet rays and / or an electron beam are irradiated from the substrate side of the pressure-sensitive adhesive sheet for processing,
Then, using a special jig, the wafer processing pressure-sensitive adhesive sheet is radially expanded, and the distance between the chips is expanded at a constant interval. Just mount it.

[0019]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. << Example 1 >> 60 parts by weight of polypropylene and Hybler 4
Cleartec CT-H807 (manufactured by Kuraray) consisting of 0 parts by weight was formed into a sheet having a thickness of 90 μm by an extruder. 50 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 37 parts by weight of vinyl acetate, 2-methyl methacrylate
For 100 parts by weight of a copolymer having a weight average molecular weight of 500,000 obtained by copolymerizing 3 parts by weight of hydroxyethyl, a bifunctional urethane acrylate having a molecular weight of 11,000 and a pentafunctional acrylate monomer having a molecular weight of 500 are used as radiation polymerizable compounds. 35 parts by weight, 65 parts by weight, 8.3 parts by weight of 2,2-dimethoxy-2-phenylacetophenone as a photopolymerization initiator, and 8.3 parts by weight of a polyisocyanate-based crosslinking agent with respect to 100 parts by weight of a radioactive polymer compound. A resin solution for forming an adhesive layer, in which 6 parts by weight are blended with respect to 100 parts by weight of the united product, is peeled off to a thickness of 38.
10 μm thickness after drying on a μm polyester film
And dried at 80 ° C. for 5 minutes. Thereafter, the base sheet was laminated to prepare a pressure-sensitive adhesive sheet for semiconductor processing. After the obtained pressure-sensitive adhesive sheet for semiconductor processing was matured at room temperature for 7 days or more, each item was evaluated. Table 1 shows the results.

Example 2 The same as Example 1 except that the base material of the sheet used in Example 1 was Cleartech CT-H817 (manufactured by Kuraray) consisting of 40 parts by weight of polypropylene and 60 parts by weight of Hibler. A sample was prepared by the method described in the above, and the same items as in Example 1 were tested. Table 1 shows the results. Comparative Example 1 A sample was prepared in the same manner as in Example 1 except that the base material of the sheet used in Example 1 was a blend of 20 parts by weight of polypropylene and 80 parts by weight of Hybler. Similar items were tested. Table 1 shows the results.
Shown in << Comparative Example 2 >> A sample was prepared in the same manner as in Example 1, except that the base material of the sheet used in Example 1 was a blend of 80 parts by weight of polypropylene and 20 parts by weight of Hybler. Similar items were tested. Table 1 shows the results.
Shown in

[0021]

[Table 1]

The following evaluation methods were used to evaluate the examples and comparative examples. (1) Tensile test According to JIS C 2813. (2) Elastic recovery rate Evaluated after stretching for 20% and holding for 3 minutes. (3) Expandability Using an expander (manufactured by Hugle), expansion was performed at a stroke of 20 mm for 10 minutes and evaluated. Evaluation criteria ：: No tear in the sheet during expansion ×: A tear in the sheet is observed when expanded Evaluation was made by measuring the amount of tarmi after time. Evaluation criteria ○: 10 mm or less △: 10 to 15 mm ×: 15 mm or more (5) Chipping characteristics A semiconductor wafer is held and fixed on an adhesive sheet, and the number of spindle rotations is 3 using a dicing saw (DISCO DAD-2H6M).
000rpm, cutting speed 120mm /
min. After the chip was cut to the chip size, the chip was peeled from the pressure-sensitive adhesive sheet, and the state of chipping on the back surface was evaluated by observing the chip with a stereoscopic microscope. Evaluation criteria ○: Chip chip width of 30 mm or less at maximum △: Chip chip width of 30 to 50 mm at maximum ×: Chip chip width of 50 mm or more at maximum

[0023]

According to the present invention, a pressure-sensitive adhesive sheet for processing semiconductor wafers which exhibits excellent expandability when processing semiconductor wafers and has excellent chipping resistance.

Continued on the front page F term (reference) 4J002 BB12W BP01X GJ00 GQ05 4J004 AA02 AA10 AA14 AB06 CA03 CA04 FA05 FA08

Claims (2)

[Claims] 1. An adhesive comprising a base polymer, a radiation-polymerizable compound and a radiation-polymerizable polymerization initiator is applied on a surface of a film substrate having transparency to ultraviolet rays and / or electron beams, and an adhesive layer is formed. In the formed pressure-sensitive adhesive sheet for processing a semiconductor wafer, the film substrate is made of polypropylene 3
0 to 70 parts by weight, and a block copolymer 70 to 70 composed of a polystyrene block (A) represented by the general formula (1) and a vinyl polyisoprene block (B) represented by the general formula (2).
An adhesive sheet for processing a semiconductor wafer, comprising a mixture with 30 parts by weight. Embedded image (In the formula (1), n is an integer of 2 or more.) (In the formula (2), n is an integer of 2 or more) 2. The tensile strength at 10% elongation of the film substrate is 10 to 125 kg / cm ² , and the restoration rate of the substrate length when the stress is released after holding for 180 seconds after the 20% elongation is reduced. The pressure-sensitive adhesive sheet for processing a semiconductor wafer according to claim 1, which is 75% or more.