Wafer processing films

Details Wafer processing films Wafer processing films

1991-04-01

1993-02-02

Buffalow, Edith

Stock material or miscellaneous articles

Structurally defined web or sheet

Including components having same physical characteristic in...

428 40, 428343, 428522, B32B 702

Patent

active

051836998

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

1. Technical Field
The present invention relates to a wafer processing film which is used when grinding wafers such as silicon wafers so as to prevent their breakage.
2. Background Art
Semiconductor integrated circuits (ICs) are generally fabricated by slicing a semiconductor material such as a high-purity silicon single crystal into a wafer, forming integrated circuits therein through etching or the like, and then dicing the resultant wafer into chips.
In a step in which the back side of an IC wafer is ground and polished, it is a routine practice to affix a wafer processing film, which has an adhesive layer, onto the surface of the wafer so that breakage to the wafer can be prevented and the grinding work can be facilitated.
A wafer processing film is generally produced by coating an adhesive on one surface of a base film and then drying the same to form an adhesive layer on the base film. A synthetic resin film called a "separator" is applied over the adhesive layer to protect the adhesive layer during storage or transportation of the wafer processing film, whereby the wafer processing film has a structure such that the adhesive layer is sandwiched between the base film and the separator. Upon grinding the wafer, the separator is peeled off and the wafer processing film is adhered to the wafer. After completion of the grinding, the wafer processing film is peeled off from the wafer.
If air is included between the adhesive layer of the wafer processing film and a wafer when the processing film is applied to the surface of the wafer, the adhesive tends to remain on the surface of the wafer when the film is peeled off from the wafer. This residue causes corrosion of the resulting IC wafer so that the performance of the IC is lowered.
Further, adhesion of any foreign matter to the surface of the wafer from the film also induces corrosion of the resulting IC wafer, resulting in a reduction in the performance of the IC.
To cope with the problem of air inclusion, the following method is proposed in Japanese Utility Model Laid-Open No. 131631/1983 by way of example. According to the method, a resin film whose surface roughness has been improved to the range of .+-.0.1 .mu.m by coating a silicone-base release agent is employed as a separator (release layer), so that the surface of a pressure-sensitive adhesive layer as an adhesive layer is prevented from being roughened by the separator and, upon application of the wafer processing film to a wafer, air is prevented from being included between the adhesive layer of the film and the wafer. Because of the use of the silicone-base release agent, this method is, however, accompanied by the drawback that the release agent is transferred to the adhesive layer to contaminate the surface of the semiconductor wafer. This method is therefore not satisfactory.
According to the method proposed in Japanese Patent Application Laid-Open NO. 177423/1988, a semiconductor wafer fixing member with a release layer made of low-density polyethylene or polymethylpentene is used, and as a result, contamination of the semiconductor wafer due to transfer of the release agent or the like from the separator can be avoided. However, because of the high surface tension of low-density polyethylene, the peelability between a pressure-sensitive adhesive layer as an adhesive layer and the release layer is so poor that the surface of the adhesive layer is roughened when the release layer is peeled off from the semiconductor wafer fixing member. As a result, a number of fine air-filled spacings is formed at the interface between the adhesive layer and the wafer. When the wafer processing film is peeled off after the back side of the wafer has been ground and polished, the adhesive tends to remain around the air-contacted spots on the surface of the wafer and the adhesive residue causes corrosion of the wafer.
As has been described above, it is the current circumstance that, as a wafer processing film to be employed upon grinding an IC wafer, there is no useful film capable of preventin

REFERENCES:
patent: 4756968 (1988-07-01), Ebe et al.
patent: 4853286 (1989-08-01), Narimatsu et al.
patent: 4928438 (1990-05-01), Narimatsu et al.

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