Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Patent
1986-01-16
1989-08-01
Buffalow, Edith
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
428451, 428 40, 156297, 156662, C09V 702
Patent
active
048532860
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
TECHNICAL FIELD
This invention relates to a film which is used in the grinding of wafers such as silicon and other wafers so as to prevent their breakage.
BACKGROUND ART
Wafers for use in the fabrication of semiconductor chips include silicon wafers, gallium arsenide wafers and similar wafers. Among others, silicon wafers are being widely used. For example, silicon wafers are produced by cutting a high-purity single-crystal silicon ingot into slices having a thickness of the order of 500 to 1000 .mu.m. In recent years, these wafers are tending to become thinner as the size of chips is reduced and the production scale of chips is enlarged. Moreover, the diameter of these wafers is passing from the conventional value of 3-4 inches to 5-8 inches.
Silicon wafers are inherently fragile. In addition, silicon wafers having integrated circuits formed in their surface are easily broken, even under the action of slight external forces, because of their surface roughness. This disadvantage constitutes a serious obstacle to post-processing operations such as back surface grinding.
As a method for preventing silicon wafers from being broken during surface grinding there has conventionally been employed the method in which, prior to surface grinding, silicon wafers are coated with paraffin, resist ink or the like so as to compensate for their surface roughness and to distribute properly the external forces exerted thereon. However, this method involves the step of drying and solidifying paraffin or the like after its application to a wafer surface and the step of washing off the paraffin or the like from the ground wafer with a solvent under the application of heat, thus requiring complicated operation. In addition, this prior art method is still unable to prevent wafer breakage in the grinding of wafers having a diameter of 5 inches or greater, which has constituted a serious obstacle to the enhancement of productivity. Moreover, the use of paraffin or the like involves the problem of contamination of wafer surfaces. Accordingly, it has been strongly desired to develop a method for the prevention of wafer breakage which can replace the application of paraffin or the like.
As a method for the prevention of wafer breakage which can replace the application of paraffin or the like, one in which a processing film having an adhesive layer is affixed to a wafer surface has been investigated. However, this method has been unable to prevent wafer breakage perfectly. Moreover, it has been found that, where such a processing film is used, airborne dust may adhere to the adhesive layer during the manufacture, transport or storage of the film. If this dust is transferred and attached to the wafer surface, deterioration of the semiconductor due to wafer corrosion or the like and, further, malfunction or other problems may result. In other words, where such a processing film is used, the dust attached to the wafer surface cannot be satisfactorily removed simply by cleaning the processed wafer in the conventional manner. Because of these problems, no practical method for preventing wafer breakage by use of a processing film has been developed as yet.
DISCLOSURE OF THE INVENTION
In view of the above-described problems, the present inventors conducted research concerning the method of preventing the breakage of wafers being processed and have found that the breakage of wafers can be prevented by affixing a processing film having a specific hardness to a wafer surface with an adhesive layer interposed therebetween, so as to compensate for the roughness of the wafer surface and to distribute properly the external forces exerted thereon during processing. They have also found that, by laminating an auxiliary film having a specific hardness to the opposite surface of this processing film to that having an adhesive layer disposed thereon, its workability in affixing the processing film to a wafer and separating it from the processed wafer can be greatly improved without impairing its effect of preventing wafer breakage.
REFERENCES:
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patent: 4312916 (1982-01-01), Kakumaru et al.
patent: 4339486 (1982-07-01), Shimamoto et al.
patent: 4395451 (1983-06-01), Althouse
patent: 4756968 (1988-07-01), Ebe et al.
Technical Update, "B-Stage Epoxieu", 3-86, Grace Co.
European Search Report, Application No. 85902642.9.
Ito Michiyasu
Komatsu Kazuyoshi
Narimatsu Osamu
Shibata Yasuhiro
Buffalow Edith
Mitsui Toatsu Chemicals Incorporated
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