The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 30, 1993
Filed:
Mar. 16, 1992
Shin-Etsu Handotai Co., Ltd., Tokyo, JP;
Abstract
The present invention provides a semiconductor substrate which is formed by bonding wafers together by heat treatment without causing the substrate to be thermally damaged to have thermal strain, separation, cracks, etc. due to the difference in the thermal expansion coefficient of the wafers, and particularly a semiconductor substrate having an SOI structure which can provide a silicon film thin enough to allow various integrated circuits or TFT-LCD to be formed In the present invention, after wafers are bonded temporarily in a low temperature range, one of the wafers is made thin by chemical treatment, then the wafers were bonded fully by heat treatment in a temperature range (where the thermal expansion coefficient of the wafer are not affected) higher than the above low temperature range, and then said one wafer can be made thinner by mechanical grinding or polishing mechano-chemically. Thus according to the present invention, even if a semiconductor substrate is formed by sticking a silicon wafer and a quartz wafer together, damages that will be caused thermally due to thermal expansion can be prevented and a film which is made thin enough required for forming various integrated circuits or TFT-LCD or the like can be easily obtained.