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:
Jul. 16, 1991
Filed:
Aug. 13, 1990
Tatsuo Ito, Jouetsu, JP;
Yasuaki Nakazato, Koushoku, JP;
Shin-Etsu Handotai Co., Ltd., Tokyo, JP;
Abstract
A process for producing an SOI-structured semiconductor device substrate has the steps of: reducing the diameter of the one Si-monocrystal wafer of two bonded polished Si-monocrystal wafers to be slightly smaller than that of the other Si-monocrystal wafer so that the width of the annular margin defined between the bonded surfaces of the Si-monocrystal wafers is uniform; then forming an annular polishing guard on the cylindrical surface of the one wafer and the margin of the other wafer, the polishing guard having a predetermined thickness and being made of a material providing a polishing speed lower under the same condition than the one wafer; and then polishing the one wafer so as to make it in thin film. The polishing guard provides an accurate thickness control of the resulting Si-monocrystal thin film, in particular, even at a few micrometers level.