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:
Sep. 03, 1991
Filed:
Apr. 23, 1990
Hirokazu Kimura, Joetsu, JP;
Shin-Etsu Handotai Co., Ltd., Tokyo, JP;
Naoetsu Electronics Company, Niigata, JP;
Abstract
When both main surface sides of a substrate doped with an impurity at a lower concentraiton are subjected to diffusion to form a higher concentrated impurity layer on the surfaces, about a half of the thickness of the substrate is removed to expose a layer doped with the impurity at the lower concentration on one surface of the substrate. Then the exposed lower concentrated impurity layer is polished to provide the substrate for semiconductor device comprising double layers composed of higher and lower concentrated impurities. Beveled portions are formed to have such a peripheral contour of the substrate as a beveled depth of the surface to be removed substantially half the thickness of the substrate is made larger than that of the surface not to be removed of the substrate, and an angle between an inclining surface and a main surface of the beveled portion on the removed surface is made larger than that of the beveled portion of the non-removed surface, before the diffusion to both the surfaces is carried out or after the same has been carried out.