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. 25, 1978
Filed:
Dec. 16, 1976
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A silicon oxide layer containing a group III element such as boron, aluminum or gallium is formed on a semiconductor substrate. The substrate is then heat treated at 600.degree. C - 1200.degree. C in a nitrogen atmosphere and a diffusion process carried out thereafter. In this manner, the impurity diffused surface of the semiconductor body is controlled to a low concentration not higher than 10.sup.18 /cm.sup.3 of the group III element. This is due to the fact that the silicon oxide layer containing the group III element (that is, the so-called doped oxide) is partly converted to a nitride in the course of an ammonia treatment resulting in an impurity source for the low concentration diffusion. The present method is useful in forming the base region of an NPN transistor, for example.