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. 23, 1991
Filed:
Oct. 10, 1990
Yasukazu Seki, Kanagawa, JP;
Fuji Electric Co., Ltd., Kawasaki, JP;
Abstract
The present invention relates to a method of producing an insulated gate bipolar transistor, of a vertical insulated gate field effect transistor. In the present invention a window portion is formed on a low-temperature oxide film and a polysilicon layer deposited on a polysilicon layer, which serves as a gate, and the ions of impurities are implanted while using these as a mask, thereby forming a P-base layer. The ions of impurities are then again implanted using this mask to form a P.sup.++ layer instead of using a conventional resist mask. Accordingly, in the present invention, the P.sup.++ layer is formed in self alignment with the edge of the polysilicon gate. Since there is no positional deviation due to inaccurate mask positioning which may be produced when a mask such as a resist is used, positional accuracy is enhanced which hereby eliminates latchup.