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:
Apr. 20, 1993
Filed:
Jan. 24, 1991
Hiroomi Nakajima, Yokohama, JP;
Nobuyuki Itoh, Tokyo, JP;
Hiroyuki Nihira, Ayase, JP;
Eiryo Tsukioka, Tokorozawa, JP;
Kenji Hirakawa, Yokohama, JP;
Shin-ichi Taka, Yokosuka, JP;
Hideki Takada, Yokohama, JP;
Yasuhiro Katsumata, Chigasaki, JP;
Toshio Yamaguchi, Tokyo, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
In the method of manufacturing a semiconductor device, a buffer oxide film, an oxidation-resistant film and a first poly-Si film containing a p-type impurity are successively formed to form a laminate structure on the n-type collector region, followed by forming a protective oxide film by CVD. Then, an opening portion reaching the oxidation-resistant film is formed, followed by forming a second protective insulation film to cover the surface of the first poly-Si film exposed at the side wall of the opening portion. The oxidation-resistant film is excessively etched using the protective insulation films as an etching mask so as to expose the buffer oxide film and to form a bore below the first poly-Si film. The exposed buffer oxide film is removed, followed by filling the bore with a second poly-Si film. Then, a heat treatment is performed under an oxidative atmosphere to form a thermal oxide film covering the surface of the second poly-Si film. At the same time, the p-type impurity contained in the first poly-Si film is diffused through the second poly-Si film into the collector region to form a p-type outer base region. Further, a p-type inner base region, n-type emitter region and an emitter electrode are formed.