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. 18, 2000
Filed:
Jan. 14, 1998
Applicant:
Inventor:
Yasuki Yoshihisa, Tokyo, JP;
Assignee:
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01L / ;
U.S. Cl.
CPC ...
257588 ; 438325 ;
Abstract
An oxide film mask 6b of a desired shape is formed on the surface of a polysilicon film 5a which becomes a base electrode and the top of the polysilicon film 5a is isotropically etched with the mask 6b, then the polysilicon film 5a is anisotropically etched with the same mask 6b for exposing an epitaxial layer 3.