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. 25, 1989
Filed:
Feb. 05, 1988
Yasutomo Kajikawa, Itami, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A method of manufacturing a heterojunction bipolar transistor comprising the sequential steps of; forming an extra epitaxial layer (9) on a layered structure which consists of a collector layer (2), a base layer (3), and an emitter layer (4) provided on a semiconductor substrate (1) in that order; forming a recess (10) by selectively etching the extra epitaxial layer (9); and forming an emitter electrode (70a) and a resist mask (70a) in the recess (10) by way of self alignment scheme, where the resist mask (70a) covers the emitter electrode (60e). An extremely small-sized resist mask (70a) can be formed, and extremely small-sized emitter mesa (4a) is formed by applying wet etching to the epitaxial layer (9) and the emitter layer (4) using the resist mask (70a).