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:
Nov. 08, 1994
Filed:
May. 03, 1993
Takeshi Kuragaki, Itami, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A method for producing a semiconductor device includes growing a collector layer, a base layer, and an emitter layer on a substrate; forming an emitter electrode, a tungsten film, and a silicon film services as an etching stopper on a prescribed region of the emitter layer; etching the emitter layer using the above-described films as a mask to expose the base layer; forming side walls on opposite side surfaces of the silicon film, tungsten film, emitter electrode, and emitter layer; forming a zinc oxide layer serving as an impurity diffusion source on the base layer and performing a diffusion to produce high purity concentration regions in the base layer; removing the zinc oxide layer by wet etching using hydrofluoric acid as an etchant; depositing a base metal on the base layer and removing an unnecessary portion of the base metal by ion milling for form base electrodes; selectively removing the silicon film; and forming an electrode in contact with the tungsten film. Since the silicon film is not etched by hydrofluoric acid when the zinc oxide layer is removed, the emitter electrode is not adversely affected by the ion milling in removing the base metal, resulting in an HBT with a reliable emitter electrode.