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:
May. 13, 2003
Filed:
Nov. 22, 2000
Tatsuhiko Ikeda, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A method of manufacturing a hetero-junction bipolar transistor (HBT) which is suitable for high frequency operation. In the method, a first conductive layer and a first insulation layer are formed on a semiconductor substrate in an overlapping manner. A first mask is patterned on the first insulation layer. An impurity of a first conductive type is implanted into the first insulating layer using the first mask. The first mask is scaled down before a second mask is formed so as to cover the entire surface of the first insulating layer, with exception of an area covered by the scaled-down first mask. After elimination of the first mask, an opening is formed in the first insulating layer, by means of removal of the area coated with the scaled down first mask. An impurity of second conductivity type is introduced into an exposed portion of the first conductive layer within the opening.