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:
Mar. 10, 1998
Filed:
Dec. 02, 1994
Hung-Sheng Chen, San Jose, CA (US);
Chih Sieh Teng, San Jose, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A bipolar transistor is fabricated by a process in which first and second dopants of the same conductivity type are introduced into a semiconductor body through at least partially overlapping sections, preferably the same section, of the body's upper surface to form an emitter. The first dopant is introduced at a greater dosage than the second dopant such that the emitter consists at least of a main emitter region constituted primarily with the first dopant. The introduction of the second dopant into the body entails ion implanting the second dopant at a tilt angle of at least 15.degree. relative to a direction generally perpendicular to the body's upper surface. Part of the second dopant is so implanted into an extension zone that extends laterally beyond the main emitter region. The extension zone may be of the same conductivity type as, or of opposite conductivity type to, the main emitter region. In either case, the extension zone is lightly doped and reduces transistor performance degradation by reducing the electric field along the emitter-base junction, especially along the upper semiconductor surface.