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:
Jan. 01, 1991
Filed:
Apr. 03, 1990
Henricus G Maas, Eindhoven, NL;
Roland A Van ES, Eindhoven, NL;
Johannes W Van Der Velden, Eindhoven, NL;
Peter H Kranen, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A device area (16) is defined in a semiconductor body (10) by forming at one major surface (12, 12a) of the body a step (11) having a side wall (11a) and top surface (11b) bounding the device area 16. A silicon layer (13) is deposited so as to cover the side wall (11a) and top surface (11b) of the step and an adjoining lower surface area (12c). Dopant impurities are introduced so that the side wall silicon region (13a) is shielded from the dopant impurities and the undoped side wall silicon region (13a) is later removed by selective etching. The silicon region (13c) on the lower surface area (12a) adjoining the step (11) is masked and the silicon region (13a) on the top surface (11b) at the step (11) removed to leave the doped silicon region (13c) on the one major surface (12a) for contacting a device region (29), for example the base region of a transistor, of the device area.