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. 05, 1993
Filed:
Jan. 24, 1992
John E Turner, Woodside, CA (US);
Theodore I Kamins, Palo Alto, CA (US);
Martin P Scott, San Francisco, CA (US);
Yvonne H Keller, San Jose, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A method of fabricating a semiconductor device to retard diffusion of a dopant from a center active region into adjacent regions. The center active region is epitaxially formed by selectively increasing and decreasing an introduction of diffusion-suppressing material, preferably germanium, into a semiconductor material, preferably silicon, so that a vertical profile of the content of the diffusion-suppressing material is such that outdiffusion of a dopant is minimized. One embodiment of the tailoring is to increase the concentration of the diffusion-suppressing material at both of the opposed sides of a base region of a bipolar transistor, thereby providing concentration peaks at the interfaces of the base region with collector and emitter regions. The concentration of germanium in a Si.sub.1-x Ge.sub.x layer is such that the value x is within the range 0.08 to 0.35 and optimally within the range 0.15 to 0.31. The dopant, preferably boron, also has a tailored concentration profile to minimize outdiffusion. A thinner, more highly doped active region is thereby achieved.