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:
Aug. 19, 1997
Filed:
Sep. 23, 1994
Yi-Hen Wei, Saratoga, CA (US);
VLSI Technology, Inc., , US;
Abstract
The present invention provides a bipolar transistor in which a lightly doped n-type hot-carrier shield extends in an epitaxial layer adjacent from a poly-emitter to an extrinsic base. This hot-carrier shield minimizes performance impairment that would otherwise occur due to a hot-carrier effect. Key steps in the method of making the bipolar transistor include a differential thermal oxidation while the poly-emitter is covered with a nitride cap. After the nitride cap is removed, an n-type dopant is implanted. The unprotected poly emitter is heavily doped. The implant partially penetrates a relatively thin oxide growth, thereby forming the hot-carrier shield. Other areas, such as the extrinsic base, and a polycrystalline base extension are covered by a relatively thick oxide growth and are unaffected by the n-type implant.