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:
Jul. 16, 1996
Filed:
Aug. 15, 1994
Murray J Robinson, Falmouth, ME (US);
Christopher C Joyce, Gorham, ME (US);
Timwah Luk, Scarborough, ME (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
An improved Schottky transistor structure (6), including a bipolar transistor structure (7) and a Schottky diode structure (8), is formed by retrograde diffusing relatively fast diffusing atoms to form a localized retrograde diode well (9) as the substrate for the Schottky diode structure. An expanded buried collector layer (11) formed of relatively slow diffusing atoms underlies the base and collector regions of the bipolar transistor structure (7) and the retrograde diode well (9). A diode junction (10) is formed by expanding the base contact of the bipolar transistor structure to include the surface of the retrograde diode well. Preferably, the diode junction is a Platinum-Silicide junction. The improved Schottky transistor structure may be formed as part of a bipolar junction transistor fabrication process or a BICMOS integrated circuit fabrication process wherein the buried diode layer may be formed at the same time as the buried collector layer of the bipolar transistor structure and the retrograde diode well may be formed at the same time as the sub-emitter collector region of the bipolar transistor structure. The buried collector layer definition mask is also a buried diode layer definition mask, the sub-emitter collector region definition mask is also a retrograde diode well definition mask, and the bipolar contacts definition mask is also a diode junction contact definition mask.