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. 14, 1998
Filed:
Apr. 03, 1997
Todd A Randazzo, Colorado Springs, CO (US);
John J Seliskar, Colorado Springs, CO (US);
Symbios, Inc., Fort Collins, CO (US);
Abstract
A bipolar transistor with a relatively deep emitter region is formed in a BICMOS device using the source/drain mask used to form the source and drain regions of MOSFETs of the device and the base region mask which would otherwise be required in any event to diffuse an emitter region of the bipolar transistor. The emitter is diffused or implanted to a depth greater than the depth to which a source and a drain region of the MOSFET are diffused. By using only the base region and source/drain region masks, and developing in sequence, each of two coatings of photoresist applied on top of one another, an access opening to the emitter region is define solely by the co-location of openings in each of the two coatings, thereby allowing the emitter region to be separately and additionally implanted. The access to the base region for the additional implication is achieved using only a few additional photo-ops and not as a result of using an additional emitter mask.