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. 15, 1997
Filed:
Apr. 13, 1994
Liem Thanh Tran, Torrance, CA (US);
Dwight Christopher Streit, Seal Beach, CA (US);
Aaron Kenji Oki, Torrance, CA (US);
TRW Inc., Redondo Beach, CA (US);
Abstract
This invention discloses a heterojunction bipolar transistor (HBT) which includes a relatively thin intrinsic collector region and a relatively thick extrinsic collector region such that collector-base capacitance is reduced and electron transit time is maintained. The fabrication of the HBT includes loading a semi-insulating substrate into an molecular beam epitaxy machine, and growing a sub-collector contact layer, a bottom collector layer and a top collector layer on the substrate. Next, the substrate is removed from the molecular beam epitaxy machine and the top collector layer is etched by a photolithographic process to produce separate intrinsic and extrinsic collector regions. Then, the substrate is again loaded into the molecular beam epitaxy machine so that the base and emitter layers can be grown. And finally, the emitter layer is etched to form an emitter mesa only over the intrinsic semiconductor region.