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. 20, 2002
Filed:
Sep. 29, 2000
Applicant:
Inventors:
Peter H Osborne, Swindon, GB;
Martin C Wilson, Cricklade, GB;
Assignee:
Mitel Semiconductor Limited, , GB;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01L 2/18222 ;
U.S. Cl.
CPC ...
H01L 2/18222 ;
Abstract
A number of npn and pnp bipolar transistors are formed in a single chip of silicon, so that some of the transistors have a greater frequency response than others The higher frequency transistors have their emitters located closer to the collectors, by positioning a collector, or emitter, of a transistor in a recessed portion of the surface of the chip. The recess is formed in an accurate and controlled manner by locally oxidising the silicon surface, and subsequently removing the oxide to leave the recess.