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:
Mar. 10, 1992
Filed:
Jul. 17, 1990
Applicant:
Inventors:
Assignee:
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01L / ; H01L / ; H01L / ;
U.S. Cl.
CPC ...
357 35 ; 357 15 ; 357 34 ; 357 36 ; 357 45 ; 357 51 ;
Abstract
A bipolar RAM comprising a plurality of memory cells formed of cross-coupled bipolar transistors and a peripheral bipolar circuit formed of bipolar transistor, provided with an epitaxial layer which is to be the collector region of the bipolar transistor in the memory cell portion which is thinner and has higher impurity density than the epitaxial layer which is to be the collector region of a bipolar transistor in the peripheral circuit.