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:
May. 01, 1990
Filed:
Mar. 31, 1988
Atsuo Watanabe, Hitachiota, JP;
Takahide Ikeda, Tokorozawa, JP;
Kiyoshi Tsukuda, Hitachi, JP;
Mitsuru Hirao, Naka, JP;
Touji Mukai, Sanda, JP;
Tatsuya Kamei, Hitachi, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An improved arrangement is provided for forming a bipolar transistor on a substrate with CMOS elements. All of the transistors (i.e., the bipolar, P-MOS and N-MOS) are formed in regions having gradually decreasing impurity concentrations from the surface toward the substrate. In addition, a buried layer is provided under each of the regions of decreasing impurity concentration in which the transistors are formed. These buried layers have a significantly higher impurity concentration than the portion of the region of decreasing impurity concentration which they are respectively adjacent to. Using this arrangement, punch-through is prevented and excellent electrical operating characteristics are provided for both the bipolar transistors and the CMOS elements.