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:
Nov. 03, 1998
Filed:
Sep. 06, 1996
Tetsuo Mizoguchi, Hitachi, JP;
Masahiro Nagasu, Hitachinaka, JP;
Hideo Kobayashi, Hitachi, JP;
Tsutomu Yatsuo, Hitachi, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
There is provided a semiconductor substrate which includes a pair of main surfaces, a first semiconductor layer of a first conductivity type adjacent to one of the main surface, a second semiconductor layer of a second conducting type of which impurity concentration is lower than that of the first semiconductor layer and which is adjacent to the first semiconductivity, a third semiconductor layer of the first conductivity type adjacent to the second semiconductor, and a fourth semiconductor of the second conductivity type of which impurity concentration is higher than that of the third semiconductor and which is adjacent to the other of the main surfaces and the third semiconductor. The device further includes one main electrode in ohmic-contact with the first semiconductor layer on one of the main surfaces of said semiconductor substrate, the other main electrode in ohmic-contact with the first semiconductor layer on the other of the main surfaces of said semiconductor substrate, and a control electrode connected electrically to the third semiconductor layer. The total amount of impurities of said third semiconductor layer is less than 10.sup.14 cm.sup.-2.