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. 27, 1991
Filed:
Aug. 21, 1989
Kayoko Omoto, Hyogo, JP;
Kazuaki Miyata, Hyogo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A single chip microcomputer as a semiconductor device comprises CMOS logic portion and a driver portion operating at a high voltage which can be connected to an external device. In the region of the CMOS logic portion, a P type well layer and an N type well layer are formed on a P type silicon substrate. An N type well layer is formed in the region constituting the driver portion. The junction depth of the N type well layer constituting the driver portion is made deeper than that of the N type well layer constituting the CMOS logic portion. A MOS transistor is formed in the region of each well layer in the CMOS logic portion. A MOS transistor whose drain breakdown voltage is increased is formed in the region of the N type well layer of the driver portion. The junction depth of the N type well layer is made deeper than that of the N type well layer constituting the CMOS logic portion at least below the drain region of this MOS transistor. The MOS transistor constituting the CMOS logic portion operates at a lower voltage while the MOS transistor constituting the driver portion operates at a higher voltage in order to drive external devices such as a fluorescent display tube connected thereto.