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:
Jun. 01, 1993
Filed:
Aug. 29, 1991
Shigeo Nagao, Hyogo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A method of forming a isolation region in a semiconductor device includes the steps of forming an underlying oxide film on a semiconductor substrate, forming a first polysilicon layer on the underlying oxide film, forming a silicon nitride film on the first polysilicon layer, patterning the silicon nitride film such that the silicon nitride film is left only on a circuit element region of the substrate at which a circuit element is to be formed, depositing selectively a second polysilicon layer by vapor deposition on regions of the first polysilicon layer which are exposed by patterning, and forming isolation regions of silicon oxide by thermally oxidizing at least the second and the first polysilicon layers using the patterned nitride film as a mask.