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:
Sep. 02, 2003
Filed:
Dec. 17, 2001
Masahiro Oda, Takatsuki, JP;
Kazuhiro Sasada, Hashima, JP;
Sanyo Electric Co., Ltd., Osaka, JP;
Abstract
Threshold voltage fluctuation in upper corner portions of a trench isolation is inhibited by rounding upper corner portions of the trench by thermal oxidation, introducing a first impurity into both upper corner portions of the trench and heat-treating the semiconductor substrate. Embodiments include increasing the threshold voltage in the upper corner portion of the trench in an n-channel transistor, previously increased by rounding oxidation, and introducing a p-type impurity, thereby canceling the threshold voltage reduction resulting from diffusion of the impurity during heat-treating the semiconductor substrate. In a p-channel transistor, the threshold voltage in the upper corner portion of the trench is increased by rounding oxidation thereby canceling the threshold voltage reduction resulting from introduction of the p-type first impurity into both upper corner portions of the trench.