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:
Dec. 09, 2008
Filed:
Oct. 12, 2006
Osamu Fujita, Kanagawa, JP;
Osamu Fujita, Kanagawa, JP;
NEC Electronics Corporation, Kanagawa, JP;
Abstract
Fabrication method of semiconductor device to reduce leak current at junction interface of p-type well and n-type well. The method includes forming a first trench portion by selective dry etching of a silicon substrate using a first etching gas and forming a second trench portion including an enlarged width portion downward from a bottom of the first trench portion by additional dry etching of a silicon substrate at the bottom of the first trench portion using a second etching gas. A mixture gas of a chlorine gas and a fluorocarbon gas is used as the second etching gas and also a bias voltage lower than that in the process to form the first trench portion are used in the process to form the second trench portion.