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. 24, 2009
Filed:
Feb. 02, 2005
Takaoki Ogawa, Kawasaki, JP;
Kazuhiro Tomita, Kawasaki, JP;
Koju Aoki, Kasugai, JP;
Fujitsu Microelectronics Limited, Tokyo, JP;
Abstract
An n-well is formed in a p-type semiconductor substrate. A gate insulative film is formed to the p-type semiconductor substrate and the n-well, and a gate electrode is formed on the gate insulative film. A source layer selectively diffused with n-type impurities at high concentration is formed adjacent to the gate insulative film on the surface of the p-type semiconductor substrate, the n-well and a region extending on both of them. Further, a contact layer selectively diffused with p-type impurities at high concentration is formed being spaced from the source layer. A capacitance characteristic of good linearity over a wide range relative to the inter-terminal voltage VT can be obtained by applying an inter-terminal voltage VT between the source layer and the gate electrode. A MOS type variable capacitance device capable of obtaining a characteristic of good linearity for a wide range relative to the inter-terminal voltage VT and capable of coping with the improvement of the performance of a VCO circuit, etc., as well as simple in the structure, and capable of being manufactured easily with no requirement for addition of masks and steps can be provided.