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. 02, 2011
Filed:
Feb. 08, 2008
Randy W. Mann, Burlington, NC (US);
Jae-eun Park, Wappingers Falls, NY (US);
Richard A. Wachnik, Mount Kisco, NY (US);
Randy W. Mann, Burlington, NC (US);
Jae-Eun Park, Wappingers Falls, NY (US);
Richard A. Wachnik, Mount Kisco, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
An array of deep trenches is formed in a doped portion of the semiconductor substrate, which forms a lower electrode. A dielectric layer is formed on the sidewalls of the array of deep trenches. The array of deep trenches is filled with a doped semiconductor material to form an upper electrode comprising a top plate portion and a plurality of extension portions into the array of trenches. In a depletion mode, the bias condition across the dielectric layer depletes majority carriers within the top electrode, thus providing a low capacitance. In an accumulation mode, the bias condition attracts majority carriers toward the dielectric layer, providing a high capacitance. Thus, the trench metal-oxide-semiconductor (MOS) varactor provides a variable capacitance depending on the polarity of the bias.