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:
Jan. 23, 2001
Filed:
May. 20, 1999
Tower Semiconductor Ltd., Migdal Haemek, IL;
Abstract
A method for forming a CMOS image sensor cell such that stress is minimized in regions surrounding the light sensitive (e.g., photodiode) portion of the cell, thereby reducing leakage current and minimizing white spots in CMOS image sensors. The field oxide surrounding the light sensitive region is formed with interior angles greater than 90° and/or is continuously curved. The reset gate is offset from the light sensitive regions of active pixel cells by a distance greater than 0.25 &mgr;m. A mask is used during n+ doping of the light sensitive region to shield an inner edge of the surrounding field oxide and extends 0.5 &mgr;m or more over the light sensitive region. A mask is provided over the interface between the field oxide and the light sensitive region during sidewall spacer formation. A metal structure contacting the light sensitive region is spaced 0.4 &mgr;m or greater from the surrounding field oxide. Metal lines passing between the light sensitive regions are provided with stress-relieving slits. Metal lines of a guard ring surrounding the pixel array are non-continuous to also provide stress relief.