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. 17, 2010
Filed:
Aug. 11, 2005
Charles A. Dark, Arlington, TX (US);
Charles A. Dark, Arlington, TX (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A system and method is disclosed that prevents the formation of a vertical bird's beak structure in the manufacture of a semiconductor device. A polysilicon filled trench is formed in a substrate of the semiconductor device. A composite layer stack is formed over the trench that has a nitride layer as a top layer. A plasma enhanced chemical vapor deposition (PECVD) oxide cap layer is formed over the nitride layer over the trench area. A mask and etch process is then applied to etch the composite layer stack adjacent to the polysilicon filled trench. A field oxide process is applied to form field oxide portions in the substrate adjacent to the trench. Because no field oxide is placed over the trench there is no formation of a vertical bird's beak structure. A gate oxide layer is applied to protect the trench from unwanted effects of subsequent processing steps.