Patent ID: 6380610
Filing Date: 2002-04-30
Classification: H01L,Y10S

Abstract:
An oxidation mask for the local oxidation of silicon comprising:(a) a pad oxide; (b) a first silicon nitride layer over said pad oxide; (c) an auxiliary layer over said first silicon nitride layer; (d) a second silicon nitride layer over said auxiliary layer; (e) an opening passing through said second silicon nitride layer, said auxiliary layer, and said first silicon nitride layer, whereby the said opening in said second silicon nitride layer is of the same width as and concentric with said opening in said first silicon nitride layer; and (f) a lateral cavity in within said opening, recessing said auxiliary layer under the perimeter of said second silicon nitride layer whereby said second silicon nitride layer is undercut and overhangs said first silicon nitride layer in said opening.