Patent ID: 7238586
Filing Date: 2007-07-03
Classification: H01L

Abstract:
1. A method of forming a trench isolation region, comprising: providing a substrate having thereon a mask layer; performing lithographic and etching processes to form an opening in said mask layer, said opening exposes a portion of said substrate; etching said substrate through said opening, thereby forming a trench; performing a sub-atmospheric pressure chemical vapor deposition (SACVD) process to deposit a silicon oxide layer in said trench, wherein said silicon oxide layer fills said trench and leaves a seam defect near its center; performing a steam anneal in hydrogen/oxygen ambient and at a temperature of lower than 800° C. to eliminate said seam defect; wherein said steam anneal is carried out at a relatively higher hydrogen flowrate of 5–20 L/min and oxygen flowrate of 5–20 L/min with hydrogen-to-oxygen ratio (volumetric flowrate ratio) between 1:2 and 3:1; and performing a densifying anneal process at a temperature of higher than 900° C. to densify said silicon oxide layer.