Patent ID: 6486024
Filing Date: 2002-11-26
Classification: H01L

Abstract:
A method of forming an isolation collar in a deep trench on a semiconductor substrate, said method comprising:forming a conformal oxide layer on an interior surface of said trench; filling a lower portion of said trench with a mask layer, thereby masking a lower sidewall and bottom of said oxide layer and leaving an upper sidewall of said oxide layer unmasked; forming a conformal insulation layer on said oxide layer upper sidewall and on an upper surface of said mask layer; anisotropically etching said insulation layer to remove horizontal sections of said insulation layer, thereby leaving an upper sidewall of said insulation layer in said trench adjacent said oxide layer upper sidewall; removing said mask layer from said trench to expose said lower sidewall and bottom of said oxide layer; and removing said lower sidewall and bottom of said oxide layer from said trench to expose said substrate surface in said lower portion of said trench.