Patent ID: 6967136
Filing Date: 2005-11-22
Classification: H01L

Abstract:
1. A method of providing a trench capacitor on a semiconductor substrate, comprising: forming a pad stack including a first material on a semiconductor substrate; forming a hard mask including a second material over said pad stack, wherein said first material is etch distinguishable from said second material; patterning said hard mask and said pad stack to form aligned openings in said hard mask and said pad stack extending from a top surface of said hard mask to a top surface of said semiconductor substrate; vertically etching said semiconductor substrate through said aligned openings to form a trench; horizontally widening sidewalls of said trench by a first etch process to form a widened trench having widened sidewalls extending from said top surface of said semiconductor substrate; widening sidewalls of said opening in said pad stack by a second etch process having etch selectivity to said second material to form a widened opening in said pad stack relative to said opening in said hard mask such that said hard mask overhangs said widened sidewalls of said widened opening in said pad stack and overhangs said widened sidewalls of said widened trench; forming a sacrificial collar on said widened sidewalls of said widened trench; vertically deepening said trench to create a lower portion extending below said sacrificial collar; and forming a capacitor in said lower portion.