Patent ID: 7879728
Filing Date: 2011-02-01
Classification: H01L

Abstract:
1. A method for forming a trench structure disposed over a substrate, the method comprising: depositing a sacrificial layer of a sacrificial material over the substrate; forming a first set of trenches in the sacrificial layer with a lithographic mask; filling the first set of trenches completely with a first set of step spacer blocks using two alternating spacer materials, the two alternating spacer materials being separately removable; forming a second set of trenches by selectively removing the remaining sacrificial material after filling the first set of trenches; filling the second set of trenches completely with a second set of step spacer blocks using the two alternating spacer materials in continuing sequence with the first set of step spacer blocks in the first set of trenches; forming a hard mask by selectively removing one of the two alternating spacer materials; and using the hard mask to etch the trench structure in the substrate; wherein forming the first set of step spacer blocks and the second set of step spacer blocks includes: