Patent ID: 8421194

Claim:
A trench structure disposed over a substrate, the trench structure formed at least in part by the steps of: 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 first set of step spacer blocks includes a first pair of step spacers along the inside walls of the first set of trenches using a first spacer material, a second pair of step spacers along the inside walls of the first pair of step spacers using a second spacer material, and a first spacer plug along the inside walls of the second pair of step spacers using the first spacer material, 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.