Patent ID: 9614053
Date: 2017-04-04
CPC Classifications: H01L

Claim:
1. A method comprising: forming a spacer layer on a first top surface and sidewalls of a patterned feature, wherein the patterned feature is overlying a base layer, wherein the spacer layer comprises first horizontal portions directly on the base layer, and the first horizontal portions cover an entire top surface of the base layer, with the entire top surface being between the patterned feature and a neighboring patterned feature; forming a protection layer contacting a second top surface and a sidewall surface of the spacer layer, wherein the protection layer comprises second horizontal portions over the first horizontal portions; removing the second horizontal portions of the protection layer, wherein vertical portions of the protection layer remain after the removing; etching the spacer layer using the remaining vertical portions of the protection layer as an etching mask to remove all horizontal portions of the spacer layer, wherein the vertical portions of the spacer layer and the remaining vertical portions of the protection layer remain to form spacers; after the etching the spacer layer, removing the patterned feature; etching the base layer and the vertical portions of the protection layer to form a trench in the base layer, wherein the spacers are used as an etching mask; filling the trench with a metal; and removing the spacers.