Patent ID: 8119531
Filing Date: 2012-02-21
Classification: H01L

Abstract:
1. A method of forming a trench comprising: providing a material stack comprising a semiconductor layer or a dielectric layer, a metal nitride layer present on the semiconductor layer or the dielectric layer, a leveling layer that is present on the metal nitride layer, and at least one first mask layer on the leveling layer; etching a first plurality of trenches having a first pitch through the at least one first mask layer and the leveling layer, wherein the base of the first plurality of trenches stops on the metal nitride layer; removing the at least one first mask layer; forming at least one second mask layer on the leveling layer and an exposed portion of the metal nitride layer; etching a second plurality of trenches having a second pitch through at least the at least one second mask layer, wherein the base of the second plurality of trenches do not extend through the metal nitride layer; removing the at least one second mask layer; and etching exposed portions of the metal nitride layer selectively to the semiconductor layer or the dielectric layer and remaining portions of the leveling layer to extend the first plurality of trenches and the second plurality of trenches into contact with an upper surface of the semiconductor layer or the dielectric layer.