Patent ID: 7732341

Claim:
A method of forming a hard mask, comprising: forming a first hard mask layer on a substrate; forming a first sacrificial pattern of substantially identical features on the first hard mask layer, wherein the features are spaced from one another in a first direction by a first pitch; forming a second hard mask layer on the first sacrificial pattern and the first hard mask layer, wherein the second hard mask layer delimits recesses each of which extends between a respective pair of adjacent ones of the features of the first sacrificial pattern; forming a second sacrificial pattern within the recesses; removing upper portions of the second hard mask layer to expose the first sacrificial pattern; removing all parts of the first sacrificial pattern and all parts of the second sacrificial pattern; and subsequently etching the second hard mask layer and the first hard mask layer to form a hard mask having a pattern of features composed of residual portions of the first hard mask layer and residual portions of the second hard mask layer disposed on the residual portions of the first hard mask layer.