Patent ID: 7662721

Claim:
A method of patterning a layer to be patterned, comprising: providing a layer to be patterned; providing a hard mask layer stack, comprising a carbon layer disposed on top of the layer to be patterned, a first layer of a material selected from a group comprising of SiO 2 and SiON disposed on top of the carbon layer, and a silicon layer disposed on top of the first layer, on the layer to be patterned; providing, a first photoresist layer on top of the silicon layer; imaging first structures in a first exposure using a first photomask into the first photoresist layer; and developing the first photoresist layer, so as to generate a photoresist pattern on the silicon layer; etching the portions of the silicon layer uncovered by the fist photoresist pattern thereby forming first patterns; removing the first photoresist layer from the silicon layer leaving a surface of a substrate with regions covered by the silicon layer and regions with uncovered first layer of the hard mask layer stack; providing a second photoresist layer on top of the surface of the substrate; imaging second structures in a second exposure using a second photomask into the second photoresist layer; developing the second photoresist, so as to generate a photoresist pattern on the surface of the substrate; and etching the uncovered portions of the silicon layer uncovered by the second photoresist pattern thereby forming second patterns; patterning the first layer and the carbon layer in accordance with the second patterns; and etching the uncovered portions of the layer to be patterned.