Patent ID: 7994065

Claim:
A method for fabricating a semiconductor device, the method comprising: stacking a spin on carbon (SOC) layer and a multifunction hard mask (MFHM) layer on a substrate, wherein the SOC layer formed beneath the MFHM layer contains carbon; forming a photoresist pattern over the MFHM layer; first etching the MFHM layer using a first amount of a fluorine-based gas; second etching the first-etched MFHM layer using a second amount of a fluorine-based gas, wherein the second amount is less than the first amount; etching the SOC layer using the second-etched MFHM layer as an etch barrier; and etching the substrate using the etched SOC layer and the second-etched MFHM layer as an etch barrier, wherein the fluorine-based gas used in second etching the first-etched MFHM consists essentially of a gas mixture of CHF 3 at a flow of approximately 8 sccm to approximately 12 sccm and He at a flow rate of approximately 90 sccm to approximately 110 sccm.