Method of forming etching mask

A method of forming an etching mask to etch a film under a hard mask film on a substrate having the hard mask film comprising SiN and a patterned photoresist sequentially formed thereon, the patterned photoresist comprising an ArF (193 nm) resist, the method comprising the step of:

• etching the hard mask film using the photoresist pattern as a mask and using an etching gas including a CH2F2 gas injected at a flow rate of 20 to 40 sccm and H2 gas injected at a flow rate of 40 to 80 sccm so that etch selectivity of the hard mask to the photoresist approaches infinity.

A method of forming an etching mask to etch a film under a hard mask film on a substrate having the hard mask film comprising SiN, a ARC and a patterned photoresist sequentially formed thereon, the patterned photoresist comprising an ArF (193 nm) resist, the method comprising the steps of:

• etching the ARC using the photoresist pattern as a mask;
• and
• etching the hard mask film using the photoresist pattern and ARC as a mask while a surface of the photoresist pattern is polymerized, and using an etching gas including a CH2F2 gas injected at a flow rate of 20 to 40 sccm and H2 gas injected at a flow rate of 40 to 80 sccm so that etch selectivity of the hard mask to the photoresist approaches infinity.