Etching gas

Abstract

Disclosed is an etching gas provided containing CHF2COF. The etching gas may contain, as an additive, at least one kind of gas selected from O2, O3, CO, CO2, F2, NF3, Cl2, Br2, I2, XFn (In this formula, X represents Cl, I or Br. n represents an integer satisfying 1≦n≦7.), CH4, CH3F, CH2F2, CHF3, N2, He, Ar, Ne, Kr and the like, from CH4, C2H2, C2H4, C2H6, C3H4, C3H6, C3H8, HI, HBr, HCl, CO, NO, NH3, H2 and the like, or from CH4, CH3F, CH2F2 and CHF3. This etching gas is not only excellent in etching performances such as the selection ratio to a resist and the patterning profile but also easily available and does not substantially by-produce CF4 that places a burden on the environment.

Dependencies are inferred from the claim text.