Etching gas compositions, methods of forming micropatterns, and methods of manufacturing semiconductor device

An etching gas composition comprising:

• a first organofluorine compound having a formula of CaFbHc;
• and
• an organosulfur compound having a formula of CxFySz, the organosulfur compound comprising at least one carbon-carbon double (—C═C—) bond,
• wherein the organosulfur compound is present in the etching gas composition in an amount of about 10 parts to about 60 parts by mole based on 100 parts by mole of the first organofluorine compound,
• wherein a is an integer of 3 to 6, b is an integer of 1 to 10, c is an integer of 1 to 6, x is an integer of 1 to 6, y is an integer of 1 to 16, and z is an integer of 1 to 4,
• wherein the etching gas composition comprises both a second organofluorine compound and a third organofluorine compound, wherein the first, second and third organofluorine compounds are different from each other,
• wherein the second organofluorine compound and/or the third organofluorine compound is present in the etching gas composition in an amount of about 1 part to about 60 parts by mole based on 100 parts by mole of the first organofluorine compound, and
• wherein a ratio of a molar number of the second organofluorine compound to a molar number of the third organofluorine compound is in a range of about 10 to about 32.