TAPER PROFILE ETCHING METHOD

PROBLEM TO BE SOLVED: To form a smooth etching profile without stepped portions or boundary irregularities by exposing a part comprising a substrate, an etchable film and a pattern-formable mask layer, to an etchant-gas mixture of halogen-including gas and inert gas. SOLUTION: The part to be etched having the substrate, an etchable film 12 and a mask layer 14 is exposed to an etchant-gas mixture of chlorine- including gas, helium gas and the like. Then, a taper mask layer surface 18 and a taper-etchable film surface 20 on the substrate form substantially equal etching angles θ1 and θ2 . A desired smooth etching profile is formed without stepped portions through the boundary between the etchable film 12 and the mask layer 14. The etchable film is etched when it is exposed to the etchant gas mixture, and non-exposed regions of the part are left after the completion of the etching process.