PURPOSE: To simply and easily control etching process by using etching gas, which has different composition from that of the etching gas used in the initial process, for the latter process and forming a contact hole, which has taper sidewall, on a silicon oxide film.

CONSTITUTION: A resist film 8 provided with a window 8a is formed on a silicon substrate or on the surface of the silicon oxide film 6 formed on the base layer 5 of a wiring layer. When anisotropic etching is performed using only carbon tetrafluoride as etching gas, the edge of the resist film 8 is removed and a taper contact hole 7a which has an opening larger than the window 8a of the resist film 8 is formed. Then, when anisotropical etching is performed using the carbon tetrafluoride and argon mixed gas as etching gas keeping the plasma discharge condition, a cylindrical contact hole 7b with the size of the bottom of the contact hole 7a is formed, and a taper contact hole which has the continuous taper part and the cylindrical part is formed.