Abstract: A process for fabricating a semiconductor device, which comprises forming a recess portion in an insulating film covering a wiring made of copper or a copper alloy so that the recess portion reaches the wiring, wherein, after forming the recess portion, a plasma treatment using a gas containing hydrogen gas and nitrogen gas is conducted in a state such that the wiring is exposed through the bottom portion of the recess portion, or a plasma treatment using a gas containing hydrogen gas is conducted in a state such that the wiring is exposed through the bottom portion of the recess portion while cooling a substrate on which the wiring is formed. By the process of the present invention, a problem of redeposition of copper on the sidewall of a via hole in the argon sputtering and a problem of an etching process of the organic insulating film in the hydrogen plasma treatment can be solved, thus realizing excellent cleaning of the bottom portion of the via hole.