Method for forming a self-aligned contact and a plasma especially applicable in performing said method.

摘要

The method is applied after the contact region (27a) has been covered by a silicon nitride oxidation blocking mask (28a) which subsequently was subjected to oxidation and/or doping processes causing the formation of various compounds in the silicon nitride (28a) and at the interface between the silicon nitride (28a) and the contact region (27a). A non-selective etching process is used to remove silicon nitride (28a) and the formed compounds. In particular it has been found that a plasma comprising a organo-halide and an excess of oxygen can be used to non-selectively etch the silicon dioxide, the silicon nitride, its associated compounds and the material of the contact region, like polysilicon. The method is useful e.g. for the formation of the polysilicon gate of a silicon field effect transistor.