A process to form a copper-silicon-nitride layer on a copper surface on a
semiconductor wafer is described. The process may include the step of
exposing the wafer to a first plasma made from helium. The process may
also include exposing the wafer to a second plasma made from a reducing
gas, where the second plasma removes copper oxide from the copper
surface, and exposing the wafer to silane, where the silane reacts with
the copper surface to selectively form copper silicide. The process may
further include exposing the wafer to a third plasma made from ammonia
and molecular nitrogen to form the copper silicon nitride layer.