Key-hole reduction during tungsten plug formation

摘要

The problem of key-hole formation during the filling of small diameter via holes has been overcome by means of soft sputtering in argon after the barrier layer is in place. This sputtering step may be used twice-once to widen the mouth of a newly formed via hole, and a second time after the barrier layer is in place, thereby widening the mouth further (as well as removing oxide from the surface of the barrier layer). In an alternate optional embodiment, widening of the via hole mouth may be limited to a single sputtering step after the barrier layer has been laid down. In either case, this is followed by filling of the via hole which occurs without any key-hole formation.