Oxidation Phenomena of Polysilicon/Tungsten Silicide Structures

In order to increase the conductivity of polysilicon lines used in polysilicon VLSI technology, silicides ( e,g. , , , and ) are presently being considered as overlays on the polysilicon lines. One advantage of a polysilicon/silicide structure is that presumably, it is an oxidizable, self‐passivating structure. Under certain oxidation conditions similar to those employed in polysilicon FET processing, voids may develop in the polysilicon layer and/or undesirable oxides lacking structural integrity may develop on the silicide surface. The oxidation mechanisms governing these phenomena are herein discussed.