Deposition of WSi_x films from preactivated mixture of WF₆/SiH₄

WSi_x films were formed on a substrate from thermal chemical vapor deposition (CVD) of WF₆ and SiH₄. Chemical reactions were initiated upstream of the substrate by a preheater, and chemical reactions are radical chain reactions which produce preactivated cursors that are deposited, causing film growth. Because chemical reactions occur upstream of the substrate, film formation occurred even at temperatures as low as 40° C. Compared with films deposited at the same substrate temperature, without preheating, the Si content increased by 50%, the interfacial concentration of residual fluorine decreased by one order of magnitude, and the sticking probability of the precursors on the substrate was the same. The sticking probability was shown to depend solely on the substrate temperature, even for varying degrees of preheating. Deposition on a low-temperature substrate of the preactivated precursors provides a means to deposit conformal WSi_x films with low interfacial concentration of fluorine.