layers in this reaction a seed layer of tungsten silicide is formed on the silicon finger the hydrogen reduction results in good coverage with a well crystalized film this reaction occurs at a temperature of between approximately 300 u00b0 c to approximately 500 c deposition rates increase at increased pressure of 10 to 60 torr however lower pressures favor tungsten layers with lower tensile stresses the hydrogen reaction is generally not preferred as a mechanism to deposit a seed layer in that the high reactivity of wf 6 with si can result in excessive si consumption encroachment of the si sio 2 interface and wormhole formations in contrast the silane reduction reaction generally does not disturb the silicon substrate the tungsten deposition involves a temperature dependent chemical reaction thus the deposition may take place at any temperature that promotes the reaction it is preferred that the reaction take place at approximately 400 u00b0 c alternatively the reaction may take place at a temperature of between approximately 300 u00b0 c to approximately 500 u00b0 c tungsten depositions are further characterized by good conformality the thickness of the coating is generally even at differing points of the underlying surface 0 preferably the seed layer is coated on all exposed.