Gas-phase reactions of WF6with SiH4for deposition of WSinfilms free from powder formation

We elucidate the comprehensive mechanism of gas-phase reactions of WF6 with SiH4 for deposition of high-density W silicide (WSi n , 0 ~10, less reactive fluorine-deficient molecules are formed by the reduction reaction, inhibiting the powder formation. Only when the gas-phase reaction with SiH4 is sufficiently promoted under the condition of an extremely high R S/W > 103, the W-atom-encapsulated Si n cage clusters are formed without fluorine content, leading to the powder-free deposition of the dense WSi n film of n ≥ 6 with a homogeneously smooth surface.