Selective Low Pressure Chemical Vapor Deposition of Tungsten

We have examined the kinetics of low pressure chemical vapor deposition of tungsten by the hydrogen and silicon reduction of within a pressure range of 0.1–5 torr and a temperature range of 250°–500°C. The rate‐limiting mechanism for the hydrogen reduction system was determined to be the dissociation of adsorbed on the surface, with an activation energy of 0.71 eV. A self‐limiting deposit results from the reaction, the thickness and structure of which are dependent upon the initial native oxide characteristics. Deposition occurs selectively on materials that react directly with or yield monatomic hydrogen. In the presence of hydrogen, the degree of selectivity is a function of temperature, substrate material, and surface cleanliness.