LOW-PRESSURE CVD OF TUNGSTEN CARBIDES

Tungsten carbide films have been deposited by CVD from a WF6/C3H8/H-2 gas mixture on several different substrate materials (Ta, Si, SiC and C). Single-phase WC films could easily be obtained on Ta substrates at 900 degrees C using a total pressure of 100 mTorr and a high linear g as flow velocity (7 m/s). It was found that the low pressures favoured the growth of carbon-rich films and made the deposition zone for WC l onger. The phase composition of the films and deposition rates were al so strongly affected by the substrate material. The substrate dependen ce was attributed to the chemical reactivity of WF6.