Interaction of hydrogen plasma with carbon–tungsten composite layer

Interaction of neutral hydrogen atoms with the layer of hydrogenated carbon–tungsten composite was studied. A 1 μm thick layer was prepared by sputter deposition from C and WC-targets in Ar/C2–H2 gas mixture. After deposition the samples were treated in weakly ionized highly dissociated hydrogen plasma created in a microwave discharge at a power of 1 kW. The gas flow was 13 l/h and pressure was 90 Pa. Temperature of the samples during treatment was about 850 K. After plasma treatment the samples were analyzed by AES (Auger electron spectroscopy) depth profiling, XPS (X-ray photoelectron spectroscopy) and SEM (scanning electron microscopy). It was found that during hydrogen plasma treatment selective etching of the C–W layer occurred. Carbon was preferentially removed from the C–W layer, and after about 10 min of treatment practically only tungsten with a huge porosity was detected.