The effect of thermal annealing in a hydrogen atmosphere on tungsten deposited on 6HSiC

Tungsten (W) film was deposited on a bulk single crystalline 6HSiC substrate and annealed in H2 ambient at temperatures of 700 °C, 800 °C and 1000 °C for 1 h. The resulting solid-state reactions, phase composition and surface morphology were investigated by Rutherford backscattering spectrometry (RBS), grazing incidence X-ray diffraction (GIXRD) and scanning electron microscopy (SEM) analysis techniques. These results are compared with the vacuum annealed results reported in our earlier work. As-deposited RBS results indicated the presence of W and O2 in the deposited thin film, the GIXRD showed the presence of W, WO3, W5Si3 and WC. RBS results indicated the interaction between W and SiC was accompanied by the removal of oxygen at 700 °C. The GIXRD analysis indicated the presence of W5Si3 and WC in the samples annealed at 700 °C. At temperatures of 800 °C and 1000 °C, W annealed in a H2 ambient further reacted with the SiC substrate and formed a mixed layer containing silicide phases and carbide phases, i.e.W5Si3, WSi2, WC and W2C. The SEM micrographs of the as-deposited samples indicated the W thin film had a uniform surface with small grains. Annealing at 800 °C led to the agglomeration of W grains into clusters making the surface rough.