The effect of thermal annealing in a hydrogen atmosphere on tungsten deposited on 6H-SiC

Abstract

Tungsten (W) film was deposited on a bulk single crystalline 6HeSiC 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 ofW,WO3, W5Si3 andWC. RBS results indicated the interaction betweenWand 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, Wannealed 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.