Abstract:
Tungsten (W) thin film was deposited on bulk single crystalline 6H-SiC substrate and annealed in vacuum
at temperatures ranging from 700 to 1000 C for 1 h. The resulting solid-state reactions, phase composition
and surface morphology were investigated by Rutherford backscattering spectroscopy (RBS), grazing
incidence X-ray diffraction (GIXRD) and scanning electron microscopy (SEM). XRD was used to identify
the phases present and to confirm the RBS results. The RBS spectra were simulated using the RUMP
software in order to obtain the deposited layer thickness, composition of reaction zone and detect phase
formation at the interface. RBS results showed that interaction between W and SiC started at 850 C. The
XRD analysis showed that WC and CW3 were the initial phases formed at 700 and 800 C. The concentration
of the phases was however, too low to be detected by RBS analysis. At temperatures of 900 and
1000 C, W reacted with the SiC substrate and formed a mixed layer containing a silicide phase (WSi2)
and a carbide phase (W2C). The SEM images of the as-deposited samples showed that the W thin film
had a uniform surface with small grains. The W layer became heterogeneous during annealing at higher
temperatures as the W granules agglomerated into island clusters at temperatures of 800 C and higher.
