High Temperature Evolution of Thin Films Confined between Two SiC Substrates

We investigate the possibility to use silicon, titanium and tungsten as bonding materials between a SiC substrate and a SiC layer, a novel substrate for application in high-power electronics. By using transmission electron microscopy, scanning transmission electron microscopy and X-ray scattering techniques, we address the high temperature-induced phase and morphology changes in thin layers composed of these materials and at their interfaces with SiC. For all three materials, we show that the homogenous continuous film created after low temperature deposition transforms into a discontinuous structure following high temperature annealing. All layer’s structures tend to reach an epitaxial relation with the SiC substrates. In contrast to Si layer which preserves its composition, both Ti and W layers are transformed into new phases which were identified. We evidence that these peculiar structural and compositional changes in the layers, which were studied as a function of annealing temperature and time, are related to mechanisms of SiC dissolution and transport of C, Si, Ti, W atoms at the interface. Potential chemical and structural reactions during interface reconstructions are discussed in relation to the experimental findings.