Structure and growth kinetics of RhSi on single crystal, polycrystalline, and amorphous silicon substrates

Growth kinetics of rhodium silicide in the temperature range of 375-450°C have been studied on three different silicon substrates: single crystal, polycrystalline, and amorphous. The methods of analysis and specimen characterization utilized in this study are Rutherford backscattering spectroscopy (RBS), Seemann-Bohlin x-ray diffraction, cross-sectional transmission electron microscopy (TEM), sheet resistivity via four-point probe, and Schottky barrier height measurements obtained from the current-voltage relationship. Our results conclude that all three silicon substrates form an identical rhodium silicide compound, RhSi, indicating that the crystallinity of the substrate has no effect on the resulting rhodium silicide. The growth of RhSi was determined to be diffusion-limited and the activation energy of growth was similar for single crystal (1.88±0.04 eV) and amorphous silicon (1.86±0.07 eV), yet it was slightly lower (1.71±0.08 eV) for polycrystalline silicon. The difference can be attributed to the rhodium silicide compound having a smaller grain size in the polycrystalline silicon case. The layer formation and the thickness of rhodium silicide between unreacted rhodium and the three different silicon structures was examined by cross-sectional TEM and compared to those measured by RBS.