Temperature dependence of silicon carbide interface formation: A photoelectron spectroscopy study

Abstract

The formation of a carbide interface layer between the Si(100) surface and hydrogen-free ${\mathrm{sp}}^{2}$ amorphous carbon films is investigated at different substrate temperatures in the range from ambient to 1040 \ifmmode^\circ\else\textdegree\fi{}C. The analysis of the interface and film is performed with photoelectron spectroscopy in the ultraviolet and x-ray regime. A carbon beam is created by electron-beam evaporation of graphite and the stepwise in situ deposition of carbon (0.3 monolayer/min) allows to follow the evolution of the carbide surface layer and interface. At temperatures at and below 750 \ifmmode^\circ\else\textdegree\fi{}C a thin carbide layer (\ensuremath{\leqslant}0.4 nm) is rapidly formed, followed by the growth of a pure carbon overlayer. The valence band (VB) as well as the core-level spectra reflect the rapid formation of a SiC interface and subsequent carbon overlayer growth. If a substrate temperature above 900 \ifmmode^\circ\else\textdegree\fi{}C is chosen, the carbon overlayer growth is completely suppressed, and a pure carbide layer is present. The VB spectra of the carbide layer are identical to those of the bulk SiC phases. The continued carbide layer formation and absence of a carbon overlayer is attributable to the enhanced outdiffusion of silicon, which leads at the same time to the formation of a Si-rich surface. For temperatures below 900 \ifmmode^\circ\else\textdegree\fi{}C the carbidic interface is carbon-rich, which is attributed to carbon enrichment at the carbon-overlayer--carbide contact area. A comparison with experiments described in the literature allows to evaluate the influence of processing parameters such as ion irradiation on the interface formation.