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

The formation of a carbide interface layer between the Si(100) surface and hydrogen-free sp(2) amorphous carbon films is investigated at different substrate temperatures in the range from ambient to 1040 degrees 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 degrees C a thin carbide layer (less than or equal to 0.4 nm) is rapidly formed, followed by the growth of a pure carbon overlayer. The valence band (VB) as well as the con-level spectra reflect the rapid formation of a SiC interface and subsequent carbon overlayer growth. if a substrate temperature above 900 degrees 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 degrees 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.