Energy filtered TEM analyses of Ge snowploughing during oxidation of SiGe/Si MOSFET device structures

Energy filtered transmission electron microscopy has been used to investigate the effects of oxidation of SiGe/Si pseudomorphic MOSFET test structures. In particular, it will be demonstrated that Ge is found to accumulate or be ‘snow-ploughed’ to the Si/SiO₂ interface during Si-cap oxidation. Moreover, the concentration of Ge confined to this interface is found to be an order of magnitude greater than suggested by previous measurements made by SIMS. Such an enriched Ge layer is entirely consistent with theoretical predictions based of segregation modelling of the Ge distribution in such alloy layers.