PLASMA-ASSISTED OXIDATION OF SIGE LAYERS AT 500-DEGREES-C - INTERFACECHARACTERIZATION

In this paper, we investigate the germanium behaviour during the low t emperature plasma assisted oxidation of strained epitaxial Si1-xGex (x = 0.05, 0.1 and 0.2) layers. For an oxidation temperature of 500 degr ees C and an oxide thickness between 80 and 350 Angstrom, using Auger depth profiling, we find that the oxidation process leads to the forma tion of a pure SiO2 top layer and the rejection of Ge at the oxide/all oy interface. Taking into account in a suitable way the broadening eff ects affecting the Auger profiles, we show that a pure Ge layer is for med at the interface. For longer oxidation times, this interfacial lay er reaches a 'critical' thickness which is found to be independent of the germanium concentration of the SiGe substrate. Then, some germaniu m atoms begin to be embedded in the SiO2 layer before starting to be o xidized.