A kinetic model was developed in order to describe the oxidation behavior of SiGe alloys during Ge segregation. This compared the Deal-Grove flux of oxidant, diffusing through the oxide, to the maximum flux of Si which diffused through the Ge-rich layer. It served to explain the results of thermal oxidation data for Si1-xGex alloys, where x was less than 0.17, in a F-containing ambient (O2 plus 200ppm of NF3). It was recalled that F was known to bias point defect generation, during the oxidation of pure Si, towards vacancy production. This was also the case for Ge in Si. It was demonstrated that the fluorinated oxidation of SiGe enhanced the oxidation rate by 25 to 40% at temperatures ranging from 700 to 800C. The oxide which formed at these temperatures was SO2 while, at 600C, there was a transition from SO2 to mixed-oxide growth at some point in the very early stages of oxidation. This depended upon the alloy composition.

S.J.Kilpatrick, R.J.Jaccodine, P.E.Thompson: Journal of Applied Physics, 1997, 81[12], 8018-28