SiGe amorphization during Ge condensation in silicon germanium on insulator

High temperature oxidation and annealing are found to be desirable to achieve a uniform germanium (Ge) profile in silicon germanium on insulator (SGOI) layers formed using germanium condensation technique. This work investigates the amorphization mechanism, which was considered as an undesirable consequence of lowering the temperature during Ge condensation when oxidations are conducted at 900 or 950 degrees C. A dual layer SGOI stack, composed of an amorphous layer above a crystalline layer, was obtained at low temperature condensation as characterized using transmission electron microscope and Auger analysis. A possible mechanism is presented. Si0.4Ge0.6OI and Si0.25Ge0.75OI layers can be achieved without amorphization through oxidation/annealing at 1050 degrees C and two oxidations at 1050 and 1000 degrees C, respectively.