Thickness dependent gate oxide quality of thin thermal oxide grown on high temperature formed SiGe

For thin oxides grown on high temperature formed Si/sub 0.3/Ge/sub 0.7/, the gate oxide quality is strongly dependent on oxide thickness and improves as thickness reduces from 50 to 30 /spl Aring/. The thinner 30 /spl Aring/ oxide has excellent quality as evidenced by the comparable leakage current, breakdown voltage, interface-trap density and charge-to-breakdown with conventional thermal oxide grown on Si. The achieved good oxide quality is due to the high temperature formed Si/sub 0.3/Ge/sub 0.7/ that is strain relaxed and stable during oxidation. The possible reason for strong thickness dependence may be due to the lower GeO/sub 2/ content formed in thinner 30 /spl Aring/ oxide rather than strain relaxation related rough surface or defects.