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

Abstract

For thin oxides grown on high temperature formed Si0.3Ge0.7, the gate oxide quality is strongly dependent on oxide thickness and improves as thickness reduces from 50 to 30 Angstrom. The thinner 30 Angstrom 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 Si0.3Ge0.7 that is strain relaxed and stable during oxidation, The possible reason for strong thickness dependence may be due to the lower GeO2 content formed in thinner 30 Angstrom oxide rather than strain relaxation related rough surface or defects.