Ultra-Dry Oxidation for Improving the Time-Dependent Dielectric Breakdown Lifetime of Ultra-Thin Silicon Oxide Films

Abstract
Time-dependent dielectric breakdown lifetime of 5-nm-thick silicon oxide films oxidized in an ultra-dry oxygen gas of less than 1-ppm moisture concentration was investigated. The lifetime for the ultra-dry films was larger than that for the conventional films oxidized in more than 100-ppm humidity. In particular, a pronounced improvement can be confirmed in the case when a silicon substrate is an anode. Since stress-induced positive charges, which affect the lifetime, are mainly generated near the anode-side oxide interfaces, the oxide-silicon interface conditions are probably improved by the ultra-dry oxidation.