Plasma process induced damages on n-MOSFET with plasma oxidized and nitrided gate dielectrics

Abstract

The material and electrical properties of a 30 A-thick gate oxide, which is fabricated using plasma oxidation and subsequently nitrided in N-2 plasma, are investigated. Before plasma nitridation, the chemical bonding states and gate oxide integrity characteristics of the plasma oxidized (PO) gate are nearly the same as these of the wet oxidized (WO) gate. The plasma nitridation reduces the bandgap of the gate dielectric and increases the gate leakage current. The gate dielectric with a reduced bandgap provides a discharge path for the charging current from processing plasma and decreases the plasma process-induced damage. The immunity of the gate dielectric to hot carrier effects is improved with plasma nitridation even at a very high antenna ratio. Although both the PO and WO gates show a similar immunity to hot carrier stress after plasma nitridation, the immunity to a constant voltage stress is better on the plasma nitrided WO gate. (C) 2004 Elsevier B.V. All rights reserved.