p-Channel Hot-Carrier Optimization of RNO Gate Dielectrics Through the Reoxidation Step

The effects of reoxidation conditions on the hot-carrier properties of reoxidized nitrided oxides (RNO's) for both n-and p-MOS transistors are examined. Using a recently developed lifetime extraction technique for p-MOS transistors, it is shown that the reoxidation conditions for the RNO dielectric involve a compromise between n-channel hot-carrier hardness and p-channel hot-carrier susceptibility. Whereas the n-MOS transistor lifetimes are relatively unchanged as a function of reoxidation time, the p-MOS devices show monotonic increases with increased reoxidation time. This is attributed to changes of nitrogen concentration in the bulk of the oxide, but not at the interface. It is concluded that attention will have to be paid to the p-channel transistor reliability when optimizing the RNO process.