Cold and hot carrier effects on HfO/sub 2/ and HfSiO NMOSFETS with tin gate electrode

Abstract

Introduction Hafnium based high-k dielectrics and metal gate electrodes have been aggressively investigated in order to ensure continued scaling ofCMOS technology. Well known limitations of high-k dielectric devices such as low mobility, charge trapping, interfacial oxide quality have been improved significantly and will no longer be a show stopper for the implementation in 45nm node [1-4]. However, reliability characteristics of high-k dielectrics have not been fully understood yet. Since the transient charging effect, which is generally not observed in SiO2, complicates evaluation of the properties of high-k gate stacks [5-10]. Hot carrier effects of the high-k gate dielectrics should be investigated considering the effect from cold carriers [1114]. Even though the contribution of cold carrier are not separable from that of hot carrier during channel hot carrier stress, the reversibility of cold carrier effects can be carefully examined to differentiate the effect of cold carrier from hot carrier induced damage on the device, which is assumed to be permanent. In this paper, we investigate the effect of cold carrier and hot carrier on the HfO2 and HfSiO NMOSFETs transistor devices.