(Invited) Degradation in MOSFET Multistack High-k Gate Dielectrics Due to Hot Carrier and Constant Voltage Stress

Abstract

Hafnium based materials are the leading high dielectric constant (high-k) candidates to replace conventional SiO2 and SiON as the gate dielectric in complementary metal-oxide-semiconductor (CMOS) devices for sub-45nm technology nodes. To explain the low frequency noise behavior in these gate dielectrics, a new model is required that can take care of various material properties and new structures. In this paper, a new low frequency noise model for high-k gate materials as well as various stress-induced noise degradation are presented. The additional, stress-induced low-frequency noise was evaluated on nMOSFETs with TiN metal gate and HfSiON gate dielectric. Nitridation of HfSiO was achieved either by high temperature thermal nitridation or by relatively lower temperature plasma nitridation. The difference in stress-induced noise behavior is attributed to the nitrogen profile across the gate dielectric/Si interface and the bulk of the high-k gate oxide caused by different nitridation techniques.