Improved Degradation and Recovery Characteristics of SiGe p-Channel Metal–Oxide–Semiconductor Field-Effect Transistors under Negative-Bias Temperature Stress

Abstract

This paper describes the degradation and recovery characteristics of SiGe pMOSFETs with a high-k/metal gate stack under negative-bias temperature instability (NBTI) stress. The threshold voltage instability (ΔVth) of SiGe pMOSFETs shows an increased percentage of recovery (R) as well as lower degradation than those of control Si pMOSFETs. It is found that the recovery characteristics of SiGe and Si pMOSFETs have similar dependencies on various stress conditions, and the increased R of SiGe pMOSFETs is mainly attributed to their lower degradation characteristic. Under real operating conditions, most of the ΔVth caused by hole trapping would be rapidly recovered through a fast recovery process, and newly-generated interface traps during the stress would determine the degradation level of Vth. The SiGe pMOSFETs show lower stress-induced interface traps; thus, they would display more reliable NBTI characteristics than Si pMOSFETs under real operating conditions.