Improved NBTI in SiN-capped PMOSFETs with ultra-thin HfO2 buffer

Abstract

Although a compressive SiN capping could effectively boost the drive current of PMOS devices, it may concomitantly worsen the NBTI characteristics owing to the high hydrogen content in the SiN layer which might diffuse to the channel region during processing. To address this issue, inserting a thin 3nm HfO2 buffer layer between the gate and SiN capping is proposed and demonstrated to improve NBTI reliability without sacrificing the performance enhancement by SiN capping.