Positive bias temperature instability effects of Hf-based nMOSFETs with various nitrogen and silicon profiles

Abstract

Positive bias temperature instability (PBTI) effects of HfO/sub 2/-based nMOSFETs with various nitrogen profiles in HfO/sub 2/ were investigated. The nitrogen profile was modulated by an inserting Si layer (/spl sim/6/spl Aring/) into hafnium oxynitride gate dielectrics. The Si layer is used to trap nitrogen and to suppress nitrogen out-diffusion during subsequent anneals. Compared to control HfO/sub x/N/sub y/ without Si insertion, the Si-inserted HfO/sub x/N/sub y/ samples exhibited reduced PBTI degradation, especially if the Si layer was placed further from the Si interface. The improvement can be attributed to the reduction of oxide bulk trapped as well as reduced interface trapped charge generation resulting from compensation effect of inserted Si layer.