Negative Bias Temperature Instability of p-Channel Metal Oxide Semiconductor Field Effect Transistor with Novel Hf_xMo_yN_z Metal Gate Electrodes

Abstract

The negative bias temperature instability (NBTI) characteristics of p-channel metal oxide semiconductor field effect transistor (pMOSFET) devices with novel Hf x Mo y N z metal gates have been investigated for the first time. The threshold voltage (V th ) shift, subthreshold swing (SS), off-leakage current, and field effect mobility ( FE ) were found to be degraded after NBTI stress. The possibility of nitrogen diffusing to the oxide is increased by employing a higher N 2 ratio during Hf x Mo y N z deposition. The higher nitrogen content in Hf x Mo y N z metal gates shows threshold voltage (V th ) shift, subthreshold swing (SS), off-leakage current, and field effect mobility ( FE ) degradation. The degradation of threshold voltage (V th ), subthreshold swing (SS), off-leakage current, and field effect mobility ( FE ) are believed to be due to the interface states and fixed oxide charges generation from the broken Si-H bonds at the SiO 2 /Si interface. Furthermore, the mechanism of NBTI degradation has been suggested by a physical model and an energy band diagram.

Effects of a HfMoN Metal Gate and Self-Aligned Fluorine-Ion Implantation on the Negative-Bias Temperature Instability of pMOSFETs With $\hbox{Gd}_{2} \hbox{O}_{3}$ Gate Dielectrics

“…The accumulation of nitrogen at the high-k/Si interface enhances the NBTI. In a previous study [9], the enhanced NBTI in a HfMoN/SiO 2 pMOSFET was attributed to nitrogen diffusion in SiO 2 . Similarly, we deduce that, in our samples, the nitrogen diffused into either the bulk Gd 2 O 3 or the Gd 2 O 3 /Si interface and subsequently enhanced the NBTI.…”