Effect of Plasma Nitridation on Hot-Carrier Instability and Low-Frequency Noise in Gd-Doped High- Dielectric nMOSFETs

摘要

The effects of post-$hbox{NH}_{3}$ plasma nitridation on device's hot-carrier instability and low-frequency noise in the Hf-based high-$ kappa$/metal-gate n-channel metal–oxide–semiconductor field-effect transistors (nMOSFETs) with gadolinium (Gd) cap layers are investigated. With postnitridation, the direct-current and $hbox{1}/f$ noise characteristics can be improved apparently. Moreover, a hot-carrier stressing-induced threshold voltage shift can be also suppressed despite of a similar transconductance degradation when comparing with that in the device without nitridation. With the charge-pumping and low-frequency noise measurements, we find that the bulk- and interfacial-trap densities can be reduced with nitrogen incorporation. The reduction of bulk and interfacial traps can be contributed to the suppression of Gd diffusion into a high-$kappa$ layer. In this paper, appropriate post- $hbox{NH}_{3}$ plasma nitridation can improve the device performance and reliability and low-frequency noise for a gate-first high-$ kappa$/metal-gate nMOSFET with a Gd cap layer.