Abnormal Relationship Between Hot Carrier Stress Degradation and Body Current in High-k Metal Gate in the 14-nm Node

Abstract

This letter discusses the hot carrier stress (HCS) degradation mechanisms for different gate voltages ( $\text{V}_{\textsf {G}}$ ) in FinFET devices, and finds the abnormal relationship between HCS degradation and body current under high $\text{V}_{\textsf {G}}$ . According to the distributions of lifetime ( ${\tau }$ )- $\text{I}_{\textsf {B}}$ and ${\tau }$ -drain current ( $\text{I}_{\textsf {D}}$ ), it is found that the ${\tau }$ under the high $\text{V}_{\textsf {G}}$ is related to the $\text{I}_{\textsf {D}}$ instead of the $\text{I}_{\textsf {B}}$ . In addition, as the $\text{V}_{\textsf {G}}$ increases from low to middle to high values, the HCS degradation mechanism exhibits single vibrational excitation, electron-electron scattering, and multiple vibrational excitation (MVE) models, respectively. Therefore, the HCS degradation mechanism at higher $\text{V}_{\textsf {G}}$ is not dominated by the traditional impact ionization but by the carrier concentration of the channel. Finally, according to the results of fitting MVE model, the reason for breaking the Si-H bonds to form dangling bonds is the bending vibrational mode.