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

This letter discusses the hot carrier stress (HCS) degradation mechanisms for different gate voltages (V-G) in FinFET devices, and finds the abnormal relationship between HCS degradation and body current under high V-G. According to the distributions of lifetime (tau)-I-B and tau-drain current (ID), it is found that the tau under the high V-G is related to the I-D instead of the I-B. In addition, as the V-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 V-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.