The Impact of Hot Carrier Injection-Induced Device Degradation for Lower-Power FinFETs

The impact of hot carrier injection (HCI) on the performance of standard and low-V_T FinFETs are investigated and benchmarked with each other. For this investigation, these FinFETs were fabricated with various gate lengths (L) from 16 to 36 nm. HCI-induced transconductance degradation in standard devices for gate length variations of 36 nm down to 16 nm was 75%, while it was 35% for low-V_T devices. Similarly, the degradation of threshold voltage in standard devices for gate length variations of 36 nm down to 16 nm was 39%, while it was 36% for low-V_T device. In this work, as the device is subject to HCI, we found that: (1) short-channel devices cause severe degradation on the threshold voltage and transconductance (g_m) compared to long-channel devices, owing to the higher electric field for short-channel devices at the gate edge, (2) standard devices exhibit a more stable threshold voltage than that of low-V_T power devices, since the TiN barrier layer prevents Al atom diffusion into the HfO₂ layer, and (3) the transconductance efficiency of standard devices is better than that of low-V_T power devices. Further, the lower-V_T devices show lower transconductance degradation than standard devices. However, the transconductance degradation of the long-channel standard and low-V_T devices are the same. Compared to short-channel low-V_T devices, extended-channel standard devices are more immune to the HCI effect.