Hot carrier instability associated with hot carrier injection and charge injection in In_0.7Ga_0.3As MOSFETs with high-κ stacks

Abstract

Channel hot carrier (CHC) reliability in In 0.7 Ga 0.3 As nMOSFETs with Al 2 O 3 /HfO 2 (EOT = 0.8 nm) during CHC stress has been studied in scaleddown gate devices. The threshold voltage degradation (ΔV T ) during CHC stress was attributed to the hot carrier injection into Al 2 O 3 or/and HfO 2 defect sites, rather than charge trapping into high-κ bulk defects. Additionally, with an increase of gate voltage at a fixed drain voltage (V DS ), there was an increase in probability that the InGaAs channel carriers are easily injected into Al 2 O 3 or/and HfO 2 defect sites, causing the worst ΔV T degradation at the same V GS = V DS stress condition. Hence, hot carrier injection during CHC stress was divided into two components: charge injection by the vertical field near the source region and injection of hot carriers into the oxide bulk defects at the drain corner. To decouple the charge trapping and hot carrier injection into the gate oxide defect sites during CHC stress, an unrecovered (hot carrier damage) and recovery ratio (charge injection) of the ΔV T degradation after relaxation and opposite polarity voltage were calculated to be about ∼70% and ∼30%, respectively. Therefore, hot carrier injection has emerged as a dominant degradation factor in InGaAs MOSFETs with high-κ dielectrics.