Analysis of Contrasting Degradation Behaviors in Channel and Drift Regions Under Hot Carrier Stress in PDSOI LD N-Channel MOSFETs

This letter studies the effects of hot carrier stress (HCS) in laterally diffused silicon-on-insulator n-channel metal-oxide-semiconductor field-effect transistors. After HCS, threshold voltage and subthreshold swing degrade, while the ON-state current exhibits degradation after an abnormal spike due to hole trapping in the resist-protective oxide. Impact ionization simulation shows that low doping concentrations in the drift region cause a severe Kirk effect under HCS and more severe degradation at higher gate voltages. However, degradation in the channel contrasts with the simulation result, which suggests an additional mechanism. Variable temperature HCS confirms that channel degradation is instead dominated by temperature.