NBTI degradation in STI-based LDMOSFETs

NBTI degradation in STI-based LDMOSFETs has been investigated by multi-region DCIV spectroscopy (MR-DCIV), a non-destructive and sensitive method to probe the interface states on channel, accumulation and STI region. A unified MR-DCIV current model was proposed based on its independency to the forward bias and temperature. Under the same negative gate stress condition, MR-DCIV current degradation was compared for nLDMOSFET and pLDMOSFET. Much larger MR-DCIV current shift was observed at channel and accumulation region with thin gate oxide thickness, indicating interface states generation at related regions. Our results show that more significant degradation for multi-finger device was consistent with NBTI degradation mechanism. High voltage device design with thermal management consideration is of crucial importance to guaranteeing the device performance and reliability.