Impact of Thin-oxide Gate on the On-Resistance of HV-PNP Under ESD Stress

Physical insights into the impact of the thin-oxide polysilicon gate on the on-resistance of DeMOS-based HV-PNP are developed using detailed TCAD simulation. Turn-on and eventual failure mechanisms in HV-PNP are discussed. The impact of thin-oxide polysilicon placed over the N-Well and P-Well regions is investigated separately. The physics of regenerative bipolar degradation and its effect of dynamic on-resistance is understood as a function of thin-oxide placement. Furthermore, floating the thin-oxide gate mitigated regenerative bipolar degradation while having a faster lateral PNP trigger, resulting in the best case of on-resistance at all current levels. The insights developed in this work help to design compact high-voltage PNPs.