Hot-carrier-induced on-resistance degradation of step gate oxide NLDMOS

The hot-carrier-induced on-resistance degradations of step gate oxide NLDMOS (SG-NLDMOS) transistors are investigated in detail by a DC voltage stress experiment,a TCAD simulation and a charge pumping test.For different stress conditions,degradation behaviors of SG-NLDMOS transistors are analyzed and degradation mechanisms are presented.Then the effect of various doses of n-type drain drift (NDD) region implant on Ron degradation is investigated.Experimental results show that a lower NDD dosage can reduce the hot-carrier induced Ron degradation effectively,which is different from uniform gate oxide NLDMOS (UG-NLDMOS) transistors.