Hybrid Junction Termination Consisting of a Variation Lateral Doping Structure and a Spiral Polysilicon Resistive Field Plate

Abstract

A hybrid junction termination structure consisting of a variation lateral doping (VLD) region and a spiral polysilicon resistive field plate (PRFP) is proposed in this brief. Surface electric fields of the VLD region are modulated by the PRFP and distribute more uniformly. Compared with the conventional VLD structure with the same size, its measured breakdown voltage increases by 11%. The breakdown voltage still has a positive temperature coefficient. And, the leakage current changes very little from −40 to 150 °C. Besides, it is more immune to the deviation of the VLD dosage. The deviation range of the VLD dosage increase from −20% - +20% to −50% - +60% when the breakdown voltage keeps above 90% of the maximum value. No extra masks or process steps are needed in power devices with a MOS gate structure, because the gate layer can be used to implement the spiral PRFP. At last, the hybrid termination is not detrimental to the switching characteristic of the device.