Power semiconductor device having guard ring structure, and method of formation

A power semiconductor device, comprising:

• a semiconductor substrate, wherein the semiconductor substrate comprises an active device region and a junction termination region;
• and
• a polysilicon layer, disposed over the semiconductor substrate, wherein the polysilicon layer comprises:
• an active device portion, disposed over the active device region, and defining at least one semiconductor device;
• and
• a junction termination portion, disposed over the junction termination region, the junction termination portion defining a polysilicon ring structure, wherein the junction termination region comprises a plurality of well structures, wherein
• at least one well structure of the plurality of well structures comprises:
• a first doped region, having a relatively higher dopant concentration of a dopant of a first type, and extending into the semiconductor substrate to a relatively greater depth;
• and a second doped region, having a relatively lower dopant concentration of the dopant of the first type, and extending into the semiconductor substrate to a relatively lesser depth than the first region.