Superjunction LDMOS with drift region charge-balanced by distributed hexagon p-islands

A new device structure suitable for practical implementation of silicon superjunction LDMOS is proposed. With hexagonal p-islands distributed in the drift region of a conventional LDMOS (SJ-HexLDMOS), the tradeoff between breakdown voltage (BV/sub dss/) and specific on resistance (R/sub on,sp/) can be improved. Maximum efficiency in depleting the drift region upon reverse bias can be achieved when those p-islands are arranged in a honeycomb shape. As the lateral superjunction layer gets thinner, the combined effect of superjunction and RESURF makes the optimization more complicated and the benefit of the SJ-structure is compromised.