Double-resurf ldmos with drift and psurf implants self-aligned to a stacked gate 'bump' structure

Abstract

A double-RESURF LDMOS transistor has a gate dielectric structure including a shallow field 'bump' oxide region and an optional raised dielectric structure that provides a raised support for the LDMOS transistor's polysilicon gate electrode. Fabrication of the shallow field oxide region is performed through a hard 'bump' mask and controlled such that the bump oxide extends a minimal depth into the LDMOS transistor's drift (channel) region. The hard “bump” mask is also utilized to produce an N-type drift (N-drift) implant region and a P-type surface effect (P-surf) implant region, whereby these implants are “self-aligned” to the gate dielectric structure. The N-drift implant is maintained at Vdd by connection to the LDMOS transistor's drain diffusion. An additional Boron implant is utilized to form a P-type buried layer that connects the P-surf implant to the P-body region of the LDMOS transistor, whereby the P-surf implant is maintained at 0V.