Patent ID: 7576391

Claim:
A lateral trench DMOS device formed in a semiconductor substrate of a first conductivity type, the substrate not comprising an epitaxial layer, the device comprising: a dielectric layer formed at a surface of the substrate, the dielectric layer having first and second openings; a trench formed in the substrate, the trench extending downward from the surface of the substrate directly below the first opening in the dielectric layer, the trench containing a gate and a gate dielectric layer; a body region of the first conductivity type formed adjacent the trench; a source region of a second conductivity formed adjacent the surface of the substrate and the trench; a drain region of the second conductivity type formed adjacent the surface of the substrate below the second opening in the dielectric layer, the drain region comprising a drain contact region, an upper dopant region and a lower dopant region, the drain contact region being located at the surface of the substrate directly above the upper dopant region viewed at a vertical centerline of the drain region, the upper dopant region being located directly above the lower dopant region viewed at the vertical centerline of the drain region, the drain contact region having a peak doping concentration greater than a peak doping concentration of either the upper dopant region or the lower dopant region, the lower dopant region having a peak doping concentration greater than a peak doping concentration of the upper dopant region; and a conformal drift region of the second conductivity type abutting the trench, the body region and the drain region, the drift region having a doping concentration that is less than a doping concentration of the drain region, the drift region comprising first and second deep portions located directly below the first and second openings in the dielectric layer, respectively, and a shallow portion located directly below the dielectric layer, the deep portions extending deeper into the substrate than the shallow portion.