Patent ID: 8836017

Claim:
A semiconductor device, comprising: a plurality of first epitaxial layers stacked on a substrate, wherein the plurality of first epitaxial layers and the substrate have a first conductivity type, each of first epitaxial layer comprises at least one first doping region and at least one second doping region adjacent thereto, the first doping region has a second conductivity, and the second doping region has the first conductivity type; a second epitaxial layer disposed on the plurality of first epitaxial layers, having the first conductivity type, wherein the second epitaxial layer has a trench therein to expose the first doping region thereunder; a third doping region adjacent to a sidewall of the trench, having the second conductivity type, wherein the second epitaxial layer and the first, second and third doping regions have a doping concentration greater than that of each first epitaxial layer; and a gate structure disposed on the second epitaxial layer above the second doping region.