A semiconductor device is provided that includes an insulated gate field effect transistor series connected with a FET having several parallel conductive layers, a substrate of first conductivity type extending under both transistors, and a first layer of a second conductivity type overlies the substrate. Above this first layer are several conductive layers with channels formed by several of the first conductivity type doped epitaxial layers with layers of a first conductivity type on both sides. The uppermost layer of the device may be substantially thicker than the directly underlying parallel conductive layers. The JFET is isolated with deep poly trenches of second conductivity type on the source side. The insulated gate field effect transistor is isolated with deep poly trenches of the first conductivity type on both sides. A further isolated region is isolated with deep poly trenches of the first conductivity type on both sides.