Semiconductor devices for high voltage application are presented. A high power semiconductor device includes a first type doped semiconductor substrate and a second type doped epitaxial layer deposited thereon. A first type doped body region is disposed in the second type doped epitaxial layer. A heavily doped drain region is formed in the second type doped epitaxial layer and isolated from the first type doped body region with an isolation region and a channel. A second type deep heavily doped region extends from the heavily doped drain region to the semiconductor substrate. A pair of inversed type heavily doped source regions is disposed in the first type doped body region. A gate electrode is disposed overlying the channel with a dielectric layer interposed therebetween. The high power semiconductor device is isolated from the other semiconductor devices with a first type deep heavily doped region.