Abstract: A trenched power semiconductor device on a lightly doped substrate is provided. The device has a base, a plurality of trenches including at least a gate trench, a plurality of first heavily doping regions, a body region, a source doped region, a contact window, a second heavily doped region, and a metal layer. The trenches are formed in the base. The first heavily doped regions are beneath the trenches respectively and spaced from the bottom of the respective trench with a lightly doped region. The body region encircles the trenches and is away from the first heavily doped region with a predetermined distance. The source doped region is in an upper portion of the body region. The contact window is adjacent to the edge of the base. The second heavily doped region is below the contact window filled by the metal layer for electrically connecting the second heavily doped region.