A power MOSFET device includes at least one MOSFET unit disposed over a substrate, wherein the MOSFET unit includes a plurality of cells and a boundary surrounding the cells. In one embodiment of the present invention, the cell is configured to provide a unit current, and comprises at least one source pillar and at least one drain pillar, a gate conductor surrounding the source pillar and the drain pillar, and an insulating structure electrically separating the gate conductor from the source pillar and the drain pillar, wherein the gate conductor extends from the cell to the boundary.