| A semiconductor device includes a substrate and units. Each unit includes a drift layer, a fin, a first, second, and third doped region, and a first gate structure. The drift layer is located on a first surface of the substrate. The fin is located on a first surface of the drift layer. The first doped region is located in the fin and extends from a top surface of the fin toward the drift layer. The second doped region is located in the substrate and extends from a second surface of the substrate toward the first surface of the substrate. The third doped region is located in the drift layer and extends from the first surface of the drift layer toward a second surface of the drift layer. The first gate structure is between the first and third doped regions and extends to the first surface of the drift layer. |