| A semiconductor device includes a substrate and a plurality of units. Each unit includes drift layer, a fin, a first doped region, a second doped region, a 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 to 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 to a second surface of the drift layer. The first gate structure is disposed between the first doped region and the third doped region, on a first lower sidewall of the fin and extending to the first surface of the drift layer. |