The present invention relates to a semiconductor device and a semiconductor package having the same. The semiconductor device includes a semiconductor substrate, a backside dielectric layer, a plurality of first backside under ball metal (UBM) pads and a first backside UBM plane. The backside dielectric layer is disposed adjacent to a backside surface of the semiconductor substrate. The first backside UBM pads are disposed on the backside dielectric layer. The first backside UBM plane is disposed on the backside dielectric layer, and has a plurality of through holes. The first backside UBM pads are located within the through holes, and a gap is between the first backside UBM plane and the first backside UBM pads. Whereby, the cost for forming the first backside UBM pads and the first backside UBM plane is relatively low.