A semiconductor device comprises a substrate, a first semiconductor unit on the substrate, and an first adhesion structure between the substrate and the first semiconductor unit, and directly contacting the first semiconductor unit and the substrate, wherein the first adhesion structure comprises an adhesion layer and a sacrificial layer, and the adhesion layer and the sacrificial layer are made of different materials, and wherein an adhesion between the first semiconductor unit and the adhesion layer is different from that between the first semiconductor unit and the sacrificial layer.