The present disclosure provides a semiconductor structure, including a sensing substrate, a capping substrate over the sensing substrate, the capping substrate having a first surface facing toward the sensing substrate and a second surface facing away from the sensing substrate, wherein the capping substrate comprises a through hole extending from the first surface to the second surface, a spacer between the sensing substrate and the capping substrate, the spacer, the sensing substrate, and the capping substrate forming a cavity connecting with the through hole, and a sealing structure at the second surface and aligning with the through hole, wherein the sealing structure comprises a metal layer and a dielectric layer.