A semiconductor structure includes: a base including a substrate and a dielectric layer, herein the substrate having a front surface and a back surface that are oppositely arranged, and the dielectric layer is located on the front surface; a connecting hole penetrating the substrate and extending to the dielectric layer; a connecting structure, located in the connecting hole; and an insulating structure, located between the connecting structure and the inner wall of the connecting hole. The insulating structure, the inner wall of the connecting hole, and the connecting structure define an air gap.