A semiconductor structure is provided and includes: a substrate, containing first doping ions and including a photosensitive region and a floating diffusion region; a deeply doped region, in the photosensitive region of the substrate and containing second doping ions; a floating diffusion area, in the floating diffusion region of the substrate and containing third doping ions; a gate structure on the substrate at a junction of the photosensitive region and the floating diffusion region; a sidewall spacer on the photosensitive region of the substrate, and on sidewalls and top of the gate structure in the photosensitive region; a first doped region located in the floating diffusion area and having fourth doping ions; a metal connection layer on the first doped region; an interlayer dielectric layer on the substrate exposed by the gate structure; and a contact plug, in the interlayer dielectric layer and electrically connected to the metal connection layer.