A semiconductor structure includes a first substrate, a second substrate, a dam layer, a photoresist layer, and a conductive layer. The first substrate has a conductive pad. The second substrate has a through via, a sidewall surface surrounding the through via, a first surface, and a second surface opposite to the first surface. The through via penetrates through the first and second surfaces. The conductive pad is aligned with the through via. The dam layer is located between the first substrate and the second surface. The dam layer protrudes toward the through via. The photoresist layer is located on the first surface, the sidewall surface, the dam layer protruding toward the through via, and between the conductive pad and the dam layer protruding toward the through via. The conductive layer is located on the photoresist layer and the conductive pad.