A semiconductor structure includes a semiconductor substrate, a buried layer, a pair of first well regions, a second well region, a body doped region, and a first heavily doped region. The semiconductor substrate has a first conductivity type. The buried layer is disposed on the semiconductor substrate. The first well regions having the second conductivity type are disposed on the buried layer. The second well region having the first conductivity type is disposed between the first well regions. The body doped region having the first conductivity type is disposed in the second well region. The first heavily doped region having the first conductivity type is disposed in the body doped region. From a top view, the first heavily doped region and the first well regions extend in a first direction, and the first heavily doped region extends beyond the opposite edges of the first well regions.