A semiconductor device includes first well regions in a substrate and spaced apart from each other, a connection doped region between the first well regions, and a first interconnection line electrically connected to the connection doped region through a first contact. The first well regions and the connection doped region include impurities of a first conductivity type, and a concentration of the impurities in the connection doped region is higher than that in the first well regions. The first well regions extend into the substrate to a depth larger than that of the connection doped region. A first portion of the connection doped region is disposed in the first well regions and a second portion of the connection doped region contacts the substrate.