A semiconductor device includes a semiconductor substrate and a pair of first well regions formed in the semiconductor substrate, wherein the pair of first well regions have a first conductivity type and are separated by at least one portion of the semiconductor substrate. The semiconductor device also includes a first doping region formed in a portion of at least one portion of the semiconductor substrate separating the pair of first well regions, and a pair of second doping regions, respectively formed in one of the pair of first well regions, having the first conductivity type. Further, the semiconductor device includes a pair of insulating layers, respectively formed over a portion of the semiconductor substrate to cover a portion of the first doped region and one of the pair of second doping regions.