According to an embodiment of a semiconductor device, the semiconductor device includes a power device well in a semiconductor substrate, a logic device well in the substrate and spaced apart from the power device well by a separation region of the substrate, and a minority carrier conversion structure including a first doped region of a first conductivity type in the separation region, a second doped region of a second conductivity type in the separation region and a conducting layer connecting the first and second doped regions. The second doped region includes a first part interposed between the first doped region and the power device well and a second part interposed between the first doped region and the logic device well.