A semiconductor device includes a first and a second active regions having a first conductive type and a second conductive type, respectively, being arranged in a first direction; a gate extending in the first direction; a first and a second channel regions defined under the gate in the first and the active regions, respectively; a first low-concentration doped region, having the second conductive type, formed at sides of the gate in the first active region and a first high-concentration doped region, having the second conductive type, formed at sides of the first low-concentration doped region in the first active region; and a second low-concentration doped region, having the first conductive type, formed at sides of the gate in the second active region and a second high-concentration doped region, having the first conductive type, formed at sides of the second low-concentration doped region in the second active region.