A method of manufacturing a semiconductor device, the method including providing a substrate, the substrate including single crystalline silicon and having the first region and a second region; growing a pillar from a top surface of the substrate in the first region; forming a vertical channel transistor including a first gate structure such that first gate structure surrounds a central portion of the pillar; and forming a second transistor on the second region of the substrate such that the second transistor includes a second gate structure.