US Patent 7449387 MOS transistor and method of manufacturing the same

A manufacturing method of a double LDD MOS transistor includes forming a gate electrode on a semiconductor substrate; forming a first LDD area by implanting and thermally annealing impurity ions using the gate electrode as a mask; forming a first spacer on both lateral walls of the gate electrode; forming a second LDD area by implanting and thermally annealing impurity ions using the gate electrode and the first spacer as a mask; forming a second spacer on both lateral walls of the gate electrode and the first spacer; and forming a source-drain diffusion area by implanting and thermally annealing impurity ions using the gate electrode, the first spacer, and the second spacer as a mask.