A semiconductor device, such as a positive channel metal-oxide semiconductor (PMOS) transistor, and a fabricating method thereof are provided. The semiconductor device includes: a gate insulation layer and a gate electrode, a semiconductor substrate, a spacer formed on side walls of the gate insulation layer and the gate electrode, a lightly doped drain (LDD) area formed on the semiconductor substrate at both sides of the gate electrode, a source/drain area formed on the semiconductor substrate at both sides of the gate electrode, and an oxide-nitride layer formed on the gate electrode and on the source/drain area.