A semiconductor device, particularly, a method for manufacturing a high voltage semiconductor device is disclosed. The method includes forming a high voltage gate oxide film on a semiconductor substrate having a high voltage device region and a low voltage device region, forming a gate electrode on the semiconductor substrate having the high voltage gate oxide film, forming a fluorinated silicate glass (FSG) film and a liner film sequentially on an entire surface of the semiconductor substrate including the gate electrode, and forming an interlayer insulating film on the liner film. Thus, it is possible to prevent an increase in leakage current of the high voltage semiconductor device such as a MOS transistor.