In a method of manufacturing a semiconductor device, a gate insulating film is formed at a first surface of a first semiconductor layer of a first conductivity type; a second semiconductor layer of a second conductivity type is formed at the first surface; a gate electrode is formed on the gate insulating film; the gate insulating film is selectively removed; a thermal oxide film is formed at a surface of the second semiconductor layer; a third semiconductor layer of the first conductivity type is selectively formed at the surface of the second semiconductor layer; an interlayer insulating film is formed on the thermal oxide film; a contact hole is selectively formed to expose the third semiconductor layer; a barrier metal is formed in the contact hole; and a metal plug is embedded in the contact hole on barrier metal by a CVD method that uses a metal halide.