Semiconductor device having a silicide layer and manufacturing method thereof

A method of manufacturing a semiconductor device, the method comprising:

• forming a thin film transistor comprising a substrate having a semiconductor layer and silicon, a gate insulation layer formed on the semiconductor layer, a gate electrode formed on the gate insulation layer, and source and drain regions formed in the semiconductor layer;
• forming a first metal layer on the substrate having the semiconductor layer and the gate electrode;
• forming a second metal layer on the first metal layer, the second metal layer is formed of a metal different from that of the first metal layer, the second metal layer formed thinner than the first metal layer;
• forming a third metal layer on the second metal layer;
• forming a nitride layer on the third metal layer;
• and
• annealing the substrate having the nitride layer, and forming a silicide layer on the gate electrode and the source and drain regions.