US Patent 7439120 Method for fabricating stress enhanced MOS circuits

A stress enhanced MOS circuit and methods for its fabrication are provided. The stress enhanced MOS circuit comprises a semiconductor substrate and a gate insulator overlying the semiconductor substrate. A gate electrode overlies the gate insulator; the gate electrode has side walls and comprising a layer of polycrystalline silicon having a first thickness in contact with the gate insulator and a layer of electrically conductive stressed material having a second thickness greater than the first thickness overlying the layer of polycrystalline silicon. A stress liner overlies the side walls of the gate electrode.