Work function controlled metal gate electrode on ultrathin gate insulators

We investigated MOS characteristics of metal gate electrodes on ultrathin gate oxide. Gate leakage currents of sputtered TiN and WN/sub x/ electrodes were found to be much higher than that of CVD TiN electrodes due to metal penetration during sputtering. Moreover, the deviation of crystal orientation of the TiN was found to affect the flat band voltage. The CVD TiN film was found to be formed with highly preferred orientation and to show very stable MOS characteristics, even on 2 nm gate oxide.