Robust high-quality HfN-HfO/sub 2/ gate stack for advanced MOS device applications

In this letter, a thermally stable and high-quality HfN-HfO/sub 2/ gate stack for advanced MOS applications is reported for the first time. Negligible changes in both equivalent oxide thickness (EOT) and work function of HfN-HfO/sub 2/ gate stack are demonstrated even after 1000/spl deg/C postmetal annealing (PMA), which is attributed to the superior oxygen diffusion barrier property of HfN as well as the thermal stability of the HfN-HfO/sub 2/ interface. Therefore, even without surface nitridation prior to HfO/sub 2/ deposition, the EOT of HfN-HfO/sub 2/ gate stack can be successfully scaled down to less than 10 /spl Aring/ after 1000/spl deg/C PMA with excellent leakage and long-term reliability.