Improved performance of ultra-thin HfO/sub 2/ CMOSFETs using poly-SiGe gate

Poly-SiGe is investigated as the gate material for CMOS transistors with ultra-thin HfO/sub 2/ gate dielectric. Compared with poly-Si, poly-SiGe reduces the gate depletion effect, and also results in thinner EOT of the gate dielectric after 1000/spl deg/C annealing, with low gate leakage maintained. The Si interface quality is also better than that achieved with surface nitridation, which has been used to reduce EOT. Therefore, the use of poly-SiGe as the gate material is effective for improving the performance of ultra-thin HfO/sub 2/ CMOS transistors.