Physical and Electrical Properties of Al_2O_3,HfO_2,and their Alloy Films Prepared by Atomic Layer Deposition for 65nm CMOS Gate Dielectric

摘要

We have investigated physical and electrical properties of Al_2O_3,HfO_2,and their alloy films deposited on 300mm Si wafers by Atomic Layer Deposition (ALD).It is found that Al_2O_3 films are not crystallized even after the heat treatment of 1050 deg C,while HfO_2 films are already crystallized even after a-Si deposition (530 deg C).The crystallization temperature can be higher by adding Al_2O_3 to HfO_2.It is confirmed by in-plane XRD and plane views of TEM that HfA10x films with lower Hf content (Hf/(Hf+Al) <30%) are amorphous without phase separation after annealing at 1050 deg C and 5sec.The dependences of equivalent oxide thicknesses (EOT) on the physical thicknesses of Al_2O_3,HfAlO_x (Hf/(Hf+Al)-22%),and HfO_2 films in poly-silicon gate capacitors indicate that those dielectric constants k are -9,14,and 23,respectively.The gate dielectric with EOT of 1.5nm and the leakage current density J_g of 3mA/cm~2 can be fabricated with 2nm-thick HfAlO_x (22%) film.