Chemical Stability of Advanced Metal Gate and Ultra-Thin Gate Dielectric Interface During Rapid Thermal Annealing

摘要

The chemical stability of the compound metals TiN_x and WN_x on SiO_2 and SiO_2/Si_3N_4 (ON) dielectric stacks is studied by on-line Auger electron spectroscopy (AES) following sequential rapid thermal annealing treatments of 15 - 180 s up to 850 deg C. The TiN_x/SiO_2 interface reacts at 850 deg C and the reaction is kinetics driven. The TiN_x/Si_3N_4 interface is more stable than TN_x/SiO_2 even after a 180 s anneal at 850 deg C. WN_x is stable below 650 deg C both on Si_2 and Si_3N_4, but above this temperature the film changes, possibly due to crystallization or interdiffusion. The changes in the WN_x film are not controlled by kinetics. The compound metals are chemically more stable at elevated temperatures than pure Ti or W on SiO_2.