Effects of post-deposition annealing temperature and ambient on RF magnetron sputtered Sm_2O_3 gate on n-type silicon substrate

摘要

Samarium oxide (Sm_2O_3) thin films with thicknesses in the range of 15-30 nm are deposited on n-type silicon (100) substrate via radio frequency magnetron sputtering. Effects of post-deposition annealing ambient [argon and forming gas (FG) (90% N_2 + 10% H_2)] and temperatures (500, 600, 700, and 800 ℃) on the structural and electrical properties of deposited films are investigated and reported. X-ray diffraction revealed that all of the annealed samples possessed polycrystalline structure with C-type cubic phase. Atomic force microscope results indicated root-mean-square surface roughness of the oxide film being annealed in argon ambient are lower than that of FG annealed samples, but they are comparable at the annealing temperature of 700 ℃ (Argon-0.378 nm, FG-0.395 nm). High frequency capacitance-voltage measurements are carried out to determine effective oxide charge, dielectric constant and semiconductor-oxide interface trap density of the annealed oxide films. Sm_2O_3 thin films annealed in FG have smaller amount of effective oxide charge and semiconductor-oxide interface trap density than those oxide films annealed in argon. Current-voltage measurements are conducted to obtain barrier heights of the annealed oxide films during Fowler-Nordheim tunneling.