Thermal Stability of Atomic Layer Deposition Al_2O_3 Thin Films

Al2O3 thin films were grown by atomic layer deposition using trimthylaluminum (TMA) and water (H2O) as precursors at 270℃. Thermal stability of the Al2O3 film was explored by using X-ray diffraction, X-ray photoemission spectroscopy, Fourier transform infrared spectroscopy and atomic force microscopy. The results indicated that a small quantity of Al-OH groups existed in the as-deposited samples, and almost disappeared after rapid thermal annealing (RTA) at 600℃or higher. The O/Al ratio in the as deposited film was 1.57. And the ratio decreased to 1.52 in the RTA treated film, as expected in the case of stoichiometric Al2O3. FTIR spectroscopic revealed that there were also the presence of-CH3 species in the as-deposited films. The amount of -CH3 species decreased as annealing temperature increasing. In addition, after high temperatures RTA, the surface roughness of the Al2O3 films improved obviously, its RMS approached 1.15nm after 900℃RTA.