Thin aluminum oxide (Al 2 O 3 ) films were grown by plasma-assisted atomic layer controlled deposition (PAALD) method using Dimethylethylamine alane ((CH 3 ) 2 (C 2 H 5 )N:AlH 3 ) (DMEAA). Al was deposited by PAALD method, then the Al films were oxidized into Al 2 O 3 by the plasma oxidation in the same chamber without breaking the vacuum. Al 2 O 3 thin films of 15 nm thickness were prepared by repetition of the above mentioned process. Thus, prepared Al 2 O 3 thin films showed a refractive index of 1.68. The thickness and the refractive index fluctuation of the film over a 4-in. wafer were +/-2.3% and +/-1.9%, respectively, for atomic layer controlled deposited films. The leakage current density and breakdown field were measured to be about 10 - 8 A/cm 2 at 1 and 7 MV/cm, respectively.