Al thin films were deposited on TiN/Si(100) via metal-organic chemical vapor deposition using N-methylpyrrolidine alane as a precursor. Characterization of the deposited films were investigated with SEM, XRD, α-step, AFM, 4-point probe. The early stage of Al thin film deposition was analyzed by in-situ surface reflectance measurement with laser and photometer apparatus. The surface reflectance were changed greatly during the initial 30∼40 seconds. There were two increases and two decreases in the surface reflectance, thus the sequence of Al films were deposited at 8 significant points of the surface reflectance change. Surface topograph and cross-sectional view of each film were analyzed with SEM. Al films were grown in the complex mechanism of Volmer-Weber and Stranski-Krastanov process.