The gas phase reaction mechanism in the aluminum metalorganic chemical vapor deposition from dimethylethylamine alane (DMEAA) was investigated by Fourier transform infrared spectroscopy. DMEAA in the gas phase was dissociated into dimethylethylamine and alane even at room temperature and the dissociation rate was accelerated at higher gas temperatures. Alane, produced from the dissociation of DMEAA, disappeared rapidly and the intermediates, produced during the degradation of alane, may form Al particles. The dissociation reaction was found to be a first order reaction, and the activation energy was about 9.56 kcal/mol. In H-2 carrier gas, the dissociation of DMEAA was slower than that in Ar gas. The deposition rate was decreased when the substrate temperature was above 150 degrees C because DMEAA decomposed rapidly in the gas phase. From the experimental observations, a gas phase reaction mechanism was proposed and the degradation mechanism of liquid DMEAA was suggested.