LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION OF MOLYBDENUM OXIDES FROM MOLYBDENUM HEXACARBONYL AND OXYGEN

Thin films of molybdenum oxides were deposited at 300-500 degrees C an d 200-1014 mTorr (26.6-135 Pa) from Mo(CO)(6), O-2, and H2O using an i nductively heated low pressure chemical vapor deposition system. Two o xygen gas flow rates of 5 and 15 seem were used. alpha-MoO3 films were deposited at temperatures of 425-450 degrees C, pressures of 660-1014 mTorr (88.0-135 Pa), with an O-2 flow rate of 5 seem; and at 450-500 degrees C, 300-500 mTorr (40.0-66.7 Pa), with an O-2 flow rate of 5 se em. The polycrystalline films were deposited on silicon (100) wafers a nd exhibited preferred orientations. Gas phase decomposition of the pr ecursor was significant with temperatures >400 degrees C and pressures >600 mTorr (88.0 Pa), with an O-2 flow rate of 15 seem. Owing to deco mposition of the precursor in the gas phase and low gas velocities, th e films decreased in thickness in the direction of flow. Thermodynamic equilibrium calculations indicated that alpha-MoO3 was the most stabl e phase for all deposition conditions. However, alpha-MoO3 was deposit ed only at high temperatures and pressures. A quadratic model of alpha -MoO3 formation was developed using experimental design for the 5 seem deposition data as a function of temperature and pressure. Both param eters were significant in the formation of alpha-MoO3 films. The films were characterized using X-ray diffraction and X-ray photoelectron, A uger, and laser Raman spectroscopies.