Growth rate and microstructure of Mo film by Chemical-Vapour-Deposition

Gas mixture consisting of MoCl5, H-2 was fed into an externally heated fused silica tube, Mo films were deposited on the inner wall by means of thermal atmospheric Chemical-Vapour-Deposition(CVD). Growth rate distribution and microstructural change at different deposition conditions were investigated. Film microstructures were dependent on the substrate temperature, and classified to be zone I and zone II structures. At high P-H2, film growth rate was high in the inlet region. The deposited films did'nt have homogeneous microstructure and composed of irregularly shaped columnar grains. On the other hand, at low P-H2, growth rate distributions were flat along the axial direction, and films were made of homogeneous columnar grains. The growth rate distributions at different gas composition at 1023K were simulated, calculating the rates of mass transfer, the reactions in gas phase and on the substrate surface. The calculated distributions agreed well with the experimental data. The formation of microstructures was discussed, considering the deposition reaction mechanisms.