Atomic Layer Deposition of AlMoxOy Films Using Aluminum Trichloride or Trimethylaluminum and Quantum-Chemical Calculations of Growth, Reduction, and Conversion Processes

A comparative analysis of the surface processes of atomic layer deposition (ALD) of AlMoxOy using H2O, molybdenum dioxide (MoO2Cl2), and trimethylaluminum (Al(CH3)3, TMA) or aluminum chloride (AlCl3) has been carried out. The effect of the aluminum precursor nature on the composition and oxidation state of molybdenum in the films has been studied. According to X-ray photoelectron spectroscopy evidence, the molybdenum content in the obtained films is lower than the aluminum content. Molybdenum with oxidation states Mo+6, Mo+5, and Mo+4 was also detected in the films; the ratio of the atomic concentration of Mo+6 to the reduced forms was 0.76 : 1 in the case of the TMA process, and 6.3 : 1 in the case of AlCl3. Replacing TMA with AlCl3 in the ALD of AlMoxOy decreased the amount of reduced Mo in the films, as well as the total molybdenum content. To evaluate the thermodynamic parameters of the proposed reactions for the ALD processes using AlCl3 and TMA, quantum-chemical DFT calculations were performed, which enabled the explanation for the observed differences in the films.