Interface State Reduction by Plasma-Enhanced Atomic Layer Deposition of Homogeneous Ternary Oxides

Homogeneous ternary oxides of silicon-, niobium-, and molybdenum-aluminate were deposited by plasma-enhanced ALD using sequential metal precursor pulses prior to the oxidation step, to reduce interfacial defects usually observed in nanolaminate growth. The growth kinetics can be understood in terms of competitive adsorption. Trimethyl aluminum (TMA) is strongly chemisorbed to the growth surface and does not permit coadsorption of any of the other precursors; when we lead with a TMA pulse, the resulting film is always Al₂O₃. When we lead with the Si or Nb precursors, the growth surface is partially saturated, but open sites are available for TMA coadsorption. The Mo precursor is weakly chemisorbed and is largely displaced by a subsequent TMA dose. As compared to nanolaminate films of the constituent binary oxides, the interface state density is reduced by up to a factor of 5.