Mechanism, products, and growth rate of atomic layer deposition of noble metals.

We present mechanisms for atomic layer deposition of Ru, Rh, Pd, Os, Ir, or Pt metal from homoleptic precursors and oxygen. The novel mechanistic feature is that combustion of ligands produces transient hydroxyl groups on the surface, which can undergo Brønsted-type elimination of a further ligand or water from the surface. Each ligand therefore releases one electron for reduction of the metal. The growth reaction may be described as oxide-catalyzed redox decomposition of the precursor. To validate the mechanism against experiment, we derive analytical expressions for product ratios and the growth rate in terms of saturating coverages.