AVS 53rd International Symposium
    Thin Film Tuesday Sessions
       Session TF+SS-TuA

Paper TF+SS-TuA3
Surface Mechanisms in Oxygen-Based Noble Metal Atomic Layer Deposition

Tuesday, November 14, 2006, 2:40 pm, Room 2022

Session: Surface Functionalization for Selective Area ALD
Presenter: G.N. Parsons, North Carolina State University
Authors: K.J. Park, North Carolina State University
S.M. Stewart, North Carolina State University
G.N. Parsons, North Carolina State University
Correspondent: Click to Email
Atomic layer deposition of noble metals, including Pt, Ru, Re, and Rh is often achieved using a binary exposure sequence of metal-organic precursors and oxygen, and processes show saturation near one monolayer per growth cycle for varying oxygen exposure and for varying metal-organic exposure. The surface typically oxidizes during the oxygen exposure step, and then the metal precursor ligand is oxidized during the precursor exposure, leaving a single layer of metal deposited on the surface. We have recently observed that for the case of Ru ALD from bis-(cyclopentadienyl) ruthenium and oxygen, the growth thickness per cycle saturates at a value that depends on the extent of oxygen exposure in the ALD sequence. On-line Auger spectroscopy analysis shows that the extent of metal surface oxidation increases with the extent of oxygen exposure, suggesting that the extent of Ru ligand oxidation is determined by the amount of oxygen available at the surface. This is consistent with the observed increase in Ru film growth/cycle during the Ru(Cp)2 exposure step. This dependence of film growth/cycle on oxygen exposure can explain the previously observed pressure dependence of growth thickness per cycle during Ru deposition which is not expected in an ALD process. We believe these observations lead to new insights into methodologies to significantly expand and control the process window and nucleation in Ru ALD, and this can likely be extended to other noble metal ALD processes.