Atomic layer deposition of transition metals

Nat Mater. 2003 Nov;2(11):749-54. doi: 10.1038/nmat1000. Epub 2003 Oct 26.

Abstract

Atomic layer deposition (ALD) is a process for depositing highly uniform and conformal thin films by alternating exposures of a surface to vapours of two chemical reactants. ALD processes have been successfully demonstrated for many metal compounds, but for only very few pure metals. Here we demonstrate processes for the ALD of transition metals including copper, cobalt, iron and nickel. Homoleptic N,N'-dialkylacetamidinato metal compounds and molecular hydrogen gas were used as the reactants. Their surface reactions were found to be complementary and self-limiting, thus providing highly uniform thicknesses and conformal coating of long, narrow holes. We propose that these ALD layers grow by a hydrogenation mechanism that should also operate during the ALD of many other metals. The use of water vapour in place of hydrogen gas gives highly uniform, conformal films of metal oxides, including lanthanum oxide. These processes should permit the improved production of many devices for which the ALD process has previously not been applicable.

Publication types

  • Evaluation Study
  • Historical Article
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adsorption
  • Cobalt / chemistry
  • Copper / chemistry
  • Gases / chemistry*
  • History, Ancient
  • Hot Temperature
  • Iron / chemistry
  • Macromolecular Substances
  • Materials Testing
  • Membranes, Artificial*
  • Metals / chemical synthesis
  • Metals / chemistry*
  • Molecular Conformation
  • Nanotechnology / methods*
  • Nickel / chemistry
  • Surface Properties
  • Transition Elements / chemical synthesis
  • Transition Elements / chemistry*

Substances

  • Gases
  • Macromolecular Substances
  • Membranes, Artificial
  • Metals
  • Transition Elements
  • Cobalt
  • Copper
  • Nickel
  • Iron