Atomic layer deposition of transition metals

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Atomic layer deposition (ALD) is a key technique for creating uniform thin films.
• ALD has been limited in its application for depositing pure metals, with success mainly in metal compounds.
• Developing new ALD processes for pure metals is crucial for advanced material applications.

Purpose of the Study:

• To demonstrate novel ALD processes for depositing pure transition metals like copper, cobalt, iron, and nickel.
• To investigate the underlying surface reactions and growth mechanisms for these metal ALD processes.
• To explore the potential of ALD for producing metal oxide films using water vapor.

Main Methods:

• Utilized homoleptic N,N'-dialkylacetamidinato metal compounds as precursors.
• Employed molecular hydrogen gas as a coreactant for metal deposition.
• Investigated complementary and self-limiting surface reactions for conformal film growth.
• Explored the use of water vapor for metal oxide film deposition.

Main Results:

• Successfully demonstrated ALD processes for copper, cobalt, iron, and nickel.
• Achieved highly uniform film thicknesses and conformal coating in nanoscale features.
• Proposed a hydrogenation mechanism responsible for the observed ALD growth.
• Produced uniform, conformal films of metal oxides, including lanthanum oxide, using water vapor.

Conclusions:

• The developed ALD processes significantly expand the range of materials that can be deposited using this technique.
• The hydrogenation mechanism offers a pathway for ALD of other metals.
• These advancements enable the improved production of devices previously limited by ALD material constraints.