Low temperature hydrogen plasma-assisted atomic layer deposition of copper studied using in situ infrared reflection absorption spectroscopy
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado 80401 (United States)
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)
Atomic layer deposition (ALD) is an ideal technique to deposit ultrathin, conformal, and continuous metal thin films. However, compared to the ALD of binary materials such as metal oxides and metal nitrides, the surface reaction mechanisms during metal ALD are not well understood. In this study, the authors have designed and implemented an in situ reflection-absorption infrared spectroscopy (IRAS) setup to study the surface reactions during the ALD of Cu on Al{sub 2}O{sub 3} using Cu hexafluoroacetylacetonate [Cu(hfac){sub 2}] and a remote H{sub 2} plasma. Our infrared data show that complete ligand-exchange reactions occur at a substrate temperature of 80 °C in the absence of surface hydroxyl groups. Based on infrared data and previous studies, the authors propose that Cu(hfac){sub 2} dissociatively chemisorbs on the Al{sub 2}O{sub 3} surface, where the Al-O-Al bridge acts as the surface reactive site, leading to surface O-Cu-hfac and O-Al-hfac species. Surface saturation during the Cu(hfac){sub 2} half-cycle occurs through blocking of the available chemisorption sites. In the next half-reaction cycle, H radicals from an H{sub 2} plasma completely remove these surface hfac ligands. Through this study, the authors have demonstrated the capability of in situ IRAS as a tool to study surface reactions during ALD of metals. While transmission and internal reflection infrared spectroscopy are limited to the first few ALD cycles, IRAS can be used to probe all stages of metal ALD starting from initial nucleation to the formation of a continuous film.
- OSTI ID:
- 22258758
- Journal Information:
- Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films, Vol. 32, Issue 1; Other Information: (c) 2014 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0734-2101
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
ABSORPTION SPECTROSCOPY
ALUMINIUM OXIDES
CHEMISORPTION
COMPARATIVE EVALUATIONS
COPPER
DEPOSITS
HYDROGEN
HYDROXIDES
INFRARED SPECTRA
ION EXCHANGE
PLASMA
REACTION KINETICS
REFLECTION
SUBSTRATES
SURFACES
TEMPERATURE RANGE 0065-0273 K
THIN FILMS