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Title: Low temperature hydrogen plasma-assisted atomic layer deposition of copper studied using in situ infrared reflection absorption spectroscopy

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 ALDmore » 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.« less
Authors:
; ;  [1] ;  [2]
  1. Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado 80401 (United States)
  2. Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)
Publication Date:
OSTI Identifier:
22258758
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 32; Journal Issue: 1; Other Information: (c) 2014 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, 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