The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Development of Low-Temperature Deposition Processes by Atomic Layer Epitaxy for Binary and Ternary Oxide Thin Films

Matti Putkonen

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Chemical Technology for public examination and debate in Auditorium KE 2 at Helsinki University of Technology (Espoo, Finland) on the 8th of March, 2002, at 12 noon.

Overview in PDF format (ISBN 951-22-5708-4)   [4621 KB]
Dissertation is also available in print (ISBN 951-22-5852-8)

Abstract

Atomic layer epitaxy (ALE) method was employed for the study of growth of binary and ternary metal oxide thin films. As background for the study, the basic principles of the ALE method are presented together with a review of existing ALE deposition processes and precursors for oxide thin films.

The suitability of β-diketonate type precursors (M(thd)3 M=Sc,Y,La; thd = 2,2,6,6-tetramethylheptanedione) and ozone were studied for ALE depositions of Group 3 oxides, namely Sc2O3, Y2O3 and La2O3. All three oxides could be deposited by a self-limiting ALE process once a suitable deposition temperature was identified. The optimal deposition temperature was found to depend on the position of the self-limiting deposition region, but also on the impurity content, which increases at low deposition temperatures. Deposition rate of Sc2O3 was considerably higher from organometallic precursor, (C5H5)3Sc, than from β-diketonate precursor (0.75 Å(cycle)-1 vs. (0.125 Å(cycle)-1).

In a second set of experiments, the suitability of the ALE processes developed was tested for the deposition of ternary thin films, namely yttria-stabilised zirconia (YSZ) and lanthanum aluminate. Before these processes were applied, study was made of the deposition of ZrO2 from β-diketonate and organometallic precursors at 200-500 °C. Furthermore, ALE deposited MgO films were tested for their suitability as buffer layers between silicon substrate and LaAlO3 film. Crystalline YSZ films were obtained regardless of the yttrium to zirconium ratio, whereas the LaAlO3 films were crystalline only after annealing at 900 °C.

This thesis consists of an overview and of the following 8 publications:

  1. Putkonen, M., Nieminen, M., Niinistö, J., Sajavaara, T. and Niinistö, L., Surface-controlled deposition of Sc2O3 thin films by atomic layer epitaxy using β-diketonate and organometallic precursors, Chem. Mater. 13 (2001) 4701-4707.
  2. Putkonen, M., Sajavaara, T., Johansson, L.-S. and Niinistö, L., Low temperature ALE deposition of Y2O3 thin films from β-diketonate precursors, Chem. Vap. Deposition 7 (2001) 44-50.
  3. Nieminen, M., Putkonen, M. and Niinistö, L., Formation and stability of lanthanum oxide thin films grown by atomic layer epitaxy, Appl. Surf. Sci. 174 (2001) 155-165.
  4. Putkonen, M. and Niinistö, L., Zirconia thin films by atomic layer epitaxy. A comparative study on the use of novel precursors with ozone, J. Mater. Chem. 11 (2001) 3141-3147.
  5. Putkonen, M., Sajavaara, T., Niinistö, J., Johansson, L.-S. and Niinistö. L., Deposition of yttria-stabilized zirconia thin films by atomic layer epitaxy from β-diketonate and organometallic precursors, J. Mater. Chem., in press.
  6. Putkonen, M., Johansson, L.-S., Rauhala, E. and Niinistö, L., Surface-controlled growth of magnesium oxide thin films by atomic layer epitaxy, J. Mater. Chem. 9 (1999) 2449-2452.
  7. Putkonen, M., Sajavaara, T. and Niinistö, L., Enhanced growth rate in atomic layer epitaxy deposition of magnesium oxide thin films, J. Mater. Chem. 10 (2000) 1857-1861.
  8. Nieminen, M., Sajavaara, T., Rauhala, E., Putkonen, M. and Niinistö, L., Surface-controlled growth of LaAlO3 thin films by atomic layer epitaxy, J. Mater. Chem. 11 (2001) 2340-2345.

Keywords: oxide thin films, atomic layer epitaxy, atomic layer deposition

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© 2002 Helsinki University of Technology

Last update 2011-05-26