Al3O3 thin film growth on Si(100) using binary reaction sequence chemistry

A. W. Ott*, J. W. Klaus, J. M. Johnson, S. M. George

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

438 Scopus citations

Abstract

Al2O3 films with precisely controlled thicknesses and excellent conformality were grown on Si(100) at low temperatures of 350-650 K using sequential surface chemical reactions. This controlled deposition was achieved by separating a binary reaction for Al2O3 chemical vapor deposition (2A1(CH3)3 + 3H2O → Al2O3 + 6CH4) into two half-reactions: (A) AlOH* + Al(CH3)3 → AlOAl(CH3)*2 + CH4 (B) AlCH*3 + H2O → AlOH* + CH4 In the above reactions, the trimethylaluminum [A1(CH3)3] (TMA) and H2O reactants were employed alternately in an ABAB... binary reaction sequence where the asterisks designate the surface species. At the optimal reaction conditions, a growth rate of 1.1 Å per AB cycle was measured on the Si (100) substrate using ellipsometry. These Al2O3 films had an index of refraction of n = 1.65 and a corresponding density of p = 3.50 g cm-3. Additional ellipsometric measurements revealed that the Al2O3 deposition rate per AB cycle decreased at substrate temperatures > 450 K. The decrease in the growth rate closely matched the thermal stability of the AlOH* and AlCH*3 surface species previously measured with FTIR spectroscopy. This correlation supports a reaction mechanism based on self-limiting surface chemistry. Atomic force microscope images revealed that the deposited Al2O3 films were exceptionally flat with a surface roughness of only + 3 Å (rms) after 500 AB cycles and the deposition of a film thickness of ∼ 560 Å. The power spectra of the surface topography measured by AFM also demonstrated that the surface roughness was nearly identical for the initial Si(100) substrate and the deposited Al2O3 films after 20-500 AB reaction cycles.

Original languageEnglish (US)
Pages (from-to)135-144
Number of pages10
JournalThin Solid Films
Volume292
Issue number1-2
DOIs
StatePublished - Jan 5 1997

Keywords

  • Aluminium oxide
  • Atomic force microscopy
  • Chemical vapour deposition
  • Ellipsometry

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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