Atomic layer controlled deposition of Al 2 O 3 films using binary reaction sequence chemistry

A. W. Ott, K. C. McCarley, J. W. Klaus, J. D. Way, S. M. George*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

120 Scopus citations

Abstract

Al 2 O 3 films with precise thicknesses and high conformality were deposited using sequential surface chemical reactions. To achieve this controlled deposition, a binary reaction for Al 2 O 3 chemical vapor deposition (2A1(CH 3 ) 3 + 3H 2 O → Al 2 O 3 + 6CH 4 ) was separated into two half-reactions: (A) AlOH* + Al(CH 3 ) 3 → Al-O-Al(CH 3 )* 2 + CH 4 , (B) AlCH* 3 * + H 2 O → AlOH* + CH 4 , where the asterisks designate the surface species. Trimethylaluminum (Al(CH 3 ) 3 ) (TMA) and H 2 O reactants were employed alternately in an ABAB . . . binary reaction sequence to deposit Al 2 O 3 films on single-crystal Si(100) and porous alumina membranes with pore diameters of ∼ 220 Å. Ellipsometric measurements obtained a growth rate of 1.1 Å/AB cycle on the Si(100) substrate at the optimal reaction conditions. The Al 2 O 3 films had an index of refraction of n = 1.65 that is consistent with a film density of ρ 3.50 g/cm 3 . Atomic force microscope images revealed that the Al 2 O 3 films were exceptionally flat with a surface roughness of only ± 3 Å (rms) after the deposition of ∼ 270 Å using 250 AB reaction cycles. Al 2 O 3 films were also deposited inside the pores of Anodisc alumina membranes. Gas flux measurements for H 2 and N 2 were consistent with a progressive pore reduction versus number of AB reaction cycles. Porosimetry measurements also showed that the original pore diameter of ∼ 220 Å was reduced to ∼ 130 Å after 120 AB reaction cycles.

Original languageEnglish (US)
Pages (from-to)128-136
Number of pages9
JournalApplied Surface Science
Volume107
DOIs
StatePublished - Nov 1996

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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