FTIR and ellipsometry characterization of ultra-thin ALD TaN films

Y. Y. Wu*, M. Eizenberg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

In this paper, Fourier-transform infrared (FTIR) spectroscopy and ellipsometric spectroscopy were used to characterize the optical properties of atomic layer-deposited (ALD) ultra-thin TaN films on a Si(1 0 0) single crystal. The analysis of FTIR spectra indicates that the incorporated impurities are in the form of radicals of NHx, CHx and OHx. SiHx is also detected due to interfacial reactions between NHx and the Si substrate native oxide. These H-containing radicals can be removed by post-annealing the samples. The vibration of Ta-N bonding is at the wavenumber of 1190 cm-1, which is independent of the film thickness and post-annealing temperature. The results of ellipsometric spectra show that the band gaps are 3.28 eV, 2.65 eV and 2.50 eV as the films thicknesses are 1 nm, 5 nm and 10 nm, respectively. A slight red-shift of the band gap takes place after annealing the ultra-thin films. The mechanisms of the film optical properties were analyzed in the paper.

Original languageEnglish
Pages (from-to)269-275
Number of pages7
JournalMaterials Chemistry and Physics
Volume101
Issue number2-3
DOIs
StatePublished - 15 Feb 2007
Externally publishedYes

Keywords

  • Atomic layer deposition
  • Ellipsometry
  • FTIR
  • Tantalum nitride

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