Thermal nitridation of ultrathin SiO2 on Si by NH3

Osamu Jintsugawa, Masao Sakuraba, Takashi Matsuura, Junichi Murota

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27 Citations (Scopus)


Thermal nitridation of a 30 Å thick SiO2 film on Si(100) was carried out at 750-850°C with NH3 pressures of 100-500 Pa using an ultraclean low-pressure chemical vapour deposition system, and the depth profile of the nitrogen atom concentration in the SiO2 film was measured with atomic order resolution by repetitions of XPS measurement and etching with dilute HF solution dipping. It is suggested that nitrogen species are adsorbed at the outermost SiO2 surface by NH3 reaction, diffuse into the SiO2 film and then nitride the Si substrate surface at the SiO2/Si interface. With increasing nitridation time, the surface nitrogen concentration initially increased and saturated to 2-3(×1022) cm-3; the saturation time was dependent on the NH3 pressure. The interface nitrogen concentration increased with a delay period and saturated to ∼6.5 × 1014 cm-2; the time to increase of interface concentration was also dependent on the NH3 pressure. The diffusion characteristics of the nitrogen atoms in SiO2 were expressed by Fick's law and the temperature dependence of the diffusion coefficient was well determined as D = 2.2 × 10-8 exp(-2.2 eV/kT) (cm2 s-1). Finally, it is clarified that most of the nitrogen atoms can be localized to within a 10 Å thick surface region by choosing the nitridation conditions.

Original languageEnglish
Pages (from-to)456-459
Number of pages4
JournalSurface and Interface Analysis
Issue number1
Publication statusPublished - 2002 Aug
EventECASIA'01 Proceedings of the 9th European Conference on Applications of Suface and Interface Analysis - Avignon, France
Duration: 2001 Sept 302001 Oct 5


  • Diffusion
  • NH
  • Nitridation
  • Segregation
  • Silicon dioxide
  • Silicon oxynitride


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