Kinetic study of chemical vapor deposition of WSix films from WF6 and SiH2Cl2: Determination of molecular size and reactivity of gas species

Takeyasu Saito, Yukihiro Shimogaki, Yasuyuki Egashira, Katsuro Sugawara, Katsumi Takahiro, Shinji Nagata, Sadae Yamaguchi, Hiroshi Komiyama

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2 Citations (Scopus)


A kinetic study of chemical vapor deposition of tungsten silicide (WSix) films from WF6 and SiH2Cl2 was done, focusing on the deposition rate profile, atomic composition ratio (ratio of Si/W), and the reactivity of film precursors. The deposition mode was changed from blanket WSix deposition to selective W deposition by decreasing the ratio of SiH2Cl2 to WF6 and also by decreasing the substrate temperature, Tsub. The rate-determining step for film deposition was determined to be diffusional mass transport of the film-forming species. The molecular diameter of the film precursor was calculated from measured diffusion coefficients to be 6-7 Å, which is close to the diameter of WF6 molecules. The temperature at which film formation was extinguished, Tex, was measured as a function of the inner diameter of the reactor. Tex was found to depend on the inner diameter of the reactor, which indicates that the first step of the WF6/SiH2Cl2 process is controlled by radical chain reactions in the gas phase to form active intermediate species. The sticking probability of the film precursor was also calculated by measuring the step coverage in micron-sized trenches. For Tsub > 600 °C, the sticking probability was about 0.35 with an activation energy of 19 kJ/mol. However, for Tsub = 500 °C, the sticking probability decreased to 0.15, which corresponds to an activation energy of 61 kJ/mol.

Original languageEnglish
Pages (from-to)36-42
Number of pages7
JournalThin Solid Films
Issue number1-2
Publication statusPublished - 2006 Aug 14


  • Chemical vapor deposition
  • Reaction kinetics
  • Silicide
  • Tungsten

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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