Applied Microscopy

  • Volume 50
  • /
  • Pages.7.1-7.10
  • /
  • 2020
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  • 2287-5123(pISSN)
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  • 2287-4445(eISSN)
Korean Society of Microscopy (한국현미경학회)
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Microstructural evolution of tantalum nitride thin films synthesized by inductively coupled plasma sputtering

  • Sung-Il Baik (Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University) ;
  • Young-Woon Kim (Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University)
  • Received : 2019.11.27
  • Accepted : 2020.02.09
  • Published : 2020.12.31
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Abstract

Tantalum nitride (TaNx) thin films were grown utilizing an inductively coupled plasma (ICP) assisted direct current (DC) sputtering, and 20-100% improved microhardness values were obtained. The detailed microstructural changes of the TaNx films were characterized utilizing transmission electron microscopy (TEM), as a function of nitrogen gas fraction and ICP power. As nitrogen gas fraction increases from 0.05 to 0.15, the TaNx phase evolves from body-centered-cubic (b.c.c.) TaN0.1, to face-centered-cubic (f.c.c.) δ-TaN, to hexagonal-close-packing (h.c.p.) ε-TaN phase. By increasing ICP power from 100 W to 400 W, the f.c.c. δ- TaN phase becomes the main phase in all nitrogen fractions investigated. The higher ICP power enhances the mobility of Ta and N ions, which stabilizes the δ-TaN phase like a high-temperature regime and removes the micro-voids between the columnar grains in the TaNx film. The dense δ-TaN structure with reduced columnar grains and micro-voids increases the strength of the TaNx film.

Keywords

Acknowledgement

This research was supported by Creative Materials Discovery Program through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT (No.NRF-2019M3D1A1079215). The authors thank to Dr. Gi-Rak Lee, Prof. Jung-Joong Lee (Seoul National University) for providing the samples and microhardness value for Fig. 1.

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