Applied Microscopy

  • Volume 50
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  • Pages.7.1-7.10
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  • 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.

References

  1. K. Baba, R. Hatada, Synthesis and properties of tantalum nitride films formed by ion beam assisted deposition. Surf. Coat. Technol. 84, 429 (1996)
  2. S.I. Baik, A. Duhin, P.J. Phillips, R.F. Klie, E. Gileadi, D.N. Seidman, N. Eliaz, Atomicscale structural and chemical study of columnar and multilayer re-Ni electrodeposited thermal barrier coating. Adv. Eng. Mater. 18(7), 1133-1144 (2016)
  3. S.I. Baik, J.W. Park, T.Y. Ahn, G.R. Lee, J.J. Lee, Y.W. Kim, Characterization of TaN thin films synthesized by ICP assisted sputtering. Microsc. Microanal. 14, 330-331 (2008)
  4. S.L. Cho, K.B. Kim, S.H. Min, H.K. Shin, S.D. Kim, Diffusion barrier properties of Metallorganic chemical vapor deposited tantalum nitride films against cu metallization. J. Electrochem. Soc. 146, 3724 (1999)
  5. K.J. Choi, S.G. Yoon, Characteristics of Pt and TaN metal gate electrode for high-k hafnium oxide gate dielectrics. Electrochem. Solid-State Lett. 7, G47 (2004)
  6. W. Ensinger, M. Kiuchi, M. Satou, Low-temperature formation of metastable cubic tantalum nitride by metal condensation under ion irradiation. J. Appl. Phys. 77(12), 6630-6635 (1995)
  7. K. Frisk, Analysis of the phase diagram and thermochemistry in the ta-N and the ta-C-N systems. J. Alloys Comp. 278, 216 (1998)
  8. C.H. Han, K.N. Cho, J.E. Oh, S.H. Paek, C.S. Park, S.I. Lee, M.Y. Lee, J.G. Lee, Barrier metal properties of amorphous tantalum nitride thin films between platinum and silicon deposited using remote plasma metal organic chemical vapor method. Jpn. J. Appl. Phys. 37, 2646-2651 (1998)
  9. J. Hopwood, F. Qian, Mechanisms for highly ionized magnetron sputtering. J. Appl. Phys. 78, 758 (1995)
  10. H. Kawasaki, K. Doi, J. Namba, Y. Suda, T. Ohshima, K. Ebihara, Characterization of tantalum nitride thin films fabricated by pulsed Nd. Jpn. J. Appl. Phys. 40, 2391 (2001)
  11. S.K. Kim, B.C. Cha, Deposition of tantalum nitride thin films by D.C. magnetron sputtering. Thin Solid Films 475, 202 (2005)
  12. T. Laurila, K. Zeng, J.K. Kivilahti, J. Molarius, T. Riekkinen, I. Suni, Tantalum carbide and nitride diffusion barriers for cu metallisation. Microelectron. Eng. 60, 71-80 (2001)
  13. G.R. Lee, H. Kim, H.S. Choi, J.J. Lee, Superhard tantalum- nitride films formed by inductively coulpled plasma- assisted sputtering. Surf. Coatings Technol 201, 5207-5210 (2007)
  14. G.R. Lee, J.J. Lee, C.S. Shin, I. Petrov, J.E. Greene, Self-organized lamellar structured tantalum-nitride by UHV unbalanced-magnetron sputtering. Thin Solid Films 475(1), 45-48 (2005)
  15. J.J. Lee, J.H. Joo, Application of inductively coupled plasma to super-hard and decorative coatings. Surf. Coat. Technol. 169-170, 353 (2003)
  16. W.H. Lee, J.C. Lin, C. Lee, Characterization of tantalum nitride films deposited by reactive sputtering of ta in N2/Ar gas mixtures. Mater. Chem. Phys. 68, 266 (2001)
  17. S. Li, P.P. Freitas, M.S. Rogalski, M. Azevedo, J.B. Sousa, Z.N. Dai, J.C. Soares, N. Matsakawa, H. Sakakima, Magnetic properties and structure of a new multilayer [FeTaN/TaN]n for recording heads. J. Appl. Phys. 81, 4501-4503 (1997)
  18. J.W. Lim, H.S. Park, T.H. Park, J.H. Joo, J.J. Lee, Mechanical properties of titanium nitride coatings deposited by inductively coupled plasma assisted direct current magnetron sputtering. J. Vac. Sci. Technol. A 18(2), 524-528 (2000)
  19. M. Ohring, The Materials Science of Thin Films (Academc press, San Diego, 1992)
  20. David C. Palmer & Shirley E. Palmer. CrystalMaker Software (1994), http://crystalmaker.com/index.html
  21. H.L. Park, K.B. Byun, W.J. Lee, Transformer coupled plasma enhanced metal organic chemical vapor deposition of ta (Si) N thin films and their cu diffusion barrier properties. Jpn. J. Appl. Phys. 41, 6153 (2002)
  22. T. Riekkinen, J. Molarius, T. Laurila, A. Nurmela, I. Suni, J.K. Kivilahti, Reactive sputter deposition and properties of ta N thin films. Microelectron. Eng. 64, 289-297 (2002)
  23. S.B. Rossnagel, J. Hopwood, Magnetron sputter deposition with high levels of metal ionization. Appl. Phys. lett. 63, 3285 (1993)
  24. C.S. Shin, D. Gall, Y.W. Kim, N. Hellgren, I. Petrov, J.E. Greene, Development of preferred orientation in polycrystalline NaCl-structure d-TaN layers grown by reactive magnetron sputtering: Role of low-energy ion surface interactions. J. Appl. Phys. 92(9), 5084-5093 (2002a)
  25. C.S. Shin, Y.W. Kim, N. Hellgren, D. Gall, I. Petrov, J.E. Greene, Epitaxial growth of metastable d-TaN layers on MgO 001 using low-energy, high-flux ion irradiation during ultrahigh vacuum reactive magnetron sputtering. J. Vac. Sci. Technol. A 20, 2007-2201 (2002b)
  26. R. Sreenivasan, T. Sugawara, K.S. Saraswat, P.C. Mclntyre, High temperature phase transformation of tantalum nitride films deposited by plasma enhanced atomic layer deposition for gate electrode applications. Appl. Phys. Lett. 90, 102101 (2007)
  27. M. Stavrev, D. Fisher, C. Wenzel, K. Dresher, N. Mattern, Crystallographic and morphological characterization of reactively sputtered ta, ta-N and ta-N-O thin films. Thin Solid Films 307, 79 (1997)
  28. J.-E. Sundgren, H.T.G. Hentzell, A review of the present state of art in hard coatings grown from the vapor phase. Vac. Sci. Technol. A 4, 2259 (1986)
  29. H. Wiesenberger, W. Lengauera, P. Ettmayera, Reactive diffusion and phase equilibria in the V-C, Nb-C, Ta-C and Ta-N systems. Acta Mater. 46(1), 651-666 (1988)