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Russian Microelectronics

, Volume 48, Issue 6, pp 364–372 | Cite as

Parameters of Plasma and Way of Etching Silicon in a CF4 + CHF3 + O2 Mixture

  • A. M. EfremovEmail author
  • D. B. Murin
  • K.-H. Kwon
Article

Abstract

The effect of the CF4/CHF3 ratio in a CF4 + CHF3 + 9% O2 mixture on the parameters of the gaseous phase and kinetics of etching of silicon under the conditions of low-pressure inductively coupled plasma is investigated. It was found that substitution of CF4 by CHF3 at constant external parameters of the plasma (1) leads to a change of the temperature (average energy) and density of the electrons; (2) causes a decrease of the fluorine atom density followed by the majority of the molecules of HF; and (3) stimulates an increase of the rate of deposition and thickness of the fluorocarbon polymer film. By the analysis of the way of etching of silicon with the use of the calculated data on the fluxes of active particles, it was found that the observed change of the etching rate can be explained by heterogeneous reactions with the involvement of O, H, and HF. It was assumed that the process of etching silicon proceeds in the mode of limitation by the flux of chemically active particles F + HF and is characterized by the effective probability depending on the thickness of the fluorocarbon polymer film.

Notes

FUNDING

The investigation was financially supported by the by the Russian Foundation for Basic Research (scientific project no. 18-37-00064 mol_a).

REFERENCES

  1. 1.
    Rossnagel, S.M., Cuomo, J.J., and Westwood, W.D., Handbook of Plasma Processing Technology, Park Ridge: Noyes, 1990.Google Scholar
  2. 2.
    Rooth, J.R., Industrial Plasma Engineering, Philadelphia: Inst. of Phys., 1995.CrossRefGoogle Scholar
  3. 3.
    Roosmalen, A.J., Baggerman, J.A.G., and Brader, S.J.H., Dry Etching for VLSI, New York: Plenum, 1991.CrossRefGoogle Scholar
  4. 4.
    Wolf, S. and Tauber, R.N., Silicon Processing for the VLSI Era, Vol. 1: Process Technology, New York: Lattice, 2000.Google Scholar
  5. 5.
    Lieberman M.A. and Lichtenberg A.J., Principles of Plasma Discharges and Materials Processing, New York: Wiley, 1994.Google Scholar
  6. 6.
    Jansen, H., Gardeniers, H., de Boer, M., Elwenspoek, M., and Fluitman, J., A survey on the reactive ion etching of silicon in microtechnology, J. Micromech. Microeng., 1996, vol. 6, pp. 14–28.CrossRefGoogle Scholar
  7. 7.
    Turban, G., Grolleau, B., Launay, P., and Briaud, P., A mass spectrometric diagnostic of C2F6 and CHF3 plasmas during etching of SiO2 and Si, Rev. Phys. Appl., 1985, vol. 20, pp. 609–620.CrossRefGoogle Scholar
  8. 8.
    Takahashi, K., Hori, M., and Goto, T., Characteristics of fluorocarbon radicals and CHF3 molecule in CHF3 electron cyclotron resonance downstream plasma, Jpn. J. Appl. Phys., 1994, vol. 33, pp. 4745–4758.CrossRefGoogle Scholar
  9. 9.
    Kimura, T. and Ohe, K., Model and probe measurements of inductively coupled CF4 discharges, J. Appl. Phys., 2002, vol. 92, pp. 1780–1787.CrossRefGoogle Scholar
  10. 10.
    Kimura, T. and Ohe, K., Probe measurements and global model of inductively coupled Ar/CF4 discharges, Plasma Sources Sci. Technol., 1999, vol. 8, pp. 553–560.CrossRefGoogle Scholar
  11. 11.
    Chun, I., Efremov, A., Yeom, G.Y., and Kwon, K.-H., A comparative study of CF4/O2/Ar and C4F8/O2/Ar plasmas for dry etching applications, Thin Solid Films, 2015, vol. 579, pp. 136–143.CrossRefGoogle Scholar
  12. 12.
    Ho, P., Johannes, J.E., and Buss, R.J., Modeling the plasma chemistry of C2F6 and CHF3 etching of silicon dioxide, with comparisons to etch rate and diagnostic data, J. Vac. Sci. Technol., A, 2001, vol. 19, pp. 2344–2367.CrossRefGoogle Scholar
  13. 13.
    Bose, D., Rao, M.V.V.S., Govindan, T.R., and Meyyappan, M., Uncertainty and sensitivity analysis of gas-phase chemistry in a CHF3 plasma, Plasma Sources Sci. Technol., 2003, vol. 12, pp. 225–234.CrossRefGoogle Scholar
  14. 14.
    Proshina, O., Rakhimova, T.V., Zotovich, A., Lopaev, D.V., Zyryanov, S.M., and Rakhimov, A.T., Multifold study of volume plasma chemistry in Ar/CF4 and Ar/CHF3 CCP discharges, Plasma Sources Sci. Technol., 2017, vol. 26, p. 075005.CrossRefGoogle Scholar
  15. 15.
    Son, J., Efremov, A., Yun, S.J., Yeom, G.Y., and Kwon, K.-H., Etching characteristics and mechanism of SiNx films for nano-devices in CH2F2/O2/Ar inductively coupled plasma: effect of O2 mixing ratio, J. Nanosci. Nanotech., 2014, vol. 14, pp. 9534–9540.CrossRefGoogle Scholar
  16. 16.
    Johnson, E.O. and Malter, L., A floating double probe method for measurements in gas discharges, Phys. Rev., 1950, vol. 80, pp. 58–70.CrossRefGoogle Scholar
  17. 17.
    Sugavara, M., Plasma Etching: Fundamentals and Applications, New York: Oxford Univ. Press, 1998.Google Scholar
  18. 18.
    Efremov, A., Lee, J., and Kwon, K.-H., A comparative study of CF4, Cl2 and HBr + Ar inductively coupled plasmas for dry etching applications, Thin Solid Films, 2017, vol. 629, pp. 39–48.CrossRefGoogle Scholar
  19. 19.
    Lim, N., Efremov, A., Yeom, G.Y., and Kwon, K.-H., On the etching characteristics and mechanisms of HfO2 thin films in CF4/O2/Ar and CHF3/O2/Ar plasma for nano-devices, J. Nanosci. Nanotechnol., 2014, vol. 14, pp. 9670–9679.CrossRefGoogle Scholar
  20. 20.
    Son, J., Efremov, A., Chun, I., Yeom, G.Y., and Kwon, K.-H., On the LPCVD-formed SiO2 etching mechanism in CF4/Ar/O2 inductively coupled plasmas: effects of gas mixing ratios and gas pressure, Plasma Chem. Plasma Process., 2014, vol. 34, pp. 239–257.CrossRefGoogle Scholar
  21. 21.
    Efremov, A., Kwon, K.-H., Morgunov, A., and Shabadarova, D., Comparative study of CF4- and CHF3-based plasmas for dry etching applications, Proc. SPIE, 2016, vol. 10224, p. 102241W.CrossRefGoogle Scholar
  22. 22.
    Chistophorou, L.G. and Olthoff, J.K., Fundamental Electron Interactions with Plasma Processing Gases, New York: Springer Science, 2004.CrossRefGoogle Scholar
  23. 23.
    NIST Chemical Kinetics Database. http://kinetics. nist.gov/kinetics/.Google Scholar
  24. 24.
    Standaert, T.E.F.M., Hedlund, C., Joseph, E.A., and Oehrlein, G.S., Role of fluorocarbon film formation in the etching of silicon, silicon dioxide, silicon nitride, and amorphous hydrogenated silicon carbide, J. Vac. Sci. Technol., A, 2004, vol. 22, pp. 53–60.CrossRefGoogle Scholar
  25. 25.
    Stoffels, W.W., Stoffels, E., and Tachibana, K., Polymerization of fluorocarbons in reactive ion etching plasmas, J. Vac. Sci. Technol. A, 1998, vol. 16, pp. 87–95.CrossRefGoogle Scholar
  26. 26.
    Matsui, M., Tatsumi, T., and Sekine, M., Relationship of etch reaction and reactive species flux in C4F8–Ar–O2 plasma for SiO2 selective etching over Si and Si3N4, J. Vac. Sci. Technol., A, 2001, vol. 19, pp. 2089–2096.CrossRefGoogle Scholar
  27. 27.
    Gray, D.C., Tepermeister, I., and Sawin, H.H., Phenomenological modeling of ion enhanced surface kinetics in fluorine-based plasma etching, J. Vac. Technol. B, 1993, vol. 11, pp. 1243–1257.CrossRefGoogle Scholar
  28. 28.
    Lee, C., Graves, D.B., and Lieberman, M.A., Role of etch products in polysilicon etching in a high-density chlorine discharge, Plasma Chem. Plasma Process., 1996, vol. 16, pp. 99–118.CrossRefGoogle Scholar
  29. 29.
    Efremov, A.M., Murin, D.B., and Kwon, K.H., On the effect of the ratio of concentrations of fluorocarbon components in a CF4 + C4F8 + Ar mixture on the parameters of plasma and SiO2/Si etching selectivity, Russ. Microelectron., 2018, vol. 47, no. 4, pp. 239–246.CrossRefGoogle Scholar
  30. 30.
    Efremov, A.M., Murin, D.B., and Kwon, K.H., Parameters of plasma and kinetics of active particles in CF4(CHF3) + Ar mixtures of a variable initial composition, Russ. Microelectron., 2018, vol. 47, no. 6, pp. 371–380.CrossRefGoogle Scholar
  31. 31.
    Jang, W.I., Choi, C.A., Lee, M.L., Jun, C.H., and Kim, Y.T., Fabrication of MEMS devices by using anhydrous HF gas-phase etching with alcoholic vapor, J. Micromech. Microeng., 2002, vol. 12, pp. 297–306.CrossRefGoogle Scholar
  32. 32.
    Clements, L.D., Busse, J.E., and Mehta, J., Reaction mechanisms and rate limitations in dry etching of silicon dioxide with hydrous hydrogen fluoride, in Semiconductor Fabrication; Technology and Metrology, 1989, ASTM STP 990, pp. 182–201.Google Scholar
  33. 33.
    Hoshino, T. and Nishioka, Y., Etching process of SiO2 by HF molecules, J. Chem. Phys., 1999, vol. 111, pp. 2109–2114.CrossRefGoogle Scholar
  34. 34.
    Jang, W.I., Choi, C.A., Lee, C.S., Hong, Y.S., Lee, J.H., Kim, B.W., and Kim, D.Y., Optimal gas-phase etching for the dry release of polysilicon and SOI microstructures, J. Korean Phys. Soc., 1999, vol. 34, pp. 69–74.Google Scholar
  35. 35.
    Kastenmeier, B.E.E., Matsuo, P.J., Beulens, J.J., and Oehrlein, G.S., Chemical dry etching of silicon nitride and silicon dioxide using CF4/O2/N2 gas mixtures, J. Vac. Sci. Technol., A, 1996, vol. 14, pp. 2802–2813.CrossRefGoogle Scholar
  36. 36.
    Kastenmeier, B.E.E., Matsuo, P.J., and Oehrlein, G.S., Highly selective etching of silicon nitride over silicon and silicon dioxide, J. Vac. Sci. Technol., A, 1999, vol. 17, pp. 3179–3184.CrossRefGoogle Scholar

Copyright information

© Pleiades Publishing, Ltd. 2019

Authors and Affiliations

  1. 1.Ivanovo State University of Chemistry and TechnologyIvanovoRussia
  2. 2.Korea UniversitySejongSouth Korea

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