Nano-scale Stress and Compositional Analysis of Epitaxial Si1−xGex / Si (100) Undulated Films

Abstract

Spontaneous surface roughening, stress relaxation and composition re-distribution are coupled fundamental processes during the growth of strained epitaxial Si1−xGex / Si (100) alloy layers. In this work, we will present both modeling and experimental approaches to investigate the inter-relationships among these mechanisms. Stress distributions in undulated layers were calculated via the Finite Element Method by assuming a sinusoidal surface geometry. They were investigated as functions of undulation wavelength and amplitude between the trough and peak regions. For example, with a 50 nm layer of x = 0.3 having undulations of 250 nm wavelength and 40 nm amplitude, the compressive stress is twice as high in the trough regions than in the peak regions even without compositional redistribution. To explore compositional redistribution in response to these laterally varying strain fields, an experimental approach has been developed to determine local germanium concentrations for such undulated alloyolayers. An etchant consisting of HNO3 (70 wt %): H2O: HF (0.5 wt %), 25: 35: 5, at 28 oC etches Si1−xGex / Si (100) alloy layers at a rate of several nanometers per minute. The etching rate increases linearly with increasing Ge concentration in the alloy layer. Such etching experiments can thus be applied to etch alloy layers with compositionally varying undulations on the free surface and utilized to quantify the local germanium concentrations. For an alloy layer with x = 0.3, the Ge concentration from this analysis is estimated to be about 20 % enhanced / depleted in the peak / trough regions, respectively.

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References

  1. 1.

    R.J. Asaro and W.A. Tiller, Metall. Trans. 3, 1789 (1972).

    Article  CAS  Google Scholar 

  2. 2.

    M.A. Grinfeld, Sov. Phys. Dokl. 31, 831 (1986).

    Google Scholar 

  3. 3.

    D.J. Srolovitz, Acta Metall. 37 (2), 621 (1989).

    Article  Google Scholar 

  4. 4.

    H. Gao, J. Mech. Phys. Solids 39 (4), 443 (1991); 42 (5), 741 (1994).

    Article  Google Scholar 

  5. 5.

    H. Gao and W.D. Nix, Annu. Rev. Mater. Sci. 29, 173 (1999).

    Article  CAS  Google Scholar 

  6. 6.

    J.E. Guyer and P.W. Voorhees, Phys. Rev. Lett. 74 (20), 4031 (1995); Phys. Rev. B 54 (16), 11710 (1996); J. Cryst. Growth 187, 150 (1998).

    Article  CAS  Google Scholar 

  7. 7.

    P. Venezuela and J. Tersoff, Phys. Rev. B58 (16), 10871 (1998).

    Article  Google Scholar 

  8. 8.

    B.J. Spencer, P.W. Vorhees, and J. Tersoff, Phys. Rev. B64, 235318 (2001).

    Article  CAS  Google Scholar 

  9. 9.

    F. Leonard and R.C. Desai, Phys. Rev. B57 (8), 4805 (1998); Appl. Phys. Lett. 74 (1), 40 (1999).

    Article  Google Scholar 

  10. 10.

    F. Glas, Phys. Rev. B55 (17), 11277 (1997).

    Article  Google Scholar 

  11. 11.

    C.H. Wu, Acta Mech. 157, 129 (2002).

    Article  Google Scholar 

  12. 12.

    H. Emmerich, Continuum Mech. Thermodyn. 15, 197 (2003).

    Article  Google Scholar 

  13. 13.

    A.G. Cullis, D.J. Robbins, A.J. Pidduck, and P.W. Smith, J. Cryst. Growth 123, 333 (1992).

    Article  CAS  Google Scholar 

  14. 14.

    I. Berbezier, A. Ronda, and A. Portavoce, J. Phys. Condens. Matter 14, 8283 (2002).

    Article  CAS  Google Scholar 

  15. 15.

    T. Walther, C.J. Humphreys, A.G. Cullis, and D.J. Robins, Mat. Sci. Forum 196–201, 505 (1995).

    Article  Google Scholar 

  16. 16.

    T. Walther, C.J. Humphreys, and A.G. Cullis, Appl. Phys. Lett. 71 (6), 809 (1997).

    Article  CAS  Google Scholar 

  17. 17.

    A. Benedetti, D.J. Norris, C.J.D. Hetherington, A.G. Cullis, A. Armigliato, R. Balboni, D.J. Robbins, and D.J. Wallis, Inst. Phys. Conf. Ser. No. 164, 219 (1999).

    CAS  Google Scholar 

  18. 18.

    D.J. Smith, D. Chandrasekhar, S.A. Chaparro, P.A. Crozier, J. Drucker, M. Floyd, M.R. McCartney, and Y. Zhang, J. Cyrst. Growth 259, 232 (2003).

    Article  CAS  Google Scholar 

  19. 19.

    A. Malachias, S. Kycia, G. Medeiros-Ribeiro, R. Magalhaes-Paniago, T.I. Kamins, and R.S. Williams, Phys. Rev. Lett. 91 (17), 176101–1 (2003).

    Article  CAS  Google Scholar 

  20. 20.

    D.J. Godbey, A.H. Krist, K.D. Hobart, and M.E. Twigg, J. Electrochem. Soc. 139 (10), 2943 (1992).

    Article  CAS  Google Scholar 

  21. 21.

    U. Denker, M.W. Dashiell, N.Y. Jin - Phillipp, and O.G. Schmidt, Mater. Sci. Eng. B89, 166 (2002).

    Article  CAS  Google Scholar 

  22. 22.

    Microshield masking aid and protectant, SPI Supplies, Division of Structure Probe, Inc.

  23. 23.

    K. Tsunoda, E. Ohashi, and S. Adachi, J. Appl. Phys. 94 (9), 5613 (2003).

    Article  CAS  Google Scholar 

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Acknowledgments

This work is funded by the NSF - DMR (Grant # 0075116). We acknowledge Dr. Alain Portavoce (UVa) for valuable discussions. The samples were grown by Dr. J.C. Bean (UVa).

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Correspondence to Chi-Chin Wu.

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Wu, CC., Hull, R. Nano-scale Stress and Compositional Analysis of Epitaxial Si1−xGex / Si (100) Undulated Films. MRS Online Proceedings Library 854, U3.8 (2004). https://doi.org/10.1557/PROC-854-U3.8

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