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Processes during annealing of Ti–Al–Ni and Ti–Al–Ni–Au contact metallization systems

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Abstract

The Ti/Al/Ni/Au multilayer metallization system is widespread in the technology of n-GaN-based devices. Herein, the mechanisms of the formation of the surface roughness of the Ti/Al/Ni/Au metallization (with 300 nm hillocks) upon annealing in a nitrogen atmosphere for 30 s at a temperature of 850°C, which creates problems in further lithographic processes, and the ways of overcoming this disadvantage have been studied. The formation of a rough surface during the annealing of a multilayer metallization, associated with the interaction of the constituent metals, has been investigated with the Ti/Al/Ni and Ti/Al/Ni/Au systems. An increase in the sheet resistance of both metallization systems as the annealing temperature is raised can be explained by the interdiffusion of metals and the growing degree of interaction between them with the formation of various intermetallic compounds, exhibiting a far higher specific resistance than that of the initial metals. The X-ray analysis has confirmed the origination of the main NiTi, Al3Ti, and Ni2Al3 intermetallic phases in the Ti/Al/Ni three-layer metallization upon annealing. The surface of the Ti/Al/Ni metallization system has become rougher upon annealing; however, large hemispherical convexes (like those in the Ti/Al/Ni/Au metallization) have not been generated. This has refuted the hypothesis of the balling-up of the molten Al–Ni alloy on the surface of the Ti/Al/Ni metallization. To reduce the amount of an Au–Al liquid phase formed during the annealing, which is the reason that renders the Ti/Al/Ni/Au metallization surface rough, the Au layer thickness was reduced to a minimum, at which the contrast of the metallization elements to the semiconductor surface is sufficient for self-aligning during electron-beam lithography. It has been found that the 50-nm-thick Au layer serves a satisfactory contrast. At such a thickness of the Au layer, the metallization surface morphology improved considerably: the roughness decreased from 300 to 80 nm, and the surface become specular.

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References

  1. Jacobs, B., Towards integrated AlGaN/GaN based X-band high-power amplifiers, Dissertation, Eindhoven: Technische Universiteit Eindhoven, 2004.

    Google Scholar 

  2. Jacobs, B., Kramer, M.C.J.C.M., Geluk, E.J., and Karouta, F. Optimisation of the Ti/Al/Ni/Au ohmic contact on AlGaN/GaN FET structures, J. Cryst. Growth, 2002, vol. 241, pp. 15–18.

    Article  Google Scholar 

  3. Xin, H.P., Poust, S., Sutton, W., Li, D., Lam, D., Smorchkova, I., Sandhu, R., Heying, B., Uyeda, J., Barsky, M., Wojtowicz, M., and Lai, R., Optimization of AlGaN/GaN HEMT ohmic contacts for improved surface morphology with low contact resistance, in Proceedings of the CSMANTECH Conference, Portland, Oregon, USA, 2010, pp. 149–152.

    Google Scholar 

  4. Vasil’ev, A.G., Kolkovskii, Yu.V., and Kontsevoi, Yu.A., SVCh pribory i ustroistva na shirokozonnykh poluprovodnikakh (Microwave Wide-Gap Semiconductor Devices), Moscow: Tekhnosfera, 2011.

    Google Scholar 

  5. Boudart, B., Trassaert, S., Wallart, X., Pesant, J.C., Yaradou, O., Théron, D., Crosnier, Y., Lahreche, H., and Omnes, F., Comparison between TiAl and TiAlNiAu ohmic contacts to n-type GaN, J. Electron. Mater., 2000, vol. 29, no. 5, pp. 603–606.

    Article  Google Scholar 

  6. Vanyukhin, K.D., Zakharchenko, R.V., Kargin, N.I., Pashkov, M.V., and Seidman, L.A., Research of structure and surface morphology of two-layer contact Ti/Al metallization, Izv. Vyssh. Uchebn. Zaved., Mater. Elektron. Tekh., 2013, no. 3, pp. 60–65.

    Google Scholar 

  7. Thin Films—Interdiffusion and Reactions, Poate, J.M., Tu, K.N., and Mayer, J.W., Eds., New York: Wiley, 1978.

  8. Feng, Q., Li, L.M., Hao, Y., Ni, J.Y., and Zhang, J.C., The improvement of ohmic contact of Ti/Al/Ni/Au to AlGaN/GaN HEMT by multi-step annealing method, Solid State Electron., 2009, vol. 53, pp. 955–958.

    Article  Google Scholar 

  9. Roccaforte, F., Iucolano, F., Giannazzo, F., Alberti, A., and Raineri, V., Nanoscale carrier transport in Ti/Al/Ni/Au ohmic contacts on AlGaN epilayers grown on Si (111), Appl. Phys. Lett., 2006, vol. 89, no. 2, pp. 022103-1–3.

    Article  Google Scholar 

  10. Bright, A.N., Thomas, P.J., Weyland, M., Tricker, D.M., Humphreys, C.J., and Davies, R., Correlation of contact resistance with microstructure for Au/Ni/Al/Ti/AlGaN/GaN ohmic contacts using transmission electron microscopy, J. Appl. Phys., 2001, vol. 89, no. 6, pp. 3144–3150.

    Article  Google Scholar 

  11. Selvanathan, D., Mohammed, F.M., Tesfayesus, A., and Adesida, I., Comparative study of Ti/Al/Mo/Au, Mo/Al/Mo/Au, and V/Al/Mo/Au ohmic contacts to AlGaN/GaN heterostructures, J. Vac. Sci. Technol. B, 2004, vol. 22, pp. 2409–2416.

    Article  Google Scholar 

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Authors and Affiliations

  1. Institute of Functional Nuclear Electronics, National Research Nuclear University (MEPhI), Kashirskoe sh. 31, Moscow, 115409, Russia

    K. D. Vanyukhin, R. V. Zakharchenko, N. I. Kargin, M. V. Pashkov & L. A. Seidman

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  1. K. D. Vanyukhin
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  2. R. V. Zakharchenko
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  3. N. I. Kargin
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  4. M. V. Pashkov
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  5. L. A. Seidman
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Correspondence to L. A. Seidman.

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Original Russian Text © K.D. Vanyukhin, R.V. Zakharchenko, N.I. Kargin, M.V. Pashkov, L.A. Seidman, 2014, published in Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki, 2014, No. 2, pp. 122–127.

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Vanyukhin, K.D., Zakharchenko, R.V., Kargin, N.I. et al. Processes during annealing of Ti–Al–Ni and Ti–Al–Ni–Au contact metallization systems. Russ Microelectron 44, 564–568 (2015). https://doi.org/10.1134/S1063739715080132

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  • DOI: https://doi.org/10.1134/S1063739715080132

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