Simultaneous Formation of Ohmic Contacts for Both N- and P-Type 4H-Sic Using Nial-Based Contact Materials

Abstract

In order to simplify a fabrication process of silicon carbide power MOSFETs (metal oxide semiconductor field effect transistors), development of a simultaneous formation process of ohmic contacts to both the p-well and n-source regions of the SiC devices using same contact materials and one step annealing was challenged. We succeeded to develop NiAl-based contact materials which provided ohmic behaviors for both n- and p-type 4H-SiC after one step annealing. The Ni/Al and Ni/Ti/Al ohmic contacts were prepared by depositing sequentially Ni, (Ti) and Al layers with various layer thicknesses onto the n- and p-type SiC substrates which were doped with N at 1×1019 cm−3 and with Al at 8×1018 cm−3, respectively. The Ni(50 nm)/Al(5 ~ 6 nm) contacts showed ohmic behaviors for both the n- and p-type SiC substrates after annealing at 1000 °C. The Ni(20 nm)/Ti(50 nm)/Al(50 ~ 70 nm) contacts showed ohmic behaviors for both the n- and p-type SiC substrates after annealing at a lower temperature of 800 °C. The specific contact resistances of these contacts were measured to be in the order of 10−3 Ω-cm2 for both p- and n-type SiC, and were found to have strong dependence of the Al layer thicknesses of materials. The interfacial microstructures of the NiAl-based contacts were also observed by transmission electron microscopy (TEM) to understand the current transport mechanism through the metal/SiC interfaces.

This is a preview of subscription content, access via your institution.

References

  1. 1

    J. Crofton, L.M. Porter, and J.R. Williams, Phys. Status Solidi B 202, 581 (1997).

    CAS  Article  Google Scholar 

  2. 2

    V.R. Vathulya, and M.H. White, IEEE Trans. Electron Devices 47, 2018 (2000).

    CAS  Article  Google Scholar 

  3. 3

    L.G. Fursin, J.H. Zhao, and M. Weiner, Electron. Lett. 37, 1092 (2001).

    CAS  Article  Google Scholar 

  4. 4

    S. Tanimoto, N. Kiritani, M. Hoshi, and H. Okushi, Mater. Sci. Forum 389, 879 (2002).

    Article  Google Scholar 

  5. 5

    N. Kiritani, M. Hoshi, S. Tanimoto, K. Adachi, S. Nishizawa, T. Yatsuo, H. Okushi, and K. Arai, Mater. Sci. Forum 433-436, 669 (2003).

    Article  Google Scholar 

  6. 6

    J. Crofton, P.G. McMullin, J.R. Williams and M.J. Bozack, J. Appl.Phys.77,1317(1995).

    CAS  Article  Google Scholar 

  7. 7

    J. Crofton, P.A. Barnes, J.R. Williams and J.A. Edmond, Appl. Phys.Lett. 62, 384(1993).

    CAS  Article  Google Scholar 

  8. 8

    O. Nakatsuka, T. Takei, Y. Koide, and M. Murakami, Mater. Trans. 43, 1684 (2002).

    CAS  Article  Google Scholar 

  9. 9

    S. Tsukimoto, K. Nitta, T. Sakai, M. Moriyama and M. Murakami, J. Electron. Mater. 33, 460 (2004).

    CAS  Article  Google Scholar 

  10. 10

    J. Crofton, L. Beyer, J.R. Williams, E.D. Luckowski, S.E. Mohney, and J.M. Delucca, Solid-State Electron. 41, 1725 (1997).

    CAS  Article  Google Scholar 

  11. 11

    J. Crofton, S.E. Mohney, J.R. Williams, and T. Isaacs-Smith, Solid-State Electron. 46, 109 (2002).

    CAS  Article  Google Scholar 

  12. 12

    R. Konishi, R. Yasukochi, O. Nakatsuka, Y. Koide, M. Moriyama, and M. Murakami, Mater. Sci. Eng. B 98, 286 (2003).

    Article  Google Scholar 

  13. 13

    Ts. Marinova, R. Yakimova, V. krastev, C. Hallin, and E. Janzén, J. Vac. Sci. Technol. B 14, 3252 (1996).

    CAS  Article  Google Scholar 

  14. 14

    Y. Gao, Y. Tang, M. Hoshi, and T.P. Chow, Solid-state Electronics 44, 1875 (2000).

    CAS  Article  Google Scholar 

  15. 15

    S. Tsukimoto, T. Sakai, T. Onishi, K. Ito, and Masanori Murakmai, J. Electron. Mater. 34, 1310 (2005).

    CAS  Article  Google Scholar 

  16. 16

    B. Pécz, Appl. Surf. Sci. 184, 287 (2001).

    Article  Google Scholar 

  17. 17

    K.W. Richter, K. Chandrasekaran, and H. Ipser, Intermetallics 12, 545 (2004).

    CAS  Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Tsukimoto, S., Onishi, T., Ito, K. et al. Simultaneous Formation of Ohmic Contacts for Both N- and P-Type 4H-Sic Using Nial-Based Contact Materials. MRS Online Proceedings Library 911, 1105 (2005). https://doi.org/10.1557/PROC-0911-B11-05

Download citation