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Thermoplastic Deformation and Residual Stress Topography of 4H-SiC Wafers

Published online by Cambridge University Press:  15 March 2011

Robert. S. Okojie  and
Ming Zhang
Robert. S. Okojie
Affiliation:
NASA Glenn Research Center, 21000 Brookpark Road, M/S 77-1, Cleveland, OH 44135, USA
Ming Zhang
Affiliation:
Department of Materials Science & Engineering, CWRU, Cleveland, OH 44106, USA
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Abstract

We have measured thermoplastic deformation in as-received, single-side polished, 4H-SiC wafers and also residual stresses in homoepitaxially grown epilayers on wafers by radius curvature measurements. The wafers studied had n-type resistivities of 0.010-0.011 ω-cm and p-type resistivities of 4.42, 4.72, 9.57 ω-cm. In a first thermal excursion to 900 °C in vacuum, the bow height of the bare substrates in all cases decreased with temperature. Upon cooling down, however, the bow heights remained largely unchanged from their values at 900 °C. A second cyclic excursion to 900 °C did not yield any significant change in the curvature, thus indicating that the substrates had thermoplastically deformed in the first heating cycle. Epilayers having nitrogen doping between 5 × 1017 and 2 × 1019 cm−3 grown on the n- and p-type substrates resulted in compressive stresses ranging between 190 and 400 MPa in the epilayers. Transmission electron microscopy (TEM) examination of the n-type epilayer (with doping levels of 5 × 1017 cm−3 and 5 × 1018 cm−3) on the n-type substrate, revealed bands of stacking faults (SFs) confined within the epilayers after the bicrystals were further annealed at 1150°C in nitrogen for thirty minutes. These doping levels are approximately one and two orders of magnitude below the reported threshold value of 3 × 1019 cm−3 previously suggested for the onset generation of SFs in annealed n-type 4H-SiC epilayers. The calculated residual stresses in all the epilayers were above the critical stress for the motion of dislocations above 1000 °C in 4H-SiC. Thus the SFs that form by glide of pre-existing partial dislocations may actually be stress induced and occur across a much wider range of doping levels. Therefore, it is possible that a significant mechanism for formation of the stacking faults and 3C bands observed in thermally treated 4H-SiC wafer is stress relief via the generation and motion of new and pre-existing partial dislocations on the basal planes of 4H-SiC.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 815 , 2004 , J6.2
Copyright
Copyright © Materials Research Society 2004

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References

[1] Tatsumi, M., Hosokawa, Y., Iwasaki, T., Toyoda, N., and Fujita, K., Mat. Sci. and Eng. B 28, 65–71 (1994).Google Scholar
[2] Neudeck, P. G., in The VLSI Handbook, edited by Chen, W.-K. (CRC Press and IEEE Press, Boca Raton, Florida, 2000), p. 6.1–6.24.Google Scholar
[3] Müller, S. G., Glass, R. C., Hobgood, H. M., Tsvetkov, V. F., Brady, M., Henshall, D., Jenny, J. R., Malta, D., and Carter, C. H., J. Cryst. Growth 211, 325–332 (2000).Google Scholar
[4] Tsvetkov, V. F., Henshall, D. N., Brady, M. F., Glass, R. C., and Carter, J. C. H., (Mater. Res. Soc. Proc. 512, Pittsburgh, PA 1998) pp. 89–99.Google Scholar
[5] Hong, M. H., Samant, A. V., and Pirouz, P., “Stacking Fault Energy of 6H-SiC and 4H-SiC Single Crystals”, Phil. Mag. A, 80(4), 919–935 (2000).Google Scholar
[6] Lendenmann, H., Dahlquist, F., Johansson, N., Bergman, J., Bleichner, H., and Ovren, C., in Performance and Reliability of High Power SiC Diodes, Nara Centennial Hall, Nara Japan, 2000 (Research and Development Association for Future Electron Devices), p. 125–130.Google Scholar
[7] Okojie, R., Xhang, M., Pirouz, P., Tumakha, S., Jessen, G., and Brillson, L., Mater. Sci. Forum 389–393, 451–454 (2002).Google Scholar
[8] Skromme, B. J., Palle, K., Poweleit, C. D., Bryant, L. R., Vetter, W. M., Dudley, M., Moore, K., and Gehoski, T., Mater. Sci. Forum, 389–393, p. 455 (2001).Google Scholar
[9] Lindefelt, U., Iwata, H., Öberg, S., and Briddon, P. R., Phys. Rev. B 67, 155204 (2003).Google Scholar
[10] Miao, M. S., Limpijumnong, S., and Lambrecht, W. R. L., Appl. Phys. Lett. 79, 4360–4362 (2001).Google Scholar
[11] Liu, J. Q., Chung, H. J., Kuhr, T., Li, Q., and Skowronski, M., Appl. Phys. Lett. 80, 2111–2113 (2002).Google Scholar
[12] Kuhr, T. A., Liu, J., Chung, H. J., Skowronski, M., and Szmulowic, F., J. Appl. Phys. 92, 5863–5871 (2002).Google Scholar
[13] Cree, in 4600 Silicon Drive, 27703 ed. (Durham, NC).Google Scholar
[14] Frontier Semiconductor, Inc, 1631 North First Street, San Jose, CA 95112 USA. (www.frontiersemi.com).Google Scholar
[15] Okojie, R. S., Xhang, M., and Pirouz, P., to be published in the Proceedings of the International Conference on Silicon Carbide and Related Materials, October 5-10, 2003, Lyon, France.Google Scholar
[16] Ohring, M., The Materials Science of Thin Films, Academic Press, Inc., New York. (1992).Google Scholar
[17] Ellison, A., Radamson, H., Tuominen, M., Milita, S., Hallin, C., Henry, A., Kordina, O., Tuomi, T., Yakimova, R., Madar, R., and Janzen, E., Diamond and Related Materials 6, 1369–1373 (1997).Google Scholar
[18] Hull, D. and Bacon, D. J., Introduction to Dislocations, Fourth ed. (Butterworth-Heinemann, Woburn, 2001).Google Scholar