Stress Evolution in Thin Films; Diffusion and Reactions

Abstract:

After a brief discussion of possible mechanisms of stress generation in thin film diffusion/reaction couples, two recent experimental examples are reviewed: (i) Thin film diffusion couples (Pd-Cu, individual layer thicknesses: 50nm) prepared by DC-magnetron sputtering on silicon substrates. The microstructural development, phase formation and the stress evolution during diffusion annealing have been investigated employing Auger-electron spectroscopy in combination with sputter depth profiling, transmission electron microscopy, in-situ wafer-curvature measurements and ex-situ and, in particular, in-situ X-ray diffraction measurements. (ii) Tin layers on copper substrates (layer thicknesses of some microns) prepared by electrodeposition. Upon storage at ambient temperatures, Cu diffuses into the Sn layer and forms the intermetallic phase η’- Cu6Sn5. The phase formation is accompanied by a volume expansion and as a consequence, compressive residual stresses can be generated in the Sn layers. These compressive residual stresses may drive the formation of Sn whiskers on the Sn surface. The microstructural development, phase formation and the stress evolution during diffusion annealing have been investigated employing scanning electron and focused ion beam microscopy, metallography and ex-situ and, in particular, in-situ X-ray diffraction measurements.

• Periodical: Defect and Diffusion Forum (Volume 264)
• Pages: 71-78
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.264.71
• Online since: April 2007
• Authors: U. Welzel, Eric Jan Mittemeijer
• Keywords: Diffusion, Metal Thin Films, Sn Coatings, Stress, Whisker Growth, X-Ray Diffraction (XRD)

References

[1] B. Okolo, P. Lamparter, U. Welzel, T. Wagner and E.J. Mittemeijer: Thin Solid Films Vol. 474 (2005), p.50.

DOI: 10.1016/j.tsf.2004.08.006

[2] B. Okolo, P. Lamparter, U. Welzel and E.J. Mittemeijer: J. Appl. Phys. Vol. 95 (2) (2004), p.466.

[3] J.C.M. Li: Metall. Trans. A Vol. 9A (1978), p.1353.

[4] D.W. Stevens and G.W. Powell: Metall. Trans. A Vol. 8 (10) (1977), p.1531.

[5] U. Welzel, P. Lamparter, M. Leoni and E.J. Mittemeijer: Mater. Sci. Forum Vol. 347-349 (2000), p.405.

DOI: 10.4028/www.scientific.net/msf.347-349.405

[6] U. Welzel, P. Lamparter and E.J. Mittemeijer: Mater. Res. Soc. Symp. Proc. Vol. 562 (1999), p.147.

[7] F. C. Larché and J.W. Cahn: Acta Metall. Vol. 30 (1982), p.1835.

[8] P.G. Shewmon: Diffusion in Solids, (TMS Publication U.S.A. 1989).

[9] F.C. Larché and J.W. Cahn: Acta Metall. Vol. 33 (1985), p.331.

[10] N. Balandina, B.S. Bokstein, A. Ostrovsky, V. Ivanov, A.L. Petelin and S. Petelin: Defect and Diffusion Forum Vol. 143 (1997), p.1499.

DOI: 10.4028/www.scientific.net/ddf.143-147.1499

[11] A.S. Ostrovsky and B.S. Bokstein: Appl. Surf. Sci. Vol. 175 (2001), p.312.

[12] P. Chaudhari: J. Vac. Sci. and Tech. Vol. 9 (1972), p.520.

[13] M.F. Doerner and W.D. Nix : Critical Reviews in Solid State and Materials Sciences Vol. 14 (1988) p.225.

[14] A.H. King and K.E. Harris: Mater. Res. Soc. Symp. Proc. Vol. 343 (1994), p.33.

[15] E. Arzt: Acta Mater. Vol. 46 (1998), 5611.

[16] J. Chakraborty, U. Welzel and E. J. Mittemeijer: to be submitted.

[17] J. Chakraborty, U. Welzel and E. J. Mittemeijer: to be submitted.

[18] Y. Kuru, M. Wohlschlögel, U. Welzel and E. J. Mittemeijer: to be submitted.

[19] M. Wohlschlögel, U. Welzel, G. Maier and E. J. Mittemeijer: J. Appl. Cryst. Vol. 39 (2006), p.194.

[20] U. Welzel, J. Ligot, P. Lamparter, A. C. Vermeulen and E. J. Mittemeijer: J. Appl. Cryst. Vol. 38 (2005), p.1.

[21] S. Hofmann: Surf. Interface Anal. Vol. 21 (1994) p.673.

[22] J.Y. Wang and E.J. Mittemeijer: J. Mater. Res. Vol. 19 (2004) p.3389.

[23] W. F. Gale and T. C. Totemeier: Smithells Metals Reference Book, (Elsevier U.S.A. 2004).

[24] R. Schuster, Diploma Thesis Whiskerbildung im System Kupfer-Zinn, Universität Stuttgart (2006).

[25] K.N. Tu: Phys. Rev. B Vol. 49 (1994) p. (2030).

[26] K.N. Tu: Materials Chemistry and Physics Vol. 46 (1996).