Hostname: page-component-6bf8c574d5-t27h7 Total loading time: 0 Render date: 2025-02-15T09:17:10.264Z Has data issue: false hasContentIssue false
  • English
  • Français

Diffusional Hillock Formation in Al Thin Films Controlled by Creep

Published online by Cambridge University Press:  10 February 2011

Deok-kee Kim ,
William D. Nix ,
Eduard Arzt ,
Michael D. Deal  and
James D. Plummer
Deok-kee Kim
Affiliation:
Center for Integrated Systems, Stanford University, Stanford, CA
William D. Nix
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA
Eduard Arzt
Affiliation:
Max-Planck-Institut für Metallforschung, Stuttgart, Germany
Michael D. Deal
Affiliation:
Center for Integrated Systems, Stanford University, Stanford, CA
James D. Plummer
Affiliation:
Center for Integrated Systems, Stanford University, Stanford, CA
Get access

Abstract

Thermal hillocks in sputter-deposited Al films have been studied as a part of a broad study of stress-induced diffusional processes in Al. Trace amounts of the impurities Ti, W, and O were incorporated into the films during deposition, causing them to be much stronger than most sputter deposited Al films. Stress measurement during thermal cycling, using the wafer curvature method, showed that these Al films are very strong; this finding was corroborated by hardness measurements. Microstructural studies using TEM and FIB showed that the hillocks start to form at the Al/SiO2 interface and grow under the original Al film, with its columnar grain structure. In some cases, the film fails as hillocks grow completely through the original film. The Al film on top of the hillocks appears to inhibit hillock growth by creating a back pressure associated with power law creep of the film. We modeled this form of hillock formation by modifying the boundary conditions in Chaudhari's hillock model [1]. Our model describes hillock formation by diffusion of Al atoms from the surrounding area into isolated hillocks, assuming that the original Al film on top of hillocks deforms following power law creep. Our model can be applied to many different situations by using different creep laws for the top Al film.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 594: Symposium V – Thin Films - Stresses & Mechanical Properties VIII , 1999 , 129
Copyright
Copyright © Materials Research Society 2000

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Chaudhari, P., J. Appl. Phy. 45, 4339 (1974)Google Scholar
2. Nix, W. D., Metall. Trans. A 20, 2217 (1989)Google Scholar
3. Chang, C. Y. and Vook, R. W., Thin Solid films 228, 205 (1993)Google Scholar
4. Gerth, D., Datzer, D. and Schwarzer, R., Mater. Sci. Forum 94–96, 557 (1992)Google Scholar
5. Iwamura, E., Ohnishi, T., Yoshikawa, K., Thin Solid Films 270,450 (1995)Google Scholar
6. Venkatraman, R., Chen, S., and Bravman, J. C., J. Vac. Sci. Technol. A 9, 2536 (1991)Google Scholar
7. Griffin, A. J. Jr., Brotzen, F. R., and Dunn, C. F., Thin Solid Films 150, 237 (1987)Google Scholar
8. Venkatraman, R., dissertation, Ph. D., Stanford University (1992)Google Scholar
9. Besser, P. R., Bader, S., Venkatraman, R., and Bravman, J. C., Mat. Res. Soc. Symp. Proc. 309, 255 (1993)Google Scholar
10. Kim, D.-K., Nix, W. D., Deal, M. D., Plummer, J. D., “Creep-controlled diffusional hillock formation in blanket aluminum thin films as a mechanism of stress relaxation” (submitted to J. Mat. Res.)Google Scholar
11. Kim, D.-K., Heiland, B., Nix, W. D., Arzt, E., Deal, M. D., and Plummer, J. D., “Microstructure of Thermal Hillocks on Blanket Al Thin Films”, (submitted to Thin Solid Films)Google Scholar
12. Hamilton, C. H., Bampton, C. C., and Paton, N. E., Conference Proceedings of the Metallurgical Society of AIME (Superplastic Forming of Structural Alloys), 173 (1982)Google Scholar
13. Frost, H. J. and Ashby, M. F., Deformation-Mechanism Maps, Pergamon Press, 21 (1982)Google Scholar