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Quantitative analysis of strengthening mechanisms in thin Cu films: Effects of film thickness, grain size, and passivation

Published online by Cambridge University Press:  31 January 2011

R-M. Keller ,
S. P. Baker  and
E. Arzt
R-M. Keller
Affiliation:
Max-Planck-Institut für Metallforschung, and Institut für Metallkunde, University of Stuttgart, Seestrasse 71, D-70174 Stuttgart, Germany
S. P. Baker
Affiliation:
Max-Planck-Institut für Metallforschung, and Institut für Metallkunde, University of Stuttgart, Seestrasse 71, D-70174 Stuttgart, Germany
E. Arzt
Affiliation:
Max-Planck-Institut für Metallforschung, and Institut für Metallkunde, University of Stuttgart, Seestrasse 71, D-70174 Stuttgart, Germany
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Abstract

Thermal stresses in thin Cu films on silicon substrates were examined as a function of film thickness and presence of a silicon nitride passivation layer. At room temperature, tensile stresses increased with decreasing film thickness in qualitative agreement with a dislocation constraint model. However, in order to predict the stress levels, grain-size strengthening, which is shown to follow a Hall–Petch relation, must be superimposed. An alternative explanation is strain-hardening due to the increase in dislocation density, which was measured by x-ray diffraction. At 600 °C, the passivation increases the stress by an order of magnitude; this leads to a substantially different shape of the stress-temperature curves, which now resemble those of aluminum with only a native oxide layer. The effect of passivation is shown to be very sensitive to the deposition and test conditions.

Type
Articles
Information
Journal of Materials Research , Volume 13 , Issue 5 , May 1998 , pp. 1307 - 1317
Copyright
Copyright © Materials Research Society 1998

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