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Thermal Stresses in Passivated Copper Interconnects Determined by X-Ray Analysis and Finite Element Modeling

Published online by Cambridge University Press:  22 February 2011

R.P. Vinci ,
E.M. Zielinski  and
J.C. Bravman
R.P. Vinci
Affiliation:
Department of Materials Science, Stanford University, Stanford, CA 94305-2205
E.M. Zielinski
Affiliation:
Department of Materials Science, Stanford University, Stanford, CA 94305-2205
J.C. Bravman
Affiliation:
Department of Materials Science, Stanford University, Stanford, CA 94305-2205
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Abstract

Stresses in passivated copper lines were determined from strains measured using x-ray methods and compared to stresses calculated using finite element methods. Copper lines, 2 µm wide by 0.8 µm thick, were fabricated by DC magnetron sputtering and lift off patterning. The cross section of these lines was trapezoidal, with approximately 50° sidewalls. One set of samples was left bare, the others passivated with Si3N4 in several different thicknesses. Strain was determined using x-rays. Stress was calculated using elastic moduli adjusted for predominantly (111) fiber texture. Elastic-plastic finite element models provided comparisons of the effects of passivation thickness, rectangular and trapezoidal cross section, and mechanical anisotropy due to preferred texture on the hydrostatic stress in a line. A similar model for aluminum also provided a comparison case of stress as a function of passivation thickness.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 338: Symposium – Materials Reliability in Microelectronics IV , 1994 , 289
Copyright
Copyright © Materials Research Society 1994

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References

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