M. Lane et al.: Plasticity contributions to interface adhesion in thin-film interconnect structures
VI. CONCLUSIONS
where the film thickness (0.25–2.5 m) dominated de-
formation behavior. For thicker metal layers, a transition
region was identified in which the plastic deformation
and associated plastic energy contributions to the interface
fracture energy were no longer dominated by the film thick-
ness. The effects of other salient interface parameters in-
cluding peak cohesive stress and Go were reported.
The effects of plasticity in thin copper metal layers on
the TaN/SiO2 interface fracture energy were measured in
thin-film Cu/TaN/SiO2 structures in which the Cu layer
was varied over a wide range of thicknesses (0.03–
16.4 m). The experimental results allowed an accurate
measurement of Go ס
5 J/m2 with the thinnest Cu layers
where the plasticity contribution was absent. A multi-
scale continuum/FEM model was employed to calculate
the macroscopic fracture energy of the layered structure.
Published Cu thin-film yield properties together with a
plastic flow model were used to accurately predict the
plasticity contribution to interface fracture resistance
ACKNOWLEDGMENTS
This work was supported by the Director, Office of
Energy Research, Office of Basic Energy Sciences, Ma-
terials Science Division of the United States Department
of Energy, under Contract No. DE-FG03-95ER45543,
and by the INTEL and Applied Materials Corporations.
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FIG. 17. Effect of (a) Ro/D and (b) c/ on normalized debond
driving energy.
ys
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