5.5.3  Summary and Conclusion

The stress development in the metal layers of the unfilled TSVs during the thermal processing cycle was investigated. A modeling methodology was developed to include low-temperature plastic deformation by dislocation glide in FEM simulations. Additionally, a procedure to obtain the model parameters was described and the parameters for a tungsten thin film were determined. The simulated results were verified through comparison with experiments, proving the validity of the approach. The stress inside the TSV follows a particular evolution due to the influence of geometry deformations during temperature variation. Finally, a critical scenario for the mechanical reliability of the structure was found, which is defined by the valleys between the scallops in the middle of the TSV during the structure heating.