Comparison of passivation materials for high frequency 3D packaging application up to 110 GHz

For high frequency applications, the electrical circuit performance is strongly related to the quality and loss characteristics of the passivation layer. In this work, we present the comparison of high frequency performances of different passivation materials for in a frequency range up to 110 GHz. The evaluation of the materials is based on measurement of coplanar transmission lines on the redistribution layer and through-silicon-vias, which are the primary interconnects in silicon based 3D systems. Different variations of silicon oxide processes and polymers on both low and high resistivity substrates are considered.