Low slow-wave effect and crosstalk for low-cost ABF-coated TSVs in 3-D IC interposer

A solution for reducing the signal distortion in SiO2-coated through silicon vias (TSVs) is proposed. The mechanism can be explained by using a verified equivalent circuit model of a four-TSV system. Based on this circuit model, the phenomena that larger thickness of dielectric layer causes lower slow-wave factor (SWF), smaller insertion loss and smaller crosstalk level can be observed. With the aid of ajinomoto-build-up-film-coated (ABF-coated) TSVs, the solution can be implemented. The insertion loss is 3 dB better, the near-end crosstalk is 5 dB better, and the far-end crosstalk is 25dB better than conventional SiO2-coated TSVs at 2 GHz. Measurement results are also given. Good consistency can be seen, and can support the conclusion of the simulation results.