ABF-Based TSV Arrays With Improved Signal Integrity on 3-D IC/Interposers: Equivalent Models and Experiments

An Ajinomoto-Build-up-Film (ABF) material is proposed to manufacture through-silicon vias (TSVs) with better signal integrity and lower cost than that of conventional TSVs. The unique advantage of the ABF-based TSVs is that the isolation layer can be thicker than the conventional TSVs, and thus both the insertion loss and crosstalk of the ABF-based TSVs can be improved. An equivalent circuit model is given to predict the electrical behavior of the TSVs and to explain how ratio of the isolation layer's thickness to the radius affects the signal integrity. The concept is demonstrated both in frequency- and time-domain simulations. Finally, a test sample of nine-stack ABF-based TSVs is fabricated and assembled. The scanning electron microscope figure supports that the ABF-based TSVs have a thickness-to-radius ratio of 0.667, which is much higher than the conventional TSVs ratio of about 0.1. The measurements also support the simulated results from the equivalent circuit model.