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.