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Title: Electrical Modeling, Design and Characterization of Tapered Through-package-vias in Glass Interposers for High-performance Applications
Committee:
Dr. Tummala, , Advisor
Dr. Peterson, Chair
Dr. Brand
Dr. Sundaram
Abstract: The objective of the proposed research is to study the effect of TPV taper on the electrical parameters for high-performance glass interposers, leading to TPV specifications for a variety of applications and tapered TPV design guidelines. To achieve these goals, three main research challenges are identified. (a) Equivalent circuit model for tapered TPVs in glass is needed for circuit simulators to reduce the design cycle, while high-accuracy modeling is required to capture the taper shape in μm regime, . (b) Signal transition between layers enabled by TPVs typically suffers impedance discontinuity, and TPVs placed at fine pitch in glass interposers have crosstalk noise. Minimizing them are the main concerns for the TPV design. (c) Given the wide bandwidth requirement for high performance, high-frequency and high-precision experimental characterization is needed to validate the TPV model and the design. To address these challenges, three research tasks are proposed and carried out. (a) A wideband scalable circuit model for tapered TPVs in glass interposers has been proposed, and it has been verified against a 3D electromagnetic (EM) solver with the differences of S21 magnitude and S21 phases being less than 0.01 dB and 1 deg, respectively. (b) A comparative study has been performed between TSVs in silicon and TPVs in glass, LTCC and LCP, covering electromagnetic field distributions, self-impedances, and insertion losses. (c) A low-cost panel-based novel process has been developed for metallizing high-aspect-ratio tapered TPVs in glass interposers, and a ring-resonator method was used as the characterization approach, along with detailed fundamental analysis.
