Design and Electromagnetic Modeling of TSV-Integrated Transmon Qubits for Improved Control and Reduced Loss

3D integration of superconducting qubits offers a path toward scalable quantum processors by increasing package density and enabling vertical signal routing. However, the inclusion of through-silicon vias (TSVs) introduces potential loss mechanisms that can limit coherence and control fidelity. We present a parametric electromagnetic study of superconducting TiN-based TSVs integrated within transmon architectures to quantify geometry-dependent impacts on microwave performance. Using full-wave simulations, we evaluate field confinement and crosstalk, benchmarking them against planar designs. We additionally extract participation ratios to assess loss contributions associated with TiN surfaces and silicon interfaces. By linking TSV geometry and material parameters to loss participation and crosstalk, we establish quantitative trends that inform the design of scalable, low-loss superconducting qubits.