Computationally Efficient Design and Optimization

As the semiconductor industry transitions from monolithic system-on-chip architectures to chiplet-based designs, die-to-die interconnects have emerged as a critical determinant of system performance. UCIe-based interfaces must support extremely high bandwidth densities across short physical distances, causing interconnects to exhibit transmission line behavior and introducing significant signal integrity challenges. At the same time, advanced packaging technologies increasingly rely on hatched or patterned ground planes to address manufacturing and yield constraints, fundamentally altering return current behavior and invalidating traditional assumptions of electrically uniform reference planes.

Accurately capturing these effects requires full-wave electromagnetic (EM) simulation. However, applying full-wave methods across complete multi-lane chiplet interconnect buses is computationally prohibitive due to rapidly increasing mesh complexity, memory consumption, and simulation runtime. This limits design iteration and restricts the ability to evaluate alternative routing and ground plane configurations early in the development cycle.

This whitepaper presents a hybrid electromagnetic modeling methodology designed to balance simulation fidelity with computational efficiency. The approach combines selective full-wave EM simulation for critical discontinuities (such as vias, bumps, and breakout regions) with scalable two-dimensional cross-sectional analysis for long, uniform routing segments over patterned ground structures. Using a unit-cell-based representation of hatched ground planes, the methodology captures return current redistribution, impedance variation, and resonance effects while dramatically reducing computational cost.

The paper also introduces the 3D Interconnect Designer, a pre-layout workflow environment that integrates this hybrid methodology into a practical chiplet design flow. Engineers can rapidly define, simulate, and optimize die-to-die interconnect architectures, evaluate signal integrity metrics including insertion loss and crosstalk, and export validated models into system-level simulation environments.

Validation against silicon interposer and PCB test structures demonstrates strong agreement with measured results while achieving substantial reductions in simulation time and memory usage, enabling practical full-bus analysis for next-generation heterogeneous integration systems.