The Shift from Planar to Vertical Packaging

The era of treating advanced packaging as a flat, lateral routing surface is reaching its limit. As AI platforms demand higher bandwidth and greater power density, the industry must move beyond placing chiplets side by side on interposers and toward a vertical realization environment.

Current architectures for GPUs and HBM rely heavily on 2.5D integration, where signals move across substrates or bridges in a largely lateral fashion 3dic/370223-a-tower-like-heterogeneous-packaging-architecture-for-the-ai-era/. This approach works for today's requirements, but the expansion of heterogeneous integration necessitates a new way to manage the physical path where signal integrity, power integrity, and thermal behavior interact. This is the Vertical System EM Corridor.

The transition to verticality introduces significant engineering hurdles. While glass substrates and through-glass vias (TGVs) offer potential for dimensional stability and fine interconnect scaling, vertical routing alone is insufficient. High-speed signals require a return path; without nearby ground-reference TGVs, the industry faces higher loop inductance, impedance discontinuity, and signal integrity degradation.

The fundamental challenge is not merely whether glass can provide vertical vias, but whether this vertical electromagnetic path can become a trusted realization path. A future AI package will likely integrate compute, memory, power delivery, and optical transition zones across multiple vertical regions. While short-reach links like GPU-to-HBM may remain electrical, longer-range movement across the package or rack-level structures will increasingly favor optical transitions.

For architects, the implication is clear: success in the AI era depends on mastering the verticality of the package. We are moving from a period of lateral connectivity to one defined by complex, multi-layered vertical systems.

How will engineers ensure signal integrity remains stable as the EM corridor extends vertically through the package body?