Electrical characterization of a novel coaxial die-to-die interconnect

This paper presents the electrical modeling and characterization of a new chip-to-chip interconnect scheme consisting of miniature coaxial cables. A Micro-Electrical-Mechanical System (MEMS) etching process is used to create trenches along the perimeter of a Silicon substrate to form interface features for the miniature coaxial cables. The coaxial cables use this transition trench to make contact to coplanar transmission lines implemented on-chip. This technique yields a fully impedance matched system for use in high speed signal propagation between dies. This approach promises to deliver higher signaling performance over the traditional wire bond or flip-chip bumping techniques by reducing or eliminating sources of electrical noise such as reflections, cross-talk, and simultaneous switching noise. This paper presents the electrical characterization of prototypes which were fabricated using this interconnect system. Adjacently placed dies are measured when using the new coaxial interconnect approach and compared to measurements of the same system when using wire-bonding. Finite Element Analysis is used to de-embed the system response to yield a comparison of the two interconnect structures (coaxial vs. wire bond).