Ultra-reliable packaging for silicon-on-silicon WSI

Silicon-on-silicon WSI (wafer-scale integration) packaging provides electronic equipment with significant reductions in size, weight, cost, and IC junction temperatures, together with significant increases in reliability and high-speed electrical performance. It combines semiconductor lithography techniques, printed-circuit multilayer techniques, and hybrid multichip module techniques. The silicon substrate has multiple layers of metallization and dielectric and services as a silicon circuit board. The author discusses the advantages of using silicon instead of conventional ceramic as the substrate materials and reviews the published status of this technology at other organizations. While conventional hybrid packages are successfully being used in early implementations to reduce size and weight, there exists an untapped potential for significant reliability improvements by switching to packages specifically designed for silicon substrates. Several potential packaging approaches are reviewed and results are presented for the fatigue life and thermal performance of silicon substrates