Manufacturing Technologies for Three-Dimensional Integrated Circuits

The manufacturing processes that enable three-dimensional (3-D) integrated systems, where the interconnections between the noncoplanar circuits are achieved by short vertical vias, are described in this chapter. These interconnect schemes provide the greatest reduction in wirelength and, therefore, the largest improvement in speed and power consumption. Specific fabrication processes that have been successfully developed for 3-D circuits are reviewed. The material in this chapter reviews three alternative approaches for 3-D integration. Monolithic integration that supports transistor level integration, which provides the highest device density, is described first. An extensive discussion on the stacking of circuits with through silicon vias follows, including a review of the diverse fabrication approaches and bonding styles between the circuit tiers. Contactless methods for intertier communication through AC coupling are also briefly reviewed.