Monolithic 3D Integrated Circuits

3D IC's promise to solve the 2D communication bottleneck, and enable the integration of heterogeneous materials, devices and systems. There are at least three approaches to realize 3D IC's : chip stacking, wafer stacking and full monolithic integration. Each approach is at a different level of maturity and offers various degree of improvement. This paper will focus on the monolithic 3D approach, which offers a high density of device-dimension vertical interconnects and thereby facilitates the optimal assembly of transistors and interconnects in a 3D volume. The performance advantages of such a technology are demonstrated with a 3D-FPGA. Technology challenges of monolithic approach are discussed.