Abstract
This paper proposes to use the high density of vias enabled by monolithic 3D integration to produce multi-stack FPGA designs with improved performance and functionality. The use of fine grain vertical interconnects enables reconfiguration of FPGA logic within a few clock cycles, as shown in our design that features dynamic reconfiguration capabilities through the use of a pair of configuration memories on the upper stack. Along with the reconfigurability feature, results show that our SLICE design offers an area reduction of 23% compared to a standard design without reconfiguration capability. Our analysis of FPGA switch box logic and physical design with M3D vias provides insights into the sources of benefits from vertical routing in a multi-stacked design. We also discuss the design overheads involved in incorporating multiple inter-stack vias for better and faster communication among logic routed in different design stacks.