Nonvolatile 3D-FPGA with monolithically stacked RRAM-based configuration memory

SRAM based configuration memory is the primary contributor to the large area, delay, and power consumption of FPGAs relative to ASICs. In [1] it is estimated that a 3D-FPGA with the configuration memory stacked on top of the FPGA logic and routing can achieve 57% smaller die area than a baseline 2D-FPGA in 65nm CMOS technology. Motivated by these potential performance gains, several programmable logic devices with different monolithically stacked configuration memory technologies have been reported [2-4]. These memory technologies, however, require materials and/or processes that may not be compatible or scalable with CMOS processes. This paper presents the first 3D-FPGA with stacked configuration memory based on the emerging nonvolatile Resistive RAM (RRAM) technology described in [5], which is both compatible and scalable with CMOS.