A 3D NAND Flash Ready 8-Bit Convolutional Neural Network Core Demonstrated in a Standard Logic Process

A convolutional neural network (CNN) core that can be readily mapped to a 3D NAND flash array was demonstrated in a standard 65nm CMOS process. Logic compatible embedded flash memory cells were used for storing multi-level synaptic weights while a bit-serial architecture enables 8 bit multiply-and-accumulate operation. A novel back-pattern tolerant program-verify scheme reduces the cell current variation to less than 0.6 mu A. Positive and negative weights are stored in eFlash cells in adjacent bitlines, generating a differential output signal. Our eNAND based neural network core achieves a 98.5% handwritten digit recognition accuracy which is close to the software accuracy of 99.0% for the same precision. This work represents the first physical demonstration of an embedded NAND Flash based neuromorphic chip in a standard logic process.