Optimization of Programming Pulse Shape for Vertical NAND Flash Memory Using Neural Networks
Sungho Park, Jaehyeon Kim, Jonghyun Ko, Jiseong Im, Yeongheon Yang, Jae‐Joon Kim, Jong‐Ho Lee
Abstract
We optimize the shape of the pulse to maximally increase threshold voltage (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}\text {)}$ </tex-math></inline-formula> during the incremental step pulse programming (ISPP) of vertical NAND (V-NAND) flash memory using neural networks (NNs). NN is trained using data on the increase in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> of commercial V-NAND flash memory in response to randomly shaped programming pulses (PPs). The trained NN is utilized to optimize the shape of the PP. The principle behind the improvement in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> increase due to the optimized PP, as well as the improvement results, are confirmed through measurements. When the optimized PP is applied to ISPP operation, it results in a 37% increase in ISPP slope. Furthermore, the optimized PP exhibits lower program disturbance, indicating the potential for faster programming with lower energy consumption.