Impact of channel tapering on threshold voltage variation in multi-layer word line 3 dimensional NAND structures

Abstract

This work investigates the problems caused by the new multi-layer word line (WL) counts in 3D NAND flash memory, a technology that radically changes conventional memory designs. This study explores the effects of channel doping and taper angle on the electrical properties of vertical 3D NAND Flash memory to deliver issues related to increasing overall mold height and channel tapering. Operating Sentaurus technology computer-aided design (TCAD) tools, the investigation inspects the threshold voltage (Vth) appropriation among word lines (WLs) along the string. The goal is to assess current difficulties and propose a viable way to deal with achieving stable Vth dissemination. This includes breaking down the impacts of various shape points and channel doping levels on the electrical attributes of vertical 3D NAND flash memory. The results are expected to help improve the technology behind 3D NAND Flash memory.