Investigation of the Memory Operations in the 3D NAND Flash with More Realistic Geometry with Wavey Channel in the Tapered Channel Hole

Abstract

Recent developments in 3D NAND flash memory technology have greatly enhanced memory capacity and integration density compared to 2D NAND, addressing the growing demand for high-performance storage in various fields. This study investigates the effects of wavey shape factor (WF) and taper angle on the programming characteristics of 3D NAND flash memory by a series of technology computer-aided design (TCAD) device simulations. Our analysis reveals that both WF and taper angle significantly impact the threshold voltage (VTH) and trapped charge in memory cells. Specifically, as the taper angle increases, the bottom memory cell experiences more pronounced variations in VTH and trapped charge due to a smaller channel radius and altered electric field distribution. This study also shows that larger taper angles affect the tunneling oxide region more significantly than the blocking oxide region, leading to greater performance variations. These investigations highlight the need for optimized design strategies to minimize performance non-uniformity and improve the reliability of next-generation NAND memory technologies.