R&D: Modeling and Optimization of Structural Tuning in Bandgap-Engineered Tunneling Oxide for 3D NAND Flash Application

Electronics has published an article written by Zhihong Xu, Shibo Xie, Zhijun Ying, Wenlong Zhang, and Liming Gao, State Key Laboratory of Metal Matrix Composites, School of Material Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.

Abstract: “The bandgap-engineered tunneling oxide (BE-TOX) structure has been proposed to address the incompatibility between erase efficiency and retention performance in NAND flash memory. Previous studies have primarily focused on single flash memory cells, whose architecture significantly differs from that of 3D NAND flash memory. Thus, the BE-TOX structure requires further research and optimization to improve device performance. In this study, the impact of varying proportions of the SiO₂/SiO_xN_y/SiO₂ (O1/N/O2) structure on performance is investigated using Technology Computer-Aided Design (TCAD) simulations. The results indicate that as the thickness of the N layer increases, the program/erase (P/E) speed improves, but reliability deteriorates. By adjusting the ratio of the O1 and O2 layers, the P/E speed can be optimized, and an optimal thickness can be identified. The simulation results demonstrate that the phenomenon is attributed to the combined effects of different barrier heights for charge tunneling and variations in band bending across the material layers. This study paves the way for further designing BE-TOX structures with balanced P/E performance and reliability.“