Investigation of Program and Reliability Characteristics of Concave and Convex Structures for Advanced 3D NAND Flash Memory Technology

Abstract

Investigation of Program and Reliability Characteristics of Concave and Convex Structure for Advanced 3D NAND Flash Memory Technology Jiho Song Dept. of Electronics Engineering The Graduate School Hanyang University In the NAND flash memory industry, scaling down the 3D NAND flash memory cells to increase bit density has various limitations, such as program performance degradation and reliability issues. To overcome these limitations, many cell structures have been reported through prior research, and we investigated the program and reliability characteristics of convex and concave structures as the promising candidates for advanced 3D NAND Flash memory in this paper. The program characteristics of the convex structure have a confined trapped charge distribution because the electric field was concentrated in the cell region, leading to better characteristics than a conventional structure. On the other hand, in the concave structure, the electric field was dispersed and an inter-cell charge trapping in spacer region was occurred, which led to degradation of the program performance. For the reliability characteristics, the convex structure showed improved interference characteristics because of the confined trapped charge characteristics, and the concave structure was improved for the read disturbance. Overall, the convex structure with a recess thickness of 1.0 nm or less had the most optimal program and reliability characteristics compared with the conventional structure.