Mechanical Stress Distribution and the Effects of Process Parameter Changes in Vertical NAND Flash Memory

Abstract

We investigated the stress distribution and electrical characteristics according to changes in the process parameters in a vertical NAND (VNAND) flash cell with a poly-Si channel. We used technology computer-aided design to confirm that process parameters changes affect the stress distribution in a VNAND flash cell and the stress in the poly-Si channel. Also, we found that, as the stress distributions changed, the electrical characteristics depended significantly on the annealing temperature, channel hole angle, and tungsten intrinsic stress in a VNAND flash cell. Thus, the industry needs to develop and apply better process parameters and acquire a better understanding of how the electrical characteristics of a VNAND flash cell depend on those parameters.