文献类型：期刊文献

英文题名：How are Bubbles Avoiding the Oxide Re-Deposition in Selective Etching of Si3n4 in 3d-Nand Fabrication?

作者：Liu, Bo[1]; Yang, Haiqiang[1]; Zhang, Hao[1]; Yuan, Fang[1]; Yang, Qiang[1]

机构：[1] Department of Mechanical and Power Engineering, East China University of Science and Technology, No. 130 Meilong Road, Lingyunlu Street, Xuhui District, Shanghai, China

年份：2023

外文期刊名：SSRN

收录：EI(收录号：20230101723)

语种：英文

外文关键词：Carbon dioxide - Deposition - Fabrication - Morphology - NAND circuits - Silicon wafers - Wet etching

摘要：Selective etching of Si3N4 is a critical process in the fabrication of 3D-NAND structures; however, it faces a by-product re-deposition problem that significantly deteriorates the remaining structure morphology. A recent study by Kim et al.[1] showed that generating CO2 bubbles during the etching process efficiently solves the re-deposition problem in the fabrication of a 128 multi-layer 3D-NAND structure. In this study, we numerically investigated the multiscale mass transport of byproducts in the etching process to reveal the underlying mechanism. We found that mass transport within the multilayer structures alone cannot contribute to the oxide re-deposition behavior. Macroscopic transport from the wafer-etchant interface to the bulk must be considered. This contributes to a high by-product concentration at the wafer-etchant surface, which further increases the concentration within the slits, leading to the re-deposition problem. The large bubbles generated from the reaction agitate the surrounding liquid and dramatically reduce the surface concentration by one order of magnitude, thereby solving the re-deposition problem. Our findings clearly explain the experimental results reported by Kim et al. and will further benefit the development of process-intensification technologies in wet etching. ? 2023, The Authors. All rights reserved.