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?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：20230074151)

语种：英文

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

摘要：The selective etching of SI3N4 is a critical process in the fabrication of the 3D-NAND structures but faces the by-product re-deposition problem that significantly worsens the remaining structure morphology. A recent work by Kim et al.[1] show that generating CO2 bubbles in the etching process can efficiently solve the re-deposition problem in fabricating a 128 multi-layer 3D-NAND structure. In this work, we numerically studied the multi-scale mass transport of by-products in the etching process to unveil the underlying mechanism. We found that mass transport within the multi-layer structures alone cannot contribute to the oxide re-deposition behavior. The macroscopic transport from the wafer-etchant interface to the bulk must be considered. It contributes to a high by-product concentration at the wafer-etchant surface, which further increases the concentration within the slits that leading to the re-deposition problem. The reaction-generated large bubbles agitated the surrounding liquid and dramatically reduced the surface concentration by one order of magnitude, solving the re-deposition problem. Our findings clearly explain the experimental results of Kim et al. and would benefit the further development of process intensification technologies in wet etching. ? 2023, The Authors. All rights reserved.