Research Progress of SiO₂ Regrowth during Selective Etching Process in 3D NAND Manufacture Procedure

Authors

Zi-Han Zhou, 1. College of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
Yun-Wen Wu, 1. College of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
Ming Li, 1. College of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;Follow
Su Wang, 2. Shanghai Sinyang Semiconductor Materials Co., Ltd., Shanghai 201616, China;

Corresponding Author

Ming Li(mingli90@sjtu.edu.cn)

Abstract

As one of the most significant memory chips in semiconductor market, NAND has been developed from two-dimension (2D) to three-dimension (3D). Due to the three-dimensional memory structure of 3D NAND, the capacity density, read-write speed and reliability of memory chips have been greatly improved, as well as the reduction of power dissipation. It is by nitride-oxide selective etching process in the alternate stacked structure of 3D NAND that the inter-dielectric layers can be obtained. The more stack layers, the better performance of chips will be. Meanwhile, however, silicon dioxide (SiO₂) would regrow on the corner of oxide layers, the phenomenon called regrowth, which directly makes damage to the stack structure. If the deposition is so thick that becomes adhesive together, the stack structure will collapse, severely affecting the performance of devices. Preventing SiO₂ regrowth is imperative for higher stacked layers, meaning that the key point is to figure out the specific process of regrowth and its impact factors. Due to the rapid development of this field, the existing information is such a mess that there is a lack of sorted information and systematic research dealing with the problem of regrowth. This paper briefly reviewes developing situation and existing research results of silicon nitride selective etching process in 3D NAND manufacture procedure, with emphases in the significance of controlling silicon concentration to avoid regrowth. Furthermore, relative theoretical models are introduced to provide simulation and prediction for regrowth process. In order to analyze the chemical reaction in regrowth, this paper summarizes the relative solution chemistry of silica and the impact of polysilicic acid formation, and suggests that the gel curve can reflect its aggregation behavior. Accordingly, researches on how to avoid regrowth can be guided theoretically by discovering the influence factors of silicic acid aggregation or the deposition behaviors of polysilicic acid on oxide layers.

Graphical Abstract

Keywords

semiconductor memory, 3D NAND, etching, silicon nitride, silica, silicic acid

DOI Link

https://doi.org/10.13208/j.electrochem.200610

Publication Date

2021-02-28

Online Available Date

2020-12-02

Revised Date

2020-07-13

Received Date

2020-06-11

Recommended Citation

Zi-Han Zhou, Yun-Wen Wu, Ming Li, Su Wang. Research Progress of SiO₂ Regrowth during Selective Etching Process in 3D NAND Manufacture Procedure[J]. Journal of Electrochemistry, 2021 , 27(1): 26-34.
DOI: 10.13208/j.electrochem.200610
Available at: https://jelectrochem.xmu.edu.cn/journal/vol27/iss1/7