Asymmetric etching profile control during high aspect ratio Plasma etch

Yang, Zusing; Wu, Li-Ian; Chang, Sheng-Yuan; Chiu, Yuan-Chieh; Lee, Hong-Ji; Lian, Nan-Tzu; Yang, Tahone; Chen, Kuang-Chao; Lu, Chih‐Yuan; Watanabe, Haruyuki; Cheng, Yinhwa; Arase, Takao; Mori, Masahito

doi:10.1109/asmc.2018.8373146

Cited by 2 publications

(2 citation statements)

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“…Charges were trapped in bottom N/O film layers during CH etch process and lead to etch plasma tilt which cause CSL slit tilting (figure 5). After the long-time CH etching process, positive ion charges were accumulated near the bottom layers [14,17] and would trapped in bottom N/O films. After that, charges would accumulate around CH in poly-Si channels deposited process due to antenna effect [22,23].…”

Section: Methodsmentioning

confidence: 99%

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Influence of accumulated charges on deep trench etch process in 3D NAND memory

Chen

Wu²,

Chuan³

et al. 2020

Semicond. Sci. Technol.

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Channel holes (CH) and common source line (CSL) etch are two of key process challenges in 3D NAND. With the increase of stacked layers, the aspect ratio become larger than 50:1. One of key issues is CSL tilting to CH, leading to serious word-line leakage and block fail in array. In this work, it is demonstrated that trapped charges brought by CH etch process can affect the CSL slit etch process seriously, and lead to CSL tilting issue. Charging model was used to explain the phenomenon and is validated by experiments. An approach by removing the backside films for charges release via poly-Si deposition film is proposed to solve this issue. This work provides effective approach to solve the special deep trench tilting issue in 3D NAND memory processes development.

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Section: Methodsmentioning

confidence: 99%

“…In order to study the causes of this issue and eliminate its impact, the charging model [8,[14][15][16][17] was proposed to explain the causes of the phenomena shown in the figure 1. It is ion charges trapped in N/O films that distorted the plasma in the etch process, which caused the plasma to tilt and then CSL tilted to one side.…”

Section: Introductionmentioning

confidence: 99%