| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2022: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2021: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2020: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Outline of Annual Research Achievements |
The 3D NAND flash memory technology has been the primary solution for any platforms requiring data storage. Its memory capacity is dictated by the number of alternating silicon dioxide (SiO2) and silicon nitride (SiN) stacked films (referred to as ONO) deposited on a Si substrate. Hole channels with a high aspect ratio (AR) and straight profiles are etched through the stacked films to form the memory cell arrays. However, maintaining a straight profile becomes more difficult as the AR increases. As such, high aspect ratio (HAR) etching has been the roadblock for 3D NAND devices with larger storage capacity. In this research, experiments, and simulations had been performed to understand the HAR etching process in the fabrication of 3D NAND memory devices. For the experiment, SiO2, SiN, and ONO stacked films deposited on Si wafers were etched with Ar and CF3 ions using the mass-selected ion beam system. The etch yields and etch rates were calculated, and the films were characterized by X-ray photoelectron spectroscopy (XPS). For the simulation, molecular dynamics (MD) simulations of the etching of SiO2, SiN, and ONO by Ar, Cl, and CF3 ions were done. The etch yields from the simulations were compared to the etch yields from the experiments wherein a relatively good agreement was attained. As such, some of the results of the research have been presented at various domestic and international conferences. The research has also been summarized in a dissertation and published in 3 scientific papers.
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