3次元積層デバイス開発為の分子動力学計算によるプラズマエッチング反応の解析

3D NAND闪存技术一直是任何需要数据存储的平台的主要解决方案。其存储容量由在硅衬底上沉积的交替的二氧化硅(SiO)和氮化硅(SiN)堆叠膜(称为ONO)的数量决定。具有高长宽比(AR)和直轮廓的空穴沟道被刻蚀通过堆叠的薄膜以形成存储单元阵列。然而，随着AR的增加，保持笔直的轮廓变得更加困难。因此，高深宽比(HAR)刻蚀一直是具有更大存储容量的3D NAND器件的障碍。在这项研究中，我们进行了实验和模拟，以了解3D NAND存储器件制造中的Har刻蚀过程。在本实验中，用Ar和CF3离子刻蚀了沉积在硅片上的SiO_2、SiN和ONO叠层薄膜。计算了薄膜的刻蚀产率和刻蚀速率，并用X射线光电子能谱(XPS)对薄膜进行了表征。为了进行模拟，用分子动力学方法模拟了Ar、Cl和CF3离子对SiO_2、SiN和ONO的刻蚀。将模拟得到的刻蚀产额与实验得到的刻蚀产额进行了比较，得到了相对较好的一致性。因此，这项研究的一些成果已在各种国内和国际会议上公布。这项研究还在一篇论文中进行了总结，并发表在3篇科学论文中。

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.