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。其存储容量由沉积在Si衬底上的交替二氧化硅（SiO2）和氮化硅（SiN）堆叠膜（称为ONO）的数量决定。具有高纵横比（AR）和直轮廓的孔通道被蚀刻穿过堆叠的膜以形成存储器单元阵列。然而，随着AR的增加，保持直线轮廓变得更加困难。因此，高纵横比（HAR）蚀刻已经成为具有更大存储容量的3D NAND器件的障碍。在这项研究中，进行了实验和模拟，以了解在3D NAND存储器设备的制造中的HAR蚀刻工艺。对于实验，SiO2，SiN，和ONO堆叠膜沉积在Si晶片上的蚀刻与Ar和CF3离子使用质量选择离子束系统。计算了刻蚀产率和刻蚀速率，并通过X射线光电子能谱（XPS）对薄膜进行了表征。对于模拟，进行了Ar、Cl和CF3离子对SiO2、SiN和ONO的蚀刻的分子动力学（MD）模拟。将来自模拟的蚀刻产率与来自实验的蚀刻产率进行比较，其中获得了相对良好的一致性。因此，一些研究成果已在各种国内和国际会议上发表。该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.