Silicon (Si)-based materials such as Si and silicon dioxide (${\mathrm{SiO}}_2$) are commonly used as basic components of advanced semiconductor devices. For example, alternating stacks of poly-Si and ${\mathrm{SiO}}_2$ layers are used in three-dimensional (3D) NAND flash memory devices. Fabrication of high-aspect-ratio deep holes through such stacked materials by plasma etching may be achieved by highly energetic and chemically reactive ion injections to the surface. Etching by sulfur hexafluoride (${\mathrm{SF}}_6$) plasmas can produce ions carrying multiple fluorine (F) atoms and therefore exhibit high etch rates for both Si and ${\mathrm{SiO}}_2$. In this study, reactive ion etching of Si and ${\mathrm{SiO}}_2$ materials by ${\mathrm{SF}}_5^{+}$ ions was examined with the use of molecular dynamics (MD) simulation. For this purpose, a simplified interatomic potential functions model for sulfur (S) was developed that approximately represents molecular moieties or molecules ${\mathrm{SF}}_n$ ($n\le 6$) based on density-functional-theory (DFT) calculations. The etching yields of Si and ${\mathrm{SiO}}_2$ by ${\mathrm{SF}}_5^{+}$ ions evaluated by MD simulations with these new potential functions were found to be in good agreement with those obtained from multibeam injection system experiments, which implies that the etching process is essentially due to sputtering enhanced by chemical reactions of F atoms with the surface materials. Analyses of the depth profiles of atomic concentrations of etched surfaces and desorbed species obtained from MD simulations also indicate that the presence of excess F atoms on the surface enhances the etching yield of Si and ${\mathrm{SiO}}_2$ significantly over corresponding physical sputtering.

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Si和SiO2bySF5+离子反应离子刻蚀的分子动力学模拟

硅（Si）基材料，如Si和二氧化硅（${\mathrm{二氧化硅}}_2$) 通常用作高级半导体器件的基本组件。例如，交替堆叠多晶硅和${\mathrm{二氧化硅}}_2$层用于三维 (3D) NAND 闪存设备。可以通过向表面注入高能量和化学反应性离子来通过等离子体蚀刻制造穿过这种堆叠材料的高纵横比深孔。六氟化硫蚀刻（${\mathrm{顺丰}}_6$) 等离子体可以产生携带多个氟 (F) 原子的离子，因此对 Si 和 ${\mathrm{二氧化硅}}_2$. 在本研究中，Si 和${\mathrm{二氧化硅}}_2$ 材料由 ${\mathrm{顺丰}}_5^{+}$使用分子动力学 (MD) 模拟检查离子。为此，开发了硫 (S) 的简化原子间势函数模型，该模型近似表示分子部分或分子${\mathrm{顺丰}}_n$ ($n\le 6$) 基于密度泛函理论 (DFT) 计算。Si和的蚀刻产率${\mathrm{二氧化硅}}_2$ 经过 ${\mathrm{顺丰}}_5^{+}$发现具有这些新势函数的 MD 模拟评估的离子与从多束注入系统实验中获得的那些非常一致，这意味着蚀刻过程主要是由于 F 原子与表面材料的化学反应增强了溅射。对从 MD 模拟获得的蚀刻表面的原子浓度和解吸物种的深度分布的分析也表明，表面上过量 F 原子的存在提高了 Si 和${\mathrm{二氧化硅}}_2$ 显着超过相应的物理溅射。