Efremov Alexander, Lee Byung Jun, Kwon Kwang-Ho
Department of Electronic Devices and Materials Technology, State University of Chemistry and Technology, 7 Sheremetevsky av., 153000 Ivanovo, Russia.
Department of Control and Instrumentation Engineering, Korea University, 2511 Sejong-ro, Sejong 30019, Korea.
Materials (Basel). 2021 Mar 15;14(6):1432. doi: 10.3390/ma14061432.
This work summarizes the results of our previous studies related to investigations of reactive ion etching kinetics and mechanisms for widely used silicon-based materials (SiC, SiO, and SiN) as well as for the silicon itself in multi-component fluorocarbon gas mixtures. The main subjects were the three-component systems composed either by one fluorocarbon component (CF, CF, CHF) with Ar and O or by two fluorocarbon components with one additive gas. The investigation scheme included plasma diagnostics by Langmuir probes and model-based analysis of plasma chemistry and heterogeneous reaction kinetics. The combination of these methods allowed one (a) to figure out key processes which determine the steady-state plasma parameters and densities of active species; (b) to understand relationships between processing conditions and basic heterogeneous process kinetics; (c) to analyze etching mechanisms in terms of process-condition-dependent effective reaction probability and etching yield; and (d) to suggest the set gas-phase-related parameters (fluxes and flux-to-flux ratios) to control the thickness of the fluorocarbon polymer film and the change in the etching/polymerization balance. It was shown that non-monotonic etching rates as functions of gas mixing ratios may result from monotonic but opposite changes in F atoms flux and effective reaction probability. The latter depends either on the fluorocarbon film thickness (in high-polymerizing and oxygen-less gas systems) or on heterogeneous processes with a participation of O atoms (in oxygen-containing plasmas). It was suggested that an increase in O fraction in a feed gas may suppress the effective reaction probability through decreasing amounts of free adsorption sites and oxidation of surface atoms.
这项工作总结了我们之前的研究成果，这些研究涉及对广泛使用的硅基材料（SiC、SiO和SiN）以及多组分氟碳气体混合物中的硅本身进行反应离子蚀刻动力学和机理的研究。主要研究对象是由一种氟碳组分（CF、CF、CHF）与Ar和O组成的三元体系，或者是由两种氟碳组分与一种添加气体组成的三元体系。研究方案包括通过朗缪尔探针进行等离子体诊断以及基于模型的等离子体化学和异质反应动力学分析。这些方法的结合使我们能够：（a）找出决定稳态等离子体参数和活性物种密度的关键过程；（b）理解加工条件与基本异质过程动力学之间的关系；（c）根据与加工条件相关的有效反应概率和蚀刻产率分析蚀刻机理；（d）提出与气相相关的参数集（通量和通量比），以控制氟碳聚合物膜的厚度以及蚀刻/聚合平衡的变化。结果表明，蚀刻速率作为气体混合比的函数呈现非单调变化，这可能是由于F原子通量和有效反应概率的单调但相反的变化所致。后者要么取决于氟碳膜的厚度（在高聚合且无氧的气体体系中），要么取决于有O原子参与的异质过程（在含氧等离子体中）。有人提出，进料气体中O含量的增加可能通过减少自由吸附位点的数量和表面原子的氧化来抑制有效反应概率。
