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中文核心期刊

螺旋波等离子体功率沉积特性的数值模拟研究

NUMERICAL INVESTIGATION ON THE CHARACTERISTICS OF POWER DEPOSITION IN HELICON PLASMA

  • 摘要: 螺旋波等离子体凭借其高电离率、高密度等优势, 在半导体制造与电推进领域具有重要应用价值. 针对现有研究难以解析实验中多波耦合模式下功率沉积机制这一科学难题, 本研究基于HELIC数值模拟, 系统探究trivelpiece-gould(TG)波与helicon(H)波的本征模式竞争规律及其在低、高阶波耦合模式下的功率沉积特性. 通过构建参数化径向密度剖面模型(梯度参数s = 2.1 ~ 3.4, 峰化参数t = 1.8 ~ 2.5), 并结合自洽求解Maxwell-Boltzmann耦合方程组的数值方法, 实现了多波模式跳变过程的动态重构. 结果表明: 在低阶波模式(W1, ne = 2.0 × 1012 cm−3)下, TG波通过径向电场局域化机制贡献61.8%的边界电子加热效率, 而H波中心区功率沉积占比仅38.2%; 当激发高阶本征模(W2-W4, ne = 4.0 × 1012 ~ 1.1 × 1013 cm−3)时, TG波边缘阻尼效应导致其功率占比骤降至16.5%, 此时H波通过轴向驻波共振实现中心区83.5%的功率沉积主导, 并诱导等离子体密度分布从边缘峰化(s = 2.1)向中心聚集(s = 3.4)的模态转变. 研究结果为精确调控螺旋波等离子体参数分布及模式选择提供了重要理论支撑, 对优化半导体刻蚀均匀性和电推进器比冲性能具有直接指导意义.

     

    Abstract: Helicon plasma has significant application value in semiconductor manufacturing and electric propulsion fields, with its advantages of high ionization rate and high density. The scientific challenge of existing research is difficult to analyze the power deposition mechanism under the multi-wave coupling modes. This study systematically explores the competition rules of the eigenmodes of Trivelpiece-Gould (TG) waves and Helicon (H) waves and their power deposition characteristics in low and high-order wave coupling modes based on HELIC numerical simulation. By constructing a parameterized radial density profile model (with the gradient parameter s ranging from 2.1 to 3.4 and the peaking parameter t ranging from 1.8 to 2.5), and combining with the numerical method of self-consistently solving the coupled Maxwell-Boltzmann equations, the dynamic reconstruction of the multi-wave mode hopping process has been achieved. The results show that in the low-order wave mode (W1, ne = 2.0 × 1012 cm−3), TG waves contribute 61.8% of the boundary electron heating efficiency through the radial electric field localization mechanism, while the power deposition in the central region of H waves only accounts for 38.2%; when the high-order modes (W2-W4, ne = 4.0 × 1012 ~ 1.1 × 1013 cm−3) are excited, the edge damping effect of TG waves leads to a sudden drop in its power contribution to 16.5%, and at this time, H waves achieve 83.5% of the power deposition in the central region through axial standing wave resonance, and induce a modal transition of the plasma density distribution from the peripheral peak formation (s = 2.1) to central aggregation (s = 3.4). The research results provide important theoretical support for the precise regulation of the parameter distribution and mode selection of helicon plasmas. It has direct guiding significance for optimizing the uniformity of semiconductor etching and the specific impulse performance of electric thrusters.

     

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