Slope and amplitude asymmetry effects on low frequency capacitively coupled carbon tetrafluoride plasmas
Slope and amplitude asymmetry effects on low frequency capacitively coupled carbon tetrafluoride plasmas
复制标题
DOI：
10.1063/1.4947453
复制
发表时间：
2016-04
影响因子：
3.2
通讯作者：
B. Bruneau;I. Korolov;T. Lafleur;T. Gans;D. O’Connell;A. Greb;A. Derzsi;Z. Donkó;S. Brandt;E. Schüngel;J. Schulze;E. Johnson;J. Booth
中科院分区：
文献类型：
--
作者：
B. Bruneau;I. Korolov;T. Lafleur;T. Gans;D. O’Connell;A. Greb;A. Derzsi;Z. Donkó;S. Brandt;E. Schüngel;J. Schulze;E. Johnson;J. Booth
我们报告了对电容耦合四氟化碳 (CF4) 等离子体的研究，该等离子体由包含 5.5 MHz 基频的多达五个谐波的定制电压波形激发。通过将实验与细胞内颗粒模拟相结合来检查这些波形的斜率不对称性和幅度不对称性对放电的影响。对于本文研究的所有条件，放电显示为在漂移双极模式下运行，其中等离子体本体（鞘层外部）中相对较大的电场是电子功率吸收导致电离的主要机制。我们表明，两种类型的波形不对称性都会强烈影响电极处的离子能量，其特殊性是在观察到最低离子能量的电极上具有最高离子通量。即使在此处使用的相对较高的压力 (600 mTorr) 和 5.5 MHz 的低基频下，调整电压波形也可以有效地在几何对称反应器中产生离子能量和离子通量的不对称性。
We report investigations of capacitively coupled carbon tetrafluoride (CF4) plasmas excited with tailored voltage waveforms containing up to five harmonics of a base frequency of 5.5 MHz. The impact of both the slope asymmetry, and the amplitude asymmetry, of these waveforms on the discharge is examined by combining experiments with particle-in-cell simulations. For all conditions studied herein, the discharge is shown to operate in the drift-ambipolar mode, where a comparatively large electric field in the plasma bulk (outside the sheaths) is the main mechanism for electron power absorption leading to ionization. We show that both types of waveform asymmetries strongly influence the ion energy at the electrodes, with the particularity of having the highest ion flux on the electrode where the lowest ion energy is observed. Even at the comparatively high pressure (600 mTorr) and low fundamental frequency of 5.5 MHz used here, tailoring the voltage waveforms is shown to efficiently create an asymmetry of both the ion energy and the ion flux in geometrically symmetric reactors.