Electron dynamics in radio frequency magnetron sputtering argon discharges with a dielectric target
Electron dynamics in radio frequency magnetron sputtering argon discharges with a dielectric target
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DOI：
10.1088/1361-6595/abe9f9
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发表时间：
2021-02
影响因子：
3.8
通讯作者：
B. Zheng;Yangyang Fu;Keliang Wang;T. Schuelke;Q. Fan
中科院分区：
文献类型：
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作者：
B. Zheng;Yangyang Fu;Keliang Wang;T. Schuelke;Q. Fan
我们展示了对介电靶材的典型正电射频磁控溅射 (RFMS) 氩放电中电子动力学的自洽且完整的描述。通过全动态 2d3v 细胞内粒子/蒙特卡罗碰撞 (PIC/MCC) 静电模拟研究电子动力学，包括一个射频 (RF) 周期内的电子功率吸收动力学。通过时空动力学分析基本等离子体参数之间的相互作用。由于磁阱对电子传输的影响，在介电目标表面上观察到扰乱电势的空间相关的充电，导致沿着目标表面的空间相关的离子能量分布。 E × B 漂移与放电电流之比与玻姆扩散大致一致。电子功率吸收主要可以解耦为体等离子体区域中的正欧姆功率吸收和目标表面附近的负压引起的功率吸收。欧姆功率吸收是主要的电子功率吸收机制，主要由方位角电子电流贡献。由于电子惯性效应造成的功率吸收在时间平均上可以忽略不计。在射频周期的后半段期间，电子的最大功率吸收和耗散都出现在体等离子体区域，这意味着磁控管放电中存在强烈的电子俘获。在典型的 RFMS 放电条件下，二次电子的贡献可以忽略不计。
We demonstrate a self-consistent and complete description of electron dynamics in a typical electropositive radio frequency magnetron sputtering (RFMS) argon discharge with a dielectric target. The electron dynamics, including the electron power absorption dynamics in one radio frequency (RF) period, is studied via a fully kinetic 2d3v particle-in-cell/Monte Carlo collision (PIC/MCC) electrostatic simulation. The interplay between the fundamental plasma parameters is analyzed through their spatiotemporal dynamics. Due to the influence of magnetic trap on the electron transport, a spatially dependent charging that perturbs the electric potential is observed on the dielectric target surface, resulting in a spatially dependent ion energy distribution along the target surface. The E × B drift-to-discharge current ratio is in approximate agreement with Bohm diffusion. The electron power absorption can be primarily decoupled into the positive Ohmic power absorption in the bulk plasma region and the negative pressure-induced power absorption near the target surface. Ohmic power absorption is the dominant electron power absorption mechanism, mostly contributed by the azimuthal electron current. The power absorption due to electron inertial effects is negligible on time-average. Both the maximum power absorption and dissipation of electrons appear in the bulk plasma region during the second half of the RF period, implying a strong electron trapping in magnetron discharges. The contribution of secondary electrons is negligible under typical RFMS discharge conditions.