Magnetic field optimization and high-power discharge characteristics of cylindrical sputtering cathode
Research output: Journal Publications and Reviews (RGC: 21, 22, 62) › 21_Publication in refereed journal › peer-review
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|Original language||Chinese (Simplified)|
|Journal / Publication||Wuli Xuebao/Acta Physica Sinica|
|Publication status||Published - 20 Feb 2021|
|Link to Scopus||https://www.scopus.com/record/display.uri?eid=2-s2.0-85101658890&origin=recordpage|
基于高功率脉冲磁控溅射 (HiPIMS) 技术开发的筒形溅射阴极, 配合电磁系统可有效地提升等离子体的输运效率. 然而电磁系统的引入反作用于筒内放电特性, 从而使靶面放电面积和放电强度无法同时维持. 鉴于此, 本文通过调整磁场布局, 研究了靶面切向 (横向) 磁场和法向 (纵向) 磁场对靶面放电的作用规律, 优化后靶面切向磁场分布更加均匀, 磁场强度高于 40 mT 的靶面区域占比由 51% 增至 67%, 同时法向峰值强度外移, 强度由 73 mT 增至 96 mT. 采用 Ar/Cr 体系放电发现：相同工艺条件下, 优化后的溅射阴极辉光变亮, 靶电流增大, 放电面积变宽, 放电特性得到显著提升. 利用等离子体整体模型仿真和发射光谱仪检测发现优化后离子电流和光谱强度得到明显提升, Cr 粒子密度提高一倍, 增至 2.6 × 1020 m–3, 且离化率上升至 92.1%, 同时输出离子通量提高近一倍, 实现了靶面放电与离子输出的双促进.
High-power pulsed magnetron sputtering (HiPIMS) can produce high density and high adhesion coatings due to the high ionization. However, industrial application of HiPIMS is limited because of the unstable discharge and small deposition rate. A cylindrical cathode, developed on the basis of hollow cathode effect, can improve the discharge stability. With the development of electromagnetic systems, the plasma transport is improved, and thus increasing the deposition rate significantly. However, the introduction of electromagnetic system leads the strong discharge and large etching area on the target to be incompatibly controlled. In this work, the distribution of the tangential and longitudinal magnetic field on the target surface are improved by adding external magnets, and their effects on the plasma discharge are studied. By optimizing the magnets, the tangential magnetic field on the target surface becomes stronger and more uniform. Meanwhile, the peak of the longitudinal magnetic field increases from 73 to 96 mT and the peak location expands to two-sides of the cathode. The simulation result shows that the target etching area described by the proportion of the target area with the tangential magnetic field intensity higher than 40 mT increases from 51% to 67%, and the HiPIMS discharge studied by the particle in cell/Monte Carlo collision (PIC/MCC) method and plasma global model shows that the ion current and spectral intensity are significantly enhanced, exhibiting a doubled Cr density of 2.6 × 1020 m-3 and an increased ionization from 90% to 92.1%. The practical Ar/Cr HiPIMS discharge is carried out separately with the original and optimized cylindrical cathode, and the results reveal that the brightness of plasma glow, the target current and the etching area all increase after the improvement. Furthermore, the ion current and the optical emission spectrum suggest that the flux of ions arriving at the substrate is approximately doubled, which means that an about doubled deposition rate of the optimized cathode is achievable.
- Discharge enhancement, Electromagnetic coordination, High power impulse magnetron sputtering, Transport efficiency, 高功率脉冲磁控溅射, 磁电协同, 增强放电, 输出效率, TARGET EROSION, HIPIMS