Plasma dynamics in a highly ionized pulsed magnetron discharge
Plasma dynamics in a highly ionized pulsed magnetron discharge
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DOI：
10.1088/0963-0252/14/3/015
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发表时间：
2005-08
影响因子：
3.8
通讯作者：
J. Alami;J. Gudmundsson;J. Bohlmark;J. Birch;U. Helmersson
中科院分区：
文献类型：
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作者：
J. Alami;J. Gudmundsson;J. Bohlmark;J. Birch;U. Helmersson
本文报道了高功率脉冲磁控放电的静电探针测量。得到了等离子体参数随工艺参数变化的时空特性。通过施加高功率脉冲(峰值功率为∼0.5 mW)，脉冲开启时间为∼100µS，重复频率为20ms，在脉冲开启后不久，获得了∼1019m−3量级的峰值电子密度，即比常规直流磁控放电高3个数量级。在较高的溅射气体压力(>；5mTorr)下，脉冲关闭后数百微秒，电子密度曲线出现第二个峰值。第二个峰值主要是由于等离子体中的离子声波，反射出腔壁。这是从电子和离子饱和电流中两个峰之间的时间延迟得出的，这表明这取决于腔室的尺寸和溅射气体的组成。最后，电子温度被确定，最初非常高，但随着脉冲的关闭而迅速下降。在靠近阴极蚀刻区域的电子温度的降低是由于溅射的金属原子的冷却。
We report on electrostatic probe measurements of a high-power pulsed magnetron discharge. Space- and time-dependent characteristics of the plasma parameters are obtained as functions of the process parameters. By applying high-power pulses (peak power of ∼0.5 MW), with a pulse-on time of ∼100 µs and a repetition frequency of 20 ms, peak electron densities of the order of ∼1019 m− 3, i.e. three orders of magnitude higher than for a conventional dc magnetron discharge, are achieved soon after the pulse is switched on. At high sputtering gas pressures (>5 mTorr), a second peak occurs in the electron density curve, hundreds of microseconds after the pulse is switched off. This second peak is mainly due to an ion acoustic wave in the plasma, reflecting off the chamber walls. This is concluded from the time delay between the two peaks in the electron and ion saturation currents, which is shown to be dependent on the chamber dimensions and the sputtering gas composition. Finally, the electron temperature is determined, initially very high but decreasing rapidly as the pulse is turned off. The reduction seen in the electron temperature, close to the etched area of the cathode, is due to cooling by the sputtered metal atoms.