不同驱动电源下磁控溅射等离子体行为

磁控溅射驱动方式是影响其等离子体特征的重要因素之一,而等离子体行为最终影响所沉积薄膜结构和性能。磁控溅射过程中基体上产生的浮动电势与等离子体中电子能量分布有关,基体饱和电流则与等离子体的离子密度有关,可综合反映辉光放电系统等离子体状态。本实验分别采用射频、直流和脉冲直流电源溅射Mo粉末靶,改变靶基距,测量基体浮动电势及饱和电流,探讨溅射驱动方式对等离子体行为的影响。研究表明:靶功率增加,靶电压、电流均随靶功率增大,基体浮动电势基本保持不变,基体饱和电流增加,但电压增加率极小,而电流增加率较大。基体浮动电势绝对值随靶基距的增加而降低,即电子的能量分布随靶基距增加而降低。射频溅射产生的浮动电势明显小于直流和脉冲直流溅射的。直流溅射等离子体能量最高,射频溅射等离子体密度最大。

Characteristics of plasmas of magnetron sputtering by various power drives

The power driver modes are the key factor to affect the plasma characteristics, which finally lead to the variations of the structure and properties of as-deposited thin films in magnetron sputtering. The character-istics of the magnetron sputtering plasmas can be featured by the distributions of the energies and concentra-tions of the ions and electrons in the plasmas. The substrate floating potentials are depended on the energies of ions and electrons of the plasma, and the substrate saturation currents on their densities in magnetron sputter-ing. RF, DC and pulsed DC power drives were used to sputter the Mo powder target in this experiments. The substrate floating potentials and saturation currents were measured by varying the target powers and target-sub-strate separations. The studies showed that the target voltages and currents increased as the increases of target powers, the floating potentials remained constant. The value-added of the voltage was very small, but that of the current was significant. The increases of the saturation currents on the substrates were observed as the in-creases of the target powers. The floating potentials on substrate decreased as the increases of the target-sub-strate separations, i.e. the energies of the electrons in the plasma reduced as the substrates moved far away from the targets. The floating potentials by RF drive mode were obviously smaller than those by DC or Pulsed DC drive modes. The energy of the DC plasma is the highest among the three drive modes, and the RF plasma is the dentist.