放电参数对不同频率驱动的容性耦合氩等离子体影响的研究

Research on influence of discharge parameters on capacitively coupled Ar plasma driven by different frequencies

研究了不同放电参数(功率、气压、频率)下容性耦合氩等离子体中电子温度以及电子密度的变化规律.电子温度和电子密度的测量由双探针诊断获得,而功率电极自偏压则由示波器测量得到.实验结果表明,不同驱动频率下,电子温度随功率上升明显降低直至达到稳定值,而随着驱动频率和气压的上升,电子与周围粒子碰撞加剧,从而导致电子温度降低.低功率时,电子密度呈现出类抛物线增长,高功率时,电子密度则线性增加.随着气压的上升,电子密度呈现先上升后略有下降的趋势.此外,当驱动频率由13.56MHz增加到60MHz时,观察到电子密度与驱动频率的成二次方的依赖关系.自偏压的测量结果表明,自偏压随着放电功率增大而增大,而当气压和驱动频率上升时,自偏压反而降低.

The variations of electron temperature and electron density have been investigated in a capacitively coupled Ar plasma driven by different discharging parameters,such as power,pressure and frequency.The evolutions of electron temperature and electron density over a wide range of gas pressures are obtained by a dual probe while the bias voltage of powered electrode is measured by an oscilloscope.It is shown that,regardless of frequency,electron temperature gives a significant decrease until it comes to a stable value and as driving frequency and pressure go up,electron temperature also exhibits a decrease due to the continuous collision between electrons and around particles.Electron density presents an analogous parabolic increase at low discharge power while it increases linearly at high discharge power.From low pressure to high pressure,electron density increases at first and then it doesn＇t change a lot or even start to go down.Besides,a second order dependence of electron density on driving frequency is observed over the frequency range from 13.56MHz to 60MHz.Bias voltage goes up with discharge power while it decreases with pressures as well as frequencies.