容性耦合电负性氧等离子体的激光诱导光致剥离技术诊断研究

摘要

采用波长532nm的高能脉冲激光束照射40.68MHz激发的容性耦合氧等离子体,并给处于激光束中央的探针施加一定的正偏压,由此诊断氧等离子体的空间电位和电负度.实验结果表明,探针偏压从0V逐渐增加时,探针搜集的电流波形从V型向倒U型转变,转变电压点正是电负性等离子体的空间电位.尝试着给出了运用激光诱导光致剥离技术诊断电负性等离子体空间电位的经验方法.另外,探针上施加的正偏压高于等离子体空间电位时,等离子体的电负度基本保持不变.实验还表明,氧等离子体的电负度随着射频输入功率的增加而呈现下降的趋势.%A high energy pulsed laser beam with wavelength of 532nm was applied to irradiate the capacitively coupled O2 plasma driven by 40.68MHz. Spatial potential of the plasma and electro negativity are diagnosed by exerting a certain positive bias on the probe aligned with laser beam at the center. The experimental results show that a transition of signal wave shape on the probe occurs from V-shaped to invert U-shaped as increasing positive bias. The transition voltage point is just the spatial potential of electronegative plasma. An empirical method was given to obtain the spatial potential of negative plasma by using LIPD technique. Additionally, plasma electro negativity keeps a constant basically as increasing positive bias beyond the plasma spatial potential. The experiments still show a trend of decrease in electro negativity of O2 plasma with increasing RF input power.