Frequency dependence of plasma characteristics at different pressures in cylindrical inductively coupled plasma source

作     者：Zeyu HAO Jian SONG Yue HUA Gailing ZHANG Xiaodong BAI Chunsheng REN 郝泽宇;宋健;滑跃;张改玲;白晓东;任春生

作者机构：Key Laboratory of Materials Modification by Laser Ion and Electron Beams (Dalian University of Technology) Ministry of Education 

出 版 物：《Plasma Science and Technology》 (等离子体科学和技术（英文版）)

年 卷 期：2019年第21卷第7期

页      面：114-122页

核心收录：

学科分类：07[理学] 0805[工学-材料科学与工程（可授工学、理学学位）] 070204[理学-等离子体物理] 0702[理学-物理学] 

基　　金：supported by National Natural Science Foundation of China (No. 11475038) 

主　　题：inductively coupled plasma driving frequency electron heating efficiency electron temperature electron density 

摘      要：The effects of driving frequency on plasma parameters and electron heating efficiency are studied in cylindrical inductively coupled plasma(ICP) source. Measurements are made in an Ar discharge for driving frequency at 13.56/2 MHz, and pressures of 0.4-1.2 Pa. In 13.56 MHz discharge, higher electron density(n_e) and higher electron temperature(T_e) are observed in comparison with 2 MHz discharge at 0.6-1.2 Pa. However, slightly higher n_e and T_e are observed in 2 MHz discharge at 0.4 Pa. This observation is explained by enhanced electron heating efficiency due to the resonance between the oscillation of 2 MHz electromagnetic field and electron-neutral collision process at 0.4 Pa. It is also found that the variation of T_edistribution is different in 13.56 and 2 MHz *** ICP at 13.56 MHz, T_eshows an edge-high profile at 0.4-1.2 Pa. For 2 MHz discharge, T_e remains an edge-high distribution at 0.4-0.8 Pa. However, the distribution pattern involves into a center-high profile at 0.9-1.2 Pa. The spatial profiles of n_e remain a center-high shape in both 13.56 and 2 MHz discharges, which indicates the nonlocal kinetics at low pressures. Better uniformity could be achieved by using 2 MHz discharge. The effects of gas pressure on plasma parameters are also examined. An increase in gas pressure necessitates the rise of n_e in both 13.56 and 2 MHz discharges. Meanwhile, T_e drops when gas pressure increases and shows a flatter distribution at higher pressure.