Improvement of the Harmonic Technique of Probe for Measurements of Electron Temperature and Ion Density  

作　　者：白玉静 李建泉 徐军 陆文琪 王友年 丁万昱 

机构地区：[1]Key Laboratory of Materials Modification by Laser, Ion and Electron Beams(Dalian University of Technology), Ministry of Education [2]School of Physics and Optoelectronic Technology, Dalian University of Technology [3]School of Materials Science and Engineering, Dalian Jiaotong University

出　　处：《Plasma Science and Technology》2016年第1期58-61,共4页等离子体科学和技术（英文版）

摘　　要：Conventional Langmuir probe techniques usually face the difficulty of being used in processing plasmas where dielectric compounds form,due to rapid failure by surface insulation.A solution to the problem,the so-called harmonic probe technique,had been proposed and shown effectiveness.In this study,the technique was investigated in detail by changing bias signal amplitudes V_0,and evaluated its accuracy by comparing with the conventional Langmuir probe.It was found that the measured electron temperature Teincreased with V_0,but showing a relatively stable region when V_0〉Te/e in which it was close to the true Tevalue.This is contrary to the general consideration that V_0should be smaller than Te/e for accurate measurement of Te.The phenomenon is interpreted by the non-negligible change of the ion current with V_0at low V_0values.On the other hand,the measured nialso increased with V_0due to the sheath expansion,and to improve the accuracy of niit needs to linearly extrapolate the ni-V_0trend to V_0=0.The results were applied to a diagnosis of the plasmas for chemical vapor deposition of diamond-like carbon thin films and the relationship between plasma parameters and films deposition rates was obtained.Conventional Langmuir probe techniques usually face the difficulty of being used in processing plasmas where dielectric compounds form,due to rapid failure by surface insulation.A solution to the problem,the so-called harmonic probe technique,had been proposed and shown effectiveness.In this study,the technique was investigated in detail by changing bias signal amplitudes V_0,and evaluated its accuracy by comparing with the conventional Langmuir probe.It was found that the measured electron temperature Teincreased with V_0,but showing a relatively stable region when V_0〉Te/e in which it was close to the true Tevalue.This is contrary to the general consideration that V_0should be smaller than Te/e for accurate measurement of Te.The phenomenon is interpreted by the non-negligible change of the ion current with V_0at low V_0values.On the other hand,the measured nialso increased with V_0due to the sheath expansion,and to improve the accuracy of niit needs to linearly extrapolate the ni-V_0trend to V_0=0.The results were applied to a diagnosis of the plasmas for chemical vapor deposition of diamond-like carbon thin films and the relationship between plasma parameters and films deposition rates was obtained.

关 键 词：plasma diagnosis Langmuir probe harmonics insulative deposition 

分 类 号：O536[理学—等离子体物理]