| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Thursday Sessions |
| Session PS-ThP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | Chuyu Kao, National Tsing Hua University, Taiwan, Republic of China |
| Authors: | C.Y. Kao, National Tsing Hua University, Taiwan, Republic of China W.C. Chen, National Tsing Hua University, Taiwan, Republic of China K.C. Leou, National Tsing Hua University, Taiwan, Republic of China C.H. Hsieh, National Tsing Hua University, Taiwan, Republic of China |
| Correspondent: | Click to Email |
Measurement of plasma density, a key parameter that control the property of processing plasmas and hence the processing results, has been the focus of extensive studies in recent years, not only for characterization of the plasmas but also for development of tools for monitoring of the plasma based processes1. In this study, a multi-mode plasma absorption probe2 was investigated by employing a full wave electromagnetic simulation using a finite element code, High Frequncy Structure Simulation (HFSS, ANSOFT CORP). The spherically-shaped probe was formed by two isolated hemispherical conductors, which was enclosed by a layer of dielectrics (alumina). In the simulation analysis, a coaxial line was attached to the spherical probe head and the "driven mode" was adoped, i.e., the wave was fed into the coaxial line and the absorption specturm, reflection coefficient vs frequency, was then analyzed. The probe was in a plasma, characterized by the collisional electromagnetic plasma permittivity, determined by plasma density, wave frequency and momentum transfer collisional frequency. Simulation results show that the absorption spectrum exhibits a number of resonances, as a result of cavity-like structure resonant modes, as well as the plasma density, similar to the results reported in a previous work based on an electrostatic analysis2. The electromagnetic analysis adopted in this work, however, reveals that the wave also propagates along the interface between the plasma and the coaxial cable, similar to the characteristics of a conventional plasma absorption probe3. This effect thus contributes to resonant peaks in the absorption spectrum that did not appear in the electrostatic analysis. A parametric study by varying the plasma density, probe size and dielectric thickness have been conducted and the results will be presented.
1 M. A. Lieberman and A. J. Lichtenberg, Principle of Plasma Dishcarges and Material Processing, Wiley, New York, 2005.
2 C. Scharwitz, et al, Appl. Phys. Lett., 94, 011502(2009).
3 H. Kokura, et al, Jpn. J. Appl. Phys., Part 1, 38, 5262, 1999.
* Work supported by the National Science Council of Taiwan, ROC.