AVS 50th International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS-ThA

Paper PS-ThA2
Discharge Frequency Dependence of Plasma Parameters in Parallel-plate-electrode VHF Plasmas

Thursday, November 6, 2003, 2:20 pm, Room 315

Session: Plasma Diagnostics: Mechanisms
Presenter: Y. Ichikawa, Fuji Electric Co. Ltd., Japan
Authors: Y. Ichikawa, Fuji Electric Co. Ltd., Japan
T. Sasaki, Fuji Electric CRD, Japan
S. Matsumura, Musashi Institute of Technology, Japan
Correspondent: Click to Email
Recently, plasmas generated by power supplies of VHF band attract considerable interest in plasma CVD technique to increase deposition rate and to improve film properties of silicon related thin films. In this work, we have studied the effect of discharge frequency on the characteristics of plasma with a view to understanding the mechanism why VHF plasmas are more desirable than the conventional 13.56MHz plasma. We used a capacitively coupled plasma CVD apparatus with a pair of parallel plate electrodes of 160mm in diameter; the discharge frequency can be varied from 10MHz to 100MHz continuously. To measure the plasma parameters of VHF plasma precisely, we developed the following two probe diagnostic techniques: (1) A modified capacitance probe to measure the amplitude of plasma potential variation (V@sub sp-p@) at discharge frequency (2) Compensation single probe by which variation of the plasma potential is compensated and precise current voltage characteristics are measured Employing these probe techniques, we measured electron temperature, electron density, time averaged space potential, and V@sub sp-p@ in H@sub 2@ VHF plasmas. The results measured at frequencies of 13, 24.5 and 92.3MHz show that (1) the electron temperature, Te, decreases with increasing discharge frequency; (2) the electron density for 92.3Hz is about 30 times as high as that for 13MHz under the same discharge power condition. The spatial distributions of these plasma parameters and the space potential were also measured. The details of these experimental results will be presented and discussed.