Photodetachment Study of Capacitively-Coupled RF C_4F_8 Plasma

概要

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Behaviors of electrons and negative ions in a capacitively coupled RF(13.56 MHz)plasma of c-C_4F_8(perfluorocycrobutane)were studied using a laser-induced photodetachment technique in combination with a microwave cavity resonance technique. The results indicate that the negative ion formation process strongly depends on the RF power because of the dissociation of c-C_4F_8 even in the low power range(< 100 W)studied in this work. The negative ion density estimated on the assumption that all negative ion species have the same photodetachment efficiency as that for F^- is larger by a factor of 〜50 than the electron density in the typical condition in this work(100 m Torr C_4F_8, 10W RF power). However, the electron attachment rate and ion recombination rate suggest that the actual negative ion density should be significantly higher than that derived on the above assumption ; this discrepancy could be attributed to the low photodetachment efficiency for large molecular negative ions which may exist abundantly in the low RF power region.
社団法人応用物理学会の論文
2000-03-15