AVS 53rd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS-ThP

Paper PS-ThP3
A New Production Method of Negative-Ion-Plasma in an Extremely High Dielectric-Constant Discharge Tube

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: High Pressure Discharges and Novel Diagnostics & Sources Poster Session
Presenter: K. Kusaba, Tokai University, Japan
Authors: K. Kusaba, Tokai University, Japan
Y. Ikeda, KYOCERA Co. LTD., Japan
K. Shinohara, Japan High Frequency Co., LTD
H. Shindo, Tokai University, Japan
Correspondent: Click to Email
Negative ions in plasmas are much attractive species in material processing, such as ion implantation, CVD and etching in ULSI fabrications. The objective of this work is to study a new negative ion plasma source. In particular, an innovative method to produce a high density negative ion plasmas is proposed by employing RF surface-wave plasma with a extremely high dielectric constant discharge tube. In this work, a negative ion plasma is produced by employing the after-glow appeared in the resonance density of the surface-wave which is enhanced by a extremely high dielectric constant discharge tube. The surface-wave plasmas of O2 and SF6 were produced in a discharge tube by supplying 13.56 and 60 MHz power. The two discharge tubes of a ceramic of TiCa-TiMg, K-140, which is commercially available from KYOCERA Co. and quartz are employed, and their permittivities are, respectively, 140 and 3.8. The optical emission line measurements were carried out from the lateral view. The axial decay rate of the intensities of the optical emission lines FI in SF6 plasma were 5 times faster in the K-140 discharge tube than in the quartz. In particular, a sudden precipitation of the line intensity could be observed, and this is due to the surface-wave ending at the resonance density, providing a high density after-glow. In O2 plasma, in this after-glow region, the OI emission lines of 777 and 845 nm, which are originated from the mutual neutralization of O- and O+, were observed to be very much enhanced after the sudden precipitation, indicating the rich negative ions populated in this region. Furthermore, the emission line of OI 645 nm, which is known free from the mutual neutralization, was not observed in the after-glow. This fact clearly demonstrates that the line intensity enhancement in the downstream is due to the negative oxygen ion. While in the quartz discharge tube the line intensity decayed just simply and monotonically.