AVS 52nd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP29
A High Density Negative Ion Plasma in a Very High Dielectric-Constant Discharge Tube

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Plasma Science and Technology Poster Session
Presenter: Y. Ikeda, KYOSERA Co. LTD., Japan
Authors: Y. Ikeda, KYOSERA Co. LTD., Japan
K. Endo, Tokai University, Japan
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 negative ion plasma source. In particular, an innovative method to produce a negative ion rich plasmas is proposed by employing RF surface-wave plasma with a extremely high dielectric constant discharge tube. As well-known, the surface-wave can only be existed above the resonance density, which depends on the permittivity of the 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 a 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. While in the quartz discharge tube the line intensity decayed just simply and monotonically. Thus it was concluded that the surface-wave plasma with a extremely high dielectric constant discharge tube was an innovative method of negative ion rich plasma.