AVS 47th International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP9
Ion Angular Distribution at RF Biased Electrode in Inductively Coupled Plasma

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: N. Mizutani, ULVAC JAPAN, Ltd.
Authors: N. Mizutani, ULVAC JAPAN, Ltd.
K. Yamamuro, ULVAC JAPAN, Ltd.
T. Hayashi, ULVAC JAPAN, Ltd.
Correspondent: Click to Email
Ions play an important role in the plasma etching process. The ions, which were accelerated in the sheath, bombard the substrate with high energies. The etching characteristics, that is to say, the etching rate, the selectivity, the uniformity, and so on, depend on the ion energy. The ion incident angle at the substrate will affect the characteristics in the etching of the fine pattern such as contact holes, because the ion flux at the bottom of the pattern depends on the incident angle. The ion angular distribution (IAD) had been measured at the earthed electrode in the plasma chamber by several groups.@footnote 1@ However, the IAD has never been measured at the RF biased electrode, at which the etching is done. Therefore, we measured the IAD at the RF biased electrode in the inductively coupled plasma. For the measurement at the RF electrode, the analyzer must be RF floating, that is to say, the electric potential reference of the analyzer must be the potential of the RF electrode.@footnote 2@ Therefore, we have developed such an analyzer. For 2 MHz biased Ar-O@sub 2@ plasma, the IADs were measured by using annular ion collectors that were similar to ones used in Ref. 1. The ion energy distribution (IED) at each ion collector was also measured. For the low gas pressure, 0.4 Pa, the IED was a bimodal distribution at a small incident angle (< 1°), where the vertical incidence corresponds to 0°. The bimodal distribution is due to ions that did not collide in the sheath. The ion flux at the large angle (20°) was very low compared with one at the small angle. For the high pressure, 2.7 Pa, the IED was not the simple bimodal distribution at the small incident angle, and low-energy ions increased relatively. The ion flux at the large angle increased compared with the low-pressure case. The measured behaviors of the IED and IAD can be explained by charge exchange and elastic collisions in the sheath.@footnote 3@ Comparison between the measured IAD and IED and calculated ones will be shown. @FootnoteText@ @footnote 1@ J. R. Woodworth, M. E. Riley, D. C. Meister, B. P. Aragon, M. S. Le and H. H. Sawin, J. Appl. Phys. 80, 1304 (1996). @footnote 2@ N. Mizutani, Y. Nagata, A. Kubo and T. Hayashi, Rev. Sci. Instrum. 69, 1918 (1998). @footnote 3@ N. Mizutani and T. Hayashi, Jpn. J. Appl. Phys. 38, 4206 (1999).