AVS 53rd International Symposium
    Plasma Science and Technology Friday Sessions
       Session PS2-FrM

Paper PS2-FrM5
2D-t Plasma Image during One Bias Period of a 2f-CCP in Ar by Emission CT

Friday, November 17, 2006, 9:20 am, Room 2011

Session: Diagnostics
Presenter: T. Ohmori, Keio University, Japan
Authors: T. Ohmori, Keio University, Japan
T. Kitajima, Keio University, Japan
T. Makabe, Keio University, Japan
Correspondent: Click to Email
It has been required to maintain the radial uniformity of the ion velocity distribution incident on an oxide wafer biased deeply by a LF source in a 2f-CCP. The ion velocity distribution synchronized with the sheath dynamics in front of the biased wafer is one of the critical internal plasma parameters further to control and optimize the etching profile in the next generation of the technology having an allowance within several nm. In our previous paper, we have performed a design of the functional separation in a 2f-CCP. High density plasma is sustained at a VHF (100 MHz) source, while the high energy ions are produced by a LF (500 kHz) bias source without additional discharge. We have experimentally investigated the temporal image at the central z-axis @LAMBDA@(z, t; r = 0) and at the radial position at fixed z @LAMBDA@(r, t; z), and the time-averaged image in the 2D space @LAMBDA@(r, z) in a 2f-CCP by using the CT of the optical emission from the short-lived Ar(2p@sub 1@) and Ar+(4p@super 4@D@sub 7/2@) as a probe of the plasma structure and the transport of the secondary electrons.@footnote 1@ In this work, we reconstruct an automatic CT system for the detection of the line integral of the emission in the entire space of the reactor, and demonstrate the temporal change of the 2D image @LAMBDA@(z, r, t) in a full gap of 20 mm of parallel plates during one cycle of the bias in a 2f-CCP at 25 mTor in Ar. In particular, we focus on the profile of the sheath-bulk edge and of the electrode-wall interaction as a function of bias phase in the results of the 2D-t images. @FootnoteText@ @footnote 1@T. Kitajima, Y. Takeo, N. Nakano, and T. Makabe, J. Appl. Phys. 84, 5928(1998). T. Kitajima, Y. Takeo, and T. Makabe J. Vac. Sci. Technol. A 17, 2510 (1999).