AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS1-MoA

Paper PS1-MoA5
Stabilization of Radical Composition Drift in Fluorocarbon Plasmas

Monday, November 15, 2004, 3:20 pm, Room 213A

Session: Plasma Surface Interactions in Etching
Presenter: K. Nakamura, Chubu University, Japan
Authors: K. Nakamura, Chubu University, Japan
H. Sugai, Nagoya University, Japan
K. Oshima, Sony, Japan
A. Ando, Sony, Japan
T. Tatsumi, Sony, Japan
Correspondent: Click to Email
Fluorocarbon discharges have been widely used for etching processes of dielectric thin films for microfabrication. However, these have suffered from various problems, in particular, repeatability of the etching characteristics. The problem becomes recently severe due to narrow process margin for next generation ULSI devices. One of the major origins is plasma-surface interaction on polymer-deposited vessel wall, leading to significant time-variation of radical composition of the plasma. Alternating ion bombardment (AIB) method has been proposed to reduce such interactions by applying a RF bias to the chamber wall@footnote 1@. This paper reports the effects of the AIB on polymer film deposition onto the chamber walls and the time-variation of radical density in fluorocarbon plasma reactors. 13.56 MHz inductively-coupled plasmas are produced in Ar-diluted C@sub 4@F@sub 8@ gases in a stainless steel chamber in which two semi-cylindrical electrodes are set. A 400 kHz RF source serves alternating negative bias to the electrodes. The AIB drastically suppressed polymer deposition on the biased wall, and the deposition rate decreases by one order of magnitude with ~100 eV ion bombardment compared to the non-bias case. On the other hand, the AIB also reduces a rise time of densities of the fluorocarbon radicals after the discharge starts, and reached to steady state within ~10 s for CF@sub 2@ radicals. @FootnoteText@ @footnote 1@K. Nakamura et al: J. Vac. Sci. Techonol. A 18 (2000) 137.