AVS 50th International Symposium
    Plasma Science and Technology Friday Sessions
       Session PS-FrM

Paper PS-FrM2
Study of Gas Phase Fluorocarbon Chemistries in a Modified Gaseous Electronics Conference Plasma Reactor Using Fourier Transform Infrared Spectroscopy and Ellipsometry

Friday, November 7, 2003, 8:40 am, Room 315

Session: Plasma-Surface Interactions: Etching
Presenter: B. Zhou, University of Texas at Dallas
Authors: B. Zhou, University of Texas at Dallas
E.A. Joseph, University of Texas at Dallas
S.P. Sant, University of Texas at Dallas
L.J. Overzet, University of Texas at Dallas
M.J. Goeckner, University of Texas at Dallas
Correspondent: Click to Email
Fluorocarbon chemistries of CF@sub 4@ plasmas during dry etching are studied in the modified Gaseous Electronics Conference (mGEC) Reference cell, using Fourier Transform Infrared (FTIR) spectroscopy. These measurements are enhanced by the use of a multi-pass White cell with capabilities up to 40 passes. The flexible design of the mGEC reactor allows us to study the effect of the dimensions, materials and wall conditions of a plasma reactor on the gas phase and surface phase chemistries, as well as the interactions between them. Three sets of inner walls with diameters of 20.3, 40.6, and 61 cm are used and the wall temperature can be raised above 100°C. The gap between the quartz window and chuck can be varied from 2.7cm to 18 cm. For a 5 cm gap, the IR spectra show that the concentrations of CF@sub 2@ and CF@sub 3@ radicals and etch products such as SiF@sub 4@ and COF@sub 2@, are strongly dependent upon the bias voltage. The concentration of CF@sub 2@ radicals is raised by about an order of magnitude to 10@sup 13@ cm@sup -3@ when the chuck self-bias voltage is changed from 0 to -40V. In addition, the concentration ratio of CF@sub 2@ to CF@sub 3@ increases as the bias voltage is made more negative due to an increased etch rate and increased consumption of F atoms. These gas phase measurements will also be compared with etch rate measurements using in-situ spectroscopic ellipsometry. Finally, the experimental data will be compared with simulation results using HPEM.@footnote 1@ This work is supported by a grant from NSF/DOE, CTS-0078669. @FootnoteText@ @footnote 1@ D. Zhang and M. J. Kushner, "Surface Kinetics and Plasma Equipment Model for Si Etching by Fluorocarbon Plasmas", J. Appl. Phys. 87, 1060 (2000).