AVS 51st International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP3
Spectroscopic Study of Effect of Wall Conditions on Gas Phase and Surface Phase Chemistries in Inductively Coupled Fluorocarbon Plasmas

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: B.S. Zhou, University of Texas at Dallas
Authors: B.S. 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
The effect of wall conditions including dimension, material, temperature, and cleanliness on the gas phase and surface phase chemistries in CF@sub 4@ plasma etching of Si was studied in the modified Gaseous Electronics Conference (mGEC) reference cell. In the mGEC, Al inner walls of various diameters were used to confine the plasma to the center of the chamber and induce changes in the gas phase chemistry. The range of the wall temperature was 25 -150°C. The gaseous molecules and radicals monitored included CF@sub 4@, CF@sub 3@, CF@sub 2@, SiF@sub 4@ and COF@sub 2@, among which CF@sub 4@ and SiF@sub 4@ were found to be the two dominant species, accounting for about 80% of the total concentration. The density ratio of SiF@sub 4@ and COF@sub 2@ was about 2:1 with no bias on the substrate and increased to ~6:1 when Si substrate etching took place. Specifically, as the Si etch rate increased, the COF@sub 2@ density dropped, likely due to suppressed etching of the quartz source window, while the density of SiF@sub 4@ increased. These rates are likely linked through the atomic fluorine density. In addition, the CF@sub 3@ radical density was observed to increase over time. This is indicative of increased surface production of fluorocarbon species from CF@sub x@ film on the wall. This work is supported by a grant from NSF/DOE, CTS-0078669.