AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS-MoP

Paper PS-MoP28
Real-Time Etch Optimization in Electron Cyclotron Resonance-Microwave CO/H@sub 2@ and CO@sub 2@/H@sub 2@ Plasmas

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: A.A. Dyachenko, Auburn University
Authors: A.A. Dyachenko, Auburn University
A.S. Orland, Auburn University
R. Blumenthal, Auburn Univerisity
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Previous results, in our group@super 1@, have indicated that the etch rates of nickel are significantly enhanced when formic acid appears in CO/H@sub 2@ plasmas and when oxalates appear in CO@sub 2@/H@sub 2@ plasmas. At that point, it was not clear whether the formic acid and oxalates are new primary etchants or daughter ions of the metal complex product. In this work, a real-time monitoring of the concentrations of chemically generated species in electron cyclotron resonance (ECR) hydrogen plasmas is investigated by means of supersonic pulse plasma sample mass spectrometry. The influence of various plasma parameters, on the concentration of etching products/etchants and on the actual etch rates, has been examined with a -200 V DC bias at maximum brightness. Above 30% CO concentration, contamination of the vacuum chamber occurs and therefore experiments under such conditions have not been conducted. Upon decreasing the CO fraction from 30% to 5%, an increase on the order of 30% in the formic acid concentration was observed. Increasing microwave power from 150 W to 250 W results in a 20% increase in the formic acid concentration. Correlations and anticorrelations between the concentrations of reactive species formed in the plasma and the etch rates measured by profilometry will be presented along with a chemical mechanism consistent with the observed etch rate enhancement. Similar results for oxalates in CO@sub 2@/H@sub 2@ plasma will also be presented. @FootnoteText@ @footnote 1@ A.Orland, Ph.D. thesis, Auburn University, 2003.