AVS 46th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoM

Paper TF-MoM1
Investigation of the Plasma Properties and Fluxes in a Hydrogenated Amorphous Carbon Deposition Process

Monday, October 25, 1999, 8:20 am, Room 615

Session: Fundamentals of PECVD
Presenter: T.A. Grotjohn, Michigan State University
Authors: B.K. Kim, Michigan State University
T.A. Grotjohn, Michigan State University
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The deposition process and conditions used for hydrogenated amorphous carbon (a-C:H) film deposition from acetylene, acetylene-helium, and acetylene-argon gas mixtures in a microwave ECR plasma reactor are studied. This paper quantifies the plasma discharge fluxes to the substrate based on experimental measurements and plasma discharge modeling. The film properties are also correlated to the plasma discharge conditions. The films are deposited on glass and silicon substrates which are placed on an rf biased (13.6 MHz) substrate holder located just at the exit of a multipolar, permanent magnet ECR plasma source operating at 2.45 GHz. The deposition parameters varied during this investigation included rf induced dc substrate bias voltage (-50 to -300 V), pressure (0.1-1.0 mTorr) and argon/acetylene (or helium/acetylene) gas flow ratio. The properties of the plasma discharge measured include electron temperature, ion saturation current, and residual gas composition. The films deposited with different gas mixtures, pressures and rf biases have substantially different properties including deposition rate, mass density, optical absorption coefficient, optical bandgap and hydrogen content. The use of lower pressures to obtain an increased ion-flux/neutral-flux ratio to the substrate was found to be critical for obtaining dense, low hydrogen content films from acetylene. The addition of argon and helium were found to substantially change the plasma discharge deposition conditions, as well as, influence the deposited film properties.