AVS 46th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoP

Paper PS-MoP2
Surface Reactivities of Radicals in Fluorine Containing Plasmas

Monday, October 25, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: C.I. Butoi, Colorado State University
Authors: C.I. Butoi, Colorado State University
E.R. Fisher, Colorado State University
Correspondent: Click to Email
Fluorocarbon plasmas have a variety of applications such as generation of interlevel dielectric films and etching in the microelectronics industry, as well as generation of polymeric biocompatible materials. Understanding deposition and etching mechanisms is a difficult task given the complexity of plasma systems. Using the imaging of radicals interacting with surfaces (IRIS) technique, we are able to investigate the behavior of one plasma species at a time. Hexafluoropropylene oxide (HFPO) has shown great promise for generating high CF@sub 2@ content films, and CF@sub 2@ radicals have been postulated as the main deposition precursors. Thus, studying the reactivity of CF@sub 2@ radicals impinging on surfaces is of the utmost importance in understanding film formation mechanisms. In the IRIS experiments, CF@sub 2@ spatially resolved LIF signals are collected and analyzed using a geometrical simulation of the experiment. Fitting the experimental data to simulated fits generates scatter values, S, for CF@sub 2@ radicals. S values less than 1 indicate loss of CF@sub 2@ moieties at the substrate surface, whereas S > 1 suggests surface generation of CF@sub 2@. In CW HFPO plasmas, S values of 1 were calculated for silicon based and polymeric substrates regardless of the rf power employed. Pulsed plasmas were also used and duty cycles were varied. A decrease in the CF@sub 2@ scatter coefficients was observed for both substrates tested at all duty cycles. Also, the CF@sub 2@ S values were determined when a grounded mesh was placed in the path of the molecular beam in order to probe the possible role of ions generated in the plasma. Decreases in S were observed under these conditions. To further investigate ion effects, silicon substrates were biased at +200V, which resulted in S 0.5-0.6. Additional results for plasma etching systems will be presented.