IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Plasma Science Thursday Sessions
       Session PS-ThP

Paper PS-ThP27
The Effect of Reflected Ions on the Etching of Silicon Dioxide Surface in the Fluorocarbon Plasma

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Plasma Etching Poster Session
Presenter: G.R. Lee, Seoul National University, Korea
Authors: G.R. Lee, Seoul National University, Korea
S.H. Hwang, Seoul National University, Korea
J.H. Min, Seoul National University, Korea
S.H. Moon, Seoul National University, Korea
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In the plasma etching process, ions reflected from the sidewall surface of a deep, narrow pattern contribute to the additional etching of the other surfaces, which may be called as a secondary etching. When the aspect ratio of the etched pattern becomes high, the influence of the secondary etching on the etch profile becomes significant. In spite of its importance, however, the secondary etching due to the reflected ions has not been studied much especially under the conditions of industrial plasma processes. In many cases of the etch-profile simulation, it has been commonly assumed that ions reflect from the sidewall in an elastic-specular mode, particularly when the ion-incident angle is high. In this study, we observed the position and the extent of the secondary etching of silicon dioxide in a fluorocarbon plasma due to the reflected ions with various incident angles. The ion angles were controlled by using a Faraday cage and specially fabricated sample holders placed in a plasma reactor. The experimental results deviated from those predicted based on an elastic-specular assumption when the ion-incident angles were close to 90°. According to the analysis of the substrate surface after the plasma etching, the deviation of the ion reflection from the elastic-specular mode originated from the deposition of a fluorocarbon film on the substrate surface. The film-deposited surface became rough, and consequently ions reflected from the surface in a non-elastic, non-specular mode.