Cho, Byeong-Ok
(School of Chemical Engineering and Institute of Chemical Processes, Seoul National University, Shillim-dong San 56-1, Kwanak-ku, Seoul 151-742, Korea)
,
Hwang, Sung-Wook
(School of Chemical Engineering and Institute of Chemical Processes, Seoul National University, Shillim-dong San 56-1, Kwanak-ku, Seoul 151-742, Korea)
,
Lee, Gyeo-Re
(School of Chemical Engineering and Institute of Chemical Processes, Seoul National University, Shillim-dong San 56-1, Kwanak-ku, Seoul 151-742, Korea)
,
Moon, Sang Heup
(School of Chemical Engineering and Institute of Chemical Processes, Seoul National University, Shillim-dong San 56-1, Kwanak-ku, Seoul 151-742, Korea)
SiO 2 etch rates in a CF4 plasma were obtained at various surface angles using a Faraday cage with pinholes on the upper plane through which ions are incident on the substrate fixed at various angles inside the cage. The reactive ion etching experiments were performed at 5 mTorr in a wide bias-volta...
SiO 2 etch rates in a CF4 plasma were obtained at various surface angles using a Faraday cage with pinholes on the upper plane through which ions are incident on the substrate fixed at various angles inside the cage. The reactive ion etching experiments were performed at 5 mTorr in a wide bias-voltage range from −100 to −800 V. The normalized etch-yield curves showed virtually the same angular dependence regardless of the ion incident energy. The curve shape was similar to that of physical sputtering except that the ratio of the maximum yield to that at 0° was as low as about 1.3. This is the deviation from the cosine dependence characteristic of chemical sputtering, which is the main mechanism of SiO2 etching in a fluorocarbon plasma. This deviation is partly attributed to the fluorocarbon polymer film, which existed as a few monolayers-thick film on the substrate surface at low angles near 0° but as a submonolayer at high angles between 45° and 75°. The effect of the film-coverage difference on the deviation is explained in terms of reactant chemisorption, product desorption, energy deposited by ions causing the collision cascade, and incorporation of projectiles and recoils leading to the mixing effect. The deviation is also attributed to physical sputtering, which became comparable to chemical sputtering as the ion energy increased. Both factors, i.e., the formation of the thin fluorocarbon polymer film and physical sputtering, are supposed to contribute to the curve deviation, although their relative importance changed with the ion incident energy.
SiO 2 etch rates in a CF4 plasma were obtained at various surface angles using a Faraday cage with pinholes on the upper plane through which ions are incident on the substrate fixed at various angles inside the cage. The reactive ion etching experiments were performed at 5 mTorr in a wide bias-voltage range from −100 to −800 V. The normalized etch-yield curves showed virtually the same angular dependence regardless of the ion incident energy. The curve shape was similar to that of physical sputtering except that the ratio of the maximum yield to that at 0° was as low as about 1.3. This is the deviation from the cosine dependence characteristic of chemical sputtering, which is the main mechanism of SiO2 etching in a fluorocarbon plasma. This deviation is partly attributed to the fluorocarbon polymer film, which existed as a few monolayers-thick film on the substrate surface at low angles near 0° but as a submonolayer at high angles between 45° and 75°. The effect of the film-coverage difference on the deviation is explained in terms of reactant chemisorption, product desorption, energy deposited by ions causing the collision cascade, and incorporation of projectiles and recoils leading to the mixing effect. The deviation is also attributed to physical sputtering, which became comparable to chemical sputtering as the ion energy increased. Both factors, i.e., the formation of the thin fluorocarbon polymer film and physical sputtering, are supposed to contribute to the curve deviation, although their relative importance changed with the ion incident energy.
참고문헌 (37)
J. Vac. Sci. Technol. A 12 333 1994 10.1116/1.578877
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