Direct Spectroscopic Evidence of the Influence of Chamber Wall Condition on Oxide Etch Rate |
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Authors: | Lee Szetsen Tien Yu-Chung Hsu Chin-Fa |
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Institution: | (1) Winbond Electronics Corporation, Fab 4, 9 Li Hsin Road, Hsinchu, 300, Taiwan |
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Abstract: | The drift of TEOS etch rate has been observed during MERIE oxide etch for the damascene process. The etch rate typically fluctuates between 5300 Å/min and 6000 Å/min. Studies using fluorocarbon-based chemistry show a normal TEOS etch rate when the chamber wall is heavily coated with polymer deposition. On the other hand, a lower etch rate appears when the chamber has less deposition. Hysteresis behavior has been observed during the etch rate of TEOS, as well as emission intensity trends of F, CF
x
(x=1~3), and SiF. From the observed emission intensity variation of F, CF
x
, and SiF, a model is proposed to explain the impact of chamber wall polymer deposition on the etch rate of TEOS. This model includes a mechanism of etch rate enhancement by embedding oxygen in the chamber wall polymer. From the correlation between etch rate and emission intensity, it clearly shows that F is directly responsible for the etch of TEOS. Compared to F, CF
x
plasma chemistry has a closer link to chamber wall polymer formation, but contributes less in the etch of TEOS. |
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Keywords: | Oxide etch polymer deposition emission plasma hysteresis fluorocarbon Le Chatelier's principle |
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