In situ real-time monitoring of profile evolution during plasma etching of mesoporous low-dielectric-constant SiO{sub 2}
- University of New Mexico, Albuquerque, New Mexico 87131 (United States)
We have employed attenuated total reflection Fourier transforms infrared spectroscopy (ATR-FTIRS) to monitor the profile evolution of patterned mesoporous, low-dielectric-constant SiO{sub 2} films in situ and in real time during plasma etching. A stack of patterned photoresist, anti-reflective coating, and mesoporous SiO{sub 2} is etched in an inductively coupled plasma reactor, using CHF{sub 3} and Ar. During etching, the IR absorbance of Si-O-Si stretching modes near 1080 cm{sup -1} decreases, and the rate of decrease in Si-O-Si absorbance translates to the SiO{sub 2} removal rate. When corrected for the exponentially decaying evanescent electric field, the removal rate helps monitor the profile evolution and predict the final etch profile. The predicted profiles are in excellent agreement with the cross-sectional images taken by scanning electron microscopy. In a similar approach, we calculate the absolute total number of C-F bonds in the sidewall passivation and observe its formation rate as a function of time. Assuming that the thickness of the sidewall passivation tapers down towards the trench bottom, we deduce that C-F formation occurs mostly in the final stage of etching when the trench bottom meets the Ge ATR crystal and that a critical amount of C-F buildup is necessary to maintain the anisotropic etch profile.
- OSTI ID:
- 20637029
- Journal Information:
- Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films, Vol. 23, Issue 2; Other Information: DOI: 10.1116/1.1865154; (c) 2005 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0734-2101
- Country of Publication:
- United States
- Language:
- English
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