Ion and neutral species in C{sub 2}F{sub 6} and CHF{sub 3} dielectric etch discharges
- The Pennsylvania State University, University Park, Pennsylvannia 16802 (United States)
- Sandia National Laboratories, Albuquerque, New Mexico (United States)
Relative concentrations of reactive ions, neutral radicals, resist and substrate etch products have been measured in dielectric etch chemistries using an uncollided beam mass spectrometer/ion extractor from Hiden Analytical. Analysis techniques employed include both electron impact ionization and dissociative ionization of neutral gas, and potential bias extraction of positive ions from the reactor discharge volume. Measurements were made in C{sub 2}F{sub 6} and CHF{sub 3} discharges in an inductively coupled plasma (GEC) research reactor operating with power densities, pressures, gas compositions and wafer materials typical of those found in etch processing tools. Wafer substrates investigated included blanket silicon wafers and silicon wafers with varying amounts of photoresist coverage of the surface (20{percent}, 80{percent} and 100{percent}). In C{sub 2}F{sub 6} discharges CF{sub 3}{sup +} was consistently the dominant fluorocarbon ion present, in agreement with published cross sections for dissociative ionization. Smaller concentrations of CF{sup +}, CF{sub 2}{sup +}, and C{sub 2}F{sub 5}{sup +}, were also observed, though the dissociative ionization production of C{sub 2}F{sub 5}{sup +} was a factor of 5 smaller than would be expected from published cross section values. The presence of photoresist, even in small amounts, was found to produce marked changes in the discharge composition. For example, in C{sub 2}F{sub 6} discharges, concentrations of SiF{sub x} etch products relative to concentrations of C{sub x}F{sub y} species were notably diminished and larger concentrations of water vapor were observed when resist was present. In CHF{sub 3} discharges, CF{sub 3}{sup +} and CHF{sub 2}{sup +} were found to be the main species present, along with smaller concentrations of CF{sub 2}{sup +}, CF{sup +}, CHF{sup +}, CH{sup +} and F{sup +}. {copyright} {ital 1999 American Vacuum Society.}
- OSTI ID:
- 359791
- Report Number(s):
- CONF-981126-; ISSN 0734-2101; TRN: 9914M0039
- Journal Information:
- Journal of Vacuum Science and Technology, A, Vol. 17, Issue 4; Conference: 45. annual American Vacuum Society symposium and topical conference, Baltimore, MD (United States), 2-6 Nov 1998; Other Information: PBD: Jul 1999
- Country of Publication:
- United States
- Language:
- English
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