Inductively Coupled Plasmas in Low Global Warming Potential Gases

Published

August 1, 2000

Author(s)

Amanda N. Goyettes, Yicheng Wang, James K. Olthoff

Abstract

Many high density discharges used in microelectronics fabrication use fluorocarbon gases with coincidentally high global-warming potentials (GWPs). We have determined the identities, fluxes, and energy distributions of ions produced in high density discharges generated in two low GWP gases, CF₃I and CF₃CH₂F (HFC-134a), which have attracted interest for plasma processing applications. Measurements were made using a combined ion energy analyser-mass spectrometer that samples ions through an orifice in the lower electrode of an inductively coupled Gaseous Electronics Conference (GEC) rf reference cell. The effects of plasma operating conditions and Ar dilution on ion fluxes and energies were examined. Nearly complete dissociation of CF₃I occurs in CF₃I discharges and I⁺ comprises almost all of the ion yield. Mean ion energies range from 5-10 eV for the operating conditions investigated. Discharges generated in mixtures of CF₃I with Ar have ion fluxes and energies resembling those in pure CF₃I discharges. Pure HFC-134a discharges produce several ions of significant intensity, with HF⁺ and Si⁺ being the most abundant. Mean ion energies range from 20-35 eV, and decrease as HFC-134a is diluted with Ar. Higher discharge powers result in greater dissociation in HFC-134a discharges, shifting the ion composition towards higher fluxes of lighter ions.

Citation

Journal of Physics D-Applied Physics

Volume

33

Pub Type

Journals

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Keywords

CF3CH2F, CF3I, GEC rf reference cell, inductively coupled plasma, ion energy distribution, ion flux

Citation

Goyettes, A. , Wang, Y. and Olthoff, J. (2000), Inductively Coupled Plasmas in Low Global Warming Potential Gases, Journal of Physics D-Applied Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=29982 (Accessed April 19, 2024)