Probe Measurements and Optical Emission Spectroscopy in Inductively Coupled Ar/CF4, Ar/NF3, and Ar/SF6 Discharges

概要

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Experiments of inductive Ar/CF4, Ar/NF3, and Ar/SF6 discharges with a Langmuir probe and optical emission spectroscopy are carried out in the total pressure range of 8–30 mTorr, changing the ratio of the partial pressure of reactive gas to the total pressure (the fraction of the reactive gas) from 0 to 30%. The structure of the measured electron energy probability functions (EEPFs) deviates from the Maxwellian distribution owing to the large depletion of high-energy electrons at any reactive gas fraction. The electron density markedly decreases with increasing reactive gas fraction in the fraction range below 10%, whereas the electron temperature gradually increases. The density of the ground state fluorine atoms in the Ar/SF6 and Ar/NF3 discharges is about 5 times higher than that in the Ar/CF4 discharges. The effects of oxygen addition on the plasma parameters in those discharges are also investigated. The plasma parameters, such as electron density and temperature, do not depend on the fraction of oxygen for the fixed fraction of Ar. On the other hand, the dependence of the fluorine atom density on the fraction of oxygen differs among the inductive Ar/CF4, Ar/NF3, and Ar/SF6 discharges.
2008-11-25