Spectrometry of 0.46 and 13.56MHz Ar∕SF6 inductive plasma discharges

The neutral and positive ion species of two inductively coupled plasma (ICP) discharges, operated with low-pressure argon and sulfur hexafluoride (Ar∕SF6) gas mixtures, are studied with optical emission and mass spectrometry. Similar discharges sustained in the two ICPs show significantly different species. The spectra of the 0.46MHz hemispherical ICP suggest nearly pure Ar∕SF6 discharges. The spectra of the 13.56MHz planar ICP reveal many species containing silicon and oxygen, from etching of the quartz dielectric. Etch rate measurements support these observations.