Abstract

Infrared tunable diode laser absorption studies of process plasmas are being carried out in a laboratory reactor which allows a long absorption path. In this paper we report studies of CF₄ and CH₄ radio frequency plasmas. The molecular species whose concentrations have been measured include CF₂, CF₃, and C₂F₆ as well as CF₄ in CF₄ plasmas, CH₃, CH₂, and C₂H₂ as well as CH₄ in methane plasmas. Observations are made for ranges of reactor parameters, including rf power, dilution by Ar or H₂, total pressure, and O₂ addition. Estimation of the plasma temperature from rotational line absorption intensities is also discussed. Recently, several groups have undertaken detailed chemical kinetic modeling of CF₄ and CH₄ discharges. The absolute concentrations presented here should be of use in assessing the predictive capabilities of the models.

© 1989 Optical Society of America