Measurement of the CF3radical using infrared diode laser absorption spectroscopy

Abstract

A measurement method for the CF₃ radical using infrared diode laser absorption spectroscopy (IRLAS) was established. The CF₂ radical density in a RF discharge CHF₃ plasma was measured first. The obtained density was estimated to be of the order of 10¹³ cm^-1 under the assumptions concerning the laser pathlength and radical temperatures. The spatial distribution of the CF₃ radical density was almost uniform between the electrodes. Moreover, the CF₃ and CF radical densities were measured as a function of H₂ partial pressure, showing that the CF₃ radical decreases with addition of H₂ gas more rapidly than the CF radical.