Absolute density measurement of cyanogen fluoride in CHF3/N2 electron cyclotron resonance plasma using infrared diode laser absorption spectroscopy

The absolute density of the cyanogen fluoride (FCN) molecule has been measured in a CHF3/N2 electron-cyclotron-resonance (ECR) plasma using infrared diode laser absorption spectroscopy. The R(22) rotational-vibrational line at 1060.340 cm−1 in the ν1 fundamental of F19C12N14 was used for the spectroscopy. The extinction process of FCN in the afterglow was discussed on the basis of the decay rate after discharge termination. Moreover, the absolute FCN density in a CHF3 ECR plasma during etching of silicon nitride has been calculated on the basis of the data shown in our previous study [K. Miyata et al., J. Vac. Sci. Technol. A 15, 568 (1997)]. It was found that approximately 10% of nitrogen atoms coming from silicon nitride formed FCN.