Measurement of CH3 Radical in RF Methane/Rare Gas Plasma Using Infrared Diode Laser Absorption Spectroscopy

Infrared diode laser absorption spectroscopy (IRLAS) was used to measure the CH3 (methyl) radical density in an RF-discharge methane plasma. It was found that the CH3 radical density was of the order of 1012 cm-3. We also measured the CH3 radical density as a function of Xe or Ar gas partial pressure, and this partial pressure dependence shows that the addition of Xe brings about an increase in the CH3 radical density.