Ionic Species in 13.56 MHz Discharges in CF 4 Gas and Mixtures of It with Ar and O 2

Signal intensities of positive ions were measured in situ by direct sampling from parallel-plate discharges in CF4/Ar and CF4/O2 mixtures using a quadrupole mass spectrometer. Major positive ions in CF4/Ar discharge are CF x + (x=3, 2, 1) and Ar+. Some of the production of CF2 + and CF+ is considered to be due to the contribution of Ar+. Major positive ions in CF4/O2 discharge are CF3 +, O y + and F y + (y=2, 1). The signal intensity of CO2 + is of the same order as that of F y +. The signal intensities of F y + and O+ in CF4/O2 discharge are higher than those in pure CF4 and O2 discharges, respectively. Intensity ratios of the ions vary with the gas mixing ratios.