Measurements of Electron Energy Distribution Functions in Pulse-Modulated Ar and Ar/O 2 Inductively Coupled Plasmas using Laser Thomson Scattering

The time-resolved electron energy distribution functions (EEDFs) in Ar and Ar/O 2 pulse-modulated inductively coupled plasmas have been measured in the afterglow for the first time using laser Thomson scattering. The measurements were performed for RF powers of 100 and 500 W at a frequency of 13.56 MHz, a duty cycle of 50%, and a pulse repetition frequency of 12.5 kHz. The Ar pressures were 20 and 100 mTorr at a flow rate of 132 sccm, and the Ar/O 2 (10% O 2 ) pressure was 20 mTorr at a flow rate of 132 sccm. The measured EEDFs were all Maxwellian for the Ar and Ar/O 2 (10% O 2 ) plasmas. The Maxwellian distributions in the afterglow may be attributed to electron–electron collisions.