Probe measurements and global model of inductively coupled Ar/CF4 discharges

The electron energy distribution function (EEDF) is measured with a Langmuir probe in an inductively-coupled radio frequency (RF, 13.56 MHz) Ar/CF4 discharge over a pressure range 3-30 mTorr by changing the CF4 content from 0 to 20%, while keeping the power injected into the plasma at about 50 W. EEDFs measured at a pressure lower than 10 mTorr are bi-Maxwellian distributions over the measured CF4 content, while those at a pressure of 30 mTorr are Druyvesteyn ones in the presence of a small amount of CF4. The average electron energy slightly increases with CF4 content, while the electron density decreases. The decrease in the electron density with addition of CS is more prominent as the total pressure increases. Dependences of the electron density and the averaged electron energy on CF4 content are predicted in the global model.