Measurement of electron energy distribution in low-pressure RF discharges

Abstract

Electron energy distribution functions (EEnFs) have been measured in low-pressure capacitive R F discharges over a wide range of well defined (geometrically and electrically) discharge conditions. Measurements have been made in argon and helium ranging in gas pressure between 3mTorr and 3Torr and in discharge current density between 0.1 mAcm-Z and 10mAcm-Z. The measurements show changes in the EEDF due to the occurrence of physical phenomena such as stochastic electron heating and t h e effect of discharge transition into the y mode. Substantial differences in the EEDF in Ramsauer and non-Ramsauer gases are also demonstrated and discussed. To achieve these results a higher level of performance was required from the measurement system than had been attained in previous EEnF measurements in R F discharges. EEnF measurements were made using a probe system specifically designed to remove or reduce the severity of many problems inherent to such measurements in RF discharges. The rationale and considerations in the probe system design, as well as many construction details of the probe system itself, are discussed.

Electron energy distribution function close to the mode transition region in an inductively coupled gaseous electronics conference reference cell

“…For our purpose, the absence of the ͱ −eU term in the EEPF eases the demonstration of differences in the shape of the distribution function. 18 Figure 1 shows the evolution of the EEPF with increasing power at 1.33 Pa. At 41 W in the E mode the EEPF is obviously a Maxwellian. At 47 W the low-energy part ͑be-low 5 eV͒ of the EEPF is slightly enhanced and has a steeper slope.…”

A non-Maxwellian kinetic approach for charging of dust particles in discharge plasmas

“…Two different dust density profiles were taken in our simulation: (a) one with a maximum in the center of the discharge gap, n d (x) = n max sin(π(x − l s )/(d − 2l s )), and (b) with two maxima near the electrode sheaths and a void in the gap center, which is often observed in experiments, n d (x) = n max sin 2 …”

“…However, it is known from experiments that in a capacitively coupled radio frequency (ccrf) discharge without dust the electron energy distribution function (EEDF) can be far from Maxwellian even in a bulk plasma. The EEDFs were measured in [2] in a ccrf discharge in helium and argon to illustrate the difference in the electron kinetics in non-Ramsauer and Ramsaur gases. It was shown that in helium the shape of the EEDF remains Maxwellian for all pressures.…”

Ion energy distribution measurements in rf and pulsed dc plasma discharges

“…The EEDFs are bi-Maxwellian with the two temperatures remaining approximately constant as a function of power. The bi-Maxwellian EEDF is now a well understood feature of low pressure CCP discharges [38].…”