On electron heating in a low pressure capacitively coupled oxygen discharge

Abstract

We use the one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 to explore the charged particle densities, the electronegativity, the electron energy probability function (EEPF), and the electron heating mechanism in a single frequency capacitively coupled oxygen discharge when the applied voltage amplitude is varied. We explore discharges operated at 10 mTorr, where electron heating within the plasma bulk (the electronegative core) dominates, and at 50 mTorr where sheath heating dominates. At 10 mTorr the discharge is operated in combined drift-ambipolar (DA) and α-mode and at 50 mTorr it is operated in pure α-mode. At 10 mTorr the effective electron temperature is high and increases with increased driving voltage amplitude, while at 50 mTorr the effective electron temperature is much lower, in particular within the electronegative core, where it is roughly 0.2 -0.3 eV, and varies only a little with the voltage amplitude.

The role of surface quenching of the singlet delta molecule in a capacitively coupled oxygen discharge

“…Also by increasing the voltage at a fixed pressure, a transition from the DA-mode to the α-mode is observed in a CF 4 discharge [13]. Oxygen behaves in the opposite way, by increasing the pressure at a given voltage a transition from the DA-α-mode to the α-mode is observed in the oxygen discharge [31]. This is a similar to the transition reported by Derzsi et al [35] which observe an operation mode transition from DA-α-mode to α-mode in an oxygen discharge as harmonics are added to the voltage waveforms for 10 and 15 MHz driving frequency, which also coincides with a strong decrease in the electronegativity.…”

“…the pressure [27], the driving voltage amplitude [31], and the driving frequency [32]. Here we take a different approach and calculate the partial pressure for each combination of pressure and surface quenching coefficient using a global (volume averaged) model as discussed in section II C. The two electrodes are assumed to be identical, and the surface coefficients, surface recombination and surface quenching, are kept the same at both electrodes.…”

Electron power absorption dynamics in a low pressure radio frequency driven capacitively coupled discharge in oxygen

“…In recent years the oxygen reaction set in the oopd1 code has been improved significantly [12][13][14]. The oopd1 code has been applied to explore the electron power absorption in the capacitively coupled oxygen discharge while varying the various external parameters and operating conditions such as discharge pressure [14][15][16], driving voltage amplitude [17], driving frequency [18], the secondary electron emission [14,19], the surface quenching of the metastable states [20] and the electrode gap distance [21].…”

Experimental and computational investigations of the effect of the electrode gap on capacitively coupled radio frequency oxygen discharges

“…56 As mentioned above, in order to gain access to various discharge characteristics such experimental studies should also be accompanied by modeling/simulations, which is now possible with accurate kinetic PIC/MCC codes developed recently. 44, [57][58][59][60][61] Therefore, in this work, we investigate the effects of changing the electrode gap on important plasma characteristics such as the central electron density, electronegativity, mean electron energy, and ion flux-energy distribution functions in low pressure single-frequency CCPs operated at 13.56 MHz in O 2 . We also study the time averaged optical emission from atomic oxygen lines and the spatio-temporal ionization dynamics.…”