Measurement of electronegativity during the E to H mode transition in a radio frequency inductively coupled Ar/O2 plasma*
- 23 November 2020
- journal article
- research article
- Published by IOP Publishing in Chinese Physics B
- Vol. 30 (3), 035202
- https://doi.org/10.1088/1674-1056/abccb0
Abstract
This paper presents the evolution of the electronegativity with the applied power during the E to H mode transition in a radio frequency(rf) inductively coupled plasma (ICP) in a mixture of Ar and O2. The densities of the negative ion and the electron, as well as their ratio, i.e., the electronegativity, are measured as a function of the applied power by laser photo-detachment combined with a microwave resonance probe, under different pressures and O2 contents. Meanwhile, the optical emission intensities at Ar 750.4 nm and O 844.6 nm are monitored via a spectrograph. It was found that by increasing the applied power, the electron density and the optical emission intensity show a similar trench, i.e. they increase abruptly at a threshold power, suggesting that the E to H mode transition occurs. With the increase of the pressure, the negative ion density presents opposite trends in the E-mode and the H-mode, which is related to the difference of the electron density and energy for the two modes. The emission intensities of Ar 750.4 nm and O 844.6 nm monotonously decrease with increasing the pressure or the O2 content, indicating that the density of high-energy electrons, which can excite atoms, is monotonically decreased. This leads to an increase of the negative ion density in the H-mode with increasing the pressure. Besides, as the applied power is increased, the electronegativity shows an abrupt drop during the E to H mode transition.Keywords
This publication has 43 references indexed in Scilit:
- The spatial distribution of negative oxygen ion densities in a dc reactive magnetron dischargeJournal of Physics D: Applied Physics, 2012
- A study of the plasma electronegativity in an argon–oxygen pulsed-dc sputter magnetronJournal of Physics D: Applied Physics, 2010
- Using the resonance hairpin probe and pulsed photodetachment technique as a diagnostic for negative ions in oxygen plasmaPlasma Sources Science and Technology, 2010
- Negative ion density measurements in a reactive dc magnetron using the eclipse photodetachment methodPlasma Sources Science and Technology, 2010
- A floating hairpin resonance probe technique for measuring time-resolved electron density in pulse dischargeMeasurement Science and Technology, 2007
- Oxygen discharges diluted with argon: dissociation processesPlasma Sources Science and Technology, 2007
- The distribution of ion energies at the substrate in an asymmetric bi-polar pulsed DC magnetron dischargePlasma Sources Science and Technology, 2002
- Hysteresis and the E-to-H transition in radiofrequency inductive dischargesPlasma Sources Science and Technology, 1999
- Inductive plasmas for plasma processingPlasma Sources Science and Technology, 1996
- Plasma diagnostics in negative ion sourcesPlasma Sources Science and Technology, 1993