Indexed by:期刊论文

Date of Publication:2015-02-28

Journal:JOURNAL OF APPLIED PHYSICS

Included Journals:SCIE、EI、Scopus

Volume:117

Issue:8

ISSN No.:0021-8979

Abstract:A two-dimensional self-consistent electrostatic fluid model and the experimental diagnostic method are employed to investigate the plasma radial uniformity in capacitively coupled nitrogen discharges driven at 60 MHz. The effects of the rf power and electrode gap on the spatial profiles of the N-2(+) ion density and the radial profiles of the ion flux to the lower electrode are demonstrated. It is found in the simulation that with the increase of rf power or the decrease of electrode gap, the electrostatic edge effect becomes remarkable, which gives rise to an increase in the positive ion density at the electrode edge and thus the radial uniformity of plasma becomes worse. Moreover, the radial profiles of the N-2(+) ion flux to the lower electrode show a similar behavior to that of the ion density. These results are further understood by the calculated axial and radial components of the power deposition, which exhibit pronounced peaks at the electrode edge at high rf power or small electrode gap. In order to validate the simulation results, the radial profiles of the N-2(+) ion density were measured by a floating double probe. A general qualitative agreement between the experimental and calculated results is achieved. (C) 2015 AIP Publishing LLC.