Hits:

Indexed by:期刊论文

Date of Publication:2018-04-01

Journal:CHINESE PHYSICS B

Included Journals:SCIE

Volume:27

Issue:4

ISSN No.:1674-1056

Key Words:ion energy distribution; phase shift; synchronous pulse modulated; inductively coupled plasmas

Abstract:A retarding field energy analyzer (RFEA) is used to measure the time-averaged ion energy distributions (IEDs) on the substrate in both continuous wave (CW) and synchronous pulse modulated radio-frequency (RF) inductively coupled Ar plasmas (ICPs). The effects of the phase shift theta between the RF bias voltage and the RF source on the IED is investigated under various discharge conditions. It is found that as theta increases from 0 to pi, the IED moves towards the low-energy side, and its energy width becomes narrower. In order to figure out the physical mechanism, the voltage waveforms on the substrate are also measured. The results show that as q increases from 0 to pi, the amplitude of the voltage waveform decreases and, meanwhile, the average sheath potential decreases as well. Specifically, the potential drop in the sheath on the substrate exhibits a maximum value at the same phase (i.e., theta = 0) and a minimum value at the opposite phase (i.e., theta = pi). Therefore, when ions traverse across the sheath region above the substrate, they obtain less energies at lower sheath potential drop, leading to lower ion energy. Besides, as theta increases from pi to 2 pi, the IEDs and their energy widths change reversely.