Experimental and theoretical study of dynamic effects in low-frequency capacitively coupled discharges

Abstract

A low-frequency capacitively coupled radio-frequency (rf) discharge in Ar excited at 1.76 MHz is studied both experimentally and theoretically. Experimental measurements of electron concentration, discharge voltage and current are presented for a wide range of rf input powers. The rf current shape is nonsinusoidal, close to the triangle one. The evolution of Ar(2p1) emission excitation function in the interelectrode gap during an rf cycle is measured using the phase-resolved optical emission spectroscopy technique. Theoretical study is based on the particle-in-cell Monte Carlo collision numerical simulation. Specific dynamic features of the low-frequency discharge are discussed. The important role of secondary electrons in discharge maintenance and power balance is shown. This study is crucial for understanding dual-frequency discharges with a corresponding value of low frequency.

The effect of ambipolar electric fields on the electron heating in capacitive RF plasmas

“…In addition, there is also a strong field reversal during sheath collapse in helium [35][36][37][38][39]. Similar ambipolar electric field structures and field reversal effects have been observed by Braginsky et al in CCRF discharges driven at a lower driving frequency of 1.76 MHz [49]. The horizontal layer of high electric field outside the sheath results in strong electron heating during the first half of the RF period, when the sheath expands, and cooling during the second half, when the sheath collapses [figs.…”

Modeling of Single and Dual Frequency Capacitive Discharge in Argon Hydrogen Mixture − Dynamic Effects and Ion Energy Distribution Functions

“…The described PIC MCC model was used to study the CCP discharge in single and dual‐frequency case in pure argon and in Ar/CF 4 /CHF 3 mixture …”

“…The hybrid approach is used, in which particle‐in‐cell with Monte Carlo Collision method (PIC MCC) is applied to electrons, ions, and fast neutrals, and the fluid approach is used for thermal neutral species in Ar/H 2 plasma chemistry. The detail description of our PIC MCC‐hybrid model can be found in papers . The equations for neutral chemistry are described in detail in ref ,.…”

“…The secondary electron emission (SEE) from the electrodes may play essential role in the CCP discharges . Our model includes SEE induced by ions, fast Ar atoms and metastable atoms Ar m .…”

“…This electron reflection processes are important when the large sheath voltage is applied. Including these processes in the simulation of SF 1.76 MHz discharge in argon allows us to describe better the experimental spatio‐temporal distribution of Ar(2p 1 ) atom emission . The detailed description of these processes treating in PIC MCC model can be found in paper …”