Discharge asymmetry induced by the pulsed radio-frequency current

Through particle-in-cell/Monte Carlo simulations, the discharge asymmetry induced by the pulsed radio-frequency (rf) form of the driving current is found in capacitively coupled plasmas. It is shown that this discharge asymmetry originates from the phase shift between the rf current and voltage during the current-on time. Consequently, the degree of the asymmetry can be controlled by varying the phase of the rf current. As the duty ratio decreases, the plasma density decreases but the dc bias increases. Hence, it is possible to control the ion flux and ion bombardment energy independently by varying both the amplitude of the rf current and the duty ratio.