Electron power absorption in radio frequency driven capacitively coupled chlorine discharge

Particle-in-cell Monte Carlo collision simulations and Boltzmann term analysis are applied to study the origination and properties of the electric field and the electron power absorption within the electronegative core of a capacitively coupled discharge in chlorine as the pressure is varied in the range from 1 to 50 Pa.  The electronegativity is very high and the electron power absorption is mainly due to drift-ambipolar (DA) electron power absorption as electric field develops within the electronegative core [1]. It is found that the electron power absorption increases and the ion power absorption decreases as the pressure is increased. At 1 Pa the electron power absorption is due to both the pressure and Ohmic terms. At the higher pressures > 10 Pa the Ohmic term dominates and all the other contributions to the electron power absorption become negligible, and the discharge eventually behaves as a resistive load.  Tailored voltage waveform, composed of a fundamental frequency and the second harmonic are then applied to the capacitive chlorine discharge [2].  For pressures of 1 and 10 Pa the creation of a dc self-bias and asymmetric response is demonstrated and applied to control the ion bombardment energy while the ion flux on the electrodes remains fixed. However, the available range in mean ion energy is rather limited and the range is significantly narrower than typically observed for electropositive discharges. For operating pressure of 50 Pa it is not possible to control the ion bombardment energy by the phase angle between the fundamental frequency and the second harmonic.