Particle in cell Monte Carlo collision simulations of capacitive Ar/Cl2 discharges: Plasma chemistry

Reactive gases mixed with rare gases in capacitively coupled discharges are often used in etching and deposition processes in microelectronic device fabrication. Chlorine discharge and its mixtures are frequently applied in the etching of semiconductors and metals. Here, capacitive discharges in Ar/Cl2 mixture at 10 Pa in a 2.54 cm gap driven by sinusoidal rf voltage at 13.56 MHz are explored using one-dimensional particle-in-cell/Monte Carlo collision simulations. Chlorine is a highly electronegative discharge gas, whereas argon forms an electropositive discharge. By adding chlorine to an argon discharge, the plasma discharge can be transformed from being electropositive to become electronegative, and the electronegativity can be varied over a wide range. The electronegativity varies from 0 to 107, the electron energy distribution varies from bi-Maxwellian to Druyvsteyn like, and the plasma chemistry changes, as the Cl2 fraction in the admixture varies from 0% to 100%. We will discuss how the electron power absorption mechanisms, the electronegativity, the electron energy distribution function, the reaction rates, and the composition of the discharge vary with the addition of chlorine to the argon discharge. In particular, the influence of the metastable argon atoms and secondary electrons, emitted from the electrode surfaces, on the discharge properties, will be discussed.