Angular distribution measurement of high-energy ions and neutrals impinging on an RF electrode in a dual-frequency capacitively-coupled Ar plasma

Abstract The angular distributions of high-energy neutrals and ions impinging on a radio frequency (RF)-biased electrode in a 40.7/2 MHz dual-frequency capacitively coupled argon plasma were investigated with maximum ion energies up to ∼2.5 keV. The angular distributions were measured as two-dimensional beam images using a micro-channel plate. Further, the incident ion energy distribution on the RF electrode was measured in the same apparatus using a Faraday cup. The angular distribution widths for the ions and neutrals were measured as a function of the maximum ion energy, and the result was explained by the ratio of the ion temperature to the ion energy accelerated by the RF sheath. Additionally, the angular distribution width was measured while changing the pressure. An increase in the angular distribution width with increasing pressure was observed for the ions and neutrals, particularly at relatively high peak-to-peak voltages.