Experimental investigation of edge-to-center density ratios in argon and neon capacitively coupled plasmas

Capacitively Coupled Plasmas (CCPs) are widely used in semiconductor processes such as etching and deposition. Plasma density and its uniformity directly affect semiconductor and display process results and thus, it is essential for comparing and validating theoretical models of plasma behavior against experimental results. However, systematic studies measuring plasma density uniformity in CCPs under varying external parameters such as electrode gap distances and gas pressures remain rare. In this study, the effects of gas species, electrode gap distances, and gas pressures on plasma density uniformity were investigated. Plasma density uniformity was measured in 13.56 MHz capacitively coupled neon and argon discharges while varying gas pressure and electrode spacing from 50 to 90 mm, and the results were compared with the theoretical model of edge-to-center density ratios.