Analysis of Plasma and Gas Characteristics According to the Recovery Process Using a New Alternative Gas

Abstract

Perfluorocarbon (PFC) gas, which is predominantly used in the etching and chamber cleaning processes of semiconductor manufacturing, is very stable and remains on Earth for long periods. Moreover, it has a high global warming potential because it blocks the emission of radiant heat from the Earth and contributes to global warming. To mitigate these effects, the waste PFC gas can be recovered and reused, which also limits the unnecessary waste of resources. In this study, the liquid fluorocarbon C6F6, which has a high C/F ratio and exists as a liquid at room temperature, was selected as an alternative to PFC gas, and adsorption and recovery were performed through an adsorption module during the plasma process. To characterize the recovered gas, residual gas analysis was performed on the gases recovered during etching. In addition, optical emission spectroscopy and printed circuit board probes were used to characterize the plasma. Finally, the feasi-bility of the gas recovery process was evaluated by comparing the thicknesses of the CF polymers produced in Si and SiO2 using an ellipsometer. The results revealed that the C6F6 had similar characteristics before and after recovery, confirming that this gas can be reused and is suitable for use in semiconductor manufacturing as a green alternative.