The Characteristics of Ar/O₂ Plasma with Dual Frequency Capacitive Coupling at Atmospheric Pressure

In this paper, the characteristics of Ar/O₂ discharge driven by dual frequency at atmospheric pressure are studied by using a two-dimensional fluid model. We mainly focus on the influences of different matching methods, such as high and low-frequency source voltage and low-frequency source frequency, on the plasma parameters. The dual frequency control mechanism of atmospheric pressure Ar/O₂ discharge is analyzed by electron heating mode, electron density, neutral particle density, positive ion energy, and total positive ion flux. The results show that when the low-frequency source voltage increases, the electron heating mode changes from α mode to DA/α mode, and the plasma density, the total flux of positive ions, as well as the ion energy increase with the low-frequency voltage; this means that decoupling occurs. Different from the low-frequency source voltage, the high-frequency source voltage and the low-frequency source frequency have little effect on the electron heating mode. Furthermore, it is shown that the voltage of the high-frequency source can greatly influence the plasma density and the total positive ion flux, while the ion energy which damages the material in the etching industry changes little. The frequency of the low-frequency source has a great influence on the ion total flux and the energy of the positive ions, which easily affects the reaction in the industry but has little effect on the plasma density. Therefore, the independent control of plasma density and ion energy is realized.