Discharge characteristics of dual-frequency magnetized capacitively coupled Ar/CH<sub>4</sub> plasma

<sec>In recent years, dual-frequency capacitively coupled plasma discharge technology has demonstrated remarkable advantages in the fields of material processing. In this paper, a one-dimensional PIC/MCC (particle-in-cell/Monte Carlocollision) simulation method is used to discuss the influence of low frequency on the discharge characteristics of capacitively coupled argon/methane plasma driven by dual-frequency (20/100 MHz) dipole, with an external magnetic field added. The simulation results show that when the high frequency is an integer multiple of the low frequency, the superposition of high and low frequencies is significant, and the sheath oscillation is more obvious. As low frequency increases, the electron density, charge density, high-energy electron density and electron heating rate all increase. Specifically, as low frequency increase, the electron density increases to 14%, the electron temperature near the sheath decreases by about 12%, the electron energy probability distribution (EEPF) shows a double Maxwellian distribution, the populations of both low-energy electrons and high-energy electrons increase, and at the same time, the densities of various ions and the angle and energy distributions of <inline-formula><tex-math id="Z-20250717143213">\begin{document}${\text{CH}}_{4}^{+} $\end{document}</tex-math></inline-formula> and <inline-formula><tex-math id="Z-20250717143223">\begin{document}${\text{CH}}_{3}^{+} $\end{document}</tex-math></inline-formula> particles reaching the electrode plates are influenced.</sec><sec>In the Ar/CH<sub>4</sub> plasma driven by dual-frequency, with external magnetic field added, the controlling of ion energy can effectively optimize the structure and performance of carbon-containing films. By regulating discharge parameters to control the incident angle of the ions on the substrate, carbon-containing atoms can be deposited in a specific direction, thereby achieving the directional growth of carbon-containing films. This is significant for the preparation of graphene films, carbon nanotube arrays, etc. Meanwhile, the regulation of the incident angle of ions is helpful to improve the binding force between the carbon film and the substrate. It is found in this study that when the incident angle of the ions is around 0.32, the average energy of the ions reaches its peak. This peak is most significant at a low frequency of 15 MHz. The results in this paper provide a theoretical reference for preparing carbon films.</sec>