Numerical Simulation of Pulse-Modulation Radio-Frequency Atmospheric-Pressure SiH₄/He/O₂ Discharge

Atmospheric-pressure plasma discharge has been widely used in silicon dioxide film deposition because of its simple equipment and low production cost. Compare to other kinds of discharges, atmospheric pressure pulse discharge attracts more attention because of its stability and high efficiency. In order to better understand the reaction mechanism, a two-dimensional hydrodynamics model is established to study the pulsed radio-frequency atmospheric pressure SiH₄/He/O₂ discharge, focusing on the effects of the duty ratio and modulation frequency on the plasma parameters in pulse discharge. The results show that the duty ratio has a significant impact on the deposition rate and film quality under the same power. The density of each particle in the reaction cavity decreases with the duty ratio, and the density of SiO₂ reaches 10¹⁴ cm^-3 when the duty ratio is 0.4, which is three orders of magnitude higher than that of continuous discharge. Meanwhile, the restriction of electric field on the negative ion is weakened when the duty ratio decreases, and a large number of negative ions flow to the wall of the device, thus a negative ion flow which has a significant impact on the surface treatment of the material is formed. In addition, properly reducing duty ratio can improve the uniformity of thin films. Noticeable, appropriately reducing the modulation frequency can also increase the film deposition rate and improve the film adhesion property without affecting the film uniformity, but its influence is far less than that of duty ratio.