Development of a Microwave‐Driven Large‐Area and Uniform Plasma Device With Dual‐Frequency

ABSTRACT In this paper, a dual‐frequency (915 MHz and 2450 MHz) microwave low‐pressure plasma source based on a rectangular cavity and feeding waveguides equipped with slot‐array antennas was designed. A large‐area, uniform plasma was obtained. Experiments showed that plasma discharge was much more uniform under dual‐frequency compared to single‐frequency. Plasma volume uniformity of argon plasma under dual‐frequency could achieve up to 80.2% when incident power was 800 W and pressure was 100 Pa, while its line uniformity achieved 99.6%. Dependence of incident power, power ratio of dual‐frequency, and various working gases with plasma uniformity were investigated. Adjusting sliding shorts, energy coupling efficiency of the cavity was effectively enhanced. Overall, the dual‐frequency plasma device offered a novel approach to improve plasma uniformity.