Circuit model for flat cut-off probes with coplanar capacitance

Abstract

Fine tuning of plasma parameters is essential in semiconductor plasma processing because of the demand for smaller, low-power, and high-integration nanoelectronic devices in the semiconductor industry. Existing method monitors process abnormality based on the real-time measurement of some in situ processing sensors, such as optical emission spectroscopy and voltage–current sensor, owing to the absence of a direct plasma measurement sensor applicable to in situ plasma processing monitoring. In this paper, we propose a microwave flat cutoff probe and its circuit modeling, in which the plasma and sheath are considered as coplanar capacitance. The circuit model was verified through both electromagnetic simulation and experiment, and the results were found to be in good agreement. Through this circuit model with the coplanar capacitance, the effect on the distance between the microwave radiating antenna and detecting antennawas analyzed in detail.