Development of a High-Linearity Voltage and Current Probe with a Floating Toroidal Coil: Principle, Demonstration, Design Optimization, and Evaluation

Abstract

As the conventional voltage and current (VI) probes widely used in plasma diagnostics have separate voltage and current sensors, crosstalk between the sensors leads to degradation of measurement linearity, which is related to practical accuracy. Here, we propose a VI probe with a floating toroidal coil that plays both roles of a voltage and current sensor and is thus free from crosstalk. The operation principle and optimization conditions of the VI probe are demonstrated and established via three-dimensional electromagnetic wave simulation. Based on the optimization results, the proposed VI probe is fabricated and calibrated for the root-mean-square (RMS) voltage and current with a high-voltage probe and a vector network analyzer. Then, it is evaluated through a comparison with a commercial VI probe, with the results demonstrating that the fabricated VI probe achieved a slightly higher linearity than the commercial probe: R2 of 0.9967 and 0.9938 for RMS voltage and current, respectively. The proposed VI probe is believed to be applicable to plasma diagnostics as well as process monitoring with higher accuracy.

Determination of Plasma Potential Using an Emissive Probe with Floating Potential Method

“…In particular, plasma has played a significant role in plasma processes such as plasma etching [ 1 , 2 , 3 ], ashing [ 4 ], deposition [ 5 ], and plasma decomposition [ 6 , 7 ]. To analyze the process chemistry and mechanism, several instruments have been developed and utilized, such as voltage–current probes [ 8 , 9 ], optical emission spectroscopy [ 10 , 11 ], and quadrupole mass spectrometers [ 12 , 13 ]. Recently, understanding plasma behavior in plasma processing has attracted significant attention, since plasma produces chemical species and thus dominates process chemistry [ 14 ].…”