Conductivity Meter with Carbon Electrodes and Application for Densitometers Technologies for a Practical Densitometer

By: Riichiro SUZUKI

30 January 2018

Figure 1 Current, voltage signal and current divided by voltage signal of the 4-electrode carbon sensor

Author Information: Research & Development Division, HORIBA Advanced Techno, Co., Ltd.

Abstruct: HORIBA developed 2-pole electrical conductivity sensors with chemical-resistant carbon electrodes in 2002. These sensors are installed in semiconductor wet processes and are put into practical use as densitometers. In addition, HORIBA developed a new circuit for 4-pole conductivity measurement, which was an innovation that improved the precision with any 4-pole sensors. Concentration of single-component such as hydrofluoric acid or TMAH are measured based on precise electrical conductivity and temperature measurements. Temperature compensation calculations for the conductivity of the individual component are necessary to convert the conductivity into the concentration. Etching and developing solutions, etc. need to be controlled at a constant level, and the demand for various types of densitometers that use electrical conductivity systems is increasing.

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