Temperature Controllable QCM Sensor with Accurate Temperature Measurement for Outgas and Contamination Assessment

The Quartz Crystal Microbalance (QCM) sensor is a key device used in evaluating outgas characteristics such as deposition, desorption, and temperature-dependent properties. We propose a new cryogenic QCM (CQCM) sensor with good usability and temperature measurement accuracy using the twin-electrode technique. The sensor was named "Twin-CQCM". Its operating temperature ranges from –190 to +125°C. The temperature-dependent drift of the frequency was less than ±10 ppm over the whole temperature range by using the temperature compensation technique. A temperature sensor placed directly on the quartz crystal improves temperature measurement accuracy. To confirm the accuracy, an additional platinum temperature sensor was installed at the center of the crystal. The original sensor temperature output was compared to that of the additional sensor, with the difference between both temperature sensors being +0.4 to +2.6°C in the temperature range from –130 to +100°C. Furthermore, the user can easily replace the sensor’s crystal because of the simple structure. This good usability enables not only simplified sensor replacement but also new applications, such as atomic oxygen (AO) measurement. This paper describes the proposed twin-electrode technique and discusses the evaluation results.