Development of a calibration system for wafer-type temperature sensor

Wafer-type temperature sensors are widely used during semiconductor fabrication as integrated monitoring sensors for the real-time monitoring of wafer surface temperature, which affects the quality and yield of semiconductor devices. In recent years, various wafer-type temperature sensors have been developed according to the process type and temperature range for monitoring the temperature distribution. However, there is little research on the calibration system to ensure the accuracy and reliability of the developed wafer-type temperature sensor. In this study, we designed a system for the calibration of wafer-type temperature sensors. With this system, the traceability of the sensor can be guaranteed by calibrating the sensing characteristics, such as area uniformity, temperature stability, and accuracy. The conventional temperature calibration bath is calibrated by placing a wafer-type temperature sensor in a liquid-controlled system to have uniform temperature. This method is difficult to apply to the field because the wafer-type temperature sensor can be contaminated by liquids and can adversely affect semiconductor processes. For this reason, we used a heating chamber similar to chemical vapor deposition equipment for a calibration system. We evaluated the properties of the calibration system including the rising time (which means the time taken to reach the target temperature) and temperature stability according to the heat capacity. Moreover, we developed a measurement method that allows for the evaluation of the temperature of the wafer-type temperature sensor within 15 min at 150 °C. The calibration system and measurement method developed in this study are expected to improve the efficiency of semiconductor fabrication processes.