Enhancing Stability of ZrO x N y Thin-Film Cryogenic Temperature Sensors Through Thermal Shock Treatment

Transition metal oxynitride thin-film temperature sensors show great promise for cryogenic thermometry. However, enhancing their stability to meet high-precision measurement requirements remains challenging. In this work, we established three thermal shock methods with different intensities, controlled by the minimum exposure temperature and the cryogenic dwell time, to systematically investigate the effect of shock intensity on the cryogenic stability of packaged zirconium oxynitride (ZrOxNy) thin-film temperature sensors. A total of eleven packaged microsensors were developed and divided into three groups for the three thermal shock methods. The stability of these sensors was quantitatively evaluated using the standard deviation of temperature fluctuations (Tstdev) from 17.6 K to 24.6 K, both before and after the thermal shock treatment. The results show that the effect of thermal shock on sensor stability strongly depends on the shock intensity. The shock method with the weakest intensity yielded the largest number of data points exhibiting enhanced stability, with 85% of the measurements demonstrating improvement, and achieved an excellent post-shock stability of 0.43-1.80 mK. The stability of sensors treated with method C was additionally tested at the triple point of water (TPW, 273.16 K), and all sensors achieved a great stability of 2.3-5.6 mK. This study points out that weak-intensity thermal shock treatment can effectively enhance the stability of ZrOxNythin-film temperature sensors at cryogenics while also ensuring high stability at elevated temperatures near room temperature, providing valuable insights for the development of high-precision cryogenic temperature sensors.