Implantable hybrid chrome silicide temperature sensor for power MEMS devices

Abstract

In this Letter, an implantable hybrid temperature sensor for use in a micro-scale space in power MEMS devices is proposed. The developed sensor use chrome silicide (CrSi2), which has a very high electromotive force, and nickel as a base metal. Since a thermocouple is an appropriate device to measure temperature at a specific spot, the correlations between the junction sizes and electromotive forces should be verified to reduce the junction size of the thermocouple. Furthermore, it is necessary to verify the performance of the thermocouple implanted in a microdevice by patterning a resistance temperature detector (RTD) on the side of the cold junctions to evaluate the reference temperature of the nickel. The Seebeck coefficients of the CrSi2 thin film thermocouples occur at approximately 70 µV/°C, and the values have been shown to be 1.8 times higher than those of commercial thermocouples. The value of the slope, αNi, which is the temperature coefficient of resistance (TCR) of the nickel RTD is 0.0063/°C at 20°C, whereas the reference value of the TCR of nickel, αNi-ref is 0.0067/°C at 20°C. The third-order polynomial compensation is 99.989% of the regression square value. Based on the verification, a prototype of the hybrid temperature sensor is implanted in a micro methanol–hydrogen peroxide auto-thermal reforming module by stacking six different layers that consist of temperature sensors for the base and different channel figures for the reforming reaction.