Smart-Cut™ piezoresistive strain sensors for high temperature applications

This paper presents research results on novel high performance silicon piezoresistive strain sensors based on Smart-Cut^TM SOI wafer, with 340 nm silicon overlayer and 1 μm buried oxide. Experimental results show that the 3 kΩ Wheatstone bridged piezoresistive strain sensor has a sensitivity of 0.14 mV/με at 5V bias and a linearity of 0.9% full scale, in the range of ±1000 /με. When tested at elevated temperatures, the gauge factor of the sensor changed from 27.6 at 24 °C to 25.4 at 130 °C, equivalent to a temperature coefficient of the gauge factor of -0.02 /°C, which is an order of magnitude smaller than the -0.55 /°C value of previous sensors developed with 2×10¹⁸ cm^-3 doping. This piezoresistive sensor is suitable for applications that need high temperature stability.