A novel monolithically integrated pressure, accelerometer and temperature composite sensor

The paper presents a novel single-side micromachined composite sensor, with a piezoresistive pressure sensor, a thermal-convection accelerometer and a thermometer monolithically integrated in one 2.5times2.5 mm² chip, for low-cost production and applications such as tire-pressure monitoring systems (TPMS). The accelerometer is based on heat convection, including a micro heater and two pairs of micro machined thermopile sensors for temperature difference sensing. The convective accelerometer sensitivities at the heater power of 10.90mW, 19.56 mW and 30.12 mW are 37.92 muv/g, 85.04 muv/g and 134.08 muv/g, respectively. The pressure sensor sensitivity range 450 KPa is about 0.038 mV/V/KPa .The nonlinearity is less than plusmn1.06% FS (full scale) and even in over load case of 700 KPa nonlinearity is under plusmn 1.62% FS. In this boron ion implantation case, the temperature coefficient of polysilicon resistor is -578 ppm/degC.