Fabrication of Micromachined Ceramic Thin-Film Pressure Sensors for High Overpressure Tolerance

This paper reports on the fabrication process and characteristics of a ceramic thin-film pressure sensor based on Ta-N strain-gauges for harsh environment applications. The Ta-N thin-film strain-gauges are sputter-deposited on a thermally oxidized micromachined Si diaphragms with buried cavities for overpressure tolerance. The proposed device takes advantage of the good mechanical properties of single-crystalline Si as a diaphragm fabricated by SDB and electrochemical etch-stop technology, and in order to extend the temperature range, it has relatively higher resistance, stability and gauge factor of Ta-N thin-films more than other gauges. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.21 ~ 1.097 mV/V.kgf/$\textrm{cm}^2$ in temperature ranges of 25~ $200^{\circ}C$ and a maximum non-linearity is 0.43 %FS.