The warm-up and offset stability of a low-pressure piezoresistive ceramic pressure sensor

Ceramic pressure sensors were investigated as candidates for applications in the low-pressure range. The use of low-temperature co-fired ceramic (LTCC) materials and technology combines many advantageous features for pressure sensors: the relative ease of producing three-dimensional structures, the availability of relatively thin sheets, and the relatively low Young's moduli together with a still reasonable mechanical strength. This makes it possible to achieve a higher resolution in comparison to the most commonly used Al 2O 3-based ceramic pressure sensors and an appropriate miniaturisation. However, special precautions are needed when designing a sensor for applications at very low pressures, starting from the selection of the materials and the processing parameters to the realization of the package. In this paper we present a few details of a case study of an LTCC-based piezoresistive sensor designed for the measurement of air or liquid pressures lower than 3 kPa. A series of test sensors was manufactured and characterised. Among the experimental tests the numerical analyses were included to show the trends and help reveal the impact of some of the design parameters. The essential sensor characteristics, i.e., the sensitivity, the warm-up drift and the offset voltage stability are discussed. The numerical and experimental results showed that the characteristics are favourable for applications in the pressure range below 10 kPa.