Comparison of the Intrinsic Characteristics of LTCC and Silicon Pressure Sensors by Means of 1/f Noise Measurements

A pressure sensor with high resolution is of key importance for precise measurements in the low-pressure range. The intrinsic resolution of piezoresistive ceramic pressure sensors (CPSs) mainly depends on their func¬tional sensitivity and the electronic noise in the thick-film resistors. Both the sensitivity and the noise level depend on the material and the structural properties, and the dimen¬sions of the sensing structure. In general, the sensitivity can be increased and the noise can be reduced by using additional electronics for the signal processing, but this makes the sensor bigger, more complex and more expen¬sive. In this study we discuss the technological limits for downscaling the sensor’s pressure range without any processing of the sensor’s signal. The intrinsic resolution of the piezoresistive pressure sensors designed for the pressure range 0 to ±100 mbar and realized in LTCC (Low Temperature Cofired Ceramic) technology was evaluated and compared to the resolution of a commercial 100-mbar silicon pressure sensor. Considering their different typical sensitivities, the resolutions of about 0.02 mbar and 0.08 mbar were obtained for the CPS and the silicon sen¬sors, respectively. The low-frequency noise measurements showed that the noise characteristics of both sensors were not influenced by the pressure loads.