High Temperature Silicon Pressure Sensors

This chapter gives a complete development process of a high- temperature silicon pressure sensor. Firstly, the piezoresistive effect was described for sensor chip used in high temperature application. Based on the SiO₂ isolation layer, the leakage current generating through p-n junction can be eliminated, which ensured the proper function of piezoresistors in high-temperature working condition. Secondly, the mechanics models for circular, rectangular, and island-structured diaphragms had been presented. Also a theoretical guide for designing and optimizing a sensor chip was presented in section “Mechanics Model of the Pressure Sensor Chip.” Thirdly, based on the mechanics models, section “Structure Designing, Lithography Mask Designing and Fabrication of the Sensor Chip” presented a designing principle of sensor chip to find a balance point between the sensitivity and dynamic response frequency, in order to take full use of elastic strain energy induced by structure deformation. Then, lithography masks for corresponding pattern structures were presented. Followed by the lithography mask designing, the fabrication process of sensor chip was presented. Fourthly, the packaging technology for sensor chip was presented in section “Packaging Structure for the Pressure Sensor Chip.” The packaging structure not only enabled the sensor chip to work properly in a harsh environment but also ensured the packaged sensor had a good performance in dynamic and sensitivity performance. Finally, in section “Conclusions,” the experimental calibration for the sensitivity, dynamic performance, and cross-sensitivity of developed high-temperature silicon pressure sensor were conducted to obtain a comprehensive performance evaluation.