Optimization of Pressure Sensors Fabrication Processes with SOI and Bonding Technology

摘要

An optimized method is designed for pressure sensor fabrication with bonding technology. For piezoresistive pressure sensors,the most critical step is to define a silicon diaphram, which acts as a pressure sensitive layer. To get outstanding performance of the pressure sensor, the difference of the diaphram thickness should be as less as possible, both across the wafer and among wafers. The buried oxidation layer of SOI wafers performances as an etch-stop layer to control the thickness of the diaphram preciously. At the same time, the proposed method provides a stable and repeatable way to get the samll size and stable mechanical structure by bonding process. In addition, the optimized processes also provide an easy and cost-efficient solution for measurement with different scale and sensitivity. Finally, absolute pressure sensor based on the proposed method is fabricated. Pressure test shows a high sensitivity of 39.83mV/V/Mpa, low nonlinearity of 0.17% FS and low temperature drift of 0.005%/℃ FS is realized. Aspersion of the sensors across the wafer and among the wafers is low.