A SOI-MEMS atmosphere pressure sensor and its low stress packaging

An atmosphere pressure sensor is developed using SOI (silicon on insulator) wafer based on MEMS technology. In this sensor, the device layer of SOI wafer is etched as the stress detection resistor. And the depth of pressure cavity is controlled by wet etching time. The whole chip is finished by anodic bonding with SOI wafer and pyrex 7740 glass wafer. Also, a kind of plastic packaging for pressure sensor is studied and optimized to reduce the stress in the packaged atmosphere pressure sensor so as to improve the stability and sensitivity of the sensor. In the packaging, silicon rubber, instead of epoxy, is chose as adhesive material to bond chip onto the lead frame and reduce the stress caused by thermal mismatch when temperature changes. And, silicone gel is used to fill in the shell to protect the chip and wire. It is shown by the experimental results that the stability and sensitivity of pressure sensor is improved.