A Magnetic Sensor with Silicon on Insulator Structure for High Temperature Applications

Silicon magnetic Hall sensor for high temperature applications has been developed with Silicon-On-Insulator(SOI) structure. The Hall cell of magnetic sensor is dielectrically isolated by silicon dioxide from silicon substrate in order to reduce leakage current between the Hall cell and silicon substrate at high temperature. The theoretical sensitivity of the magnetic sensor was calculated and compared to the experimental result. There is a tradeoff between sensitivity and available temperature range. The magnetic sensor has temperature offset drifts which are caused by size mismatching, unbalance of doping condition and thermal stress between sensor and package. These offsets are compensated by design optimization and signal conditioning circuit. As a result, silicon magnetic Hall sensor with SOI structure could be operated steadily over high temperature of 200∘.