A high precision two-axis GMR angular sensor manufactured by post-annealing

This work demonstrates a high-precision in-plane two-axis GMR angle sensor is prepared by post-annealing. The pinning direction of the GMR strips is modulated by annealing two times to achieve orthogonal sensitive directions of the two sensors. The sensitivity of a full-bridge sensor is 6.59 mV/V/mT, with the sensing direction along the Y-axis and the sensitivity of a half-bridge GMR sensor is 1.68 mV/V/mT with the sensing direction along the X-axis. A simulation of the two-axis sensor output with the field has been performed, which proves the correctness of the P2 direction measured by the angle test. The detectivity of the full-bridge sensor is 22 nT/(Hz)^0.5 at 10 Hz and it is 88 nT/(Hz)^0.5 at 10 Hz for half-bridge sensor. The orthogonality error of the two-axis sensor for the geomagnetic angle detection is lower than 0.04. The sensor in this study demonstrates higher detectivity than some commercial GMR sensors, such as YAS532 produced by Yamaha and HSCDTD008A produced by ALPS. This work proposes an efficient and simple method for producing two-axis GMR angle sensors, which can be a promising solution for mass production.