A Commercial Compact Integrated Triaxial Fluxgate Sensor Based on 4-D Heterogeneous Multidimensional Integration

This article presents the design and fabrication of a compact integrated microelectromechanical system (MEMS) triaxial fluxgate sensor based on 4-D heterogeneous multidimensional integration for large-scale commercial high precision navigation grade geomagnetic field detection application, utilizing three fluxgate chiplets and two combined substrates. The sensor achieves full three-component magnetic field detection by bonding the chiplets onto the substrates in orthogonal L-configuration. The fluxgate chiplet measures $6\times 3.9\times 0.5$ mm, while the triaxial fluxgate sensor has dimensions of $12\times 11.7\times 7.2$ mm. This results in a 2.9-fold area increase and only a 20% height increase compared to individual chiplets. The sensor exhibits X-, Y-, and Z-axes sensitivities of 889, 887, and 880 V/T, with noise levels of 0.031, 0.085, and 0.071 nT $\surd $ Hz at 1 Hz, respectively, and range of $\pm 100~\mu $ T. In the time drift stability test, three fluxgate chiplets showed noise peak to peak values below 22 nT within one hour, and below 2 nT with 10 s, confirming the time-stability of the sensor. The orthogonality error of the sensor reaches 1°. A neural network-based error correction method significantly improves measurement accuracy, reducing the fluctuation range from 28.4917 to $1.3015~\mu $ T. This advancement in miniaturized fluxgate sensor technology promises broad applications in geomagnetic field detection.