CMOS-MEMS Z-Axis Magnetic Field Sensor with an Additional Collector

A complementary metal oxide semiconductor (CMOS)-compatible z-axis magnetic field sensor incorporating an additional collector is proposed to enhance magnetic sensing performance. The sensor consists of four identical magnetic sensing elements arranged in a cross-shaped configuration, while shallow trench isolation (STI) and a post-CMOS cavity structure are employed to suppress substrate leakage current and improve electrical isolation. The sensing characteristics were investigated using three-dimensional TCAD simulations to analyze carrier transport and current density distributions under different magnetic fields. The simulation results confirmed that the structure effectively enhances the differential output response and magnetic sensitivity. The device was fabricated using a commercial CMOS process followed by a simple post-CMOS micromachining process. Optical microscope and scanning electron microscope observations verified the successful formation of the sensing structure and the cavity beneath the sensing elements. The sensor was experimentally characterized under magnetic fields ranging from -300 to 300 mT. The measured results exhibited excellent linearity over the entire measurement range. The sensor achieved a measured sensitivity of 120 mV/T. Owing to its high sensitivity, simple fabrication process, and full compatibility with standard CMOS technology, the magnetic field sensor is promising for integrated microsystems, industrial monitoring, and intelligent sensing applications.