High-Sensitivity Magnetic Field Sensors Manufactured Utilizing CMOS-MEMS Technology

A high-sensitivity two-axis magnetic field sensor (MFS) was successfully developed utilizing CMOS process. The MFS is constructed by two components: an x-axis MFS (x-MFS) and a y-axis MFS (y-MFS). The x-MFS is designed by connecting four x-axis magnetotransistors (x-MTs) in parallel, which enhances the output current of the x-MFS. Similarly, the y-MFS is constructed by connecting four y-axis magnetotransistors (y-MTs) in parallel, leading to an increase in its output current. The x-MTs and y-MTs function based on the Lorentz force, which alters the transistor’s electrical characteristics in response to variations in a magnetic field (MF). To improve performance, a postprocessing is applied to etch the MFS’s silicon substrate and to form isolated cavities around the sensor. This etching technique significantly reduces substrate leakage currents, thereby enhancing the sensor’s sensitivity. Experimental results reveal that the sensitivities of x-MFS and y-MFS achieve 560 and 556 mV/T, respectively. The MFSs have a potential use in precision navigation, electronic products, and industrial sensing applications due to its high sensitivity and compact design.