Investigation of Sensitivity of Two-Dimensional Integrated Magnetic Sensor Fabricated in Sub-micron CMOS Process

Abstract

To realize a high-resolution two-dimensional integrated magnetic sensor, the process rule was changed from 0.35 to 0.18 μm. The fabricated magnetic sensor was an n-type Hall sensor that uses an inversion layer under the gate oxide of the MOSFET. The decided sensor area size was 6.6 × 6.6μm². The Hall sensors were arrayed in 32 × 32 pixels. The average sensitivity of the fabricated magnetic sensors was 34.6mV/(mA·T), and this value was the same as that of fabricated magnetic sensors in the 0.35μm standard CMOS process. No degradation of sensitivity was introduced to a magnetic sensor fabricated in 0.18 μm process rule. From the result of two-dimensional integrated magnetic sensor, two-dimensional magnetic flux distribution was successfully measured from the 1-mm diameter Nd-Fe-B rare-earth permanent magnet. By changing the position of the probe that measures Hall voltage, the sensitivity of magnetic sensors was increased by 17%.