A fluxgate magnetic sensor with micro-solenoids and electroplated permalloy cores

Abstract In this paper, a fluxgate magnetic sensor with silicon micro-technology is presented. The sensor is composed of micro-structured solenoids for the excitation and pick-up coils and permalloy cores formed by electropolating. This device is for a sensing element of the integrated silicon magnetic sensor with high sensitivity and high resolution. Two types of core structures have been fabricated. One is a rod-core sensor based on micromachining technology by using anisotropic etching for the deep groove formation, direct electron-beam lithography for patterning the metal wires on the groove, and selective electroplating for the rod-shaped permalloy core formation in the groove. The other is a thin-film core sensor made by using a similar but simpler process without the groove formation. Relatively high sensitivity and low-offset characteristics have been achieved compared with those of the conventional silicon magnetic sensors.