NI MUSHROOM ARRAY TO ENHANCE OUT-OF-PLANE MAGNETIC FIELD SENSITIVITY OF ANISOTROPIC MAGNETORESISTANCE SENSOR

This study demonstrates anisotropic magneto-resistive (AMR) sensor with a novel Ni mushroom-shape structure as magnetic flux guide to enhance the out-of-plane magnetic field detection (Fig.1). AMR sensors could detect external magnetic fields through the change of magnetization and resistance. Since typically made of thin films, AMR sensors are mainly sensitive to the in-plane magnetic field. This study extends the concept in [1] to demonstrate a mushroom-shape magnetic flux guide array to significantly enhance the sensitivity of out-of-plane magnetic field detection. Merits of the design are: (1) Mushroom-cap could receive more out-of-plane magnetic flux, (2) Mushroom-stem (pillar structure) could concentrate and convert the out-of-plane magnetic field into in-plane one, (3) The design is easily achieved by electroplating. Measurements demonstrate the sensitivity of presented mushroom-shape design is 3-fold higher than the reference one with pillar design in [1].