Monolithic integration of micro magnetic pillar array with anisotropic magneto-resistive (AMR) structure for out-of-plane magnetic field detection

A novel integrate micro magnetic pillar array with anisotropic magneto-resistive (AMR) structure for out-of-plane magnetic field detection has been proposed and demonstrated. The merits of this study are: (1) The magnetic pillar converts magnetic field from out-of-plane to in-plane and provide magnetic gain (G) where G≈1/N (N:demagnetization factor) [1]; (2) The micro magnetic pillar array can be batch fabricated and defined at appropriate locations, and further monolithically integrated with AMR sensor; and (3) The magnetic conversion efficiency can be easily further enhanced by increasing the density of magnetic pillar array. The AMR sensor with different magnetic pillar density has been implemented and measurements indicate that the AMR sensor with larger density of magnetic pillar array has better sensitivity and resolution for detecting out-of-plane magnetic field.