Wafer-level magnetic field biased single domain soft magnetic layers by integrated NdFeB micromagnets

Abstract

Single magnetic domain soft magnetic films are the basis for many magnetic field sensing applications. The absence of magnetic domain walls reduces magnetic noise, which is relevant for magnetic sensing layers and supporting structures such as magnetic shields and flux concentrators. Here, the use of wafer-level integrated NdFeB micromagnets for on-chip field biasing of soft magnetic submicrometer thick layers for magnetic domain control is presented. Effective bias field strengths are modeled and experimentally evaluated using a magnetooptical indicator film technique. Single magnetic domain behavior in the soft magnetic layers is demonstrated. Effects of the granular micromagnet structure on the magnetic field homogeneity are discussed. The demonstrated integrated magnetic biasing scheme is applicable to various magnetic layer-based field sensing devices benefiting from single magnetic domain behavior.