Batch Fabrication of 50 μm-Thick Anisotropic Nd–Fe–B Micro-Magnets

We used standard micro-electro-mechanical systems (MEMS) fabrication techniques (lithography, etching, and sputtering) to the batch fabrication of out-of-plane textured
$50~\mu \text{m}$
-thick Nd–Fe–B micro-magnets on Si substrates of 100 mm diameter. Pre-patterning of the Si substrate serves to structure the in-plane dimensions of the micro-magnets and affords stress relief in the magnetic layer. Two protocols were applied to grow the films: a one-step process, in which the film is directly crystallized and a two-step process, where the film is amorphous in the as-deposited state and crystallized during post-deposition annealing. Both processing routes result in micro-magnets with magnetic properties (texture and coercivity) comparable to sintered Nd–Fe–B bulk magnets. We report on how substrate patterning and film thickness affect the very distinctive microstructures of our films. Finally, the stray magnetic field patterns produced above these topographically patterned films were characterized by scanning Hall probe microscopy (SHPM).