The performance of a novel type of NdFeB micromagnets fabricated by agglomeration
of magnetic powder by atomic layer deposition is investigated. The ALD-bonded
micromagnets can withstand standard BEOL (back-end of line) processing and heat
treatments at temperatures of up to 400 °C in air and vacuum without
any significant impact on the demagnetization curves. By optimized packing
density a remanence of 660 mT is realized for the micromagnets. The coercivity
µ0Hc = 890 mT remains constant for
all samples and corresponds to the powder value.
A comparison of the demagnetizing behavior of micromagnets with theory of solid
body magnets prove that the influence of particle shape and hollow spaces on
demagnetizing field is low. Hence, a similar impact of shape on stray field and
forces as for solid body magnets can be assumed when integrating NdFeB
ALD-bonded micromagnets in applications.