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Temperature-stable NdFeB micromagnets with high-energy density compatible with CMOS back end of line technology

: Reimer, T.; Lofink, F.; Lisec, T.; Thede, C.; Chemnitz, S.; Wagner, B.


MRS advances 1 (2016), No.3, pp.209-213
ISSN: 2059-8521
Journal Article
Fraunhofer ISIT ()

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.