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Magnetic tunnel junctions: Laser annealing versus oven annealing

: Sharma, A.; Hoffmann, M.A.; Matthes, P.; Koehler, N.; Busse, S.; Mueller, M.; Exner, H.; Schulz, S.E.; Zahn, D.R.T.; Salvan, G.


IEEE transactions on magnetics 55 (2019), Nr.1, Art. 4400104, 4 S.
ISSN: 0018-9464
ISSN: 1941-0069
Fraunhofer ENAS ()

The performance of CoFeB/MgO tunnel junctions is strongly dependent on an annealing step at the end of the fabrication process to first, set a reference magnetization through the exchange bias effect and second, to crystallize the MgO/CoFe layers while boron diffuses out, in order to maximize the magnetoresistance ratio. In this regard, a laser-induced annealing process presents several advantages against traditional oven annealing techniques, providing a scalable approach with no limitations regarding the defined reference magnetization that can be aligned in different directions on a wafer. This paper concentrates on the mechanisms and dependences of laser annealing on the magnetic properties in comparison to the standard vacuum oven annealing, providing a first insight for the applicability of laser annealing for CoFeB-/MgO-based magnetic tunnel junctions with all concomitant needs.