Magnetic Tunnel Junctions: Laser Annealing Versus Oven Annealing

Abstract

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.