Patterning of sub-50 nm perpendicular CoFeB/MgO-based magnetic tunnel junctions

Abstract

Perpendicular magnetic tunnel junctions (p-MTJs) were patterned into nanopillars using electron-beam lithography to study their scaling and switching behaviour. Magnetoresistance measurements of annealed and unannealed p-MTJ films using scanning probe microscopy showed good agreement with Monte Carlo modeling. p-MTJ pillars demonstrated clear parallel magnetic states, both 'up' or both 'down' following AC-demagnetization. Significant variability in the resistance of p-MTJ pillars was observed and attributed to edge features generated during patterning or local inhomogeneity in the MgO layer.

Relaxation dynamics of magnetization transitions in synthetic antiferromagnet with perpendicular anisotropy

“…The growth conditions are described in details in [14,15]. A perpendicular magnetic anisotropy (PMA) of CoFeB layers arises at the CoFeB/MgO interface due to hybridization between 3d shells of transition metals (Fe, Co) and 2p shell of oxygen in MgO [16,17]. Short (3 min) annealing at 250 °C was carried out to enhance perpendicular anisotropy by crystallization of CoFeB layer.…”

“…Short (3 min) annealing at 250 °C was carried out to enhance perpendicular anisotropy by crystallization of CoFeB layer. The boron diffusion into Ta interlayer, occurring during this process, increases antiferromagnetic exchange interaction between the two CoFeB layers, reducing the roughness of Ta/CoFeB interface [16][17][18]. The plate-shaped samples 0.4 × 3.5 × 4.5 mm 3 in size were used for static and dynamic magnetic measurements.…”

Field-free spin–orbit-torque switching of perpendicular magnetization aided by uniaxial shape anisotropy

“…High-speed and energy-efficient switching mechanism of perpendicular magnetization is strongly desired in spintronics applications, as it could benefit the write performance of magnetic random access memories and spin logic devices [1][2][3]. Currently the most widely used mechanism is spin transfer torque (STT) [4,5], which, however, is suffering from several intrinsic drawbacks.…”

Magnetic reversal and thermal stability of CoFeB perpendicular magnetic tunnel junction arrays patterned by block copolymer lithography

“…The growth [4][5][6][7] , the physical origin of interfacial anisotropy 8 , and voltage-controlled magnetic properties [9][10][11] of p-MTJs have been extensively characterized. Scaling and switching behavior have been investigated in p-MTJ devices with diameters ranging from 11 nm to 500 nm [12][13][14][15][16] , and the effective anisotropy has been estimated by analyzing telegraph noise while measuring TMR using conductive atomic force microscopy 17 .…”