According to an aspect, there is provided a method of forming a magnetic tunneling junction (MTJ) device, including: forming a layer stack including an MTJ layer structure and a spin-orbit torque (SOT) layer below the MTJ layer structure; forming a first etch mask over the layer stack, the first etch mask including a first mask line extending in a first horizontal direction; patterning the layer stack to form an MTJ line extending in the first horizontal direction, the patterning including etching while the first etch mask masks the layer stack, and stopping etching on or above the SOT-layer; forming sidewall spacers on one or both sides of the MTJ line; while the sidewall spacers mask the SOT-layer, etching the SOT-layer to form a patterned layer stack including the MTJ line and a first patterned SOT-layer; forming a second etch mask over the patterned layer stack, the second etch mask including a second mask line extending in a second horizontal direction across the MTJ line; and patterning the patterned layer stack to form a twice patterned SOT-layer, the twice patterned SOT-layer including an SOT-line extending in the second horizontal direction, and to form an MTJ pillar on the SOT-line, the patterning including etching while the second etch mask masks the patterned layer stack.