Spin-orbit-torque (SOT) MRAM with doubled layer of SOT metal

A method comprising:

• forming a dielectric base of a first dielectric material and a dielectric pillar of a second dielectric material, wherein the dielectric pillar protrudes from the dielectric base;
• forming a first intermediate structure by depositing a first layer of conductive material onto the dielectric base, sufficiently thick to cover the pillar and the base;
• forming a planarized structure by planarizing the first intermediate structure to reveal the pillar;
• and
• depositing a second layer of spin-orbit-torque metal onto the planarized structure.

A magnetic random access memory (MRAM) apparatus comprising:

• a magnetic tunnel junction (MTJ) stack;
• and
• a spin-orbit-torque (SOT) layer underlying the MTJ stack,
• wherein the SOT layer has an upper step covering an area directly under the MTJ stack and a lower step adjacent to and below the upper step,
• wherein the upper step comprises spin-orbit-torque metal, and
• wherein the SOT layer has a generally uniform thickness.