MTJ Nanopillar Fabrication

INL is capable of fabricating nanopillars out of MTJ stacks with diameters down to 40 nm. We succeeded with the typical stack with a free layer on top of the stack as well as inverted stacks. The latter has the benefit of a free layer that is in direct contact with the bottom contact material. These two approaches were applied to fabricate devices used for research on MTJ-based spin transfer torque nano-oscillators (STNOs) and Spin Hall nano-oscillators (SHNOs) described in the Spin dynamics and Spin Transfer Torque Nano-Oscillators page.

Two pillar image – “Two MTJ nanopillars in an intermediate fabrication step defined by e-beam lithography. Both have a diameter far below 100 nm, and show TMR signals of up to 120%.

Spintronicsp2 – “Flow diagram of the planarization process for achieving high quality electrical contacts to MTJ nanopillars”

X section “Cross section of an MTJ nanopillar. This image was obtained by cutting the sample with a focused ion beam into a thin lamella and imaging the electron transmission through the sample.