Spin transfer torque magnetic random-access memory: Towards sub-10 nm devices

摘要

We present a new approach to increase the downsize scalability of perpendicular STT-MRAM. It is achieved by increasing the thickness of the free layer in order to induce a perpendicular shape anisotropy (PSA). Therefore, in PSA-STT-MRAM, the perpendicular anisotropy mainly arises from the shape of the storage layer and no longer from an interfacial anisotropy with the tunnel barrier. This approach allows to easily tune the stability of the memory point just by changing the aspect ratio (thickness / diameter) of the storage layer. The paper is mainly focused on presenting the theory of PSA-MRAM and briefly discusses practical realizations of such devices.