A novel nonvolatile memory with spin torque transfer magnetization switching: spin-ram

TLDR

A novel nonvolatile memory utilizing spin torque transfer magnetization switching (STS), abbreviated spin‑RAM, is presented for the first time. The spin‑RAM is programmed by magnetization reversal via spin‑momentum‑torque‑transferred current in magnetic tunnel junctions, using an oval‑shaped 100 × 150 nm MTJ in a 1‑transistor/1‑MTJ (ITU) structure fabricated on a 4‑level metal, 0.18 µm CMOS process. Writing speed as high as 2 ns and a write current as low as 200 µA were demonstrated, showing that spin‑RAM offers high speed, low power, and high scalability for next‑generation universal memory.

Abstract

A novel nonvolatile memory utilizing spin torque transfer magnetization switching (STS), abbreviated spin-RAM hereafter, is presented for the first time. The spin-RAM is programmed by magnetization reversal through an interaction of a spin momentum-torque-transferred current and a magnetic moment of memory layers in magnetic tunnel junctions (MTJs), and therefore an external magnetic field is unnecessary as that for a conventional MRAM. This new programming mode has been accomplished owing to our tailored MTJ, which has an oval shape of 100 times 150 nm. The memory cell is based on a 1-transistor and a 1-MTJ (ITU) structure. The 4kbit spin-RAM was fabricated on a 4 level metal, 0.18 mum CMOS process. In this work, writing speed as high as 2 ns, and a write current as low as 200 muA were successfully demonstrated. It has been proved that spin-RAM possesses outstanding characteristics such as high speed, low power and high scalability for the next generation universal memory