Reliable Sub-Nanosecond Switching of a Perpendicular SOT-MRAM Cell without External Magnetic Field

Abstract

The steady increase in performance and speed of modern integrated circuits is continuously supported by constant miniaturization of complementary metal-oxide semiconductor (CMOS) devices. However, a rapid growth of the dynamic and stand-by power due to transistor leakages becomes a pressing issue. A promising way to stop this trend is to introduce non-volatility. The development of an electrically addressable non-volatile memory combining high speed and high endurance is essential to achieve these goals. It is particularly promising to employ non-volatility in the main computer memory as a replacement of conventional volatile CMOS-based DRAM. To further reduce the energy consumption, it is essential to replace caches (SRAM) in modern hierarchical multi-level processor memory structures with a non-volatile memory technology. The spin-orbit torque magnetic random access memory (SOT-MRAM) combines non-volatility, high speed, high endurance, and is thus suitable for applications in caches. However, its development is still impeded by the necessity of a static in-plane magnetic field. We propose a magnetic field-free perpendicular SOT-MRAM, based on a cross-bar architecture and the use of two consecutive orthogonal sub-nanosecond current pulses. In this way small layout footprint and high integration density are guaranteed.

Keywords

• sram
• non-volatile magnetoresistive memory
• perpendicular magnetic anisotropy
• sub-0.5ns switching
• spin-orbit torque