Enhancement of data retention and write current scaling for sub-20nm STT-MRAM by utilizing dual interfaces for perpendicular magnetic anisotropy

Abstract

We investigate the sub-20nm level scalability of STT-MRAM cells possessing perpendicular magnetization induced from the interface of free layer (FL) and MgO tunnel barrier. We demonstrate that the MTJs utilizing dual interfaces of FL and MgO exhibit enhanced scalability with high thermal stability and low switching current, compared with the MTJs with a single interface. As thermal stability factor (Δ) varies as a function of MTJ dimension, MTJs with dual interfaces show Δ over 60 at 20nm node, while MTJs of single interface show Δ around 33. MTJs with dual interface also exhibit lower switching current per thermal stability (Ic/Δ), ∼1/2 level of single interface MTJs.