SPIN-TRANSFER TORQUE MAGNETIC RANDOM ACCESS MEMORY WITH PERPENDICULAR MAGNETIC ANISOTROPY MULTILAYERS

摘要

A spin-torque transfer memory random access memory (STTMRAM) element includes a composite fixed layer formed on top of a substrate and a tunnel layer formed upon the fixed layer and a composite free layer formed upon the tunnel barrier layer, the magnetization direction of each of the composite free layer and fixed layer being substantially perpendicular to the plane of the substrate. The composite layers are made of multiple repeats of a bi-layer unit which consists of a non-magnetic insulating layer and magnetic layer with thicknesses adjusted in a range that makes the magnetization have a preferred direction perpendicular to film plane.