Structure and method to fabricate high performance MTJ devices for spin-transfer torque (STT)-RAM

A Magnetic Tunneling Junction (MTJ) nanopillar structure formed on a bottom electrode in a Spin Torque Transfer Random Access Memory (STT-RAM) device, comprising:

• (a) a seed layer formed on the bottom electrode;
• (b) an anti-ferromagnetic (AFM) layer formed on the seed layer;
• (c) a synthetic anti-ferromagnetic (SyAF) pinned layer with a second antiparallel (AP2)/coupling/first antiparallel (AP1) configuration formed on the AFM layer wherein the AP2 layer contacts the AFM layer;
• (d) a MgO tunnel barrier layer contacting the AP1 layer;
• (e) a composite free layer having a lower magnetic layer, an upper magnetic layer, and a middle nanocurrent channel (NCC) layer with magnetic channels connecting the upper and lower magnetic layers wherein NCC is a nanocurrent channel layer comprised of R(Si) grains having a minimum diameter that are formed in an oxide or nitride insulator matrix and R is Fe, Ni, Co, a metal M or a combination thereof, said lower magnetic layer contacting the MgO layer has a greater thickness than that of the upper magnetic layer and the NCC layer has a thickness which is less than or equal to the R(Si) grain minimum diameter;
• and
• (f) a capping layer disposed on the composite free layer.