A novel MTJ for STT-MRAM with a dummy free layer and dual tunnel junctions

Abstract

A novel magnetic tunnel junction (MTJ) for embedded memory applications such as spin transfer torque magneto-resistive random access memory (STT-MRAM) is proposed. It consists of a dummy free layer and dual tunnel junctions using perpendicular magnetic anisotropy at the CoFeB/MgO interface. A fabricated MTJ with 53 nm diameter exhibited a high thermal stability factor Δ = 52 and a small switching current I c0 = 57 μA, resulting in an Δ/I c0 ratio of 0.91, which is more than twice that of the reference MTJ. This MTJ simultaneously provides an excellent Δ/I c0 ratio, low-voltage switching (0.34 V at 100 ns), and good manufacturability.