A 64Mb MRAM with clamped-reference and adequate-reference schemes

Abstract

A 64 Mb spin-transfer-torque MRAM in 65 nm CMOS is developed. A 47 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> die uses a 0.3584 ¿m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> cell with a perpendicular-TMR device. To achieve read-disturb immunity for the reference cell, a clamped-reference scheme is adopted. An adequate-reference scheme is implemented to suppress read-margin degradation due to the resistance variation of reference cells.