Diode-MTJ Crossbar Memory Cell Using Voltage-Induced Unipolar Switching for High-Density MRAM

This letter presents a diode-magnetic tunnel junction (MTJ) magnetic random access memory cell in a 65-nm complimentary metal-oxide-semiconductor compatible process. A voltage-controlled magnetic anisotropy switching mechanism, in addition to STT, allows for a unipolar set/reset write scheme, where voltage pulses of the same polarity, but different amplitudes, are used to switch the MTJs. A small crossbar array is constructed from 65-nm MTJs fabricated on a silicon wafer, with switching voltages ${\sim}{\rm 1}~{\rm V}$ and thermal stability greater than 10 years, with discrete germanium diodes as access devices to allow for read/write operations. The crossbar architecture can be extended to multiple layers to create a 3-D stackable, nonvolatile memory with a sub- $1{\rm F}^{2}$ effective cell size.