High Density 3D Cross-Point STT-MRAM

Abstract

Stackable 3D cross-point Spin transfer torque magnetic RAM (STT-MRAM) is one of the best candidates to replace DRAM and serve as storage class memory (SCM). For very high density and low cost STT-MRAM, stackable 3D cross-point STT-MRAM architecture requires selectors integrated in series with a magnetic tunneling junction (MTJ) memory element. We have developed a two-terminal bi-directional threshold switching selector and integrated the selector with a perpendicular MTJ to form a 1S1R device. The write operations between "AP" and "P" resistance state have been demonstrated for 1S1R STT-MRAM devices. A simulation model has been developed to simulate conductive filament growth and dissolution process, and dynamic switching of coupled pMTJ and selector devices. The simulation results show the importance of optimal matching of pMTJ magnetic properties with selector resistive properties to achieve high performance.