Microstructure processing and micromagnetic simulations of magnetic tunnel junction based low power magnetic memories

Abstract

Magnetoresistive memory (MRAM) is one of the forerunners of the nanotechnology enabled memories lined to replace the traditional memories like Flash, DRAM and SRAM. MRAMs are based on the phenomenon of spin dependent tunneling in magnetic tunnel junctions (MTJs). It stores data in the magnetization of a magnetic layer as opposed to electrical charge in conventional RAMs. Yet the read-out of MRAM is electrical. It is claimed to offer something close to the speed of SRAM, with a density approaching that of single-transistor DRAM and the ability to store information when power is removed, like flash memory or EEPROM. This paper works out the microstructure processing steps in the fabrication of an MTJ based MRAM cell in two distinct versions. The technicalities of the two MTJ based MRAM cell configurations have been discussed in this paper. The I-V characteristics and TMR ratios of the widely investigated Fe/MgO/Fe magnetic tunnel junction have also been evaluated using first principle LSDA band-structure calculations. Micro magnetic simulations of the MTJ demonstrate the magnetic switching in the two ferromagnetic layers. The resulting hysteresis loop has been presented at the end of the paper.