US Patent 9564577 MRAM device and fabrication method

A magnetoresistive random access memory (MRAM) device comprises a bottom electrode over a tapered bottom via, a tapered magnetic tunnel junction (MTJ) over the bottom electrode, a top electrode over the MTJ, and a top via over the top electrode. The top via, top electrode, MTJ, bottom electrode, and bottom via (and electrical interfaces therebetween) are substantially aligned along a common vertical axis. The bottom via has a taper angle of about 120° to about 150°. The MTJ has a taper angle of about 70° to about 85°. The MTJ is isolated and protected with dual sidewall spacers.