Patterned magnetoresistive random access memory (MRAM) stacks are formed by performing a main etch through a plurality of MRAM layers disposed on a substrate, where the main etch includes using ion beam etching (IBE). After the main etch, gapfill dielectric material is deposited in spaces between the patterned MRAM stacks, and the gapfill dielectric material is selectively etched or otherwise formed to an etch depth that is above a depth of an underlayer. After the gapfill dielectric material is formed, at least some of the gapfill dielectric material and any electrically conductive materials deposited on sidewalls of the patterned MRAM stacks are removed by performing an IBE trim etch.