Free layer sidewall oxidation and spacer assisted magnetic tunnel junction (MTJ) etching for high performance magnetoresistive random access memory (MRAM) devices

摘要

Disclosed is a magnetic tunnel junction (MTJ) that avoids electrical shorts and has improved data retention. The top capping layer has a first sidewall that is coplanar with the interface between the outer oxidized portion and the central ferromagnetic portion of the free layer FL having an FL width FLW. Dielectric spacers are formed on the first sidewall and the oxidized outer FL portion. The pinned layer PL has a width PLW substantially greater than that of FLW, and the second sidewall thereon is formed by self-aligned etching using a dielectric spacer and a capping layer as an etching mask. The sidewall layer may be formed on the second sidewall and dielectric spacer, but the sidewall layer does not degrade MTJ properties as it does not contact the FL and PL center portions responsible for device performance. PL width FLW ensures greater capacity for data retention, especially for FLW 60 nm.