Magnetic tunnel junction-based MRAM and related processing issues

Magnetic tunnel junction (MTJ) research and development aimed at developing fast, nonvolatile MRAM memory continues to grow at a rapid pace. The subject of the first part of this paper is memory applications of MTJs, and includes an introduction to them, details of the stack layers, prospects for achieving higher tunneling magnetoresistance (TMR), data writing methods, and demonstrator chips. Several important aspects of fabricating MTJs, including needed future processing enhancements, are discussed in the second part: stack deposition, MTJ patterning (including etching and free layer conversion methods), wet cleaning, and thermal stability.