Radiation-Hardened Non-Volatile RAM

Magnetoresistive Random Access Memory (MRAM) is a candidate for nonvolatile memory applications in DoD military, space systems, MILSATCOM, and commercial space systems. 2D memory organizations used to date have placed stringent requirements on uniformityand "disturb" sensitivity of the cells resulting in poor manufacturing yields. Several innovations in memory architecture and cell structure in this proposed program will enhance manufacturability. A memory element consists of two magnetic filmsseparated by a thin ruthenium layer, with one of the film layers forming a tunnel junction with a pinned synthetic antiferromagnet for non-destructive read-out (NDRO). Selection of a cell for writing is accomplished through a select transistor, with asingle write current passing through only one magnetic film sandwich in an array. The memory cell can be configured from a single element for high speed, or from two elements for higher density. Low write currents of 2.5 mA have been achieved with 3 nsswitching. Niche memory products and reconfigurable elements are also potential applications. Its scalability could also allow densities of 16 megabits per square centimeter using 0.15 micron lithography. NVE's backend process will complete the SDTmaterial fabrication with the front end processing being provided by a radiation hard foundry.