MgO-based tunnel junction material for high-speed toggle magnetic random access memory
2006 (English)In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 42, no 8, 1935-1939 p.Article in journal (Refereed) Published
We report the first demonstration of a magnetoresistive random access memory (MRAM) circuit incorporating MgO-based magnetic tunnel junction (MTJ) material for higher performance. We compare our results to those of AlOx-based devices, and we discuss the MTJ process optimization and material changes that made the demonstration possible. We present data on key MTJ material attributes for different oxidation processes and free-layer alloys, including resistance distributions, bias dependence, free-layer magnetic properties, interlayer coupling, breakdown voltage, and thermal endurance. A tunneling magnetoresistance (TMR) greater than 230% was achieved with CoFeB free layers and greater than 85% with NiFe free layers. Although the TMR with NiFe is at the low end of our MgO comparison, even this MTJ material enables faster access times, since its TMR is almost double that of a similar structure with an AlOx barrier. Bit-to-bit resistance distributions are somewhat wider for MgO barriers, with sigma about 1.5% compared to about 0.9% for AlOx. The read access time of our 4 Mb toggle MRAM circuit was reduced from 21 ns with AlOx to a circuit-limited 17 ns with MgO.
Place, publisher, year, edition, pages
2006. Vol. 42, no 8, 1935-1939 p.
MgO, magnetic random access memory (MRAM), magnetic tunnel junction (MTJ), toggle switching, tunneling magnetoresistance (TMR), room-temperature, magnetoresistance
IdentifiersURN: urn:nbn:se:kth:diva-15874ISI: 000239368100001OAI: oai:DiVA.org:kth-15874DiVA: diva2:333916
QC 201005252010-08-052010-08-05Bibliographically approved