Long considered a potential next-generation memory, magnetoresistive RAM was in the spotlight at last week's VLSI symposium.
Fujitsu Laboratories Ltd. and the team of NEC Corp. and Toshiba Corp. presented new approaches to MRAM circuitry and cell structure, respectively. The companies said they were establishing essential technologies for MRAMs, which are nonvolatile, blessed with unlimited read/write cycles and expected to enter practical widespread use around 2008.
NEC and Toshiba formed a joint R&D MRAM project in 2002. At last week's symposium, the team proposed a toggle-mode MRAM cell. Its magnetic tunnel junction with a multilayered structure, the team said, solves the toggle-switching issue.
Separately, Fujitsu is developing embedded MRAM to differentiate its system-on-chip products. Its Fujitsu Laboratories unit has proposed a one-transistor/two-magnetic tunnel junction (1T/2MTJ) structure MRAM cell with a direct voltage-sensing scheme, which it said has the advantages of DRAMs.
In the proposed 1T/2MTJ cell, two MTJs were connected in series. Fujitsu fabricated the test device with each MTJ measuring 0.2 x 0.4 micron and confirmed the cell operation.
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