Sony researchers built a 4-kbit memory cell in a 180-nanometer CMOS process with four-level metal, according to the paper the company present in Washington at IEDM. The MTJ was built of optimized CoFeB material. Sony has also used CoFeB for conventional-MRAM development.
The researchers verified data write speeds of 2 nanoseconds for the experimental device. Circuit simulations indicate the same speed for reads. The current required to switch the free layer's orientation was 200 microamps, or 1/30 the power required for a conventional MRAM.
"Simulation shows that the density of the memory can be increased to the level of DRAM or beyond, depending on the improvement of the material properties, especially to lower the power needed for writes," said Hiroshi Kano, senior manager of New Memory Technology Group #2 at Sony's Solid State Memories Research Laboratory. "With further evolution of the material, we believe densities higher than DRAM will be possible." Kano said the group aims to build "a working prototype for evaluation within two years."

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