pMTJ - Page 6

Researchers from NY University, together with Spin Transfer Technologies have demonstrated magnetic vector switching for current pulses as short as 100 picoseconds. This is among the shortest write times reported by developers of MRAM devices.

The underlying technology is based on a unique orthogonal orientation between the magnetic vectors in two magnetic layers -- a pinned magnetic layer where the magnetic orientation is fixed and a free magnetic layer where the magnetic field is aligned in one of two directions, thereby storing one bit of binary information. In contrast, all other MRAM efforts involve magnetic vectors that are both parallel to the physical layers or both perpendicular to the layers. Termed Orthogonal Spin Transfer MRAM (OST-MRAM), the technology results in a deterministic switching behavior, which enables high speed and very low power device operation. Other approaches result in stochastic switching which involves thermal fluctuations to initiate or hasten the switching process, leading to an incubation delay and requiring higher power for operation.

In addition, the OST-MRAM technology allows the use of magnetic tunnel junctions to achieve large read-out signals, while maintaining the advantages of deterministic switching and low power operation. Another key aspect of the technology is that it does not require sophisticated processes, such as magnetic annealing, for the fabrication of devices. This will significantly lower the cost of future commercial devices based on OST-MRAM technology, compared to other MRAM devices currently in development.

Back in October 2008, we have talked to Vincent Chun from Spin-Transfer-Technologies, and he explained their tech and plans.

A couple of days ago we reported that NEC are working towards perpendicular MRAM using 2T1MTJ... now we have some more info, thanks to TechOn.

NEC and NEC Electronics employed a new method called "spin torque domain wall displacement write method" to reduce write current and realize microfabrication at the same time. In fact, they aim to reduce the current by as much as 90%. They were also able to increase speed to 500Mhz. This technology is not 'new', it was announced in 2007, but now they have a test chip ready.

NEC announced that they have developed the world's first STT-MRAM with current-induced domain wall motion using perpendicular magnetic anisotropy material. Perpendicular magnetic anisotropy enables a cell to carry out the current-induced domain wall motion writing method using spin torque at a low current, which leads to easy scaling down of cell size and creates suitable conditions for next generation system LSI.

The newly developed current-induced domain wall motion writing method, using spin torque and perpendicular magnetization material, is capable of reducing current while writing for a scaled down cell beyond the 55 nanometer process.

Japan's National Institute of Advanced Industrial Science and Technology (AIST) developed a current-perpendicular-to-the-plane (CPP) GMR device.

The CPP GMR device is developed by combining the spin injection magnetization reversal (spin injection) method and perpendicular magnetization technology. AIST aims at developing an MRAM with a capacity of 1 Gbit. The new device was presented at 52nd Annual Conference on Magnetism and Magnetic Materials (MMM), an international conference on magnetic recording now being held in Tampa, Florida.

Read more here (TechOn)

Toshiba Corporation today announced important breakthroughs in key technologies for MRAM. The company has successfully fabricated a MRAM memory cell integrating the new technologies and verified its stable performance.

In making these major advances, Toshiba applied and proved the spin transfer switching and perpendicular magnetic anisotropy (PMA) technologies in a magnetic tunnel junction, which is a key component in the memory cell.

Spin transfer switching uses the properties of electron spin to invert magnetization and writes data at very low power levels. It is widely regarded as a major candidate among next-generation principles for new memory devices. PMA aligns magnetization in the magnetic layer perpendicularly, either upward or downward, rather than horizontally as in in-plane shape anisotropy layers. The technology is being increasingly used to enhance for storage capacity for high-density hard disc drives (HDDs), and Toshiba has successfully applied it to a semiconductor memory device. With PMA data write operation and magnetic switching can be achieved at a low energy level. Toshiba also overcame the hurdle of achieving the required precision in the interface process and significantly cutting write power consumption.

In order to realize a miniature memory cell based on PMA, Toshiba optimized the materials and device structure of the new MRAM. Close observation of performance confirms stable operation (see the diagram for full explanation of structure). Toshiba will further enhance development toward establishing fundamental technologies within the coming years.

Development of the new MRAM technologies was partly supported by grants from Japan’s New Energy and Industrial Technology Development Organization (NEDO).