Technical / Research - Page 20

Someone uploaded an MRAM presentation online. It explains how MRAM works, about GMR, competing technologies, advantages, applications and more.

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.

The final day of the Flash Memory Summit started with a panel on new memory technologies.

Crocus Technologies presented their TAS MRAM design which is targeted at SRAM and flash applications. Their product compared to SRAM at a 25% smaller cell, adding Non-Volatile capability, and a zero standby current. The product compared to NAND flash by having a smaller cell and only 1X area overhead for controlling circuitry. It is currently being built on a 130nm node and can be scaled. It is targeted at Cache memory, data logging, medical instrumentation, casino gaming and industrial control applications. They are targeting several business models - selling the standard product ICs, licensing IP a process technology licensing service and providing a foundry service.

QuantumWise A/S is announcing a new release of its software package for atomic-scale simulations of nanoscale electronic and spintronic devices, Atomistix ToolKit (ATK). This code is able to compute electronic structure and transport properties (e.g. I-V characteristics) of nanoscale structures such as nanotubes, graphene, molecular electronics devices, magnetic tunnel junctions and other magnetic system, interface structures, nanowires, etc.

Based on semi-empirical methods, the newly released package extends the company's modeling platform, which already comprises a density-functional theory (DFT) method, to allow faster simulations of larger structures (>1,000 atoms). The new model also offers a better description of semiconducting materials.

Read more at Spintronics-Info

There's an interesting article at Tech-On, by NEC, on their MRAM-based magnetic flip flip (MFF). NEC say that using such flip-flops can make low power  'standby' mode for appliances (TVs, computers, portable devices...).

Today, for example, LCD TVs have two kinds of standby - "fast standby" which consumes as much as 15W, and 'slow standby' that may consume as low as 0.1W, but may take a few seconds to show a picture when powered back on. The MFF might make it possible to design a stand-by mode that is both fast to power on, and uses minimal power.

We're happy to announce a new addition to the Metalgrass site network: Graphene-Info. Graphene is a sheet, one-atom-thick of carbon atom, in a honeycomb crystal lattice. If you use many layers of graphene, stacked one on top of the other, you’ll get Graphite. Graphene has many uses - Spintronics, sensors, ICs (for example a transparent backplane for OLEDs), ultra-capacitors and more.

We hope you'll enjoy the new site...

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.

The French Montpellier Laboratory has developed a new FPGA architecture based on TAS-MRAM technology.

The use of MRAMs helps to overcome the drawbacks of classical SRAM based FPGAs without significant speed penalty. Besides its advantage that lies in power saving during the standby mode, it also benefits to the configuration time reduction since there is no need to load the configuration data from an external non-volatile memory as is usual in SRAM based FPGAs. Furthermore, during the FPGA circuit operation, the magnetic tunneling junctions can be written which allows a dynamic configuration and further increases the flexibility and performances of FPGA circuits based on the MRAM.

Jean-Pierre Braun, the CEO of Crocus technologies, is visiting Israel these days, and I had the good chance of meeting him. Crocus' technology is based on work done by the French Spintec research center. In fact they get an exclusive access to Spintec MRAM related research and patents for the next 15 years.

Crocus' technology

Crocus' basic technology is based on Field-Induced MRAM (Toggle MRAM), which is in some ways similar to Everspin's technology (or 1st generation MRAM). Historically, Field-Induced MRAM is very hard to scale, and has stability and retention problems. Crocus aims to solve all this using a thermally activated magnetic latch. They call their technology Thermally Assisted Switching or TAS. Basically this means that the latch helps the cell retain the memory value very well. It can also scale quite well. This also (theoretically) will allow them to pack more than 1 bit per cell... some day.

Jean-Pierre says that many companies are doing 'Thermal MRAM' - which only means heating the material for easier handling. But Crocus technology is very different - because of the use of this magnetic latch, not just heat by itself.

Crocus plans

Crocus already has a 'small' (few KBits) working sample of their memory, and towards the end of 2009 they will hopefully get a real product out. I can't say much yet, but this product will have a higher-density than Everspin's products (currently 4Mbit), smaller size and will also be considerably cheaper. This is great news, and hopefully they'll be able to pull it off. Even though the largest MRAM market is for embedded memory, the first Crocus product will be stand-alone.

Crocus financials

Obviously these are hard times - especially for start ups and companies that are still losing money. Crocus has already raised around US$30M, but they aim to break-even in 2010 or 2011. They will still require another round of investment, but hopefully a small one.

Future plans

Crocus are also working on STT-RAM. Jean-Pierre thinks that the best way forward is Perpendicular STT-RAM, which is currently lead by Toshiba. Crocus' MRAM road map looks like this -

• 130-90ns : Field induced TAS MRAM
• 65-45ns : STT-MRAM
•  

But volume production of STT-RAM is still way off, probably "at least 4-5 years" away according to Jean-Pierre.

Will MRAM ever be the 'Universal Memory'?

In the happy days of 2004, MRAM was hyped as the universal memory - being able to replace your SRAM, DRAM, FLASH and H/D - all in one chip. This is great - but not realistic - at least Jean-Pierre does not believe it. It will require some serious technological breakthrough to compete in particular with NAND Flash, and he just can't see it happen anytime soon. Better to focus on 'niche' memory markets that will take full advantage of the specifics of MRAM - infinite endurance and fast write & read cycles, reliability, small die size and low memory requirements. I'm also quite tired of the old MRAM buzz and hype, and hopefully Crocus and other companies are more sober today and this might actually lead to commercial products. Good luck!

Researchers working at the National Institute of Standards and Technology (NIST) have demonstrated for the first time the existence of a key magnetic—as opposed to electronic—property of specially built semiconductor devices. This discovery raises hopes for even smaller and faster gadgets that could result from magnetic data storage in a semiconductor material, which could then quickly process the data through built-in logic circuits controlled by electric fields.

In a new paper, researchers from NIST, Korea University and the University of Notre Dame have confirmed theorists’ hopes that thin magnetic layers of semiconductor material could exhibit a prized property known as antiferromagnetic coupling—in which one layer spontaneously aligns its magnetic pole in the opposite direction as the next magnetic layer. The discovery of antiferromagnetic coupling in metals was the basis of the 2007 Nobel Prize in Physics, but it is only recently that it has become conceivable for semiconductor materials. Semiconductors with magnetic properties would not only be able to process data, but also store it.