IBM and Infineon Technologies have signed an agreement to collaborate in the development of Magnetic Random Access Memory (MRAM), which uses magnetic, rather than electronic, charges to store bits of data. MRAM may significantly improve electronic products -- from computers to cell phones to game systems -- by storing more information, accessing it faster and using less battery power than the electronic memory used today. MRAM also retains information when power is turned off, meaning products like personal computers could start up instantly, without waiting for software to 'boot up'.
Infineon's early work with MRAM was conducted in cooperation with the German Ministry of Education and Technology (BMBF), and as long ago as 1974 IBM developed a miniature component called the 'magnetic tunnel junction'. In 1998 the device was adapted as a means of storing information and to built a working MRAM. Using this IBM technology, coupled with Infineon's expertise in creating very high density semiconductor memory, the companies believe actual MRAM products could be commercially available by 2004.IBM and Infineon have more than 10 years experience successfully developing new chip technologies together, including traditional Dynamic RAM (DRAM), logic and embedded-DRAM technologies.
"Infineon and IBM are combining our technological capabilities and resources to help bring MRAM technology to maturity on a fast track," said Wilhelm Beinvogl, Senior Vice President of Technologies and Innovations, Memory Products, Infineon Technologies. He added, "MRAM technology offers equally interesting potential both for embedded logic products and standalone memory chip applications."
Since MRAM will not need constant power to keep the data intact, it could consume much less power than current random access memory technologies. However both companies will not disclose what memory densities will be achieved. Experts say somewhere between SRAM and DRAM, but multi-bit storage is at least five years away.
A combined workforce of approximately 80 IBM and Infineon engineers and scientists will be assisting with the project. Development work will be conducted at IBM's Thomas J. Watson Research Center in Yorktown Heights, NY, IBM's Almaden Research Center in San Jose, Calif., and the IBM Microelectronics Semiconductor Research and Development Centre (SRDC) in East Fishkill, NY. While the structures involved in MRAM are straight forward, the big problem lies in the processing temperatures which has to below the Curie point of the ferromagnetic film used.
The heart of MRAM is a magnetic storage cell based on micron-sized magnetic tunnel junctions (MTJs). IBM has demonstrated magnetic tunnel junctions with high magnetoresistance (>25%) at low field and room temperature.
These devices consist of sandwiches of two ferromagnetic layers separated by thin insulating layers. The tunneling current across the sandwich depends on the magnetic arrangement of the magnetic moments of the magnetic layers and is higher when the magnetic moments are aligned parallel one another, thus giving rise to a magnetic-tunneling effect. In small magnetic fields these devices display room temperature magnetoresistance values which are even larger than those exhibited by giant magnetoresistive (GMR) structures.
In contrast to GMR structures in which the sense current usually flows parallel to the layers of the structure, the current is passed perpendicular to the layers of the MTJ sandwich. Similarly to GMR the resistance of the MTJ sandwich depends on the magnetic arrangement of the magnetic moments of the two ferromagnetic layers.
Both these devices and GMR elements form excellent candidates for advanced non-volatile magnetic memory storage cells to replace conventional capacitive storage cells in DRAM memory chips. Other more sophisticated electronic devices which take advantage of the spin polarisation of electronic current via spin filtering and detection at magnetic/ non-magnetic interfaces include the "spin transistor".
Magnetic tunnel junctions (MTJ) comprise sandwiches of two ferromagnetic (FM) layers separated by a thin insulating layer which acts as a tunnel barrier. In contrast to giant magnetoresistive (GMR) structures in which the sense current usually flows parallel to the layers of the structure, the current is passed perpendicular to the layers of the MTJ sandwich. Similarly to GMR the resistance of the MTJ sandwich depends on the magnetic arrangement of the magnetic moments of the two ferromagnetic layers. Typically, the resistance of the MTJ is lowest when these moments are aligned parallel to one another, and is highest when antiparallel, thereby giving rise to magnetoresistance.