NEC and Toshiba have leapt ahead with what they claim is the successor to Flash memory.
The companies have made two key developments in the production of MRAM (magnetorestitive RAM) that will see it supercede the memory currently used in mobile phones, MP3 players and other portable electronic devices.
Flash memory is currently favoured for memory cards because it retains data after a device is switched off. MRAM offers the same by uses magnetic fields to store data, but it can also recall data faster, work longer and potentially be produced at a lower cost than Flash memory.
MRAM could replace flash and DRAM by as early as 2010, its backers say, but only if certain technical problems are solved first.
One issue involves the size of MRAM cells, which tend to be bigger than those of other memory types. Bigger cells result in higher production costs and can also use a lot of power when writing data. The developers must also determine how to control magnetic fields in each memory cell, to stop the fields from interferring with their neighbours and creating errors.
For these and other reasons, the capacity of MRAM chips developed so far has been limited to about 16MB, while flash memory is already available in GB densities.
NEC and Toshiba have developed two technologies that help solve some of the problems, allowing MRAM chips to store much more data and use less electricity - 256MB by early 2006, they claim.
One technology involves a new cell design that has arc-shaped bulges on its sides. The design reduces the amount of current required to write to the cells by about a half compared to current MRAM designs and also reduces errors.
They have also developed an alternative to the two basic MRAM cell designs produced to date. One of the existing designs couples each cell with a transistor, which improves "read times" but increases cell size. The other removes the transistor from each cell but results in read errors and longer read-access times.
NEC and Toshiba have created a design that uses one transistor to control four cells, resulting in smaller cells that have a faster read time of about 250 nanoseconds. It has been used to design a 1MB chip that uses only about half the voltage of Toshiba's current 4GB flash products.
Despite the advances, Toshiba has not set a schedule for commercialising MRAM chips, said spokesman Makoto Yasuda. MRAM could one day be useful for flash or other memory applications, said Kim Soo-Kyoum, a program director for semiconductor research at IDC. However, its small memory capacities and future development work may mean MRAM takes a long time to replace other memory types, he said. "MRAM is just in its infancy. Really, it's future is as yet unknown," he said.
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