MRAM: A solution in search of problems

Having succeeded in building a memory chip that stores data quickly, and then doesn't forget, Freescale Semiconductor now faces a new challenge: what to do with it.

The company must have been looking for answers to that question when it showed off its new magnetic RAM (MRAM) chips at the Freescale Technology Forum, an event for customers and partners, in Paris this week.

MRAM has attracted interest because data can be written to it quickly, like SRAM (static RAM), yet it doesn't lose its contents if power is removed, a quality it shares with flash memory. Unlike flash memory, which can start to fail after as few as 100,000 cycles, data can be written to it repeatedly. MRAM can also operate at high temperatures, is radiation-resistant, consumes little power and is compact, making it potentially useful for all types of applications.

And there's the problem for Freescale: which applications to target?

Freescale's first MRAM chips have a capacity of 4Mb. For now, customers are looking at them as a drop-in replacement for battery-backed SRAM -- without the battery. Compared to the cost of an SRAM chip and a battery, "We are already cheaper, well under 50 percent," said Andrew Birnie, an engineering manager at Freescale demonstrating the product.

But to address the market for solid-state replacements for computer hard disks with capacities of tens of gigabytes, the company needs to make chips with much higher capacity, yet make the chips smaller and cheaper for the hundreds of embedded applications that only require a few bytes of nonvolatile storage.

On top of that, there are the applications that no one has yet thought of: "MRAM will be a replacement for other kinds of memory. But MRAM also brings new properties. We are looking forward to the new designs that will be made after MRAM's introduction," said Andreas Wild, Freescale's director of advanced technology and design solutions.

For example, it could become possible to build notebook computers or PDAs (personal digital assistants) that retain all their memory when the power is off, making it quicker to resume work when they are turned on again. "Putting MRAM in instead of volatile memory is a big evolution," said Wild.

Forty customers have bought samples of the 4Mb chips, which Freescale sells for $25 each in sample quantities of less than 1,000. Two of them are now buying production quantities, the company said.

Pricing for production quantities "is negotiated case by case," said Wild. He compared the price of the chips to that of DRAM (dynamic RAM), the memory used in computers. "In 1974, 1Mb of DRAM cost $75,000. Today, it's a small fraction of a cent. There's no reason why MRAM should not make the same evolution, if not faster," he said.

Freescale made the 4Mb chips using its 180-nanometer process technology, and said it has produced 16Mb parts in its labs using a 90-nm process. As Freescale reduces the size of the features on the chips, it increases their density and capacity.

"We have shown we can do it down to 65 nm and beyond," said Wild.