Freescale serves up alternative to flash


Comment When Freescale recently announced a four megabit memory chip, my immediate reaction was to laugh.

Magneto-resistive RAM - a technology which several aspirant companies have abandoned - has been announced in commercial form by Freescale, which is prepared to sell you a four megabit memory chip.

It's been described as "an expensive solution to a problem nobody has" by experts on Flash memory, its main technology rival. But after some laughter, I decided to see what was going on - and came to the conclusion that there may be a market in RFID.

Scepticism has greeted the announcement from the few sources who actually investigated it. Once they realised that the memory chip in question is a mere four megabits in capacity, only 512 Kb - which compares dismally with the $20 1Gb Flash chips available to consumer markets - most comment has been to pour scorn on the investors who sold Sandisk short.

Sandisk, supplier of Flash RAM, is really not under threat just yet. It would take 2,000 MRAM chips to match the capacity of that Flash chip, and quite probably, just one of the MRAM chips would cost well over $25. So, say sceptics, why is Freescale bothering?

The main advantage of MRAM over Flash is that you can write more data, and much quicker, for the expenditure of far less power. So applications are, like those for Flash, ones where power may fail but data must not be lost, but where the time available before power fails is minimal.

Point-of-sale tags (like the London Underground "Oyster" ticket system) would appear to be the obvious example. The chip inside the Oyster card has no battery. It only functions for as long as power is transmitted by the card reader - and in that time, it has to "wake up" its radio, verify its access rights, and then write any changed data (like, how much cash is left) back to the RFID chip memory.

The Freescale announcement focuses on the "fast" feature of MRAM. It is, says Andreas Wild, European R&D director, "as fast as SRAM".

The capacity of the chip isn't as much of an issue as it sounds, says Wild. "It will scale. This technology is very conservative. It's standard CMOS, completely standard - that's the point of it - and then you add four new layers of processing to build the tunnelling electron engines."

Conservative means fabricated on virtually antique semiconductor processes - specifically, 0.18 microns (180 nanometres). It will, he assured us, scale right down to 65 nanometres.

That's a relief, because rival announcements from NEC and Toshiba spoke back in February of a 16 megabit chip. The reason this is only a quarter the capacity is "because it is nothing more than a lab curiosity until someone has a commercial-grade product with commercial-grade maturity and reliability", said Wild.

He's not giving too much away about what makes Freescale the first (it claims) to put this on the market, or why it took it so long. It isn't the only semiconductor on the trail. According to EE Times, Crocus Technology SA of Grenoble in France just raised $17m in capital (that was as recently as June) based on "key patents from Spintec, a CEA/CNRS research laboratory" (CEA is the French atomic energy commission, and CNRS is the national research council).

The Freescale announcement punctures the promise by Crocus's backers that it would be first to market. It may still be first to market with a different technology, but Freescale's announcement ensures that anybody doing prototype development will be ringing the Freescale phone number right now.

What, exactly, is tunnelling? What is magneto-resistive RAM? The first thought is that it's something dreamed up by Nobel prize-winner Professor Brian D Josephson - who used tunnelling in superconductor chips - and indeed, the technology is similar in that both use quantum effects. Professor Josephson said: "I can tell you the total of my knowledge of magnetic tunnelling..." and offered me a blank paragraph.

I guess he had real work to do. Of course, he could be more informative on the subject if he chose to be. Tunnelling is one of those phenomena of the Quantum universe, in which reality gives way to absurdity, and the measurements confirm the absurdity as the correct representation of reality.

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