Bugged about the Future of Magnetic Storage?

Recent advances in information storage using magnetic recording have been a key to producing today’s faster and smaller computers (“The Big, Bad Bit Stuffers of IBM,” TR July/August 1998). But squeezing more and more data onto magnetic materials is getting tougher, threatening to slow progress to a crawl. To tackle the problem, scientists at IBM’s Zurich Research Laboratory have built a micromechanical device, called Millipede, that uses a thousand tiny tips to rapidly “feel” data bits on a nanometer (one-billionth of a meter) scale.

“In a sense,” says IBM researcher Gerd Binnig, “it’s old-fashioned. It works very similarly to a record player that has an arm and a needle.” But, Binnig adds, the micromechanical device could also represent the future of information storage. Because of its potential ability to “read” and “write” data on a nanometer scale, it could store up to 500 billion bits (gigabits) per square inch (the record for magnetic storage is 11 gigabits per square inch). That could lead to hard disks with storage capacity of several trillion bits (terabits). It could also mean small products, such as watches and mobile phones, that have immense storage capacity.

Millipede is a direct descendent of atomic force microscopy (AFM), a research tool invented by Binnig and IBM co-workers in 1986 that uses a tiny needle mounted on a sensitive cantilever to probe and mechanically manipulate nanometer-sized objects, including atoms. A couple of years ago, a group at IBM’s Almaden Research Center in San Jose, Calif., found they could use an AFM tip to punch 100-nanometer-wide divots in a polymer surface; the AFM tip then could read each depression as a data bit.
The potential data density was impressive. But using AFM for reading and writing data was a laboratory curiosity, far too slow for commercial purposes. To speed things up, Binnig and co-worker Peter Vettiger, the leaders of IBM Zurich’s micron and nanomechanics team, replaced the single AFM tip with an array of tips that can “read” the nanometer-scaled depressions in parallel. In the current version, built late this summer, the researchers incorporated 1,024 tips in a 32-by-32 array. In theory, this device can read and write data as fast or faster than magnetic storage.

Binnig says that Millipede is in early development. For one thing, the IBM scientists still must demonstrate that Millipede can reliably read and write data. Then there’s the problem of developing the electronics needed for a practical storage device. “All that’s not so extremely interesting from a scientific point of view, but it has to be done to have a real product,” Binnig says.

And if it is, Millipede’s thousands of tiny feet might just be beating a path into the future of information storage.