Computer memory set for five-fold boost

Posted by Kate Taylor

Hard drive capacity could increase by five times, thanks to a new process currently being tested by supplier HGST.

With capacity starting to hit its theoretical limits, chemists and engineers at the University of Texas at Austin have developed a new technique, which relies on self-organizing substances known as block copolymers.

"In the last few decades, there's been a steady, exponential increase in the amount of information that can be stored on memory devices, but things have now reached a point where we're running up against physical limits," says Professor C Grant Willson.

With current production methods, zeroes and ones are written as magnetic dots on a continuous metal surface; and the closer together the dots are, the more information can be stored in the same area. But we're now at the limits of this technique, as moving the dots any closer together would mean they'd be affected by the magnetic fields of their neighboring dots and become unstable.

"The industry is now at about a terabit of information per square inch," says Willson.

"If we moved the dots much closer together with the current method, they would begin to flip spontaneously now and then, and the archival properties of hard disk drives would be lost. Then you're in a world of trouble. Can you imagine if one day your bank account info just changed spontaneously?"

There is a loophole, however. If the dots are isolated from one another, with no magnetic material between them, they can be pushed closer together without destabilization - and this is where block copolymers come in.

Under the right conditions, they'll self-assemble into highly regular patterns of dots or lines. If the surface onto which they're coated already has some guideposts etched into it, the dots or lines will form into precisely the patterns needed for a hard disk drive.

And the University of Texas researchers say they've now synthesized block copolymers that self-assemble into the smallest dots in the world. In some cases they form into the right, tight patterns in less than a minute - another world record.

Most significantly, the team has designed a special top coat that goes over the block copolymers while they are self-assembling, and which allows the polymers to achieve the right orientation relative to the plane of the surface simply by heating.

"The patterns of super small dots can now self-assemble in vertical or perpendicular patterns at smaller dimensions than ever before," says Thomas Albrecht, manager of patterned media technology at HGST.

"That makes them easier to etch into the surface of a master plate for nanoimprinting, which is exactly what we need to make patterned media for higher capacity disk drives."