Self-assembling polymer arrays the secret of next-generation hard driv

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Madison (WI) – Researchers from the University of Wisconsin-Madison and Hitachi Global Storage Technologies discovered a new patterning technology that could lead to a new generation of hard drives that are not only easier to manufacture but also feature a storage density that cannot be achieved with traditional media and processes today.

Future hard drive and disk technologies are among the most fascinating topics in IT. Research in this area does not only affect a cheap mass storage technology we all depend on, but hard drive technology always has been at the center of a discussion of natural limits for their storage capacity and the industry now looks back to a 35 year history of moving predicted natural barriers a few years out into the future.

My personal favorite in this category is OAW, or Optical Assisted Winchester, a technology that was developed by Quinta, a company that was acquired by Seagate in 1998. Ten years ago, Seagate believed that the natural barrier of storage density in traditional (Winchester) hard drives would be somewhere in the 100 Gb per square inch neighborhood, while the laser-based OAW approach would be able to hit about 250 Gb per square inch. Using a laser beam, OAW was described to heat the surface material before recording data at a specific location, which decreases the need for a stronger magnetic field, as it is the case with growing densities in today's drives.

Of course, today we know that perpendicular magnetic recording recently bought the industry some time and pushed the natural barrier once again out into the future. 250 Gb per square inch disks are in mainstream production today, while some drives are already exceeding 330 Gb per square inch.

OAW is not off the table, though, and was moved into a new project called Heat Assisted Magnetic Recording (HAMR) in 2004. Back then, Seagate said that HAMR has the potential to take the platter to densities of 50 terabits per square inch, which translates into storage space for more than 3.5 million high resolution photos, 2800 audio CDs or 1600 hours of movies on a platter with the size of a half dollar (30.61 mm).

Heat-assisted technology, however, is only one way to think about future hard drives. As it is the case with many technologies that get smaller and smaller today, many believe that production technologies eventually will reach a point at which they cannot scale anymore and new production technologies will be required – technologies that do not scale down, but use a process to build up structures from scratch instead.

Such an idea is now being pitched by researchers from Researchers from the University of Wisconsin-Madison and Hitachi Global Storage Technologies (HGST). The new production method builds on existing approaches by combining the lithography techniques traditionally used to pattern microelectronics with novel self-assembling materials called block copolymers, the researchers said When added to a lithographically patterned surface, the copolymers' long molecular chains spontaneously assemble into the designated arrangements. According to a paper published in the August 15 issue of Science, the block copolymers pattern the resulting array down to the molecular level, offering a precision unattainable by traditional lithography-based methods alone. They even correcting irregularities in the underlying chemical pattern.

The result: Nanoscale control theoretically allows the researchers to create higher-resolution arrays capable of holding more information than those produced today.

"There's information encoded in the molecules that results in getting certain size and spacing of features with certain desirable properties," Paul Nealey, director of the University of Wisconsin-Madison Nanoscale Science and Engineering Center (NSEC), said. "Thermodynamic driving forces make the structures more uniform in size and higher density than you can obtain with the traditional materials."

Nealey said that block copolymers only need one-fourth as much patterning information as traditional materials to form the desired molecular architecture, which would mean that the manufacturing process could be very efficient. "If you only have to pattern every fourth spot, you can write those patterns at a fraction of the time and expense," he said.

Before you get too excited about the potential of this technology, no, there were no potential storage numbers mentioned and there is not even an indication when this technology could be available. In fact, it is further out than OAW was back in 1998. But the polymer project apparently was not just playtime for the scientists, but in fact has the objective to create a technology that is industrially viable. "This research addresses one of the most significant challenges to delivering patterned media - the mass production of patterned disks in high volume, at a reasonable cost," says Richard New, director of research at HGST. "The large potential gains in density offered by patterned media make it one of the most promising new technologies on the horizon for future hard disk drives."

Somehow we feel that this technology is in its very early stages and its future is uncertain. As long as hard drive manufacturers can increase the storage density of today’s hard drives using traditional methods there is no reason for anyone to take a risk with a new technology. And even if we will not see this technology in actual products, the scaling progress made these days is simply stunning.

http://www.tgdaily.com/content/view/38895/113/