One or the other
The heat-assisted camp wants to change the grains. Unlike cobalt-platinum grains, iron-platinum grains will not flip at room temperature, Kryder said. To record or erase data, a laser integrated into the drive would heat a particular bit. The data would get recorded or erased, and the bit would quickly cool.
"We'd have to change the (recording) head to add heat, but it's not that big of a deal," Kryder said. Adding a laser wouldn't increase costs much, he noted. More important, the bits could be applied to the platter surfaces through a film, which is how bits are applied today.
Material changes, however, are rarely easy; for example, the switch from aluminium to copper in semiconductors confounded semiconductor makers. For the heat-applied technology, engineers would have to perfect ways to pinpoint the heat from the laser.
"It requires small optical spots. It requires very sharp thermal gradients. It requires new materials," John Best, chief technologist at Hitachi, said, pointing out hurdles in the process.
"You could argue (about) which one's easier to solve, but it looked to us that the practical problems with patterned media meant that we could probably do it first more easily," Best added.
By contrast, the patterned media group wants to keep the current grains. It proposes, instead, reducing the number of grains in each bit from 100 to one, and then isolating the bits from each other to reduce cross-talk and the risk of data corruption, Best said. Initially, the grains in the first patterned media drives would be larger than the grains in today's drives, but the overall size of the bit would be smaller.
"With this, you can get a factor of 100 in increase in density. Of course, you have to scale everything else, so it will take time. But the problem of the temperature of the room reversing magnetization goes away," Best said.
So how do you create a pattern? A master pattern could be drawn with e-beam lithography. That pattern could then be transferred to a mold, which would then be used to stamp out the pattern on hard drive platters though imprint lithography.
Adopting e-beam and imprint lithography into mass manufacturing won't be easy. In fact, patterned media hard drives could easily become the first widescale application for both, Best said.
E-beam, which creates a pattern by firing electrons, was invented years ago to replace traditional lithography in chipmaking, but it never did. Imprint lithography, which makes an impression like that on a signet ring, was only developed in the last few years.
However, lithography of any kind is expensive, particularly when compared to the film-coating processes used today. "We don't have to personalize each bit by patterning it lithographically," Kryder noted, referring to the heat-assisted technique.
Both camps have published papers and lab results, but no one is close to having manufacturing samples. Hitachi, for instance, has created prototype components, but not complete patterned media drives.
Ultimately, the decision could turn on which technology looks easier to bring to mass manufacturing. This year, around 450 million to 460 million drives will leave factories, according to data from Disk/Trend.
"You've got to figure out how to do this, not just in a lab demonstration, but by producing them in the hundreds of millions," said Porter of Disk/Trend. "The good news is that you have people working in both of these camps, and maybe others. There's nano-this and nano-that."
No matter which goes first, the end is not near. Hard drive makers are even examining new materials that could take the grain size below 8 nanometers, although the current candidates are corrosive.
"We can see 50 to 100 terabits being possible," Kryder said. "We are three orders of magnitude from any truly fundamental limits."
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