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SSD + BPM Spells Good Business
August 25, 2008
The competition between flash-based solid-state disk drives (SSDs) and bit patterned media HDDs is shaping up to be an intense race, although not a winner-take-all affair.
In mid-August, the patterned media camp got a big boost when Hitachi Global Storage Technologies (HGST) and the University of Wisconsin at Madison reported self-assembly techniques promising to ease the expense of creating templates for the nanoimprint lithography (NIL) steps in bit patterned media (BPM).
At the same time, the SSD side got a lot of ink when Intel executives announced their latest SSD product rollout at the Intel Developer Forum in San Francisco, including 80 GB and 160 GB SSDs based on multi-level-cell flash architectures.
The HDD industry is not about to roll over. Tom Albrecht, manager of patterned media research at Hitachi Global Storage Technologies, said, “We absolutely have cost and technical advantages over SSDs. Magnetic recording does not have the wear-out mechanism that flash does. That is one key advantage we have over SSDs. We also are 10-20× cheaper per-bit, and we intend to maintain that cost advantage.” With just a hint of sarcasm, Albrecht said, “SSD’s advantage is that you can throw it against the wall.”
The benchmark for a disk with today’s continuous grain recording is 250 Gbits/in2. A 3.5 in. platter has roughly 9 in2 of area, which would deliver >250 gigabytes (GB) of capacity per disk. With discrete track media (DTM), in which NIL and etching create rectangular islands of magnetic material with a ~50 nm pitch, Albrecht said the HDD industry can get to a terabit/in2, or slightly less. The next step is to use NIL and self-assembly techniques to create pillars of magnetic material in bit patterned media.
“With bit patterned media we can improve the aerial density by 4× over DTM, or 40× more than today’s aerial density,” he said. (Back-of-the-envelope calculations show that a single BPM disk could hold 10 terabytes (80 terabits) of data.) The first step is to patterned media with discrete track recording, with the next leap to bit patterned media with billions of small pillars of magnetic material, defined by NIL.
However, Albrecht cautions that for bit patterned media “there are significant challenges to the manufacturing costs and this approach is not promising if there is much difference in costs. It does require significant new capital investments. The question is: How much of a cost adder will it be?”
Over the next decade one can imaging the best of all worlds for the equipment industry: notebook computers using both forms of storage, causing HDD and disk media vendors to buy imprint lithography and etch tools to create bit patterned media disks that would store HD movies and other large files, with flash vendors gobbling up much more equipment to build leading-edge flash fabs.
Remember that the HDD industry has not been using lithography in the pre-patterned era we live in now. In a few years, a billion disks a year could have NIL-created patterns, with terabit/in.2 densities on both sides of the disk.
Another bullish thought: if self-assembly techniques work so well for improving the density of the NIL templates, surely they will be applied to the regular patterns of the NAND flash chips. University of Illinois researchers, among others, are pursuing the self assembly NIL topic for ICs.
This is going to be a sizable market for the NIL vendors. HDD patterned media development teams already have purchased seven imprint machines from Molecular Imprints Inc. (MII, Austin, Texas), with Hitachi Global Storage Technologies (which acquired IBM’s HDD business) and Yamagata Fujitsu as the two publicly identified customers. Sweden’s Obducat also has sold its Sindre imprint litho tools to HDD media R&D centers, and its electron beam equipment is designed for the template-writing for the circular disks.
The SSD and patterned media folks are spurring each other on. Soon, highly mobile people will demand the power savings and instant-on cache of SSDs, while also requiring the capacity of bit patterned disks. Sweet, indeed.
Posted by David Lammers on August 25, 2008 | Comments (3)
