Western Digital Corp.’s division HGST said Thursday it is leading the disk drive industry to the forefront in nanolithography, long the exclusive purview of semiconductor manufacturers, by creating and replicating minute features that will allow the doubling of hard disk drive (HDD) density in future disk drives.
HGST Labs, which inherits heritage from IBM and Hitachi Global Storage Technologies, announced today they have combined two innovative nanotechnologies – self-assembling molecules and nanoimprinting – to create large areas of dense patterns of magnetic islands only 10nm wide.
Nanotechnology Advance for HDDs
“As creators of the original hard disk drive, we are proud to continue our heritage of innovation with today’s nanotechnology advance. The emerging techniques of self-assembling molecules and nanoimprinting utilized at the HGST Labs will have an enormous impact on nanoscale manufacturing, enabling bit-patterned media to become a cost-effective means of increasing data densities in magnetic hard disk drives before the end of the decade,” said Currie Munce, vice president of HGST Research.
HGST’s discoveries in nanolithography overcome the increasing challenges associated with photolithography. Long the preferred technology among the semiconductor industry for achieving successively smaller circuit features using traditional ever-shorter wavelengths of light, improved optics, masks, photosensitive materials and clever techniques, photolithography advancements have slowed as ultraviolet light sources have become too complex and expensive.
Today’s announcement represents a creative answer to the problems with photolithography and has grown out of the storage industry’s unique technical and strict cost targets. HGST nanolithography achievements come at a critical juncture for storage drives as cloud computing, social networking and mobility create an ever increasing amount of content that must be stored, managed and accessed efficiently.
Magnetic Disk of the Future
This image below shows the dense patterns of magnetic islands made by HGST Labs using such emerging nanotechnologies as self-assembling molecules, line doubling and nanoimprinting. Each dot can store a single bit of information.
This pattern has 1.2 trillion dots per square inch – twice the density of today’s disk drives. To make these islands, HGST Labs used the nanotechnoloiges to created dense patterns of even smaller 10nm structures, each only about 50 atoms wide. HGST is first to combine self-assembling molecules, line doubling and nanoimprinting to make rectangular features as small as 10nm in the radial and circular paths necessary for rotating disk storage. HGST expects bit-patterned media similar to this to become a cost-effective means of increasing data densities in magnetic hard disk drives before the end of the decade.
The Nanolithography Process
Tom Albrecht, a HGST fellow, described the patent-pending work his team did in partnership with Austin, Texas-based Molecular Imprints to make dense patterns of magnetic islands in about 100 000 circular tracks required for disk drives.
Self-assembling molecules use hybrid polymers, called block copolymers, composed of segments that repel each other. Coated as a thin film on a properly prepared surface, the segments line up into perfect rows. The size of the polymer segments determines the row spacing. After polymer patterns are created, a chip-industry process called line doubling makes the tiny features even smaller, creating two separate lines where one existed before. The patterns are then converted into templates for nanoimprinting, a precision stamping process that transfers the nanometer-scale pattern onto a chip or disk substrate. A key challenge proved to be preparing the original surface so the block copolymers form their patterns in the radial and circular paths necessary for rotating disk storage. HGST is the first to combine self-assembling molecules, line doubling and nanoimprinting to make rectangular features as small as 10nm in such a circular arrangement.
Today’s announcement provides a roadmap for how to cost effectively create the magnetic islands at densities much beyond today’s capabilities. The bit density of HGST’s 10nm pattern is double that of today’s disk drives and lab tests show excellent initial read/write and data retention. When extended to an entire disk, the nanoimprinting process is expected to create more than a trillion discrete magnetic islands.
“We made our ultra-small features without using any conventional photolithography. With the proper chemistry and surface preparations, we believe this work is extendible to ever-smaller dimensions,” said Mr. Albrecht.
Because self-assembling molecules create repetitive patterns, researchers expect they will be best suited to making bit-patterned magnetic media for disk drives, uniformly spaced regions for computer memories, various wiring contacts and other periodic features of other types of semiconductor chips. Nanoimprinting and self-assembling molecules are also most easily introduced in defect-tolerant applications such as disk drives or memory, even as the industry works to perfect the technologies for more demanding applications.