Global Sources
EE Times-Asia
Stay in touch with EE Times Asia
EE Times-Asia > Memory/Storage

Hitachi claims 'smallest' read-head tech for Tbyte drives

Posted: 18 Oct 2007 ?? ?Print Version ?Bookmark and Share

Keywords:read-head technology? hard disk drives? HDDs? terabyte drives?

Hitachi Ltd and Hitachi Global Storage Technologies (Hitachi GST) have developed what they claim as the world's smallest read-head technology for HDDs, which will quadruple current storage capacity limits to 4Tbytes on a desktop hard drive and 1Tbyte on a notebook drive.

Researchers at Hitachi have successfully reduced existing recording heads by more than a factor of two to achieve new heads in the 30-50nm range, which is up to 2,000 times smaller than the width of an average human hair. Dubbed current perpendicular-to-the-plane giant magnetoresistive (CPP-GMR) heads, Hitachi's new technology is expected to be implemented in shipping products in 2009 and reach its full potential in 2011.

Hitachi presented the technology at the 8th Perpendicular Magnetic Recording Conference (PMRC 2007) held from Oct. 15-17, 2007 at the Tokyo International Forum in Japan.

"Hitachi continues to invest in deep research for the advancement of HDDs as we believe there is no other technology capable of providing the hard drive's high-capacity, low-cost value for the future," said Hiroaki Odawara, research director, Storage Technology Research Center, Central Research Laboratory at Hitachi. "This is an achievement for consumers as much as it is for Hitachi. It allows Hitachi to fuel the growth of the 'Terabyte Era' of storage, which we started, and gives consumers virtually limitless ability for storing their digital content."

Hitachi believes CPP-GMR heads will enable HDD recording densities of 500Gbits/in? to 1Tbit/in?, a quadrupling of today's highest areal densities. Earlier this year, Hitachi GST delivered the industry's first 1Tbyte hard drive at148Gbit/in?. The company's highest areal density shipping in products today is in the 200Gbit/in? range. These products use existing head technology, called TMR2 (tunnel-magnetoresistive) heads. The recording head and media are the two key technologies controlling the miniaturization evolution and the exponential capacity growth of the HDD.

Cutting through the noise
The continued advancements of HDDs requires the ability to squeeze more, and thus, smaller data bits onto the recording media, necessitating the continued miniaturization of the recording heads to read those bits. However, as the head becomes smaller, electrical resistance increases, which, in turn, also increases the noise output and compromises the head's ability to correctly read the data signal.

High signal output and low noise is what is desired in hard drive read operations; thus, researchers try to achieve a high SNR in developing effective read-head technology. Using TMR head technology, researchers predict that accurate read operations would not be conducted with confidence as recording densities begin to exceed 500Gbit/in?.

The CPP-GMR device, compared to the TMR device, exhibits less of an electrical resistance, resulting in lower electrical noise but also a smaller output signal. Thus, issues such as producing a high output signal while maintaining a reduced noise to increase the SNR needed to be resolved before the CPP-GMR technology became practical.

To address this challenge, Hitachi and Hitachi GST have co-developed high-output technology and noise-reduction technology for the CPP-GMR head. A high electron-spin-scattering magnetic film material was used in the CPP-GMR layer to increase the signal output from the head, and new technology for damage-free fine patterning and noise suppression was developed. As a result, the SNR, an important factor in determining the performance of a head, was drastically improved. For heads with track widths of 30nm to 50nm, industry-leading SNRs of 30dB and 40dB, respectively, were recently achieved with the heads co-developed at Hitachi GST's San Jose Research Center and Hitachi's Central Research Laboratory in Japan.

According to the companies, recording heads with 50nm track widths will debut in commercial products in 2009, and those with 30nm track widths will be implemented in products in 2011. Current TMR heads, shipping in products today, have track widths of 70nm.

Article Comments - Hitachi claims 'smallest' read-head ...
*? You can enter [0] more charecters.
*Verify code:


Visit Asia Webinars to learn about the latest in technology and get practical design tips.

Back to Top