The challenges for perpendicular recording technology Rob Hardeman Seagate Technology (Ireland)

The challenges for perpendicular recording technology

Rob HardemanSeagate Technology (Ireland)

January 2006

© Seagate Confidential

It’s been around for a while …

1890’s Poulsen

1970’s Iwasaki

But now it’s really here..

2005 HGST, Seagate, Toshiba…..

(that’s in strictly alphabetical order – most would say Toshiba won but….)

January 2006


Current Reality – HGSTHitachi lays groundwork for 20-GB Microdrive with century-old technology

As the resolution of digital images keeps growing, it proves a challenge for storage devices to keep up with the pace. As current technology for harddisk recording reaches its limits, a revolutionary step is needed. A new technolgy, "Perpendicular Recording" has been waiting in the wings for some time now, but apparently proved difficult to implement. Hitachi has now demonstrated a data density at 230 gigabits per square inch using this new technology...

Company Demonstrates 230 Gigabit Per Square Inch Data Density on Perpendicular Recording; Industry Luminaries Make History as Part of Worldwide Field Test Program

TOKYO – April 4, 2005 – Hitachi Global Storage Technologies is today announcing new advancements to a 100-year-old magnetic recording technology that will set the stage for ultra-high capacities such as a 20-gigabyte* Microdrive or a one terabyte 3.5-inch hard drive.

To achieve this, Hitachi has demonstrated the industry's highest data density at 230 gigabits per square inch (Gb/in2) on perpendicular recording. Hitachi believes 230 Gb/in2, which represents a doubling of today's highest longitudinal recording densities, will be implemented in commercial hard drive products in 2007. When fully realized over the next 5-7 years, perpendicular recording could enable a 10-fold increase in data densities over longitudinal recording, paving the way for new heights in capacity such as a 60 GB one-inch drive.

"We are at the cusp of the most significant hard drive technology transition of the past decade, and it's one that holds so much promise for the hard drive and consumer electronics industries," said Jun Naruse, CEO, Hitachi Global Storage Technologies. "As the biggest supplier of small-form-factor hard drives, 2.5-inch and below, consumers' demand for storing more data on smaller devices has provided a strong impetus for us to pursue perpendicular recording with a greater sense of urgency."

While the transition to perpendicular recording will start as early as the next product generation, Hitachi believes the true potential will be realized in the 200+ Gb/in2 range – the point of technology maturation when meaningful advancements in storage capacity will ensure full-scale adoption of perpendicular recording technology.

"The health of this industry over the next 5-10 years is critically tied to the successful implementation and transition to perpendicular recording technology," said Jim Porter, hard drive industry analyst and historian, owner of DISK/TREND. "Hitachi is taking a responsible approach in assuring that it proceeds smoothly with extensive testing programs."

January 2006


HGST website – excellent…

January 2006


Current Reality - Seagate

SEAGATE INTRODUCES WORLD'S FIRST 2.5-INCH PERPENDICULAR RECORDING HARD DRIVE;

SCOTTS VALLEY, Calif.—08 June 2005—

•Seagate 160GB 2.5-Inch Notebook Drive Sets New Capacity Benchmark

Breaking new ground in the mobile computing market, Seagate Technology (NYSE:STX) today announced the world's first 2.5-inch disc drive built on perpendicular recording technology - a 160GB notebook PC giant with 25 percent more capacity than the largest capacity notebook drive currently available. This expansion of Seagate's family of Momentus notebook drives further closes the capacity and performance gap between desktop and notebook PC hard drives as more users replace aging desktop systems with fast, high-capacity notebook computers

January 2006


Current Reality - Toshiba

TOSHIBA CROSSES FINISH LINE FIRST, DELIVERING FIRST HARD DISK DRIVE BASED ON PERPENDICULAR MAGNETIC RECORDING

New era of HDD technology begins with Toshiba’s shipment of 40GB 1.8-inch PMR drives

Irvine, Calif, Aug. 16, 2005 – Toshiba Storage Device Division (SDD), the industry pioneer in small form factor hard disk drives (HDDs), today announced shipment of the world's first HDD based on perpendicular magnetic recording (PMR). The new 1.8-inch HDD, used primarily in consumer electronics (CE) devices, enables up to 10,000 songs or 25,000 photos on a single 40GB platter.

The MK4007GAL HDD 1.8-inch HDD packs 40GB on a single platter – the largest single-platter capacity1 yet achieved in the 1.8-inch form factor. This breakthrough technology sets new benchmarks for data density with the highest areal density currently on the market at 206 megabits per square millimeter2 (133 gigabits per square inch). The 1.8-inch PMR HDD is now shipping in Toshiba’s new Gigabeat F41, enabling the MP3 player to store up to 10,000 songs.

"Toshiba has started an exciting new frontier for the HDD industry by leading the race to achieve this revolutionary technology, which has been the industry’s aim for more than 20 years," said Scott Maccabe, vice president, Toshiba Storage Device Division. "PMR opens the door to products we haven’t even begun to imagine, by removing the technical barriers inherent to packing more data on an HDD. Providing greater storage capacity on mobile disk drives allows Toshiba to give system OEMs the tools they need for next-generation digital information and entertainment devices."

January 2006


The items I’ll cover – or not..

IncludedSystem and environmental aspectsRead and write processes and mechanisms Details of the writer in the head

Media will be touched on but deferred to later speakers

Channels and coding will not be addressed – also to later speakers.

January 2006


Fundamentals

• Figure 1. a) Longitudinal recording with magnetization in the plane of the medium; b) perpendicular recording with magnetization perpendicular to the plane of the medium (Source: Komag.com); and c) magnetoresistive sensing of a storage bit's magnetization state in the HDD medium (perpendicular recording).

The media has vertical magnetic alignment not horizontal

The head and media are now even more linked – half the head is “in the media” as an image

The recording field is now from a deep gap - not fringing

January 2006


Not quite so obviousSignals of higher linear density are more thermally stable

for perpendicular magnetic recording due to the reduced demagnetizing field transition. This is in sharp contrast to longitudinal recording. Measurements of overwrite now need to become

“reverse overwrite” i.e. Low frequency ovewriting highThe writing point is now the trailing edge of the write pole,

not the leading gap edge. The shape of the written transition can be influenced by its geometry

Sensitivity to external magnetic fields – perhaps surprisingly with higher coercivity “stable” media -is a potential issue.

Small diameter discs are favoured for combination of capacity, data rate and access time.

January 2006


Plus ça change..

January 2006


Plus c’est la même chose..

January 2006


Disc media

It’s not getting easier !More layersMore control..

Solid State Technology September, 2005

January 2006


Soft Underlayer (SUL)

Underlayer charactersistics of importanceDynamics AnisotropyInteraction with recording layerThickness, cost, manufacturability…

January 2006


Head – reader

The existing GMR / TMR designs have adequate sensitivity.

Reader fabrication methods are largely unchanged from advanced longitudinal products.

January 2006


Erasure phenomena 1 – same track

Q. Why doesn’t the return pole write as well ?

Return pole Write pole

A. It does – unless

It’s big enough

It’s shaped properly

(or it’s not there at all !!)

And the write pole can continue to write when you don’t want it to – if it has remanence..

January 2006


Erasure phenomena 2 – side tracks

But making trapezoidal poles at less than 100 nm dimension and with angular accuracy of +/- a degree or so is not the easiest of manufacturing tasks…

January 2006


Head – writerMaterials

High moment materials are even more desirableLow remanence is criticalHigh frequency properties essentialapproaches using composites and laminates are active

Formation – additive or subtractive…

Okada et al

January 2006


Stray fields

Realised a decade ago but still under-appreciated…

Soft Underlayer and very small “probe” head as flux concentrators

More efficient heads – greater problems…

January 2006


Signals & Noise

Because the reader is mostly “on” – signals from bits not transitions there is much more low frequency component.

This is a different challenge for the channel and optimal coding

January 2006


Summary

Perpendicular recording is here – the threshold is around 200 Gb/in2 as predicted for a while. Early applications are in small form factor mobile devices.

System problems have been largely understood and worked on for up to five years. A lot of knowledge is directly transferable from longitudinal BUT a few items thought to be subtleties have proved major obstacles

Capable media exist; SUL optimisation is still possible.Manufacturing emphasis in the head has shifted from

reader sensitivity to writer formation.Consumer confidence will grow with multiple suppliers

demonstrating reliability in service.

January 2006


And what’s next ?

Patterned/selected track media ?

Thermally assisted systems (HAMR) ?

…

Documents

The challenges for perpendicular recording technology Rob Hardeman Seagate Technology (Ireland)