Transcript The challenges for perpendicular recording technology

The challenges for
perpendicular
recording technology
Rob Hardeman
Seagate Technology (Ireland)
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
© Seagate Confidential
Current Reality – HGST
Hitachi 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
© Seagate Confidential
HGST website – excellent…
January 2006
© Seagate Confidential
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
© Seagate Confidential
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
© Seagate Confidential
The items I’ll cover – or not..
Included
System and environmental aspects
Read 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
© Seagate Confidential
Fundamentals
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
© Seagate Confidential
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).
Not quite so obvious
Signals 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 high
The 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
© Seagate Confidential
Plus ça change..
January 2006
© Seagate Confidential
Plus c’est la même chose..
January 2006
© Seagate Confidential
Disc media
It’s not getting easier !
More layers
More control..
Solid State Technology September, 2005
January 2006
© Seagate Confidential
Soft Underlayer (SUL)
Underlayer charactersistics of importance
Dynamics
Anisotropy
Interaction with recording layer
Thickness, cost, manufacturability…
January 2006
© Seagate Confidential
Head – reader
The existing GMR / TMR designs have adequate
sensitivity.
Reader fabrication methods are largely unchanged from
advanced longitudinal products.
January 2006
© Seagate Confidential
Erasure phenomena 1 – same track
Return pole
Write pole
Q. Why doesn’t the
return pole write as
well ?
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
© Seagate Confidential
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
© Seagate Confidential
Head – writer
Materials
High moment materials are even more desirable
Low remanence is critical
High frequency properties essential
approaches using composites and laminates are active
Formation – additive or subtractive…
Okada et al
January 2006
© Seagate Confidential
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
© Seagate Confidential
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
© Seagate Confidential
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
© Seagate Confidential
And what’s next ?
Patterned/selected track media ?
Thermally assisted systems (HAMR) ?
…
January 2006
© Seagate Confidential