A Review of the IDEMA PMR Symposium Held on … Review of the IDEMA PMR Symposium Held on December 7...

A Review of the IDEMA PMR Symposium Held on December 7, 2006

Presented by Michael A. Russak, Ph.D.Executive Director, IDEMA USADISKCON Asia Pacific 2007March 7, [email protected]

Introduction and Opening Comments

• The first IDEMA PMR symposium was held about three years before this one on February 26, 2004

• Since then PMR has transitioned from the R&D phase to shipping in products

• The transition from LMR to PMR in products will most likely occur fully over the next 2 to 3 years

• Clearly this transition will be required to sustain a reasonable areal density growth rate, assumed to be about 40% per year

• “Planar” PMR (with some variants) will take the areal density to about 1 TB/in2

Structure of the Presentation• The symposium consisted of about 20 presentations and two panel

discussions

• Six presentations were selected to be summarized in this presentation• The presenter is solely responsible for the selection and said selection

should not be construed to be a ranking of the talks in the symposium

• Hopefully the current audience will get a flavor for the breadth of presentations made and be motivated to review these and other presentations fully on the IDEMA website

• The symposium proceedings, along with this presentation, are available to IDEMA members by using the following link:

http://www.idema.org/_smartsite/modules/local/data_file/show_file.php?cmd=doc_all&h=0#

(Or go to www.idema.org, select Document Library, Event Proceedings, PMR Symposium Dec 2006 Presentations)

15

PERPENDICULAR FILM HEAD PROCESSING PERSPECTIVES

FOR AREAL DENSITY INCREASES

R. E. Fontana, Jr., N. Robertson, M.C. Cyrille, J. Li, J. KatineSan Jose Research Center

Hitachi Global Storage TechnologiesSan Jose, CA

R. E. Fontana, Jr. “Perpendicular Film Head Processing Perspectives for Areal Density Increases” 15December 7, 2006

16

Processing Overview

• As with any solid state device, lithography and patterning are the central challenges in forming memory cells or transducers

• Lithography – Minimum feature size “F”– Alignment control (3σ) “20% F”

• Patterning– Sensor and pole tip ion milling– Sensor CMP


17

Some Observations

• Lithography: Recording head processing will track the traditional International Technology Roadmap for Semiconductors (ITRS) trends. It is doubtful that head lithography will exceed the IC roadmap goals for gate resist dimensions (i.e. isolated features).

• Patterning: Because of the isolated geometry of head structures (1 minimum feature per 0.3 mm²) head patterning for pole tips and sensors uses non “mainstream IC” techniques like ion milling and subtractive CMP pattern removal to form sensor and pole tip minimum features.

• Bit Aspect Ratio (BAR): Magnetic recording areal density improvements of 40% per year are required to match IC improvements in bit cell efficiency. For constant BAR an annual minimum feature reduction of 20% is required in comparison to IC roadmap reductions of 16%. It is unlikely that constant BAR can be sustained due to the thickness of sensor structures. This BAR issue, together with the inability to scale fly height, leads to “hyper scaling”in lithography (trackwidth) to sustain annual areal density increases.


18

The Head Structure

• The perpendicular head structure

Trailing Shield

Write Pole Tip

MR Sensor

Cross Section ViewABS View


19

The IC Environment

• IC minimum features, F, are printed on a 2F pitch (equal line and space)

• The smallest IC feature is the gate resist, about 0.6F, and printed on a 4F pitch

• In 2005 the ITRS expanded the concept of lithography nodes to set distinct roadmap goals to the main IC technologies of DRAM, Microprocessors, and FLASH.

• FLASH is now considering printing equal line and space lithography using 2 mask processing, i.e. 2 masks with minimum feature F printed on a 4F pitch and anticipating increase alignment capability of tools to create the equal line and space final structure


20

Patterning

• Pole tip processing for perpendicular recording has become more ion mill intensive than for a comparable longitudinal recording head

– Perpendicular thin pole tip material ~ 100 nm– Longitudinal thick plated pole tip material ~ 1000 nm– Perpendicular ion milling to form re-entrant feature – Longitudinal ion milling to form a notch and to tune trackwidth

• Sensor processing has now evolved to intensive ion milling for tunnel structures and CMP for liftoff

• Patterning processes for sensor and pole tip formation are converging!!


21

Summary and Final Observations from a Process Person

• Minimum feature formation will track the ITRS roadmaps. Head dimensions will approach the gate resist dimensions at 500 Gbit/in² areal densities

• Alignment is becoming the critical process issue. Alignment is a key concern for the IC industry and tooling will target delivering 3σ alignment at 20% of minimum feature. Alignment is a vector quantity and perpendicular head alignments rely on one component of the vector, i.e. x and not x and y. NAND Flash is driving both alignment and minimum feature

• As sensor and pole tip thicknesses converge, patterning strategies practiced for the sensor are now being leveraged and utilized for pole tip formation.

A Caution

• Total sensor thickness and spacing do not scale with areal density placing limits on constant BAR recording system designs. The net result is hyper scaling in TW reduction.

• The write head is becoming more complex. Need to have head designs consistent with ITRS roadmap and not exceed it.


Precision Cleaning Process and Equipment Considerations for PMR media

Dave FrostSenior Director of Business Development

Media Process Equipment

December 7, 2006

23

PMR cleaning “opportunity” comment from leading Industry Analyst

“The (PMR) head-disk interface is arguably the most intricate in the history of the HDD industry………..and cleanliness has both never been more important and less understood”

“Focus on PMR Transition” paperTrendFOCUS 8/1/06

24

Particle/Defect size as areal density increasesParticle/Defect size relation as areal density increases

The incredible shrinking defect

25

Maximum Critical Defect Size Roadmap

0

0.2

0.6

1.0

1.4

40 60 80 120 160 240 320 480 640 960 1.280

Capacity per 95mm disk, GB

Dia

met

er (µ

) 2005

2003

20112009

2007

LMR PMR

26

Types of Defects to be removed via cleaning

Particles Head/Disk Interface issues that can cause a head crashMagnetic defectsCorrosionUsually can be caught at final test, before shipment

Film or StainsImpairs film adhesion Magnetic defectsCorrosion Difficult to detect and can grow over time, after shipment!

27

Scrub Trends – more is better

28

Information on PMR Cleaning Requirements

PMR media cleaning requirements are distinctly different than LMR;

PMR substrates are fundamentally different than LMR substrates due to the amount of incoming surface variability, so from a cleanability perspective PMR is more challenging than ever, because;

• PMR media does not require a texture step to aid in magnetic orientation, so the substrate surface enters the pre-sputter cleaner with an aged surface that is hydrophobic, consisting of:

• A thin oxide surface layer, based on time and storage environment metrics due to the fact substrates arrive from all over the world

• Polish induced surface asperities (scratches, nodules and ridges)• Adhered particles not removed by the final cleaning step after polish

due to existing lower capability • Loosely adhered, environmentally added particles

29

Final Comments and Considerations on PMR Cleaning Requirements

PMR is prone to single point “Killer” defect at ~ 1µ and below

PMR requires several cleaning improvement considerations

Substantially improved cleaning requirements for incoming substrates due to texture process eliminationMore aggressive scrubbing, longer scrubbing times and/or increased surface contactMore complex soaps or aggressive chemistryImproved rinsing prior to drying, so particle free disks enter the dryerHigher frequency, multiple frequency megasonics and higher powerdensitiesEnhanced drying environment, to minimize particle adders, contact points and insuring complete drying

30

Perpendicular Integration:An Industry ChallengeMartin Lynch – Chief Operating OfficerDecember 7, 2006

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Overview & Key Challenges

Competitive pressures to integrate PMR before technology, reliability, and manufacturing has matured

Key PMR HDD Integration Issues– Lower H/M spacing requirements to assure adequate drive level

writing, thermal, and altitude performance

– Signal distortion due to adjacent track DC erasure

– H/M thermal stability

– Media corrosion & surface roughness impacts

– Head magnetic write width sensitivity to media variations– TPI warping due to high skew angle

Supplier H/M manufacturing yields

32

Improved PMR Thermal Decay

One of the prime motivations to move to PMR was improved thermal decay at equivalent or greater densities compared to LMR

Thermal Decay: PMR 150Gb/in2 vs. LMR 100Gb/in2

72 ºC

40

45

50

55

60

65

70

75

0 1 2 3 4 5 6 7 8

decades of seconds

-10l

ogB

ER

PMR BER decay (raw)

decay projection

LMR BER decay (raw)

Thermal Decay: PMR 150Gb/in2 vs. LMR 100Gb/in2

72 ºC

40

45

50

55

60

65

70

75

0 1 2 3 4 5 6 7 8

decades of seconds

-10l

ogB

ER

PMR BER decay (raw)

decay projection

LMR BER decay (raw)

33

Media Corrosion, Surface Roughness Impacts

Present PMR media has had some corrosion issues– Magnetic films of PMR media are much thicker than those of LMR

media resulting in increased likelihood of corrosion

– Short term start up issues that will not hold back PMR technology

Media surface roughness more dependent upon magnetic layers & less dependent upon substrate texture– Ra of disk surface w/ PMR films can be very different than that of

same substrate w/ LMR films

– Thicker magnetic layers contribute to a significantly different surface texture

– Impacts dynamic fly height wear optimization algorithms

34

Conclusions

Over 20 years of PMR research and development have made for a fairly smooth transition

Most difficult transition impacts were due to increased sensitivity to H/M spacing requirements

Some initial adjustments optimizing manufacturing processes (supply chain & HDD)

PMR necessitates total optimization across the supply chain and unprecedented level of cooperation

Competitive pressures both within the HDD industry as well as outside will tend to force earlier adoption of new technologies, risking over-commitments

©2006 Information Storage Industry Consortium2006 Information Storage Industry Consortium

Information Storage Industry ConsortiumInformation Storage Industry Consortium

THE THE HDD TECHNOLOGY ROADMAP HDD TECHNOLOGY ROADMAP –– PMR AND BEYONDPMR AND BEYONDPaul D. FrankPaul D. Frank

December 7, 2006December 7, 2006


HDD Areal Density Trends HDD Areal Density Trends –– TodayToday’’s Views View

1

10

100

1000

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

2012

2014

Year

Are

al D

ensi

ty (G

bits

per

squ

are

inch

) Longitudinal demosPerpendicular demosProducts

Products 1998-2000100 %/yr

2000-2 demos40 %/yr

Recent products31 %/yr

INSICEHDR goalRecent demos

31 %/yr

1999 demos190 %/yr

1991-9 demos40 %/yr


International HDD Technology WorkshopInternational HDD Technology Workshop

Year 2009 (demo) 2009 2013

(demo) 2013

Areal Density (Gb/in2) 477 881 971 1416KTPI 291 348 547 644KFCI 1642 2530 1776 2199BAR 5.7 7.3 3.3 3.4Ww (nm) 44 44 23 23Wr (nm) 26.3 43 14.0 21.4Dgrain (nm) 4.7 3.5 3.3 3.7δ (nm) 15 20 15 15σ_grain_area 0.15 0.15 0.1 0.1Hk (kOe) 21.7 21.2 23.5 23.5σHk 0.05 0.05 0.01 0.01∆θ (degrees) 5 5 1 1HMS (nm) 5 20 2 20Ms (emu/cm3) 655 650 800 800Jitter (%) 12 15 15 15Relative Read Sensitivity 4.9? 6.4 6.1 4.4θ (degrees) 45 45

Roy Gustafson


Beyond Conventional PMRBeyond Conventional PMR……

The future is probably ALL perpendicular.Although modeling (and consensus) currently suggests that conventional PMR will not likely get us beyond 0.6 ~ 1.0 Tb/in2, the leading candidate successor technologies, Thermally-Assisted or Heat-Assisted Magnetic Recording (HAMR) and Bit Patterned Media (BPM) are also likely to rely on perpendicular recording, and could perhaps be best thought of as extensions, rather than replacements, of perpendicular recording.


The Superparamagnetic EffectThe Superparamagnetic Effect

©2006 Information Storage Industry Consortium

Magnetic stability requires that

KKuuV/kTV/kT > 40 ~ 60> 40 ~ 60where…

Ku = magnetic anisotropy energyV = magnetic grain volumek = Boltzmann’s constantT = absolute temperature


GMR laser

write coils

heat spot

Read Sensor

Thermal Assist (increased KKuu,utilizing very high anisotropy media)

(two favorite technology options to extend thermal limit)

deposition

islands

1 bit = 1 island

Patterned Media (increased VV,utilizing 1 large “grain” per bit)

high anisotropy

medium sensitive to temperature

‘HAMR’

Beyond Conventional Perpendicular RecordingBeyond Conventional Perpendicular Recording

Challenges: Disk ManufactureLithography/Stamping

Challenges: Head IntegrationNew Media Development

…… plus all the engineering challenges of scaling dimensions for >plus all the engineering challenges of scaling dimensions for >Terabit/inTerabit/in22 !!

R. Wood & P. Frank, presented at APMRC2006


One Potential Solution: Bit Patterned MediaOne Potential Solution: Bit Patterned Media

20 nm

~ 1,000 grains per bit

From this: To this:

100-1000grains per bit

1 grainper bit

B. Terris, Hitachi Global Storage Technologies andG. Hughes, Center for Magnetic Recording Research, University of California San Diego



The bottom line is that one or both of these approaches (HAMR or Patterned Media) will likely be needed within 2 to 4 years at the technology demonstration level and within 5 to 7 years for products, even at the current rate of areal density progress, which appears to be roughly 30%/year. Otherwise, areal density progress will slow even more…



What comes after HAMR and/or BPM?

Possibly a combination of HAMR and BPM…

Ultimately, reading/writing of individual small magnetic grains, as might be possible with Self-Organized Magnetic Array (SOMA) media, which might also be combined with either BPM or HAMR or both, and might need to be written and read with something more like a probe transducer.


Beyond Lithography: Self Organized ArraysBeyond Lithography: Self Organized Arrays

From this:Grain Diameter= 4.5±0.15nm random

σD=0.03

DC=4.5 nm

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

3.911 4.168 4.426 4.684 4.942

Pop

ulat

ion

%

Size (nm)

Grain Diameter= 4.5±0.15nm

σD=0.03

DC=4.5 nm

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

3.911 4.168 4.426 4.684 4.942

Pop

ulat

ion

%

Size (nm)0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

3.911 4.168 4.426 4.684 4.942

Pop

ulat

ion

%

Size (nm)0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

3.911 4.168 4.426 4.684 4.942

Pop

ulat

ion

%

Size (nm)

To this:

20 nm0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

1 3 5 7 9 11 13 15 17 19

Grain Size (nm)

Nor

mal

ized

Fre

quen

cy

Histogram

Lognormal Fit

Grain Diameter = 9.9±2.6 nm ∆θ50 = 6.8°

σD=0.26Dc= 10.5 nm

20 nm20 nm0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

1 3 5 7 9 11 13 15 17 19

Grain Size (nm)

Nor

mal

ized

Fre

quen

cy

Histogram

Lognormal Fit

Grain Diameter = 9.9±2.6 nm ∆θ50 = 6.8°

σD=0.26Dc= 10.5 nm

Oriented CoPtCr Films FePt Particles Deposited from SolventD. Weller, Seagate


Beyond Lithography: Self Organized ArraysBeyond Lithography: Self Organized Arrays

1

Conventional Granular Media1

1

Conventional Granular Media1 Conventional Granular Media1

130 nm 3

3 Single-Grain-Per-Bit Patterned Media

3

3 Single-Grain-Per-Bit Patterned Media3 Single-Grain-Per-Bit Patterned Media

2

2 Bit Patterned Media

2

2 Bit Patterned Media2 Bit Patterned Media

9 Tbpsi

Thermal Stability Limit∅ 3 nm → >40 Tbit/in2

Development time: ~ 13 years @ 60% CAGR and ~22 years @ 30% CAGR

9 Tbpsi


9 Tbpsi


Development time: ~ 13 years @ 60% CAGR and ~22 years @ 30% CAGR

Toward single particle

per bit recording!

D. Weller, Seagate


INSICINSIC’’s EHDR Research Program in s EHDR Research Program in EExtremely xtremely HHigh igh DDensity ensity RRecordingecording

EHDR Extended GoalEHDR Extended GoalStable Recording for HDDs at 1 Terabit/in2 and beyond…

Primary Areas of InvestigationPrimary Areas of InvestigationPerpendicular Magnetic Recording (primary focus to date)Exchange Coupled Composite Magnetic Media RecordingBit Patterned Media (likely to become a “second front” going

forward, probably aimed at ~ 2 Terabits/in2)ParticipantsParticipants

Drive Companies:Drive Companies: Hitachi GST, Samsung, Seagate, Western DigitalIndustry Suppliers:Industry Suppliers: Hutchinson, Magnecomp, MIPOX InternationalNational Research Institutes:National Research Institutes: Data Storage Institute (Singapore),

NIST Boulder Labs (US), NIST Gaithersburg Labs (US)Leading Research Universities:Leading Research Universities: 18 (on 3 continents) currently

Summary• Longitudinal Magnetic Recording

• LMR has been very, very good to us for over 50 years• It is now riding off into the sunset—farewell old friend!

• Perpendicular Magnetic Recording• PMR is alive and well• PMR is becoming the mainstream HDD recording

technology• “Planar” PMR and variants (e.g. ECC) will carry areal

density to at least 1 TB/in2

• HAMR, BPR, SOMA will carry us further

A Review of the IDEMA PMR Symposium Held on … Review of the IDEMA PMR Symposium Held on December 7...

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