f r e e d o m t o i n n o v a t e high density ... - idema230g perpendicular experiment - overview...

1Hitachi Confidential

f r e e d o m t o i n n o v a t e

9/26/2005

© 2004 Hitachi Global Storage Technologies

High Density Perpendicular RecordingTechnology and Challenges of Hitachi’s 230 Gbit/in2 Demonstration

Kurt A. RubinManager, Recording Systems & Integration

San Jose Research Center

230 Gbit/in2 Team:C. Bonhote, M. Chen, Q. Dai, H. Do, B. Knigge, Y Ikeda, P. Kasiraj, Q. Le, B. Lengsfield, J. Li, S. MacDonald, B. Marchon, A. Moser, V. Nayak, L. Nix, T. Okada et al, R. Payne, N. Robertson, H. Rosen, M. Schabes, N. Smith, K. Takano, C. Tsang, P. van derHeijden, W. Weresin, M. Williams, M. Xiao, HGST AdTech H/M

Hitachi San Jose Research Center

This presentation is being projected from a

Hitachi prototype perpendicular HDD

IDEMA DISKCON USA, 2005 Conference, Sept. 21, 2005

2© 2005 Hitachi Global Storage Technologies

Longitudinal scaling will end after 50+ years of success

Growth of Recording Areal Densities

0.001

0.01

0.1

1

10

100

1000

1975 1980 1985 1990 1995 2000 2005

Year of Introduction

Are

al D

ensi

ty (G

b/in

2 )

1st MR Head

1st GMR Head

In 1990’s rate of increase greatly accelerated to 60-100% CGR, still by scaling

4/05 Hitachi 230 Gb/in2

7/05 Fuji-Electric 253 Gb/in2

8/05 Seagate 245 Gb/in2

8/05 TDK 238 Gb/in2

“Superparamagnetic”effect” poses a significant challenge for longitudinal

Perpendicular technology required

Simple scaling allowed for increasing areal density for many years at 30% CGR


SPT write pole. With SUL gives higher

write field in media than a longitudinal

write head

Perpendicular Recording Attributes

disk motion

Write-Pole

Soft Underlayer(SUL)

Read-shield

Read-shield

read-element

SUL imagingreduces reader

MRW

Recording Layer: Thermally stable. Tight sigma on grain diameter, Hk. Optimization of exchange, Hk, M. Highly oriented.

Low spacing u higher field/gradient, higher output, better resolution, less

side-reading/writing

SUL: Part of head. Return path for flux Increases write field for switching the media.Thin EBL u higher

fields, higher output,less side-reading and

less side-writing

Trailing-shield gives sharper gradients & larger field angle

⇒ lower noise ⇒ sharper transitions⇒ higher linear density

Return-pole &Trailing Shield

Main-Pole


230G Perpendicular Experiment - Overview

Motivation • Examine extendibility of perpendicular technology

Major challenges to achieve 230 Gb/in2

1. Media – Create media combining adequate SNR and good thermal stability, together with narrow track writability

2. Write head – Build tiny geometry trailing-shield writers with adequate field and gradient

3. Read head - Narrow track and narrow gap definition

Micromagnetic recording system simulationsIncorporated detailed media structure and switching physicsGuided head and media designs and optimized system performance


Detailed Simulation of Magnetic Field from Write Head

Effe

ctiv

e W

rite

Fiel

dDown-track Position

• Effective write field depends on applied field angle

• ‘Stoner-Wohlfarth’ effective write field

• Heffective = Hmag * ( cosx + sinx )1/x

• Fit media-dependent exponent x to angle-dependent Hc

Fiel

d

Down-track Position

Finite Element Models of Head StructuresPerpendicular

Field

LongitudinalField

TS head


Higher Gradient and Write Field Angle u Lower Noise

A large write field angle reduces the distribution width of write fields resulting in lower noise and sharper transitions

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

-10 0 10 20 30 40 50

Angle (deg)H

r (no

rm)

GGLA

∆Hswitch (TS)

Single pole

Trailing Shield

Angle dependent Kerr data

Applied Field Angle [degrees]H

r(n

orm

aliz

ed)

∆Hswitch (SPT)

SPT ∆angle

Switching Field vs. Angle

TS ∆angle

Effe

ctiv

e W

rite

Fiel

d G

radi

ent

Media Ho [T]

Maximize gradient for reasonable H0

240 Oe/nm


Reliable Micromagnetic Simulations Predict Performance

TEM of media

FEM model of the write head

Micromagnetic simulation consistent with experiment

Ability to guide component optimization and to assess even higher areal density designs

Transition roughness

Recorded transition

Down-track Distance [nm]


System Performance and Writing Quality Predictions

Optimization of jitter performance

Cro

ss-tr

ack

Jitte

r [nm

] 15% off-trackjitter=1.9nm

On-trackjitter=1.7nm

Down-track Position [nm]

Cro

ss-tr

ack

Pos

ition

[nm

]

110nm

Transition curvature

Simulations results:• Signal to noise ratio, transition jitter, a-parameter, magnetic write

width, transition curvature, etc., …

-30 -20 -10 0 10 20 30-1

1.2

1.4

1.6

1.8

2

2.2

Cross-track Displacement [nm]


Transition Curvature Decreases Achievable Linear Density

1 µm

1 µm

1024 kfci

229 kfci

MRW

MWW @ 2Taverage transitioncurvature

-80 -60 -40 -20 0 20 40 60 80-60

-40

-20

0

trans

ition

pos

ition

[nm

]

offset [nm]

(independent of density)

Transitions written with 214 GBit/in2 head

Position Offset [nm]

Tran

sitio

n P

ositi

on [n

m]

Transition Curvature

High-resolution MFM imaging

hrMFM229kfci

1024kfci


Trailing Shield Writer Design for Performance

100 nm100 nm

Pole width 75 nmPole thickness 140 nmTS gap 35 nm

100 nm100 nm

w 85 nmhfl 45 ofl 125 nm

Vertical SectionFlare region

Write Pole

Trailing shield

Write Pole

TS gap

Pole width

TS throat

Trailing Shield Requirements

• Narrow gap significant field gradient improvement: trailing shield gap ~ head-underlayer-spacing (HUS)

• Narrow throat minimize write field loss from write flux shunting by trailing shield

• High saturation moment minimize effective gap broadening from magnetic saturation

• Tight tolerances maintain write field and gradient

ABS SEM

P2Top-section

SEM


Conventional CIP-GMR Read Head was Used for Demo

-300 -200 -100 0 100 200 300

0.0

0.2

0.4

0.6

0.8

1.0

sign

al

cross track position [nm]

microtrack profile at 500 kfci

0 200 400 600 800 10000

10

20

30

40

50

60

70

80

90

100

mag

netic

read

wid

th [n

m]

linear density [kbpi]

Relatively flat density dependence of read width

53nm

40A Free layer ∆R/R~13% couponModerate HM ratio 61 nm

Linear density [kbpi]

Cross-track position [nm]

Sig

nal

CIP-GMR enabled by large signal and side-reading reduction of perpendicular recording

Narrow track fabrication issues:1. Sensor track-width definition

193 nm optical lithography2. Narrow sensor height

Scaled with track-width & tighter lapping control3. Narrow & planar read gap

Thin leads4. Non-ideal edge effects

Wafer & row patterning processesM

agne

tic re

ad w

idth

[nm

]


230Gb/in2 Recording Medium

Media Properties (matched to head)• Small crystalline grains for low noise• Areal moment density: 0.7 memu/cm2

• H0: 12 kOe, coercivity: 6.4 kOe• Nucleation field: -2.4 kOe• KuV/kT: 75 • Thermally stable

10 nm

SUL

CoCrPt-O SiN Overcoat

EBL – Growth Layers

Substrate

SUL Growth Layers

Overcoat LayerSiN

Recording LayerCoCrPt-O oxideHighly oriented magnetic momentAnisotropy dispersion angle ~ 2-4 degreesOptimum non-zero exchange

Exchange Break Layer (EBL)Media Growth Template u media Ho

Soft-Under-Layer (SUL)Magnetic Layer with High PermeabilityCarries Magnetic Flux between Poles of the Head


209-233 Gb/in2 Achieved with Bit-Cell Aspect Ratios ~ 4

Test Conditions• 15% off-track criteria• 10-4 symbol-error-rate on-track• 10-2 symbol-error off-track• 1 symbol = 10 bits

on-track ~10-5 bit erroroff-track ~10-3 bit error

• Pseudo-random background noise and squeeze

• Noise predictive PRML• 4 parity bits• 50 MB/s data rate• Zero skew head

• Well behaved bathtub shapes• Good writabilty with narrow pole-tips at

low write current

Squeeze Track Pitch [nm]

Off-

track

Pos

ition

[nm

]

80 120 160 200 240

0

5

10

1

5

20

25

Gb/in2 Kbpi Ktpi TP [nm] BAR233 965 242 105 4.0217 946 217 111 4.1214 910 235 108 3.9

Off-track = 15% squeeze

Off-Track Distance [nm]

Log

(Byt

e E

rror)


Summary of 747 Data of Optimized Performance

125

150

175

200

225

250

275

800 825 850 875 900 925 950 975 1000 1025 1050 1075 1100Linear Density (kBPI)

125Gb/in2

150Gb/in2

175Gb/in2

200Gb/in2

225Gb/in2

250Gb/in2

275Gb/in2

BAR = 8

BAR = 7

BAR = 6

BAR = 5

BAR = 4.5

BAR = 4

Trac

k D

ensi

ty (k

TPI)

BAR = 3.5BAR = 3

230Gb/in2

TS Heads

SPT Heads

SPT headTS head


References

• “Head challenges for perpendicular recording at high areal density,” Ching Tsang, C. Tsang, C. Bonhote, Q. Dai, H. Do, B. Knigge, Y. Ikeda, Q. Le, B. Lengsfield, J. Lille, J. Li, S. MacDonald, A. Moser, V. Nayak, R. Payne, N. Robertson, M. Schabes, N. Smith, K. Takano, P. van der Heijden, W. Weresin, M. Williams, M. Xiao, presented at TMRC 2005, IEEE Trans. Magn. (in print)

• “Perpendicular magnetic recording technology at 230 GBit/in2” Andi Moser, et al., presented at ISPMM 2005, J. Magn. Magn. (in print)

• “Dynamic micromagnetic studies of anisotropy effects in perpendicular write heads”, Manfred E. Schabes et al, Intermag 2005, Nagoya, paper CB-03, (in print)

• “Perpendicular magnetic recording technology at 230 GBit/in2,” Paul van derHeijden et al, to be presented at 50th Magnetism and Magnetic Materials Conference, October 2005, San Jose, Calif.

• “Recording Studies of Perpendicular Media Leading to 230 Gbit/in2,” Min Xiao, et al, to be presented at 50th Magnetism and Magnetic Materials Conference, October 2005, San Jose, Calif.


Summary

230Gb/in2 demonstrated

Full 747 taking into account 15% off-track capability, on-track bit error rate ~10-5, off-track bit error rate ~10-3

Narrow geometry components• Linear density 965 kbpi

• Track density 242 ktpi

• BAR 4

Good thermal stability and writability

Multiple head-media combinations


These materials contains forward-looking statements within the meaning of the federal securities laws, including statements about the following: the future demand for hard disk drives, future revenue projections for the hard disk drive industry, Hitachi’s future product portfolio, and the future demand for consumer products. These statements are subject to risks and uncertainties that could cause actual results and events to differ materially, including the following: possible fluctuations in the demand for our products; possible delays in developing and marketing new products;the introduction of new products by competitors or the entry into the market of new competitors;and the possibility of legal disputes. A detailed discussion of other risks and uncertainties that could cause actual results and events to differ materially from forward-looking statements in included in Hitachi Ltd.'s most recent filings and reports with the Securities and Exchange Commission. Hitachi Ltd and Hitachi GST undertake no obligation to update forward looking statements to reflect events or circumstances occurring after the date of this presentation.

Forward-looking Statements

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