1
1
PMR Media Technology
Tom Yamashita and Gerardo Bertero
Komag, Inc.IDEMA Singapore Conference
March 7, 2007
2Outline
• PMR Media • State of the art granular oxide media• Key current issues with PMR media • Media improvement opportunities• Beyond current media structures and designs
• Summary
2
3
1999199919991999 2000200020002000 2001200120012001 2002200220022002 2003200320032003 2004200420042004 2005200520052005 2006200620062006 2007200720072007 2008200820082008 2009200920092009 2010201020102010 2011201120112011 2012201220122012
10101010
100100100100
1,0001,0001,0001,000
10101010
1515151520202020
3030303040404040
60606060
80808080120120120120
160160160160240240240240
320320320320480480480480
640640640640960960960960
12801280128012801920192019201920
100% CAGR100% CAGR100% CAGR100% CAGR60% CAGR60% CAGR60% CAGR60% CAGR40% CAGR40% CAGR40% CAGR40% CAGRCapacity/Platter (95mm)Capacity/Platter (95mm)Capacity/Platter (95mm)Capacity/Platter (95mm)
Areal Density and Capacity vs. TimeAreal Density and Capacity vs. Time95 mm Disk Capacities and Technology Transitions95 mm Disk Capacities and Technology Transitions
Year of Product IntroductionYear of Product IntroductionYear of Product IntroductionYear of Product Introduction
Are
al D
ensi
ty (G
b/in
Are
al D
ensi
ty (G
b/in
Are
al D
ensi
ty (G
b/in
Are
al D
ensi
ty (G
b/in
22 22 )) ))
Longitudinal
Long. SAF
Perpendicular
DTR, BPM, HAMR?
250
4
LMR and PMR Recording Geometries
LMR PMR
Recording Head
Read ElementRead Shield
Soft Magnetic Underlayer
Recording Layer
Write Shield
3
5
LMR Media Structure
Stabilizing Layer
Ru
Bottom Magnetic Layer
Exchange Enhancing Layer
Underlayers
Top Magnetic Layer
M
M
~80 Å
~160 Å
~30 Å
BC
CH
CP
6CoCrPt-Oxide Perpendicular Media Structure
Substrate (AlMg or Glass)Substrate (AlMg or Glass)Substrate (AlMg or Glass)Substrate (AlMg or Glass)
OvercoatsOvercoatsOvercoatsOvercoats
CoCrPtO Hard Magnetic LayerCoCrPtO Hard Magnetic LayerCoCrPtO Hard Magnetic LayerCoCrPtO Hard Magnetic Layer
Seed LayerSeed LayerSeed LayerSeed Layer
SAF Soft Magnetic Under Layer
SAF Soft Magnetic Under Layer
SAF Soft Magnetic Under Layer
SAF Soft Magnetic Under Layer
Adhesion LayerAdhesion LayerAdhesion LayerAdhesion Layer
Capping Layer
RuRuRuRu----Alloy Interlayer Alloy Interlayer Alloy Interlayer Alloy Interlayer
4
7Comparison of LMR and PMR Media Cross-Sections
SubstrateSubstrateSubstrateSubstrate
SubstrateSubstrateSubstrateSubstrate
Recording LayerRecording LayerRecording LayerRecording Layer
Magnetic Soft
Magnetic Soft
Magnetic Soft
Magnetic Soft Underlayer
Underlayer
Underlayer
Underlayer
LMRLMRLMRLMR
PMRPMRPMRPMR
8
-150 -100 -50 0 50 100 150-30
-20
-10
0
10
20
30
m (m
emu/
cmm
(mem
u/cm
m (m
emu/
cmm
(mem
u/cm
22 22 )) ))
H (Oe)H (Oe)H (Oe)H (Oe)
Radial Circum.
-150 -100 -50 0 50 100 150-2
-1
0
1
2
M (m
emu)
M (m
emu)
M (m
emu)
M (m
emu)
H (Oe)H (Oe)H (Oe)H (Oe)
Radial Circum
-150 -100 -50 0 50 100 150-30
-20
-10
0
10
20
30
m (m
emu/
cmm
(mem
u/cm
m (m
emu/
cmm
(mem
u/cm
22 22 )) ))
H (Oe)H (Oe)H (Oe)H (Oe)
Radial Circum
Typical Magnetic Domains in SUL Structures
Single SUL CoTaZr
SAF SULCoTaZr/Ru/CoTaZr
HB SULCoCrTa/Ru/CoTaZr
5
9Nucleation Layer
• Main purpose is to:• Break magnetic exchange between SUL and Recording layer• Control recording layer crystallogrphic orientation• Control recording layer grain size• Help with recording layer grain isolation
• These nucleation layers provide smaller magnetic grain sizes and more magnetic grain isolation.
10Rocking Curves of Co and Ru (0002) Peaks
Ru Co(∆θ∆θ∆θ∆θ50) (∆θ∆θ∆θ∆θ50)
S7817 2.68 3.29S7176 2.53 3.02A8155 2.26 2.90P8035 2.06 2.76
15 18 21 24 270
500000
1000000
1500000
Inte
nsity
(cou
nts)
Inte
nsity
(cou
nts)
Inte
nsity
(cou
nts)
Inte
nsity
(cou
nts)
Theta (degree)Theta (degree)Theta (degree)Theta (degree)
S7817 RuCr10
S7176 RuCr15
A8155 RuCr15
P8035D RuCr15
15 18 21 24 270
100000
200000
300000
400000
Inte
nsity
(cou
nts)
Inte
nsity
(cou
nts)
Inte
nsity
(cou
nts)
Inte
nsity
(cou
nts)
Theta (degree)Theta (degree)Theta (degree)Theta (degree)
S7817 RuCr10
S7176 RuCr15
A8155 RuCr15
P8035D RuCr15
Ru (0002) Co (0002)
6
11
10 nm
Magnetic Grain Morphology LMR/PMR
LMR PMR
12Current Issues with PMR Media
• Production Ramp of PMR media• Yields and Utilization • Cost Reduction
• Learning curve for• Drive and head integration • Measurements – magnetic and recording • Process monitor and control
• Ruthenium problem • Price went from <$200/troy oz. to over $800/troy oz in the last 4
months.• HDD industry is now the biggest consumer of Ruthenium • ~ 1M troy/oz mined per year = 1 m3 of metal• Production of Ruthenium tied to Platinum mining (Quantity mined
is not likely to increase on the short term).
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13
PMR Media Improvements
• SUL domain noise is not a problem with SAF SUL structures.
• C-axis orientation is already very good.
• Physical grain size is rather small already.
• Magnetic grain size is optimized (increased somewhat) by adding intergranular exchange.
Where can we expect improvements to come from ?
Given the above,
14PMR Media Improvement OpportunitiesPMR Media Improvement OpportunitiesPMR Media Improvement OpportunitiesPMR Media Improvement Opportunities
� SUL Domain and Magnetic Noise Reduction� SAF SUL Structure improvements� Domain free SULs
� Grain Size Uniformity� DC noise reduction� Narrower transition parameter
� IL Thickness Reduction� Better writability ���� Higher Hc� Sharper head field gradients ���� Narrower transition parameter
� Improved Magnetic Layer Structures� ECC Media/Exchange Spring Media� Narrower transitions, better DC noise, better writability
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15
How Much Improvement ?How Much Improvement ?How Much Improvement ?How Much Improvement ?
At the Intermag 2006 Conference:
• Limit of PMR recording using non-patterned granular media is placed at ~400-500 Gb/in2 (E.g., R. Wood (CA01), S. Greaves (ER02), M. Kryder (ZA)).
• Current (or about to be launched) commercial PMR programs are designed at 130-180 Gb/in2 recording.
• Assuming 3 to 4 dB SNRme needed for every doubling of areal density, we will need to deliver 6 - 12 dB of SNRme improvement on non-patterned, granular oxide media (of any kind).
16
With IL thickness reduction we expect:With IL thickness reduction we expect:With IL thickness reduction we expect:With IL thickness reduction we expect:• Stronger writing fieldsStronger writing fieldsStronger writing fieldsStronger writing fields• Sharper write field gradientsSharper write field gradientsSharper write field gradientsSharper write field gradients• Higher OWHigher OWHigher OWHigher OW• Higher SNRHigher SNRHigher SNRHigher SNR
Interlayer Thickness Reduction EffectsInterlayer Thickness Reduction EffectsInterlayer Thickness Reduction EffectsInterlayer Thickness Reduction Effects
x
2x
9
17Optimizing Exchange in Granular MediaOptimizing Exchange in Granular MediaOptimizing Exchange in Granular MediaOptimizing Exchange in Granular Media
Intergranular exchange coupling is key for overwrite, SNR and nucleation field optimization. However, each of these properties optimize at different points so, tradeoffs must be made when optimizing media performance as a whole. Various approaches and schemes have been proposed to facilitate this task, e.g.,
• Capping layer media• Coupled granular composite media, CGC
The capping layer approach is the most practical for performance and manufacturability.
18Capping Layer EffectCapping Layer EffectCapping Layer EffectCapping Layer Effect
Hc (Oe)Hc (Oe)Hc (Oe)Hc (Oe) S*S*S*S* Hn (Oe)Hn (Oe)Hn (Oe)Hn (Oe)5000 0.45 -1900
Hc (Oe)Hc (Oe)Hc (Oe)Hc (Oe) S*S*S*S* Hn (Oe)Hn (Oe)Hn (Oe)Hn (Oe)5100 0.58 -2936
Nucleation field improvement for ATI robustness
S6651S6651S6651S6651
-150
-100
-50
0
50
100
150
-20000 -15000 -10000 -5000 0 5000 10000 15000 20000
S7176 S7176 S7176 S7176
-100
-75
-50
-25
0
25
50
75
100
-20000 -15000 -10000 -5000 0 5000 10000 15000 20000
w/o Cap Layer w Cap Layer
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19
ECC and Exchange Spring ECC and Exchange Spring ECC and Exchange Spring ECC and Exchange Spring MediaMediaMediaMedia
���������������� ������������������� ������������������� ������������������� ���
Material with extremely high anisotropy Ku and volume Vhard.
Store information. Provide thermal stability
Soft material with volume Vsoft. Facilitate switching
of the grain.
2
s s
EM H V
ξ ∆=hardKu V×
hard softV V+
This figure of merit term can be used to compare the switching fields of different kinds of media with the same thermal barrier, volume and magnetization
UNIVERSITY OF MINNESOTAUNIVERSITY OF MINNESOTAUNIVERSITY OF MINNESOTAUNIVERSITY OF MINNESOTA
Courtesy of Prof. R. Victora
11
���������������� ������������������� ������������������� ������������������� ���
2
s s
EM H V
ξ ∆=
Perpendicular Media1.0ξ =
45° tilted Media
2.0ξ =
ECC Media
Mhard/Msoft
Jex/
(KuV
)
1.71.81.9
UNIVERSITY OF MINNESOTAUNIVERSITY OF MINNESOTAUNIVERSITY OF MINNESOTAUNIVERSITY OF MINNESOTA
ξ ����
Courtesy of Prof. R. Victora
���� ���� � ������� ���� � ������� ���� � ������� ���� � ���
• The switching process of ECC media include two steps: first, magnetizations of the soft regions coherently rotate to a certain angle; second,complete switching of each grain.
• ECC media switches more rapidly than conventional media.
• ECC media impervious to misalignment (up to 20°) of easy axes.
• The write field profile associated with ECC media is narrower in the cross track direction than that associated with conventional perpendicular media.
• The combination of enhanced thermal stability and reduced adjacent track erasure should allow recording at 1 Terabit/inch2.
UNIVERSITY OF MINNESOTAUNIVERSITY OF MINNESOTAUNIVERSITY OF MINNESOTAUNIVERSITY OF MINNESOTA
Courtesy of Prof. R. Victora
12
( )ε ε
ε ε
−=+
2
2 1
1
hard K Ac
hard J A
KHJ ε = s
KH
KK
=s HJ J
ε = sA
H
AA
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��� ������ � ��������� ��������� ���� �������������� ��!���""��
�#
$#
%#
��
$�
%� = × 214
hardc
hard
KHJ
=s HA A
= 0sK
= × 215
hardc
hard
KH
J= / 5s HK K
ε = sJ
H
JJ
−= × 2( )14
hard softc
hard
K KH
J
Courtesy of Dr. Dieter Suess
�������������
∆&�'�(���
�" )" !""
*���� +� ,
∆&�+&
�-,
� �.
∆ = 14E F AK
∆ = 1E K V
∆ = 14E F AK
∆ = 14 5E F AK
��������/�0��������1��2�1����)
����� ����2����0�)34
*����=
15HALK
=1
HALK
Courtesy of Dr. Dieter Suess
13
25Angular Dependence of Switching FieldAngular Dependence of Switching FieldAngular Dependence of Switching FieldAngular Dependence of Switching Field
0 15 30 45 60 75 900.6
0.7
0.8
0.9
1.0
1.1
1.2
h cr (=
Hcr
θ/H
cr θ
=0o)
Angle (degree)Angle (degree)Angle (degree)Angle (degree)
tCap
C7 - 0 nm C3 - 6 nm C6 - 12 nm S8675 Expected
Exchange Spring media behavior
26Ho and KuV/kT of ES Media
1E-9 1E-7 1E-5 1E-3 0.1 102000
4000
6000
8000
10000
n = 2/3 and fn = 2/3 and fn = 2/3 and fn = 2/3 and foooo = 1 GHz = 1 GHz = 1 GHz = 1 GHz
HHHHoooo K K K K
uuuuV/kTV/kTV/kTV/kT
9149 101.59149 101.59149 101.59149 101.57733 112.87733 112.87733 112.87733 112.85118 169.65118 169.65118 169.65118 169.6
HH HHcrcr crcr (O
e) (O
e) (O
e) (O
e)
Time (sec)Time (sec)Time (sec)Time (sec)
ttttCapCapCapCap
C7 - 0 nm C3 - 6 nm C6 - 12 nm
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DTR LMR Process
DTR processing to form groovesBy wet-etch process .
Clean textured NPP
Sputter Full Stack LMR Media
DTR LMR ProcessDTR LMR ProcessDTR LMR ProcessDTR LMR Process(etched(etched(etched(etched----NiPNiPNiPNiP))))
etchedetchedetchedetched----NiPNiPNiPNiP DiskDiskDiskDisk
Sputtered LMR film stackSputtered LMR film stackSputtered LMR film stackSputtered LMR film stack
Finished DTR LMR DiskFinished DTR LMR DiskFinished DTR LMR DiskFinished DTR LMR Disk
TEM xTEM xTEM xTEM x----sectionsectionsectionsection
28DTR PMR Structure
DTR processing to form groovesby wet-etch process.
Clean Polished NPP
Sputter Full Stack PMR Media
DTR PMR ProcessDTR PMR ProcessDTR PMR ProcessDTR PMR Process(etched(etched(etched(etched----NiPNiPNiPNiP))))
SAF Soft SAF Soft SAF Soft SAF Soft UnderlayerUnderlayerUnderlayerUnderlayer (SUL)(SUL)(SUL)(SUL)
EtchedEtchedEtchedEtched----NiPNiPNiPNiP
NiP groove width/depth: 155 nm / 33 nm at 380 nm TP
Finished DTR PMR DiskFinished DTR PMR DiskFinished DTR PMR DiskFinished DTR PMR Disk
TEM xTEM xTEM xTEM x----sectionsectionsectionsection
15
29Summary
• We are working on both performance and manufacturability aspectsof PMR media.
• Much improvement in grain size, intergranular exchange, SUL noise and c-axis dispersion has already been accomplished.
• Opportunities for SNR improvement remain with IL thickness reduction mainly (must have appropriate heads to take advantage of such improvement).
• Additional improvements will be possible with new structures incorporating concepts from ECC and exchange spring media structures.
• Given the head and media strong interactions with PMR recording, need to work closely with customers to identify other areas of improvement based on specific applications.
