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Komag R&D / Confidential
Current Progress in Current Progress in Discrete Track Recording Discrete Track Recording
(DTR) Media(DTR) MediaOctober 25October 25thth, 2006, 2006
Komag, Inc.1710 Automation Parkway
San Jose, CA 95131
October 25, 2006 Komag Confidential 2
OutlineOutline• Discrete Track Recording (DTR) Concept
– Feature dimensions• DTR Project Goals
– Key Technology Requirements• Nano-Imprint Lithography (NIL) Overview
– Masters and Stampers– Process Steps and Tools
• Spin-coat• Bake• Imprint• Develop (ash)• Wet etch• Strip and Clean
• DTR LMR and PMR Process Results Overview– DTR LMR– DTR PMR
• Overview of Recording Results• Current Challenges for DTR Processes
DTR Land & Grooves
Slider
October 25, 2006 Komag Confidential 3
Substrate
Write & ReadHead
Conventional Media: Magnetic Read Width (MRW) ≅ 50% to 60% TPMagnetic Write Width (MWW) ≅ TP
DTR Media:Land-to-Groove Ratio ≅ 3 to 1MRW ≅ Land Width = 75% TPMWW ≥ Land Width
Discrete Track Recording (DTR) ConceptDiscrete Track Recording (DTR) Concept
Write Wide Write Wide -- Read Wide Read Wide ≥≥ Land WidthLand Width
October 25, 2006 Komag Confidential 4
0
100
200
300
400
500
600
700
0 100 200 300
ArealAreal Density vs. Track PitchDensity vs. Track Pitch
Track Pitch (nm)
Den
sity
(Gb/
in2 )
B.A.R. = 567
October 25, 2006 Komag Confidential 5
ArealAreal Density vs. Groove WidthDensity vs. Groove Width(land(land--toto--groove ratio: 3 to 1)groove ratio: 3 to 1)
0
100
200
300
400
500
600
700
0 20 40 60 80
Groove Width (nm)
Den
sity
(Gb/
in2 )
B.A.R. = 567
October 25, 2006 Komag Confidential 6
DTR Project GoalsDTR Project Goals
• Develop cost-effective processes and tools for manufacturing DTR (patterned) media.– Nano-Imprint Lithography (NIL) has been primary focus.
• Study the recording performance of DTR media.– Ideally requires recording heads optimized for DTR media
(i.e., MRW ≅ land width).
• Study the feasibility and value of pre-formatted servo in DTR media.– Test various pattern schemes
• Study the tribology and corrosion performance of DTR media.– Slider fly-height is affect by grooved structures.
October 25, 2006 Komag Confidential 7
Key Technology RequirementsKey Technology Requirements
• Masters/stampers– E-beam tool capable of uniformly mastering features widths sub 30 nm.– Ability to format complex servo patterns.– Ability to replicate single master into multiple stampers.
• Tooling to uniformly spin-coat polymer on both sides of a disk simultaneously.
• NIL– Tool (i.e., press) which can uniformly imprint both sides of a disk
simultaneously out to the disk edge with high through-put.– Polymer which supports high fidelity and fast imprint cycle.– Reliable mold release for many cycles
• Wet-etch process with minimal undercutting (anisotropic) in order tomaintain small feature dimensions.
• Post-etch polymer stripping and cleaning process for DTR media– Possibly requires grooves to be filled and planarized.
October 25, 2006 Komag Confidential 8
NanoNano--Imprint Lithography (NIL) Imprint Lithography (NIL) Processing of Substrate (Disk)Processing of Substrate (Disk)
Develop Polymer Mask
Imprint PolymerNi Stamper
NiP Substrate
Wet Etch Substrate
Strip Polymer
polymercoating
October 25, 2006 Komag Confidential 9
Mastering ProcessMastering ProcessUsing an rUsing an r--θθ ElectronElectron--Beam RecorderBeam Recorder
ElectronElectron--Beam ColumnBeam Column
ResistResist--CoatedCoatedSi WaferSi Wafer
AFM xAFM x--section of developed resist mastersection of developed resist masterDepth = 70 nmDepth = 70 nm FWHD = 30 nm FWHD = 30 nm Pitch = 150 nmPitch = 150 nm
October 25, 2006 Komag Confidential 10
Process Steps
Pre-coat disk cleaning and/or sputtering
Spin-coat disk with polymer
DTR Disk: NIL Process Steps
95 mm NiP disk coated with polymer on both sides from 17 mm radius to disk edge.
Disk Location
Polymer thickness(Å)
i.d. 599
m.d. 624
o.d. 639
October 25, 2006 Komag Confidential 11
Process Steps
Pre-coat disk cleaning and/or sputtering
Spin-coat disk with polymer
Bake Polymer Coating
Imprint polymer (press)
DTR Disk: NIL Process Steps
Angle 0.2 1.5 2.70 47 43 4990 42 42 46
180 49 54 49270 52 51 52
Distance from Disk Edge (cm)225 nm TP Stamper
polymer-coated disk embossed at 150 nm pitch
Imprint IssuesContamination control
particlesdelaminated polymer
Selection of polymerlow temp imprintshort imprint time
Selection of elastomerdurabilitycompliance
Stampermold release agentcompliance durabilitycost
Imprint eccentricity
Imprinting to the disk edge
Isothermal Imprinting
Process cycle time (throughput)imprint depth (nm)
October 25, 2006 Komag Confidential 12
imprint time (sec)
imprint depth (nm)
imprint depth range (nm)
imprint depth (nm)
imprint depth range (nm)
105 48.0 ± 1.2 58.2 ± 3.075 46.5 ± 1.9 53.8 ± 3.845 43.0 ± 2.6 53.3 ± 1.515 43.6 ± 1.4 51.8 ± 4.42 39.8 ± 2.0 47.6 ± 3.9
Imprint Depth as a Function Imprint Depth as a Function of Imprint Timeof Imprint TimeImprint pressure = 1300 psi
Imprint temperature = 131 ºCRamp time to max. pressure = 15 sec
Imprint depth measured using AFM at m.d. of disk at 0º, 90º, 180º and 270º.
polymer X
Dynamic viscosity = 10±2 mPa·sTg = 115 ºC
Dynamic viscosity = 5±2 mPa·sTg = 115 ºC
standardimprint time
polymer Y
October 25, 2006 Komag Confidential 13
DTR Disk: NIL Process StepsProcess Steps
Pre-coat disk cleaning and/or sputtering
Spin-coat disk with polymer
Bake Polymer Coating
Imprint polymer (press)
Ash in O2 plasma to create polymer mask
Polymer Mask
Surface of Substrate
68-70/33
66-66/31
64-70/34
66-68/30
60-64/30
64-66/26
72-76/28
68-70/27
G (nm)/H (nm)at 42.5, 32.5,22.5 mm radii
Gap Width (G)
Polymer Height (H)
October 25, 2006 Komag Confidential 14
Process Steps
Pre-coat disk cleaning and/or sputtering
Spin-coat disk with polymer
Bake Polymer Coating
Imprint polymer
Ash in O2 plasma to create polymer mask
Wet etch Substrate
Strip polymer (chemical)
Clean disk
DTR Disk: NIL Process Steps
NiP surface (wobbled tracks)
Etched grooves
SEM of Etched NiP
October 25, 2006 Komag Confidential 15
NanoNano--Imprint Lithography (NIL) Processing of Imprint Lithography (NIL) Processing of NiPNiP Disk With Narrow Grooves at 225 nm Track Pitch (TP)Disk With Narrow Grooves at 225 nm Track Pitch (TP)
Develop Polymer Mask
Imprint PolymerNi Stamper
NiP Substrate
Wet Etch Substrate
Strip Polymer
polymercoating
52 nm
35 nm 37 nm
36 nm
59 nm
23 nm
57 nm
Imprinted polymer
Polymer mask
Etched-NiP disk
October 25, 2006 Komag Confidential 16
Overview of DTR LMR ProcessOverview of DTR LMR Process
DTR processing to form groovesWet-etch process is slightly anisotropic
horizontal etch ~ 1.5 × vertical etch
Clean textured NPP
Sputter Full Stack LMR Media
DTR LMR Process(etched-NiP)
etched-NiP Disk
Sputtered LMR film stack
Finished DTR LMR Disk
TEM x-section
October 25, 2006 Komag Confidential 17
Original Demo of DTR PMR StructureOriginal Demo of DTR PMR Structure
DTR processing to form groovesWet-etch process is slightly anisotropic
horizontal etch ~ 1.5 × vertical etch
Clean Polished NPP
Sputter Full Stack PMR Media with SAF SUL
DTR PMR Process(etched-NiP)
SAF Soft Underlayer (SUL)
Etched-NiP
NiP groove width/depth: 155 nm / 33 nm at 380 nm TP
Finished DTR PMR Disk
TEM x-section
October 25, 2006 Komag Confidential 18
Alternative DTR PMR ProcessAlternative DTR PMR Process
Sputter Interlayers + Hard Magnetic Layers + Carbon
Clean NPP
Sputter SAF Soft Underlayer (SUL)
DTR processing to form groovesWet-etch process is isotropic
horizontal etch ~ 2 × vertical etch
SULSUL
Ru
Ru
DTR PMR Process(etched-SUL)
195 nm 203 nm
34 nm
Etched-SUL
Etched-SUL
grooveland
October 25, 2006 Komag Confidential 19
Limitations of DTR PMR Limitations of DTR PMR EtchedEtched--NiPNiP and Etchedand Etched--SUL ProcessesSUL Processes
• Poor Groove Geometry (e.g., shallow side-wall angles in grooves due to thick sputter layers, particularly for the etched-NiP case).
• Difficult to achieve narrow grooves due to groove depth requirement for magnetic isolation (i.e., spacing loss) and nearly isotropic etching of grooves.
• Possible poor magnetic properties caused by groove structure in Soft Magnetic Underlayer (SUL) (e.g., circumferential magnetization of SUL).
October 25, 2006 Komag Confidential 20
Current Process Development Current Process Development For DTR PMRFor DTR PMR
Sputter Full Stack PMR Media on NPP(or without carbon)
Coat w/polymer
Emboss and Develop Polymer MaskWet Etch ONLY Hard Magnetic (HM) Layer
Strip Polymer/Clean(Sputter carbon)interlayers
seed layer
HM HM
SAF SUL
interlayersseed layer
HM HM
polymer polymer
SAF SUL
interlayersseed layer
Hard Magnetic Layers (HM)
SAF SUL
polymer
October 25, 2006 Komag Confidential 21
SEM and AFM of SEM and AFM of OffOff--Track and LandTrack and Land--Groove Area Groove Area
AFM of Etched-PMR w/CarbonTrack Pitch (TP) = 380 nm
landgroove
SEM of Etched-PMR w/CarbonTrack Pitch (TP) = 380 nm
Etched-PMR w/Carbon
October 25, 2006 Komag Confidential 22
NPP Disk
texture
Clean
DTR Process
Clean
Sputter
Spin Coat Disk w/Polymer
Emboss Disk w/Stamper
Develop Mask
Wet Etch Disk
Strip Polymer
DTR Disk Fabrication Process FlowDTR Disk Fabrication Process FlowDTR LMR Process DTR PMR Process
Sputter Disk(full stack)
DTR Process
Clean
Lube
NPP Disk
Clean
October 25, 2006 Komag Confidential 23
Recording TestsRecording TestsLocating DTR TracksLocating DTR Tracks
DTR tracks
Data track
DTR RegionContinuousFilm
ContinuousFilm
Effect of eccentricity on waveforms
October 25, 2006 Komag Confidential 24
-1250 -1000 -750 -500 -250 0 250 500 750 1000 1250Cross-Track Position (nm)
0
5
10
15
20
25
30
35
40
45Sl
ot S
NR
(dB
)
100 kFCI500 kFCI
Measured SNR vs. CrossMeasured SNR vs. Cross--Track PositionTrack PositionDTR LMR MediaDTR LMR Media
DTR Structure:DTR Structure:Land Width = 550 nmLand Width = 550 nmGroove Width = 250 nmGroove Width = 250 nmGroove Depth = 60 nmGroove Depth = 60 nm
Head Parameters:Head Parameters:MWW = 240 nmMWW = 240 nmMRW = 155 nmMRW = 155 nm
October 25, 2006 Komag Confidential 25
-500 -400 -300 -200 -100 0 100 200 300 400 500Cross-Track Position (nm)
0
2
4
6
8
10R
esid
ual L
F Si
gnal
(μV)
ConventionalDTR
Residual LF Signal After OverwritingResidual LF Signal After OverwritingLand Width = 290 nmLand Width = 290 nmGroove Width = 250 nmGroove Width = 250 nmGroove Depth = 44 nmGroove Depth = 44 nm
MWW = 340 nmMWW = 340 nmMRW = 237 nmMRW = 237 nm
October 25, 2006 Komag Confidential 26
-500 -400 -300 -200 -100 0 100 200 300 400 500Cross-Track Position (nm)
0
10
20
30
40
50
HF/
LF O
verw
rite
(dB
)
DTRConventional
Overwrite vs. CrossOverwrite vs. Cross--Track PositionTrack PositionFor DTR and NonFor DTR and Non--Patterned MediaPatterned Media
Land Width = 290 nmLand Width = 290 nmGroove Width = 250 nmGroove Width = 250 nmGroove Depth = 44 nmGroove Depth = 44 nm
MWW = 340 nmMWW = 340 nmMRW = 237 nmMRW = 237 nm
Land Width
October 25, 2006 Komag Confidential 27
AFM and MFM of AFM and MFM of OffOff--Track and LandTrack and Land--Groove AreaGroove Area
AFM Image MFM Image
off-track land
track lands
grooves
off-track land
grooves
track lands
AC demagnetized case
Etched-PMR w/o Carbon
October 25, 2006 Komag Confidential 28
DTR PMR MediaDTR PMR MediaSpectrum @ 150 KFCISpectrum @ 150 KFCI
0 100 200 300 400 500 600 700-50
-40
-30
-20
-10
0
10
frequency (MHz)
Spe
ctru
m (d
B)
Land
Groove
• Signal reduction is about 45 dB from land to groove.• No signal pickup from the grooves.
October 25, 2006 Komag Confidential 29
Servo Using Wobbled GroovesServo Using Wobbled Grooves
f1 = 720 nmf2 = 790 nm
October 25, 2006 Komag Confidential 30
SNR Concern with SNR Concern with Wobbled Servo BlocksWobbled Servo Blocks
• Wavelength:– Carrier = 400nm (127 KFCI); Wobble f1= 720 nm, f2=790 nm
• Example shown here is for readback from center of land.– Land-to-grove = 3:1; MRW = land width; wobble 0-p = 1/4 of TP.
0 1 2 3 4 5 6 7 8 9 10-80
-60
-40
-20
0
20
40
1/λ (1/um)
Side band is more than 20dB lower than Carrier
Spectrum
October 25, 2006 Komag Confidential 31
Spectral Side Bands Spectral Side Bands Due to Groove WobbleDue to Groove Wobble
0 50 100 150 200 250 300 350 400-50
-40
-30
-20
-10
0
10
20Pos=-16uIn.txt
Frequency MHz
Pow
er S
pect
alD
ensi
ty (d
B)
188 190 192 194 196 198 200 202
-30
-25
-20
-15Pos=-16uIn.txt
f0+f2 f0+f1
f0=165.8MHzf1 = 29.00 MHz λ1 = 726 nmf2 = 26.36 MHz λ2 = 799 nm
0 100 200 300 400-50
-40
-30
-20
-10
0
10
Write Carrrier Signal or DC-Erase Land Area To Detect Groove Wobble
October 25, 2006 Komag Confidential 32
DTR LMR MediaDTR LMR MediaExperimental DataExperimental Data
-30 -20 -10 0 10 20 30-35
-30
-25
-20
-15
-10
-5
0
5
10
15E5793L: Land:Groove=1:1
Write Position (uIn)
20Lo
g10
Am
plitu
de (
dB)
f0f0+f1f0+f2
• Read width is comparable to land width.• Side band signals peak at track edges which could be used to develop new servo schemes on DTR media. However, side band signals are more than 20 dB below the carrier.
October 25, 2006 Komag Confidential 33
Focus of DTR LMR DevelopmentFocus of DTR LMR Development
• Prototype DTR Disk with Servo Capability– DTR LMR Disk Specifications:
• 225 nm track pitch (113 kTPI)• 3:1 land-to-groove ratio (groove width ~ 56 nm)
SEM ofetched-NiP disk
October 25, 2006 Komag Confidential 34
Focus of DTR PMR DevelopmentFocus of DTR PMR Development
• Demo extendibility of DTR for PMR media with High Areal Density Storage Capacity– DTR PMR disk specifications:
• 150 nm track pitch (170 kTPI)• 3:1 land-to-groove ratio (groove width ~ 36 nm)
SEM of Etched-PMR w/CarbonTrack Pitch (TP) = 150 nm
Land-to-groove ratio ~ 1 using current Stamper
October 25, 2006 Komag Confidential 35
Current Challenges For Current Challenges For DTR DevelopmentDTR Development
• Fabrication of e-beam Masters and Ni stampers with sub 30 nm wide features.
• Demonstrate the capability to wet etch very narrow grooves in PMR media with adequate signal reduction. (e.g.,20 nm for 100 nm TP at a 3:1 land-to-groove ratio).
– Requires e-beam masters and stampers with features < 20 nm wide.– Requires optimization of NIL process conditions in order to maintain groove
uniformity and minimize line edge roughness.
• Availability of recording heads for DTR– Groove volume affects slider fly-height– MRW ≅ Land Width (e.g., ~112 nm at 150 nm TP for a 3:1 land-to-groove ratio)
• Corrosion/Tribology on etched-PMR disks– Do grooves need to be filled and planarized?
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