Deposition Technologies for 500GBin2 PMR and HAMR Write ... · PMR pole • Good thickness control • Compensate for trench etch variation Ru CVD also used as a plating seed for

Deposition Technologies for >500GB/in2 PMR and HAMR Write Heads

©2010 Veeco Instruments Inc2

OutlineOutline

Background

New technologies for PMR pole deposition

Optical films for HAMR write heads

Summary


Background – Technology RoadmapBackground – Technology Roadmap

BPMBPMHAMRHAMRPMRPMR

> 20152012 – 20142009 – 2011

2D signal processing

Media patterning

Light delivery

Near-field transducer

Sigma reduction

Damascene writer

Reduced HOC

Key AreasKey Areas

HAMR

Shingled (SWR)

2D read-back

BPM

HAMR

Shingled (SWR)

DFH

PMR

DFHTechnologiesTechnologies

> 5 TB/in21 – 5 TB/in2< 1TB/in2DensityDensity

Damascene Processes for Advanced PMR Poles


PR PR

Motivation for Damascene ProcessesMotivation for Damascene Processes

Two types of process are used for PMR poles– Subtractive process (etch)– Additive process (Damascene)

PR

Alumina

Pole

RIBE IBE IBE

Alumina

PolePR

Alumina

PR

Alumina

CMP IBE

Damascene Processes are Preferred as Geometries Shrink


Requirements for Damascene Pole ProcessesRequirements for Damascene Pole Processes

Key steps in the damascene process– Deposition of seed layer– Plating of magnetic materials– CMP

Seed layer requirements1. Conformal2. Conductive / Low resistivity3. Void free plating of magnetic materials with desired properties4. Deposited at TFMH compatible temperatures (<200ºC)5. Good thickness control6. Adhesion

CVD deposition of Ru meets the above requirements

Fabrication Sequence

Alumina Alumina Alumina

Etch CVD Ru Deposition Plate + CMP

CVD Plated pole


Ru CVD for Damascene Writer PoleEnabling FeaturesRu CVD for Damascene Writer PoleEnabling Features

CVD Ru is unique in being able to combine several key features1. Appropriate properties as a seed layer for plating

• Conformal

• Conductive / Low resistivity

2. Appropriate as a seed layer for Magnetic properties of plated layer

• Void free plating of magnetic materials

• High Bs plated layer

3. Provides ability to fine tune final track-width of the PMR pole

• Good thickness control

• Compensate for trench etch variation

Ru CVD also used as a plating seed for wrap around shields– Enables narrower track-widths by reduced cross

track interference

Step coverage95 -105 %

~ 0.4 m trenches

Step coverage95 -105 %

~ 0.4 m trenches

a

a

b

CVD- Rua

a

b

CVD- Ru


Ru CVD ChemistryRu CVD Chemistry

Precursor : RuO4– ToRuS Blend from Air Liquide

• Mixture of RuO4 in two fluorinated solvents• Liquid at room temperature• High Vapor Pressure

– Rapid Reaction – practical deposition rates– Low Temperature Process (170°C)– Small molecule that nucleates on all tested surfaces

Two step reaction (heated wafer)

A. RuO4 RuO2 + O2 (not self limiting)B. RuO2 + 2H2 Ru + 2H2O

Accomplished as cyclic CVD in 4 steps – Steps 1,2 : Reaction A: + Inert Gas Purge – Steps 3,4 : Reaction B: + Inert Gas Purge Repeat to get desired thickness


System ArchitectureSystem Architecture

Cross flow Design

Heated substrateInlet Outlet

Heated substrate

InletShowerhead Design

Outlet Outlet

RuO4 decomposition reaction to RuO2 is catalyzed by Ru but not self limiting

Cross flow architecture requires self limiting reactions to achieve good WiWuniformity and precursor utilization

Showerhead architecture allows for localized flow optimization to achieve optimum WiW uniformity and precursor utilization

NEXUS Ru CVD uses a showerhead design

180

210

240

270

300

330

1 2 3 4 5 6

ToRuS pulse time (s)

XRF

thic

knes

s (A

)

Lower ToRuS partial pressureHigher ToRuS partial pressure


Deposition ConformalityDeposition Conformality

Cross-section SEM ~400Å CVD Ru on

SiO2

Deposition conformality similar at process temperatures from 170-200°C

Deposition conformality similar for features of various sizes

Conformality of adhesion enhancing under-layers can impact stack conformality


CVD Ru: Thickness Control, ResistivityCVD Ru: Thickness Control, Resistivity

Rate Linearity of RuCVD on SiO2

0100200300400500600

0 50 100 150 200 250

# of Cycles

XR

F Thic

knes

s (A

)

170C190C y=2.6x - 40.3

y=2.8x - 29.8

C VD R u on S iO2 - R ate vs D ep Temp

2.5

2.6

2.7

2.8

2.9

3

3.1

3.2

3.3

160 170 180 190 200 210 220D ep Temp(degC )

Gro

wth

Rat

e(A

/cyc

le)

Growth rate is linear with number of cycles– Thickness can be accurately targeted– Initial nucleation delay <7 cycles at 200ºC

Good thickness control, appropriate electrical properties for plating

R es is tiv ity vs D ep T em p (~400A o n S iO 2)

17

17 .5

18

18 .5

19

19 .5

20

20 .5

21

160 170 180 190 200 210 220D ep T em p eratu re (d eg C )

Res

istiv

ity (u

Ohm

-cm

) Resistivity change slightly with temperature

– < 20µΩ-cm at 400Å on SiO2 at 170-210°C

Growth rate varies with temperature


Film Stress EngineeringFilm Stress Engineering

Ru CVD film stress ~2600MPa Stress can be tuned to desired value by periodic plasma annealing Stress driven more compressive with:

– More plasma anneals– Higher power plasma anneals– Lower pressure plasma anneals

CVD only

CVD withperiodic plasmaanneal

Substrate Substrate


Marathon Test Through Ampoule LifeMarathon Test Through Ampoule Life

Data from one 3.6L ampoules with single process recipe on Lab Tool 150mm wafers, 190°C deposition temp 632 wafers processed within tight specifications (black line shows End Of Life)

– Mean thickness at 401.6A with 3variation of 1.45%– Ampoule Utilization at 83A/cc

Sheet Resistance and Non-Uniformity with # of wafers

3.73.83.94.04.14.24.34.44.54.64.7

0 100 200 300 400 500 600 700

Wafer Number

She

et R

esis

tanc

e (o

hm/s

q)0.00.51.01.52.02.53.03.54.0

3s R

s un

if (%

)

Film Thickness (XRF) and Resistivity with # of wafers

350

360

370

380

390

400

410

420

0 100 200 300 400 500 600 700

Wafer Number

Cen

ter X

RF

Thic

knes

s (A

)

16.5

17.0

17.5

18.018.5

19.0

19.5

20.0

20.5

Res

istiv

ity(u

ohm

-cm

)

WTW 0.34% 1σ

WTW 0.36% 1σ

WTW 0.49% 1σ

Mean 1.38%

Good WTW and WIW repeatability across ampoule life< 2% 3 Non-Uniformity up to 650 wafers


CVD Ru: Uniformity, Repeatability (200mm)CVD Ru: Uniformity, Repeatability (200mm) 12-wafer lot on Lab Tool: WIW < 3% 3σ, WTW ~1% 3σ Multiple ampoules on Lab Tool: WIW ~3% 3σ, WTW ~2.5% 3σ Data through ampoule life: WIW <6% 3σ, WTW < 2% 3σ

Good uniformity and repeatability through multiple ampoules< 6% 3σ WIW, < 2% 3σ WTW through ampoule life

~400A CVD Ru on 200mm SiO2 - 200C(49pt 6mmEE measurement)

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5

1 2 3 4 5 6 7 8 9 10 11 12

Wafer #

Rs

(ohm

/sq)

00.10.20.30.40.50.60.70.80.91

Nu

(%, 1

s)

Sheet resistanceWIW uniformity

WTW repeatability 0.35% 1σ

Average WIW uniformity 0.81% 1σ

Sheet Resistance and Uniformity vs Ampoule CyclesThree Ampoules - 200mm wafer - 200C - Lab Tool

0

1

2

3

4

5

6

0 2500 5000 7500 10000 12500 15000 17500

Nos. of cycles on three 1.2l ampoules

Rs

(ohm

/sq)

0

1

2

3

4

5

6

WiW

1s

non-

unif

(%)

Average WiW 1σ non-uniformity 0.88% 1σ

WTW repeatabilty 0.83% 1σ


SummarySummary

NEXUS CVD Ru meets the film properties required of a conformal seed layer for damascene processing of high areal density write poles and shields– Conformality: >0.98– Deposition temperature: <200°C– Resistivity: <20cm– Uniformity: <3%3– Repeatability: <2%3– High efficiency of chemical use: >80Å/ml

The showerhead architecture is ideal for the ToRuS based CVD Ruprocess

The NEXUS CVD Ru system has been proven in production– Demonstrated >90% uptime– Stable film performance over lifetime of ampoule

Deposition of Optical Materials for HAMR Write Heads


HAMR TechnologyHAMR Technology

Overview– HAMR is the leading candidate for >1TB/in2 areal

densities for write heads

Concept– At high areal densities, write heads cannot produce

enough field to record data in high coercivity media

– By heating the media locally, the coercivity can be reduced and the data recorded

– HAMR write heads incorporate a laser light and near field transducer to locally heat the media

Challenges1. Integration of light source and delivery mechanism

2. Thermal management

3. Low loss optical materials for light transmission

HAMR is a key technology for >1Tb/in2

Light transmission via low loss waveguides

Media

Head

Maximum Head Field

Field needed for smaller bit size

Mag

netic

Fi

eld

Source: IDEMA Presentation 12/6/07, Mark Re, Seagate


HAMR: Waveguide MaterialsHAMR: Waveguide Materials

Laser with optical waveguide – Core/Cladding for waveguides

Requirements– Low and high index films– Low optical loss / defect free– Good Throughput

<10 dB/cm (cladding)<5 dB/cm (core)

Optical Loss

<3% R/M (200mm)Uniformity

100-500 Å/min (core)500-1500 Å/min (cladding)Rate

0 (below ellipsometer limit)k

High n: >2 (Ta2O5) (core)Low n: <2 (Al2O3) (cladding)Index

RequirementParameter


PVD Deposition Technologies for Waveguide FilmsPVD Deposition Technologies for Waveguide Films

RateUniformity (R/M 200mm)Loss

Cladding>1000 Å/min<3.5% Al2O3<10 dB/cmPVD1 Metal Mode

100-500 Å/min

60-150 Å/min

Core

Good optical propertiesLow Rate / Poor CoO

Comment

<3% Ta2O5<5 dB/cmPVD1 Dielectric Mode

<3%<0.5 dB/cmIBD

PropertyTechnology

PVD processing has flexibility of hardware and deposition modes– Hot chuck capability (up to 400ºC)– Dielectric and metal modes of deposition– RF diode / DC magnetron


Ta2O5 Dielectric/Poisoned Mode FilmsTa2O5 Dielectric/Poisoned Mode Films

No measurable change in optical

properties (ellipsometry) operating at

different O2 flows in poison mode

Processes show acceptable loss

properties

Ta Ox Hyste re sis

300320340360380400420440460480500

0 2 4 6 8 10 12 14 16

Oxyge n flow (s ccm )

Targ

et V

olta

ge(V

)

No t po is one d

Pois one d

0.07

0.07

0.1

Index U%1σ%

1.662.131.01551250Flow 3Process C

1.542.120.51451250Flow 2Process B

1.51 2.120.53503000Flow 1Process A

Process Loss ResultsDb/cm

IndexU% 1σ%200 mm

Deposition Rate (A/min)

Power (W)O2 flow (sccm)


Closed-Loop Control “Metal Mode” Al2O3Deposition for High Deposition RatesClosed-Loop Control “Metal Mode” Al2O3Deposition for High Deposition Rates

Closed-loop control with High Speed MFC partial pressure controller– Target voltage continuously monitored– High speed piezo MFC: oxygen flow adjusted to maintain target voltage– Can now operate in “forbidden” range of voltages– Rate ~ 50% of Al deposition rate achievable

150

200

250

300

350

400

450

0 5 10 15 20 25 30 35 40

O2 Flow (sccm)

V (V

olts

)

O2 incr

O2 decr

Characteristic Hysteresis Loop of Target V vs. O2

Target surface metallic

Target surface dielectric

Ideal operating point• High rate• Good film properties• Difficult to control due

to target poisoning


Al2O3: Optical LossAl2O3: Optical Loss

Strong dependence of optical loss on wafer deposition temperature No significant changes observed using ellipsometry measurement

– Measure extinction coefficient zero for all above films.– Loss not correlated to measured refractive index

• Within 1.63-1.66 range

Optical Loss vs. Wafer Temperature

0

5

10

15

20

25

30

200 210 220 230 240 250 260 270 280 290Temperature

Opt

ical

Los

s [d

b/cm

]Optical Loss vs. Deposition Temperature


0

1

2

3

4

5

6

7

8

0 2 4 6 8 10

Annealing Time [hrs]

Leng

th o

f Lig

ht S

treak

[cm

]

175C dep + 200C anneal (Ar)175C dep + 175C anneal (Ar)175C dep + 175C anneal (Ar) (cummulative anneal time)175C dep + 175 C anneal (Ar/O2)

reference:3.3 dB/cm

reference: 8.0 dB/cm

Al2O3 Post Deposition AnnealingAl2O3 Post Deposition Annealing

Appropriate post-deposition annealing (<2hrs) results in low loss Al2O3

Optimized Annealing Process

Reference data (no anneal)

0 dB

5 dB

10 dB

15 dB

20 dB

3.33 db/cm (7cm light streak)270°C deposition

8 db/cm (4-5 cm light streak)250°C deposition

waferLight Streak waferLight Streak

waferLight Streak

Prism Coupler

waferLight Streak

Prism Coupler

Optical Loss vs. Annealing Time and Temperature

Veeco has developed optimized annealing conditions that enable low temperature deposition of alumina with low-loss optical properties


Ta2O5 Thickness and Index RepeatabilityTa2O5 Thickness and Index Repeatability

<2dB/cmOptical Loss

-147Stress [MPa]

2.13Index

0.24%WIW Index (1)

0.08%WTW Index (1)

0.75%WIW Thickness (1)

0.75% (300 A/min)WTW Thickness (1)

DataTa2O5 – 2000 ÅTa2O5 Thickness Repeatability

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

0 5 10 15 20 25 30 35 40

Run #

Thic

knes

s [A

]

Ta2O5 Index Repeatability

2.0500

2.0700

2.0900

2.1100

2.1300

2.1500

2.1700

2.1900

0 5 10 15 20 25 30 35 40

Run #

Inde

x


Al2O2 Thickness and Index RepeatabilityAl2O2 Thickness and Index Repeatability

<5dB/cmOptical Loss

-126Stress [MPa]

1.67Index

0.1%WIW Index (1)

0.03%WTW Index (1)

0.4%WIW Thickness (1)

0.3% (1300 A/min)WTW Thickness (1)

DataAlumina – 1m

Ta2O5 Index Repeatability

1.65

1.655

1.66

1.665

1.67

1.675

1.68

0 5 10 15 20 25 30 35 40

Run #

Inde

x

Al2O3 Thickness Repeatability

9000

9200

9400

9600

9800

10000

10200

10400

10600

10800

11000

0 5 10 15 20 25 30 35 40

Run #

Thic

knes

s [A

]


Bi-layer Optical Loss Repeatability Al2O3 1m / Ta2O5 2000ÅBi-layer Optical Loss Repeatability Al2O3 1m / Ta2O5 2000Å

Alumina/Tantala Bilayer Loss

0

1

2

3

4

5

6

7

8

0 10 20 30 40 50Run #

Loss

[dB

/cm

]

Cassette 1 Cassette 2 Cassette 3 Cassette 4

Repeatable optical loss <5dB/cm obtained with Al2O3 1m / Ta2O5 2000Å– 12 wafers measured (total of 48 wafers run)

Four cassettes run over two days


HAMR Data SummaryHAMR Data Summary

Ta2O5 process developed for low loss core layers– Loss: <2 dB/cm– Rate: 334 Å/min– U%: 0.7% 1– WTW% 0.7% 1

Al2O3 for cladding layers– Loss: <2dB/cm (with post deposition annealing – max temp 200°C)– Rate: >1000 Å/min– U%: 0.4% 1– WTW%: 0.3% 1

Bi-layer Al2O3/Ta2O5 films show <5dB/cm loss SiO2 films in development

Documents

Deposition Technologies for 500GBin2 PMR and HAMR Write ... · PMR pole • Good thickness control • Compensate for trench etch variation Ru CVD also used as a plating seed for