lithography options for the 32nm half pitch node - … 2006 1 lithography options for the 32nm half...

imec 2006 1

Lithography options for the 32nm half pitch node

Luc Van den hove and Kurt Ronse

Lithography options for the 32nm half pitch node

imec 2006 3

Fig 7&8 Simplified – Option 12005 ITRS Product Technology Trends -

Half-Pitch, Gate-Length

1.0

10.0

100.0

1000.0

1995 2000 2005 2010 2015 2020

Year of Production

Prod

uct H

alf-P

itch,

Gat

e-Le

ngth

(nm

)

DRAM M1 1/2 Pitch

MPU M1 1/2 Pitch(2.5-year cycle)

Flash Poly 1/2 Pitch

MPU Gate Length -Printed

MPUGate Length -Physical

MPU M1.71X/2.5YR

GLpr IS =1.6818 x GLph

MPU & DRAM M1& Flash Poly

.71X/3YR

Flash Poly.71X/2YR

Gate Length.71X/3YR

Before 1998.71X/3YR

After 1998.71X/2YR

ITRS roadmap:32 nm half pitch requirement

imec 2006 4

32nm half pitch options

NA k1 λNA

kresolution λ.1=

Lens complexityNew liquid (nf>1.8)

New optical material(n>1.9)

Technical challenges:

ArF Immersion1.65 NA

(k1=0.275)

Single exposure

EUVL0.25 NA(k1=0.6)

Single exposure

Source powerOptics lifetimeResist infrastructureMask infrastructure

ArF Immersion with

double patterning1.35 – 1.40 NA

(k1=0.20)

Overlay requirementProcess integration

imec 2006 5

Outline

• Introduction

• 193 nm immersion lithography

• EUV Lithography

• Double patterning

• Conclusions

imec 2006 6

193nm immersion lithography

from RESEARCH IDEA…

in WORLD RECORD TIME

to DEVELOPMENT

imec 2006 7

193nm immersion lithography

to MANUFACTURING ???

DEFECTIVITYfrom DEVELOPMENT…

Is immersion ready ?

imec 2006 8

Status 193nm immersion lithographyDefectivity

Air bubbles

Water marks and drying stains

Particles

Resist / TC – water interaction

imec 2006 9

Air bubbles


Early config. Latest XT:1250i config.

24 bubbles 0 bubbles

: no longer an issue

imec 2006 10



Receding contact angle approaching 0Depends on material hydrophobicityDepends on scan speed (500mm/s)…

imec 2006 11


Receding Contact Angle

Num

ber o

f Wat

er D

ropl

ets


imec 2006 12


Leachingof resist components in the water

Water uptakeby resist / TC…


imec 2006 13


Leaching statusMethod in place for dynamic leaching measurements

0.0E+00

5.0E-12

1.0E-11

1.5E-11

2.0E-11

2.5E-11

0 2 4 6 8 10time (s)

leac

hing

(mol

/cm

2 )

0.E+001.E-122.E-123.E-124.E-125.E-126.E-127.E-128.E-129.E-121.E-11

leac

hing

rate

(mol

/cm

2 .s)

PAR-817

Amount of leaching during first 1-2 seconds is key (for a high throughput immersion scanner)


imec 2006 14

0.0E+00

5.0E-12

1.0E-11

1.5E-11

2.0E-11

2.5E-11

0 2 4 6 8 10time (s)

leac

hing

(mol

/cm

2 )

PAR-817

0.0E+00

5.0E-14

1.0E-13

1.5E-13

2.0E-13

2.5E-13

0 2 4 6 8 10

time (s)

leac

hing

(mol

/cm

2 )

PAR-817 + TCX-007


Leaching statusMethod in place for dynamic leaching measurementsTop coats very efficient in preventing leaching (~100 x less)

Leaching currently prime reason to use top coatRecent immersion specific resists much lower leaching (factor 4)

(5.10-12mol/cm plateau)


imec 2006 15


Wafer edge film peelingEdge bead engineering !

Particle transportfrom chuck onto wafer

Wafer Stage

Resist

Shower Head

Wafer Stage

Resist

Shower Head

Particles

imec 2006 16


Wafer edge film peelingEdge bead engineering !

BARC

Resist

Before exposure After exposure Before develop

SEM after develop

BARC

Resist Resist

BARC BARC

Resist

Particles

imec 2006 17

Breakthroughs by strong partnership

Defect reduction trend (daily monitor)

Spectacular progress over the past 12 months

Immersion defects

050

100150200250300350400450500

1 2 3 4 5 1 2 3 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 1 2 3 1 2 3 1 2 1 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

9-Nov

9-Nov

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6-Dec

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6-Dec

6-Dec

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13-Dec

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26-Jan

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30-Jan

30-Jan

30-Jan

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31-Jan

31-Jan

1-Feb

1-Feb

1-Feb

2-Feb

2-Feb

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3-Feb

5-Feb

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9-Feb

9-Feb

10-Feb

10-Feb

10-Feb

date

Coun

t (#

defe

cts/

waf

er)

2005 2006

imec 2006 18

“Litho friendly 6T SRAM design”

193nm immersion lithographyPolarization

0.186μm2 cell size32nm node

ASML XT:1250i0.85 NA

Poly hp : 75nm (0.330 k1)Fin hp : 62nm (0.273 k1)

SRAM array after spacer etch

SRAM array after spacer etch

imec 2006 19

“Litho friendly 6T SRAM design”

193nm immersion lithographyPolarization

ASML XT:14000.93 NA

Dipole Y illumination

BE+15.4% BE+10.3% BE+5.1% BE BE-5.1% BE-10.2% BE-15.4%

BE+6.6% BE+3.3% BE BE-3.3% BE-6.6%

Un-polarized

Polarized

Fin hp 55nm (0.265 k1)22nm node

imec 2006 20

193nm immersion lithographyHyper NA 193i

-240nm NF +120nm +210nm-300nm -120nm +60nm500nm DoF


50nm k1=0.31 1.2NA, σ=0.74/0.94, annular

45nm k1=0.28 1.2NA, σ=0.82/0.97, C-Quad-30


42nm k1=0.26 1.2NA, σ=0.89/0.98, Dipole X-35



50nm k1=0.31 1.2NA, σ=0.74/0.94, annular

45nm k1=0.28 1.2NA, σ=0.82/0.97, C-Quad-30


42nm k1=0.26 1.2NA, σ=0.89/0.98, Dipole X-35-240nm NF +120nm +210nm-300nm -120nm +60nm500nm DoF


50nm k1=0.31 1.2NA, σ=0.74/0.94, annular

45nm k1=0.28 1.2NA, σ=0.82/0.97, C-Quad-30


42nm k1=0.26 1.2NA, σ=0.89/0.98, Dipole X-35



50nm k1=0.31 1.2NA, σ=0.74/0.94, annular

45nm k1=0.28 1.2NA, σ=0.82/0.97, C-Quad-30


42nm k1=0.26 1.2NA, σ=0.89/0.98, Dipole X-35

ASML XT1700i – NA=1.2

imec 2006 21

193nm immersion lithographyHyper NA 193i

41nm, approaching 0.25k1

P82 – k1 0.25441nm dense

P84 – k1 0.26142nm dense

P86 – k1 0.26743nm dense

1.2NA, Y-pol, dipole X 35° s=0.98-0.89CPL – chromeless lines42nm barc, 120nm resist, topcoat

41nm dense


P82 – k1 0.25441nm dense

P84 – k1 0.26142nm dense

P86 – k1 0.26743nm dense


41nm dense

ASML XT:1700i1.2 NA41nm, approaching 0.25k1

P82 – k1 0.25441nm dense

P84 – k1 0.26142nm dense

P86 – k1 0.26743nm dense


41nm dense


P82 – k1 0.25441nm dense

P84 – k1 0.26142nm dense

P86 – k1 0.26743nm dense


41nm dense

ASML XT:1700i1.2 NA41nm, approaching 0.25k1

P82 – k1 0.25441nm dense

P84 – k1 0.26142nm dense

P86 – k1 0.26743nm dense


41nm dense


P82 – k1 0.25441nm dense

P84 – k1 0.26142nm dense

P86 – k1 0.26743nm dense


41nm dense

ASML XT:1700i1.2 NA

imec 2006 22

1520253035404550556065

0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65

NA

Hal

f Pitc

h (n

m) k1 < 0.27

k1 < 0.4

193nm immersion lithography Ultimate limits

• k1 as function of NA and half pitch (λ=193nm)

32nm half pitch limit requires 1.65 NA

32nm

45nm

imec 2006 23

BS

Excimer laser

Prism

PC

D

WDS

Stages

Pol

Waveplate

Wafer

High index liquid testing on ASML Immersion Interference Printer

193nm immersion lithographyLiquids beyond water?

HIL stays between prism and wafer during stage motion

imec 2006 24

193nm immersion lithographyOutlook high index liquids

25

30

35

40

45

50

3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0

Exposure dose (uncalibrated)

Line

CD

(nm

)Water (n=1.44) : 14.6 % EL

• Lithographic results 2nd generation fluids (n=1.65) :36nm HP

25

30

35

40

45

50

2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5

Exposure dose (uncalibrated)

Line

CD

HIL (n=1.65) : 18 % EL

imec 2006 25

2nd generation HI liquidsContact angle measurements

• Much lower surface tension : containment ?

H20

HI Liquid

imec 2006 26

2nd generation HI liquidsInteraction HI liquid with resist (defect formation ?)

• Purpose: – apply droplets of the liquid on either an inert substrate or resist

surface in a controlled way

– Analyse what is left after drying (profilometry)

100 µm

imec 2006 27

NA=1.65 requirements

Fluid recycling systemRadiation & contamination evaluation

Fluid containmentScanning tests & IH evaluation

High nf Fluid characterization (nf>1.9)Defectvity: Leaching & drying stains

High nf Resist developmentimaging characterization, defectivity

Optical systemHRI glass evaluation (nf > 1.8)

appl

icat

ion

imm

ersi

onsy

stem

lens

Can we use HI fluids?

Can we make the system?

Can we make the lens?

TIMING is most critical

imec 2006 28

1520253035404550556065

0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65

NA

Hal

f Pitc

h (n

m) k1 < 0.27

k1 < 0.4

193nm immersion lithography Ultimate limits


32nm

45nm

imec 2006 29

Outline

• Introduction


• EUV Lithography


• Conclusions

imec 2006 30

EUV LithographyCritical challenges

• 2005 International Symposium on EUVL

Top 3 Critical Issues 2004 Rank1. Resist resolution, sensitivity and LER 32. Collector lifetime 23. Availability of defect free masks 14. Source power

Remaining Critical Issues• Reticle protection during storage, handling and use• Projection and illuminator optics quality and lifetime

*** Significant concern: Timing and cost / business case for EUVLdevelopment.

Critical Technical Issues for EUV Lithography

imec 2006 31

Experimental : Interference LithographyPaul Scherrer Institute (PSI), Switzerland

Mask:

2mask

waferPP =

beamlineExposure chamber

imec 2006 32

EUV Resist progress40

nm

32.5

nm

30 n

m

2004 2005 2006

20 mJ/cm2 7.5 mJ/cm2 12.4 mJ/cm2

imec 2006 33

AD-tool imaging results :40nm scanning H-lines/spaces ‘through focus’

-100 nm -50 nm near focus

+50 nm +100 nm

>200 nm DOF

Resist: MET-2D~18 mJ/cm2NA=0.25, σ=0.5no process optimization yet

40nm L/S

imec 2006 34

AD-Tool imaging results :40nm scanning H-lines/spaces ‘through slit’

-10.6 mm -6.36 mm 0.0 mm 6.36 mm 10.6 mm

(22-May-’06)Full slit coverage

40nm L/S

Resist: MET-2D~18 mJ/cm2NA=0.25, σ=0.5no process optimization yet

imec 2006 35

AD imaging results: 55 nm CH

55 nm CH

Resist: MET-2Dno process optimization

~40 mJ/cm2

NA=0.25, σ=0.5

Dense (aligned)

Dense (staggered)

Iso(aligned)

Iso(staggered)

All at same conditions:

- NA/Illumination/focus/dose

- Binary mask

- No OPC applied!

imec 2006 36

1520253035404550556065

0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65

NA

Hal

f Pitc

h (n

m) k1 < 0.27

Double patterningOutlook

k1 = 0.4

k1 = 0.27


20 0.25 0.30 0.350.2

EUVL

32nm

45nm

193 nm

22nm

imec 2006 37

Outline

• Introduction


• EUV Lithography


• Conclusions

imec 2006 38

Double patterning (2x litho + 2x etch)Possible integration flow

SiNitride HM

Resist

Int.Exposure 1

& development

Transfer tohardmask

Int.Int.

1nm alignment error -> 1nm CD change

Exposure 2

& development

Transfer tohardmask

k1=0.19

40 nm L&Setched in oxide

hard mask on poly-Si

ASML XT:14000.93 NA

imec 2006 39

Design Split exercises NAND FLASHDouble Line for Poly

Annular 0.8/0.4Unpolarized

1.35NA

SPLIT + OPC PROCESS CHECKTARGET

min pitch 64nmk1=0.22 intuitive split

Cr - ImB

Cr - ImA

min pitch 128nmk1=0.44

imec 2006 40

Design Split exercises NAND FLASHDouble Trench for Poly


1.35NA

PROCESS CHECKTARGET SPLIT + OPC

Cr - ImB

Cr - ImA



imec 2006 41

Design Split exercises Logic NOR Double Line for Poly


1.35NA

TARGET SPLIT + OPC PROCESS CHECK


Cr - ImB

Cr - ImA

imec 2006 42

Design Split exercises Logic NOR Double Trench for Poly


1.35NA

TARGET SPLIT + OPC PROCESS CHECK

Cr - ImB

Cr - ImA


imec 2006 43

resist 48.7nm at 130nm pitchLER(3s) 3.1nm

HM etch&strip 38nm at 130nm pitchLER(3s) 5nm

resist+HM48.7nm at 130nm pitchLER(3s) 3.1nm

Si

Poly Si

BARCHM

Resist

Litho Etch/strip Litho Etch/strip

Double Line for PolyDP k1=0.14

/1250i – 193nm 0.85NA – Dipole DP 32nm 1:1

Poly32nm at 65nm pitch

imec 2006 44

1520253035404550556065

0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65

NA

Hal

f Pitc

h (n

m)


k1 = 0.4

k1 = 0.20

k1 = 0.27


20 0.25 0.30 0.350.2

EUVL

32nm

22nm

45nm

193 nm

Double patterning

imec 2006 45


• Lowest risk route to 32nm half pitch in time

• But… worst in terms of CoO– Requires 2 critical masks per critical layer

– Reduces throughput (~ factor 2)

– Adds cost of second etch step

– Impacts total cycle time (additional photo, etch, …)

– Some integration approaches very critical for alignment

• Any development improving CoO issues is a plus for double patterning

imec 2006 46

Outline

• Introduction


• EUV Lithography


• Conclusions

imec 2006 47

Summary and conclusions

• Still 3 lithography options for 32nm half pitch critical levels

• Immersion lithography beyond water urgently needs a 3rd

generation fluid (n>1.8) to be identified• EUV lithography makes steady progress

– First ASML EUV alpha demo tools about ready to ship to the field

– EUV resist has become issue number one and requires a lot of focus

– EUVL is the solution for small contact holes !

• Double patterning is the lowest-risk route towards 32nm but CoO needs to be controlled

• Towards 22nm volume production, EUVL is the only option

imec 2006 48

1520253035404550556065

0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65

NA

Hal

f Pitc

h (n

m)


k1 = 0.4

k1 = 0.20

k1 = 0.27


20 0.25 0.30 0.350.2

EUVL

32nm

22nm

45nm

193 nm

imec 2006 49

Aknowledgements

LamRESEARCH

Equi

pmen

tSu

pplie

rsM

ater

ial S

uppl

iers

Softw

are

Supp

liers

Mas

k sh

ops

The world’s largest 193nm immersion lithography effort

STMicroelectronicsSTMicroelectronics

IC c

ompa

nies

imec 2006 50

Thank you!

lithography options for the 32nm half pitch node - … 2006 1 lithography options for the 32nm half...

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