The Design of Chemically Amplified Resist for EUV...

Page.12006 EUVL Symposium on October 16 – 18, 2006 @ WTC Barcelona, Spain

The Design of Chemically Amplified Resist for EUV lithography

C/N:1220610082

Hiroto Yukawa, Ryoichi Takasu, Takako Suzuki, Takeyoshi Mimura,Tasuku Matsumiya, Daiju Shiono, Akiya Kawaue, Takahiro Dazai and Hideo Hada

TOKYO OHKA KOGYO CO., LTD.Advanced Material Development Division 1

2006 EUVL Symposium on October 16 – 18, 2006 @ WTC Barcelona, Spain Page.2

Introduction

EUV Resist Criteria

Discussion

Summary

Acknowledgements

Contents


3

Ref: Steering Committees – 2nd, 3rd & 4th International EUVL Symposia

EUVL Critical Issues

Industry concern about re sists for EUVL has steadily risen to #1 issue

1.Optics: projection and illumination quality & lifeti me

1.Optics: projection and illumination lifeti me

1.Optics: quality for 32nm half-pitch node

1.Masks: defect protection during storage, handling, use

1.Source: power1.Resist: resolution, sensiti vity and LER

1.Source: power1.Masks: defect protection during storage, handling, use

1.Optics: projection and illumination lifeti me

1.Masks: defect-free availability

1.Resist: resolution, sensitivity and LER met simultaneousl y

1.Masks: defect protection during storage, handling use

1.Collector: Lifetime1.Source, Optics: lifeti me of components


1.Resist: resolution, sensiti vity and LER met simultaneousl y


1.Source: power and lifetime including condenser optics lifetime

200520042003

Concern is that EUVL resists may not simultaneously meet:Re solution targets for 22nm half-pitch nodeEnergy sensitivity target ≤ 5 mJ/cm2

Line-Edge Roughne ss target of ≤ 3nm

EUV Lithographic Critical Issue

lithographicuncertainty

principle

Sensitivity

Resolution LWR

/ LE

R

Shot Noise

Acid

Diff

usio

n

Chemical Flare

Outgas

The achievement of EUV resist is becoming more and more concerned.Four critical categories of EUV resist, sensitivity (photo speed), resolution, LWR/LER and outgas might be unable to achieve simultaneously current requirements in flash 32nm hp time line (2012).


Contents ITRS 2005(Flash 2009)

ITRS 2005(Flash 2012) Current status Countermeasure TOK targets

(Beta data in 2H,2008)

Resolution 45nm 1:1 32nm 1:1 35nm 1:1(polymer resist)

Polymer aggregateMolecular sizePAG quantum yieldDeveloper system…

32nm 1:1

PhotoSpeed

5mJ/cm2

(115W)ND 18mJ/cm2

(polymer resist)

Molecular sizeProtecting groupPAG quantum yieldRemaining solvent in resistfilm…

15mJ/cm2

LWR

2.7nm(LER:<1.4nm)

Gate18nmlength

<SEMATECH>

1.9nm

4.3nm @ 35nm 1:1(polymer resist)

LER4.0nm @ 50nm1:1

(low molecular resist)

Thin film thicknessPolymer structureProtecting groupPAG quantum yieldDeveloper system…

3nm

Outgas TBD ND 2.00 X 10-6 Pa(low molecular resist)

Eact control of protectinggroupCasting solventPAG quantum yieldPolymer-bound-PAGRemaining solvent in resistfilm

TBD

Etching ND ND similar to NovolakCarbon densityBulky structure…

Similar to Novolak

ResistContrast ND ND ND

PAG quantum yieldProtecting groupMolecular size…

TBD

CoatingUniformity ND ND ND Casting solvent

… < 2.0nm @ 300mm

EUV Resist Criteria

New chemical design for EUV resist should be necessary.


Polymer Resist Performance

32.5 nm 1:135 nm 1:1 30 nm 1:137.5 nm 1:1

CD: 31nm LWR 3σ: 4.3nm

CD: 32.5nm LWR 3σ: 4.3nm

CD: 28nm LWR 3σ: 5nm

CD: 25nm LWR 3σ: 9nm

Dose : 18mJ/cmDose : 18mJ/cm22

MET@BerkeleyMET@Berkeley

Courtesy of collaboration company

Evaluation conditionsEvaluation conditionsResist thicknessResist thickness : 80nm: 80nmSoft bake/PEBSoft bake/PEB : 100C/110C: 100C/110C--90s90sExposureExposure : MET (Y: MET (Y--monopole) monopole) DevelopmentDevelopment : TMAH 2.38% 60s: TMAH 2.38% 60s

Outgas: 1.35*E+13 molecules/cm2 @ Wisconsin


Ariel imageAcid conc.Acid diff. lengthProtecting group conc.Molecular size

* 0.36* 22.25* 0.36* 22.25* 0.36

H. Fukuda: Jpn. J. Appl. Phys., 42 (2003) 3748.

90 nm hp 32 nm hp

20 40 60 80 100

A

H

B

G

CD size (nm)

Nor

mal

ized

CD

EF

CD

Diff. length

Acid conc.

Mol. size

A B C D E G H

1/K 1/K 1/K 1/K 1/K 1/K 1/K

1 1/K 1/K 1 1

1

1/K 1/K

K3

1/K

K3

1/K

1

90nm hp 32nm hp

GF

F

1/K

1/K

E1 1 1

1 1 1

K3

1

K3

1/KE

Acid concentration (quantum yield)

Diffusion control

Molecular size (also aggregation)

A

9090nm hp nm hp 32nm hp32nm hp

How achieve to LWR spec.?


Mimic measurement of diffusion length

Baking (110C-90s)= diffusion to upper film

2.38%TMAH development (30s),then measurement

Put non-exposure resist film on

Resist (non-exposure)

Upper layer: Capturing layer (Resist formulation, non-exposure)　 Sample-A0 / A1 / A2 / A3 / Sample-A4

Quencher loading levelQuencher loading levelLowLow HighHigh

Generated acid in film

Polymer + PAG

EB

S O3S CF3

Lower layer: Generated acid layer (Polymer + PAG only)


LWR improvement (Quencher loading level)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

50 75 100 125 150 175 200

Normalized Acid Difusion Length (A)

LWR

(nm

)@10

0nm

LS

0

2

4

6

8

10

12

14

16

18

20

Que

nche

r lo

adin

g (w

t%)

Quencher

LWR

A0: 11uC/cm2

168A12.8nm

A1: 15uC/cm2

151A9.6nm

A2: 30uC/cm2

133A7.2nm

A3: 60uC/cm2

113A6.8nm

A4: 150uC/cm2

81A6.5nm

When quencher loading level is increased, normalized acid diffusion length is shorter.In case of normalized acid diffusion length is becoming shorter, the value of LWR is going down.Although, resolution capability of high quencher loading sample shows better.

A0: 11uC/m2 A1: 15uC/m2 A2: 30uC/m2 A3: 60uC/m2

100nm

60nm

70nm


Investigation of Resolution & LER

Non protecting

1 part protecting

2 parts protecting4 parts protecting

Crude Platform(non to 4 parts protecting groups mixture)

Purifying Platform(only 2 parts protecting group)

3 parts protecting

Crude Platform(non to 4 parts protecting groups mixture)

Purifying Platform(only 2 parts protecting group)

Resolution, LERPurifying Platform >>> Crude Platform

H3C

OR

CH3

CH3

OR

CH3

OR

OR

CH3

H3C

CH3

RO

CH3

RO

H2C O

OR : or H

Protecting group

Platform

Molecular resist material without no distribution of the protecting groups

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1

21

41

61

81

101

121

141

161

181

201

221

241

261

281

301

321

341

361

381

401

421

441

461

481

Mass Number

Par

tial

Pre

ssure

Dis

plac

em

ent (P

a/s)

50nm hp, Exposure dose; 12mJ/cm2

LER = 4.2nm Inspection area; 2umResolution; 28nm

EUV Process TechnologyEUV Process Technology

Poster Session on October 16, 2006 (tonight)“Distribution control of protecting groups and its effect on LER for EUV molecular resist”Daiju Shiono et al. (TOK)


Standard CAR Scissor CAR (Main Chain Cleavage CAR)

After cleaved polymer main chain, the final size of materials should be smaller in order to obtain better resolution.

Resolution improvement


Photo Speed and Resolution

S. Tagawa et al., Jpn. J. Appl. Phys. 43 (2004) L848 for PHSS. Tagawa et al., J. Vac. Sci. Technol. B 22 (2004) 3522 for adamanthoxyethyl

S. Tagawa et al., Jpn. J. Appl. Phys. 44 (2005) 5836 for the other protecting groups

The protecting group and protecting ratio can contribute to acid quantum yield, and have significant effect on resolution capability and photo speed.

0.50.60.70.80.91.01.11.21.31.41.5

0 10 20 30 40 50Protection ratio (%)

Rel

ativ

e ac

id y

ield tert-butyl

adamanthoxyethylnaphthoxylethylcyclohethoxyethylethoxyethyltert-buthoxyethyl


1.1 mJ/cm22.84 x 10-6

3.8 mJ/cm21.28 x 10-6

PAG

ND

3.05 x 10-6

Total pressure displacement (Pa)

3.1 mJ/cm2

2.0 mJ/cm2

Photo Speed@Eth

PAG structure studyPAG structure study Protecting Group dependencyProtecting Group dependency

1 x 10~-9

3 x 10-8tert-Bu

EE

Protecting Group

3 x 10-6

Total pressure displacement (Pa)

S+

O2S CF2

CF2

CF2O2S

-N

S+ C4F9SO3-

S+

R

-N

O2S CF2

CF2

CF2O2S

S+

R

-SO3F9C4

H. Hada, et al., J. Photopolym. Sci. Technol. 18 (2005) 475

H. Hada, et al., SPIE, 5374 (2004), 686

Low Outgas


State-of-the-art Polymer Resist

L44P88

CD: 44.6nmLWR:5.3nmLER: 5.0nm




CD: 29.0nmLWR: 6.3nmLER: 6.6nm

L40P80

Dose : 12mJ/cmDose : 12mJ/cm22

MET@BerkeleyMET@Berkeley


Evaluation conditionsEvaluation conditionsResist thicknessResist thickness : 80nm: 80nmDevelopmentDevelopment : TMAH 2.38% 60s: TMAH 2.38% 60s

Outgas: 5.2*E+12 molecules/cm2 @ Wisconsin

L36P72 L32P64

L28P56


centre + 50nm


+ 100nm + 150nm





State-of-the-art Polymer Resist

Focus Latitude @ 28nm LSDose : 12mJ/cmDose : 12mJ/cm22


Summary

The acid concentration related to quantum yield, diffusion control

and molecular size based on aggregation concern are key words in

order to achieve aggressive specification on EUV Lithographic

generation.

The state-of-the-art TOK EUV resist which is based on polymer

type shows 28nm L/S resolution, photo speed: <15mJ/cm2, outgas:

5.2*E+12 molecules/cm2 , and LWR/LER: 6.3nm / 6.6nm respectively.

It is absolutely necessary to make much closer collaboration and

discussion among exposure tool vendor, source, mask, optical

and materials, so on to realize EUV lithography generation on time.


Acknowledgments

Author would like to thank SEMATECH and collaboration companies

for the EUV exposure opportunities provided for the experiments.

Author is likewise grateful to Tagawa Lab. at OSAKA University for

their valuable suggestion.

Author would like to express sincere thanks to ASET for their

numerous cooperation.

The work of EUV low molecular resist was supported by the New

Energy and Industrial Technology Development Organization (NEDO)

under the management of the Key Technology Research Promotion

Program.

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