EUV resist challenges of image collapse, LWR, sensitivity...

EUV resist challenges of image collapse, LWR,

sensitivity, and resolution

James W. ThackerayOctober 17, 2010

Presentation Outline

Resist Material Challenges for EUV TechnologyDow Material ApproachRLS AdvancementPattern Collapse AdvancementFuture Challenges

Critical Challenges for EUV Resists

Challenge Areas to work onFundamental EUV interaction with Resist

MaterialElectron blur, line slimming, negative

resist behavior, acid yieldResolution Polymer-bound PAG, low activation LG,

swelling reductionLWR Polymer-bound PAG, etch trim, rinse,

polymer homogeneityPhotospeed EUV sensitization, higher PAG loading

Etch Resistance Lower Ohnishi parameter approach

Pattern Collapse Lower A/R, UL matched for adhesion, surfactant rinse

Outgassing PAG byproducts from ionization, LG and solvent effects, other species?

Defects HSP solvents, aggregation elimination

Quality Control EUV photospeed

test, EUV chemical signature requirement

11

2

2

3

22

2 4 Acid Diffusion

Substrate

PAG Reaction w/ thermal e-’s<15eV

13.4nm [92eV] source

PAG

80 eV

secondary e-

CA Resist Matrix

5 Deprotection

Sphere

EUV Reaction Mechanism

1. Photon Absorption by Resist Matrix2. Secondary electron generation3. PAG reaction w/ thermal electrons4. Acid Diffusion5. Deprotection Sphere

EUV only

PH + hv (13.4nm)1) [PH] + e-

2)

AG + e- G- + A3)

[PH] [P] + H+

4) G- + H+HG

EUV Sensitization Mechanism: Higher Acid Yield Through sensitization

EUV photons ionize polymer to create 3-4 secondary electronsSecondary electron yield can be increased through increased EUV absorption [ie F-containing monomer] or low ionization potential monomer [ie naphthylmonomer]Acid Yield increase improves latent acid image in resist

50 100 150 200 250

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

0.050

0.055

0.060

SE

Y

Eph

Sa_5 Sa_6 Sa_7 Sa_8

XE081095G

[HFA-containing]

MET-2D

Madey

et al -

Rutgers University

LG

OO

OO

OO

O O OO

F F

FFSO3

S+

ESM

EUV Sensitization Monomer

Photon absorption by a volume in ArF and EUV at 10 mJ/cm2

2, 10 / , 4 /

25328, 2326absorbed absorbed

EUV mJ cm um

n E keV

α =

= =

2, 10 / , 4 /

366528, 2354absorbed absorbed

ArF mJ cm um

n E keV

α =

= =

• About 14x more photons absorbed at ArF than EUV • Average absorbed energy is the same, about 2.3 eV / nm3

x, nm y, nm

depth, nm

ArF

x, nm y, nm

depth, nm

EUV

Biafore, Thackeray et al SPIE 2009

Simulated acid yield: direct photolysis vs. ionization w/scattering13.5 nm, dose = 10 mJ/cm2, B = 4.5 / um, open frame, 0.25 NA, 0.5 sigma

Simulated acid yield: direct photolysis vs. ionization w/scattering13.5 nm, dose = 10 mJ/cm2, B = 4.5 / um, open frame, 0.25 NA, 0.5 sigma

Acid by direct photolysis Acid by ionization and electron scattering

•

An exposure mechanism which considers ionization and electron scattering may explain acid yields and sizing doses observed at EUV

Courtesy John Biafore KLA-

Tencor

INC

0.122Yield = Φ = 1.27Yield = Φ =

7.25

30.27.4

SIZEE mJ

CD nmLWR nm

=

==

15

30.15.4

SIZEE mJ

CD nmLWR nm

=

==

30

29.64.5

SIZEE mJ

CD nmLWR nm

=

==

60

30.43.8

SIZEE mJ

CD nmLWR nm

=

==

• Lowering exposure dose clearly degrades LWR• Simulation using EUV calibrated stochastic resist model

• Photospeed

is adjusted by quencher addition

Simulated Effect of Exposure Dose on Resist LWR13.5 nm, 0.25 NA, 0.5 sigma, 30 nm lines and spaces, PROLITH X3.1.1 stochastic simulator

Simulated Effect of Exposure Dose on Resist LWR13.5 nm, 0.25 NA, 0.5 sigma, 30 nm lines and spaces, PROLITH X3.1.1 stochastic simulator

Courtesy John Biafore, KLA-

Tencor

Genealogy of Methacrylate

platformsMA

XE-081095AJ

XE-081095G

Kinetic study Process DOE

Homogeneity: LWRPolymer: under analysis

JMP DOEPAB/PEB etc

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

0.080

0 5000 10000 15000 20000 25000Time (sec)

Con

c(m

oles

/L)

M1M2M3M4

XE-100291AH

Low Ea/LWR: 4.3 @28nmPS: 15 mj/cm2

New PAGLWR: 4.4

PS: 16 mj/cm2

XP-6627G 25nm 1:1 @ Es~49mj/cm2

F4-PAG

30nm 1:1 @ Es~7.8mj/cm2

EUV sensitizerXP-6627A

ESM3 (Oct/09) LWR ~5 @ 30nm/Es~13 mj/cm2

Process DOE: XE-081095AJ on Albany eMET

PS: 15 mj/cm2LWR:4.3nm

--+ best process from DOE: 54nm thickness, 100CPAB, 95CPEB

Albany ADT: XE-081095AJ

30nm HP

•

Target 2nm offset to 30nm feature due to typical offset from 9380 to Cross Section

MAResist: 60nm XE081095AJPAB=140°C/90s; PEB=100°C/60sUL: XU081104AA@250Å; 205°C/60sEXP:ADT Albany, NA=0.25; 0.50σMask SEC#2; Subfield SPDR30DEV: TMAH, 30s

13

18

23

28

33

38

43

-0.134

-0.094

-0.054

-0.014

0.026

0.066

0.106

0.146

Defocus(µm)

CD(n

m)

25.00

24.00

23.00

22.00

21.00

20.00

19.00

18.00

17.00

16.00

15.00Target CD

±10%

Resist: 60nm XE081095AJPAB=140°C/90s; PEB=100°C/60sUL: XU081104AA@250Å; 205°C/60sEXP:ADT Albany, NA=0.25; 0.50σMask SEC#2; Subfield SPDR30DEV: TMAH, 30s

Albany ADT: XE-081095AJ

28nm HP

•

Target 2nm offset to 28nm feature due to typical offset from 9380 to Cross Section

XE-100291AH

on Albany eMET

E=16.3mj/cm2, UL=XU-081104, PAB/PEB=120/90

28nm 1:1 26nm 1:1

16.3mJ, 28nm HP

24.8nm, 4.4nm

MA

Pattern Collapse

Main reasons for pattern collapse

Young’s modulus. The mechanical stiffness of the lines is dominated by the Young’s Modulus.−

Mechanical stability of resist lines decreases•

Intrinsic decrease of the modulus towards ultra thin films based

on the intrinsic decrease of Tg

towards thinner films

Unbalanced capillary forces:

-

surface tension of the rinsing liquids1

and s2

different spaces beside the resist lineH and A –

the resist film thickness and the line edge area the contact angle of the rinsing liquid

Adhesion between substrate and resist

HAss

Pi ⎟⎟⎠

⎞⎜⎜⎝

⎛−••=Δ

21

11cos2 θγ

γ

θ

eMET 28nm 1:1 Images

Resist: XE100291AHResist Film Thickness=500ÅPAB=120°C/90s; PEB=90°C/60s

ARC: XU081104AA@250Å; 205°C/60s

EXP: eMET AlbanyNA=0.30; Quad; 0.22σ/ 0.68σMask; Subfield HCleve Lines

DEV: TEL-SMT-30S=TMAH, 30s

14.01mJ 14.84mJ 15.67mJ 16.50mJ 17.33mJ 18.16mJ 18.99mJ

-200nm-100nm

0nm+100nm

+200nm

29.7nm

5.3 LWR

27.5nm

6.1 LWR

26.6nm

7.0 LWR

24.2nm

5.6LWR

22.6m

5.8 LWR

31.3nm

7.2 LWR

28.2nm

8.1 LWR

27.0nm

5.5 LWR

27.9nm

7.2 LWR

26.6nm

6.2 LWR

E-Size ~17.5mJ (CD 26)

ADI LWR=6.5nm

eMET 28nm 1:1 Images


ARC: XU081104AA@250Å; 205°C/60s


DEV: TEL-DOW-30s-R1=TMAH, 30sXE090443B Rinse

13.84mJ 14.66mJ 15.48mJ 16.3mJ 17.12mJ 17.94mJ 18.76mJ

-200nm100nm

0nm+10nm

+200nm

24.8nm

4.4 LWR

E-Size ~16.0mJ (CD 26)

ADI LWR=5.2nm

29.3nm

4.9 LWR

23.2nm

4.3 LWR

21.5nm

4.5LWR

18.4m

3.6 LWR

31.7nm

6.0 LWR

25.8nm

5.1 LWR

29.5nm

6.0 LWR

25.4nm

4.8 LWR

29.1nm

5.9 LWR

CD Process Window

28nm CDXE100370KB

0.0000

0.0050

0.0100

0.0150

0.0200

0.0250

0.0300

0.0350

11.98 µm 11.88 µm 11.78 µm 11.68 µm 11.58 µmFocus(um)

Mea

sure

men

t 14.01 mJ14.84 mJ15.67 mJ16.5 mJ17.33 mJ18.16 mJ18.99 mJ

28nm CDXE100291AH

0.00000.00500.01000.01500.02000.02500.03000.0350

12.4 µm 12.3 µm 12.2 µm 12.1 µm 12 µm

Focus(um)

Mea

sure

men

t

13.84 mJ14.66 mJ15.48 mJ16.3 mJ17.12 mJ17.94 mJ18.76 mJ


ARC: XU081104AA@250Å; 205°C/60s




ARC: XU081104AA@250Å; 205°C/60s



LWR Process Window


ARC: XU081104AA@250Å; 205°C/60s




ARC: XU081104AA@250Å; 205°C/60s



28nm LWRXE100291AH

0.0000

0.0020

0.0040

0.0060

0.0080

0.0100

0.0120

12.4 µm 12.3 µm 12.2 µm 12.1 µm 12 µm

Focus(um)

Mea

sure

men

t

15.48 mJ16.3 mJPoly. (15.48 mJ)

28nm LWRXE100370KB

0.0000

0.0020

0.0040

0.0060

0.0080

0.0100

0.0120

11.98 µm 11.88 µm 11.78 µm 11.68 µm 11.58 µm

Focus(um)

Mea

sure

men

t

17.33 mJ18.16 mJPoly. (18.16 mJ)

SEMATECH eMET

: Improved Resolution Polymer Bound PAG

C-Dipole 22nm hp

22nm hpQuadrapole

Continuous improvement in resolution•

Low Activation Resists with Reduced swelling

1820222426283032

2009,1Q

2009,2Q

2009,3Q

2009,4Q

2010,1Q

Date

Res

olut

ion,

nm

Polymer-boundPAG

C Dipole 20nm hp

There are many important parameters to optimize for EUV ResistRLS improvement:

•

Polymer-bound PAG•

High EUV quantum yield and High EUV absorption•

Developer contrast also important

Pattern Collapse improvement:•

Surfactanated

Rinses help methacrylate

LWR•

Aspect ratios should more realistically be 2:1

EUV access is a critical path to better resists!

Summary

EUV resist challenges of image collapse, LWR, sensitivity...

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