Cornell University

Effect of PAG Location on Resists for Next Generation

LithographiesOber Research Group

Cornell UniversityMaterials Science & Engineering

Ithaca, NY 14853

Cornell University

Development Trends in Microlithography

Architectures

436nm

365nm

248nm

CyclizedRubber

DNQ - Novolak

HS Copolymers

ContactPrinter

75 85 95 05

0.1

1.0

10

Year

Resolution (µm)

193nm

Hydrocarbon Polymers

H3C

H3C

N

CH3

CH3

N X

CH3 CH3

OHOH

OH OH

O O

O

O O

OH

Cornell University

(CH3)4N+OH-

Aqueous Base Dissolution

Positive Chemically Amplified Photoresist Chemistry

0.12µm

0.40µm

OH

O OH

OH

O O

PAG

hv H+

Cornell University

Photoacid Generators - PAGs

I

RSO 3

I

RSO 3

+

I

RSO 3

HI + RSO 3H

+

h?

XH

X

Homolysis

Dissociation

Radical Abstraction / Protonation

Cornell University

Rutherford Backscattering

? Depth resolution ~ 200 A

? RBS spectrum contains information about target’s? mass? concentration ? depth profile

? Most photoacid generators (PAGs) have a self-label such as Sb, I, etc.

PAG

Res is t Lay er

He Ion BeamE (MeV)

Energy SensitiveDetector

4 ++

0

E E

M < M1 2

1 2

E1 E2

Cornell University

0

25

50

75

100

125

150

0 5000 10000 15000 20000 25000

Thickness (Â)

Con

cent

ratio

n (a

.u.)

Exposed SbPAG - experimentalExposed SbPAG - simulatedUnexposed SbPAG - experimentalUnexposed SbPAG - simulated

Diffusion of PAG and Photogenerated Acid

Photogeneratedacid (2)

PAG(1)

120oC/60s

S+ Sb F6-

H Sb F6

h? , ?

(1)

(2)

Cornell University

Photoacid Generator (PAG) Distribution

OH

OO

Si wafer

= PAG

Br

CH 3

CH 3

OSO 2CF 2 CF 2CF 2CF 3

= Matrix

T-topping Closure Footing

Uneven distribution of PAG

Cornell University

Effect of Block Copolymers As Additives

0

10

20

30

40

50

60

-0.2 0 0.2 0.4 0.6 0.8 1 1.2

Normalized film thickness

with bcp

without bcp

THPMA-b-IBMA with and without IBMA-b-MMA additive

C O C O

OO

O

THPMA-b-IBMAwith

C O C O

OO

CH3

MMA-b-IBMA

waf

er

Cornell University

IBM zero thinning resist

5800 A thick films ; PAB -140C/60s PEB - 140C/60s ; Dev. - 0.05 TMAH

with 2 wt% MMA-b-IBMA

Block Copolymers as AdditivesC C

CH3

C

OCH3

O

CH3

C O

O

C CH3H3C

CH3

C

CH3

C O

OH

CH2 CH2 CH2a b c

MMA-tBMA-MAA

Cornell University

O

OC

CH3

CCH2

CD3

O

OC

CD3

CCD2 a bb

Effect of Block Copolymer Additives - SIMS Measurements

I CF3(CF2)3SO3

Photoacid generator

Block copolymeradditive

100

1000

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Thickness (Å)

Con

cent

ratio

n (a

.u.)

Carbon

Deuterium of Block Copolymer Additive

Iodine of PAG with additive

Iodine of PAG without additive

Air-polymer interface

substrate-polymer interface

(5 wt%)

2 wt%

Cornell University

Polymers for Chemically Amplified Photoresists

pKa = 9-10

pKa = 9-10 / pKa = 4-5

pKa = 4-5

pKa = 4-5 / Anhydride

O

O O

OHO

O

OO

CH3O

O OO

O

OHCH3

O OHOH

O

O

OH

O OH

OH

O O

OOO

O O

OOO

O OH

H+

H+

H+

H+

Collaboration with G. Barclay, Shipley

Cornell University

Labeling of Photoacid Generators for RBS

S

SbF6

CF3SO3

I

S

RSO3

N

O

O

OSO2CF3

Self Labeled No Label

Heavy Atoms: Sb (51), As (75), Br (79), I (127)Light Atoms: C (12), N (14), O (16), F (18), S (32)

Cornell University

Br

CH3

CH3

OSO 2CH3

Br

CH3

CH3

OSO 2 CH2CH2CH2CH2CH2CH2 CH2CH3

Br

CH3

CH3

OSO 2CF 2CF2 CF2CF 3

Br

CH3

CH3

OSO 2CF 2CF2 CF2CF 2CF2 CF2CF 2CF3

Br-1

Br-2

Br-3

Br-4

Design of Labeled PAGs for RBS Study

Non Polar Sulfonate EstersIodonium Polar PAGs

H3C CH3

SO 3O

I

I CF3(CF2)7SO3

I

I-1

I-2

I-3

I CF3(CF2)3SO3

I-4

CF3SO3

I - Labeled Br - LabeledCollaboration with G. Barclay, Shipley

Cornell University

Design of Non-Polar Sulfonate Ester PAGs

Br

CH3

CH3

OSO 2

RBS Label Steric Hindeance forThermal Stability

Moiety to InvestigateStructural Effects

• Thermally Stable in Phenolic and Methacrylate Matrices• Photogenerates acid via “Blocked” Photo-Fries

Collaboration with G. Barclay, Shipley

Cornell University

Model Photoresist Matrices

OH OH

O O O OHO

OO O

CH3

248 nm 193 nm

Hydrophilic Hydrophobic

70/30 57/20/23

Collaboration with G. Barclay, Shipley

Cornell University

Distribution of Polar Ionic PAGs in Poly(4-Hydroxystyrene)

H3C CH3

SO 3O

I

I CF3(CF2)7SO3

I

I CF3(CF2)3SO3

CF3SO3

The distribution of Iodonium PAGs is uniform through the depth of the PHS film independentof counter ion

Si Air

IS

OH

Collaboration with G. Barclay, Shipley

Cornell University

Distribution of Polar Ionic PAGs in 193 nm Acrylic Matrices

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

-0.2 0 0.2 0.4 0.6 0.8 1

Normalized film thickness

CF3SO3

CF3(CF2)3SO3

CF3(CF2)7SO3

I CF 3SO3

I CF3(CF2)3SO3

I CF3(CF2)7SO3

Degree of segregation is dependent upon lenght offluoronated counter ion

Collaboration with G. Barclay, Shipley

Cornell University

RBS Spectra of N-Oxy Sulfonate in PHS

OH

N

O

O

OSO2CF3

Heavy Atoms: Sb (51), As (75), Br (79), I (127)Light Atoms: C (12), N (14), O (16), F (18), S (32)

S

Si Air

Collaboration with G. Barclay, Shipley

Cornell University

RBS Spectra of Iodonium Triflate in PHS

OH

CF3SO3

I

Si

Si

Air

Air

Collaboration with G. Barclay, Shipley

Cornell University

Distribution of Non-Polar PAGs in PHS Copolymers

Br

CH 3

CH 3

OSO 2CH3

Br

CH3

CH3

OSO 2CH2CH 2CH2CH 2CH2CH 2CH2CH 3

Br-1

Br-2

Uniform Distribution

Non-uniform Distribution

Br

CH3

CH3

OSO 2CF 2CF 2CF2CF 3Br-3

Phase Separation - Insoluble in Matrix

Br

CH3

CH3

OSO 2CF 2CF 2CF 2CF2CF 2CF 2CF 2CF 3Br-4

OH

O O

70/30

Si Air

Collaboration with G. Barclay, Shipley

Cornell University

0

0.0005

0.001

0.0015

0.002

-0.2 0 0.2 0.4 0.6 0.8 1 1.2

Normalized film thickness

PAG

con

cent

ratio

n, a

tom

ic %

c8h17c4f9c8f17

waf

er

air

Distribution of Non-Polar PAGs in Model 193 Matrices

Br OSO2(CF2)7CF3

CH3

CH3

Br OSO2(CF2)3CF3

CH3

CH3

Br OSO2(CH2)3CH3

CH3

CH3

c8h17

c4f9

c8f17

O OHO

OO O

CH3

MatrixCollaboration with G. Barclay, Shipley

Cornell University

Br

CH3

CH3

OSO 2CF 2CF 2CF 2CF2CF 2CF 2CF 2CF 3Br-4

O OHO

OO O

Matrix

Distribution of Non-Polar PAGs in Model 193 Matrices

IS

AirSi

Collaboration with G. Barclay, Shipley

Cornell University

Comparison of PAG Distribution Different Resist Matrices

0

0.0005

0.001

0.0015

0.002

0.0025

-0.2 0 0.2 0.4 0.6 0.8 1 1.2

Normalized film thickness

PHS-tBA

IBOMA-MMA-tBMA

Br OSO2(CF2)3CF3

CH3

CH3

O OHO

OO O

CH3

OH

O O

Non PolarSulfonatePAG

Collaboration with G. Barclay, Shipley

Cornell University

400

500

600

700

800

900

1000

0 50 100 150 200 250 300 350Time (A sec)

0

2000

4000

6000

8000

1 104

1.2 104

0 50 100 150 200 250 300 350Time (Sec)

OH

O O

70/30

Dissolution Behavior

Incident Light

Photoresist

Substrate

Collaboration with G. Barclay, Shipley

Cornell University

Dissolution Behavior of Matrix Containing Model PAG

OH

O OBr

H3C

H3C

F 3CF 2CF 2CF 2CO 2SO

70/30

600

700

800

900

1000

1100

0 1000 2000 3000 4000 5000Time (sec)

0

1000

2000

3000

4000

5000

6000

7000

8000

0 1000 2000 3000 4000 5000Time (sec)

Collaboration with G. Barclay, Shipley