NPRLNanoscale Physics Research Laboratory

Fullerene ResistsOptimizing RLS

J. Manyam, R.E. Palmer, A.P.G. RobinsonNanoscale Physics Research Laboratory, The University of Birmingham

M. Manickam, J.A. PreeceSchool of Chemistry, The University of Birmingham

http://nprl.bham.ac.uk

NPRLNanoscale Physics Research Laboratory

* D. Drygiannakis et al, Microelectron. Eng, 84, 1062 (2007)

Dose

LWR

Resolution

PMMA fragment

Dose

LWR

Resolution

Fullerene

Resists for Next Generation LithographyShrinking the RLS Tradeoff

Conventional Polymeric Resist

Simulations indicate that molecular resists may shrink the RLS tradeoff*

Molecular Resist

NPRLNanoscale Physics Research Laboratory

*A.M. Rao, et al, Science, 259, 955 (1993)†T. Tada, et al, Jpn. J. Appl. Phys., 35, L63 (1996)

C60 photopolymerisation was first demonstrated by Rao*. hν

Electron beam resist behaviour was first shown by Tada†.

Insoluble Graphitic Material

e-

Fullerene Resists

NPRLNanoscale Physics Research Laboratory

Advantages of C60 Resist: Very high etch resistanceHigh resolution (< 20 nm)

Very low sensitivity (10 mC/cm2)Coating by vacuum sublimationDisadvantages of C60 Resist:

Improving the C60 Resist:

RR

Derivatise to improve solubility

Fullerene Resists

NPRLNanoscale Physics Research Laboratory

Fullerene Resists

20 nm linewidth

Dose = 30,000 pC/cm at 30 keVPAB = NonePEB = None Develop = 10 s, MCBRinse = 10 s, IPA

NPRLNanoscale Physics Research Laboratory

The Sensitivity Problem

Solution

LMW Resists typically have poor sensitivity - the best fullerene resist sensitivity is ~ 370 µC/cm2.

Chemical Amplification to enhance sensitivity

Unexposed Resist Exposed Resist

PhotoacidGenerator H⊕ ∆T

hν

CA Schematic after: H. Ito, Adv. Polym. Sci., 172, 37 (2005),

NPRLNanoscale Physics Research Laboratory

MF07-01 Resist System

Methanofullerene: MF07-01

Photoacid Generator(mixed triarylsulfonium hexafluroantimonate salts)

+ Epoxy Crosslinker

NPRLNanoscale Physics Research Laboratory

MF07-01 Synthesis

Yield123

MF07-01

%50683735

NPRLNanoscale Physics Research Laboratory

Epoxy Crosslinker

Poly[(phenyl glycidyl ether)-co-formaldehyde]

Poly[(o-cresyl glycidyl ether)-co-formaldehyde]

Name

CL1-1CL1-2CL1-3

CL2-1CL2-2CL2-3CL2-4

~Mn

345570680

5401080870

1270

Epoxies

2.23.63.8

2.74.85.05.4

NPRLNanoscale Physics Research Laboratory

Sensitivity vs Composition

Exposure = 20 keVDevelop = MCB:IPA [1:1]

PAB = 75 ºC for 600 sPEB = 90 °C for 180 s

NPRLNanoscale Physics Research Laboratory

Sensitivity vs Crosslinker

CL1-1

CL1-2

CL1-3

CL2-1

CL2-4CL2-3

CL2-2

Exposure = 20 keVDevelop = MCB:IPA [1:1]

CL

CL1-1CL1-2CL1-3

CL2-1CL2-2CL2-3CL2-4

PAB (ºC/s)

75/30080/600None

None75/60075/60075/600

PEB (ºC/s)

90/18090/180100/60

90/18090/18090/18090/180

NPRLNanoscale Physics Research Laboratory

MF07-01 : CL2-4 : PAG

25 nm Half Pitch

Dose = 140 pC/cmPAB = 75 ºC for 600sPEB = 90 °C for 180 sDev = 10 s, MCB:IPA [1:1]Rinse = None

17 nm Linewidth

Dose = 240 pC/cm at 30 keVPAB = NonePEB = 90 °C for 180 sDev = 10 s, MCB:IPA [1:1]Rinse = 10 s, IPA

NPRLNanoscale Physics Research Laboratory

MF07-01 : CL2-4 : PAG50 nm Half Pitch 35 nm Half Pitch

30 nm Half Pitch 25 nm Half Pitch

NPRLNanoscale Physics Research Laboratory

MF07-01 : CL2-4 : PAG15 nm Sparse Features

NPRLNanoscale Physics Research Laboratory

MF07-01 : CL2-4 : PAGPEB Process Latitude

1 min

5 min

75 ºC 90 ºC 105 ºC

NPRLNanoscale Physics Research Laboratory

MF07-01 : CL2-4 : PAG

18 nm Linewidth

LWR = 2.4(LER ~ 1.7 nm)

NPRLNanoscale Physics Research Laboratory

12 nm Linewidth

Dose = 300 pC/cm at 30 keVPAB = 75 ºC for 600sPEB = 90 °C for 180 sDev = 10 s, MCB:IPA [1:1]Rinse = 10 s, IPA

MF07-01 : CL1-1 : PAG

20 nm Half Pitch

Dose = 140 pC/cmPAB = 75 ºC for 600sPEB = 90 °C for 180 sDev = 10 s, MCB:IPA [1:1]Rinse = None

NPRLNanoscale Physics Research Laboratory

MF07-01 : CL1-1 : PAG

18 nm hp Dense Pattern

NPRLNanoscale Physics Research Laboratory

MF07-01 : CL1-1 : PAGPEB Process Latitude

1 min

5 min

75 ºC 90 ºC 105 ºC

NPRLNanoscale Physics Research Laboratory

All CrosslinkersSparse Line Dose Process Latitude

10

15

20

25

30

35

100 200 300 400 500 600 700

CL0603CL0604CL0609CL0610CL0801CL0802

Line

wid

th (n

m)

Line dose (pC/cm)

CL1-1CL1-2CL2-1CL2-4CL2-3CL2-2

NPRLNanoscale Physics Research Laboratory

Etch Durability

0

1

2

3

4

SAL601 A B C D E F

PABno PAB

Etc

h re

sist

ance

(res

ist t

o si

licon

)

200 nm pitch Si structures

25 nm half pitch Si structures

Crosslinker CL1-1

CL2-3

CL2-2

CL2-4

CL2-1

CL1-2

CL1-1

SAL601

NPRLNanoscale Physics Research Laboratory

MF07-01 : CL2-4 : PAG

New Resist Aged 7 days Aged 30 days

NPRLNanoscale Physics Research Laboratory

EUV Exposure at PSI

Exposure time at PSI was kindly provided by Intel Corp, (Dr M.J. Leeson), and exposures were done with the assistance of Drs H. Solak, V. Auzelyte and P. Sahoo of the Paul Scherrer Institute

50 nm Half Pitch in CL2-4

NPRLNanoscale Physics Research Laboratory

Line Width RoughnessSparse Resolutions of 12 nm and dense resolutions of 20 nm have been achieved at < 10 µC/cm2 sensitivities. Line width roughness is typically about 4 - 5 nm, but 2.5 nm has been seen under certain circumstances.

Currently studying line width roughness in relation to:

DoseLine widthPitchPEB PAB

PAG ConcentrationPAG TypeBase QuencherCasting SolventDeveloper

DosePitchPEB PABCrosslinker

PAG ConcentrationPAG TypeBase ConcentrationCasting SolventDeveloper

LWR measured with IMEL Demokritos software

NPRLNanoscale Physics Research Laboratory

LWR vs DoseDose (pC/cm)

200 - 290

300 - 390

400 - 490

500 - 590

MF07-01:CL1-1:PAG (1:2:1), PAB 75ºC, 10 m; PEB 90ºC, 3 m

NPRLNanoscale Physics Research Laboratory

CL2-1CL2-2CL2-3CL2-4

2

3

4

5

6

7

8

9

10

100 200 300 400 500 600

Line

Wid

th R

ough

ness

(nm

)

Line Dose (pC/cm)

2

3

4

5

6

7

8

9

10

100 200 300 400 500 600

CL1-1CL1-2

Line

Wid

th R

ough

ness

(nm

)

Line Dose (pC/cm)

LWR vs Dose

PAB 75ºC, 10 mPEB 90ºC, 3 mComposition [1:2:1]Crosslinker Variable

Casting Solvent ChloroformDeveloper MCB:IPA [1:1]Rinse IPAFeature Type Sparse

NPRLNanoscale Physics Research Laboratory

LWR vs Crosslinker

0

2

4

6

8

10

None CL1-1 CL1-2 CL2-1 CL2-2 CL2-3 CL2-4

SparseDense

Line

Wid

th R

ough

ness

(nm

)

Crosslinker

PAB 75ºC, 10 mPEB 90ºC, 3 mComposition [1:2:1]Crosslinker VariableCasting Solvent ChloroformDeveloper MCB:IPA [1:1]Rinse IPADose Optimal

NPRLNanoscale Physics Research Laboratory

LWR vs Pitch

2

3

4

5

6

7

8

9

10

50 100 150 200 250 300 350 400 450

200pC/cm240pC/cm280pC/cm320pC/cm

Line

Wid

th R

ough

ness

(nm

)

Pitch (nm)

10

15

20

25

30

50 100 150 200 250 300 350 400 450

200pC/cm240pC/cm280pC/cm320pC/cm

Line

Wid

th (n

m)

Pitch (nm)

PAB 75ºC, 10 mPEB 90ºC, 3 mComposition [1:2:1]Crosslinker CL1-1

Casting Solvent ChloroformDeveloper MCB:IPA [1:1]Rinse IPAFeature Type Variable

NPRLNanoscale Physics Research Laboratory

2

3

4

5

6

7

8

9

10

100 150 200 250 300 350 400 450 500

75C 5min90C 5min105C 5min

Line

Wid

th R

ough

ness

(nm

)

Line Dose (pC/cm)

2

3

4

5

6

7

8

9

10

100 150 200 250 300 350 400 450 500

75C 1min90C 1min105C 1min

Line

Wid

th R

ough

ness

(nm

)

Line Dose (pC/cm)

LWR vs PEB

PAB 75ºC, 10 mPEB VariableComposition [1:2:1]Crosslinker CL2-4

Casting Solvent ChloroformDeveloper MCB:IPA [1:1]Rinse IPAFeature Type Sparse

NPRLNanoscale Physics Research Laboratory

LWR vs PAG Concentration

10

15

20

25

30

100 1000

14 wt%20 wt%25 wt%29 wt%33 wt%37 wt%40 wt%

Line

Wid

th (n

m)

Line Dose (pC/cm)

2

3

4

5

6

7

8

9

10

100 1000

14 wt%20 wt%25 wt%29 wt%33 wt%37 wt%40 wt%

Line

Wid

th R

ough

ness

(nm

)

Line Dose (pC/cm)

PAB 75ºC, 10 mPEB 90ºC, 3 mComposition VariableCrosslinker CL1-1

Casting Solvent ChloroformDeveloper MCB:IPA [1:1]Rinse IPAFeature Type Sparse

NPRLNanoscale Physics Research Laboratory

10

15

20

25

30

35

400 600 800 1000 1200 1400 1600

1.0 wt%2.5 wt%5.0 wt%7.5 wt%10 wt%

Line

Wid

th (n

m)

Line Dose (pC/cm)

2

3

4

5

6

7

8

9

10

400 600 800 1000 1200 1400 1600

1.0 wt%2.5 wt%5.0 wt%7.5 wt%10 wt%

Line

Wid

th R

ough

ness

(nm

)

Line Dose (pC/cm)

LWR vs Base Concentration

PAB 75ºC, 10 mPEB 90ºC, 3 mComposition [1:2:1]Crosslinker CL-1-1

Casting Solvent ChloroformDeveloper MCB:IPA [1:1]Rinse IPAFeature Type Sparse

NPRLNanoscale Physics Research Laboratory

LWR vs Casting Solvent

2

3

4

5

6

7

8

9

10

100 200 300 400 500 600

AnisolePGMEAChloroform

Line

Wid

th R

ough

ness

(nm

)

Line Dose (pC/cm)

10

15

20

25

30

100 200 300 400 500 600

AnisolePGMEAChloroform

Line

Wid

th (n

m)

Line Dose (pC/cm)

PAB 75ºC, 10 mPEB 90ºC, 3 mComposition [1:2:1]Crosslinker CL1-1

Casting Solvent VariableDeveloper MCB:IPA [1:1]Rinse IPAFeature Type Sparse

NPRLNanoscale Physics Research Laboratory

ConclusionsCL2-4: Resolution 17nm (sparse) CL1-1: Resolution 12 nm (sparse)

25 nm (dense) 20 nm (dense)Sensitivity 6 µC/cm2 13 µC/cm2

LWR 4 nm (sparse) 4.3 nm (sparse)7.1 nm (dense) 6.4 nm (dense)

The process latitude is good. Preliminary ageing data indicates that they are stable.

The etch durability is equivalent to commercial novolac resists, and patterns can be transferred with ECR SF6 etching.

LWR Studies are on-going: Increasing dose does not improve LWRPAG level needs to be optimized (more not necessarily better)Some base is beneficial (too much increases LWR) Slow or hot PEB seems beneficialCasting Solvent is importantBest combination: R = 15.3 nm (sparse), LWR = 2.3 nm, S = 600 pC/cm

R = 13.5 nm (sparse), LWR = 2.3 nm, S = 200 pC/cm

NPRLNanoscale Physics Research Laboratory

AcknowledgmentsMr J. Manyam, Ms M-Y. Song, Mr J. Lawton, Mr C. Jones, Dr J. Yin, Dr A. Pulisciano, Dr H Zheng, Dr F.P. Gibbons, Dr H.M. Zaid, Dr J.C. Barnard, Dr A.J. Parker, Dr M.R.C. Hunt, Prof. R.E. Palmer Nanoscale Physics Research Laboratory, University of Birmingham

Dr U. Jonas, Prof. F. DiederichLaboratorium für Organische Chemie, ETH Zentrum, Switzerland

Dr S. Diegoli, Dr M. Manickam, Dr E.J. Shelley, Dr D. Philp, Dr M.T. Allen, Prof. K.D.M. Harris, Prof. J.A. PreeceSchool of Chemistry, The University of Birmingham, UK

Dr E. Tarte, Dr C. Anthony, Dr. J. TengSchool of Engineering, The University of Birmingham, UK

Dr T. Tada, Dr T. KanyamaJoint Research Center for Atom Technology, NAIR, Japan

Dr C. FigguresSowerby Research Centre, BAe Systems, UK

Dr J. Mackevich, Dr R. Brainard, Dr T. Zampini, Dr K. O’ConnellRohm and Haas (Electronic Materials), Marlborough USA

Dr J.H. TortaiCNRS, France

Dr L. RumizSincrotrone Trieste S.C.p.A., Italy

Dr M.J. LeesonIntel Corp

Dr H. Solak, Dr V. Auzelyte, Dr P. SahooPaul Scherrer Institute, Switzerland

more Moore

NPRLNanoscale Physics Research Laboratory

Thank you

Questions?