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
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MF07-01 : CL1-1 : PAGPEB Process Latitude
1 min
5 min
75 ºC 90 ºC 105 ºC
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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
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MF07-01 : CL2-4 : PAG
New Resist Aged 7 days Aged 30 days
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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
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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?