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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
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