RAFT Technology for the Production of Advanced Photoresist Polymers
Michael T. Sheehanb, William B. Farnhama, Hiroshi Okazakib, James R. Sounikc, George W. ClarkcaE. I. DuPont de Nemours, Central Research and Development, Wilmington, DE 19880, bDuPont Electronic Polymers L.P., Ingleside, Texas 78359, cDuPont Electronic Polymers L.P., Dayton, Ohio, 45418
2
Copyright © 2008 DuPont. All rights reserved.
Design Concept
Produce fully compatible topcoat-less 193 immersion photoresist polymers using Reversible Addition Fragmentation Chain Transfer (RAFT) technology to control polymer architecture and provide top surface hydrophobicity
- Produce a random copolymer of matching commercial 193 nm resistpolymer using RAFT technology
- Attach a hydrophobic block to the active end of the random resist polymer
- Remove the end group
- Solution blend with standard 193 nm photoresists
3
Copyright © 2008 DuPont. All rights reserved.
RAFT Reagent Synthesis
2 C12H25SH + 2 KOt-Bu + 2 CS2 + I2 C12H25SC(S)SSC(S)SC12H25
Step 2 - 4-cyano-4-(dodecylsulfanylthiocarbonyl)sulfanyl pentanoic acid
Step 1 - bis-(dodecylsulfanylthiocarbonyl) disulfide
C12H25SC(S)SSC(S)SC12H25 + 4,4’-azobis(4-cyanopentanoic acid)
2 C12H25SC(S)SC(CH3)(CN)CH2CH2CO2H
Step 3 - methyl 4-cyano-4-(dodecylsulfanylthiocarbonyl)sulfanylpentanoate
C12H25SC(S)SC(CH3)(CN)CH2CH2CO2H + DBU + CH3I
C12H25SC(S)SC(CH3)(CN)CH2CH2CO2CH3
4
Copyright © 2008 DuPont. All rights reserved.
Synthesis of Poly(α-GBLMA/MAdMA/ECPMA)
O
O
MAdMA
O
O O
O
a-GBLMA
OO
ECPMA
+ +RAFT
V601
R=RAFT end group =S SC12H25
S
RAFT = 4-cyano-4 -(dodecylsulfanylthiocarbonyl)sulfanyl pentanoate
O
O
O
O
O
O
*
R
OO
z
Random terpolymerMw = 3330, PD = 1.15
x yn
5
Copyright © 2008 DuPont. All rights reserved.
Synthesis of Poly(α-GBLMA/MAdMA/ECPMA-b-1H,1H,2H,2H-perfluorooctyl methacrylate)
F-Block 1
O
O
O
O
O
O
*
R
OO
z
Random terpolymerMw = 3330, PD = 1.15
x yn
R=RAFT end group =S SC12H25
S
RAFT = 4-cyano-4 -(dodecylsulfanylthiocarbonyl)sulfanyl pentanoate
+
FF
FF F
F
FF
FF
F FF
O O
C6-Z
Mw = 4981; Mn = 4251; PD = 1.17Block coplymer
OO
FF
F FFF
F F
F F
FFF
R
b
O
OO
O
O
O
*
OO
zx yn
6
Copyright © 2008 DuPont. All rights reserved.
Reduction of trithiocarbonate end group from Poly(α-GBLMA/MAdMA/ECPMA)-b-(1H,1H,2H,2H-perfluorooctyl methacrylate)
F-Block 1 with RAFT end group F-Block 1 with RAFT end group removed
R=RAFT end group =S SC12H25
S
R3NH H2PO2
radical initiator
OO
FF
F FFF
F F
F F
FFF
H
b
O
OO
O
O
O
*
OO
zx yn
Mw = 4981; Mn = 4251; PD = 1.17Block coplymer
OO
FF
F FFF
F F
F F
FFF
R
b
O
OO
O
O
O
*
OO
zx yn
7
Copyright © 2008 DuPont. All rights reserved.
Preparation of blends of 193 nm resist copolymer with fluorinated block copolymer additive
Blends of F-Block 1 with commercial random Poly(α-GBLMA/MAdMA/ECPMA) with Mw of ~ 8,000 Mw and PD of 1.2 were produced in the following ratios (1:2, 1:4, 1:9, 1:29, 1:100, 1:199) in PGMEA/EL (2:1) as 12 wt. % solutions and spun on Si wafers. Film were annealed during post apply bake to allow alignment of the F-Block portion of the polymer at or near the surface of the resist. Contact angles are shown below.
Weight Fraction Block Copolymer (F-Block 1)
Cont
act
Ang
le (
degr
ees)
1.00.80.60.40.20.0
120
110
100
90
80
70
60
50
Variableadvancingreceding
118120120120119
109
102
80 80828384
87
73
81
54
Advancing and Receding Water Contact Angles - (F-Block 1) in 193 terpolymer
8
Copyright © 2008 DuPont. All rights reserved.
Conceptual drawing of F-Block 1 alignment in resist
wafer surface
photoresist surface/water interface
OO
OO
OO
*
*
O
O
xy
zn
OO
OO
OO
*
*
O
O
xy
zn
OO
OO
OO
*
*
O
O
xy
zn
OO
OO
OO
*
*
O
O
xy
zn
OO
OO
OO
*
*
O
O
xy
zn
OO F
FFFFFF
FF
F FFF
H b
OO
OO
OO
*
O
O
zx
yn
OO F
FFFFFF
FF
F FFF
H b
OO
OO
OO
*
O
O
zx
yn
hydrophobic surface
9
Copyright © 2008 DuPont. All rights reserved.
1 wt.% (F-block 2) in a commercial 193 nm resist
31 mJ/cm2 32 mJ/cm2 33 mJ/cm2 34 mJ/cm2 35 mJ/cm2 36 mJ/cm2 37 mJ/cm2 38 mJ/cm2 39 mJ/cm2 40 mJ/cm2
-0.5 μm -0.4 μm -0.3 μm -0.2 μm -0.1 μm 0.0 μm 0.1 μm 0.2 μm 0.3 μm 0.4 μm
Mask CD 100 Mask CD 110 Mask CD 120 Mask CD 130 Mask CD 140 Mask CD 150
137.0 122.4 122.7 123.9 126.7 131.9
120 nm L/S @ best focus
120 nm L/S @ 34.0 mJ/cm2
Linearity @ 34.0 mJ/cm2
10
Copyright © 2008 DuPont. All rights reserved.
3 wt.% (F-block 2) in a commercial 193 nm resist
28 mJ/cm2 29 mJ/cm2 30 mJ/cm2 31 mJ/cm2 32 mJ/cm2 33 mJ/cm2 34 mJ/cm2 35 mJ/cm2 36 mJ/cm2 37 mJ/cm2
-0.5 μm -0.4 μm -0.3 μm -0.2 μm -0.1 μm 0.0 μm 0.1 μm 0.2 μm 0.3 μm 0.4 μm 0.5 μm
120 nm L/S @ best focus
120 nm L/S @ 32.0 mJ/cm2
Linearity @ 32.0 mJ/cm2
Mask CD 100 Mask CD 110 Mask CD 120 Mask CD 130 Mask CD 140 Mask CD 150
139.2 125.8 124.8 125.1 127.2 133.7
11
Copyright © 2008 DuPont. All rights reserved.
5 wt.% (F-block 2) in a commercial 193 nm resist
28 mJ/cm2 29 mJ/cm2 30 mJ/cm2 31 mJ/cm2 32 mJ/cm2 33 mJ/cm2 34 mJ/cm2 35 mJ/cm2 36 mJ/cm2 37 mJ/cm2
-0.4 μm -0.3 μm -0.2 μm -0.1 μm 0.0 μm 0.1 μm 0.2μm 0.3 μm 0.4 μm
Mask CD 100 Mask CD 110 Mask CD 120 Mask CD 130 Mask CD 140 Mask CD 150
120 nm L/S @ best focus
120 nm L/S @ 31.0 mJ/cm2
Linearity @ 31.0 mJ/cm2
137.6 135.1 118.1 118.0 120.9 129.9
12
Copyright © 2008 DuPont. All rights reserved.
Results and discussions
Customized F-containing block copolymer can be synthesized via RAFT technology to allow for full compatibility with commercial 193 nm polymers resulting in a topcoat-less 193 immersion photoresist
The F-block copolymer migrates to the air-solid interface and provides a hydrophobic surface. The A-block of each polymer chain provides compatibility with the main resist polymer and enables development of exposed area
Further optimization will involve refined selection of the fluoromonomer and size of the fluoropolymer block to achieve thedesired advancing and receding contact angles
13
Copyright © 2008 DuPont. All rights reserved.
Acknowledgements and References
ACKNOWLEDGEMENTSThe authors would like to acknowledge the contributions of CSIRO in the development of RAFT technology. We would also like to acknowledge JSR Micro for the microlithography and SEMs.
REFERENCES[1] Wei, Y. et al., "Selection and evaluation of developer-soluble topcoat for 193-nm immersion lithography," Proc. SPIE 6153, 6153-71, (2006)[2] Lee, T.Y., et al., "Polymers with well-controlled molecular weight for DUV/VUV lithography," Proc. SPIE 5039, 548-557(2003)[3] Kim, Sang Soo et al, "Modified polymer architecture for immersion lithography," Proc. SPIE 6519, 65191W-1, (2007)[4] Moad, G., Rizzardo, E., Thang, S. H., "Living radical polymerization by RAFT process," Australian Journal of Chemistry 58(6), 379-410 (2005)[5] Black, C.T., et al, "Polymer self assembly in semiconductor microelectronics," IBM J. Res. & Dev. 51, No. 5., (605-632), (2007) [6] Chiefari, J., Chong, Y.K., Ercole, F., Krstina, J., Jeffery, J., Le, T., Mayadunne Roshan,T.A., Meijs, G.F., Moad, C. L., Moad, G., Rizzardo, E., Thang,
S.H., "Living free-radical polymerization by reversible addition-fragmentation chain transfer: the RAFT process," Macromolecules 31(16), 5559-5562 (1998)
[7] Mayadunne, R.T.A., E. Rizzardo, J. Chiefari, J. Krstina, G. Moad, A. Postma, S. H. Thang, "Living polymers by the use of trithiocarbonates as reversible addition-fragmentation chain transfer (RAFT) agents. ABA triblock copolymers by radical polymerization in two steps," Macromolecules 33(2), 243-245 (2000)
[8] Moad, G., Chefari, J., Chong, Y.K., Krstina, J., Mayadunne, R.T.A, Postma, A., Rizzardo, E., Thang, S.H., "Living free radical polymerization with reversible addition-fragmentation chain transfer (the life of RAFT)," Polymer International 49(9), 993-1001 (2000)
[9] Chong, Y.K., Le, T.P.T., Moad, G., Rizzardo, E., Thang, S.H.,"A more versatile route to block copolymers and other polymer of complex architecture by living radical polymerization: the RAFT process," Macromolecules 32(6), 2071-2074 (1999)
[10] Mayadunne, R.T.A., Rizzardo, E., Chiefari, J., Chong, Y.K., Moad, G., Thang, S.H., " Living radical polymerization with reversible addition-fragmentation chain transfer (RAFT polymerization) using dithiocarbamates as chain transfer agents," Macromolecules 32(21), 6977-6980 (1999)
[11] Moad, G., Chong, Y., Postma, A., Rizzardo, E., Thang, S., "Advances in RAFT polymerization: the synthesis of polymers with defined end-groups," Polymer 46, 8458-8468 (2005)
[12] Chong, Y., Moad, G., Rizzardo, E., Thang S., "Thiocarbonylthio end group removal from RAFT-synthesized polymers by radical-induced reduction," Macromolecules 40, 4446-4455 (2007)
[13] Farnham, W. B., Fryd, M., Moad, G., Thang, S.H., Rizzardo, E., “Removing sulfur-containing end groups from vinyl polymer without changing solvent,” PCT Int. Appl. WO 2005113612, (2005)