Fluorine-contained photoacid generators (PAGs) and corresponding polymer resists

Article abstract of DOI:10.1016/j.jfluchem.2008.04.014

A new series of fluorinated anionic photoacid generators (PAGs) (F4-MBS-TPS, F4VBzBS-TPS, F4-IBBS-TPS, CF3 MBS-TPS, MTFBS-TPS and VBzTFBS-TPS), and corresponding PAG bound polymeric resists (HS-EA-PAG) based on hydroxystyrene (HOST) and 2-ethyl-2-adamanty

Full text of DOI:10.1016/j.jfluchem.2008.04.014

Journal of Fluorine Chemistry 129 (2008) 607–612
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Fluorine-contained photoacid generators (PAGs) and corresponding
polymer resists
Mingxing Wang a, Wang Yueh b, Kenneth E. Gonsalves a,
*
a Polymer Nanotechnology Laboratory at Center for Optoelectronic and Optical Communications & Department of Chemistry, University of North Carolina,
Charlotte, NC 28223, USA
b Intel Corp., Hillsboro, OR 97124, USA
A R T I C L E I N F O
A B S T R A C T
Article history:
A new series of fluorinated anionic photoacid generators (PAGs) (F4-MBS-TPS, F4VBzBS-TPS, F4-IBBS-
TPS, CF3 MBS-TPS, MTFBS-TPS and VBzTFBS-TPS), and corresponding PAG bound polymeric resists (HS-
EA-PAG) based on hydroxystyrene (HOST) and 2-ethyl-2-adamantyl methacrylate (EA), (GB-EA-PAG)
Received 28 January 2008
Received in revised form 27 April 2008
Accepted 30 April 2008
based on
g-butyrolactone methacrylate (GBLMA) and 2-ethyl-2-adamantyl methacrylate (EA) were
Available online 13 May 2008
prepared and characterized. The acid generating efficiency of PAG bound polymers (HS-EA-PAG) series
was in the range of 54–81%, which agrees well with the electron withdrawing effect of the substituents.
With regard to the referenced F4-PAG bound polymer with 68% acid generating efficiency, and our
previously reported EUVL results of F4-MBS-TPS bound polymer photoresists, these new PAG bound
polymers should be effective resists for 193 nm or EUV lithography.
Keywords:
Fluorinated photoacid generators (PAGs)
Polymer resists
ß 2008 Elsevier B.V. All rights reserved.
1. Introduction
consecutive CF2 units are an environmental hazard [4,5]. On the
other hand, several systems with ionic or non-ionic PAG grafting
The chemically amplified resist (CAR) system has been brought
into the technology of microelectronic devices since it was
proposed by IBM in 1980. The main advantanges of chemically
amplified resists are its high sensitivity and resolution. Generally,
it is composed of protected polymer matrix and a small molecule
photoacid generator (PAG). PAG is one of the critical components in
CAR system, it generates acid and catalyzes important chemical
transformations within the film, such as deprotection, polymer-
ization initiation, chain scission, or cross-linking process [1]. The
traditional PAG blended CAR system has inherent incompatibility
that can lead to PAG phase separation, PAG aggregation, non-
uniform initial PAG and photoacid distribution, as well as acid
migration during the post-exposure baking (PEB) processes. At the
critical patterning challenge down to 32 nm or below, these
problems ultimately create a tradeoff between achieving the
desired characteristics of high resolution, high sensitivity, and low
line edge roughness through formulation changes [2]. To overcome
these problems, some new perfluoroalkanesulfonate (PFAS) blend
PAGs that provide strong acid, good lithographic performance, and
process compatibility were developed [1,3]. However, it has been
reported that the PFAS compounds with more than four
into the main-chain of polymer have been reported [6–12]. The
incorporation of anionic PAG units into the main chain of the
hydroxystyrene and 2-ethyl-2-adamantyl methacrylate-based
polymers showed improved EUV lithographic performance, such
as high PAG loading, improved resolution, lower outgassing, and
lower line edge roughness (LER) than corresponding cationic PAG
bound polymer or PAG blend polymer resists [9–13]. Fluorinated
compounds show special properties and application of optical-
electronic, thermochemistry, biomedical and nanotechnology,
because of their highest electronegativity and smaller atomic
radius [14,15]. Herein we report a series of fluorinated anionic
vinyl monomer PAGs and corresponding photoresists incorporat-
ing them in the main chain of the polymer (Figs. 1 and 2). Fig. 2 also
outlines the anticipated advantages of polymer microstructures
incorporating PAGs in the resist backbone.
2. Experimental Section
2.1. Materials
m-Trifluoromethylphenol, 2,3,5,6-tetrafluoro-phenol, 2,20-azo-
bisisobutyronitrile (AIBN), 4-bromo-1,1,2-trifluoro-1-butene,
methacryloyl chloride, N,N-dimethylformide (DMF), p-chloro-
methylstyrene were purchased from Aldrich. Trifluoroacetic acid
(TFA) and trifluoroacetic anhydride (TFAA), and acetoxystyrene
* Corresponding author. Tel.: +1 704 687 8293; fax: +1 704 687 8241.
E-mail address: kegonsal@uncc.edu (K.E. Gonsalves).
0022-1139/$ – see front matter ß 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2008.04.014

608
M. Wang et al. / Journal of Fluorine Chemistry 129 (2008) 607–612
Fig. 1. Photoacid generator (PAG) structures.
were purchased from Tokyo Kasei Kogyo Co., Ltd., Japan.
Methacrylic acid and isobutyric acid were purchased from ACROS
ORGANICS. Triphenylsulfonium chloride 50% aqueous solution was
purchased from City Chemical LLC, USA. 2-Ethyl-2-adamantyl-
ment, Hi-Res TGA 2950 Thermogravimetric Analyzer 7, and
differential scanning calorimetry (DSC 2920) under a nitrogen
atmosphere at a heating rate of 10 8C/min. TGA was used to
determine the decomposition temperature (Td, at 5% weight loss).
methacrylate (EAMA) and g-butyrolactone methacrylate (GBLMA)
were supplied by AZ Electronic Materials Ltd. 2-Thienylmethyl
methacrylate (TMM) was prepared according to the reported
method [16]. All chemicals and solvents were used without further
purification unless otherwise noted. Tetrahydrofuran (THF) and
acetonitrile were dried (over sodium, calcium hydride) before use.
Hydroxystrene (HOST) was prepared by the hydrolysis of acetic
acid 4-vinylphenyl ester.
2.3. Synthesis of photoacid generators
2.3.1. F4-MBS-TPS, F4-IBBS-TPS and F4-VBzBS-TPS
Triphenylsulfonium salt 4-(methacryloxy)-2,3,5,6-tetrafluoro ben-
zenesulfonate (F4-MBS-TPS, Scheme 1) [7,8]: First, 4-hydroxy-
2,3,5,6-tetrafluoro benzenesulfonate was prepared as per litera-
ture method [17]. This was then reacted with methacrylic acid in
trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) as
media, under a nitrogen atmosphere overnight, to get sodium 4-
(methacryloxy)-2,3,5,6-tetrafluorobenzenesulfonate(F4-MBS-Na)
in 97% yield, characterized by 1H NMR (25 8C, ppm)
6.13 (s, 1H); 2.06 (s, 3H), 19F NMR (25 8C, ppm, ext. CF3COOH):
ꢀ152.35 (m, 2F); ꢀ137.68 (m, 2F). Then it was reacted with
triphenylsulfonium chloride 50% aqueous solution in water, at
room temperature overnight. The product was refined with
dichloromethane and hexane, F4-MBS-TPS was obtained in 90%
yield as a colorless crystal, mp: 57–59 8C. 1H NMR (500 MHz,
2.2. Characterization
The NMR was performed on a JEOL500 spectrometer with
DMSO-d6 or CDCl3 and TMS as the solvent and internal standard,
respectively. Elemental analyses were performed at Atlantic
Microlab Inc., Atlanta, GA. UV–vis absorption spectra were
obtained on a Varian CARY 300 Bio UV-Visible spectrophotometer.
Gel permeation chromatography (GPC, Waters Breeze software)
was performed with THF as the eluent. The molecular weights of
polymers were calculated with respect to polystyrene as narrow
Mw standards. Thermal analysis was performed on a TA instru-
d6.45 (s, 1H);
d
DMSO-d6,
d
) 7.42–7.92 (m, 15H); 6.45 (s, 1H); 6.12 (s, 1H); 2.03 (s,
) 162.8, 141.0, 136.3, 134.5,
3H). 13C NMR (125 MHz, DMSO-d6,
d
Fig. 2. Design of polymer microstructures for EUV lithography.

M. Wang et al. / Journal of Fluorine Chemistry 129 (2008) 607–612
609
Scheme 1. Synthetic scheme of F4-MBS-TPS, F4-IBBS-TPS and F4-VBzBS-TPS.
133.1, 132.5, 131.3, 130.4, 128.7, 125.4, 124.2 and 17.9. 19F NMR
(470 MHz, DMSO-d6,
(m, 2F). Anal. Calcd for C28H20F4O5S2: C, 58.33; H, 3.50; F, 13.18; O,
13.87; S, 11.12. Found: C, 58.39; H, 3.34; F, 12.85; O, 13.83; S,
11.06.
Triphenylsulfonium salt 4-(isobutyloxy)-2,3,5,6-tetrafluorobenze-
nesulfonate (F4-IBBS-TPS) was prepared by a method similar to F4-
MBS-TPS using isobutyric acid instead of methacrylic acid in 78.0%
yield as a colorless crystal, mp: 62–64 8C. 1H NMR (500 MHz,
DMSO-d6,
1H); 5.86 (d, J = 17.8 Hz, 1H); 5.27 (d,s J = 11.2.0 Hz, 3H). 13C NMR
(125 MHz, DMSO-d6, ): 146.1, 144.1, 142.2, 141.7, 141.0, 139.2,
d): 7.42–7.92 (m, 19H); 6.73 (dd, J = 11.2 and 17.8 Hz,
d
, ext. CF3COOH): ꢀ152.55 (m, 2F); ꢀ137.62
d
137.6, 136.2, 135.2, 134.4, 132.5, 131.4, 130.4, 128.9, 126.3, 125.2,
124.2, 121.3, 115.1, and 75.8. 19F NMR (470 MHz, DMSO-d6,
CF3COOH): ꢀ156.55 (m, 2F); ꢀ139.82 (m, 2F).
d, ext.
2.3.2. Triphenylsulfonium salt 2-(methacryloxy)4-trifluoromethyl
benzenesulfonate (E) and triphenylsulfonium salt 4-(methacryloxy)2-
trifluoromethyl benzenesulfonate (F) (CF3-MBS-TPS)
Triphenylsulfonium salt 2-(methacryloxy)4-trifluoromethyl
benzenesulfonate (E) and triphenylsulfonium salt 4-(methacry-
loxy)2-trifluoromethyl benzenesulfonate (F) (CF3-MBS-TPS) were
prepared as shown in Scheme 2 [19,20]. 2-Hydroxy-4-trifluor-
omethylbenzenesulfonic acid (A) and 4-hydroxy-2-trifluoro-
methylbenzenesulfonic acid (B) were prepared as per literature
method, yield 63% (A:B = 7:3), characterized by 1H NMR (500 MHz,
DMSO-d6,
1.26 (s, 6H). 13C NMR (125 MHz, DMSO-d6,
134.3, 132.4, 131.3, 131.0, 128.6, 125.1, 124.1, 33.1 and 18.4. 19F
NMR (470 MHz, DMSO-d6,
d
): 7.42–7.95 (m, 15H); 3.02 (heptet, J = 7.2 Hz, 1H) and
d
): 172.9, 140.9, 136.2,
d
, ext. CF3COOH): ꢀ153.82 (m, 2F);
ꢀ138.73 (m, 2F). Anal. Calcd for C28H22F4O5S2: C, 58.12; H, 3.83; F,
13.13; O, 13.83; S, 11.08. Found: C, 58.34; H, 3.56; F, 12.79; O,
13.54; S, 10.83.
Triphenylsulfonium salt 4-(vinyl benzyloxy)-2,3,5,6-tetrafluoro
benzenesulfonate (F4-VBzBS-TPS, scheme 1) [18]: P-Chloromethyl-
styrene (20 mmol, 3.04 g) in 10 ml acetone was added dropwise to
the aqueous solution of sodium 4-hydroxy-2,3,5,6-tetrafluoro
benzenesulfonate (22 mmol, 5.90 g) under nitrogen at reflux over
24 h. After cooling to room temperature, the solid was filtered and
washed with acetone, and dried under high vacuum overnight to
give pure product sodium salt, 4-(vinyl benzyloxy)-2,3,5,6-
tetrafluoro benzenesulfonate (F4-VBzBS-Na) as white solid in
DMSO-d6, d): 7.56 (d, J = 8.3 Hz, 1H); 7.36 (d, J = 8.3 Hz, 1H); 7.30 (d,
J = 8.3 Hz, 1H) for A, and 7.66 (d, J = 8.3 Hz, 1H); 7.15 (d, J = 8.3 Hz,
1H); 7.10 (d, J = 8.3 Hz, 1H) for B. Intermediates (A and B, 0.01 mol)
were next reacted with methacrylic acid (0.012 mol) in trifluor-
oacetic acid and trifluoroacetic anhydride as the media, under a
nitrogen atmosphere overnight. On removing the solvent, followed
by washing with diethyl ether, the sodium 4-(methacryloxy)
trifluorobenzenesulfonate (C:D = 4:1) was obtained in 51% yield,
72% yield characterized by 1H NMR (500 MHz, DMSO-d6,
(d, J = 8.1 Hz, 2H); 7.45 (d, J = 8.1 Hz, 2H); 6.72 (dd, J = 11.2 and
17.8 Hz, 1H); 5.85 (d, J = 17.8 Hz, 1H); 5.26 (d, s J = 11.2 Hz, 3H). 19
NMR (470 MHz, DMSO-d6,
d
): 7.49
characterized by 1H NMR (25 8C, DMSO-d6, ppm)
d 7.92–7.96 (m,
2H); 7.55 (b, 1H); 5.98 (s, 1H); 5.61 (s, 1H); 1.81 (s, 3H) for C, and
7.84 (d, J = 7.5 Hz, 1H); 7.79 (dd, J = 7.5 and 1.7 Hz, 1H); 7.60 (d,
J = 1.7 Hz, 1H); 6.33 (s, 1H); 5.80 (s, 1H); 2.00 (s, 3H) for D. The
molar ration of isomers was calculated based on the integration
ratios of the above corresponding peaks (see supporting informa-
tion). The intermediates (C and D, 0.01 mol) were next reacted with
50% aqueous solution of triphenylsulfonium chloride (0.03 mol) in
water, at room temperature overnight. The product was purified
with dichloromethane and hexane. Triphenylsulfonium salt
F
d
, ext. CF3COOH): ꢀ156.35 (m, 2F);
ꢀ139.68 (m, 2F). Then (F4-VBzBS-Na) was reacted with triphe-
nylsulfonium chloride 50% aqueous solution in water, at room
temperature overnight. The product was refined with dichlor-
omethane and hexane, triphenylsulfonium salt 4-(vinyl benzy-
loxy)-2,3,5,6-tetrafluoro benzenesulfonate (F4-VBzBS-TPS) was
obtained in 76% yield as a colorless crystal. 1H NMR (500 MHz,

610
M. Wang et al. / Journal of Fluorine Chemistry 129 (2008) 607–612
Scheme 2. Synthetic scheme of CF3 MBS-TPS.
methacryloxy trifluoro benzenesulfonate (CF3 MBS-TPS; E:F = 4:1)
dried over MgSO4. On removal of the solvent, the product was
obtained and dried under vacuum to get a white glassy solid in
yield of 75%. FT-IR(film), v cmꢀ1: 2981, 2890(CH3, str.); 1715
(C O); 1568, 1475, 1446 (phenyl ring); 1242 (CF, S O); 1088
was obtained in 62% yield as a colorless crystal. 1H NMR (500 MHz,
DMSO-d6,
3H) for E, and 7.22–7.93 (m, 18H); 6.28 (s, 1H); 5.80 (s, 1H); 2.00 (s,
3H) for F. 13C NMR (125 MHz, DMSO-d6,
): 166.2, 164.8, 153.6,
d): 7.22–7.93 (m, 18H), 5.99 (s, 1H), 5.62 (s, 1H), 1.83 (s,
d
(S O); 1066 (S O). 1H NMR (500 MHz, DMSO-d6,
15H), 6.06 (s, 1H), 5.51 (s, 1H), 5.22 (m, 1H), 4.34 (d, m, 2H), 2.24–
2.63(m, 2H), 1.89 (s, 3H). 13C NMR (125 MHz, DMSO-d6,
): 168.0,
149.6, 134.9, 132.3, 132.0, 131.6, 130.9, 129.0, 125.9, 120.3, 89.9,
60.8, 29.2, 18.8. 19F NMR (470 MHz, DMSO-d6,
, ext. CF3COOH):
ꢀ113.8 ꢀ119.6 (d, d, 2F), ꢀ203.1 (m, 1F). Anal. Calcd for
26H25F3O5S2: C, 57.98; H, 4.68; F, 10.58. Found: C, 57.68; H,
d): 7.25–7.74 (m,
147.5, 146.0, 143.9, 136.1, 135.2, 134.9, 134.3, 132.1, 131.3, 131.1,
130.2, 129.5, 128.7, 128.3, 127.5, 125.4, 124.5, 122.0, 121.3, 115.1,
113.3 and 18.0. 19F NMR (470 MHz, DMSO-d6,
d, ext. CF3COOH):
d
ꢀ60.26, ꢀ60.75. Anal. Calcd for C29H23F3O5S2: C, 60.83; H, 4.05; F,
d
9.95; Found: C, 60.39; H, 4.34; F, 10.06.
C
2.3.3. Triphenylsulfonium salt of 1,1,2-trifluorobutanesulfonate
methacrylate (MTFBS-TPS) and triphenylsulfonium salt of 4-(vinyl
benzyloxy)1,1,2-trifluorobutanesulfonate (VBzTFBS-TPS)
4.53; F, 10.33.
Triphenylsulfonium salt of 4-(vinyl benzyloxy)1,1,2-trifluorobu-
tanesulfonate (VBzTFBS-TPS) was prepared by a method similar to
MTFBS-TPS using P-chloromethylstyrene instead of methacrylic
acid under the condition of DMF and TEA at room temperature,
36 h. The product was obtained as a white glassy solid in yield of
75%. FT-IR(film), v cmꢀ1: 3030, 2981, 2890(phenyl ring, CH3, str.);
1568, 1475, 1446 (phenyl ring); 1242 (CF, S O); 1088 (S O); 1066
(S O). 1H NMR (500 MHz, DMSO-d6,
d): 7.33–7.92 (m, 19H), 6.74
(dd, J = 11.2 and 17.8 Hz, 1H); 5.83 (d, J = 17.8 Hz, 1H); 5.25 (d,
J = 11.2.0 Hz, 1H); 4.96–5.14(m, 1H); 4.76(s, 2H); 3.45–3.56(m,
2H); 2.12–2.32(m, 2H). 13C NMR (125 MHz, DMSO-d6,
d): 146.4,
Triphenylsulfonium salt of 1,1,2-trifluorobutanesulfonate
methacrylate (MTFBS-TPS) and triphenylsulfonium salt of 4-(vinyl
benzyloxy)1,1,2-trifluorobutanesulfonate (VBzTFBS-TPS) was pre-
pared in Scheme 3. It was prepared as per reported Ref. [19].
Triphenylsulfonium salt of 1,1,2-trifluorobutanesulfonate metha-
crylate (MTFBS-TPS): The lithium salt of 1,1,2-trifluoro-4-hydroxy-
1-butanesulfonate (HOTFHBSO3Li) was prepared according to the
literature [21]. This (5.0 mmol) was then dissolved in 50 ml
deionized water. A 50% aqueous solution of triphenylsulfonium
chloride (10.0 mmol) was added with stirring at room tempera-
ture. The reaction mixture was stirred overnight, and extracted
with dichloromethane. The organic layer was dried over MgSO4.
The solvent was removed and the product was dried under vacuum
to get HOTFHBSO3.TPS as white solid (yield 42%). FT-IR(film),
v cmꢀ1: 3448 (OH, str.); 3060 (phenyl ring C–H, str.); 1568,
1475,1446 (phenyl ring); 1243 (CF, S O); 1088 (S O); 1065 (S O).
136.1, 134.9, 134.2, 132.2, 131.3, 131.1, 130.3, 129.8, 129.2, 128.7,
126.3, 125.2, 121.3, 114.9, 88.6, 87.1, 55.8, 46.5, 32.3. 19F NMR
(470 MHz, DMSO-d6,
d
, ext. CF3COOH):
d
ꢀ112.8 ꢀ120.4 (d, d, 2F),
ꢀ202.9 (m, 1F). Anal. Calcd for C31H29F3O4S2: C, 63.46; H, 4.98; F,
9.71. Found: C, 63.73; H, 5.23; F, 10.16.
2.4. Synthesis of polymers
1H NMR (500 MHz, DMSO-d6,
d): 7.3–7.8 (m, 15H); 5.0–5.2 (m,
1H); 3.7–3.9 (m, 2H); 2.0–2.4 (m, 2H).
Terpolymers were prepared by free radical polymerization in
HOTFHBSO3ꢁTPS (5.0 mmol) was dissolved in 10 ml dried
dichloromethane. Methacryloyl chloride (6.0 mmol in 3 ml
dichloromethane) was added dropwise at 0 8C under nitrogen
flow, then warmed to room temperature, kept it for 2 days. Next
the solution was washed with water, and the organic layer was
sealedpressure vessels(Scheme4). Hydroxystrene/g-butyrolactone
methacrylate/2-thienylmethyl methacrylate, 2-ethyl-2-adamantyl-
methacrylate, anionic PAGs, and 2, 20-azobisisobutyronitrile (AIBN)
as a free radical initiator (5 mol% to the monomers) were dissolved
in freshly distilled anhydrous tetrahydrofuran and acetonitrile

M. Wang et al. / Journal of Fluorine Chemistry 129 (2008) 607–612
611
Scheme 3. Synthetic scheme of MTFBS-TPS and VBzTFBS-TPS.
Scheme 4. Synthetic scheme of terpolymers.
(v/v = 1:1). Polymerization was performed at 65 8C for 24 h. The
3. Results and discussion
polymer solutions were precipitated into a large amount of diethyl
ether or petroleum ether and dried in vacuum, the products were
then redissolved in THF and precipitated with petroleum ether
twice, and then dried in vacuum for 24 h. The polymer composition
was calculated by 1H NMR. The results are given in Table 1.
The anionic bound PAGs were prepared in moderate to good
yield, and characterized by 1H NMR (see Fig. 3), 19F NMR and 13C
NMR, as well as elemental analyses. The terpolymers were
obtained in yields from 31.3 to 43.2%, with PAG contents in the
Table 1
Polymerization results
Stabilityb (8C)
Tg (8C)
a
Polymer
Mole feed ratio
Polymer composition
Yield (%)
Mw (PDI)
AdG
EAMA
PAG
AdG
EAMA
PAG
GB-EA-F4-MBS-TPS
GB-EA-CF3 PAG
25
72.5
72.5
67.5
63.6
64.5
72.5
72.5
60
2.5
2.5
2.5
2.8
2.8
2.5
2.5
5.0
5.0
5.0
44.8
42.4
42.6
41.3
42.7
35.0
52.4
40.3
38.5
33.4
48.6
51.2
51.7
46.3
46.0
57.9
40.8
51.4
56.2
57.9
6.6
6.4
36.2
31.4
43.0
28.5
35.7
37.3
31.3
31.3
42.3
43.2
3100 (3.1)
2700 (2.1)
3100 (3.1)
2970 (1.6)
3050 (2.1)
3600 (1.6)
3200 (2.1)
3700 (2.0)
2600 (1.6)
2900 (1.8)
178
181
195
187
147
145
149
159
170
186
151
162
166
147
25
GB-EA-MTFB-TPS
30
5.7
TMM-EA-F4-MBS-TPS
TMM-EA-MTFB-TPS
HS-EA-F4-MBS-TPSa
HS-EA-F4-VBzBS-TPS
HS-EA-CF3 MBS-TPS
HS-EA-MTFBS-TPS
HS-EA-VBzTFBS-TPS
33.6
32.7
25
12.4
11.3
7.1
123
c
c
c
25
6.8
35
8.3
30
65
5.3
117
139
30
65
6.7
a
The molecular weight was determined by GPC with THF as mobile phase and polystyrene as narrow standards.
The decomposition temperature was determined according to weight loss around 3.0%.
b
c
Could not be determined by DSC, probably due to rigidity of these polymers, resulting from the bulky adamantyl and triphenylsulfonium moiety of the PAG in the
polymer.

612
M. Wang et al. / Journal of Fluorine Chemistry 129 (2008) 607–612
below the decomposition temperature for these polymers in this
study also.
The acid generation efficiency for HS-EA-MTFBS-TPS, HS-EA-F4-
MBS-TPS, HS-EA-CF3 MBSTPS are 81, 68, and 54% at the dose of
150 mJ/cm2, respectively [19]. This demonstrates that the acid
generation of PAGs is in the following order, MTFBS-TPS > F4-
MBS-TPS > CF3 MBS-TPS. The stronger the electron-withdrawing
group substituted on the aromatic ring, the higher the acidity of the
PAG, leading to higher acid generation. The MTFBS-TPS and
VBzTFBS-TPS has strong electron withdrawing fluorines next to the
sulphonium group, this promotes higher acid generation on
exposure.
Fig. 3. 1H NMR of F4-MBS-TPS in DMSO-d6.
4. Conclusion
A new series of functionalized anionic PAGs [methacrylate-
substituted benzene sulfonic PAGs] (CF3 MBS-TPS, F4-MBS-TPS,
F4-VBzBS-TPS) and perfuoroalkanesulfonic PAGs (MTFBS-TPS and
VBzTFBS-TPS), as well as corresponding PAG bound polymeric
resists were prepared and characterized. The acid generation
efficiency of PAG bound polymers was in the range of 54–81%,
which is consistent with the electron withdrawing power of the
substitutes. Based on previously reported 193 nm and EUVL results
of F4-MBS-TPS bound polymer photoresists [10,15], these fluori-
nated PAGs and corresponding PAG bound polymers should be
effective resists for 193 nm or EUV lithography.
Acknowledgment
Fig. 4. 1H NMR of HS-EA-F4-MBS-TPS in DMSO-d6.
The authors gratefully acknowledge Intel Corp. for financial
support.
range of 5.3–8.3%, except for the TMM series with high PAG content
of 11.3, 12.4% (mole ratio) for TMM-EA-MTFBS-TPS, TMM-EA-F4-
TPS, respectively, which depends on the reactivity of the
monomers. The molar composition of each unit in the terpolymers
was determined by 1H NMR (Fig. 4). The characteristic peaks:
around 9.1 ppm is assigned to the proton of hydroxyl group of
HOST, 7.6–7.8 ppm is assigned to the protons from PAG’s cation
TPS, 6.6–7.1 ppm from HOST and PAG’s anionic part, 0.7–2.6 ppm
from the EAMA and main-chain of polymer. The molar composition
was calculated based on the integration ratios of the above
corresponding peaks. The molecular weights were determined by
GPC with THF as mobile phase. The results indicated the
fluorinated PAG grafting polymers had a moderate molecular
weight and molecular weight distribution (MWD), there is no big
difference among different PAGs. The thermal stability of the
polymers was identified by estimating the percentage of the
weight loss of the polymer on thermal decomposition using TGA.
The decomposition temperatures (Td) were in the range of 147–
195 8C. The glass transition temperature (Tg) of polymer GB or
TMM systems was between 123 and 166 8C related to the
thermostability. As for HOST system polymers, we just got the
Tg of HS-EA-MTFBS PAG was 117 8C, the other polymers that bound
CF3, F4 or VBzF4-PAG showed no obvious Tg, suggesting that
polymer HS-EA-MTFBS PAG has softening behavior due to the alkyl
plasticization chain structure of the PAG. The other polymers are
probably quite rigid, resulting from the restrictive motion of the
aromatic structures of the PAG. As reported previously for
analogous rigid polymers [12], no transitions were observed
References
[1] H. Ito, Adv. Polym. Sci. 172 (2005) 37.
[2] K.L. Covert, D.J. Russell, J Appl. Polym. Sci. 49 (1993) 657.
[3] Y. Suzuki, D.W. Johnson, Proc. SPIE 3333 (1998) 735.
[4] K. Kannan, J. Koistinen, K. Beckman, T. Evans, J.F. Gorzelany, K.J. Hansen, O.P.D.
Jones, E. Helle, M. Nyman, J.P. Giesy, Environ. Sci. Technol. 35 (2001) 1593.
[5] J.W. Martin, S.A. Mabury, K.R. Solomon, D.C.G. Muir, Environ. Toxicol. Chem. 22
(2003) 196.
[6] M.D. Stewart, H.V. Tran, G.M. Schmid, T.B. Stachowiak, D.J. Becker, C.G. Willson, J.
Vac. Sci. Technol. B 20 (2002) 2946.
[7] M.-X. Wang, N.D. Jarnagin, W. Yueh, J.M. Roberts, K.E. Gonsalves, J. Mater. Chem.
16 (2006) 3701.
[8] M.-X. Wang, K.E. Gonsalves, W. Yueh, J.M. Roberts, Macromol. Rapid Commun. 27
(2006) 1590.
[9] H. Wu, K.E. Gonsalves, Adv. Mater. 13 (2001) 195.
[10] M. Thiyagarajan, K. Dean, K.E. Gonsalves, J. Photopolym. Sci. Technol. 18 (2005)
737.
[11] T. Watanabe, Y. Fukushima, H. Shiotani, M. Hayakawa, S. Ogi, Y. Endo, T. Yama-
naka, S. Yusa, H. Kinoshita, J. Photopolym. Sci. Technol. 19 (2006) 521.
[12] M.-X. Wang, K.E. Gonsalves, M. Rabinovich, W. Yueh, J.M. Roberts, J. Mater. Chem.
17 (2007) 1699.
[13] C.-X. Lee, M.-X. Wang, N. D. Jarnagin, K.E. Gonsalves, J.M. Roberts, W. Yueh, C.L.
Henderson, Proc. SPIE (2007), 6519 (Pt. 1, Advances in Resist Technology and
Processing XXIV), 65191E.
[14] G. Sandford, Phil. Trans. R. Soc. Lond. A 358 (2000) 455.
[15] S. Ebnesajjad, Introduction to Fluoropolymers, www.FluoroConsutants.com.
[16] R.K. Khanna, N. Bhingara, Chem. Mater. 5 (1993) 899.
[17] K.R. Gee, E.A. Archer, H.C. Kang, Tetrahedron Lett. 40 (1999) 1471.
[18] M.-X. Wang, W. Yueh, M. Tang, T.-H. Her, K.E. Gonsalves, J. PhotoPolym. Sci.
Technol. 20 (2007) 793.
[19] M.-X. Wang, W. Yueh, K.E. Gonsalves, Macromolecules 40 (2007) 8220.
[20] M.-X. Wang, W. Yueh, K.E. Gonsalves, J. PhotoPolym. Sci. Technol. 20 (2007) 751.
[21] J.M.G. Cowie, G.H. Spence, Solid State Ionics 123 (1999) 233.