Title: Photoacid generators and photoresists comprising same
Abstract: This invention relates to new photoacid generator compounds and photoresist compositions that comprise such compounds. In particular, the invention relates to photoacid generator compounds that generate an .alpha.,.alpha.-difluoroalkyl sulfonic acid upon exposure to activating radiation. Positive- and negative-acting chemically amplified resists that contain such PAGs are particularly preferred. The invention also includes methods for synthesis of such PAGs and .alpha.,.alpha.-difluoroalkyl sulfonic acids.
Patent Number: 6,849,374 Issued on 02/01/2005 to Cameron, et al.
| Inventors:
|
Cameron; James F. (Cambridge, MA);
Zydowsky; Thomas M. (Worcester, MA)
|
| Assignee:
|
Shipley Company, L.L.C. (Marlborough, MA)
|
| Appl. No.:
|
007855 |
| Filed:
|
November 3, 2001 |
| Current U.S. Class: |
430/270.1; 430/18; 430/914; 430/921; 562/113 |
| Intern'l Class: |
G03F 007/038; G03F007/039; G03F007/26; G03F007/30 |
| Field of Search: |
430/270.1,18,914,921
562/113
|
References Cited [Referenced By]
U.S. Patent Documents
| 5296332 | Mar., 1994 | Sachdev et al. | 430/270.
|
| 6280911 | Aug., 2001 | Trefonas, III | 430/326.
|
| 6358665 | Mar., 2002 | Pawlowski et al. | 430/270.
|
| Foreign Patent Documents |
| 295 421 | Oct., 1991 | DE.
| |
| 0 693 468 | Jan., 1996 | EP.
| |
| 1 033 624 | Sep., 2000 | EP.
| |
| 1199603 | Apr., 2002 | EP | .
|
Primary Examiner: Thornton; Yvette C.
Attorney, Agent or Firm: Corless; Peter F., Frickey; Darryl P.
Edwards & Angell, LLP
Parent Case Text
"This application claims the benefit of U.S. Provisional Application(s)
No(s).: 60/245,848 Nov. 3, 2000
Claims
What is claimed is:
1. A chemically-amplified positive-acting photoresist composition
comprising:
a) a resin that comprises photoacid-labile groups; and
b) one or more photoacid generator compounds other than a
N-oxyimidosulfonate that upon exposure to activating radiation generate an
acid of the formula R(CR.sup.1 R2)CF.sub.2 SO.sub.3 H
where R is optionally substituted alkyl having 4 to about 20 carbon atoms,
optionally substituted alicyclic group, optionally substituted carbocyclic
aryl group, optionally substituted heteroalicyclic group, or optionally
substituted heteroaromatic group, and R is not perhaloalkyl; and
R.sup.1 and R.sup.2 are each independently hydrogen or non-hydrogen
substituent.
2. The photoresist composition of claim 1 wherein R is optionally
substituted alkyl.
3. The photoresist composition of claim 1 wherein R is an optionally
substituted alicyclic group.
4. The photoresist composition of claim 1 wherein R is an optionally
substituted carbocyclic aryl group.
5. The photoresist composition of claim 1 wherein R is an optionally
substituted heteroalicyclic group, or optionally substituted
heteroaromatic group.
6. The photoresist composition of claim 1 wherein the one or more photoacid
generator compounds are iodonium compounds.
7. The photoresist composition of claim 1 wherein the one or more photoacid
generator compounds are sulfonium compounds.
8. The photoresist of claim 1 wherein the one or more photoacid generators
are non-ionic compounds.
9. The photoresist composition of claim 1 wherein one or more photoacid
generator compounds are sulfonate compounds.
10. The photoresist composition of claim 1 wherein one or more photoacid
generator compounds are diazosulfone compounds.
11. The photoresist composition of claim 1 wherein the resin comprises
phenolic groups.
12. The photoresist composition of claim 1 wherein the resin is at least
substantially free of aromatic groups.
13. The photoresist of claim 1 wherein the resin is completely free of
aromatic groups.
14. An article of manufacture comprising a coating layer of a photoresist
composition of claim 1.
15. The article of manufacture of claim 14 wherein the article is a
microelectronic wafer substrate.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to new photoacid generator compounds ("PAGs") and
photoresist compositions that comprise such compounds. In particular, the
invention relates to photoacid generator compounds that generate an
.alpha.,.alpha.-difluoroalkyl sulfonic acid upon exposure to activating
radiation. Positive- and negative-acting chemically amplified resists that
contain such PAGs and that are imaged with short wavelength radiation such
as sub-300 nm and sub-200 nm radiation are particularly preferred.
2. Background
Photoresists are photosensitive films for transfer of images to a
substrate. They form negative or positive images. After coating a
photoresist on a substrate, the coating is exposed through a patterned
photomask to a source of activating energy such as ultraviolet light to
form a latent image in the photoresist coating. The photomask has areas
opaque and transparent to activating radiation that define an image
desired to be transferred to the underlying substrate. A relief image is
provided by development of the latent image pattern in the resist coating.
The use of photoresists is generally described, for example, by Deforest,
Photoresist Materials and Processes, McGraw Hill Book Company, New York
(1975), and by Moreau, Semiconductor Lithography, Principals, Practices
and Materials, Plenum Press, New York (1988).
Known photoresists can provide features having resolution and size
sufficient for many existing commercial applications. However for many
other applications, the need exists for new photoresists that can provide
highly resolved images of submicron dimension.
Various, attempts have been made to alter the make-up of photoresist
compositions to improve performance of functional properties. Among other
things, a variety of photoactive compounds have been reported for use in
photoresist compositions. See, e.g., U.S. Pat. No. 4,450,360 and European
Application 615163.
More recently, certain "chemically amplified" photoresist compositions have
been reported. Such photoresists may be negative-acting or positive-acting
and rely on multiple crosslinking events (in the case of a negative-acting
resist) or deprotection reactions (in the case of a positive-acting
resist) per unit of photogenerated acid. In other words, the
photogenerated acid acts catalytically. In the case of positive chemically
amplified resists, certain cationic photoinitiators have been used to
induce cleavage of certain "blocking" groups pendant from a photoresist
binder, or cleavage of certain groups that comprise a photoresist binder
backbone. See, for example, U.S. Pat. Nos. 5,075,199; 4,968,851;
4,883,740; 4,810,613; and 4.491,628, and Canadian Patent Application
2,001,384. Upon selective cleavage of the blocking group through exposure
of a coating layer of such a resist, a polar functional group is provided,
e.g., carboxyl, phenol or imide, which results in different solubility
characteristics in exposed and unexposed areas of the resist coating
layer.
SUMMARY OF THE INVENTION
We have now discovered novel photoacid generator compounds (PAGs) for use
in either positive-acting or negative-acting photoresist compositions. In
particular, photoacid generators are provided that can produce an
optionally substituted .alpha.,.alpha.-difluoroalkyl sulfonic acid upon
exposure to activating radiation.
An .alpha.,.alpha.-difluoroalkyl sulfonic acid as referred to herein
indicates an alkyl sulfonic acid that has two fluoro atoms substituted on
the carbon adjacent (i.e. .alpha.) to the sulfonic acid moiety (i.e. the
group --CF.sub.2 --), but where the alkyl moiety is not fully substituted
by fluoro at all available positions, i.e. the alkyl moiety is not a
perfluoro moiety. For instance, suitable .alpha.,.alpha.-difluoroalkyl
sulfonic acids include those of the formula RCF.sub.2 SO.sub.3 H, where R
is other than fluoro such as hydrogen, optionally substituted C.sub.1-18
alkyl that is not filly substituted by fluoro or other
electron-withdrawing groups such as other halo, optionally substituted
aryl such as optionally substituted carbocyclic aryl particularly phenyl,
naphthyl or anthracenyl, or optionally substituted heteroalicyclic or
heteroaromatic preferably having 1 to 3 separate or fused rings with 1-3
hetero (N, O or S) ring members such as optionally substituted thienyl and
the like.
Generally preferred .alpha.,.alpha.-difluoroalkyl sulfonic acids include
those of the formula R(CR.sup.1 R.sup.2)CF.sub.2 SO.sup.3 H, where R is a
group of relatively large volume such as optionally substituted C.sub.4-20
alkyl and preferably is an alicyclic group such as cyclohexyl, adamantyl
and the like; optionally substituted carbocyclic aryl such as optionally
substituted phenyl, naphthyl or anthracenyl; or optionally substituted
heteroalicyclic or heteroaromatic preferably having 1 to 3 separate or
fused rings with 1-3 hetero (N, O or S) ring members such as optionally
substituted thienyl and the like; and R.sup.1 and R.sup.2 are each
independently hydrogen or a non-hydrogen substituents, and preferably
R.sup.1 and R.sup.2 are each hydrogen.
We have found that photoresists containing a PAG of the invention can
exhibit excellent lithographic results. Among other things, the
photogenerated .alpha.,.alpha.-difluoroalkyl sulfonic acids are strong
acids, but are not prone to phase separation or other migration that can
be exhibited by perfluoro alkyl acids. Additionally, the ability to
include a large volume substituent such as a carbon or hetero alicyclic or
aryl group enables further engineering of a resist formulation that can
favorably impact lithographic performance.
The .alpha.,.alpha.-difluoroalkyl sulfonic acid can be photo-generated from
a variety of photoreactive molecules, including ionic compounds, such as
an onium salt, as well as non-ionic compounds. Generally preferred PAG
compounds of the invention that can generate an
.alpha.,.alpha.-difluoroalkyl sulfonic acid upon photoactivation include
onium compounds such as sulfonium and iodonium compounds; and sulfonate
compounds such as N-oxyimidosulfonates, N-oxyiminosulfonates, phenolic
sulfonates arylalkylsulfonates particularly benzylic sulfonates;
disulfones; diazosulfones; .alpha.,.alpha.-methylenedisulfones,
disulfonylhydrazines, and the like.
Preferred;photoacid generator compounds of the invention include those that
comprise one or more substituents of cyclopentyl, cyclohexyl, optionally
substituted phenyl, pentafluorophenyl, optionally substituted thienyl,
optionally substituted naphthyl, optionally substituted adamantyl, or
optionally substituted isobornyl, particularly where such substituent is a
moiety of the photoacid generator compound that forms a sulfonate acid
upon photoactivation of the compound.
Further provided are new methods for synthesis of PAGs of the invention.
Preferred PAG syntheses of the invention include reaction of a carbonyl
compound to provide a difluoro alkene which is then sulfonated to provide
the .alpha.,.alpha.-difluoroalkyl sulfonic group.
Preferably, PAGs of the invention are used in positive-acting or
negative-acting chemically amplified photoresists, i.e. negative-acting
resist compositions which undergo a photoacid-promoted crosslinking
reaction to render exposed regions of a coating layer of the resist less
developer soluble than unexposed regions, and positive-acting resist
compositions which undergo a photoacid-promoted deprotection reaction of
acid labile groups of one or more composition components to render exposed
regions of a coating layer of the resist more soluble in an aqueous
developer than unexposed regions. Preferred imaging wavelengths are
sub-300 nm and sub-200 nm such as 248 nm, 193 nm and 157 nm. Longer
wavelengths such as I-line (365 nm) also can be employed, particularly
where a sensitizer is employed as an additional resist component.
Particularly preferred photoresists of the invention contain an
imaging-effective amount of one or more PAGs as disclosed herein and a
resin that is selected from the group of:
1) a phenolic resin that contains acid-labile groups that can provide a
chemically amplified positive resist particularly suitable for imaging at
248 nm. Particularly preferred resins of this class include: i) polymers
that contain polymerized units of a vinyl phenol and an allyl acrylate,
where the polymerized alkyl acrylate (which includes (meth)acrylates)
units can undergo a deblocking reaction in the presence of photoacid.
Exemplary alkyl acrylates (which includes (meth)acrylates) that can
undergo a photoacid-induced deblocking reaction include e.g. t-butyl
acrylate, t-butyl methacrylate, methyladamantyl acrylate, methyl adamantyl
methacrylate, and other non-cyclic alkyl and alicyclic acrylates (which
includes (meth)acrylates) that can undergo a photoacid-induced reaction;
such polymers have been described in U.S. Pat. Nos. 6,042,997 and
5,492,793, incorporated herein by reference; ii) polymers that contain
polymerized units of a vinyl phenol, an optionally substituted vinyl
phenyl (e.g. styrene) that does not contain a hydroxy or carboxy ring
substituent, and an alkyl acrylate (which includes (meth)acrylates) such
as those deblocking groups described with polymers i) above, such as
polymers described in U.S. Pat. No. 6,042,997, incorporated herein by
reference; and iii) polymers that contain repeat units that comprise an
acetal or ketal moiety that will react with photoacid, and optionally
aromatic repeat units such as phenyl or phenolic groups, such as polymers
as described in U.S. Pat. Nos. 5,929,176 and 6,090,526, incorporated
herein by reference.
2) a resin that is substantially or completely free of phenyl or other
aromatic groups that can provide a chemically amplified positive resist
particularly suitable for imaging at sub-200 nm wavelengths such as 193
nm. Particularly preferred resins of this class include: i) polymers that
contain polymerized units of a non-aromatic cyclic olefin (endocyclic
double bond) such as an optionally substituted norbornene, such as
polymers described in U.S. Pat. Nos. 5,843,624 and 6,048,664, incorporated
herein by reference; ii) polymers that contain alkyl acrylate units such
as e.g. t-butyl acrylate, t-butyl methacrylate, methyladamantyl acrylate,
methyl adamantyl methacrylate, and other non-cyclic alkyl and alicyclic
acrylates; such polymers have been described in U.S. Pat. No. 6,057,083;
European Published Applications EP01008913A1 and EP00930542A1; and U.S.
pending patent application Ser. No. 09/143,462, filed Aug. 28, 1998, all
incorporated herein by reference; and iii) polymers that contain
polymerized anhydride units, particularly polymerized maleic anhydride
and/or itaconic anhydride units, such as disclosed in European Published
Application EP01008913A1 and U.S. Pat. No. 6,048,662, both incorporated
herein by reference; and/or combinations of one or more resins of types
i), ii) or iii), i.e. combinations of one or more of polymers that
polymerized units of a non-aromatic cyclic olefin, polymers that contain
alkyl acrylates (which includes (meth)acrylates); and/or polymers that
contain polymerized anhydride units.
Resists of the invention also may comprise a mixture of distinct PAGs,
typically a mixture of 2 or 3 different PAGs, more typically a mixture
that consists of a total of 2 distinct PAGs. At least one PAG of the
mixture will generate an .alpha.,.alpha.-difluoroalkyl sulfonic acid upon
exposure to activating radiation, preferably a PAG compound of Formulae I,
IA, II, IIA, III, IIIA, IV, IVA, V, VA, VI, VIA, VII and VIIA as disclosed
herein. The other PAG(s) of the mixture also may generate an
.alpha.,.alpha.-difluoroalkyl sulfonic acid, or may generate another
photoacid. Photoresists that contain such PAG mixtures can exhibit even
farther enhanced lithographic performance.
The invention also provide methods for forming relief images of the
photoresists of the invention, including methods for forming highly
resolved patterned photoresist images (e.g. a patterned line having
essentially vertical sidewalls) of sub-quarter micron dimensions or less,
such as sub-0.2 or sub-0. 1 micron dimensions.
The invention further provides articles of manufacture comprising
substrates such as a microelectronic wafer or a flat panel display
substrate having coated thereon the photoresists and relief images of the
invention. Other aspects of the invention are disclosed infra.
DETAILED DESCRIPTION OF THE INVENTION
In a first aspect of the invention, iodonium PAGs are provided that can
generate an .alpha.,.alpha.-difluoroalkyl sulfonic acid. The iodonium PAGs
suitably may have substituents of optionally substituted C .sub.1-18 alkyl
such as t-butyl, pentyl and the like as well as cycloalkyl such as
cyclohexyl, adamantyl, isobornyl and the like; optionally substituted
carbocyclic aryl such as optionally substituted phenyl, naphthyl or
anthracenyl; and optionally substituted heteroalicyclic or heteroaromatic
preferably having 1 to 3 separate or fused rings and 1-3 hetero (N, O or
S, preferably O or S) ring atoms, such as thienyl.
For many applications, particularly for short-wavelength imaging such as
sub-200 nm particularly 193 nm imaging, especially preferred are iodonium
salts that have an .alpha.,.alpha.-difluoroalkyl sulfonate counter anion,
and one or more cation substituents of optionally substituted phenyl
(including pentafluorophenyl), optionally substituted naphthyl and
optionally substituted thienyl.
In particular, preferred iodonium PAGS of the invention include those of
the following Formula I:
##STR1##
wherein R and R.sup.1 are the same or different and are suitably optionally
substituted alkyl (which includes carbon alicyclic); optionally
substituted carbocyclic aryl; and optionally substituted heteroalicyclic
or heteroaromatic (including optionally substituted thienyl); and
preferably R and R.sup.1 are independently optionally substituted phenyl
(including pentafluorophenyl), optionally substituted naphthyl and
optionally substituted thienyl; and
R.sup.2 is other than fluoro or other halo and is suitably hydrogen,
optionally substituted C.sub.1-18 alkyl that is not fully substituted by
fluoro or other electron-withdrawing groups such as other halo, optionally
substituted aryl such as optionally substituted carbocyclic aryl
particularly phenyl, naphthyl or anthracenyl, or optionally substituted
heteroalicyclic or heteroaromatic preferably having 1 to 3 separate or
fused rings with 1-3 hetero (N, O or S, preferably O or S) ring members
such as optionally substituted thienyl.
Generally preferred compounds of Formula I are those where the sulfonate
counter anion has a spaced "bulky" or relatively large volume substituent,
such as PAGs of the following Formula IA:
##STR2##
wherein R and R.sup.1 are each the same as defined in Formula I above;
R.sup.3 is optionally substituted alkyl having at least 4 carbon atoms,
preferably optionally substituted C.sub.4-20 alkyl and preferably is an
alicyclic group such as optionally substituted cyclohexyl, optionally
substituted adamantyl, optionally substituted isobornyl and the like;
optionally substituted carbocyclic aryl such as optionally substituted
phenyl, naphthyl or anthracenyl; or optionally substituted heteroalicyclic
or heteroaromatic preferably having 1 to 3 separate or fused rings with
1-3 hetero (N, O or S) ring members such as optionally substituted thienyl
and the like; and
R.sup.4 and R.sup.5 are each independently hydrogen or a non-hydrogen
substituents such as optionally substituted C.sub.1-20 alkyl, optionally
substituted C.sub.1-20 alkoxy, optionally substituted carbocyclic aryl
such as optionally substituted phenyl; and preferably one or both of
R.sup.4 and R.sup.5 are hydrogen.
In a further aspect of the invention, sulfonium PAGs are provided that can
generate an .alpha.,.alpha.-difluoroalkyl sulfonic acid. The sulfonium
PAGs suitably may have substituents of optionally substituted C.sub.1-18
alkyl such as t-butyl, pentyl and the like as well as cycloalkyl such as
cyclohexyl, adamantyl, isobornyl and the like; optionally substituted
carbocyclic aryl such as optionally substituted phenyl, naphthyl or
anthracenyl; and optionally substituted heteroalicyclic or heteroaromatic
preferably having 1 to 3 separate or fused rings and 1-3 hetero (N, O or
S, preferably O or S) ring atoms, such as thienyl.
For many applications, particularly preferred are sulfonium salts that have
an .alpha.,.alpha.-difluoroalkyl sulfonate counter anion, and one or more
cation substituents of optionally substituted phenyl (including
pentafluorophenyl), optionally substituted naphthyl and optionally
substituted thienyl.
In particular, preferred sulfonium PAGs of the invention include those of
the following Formula II:
##STR3##
wherein R, R.sup.1 and R.sup.1 ' are the same or different and are suitably
the same as defined for R and R.sup.1 in Formula I above; and R.sup.2 is
the same as defined in Formula I.
Generally preferred compounds of Formula II are those where the sulfonate
counter anion has a spaced "bulky" or relatively large volume substituent,
such as PAGs of the following Formula IIA:
##STR4##
wherein R, R.sup.1 and R.sup.1 ' are each the same as defined in Formula II
above; and R.sup.3, R.sup.4 and .sup.5 are each the same as defined in
Formula IA above.
In another aspect of the invention, optionally substituted
N-oxyimidosulfonate PAGs (non-ionic compounds) are provided that have an
.alpha.,.alpha.-difluoroalkyl sulfonate substituent and that can generate
and an .alpha.,.alpha.-difluoroalkyl sulfonic acid upon photoactivation.
In particular, preferred N-oxyimidosulfonate PAGs of the invention include
those of the following Formula III:
##STR5##
wherein R.sup.2 is other than fluoro or other halo and is suitably
hydrogen, optionally substituted C.sub.1-18 alkyl that is not fully
substituted by fluoro or other electron-withdrawing groups such as other
halo, optionally substituted aryl such as optionally substituted
carbocyclic aryl particularly phenyl, naphthyl or anthracenyl, or
optionally substituted heteroalicyclic or heteroaromatic preferably having
1 to 3 separate or fused rings with 1-3 hetero (N, O or S, preferably O or
S) ring members such as optionally substituted thienyl; and
R.sup.6 and R.sup.7 are independently optionally substituted alkyl
preferably having 1 to about 10 carbon atoms; optionally substituted
alkoxy preferably having 1 to about 10 carbon atoms; or optionally
substituted alkylthio preferably having 1 to about 10 carbon atoms,
or more preferably R.sup.6 and R.sup.7 are taken together to form an
optionally substituted alkylene or alkenylene chain preferably having 2-5
carbons so as to ring with the N and C.dbd.O groups. Such compounds can be
readily prepared from open chain and cyclic N-hydroxyimides, e.g.
N-hydroxy-succinimide, N-hydroxymaleimide, N-hydroxyphthalimide,
N-hydroxy-1,8-naphtalimide, N-hydroxy-5-norbornene-2,3-dicarboximide,
HON(COCH.sub.3).sub.2 and the like. See also International Application
WO94/10608 for preparation of N-sulfonyloxyimide PAGs.
Generally preferred PAGs of Formula III include those of the following
Formula IIIA:
##STR6##
wherein R.sup.3, R.sup.4 and R.sup.5 are each the same as defined in
Formula IA above; and
R.sup.6 and R.sup.7 are the same as defined in Formula III above.
In yet a further aspect of the invention, optionally substituted N-oxyimino
sulfonate PAGs are provided that have an .alpha.,.alpha.-difluoroalkyl
sulfonate substituent and that can generate and an
.alpha.,.alpha.-difluoroalkyl sulfonic acid upon photoactivation. In
particular, preferred N-oxyiminosulfonate PAGs of the invention include
those of the following Formula IV:
##STR7##
R.sup.2, R.sup.6 and R.sup.7 are the same as defined in Formula III above.
Such compounds can be readily prepared from oximes of open chain and
cyclic ketones such as cyclohexanone, .alpha.-tetralone, pentanone, etc.
Generally preferred PAGs of Formula IV include those of the following
Formula IVA:
##STR8##
wherein R.sup.3, R.sup.4 and R.sup.5 are each the same as defined in
Formula IA above; and R.sup.6 and R.sup.7 are the same as defined in
Formula IV above.
One preferred group of N-oxyiminosulfonate PAGs are .alpha.-cyano
compounds, such as those of the following Formula V:
##STR9##
wherein R.sup.2 and R.sup.7 is the same as defined in Formula IV above, or
R.sup.7 is optionally substituted carbocyclic aryl or optionally
substituted heteroaryl, particularly optionally substituted phenyl such as
pentafluorophenyl, optionally substituted naphthyl or optionally
substituted thienyl; and EW is an electron-withdrawing group such as
cyano; haloalkyl especially halo(C.sub.1-8 alkyl) such as fluoro(C.sub.1-8
alkyl) preferably a perhaloalkyl such as perfluoroalkyl e.g.
perfluoro(C.sub.1-8 alkyl); an ester such as alkyl esters e.g.
--(.dbd.O)OC.sub.1-8 alkyl and the like. Cyano is a preferred EW group.
Such compounds can be prepared from open chain and cyclic acetonitrile
derivatives such as 4-methoxybenzeneaectonitrile (CH.sub.3 OC.sub.6
H.sub.4 CH.sub.2 CN) and 1-cyclohexenylacetonitrile.
Preferred compounds of Formula V include those of the following Formula VA:
##STR10##
wherein R.sup.3, R.sup.4, R.sup.5 and R.sup.7 are the same as defined in
Formula IVA above or R.sup.7 is optionally substituted carbocyclic aryl or
optionally substituted heteroaryl, particularly optionally substituted
phenyl such as pentafluorophenyl, optionally substituted naphthyl or
optionally substituted thienyl; and EW is the same as defined in Formula V
above, with CN being a preferred EW group.
In a further aspect of the invention, optionally substituted phenolic
sulfonate PAGs are provided that have one or more
.alpha.,.alpha.-difluoroalkyl sulfonate substituents and that can generate
and an .alpha.,.alpha.-difluoroalkyl sulfonic acid upon photoactivation.
Such compounds have .alpha.,.alpha.-difluoroalkyl sulfonate groups grafted
onto one or more phenolic --OH moieties, preferably two or three
.alpha.,.alpha.-difuoroalkyl sufonate groups on a single phenyl group.
Preferred phenolic .alpha.,.alpha.-difluoroalkyl sulfonate compounds
include PAGs of the following Formula VI:
##STR11##
wherein R.sup.2 is the same as defined in Formula I above;
R.sup.8 is a non-hydrogen substituent such as halo; hydroxy; nitro; cyano;
sulfonyl; optionally substituted aminoalkyl preferably having from 1 to
about 20 carbon atoms, more preferably 1 to about 8 carbon atoms;
optionally substituted alkoxy preferably having from 1 to about 20 carbon
atoms, more preferably 1 to about 8 carbon atoms; optionally substituted
aminoalkyl preferably having from 1 to about 20 carbon atoms, more
preferably 1 to about 8 carbon atoms; optionally substituted alkylthio
preferably having from 1 to about 20 carbon atoms, more preferably 1 to
about 8 carbon atoms; optionally substituted alkylsulfinyl preferably
having from 1 to about 20 carbon atoms, more preferably 1 to about 8
carbon atoms; optionally substituted alkylsulfonyl preferably having from
1 to about 20 carbon atoms, more preferably 1 to about 8 carbon atoms;
optionally substituted aryloxy such as phenoxy; optionally substituted
aralkyl such as benzyl; optionally substituted alkanoyl preferably having
from 1 to about 20 carbons atoms with acetyl being a preferred group;
optionally substituted carbocyclic aryl such as phenyl, naphthyl,
biphenyl, and the like; optionally substituted heteroaromatic or
heteroalicyclic having 1 to 3 rings, 3 to 8 ring members in each ring and
from 1 to 3 hetero atoms such as thienyl;
m is an integer from 0 (i.e. no R.sup.8 groups) to 4;
z is an integer from 1 to 6, and z is preferably is 1, 2, 3 or 4, and the
sum of m and z does not exceed 6.
Preferred compounds of Formula VI include those of the following Formula
VIA:
##STR12##
wherein R.sup.3, R.sup.4 and R.sup.5 are the same as defined in Formula VA
above; and R.sup.8, z and m are the same as defied in Formula VI above.
Compounds of Formulae VI and VIA can be readily prepared, e.g. by reaction
of a phenolic compound with an .alpha.,.alpha.-difluoroalkyl sulfonate
reagent (e.g. .alpha.,.alpha.-difluoroalkyl sulfonyl chloride) to thereby
transfer the desired .alpha.,.alpha.-difluoroalkyl moieties onto a
phenolic base compound.
In a yet further aspect, optionally substituted aralkyl sulfonate PAGs are
provided that have one or more .alpha.,.alpha.-difluoroalkyl sulfonate
moieties. Preferred PAGs of this type are benzylic compounds. Such
compounds have one or more .alpha.,.alpha.-difluoroalkyl sulfonate groups
grafted onto one or more benzylic carbons, preferably one or two
.alpha.,.alpha.-difluoroalkyl sulfonate groups on a single phenyl base
group. Preferred benzylic .alpha.,.alpha.-difluoroalkyl sulfonate
compounds include PAGs of the following Formula VII:
##STR13##
wherein R.sup.2 is the same as defined in Formula I above; and R.sup.8, m
and z are the same as defined in Formula VI above.
Preferred compounds of Formula VII include those of the following Formula
VIIA:
##STR14##
wherein R.sup.3, R.sup.4 and R.sup.5 are the same as defined in Formula VIA
above; and R.sup.8, z and m are the same as defined in Formula VII above.
As mentioned above, various substituent groups of PAGs of the invention may
be optionally substituted. Substituted moieties (including substituted
R.sup.1 through R.sup.8) are suitably substituted at one or more available
positions by, e.g., halogen such as F, Cl Br and/or I, alkyl including
C.sub.1-16 alkyl with C.sub.1-8 alkyl being preferred, alkoxy including
C.sub.1-16 alkoxy having one or more oxygen linkages with C.sub.1-8 alkoxy
being preferred, alkenyl including C.sub.2-12 alkenyl with C.sub.2-8
alkenyl being preferred, alkenyl including C.sub.2-12 alkenyl with
C.sub.2-8 alkynyl being preferred, aryl such as phenyl or naphthyl and
substituted aryl such as halo, alkoxy, alkenyl, alkynyl and/or alkyl
substituted aryl, preferably having the number of carbon atoms mentioned
above for corresponding groups. Preferred substituted aryl groups include
substituted phenyl, anthracenyl and naphthyl.
As used herein, the term alkyl unless otherwise modified refers to both
cyclic (alicyclic) and noncyclic groups, although of course cyclic groups
will comprise at least three carbon ring members. Preferred alicyclic
groups include e.g. cyclopentyl, cyclohexyl, and bridged groups such as
adamantyl, and the like. Preferred heteroalicyclic and heteroaromatic
groups of PAGs of the invention include e.g. coumarinyl, quinolinyl,
pyridyl, pyrazinyl, pyrimidyl, furyl, pyrrolyl, thienyl, thiazolyl,
oxazolyl, imidazolyl, indolyl, benzofuranyl, benzothiazol,
tetrahydrofuranyl, tetrahydropyranyl, piperdinyl, morpholino, and
pyrrolindinyl.
As discussed above, novel synthetic methods are provided to produce
.alpha.,.alpha.-difluoroalkyl sulfonate compounds. Preferred synthetic
methods of the invention are exemplified by the following Scheme:
##STR15##
As shown in the above exemplary Scheme, a 1,1-difluoroalkene 2 is reacted
with a sulfur-containing reagent preferably by a free radical mechanism to
provide the .alpha.,.alpha.-difluoroalkyl sulfonate compound 3. References
herein to a 1,1-difluoroalkene mean that two fluoro atoms are directly,
covalently linked to a single alkene carbon, as exemplified by compound 2
above.
Preferably, the alkene carbon with difluoro substitution has a
carbon-carbon double bond to a carbon that is substituted with a "bulky"
substituent shown as R.sup.1 in compound 2 above, such as optionally
substituted C.sub.4-20 alkyl and preferably is an alicyclic group such as
cyclohexyl, adamantyl and the like; optionally substituted carbocyclic
aryl such as optionally substituted phenyl, naphthyl or anthracenyl; or
optionally substituted heteroalicyclic or heteroaromatic preferably having
1 to 3 separate or fused rings with 1-3 hetero (N, O or S) ring members
such as optionally substituted thienyl and the like. The substituent R
shown in the compounds of the above Scheme is suitably hydrogen or a
non-hydrogen substituent such as C.sub.1-8 alkyl, or a group as defined
for R.sup.1 immediately above.
The sulfur reagent that is reacted with the 1,1-difluoroalkene 2 suitably
is a sulfite or bisulfite, which can provide the di-fluoro sulfonic acid 3
directly, i.e. without any active reagent. In the Scheme, the substituent
R.sup.2 can be the same or different than R or R.sup.1. Preferably, R2 is
hydrogen, and R2 may suitably be hydrogen (to provide an aldehyde) or
other group such as C.sub.1-8 alkyl (to provide a ketone). Other suitable
sulfur reagents include thiol acids or thiol compounds such as H.sub.2 S
or CH.sub.3 C(.dbd.O)SH, which suitably are reacted with a
1,1-difluoroalkene reagent in combination with an oxidizing agent such a
peroxide e.g. hydrogen peroxide. For instance, the 1,1-difluoroalkene
compound can be treated in solution with a thiol acid or thiol reagent
followed by addition of the oxidizing agent to the reaction solution See
Example 2 which follows for exemplary preferred reaction conditions.
The 1,1-difluoroalkene 2 can be readily prepared from a corresponding
ketone (i.e. R is C.sub.1-8 alkyl or other non-hydrogen substituent) or
aldehyde compound (i.e. R is hydrogen) 1 e.g. by reaction with a
difluoroacetic acid in the presence of a phosphine e.g. triphenyl
phosphine as generally shown in the above Scheme. The ketone compound 1,
difluoroacetic acid and triphenylphosphine are suitably admixed in a
suitable solvent, e.g. ethylene glycol dimethyl ether, chloroform and the
like stirred for an extended period, e.g. at least about 20, 30, 50, 60,
70, or 90 hours, preferably for at an elevated temperature, e.g. at least
about 40.degree. C. or 50.degree. C., or at reflux. See Example 1 which
follows for exemplary preferred reaction conditions.
The synthesis of the invention also can be carried out as a "one-pot"
procedure, i.e. in synthesis from a starting reagent of a ketone compound
1 or a 1,1-difluoroalkene compound 2 to provide difluoro sulfonic acid 3
in a single reaction vessel without isolation of any intermediate reaction
products.
The formed 1,1-difluoroalkylsulfonic acid then can be reacted with a formed
iodonium cation or sulfonium cation to provide an onium salt of the
invention. Suitably the onium cation compound undergoes an anion exchange
reaction to provide a PAG of the invention. For example, the onium
compound and the 1,1-difluorosulfonic acid can be reacted in a two-phase
system suitably at room temperature for an extended period, e.g. at least
about 5, 10, 15 or 20 hours. See Example 3 which follows for exemplary
preferred reaction conditions.
As discussed above, PAGs of the invention are useful as the radiation
sensitive component in photoresist compositions, including both
positive-acting and negative-acting chemically amplified resist
compositions.
The photoresists of the invention typically comprise a resin binder and a
photoactive component of the invention as described above. Preferably the
resin binder has functional groups that impart alkaline aqueous
developability to the resist composition. For example, preferred are resin
binders that comprise polar functional groups such as hydroxyl or
carboxylate. Preferably the resin binder is used in a resist composition
in an amount sufficient to render the resist developable with an aqueous
alkaline solution.
For imaging at wavelengths greater than 200 nm, such as 248 mm, phenolic
resins are typically preferred. Preferred phenolic resins are poly
(vinylphenols) which may be formed by block polymerization, emulsion
polymerization or solution polymerization of the corresponding monomers in
the presence of a catalyst. Vinylphenols useful for the production of
polyvinyl phenol resins may be prepared, for example, by hydrolysis of
commercially available coumarin or substituted coumarin, followed by
decarboxylation of the resulting hydroxy cinnamic acids. Useful
vinylphenols may also be prepared by dehydration of the corresponding
hydroxy alkyl phenols or by decarboxylation of hydroxy cinnamic acids
resulting from the reaction of substituted or nonsubstituted
hydroxybenzaldehydes with malonic acid. Preferred polyvinylphenol resins
prepared from such vinylphenols have a molecular weight range of from
about 2,000 to about 60,000 daltons.
Copolymers containing phenol and nonaromatic cyclic alcohol units also are
preferred resin binders for resists of the invention and may be suitably
prepared by partial hydrogenation of a novolak or poly(vinylphenol) resin.
Such copolymers and the use thereof in photoresist compositions are
disclosed in U.S. Pat. No. 5,128,232 to Thackeray et al.
Additional suitable resins include those formed from bishydroxymethylated
compounds, and block novolak resins. See U.S. Pat. Nos. 5,130,410 and
5,128,230 where such resins and use of same in photoresist compositions is
disclosed. Additionally, two or more resin binders of similar or different
compositions can be blended or combined together to give additive control
of lithographic properties of a photoresist composition. For instance,
blends of resins can be used to adjust photospeed and thermal properties
and to control dissolution behavior of a resist in a developer.
Preferably, a photoacid generator compound of the invention is employed in
a chemically amplified positive-acting resist. A number of such resist
compositions have been described, e.g., in U.S. Pat. Nos. 4,968,581;
4,883,740; 4,810,613 and 4,491,628 and Canadian Patent Application
2,001,384, all of which are incorporated herein by reference for their
teaching of making and using chemically amplified positive-acting resists.
In accordance with the present invention, those prior resist compositions
are modified by substitution of the photoactive component of the invention
as the radiation sensitive component.
For imaging at wavalengths greater than 200 nm, such as 248 nm, a
particularly preferred chemically amplified photoresist of the invention
comprises in admixture a photoactive component of the invention and a
resin binder that comprises a copolymer containing both phenolic and
non-phenolic units. For example, one preferred group of such copolymers
has acid labile groups substantially, essentially or completely only on
non-phenolic units of the copolymer, particularly alkylacrylate
photoacid-labile groups, i.e. a phenolic-alkyl acrylate copolymer. One
especially preferred copolymer binder has repeating units x and y of the
following formula:
##STR16##
wherein the hydroxyl group be present at either the ortho, meta or para
positions throughout the copolymer, and R' is substituted or unsubstituted
alkyl having 1 to about 18 carbon atoms, more typically 1 to about 6 to 8
carbon atoms. Tert-butyl is a generally preferred R' group. An R' group
may be optionally substituted by e.g. one or more halogen (particularly F,
Cl or Br), C.sub.1-8 alkoxy, C.sub.2-8 alkenyl, etc. The units x and y may
be regularly alternating in the copolymer, or may be randomly interspersed
through the polymer. Such copolymers can be readily formed. For example,
for resins of the above formula, vinyl phenols and a substituted or
unsubstituted alkyl acrylate such as t-butylacrylate and the like may be
condensed under free radical conditions as known in the art. The
substituted ester moiety, i.e. R'--O--C(.dbd.O)--, moiety of the acrylate
units serves as the acid labile groups of the resin and will undergo
photoacid induced cleavage upon exposure of a coating layer of a
photoresist containing the resin. Preferably the copolymer will have a
M.sub.w of from about 8,000 to about 50,000, more preferably about 15,000
to about 30,000 with a molecular weight distribution of about 3 or less,
more preferably a molecular weight distribution of about 2 or less.
Non-phenolic resins, e.g. a copolymer of an alkyl acrylate such as
t-butylacrylate or t-butylmethacrylate and a vinyl alicyclic such as a
vinyl norbornanyl or vinyl cyclohexanol compound, also may be used as a
resin binder in compositions of the invention. Such copolymers also may be
prepared by such free radical polymerization or other known procedures and
suitably will have a M.sub.w of from about 8,000 to about 50,000, and a
molecular weight distribution of about 3 or less.
Another preferred resin binder for a positive chemically amplified resist
of the invention has phenolic and nonaromatic cyclic alcohol units,
wherein at least of portion of the hydroxyl groups of the copolymer are
bonded to acid labile groups. Preferred acid labile moieties are acetate
groups including t-butyl acetate groups of the formula (CH.sub.3).sub.3
COC(O)CH.sub.2 --; oxycarbonyl groups such as t-butyl oxycarbonyl (t-Boc)
groups of the formula (CH.sub.3).sub.3 CC(O)O--; and acetal and ketals.
Chemically amplified positive-acting photoresists containing such a
copolymer have been disclosed in U.S. Pat. No. 5,258,257 to Sinta et al.
Other preferred resins that have acid-labile deblocking groups for use in a
positive-acting chemically-amplified photoresist of the invention have
been disclosed in European Patent Application 0829766A2 of the Shipley
Company (resins with acetal and ketal resins) and European Patent
Application EP0783136A2 of the Shipley Company (terpolymers and other
copolymers including units of 1) styrene; 2) hydroxystyrene; and 3) acid
labile groups, particularly alkyl acrylate acid labile groups such as
t-butylacrylate or t-butylmethacrylate). In general, resins having a
variety of acid labile groups will be suitable, such as acid sensitive
esters, carbonates, ethers, imides, etc. The photoacid labile groups will
more typically be pendant from a polymer backbone, although resins that
have acid labile groups that are integral to the polymer backbone also may
be employed.
PAGs of the invention (which includes PAGs of Formulae I, IA, II, IIA, III,
IIIA, IV, IVA, V, VA, VI, VIA, VII and VIIA as defined above) also are
preferably used with polymers that contain one or more photoacid-labile
groups and that are substantially, essentially or completely free of
phenyl or other aromatic groups. Such photoresist compositions are
particularly useful for imaging with sub-200 nm radiation such as 193 nm
radiation.
For example, preferred polymers contain less than about 5 mole percent
aromatic groups, more preferably less than about 1 or 2 mole percent
aromatic groups, more preferably less than about 0.1, 0.02, 0.04 and 0.08
mole percent aromatic groups and still more preferably less than about
0.01 mole percent aromatic groups. Particularly preferred polymers are
completely free of aromatic groups. Aromatic groups can be highly
absorbing of sub-200 nm radiation and thus are undesirable for polymers
used in photoresists imaged with such short wavelength radiation.
Suitable polymers that are substantially or completely free of aromatic
groups and may be formulated with a PAG of the invention to provide a
photoresist for sub-200 nm imaging are disclosed in European application
EP930542A1 of the Shipley Company.
Suitable polymers that are substantially or completely free of aromatic
groups suitably contain acrylate units such as photoacid-labile acrylate
units as may be provided by polymerization of methyladamantylacrylate,
methyladamantylmethacrylate, ethylfenchylacrylate,
ethylfenchylmethacrylate, and the like; fused non-aromatic alicyclic
groups such as may be provided by polymerization of a norbornene compound
or other alicyclic compound having an endocyclic carbon-carbon double
bond; an anhydride such as may be provided by polymerization of maleic
anhydride; and the like.
Preferred negative-acting compositions of the invention comprise a mixture
of materials that will cure, crosslink or harden upon exposure to acid,
and a photoactive component of the invention.
Particularly preferred negative acting compositions comprise a resin binder
such as a phenolic resin, a crosslinker component and a photoactive
component of the invention. Such compositions and the use thereof has been
disclosed in European Patent Applications 0164248 and 0232972 and in U.S.
Pat. No. 5,128,232 to Thackeray et al. Preferred phenolic resins for use
as the resin binder component include novolaks and poly(vinylphenol)s such
as those discussed above. Preferred crosslinkers include amine-based
materials, including melamine, glycolurils, benzoguanamine-based materials
and urea-based materials. Melamine-formaldehyde resins are generally most
preferred. Such crosslinkers are commercially available, e.g. the melamine
resins sold by American Cyanamid under the trade names Cymel 300, 301 and
303. Glycoluril resins are sold by American Cyanamid under trade names
Cymel 1170, 1171, 1172, urea-based resins are sold under the trade names
of Beetle 60, 65 and 80, and benzoguanamine resins are sold under the
trade names Cymel 1123 and 1125.
Photoresists of the invention also may contain other materials. For
example, other optional additives include actinic and contrast dyes,
anti-striation agents, plasticizers, speed enhancers, sensitizers (e.g.
for use of a PAG of the invention at longer wavelenghs such as I-line),
etc. Such optional additives typically will be present in minor
concentration in a photoresist composition except for fillers and dyes
which may be present in relatively large concentrations such as, e.g., in
amounts of from 5 to 30 percent by weight of the total weight of a
resist's dry components.
A preferred optional additive of resists of the invention is an added base,
particularly tetrabutylammonium hydroxide (TBAH), which can enhance
resolution of a developed resist relief image. The added base is suitably
used in relatively small amounts, e.g. about 1 to 10 percent by weight
relative to the PAG, more typically 1 to about 5 weight percent. Other
preferred basic additives include ammonium sulfonate salts such as
piperidinium p-toluenesulfonate and dicyclohexylammonium
p-toluenesulfonate; alkyl amines such as tripropylamine and dodecylamine;
aryl amines such as diphenylamine, triphenylamine, aminophenol,
2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, etc.
The resin binder component of resists of the invention are typically used
in an amount sufficient to render an exposed coating layer of the resist
developable such as with an aqueous alkaline solution. More particularly,
a resin binder will suitably comprise 50 to about 90 weight percent of
total solids of the resist. The photoactive component should be present in
an amount sufficient to enable generation of a latent image in a coating
layer of the resist. More specifically, the photoactive component will
suitably be present in an amount of from about 1 to 40 weight percent of
total solids of a resist. Typically, lesser amounts of the photoactive
component will be suitable for chemically amplified resists.
The photoresists of the invention are generally prepared following known
procedures with the exception that a PAG of the invention is substituted
for prior photoactive compounds used in the formulation of such
photoresists. For example, a resist of the invention can be prepared as a
coating composition by dissolving the components of the photoresist in a
suitable solvent such as, e.g., a glycol ether such as 2-methoxyethyl
ether (diglyme), ethylene glycol monomethyl ether, propylene glycol
monomethyl ether; lactates such as ethyl lactate or methyl lactate, with
ethyl lactate being preferred; proponiates, particularly methyl
propionate, ethyl propionate and ethyl ethoxy propionate; or a ketone such
as methylethyl ketone, cyclohexanone and 2-heptanone. Typically the solids
content of the photoresist varies between 5 and 35 percent by weight of
the total weight of the photoresist composition.
The photoresists of the invention can be used in accordance with known
procedures. Though the photoresists of the invention may be applied as a
dry film, they are preferably applied on a substrate as a liquid coating
composition, dried by heating to remove solvent preferably until the
coating layer is tack free, exposed through a photomask to activating
radiation, optionally post-exposure baked to create or enhance solubility
differences between exposed and nonexposed regions of the resist coating
layer, and then developed preferably with an aqueous alkaline developer to
form a relief image.
The substrate on which a resist of the invention is applied and processed
suitably can be any substrate used in processes involving photoresists
such as a microelectronic wafer. For example, the substrate can be a
silicon, silicon dioxide or aluminum-aluminum oxide microelectronic wafer.
Gallium arsenide, ceramic, quartz or copper substrates may also be
employed. Printed circuit board substrates such as copper clad laminates
are also suitable substrates. Substrates used for liquid crystal display
and other flat panel display applications are also suitably employed, e.g.
glass substrates, indium tin oxide coated substrates and the like.
A liquid coating resist composition may be applied by any standard means
such as spinning, dipping or roller coating. Photoresists of the invention
also may be applied as dry film resists, particularly for printed circuit
board manufacture applications. The exposure energy should be sufficient
to effectively activate the photoactive component of the radiation
sensitive system to produce a patterned image in the resist coating layer.
Suitable exposure energies typically range from about 1 to 300
mJ/cm.sup.2. Suitable exposure wavelengths include sub-300 nm such as 248
nm or sub-200 nm such as 193 nm and 157 mm, or longer wavelengths such as
365 nm. Higher energy exposure sources also may be employed such as EUV,
electron beam, ion beam and x-ray radiation, and other ionizing radiation.
Suitable post-exposure bake temperatures are from about 50.degree. C. or
greater, more specifically from about 50 to 140.degree. C. For an
acid-hardening negative-acting resist, a post-development bake may be
employed if desired at temperatures of from about 100 to 150.degree. C.
for several minutes or longer to further cure the relief image formed upon
development. After development and any post-development cure, the
substrate surface bared by development may then be selectively processed,
for example chemically etching or plating substrate areas bared of
photoresist in accordance with procedures known in the art. Suitable
etchants include a hydrofluoric acid etching solution and a plasma gas
etch such as an oxygen plasma etch.
All documents mentioned herein are incorporated herein by reference. The
following non-limiting examples are illustrative of the invention.
EXAMPLES 1-3
PAG Syntheses
Example 1
Synthesis of 1,1-difluoro-2-(1-naphthyl)ethenylene (compound 2 shown in the
above Scheme where R is naphthyl).
An oven-dried 250 mL, one-neck flask was fitted with a magnetic stir bar, a
reflux condenser, and a nitrogen inlet. The flask was charged with freshly
distilled 1-naphthaldehyde (17.1 g, 109 mmol), chlorodifluoroacetic acid
sodium salt (25 g, 164 mmol), and triphenylphosphine (31.4 g, 120 mmol).
Ethylene glycol dimethyl ether (75 mL) was added and the mixture was
refluxed for 96 hours during which time a precipitate formed and the
reaction tuned dark brown. The cooled mixture was filtered and the
filtered solution was concentrated to afford a dark semi-solid.
Distillation (62-67.degree. C., 1 mm) afforded the title compound as a
colorless liquid (14.1 g, 68%). NMR (CDCl.sub.3): .delta. 7.3-8.0 (m, 7M,
5.83 (dd, J.sub.1 =18 Hz), J.sub.2 =3 Hz); MS: M.sup.+ =190.
Example 2
Synthesis of 1,1-difluoro-1-sulfonic acid-2-(1-naphthyl)ethylene (compound
3 shown in the above Scheme where R is naphthyl).
A two-phase mixture of the compound of Example 1, i.e.
1,1-difluoro-2-(1-naphthyl)ethenylene (8.4 g, 44.2 mmol), sodium sulfite
(28 g, 222 mmol), and benzoyl peroxide (1.1 g, 4.5 mmol) in water (200 mL)
was heated for 67 hours at 85.degree. C. The light yellow reaction mixture
was filtered and the solid was suspended in tetrahydrofuran (950 mL) and
the suspension was refluxed for 30 minutes. The cooled suspension was
filtered and the filtrate was concentrated to afford a light tan solid.
The solid was triturated with chloroform (500 mL) and the colorless solid
obtained by filtration was dried to afford the desired product (2.85 g,
22%). NMR (DMSO-d.sub.6): .delta. 7.3-8.0 (m, 7H), 5.83 (dd, J.sub.1 =18
Hz, J.sub.2 =3 Hz); MS: M.sup.+ =190.
Example 3
Synthesis of Di(4-tert-butylphenyl)-iodonium
1,1-difluoro-1-sulfonate-2-(1-naphthyl)ethylene (compound of Formula IA
where R=R.sup.1 =4-t-butylphenyl; R.sup.3 =naphthyl; R.sup.4 =R.sup.5 =H)
A solution of the product of Example 2, i.e. 1,1-difluoro-1-sulfonic
acid-2-(1-naphthyl)ethylene (8.3 g, 21.4 mmol), in dichloromethane (250
mL) was treated with a solution of di(4-tert-butylphenyl)-iodonium sulfate
(9.04 g, 20 mmol) in water (150 mL). The two-phase mixture was vigorously
stirred for 17 hours at room temperature, and then the pH of the aqueous
phase was adjusted to 7-8 using concentrated aqueous ammonium hydroxide.
The layers were separated and the organic layer was washed with water
(1.times.200 mL). The combined aqueous extracts were extracted with
dichloromethane (1.times.200 mL) which was then combined with the
previously obtained organic phase. The combined organic extracts were
concentrated to afford a tan solid. Recrystallization from benzene/hexane
and then ethyl acetate/hexane afforded the desired compound as a light
yellow powder (9.7 g, 73%).
Example 4
Photoresist Preparation and Lithographic Processing
A photoresist of the invention is prepared by mixing the following
components with amounts expressed as weight percent based on total weight
of the resist compositions:
Resist components Amount (wt. %)
Resin binder 15
Photoacid generator 3
Ethyl lactate 81
The resin binder is a terpolymer consisting of polymerized vinylphenol
units, styrene units and t-butylacrylate. The photoacid generator was the
compound prepared in Example 3 above. Those resin and PAG components are
admi
