U.S. patent application number 15/645691 was filed with the patent office on 2018-02-22 for onium compounds and methods of synthesis thereof.
The applicant listed for this patent is Rohm and Haas Electronic Materials LLC. Invention is credited to Paul J. Labeaume.
Application Number | 20180052390 15/645691 |
Document ID | / |
Family ID | 50274819 |
Filed Date | 2018-02-22 |
United States Patent
Application |
20180052390 |
Kind Code |
A1 |
Labeaume; Paul J. |
February 22, 2018 |
ONIUM COMPOUNDS AND METHODS OF SYNTHESIS THEREOF
Abstract
New onium salt compounds and methods for synthesis of such
compounds are provided. Preferred methods of the invention include
(a) providing an onium salt compound comprising a sulfonate
component having an electron withdrawing group; and (b) treating
the onium salt compound with a halide salt to form a distinct salt
of the onium compound. The present onium compounds are useful as an
acid generator component of a photoresist composition.
Inventors: |
Labeaume; Paul J.;
(Marlborough, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Rohm and Haas Electronic Materials LLC |
Marlborough |
MA |
US |
|
|
Family ID: |
50274819 |
Appl. No.: |
15/645691 |
Filed: |
July 10, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14027361 |
Sep 16, 2013 |
9703192 |
|
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15645691 |
|
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61701612 |
Sep 15, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03F 7/38 20130101; G03F
7/0397 20130101; G03F 7/039 20130101; G03F 7/168 20130101; C07C
309/12 20130101; G03F 7/0392 20130101; C07C 309/12 20130101; C07D
335/16 20130101; C07C 303/32 20130101; G03F 7/322 20130101; C08K
5/45 20130101; G03F 7/0382 20130101; G03F 7/2004 20130101; G03F
7/0046 20130101; G03F 7/0045 20130101; G03F 7/162 20130101; C07C
2603/74 20170501; C07C 303/32 20130101 |
International
Class: |
G03F 7/004 20060101
G03F007/004; C07D 335/16 20060101 C07D335/16; C07C 309/12 20060101
C07C309/12; C08K 5/45 20060101 C08K005/45; G03F 7/039 20060101
G03F007/039; G03F 7/16 20060101 G03F007/16; G03F 7/20 20060101
G03F007/20; G03F 7/38 20060101 G03F007/38; G03F 7/32 20060101
G03F007/32 |
Claims
1-6. (canceled)
7. A method of preparing a photoresist composition, comprising
admixing a treated onium compound with a polymer to provide a
photoresist composition, wherein the treated onium compound is
obtainable by steps comprising: (a) providing an onium salt
compound comprising a sulfonate component, wherein the sulfonate
component comprises an electron withdrawing group; and (b) treating
the onium salt compound with a halide salt to form the treated
onium compound that is a distinct salt of the onium salt
compound.
8. A photolithographic method comprising: (i) applying a coating
layer of a photoresist composition prepared in accordance with
claim 7 on a substrate surface; (ii) exposing the photoresist
composition to activating radiation; and (iii) developing the
exposed photoresist composition layer to provide a resist relief
image.
9. An onium salt compound, obtainable by a method comprising: (a)
providing an onium salt comprising a sulfonate component, wherein
the sulfonate component comprises an electron withdrawing group;
(b) treating the sulfonate salt with a halide salt to form a halide
salt of the onium compound; and (c) treating the halide salt of the
onium compound to form a distinct salt of the onium compound.
10. A photoresist comprising a polymer and an onium salt compound
of claim 9.
11. The method of claim 7 wherein the wherein the treated onium
compound is obtained by the steps.
Description
1. FIELD
[0001] The present invention relates to new onium salt compounds
and methods for synthesis of such compounds. Onium compounds of the
invention are useful as an acid generator component of a
photoresist composition.
2. INTRODUCTION
[0002] 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.
[0003] Photoresists typically contain a resin component and an acid
generator compound component. Onium salt compounds have been
utilized as a photoresist acid generator component. See U.S. Pat.
No. 6,929,896; 2010/0143843; and 2012/0015297.
[0004] Known photoresists can provide features having resolution
and dimension 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.
[0005] 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 U.S.
20070224540 and EP 1906241. Extreme ultraviolet (EUV) and e-beam
imaging technologies also have been employed. See U.S. Pat. No.
7,459,260. EUV utilizes short wavelength radiation, typically
between 1 nm to 40 nm, with 13.5 nm radiation often employed.
[0006] It would be desirable to have improved photoresist
compositions, including improved routes to photoresist photoactive
components.
SUMMARY
[0007] We have now discovered new methods for synthesis of onium
salt compounds. We also provide new onium salt acid generator
compounds and photoresist composition comprising such acid
generators.
[0008] Among other things, methods of the invention can provide
convenient change of strong acid anion components of an onium salt
compound to provide an onium compound with a distinct anion
component.
[0009] More particularly, in one aspect, methods for preparing an
onium salt compound are provided comprising: (a) providing an onium
salt compound comprising a sulfonate component, wherein the
sulfonate component comprises an electron withdrawing group; and
(b) treating the onium salt compound with a halide salt to form a
distinct salt of the onium compound.
[0010] In such methods, preferably the sulfonate anion component of
the onium compound comprises one or more electron withdrawing
groups on a carbon atom alpha to an SO.sub.3-moiety. Suitable
electron withdrawing groups include one or more halogen atoms
(especially fluoro); cyano; nitro; and alkyl such as
C.sub.1-20alkyl substituted with one or more halogen (especially
fluoro), nitro and/or cyano.
[0011] In the methods of the invention, the onium salt compound may
be treated with varying halide salts such as Br, Cl and I salts,
with iodide salts preferred.
[0012] The onium salt may be treated with a halide salt in a
variety of ways, suitably to permit displacement of an anion
component of the onium salt compound with the halide anion of the
halide salt to thereby form the distinct salt of the onium
compound. That is, the distinct salt of the onium compound will
have a different anion component (e.g. halide such as I.sup.-) than
the anion component (e.g. triflate (CF.sub.3SO.sub.3.sup.-)) of the
provided onium salt compound.
[0013] In one suitable treatment method, the onium salt compound is
washed with a fluid solution comprising the halide salt. Such
washing may be suitably carried out in a variety of ways e.g. by
admixing an organic solvent solution of the onium salt compound
with an aqueous solution comprising the halide salt (e.g. 1, 2 or
3M aqueous solution of the halide salt) for a time and conditions
(such as agitation or stirring) sufficient to form a distinct salt
of the onium compound.
[0014] A desired distinct salt of the onium compound also may be
formed through further processing following the halide salt
treatment. For instance, a formed halide salt of the onium compound
may undergo an additional anion displacement reaction to provide an
onium salt compound that is distinct from both 1) the first onium
salt compound provided for treatment with the halide salt, and 2)
the halide salt formed from the first onium salt compound. In other
words, the formed halide salt of the provided onium salt compound
may function as an intermediate for synthesis of other onium salt
compounds with differing anion components.
[0015] Methods of the invention may include treatment and forming
of a variety of onium compounds, including those having sulfonium
cation components as well as iodonium cation components. Suitable
sulfonium cation components may include non-cyclic sulfonium
moieties where the sulfonium atom (S.sup.+) may be substituted by
non-aromatc (e.g. optionally substituted alkyl) and aromatic (e.g.
optionally substituted phenyl or naphthyl), cyclic sulfonium
moieties (e.g. aromatic or non-aromatic 5- or 6-member rings that
comprise carbon ring atoms and at least one S.sup.+ ring member),
and/or thioxanthone moieties.
[0016] Additional suitable cation components of acid generators of
the invention may include those of the following formula
##STR00001##
[0017] wherein in that formula X is C.dbd.O, S(O), SO.sub.2,
C(.dbd.O)O, C(.dbd.O)NH, C(.dbd.O)--C(.dbd.O)--, or --O--; and R is
a non-hydrogen substituent such as optionally substituted
carbocyclic aryl including phenyl and optionally substituted alkyl,
including C.sub.1-20 optionally substituted alkyl.
[0018] Photoresist compositions and methods for preparing
photoresist compositions also are provided. Particularly preferred
photoresists of the invention may comprise an imaging-effective
amount of one or more onium salt compounds as disclosed herein and
a suitable polymer component. Photoresists of the invention also
may comprise a mixture of differing onium salt compounds, typically
a mixture of 2 or 3 different onium salt compounds, more typically
a mixture that consists of a total of 2 differing onium salt
compounds.
[0019] In preferred aspects, onium salt compounds and photoresists
of the invention are utilized for EUV imaging. Photoresists
comprising one or more onium salt compounds as disclosed herein
also may be imaged with other radiation sources such as 193 nm and
e-beam radiation.
[0020] Methods are also provided for forming relief images of
photoresist compositions of the invention (including patterned
lines with sub sub-50 nm or sub-20 nm dimensions). Substrates such
as a microelectronic wafer also are provided having coated thereon
a photoresist composition of the invention.
DETAILED DESCRIPTION
[0021] We have found that prior onium salt syntheses can have
certain limitations, including producing a triflate salt onium acid
generator, where the triflate can be difficult to displace with
another desired anion component. As discussed above, such
shortcomings of prior approaches can be addressed by the present
methods which can effectively replace a strong acid anion component
of an onium salt compound as desired.
[0022] More particularly, we now provide new methods for methods
for preparing onium salt compounds which comprise: (a) providing an
onium salt compound comprising a sulfonate component, wherein the
sulfonate component comprises an electron withdrawing group; and
(b) treating the onium salt compound with a halide salt to form a
distinct salt of the onium compound.
[0023] In certain aspects, the provided onium compound is a
triflate salt (i.e. CF.sub.3SO.sub.3.sup.- anion component) and is
treated with an iodide salt such as sodium iodide, potassium iodide
or ammonium iodide. Suitable halide salt treatment of the onium
compound can include contact with a fluid solution comprising the
iodide salt. Preferably, the onium salt is contacted such as by
washing multiple times (e.g., 2, 3, 4, 5 or more times) with an
aqueous solution of the halide salt, although a single wash or
other single exposure with the halide salt also may be employed. As
discussed above, halide salt solutions of varying concentrations
may be suitably employed, e.g. 1, 2, 3 or 4M aqueous solution of
the halide salt. Treatment of the onium compound with a halide salt
can be suitably conducted under relatively mild conditions, e.g. at
room temperature (25.degree. C.).
[0024] We have found that such halide anion treatment can displace
strong acids such as triflate or other activated sulfonate from the
onium cation component enabling formation of a distinct onium
compound, i.e. the onium cation component complexed with a
different anion component (e.g. different than the triflate anion
of the provided onium compound).
[0025] We also found that use of an iodide salt can provide
enhanced results relative to other salts evaluated for displacement
of a strong acid anion component of an onium salt compound. Other
salts evaluated included chloride, bromide and acetate salts. Thus,
we found that iodide salt treatment of a triflate salt sulfonium
compound resulted in enhanced displacement of the triflate anion
relative to comparable treatment with chloride, bromide or acetate
salts. Enhanced displacement included higher yield of a distinct
sulfonium salt (i.e. distinct from the triflate salt) while using a
comparatively reduced number of salt washing cycles.
[0026] As discussed above, in the present methods, preferred
sulfonate anion components of the provided onium compound may
comprise one or more electron withdrawing groups. Suitable electron
withdrawing groups include one or more halogen atoms; cyano; nitro;
and alkyl such as C.sub.1-20alkyl substituted with one or more
halogen (especially fluoro), nitro and/or cyano. Halogen
particularly fluoro and C.sub.1-20alkyl substituted with one or
more halogen (especially fluoro) are often preferred. Preferred
sulfonate components of the provided onium compound may comprise a
triflate moiety as well as other fluorinated alkylsulfonate groups,
such as alkylsulfonate having 1-20 carbons and 1-20 or more
fluorine atoms, including perfluorinated alkylsulfonate groups.
[0027] In a preferred aspect, the sulfonate anion component of a
provided onium compound is of the following general formula
(I):
##STR00002##
[0028] wherein R.sub.1 and R.sub.3 are independently selected from
hydrogen, halogen, cyano, nitro, optionally substituted alkyl, and
optionally substituted carbocyclic aryl; R.sub.2 is the same or
different than R.sub.1 and R.sub.3 and is selected from a linker
moiety, hydrogen, halogen, cyano, nitro, optionally substituted
alkyl, and optionally substituted carbocyclic aryl, and wherein at
least one R.sub.1, R.sub.2 and R.sub.3 is an electron withdrawing
group. In preferred embodiments, one or more of R.sub.1, R.sub.2
and R.sub.3 are halogen or halogenated alkyl, such as fluorine and
fluorinated alkyl e.g. having 1 to 20 carbons and 1 to 20 or more
fluorine atoms, including perfluorinated alkyl.
[0029] In a further preferred aspect, the anion component of a
provided onium compound may be a sulfonate of the following general
formula (II):
##STR00003##
[0030] wherein in formula (II) each R is the same or different and
is an electron-withdrawing group such as halogen, cyano, nitro, or
a substituted alkyl; or other optionally substituted alkyl or
optionally substituted carbocyclic aryl, with at least one R being
an electron-withdrawing moiety; and m is an integer of from 1 to 5.
In preferred embodiments, one or more R groups are halogen or
halogenated alkyl, such as fluorine and fluorinated alkyl e.g.
having 1 to 20 carbons and 1 to 20 or more fluorine atoms,
including perfluorinated alkyl.
[0031] The present invention also provides onium salt compounds as
may be suitably obtainable by methods disclosed herein.
[0032] More particularly, iodide salt onium compounds are provided,
obtainable by methods comprising:
[0033] (a) providing an onium salt compound comprising a sulfonate
component, wherein the sulfonate component comprises an electron
withdrawing group; and
[0034] (b) treating the onium salt compound with a halide salt to
form a distinct salt of the onium compound
[0035] Additional onium salt compounds also are provided,
obtainable by methods comprising:
[0036] (a) providing an onium salt comprising a sulfonate
component, wherein the sulfonate component an electron withdrawing
group;
[0037] (b) treating the sulfonate salt with a halide salt to form a
halide salt of the onium compound; and
[0038] (c) treating the halide salt of the onium compound to form a
distinct salt of the onium compound.
Photoresist Compositions
[0039] As discussed above, onium salt compounds as disclosed herein
are useful as the radiation sensitive component in photoresist
compositions, including both positive-acting and negative-acting
chemically amplified resist compositions.
[0040] The photoresists of the invention typically comprise a
polymer and one or more onium salt compound as disclosed herein
that function as acid generators during lithographic processing.
Preferably the polymer has functional groups that impart alkaline
aqueous developability to the resist composition. For example,
preferred are polymers that comprise polar functional groups such
as hydroxyl or carboxylate, or acid-labile groups that can liberate
such polar moieties upon lithographic processing. Preferably the
polymer is used in a resist composition in an amount sufficient to
render the resist developable with an aqueous alkaline
solution.
[0041] Onium salt compounds of the invention are also suitably used
with polymers that comprise repeat units containing aromatic
groups, such as optionally substituted phenyl including phenol,
optionally substituted naphthyl, and optionally substituted
anthracene. Optionally substituted phenyl (including phenol)
containing polymers are particularly suitable for many resist
systems, including those imaged with EUV and e-beam radiation. For
positive-acting resists, the polymer also preferably contains one
or more repeat units that comprise acid-labile groups. For example,
in the case of polymers containing optionally substituted phenyl or
other aromatic groups, a polymer may comprise repeat units that
contain one or more acid-labile moieties such as a polymer that is
formed by polymerization of acrylate or methacrylate monomers that
comprise an acid-labile ester (e.g. t-butyl acrylate or
methacrylate). Such monomers may be copolymerized with one or more
other monomers that comprise aromatic group(s) such as optionally
phenyl, e.g. a styrene or vinyl phenol monomer.
[0042] Preferred monomers used for the formation of such polymers
include: an acid-deprotectable monomer having the formula (V), a
lactone-containing monomer of the formula (VI), a base-soluble
monomer of formula (VII) for adjusting dissolution rate in alkaline
developer, and an acid-generating monomer of the formula (VIII), or
a combination comprising at least one of the foregoing
monomers:
##STR00004##
wherein each R.sup.a is independently H, F, --CN, C.sub.1-10 alkyl,
or C.sub.1-10 fluoroalkyl. In the acid-deprotectable monomer of
formula (V), R.sup.b is independently C.sub.1-20 alkyl, C.sub.3-20
cycloalkyl, C.sub.6-20 aryl, or C.sub.7-20 aralkyl, and each
R.sup.b is separate or at least one R.sup.b is bonded to an
adjacent R.sup.b to form a cyclic structure. In lactone-containing
monomer of formula (VI), L is a monocyclic, polycyclic, or fused
polycyclic C.sub.4-20 lactone-containing group. In the base
solubilizing monomer of formula (VII), W is a halogenated or
non-halogenated, aromatic or non-aromatic C.sub.2-50
hydroxyl-containing organic group having a pKa of less than or
equal to 12. In the acid generating monomer of formula (VIII), Q is
ester-containing or non-ester containing and fluorinated or
non-fluorinated and is C.sub.1-20 alkyl, C.sub.3-20 cycloalkyl,
C.sub.6-20 aryl, or C.sub.7-20 aralkyl group, A is ester-containing
or non-ester-containing and fluorinated or non-fluorinated, and is
C.sub.1-20 alkyl, C.sub.3-20 cycloalkyl, C.sub.6-20 aryl, or
C.sub.7-20 aralkyl, T is an anionic moiety comprising carboxylate,
sulfonate, an anion of a sulfonamide, or an anion of a sulfonimide,
and G.sup.+ is a sulfonium or iodonium cation.
[0043] Exemplary acid-deprotectable monomers include but are not
limited to:
##STR00005##
or a combination comprising at least one of the foregoing, wherein
R.sup.a is H, F, --CN, C.sub.1-6 alkyl, or C.sub.1-6
fluoroalkyl.
[0044] Suitable lactone monomers may be of the following formula
(IX):
##STR00006##
wherein R.sup.a is H, F, --CN, C.sub.1-6 alkyl, or C.sub.1-6
fluoroalkyl, R is a C.sub.1-10 alkyl, cycloalkyl, or
heterocycloalkyl, and w is an integer of 0 to 5. In formula (IX), R
is attached directly to the lactone ring or commonly attached to
the lactone ring and/or one or more R groups, and the ester moiety
is attached to the lactone ring directly, or indirectly through
R.
[0045] Exemplary lactone-containing monomers include:
##STR00007##
or a combination comprising at least one of the foregoing monomers,
wherein R.sup.a is H, F, --CN, C.sub.1-10 alkyl, or C.sub.1-10
fluoroalkyl.
[0046] Suitable base-soluble monomers may be of the following
formula (X):
##STR00008##
wherein each R.sup.a is independently H, F, --CN, C.sub.1-10 alkyl,
or C.sub.1-10 fluoroalkyl, A is a hydroxyl-containing or
non-hydroxyl containing, ester-containing or non ester-containing,
fluorinated or non-fluorinated C.sub.1-20 alkylene, C.sub.3-20
cycloalkylene, C.sub.6-20 arylene, or C.sub.7-20 aralkylene, and x
is an integer of from 0 to 4, wherein when x is 0, A is a
hydroxyl-containing C.sub.6-20 arylene.
[0047] Exemplary base soluble monomers include those having the
following structures:
##STR00009##
or a combination comprising at least one of the foregoing, wherein
R.sup.a is H, F, --CN, C.sub.1-6 alkyl, or C.sub.1-6
fluoroalkyl.
[0048] Preferred acid generating monomer include those of the
formulae (XI) or (XII):
##STR00010##
wherein each R.sup.a is independently H, F, --CN, C.sub.1-6 alkyl,
or C.sub.1-6 fluoroalkyl, A is a fluorine-substituted C.sub.1-30
alkylene group, a fluorine-substituted C.sub.3-30 cycloalkylene
group, a fluorine-substituted C.sub.6-30 arylene group, or a
fluorine-substituted C.sub.7-30 alkylene-arylene group, and G.sup.+
is a sulfonium or iodonium cation.
[0049] Preferably, in formulas (XI) and (XII), A is a
--[(C(R.sup.1).sub.2).sub.b--C(.dbd.O)O].sub.b--C((R.sup.2).sub.2).sub.y(-
CF.sub.2).sub.z-- group, or an o-, m- or p-substituted
--C.sub.6F.sub.4-- group, where each R.sup.1 and R.sup.2 are each
independently H, F, --CN, C.sub.1-6 fluoroalkyl, or C.sub.1-6
alkyl, b is 0 or 1, x is an integer of 1 to 10, y and z are
independently integers of from 0 to 10, and the sum of y+z is at
least 1.
[0050] Exemplary preferred acid generating monomers include:
##STR00011##
or a combination comprising at least one of the foregoing, where
each R.sup.a is independently H, F, --CN, C.sub.1-6 alkyl, or
C.sub.1-6 fluoroalkyl, k is suitably an integer of from 0 to 5; and
G.sup.+ is a sulfonium or iodonium cation.
[0051] Preferred acid-generating monomers may include sulfonium or
iodonium cation. Preferably, in formula (IV), G.sup.+ is of the
formula (XIII):
##STR00012##
wherein X is S or I, each R.sup.0 is halogenated or non-halogenated
and is independently C.sub.1-30 alkyl group; a polycyclic or
monocyclic C.sub.3-30 cycloalkyl group; a polycyclic or monocyclic
C.sub.4-30 aryl group; or a combination comprising at least one of
the foregoing, wherein when X is S, one of the R.sup.0 groups is
optionally attached to one adjacent R.sup.0 group by a single bond,
and a is 2 or 3, wherein when X is I, a is 2, or when X is S, a is
3.
[0052] Exemplary acid generating monomers include those having the
formulas:
##STR00013##
wherein R.sup.a is H, F, --CN, C.sub.1-6 alkyl, or C.sub.1-6
fluoroalkyl.
[0053] Suitable polymers that have acid-labile deblocking groups
for use in positive-acting chemically amplified photoresists of the
invention also have been disclosed in European Patent Application
0829766A2 (polymers with acetal and ketal polymers) and European
Patent Application EP0783136A2 (terpolymers and other copolymers
including units of 1) styrene, 2) hydroxystyrene, and 3) acid
labile groups, particularly alkyl acrylate acid labile groups such
as polymerized t-butylmethacrylate and
methyladamantylmethacrylate.
[0054] Polymers for use in photoresists of the invention may
suitably vary widely in molecular weight and polydisperity.
Suitable polymers include those that have a M.sub.w of from about
1,000 to about 50,000, more typically about 2,000 to about 30,000
with a molecular weight distribution of about 3 or less, more
typically a molecular weight distribution of about 2 or less.
[0055] 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. Preferred negative acting compositions comprise a
polymer binder such as a phenolic or non-aromatic polymer, a
crosslinker component and a photoactive component of the invention.
Such compositions and the use thereof have been disclosed in
European Patent Applications 0164248 and U.S. Pat. No. 5,128,232 to
Thackeray et al. Preferred phenolic polymers for use as the polymer
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 polymers
are often particularly suitable. Such crosslinkers are commercially
available, e.g. the melamine polymers, glycoluril polymers,
urea-based polymer and benzoguanamine polymers, such as those sold
by Cytec under tradenames Cymel 301, 303, 1170, 1171, 1172, 1123
and 1125 and Beetle 60, 65 and 80.
[0056] For imaging at 193 nm, suitable polymer components may be
substantially free of aromatic content, e.g. less than 20, 10, 5 or
1 percent of total repeat units of the polymer used in the resist
containing phenyl or other aromatic groups. See U.S. Pat. Nos.
7,208,261 and 7,968,268 for exemplary suitable photoresist
compositions for imaging with 193 nm radiation.
[0057] 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, photodestroyable bases etc. Such optional
additives typically will be present in minor concentration in a
photoresist composition.
[0058] Inclusion of base materials, preferably the carboxylate or
sulfonate salts of photo-decomposable cations, provides a mechanism
for neutralization of acid from the acid decomposable groups, and
limits the diffusion of the radiation-generated acid, to thereby
provide improved contrast in the photoresist.
[0059] Photo-destroyable bases include photo-decomposable cations,
and preferably those also useful for preparing PAGs, paired with an
anion of a weak (pKa >2) acid such as, for example, a C.sub.1-20
carboxylic acid. Exemplary such carboxylic acids include formic
acid, acetic acid, propionic acid, tartaric acid, succinic acid,
cyclohexylcarboxylic acid, benzoic acid, salicylic acid, and other
such carboxylic acids.
[0060] Alternatively, or in addition, other additives may include
quenchers that are non-photo-destroyable bases, such as, for
example, those based on hydroxides, carboxylates, amines, imines,
and amides. Preferably, such quenchers include C.sub.1-30 organic
amines, imines, or amides, or may be a C.sub.1-30 quaternary
ammonium salt of a strong base (e.g., a hydroxide or alkoxide) or a
weak base (e.g., a carboxylate). Exemplary quenchers include amines
such as tripropylamine, dodecylamine,
1,1',1'',1'''-(ethane-1,2-diylbis(azanetriyl))tetrapropan-2-ol;
aryl amines such as diphenylamine, triphenylamine, aminophenol, and
2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, Troger's base, a
hindered amine such as diazabicycloundecene (DBU) or
diazabicyclononene (DBN), or ionic quenchers including quaternary
alkyl ammonium salts such as tetrabutylammonium hydroxide (TBAH) or
tetrabutylammonium lactate.
[0061] Surfactants include fluorinated and non-fluorinated
surfactants, and are preferably non-ionic. Exemplary fluorinated
non-ionic surfactants include perfluoro C.sub.4 surfactants such as
FC-4430 and FC-4432 surfactants, available from 3M Corporation; and
fluorodiols such as POLYFOX PF-636, PF-6320, PF-656, and PF-6520
fluorosurfactants from Omnova.
[0062] The photoresist further includes a solvent generally
suitable for dissolving, dispensing, and coating the components
used in a photoresists. Exemplary solvents include anisole,
alcohols including ethyl lactate, 1-methoxy-2-propanol, and
1-ethoxy-2 propanol, esters including n-butylacetate,
1-methoxy-2-propyl acetate, methoxyethoxypropionate,
ethoxyethoxypropionate, ketones including cyclohexanone and
2-heptanone, and a combination comprising at least one of the
foregoing solvents.
[0063] Such photoresists may include a polymer component in an
amount of 50 to 99 wt %, specifically 55 to 95 wt %, more
specifically 60 to 90 wt %, and still more specifically 65 to 90
based on the total weight of solids. The photo-destroyable base may
be present in the photoresist in an amount of 0.01 to 5 wt %,
specifically 0.1 to 4 wt %, and still more specifically 0.2 to 3 wt
%, based on the total weight of solids. A surfactant may be
included in an amount of 0.01 to 5 wt %, specifically 0.1 to 4 wt
%, and still more specifically 0.2 to 3 wt %, based on the total
weight of solids. A quencher may be included in relatively small
amounts of for example, from 0.03 to 5 wt % based on the total
weight of solids. Other additives may be included in amounts of
less than or equal to 30 wt %, specifically less than or equal to
20%, or more specifically less than or equal to 10%, based on the
total weight of solids. The total solids content for the
photoresist composition may be 0.5 to 50 wt %, specifically 1 to 45
wt %, more specifically 2 to 40 wt %, and still more specifically 5
to 30 wt %, based on the total weight of solids and solvent. The
acid generator compound(s) should be present in an amount
sufficient to enable generation of a latent image in a coating
layer of the resist. More specifically, the one or more onium
compounds will suitably be present in an amount of from about 1 to
50 weight percent of total solids of a resist. It will be
understood that the solids includes polymer, photo-destroyable
base, quencher, surfactant, onium salt compound, and any optional
additives, exclusive of solvent.
[0064] A coated substrate may be formed from the photoresist
containing onium salt compounds(s) which should be present in an
amount sufficient to enable generation of a latent image in a
coating layer of the resist and onium salt compound(s). Such a
coated substrate includes: (a) a substrate having one or more
layers to be patterned on a surface thereof; and (b) a layer of the
photoresist composition including the acid generator compound over
the one or more layers to be patterned. For EUV or e beam imaging,
photoresists may suitably have relatively higher content of onium
salt compound(s), e.g. where the one or more onium salt compounds
comprise 5 to 10 to about 50 weight percent of total solids of the
resist. Typically, lesser amounts of the photoactive component will
be suitable for chemically amplified resists.
[0065] The photoresists of the invention are generally prepared
following known procedures with the exception that one or more one
salt compounds of the invention are substituted for prior
photoactive compounds used in the formulation of such photoresists.
The photoresists of the invention can be used in accordance with
known procedures.
[0066] Substrates may be any dimension and shape, and are
preferably those useful for photolithography, such as silicon,
silicon dioxide, silicon-on-insulator (SOI), strained silicon,
gallium arsenide, coated substrates including those coated with
silicon nitride, silicon oxynitride, titanium nitride, tantalum
nitride, ultrathin gate oxides such as hafnium oxide, metal or
metal coated substrates including those coated with titanium,
tantalum, copper, aluminum, tungsten, alloys thereof, and
combinations thereof. Preferably, the surfaces of substrates herein
include critical dimension layers to be patterned including, for
example, one or more gate-level layers or other critical dimension
layer on the substrates for semiconductor manufacture. Such
substrates may preferably include silicon, SOI, strained silicon,
and other such substrate materials, formed as circular wafers
having dimensions such as, for example, 20 cm, 30 cm, or larger in
diameter, or other dimensions useful for wafer fabrication
production.
[0067] Further, a method of forming an electronic device includes
(a) applying a layer of a photoresist composition including on a
surface of the substrate; (b) patternwise exposing the photoresist
composition layer to activating radiation; and (c) developing the
exposed photoresist composition layer to provide a resist relief
image.
[0068] Applying may be accomplished by any suitable method,
including spin coating, spray coating, dip coating, doctor blading,
or the like. Applying the layer of photoresist is preferably
accomplished by spin-coating the photoresist in solvent using a
coating track, in which the photoresist is dispensed on a spinning
wafer. During dispense, the wafer may be spun at a speed of up to
4,000 rpm, preferably from about 500 to 3,000 rpm, and more
preferably 1,000 to 2,500 rpm. The coated wafer is spun to remove
solvent, and baked on a hot plate to remove residual solvent and
free volume from the film to make it uniformly dense.
[0069] Patternwise exposure is then carried out using an exposure
tool such as a stepper, in which the film is irradiated through a
pattern mask and thereby is exposed pattern-wise. The method
preferably uses advanced exposure tools generating activating
radiation at wavelengths capable of high resolution including
extreme-ultraviolet (EUV) or e-beam radiation. Other radiation
sources such as 193 nm radiation also may be used. It will be
appreciated that exposure using the activating radiation decomposes
the onium salt compound(s) in the exposed areas and generates acid
and decomposition by-products, and that the acid then effects a
chemical change in the polymer (deblocking the acid sensitive group
to generate a base-soluble group, or alternatively, catalyzing a
cross-linking reaction in the exposed areas). The resolution of
such exposure tools may be less than 30 nm.
[0070] Developing the exposed photoresist layer is then
accomplished by treating the exposed layer to a suitable developer
capable of selectively removing the exposed portions of the film
(where the photoresist is positive tone) or removing the unexposed
portions of the film (where the photoresist is crosslinkable in the
exposed regions, i.e., negative tone). Preferably, the photoresist
is positive tone based on a polymer having acid sensitive
(deprotectable) groups, and the developer is preferably a metal-ion
free tetraalkylammonium hydroxide solution, such as, for example,
aqueous 0.26 N tetramethylammonium hydroxide. A pattern forms by
developing.
[0071] Additionally, for positive resists, unexposed regions can be
selectively removed by treatment with a suitable nonpolar solvent
for negative tone development. See U.S. 2011/0294069 for suitable
procedures for negative tone development of positive photoresists.
Typical nonpolar solvents for negative tone development are organic
developers, such as a solvent chosen from ketones, esters,
hydrocarbons, and mixtures thereof, e.g. acetone, 2-hexanone,
methyl acetate, butyl acetate, and terahydrofuran.
[0072] The photoresist may, when used in one or more such a
pattern-forming processes, be used to fabricate electronic and
optoelectronic devices such as memory devices, processor chips
(CPU's), graphics chips, and other such devices.
Examples 1-4: Syntheses of Onium Salt Compounds
Example 1: Synthesis of
10-(5-((2-(1-ethylcyclopentyloxy)-2-oxoethoxy)carbonyl)-2-methoxyphenyl)--
9-oxo-9,10-dihydrothioxanthylium iodide
##STR00014##
[0074]
10-(5-((2-(1-ethylcyclopentyloxy)-2-oxoethoxy)carbonyl)-2-methoxyph-
enyl)-9-oxo-2-(trifluoromethyl)-4,4a,9,10-tetrahydrothioxanthylium
trifluoromethanesulfonate (20.9 g, 31.3 mmol) was dissolved in
dichloromethane (250 mL), washed with 1M aqueous sodium iodide
(4.times.250 mL), water (4.times.250 mL), dried (Na.sub.2SO.sub.4)
and concentrated to afford the title compound (17.1 g, 84%) as a
light orange solid. NMR (300 MHz, (CD.sub.3).sub.2SO) .delta.: 9.05
(vis s, 1H), 8.52-8.59 (m, 2H), 8.35-8.43 (m, 1H), 8.20-8.28 (m,
2H), 7.93-8.08 (m, 4H), 7.35 (d, J=10 Hz, 1H), 4.91 (s, 2H), 3.47
(s, 3H), 1.90-2.10 (m, 4H), 1.5-1.73 (m, 6H), 0.89 (t, J=7 Hz,
3H).
Example 2: Synthesis of
10-(5-((2-(1-ethylcyclopentyloxy)-2-oxoethoxy)carbonyl)-2-methoxyphenyl)--
9-oxo-4,4a,9,10-tetrahydrothioxanthylium
3-hydroxyadamantane-acetoxy-1,1,2,2-tetrafluorobutane-1-sulfonate
##STR00015##
[0076]
0-(5-((2-(1-ethylcyclopentyloxy)-2-oxoethoxy)carbonyl)-2-methoxyphe-
nyl)-9-oxo-4,4a,9,10-tetrahydrothioxanthylium iodide (5.00 g, 7.73
mmol) and
3-hydroxyadamantane-acetoxy-1,1,2,2-tetrafluorobutane-1-sulfonate
sodium salt (3.46 g, 8.12 mmol) were dissolved in dichloromethane
(125 mL) and water (125 mL) and stirred at r.t. overnight. The
layers were separated and the aqueous phase washed with
dichloromethane (3.times.100 mL). The combined organic layers were
washed with water (4.times.250 mL) and concentrated to affored the
title compound (5.56 g, 96%) as a light orange solid. NMR (300 MHz,
(CD.sub.3).sub.2SO) .delta.: 9.04 (vis s, 1H), 8.51-8.59 (m, 2H),
8.39 (dd, J=10, 2.4 Hz, 1H), 8.21-8.27 (m, 2H), 7.92-8.06 (m, 4H),
7.35 (d, J=10 Hz, 1H), 4.91 (s, 2H), 4.57 (s, 1 OH), 4.23 (t, J=6
Hz, 2H), 3.47 (s, 3H), 2.43-2.63 (m, 4H), 1.90-2.12 (m, 7H),
1.44-1.73 (m, 15H), 0.88 (t, J=7 Hz, 3H).
Example 3: Synthesis of
10-(5-((2-(1-ethylcyclopentyloxy)-2-oxoethoxy)carbonyl)-2-methoxyphenyl)--
9-oxo-2-(trifluoromethyl)-9,10-dihydrothioxanthylium iodide
##STR00016##
[0078]
10-(5-((2-(1-ethylcyclopentyloxy)-2-oxoethoxy)carbonyl)-2-methoxyph-
enyl)-9-oxo-2-(trifluoromethyl)-4,4a,9,10-tetrahydrothioxanthylium
(5.21 g, 7.07 mmol) was dissolved in dichloromethane (100 mL) and
washed with 1M aqueous sodium iodide (4.times.150 mL), water
(4.times.150 mL), dried (Na.sub.2SO.sub.4) and concentrated to
afford the title compound (3.81 g, 75%) as a light orange solid.
NMR (500 MHz, (CD.sub.3).sub.2SO) .delta.: 9.17 (vis s, 1H), 8.73
(vis s, 1H), 8.55-8.59 (m, 1H), 8.47-8.52 (m, 1H), 8.37-8.43 (m,
2H), 8.23 (d, J=8.5 Hz, 1H), 7.98-8.07 (m, 2H), 7.35 (d, J=8.5 Hz,
2H).
Example 4: Synthesis of
10-(5-((2-(1-ethylcyclopentyloxy)-2-oxoethoxy)carbonyl)-2-methoxyphenyl)--
9-oxo-2-(trifluoromethyl)-4,4a,9,10-tetrahydrothioxanthylium
3-hydroxyadamantane-acetoxy-1,1,2,2-tetrafluorobutane-1-sulfonate
##STR00017##
[0080]
0-(5-((2-(1-ethylcyclopentyloxy)-2-oxoethoxy)carbonyl)-2-methoxyphe-
nyl)-9-oxo-2-(trifluoromethyl)-4,4a,9,10-tetrahydrothioxanthylium
iodide (0.8 g, 1.12 mmol) and
3-hydroxyadamantane-acetoxy-1,1,2,2-tetrafluorobutane-1-sulfonate
sodium salt (0.501 g, 1.18 mmol) were dissolved in dichloromethane
(25 mL) and water (25 mL) and stirred at r.t. overnight. The layers
were separated and the aqueous phase washed with dichloromethane
(3.times.50 mL). The combined organic layers were washed with water
(4.times.50 mL) and concentrated to affored the title compound
(1.04 g, 95%) as a light orange solid. NMR (300 MHz,
(CD.sub.3).sub.2SO) .delta.: 9.21 (vis s, 1H), 8.73-8.78 (m, 1H),
8.37-8.61 (m, 6H), 8.21-8.26 (m, 1H), 7.97-8.08 (m, 2H), 7.35 (d,
J=10 Hz, 1H, 4.94 (s, 2H), 4.24 (t, J=6 Hz, 2H), 3.45 (s, 3H),
2.44-2.63 (m, 4H), 1.89-2.12 (m, 7H), 1.44-1.74 (m, 15H), 0.88 (t,
J=7 Hz, 3H).
Example 5: Preparation of Polymer with Acid Generator Units
[0081] Initiator solution was prepared by dissolving 65.96 g
initiator (V-65) in 66 g acetonitrile/tetrahydrofuran (2/1 v/v).
The polymerization was carried out in a 2 L 3-neck round bottom
flask fitted with a water condenser and a thermometer to monitor
the reaction in the flask. The contents were stirred using an
overhead stirrer. The reactor was charged with the heel solution
and the contents were heated to 75.degree. C. The feed solution and
the initiator solution were fed into the reactor using syringe pump
over a 4 hour time period. The contents were then stirred for
additional 2 hours, whereby, the reaction was quenched using
hydroquinone (2.0 g). The contents were cooled to room temperature
and precipitated twice out of 10.times. (by weight) IPE/MeOH 95/5
(w/w). The polymer obtained was dried in vacuuo after each
precipitation step at 50.degree. C. for 24 hours to yield 500 g
polymer.
Example 6: Preparation and Processing of Photoresist
Composition
[0082] A positive-tone photoresist composition is prepared by
combining 21.088 g of a 10 wt % solution of the polymer from
Example 20 in ethyl lactate, 18.779 g of a 2 wt % solution of the
acid generator compound of Example 1 above in ethyl lactate, 1.898
g of a 0.5 wt % solution of
1,1',1'',1'''-(ethane-1,2-diylbis(azanetriyl))tetrapropan-2-ol in
ethyl lactate, 0.422 g of a 0.5 wt % solution of fluorinated
surfactant (Omnova PF656) in ethyl lactate, 47.342 g of ethyl
lactate and 29.250 g of 2-hydroxyisobutyric acid methyl ester. The
formulated resist is passed through a 0.01 .mu.m PTFE filter. The
thus prepared resist is spin coated onto a silicon wafer, soft
baked to remove carrier solvent and exposed through a photomask to
EUV radiation. The imaged resist layer is then baked at 110.degree.
C. for 60 seconds and then developed with an aqueous alkaline
composition.
Example 7: Further Preparation and Processing of Photoresist
Composition
[0083] A positive-tone photoresist composition is prepared by
combining 21.088 g of a 10 wt % solution of the polymer from
Example 20 in ethyl lactate, 19.522 g of a 2 wt % solution of the
acid generator compound of Example 2 above in ethyl lactate, 1.898
g of a 0.5 wt % solution of
1,1',1'',1'''-(ethane-1,2-diylbis(azanetriyl))tetrapropan-2-ol in
ethyl lactate, 0.422 g of a 0.5 wt % solution of fluorinated
surfactant (Omnova PF656) in ethyl lactate, 46.342 g of ethyl
lactate and 29.150 g of 2-hydroxyisobutyric acid methyl ester. The
formulated resist is passed through a 0.01 .mu.m PTFE filter. The
thus prepared resist is spin coated onto a silicon wafer, soft
baked to remove carrier solvent and exposed through a photomask to
EUV radiation. The imaged resist layer is then baked at 110.degree.
C. for 60 seconds and then developed with an aqueous alkaline
composition.
* * * * *