U.S. patent application number 15/604855 was filed with the patent office on 2017-09-14 for nanoparticle - polymer resists.
The applicant listed for this patent is ROHM AND HAAS ELECTRONIC MATERIALS LLC, THE UNIVERSITY OF QUEENSLAND. Invention is credited to Idriss Blakey, Meiliana Siauw, James W. Thackeray, Peter Trefonas, III, Andrew Keith Whittaker.
Application Number | 20170261853 15/604855 |
Document ID | / |
Family ID | 57882569 |
Filed Date | 2017-09-14 |
United States Patent
Application |
20170261853 |
Kind Code |
A1 |
Thackeray; James W. ; et
al. |
September 14, 2017 |
NANOPARTICLE - POLYMER RESISTS
Abstract
A composite, which is a blend comprising: a nanoparticle
comprising a core and a coating surrounding the core; and a
polymer, wherein the coating of the nanoparticle comprises a
ligand, wherein the ligand is a substituted or unsubstituted
C.sub.1-C.sub.16 carboxylic acid or a salt thereof, a substituted
or unsubstituted C.sub.1-C.sub.16 amino acid or a salt thereof, a
substituted or unsubstituted C.sub.1-C.sub.16 dialkyl phosphonate,
or a combination thereof; and wherein the polymer is a
polymerization product of a photoacid generator comprising a
polymerizable group; at least one unsaturated monomer, which is
different from the photoacid generator comprising a polymerizable
group; and a chain transfer agent of formula (I); ##STR00001##
wherein: Z is a y valent C.sub.1-20 organic group, x is 0 or 1, and
R.sup.d is a substituted or unsubstituted C.sub.1-20 alkyl,
C.sub.3-20 cycloalkyl, C.sub.6-20 aryl, or C.sub.7-20 aralkyl.
Inventors: |
Thackeray; James W.;
(Braintree, MA) ; Siauw; Meiliana; (Annerley,
AU) ; Trefonas, III; Peter; (Medway, MA) ;
Blakey; Idriss; (Clayfield, AU) ; Whittaker; Andrew
Keith; (Toowong, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ROHM AND HAAS ELECTRONIC MATERIALS LLC
THE UNIVERSITY OF QUEENSLAND |
Marlborough
St. Lucia |
MA |
US
AU |
|
|
Family ID: |
57882569 |
Appl. No.: |
15/604855 |
Filed: |
May 25, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14812238 |
Jul 29, 2015 |
9696624 |
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15604855 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03F 7/0046 20130101;
G03F 7/038 20130101; G03F 7/0397 20130101; G03F 7/325 20130101;
G03F 7/0382 20130101; G03F 7/094 20130101; G03F 7/09 20130101; G03F
7/0045 20130101; G03F 7/2037 20130101; G03F 7/0047 20130101; G03F
7/20 20130101; G03F 7/0392 20130101; G03F 7/162 20130101 |
International
Class: |
G03F 7/09 20060101
G03F007/09; G03F 7/32 20060101 G03F007/32; G03F 7/16 20060101
G03F007/16; G03F 7/20 20060101 G03F007/20; G03F 7/038 20060101
G03F007/038; G03F 7/004 20060101 G03F007/004 |
Claims
1. A composite, which is a blend comprising: a nanoparticle
comprising a core and a coating surrounding the core; and a
polymer, wherein the coating of the nanoparticle comprises a
ligand, wherein the ligand is a substituted or unsubstituted
C.sub.1-C.sub.16 carboxylic acid or a salt thereof, a substituted
or unsubstituted C.sub.1-C.sub.16 amino acid or a salt thereof, a
substituted or unsubstituted C.sub.1-C.sub.16 dialkyl phosphonate,
or a combination thereof; and wherein the polymer is a
polymerization product of a group of reactants consisting of a
photoacid generator comprising a polymerizable group, at least one
unsaturated monomer, which is different from the photoacid
generator comprising a polymerizable group; and a chain transfer
agent of formula (I); ##STR00032## wherein: Z is a y valent
C.sub.1-20 organic group, x is 0 or 1, and R.sup.d is a substituted
or unsubstituted C.sub.1-20 alkyl, C.sub.3-20 cycloalkyl,
C.sub.6-20 aryl, or C.sub.7-20 aralkyl, wherein the at least one
unsaturated monomer is free of an acid-deprotectable monomer of
formula (IV-B): ##STR00033## wherein, R.sup.a is independently H,
F, C.sub.1-10 alkyl, or C.sub.1-10 fluoroalkyl; and R.sup.b is
independently C.sub.1-20 alkyl, C.sub.3-20 cycloalkyl, or
C.sub.7-20 aralkyl, wherein 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.
2. The composite of claim 1, wherein the core of the nanoparticle
comprises ZrO.sub.2, HfO.sub.2, TiO.sub.2, or a combination
thereof.
3. The composite of claim 1, wherein the ligand is a substituted or
unsubstituted C.sub.1-C.sub.16 carboxylic acid or a salt
thereof.
4. The composite of claim 1, wherein a median diameter of the
nanoparticle is 10 nanometers or less.
5. The composite of claim 1, wherein photoacid generator comprising
a polymerizable group is a monomer represented by formula (II):
##STR00034## wherein each R.sup.a is independently H, F, C.sub.1-10
alkyl, or C.sub.1-10 fluoroalkyl; Q.sub.2 is a single bond or an
ester-containing or non-ester containing, fluorinated or
non-fluorinated group selected from C.sub.1-20 alkylene, C.sub.3-20
cycloalkylene, C.sub.6-20 arylene, and C.sub.7-20 aralkylene group;
A is an ester-containing or non ester-containing, fluorinated or
non-fluorinated group selected from C.sub.1-20 alkylene, C.sub.3-20
cycloalkylene, C.sub.6-20 arylene, and C.sub.7-20 aralkylene; Z is
an anionic moiety comprising sulfonate, an anion of a sulfonamide,
or an anion of a sulfonimide; and G.sup.+ has formula (III):
##STR00035## wherein X is S or I, each R.sup.c is halogenated or
non-halogenated and is independently a 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, wherein when X is S, one of
the R.sup.c groups is optionally attached to one adjacent R.sup.c
group by a single bond, and z is 2 or 3, wherein when X is I, z is
2, or when X is S, z is 3.
6. The composite of claim 1, wherein the polymerized product
further comprises a repeating unit derived from a base-soluble
monomer of formula (V) or a lactone-containing monomer of formula
(VI): ##STR00036## wherein, W is a base-reactive group comprising
--C(.dbd.O)--OH; --C(CF.sub.3).sub.2OH; --NH--SO.sub.2--Y.sup.1
where Y.sup.1 is F or C.sub.1-4 perfluoroalkyl; an aromatic --OH;
or an adduct of any of the foregoing with a vinyl ether, a is an
integer of 1 to 3, L is a monocyclic, polycyclic, or fused
polycyclic C.sub.4-20 lactone-containing group.
7. The composite of claim 1, wherein G.sup.+ has formula (VII),
(VIII), or (IX): ##STR00037## wherein X is I or S, R.sup.h,
R.sup.i, R.sup.j, and R.sup.k are each independently hydroxy,
nitrile, halogen, C.sub.1-10 alkyl, C.sub.1-10 fluoroalkyl,
C.sub.1-10 alkoxy, C.sub.1-10 fluoroalkoxy, C.sub.6-20 aryl,
C.sub.6-20 fluoroaryl, C.sub.6-20 aryloxy, or C.sub.6-20
fluoroaryloxy, Ar.sup.1 and Ar.sup.2 are independently C.sub.10-30
fused or singly bonded polycyclic aryl groups; R.sup.1 is a lone
pair of electrons where X is I, or a C.sub.6-20 aryl group where X
is S; p is an integer of 2 or 3, wherein when X is I, p is 2, and
where X is S, p is 3, q and r are each independently an integer
from 0 to 5, and s and t are each independently an integer from 0
to 4.
8. The composite of claim 1, wherein the chain transfer agent of
formula (I) has the structure of formula (X): ##STR00038## wherein
R.sup.m is a C.sub.1-10 alkyl, C.sub.1-10 alkoxy, C.sub.3-10
cycloalkyl, C.sub.6-10 aryl, or C.sub.7-10 aralkyl group, and
R.sup.c is substituted or unsubstituted and is a C.sub.1-10 alkyl
or C.sub.6-10 aryl group.
9. A photoresist composition comprising the composite of claim
1.
10. A coated substrate, comprising: (a) a substrate having one or
more layers to be patterned on a surface thereof; and (b) a layer
of a photoresist composition of claim 9 over the one or more layers
to be patterned.
11. A method of forming an electronic device comprising: (a)
applying a layer of the photoresist composition of claim 9 on a
surface of the substrate; (b) pattern-wise exposing the photoresist
composition layer to activating radiation; and (c) developing the
exposed photoresist composition layer with a solvent to provide a
resist relief image.
12. The composite of claim 11, wherein the resist relief image is a
negative image.
13. The method of claim 11, wherein the solvent is a mixture of an
alcohol and a ketone.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 14/812,238, filed on Jul. 29, 2015 in the United States Patent
and Trademark Office, which is incorporated herein in its entirety
by reference.
FIELD
[0002] The present disclosure generally relates to the field of
semiconductors and semiconductor processing. Particularly, the
present disclosure provides a composite including a
nanoparticle-polymer resist.
Introduction
[0003] Metal oxide nanoparticles have recently been developed for
use in photoresists. Some of the metal oxides (such as HfO.sub.2 or
ZrO.sub.2) surrounded by organic ligands (such as methacrylic acid)
can be patterned at EUV wavelengths. During this process, ligands
are added to the metal oxides to form nanoparticle aggregates,
which are combined with photoacid generators to form photoresists.
These photoresists, coated from solvents (such as PGMEA), can be
developed either as positive (aqueous base) or negative
(2-heptanone) tone.
[0004] However, there remains a need in a new photolithography
material which would have higher sensitivity and higher resolution
than the existing photoresists.
SUMMARY
[0005] An embodiment provides a composite, which is a blend
comprising:
[0006] a nanoparticle comprising a core and a coating surrounding
the core; and
[0007] a polymer,
[0008] wherein the coating of the nanoparticle comprises a ligand,
wherein the ligand is a substituted or unsubstituted
C.sub.1-C.sub.16 carboxylic acid or a salt thereof, a substituted
or unsubstituted C.sub.1-C.sub.16 amino acid or a salt thereof, a
substituted or unsubstituted C.sub.1-C.sub.16 dialkyl phosphonate,
or a combination thereof; and
[0009] wherein the polymer is a polymerization product of [0010] a
photoacid generator comprising a polymerizable group; [0011] at
least one unsaturated monomer, which is different from the
photoacid generator comprising a polymerizable group; and [0012] a
chain transfer agent of formula (I);
[0012] ##STR00002## [0013] wherein: [0014] Z is a y valent
C.sub.1-20 organic group, [0015] x is 0 or 1, and [0016] R.sup.d is
a substituted or unsubstituted C.sub.1-20 alkyl, C.sub.3-20
cycloalkyl, C.sub.6-20 aryl, or C.sub.7-20 aralkyl.
[0017] Another embodiment provides a method of making a composite,
comprising mixing
[0018] a nanoparticle comprising a core and a coating surrounding
the core; and
[0019] a polymer,
[0020] wherein the coating of the nanoparticle comprises a ligand,
wherein the ligand is a substituted or unsubstituted
C.sub.1-C.sub.16 carboxylic acid or a salt thereof, a substituted
or unsubstituted C.sub.1-C.sub.16 amino acid or a salt thereof, a
substituted or unsubstituted C.sub.1-C.sub.16 dialkyl phosphonate,
or a combination thereof; and [0021] wherein the polymer is a
polymerization product of [0022] a photoacid generator comprising a
polymerizable group; [0023] at least one unsaturated monomer, which
is different from the photoacid generator comprising a
polymerizable group; and [0024] a chain transfer agent of formula
(I);
[0024] ##STR00003## [0025] wherein: [0026] Z is a y valent
C.sub.1-20 organic group, [0027] x is 0 or 1, [0028] R.sup.d is a
substituted or unsubstituted C.sub.1-20 alkyl, C.sub.3-20
cycloalkyl, C.sub.6-20 aryl, or C.sub.7-20 aralkyl.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The above and other aspects, advantages, and features of
this disclosure will become more apparent by describing in further
detail exemplary embodiments thereof with reference to the
accompanying drawings, in which:
[0030] FIG. 1 is a schematic representation of a process of making
a nanoparticle-polymer composite according to an embodiment;
[0031] FIG. 2 is a graph representing a .sup.13C-SS-NMR spectrum of
zirconium isopropoxide;
[0032] FIG. 3 is a graph representing a .sup.13C-SS-NMR spectrum of
ZrO.sub.2-IBA;
[0033] FIG. 4 is a graph representing a dynamic light scattering
(DLS) diagram of ZrO.sub.2-IBA in ethyl lactate;
[0034] FIG. 5 is a transmission electron microscopy (TEM) image of
ZrO.sub.2-IBA at 300,000 magnification;
[0035] FIG. 6 is a graph representing an ATR-FTIR spectrum of
ZrO.sub.2-IBA;
[0036] FIG. 7 is a graph representing an ATR-FTIR spectrum of
HfO.sub.2-IBA;
[0037] FIG. 8 is a graph representing a thermogravimetric analysis
(TGA) of ZrO.sub.2-IBA powder;
[0038] FIG. 9 is a graph representing a thermogravimetric analysis
(TGA) of HfO.sub.2-IBA powder;
[0039] FIG. 10 is a graph representing a .sup.1H-NMR spectrum of
PMMA.sub.22-co-PPAG.sub.2;
[0040] FIGS. 11A-11B are atomic force microscopy (AFM) images of CD
target 100 nm (CD:LW=1:1) obtained at the area doses of 140
.mu.C/cm.sup.2 and 240 .mu.C/cm.sup.2, respectively; and
[0041] FIGS. 12A-12C are atomic force microscopy (AFM) images of CD
target 100 nm (CD:LW=1:4) obtained at the area doses of 240
.mu.C/cm.sup.2, 340 .mu.C/cm.sup.2, and 460 .mu.C/cm.sup.2,
respectively.
DETAILED DESCRIPTION
[0042] Reference will now be made in detail to exemplary
embodiments, examples of which are illustrated in the accompanying
drawings, wherein like reference numerals refer to like elements
throughout. In this regard, the present exemplary embodiments may
have different forms and should not be construed as being limited
to the descriptions set forth herein. Accordingly, the exemplary
embodiments are merely described below, by referring to the
figures, to explain aspects of the present description. As used
herein, the term "and/or" includes any and all combinations of one
or more of the associated listed items. Expressions such as "at
least one of," when preceding a list of elements, modify the entire
list of elements and do not modify the individual elements of the
list.
[0043] It will be understood that when an element is referred to as
being "on" another element, it can be directly in contact with the
other element or intervening elements may be present therebetween.
In contrast, when an element is referred to as being "directly on"
another element, there are no intervening elements present.
[0044] It will be understood that, although the terms first,
second, third, etc., may be used herein to describe various
elements, components, regions, layers, and/or sections, these
elements, components, regions, layers, and/or sections should not
be limited by these terms. These terms are only used to distinguish
one element, component, region, layer, or section from another
element, component, region, layer, or section. Thus, a first
element, component, region, layer, or section discussed below could
be termed a second element, component, region, layer, or section
without departing from the teachings of the present
embodiments.
[0045] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting. As
used herein, the singular forms "a," "an," and "the" are intended
to include the plural forms as well, unless the context clearly
indicates otherwise.
[0046] It will be further understood that the terms "comprises"
and/or "comprising," or "includes" and/or "including" when used in
this specification, specify the presence of stated features,
regions, integers, steps, operations, elements, and/or components,
but do not preclude the presence or addition of one or more other
features, regions, integers, steps, operations, elements,
components, and/or groups thereof.
[0047] "About" or "approximately" as used herein is inclusive of
the stated value and means within an acceptable range of deviation
for the particular value as determined by one of ordinary skill in
the art, considering the measurement in question and the error
associated with measurement of the particular quantity (i.e., the
limitations of the measurement system). For example, "about" can
mean within one or more standard deviations, or within .+-.30%,
20%, 10%, 5% of the stated value.
[0048] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and the present
disclosure, and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0049] As used herein, when a definition is not otherwise provided,
the term "alkyl group" refers to a group derived from a straight or
branched chain saturated aliphatic hydrocarbon having the specified
number of carbon atoms and having a valence of at least one.
[0050] As used herein, when a definition is not otherwise provided,
the term "fluoroalkyl group" refers to an alkyl group in which one
or more hydrogen atoms are replaced with fluorine atoms.
[0051] As used herein, when a definition is not otherwise provided,
the term "alkoxy group" refers to "alkyl-O--", wherein the term
"alkyl" has the same meaning as described above.
[0052] As used herein, when a definition is not otherwise provided,
the term "fluoroalkoxy group" refers to an alkoxy group in which
one or more hydrogen atoms are replaced with fluorine atoms.
[0053] As used herein, when a definition is not otherwise provided,
the term "cycloalkyl group" refers to a monovalent group having one
or more saturated rings in which all ring members are carbon.
[0054] As used herein, when a definition is not otherwise provided,
the term "heterocyclic group" refers to a monovalent saturated or
unsaturated cyclic group that has atoms of at least two different
elements as members of its ring(s).
[0055] As used herein, when a definition is not otherwise provided,
the term "aryl", which is used alone or in combination, refers to
an aromatic hydrocarbon containing at least one ring and having the
specified number of carbon atoms. The term "aryl" may be construed
as including a group with an aromatic ring fused to at least one
cycloalkyl ring.
[0056] As used herein, when a definition is not otherwise provided,
the term "aryloxy group" refers to "aryl-O--", wherein the term
"aryl" has the same meaning as described above.
[0057] As used herein, when a definition is not otherwise provided,
the term "aralkyl group" refers to a substituted or unsubstituted
aryl group covalently linked to an alkyl group that is linked to a
compound.
[0058] As used herein, when a definition is not otherwise provided,
the term "alkylene group" refers to a straight or branched
saturated aliphatic hydrocarbon group having a valence of at least
two, optionally substituted with one or more substituents where
indicated, provided that the valence of the alkylene group is not
exceeded.
[0059] As used herein, when a definition is not otherwise provided,
the term "cycloalkylene group" refers to a cyclic hydrocarbon group
having a valence of at least two, optionally substituted with one
or more substituents where indicated, provided that the valence of
the cycloalkylene group is not exceeded.
[0060] As used herein, when a definition is not otherwise provided,
the term "arylene group" refers to a functional group having a
valence of at least two obtained by removal of two hydrogens in an
aromatic ring, optionally substituted with one or more substituents
where indicated, provided that the valence of the alkylene group is
not exceeded.
[0061] As used herein, when a definition is not otherwise provided,
the term "aralkylene group" refers to a functional group having a
valence of at least two obtained by removal of two hydrogens from
the alkyl-substituted aromatic compound, optionally substituted
with one or more substituents where indicated, provided that the
valence of the aralkylene group is not exceeded.
[0062] As used herein, when the definition is not otherwise
provided, the terms "blend" and "mixture" refer to any combination
of the ingredients constituting the blend or mixture without regard
to a physical form.
[0063] This invention relates to the development of
inorganic-polymer hybrid materials for use in the semiconductor
industry. The inorganic metal oxide nanoparticles (such as
ZrO.sub.2, HfO.sub.2 and TiO.sub.2) are small (.ltoreq.10 nm), they
offer high etch resistance, and therefore, can improve pattern
transfer, especially for small pattern size (.ltoreq.25 nm) and
thin films. The polymer used in the inorganic-polymer hybrid
material contains PAG (photoactive generator compound) along the
polymer backbone (polymer bound PAG).
[0064] Metal oxide nanoparticles combined with polymer bound PAG
(e.g., bound by blending or grafting) could cause multiple
crosslinking among the nanoparticles upon irradiation, which may
lead to the production of high sensitivity and high resolution
photolithography material (which provides less dose and high
pattern quality) (FIG. 1).
[0065] Disclosed herein is a composite, which is a blend
comprising:
[0066] a nanoparticle comprising a core and a coating surrounding
the core; and
[0067] a polymer,
[0068] wherein the coating of the nanoparticle comprises a ligand,
wherein the ligand is a substituted or unsubstituted
C.sub.1-C.sub.16 carboxylic acid or a salt thereof, a substituted
or unsubstituted C.sub.1-C.sub.16 amino acid or a salt thereof, a
substituted or unsubstituted C.sub.1-C.sub.16 dialkyl phosphonate,
or a combination thereof; and
[0069] wherein the polymer is a polymerization product of [0070] a
photoacid generator comprising a polymerizable group; [0071] at
least one unsaturated monomer, which is different from the
photoacid generator comprising a polymerizable group; and [0072] a
chain transfer agent of formula (I);
[0072] ##STR00004## [0073] wherein: [0074] Z is a y valent
C.sub.1-20 organic group, [0075] x is 0 or 1, and [0076] R.sup.d is
a substituted or unsubstituted C.sub.1-20 alkyl, C.sub.3-20
cycloalkyl, C.sub.6-20 aryl, or C.sub.7-20 aralkyl.
[0077] The core of the nanoparticle may include an oxide of any
metal element and may include an oxide of lithium, beryllium,
sodium, magnesium, aluminum, silicon, calcium, potassium,
manganese, scandium, titanium, vanadium, chromium, zinc, iron,
cobalt, nickel, copper, gallium, germanium, arsenic, selenium,
zirconium, rubidium, strontium, yttrium, niobium, molybdenum,
technetium, ruthenium, tin, cadmium, indium, cesium, antimony,
tellurium, neodymium, barium, lanthanum, cerium, praseodymium,
terbium, promethium, samarium, europium, gadolinium, ytterbium,
dysprosium, holmium, erbium, thulium, rhenium, lutetium, hafnium,
tantalum, tungsten, thallium, lead, and bismuth. These oxides may
be binary, ternary, or higher order compounds. Further, a pure
material (for example, zirconium dioxide) or mixed materials (for
example, titanium dioxide and aluminum oxide) can be used including
any mixture of oxides from the elements listed above. The core of
the nanoparticle may include a Group IV element oxide, for example,
zirconium oxide (ZrO.sub.2), hafnium oxide (HfO.sub.2), and
titanium oxide (TiO.sub.2). A skilled artisan will readily
recognize that the reactions used to functionalize and cap the
nanoparticles provided herein may need to be modified slightly for
each metal oxide in order to provide optimum size, quality, and
yield.
[0078] The nanoparticle may include a core and a coating
surrounding the core. The coating effectively caps the core of the
nanoparticle. For example, the core of the nanoparticle may include
zirconium oxide (ZrO.sub.2), hafnium oxide (HfO.sub.2), and
titanium oxide (TiO.sub.2), and the coating may include a ligand,
which is a substituted or unsubstituted C.sub.1-C.sub.16 carboxylic
acid or a salt thereof, a substituted or unsubstituted
C.sub.1-C.sub.16 amino acid or a salt thereof, a substituted or
unsubstituted C.sub.1-C.sub.6 dialkyl phosphonate, or a combination
thereof, but is not limited thereto.
[0079] The capping of the metal oxide nanoparticles may be carried
out in various manners. One method includes using a
C.sub.1-C.sub.16 carboxylic acid which caps the nanoparticle with
either the carboxylic acid or a salt thereof. The capping
carboxylic acid may be any carboxylic acid, for example, acetic
acid, propionic acid, n-butyric acid, isobutyric acid, but is not
limited thereto.
[0080] Another method includes using a C.sub.1-C.sub.6 amino acid
which caps the nanoparticle with either the amino acid or a salt
thereof. The capping amino acid may be any amino acid or a salt
thereof. For example, the capping amino acid can be an aliphatic
amino acid or a salt thereof, such as glycine, alanine, valine,
leucine, or isoleucine; a cyclic amino acid or a salt thereof, such
as proline; an aromatic amino acid or a salt thereof, such as
phenylalanine, tyrosine, or tryptophan; a basic amino acid or a
salt thereof, such as histidine, lysine, or arginine; or an acidic
amino acid or a salt thereof, such as aspartate, glutamate,
asparagine, or glutamine. But the amino acids are not limited
thereto, and any amino acid suitable for capping a nanoparticle can
be used.
[0081] Still another method includes a C.sub.1-C.sub.6 phosphoric
acid which caps the nanoparticle and/or some derivative of the
phosphoric acid. A derivative of the phosphoric acid may be a salt
of the phosphoric acid or a phosphonate. In an embodiment, a
phosphonate may be a substituted or unsubstituted C.sub.1-C.sub.6
dialkyl phosphonate, but is not limited thereto. Some dialkyl
phosphonates suitable for capping are shown below:
##STR00005##
[0082] In an embodiment, the nanoparticle may be ZrO.sub.2 coated
with isobutyric acid or a salt thereof. The isobutyrate-capped
ZrO.sub.2 may be synthesized from zirconium isopropoxide and
isobutyric acid in water as described in the example below. In some
embodiments, the capped metal oxide nanoparticles disclosed herein
do not aggregate.
[0083] The present method allows obtaining high quality
nanoparticle slurry in which the nanoparticles maintain their size
and do not aggregate or grow significantly under adverse
conditions, for example, when a nanoparticle containing solution is
heated to elevated temperatures. In this regard, it is desired to
use nanoparticles which are similar in size. The present disclosure
provides for nanoparticles with the median diameter of 10 nm or
less, for example, 6 nm or less, 3 nm or less, or even 1 nm or
less. Accurate size control can be achieved by drying an aqueous
suspension of the nanoparticles at varying temperatures and then
re-suspending the dried powder in water or solvent.
[0084] Some metals constituting the nanoparticles are toxic and may
represent danger to human health. Therefore, to reduce or prevent
harmful method contamination, effective methods of purification of
the nanoparticles are highly desired. In the present method, the
purification of nanoparticles can be achieved by a variety of
techniques such as solvent exchange, centrifugation, or multiple
decantation. Other purification methods may include, but are not
limited to dialysis, dielectrophoretic electrode arrays, size
exclusion chromatography, diafiltration, field flow fractionation,
and ultra-filtration. Purification by ultra-filtration is achieved
by passing a solution through a filter having very small pores that
do not allow for the passage of the particles. The non-limiting
examples of the filters that can be used are polytetrafluorethylene
(PTFE) membrane filter, but not limited to nylon, polycarbonate,
polyester, polyethersulfone, or cellulose type membrane filter.
[0085] The composition further comprises a photoacid generator. The
photoacid generator in the composition may be represented by
formula (II):
##STR00006##
[0086] In the formula (II), each R.sup.a may independently be H, F,
C.sub.1-10 alkyl, or C.sub.1-10 fluoroalkyl. As used throughout
this specification, "fluoro" or "fluorinated" means that one or
more fluorine groups are attached to the associated group. For
example, by this definition and unless otherwise specified,
"fluoroalkyl" encompasses monofluoroalkyl, difluoroalkyl, etc., as
well as perfluoroalkyl in which substantially all carbon atoms of
the alkyl group are substituted with fluorine atoms; similarly,
"fluoroaryl" means monofluoroaryl, perfluoroaryl, etc.
"Substantially all" in this context means greater than or equal to
90%, preferably greater than or equal to 95%, and still more
preferably greater than or equal to 98% of all atoms attached to
carbon are fluorine atoms.
[0087] In the formula (II), Q.sub.2 is a single bond or an
ester-containing or non-ester containing, fluorinated or
non-fluorinated group selected from C.sub.1-20 alkyl, C.sub.3-20
cycloalkyl, C.sub.6-20 aryl, and C.sub.7-20 aralkyl. For example,
where an ester is included, the ester forms a connective link
between Q.sub.2 and the point of attachment to the double bond. In
this way, where Q.sub.2 is an ester group, formula (II) may be a
(meth)acrylate monomer. Where an ester is not included, Q.sub.2 may
be aromatic, so that formula (II) may be, for example, a styrenic
monomer or vinyl naphthoic monomer.
[0088] Also, in formula (II), A is an ester-containing or non
ester-containing, fluorinated or non-fluorinated group selected
from C.sub.1-20 alkyl, C.sub.3-20 cycloalkyl, C.sub.6-20 aryl, or
C.sub.7-20 aralkyl. Useful A groups may include fluorinated
aromatic moieties, straight chain fluoroalkyl, or branched
fluoroalkyl esters. For example, A may be a
--[(C(R.sup.e).sub.2).sub.x(.dbd.O)O].sub.c--(C(R.sup.f).sub.2).sub.y(CF.-
sub.2).sub.z-- group, or an o-, m- or p-substituted
--C.sub.6R.sup.g.sub.4-- group, where each R.sup.e, R.sup.f, and
R.sup.g are each independently H, F, C.sub.1-6 fluoroalkyl, or
C.sub.1-6 alkyl, c 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.
[0089] Also, in formula (II), Z.sup.- is an anionic group including
a sulfonate (--SO.sub.3.sup.-), the anion of a sulfonamide
(--SO.sub.2(N.sup.-)R' where R' is a C.sub.1-10 alkyl or C.sub.6-20
aryl), or the anion of a sulfonimide. Where Z is a sulfonimide, the
sulfonimide may be an asymmetric sulfonimide having the general
structure A-SO.sub.2--(N.sup.-)--SO.sub.2--Y.sup.2, where A is as
described above, and Y.sup.2 is a straight chain or branched
C.sub.1-10 fluoroalkyl group. For example, the Y.sup.2 group may be
a C.sub.1-4 perfluoroalkyl group, which may be derived from the
corresponding perfluorinated alkanesulfonic acid, such as
trifluoromethanesulfonic acid or perfluorobutanesulfonic acid.
[0090] In an embodiment, the monomer of formula (II) may have the
structure of formula (IIa) or (IIb):
##STR00007##
[0091] wherein, A and R.sup.a are as defined for formula (II).
[0092] Formula (II) further includes a cation G.sup.+, which may be
a metal or non-metal cation. For example, a non-metal cation may
include an onium cation, such as a sulfonium cation, an oxonium
cation, or an iodonium cation. For example, the cation G.sup.+ may
be an onium cation having formula (III):
##STR00008##
[0093] wherein,
[0094] X is S or I,
[0095] each R.sup.c is halogenated or non-halogenated and is
independently a 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,
[0096] wherein when X is S, one of the R.sup.c groups is optionally
attached to one adjacent R.sup.c group by a single bond, and z is 2
or 3, and
[0097] wherein when X is I, z is 2, or when X is S, z is 3.
[0098] For example, cation G.sup.+ may have formula (VII), (VIII),
or (IX):
##STR00009##
[0099] wherein,
[0100] X is I or S,
[0101] R.sup.h, R.sup.i, R.sup.j, and R.sup.k are each
independently hydroxy, nitrile, halogen, C.sub.1-10 alkyl,
C.sub.1-10 fluoroalkyl, C.sub.1-10 alkoxy, C.sub.1-10 fluoroalkoxy,
C.sub.6-20 aryl, C.sub.6-20 fluoroaryl, C.sub.6-20 aryloxy, or
C.sub.6-20 fluoroaryloxy,
[0102] Ar.sup.1 and Ar.sup.2 are independently C.sub.10-30 fused or
singly bonded polycyclic aryl groups;
[0103] R.sup.1 is a lone pair of electrons where X is I, or a
C.sub.6-20 aryl group where X is S;
[0104] p is an integer of 2 or 3, wherein when X is I, p is 2, and
where X is S, p is 3,
[0105] q and r are each independently an integer from 0 to 5,
and
[0106] s and t are each independently an integer from 0 to 4.
[0107] Exemplary photoacid-generating monomers of the formula (II)
include:
##STR00010##
[0108] or a combination comprising at least one of the foregoing,
where
[0109] each R.sup.a is independently H, F, C.sub.1-6 alkyl, or
C.sub.1-6 fluoroalkyl,
[0110] k is an integer of 0 to 4,
[0111] l is an integer of 0 to 3, and
[0112] G.sup.+ is a cation of formula (V).
[0113] For example, G.sup.+ may be a cation of formulas (VII),
(VIII), or (IX).
[0114] Specific exemplary photoacid-generating monomers of the
formula (II) include those having the formula:
##STR00011## ##STR00012## ##STR00013##
[0115] wherein R.sup.a is H, F, C.sub.1-6 alkyl, or C.sub.1-6
fluoroalkyl.
[0116] The composition further includes at least one unsaturated
monomer, which is different from the photoacid generator including
a polymerizable group. For example, the unsaturated monomer may be
an acid-deprotectable monomer of formula (IV):
##STR00014##
[0117] In the formula (IV),
[0118] R.sup.b is independently H, 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 an embodiment, the
tertiary group including R.sup.b in formula (IV) may be a t-butyl
group. In another embodiment, the formula (IV) may include
cycloalkyl structures, which incorporate two or more R.sup.b
groups, such as 1-methylcyclopentyl, 1-ethylcyclopentyl, and
1-methylcyclohexyl, and the like.
[0119] Exemplary acid deprotectable monomers of the formula (IV)
may include:
##STR00015##
[0120] or a combination comprising at least one of the foregoing,
wherein R.sup.a is H, F, C.sub.1-6 alkyl, or C.sub.1-6
fluoroalkyl.
[0121] The unsaturated monomer may be a base-soluble monomer of
formula (V):
##STR00016##
[0122] In the formula (V), Q.sub.1 is an ester-containing or
non-ester containing group selected from C.sub.1-20 alkyl,
C.sub.3-20 cycloalkyl, C.sub.6-20 aryl, and C.sub.7-20 aralkyl
group. In an embodiment, where an ester is included, the ester
forms a connective link between Q.sub.1 and the point of attachment
to the double bond. In this way, where Q.sub.1 is an ester group,
the formula (V) may be a (meth)acrylate monomer. In another
embodiment, where an ester is not included, Q.sub.1 may be
aromatic, so that the formula (V) may be, for example, a styrenic
monomer or vinyl naphthoic monomer. Q.sub.1 may be fluorinated or
non-fluorinated. Further in the formula (V), a is an integer of 1
to 3, for example, a is 1 or 2.
[0123] Also in the formula (V), W is a base-reactive group
comprising --C(.dbd.O)--OH; --C(CF.sub.3).sub.2OH;
--NH--SO.sub.2--Y.sup.1 where Y.sup.1 is F or C.sub.1-4
perfluoroalkyl; an aromatic --OH; or an adduct of any of the
foregoing with a vinyl ether. In an embodiment, where Q is
non-aromatic (e.g., where formula (II) includes a (meth)acrylate
structure having an ester linked alkyl or cycloalkyl group Q), W is
--C(CF.sub.3).sub.2OH. In another embodiment, where Q is aromatic
(e.g., where Q is either ester-linked or non-ester linked and is an
aromatic group such as phenyl or naphthyl), W is OH or
--C(CF.sub.3).sub.2OH. It is contemplated that any of the
base-reactive groups may further be protected by an acid
decomposable acetal leaving group (e.g., having a generic structure
--O--CH(R')--O--R'' where R' may be a methyl, ethyl, or other alkyl
group). Such groups are adducts of a vinyl ether, such as, for
example, ethyl vinyl ether, propyl vinyl ether, t-butyl vinyl
ether, cyclohexylvinyl ether, the 2-vinyloxyethyl ester of
1-adamantane carboxylic acid, 2-naphthoyl ethyl vinyl ether, or
other such vinyl ethers.
[0124] Exemplary base-soluble monomers having the formula (V) may
include:
##STR00017##
[0125] or a combination comprising at least one of the foregoing,
wherein R.sup.a is H, F, C.sub.1-6 alkyl, or C.sub.1-6
fluoroalkyl.
[0126] The unsaturated monomer may be a lactone-containing monomer
of formula (III):
##STR00018##
[0127] In the formula (III), L may be a monocyclic, polycyclic, or
fused polycyclic C.sub.4-20 lactone-containing group. Such lactone
groups may be included to improve both adhesion of the polymer to a
substrate, and to moderate the dissolution of the polymer in a base
developer. In an embodiment, L may be a monocyclic C.sub.4-6
lactone which is attached to a (meth)acrylate moiety through a
monocycle ring carbon; or L may be a C.sub.6-10 fused polycyclic
lactone based on a norbornane-type structure.
[0128] In an embodiment, a lactone-containing monomer may have the
formula (VIa):
##STR00019##
[0129] wherein,
[0130] R.sup.a is H, F, C.sub.1-6 alkyl, or C.sub.1-6 fluoroalkyl,
R is a C.sub.1-10 alkyl, cycloalkyl, or heterocycloalkyl, and
[0131] w is an integer of 0 to 6.
[0132] It will be appreciated in the formula (VIa) that R may be
separate or may be attached to the lactone ring and/or one or more
R groups, and that the methacrylate moiety may be attached to the
lactone ring directly, or indirectly through R.
[0133] Exemplary lactone-containing monomers of the formulas (VI)
and (VIa) may include:
##STR00020##
[0134] or a combination comprising at least one of the foregoing,
wherein R.sup.a is H, F, C.sub.1-6 alkyl, or C.sub.1-6
fluoroalkyl.
[0135] The unsaturated monomer may be any combination of the acid
deprotectable monomer of the formula (IV), a base-soluble monomer
of the formula (V), and a lactone-containing monomer of the formula
(VI).
[0136] The composition further includes a chain transfer agent. The
chain transfer agent may be any compound based on the dithioester
or trithiocarbonate functional groups and suitable for chain
transfer under conditions of reversible addition-fragmentation
transfer (RAFT) polymerization. The chain transfer agent comprises
a compound of formula (I):
##STR00021##
[0137] wherein,
[0138] x is 0 or 1, and
[0139] Z is a y valent C.sub.1-20 organic group.
[0140] In an embodiment, Z is substituted or unsubstituted, may be
a C.sub.1-20 alkyl, C.sub.3-20 cycloalkyl, C.sub.2-20 heterocyclic,
C.sub.6-20 aryl, or C.sub.7-20 aralkyl, and may contain a halogen,
ether, sulfide, carboxylic acid, ester, amide, nitrile, or other
functional group. While y may be any integer of 1 or greater
depending on the valence of group Z, y is preferably an integer of
from 1 to 3, and more preferably 1 or 2.
[0141] Also in the formula (I), R.sup.d is a substituted or
unsubstituted C.sub.1-20 alkyl, C.sub.3-20 cycloalkyl, C.sub.6-20
aryl, or C.sub.7-20 aralkyl. For example, R.sup.d may be derived
from a radical initiator such as a peroxy or diazo initiator.
[0142] Group
##STR00022##
of a chain transfer agent of the formula (I) may be included in the
polymerization product as an end group. This group can be removed
by a number of methods including a reaction with a radical source,
for example, by radical induced reduction.
[0143] In an embodiment, the chain transfer agent may include a
compound in which Z is a C.sub.6 aryl group, such as those of
formula (X):
##STR00023##
[0144] wherein,
[0145] R.sup.m is a C.sub.1-10 alkyl, C.sub.1-10 alkoxy, C.sub.3-10
cycloalkyl, C.sub.6-10 aryl, or C.sub.7-10 aralkyl group, z is an
integer from 0 to 5, and
[0146] R.sup.c is substituted or unsubstituted and is a C.sub.1-10
alkyl or C.sub.6-10 aryl group.
[0147] Group
##STR00024##
of a chain transfer agent of formula (I) is included in the
polymerization product as an end group. This group can be removed
by a number of methods including a reaction with a radical source,
for example, by radical induced reduction.
[0148] Exemplary chain transfer agents of formula (I) include:
##STR00025##
[0149] or a combination comprising at least one of the
foregoing.
[0150] The composition may optionally include an initiator.
Suitable initiators may include any radical initiator useful in the
art, such as peroxy initiators, diazo initiators, and the like. For
example, peroxy initiators such as tert-butyl hydroperoxide,
tert-butyl peroxy 2-ethyl hexanoate (tert-butyl peroctoate),
t-butyl peroxy pivalate, tert-butyl peroxy benzoate, di-benzoyl
peroxide, tert-butyl peroxy isobutyrate, diazo initiators such as
azobis isobutyronitrile (AIBN), 4,4'-azobis(4-cyanovaleric acid);
and the like. Preferred initiators include those sold under the
trade name VAZO by DuPont, such as VAZO 52, VAZO 67, VAZO 88, and
VAZO V-601 free-radical initiators. Alternatively, the
polymerization may be carried out by thermal initiation (e.g.,
greater than about 120.degree. C., more preferably greater than
about 150.degree. C.). Preferably, thermal initiation may be used
where one or more component monomers are styrenic.
[0151] The copolymer may thus be prepared by radically or thermally
initiated polymerization of the monomers, preferably in a degassed
solvent, in the presence of the chain transfer agent, using the
aforementioned reversible addition-fragmentation transfer (RAFT)
process. The polymerization may be carried out in batch mode, by
batch addition of monomers and/or initiator to the reaction mixture
containing the chain transfer addition, by metered addition of
separate, feeds of one or more of the monomers and/or initiator
and/or chain transfer agent to the reaction mixture, or any other
suitable method for combining the reactants. It will be appreciated
that block coinitiators. Alternatively, the polymerization may be
produced by sequential addition of monomers for each block to the
reaction mixture, or a polymer having a graded composition
(statistical or gradient) may be formed by gradually changing the
monomer proportions and/or composition in the feed over time. All
such polymers preparable by the RAFT method are contemplated
herein.
[0152] Other methods of synthesizing suitable copolymers are also
contemplated, and with proper choice and control of initiators,
solvent, monomers and polymerization process and isolation
conditions could yield polymers of desirable molecular weight and
dispersity. Alternative polymerization methods include, but are not
limited to: free radical polymerization, atom transfer radical
polymerization (ATRP), stable free radical polymerization (SFRP),
nitroxide mediated polymerization (NMP), reversible-deactivation
radical polymerization, anionic step growth polymerization,
cationic step growth polymerization and ring opening metathesis
polymerization (ROMP).
[0153] The copolymer may have a weight-averaged molecular weight
(Mw) of 1,000 to 100,000 g/mol, preferably 1,500 to 50,000 g/mol,
more preferably 2,000 to 25,000 g/mol, and still more preferably
3,000 to 15,000 g/mol. The copolymer may also have a number
averaged molecular weight (Mn) of 500 to 100,000 g/mol, preferably
1,000 to 50,000 g/mol, more preferably 1,500 to 25,000 g/mol, and
still more preferably 2,000 to 15,000 g/mol. Molecular weights may
be determined using any suitable method, such as nuclear magnetic
resonance (NMR) or gel permeation chromatography (GPC) using a
crosslinked styrene-divinylbenzene column calibrated to polystyrene
standards by universal calibration, at a flow rate of about 1
ml/min. The polymer polydispersity (Mw/Mn) is preferably less than
2.0, more preferably less than or equal to 1.8, more preferably
less than or equal to 1.6, and more preferably less than or equal
to 1.5.
[0154] A photoresist composition includes the copolymer having the
polymer-bound PAG as described above. The photoresist may also
include, in addition to the PAG compound and polymer, additives
including, for example, a photo-destroyable base, and a surfactant.
Other additives, such as dissolution rate inhibitors, sensitizers,
additional PAGs, etc., may also be included. The photoresist
components are dissolved in solvent for dispensing and coating.
[0155] 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. Photo-destroyable bases include cation/anion
pairs of the following structures, and the cation is
triphenylsulfonium or one of the following:
##STR00026##
[0156] where R is independently H, a C.sub.1-20 alkyl, a C.sub.6-20
aryl, or a C.sub.6-20 alkyl aryl, and the anion is
##STR00027##
[0157] where R is independently H, a C.sub.1-20 alkyl, a C.sub.1-20
alkoxy, a C.sub.6-20 aryl, or a C.sub.6-20 alkyl aryl. Other
photo-destroyable bases include those based on non-ionic
photo-decomposing chromophores such as, for example, 2-nitrobenzyl
groups and benzoin groups. An exemplary photobase generator is
ortho-nitrobenzyl carbamate.
[0158] 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. For example, such quenchers may 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 Troger's base, a hindered amine such as
diazabicycloundecene (DBU) or diazabicyclononene (DBM), or ionic
quenchers including quaternary alkyl ammonium salts such as
tetrabutylammonium hydroxide (TBAH) or tetrabutyl ammonium
lactate.
[0159] 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.
[0160] 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.
[0161] The photoresist composition disclosed herein may include the
copolymer in an amount of 0.15 to 55 wt %, specifically 0.2 to 45
wt %, more specifically 0.25 to 40 wt %, and still more
specifically 0.3 to 34 wt % based on the total weight of solids. In
some embodiments, the photoresist composition may include the
copolymer in an amount of less than 1%. It will be understood that
"copolymer" used in this context of a component in a photoresist
may mean only the copolymer disclosed herein, or a combination of
the copolymer with another polymer useful in a photoresist.
Additional PAG may be present in the photoresist in an amount of
0.01 to 25 wt %, specifically 0.02 to 15 wt %, and still more
specifically 0.05 to 13 wt %, 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 0.2 to 50 wt %,
specifically 0.5 to 45 wt %, more specifically 1 to 40 wt %, and
still more specifically 2 to 35 wt %, based on the total weight of
solids and solvent. It will be understood that the solids include
nanoparticle, copolymer, photo-destroyable base, quencher,
surfactant, any added PAG, and any optional additives, exclusive of
solvent.
[0162] The photoresist including the copolymer having the
anion-bound PAG as disclosed herein may be used to provide a layer
comprising the photoresist. A coated substrate may be formed from
the photoresist containing the polymer-bound PAG. 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 polymer-bound PAG over the one or more
layers to be patterned.
[0163] 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
layers 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.
[0164] Further, a method of forming an electronic device includes
(a) applying (casting) a layer of a photoresist composition
including the polymer-bound PAG on a surface of the substrate; (b)
pattern-wise exposing the photoresist composition layer to
activating radiation; and (c) developing the exposed photoresist
composition layer to provide a resist relief image.
[0165] 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 dispensing, the wafer may be spun at a speed of up to
4,000 rpm, preferably from about 200 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.
[0166] The casting solvent can be any suitable solvent known to one
of ordinary skill in the art. For example, the casting solvent can
be an aliphatic hydrocarbon (such as hexane, heptane, and the
like), an aromatic hydrocarbon (such as toluene, xylene, and the
like), a halogenated hydrocarbon (such as dichloromethane,
1,2-dichloroethane, 1-chlorohexane, and the like), an alcohol (such
as methanol, ethanol, 1-propanol, iso-propanol, tert-butanol,
2-methyl-2-butanol, 4-methyl-2-pentanol, and the like), water, an
ether (such as diethyl ether, tetrahydrofuran, 1,4-dioxane,
anisole, and the like), a ketone (such as acetone, methyl ethyl
ketone, methyl isobutyl ketone, 2-heptanone, cyclohexanone, and the
like), an ester (such as ethyl acetate, n-butyl acetate, propylene
glycol monomethyl ether acetate (PGMEA), ethyl lactate, ethyl
acetoacetate, and the like), a lactone (such as
.gamma.-butyrolactone, .epsilon.-caprolactone, and the like), a
nitrile (such as acetonitrile, propionitrile, and the like), an
aprotic bipolar solvent (such as dimethylsulfoxide,
dimethylformamide, and the like), or a combination thereof. The
choice of the casting solvent depends on a particular photoresist
composition and can be readily made by one of ordinary skill in the
art based on his/her knowledge and experience.
[0167] Pattern-wise 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. It will be
appreciated that exposure using the activating radiation decomposes
the PAG in the exposed areas and generates acid and decomposition
by-products, and that the acid or the by-products then effects a
chemical change in the polymer and nanoparticles (deblocking the
acid sensitive group to generate a base-soluble group, or
alternatively, catalyzing a crosslinking reaction in the exposed
areas). The resolution of such exposure tools may be less than 30
nm.
[0168] Developing the exposed photoresist layer is then
accomplished by treating the exposed layer with 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 a negative tone, based on a polymer
having pendant and/or free acid groups or by-products (derived from
bound or free PAG following irradiation) that inhibit the
dissolution of the nanoparticles, and the developer is preferably a
solvent based. A pattern forms by developing. The solvent developer
can be any suitable developer known in the art. For example, the
solvent developer can be an aliphatic hydrocarbon (such as hexane,
heptane, and the like), an aromatic hydrocarbon (such as toluene,
xylene, and the like), a halogenated hydrocarbon (such as
dichloromethane, 1,2-dichloroethane, 1-chlorohexane, and the like),
an alcohol (such as methanol, ethanol, 1-propanol, iso-propanol,
tert-butanol, 2-methyl-2-butanol, 4-methyl-2-pentanol, and the
like), water, an ether (such as diethyl ether, tetrahydrofuran,
1,4-dioxane, anisole, and the like), a ketone (such as acetone,
methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone,
cyclohexanone, and the like), an ester (such as ethyl acetate,
n-butyl acetate, propylene glycol monomethyl ether acetate (PGMEA),
ethyl lactate, ethyl acetoacetate, and the like), a lactone (such
as .gamma.-butyrolactone, .epsilon.-caprolactone, and the like), a
nitrile (such as acetonitrile, propionitrile, and the like), an
aprotic bipolar solvent (such as dimethylsulfoxide,
dimethylformamide, and the like), or a combination thereof. In an
embodiment, the solvent developer may be a miscible mixture of
solvents, for example, a mixture of an alcohol (iso-propanol) and
ketone (acetone). The choice of the developer solvent depends on a
particular photoresist composition and can be readily made by one
of ordinary skill in the art based on his/her knowledge and
experience.
[0169] The photoresist may, when used in one or more such
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.
[0170] Provided further herein is a method of making a composite,
comprising mixing [0171] a nanoparticle comprising a core and a
coating surrounding the core; and [0172] a polymer, [0173] wherein
the coating of the nanoparticle comprises a ligand, wherein the
ligand is a substituted or unsubstituted C.sub.1-C.sub.16
carboxylic acid or a salt thereof, a substituted or unsubstituted
C.sub.1-C.sub.16 amino acid or a salt thereof, a substituted or
unsubstituted C.sub.1-C.sub.16 dialkyl phosphonate, or a
combination thereof, [0174] and [0175] wherein the polymer is a
polymerization product of [0176] a photoacid generator comprising a
polymerizable group; [0177] at least one unsaturated monomer, which
is different from the photoacid generator comprising a
polymerizable group; and [0178] a chain transfer agent of formula
(I);
[0178] ##STR00028## [0179] wherein: [0180] Z is a y valent
C.sub.1-20 organic group, [0181] x is 0 or 1, and [0182] R.sup.d is
a substituted or unsubstituted C.sub.1-20 alkyl, C.sub.3-20
cycloalkyl, C.sub.6-20 aryl, or C.sub.7-20 aralkyl.
[0183] The invention is further illustrated by the following
examples. All compounds and reagents used below are available
commercially except where a procedure is provided.
Triphenylsulfonium
1,1-difluoro-2-(methacryloyloxy)ethane-1-sulfonate (the TPS F2 PAG
monomer) was obtained commercially from Central Glass.
Examples
Materials
[0184] Zirconium isopropoxide and hafnium isopropoxide were
purchased from Strem Chemicals. Milli-Q water (18.2 M.OMEGA.cm at
25.degree. C.) was used in all experiments. Methyl methacrylate
(MMA) was obtained from Aldrich and was filtered through basic
alumina (Aldrich) to remove the inhibitor.
2,2'-Azobisisobutyronitrile (AIBN; Aldrich) was recrystallized from
methanol. 2-Cyanopropan-2-yl dithiobenzoate (CPDB), isobutyric acid
(IBA), triphenylsulfonium triflate (TPST) and ethyl lactate were
purchased from Aldrich and used as received. Triphenylsulfonium
1,1-difluoro-2-(methacryloyloxy)ethane-1-sulfonate (the TPS F2 PAG
monomer) was supplied by Dow Chemicals and used as received. All
other solvents and chemicals were reagent grade.
Characterization Instruments
.sup.1H Nuclear Magnetic Resonance (NMR) Spectroscopy
[0185] All NMR spectra were recorded on a Bruker AV3400
spectrometer operating at 400 MHz and 298 K using an external lock
(CDCl.sub.3) and utilizing a standard internal reference (solvent
reference). Spectra were collected with 256 scans. Samples were
prepared in deuterated acetone or chloroform.
Solid State Nuclear Magnetic Resonance (SS-NMR)
[0186] SS-NMR is non-destructive and requires very small amounts of
material for analysis (50 mg or less). All SS-NMR samples were
performed on 7.41 Tesla (300 MHz frequency) wide bore
superconducting magnet interfaced with a two-channel Bruker Avance
III spectrometer.
Thermogravimetric Analysis (TGA)
[0187] TGA was performed on a Mettler Toledo instrument STARe
Thermogravimetric analyzer under N.sub.2 atmosphere. The samples
were heated from room temperature to 550.degree. C. with a heating
rate of 10.degree. C./min.
Dynamic Light Scattering (DLS)
[0188] Hydrodynamic diameter measurements (the particle size and
distribution of the nanoparticles) were determined using a
Zetasizer (Malvern Instrument) at a fixed scattering angle of
173.degree. C. Experiments were performed at 25.degree. C. Dilute
solutions of nanoparticles in ethyl lactate were analyzed.
Transmission Electron Microscopy (TEM)
[0189] TEM images were taken by JEOL 1010 Transmission Electron
Microscope equipped with Olympus soft imaging solutions veleta
2k.times.2k wide angle digital camera.
Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR)
Spectroscopy
[0190] ATR-FTIR spectra were obtained on a Nicolet Nexus 5700 FTIR
spectrometer equipped with a Nicolet Smart Orbit single bounce,
diamond ATR accessory (Thermo Electron Corp., Waltham, Mass.).
Spectra were recorded at 8 cm.sup.-1 resolution for 256 scans.
Atomic Force Microscopy (AFM)
[0191] AFM in air was performed using a stand-alone MFP-3D
instrument in tapping mode. The AFM was mounted on an
anti-vibration table (Herzan LLC) and operated within an acoustic
isolation enclosure (TMC).
Procedures
[0192] Synthesis of ZrOz.sub.2-IBA Nanoparticles
(ZrOz.sub.2-Isobutyrate Ligand Capped Nanoparticles)
##STR00029##
[0193] Zirconium isopropoxide (0.6 g) and isobutyric acid (6 mL)
were mixed together in a vial and stirred at 65.degree. C. for 15
minutes. Then 2 mL of IBA/H.sub.2O solution (94/6 v/v %) was added
slowly via a syringe pump into the vial and stirred at 65.degree.
C. for 18 hours. Another 2 mL of the same IBA/H.sub.2O solution was
also added slowly into the vial and stirred for another 3 hours.
The final solution was a relatively yellowish clear solution (no
color change since the beginning). This solution was purified three
times by precipitation method in H.sub.2O and re-dissolved in
acetone. The purified ZrO.sub.2-IBA product was collected using
high speed centrifuge and dried in a vacuum oven overnight. The
product was then characterized by SS-NMR, DLS, TEM, ATR-FTIR, and
TGA.
Synthesis of HfO.sub.2-IBA Nanoparticles (HfO.sub.2--Isobutyrate
Ligand Capped Nanoparticles)
##STR00030##
[0194] Hafnium isopropoxide (0.75 g) and isobutyric acid (6 mL)
were mixed together in a vial and stirred at 65.degree. C. for 15
minutes. Then 2 mL of IBA/H.sub.2O solution (94/6 v/v %) was added
slowly via a syringe pump into the vial and stirred at 65.degree.
C. for 18 hours. Another 2 mL of the same IBA/H.sub.2O solution was
also added slowly into the vial and stirred for another 3 hours.
The final solution was a yellowish clear solution. This solution
was purified three times by precipitation method in H.sub.2O and
re-dissolved in acetone. The purified HfO.sub.2-IBA product was
collected using high speed centrifuge and dried in a vacuum oven
overnight.
Typical Formulation of ZrO.sub.2-IBA Nanoparticles Blending with
TPST Resist Solution
[0195] ZrO.sub.2-IBA nanoparticles (20 mg) and TPST (3 mg) were
dissolved in ethyl lactate (0.8 mL) to make up a concentration of
25 mg/mL ZrO.sub.2-IBA and 15% TPST with respect to the weight of
the nanoparticles. The resist solution was then filtered through a
0.22 .mu.m PTFE filter.
Typical Formulation of HfO.sub.2-IBA Nanoparticles Blending with
TPST Resist Solution
[0196] HfO.sub.2-IBA nanoparticles (20 mg) and TPST (3 mg) were
dissolved in ethyl lactate (0.8 mL) to make up a concentration of
25 mg/mL HfO.sub.2-IBA and 15% TPST with respect to the weight of
the nanoparticles. The resist solution was then filtered through a
0.22 .mu.m PTFE filter.
Typical Synthesis of PMMA-co-PPAG (without Acid End Functionality)
for the `Blending Approach`
##STR00031##
[0197] A solution containing CPDB (0.20 g, 0.90 mmol), PAG (0.45 g,
0.90 mmol), MMA (2.71 g, 27.11 mmol), AIBN (30 mg, 0.18 mmol), and
THF (19 mL) was placed in a round-bottom flask, sealed, and
degassed with Argon for 15 minutes. The solution was then heated at
60.degree. C. for 24 hours. The conversion of the polymer was
determined by .sup.1H-NMR. The polymer was purified by
precipitation method using cold hexane/THF to remove the unreacted
monomers of PAG and MMA. The purified polymer product was then
dried overnight in a vacuum oven. For the characterization of the
purified polymer: number-average MW (M.sub.n) and degree of
polymerization (DP) can be obtained from .sup.1H-NMR, which were
3409 g/mol and PMMA.sub.22-co-PPAG.sub.2, respectively.
Typical Formulation of ZrO.sub.2-IBA Nanoparticles Blending with
PMMA-co-PPAG Resist Solution
[0198] ZrO.sub.2-IBA (16.25 mg) and PMMA.sub.22-co-PPAG.sub.2 (1.69
mg) were dissolved in ethyl lactate (0.65 mL) to make up a
concentration of 25 mg/mL ZrO.sub.2-IBA and 10%
PMMA.sub.22-co-PPAG.sub.2 (i.e., equivalent to 3% PPAG in the
system) with respect to the weight of the ZrO.sub.2-IBA. The resist
solution was then filtered through a 0.22 .mu.m PTFE filter.
Thin Film Preparation of ZrO.sub.2-IBA Blending with TPST (or
PMMA-co-PPAG)
[0199] The resist solutions containing ZrO.sub.2-IBA (25 mg/mL) and
certain % of TPST (or PMMA-co-PPAG) were spin-coated into bare
cleaned Si wafers (7.5 mm.times.7.5 mm). The spin-coating
condition: 200 revolutions per minute (rpm) for 3 seconds (sec),
followed by 2,000 rpm for 60 sec. The film thickness was measured
by FilmTek.
Cleaning Procedure for the Si Wafers Used in this Project
[0200] The Si wafers were ultra-sonicated in HPLC grade acetone for
5 minutes, followed by ultrasonication in HPLC grade IPA for
another 5 minutes. The Si wafers were then dried using nitrogen gas
and put on a hot plate at 150.degree. C. for 10 minutes.
Electron Beam Lithography of the Nanoparticle Resist
[0201] After spin-coating, the wafers were then patterned using EBL
at a 10-20 kV acceleration voltage, with an aperture of 10 .mu.m,
step size of 20 nm and working distance of 7.7 mm. The pattern was
designed using Raith's software and contained line/space patterns
with critical dimension (CD) of 100 nm.
Development of the Nanoparticle Resist
[0202] Following the electron beam exposure, the film was developed
by a solvent based developer under a certain time duration and
dried with a stream of N.sub.2 gas, forming negative tone resist.
For example, for the ZrO.sub.2-IBA (25 mg/mL) blending with 10%
PMMA.sub.22-co-PPAG.sub.2 (i.e., 3% PPAG) system, the exposed film
was developed under IPA/Acetone (97/3%) for 2 minutes.
Characterization of ZrO.sub.2-IBA (and HfO.sub.2-IBA)
Nanoparticles
[0203] .sup.13C-SS-NMR was used to check the conversion of the
metal oxide precursor during the reaction. As FIG. 3 shows, the
disappearance of both CH (.about.70 ppm) and CH.sub.3 (.about.27
ppm) peaks of zirconium isopropoxide (FIG. 2) indicated that this
metal precursor was fully reacted. Moreover, the peak appearance at
.about.183 ppm indicated the successful carboxylate ligand binding
to the nanoparticles.
[0204] Dynamic light scattering (DLS) (FIG. 4) was used to measure
the hydrodynamic size of the nanoparticles and polydispersity
factor (a dimensionless measure of the broadness of particle size
distribution). The number mean diameter and polydispersity factor
for ZrO.sub.2-IBA were .about.2 nm and 0.3, respectively. Meanwhile
for HfO.sub.2-IBA they were .about.4 nm and 0.5, respectively.
[0205] FIG. 5 shows that the ZrO.sub.2-IBA nanoparticles had
relatively spherical shape and .about.3 nm core diameter. This
result is in agreement with the DLS result. Moreover, the TEM
sample preparation requires evaporation of solvent (in this case
ethyl lactate), which can cause the nanoparticles structure to
collapse and form larger aggregates as can be seen in FIG. 5.
[0206] ATR-FTIR was used to detect isobutyrate ligand binding to
the nanoparticles (ZrO.sub.2 and HfO.sub.2). FIGS. 6 and 7 show
strong characteristic peaks of carboxylate anion, which are an
asymmetrical stretching band near 1550 cm.sup.-1 and a symmetrical
stretching band near 1400 cm.sup.-1, indicating successful
carboxylate ligand binding on the nanoparticles. Moreover, the
disappearance of the C.dbd.O peak near 1700 cm.sup.-1 indicated the
successful removal of excess isobutyric acid.
[0207] TGA was used to examine the composition of the nanoparticle
powders from the weight loss % as a function of temperature. Three
weight loss steps can be observed for both ZrO.sub.2-IBA (FIG. 8)
and HfO.sub.2-IBA (FIG. 9). The first step was most likely due to
the water residue (.about.6% for ZrO.sub.2-IBA and .about.3% for
HfO.sub.2-IBA). The second step may be due to some loosely bound
organic ligand (.about.9% for ZrO.sub.2-IBA and .about.14% for
HfO.sub.2-IBA). And the third step was likely due to the
isobutyrate ligand (.about.34% for ZrO.sub.2-IBA and .about.21% for
HfO.sub.2-IBA). The remaining component % after the heating process
belonged to the inorganic core of the nanoparticles: ZrO.sub.2
(.about.50%) and HfO.sub.2 (.about.62%).
Characterization of PMMA-co-PPAG:
[0208] .sup.1H-NMR was used to determine the degree of
polymerization (DP) of the copolymers and thus the number-average
MW (M.sub.n), and to confirm the complete removal of unreacted
monomers. FIG. 10 shows the typical .sup.1H-NMR of
PMMA-co-PPAG.
[0209] The nanoparticle-polymer resist solution was prepared by
blending the metal oxide powder (ZrO.sub.2-IBA or HfO.sub.2-IBA)
with PMMA-co-PPAG in resist solvent (in this case ethyl lactate).
For the ZrO.sub.2-IBA (25 mg/mL) and 3% PPAG system, the film
thickness was measured after the spin-coating process to be
.about.50.+-.0.3 nm. The resist film was patterned using EBL with
area dose ranging from 140-520 .mu.C/cm.sup.2 and various ratios of
critical dimension (CD) to line width (LW). After development in
97% IPA/3% Acetone for 2 minutes, the pattern height was measured
by AFM.
[0210] The atomic force microscopy (AFM) images indicate that the
nanoparticle-polymer resist system can be successfully patterned
and is very promising but still needs further optimization,
especially in the pattern development area. FIG. 11 shows that
patterns can be seen at 140 .mu.C/cm.sup.2 or even lower doses, and
overexpose at 240 .mu.C/cm.sup.2. FIG. 12 shows that although the
line widths have not been fully cleared, better pattern image with
an increase in height was seen with increasing area dose.
[0211] While this disclosure has been described in connection with
what is presently considered to be practical exemplary embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments, but, on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
* * * * *