U.S. patent application number 12/200703 was filed with the patent office on 2009-03-19 for photoresist compositions comprising diamondoid derivatives.
Invention is credited to Robert M. Carlson, Jeremy E. Dahl, Shenggao Liu.
Application Number | 20090075203 12/200703 |
Document ID | / |
Family ID | 34396438 |
Filed Date | 2009-03-19 |
United States Patent
Application |
20090075203 |
Kind Code |
A1 |
Liu; Shenggao ; et
al. |
March 19, 2009 |
PHOTORESIST COMPOSITIONS COMPRISING DIAMONDOID DERIVATIVES
Abstract
Novel positive-working photoresist compositions are disclosed.
The monomers of the base resin of the resist contain
diamondoid-containing pendant groups higher than adamantane in the
polymantane series; for example, diamantane, triamantane,
tetramantane, pentamantane, hexamantane, etc. The
diamondoid-containing pendant group may have hydrophilic-enhancing
substituents such as a hydroxyl group, and may contain a lactone
group. Advantages of the present compositions include enhanced
resolution, sensitivity, and adhesion to the substrate.
Inventors: |
Liu; Shenggao; (Hercules,
CA) ; Dahl; Jeremy E.; (Palo Alto, CA) ;
Carlson; Robert M.; (Petaluma, CA) |
Correspondence
Address: |
CROWELL & MORING LLP;INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Family ID: |
34396438 |
Appl. No.: |
12/200703 |
Filed: |
August 28, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10764407 |
Jan 23, 2004 |
|
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12200703 |
|
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|
60508222 |
Oct 1, 2003 |
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Current U.S.
Class: |
430/285.1 ;
528/271 |
Current CPC
Class: |
Y10S 430/111 20130101;
C07C 2603/86 20170501; C07C 69/54 20130101; G03F 7/0397 20130101;
C07C 2603/90 20170501; C07C 35/44 20130101 |
Class at
Publication: |
430/285.1 ;
528/271 |
International
Class: |
G03F 7/004 20060101
G03F007/004; C08G 61/00 20060101 C08G061/00 |
Claims
1. A positive-working photoresist composition comprising a base
resin represented by the general formula: ##STR00008## wherein
R.sub.1 is selected from the group consisting of --H and
--CH.sub.3; R.sub.2 is selected from the group consisting of --H,
an alkyl group having from 1 to 4 carbon atoms, and an alkoxy group
having from 1 to 4 carbon atoms; R.sub.3 is --H, or a
hydrophilic-enhancing moiety selected from the group consisting of
a hydroxyl group --OH, a keto group .dbd.O, carboxylic acid group
--COOH, and alkoxy group --OR.sub.4, and a group --OC(O)OR.sub.4;
R.sub.4 is --CH.sub.3 or --C.sub.2H.sub.5; a is 0.25 to 0.75;
b+c+d+e is substantially equal to 1-a; with e being greater than 0,
and P.sub.1 is a non-diamondoid, acid-cleavable pendant group.
2. The photoresist composition of claim 1, wherein c ranges from
about 0 to 0.25.
3. The photoresist composition of claim 1, wherein d ranges from
about 0 to 0.25.
4. The photoresist composition of claim 1, wherein e is 0.25 or
less.
5. The photoresist composition of claim 1, wherein c+d+e is 0.25 or
less.
6. The photoresist composition of claim 1, wherein b, the amount of
the adamantane containing monomer, is about equal to c+d+e, the
total amount of the diamantane, triamantane, and higher
diamondoid-containing monomers.
7. The photoresist composition of claim 1, wherein P.sub.1 is a
lactone-containing pendant group.
8. The photoresist composition of claim 1, wherein the average
Onishi number of any of the diamondoid containing monomers is
greater than about 3.
9. The photoresist composition of claim 1, wherein the average
value of the solubility parameter of the base resin, in units of
cal.sup.0.5/cm.sup.1.5, ranges from about 8 to 13.
10. The photoresist composition of claim 1, further including a
photoacid generator selected from the group consisting of an onium
salt, a diazonium salt, an ammonium salt, a phosphonium salt, an
iodonium salt, a sulfonium salt, a selenonium salt, an arsonium
salt, an organic halogeno compound, and an organo-metal/organic
halide compound.
11. The photoresist composition of claim 10, wherein the photoacid
generator has an o-nitorbenzyl type protecting group.
12. The photoresist composition of claim 10, wherein the photoacid
generator generates a sulfonic acid upon photolysis.
13. The photoresist composition of claim 10, wherein the amount of
the photoacid generator in the composition ranges from about 0.01
to 30 weight percent.
14. The photoresist composition of claim 1, wherein the composition
further comprises an additive selected from the group consisting of
a surface active agent, an organic basic compound, an acid
decomposable dissolution inhibiting compound, a dye, a plasticizer,
a photosensitizer, a compound promoting solubility in a developing
solution, and additives comprising hydrophilic diamondoid
derivatives.
15. The photoresist composition of claim 1, wherein the composition
further includes a solvent selected from the group consisting of
ethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone,
.gamma.-butyrolactone, methyl ethyl ketone, ethylene glycol
monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl
acetate, ethylene glycol monoethyl ether acetate, propylene glycol
monomethyl ether (PGME), propylene glycol monomethyl ether acetate
(PGMEA), ethylene carbonate, toluene, ethyl acetate, butyl acetate,
methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl
ethoxypropionate, methyl methoxypropionate, ethyl pyruvate, propyl
pyruvate, N,N-dimethylformamide, dimethylsulfoxide,
N-methylpyrrolidone, and tetrahydrofuran.
16. The photoresist composition of claim 1, wherein b, c, and d are
0.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 10/764,407, filed Jan. 23, 2004, which is incorporated herein
by reference in its entirety. U.S. application Ser. No. 10/764,407
claims the benefit of U.S. Provisional Patent Application No.
60/508,222 filed Oct. 1, 2003 which is also hereby incorporated by
reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention are directed in general
toward high performance photoresist compositions used in
conjunction with eximer laser and electron beam lithography
sources. Specifically, the photoresist compositions of the present
invention include diamondoid derivatives having polymerizable and
hydrophilic-enhancing functionalities. The diamondoids of the
present invention include lower diamondoids such as adamantane,
diamantane, and triamantane, as well as the diamondoids
tetramantane, pentamantanes, and higher compounds.
[0004] 2. State of the Art
[0005] Increasing demands for devices with higher circuit densities
have led to the use of shorter wavelength light sources in optical
lithography. KrF (krypton fluoride) excimer laser lithography
operating at a wavelength of 248 nm has been used for the
production of devices having feature sizes ranging from 0.25 to
0.13 microns. Rapid advances in the miniaturization of
microelectronic devices, and demands for devices with increasingly
greater circuit densities, are requiring the development of new,
imagable polymeric photoresist materials to be used with ArF (argon
fluoride) excimer laser lithography at 193 nm, and there is a need
on the horizon for resist materials which can operate in the
extreme ultraviolet and soft x-ray regim. According to The National
Technology Roadmap for Semiconductors, (Semiconductor Industry
Association, San Jose, Calif., 1997), the next most likely
candidate is an F.sub.2 source operating at 157 nm.
[0006] Conventional g-line (436 nm) and i-line (365 nm)
photoresists are well-balanced in terms of high-resolution, high
sensitivity, and good dry etch resistance, but they typically
comprise a novolac base resin and a diazonaphthoquinone PAC
(photoactive compound), both of which contain a phenolic moiety
that absorbs light having wavelengths below about 365 nm. Thus, the
phenolic based resists cannot be used in these shorter wavelengths
regimes, such as those found in ArF lithography, because they are
completely opaque at 193 nm. The incident radiation cannot
penetrate through the full thickness of the resist. This is a
significant issue at 248 nm (KrF), which is the wavelength used for
0.25 micron and 0.18 micron generation devices.
[0007] Photoresists are materials used to transfer an image onto a
substrate. A layer of the photoresist (or "resist") is formed on a
substrate, and then exposed through a mask to a source of
radiation. The mask has some regions that are opaque, and some
regions that are transparent to the radiation. The portions of the
photoresist that are exposed to the radiation undergo a chemical
transformation such that the pattern of the mask is transferred to
the photoresist layer, which after development provides a relief
image that can be used to selectively process the underlying
substrate.
[0008] In general, a photoresist composition comprises at least a
resin binder and a photoactive agent. The "chemically amplified"
resists in use today were developed for the formation of sub-micron
images and other high performance applications. They may be either
positive or negative acting. In the case of a positive acting
resist, the regions that are exposed to the radiation become more
soluble in the developer, while those areas that are not exposed
remain comparatively less soluble in the developer. Cationic
initiators are used to induce cleavage of certain "blocking groups"
pendant from the photoresist binder resin, or cleavage of certain
groups that comprise a photoresist binder backbone. Upon cleavage
of the blocking group through exposure of a layer of photoresist to
light, a base soluble functional group is formed, such as a
carboxylic acid or an imide, which results in a different
solubility in the developer for the exposed and unexposed regions
of the resist layer.
[0009] As taught by J. D. Plummer et al., in "Silicon VLSI
Technology" (Prentice Hall, Upper Saddle River, N.J., 2000), pp.
221-226, deep ultraviolet (DUV) resists in use today are not
modified novolac resists. Deep ultraviolet (DUV) photoresist
materials in use today are based on chemistry that makes use of a
phenomenon called "chemical amplification." Conventional resist
materials that were designed to operate at 365 nm and 248 nm
achieved quantum efficiencies of about 0.3, meaning that about 30
percent of the incoming photons interacted with the photoactive
compound to expose the resist.
[0010] DUV resists, according to Plummer, work on a different
principle that is illustrated in FIG. 1. Referring to FIG. 1,
incoming photons react with a photo-acid generator (PAG) 101,
creating an acid molecule 102. Acid molecules 102 act as catalysts
during a subsequent resistant bake to change the properties of the
resist in the exposed region. The photo-acid generator 101
initiates a chemical reaction that makes the resist soluble in a
developer in a subsequent developing step that occurs after
exposure to the radiation. The reactions are catalytic and the acid
molecule 102 is regenerated after each chemical reaction and may
therefore participate in tens or even hundreds of further
reactions. This is what allows the overall quantum efficiency in a
chemically amplified resist to be much larger than 1, and is
responsible for improving the sensitivity of a chemically amplified
resist from the previous values of about 100 mJ cm.sup.-2 for
conventional diazonaphthoquinones to the current values of about
20-40 for the new chemically amplified the ultraviolet
photoresists.
[0011] The principle of a chemically amplified photoresist is
illustrated in FIG. 1. Referring again to FIG. 1, photoresists of
the present intention included in general a photo-acid generator
101 and a blocked or protected polymer 103 which is insoluble in
the developer because of attached molecules 104 (labeled
additionally "INSOL" in FIG. 1). Incident deep ultraviolet photons
interact with the photo-acid generator 101 to create an acid
molecule 102. The spatial pattern of the acid molecules 102 within
the resist create a "stored," or latent image of the mask pattern.
After exposure, the substrate undergoing processing is baked at a
temperature of about 120 degrees C. in a process called post
exposure bake (PEB). The heat from the post exposure bake provides
the energy needed for the reaction between the acid molecules 102
and the insoluble pendant groups 104 where the reaction is to take
place. The heat from the post exposure bake provides the energy
needed for the reaction between acid molecules 102 and the
insoluble pendant groups 104 attached to main polymer chain 103;
the heat from the post exposure bake also provides diffusion
mobility for the acid molecules 102 to seek out unreacted pendant
groups 104, the essence of the catalytic nature of this
reaction.
[0012] During the post exposure bake, the insoluble pendant groups
104 are either converted to soluble pendant groups 105, or cleaved
from the polymer chain 103. In either case, the insoluble, blocked
polymer is converted to an unblocked polymer as soluble in an
aqueous alkaline developer.
[0013] The polymers that comprise the chain 103 may comprise such
polymers as polyamides, polyimides, polyesters, and polycarbonates
since these are easily processed, mechanically strong, and
thermally stable, and thus have become important materials in the
microelectronics industry. Introduction of polycyclic hydrocarbon
substituents, including alicyclic rings and other caged
hydrocarbons, have been shown to impart greater solubility and
enhanced rigidity, improving the mechanical and thermal properties
of the resulting polymers. Previous studies have involved the
introduction of adamantyl groups into 193 nm resists, but to the
applicant's knowledge, there have been no previous attempts to
incorporate any diamondoid compound higher than adamantane into the
base resin structure. These composition may incorporate lower
diamondoids such as diamantane and/or triamantane into the resist
structure, or they may include diamondoids such as tetramantane and
higher.
[0014] In many instances, the use of photoacid generators that
produce weaker photoacids and resists compositions that require
lower post exposure bake (PEB) temperatures, such as 110.degree. C.
or less, would represent a significant advantage. For example, if
the desired deprotection chemistry could be carried out with a
weaker acid, a wider range of photoacid generators could
potentially be employed. Moreover, the industry continually seeks
use of lowered post exposure bake temperatures because of
uniformity considerations.
[0015] Thus, it would be advantageous to have new photoresist
compositions, particularly positive acting photoresist
compositions, that may be effectively imaged in the sub-200 nm
wavelength region, such as 193 nm and 157 nm. It is also desirable
to provide photoresist compositions that employ photoacid
generators.
[0016] Adamantane, the smallest member of the family of diamondoid
compounds, is a highly condensed, exceptionally stable hydrocarbon
compound. Adamantane and a range of adamantyl derivatives have been
commercially available for years. This has made adamantane a
regular substituent in a wide variety of families of chemical
structures when a large, stable, bulky hydrocarbon moiety is
desired. Adamantyl groups are found in polymers and are currently
employed as constituents of positive photoresist materials.
[0017] Diamantane is also a highly condensed hydrocarbon compound.
It is made up of two face-fused adamantane units. It can be
synthesized but also occurs naturally in petroleum and can be
isolated from various deep well hydrocarbon streams such as natural
gas streams. A number of diamantane derivatives have been reported
in the literature including a variety of mono and poly halides,
mono- and dihydroxy materials, mono- and dicarboxylic acid
derivatives, mono- and dialkynyls, and mono- and diamines. In
addition, there are a number of diamantane-containing polymers in
the literature but generally these materials appear to link the
diamantane into the polymer through two or more links such that the
diamantane forms an integral part of the polymer backbone.
[0018] We now desire to provide a family of derivatives of
diamantane that can form polymers having pendant diamantyl groups.
In addition, these derivative can contain additional functionality
to impart desirable properties to the polymers they form.
SUMMARY OF THE INVENTION
[0019] Embodiments of the present invention are directed to
positive working photoresist compositions useable at lithography
wavelengths less than about 200 nm, such as the 193 nm wavelength
from an ArF eximer laser, a 157 nm F.sub.2 light source, or e-beam
excitation. The base resins of the present resist compositions
contain acid-cleavable, pendant diamondoid groups that are
generally higher in the polymantane series than adamantane. The
diamondoid pendant groups have substituents that increase the
hydrophilic nature of the diamondoids, thereby rendering them more
soluble in an alkali developer, and consequently enhancing their
ability to resolve fine feature sizes.
[0020] Embodiments of the present invention specifically include
polymerizable diamantyl monomers having the formula Pg-D-(R).sub.n,
wherein D is a diamantyl nucleus; Pg is a polymerizable group
covalently bonded to a carbon of the diamantyl nucleus; n is an
integer ranging from 1 to 6, inclusive; at least one of the R's is
a hydrophilic-enhancing moiety; and each of the remaining R's is
independently selected from the group consisting of hydrogen and a
hydrophilic-enhancing moiety. The hydrophilic-enhancing moieties of
these diamantyl monomers may be selected from the group consisting
of a hydroxyl group --OH, a carboxylic group --COOH, an alkoxy
group --OCH.sub.3 or --OC.sub.2H.sub.5, a keto group --C(O)--, and
--OC(O)--OCH.sub.3 or --OC(O)--OC.sub.2H.sub.5.
[0021] Other embodiments of the present invention provide for
triamantyl monomers having polymerizable groups and
hydrophilic-enhancing moities similar to those for diamantyl
monomers discussed above, as well as diamondoid-containing monomers
with polymerizable groups and hydrophilic-enhancing moities,
wherein the diamondoid portion of the diamondoid-containing monomer
is selected from the group consisting of tetramantane,
pentamantane, hexamantane, heptamantane, octamantane, nonamantane,
decamantane, and undecamantane.
[0022] Other embodiments of the present invention provide for
methods of forming a layer of patterned photoresist on the surface
of a substrate, the method comprising the steps of:
[0023] a) depositing on the surface of the substrate a layer
comprising the above mentioned diamantyl, triamantyl, and higher
diamondoid containing monomers having polymerizable groups and
hydrophilic-enhancing moieties,
[0024] b) polymerizing the deposited monomers to yield a
polymerized layer comprising a photo-labile polymer on the surface
of the substrate; and
[0025] c) exposing selected regions of the polymerized layer to an
electromagnetic beam, thereby modifying the photo-labile polymer in
those regions exposed to the electromagnetic beam to yield a
selectively modified layer.
[0026] In another embodiment, the base resin of the resist may be
represented by the general formula:
##STR00001##
[0027] wherein R.sub.1 is selected from the group consisting of --H
and --CH.sub.3;
[0028] R.sub.2 is selected from the group consisting of --H, an
alkyl group having from 1 to 4 carbon atoms, and an alkoxy group
having from 1 to 4 carbon atoms;
[0029] R.sub.3 is --H, or a hydrophilic-enhancing moiety selected
from the group consisting of a hydroxyl group --OH, a keto group,
carboxylic acid group --COOH, and alkoxy group --OR.sub.4, and
--OC(O)OR.sub.4;
[0030] R.sub.4 is --CH.sub.3 or --C.sub.2H.sub.5;
[0031] a is 0.25 to 0.75;
[0032] b+c=1-a;
[0033] c is greater than zero; and
[0034] P.sub.1 is a non-diamondoid, acid-cleavable pendant
group.
[0035] According to other embodiments of the present invention, the
diamondoid pendant groups of the base resin may contain lactone
groups, and they may be linked to the main polymer chain by more
than one ester linking group, thereby providing multiple sites on
which the photo-generated acid can react. This has advantages of
allowing either weaker acids, lower post exposure bake
temperatures, and a greater variety of photo-acid generators from
which to choose. The diamondoid pendant groups may contain hetero
atoms in addition to the oxygen atom of a lactone group. The hetero
atoms may be selected from the group of O, N, B, S, and/or P. Block
co-polymers are also contemplated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] This invention will be further described with reference
being made to the accompanying drawings in which:
[0037] FIG. 1 is a schematic diagram illustrating the manner in
which a positive, chemically amplified resist operates, taken from
J. D. Plummer et al., in "Silicon VLSI Technology" (Prentice Hall,
Upper Saddle River, N.J., 2000), pp. 221-226;
[0038] FIG. 2 illustrates an exemplary photoresist that has been
used for KrF (248 nm) lithography, and an exemplary photoresist
that has been used for ArF (193 nm);
[0039] FIG. 3 illustrates the relationship of a diamondoid to the
diamond crystal lattice, and enumerates by stoichiometric formula
many of the diamondoids available;
[0040] FIG. 4 shows an exemplary process flow for isolating
diamondoids from petroleum;
[0041] FIG. 5A is a flow chart that illustrates how diamondoids may
be derivatized with hydrophilic-enhancing groups and polymerizable
groups to form feed monomers, which may then be polymerized to form
the base resin of the resist; the base resin is then mixed with a
solvent, photoacid generator, and other additives to produce the
fully formulated resist;
[0042] FIG. 5B is a schematic showing how chemistry and processing
of diamondoids into derivatized diamondoids contribute to
photoresist properties;
[0043] FIGS. 6-20 illustrate exemplary pathways for derivatizing
diamondoids;
[0044] FIGS. 21A-B illustrate exemplary base resins of the present
invention, wherein the base resin contains a diamondoid pendant
group higher in the polymantane series than adamantane (although
they may contain adamantane as well);
[0045] FIGS. 21C-D illustrate exemplary non-diamondoid, lactone
containing pendant groups;
[0046] FIGS. 22A-E gives nomenclature for the present structural
formulas, illustrating how the hydrophilic-enhancing and
polymerizable substituents on the diamondoids higher than
adamantane have a variety of attachment points;
[0047] FIGS. 23A-B illustrate Ohnishi parameter calculations for
base resin repeat units having adamantane, diamantane, triamantane,
and iso-tetramantane pendant groups, and for the same pendant
groups with 1, 2, 3, and 4 hydroxyl groups, respectively;
[0048] FIG. 24A-D shows exemplary diamondoid-containing monomers
with multiple acid-labile sites;
[0049] FIGS. 25A-B illustrate exemplary lactone-containing pendant
groups, wherein the lactone group may be part of either the
diamondoid-containing pendant group, or the non-diamondoid
containing pendant group;
[0050] FIG. 26 illustrates an exemplary block co-polymer of the
present invention;
[0051] FIG. 27 illustrates a synthetic pathway for producing a
polymer containing iso-tetramantane pendant groups;
[0052] FIG. 28 shows the total ion chromatogram (TIC) of the
resulting hydroxylation reaction mixture (10-18 min.);
[0053] FIG. 29 shows the TIC of the separated di-hydroxylated
diamantane with its corresponding mass spectrum;
[0054] FIG. 30 shows the TIC of the separated tri-hydroxylated
diamantane isomers with a mass spectrum of an isomer;
[0055] FIG. 31 shows a process to separate and purify the
tri-hydroxylated diamantanes from the hydroxylation reaction
mixture: step 1: water extraction; step 2: first flash column
chromatography; step 3: second flash column chromatography. In one
embodiment of the present invention, step 2 may be eliminated.
[0056] FIG. 32 shows the TIC of the precipitated solids from the
hydroxylation reaction, and the mass spectrum at 17.27 minutes
identifying the tetra-hydroxylated diamantanes;
[0057] FIG. 33 shows the TIC of the esterification reaction
mixtures (A from example 10 and B from example 11) between 13 and
18 minutes; and
[0058] FIG. 34 shows the TIC of the separated mono-hydroxyl
diamantane methacrylate isomers with a mass spectrum of one of the
isomer.
DETAILED DESCRIPTION OF THE INVENTION
[0059] Embodiments of the present invention include diamondoids as
pendant groups of the base resin of a positive photoresist
composition. The present disclosure will be organized in the
following manner: first, the term diamondoids will be defined,
followed by a discussion of isolation methods of diamondoids from
petroleum feedstocks, the derivatization of those isolated
diamondoids, and then polymerization of the derivatized diamondoids
into photoresist base resins.
Definition of Diamondoids
[0060] The term "diamondoids" refers to substituted and
unsubstituted caged compounds of the adamantane series including
adamantane, diamantane, triamantane, tetramantane, pentamantane,
hexamantane, heptamantane, octamantane, nonamantane, decamantane,
undecamantane, and the like, including all isomers and
stereoisomers thereof. The compounds have a "diamondoid" topology,
which means their carbon atom arrangement is superimposable on a
fragment of an FCC diamond lattice. Substituted diamondoids
comprise from 1 to 10 and preferably 1 to 4 independently-selected
alkyl substituents. Diamondoids include "lower diamondoids" and
"diamondoids," as these terms are defined herein, as well as
mixtures of any combination of lower and diamondoids.
[0061] The term "lower diamondoids" refers to adamantane,
diamantane and triamantane and any and/or all unsubstituted and
substituted derivatives of adamantane, diamantane and triamantane.
These lower diamondoid components show no isomers or chirality and
are readily synthesized, distinguishing them from
"diamondoids."
[0062] The term "diamondoids" refers to any and/or all substituted
and unsubstituted tetramantane components; to any and/or all
substituted and unsubstituted pentamantane components; to any
and/or all substituted and unsubstituted hexamantane components; to
any and/or all substituted and unsubstituted heptamantane
components; to any and/or all substituted and unsubstituted
octamantane components; to any and/or all substituted and
unsubstituted nonamantane components; to any and/or all substituted
and unsubstituted decamantane components; to any and/or all
substituted and unsubstituted undecamantane components; as well as
mixtures of the above and isomers and stereoisomers of
tetramantane, pentamantane, hexamantane, heptamantane, octamantane,
nonamantane, decamantane, and undecamantane.
[0063] Adamantane chemistry has been reviewed by Fort, Jr. et al.
in "Adamantane: Consequences of the Diamondoid Structure," Chem.
Rev. vol. 64, pp. 277-300 (1964). Adamantane is the smallest member
of the diamondoid series and may be thought of as a single cage
crystalline subunit. Diamantane contains two subunits, triamantane
three, tetramantane four, and so on. While there is only one
isomeric form of adamantane, diamantane, and triamantane, there are
four different isomers of tetramantane (two of which represent an
enantiomeric pair), i.e., four different possible ways of arranging
the four adamantane subunits. The number of possible isomers
increases non-linearly with each higher member of the diamondoid
series, pentamantane, hexamantane, heptamantane, octamantane,
nonamantane, decamantane, etc.
[0064] Adamantane, which is commercially available, has been
studied extensively. The studies have been directed toward a number
of areas, such as thermodynamic stability, functionalization, and
the properties of adamantane-containing materials. For instance,
the following patents discuss materials comprising adamantane
subunits: U.S. Pat. No. 3,457,318 teaches the preparation of
polymers from alkenyl adamantanes; U.S. Pat. No. 3,832,332 teaches
a polyamide polymer forms from alkyladamantane diamine; U.S. Pat.
No. 5,017,734 discusses the formation of thermally stable resins
from adamantane derivatives; and U.S. Pat. No. 6,235,851 reports
the synthesis and polymerization of a variety of adamantane
derivatives.
[0065] In contrast, the diamondoids, have received comparatively
little attention in the scientific literature. McKervay et al. have
reported the synthesis of anti-tetramantane in low yields using a
laborious, multistep process in "Synthetic Approaches to Large
Diamondoid Hydrocarbons," Tetrahedron, vol. 36, pp. 971-992 (1980).
To the inventor's knowledge, this is the only diamondoid that has
been synthesized to date. Lin et al. have suggested the existence
of, but did not isolate, tetramantane, pentamantane, and
hexamantane in deep petroleum reservoirs in light of mass
spectroscopic studies, reported in "Natural Occurrence of
Tetramantane (C.sub.22H.sub.28), Pentamantane (C.sub.26H.sub.32)
and Hexamantane (C.sub.30H.sub.36) in a Deep Petroleum Reservoir,"
Fuel, vol. 74(10), pp. 1512-1521 (1995). The possible presence of
tetramantane and pentamantane in pot material after a distillation
of a diamondoid-containing feedstock has been discussed by Chen et
al. in U.S. Pat. No. 5,414,189.
[0066] The four tetramantane structures are iso-tetramantane
[1(2).sub.3], anti-tetramantane [121] and two enantiomers of
skew-tetramantane [123], with the bracketed nomenclature for these
diamondoids in accordance with a convention established by Balaban
et al. in "Systematic Classification and Nomenclature of Diamond
Hydrocarbons-I," Tetrahedron vol. 34, pp. 3599-3606 (1978). All
four tetramantanes have the formula C.sub.22H.sub.28 (molecular
weight 292). There are ten possible pentamantanes, nine having the
molecular formula C.sub.26H.sub.32 (molecular weight 344) and among
these nine, there are three pairs of enantiomers represented
generally by [12(1)3], [1234], [1213] with the nine enantiomeric
pentamantanes represented by [12(3)4], [1(2,3)4], [1212]. There
also exists a pentamantane [1231] represented by the molecular
formula C.sub.25H.sub.30 (molecular weight 330).
[0067] Hexamantanes exist in thirty-nine possible structures with
twenty eight having the molecular formula C.sub.30H.sub.36
(molecular weight 396) and of these, six are symmetrical; ten
hexamantanes have the molecular formula C.sub.29H.sub.34 (molecular
weight 382) and the remaining hexamantane [12312] has the molecular
formula C.sub.26H.sub.30 (molecular weight 342).
[0068] Heptamantanes are postulated to exist in 160 possible
structures with 85 having the molecular formula C.sub.34H.sub.40
(molecular weight 448) and of these, seven are achiral, having no
enantiomers. Of the remaining heptamantanes 67 have the molecular
formula C.sub.33H.sub.38 (molecular weight 434), six have the
molecular formula C.sub.32H.sub.36 (molecular weight 420) and the
remaining two have the molecular formula C.sub.30H.sub.34
(molecular weight 394).
[0069] Octamantanes possess eight of the adamantane subunits and
exist with five different molecular weights. Among the
octamantanes, 18 have the molecular formula C.sub.34H.sub.38
(molecular weight 446). Octamantanes also have the molecular
formula C.sub.38H.sub.44 (molecular weight 500); C.sub.37H.sub.42
(molecular weight 486); C.sub.36H.sub.40 (molecular weight 472),
and C.sub.33H.sub.36 (molecular weight 432).
[0070] Nonamantanes exist within six families of different
molecular weights having the following molecular formulas:
C.sub.42H.sub.48 (molecular weight 552), C.sub.41H.sub.46
(molecular weight 538), C.sub.40H.sub.44 (molecular weight 524,
C.sub.38H.sub.42 (molecular weight 498), C.sub.37H.sub.40
(molecular weight 484) and C.sub.34H.sub.36 (molecular weight
444).
[0071] Decamantane exists within families of seven different
molecular weights. Among the decamantanes, there is a single
decamantane having the molecular formula C.sub.35H.sub.36
(molecular weight 456) which is structurally compact in relation to
the other decamantanes. The other decamantane families have the
molecular formulas: C.sub.46H.sub.52 (molecular weight 604);
C.sub.45H.sub.50 (molecular weight 590); C.sub.44H.sub.48
(molecular weight 576); C.sub.42H.sub.46 (molecular weight 550);
C.sub.41H.sub.44 (molecular weight 536); and C.sub.38H.sub.40
(molecular weight 496).
[0072] Undecamantane exists within families of eight different
molecular weights. Among the undecamantanes there are two
undecamantanes having the molecular formula C.sub.39H.sub.40
(molecular weight 508) which are structurally compact in relation
to the other undecamantanes. The other undecamantane families have
the molecular formulas C.sub.41H.sub.42 (molecular weight 534);
C.sub.42H.sub.44 (molecular weight 548); C.sub.45H.sub.48
(molecular weight 588); C.sub.46H.sub.50 (molecular weight 602);
C.sub.48H.sub.52 (molecular weight 628); C.sub.49H.sub.54
(molecular weight 642); and C.sub.50H.sub.56 (molecular weight
656).
Isolation of Diamondoids from Petroleum Feedstocks
[0073] Feedstocks that contain recoverable amounts of diamondoids
include, for example, natural gas condensates and refinery streams
resulting from cracking, distillation, coking processes, and the
like. Particularly preferred feedstocks originate from the Norphlet
Formation in the Gulf of Mexico and the LeDuc Formation in
Canada.
[0074] These feedstocks contain large proportions of lower
diamondoids (often as much as about two thirds) and lower but
significant amounts of diamondoids (often as much as about 0.3 to
0.5 percent by weight). The processing of such feedstocks to remove
non-diamondoids and to separate higher and lower diamondoids (if
desired) can be carried out using, by way of example only, size
separation techniques such as membranes, molecular sieves, etc.,
evaporation and thermal separators either under normal or reduced
pressures, extractors, electrostatic separators, crystallization,
chromatography, well head separators, and the like.
[0075] A preferred separation method typically includes
distillation of the feedstock. This can remove low-boiling,
non-diamondoid components. It can also remove or separate out lower
and diamondoid components having a boiling point less than that of
the diamondoid(s) selected for isolation. In either instance, the
lower cuts will be enriched in lower diamondoids and low boiling
point non-diamondoid materials. Distillation can be operated to
provide several cuts in the temperature range of interest to
provide the initial isolation of the identified diamondoid. The
cuts, which are enriched in diamondoids or the diamondoid of
interest, are retained and may require further purification. Other
methods for the removal of contaminants and further purification of
an enriched diamondoid fraction can additionally include the
following nonlimiting examples: size separation techniques,
evaporation either under normal or reduced pressure, sublimation,
crystallization, chromatography, well head separators, flash
distillation, fixed and fluid bed reactors, reduced pressure, and
the like.
[0076] The removal of non-diamondoids may also include a pyrolysis
step either prior or subsequent to distillation. Pyrolysis is an
effective method to remove hydrocarbonaceous, non-diamondoid
components from the feedstock. It is effected by heating the
feedstock under vacuum conditions, or in an inert atmosphere, to a
temperature of at least about 390.degree. C., and most preferably
to a temperature in the range of about 410 to 450.degree. C.
Pyrolysis is continued for a sufficient length of time, and at a
sufficiently high temperature, to thermally degrade at least about
10 percent by weight of the non-diamondoid components that were in
the feed material prior to pyrolysis. More preferably at least
about 50 percent by weight, and even more preferably at least 90
percent by weight of the non-diamondoids are thermally
degraded.
[0077] While pyrolysis is preferred in one embodiment, it is not
always necessary to facilitate the recovery, isolation or
purification of diamondoids. Other separation methods may allow for
the concentration of diamondoids to be sufficiently high given
certain feedstocks such that direct purification methods such as
chromatography including preparative gas chromatography and high
performance liquid chromatography, crystallization, fractional
sublimation may be used to isolate diamondoids.
[0078] Even after distillation or pyrolysis/distillation, further
purification of the material may be desired to provide selected
diamondoids for use in the compositions employed in this invention.
Such purification techniques include chromatography,
crystallization, thermal diffusion techniques, zone refining,
progressive recrystallization, size separation, and the like. For
instance, in one process, the recovered feedstock is subjected to
the following additional procedures: 1) gravity column
chromatography using silver nitrate impregnated silica gel; 2)
two-column preparative capillary gas chromatography to isolate
diamondoids; 3) crystallization to provide crystals of the highly
concentrated diamondoids.
[0079] An alternative process is to use single or multiple column
liquid chromatography, including high performance liquid
chromatography, to isolate the diamondoids of interest. As above,
multiple columns with different selectivities may be used. Further
processing using these methods allow for more refined separations
which can lead to a substantially pure component.
[0080] Detailed methods for processing feedstocks to obtain
diamondoid compositions are set forth in U.S. Provisional Patent
Application No. 60/262,842 filed Jan. 19, 2001; U.S. Provisional
Patent Application No. 60/300,148 filed Jun. 21, 2001; and U.S.
Provisional Patent Application No. 60/307,063 filed Jul. 20, 2001,
incorporated by reference herein in their entirety.
Derivatization of Diamondoids
[0081] According to the present embodiments, diamondoid pendant
groups are derivatized with at least one functional group to allow
attachment to the base polymer chain. Preferably these derivatives
have the following Formula I:
##STR00002##
wherein D is a diamondoid nucleus; and, R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5 and R.sup.6 are each independently selected from a
group consisting of hydrogen and covalently bonded functional
groups, provided that there is at least one functional group. More
preferably the functionalized diamondoids contain either one or two
functional groups.
[0082] In one aspect, as described in U.S. Ser. No. 10/046,486, in
the functionalized diamondoids represented by Formula I, R.sup.1,
R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are preferably
independently selected from a group of moieties consisting of --H,
--F, --Cl, --Br, --I, --OH, --SH, --NH.sub.2, --NHCOCH.sub.3,
--NHCHO, --CO.sub.2H, --CO.sub.2R', --COCl, --CHO, --CH.sub.2OH,
.dbd.O, --NO.sub.2, --CH.dbd.CH.sub.2, --C.ident.CH and
--C.sub.6H.sub.5; where R' is alkyl (preferably ethyl) provided
that R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are
not all hydrogen. Typically one or two of R.sup.1-R.sup.6 are
nonhydrogen moieties and the remaining R's are hydrogens.
[0083] Some functionalized diamondoids can be prepared from
diamondoid in a single reaction step. These materials are referred
to herein as "primary functionalized diamondoids" and include, for
example, diamondoids of Formula I wherein the functionalizing
groups are halogens, such as -bromos and -chloros, -oxides,
-hydroxyls and -nitros as well as other derivatives formed in one
reaction from a diamondoid.
[0084] In another aspect, the functionalized diamondoids are
materials prepared from a primary functionalized diamondoid by one
or more subsequent reaction steps. These materials are sometimes
referred to herein as "secondary functionalized diamondoids." It
will be appreciated that in some cases one primary functionalized
diamondoid may be conveniently formed by conversion of another
primary material. For example, a poly-bromo material can be formed
either by single step bromination or by several repeated
brominations. Similarly, a hydroxyl diamondoid can be formed
directly from a diamondoid in one step or can be prepared by
reaction of a bromo-diamondoid, a diamondoid-oxide or the like.
Notwithstanding this, to avoid confusion, the primary materials
will not be included here in the representative secondary
materials. They will, however, be depicted in various figures
showing reactions for forming primary and secondary materials to
depict both routes to them.
[0085] The functionalized groups available for synthesis of
secondary functionalized diamondoids can be selected from a wide
range of groups including chloro, bromo, hydroxides, etc. Thus, the
following types of secondary materials are merely
representatives.
[0086] Representative secondary functionalized diamondoid
functional groups include fluoro, iodo, thio, sulfonyl halide,
sulfonates, alkyl, haloalkyl, alkoxyl, haloalkenyl, alkynyl,
haloalkynyl, hydroxyalkyl, heteroaryl, alkylthio, alkoxy;
aminoalkyl, aminoalkoxy, aryl, heterocycloalkoxy, cycloalkyloxy,
aryloxy, and heteroaryloxy.
[0087] Other functional groups that can be present in secondary
functionalized diamondoids are represented by the formula --C(O)Z
wherein Z is hydrogen, alkyl, halo, haloalkyl, halothio, amino,
monosubstituted amino, disubstituted amino, cycloalkyl, aryl,
heteroaryl, heterocyclic; by --CO.sub.2Z wherein Z is as defined
previously; by --R.sup.7COZ and --R.sup.7CO.sub.2Z wherein R.sup.7
is alkylene, aminoalkylene, or haloalkylene and Z is as defined
previously; by --NH.sub.2; --NHR', --NR'R'', and --N.sup.+R'R''R'''
wherein R', R'', and R''' are independently alkyl, amino, thio,
thioalkyl, heteroalkyl, aryl, or heteroaryl; by
--R.sup.8NHCOR.sup.9 wherein R.sup.8 is --CH.sub.2, --OCH.sub.2,
--NHCH.sub.2, --CH.sub.2CH.sub.2, --OCH.sub.2CH.sub.2 and R.sup.9
is alkyl, aryl, heteroaryl, aralkyl, or heteroaralkly; and by
--R.sup.10CONHR.sup.11 wherein R.sup.10 is selected from
--CH.sub.2, --OCH.sub.2, --NHCH.sub.2, --CH.sub.2CH.sub.2, and
--OCH.sub.2CH.sub.2, and R.sup.11 is selected from alkyl, aryl,
heteroaryl, aralkyl, and heteroaralkyl.
[0088] In a further aspect, one or more of the functional groups on
the functionalized diamondoids may be of the formulae:
##STR00003##
wherein n is 2 or 3; X is --O--, --S--, or --C(O)--; Y is .dbd.O or
.dbd.S; and R.sup.2, R.sup.13, R.sup.14, and R.sup.15 are
independently hydrogen, alkyl, heteroalkyl, aryl or heteroaryl;
.dbd.N-Z'', wherein Z'' is hydrogen, amino, hydroxyl, alkyl,
##STR00004##
cyano, cyanoalkyl, cyanoaryl, or cyanoalkylamino.
[0089] In a further embodiment, one or more of the functional
groups on the functionalized diamondoid is --NHR', --NR'R'',
--N.sup.+R'R''R''', or --NHQ'' wherein R', R'', and R'''
independently are hydrogen; aryl; heteroaryl with up to 7 ring
members; alkyl; alkenyl; or alkynyl, wherein the alkyl, alkenyl and
alkynyl residues can be branched, unbranched or cyclized and
optionally substituted with halogen, aryl or heteroaryl with up to
7 ring members; or R' and R'' together with the nitrogen atom form
a heterocyclic group with up to 7 ring members. Q'' is thio,
thioalkyl, amino, monosubstituted amino, disubstituted amino, or
trisubstituted amino with an appropriate counterion such as
halogen, hydroxide, sulfate, nitrate, phosphate or other anion.
[0090] In still a further embodiment, the functional group on the
functionalized diamondoid is --COOR.sup.16 wherein R.sup.16 is
alkyl, aryl, or aralkyl; --COR.sup.17, wherein R.sup.17 is alkyl,
aryl, or heteroalkyl, --NHNHO, --R.sup.18NHCOR.sup.19 wherein
R.sup.18 is absent or selected from alkyl, aryl, or aralkyl,
R.sup.19 is hydrogen, alkyl, --N.sub.2, aryl, amino, or
--NHR.sup.20 wherein R.sup.20 is hydrogen, --SO.sub.2-aryl,
--SO.sub.2-alkyl, or --SO.sub.2-aralkyl, --CONHR.sup.21 wherein
R.sup.21 is hydrogen, alkyl, and aralkyl; --CSNHR.sup.21 wherein
R.sup.21 is as defined above; and --NR.sup.22--(CH.sub.2).sub.n
NR.sup.23R.sup.24, wherein R.sup.22, R.sup.23, R.sup.24 are
independently selected from hydrogen, alkyl, and aryl, and n is
from 1 to 20.
[0091] In an additional embodiment, the functional group on the
functionalized diamondoid may be --N.dbd.C.dbd.S; --N.dbd.C.dbd.O;
--R--N.dbd.C.dbd.O; --R--N.dbd.C.dbd.S; --N.dbd.S.dbd.O; or
--R--N.dbd.S.dbd.O wherein R is alkyl; --PH.sub.2; --POX.sub.2
wherein X is halo; --PO(OH).sub.2; --OSO.sub.3H; --SO.sub.2H; --SOX
wherein X is halo; --SO.sub.2R wherein R is alkyl; --SO.sub.2OR
wherein R is alkyl; --SONR.sup.26R.sup.27 wherein R.sup.26 and
R.sup.27 are independently hydrogen or alkyl; --N.sub.3; --OC(O)Cl;
or --OC(O)SCl.
[0092] In a further aspect, the functionalizing group may form a
covalent bond to two or more diamondoids and thus serves as a
linking group between the two or more diamondoids. This provides
functionalized diamondoids of Formula II:
D-L-(D).sub.n
wherein D is a diamondoid nucleus and L is a linking group and n is
1 or more such as 1 to 10 and especially 1 to 4.
[0093] In this embodiment, the linking group L may be
--N.dbd.C--N--
##STR00005##
wherein R.sup.28, R.sup.29, R.sup.30, R.sup.31, R.sup.32, R.sup.33
are independently hydrogen or alkyl, and n and m are independently
from 2 to 20;
##STR00006##
wherein R.sup.28, R.sup.29, R.sup.30, R.sup.31, R.sup.32, and
R.sup.33 are hydrogen or alkyl; R.sup.34, R.sup.35, R.sup.36, and
R.sup.37 are independently absent or hydrogen or alkyl with the
proviso that at least one of R.sup.34, R.sup.35, R.sup.36, and
R.sup.37 is present; and n and m are independently from 2 to 20 or
the like. The counterion may any acceptable monovalent anion, for
example, halogen, hydroxide, sulfate, nitrate, phosphate, and the
like.
[0094] In another aspect, the present invention relates to
functionalized diamondoids of Formula III:
R.sup.38-D-D-R.sup.39
wherein each D is a diamondoid nucleus and R.sup.38 and R.sup.39
are substituents on the diamondoid nucleus and are independently
hydrogen or a functionalizing group. Preferably the material
contains either 1 or 2 functional groups. Preferably R.sup.38 and
R.sup.39 are halo; cyano; aryl; arylalkoxy; aminoalkyl; or
--COOR.sup.40 wherein R.sup.40 is hydrogen or alkyl.
[0095] In an additional aspect, the present invention provides
salts, individual isomers, and mixtures of isomers of diamondoid
derivatives of Formulae I, II, and III.
[0096] Turning now to the derivatization reaction of diamondoids,
there are three different carbons in the diamondoids skeleton:
quaternary (4.degree. or C-4), tertiary (3.degree. or C-3), and
secondary (2.degree. or C-2) carbons. Of those different carbons,
quaternary carbons are impossible to perform any kind of reactions
on. Chemical reactions can only take place on those tertiary
(3.degree. or C-3) and secondary (2.degree. or C-2) carbons in the
diamondoid skeletons. It should be mentioned that some of the
tertiary or secondary carbons are equivalent. This means that the
derivatives substituted at those equivalent tertiary or secondary
carbons are identical.
[0097] FIG. 5 shows a flow chart for the strategy of derivatization
of diamondoids and FIG. 6 shows some representative primary
derivatives of diamondoids and the corresponding reactions. As
shown in FIG. 6, there are, in general, three major reactions for
the derivatization of diamondoids sorted by mechanism: nucleophilic
(S.sub.N1-type) and electrophilic (S.sub.E2-type) substitution
reactions, and free radical reaction (details for such reactions
and their use with adamantane are shown, for instance in, "Recent
developments in the adamantane and relatedpolycyclic hydrocarbons"
by R. C. Bingham and P. v. R. Schleryer as a chapter of the book
entitled "Chemistry of Adamantanes" (Springer-Verlag, Berlin
Heidelberg New York, 1971) and in; "Reactions of adamantanes in
electrophilic media" by I. K. Moiseev, N. V. Makarova, M. N.
Zemtsova published in Russian Chemical Review, 68(12), 1001-1020
(1999); "Cage hydrocarbons" edited by George A. Olah (John Wiley
& Son, Inc., New York, 1990).
[0098] S.sub.N1 reactions involve the generation of diamondoid
carbocations (there are several different ways to generate the
diamondoid carbocations, for instance, the carbocation is generated
from a parent diamondoid, a hydroxylated diamondoid or a
halogenated diamondoid, shown in FIG. 7), which subsequently react
with various nucleophiles. Some representative examples are shown
in FIG. 8. Such nucleophiles include, for instance, the following:
water (providing hydroxylated diamondoids); halide ions (providing
halogenated diamondoids); ammonia (providing aminated diamondoids);
azide (providing azidylated diamondoids); nitrites (the Ritter
reaction, providing aminated diamondoids after hydrolysis); carbon
monoxide (the Koch-Haaf reaction, providing carboxylated
diamondoids after hydrolysis); olefins (providing alkenylated
diamondoids after deprotonation); and aromatic reagents (providing
arylated diamondoids after deprotonation). The reaction occurs
similarly to those of open chain alkyl systems, such as t-butyl,
t-cumyl and cycloalkyl systems. Since tertiary (bridgehead) carbons
of diamondoids are considerably more reactive than secondary
carbons under S.sub.N1 reaction conditions, substitution at the
tertiary carbons is favored.
[0099] S.sub.E2-type reactions (i.e., electrophile substitution of
a C--H bond via a five-coordinate carbocation intermediate)
include, for instance, the following reactions: hydrogen-deuterium
exchange upon treatment with deuterated superacids (e.g.,
DF--SbF.sub.5 or DSO.sub.3F--SbF.sub.5); nitration upon treatment
with nitronium salts, such as NO.sub.2.sup.+ BF.sub.4.sup.- or
NO.sub.2.sup.+PF.sub.6.sup.- in the presence of superacids (e.g.,
CF.sub.3SO.sub.3H); halogenation upon, for instance, reaction with
Cl.sub.2+AgSbF.sub.6; alkylation of the bridgehead carbons under
the Friedel-Crafts conditions (i.e., S.sub.E2-type .sigma.
alkylation); carboxylation under the Koch reaction conditions; and,
oxygenation under S.sub.E2-type a hydroxylation conditions (e.g.,
hydrogen peroxide or ozone using superacid catalysis involving
H.sub.3O.sub.2.sup.+ or HO.sub.3.sup.+, respectively). Some
representative S.sub.E2-type reactions are shown in FIG. 9.
[0100] Of those S.sub.N1 and S.sub.E2 reactions, S.sub.N1-type
reactions are the most frequently used for the derivatization of
diamondoids. However, such reactions produce the derivatives mainly
substituted at the tertiary carbons. Substitution at the secondary
carbons of diamondoids is not easy in carbonium ion processes since
secondary carbons are considerably less reactive than the
bridgehead positions (tertiary carbons) in ionic processes.
However, reactions at the secondary carbons are achieved by taking
advantage of the low selectivity of free radical reactions and the
high ratios of 2.degree. (secondary) to 3.degree. (tertiary,
bridgehead) hydrogens in diamondoids. Thus, free radical reactions
provide a method for the preparation of a greater number of the
possible isomers of a given diamondoid than might be available by
ionic precesses. The complex product mixtures and/or isomers which
result, however, are generally difficult to separate. Due to the
decreased symmetry of substituted diamondoids, free radical
substitution of these substrates may give rise to very complex
product mixtures. Therefore, in most cases, practical and useful
free radical substitutions of diamondoids can use photochlorination
and/or photooxidation under special circumstances which permit a
simpler separation of the product mixture. For instance,
photochlorination is particularly useful for the synthesis of
chlorinated diamondoids at the secondary carbons and further
derivatizations at the secondary carbons because chlorinated
diamondoids at the secondary carbons are similar in reactivity to
those derivatized at the tertiary carbons.
[0101] Photooxidation is another powerful free radical reaction for
the synthesis of hydroxylated derivatives at the secondary carbons
which are further oxidized to keto derivatives, which can be
reduced to alcohols providing unique hydroxylated diamondoid
derivatives at the secondary carbons.
[0102] Considering this significant advantage of separating the
keto diamondoids, a variety of diamondoid derivatives at the
secondary carbons are prepared starting from the keto derivatives
(diamondoidones), such as by reducing the keto group by, for
instance, LiAlH.sub.4, to provide the corresponding hydroxylated
derivatives at the secondary carbons and further derivatizations at
the secondary carbons starting from those hydroxylated derivatives.
Diamondoidones can also undergo acid-catalyzed (HCl-catalyzed)
condensation reaction with, for example, excess phenol or aniline
in the presence of hydrogen chloride to form
2,2-bis(4-hydroxyphenyl) diamondoids or 2,2-bis(4-aminophenyl)
higher diamandoids substituted at the secondary carbons. With the
development of separation technology, such as by using up-to-date
HPLC technique, we may predict that more free radical reactions
might be employed for the synthesis of derivatives of
diamondoids.
[0103] Using those three major types of reactions for the
derivatization of diamondoids, a number of diamondoid derivatives
are prepared. Representative core reactions and the derivatives are
presented as following as either very important means to activate
the diamondoid nuclei or very important precursors for further
derivatizations.
[0104] FIG. 10 shows some representative pathways for the
preparation of brominated diamondoid derivatives. Mono- and
multi-brominated diamondoids are some of the most versatile
intermediates in the derivative chemistry of diamondoids. These
intermediates are used in, for example, the Koch-Haaf, the Ritter,
and the Friedel-Crafts alkylation/arylation reactions. Brominated
diamondoids are prepared by two different general routes. One
involves direct bromination of diamondoids with elemental bromine
in the presence or absence of a Lewis acid (e.g.
BBr.sub.3-AlBr.sub.3) catalyst. The other involves the substitution
reaction of hydroxylated diamondoids with hydrobromic acid.
[0105] Direct bromination of diamondoids is highly selective
resulting in substitution at the bridgehead (tertiary) carbons. By
proper choice of catalyst and conditions, one, two, three, four, or
more bromines can be introduced sequentially into the molecule, all
at bridgehead positions. Without a catalyst, the mono-bromo
derivative is the major product with minor amounts of higher
bromination products being formed. By use of suitable catalysts,
however, di-, tri-, and tetra-, penta-, and higher bromide
derivatives of diamondoids are isolated as major products in the
bromination (e.g., adding catalyst mixture of boron bromide and
aluminum bromide with different molar ratios into the bromine
reaction mixture). Typically, tetrabromo or higher bromo
derivatives are synthesized at higher temperatures in a sealed
tube.
[0106] To prepare bromo derivatives substituted at secondary
carbons, for example, the corresponding hydroxylated diamondoids at
the secondary carbons is treated under mild conditions with
hydrobromic acid. Preferably, diamondoids hydroxylated at secondary
carbons are prepared by the reduction of the corresponding keto
derivative as described above.
[0107] Bromination reactions of diamondoids are usually worked up
by pouring the reaction mixture onto ice or ice water and adding a
suitable amount of chloroform or ethyl ether or carbon
tetrachloride to the ice mixture. Excess bromine is removed by
distillation under vacuum and addition of solid sodium disulfide or
sodium hydrogen sulfide. The organic layer is separated and the
aqueous layer is extracted by chloroform or ethyl ether or carbon
tetrachloride for an additional 2-3 times. The organic layers are
then combined and washed with aqueous sodium hydrogen carbonate and
water, and finally dried.
[0108] To isolate the brominated derivatives, the solvent is
removed under vacuum. Typically, the reaction mixture is purified
by subjecting it to column chromatography on either alumina or
silica gel using standard elution conditions (e.g., eluting with
light petroleum ether, n-hexane, or cyclohexane or their mixtures
with ethyl ether). Separation by preparative gas chromatography
(GC) or high performance liquid chromatography (HPLC) is used where
normal column chromatography is difficult and/or the reaction is
performed on extremely small quantities of material.
[0109] Similarly to bromination reactions, diamondoids are
chlorinated or photochlorinated to provide a variety of mono-, di-,
tri-, or even higher chlorinated derivatives of the diamondoids.
FIG. 11 shows some representative pathways for the synthesis of
chlorinated diamondoid derivatives, especially those chlorinated
derivatives at the secondary carbons by way of
photochlorination.
[0110] FIG. 12 shows some representative pathways for the synthesis
of hydroxylated diamondoids. Direct hydroxylation is also effected
on diamondoids upon treatment with N-hydroxyphthalimide and a
binary co-catalyst in acetic acid. Hydroxylation is a very
important way of activating the diamondoid nuclei for further
derivatizations, such as the generation of diamondoid carbocations
under acidic conditions, which undergo the S.sub.N1 reaction to
provide a variety of diamondoid derivatives. In addition,
hydroxylated derivatives are very important nucleophilic agents, by
which a variety of diamondoid derivatives are produced. For
instance, the hydroxylated derivatives are esterified under
standard conditions such as reaction with an activated acid
derivative. Alkylation to prepare ethers is performed on the
hydroxylated derivatives through nucleophilic substitution on
appropriate alkyl halides.
[0111] The above described three core derivatives (hydroxylated
diamondoids and halogenated especially brominated and chlorinated
diamondoids), in addition to the parent diamondoids or substituted
diamondoids directly separated from the feedstocks as described
above, are most frequently used for further derivatizations of
diamondoids, such as hydroxylated and halogenated derivatives at
the tertiary carbons are very important precursors for the
generation of higher diamondiod carbocations, which undergo the
S.sub.N1 reaction to provide a variety of diamondoid derivatives
thanks to the tertiary nature of the bromide or chloride or alcohol
and the absence of skeletal rearrangements in the subsequent
reactions. Examples are given below.
[0112] FIG. 13 shows some representative pathways for the synthesis
of carboxylated diamondoids, such as the Koch-Haaf reaction,
starting from hydroxylated or brominated diamondoids. It should be
mentioned that for most cases, using hydroxylated precursors get
better yields than using brominated diamondoids. For instance,
carboxylated derivatives are obtained from the reaction of
hydroxylated derivatives with formic acid after hydrolysis. The
carboxylated derivatives are further esterified through activation
(e.g., conversion to acid chloride) and subsequent exposure to an
appropriate alcohol. Those esters are reduced to provide the
corresponding hydroxymethyl diamondoids (diamondoid substituted
methyl alcohols, D-CH.sub.2OH). Amide formation is also performed
through activation of the carboxylated derivative and reaction with
a suitable amine. Reduction of the diamondoid carboxamide with
reducing agents (e.g. lithium aluminum hydride) provides the
corresponding aminomethyl diamondoids (diamondoid substituted
methylamines, D-CH.sub.2NH.sub.2).
[0113] FIG. 14 shows some representative pathways for the synthesis
of acylaminated diamondoids, such as the Ritter reaction starting
from hydroxylated or brominated diamondoids. Similarly to the
Koch-Haaf reaction, using hydroxylated precursors get better yields
than using brominated diamondoids in most cases. Acylaminated
diamondoids are converted to amino derivatives after alkaline
hydrolysis. Amino diamondoids are further converted to, without
purification in most cases, amino diamondoid hydrochloride by
introducing hydrochloride gas into the aminated derivatives
solution. Amino diamondoids are some of very important precursors
in the synthesis of medicines. They are also prepared from the
reduction of nitrated compounds. FIG. 15 shows some representative
pathways for the synthesis of nitro diamondoid derivatives.
Diamondoids are nitrated by concentrated nitric acid in the
presence of glacial acetic acid under high temperature and
pressure. The nitrated diamondoids are reduced to provide the
corresponding amino derivatives. In turn, for some cases, amino
diamondoids are oxidized to the corresponding nitro derivatives if
necessary. The amino derivatives are also synthesized from the
brominated derivatives by heating them in the presence of formamide
and subsequently hydrolyzing the resultant amide.
[0114] Similarly to the hydroxylated compounds, amino higher
diamonds are acylated or alkylated. For instance, reaction of an
amino diamondoid with an activated acid derivative produces the
corresponding amide. Alkylation is typically performed by reacting
the amine with a suitable carbonyl containing compound in the
presence of a reducing agent (e.g. lithium aluminum hydride). The
amino diamondoids undergo condensation reactions with carbamates
such as appropriately substituted ethyl N-arylsulfonylcarbamates in
hot toluene to provide, for instance,
N-arylsulfonyl-N-diamondoidylureas.
[0115] FIG. 16 presents some representative pathways for the
synthesis of alkylated, alkenylated, alkynylated and arylated
diamondoids, such as the Friedel-Crafts reaction. Ethenylated
diamondoid derivatives are synthesized by reacting a brominated
diamondoid with ethylene in the presence of AlBr.sub.3 followed by
dehydrogen bromide with potassium hydroxide (or the like). The
ethenylated compound is transformed into the corresponding epoxide
under standard reaction conditions (e.g., 3-chloroperbenzoic acid).
Oxidative cleavage (e.g., ozonolysis) of the ethenylated diamondoid
affords the related aldehyde. The ethynylated diamondoid
derivatives are obtained by treating a brominated diamondoid with
vinyl bromide in the presence of AlBr.sub.3. The resultant product
is dehydrogen bromide using KOH or potassium t-butoxide to provide
the desired compound.
[0116] More reactions are illustrative of methods which can be used
to functionalize diamondoids. For instance, fluorination of a
diamondoid is carried out by reacting the diamondoid with a mixture
of poly(hydrogen fluoride) and pyridine (30% Py, 70% HF) in the
presence of nitronium tetrafluoroborate. Sulfur tetrafluoride
reacts with a diamondoid in the presence of sulfur monochloride to
afford a mixture of mono-, di-, tri- and even higher fluorinated
diamondoids. Iodo diamondoids are obtained by a substitutive
iodination of chloro, bromo or hydroxyl diamondoids.
[0117] Reaction of the brominated derivatives with hydrochloric
acid in dimethylformamide (DMF) converts the compounds to the
corresponding hydroxylated derivatives. Brominated or iodinated
diamondoids are converted to thiolated diamondoids by way of, for
instance, reacting with thioacetic acid to form diamondoid
thioacetates followed by removal of the acetate group under basic
conditions. Brominated diamondoids, e.g. D-Br, is heated under
reflux with an excess (10 fold) of hydroxyalkylamine, e.g.
HO--CH.sub.2CH.sub.2--NH.sub.2, in the presence of a base, e.g.
triethylamine, diamondoidyloxyalkylamine, e.g.
D-O--CH.sub.2CH.sub.2--NH.sub.2, is obtained. On acetylation of the
amines with acetic anhydride and pyridine, a variety of N-acetyl
derivatives are obtained. Direct substitution reaction of
brominated diamondoids, e.g. D-Br, with sodium azide in dipolar
aprotic solvents, e.g. DMF, to afford the azido diamondoids, e.g.
D-N.sub.3.
[0118] Diamondoid carboxylic acid hydrazides are prepared by
conversion of diamondoid carboxylic acid into a chloroanhydride by
thionyl chloride and condensation with isonicotinic or nicotinic
acid hydrazide (FIG. 17).
[0119] Diamondoidones or "diamondoid oxides" are synthesized by
photooxidation of diamondoids in the presence of peracetic acid
followed by treatment with a mixture of chromic acid-sulfuric acid.
Diamondoidones are reduced by, for instance, LiAlH.sub.4, to
diamondoidols hydroxylated at the secondary carbons. Diamondoidones
also undergo acid-catalyzed (HCl-catalyzed) condensation reaction
with, for example, excess phenol or aniline in the presence of
hydrogen chloride to form 2,2-bis(4-hydroxyphenyl) diamondoids or
2,2-bis(4-aminophenyl) diamondoids.
[0120] Diamondoidones (e.g. D=O) are treated with RCN(R=hydrogen,
alkyl, aryl, etc.) and reduced with LiAlH.sub.4 to give the
corresponding C-2-aminomethyl-C-2-D-OH, which are heated with
COCl.sub.2 or CSC12 in toluene to afford the following derivatives
shown in formula IV (where Z=O or S):
##STR00007##
[0121] Diamondoidones react with a suitable primary amine in an
appropriate solvent to form the corresponding imines. Hydrogenation
of the imines in ethanol using Pd/C as the catalyst at about
50.degree. C. to afford the corresponding secondary amines.
Methylation of the secondary amines following general procedures
(see, for instance, H. W. Geluk and V. G. Keiser, Organic
Synthesis, 53:8 (1973)) to give the corresponding tertiary amines.
Quaternization of the tertiary amines by, for instance, slowly
dropping CH.sub.3I (excess) into an ethanol solution of the amine
at around 35.degree. C. to form the corresponding quaternary
amines.
[0122] C-2 derivatives of diamondoids, C-2 D-R' (R'=alkyl, alkoxy,
halo, OH, Ph, COOH, CH.sub.2COOH, NHCOCH.sub.3, CF.sub.3COOH) are
prepared by nucleophilic substitution of
diamondoid-C-2-spiro-C-3-diazirine in solution at 0-80.degree. C.
in the presence of an acid catalyst.
[0123] N-sulfinyl diamondoids [D-(NSO).sub.n, n=1, 2, 3, 4, . . . ]
are prepared by refluxing the diamondoid-HCl with SOCl.sub.2 in
benzene for about half an hour to several hours afording mono-, di,
tri-, or higher N-sulfinyl diamondoid derivatives.
[0124] Treatment of D-Br and/or D-Cl with HCONH.sub.2 (wt. ratio
not >1:2) at <195.degree. C. followed by hydrolysis of the
formylamino diamondoids D-NHCHO with <20% HCl at <110.degree.
C. affords the amino diamondoid hydrochloride D-NH.sub.2HCl.
[0125] Diamondoid dicarboxamides are prepared by the reaction of
diamondoid dicarbonyl chloride or diamondoid diacetyl chloride with
aminoalkylamines. For instance, D-(COCl).sub.2 [from SOCl.sub.2 and
the corresponding dicarboxylic acid D-(COOH).sub.2] are treated
with (CH.sub.3).sub.2NCH.sub.2CH.sub.2CH.sub.2NH.sub.2 in
C.sub.5H.sub.5N--C.sub.6H.sub.6 to give
N,N'-bis(dimethylaminopropyl) diamondoid dicarboxamide.
[0126] Aminoethoxyacetylamino diamondoids are prepared from
chloroacetylamino diamondoids and HOCH.sub.2CH.sub.2NR'R''. Thus,
for instance, amino diamondoids, D-NH.sub.2, and ClCH.sub.2COCl in
benzene, is added to (CH.sub.3).sub.2NCH.sub.2CH.sub.2ONa in xylene
and refluxed for about 10 hours to give aminoethoxyacetylamino
diamondoids (R'.dbd.R''.dbd.CH.sub.3).
[0127] Ritter reaction of C-3 D-OH and HCN gives D-NH.sub.2; the
preparation of D-NHCHO from diamondoids and HCN; the reaction of
diamondoids with nitriles gives D-NHCHO and D-NH.sub.2; the
preparation of aza diamondoids from nitriles and compounds
containing unsaturated OH groups, and SH groups, and so on.
[0128] Hydroxylated diamondoids, e.g. D-OH, react with COCl.sub.2
or CSCl.sub.2 to afford the diamondoidyloxycarbonyl derivatives,
e.g. D-O--C(O)Cl or D-O--C(S)Cl the former being an important
blocking group in biochemical syntheses.
[0129] FIG. 18 shows representative reactions starting from
D-NH.sub.2 and D-CONH.sub.2 and the corresponding derivatives,
wherein D is a diamondoid nucleus.
[0130] FIG. 19 shows representative reactions starting from
D-POCl.sub.2 and the corresponding derivatives, wherein D is a
diamondoid nucleus.
[0131] FIG. 20 shows representative reactions starting from D-SH or
D-SOCl and the corresponding derivatives, wherein D is a diamondoid
nucleus.
Polymerizable Diamantyl, and Triamantyl, and Higher Diamondoid
Containing Monomers
[0132] Embodiments of the present invention specifically include
polymerizable diamantyl monomers having the formula Pg-D-(R).sub.n,
wherein D is a diamantyl nucleus; Pg is a polymerizable group
covalently bonded to a carbon of the diamantyl nucleus; n is an
integer ranging from 1 to 6, inclusive; at least one of the R's is
a hydrophilic-enhancing moiety; and each of the remaining R's is
independently selected from the group consisting of hydrogen and a
hydrophilic-enhancing moiety. The hydrophilic-enhancing moieties of
these diamantyl monomers may be selected from the group consisting
of a hydroxyl group --OH, a carboxylic group --COOH, an alkyl group
--OCH.sub.3 or --OC.sub.2H.sub.5, a keto group --C(O)--, and a
group --OC(O)OCH.sub.3 or --OC(O)--OC.sub.2H.sub.5.
[0133] Other embodiments of the present invention provide for
triamantyl monomers having polymerizable groups and
hydrophilic-enhancing moities similar to those for diamantyl
monomers discussed above, as well as diamonoid-containing monomers
with polymerizable groups and hydrophilic-enhancing moities,
wherein the diamondoid portion of the diamonoid-containing monomer
is selected from the group consisting of tetramantane,
pentamantane, hexamantane, heptamantane, octamantane, nonamantane,
decamantane, and undecamantane.
[0134] In other embodiments of the present invention, the
polymerizable groups Pg of the diamantyl, triamantyl, higher
diamondoid containing monomers are capable of forming photo-labile
polymers. The polymerizable groups may be covalently bonded to
either secondary (2.degree.) carbons or tertiary carbons
(3.degree., also called bridgehead carbons) of the diamantyl,
triamantyl, or higher diamondoid nucleus. These polymerizable
groups may comprise an unsaturated acid residue bound to the
diamantyl, triamantyl, or higher diamondoid nucleus to form an
ester, and the unsaturated acid residue may comprise an acrylate or
a lower alkyl acrylate. When the unsaturated acid residue is an
acrylic acid residue the respective monomer becomes an acrylate
monomer. Similarly, when the unsaturated acid residue is an
methacrylic acid residue the respective monomer becomes an
methacrylate monomer.
[0135] Further embodiments of the present invention provide for
methods of forming a layer of patterned photoresist on the surface
of a substrate. Such methods comprise the steps of:
[0136] a) forming a polymer from monomers selected from the group
consisting of a diamantyl monomer having a polymerizable group and
at least one hydrophilic-enhancing group; a triamantyl monomer
having a polymerizable group and at least one hydrophilic-enhancing
group; and a diamondoid-containing monomer having a polymerizable
group and at least one hydrophilic-enhancing group, the diamondoid
of the diamondoid-containing monomer selected from the group
consisting of tetramantane, pentamantane, hexamantane,
heptamantane, octamantane, nonamantane, decamantane, and
undecamantane;
[0137] b) depositing the polymer on a surface of the substrate as a
polymeric layer, the polymeric layer comprising a photo-labile
polymer; and
[0138] c) exposing selected regions of the polymerized layer to an
electromagnetic beam, thereby modifying the photo-labile polymer in
those regions exposed to the electromagnetic beam to yield a
selectively modified layer.
[0139] According to further embodiments, the method described above
may include the step of contacting the selectively modified layer
with a solvent system to solubilize the modified regions. The
electromagnetic beam may comprise radiation having a wavelength
less than about 200 nm, and exemplary wavelengths are 193 nm and
157 nm. The electromagnetic beam may also be an e-beam or an x-ray
beam.
[0140] As will be explained, one excellent application for these
monomers and polymers is as components of photoresists. In this
application the monomers and polymers can serve as components of
deposited layers. These layers are additional aspects of this
invention as are patterned layers and methods of preparing them all
of which employ the instant diamantyl and/or triamantyl monomers
and polymers.
Photoresist Base Resins
[0141] Prior art polymers that have been used in positive-acting
photoresists have been discussed by K. Nozaki and E. Yano in
"High-Performance Resist Materials for ArF Eximer Laser and
Electron Beam Lithography," Fujitsu Sci. Tech. J., 38, 1, p. 3-12
(June, 2002). These authors teach that conventionally,
polyvinylphenol-based resists were generally used in electron beam
lithography, and such resins made use of a variety of protecting
groups such as acetals, tert-butoxycarbonyl, and tert-butyl. The
disadvantages of these protecting groups included a poor dry-etch
resistance due to the aliphatic structures. To overcome this
problem, K. Nozaki and E. Yano suggested the use of acid sensitive
and dry etch resistant protective groups. These authors teach that
dry etch resistance may be imparted to the resist by incorporating
acid cleavable alicyclic substituents into the base polymer.
[0142] K. Nozaki and E. Yano reported on the use of mevalonic
lactone methacrylate (MLMA) and 2-methyl-2-adamantane methacrylate
(MAdMA) based copolymers. The adamantyl, polycyclic hydrocarbon
substituent provided superior sensitivity, resolution, and dry etch
resistance, whereas the lactone containing monomer afforded
compatibility with conventional developers such as
tetramethylammonium hydroxide (TMAH), and adhesion to silicon
substrates. The adamantane and lactone substituents were chosen
since they can function as acid labile ester groups in the
methacrylate polymer. The hydrophilic mevalonic lactone group
provided adhesion to the silicon substrate, and was acid cleavable
because it contained an acid sensitive .beta.-hydroxyketone
structure and a tertiary alcohol. The alicyclic adamantyl
substituent provided dry etch resistance, and was also acid
cleavable because of a tertiary alcohol. These authors teach that
the adamantyl groups have a stronger dissolution inhibition than,
for example, a t-butyl pendant group would have, which comes about
from its highly hydrophobic nature and bulky structure. Thus, a
large polarity change can be obtained with a small amount of
deprotection, and therefore a superior contrast between exposed and
unexposed regions of the resist may be realized, contributing to
enhance resolution.
[0143] Of particular interest is the imaging results obtained by K.
Nozaki and E. Yano. A series of five methacrylate polymers were
prepared, wherein the ratios of the monomers MLMA/MAdMA ranged from
0/100, 22/78, 51/49, 72/28, and 100/0, respectively. The polymers
prepared from the latter two monomer ratios could not be imaged
because they were alkali soluble, and it was not possible to
resolve any resist patterns. Furthermore, the polymer prepared from
the 100/0 ratio was difficult to spin-coat because the photo-acid
generator separated out from the resist composition. The polymers
prepared from the first two monomer ratios likewise did not image
well (or could not be imaged) because the formulated resist
patterns peeled off the silicon substrates, suggesting that the
rigid adamantyl units imparted a brittleness to the resist. The
photoresist composition containing roughly equal amounts of the two
monomers was thought to be a promising compromise, and based on
their observations, the optimum composition for the base polymer
was about MAdMA/MLMA=1/1.
[0144] The photoresist compositions of the present embodiments
include acid-cleavable diamondoid blocking groups higher in the
homologous series than adamantane. The advantages of including such
diamondoids is that an enhanced etch resistance may be imparted to
the base resin, thereby improving the resolution of the resist, but
the choice of diamondoid higher than adamantane, the amounts in
which it is used, and the number of hydrophilic-enhancing groups
with which it is derivatized, comprise a part of the subject matter
of the present disclosure.
Co-Polymer Base Resins with Diamondoids Higher than Adamantane
[0145] According to embodiments of the present invention, the base
resin of a positive-acting photoresist may be represented by the
general formula illustrated in FIGS. 21A-C. The positive-working
photoresist composition shown in FIG. 21A comprises a polymeric
backbone chain 210, which may include pendant groups 212. The
pendant groups 212 may be a non-diamondoid pendant group
represented by P.sub.1, or the pendant groups may be
diamondoid-containing such as the adamantane based pendant group
214 or the diamantane based pendant group 216. In this example, the
pendant groups 212 are connected to the main backbone chain 210
through ester groups 218, which is the linkage that imparts the
acid-cleavable character to the base resin shown in FIG. 21A. Also
depicted in FIG. 21A are alkyl groups R.sub.2 that yield a tertiary
alcohol when the blocking groups 214 and 216 are cleaved, as well
as hydrophilic-enhancing groups R.sub.3.
[0146] Specifically, in this exemplary base resin, R.sub.1 may be
either --H or --CH.sub.3, such that the polymeric backbone chain
210 constitutes either an acrylate type polymer, or a methacrylate
type polymer, respectively. R.sub.2 in this example may be either
--H, in which case the diamondoid-containing monomer is not acid
cleavable, or an alkyl (such as --CH.sub.3) group having from 1 to
4 carbon atoms. In the latter case the diamondoid-containing
pendant group is acid cleavable because the capability of forming a
carbon-carbon double bond exists. The dissolution ability of the
pendant group (i.e., the ability of the pendant group to dissolve
in an alkali developer) is enhanced by the fact that a tertiary
alcohol is formed when R.sub.2 is an alkyl group or an alkoxy
group. R.sub.3 is either --H, or a hydrophilic-enhancing moiety
that may be either a hydroxyl group --OH, a carboxylic group
--COOH, an alkyl group --OR.sub.4, a keto group --C(O)--, or
--OC(O)--OR.sub.4. It will be apparent to those skilled in the art
that --OR.sub.4 represents the situation when an alcohol group --OH
is protected, wherein the protection may be in the form of an alkyl
group or an acetate group.
[0147] One feature of the present embodiments that contribute to
their novelty is the fact that, unlike the base polymers taught by
K. Nozaki and E. Yano, a monomer having a diamondoid pendant group
higher than adamantane is included in the base resin. This
exemplary monomer that contains a pendant group higher than
adamantane is shown in FIG. 21A as diamantane. The advantages of
including monomers with diamondoid-containing pendant groups higher
than adamantane is that since because there are more carbons
present in the sp.sup.3-hybridized, diamond cubic crystal
structure, the blocking group is more resistant to the etching
process, and thus, the exposed and unexposed regions of the resist
are more delineated. This feature enhances resolution. Furthermore,
because the etch resistance has been improved, it may be possible
to incorporate less of the diamantane containing monomer into the
base resin, improving the ability of the resist to adhere to the
substrate.
[0148] According to embodiments of the present invention, the
ratios of the feed monomers for the exemplary base resin depicted
in FIG. 21A may be represented by the relationships: [0149] a is
0.25 to 0.75; [0150] b+c=1-a; and [0151] c is greater than zero,
where a, b, and c represent the relative amounts of the
non-diamondoid containing monomer, the adamantane-containing
monomer, and the diamantane-containing monomer, respectively. It
will be understood by those skilled in the art that the formula
shown in FIG. 21A is schematic only, and that the repeat units
represented in quantities a, b, and c may appear in virtually any
order in the polymer chain. In other words, the repeat units do not
have to follow the pattern a, b, c, a, b, c, and may instead take
the form a, a, b, a, c, a, b, b, a, b, c, a, c, b, etc.
[0152] A consequence of including monomers with
diamondoid-containing pendant groups higher than adamantane is that
the pendant group will be more hydrophobic, and thus it will be
more difficult to dissolve the blocking group in the alkali
developer. This issue may be addressed, however, by derivatizing
the diamantane or higher pendant group with a larger number of
hydrophilic-enhancing groups, such as the --OH group R.sub.3. The
number of these that are required is also the subject matter of the
present disclosure.
[0153] The diamondoid-containing monomer having a pendant group
higher than adamantane is not limited to diamantane, and may in
fact comprise triamantane 220, and diamondoids 222 that are even
higher than triamantane in the polymantane hydrocarbon series. This
is illustrated in FIG. 21B. The term "diamondoid" in FIG. 21B is
meant to represent any of the diamondoids tetramantane,
pentamantane, hexamantane, heptamantane, octamantane, nonamantane,
decamantane, and undecamantane. Again, the order of the repeat
units in the chain is not limited to that shown in FIG. 21B, as
this is just a schematic drawing of an exemplary polymer. If the
polymer contains either or both diamantane and triamantane, and
even diamondoids, the amounts of these repeat units (which may be
the same thing as saying the relative amounts of the monomers in
the feed, depending on the reactivity of the monomers during the
polymerization process), may be represented by c, d, and e,
respectively.
[0154] In the exemplary polymer of FIG. 21A, P.sub.1 is a
non-diamondoid, acid-cleavable pendant group that may be
represented by the structures shown in FIGS. 21C-D. The value of
"n" may be either 0 or 1. If n=0, then the non-diamondoid pendant
group shown in FIG. 21C comprises a five-membered heterocyclic ring
with no R.sub.6 or R.sub.7 substituents on the ring. If n=1, then
the non-diamondoid pendant group shown in FIG. 21C comprises a
five-membered heterocyclic ring with substituents R.sub.6 or
R.sub.7 on the alpha carbon relative to where the ring attaches to
the main polymeric backbone. Again, the linkage in this exemplary
polymer is an ester linkage, making the polymer an acrylate or
methacrylate, but many other types of linkages are possible.
[0155] A six-membered heterocyclic ring for the non-diamondoid,
acid-cleavable pendant group P.sub.1 is shown in FIG. 21D. In this
case, again exemplary, the substituents R.sub.6 or R.sub.7 are
always present on the alpha carbon.
[0156] It will be understood by those skilled in the art that the
nomenclature used in FIGS. 21A-B is meant to represent that there
are multiple attachment sites for the exemplary substituent groups
R.sub.2 and R.sub.3 onto the carbon framework of the pendant
diamondoid group. An example of this concept is illustrated
schematically in FIGS. 22A-E. An exemplary diamondoid pendant group
tetramantane is shown at 224 in FIG. 22A. The tetramantane pendant
group 224 is attached to the main polymer chain by ester linkage
226, as before. The tetramantane molecule is shown as containing
substituents R.sub.2, R.sub.3, R.sub.4, and R.sub.5, and the
nomenclature in FIG. 22A is meant to indicate that these
substituents may be attached at a number of possible sites to the
tetramantane carbon framework (secondary and tertiary carbons shown
in FIGS. 22B-E). It will become apparent to the reader that one of
the advantages of including diamondoid-containing pendant groups
higher than adamantane are the vast number of possible attachment
sites for hydrophilic-enhancing groups, alkyl groups, and
polymerizable groups.
Etch Resistance
[0157] The inclusion of diamondoid-containing monomers higher than
adamantane is contemplated to have the advantageous result of
imparting enhanced etch resistance to the polymer. As discussed in
a reference titled "Lithographic Resists," by W. D. Hinsberg et al.
(IBM Research Division, K-Othmer, Encyclopedia of Chemical
Technology), a paramater was devised by Ohnishi et al. to correlate
a photoresist's chemical composition with its ability to withstand
an etching environment. The parameter is given by
N/(N.sub.c-N.sub.o), where N is the total number of atoms in the
polymer repeat unit, including hydrogen atoms, N.sub.c is the
number of carbon atoms, and N.sub.o is the number of oxygen
atoms.
[0158] The model serves as a fair predictor of etch rates for
polymers under conditions where physical ion bombardment is a
significant component, as is the case for reactive ion etching. The
relation fails for low ion energy plasma conditions, such as those
that what occurred in a downstream glow discharge process, where
etching mechanisms are primarily chemical in nature. The Ohnishi
parameter predicts that polymers having a high content of carbon
(e.g., a low Ohnishi number) will exhibit low etch rates. In
contrast, incorporation of hydrogen and/or oxygen into the repeat
unit structure increases the etch rate, while an increased carbon
content reduces the etch rate.
[0159] The Ohnishi numbers for exemplary monomers of the present
invention, with adamantane for comparison, are shown with their
respective schematic drawings in FIG. 23A. Referring to FIG. 23A,
an adamantane-containing repeat unit has an Ohnishi number of 3.00,
while this number decreases for diamantane, triamantane, and
tetramane as follows: 2.75, 2.60, and 2.50. As taught by the
present disclosure, however, it is necessary to include
hydrophilic-enhancing groups as substituents on the diamondoid
pendant groups, and the number of these hydrophilic-enhancing
groups that are required will increase as the size of the
diamondoid increases.
[0160] It is a surprising result just how many of these
hydrophilic-enhancing groups may be tolerated with respect to etch
resistance. For example, FIG. 23B calculates the Ohnishi number for
the same series adamantane, diamantane, triamantane, and
tetramantane, only an additional hydroxyl group is added as a
substituent each time the size of the diamondoid is increased. Even
with this additional "burden" on the etch resistance of the resist,
the Ohnishi number still decreases for the series adamantane with
one hydroxyl substitutent, diamantane with two hydroxyl
substituents, triamantane with three hydroxyl substituents, and
tetramantane with four hydroxyl substituents (3.36, 3.29, 3.24, and
3.20, respectively).
Multiple Acid-Labile Sites
[0161] Embodiments of the present invention include the ability of
the diamondoid containing pendant group to be cleaved at multiple
sites in the link connecting the pendant group to the main polymer
chain. This is illustrated schematically in FIGS. 24A-D. Referring
to FIG. 24A, a polymerizable group 230, which along with methyl
group 232 and ester group 234 defines this exemplary polymer as a
methacrylate, is attached through a second ester leakage 236 to
diamondoid 238. The diamondoid 238 has an alkyl substituent 240
attached to the same carbon atom as the ester linkage 236. For
exemplary purposes, a hydroxyl substituent 242 is shown attached to
diamondoid 238, which in this case is a diamantane molecule.
[0162] The purpose of multiple ester linkages 234 and 236 is to
provide a multiplicity of locations for the acid generated from the
exposure event to cleave pendant diamondoid 238 from the main
polymer chain (not shown). The advantages of providing multiple
acid cleaving sites is at least twofold: 1) a weaker acid may be
used to cleave the diamondoid pendant groups, allowing at the same
time for a decreased post exposure bake temperature relative to
what otherwise might have been necessary, and 2) a potentially
larger variety of photo-acid generators become available. The
ability to lower the post exposure bake temperature, to 110.degree.
C. or less, for example, is highly desirable in the industry
because of uniformity considerations. Multiple acid-cleaving sites
are contemplated to be effective for the purposes cited above
because the acid-cleaving process is a diffusion driven one, and
having more sites available means that the acid molecule does not
have to diffuse as far.
[0163] Three more examples of diamondoid-containing monomers with
multiple acid-labile sites are shown in FIGS. 24B, C, and D,
wherein the diamondoid in FIG. 24B is a triamantane with a hydroxyl
and methyl substituents, and the linking group 244 contains three
ester linkages; the tetramantane in FIG. 24C has acetate and a
carboxylic acid substituent groups (and two ester linkages), and
the triamantane in FIG. 24D has two hydroxyl substituents (and
three ester linkages).
Lactone-Containing Diamondoid Pendant Groups
[0164] The adhesion enhancing lactone group need not be restricted
to the non-diamondoid containing pendant group P1 of FIGS. 21A-B.
An exemplary polymer containing lactone groups in both the
non-diamondoid and the diamondoid-containing pendant groups is
shown in FIGS. 25A-B.
Fully Formulated Resists
[0165] The photoresist composition may further include a solvent
such as ethylene dichloride, cyclohexanone, cyclopentanone,
2-heptanone, .gamma.-butyrolactone, methyl ethyl ketone, ethylene
glycol monomethyl ether, ethylene glycol monoethyl ether,
2-methoxyethyl acetate, ethylene glycol monoethyl ether acetate,
propylene glycol monomethyl ether (PGME), propylene glycol
monomethyl ether acetate (PGMEA), ethylene carbonate, toluene,
ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, methyl
methoxypropionate, ethyl ethoxypropionate, methyl
methoxypropionate, ethyl pyruvate, propyl pyruvate,
N,N-dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, and
tetrahydrofuran.
[0166] The photoresist compositions of the present embodiments may
be developed in an aqueous alkaline solution such as sodium
hydroxide, potassium hydroxide, sodium carbonate, sodium silicate,
sodium metasilicate, aqueous ammonia, a primary amind, ethylamine,
n-propylamine, a secondary amine, diethylamine, di-n-butylamine, a
tertiary amine, triethylamine, methyldiethylamine, an alcohol
amine, dimethylethanolamine, triethanolamine, a quaternary ammonium
salt, tetramethylammonium hydroxide, tetraethylammonium hydroxide,
a cyclic amine, pyrrole, and piperidine.
[0167] The photoresist compositions of the present invention
further include a photoacid generator selected from the group
consisting of an onium salt, a diazonium salt, an ammonium salt, a
phosphonium salt, an iodonium salt, a sulfonium salt, a selenonium
salt, an arsonium salt, an organic halogeno compound, and an
organo-metal/organic halide compound. The photoacid generator may
have an o-nitorbenzyl type protecting group, and it may generate a
sulfonic acid upon photolysis. Furthermore, the photoresist
composition may contain the photo-acid generator in an amount
ranging from about 0.01 to 30 weight percent.
[0168] The photoresist composition of the present embodiments may
further include an additive selected from the group consisting of a
surface active agent, an organic basic compound, an acid
decomposable dissolution inhibiting compound, a dye, a plasticizer,
a photosensitizer, and a compound promoting solubility in a
developing solution, as well as diamondoid derivatives as an
additive.
EXAMPLES
[0169] The present invention will be described in detail below in
terms of example; however, the present invention is not limited in
any way to these examples. The reaction mixture and the products
were analyzed and characterized by gas chromatography/mass
spectrometry (GC/MS) to confirm the presence of target compounds
formed and the purity of the products separated. The GC/MS systems
used is an HP 5890 Series II Chromatography connected to an HP 5973
Series MSD (mass selective detector).
Example 1
[0170] 47.1 g of diamantane was dissolved in 375 ml of acetic acid,
then 4.1 g of N-hydroxyphthalimide (NHPI), 0.322 g of
Co(acac).sub.2 (cobalt (II) acetylacetonate) were added into the
mixture. The mixture was stirred for about 23 hours at around
75.degree. C. in a bubbling oxygen atmosphere. During the reaction,
an additional portion of NHPI and Co(acac).sub.2 were added. After
cooling down to room temperature (20.degree. C.) and filtrating off
the precipitated unreacted diamantane, the orange colored reaction
mixture was concentrated under vacuum to give a dark red oily
liquid. The dark red oily liquid was dissolved in methylene
chloride. The methylene chloride solution of the reaction mixture
was first extracted with water for several times. The combined
water layers were then extracted with methylene chloride for a few
times and finally the combined organic layers were concentrated and
subjected to silica gel column chromatography, thus producing
di-hydroxylated diamantane with yields of about 30%. The conversion
rate of the diamantane was about 64%.
Example 2
[0171] A mixture of 9.42 g of diamantane, 0.82 g of
N-hydroxyphthalimide (NHPI), 0.064 g of Co(acac).sub.2 (cobalt (II)
acetylacetonate) and 75 ml of acetic acid was stirred for about 23
hours at around 75.degree. C. in an oxygen bubbling atmosphere.
During the reaction, an additional portion of NHPI and
Co(acac).sub.2 were added. After cooling down to room temperature
(20.degree. C.), the reaction mixture was then concentrated and
subjected to silica gel column chromatography, thus producing di-
and tri-hydroxylated diamantane with yields of about 30% and 20%
respectively.
Example 3
[0172] A mixture of 18.84 g of diamantane, 1.64 g of
N-hydroxyphthalimide (NHPI), 0.129 g of Co(acac).sub.2 (cobalt (II)
acetylacetonate) and 75 ml of acetic acid was stirred for about 23
hours at around 75.degree. C. in a bubbling oxygen atmosphere.
During the reaction, an additional portion of NHPI and
Co(acac).sub.2 were added. The reaction mixture was concentrated
and the concentrated reaction mixture was dissolved in methylene
chloride. The methylene chloride solution of the reaction mixture
was first extracted with water for several times. The combined
water layers were then extracted with methylene chloride for a few
times and finally the water was evaporated and the residual was
subjected to flash silica gel column chromatography, thus producing
tri-hydroxylated diamantine with yields of about 20%.
Example 4
[0173] 12.4 g of the crude red oily liquid from water extractions
in Example 1 mainly containing tri-hydroxylated diamantine was
dissolved in about 200 mL ethyl alcohol. 27 g of activated carbon
(60-100 mesh) was added into the ethyl alcohol solution. The
mixture was then stirred for about 3.5 hours at room temperature
(20 C). After filtration, the colorless solution was concentrated
to give a colorless oily liquid.
Example 5
[0174] 600 mL of combined methylene chloride extractions in Example
1 were added 6 g of activated carbon. The mixture was stirred for
about 20 hours at room temperature (20.degree. C.). After
filtration, a pale yellow solution was obtained and the solvent
evaporated to give a pale yellow solids. The crude solids were
subjected to silica gel column chromatography, thus producing a
colorless solid of di-hydroxylated diamantine.
Example 6
[0175] 5 g of colorful oily liquid from the water extractions in
Example 3 was dissolved in 70 mL of ethyl alcohol. Then 10 g of
activated carbon was added and the mixture was stirred for about
3.5 hours at room temperature (20.degree. C.). After filtration,
the colorless solution was concentrated to an almost colorless oily
liquid. The liquid was then dissolved in 2:1 v/v methylene chloride
and THF (tetrahydrofuran). The solution was passed on a flash short
silica gel column eluting first with 2:1 v/v methylene chloride and
THF followed by THF and ethyl alcohol (5:1 v/v). The second
fraction was concentrated to give a colorless oily liquid of
tri-hydroxylated diamantane. The first fraction was concentrated to
mainly give a white solid of di-hydroxylated diamantane.
Example 7
[0176] A portion of the dark red oily liquid in Example 1 was added
a large excess amount of methylene chloride to precipitate a solid.
After filtration and decoloring by activated carbon as above, the
solids were analysized by GC/MS to show the presence of
tetra-hydroxylated diamantane.
Example 8
[0177] Methacryloyl chloride was added dropwise to a stirred
solution of an equimolar amount of di-hydroxylaed diamantine,
excess triethylamine, and methylene chloride in a dry nitrogen
atmosphere at around -30 to 0.degree. C. Then the resulting mixture
was further stirred for several hours while maintaining the
temperature. The resultant mixture was filtrated, and the filtrate
was concentrated under vacuum. The concentrated mixture was washed
with water and brine. The water layers were combined and extracted
with methylene chloride. The organic layers were combined and dried
over anhydrous Na.sub.2SO.sub.4 and concentrated in vacuum.
Finally, the concentrate was subjected to silica gel column
chromatography, thus producing mono-hydroxyl diamantane
methacrylate (yield: 5%). The conversion rate of the
di-hydroxylated diamantane was about 10%.
Example 9
[0178] 0.4 g of mono-hydroxylated diamantine was dissolved in 50 mL
of methylene chloride. Methacryloyl chloride (0.2 mL) and
triethylamine (0.5 mL) were added to the solution at room
temperature (20.degree. C.) under dry nitrogen atmosphere. The
mixture was stirred at room temperature (20.degree. C.) under dry
nitrogen atmosphere for about 2 hours. Then the mixture was cooled
down to 0.degree. C. and another amount of methacryloyl chloride
(0.15 mL) and 50 mg 4-DMAP (4-dimethylaminopyridine) in 5 mL cold
methylene chloride were added into the mixture. The mixture was
stirred at 0.degree. C. for 30 minutes and then the cooling bath
was removed. The mixture was again stirred at room temperature
(20.degree. C.) for 3 days. GC-MS of the reaction mixture showed
the formation of diamantane methacrylate.
Example 10
[0179] To a 50 mL of methylene chloride were added the
di-hydroxylated diamantane (5.73 mmol) and methacrylic acid (1.1
molar equ.). The mixture was stirred for 15 minutes at 0.degree. C.
under dry nitrogen. Dicyclohexyl carbodiimide (DCC, 2.1 molar equ.)
and 4-DMAP (0.3 molar equ.) in about 25 mL cold methylene chloride
were added, and the mixture was then stirred for 30 minutes at
0.degree. C. under dry nitrogen. The cooling bath was then removed
and the solution allowed to warm to room temperature (about 20 C).
After being stirred for 50 hours under nitrogen, the reaction
mixture was filtered through a fine glass frit to yield a clear
filtrate and the insoluble urea byproduct as a fine white-grey
solid. The clear filtrate was washed with water (3.times.50 mL), 5%
acetic acid aqueous solution (3.times.20 mL), and finally again
with water (3.times.30 mL). The organic layer was separated, dried
over anhydrous Na.sub.2SO.sub.4, filtered, and the solvent
evaporated. The residual was subjected to column chromatography to
give mono-hydroxyl diamantane methacrylate (yield: 50%). The
conversion rate of the di-hydroxylated diamantane was about
60%.
Example 11
[0180] 5.8 mmol of di-hydroxylated diamantane, 6.4 mmol of
triethylamine and 75 mL of methylene chloride were placed in a
three necked round-bottom flask. A mixed solution of 5.5 mmol of
methacryloyl chloride and 5 mL methylene chloride was added
dropwise over a period of 5 minutes under stirring with the
reaction temperature maintained at 0.degree. C., and the mixture
was future stirred for 3 hours at 0.degree. C. under nitrogen. The
cooling bath was then removed and the mixture was stirred at room
temperature (20.degree. C.) for 23 hours. At last the temperature
was increased to about 30.degree. C. and the mixture was stirred at
the increased temperature for 2 more hours while adding 0.25 mL of
the acid chloride and 0.5 mL of triethylamine. An extraction was
performed by adding water to the reaction mixture, and the organic
layer was separated, washed with water and brine. The water layer
was extracted with methylene chloride. The organic layers were
combined, dried with anhydrous Na.sub.2SO.sub.4 and concentrated in
vacuum. The concentrate was subjected to silica gel column
chromatography, thus producing mono-hydroxyl diamantane
methacrylate (yield: 40%). The conversion rate of the
di-hydroxylated diamantane was about 60%.
[0181] Many modifications of the exemplary embodiments of the
invention disclosed above will readily occur to those skilled in
the art. Accordingly, the invention is to be construed as including
all structure and methods that fall within the scope of the
appended claims.
* * * * *