U.S. patent application number 14/687834 was filed with the patent office on 2016-10-20 for additives for orientation control of block copolymers.
The applicant listed for this patent is International Business Machines Corporation. Invention is credited to Joy Cheng, Anindarupa Chunder, Daniel P. Sanders, Melia Tjio, Ankit Vora.
Application Number | 20160304740 14/687834 |
Document ID | / |
Family ID | 56995337 |
Filed Date | 2016-10-20 |
United States Patent
Application |
20160304740 |
Kind Code |
A1 |
Cheng; Joy ; et al. |
October 20, 2016 |
ADDITIVES FOR ORIENTATION CONTROL OF BLOCK COPOLYMERS
Abstract
A film layer comprising a high-chi (.chi.) block copolymer for
self-assembly and a surface active polymer (SAP) was prepared on a
substrate surface that was neutral wetting to the domains of the
self-assembled block copolymer. The block copolymer comprises at
least one polycarbonate block and at least one other block (e.g., a
styrene-based block). The SAP comprises a hydrophobic fluorinated
first repeat unit and a non-fluorinated second repeat unit bearing
at least one pendent OH group present as an alcohol or acid (e.g.,
carboxylic acid). The film layer, whose top surface has contact
with an atmosphere, self-assembles to form a lamellar or
cylindrical domain pattern having perpendicular orientation with
respect to the underlying surface. Other morphologies (e.g.,
islands and holes of height 1.0Lo) were obtained with films lacking
the SAP. The SAP is preferentially miscible with, and lowers the
surface energy of, the domain comprising the polycarbonate
block.
Inventors: |
Cheng; Joy; (Taipei City,
TW) ; Chunder; Anindarupa; (San Jose, CA) ;
Sanders; Daniel P.; (San Jose, CA) ; Tjio; Melia;
(San Jose, CA) ; Vora; Ankit; (San Jose,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
International Business Machines Corporation |
Armonk |
NY |
US |
|
|
Family ID: |
56995337 |
Appl. No.: |
14/687834 |
Filed: |
April 15, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08F 12/22 20130101;
C08F 212/08 20130101; C08F 212/08 20130101; C08F 220/04 20130101;
C08F 212/14 20130101; C09D 125/08 20130101; C08F 212/08 20130101;
G03F 7/0002 20130101; H01L 21/0271 20130101; C09D 133/16 20130101;
C09D 169/00 20130101; C09D 125/18 20130101; C08F 212/14 20130101;
B81C 2201/0149 20130101; C08F 2438/01 20130101; B81C 1/00523
20130101; C08G 64/18 20130101; C09D 127/12 20130101; C08F 220/24
20130101; C08L 69/00 20130101; C08F 220/68 20130101; C08F 220/283
20200201; C08F 220/281 20200201; C08F 220/14 20130101; C08F 220/325
20200201; C08F 212/14 20130101; C08F 212/14 20130101; C08F 220/325
20200201; C08F 12/20 20130101; C08G 64/183 20130101; C08F 212/08
20130101; C08L 25/08 20130101 |
International
Class: |
C09D 169/00 20060101
C09D169/00; H01L 21/02 20060101 H01L021/02; H01L 21/308 20060101
H01L021/308; C08F 220/22 20060101 C08F220/22; H01L 21/3105 20060101
H01L021/3105 |
Claims
1. A composition, comprising: i) a solvent; ii) a block copolymer
comprising: a) a first block comprising a repeat unit of formula
(B-1): ##STR00088## wherein I) R.sup.w is a monovalent radical
selected from the group consisting of H, methyl, ethyl, and
trifluoromethyl (*--CF.sub.3) and II) R.sup.d is a monovalent
radical comprising an aromatic ring linked to carbon 1, and b) an
aliphatic polycarbonate second block (polycarbonate block) linked
to the first block; and iii) a surface active polymer (SAP),
comprising: about 40 mol % to about 90 mol %, based on total moles
of monomers used to prepare the SAP, of a fluorinated repeat unit
(first repeat unit), wherein the first repeat unit has a chemical
structure having no functionality capable of donating a hydrogen to
form a hydrogen bond, about 10 mol % to about 60 mol %, based on
total moles of monomers used to prepare the SAP, of a
non-fluorinated second repeat unit comprising a functional group
selected from the group consisting of alcohols, carboxylic acids,
phosphonic acids, and sulfonic acids; wherein the block copolymer
and the SAP are dissolved in the solvent.
2. The composition of claim 1, wherein the composition is suitable
for forming a layer for self-assembly (SA layer) disposed on an
underlayer of a substrate, wherein the SA layer comprises the block
copolymer and the SAP in non-covalent association, the SA layer has
a top surface in contact with an atmosphere, the underlayer is
neutral wetting to the block copolymer, the block copolymer of the
SA layer is capable of self-assembly to form a phase separated
domain pattern having a characteristic pitch Lo, the domain pattern
comprises alternating domains comprising respective chemically
distinct blocks of the block copolymer, each of the domains has
contact with the underlayer and the atmosphere, and a domain
comprising the polycarbonate block (polycarbonate domain) has a
higher concentration of the SAP compared to a domain comprising the
first block of the block copolymer.
3. The composition of claim 2, wherein the polycarbonate domain has
lower surface energy compared to an otherwise identical
polycarbonate domain lacking the SAP.
4. The composition of claim 2, wherein the domain pattern comprises
lamellar domains, and each of the lamellar domains has a
perpendicular orientation to the underlayer.
5. The composition of claim 2, wherein the domain pattern comprises
cylindrical domains, and each of the cylindrical domains has a
central axis oriented perpendicular to the underlayer.
6. The composition of claim 1, wherein the SAP is a random
copolymer.
7. The composition of claim 1, wherein the first repeat unit of the
SAP is selected from the group consisting of ##STR00089## and
combinations thereof, wherein each R' is independently selected
from the group consisting of *--H, *-Me, *-Et, and *--CF.sub.3, and
each n' is an independent integer having a value of 1 to 12.
8. The composition of claim 1, wherein the second repeat unit is
selected from the group consisting of: ##STR00090## and
combinations thereof, wherein each R'' is independently selected
from the group consisting of *--H, *-Me, *-Et.
9. The composition of claim 1, wherein the polycarbonate block of
the block copolymer comprises a trimethylene carbonate repeat unit
of structure: ##STR00091##
10. The composition of claim 9, wherein the polycarbonate block of
the block copolymer is a homopolymer of the trimethylene carbonate
repeat unit.
11. The composition of claim 1, wherein the polycarbonate block of
the block copolymer comprises an ester bearing carbonate repeat
unit formula (B-3): ##STR00092## wherein R.sup.g is a monovalent
hydrocarbon group comprising 1-20 carbons.
12. The composition of claim 11, wherein R.sup.g is selected from
the group consisting of methyl, ethyl, propyl, and benzyl.
13. The composition of claim 11, wherein the polycarbonate block of
the block copolymer is a homopolymer of the ester bearing carbonate
repeat unit.
14. The composition of claim 1, wherein the first block of the
block copolymer comprises repeat units of structure:
##STR00093##
15. The composition of claim 1, wherein the first block of the
block copolymer is poly(styrene) (PS) and the second block of the
block copolymer is poly(trimethylene carbonate) (PTMC).
16. The composition of claim 1, wherein the block copolymer is a
triblock copolymer.
17. The composition of claim 15, wherein the triblock copolymer
comprises a divalent central poly(styrene) (PS) block linked at
each end to two poly(trimethylene carbonate) (PTMC) blocks.
18. The composition of claim 1, wherein the composition comprises
the SAP in an amount of more than 0 wt %, and up to about 10 wt %
based on a total dry solids weight of the composition.
19. The composition of claim 1, wherein the composition comprises
the SAP in an amount of 0.1 wt % to about 5 wt % based on total dry
solids of the composition.
20. A method, comprising: providing a first layered structure
comprising a top layer (underlayer); disposing the composition of
claim 1 on the underlayer and removing any solvent, thereby forming
a second layered structure comprising a film layer disposed on the
underlayer, wherein the film layer comprises the block copolymer
and the SAP in non-covalent association, and the film layer has a
top surface in contact with an atmosphere; and allowing or inducing
the block copolymer of the film layer to self-assemble, thereby
forming a third layered structure comprising a phase separated
domain pattern having a characteristic pitch Lo, the domain pattern
comprising alternating domains comprising respective chemically
distinct blocks of the block copolymer; wherein each of the domains
has contact with the underlayer and the atmosphere, and a domain
comprising the polycarbonate block has a higher concentration of
the SAP compared to a domain comprising the first block of the
block copolymer.
21. The method of claim 20, comprising selectively etching one of
the domains, thereby forming a fourth layered structure comprising
an etched domain pattern comprising one or more remaining
domains.
22. The method of claim 20, wherein the underlayer is neutral
wetting to the domains of the self-assembled block copolymer.
23. The method of claim 20, comprising transferring the etched
domain pattern to the substrate using a wet and/or dry etch
process.
24. The composition of claim 20, wherein the domain pattern is a
lamellar domain pattern, and lamellae of each of the domains are
oriented perpendicular to a main plane of the underlayer.
25. The method of claim 20, wherein the domain pattern is a
cylindrical domain pattern comprising cylindrical domains having a
central axis oriented perpendicular to a main plane of the
underlayer.
26. The method of claim 20, wherein the underlayer comprises a
poly(styrene-r-methyl methacrylate) random copolymer.
27. The method of claim 20, wherein the underlayer comprises a
random copolymer comprising: a first repeat of structure:
##STR00094## and a second repeat unit of structure ##STR00095##
28. The method of claim 20, wherein the underlayer comprises a
random copolymer comprising: a first repeat of structure:
##STR00096## and a second repeat unit of structure ##STR00097##
wherein a' has a value greater than or equal to 1.
29. The method of claim 20, comprising baking the film layer at a
temperature of about 80.degree. C. to about 220.degree. C. for a
period of time, thereby inducing the block copolymer to
self-assemble.
30. The method of claim 20, wherein a domain comprising the first
block of the block copolymer has a top surface in contact with the
atmosphere and the top surface is essentially free of the SAP.
31. The method of claim 20, wherein the method comprises forming a
topographic resist pattern disposed on the underlayer before said
disposing the composition of claim 1, wherein the film layer
comprising the block copolymer for self-assembly is substantially
confined to recessed regions of the topographic resist pattern.
32. A method, comprising: providing a first layered structure
comprising a top layer (underlayer); forming a topographical resist
pattern disposed on the underlayer, the resist pattern comprising
features having recessed regions, the recessed regions having a
bottom surface which is a portion of a surface of the underlayer;
disposing the composition of claim 1 substantially in the recessed
regions of the resist pattern and removing any solvent, thereby
forming a second layered structure comprising a film layer, the
film layer comprising the block copolymer and the SAP, wherein the
film layer is in contact with the bottom surface, the bottom
surface is neutral wetting to the block copolymer, and the film
layer has a top surface in contact with an atmosphere; and allowing
or inducing the block copolymer to self-assemble, thereby forming a
third layered structure comprising a pattern of phase separated
domains (domain pattern) of the block copolymer in the recessed
regions, wherein each of the domains is in contact with the bottom
surface and the atmosphere, and each of domains is oriented
perpendicular to a main plane of the underlayer.
33. The method of claim 32, comprising selectively removing the
resist pattern and/or one of the domains, thereby forming a fourth
layered structure comprising an etched domain pattern, the etched
domain pattern comprising one or more remaining domains.
34. The method of claim 32, wherein the resist pattern is formed
using a negative tone resist.
35. A surface active polymer (SAP) of formula (H-5): E'-P'-E''
(H-5), wherein E' is a first end group, E'' is a second end group,
and P' is a polymer chain consisting essentially of: i) first
repeat units selected from the group consisting of: ##STR00098##
and combinations thereof, wherein each R' is independently selected
from the group consisting of hydrogen (*--H), methyl (*-Me), ethyl
(*-Et), and trifluormethyl (*--CF.sub.3), and each n' is an
independent integer having a value of 1 to 12, and ii) second
repeat units selected from the group consisting of ##STR00099## and
combinations thereof, wherein each R'' is independently selected
from the group consisting of *--H, *-Me, *-Et.
36. The SAP of claim 35, wherein the first repeat unit is
##STR00100##
37. The SAP of claim 35, wherein the first repeat unit is
##STR00101##
38. The SAP of claim 35, wherein E' and/or E'' comprises 1 to 25
fluorine atoms.
39. The SAP of claim 35, wherein E' and/or E'' comprises a
fluorinated ester group having the structure ##STR00102## wherein
n' is an integer of 1 to 12.
Description
BACKGROUND
[0001] The present invention relates to additives for orientation
control of block copolymers used in directed self-assembly
applications, and more specifically to random copolymer additives
comprising non-fluorinated hydrogen-bond donating repeat units and
fluorinated non-hydrogen-bond donating repeat units for top
orientation-control of high-chi (.chi.) block copolymers containing
a polycarbonate block.
[0002] Block copolymers (BCPs) find many applications in solution,
bulk and thin films. Thin film applications of BCPs are
particularly attractive for nanolithography and patterning due to
the ability of some BCPs to form periodic self-assembled structures
ranging in feature size from 5 nm to 50 nm. The thin-film
self-assembly property of BCPs can be utilized with existing
photolithographic techniques to provide a unique approach to long
range order for semiconductor applications. This approach, called
directed self-assembly (DSA) of block copolymers, promises to
extend the patterning capabilities of conventional lithography.
[0003] BCPs for directed self-assembly (DSA) applications comprise
two or three polymer blocks that can phase separate into domains
characterized by ordered nanoscopic arrays of spheres, cylinders,
gyroids, and lamellae. The ability of a BCP to phase separate
depends on the Flory Huggins interaction parameter chi (.chi.).
Poly(styrene)-block-poly(methyl methacrylate), abbreviated as
PS-b-PMMA, is the most widely used block copolymer for DSA. For
PS-b-PMMA, the poly(styrene) block (PS) and the poly(methyl
methacrylate) block (PMMA) have similar surface energies at the
polymer-air interface. In this instance, annealing a thin layer of
the BCP, which is disposed on an orientation control layer, induces
phase separation to produce BCP domains that are perpendicularly
oriented to the orientation control layer. Typically, for PS-b-PMMA
the orientation control layer is a crosslinkable or brush-type
random copolymer formed with styrene and methyl methacrylate. The
neutral wetting properties of the orientation control layer
(underlayer) can be controlled by adjusting the composition of
styrene and methyl methacrylate in order to enable perpendicular
orientation of the BCP lamellar domains.
[0004] The minimum half-pitch of PS-b-PMMA is limited to about 10
nm because of the lower interaction and interaction parameter chi
(.chi.) between PS and PMMA. To enable further feature
miniaturization, a block copolymer having a high interaction
parameter between two blocks (high chi block copolymer) is
desirable. Several block copolymers having higher interaction
parameters between the two blocks have been studied to obtain
smaller feature sizes. Of particular interest are block copolymers
comprising a block derived from ring opening of a cyclic carbonyl
monomer from a reactive end-group on the first polymer block. Block
copolymers formed by ring opening polymerization (ROP) of cyclic
monomers (e.g., lactides, lactones, ethylene oxide) have been used
to generate sub-10 nm feature sizes for patterning
applications.
[0005] As the interaction parameter between the two blocks of the
block copolymer increases, neutral underlayer properties alone may
not be sufficient for forming perpendicularly oriented block
copolymer domains due to the increased mismatch between the
polymer-air surface energies of the two blocks. This causes
parallel orientation of the block copolymer domains with only the
lower surface energy block present at the polymer-air interface,
rendering the thin-film undesirable for lithographic applications.
Top-coat based orientation control strategies have been employed to
control the surface energy at the polymer-air interface of the
blocks. However, these strategies introduce additional process
complexity in the integration of high-chi block copolymers into
standard lithography processes.
[0006] There exists a need to develop a top-coat free method for
perpendicularly orienting block copolymer domains of a high-chi
block copolymer with sub-10 nm half-pitch.
SUMMARY
[0007] A composition is disclosed, comprising:
[0008] i) a solvent;
[0009] ii) a block copolymer comprising: [0010] a) a first block
comprising a repeat unit of formula (B-1):
##STR00001##
[0011] wherein I) R.sup.w is a monovalent radical selected from the
group consisting of H, methyl, ethyl, and trifluoromethyl
(*--CF.sub.3) and II) R.sup.d is a monovalent radical comprising an
aromatic ring linked to carbon 1, and [0012] b) an aliphatic
polycarbonate second block (polycarbonate block) linked to the
first block; and
[0013] iii) a surface active polymer (SAP), comprising: [0014]
about 40 mol % to about 90 mol %, based on total moles of monomers
used to prepare the SAP, of a fluorinated repeat unit (first repeat
unit), wherein the first repeat unit has a chemical structure
having no functionality capable of donating a hydrogen to form a
hydrogen bond, [0015] about 10 mol % to about 60 mol %, based on
total moles of monomers used to prepare the SAP, of a
non-fluorinated second repeat unit comprising a functional group
selected from the group consisting of alcohols, carboxylic acids,
phosphonic acids, and sulfonic acids; wherein [0016] the block
copolymer and the SAP are dissolved in the solvent.
[0017] Also disclosed is a method, comprising:
[0018] providing a first layered structure comprising a top layer
(underlayer);
[0019] disposing the composition of claim 1 on the underlayer and
removing any solvent, thereby forming a second layered structure
comprising a film layer disposed on the underlayer, wherein the
film layer comprises the block copolymer and the SAP in
non-covalent association, and the film layer has a top surface in
contact with an atmosphere; and
[0020] allowing or inducing the block copolymer of the film layer
to self-assemble, thereby forming a third layered structure
comprising a phase separated domain pattern having a characteristic
pitch Lo, the domain pattern comprising alternating domains
comprising respective chemically distinct blocks of the block
copolymer;
wherein
[0021] each of the domains has contact with the underlayer and the
atmosphere, and
[0022] a domain comprising the polycarbonate block has a higher
concentration of the SAP compared to a domain comprising the first
block of the block copolymer.
[0023] Another method is disclosed, comprising:
[0024] providing a first layered structure comprising a top layer
(underlayer);
[0025] forming a topographical resist pattern disposed on the
underlayer, the resist pattern comprising features having recessed
regions, the recessed regions having a bottom surface which is a
portion of a surface of the underlayer;
[0026] disposing the composition of claim 1 substantially in the
recessed regions of the resist pattern and removing any solvent,
thereby forming a second layered structure comprising a film layer,
the film layer comprising the block copolymer and the SAP, wherein
the film layer is in contact with the bottom surface, the bottom
surface is neutral wetting to the block copolymer, and the film
layer has a top surface in contact with an atmosphere; and
[0027] allowing or inducing the block copolymer to self-assemble,
thereby forming a third layered structure comprising a pattern of
phase separated domains (domain pattern) of the block copolymer in
the recessed regions, wherein each of the domains is in contact
with the bottom surface and the atmosphere, and each of domains is
oriented perpendicular to a main plane of the underlayer.
[0028] Also disclosed is a surface active polymer (SAP) of formula
(H-5):
E'-P'-E'' (H-5),
wherein
[0029] E' is a first end group,
[0030] E'' is a second end group, and
[0031] P' is a polymer chain consisting essentially of: [0032] i)
first repeat units selected from the group consisting of:
##STR00002##
[0032] and combinations thereof, wherein each R' is independently
selected from the group consisting of hydrogen (*--H), methyl
(*-Me), ethyl (*-Et), and trifluormethyl (*--CF.sub.3), and each n'
is an independent integer having a value of 1 to 12, and [0033] ii)
second repeat units selected from the group consisting of
##STR00003##
[0033] and combinations thereof, wherein each R'' is independently
selected from the group consisting of *--H, *-Me, *-Et.
[0034] The above-described and other features and advantages of the
present invention will be appreciated and understood by those
skilled in the art from the following detailed description,
drawings, and appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0035] FIGS. 1A to 1F are cross-sectional layer diagrams showing a
process of forming a perpendicularly oriented lamellar domain
pattern using a self-assembly layer (SA layer) comprising a
disclosed high-chi block copolymer comprising a polycarbonate block
and a disclosed surface active polymer (SAP). The underlayer is
neutral wetting to the block copolymer.
[0036] FIGS. 2A to 2E are cross-sectional layer diagrams showing a
process of forming a perpendicularly oriented lamellar domain
pattern in the presence of a topographic pre-pattern. The air
interface is not neutral wetting to the block copolymer in the
absence of the SAP. The air interface becomes neutral wetting to
the block copolymer during self-assembly. The resist features can
be non-neutral wetting to the SA layer comprising the high-chi
block copolymer and SAP.
[0037] FIG. 3 is an AFM height image of the self-assembled block
copolymer film of Example 66.
[0038] FIG. 4 is an AFM height image of the self-assembled block
copolymer film of Example 67.
[0039] FIG. 5 is an AFM height image of the self-assembled block
copolymer film of Example 68.
[0040] FIG. 6 is an AFM height image of the self-assembled block
copolymer film of Example 69.
[0041] FIG. 7 is an AFM height image of the self-assembled block
copolymer film of Example 70.
[0042] FIG. 8 is an AFM height image of the self-assembled block
copolymer film of Example 71.
[0043] FIG. 9 is an AFM height image of the self-assembled block
copolymer film of Example 72.
[0044] FIG. 10 is an AFM height image of the self-assembled block
copolymer film of Example 73.
[0045] FIG. 11 is an AFM height image of the self-assembled block
copolymer film of Example 74.
[0046] FIG. 12 is an AFM height image of the self-assembled block
copolymer film of Example 75.
[0047] FIG. 13 is an AFM height image of the self-assembled block
copolymer film of Example 76.
[0048] FIG. 14 is an AFM height image of the self-assembled block
copolymer film of Example 77.
[0049] FIG. 15 is an AFM height image of the self-assembled block
copolymer film of Example 78.
[0050] FIG. 16 is a set of AFM height images at two magnifications
of the self-assembled block copolymer film of Example 79.
[0051] FIG. 17 is an AFM height image of the self-assembled block
copolymer film of Example 83.
[0052] FIG. 18 is an AFM height image of the self-assembled block
copolymer film of Example 84.
[0053] FIG. 19 is an AFM height image of the self-assembled block
copolymer film of Example 85.
[0054] FIG. 20 is an AFM height image of the self-assembled block
copolymer film of Example 86.
[0055] FIG. 21 is an AFM height image of the self-assembled block
copolymer film of Example 87.
[0056] FIG. 22 is an AFM height image of the self-assembled block
copolymer film of Example 88.
[0057] FIG. 23 is an AFM height image of the self-assembled block
copolymer film of Example 89.
[0058] FIG. 24 is an AFM height image of the self-assembled block
copolymer film of Example 90.
[0059] FIG. 25 is an AFM height image of the self-assembled block
copolymer film of Example 91.
[0060] FIG. 26 is an AFM height image of the self-assembled block
copolymer film of Example 92.
[0061] FIG. 27 is an AFM height image of the self-assembled block
copolymer film of Example 93.
[0062] FIG. 28 is an AFM height image of the self-assembled block
copolymer film of Example 94.
[0063] FIG. 29 is an AFM height image of the self-assembled block
copolymer film of Example 95.
[0064] FIG. 30 is a schematic cross-sectional representation
(Scheme 1) of parallel oriented lamellar domains of a
self-assembled diblock copolymer. The main plane of each lamellar
domain is parallel to the plane of the underlayer surface.
[0065] FIG. 31 is a schematic cross-sectional representation
(Scheme 2) of parallel oriented lamellar domains of a
self-assembled BCP when the atmosphere is non-neutral to the BCP,
and the self-assembly process forms islands and holes on a neutral
underlayer surface.
[0066] FIG. 32 is a schematic cross-sectional representation
(Scheme 3) of perpendicularly oriented lamellar domains of a
self-assembled BCP in which the SA layer comprises an SAP that is
preferentially soluble in the domain comprising block B.
DETAILED DESCRIPTION
[0067] Disclosed are phase-selective and surface active polymers
(SAPs) for lithographic processes utilizing self-assembly of block
copolymers. The SAPs are also referred to below as "polymer
additives". The SAPs provide orientation control of phase domains
formed by self-assembly of high-chi block copolymers (BCPs)
comprising a polycarbonate block. "High-chi" means the BCPs have a
large Flory-Huggins interaction parameter chi (.chi.). The higher
the chi parameter, the poorer the miscibility of the different BCP
blocks with one another, and the sharper the phase boundaries
separating the phase domains containing the different blocks after
self-assembly of the BCP. The SAPs are preferentially soluble in
the polycarbonate domain formed by self-assembly (i.e., the domain
comprising the polycarbonate block of the block copolymer). The
SAPs also lower the surface energy of the polycarbonate domain
compared to an otherwise identical polycarbonate domain lacking the
SAP, thereby allowing the polycarbonate domain to wet the
atmosphere interface resulting in lamellae and cylinders having a
perpendicular orientation with respect to the main plane of the
substrate.
[0068] Herein, an "atmosphere" is a gas, which can include air
and/or one or more other gases at any suitable pressure in contact
with the top surface of the SA layer.
[0069] Herein, "non-fluorinated" means the chemical formula of a
referenced material contains no fluorine. The referenced material
can be a sub-structure of a polymer such as a repeat unit. A
material is "fluorinated" if the chemical formula of the material
contains one or more fluorines. A material described as containing
one or more "fluorines", "fluorine groups", or "fluoride groups"
herein means the material has a chemical structure in which one or
more monovalent fluorine atoms are covalently bound to carbon(s) of
the chemical structure.
[0070] An "SA material" is a material capable of self-assembling
into compositionally different phase-separated domains.
Self-assembly (SA) refers to a process in which the SA material
undergoes phase separation to produce a pattern of immiscible solid
phase domains under suitable conditions. Self-assembly can occur
spontaneously upon formation of the SA layer, or self-assembly can
be induced (e.g., by annealing an SA layer comprising an SA
material at an elevated temperature for a suitable period of time).
The SA material is preferably a block copolymer (BCP).
[0071] A block copolymer for self-assembly comprises at least two
blocks that are immiscible with each other. Non-limiting block
copolymers include diblock and triblock copolymers. Self-assembly
of the block copolymer occurs by phase separation of the blocks to
form a pattern of segregated solid phase domains. Depending on the
volume fraction of the blocks, the domains can have the form of
lamellae, spheres, cylinders, and/or gyroids. As an example,
self-assembly of a diblock copolymer can produce a domain pattern
comprising a first lamellar domain containing substantially a first
block A of the diblock copolymer and a second lamellar domain
containing substantially a second block B of the diblock copolymer.
In this instance, the first and second lamellar domains are linked
by the covalent bond joining block A to block B of the block
copolymer.
[0072] Herein, an "SA layer" is a layer comprising an SA material
and an SAP. The SA layer is disposed on a top surface of a
substrate. The SA layer can comprise other materials.
[0073] Herein, any material of the top surface of the substrate
that has contact with the bottom of the SA layer is referred to
generally as "underlayer material" or "orientation control
material". A layer comprising underlayer material is an
"underlayer" or "orientation control layer". The underlayer surface
influences self-assembly of an SA material of the SA layer.
[0074] A surface is said to have a "preferential affinity for" or
is "preferential to" a referenced domain of a self-assembled SA
material if the referenced domain can wet the surface in preference
to another domain of the self-assembled SA material. Otherwise, the
surface is said to be "non-preferential" to the referenced
domain.
[0075] The substrate is the layered structure on which the SA layer
is disposed. The substrate has a main plane, which is parallel to
the bottom-most layer of the substrate. The substrate can comprise
one or more layers of materials arranged in a stack, more
specifically materials used in the fabrication of semiconductor
devices. As non-limiting examples, the substrate can include a
bottom layer (e.g., silicon wafer, metal foil), hard mask layer,
dielectric layer, metal oxide layer, silicon oxide layer, silicon
nitride, titanium nitride, hafnium oxide, an anti-reflection layer
(ARC), and/or an orientation control layer (underlayer) for
self-assembly. The SA layer is disposed on the top surface of the
substrate, which is typically the top surface of the orientation
control layer. When a resist pattern is formed on the orientation
control layer, the substrate includes the resist pattern. In this
instance, the SA layer can be disposed in the trenches of the
resist pattern.
[0076] The top surface of the substrate can be a "graphoepitaxial
pre-pattern" or a "chemical pre-pattern" for self-assembly. Each
type of pre-pattern can be composed of topographical features, such
as in a resist pattern. A graphoepitaxial pre-pattern influences
self-assembly by the topography and surface properties of the
pre-pattern. A "chemical pre-pattern" influences self-assembly
predominantly by way of the surface properties of different regions
of the pre-pattern. No sharp dimensional limits exist between these
two pre-pattern categories because the extent of topographical
influence on self-assembly is also dependent on the thickness of
the SA layer in relation to the underlying relief surface, as well
as the annealing conditions (time and temperature) used for
self-assembly. In general, however, when graphoepitaxial
pre-patterns are used, the thickness of the SA layer is less than
or equal to the height of the topographical features of the
pre-pattern. For chemical pre-patterns, the SA layer thickness is
greater than any height of the underlying topographical features of
the pre-pattern.
[0077] The term "interface" refers to a contact boundary between
two substantially immiscible phases. Each phase can, independently,
be a solid, a liquid, or a gas.
[0078] A lamellar or cylindrical domain can be oriented parallel or
perpendicular to the plane of the underlying orientation control
layer (underlayer) or the main plane of the SA layer. A lamellar
domain has a parallel orientation when the main plane or plate of
the lamellar domain is oriented parallel to the main plane of the
underlying surface (or SA layer). A lamellar domain has a
perpendicular orientation when the main plane or plate of the
lamellar domain is oriented perpendicular to the main plane of the
underlying surface (or SA layer). A cylindrical domain has a
parallel orientation when the cylinder axis is oriented parallel to
the main plane of the underlying surface (or SA layer). A
cylindrical domain has a perpendicular orientation when the
cylinder axis is oriented perpendicular to the main plane of the
underlying surface (or SA layer).
[0079] Domain orientation can also be expressed relative to the
main plane of the substrate. A lamellar domain has a parallel
orientation when the main plane or plate of the lamellar domain is
oriented parallel to the main plane of the substrate. A lamellar
domain has a perpendicular orientation when the main plane or plate
of the lamellar domain is oriented perpendicular to the main plane
of the substrate. A cylindrical domain has a parallel orientation
when the cylinder axis is oriented parallel to the main plane of
the substrate. A cylindrical domain has a perpendicular orientation
when the cylinder axis is oriented perpendicular to the main plane
of the substrate.
[0080] Perpendicular orientation of lamellar domains is desirable
for forming high resolution line patterns by selective etching of a
given lamellar domain. Parallel orientation is not desirable for
forming high resolution line patterns.
[0081] The term "disposed" refers to a layer in contact with a
surface of another layer. "Disposing" or "applying" refer to
forming a layer to be in contact with a surface of another layer,
without limitation as to the method employed unless otherwise
stated, with the proviso that the desirable characteristics of the
disposed or applied layer are obtained, such as uniformity and
thickness.
[0082] The term "casting" refers to forming a layer of a material
by disposing on a surface a solution of the material dissolved in a
solvent, and removing the solvent.
[0083] Random copolymers are indicated by "-co-", or "-r-" in the
name. Block copolymers are indicated by "-b-" or "-block-" in the
name. Alternating block copolymers are indicated by "-alt-" in the
name.
[0084] Herein, "symmetrical wetting" means the underlayer surface
and the atmosphere interface are wetted by the same domain(s) of
the self-assembled SA material. "Non-symmetrical" wetting means the
underlayer surface and the atmosphere interface are wetted by
different domain(s) of the self-assembled SA material.
[0085] Herein, a surface or an atmosphere interface is said to be
"neutral" to an SA material, or "neutral wetting" with respect to
an SA material if each domain of the self-assembled SA material has
contact with the surface or the atmosphere interface after
self-assembly. Otherwise, the surface or atmosphere interface is
said to be "non-neutral" to the SA material. For example, an
underlayer surface is "neutral wetting" to a block copolymer if
after self-assembly each domain of the self-assembled block
copolymer has contact with the underlayer surface. It should be
understood that each domain of the self-assembled SA material can
comprise SAP, and each domain can have a different concentration of
SAP after self-assembly. A neutral underlayer surface allows
orientation control but does not guide the lateral spatial
arrangement of the self-assembled domains. A non-neutral underlayer
surface can guide self-assembly. For purposes of the invention, it
is desirable for the underlayer and the atmosphere to be neutral
wetting to the domains formed by self-assembly of the SA layer
comprising the SA material and the SAP.
[0086] For commercial purposes, the underlayer surface and the
atmosphere interface must be non-preferential (neutral) to the SA
material in order to obtain perpendicularly oriented lamellar
domains when no other chemical or topographical features are
available to influence self-assembly of the block copolymer. If
only one interface is neutral to the SA material, the lamellar
domains orient parallel to the underlayer surface to form an
island/hole morphology having 0.5Lo ("L nought") step height. "Step
height" refers to height difference relative to the surrounding SA
material and Lo is the characteristic pitch (bulk periodicity) of
the domains of the self-assembled SA material. The higher the chi
parameter of the SA material, the smaller the potential Lo (pitch)
of the domain pattern.
[0087] These parameters are illustrated in the diagrams of Schemes
1-3 (FIGS. 30-32) described further below. If only the underlayer
surface is neutral, both block copolymer (BCP) domains initially
wet the underlayer surface with 0.5Lo perpendicular lamellae, but
eventually form parallel morphology as the atmosphere (e.g., air)
is non-neutral, resulting in island/holes with parallel lamellae
having 0.5Lo step height.
[0088] For purposes of demonstrating the present invention, the
substrate comprises an orientation control layer (underlayer)
disposed on a silicon wafer. The underlayer surface can be a planar
surface having uniform surface properties (i.e., the underlayer
surface has no topographical or chemical patterning). Most of the
examples further below utilize a planar underlayer. Other examples
utilize a substrate having a topographic resist pattern on the
underlayer for graphoepitaxy. The SA layer is disposed on the
underlayer and has a top surface in contact with an atmosphere. It
is desirable that self-assembly of the SA layer comprising the SA
material and the SAP forms a lamellar domain pattern comprising
alternating perpendicularly oriented lamellae of each domain that
are in contact with the underlayer and the atmosphere. The
underlayer material can be any material having suitable neutral
wetting properties to the domains of the given SA material.
[0089] The SA layer has the following characteristics. The SA layer
comprises a high-chi BCP comprising an aliphatic polycarbonate
block. Additionally, the BCP has a structure favoring formation of
lamellar domains or cylindrical domains during self-assembly. That
is, the volume fractions of the blocks of the block copolymer are
in a range favorable to lamellar domain or cylindrical domain
formation. Also, the SA layer is disposed on the underlayer
surface, which is neutral wetting to the domains of the
self-assembled BCP. Lastly, the SA layer has a top surface in
contact with an atmosphere. The atmosphere interface, which is
typically air, is not neutral to the BCP, meaning less than all
domains at the top surface of the self-assembled SA layer are in
contact with the atmosphere when the SA layer consists essentially
of BCP. Under these conditions, typically only one domain of the
self-assembled BCP has contact with the atmosphere (lamellae have a
parallel orientation). In general, the higher the chi parameter of
the BCP, the greater the mismatch in surface properties between the
underlayer surface and the atmosphere, causing parallel orientation
of lamellar domains.
[0090] Given the foregoing characteristics of the SA layer, an SA
layer that contains no SAP self-assembles to form parallel oriented
lamellar domains, due to less than all domains being capable of
"wetting" the atmosphere. Parallel oriented lamellar domains are
characterized by the appearance of islands and holes in atomic
force microscopy (AFM) height images (Scheme 2, FIG. 31). It is
desirable that self-assembly of the SA layer comprising the SA
material and the SAP forms a lamellar domain pattern wherein each
domain is in contact with the underlayer and the atmosphere. The
underlayer material can be any material having suitable neutral
wetting properties to the domains of the given SA material.
[0091] The following discussion is focused on lamellar domain
patterns formed by self-assembly of a diblock copolymer, but is
applicable to other block copolymers (e.g., triblock copolymers)
and other domain morphologies (e.g., cylindrical domains). It
should be understood that the layer diagrams are not drawn to scale
or meant to be limiting with respect to the possible structures
that can be produced using the below-described processes. The
diagrams are intended for illustration purposes.
[0092] Without being bound by theory, Scheme 1 (FIG. 30) is a
schematic cross-sectional representation of parallel oriented
lamellar domains of a self-assembled diblock copolymer. The main
plane of each lamellar domain is parallel to the plane of the
underlayer surface.
[0093] Scheme 1 shows the arrangement of blocks A and B of a
diblock copolymer after self-assembly of the diblock copolymer on
an underlayer surface that is preferential to the domain containing
block A. In this example, the underlayer and atmosphere interface
have preferential affinity to the domain containing block A. The
first lamellar domain comprises block A and the second lamellar
domain comprises block B. The bulk periodicity Lo of the domains is
indicated by 1.0Lo (1.0 times Lo). The individual diblock copolymer
macromolecules, domain boundaries, and 0.5Lo are also indicated. It
should be understood that within a given lamellar domain (e.g., the
second lamellar domain of Scheme 1) blocks from different polymer
macromolecules (e.g., B blocks) can be arranged end-to-end (shown)
and/or interwoven (not shown). Each block can have a backbone that
is rigid, non-rigid, or of intermediate rigidity. Each block can
have any suitable coiling, rotational and/or flexural
capability.
[0094] For purposes of the present invention, the atmosphere
interface is always a non-neutral interface with respect to the
high-chi BCPs. An SA layer consisting essentially of a high-chi BCP
in contact with the atmosphere interface will almost certainly
undergo self-assembly to form islands and holes whose boundaries
represent a disruption in parallel oriented lamellae. This occurs
regardless of whether the underlayer is neutral or non-neutral to
the BCP.
[0095] Scheme 2 (FIG. 31) is a schematic cross-sectional
representation of parallel oriented lamellar domains of a
self-assembled BCP when the atmosphere is non-neutral to the BCP,
and the self-assembly process forms islands and holes on a neutral
underlayer surface.
[0096] In Scheme 2, the underlayer surface is in contact with the
domain containing block A and the domain containing block B, and
only the block A domain has contact with the atmosphere. The
neutral (non-preferential) wetting properties of the underlayer
surface cause disruptions in the parallel oriented lamellar
domains, resulting in formation of islands and holes having a step
height h' by AFM of about 0.5 Lo. It should be understood that
block A phase separates to retain contact with the atmosphere,
including in the disruption zone of the lamellar domains (the
boundary of the hole and the island). No attempt has been made to
characterize the arrangement of blocks B in the disruption zone of
Scheme 2.
[0097] The examples further below show that an SA layer comprising
a BCP and a disclosed SAP can self-assemble to form perpendicularly
oriented lamellar domains when the top surface of the SA layer has
contact with the atmosphere. The SAP is preferentially miscible
with the polycarbonate domain (i.e., the domain comprising the
polycarbonate block of the self-assembled BCP) and substantially
immiscible with non-polycarbonate domains of the self-assembled
block copolymer (e.g., a block prepared from a vinyl polymerizable
monomer such as styrene and/or substituted styrenes).
[0098] Without being bound by theory, self-assembly is believed to
produce a polycarbonate domain having a greater concentration of
SAP than the non-polycarbonate domain. The higher SAP concentration
of the polycarbonate domain after self-assembly may allow the
SAP-enriched polycarbonate domain to wet the atmosphere interface,
thereby allowing perpendicularly orientation of the lamellar
domains. Non-polycarbonate domains having contact with the
atmosphere can be essentially free of SAP at the atmosphere
interface. When the block copolymer structure favors cylindrical
domain formation, the presence of the SAP can allow formation of
perpendicularly oriented cylindrical domains.
[0099] Scheme 3 (FIG. 32) is a schematic cross-sectional
representation of perpendicularly oriented lamellar domains of a
self-assembled BCP in which the SA layer comprises a SAP that is
preferentially soluble in the domain comprising block B. The SAP is
represented by the forward slash marks within the block B and block
A domains. The block B domain can comprise a concentration gradient
in SAP, wherein the concentration of SAP is highest at the
atmosphere interface (not shown). The block A domain can have
essentially no SAP at the atmosphere interface.
[0100] In Scheme 3, the main planes of the lamellae are oriented
perpendicular to the plane of the underlayer surface, and also to
the main plane of the SA layer. The lamellae of each domain are in
contact with the atmosphere and underlayer surface. The bulk
periodicity, Lo, is indicated, as well as 0.5Lo. In this example,
the underlayer surface has contact with block A and block B of the
self-assembled diblock copolymer. Therefore, the underlayer is
neutral to the self-assembled diblock copolymer. The presence of
the SAP allows the SAP-containing block B domain to contact the
atmosphere interface.
[0101] The examples further below were carried out using a neutral
underlayer. If an SA layer comprising a self-assembled BCP exhibits
islands and/or holes or parallel cylinders by atomic force
microscopy, the atmosphere interface (air interface) is non-neutral
to the self-assembled SA layer (undesirable). If an SA layer
comprising a self-assembled BCP exhibits perpendicularly oriented
lamellae or cylinders, the atmosphere interface (air interface) is
neutral to the self-assembled SA layer (desirable).
[0102] The examples further below show that the SAP allows
perpendicularly oriented domain patterns to be formed without
employing a top coat (i.e., a layer between the SA layer and the
atmosphere interface) or employing a topographic pre-pattern to
direct self-assembly of the high-chi BCP. Although a topographic
pre-pattern is not essential for orientation control, a topographic
pre-pattern can be present for other purposes. This is also
demonstrated in the examples further below.
[0103] The lamellar domain patterns can have a bulk periodicity,
Lo, in the range of about 4 nm to about 80 nm, which is useful for
producing line features having a half-pitch of about 2 nm to about
40 nm, respectively, more particularly about 2 nm to about 20
nm.
Surface Active Polymers (SAPs)
[0104] The SAP is phase selective, meaning the SAP has preferential
solubility in the polycarbonate domain formed by self-assembly. As
a result, the polycarbonate domain has a higher concentration of
SAP after self-assembly compared to other domains. The SAP
concentration of the polycarbonate domain after self-assembly
lowers the surface energy of the polycarbonate domain sufficiently
to allow the polycarbonate domain to wet the atmosphere interface
and provide perpendicular orientation of each domain. Perpendicular
orientation can be achieved without forming a monolayer of SAP over
the SA layer. For this reason, the SAP can be used in amounts of
more than 0 wt % up to about 10 wt %, more specifically about 0.1
wt % to about 10 wt %, and even more specifically 0.1 wt % to about
5 wt %, based on total weight of the dry solids of the SA layer. In
an embodiment, the formulation used to prepare the SA layer
comprises about 0.5 wt % to about 5 wt % SAP based on total weight
of dry solids of the SA layer. In another embodiment, the
formulation used to prepare the SA layer comprises about 1.5 wt %
to about 3 wt % SAP based on total weight of dry solids of the SA
layer.
[0105] The SAP is preferably a linear random copolymer having
preferential solubility in the polycarbonate domain. Other polymer
architectures (e.g., dendritic polymers, star polymers, and block
polymers) are not excluded as long as the SAP is preferentially
soluble in the polycarbonate domain and does not form a discrete
domain during self-assembly that is separate and distinct from the
polycarbonate domain. A random copolymer is a polymer comprising a
random distribution of the different repeat units making up the
polymer backbone. Random copolymer names can include an "-r-",
"-co-", or "-random-" separating the abbreviated monomer names used
to prepare the polymer. Herein, a linear polymer has a one polymer
branch having two peripheral ends (i.e., dangling ends, as in a
segment of a rope).
[0106] The SAP can be prepared by any suitable polymerization
technique. Exemplary polymerization techniques include radical
polymerization, atom transfer radical polymerization (ATRP),
reversible addition-fragmentation chain-transfer polymerization
(RAFT), ionic polymerization, ring opening polymerization, and
ring-opening metathesis polymerization (ROMP). Non-limiting
monomers for forming an SAP include vinyl polymerizable monomers
(e.g., styrenes, acrylates, methacrylates) and cyclic monomers
(e.g., cyclic ethers, cyclic carbonates).
[0107] The SAP comprises a hydrophobic fluorinated repeat unit
(first repeat unit). Preferably, the first repeat unit comprises a
side chain functional group selected from the group consisting of
fluorinated aromatic rings and fluorinated esters. The first repeat
unit can have a structure in accordance with formula (H-1):
##STR00004##
wherein
[0108] Q' is a monovalent radical comprising an aromatic ring
and/or an ester group,
[0109] R' is a monovalent radical selected from the group
consisting of *--H, methyl (*--CH.sub.3), ethyl (*-Et), and
trifluoromethyl (*--CF.sub.3), and
[0110] Q' and/or R' comprises at least one fluorine.
[0111] Herein, a bond with an asterisk is a starred bond. Starred
bonds are not methyl groups. It should be understood that an atomic
center shown with a starred bond is linked by a covalent bond to
another specified or unspecified atomic center of a chemical
structure. A starred bond can be said to be "linked to" a
referenced structure or atomic center, meaning that the atomic
center shown having the starred bond is linked by a covalent bond
to the referenced structure or atomic center.
[0112] The chemical structure of the first repeat unit has no
functionality capable of donating a hydrogen to form a hydrogen
bond. Non-limiting functionality capable of donating a hydrogen to
form a hydrogen bond include alkyl and aryl alcohols, alkyl and
aryl carboxylic acids, alkyl and aryl peracids, alkyl and aryl
hydrogen peroxides, alkyl and aryl sulfonic acids, alkyl and aryl
sulfinic acids, alkyl and aryl mono- and di-esters of phosphoric
acid, alkyl and aryl monoesters of phosphonic acids, alkyl and aryl
primary amines, alkyl and aryl secondary amines, alkyl and aryl
hydroxylamines, alkyl and aryl primary and secondary amides, and
alkyl and aryl primary and secondary sulfonamides. In an
embodiment, the first repeat unit has a chemical structure that
excludes functionality capable of donating a hydrogen to form a
hydrogen bond.
[0113] More specific first repeat units have a structure in
accordance with formula (H-2):
##STR00005##
wherein
[0114] a' is an integer having a value of 0-5,
[0115] each R.sup.c is an independent monovalent radical selected
from the group consisting of fluoride (*--F), chloride (*--Cl),
bromide (*--Br), fluorinated and non-fluorinated alkyl groups
comprising 1-3 carbons, and fluorinated and non-fluorinated alkoxy
groups comprising 1-3 carbons,
[0116] R' is a monovalent radical selected from the group
consisting of hydrogen (*--H), methyl (*--CH.sub.3), ethyl (*-Et),
and trifluoromethyl (*--CF.sub.3), and
[0117] the first repeat unit comprises at least one fluorine.
[0118] When a starred bond of a given group crosses a bond of a
ring as shown in the above structure, the group can be linked to
any one of the available positional isomers of the ring. The group
can be present as a mixture of positional isomers. This convention
is followed below also. It should be understood that any of
aromatic ring centers labelled 2-6 of formula (H-2), which are not
linked to an R.sup.c group, are linked to hydrogen. In a preferred
embodiment, R' is hydrogen, a' is 5, and each R.sup.c is fluoride.
That is, the aromatic ring moiety is a pentafluorophenyl group and
the first repeat unit is a pentafluorophenylethylen-1,2-yl group,
which can be formed by vinyl polymerization of
pentafluorostyrene:
##STR00006##
[0119] Other more specific first repeat units have structures in
accordance with formula (H-3):
##STR00007##
wherein
[0120] R.sup.d is a monovalent radical selected from the group
consisting of fluorinated alkyl groups comprising 1-30 carbons,
fluorinated aryl groups comprising 1-30 carbons, and fluorinated
poly(alkylene oxide) groups comprising 4 to 30 carbons, and
[0121] R' is a monovalent radical selected from the group
consisting of *--H, methyl (*--CH.sub.3), ethyl (*-Et), and
trifluoromethyl (*--CF.sub.3).
[0122] Exemplary non-limiting fluorinated first repeat units
include those of Scheme 4.
##STR00008##
[0123] In an embodiment, the fluorinated first repeat unit is
selected from the group consisting of
##STR00009##
and combinations thereof, wherein each R' is independently selected
from the group consisting of hydrogen (*--H), methyl (*-Me), ethyl
(*-Et), and trifluormethyl (*--CF.sub.3), and each n' is an
independent integer having a value of 1 to 12. In another
embodiment, the first repeat unit is
##STR00010##
[0124] In another embodiment, the first repeat unit is
##STR00011##
[0125] The SAP further comprises a non-fluorinated second repeat
unit, which comprises at least one hydroxy group capable of
donating a hydrogen to form a hydrogen bond. Each hydroxy group of
the second repeat unit can independently be present as an alcohol,
a hydroxy group of a carboxylic acid, a hydroxy group of a
phosphonic acid, or a hydroxy group of a sulfonic acid group. That
is, the second repeat unit can comprise a member of the group
consisting of alcohols, carboxylic acids, phosphonic acids,
sulfonic acids, and combinations thereof. In an embodiment, the
second repeat unit comprises a phenol.
[0126] More specific second repeat units of the SAP have structures
in accordance with formula (H-4):
##STR00012##
wherein
[0127] b' is 1 or 2,
[0128] Q'' is a single bond or a linking group having a valency of
b'+1 and comprising at least one carbon,
[0129] each J'' is an independent monovalent radical selected from
the group consisting of alcohols, carboxylic acids, phosphonic
acids, and sulfonic acids, and
[0130] R'' is a monovalent radical selected from the group
consisting of *--H, methyl (*--CH.sub.3), ethyl (*-Et).
[0131] Preferably, Q'' comprises an aromatic ring, ester carbonyl,
or amide carbonyl group linked to carbon 1 of formula (H-4). In an
embodiment, each J'' is selected from the group consisting of
*--OH, and *--COOH.
[0132] More specific Q'' groups include those of Scheme 5, wherein
the starred bond of carbon 1 of Q'' is linked to carbon 1 bearing
the R'' group of formula (H-4), and each remaining starred bond of
Q'' is linked to a J'' group.
##STR00013##
[0133] More specific second repeat units of the SAP include those
of Scheme 6.
##STR00014## ##STR00015##
[0134] In an embodiment, the second repeat unit of the SAP is
selected from the group consisting of
##STR00016##
and combinations thereof, wherein each R'' is independently
selected from the group consisting of *--H, *-Me, *-Et.
[0135] The SAP can comprise the second repeat units singularly or
in combination.
[0136] Monomers used to form the second repeat units, referred to
herein as "second monomers", can be the corresponding styrene,
methacrylate, or methacrylamide monomers of the above-mentioned
first repeat units or protected forms thereof that can be
deprotected after the polymerization. For example, the above repeat
unit S6-1 can be obtained by vinyl polymerization of
4-acetoxystyrene followed treatment of the resulting polymer with
aqueous base (e.g., ammonium hydroxide) to hydrolyze the acetoxy
ester, thereby forming S6-1. Non-limiting exemplary second monomers
include those of Scheme 7.
##STR00017##
[0137] Particularly preferred second monomers for forming a SAP
include 4-acetoxystyrene (Ac-Sty) and 4-vinylbenzoic acid
(4-VBA):
##STR00018##
[0138] More specific SAP polymers have a structure in accordance
with formula (H-5):
E'-P'-E'' (H-5),
wherein
[0139] E' is a first end group,
[0140] E'' is a second end group,
[0141] P' is a polymer chain consisting essentially of: [0142] i)
fluorinated first repeat units selected from the group consisting
of:
##STR00019##
[0142] and combinations thereof, wherein each R' is an independent
radical selected from the group consisting of hydrogen (*--H),
methyl (*-Me), ethyl (*-Et), and trifluoromethyl (*--CF.sub.3), and
each n' is an independent integer having a value of 1 to 12, and
[0143] ii) second repeat units selected from the group consisting
of
##STR00020##
[0143] and combinations thereof, wherein each R'' is independently
selected from the group consisting of *--H, *-Me, *-Et.
[0144] The SAP can have any suitable end group functionality E' and
E'', with the proviso that wetting properties of the SAP do not
adversely affect self-assembly. Non-limiting E' and/or E'' groups
include hydrogen, halide (e.g., fluoride, chloride, bromide,
iodide), alkyl groups, alkoxy groups, ester groups, aromatic
groups, non-aromatic cyclic groups, groups comprising combinations
of the foregoing functionalities, and any of the foregoing groups
substituted with one or more fluorine groups.
[0145] E' and/or E'' of formula (H-5) can comprise 1 to 25
fluorines, more particularly 10-25 flourines. In an embodiment, end
group E' and/or E'' comprises an ester group comprising 1 to 25
fluorines. Non-limiting examples of fluorinated ester groups
include those of Scheme 8.
##STR00021##
[0146] A more specific SAP polymer comprises a first end group E'
containing an above-described fluorinated ester group and a second
end group E'' that is bromide. As an example, Scheme 9 illustrates
the ATRP copolymerization of pentafluorostyrene (PFS) and
4-hydroxystyrene (HOST) to form random copolymer S9-1 using ATRP
initiator Pf-OiBr.
##STR00022##
[0147] In the above notation of Scheme 9, the square brackets
indicate the ends of the polymer chain, which is composed of the
repeat units enclosed by the square brackets. The vertical stacking
of the repeat units within the square brackets indicates a random
distribution of the repeat units in the polymer chain. In a random
distribution of the repeat units, a given repeat unit whose starred
bond overlaps the left square bracket can be linked to a different
one of the repeat units at an atomic center whose starred bond
overlaps the right square bracket, or to end group E', represented
in this instance by the moiety derived from Pf-OiBr. Likewise, a
given repeat unit whose starred bond overlaps the right squared
bracket can be linked to an atomic center of a different one of the
repeat units at an atomic center whose starred bond overlaps the
left square bracket, or to end group E'', represented in this
instance by the bromide group. End group E' can be linked to any
one of the repeat units at an atomic center having a starred bond
overlapping the left square bracket. End group E'' can be linked to
any one of the repeat units at an atomic center having a starred
bond overlapping the right square bracket. Subscripts x' and y' can
represent molar ratio or average degree of polymerization (DP) of
the corresponding repeat unit enclosed in parentheses.
[0148] The SAP can comprise the fluorinated first repeat unit in an
amount of about 40 mol % to about 90%, preferably about 55 mol % to
about 80 mol %, based on total moles of monomers used to form the
SAP. The SAP can comprise the non-fluorinated second repeat unit in
an amount of about 10 mol % to about 60%, preferably about 20 mol %
to about 45 mol % based on total moles of monomer used to prepare
the SAP.
[0149] The SAP can have a number average molecular weight (Mn) of
about 1000 to about 100000, more particularly 2000 to about 50000,
and even more particularly about 2000 to about 20000. The SAP can
have a polydispersity index of about 1.0 to about 3.0.
Random Copolymers for Orientation Control (Underlayer)
[0150] In general, the underlayer polymer is a random copolymer
capable of undergoing a reaction to form a covalent bond with
another layer of the substrate.
[0151] For SA materials comprising a polycarbonate block having
ester side chains linked to the carbonate backbone, the underlayer
polymer can potentially be a crosslinkable or brush-type random
copolymer of styrene (Sty) and methyl methacrylate (MMA), also
referred to as poly(styrene-r-methyl methacrylate) or
P(Sty-r-MMA).
[0152] The following discussion pertains to underlayers for
high-chi SA materials comprising a polycarbonate block having no
side chain groups (e.g., a poly(trimethylene carbonate) block
(PTMC)) or a polycarbonate block having carbonate repeat units
comprising an alkyl side chain group of 1-3 carbons (e.g., methyl,
ethyl, propyl).
[0153] For these high-chi SA materials, the underlayer polymer
preferably comprises a repeat unit comprising an ethylenic backbone
portion and a side chain portion comprising a polycarbonate chain.
The polycarbonate chain of the side chain can comprise 1 or more
carbonate repeat units, preferably 2 to about 40 carbonate repeat
units. In an embodiment, the carbonate repeat unit of the pendant
polycarbonate chain of the underlayer polymer has the same chemical
structure as the carbonate repeat unit of the polycarbonate block
of the BCP used in the SA layer (described further below). The
underlayer polymers comprising a pendant polycarbonate chain can be
prepared by ring opening polymerization (ROP) of a cyclic carbonate
using a polymeric macroinitiator having one or more pendant hydroxy
groups capable of initiating the ROP. The polymeric macroinitiator
can be prepared by random polymerization of one or more vinyl
polymerizable monomers comprising a pendant alcohol group (e.g.,
hydroxyethyl methacrylate, HEMA) or a protected alcohol group that
is subsequently deprotected.
[0154] I) Underlayers for SA Materials Formed Comprising
Trimethylene Carbonate (TMC)
[0155] More specifically, the random copolymers for the underlayer
comprise a first repeat unit of formula (A-1):
##STR00023##
[0156] wherein
[0157] R.sup.x is a monovalent radical selected from the group
consisting of H, methyl, ethyl, and trifluoromethyl (*--CF.sub.3),
and
[0158] R.sup.b is a monovalent radical comprising an aromatic
ring.
[0159] It should be understood that the two starred bonds of
formula (A-1) represent attachment points to other repeat units of
the polymer chain or to polymer chain end groups, carbons 1 and 2
are ethylenic carbons of the polymer backbone, R.sup.x is a first
side chain linked to carbon 1 of the polymer backbone, and R.sup.b
is a second side chain linked to carbon 1 of the polymer
backbone.
[0160] Non-limiting R.sup.b groups of formula (A-1) include
substituted and unsubstituted aryl groups. Exemplary R.sup.b groups
are listed in Scheme 10 below, where the starred bond of the
aromatic ring is linked to carbon 1 of formula (A-1).
##STR00024## ##STR00025##
[0161] In an embodiment, R.sup.x of formula (A-1) is hydrogen, and
R.sup.b is phenyl.
[0162] The random copolymers comprise a second repeat unit of
formula (A-2):
##STR00026##
wherein
[0163] R.sup.x is a monovalent radical selected from the group
consisting of H, methyl, ethyl, and trifluoromethyl (*--CF.sub.3),
and
[0164] Z' is a monovalent radical comprising two or more
carbonyl-containing functional groups independently selected from
the group consisting of ester groups, carbonate groups, amide
groups, carbamate groups, and combinations thereof.
[0165] It should be understood that R.sup.x is a first side chain
of the second repeat unit which is linked to polymer backbone
carbon 1 of formula (A-2), and Z' is a second side chain of the
second repeat unit linked to polymer backbone carbon 1 of formula
(A-2).
[0166] Second repeat units of formula (A-2) include those obtained
from styrenes, acrylates, methacrylates, acrylamides,
methacrylamides, and the like, which are modified before or after
vinyl polymerization to comprise the two or more
carbonyl-containing functional groups.
[0167] More specific Z' groups of formula (A-2) include those of
formula (A-2a):
##STR00027##
wherein
[0168] L' is a divalent linking group comprising 2 to 10
carbons,
[0169] Q.sup.a is *--O--* or *--N(H)--*,
[0170] Q.sup.b is *--O--* or *--N(H)--*, and
[0171] W' is a group comprising at least one carbon.
[0172] The starred bond of formula (A-2a) is linked to carbon 1 of
formula (A-2).
[0173] Non-limiting examples of Z' groups of formula (A-2a) include
those of Scheme 11.
##STR00028##
[0174] In an embodiment, Z' is
##STR00029##
[0175] Other more specific Z' groups of formula (A-2) include those
of formula (A-2b):
##STR00030##
wherein
[0176] a' represents the average number of repeat units and has a
value of 1 or more,
[0177] E.sup.1 is a monovalent end group independently selected
from the group consisting of hydrogen and groups comprising 1 to 10
carbons,
[0178] each J' is an independent monovalent radical selected from
the group consisting of hydrogen and groups comprising 1 to 10
carbons,
[0179] L' is a divalent linking group comprising 2 to 10
carbons,
[0180] Q.sup.a is *--O--* or *--N(H)--*,
[0181] Q.sup.b is *--O--* or *--N(H)--*, and
[0182] each R.sup.a is an independent monovalent radical selected
from the group consisting of hydrogen, methyl, and ethyl.
[0183] The starred bond of formula (A-2b) is linked to carbon 1 of
formula (A-2). The average degree of polymerization, a', of the Z'
polymer is preferably 1 to about 40, more preferably 1 to about 20.
R.sup.a is a first side chain of the Z' polymer, and J' is a second
side chain of the Z' polymer (labeled above).
[0184] Non-limiting examples of Z' groups of formula (A-2b) include
those of Scheme 12.
##STR00031##
[0185] In an embodiment, Q.sup.a and Q.sup.b are *--O--*, L' is
ethylene (*--CH.sub.2CH.sub.2--*), R.sup.a is hydrogen, and J' is
hydrogen of formula (A-2b). In another embodiment, Z' is
##STR00032##
wherein a' represents the average number of repeat units and has a
value of 1 or more.
[0186] Still other more specific Z' groups of formula (A-2) include
those of formula (A-2c):
##STR00033##
wherein
[0187] a' represents the average number of repeat units enclosed in
the parentheses and has a value of 1 or more,
[0188] u' is 0 or 1,
[0189] E.sup.1 is a monovalent end group independently selected
from the group consisting of hydrogen and groups comprising 1 to 10
carbons,
[0190] each J' is an independent monovalent radical selected from
the group consisting of hydrogen and groups comprising 1 to 10
carbons,
[0191] L.sup.a is a divalent linking group comprising 1 to 5
carbons,
[0192] each R.sup.a is an independent monovalent radical selected
from the group consisting of hydrogen, methyl, and ethyl, and
[0193] when a' is 1, L.sup.a, R.sup.a, J' and/or E' comprises a
carbonyl-containing functional group selected from the group
consisting of esters, carbonates, carbamates, and combinations
thereof.
[0194] The starred bond of formula (A-2c) is linked to carbon 1 of
formula (A-2). The average degree of polymerization, a', of the Z'
polymer is preferably 1 to about 40, more preferably 1 to about 20.
R.sup.a is a first side chain of the Z' polymer, and J' is a second
side chain of the Z' polymer.
[0195] Non-limiting examples of Z' groups of formula (A-2c) include
those of Scheme 13, wherein a' has an average value of 1 to about
40, and R.sup.f is a group comprising 1 to 10 carbons (e.g.,
methyl, ethyl, propyl, butyl, benzyl).
##STR00034## ##STR00035##
[0196] Non-limiting examples of second repeat units of formula
(A-2) include those of Scheme 13b, wherein a' has an average value
of 1 to about 40, and R.sup.f is a group comprising 1 to 10
carbons.
##STR00036## ##STR00037##
[0197] In an embodiment, the second repeat unit of the underlayer
random copolymer is selected from the group consisting of
##STR00038##
and combinations thereof, wherein a' represents degree of
polymerization and has an average value of about 1 to about 40 and
R.sup.f is a member of the group consisting of methyl, ethyl,
propyl, phenyl, and benzyl.
[0198] The random copolymer for the underlayer preferably comprises
a first repeat unit:second repeat unit mole ratio between 24:76 to
88:12.
[0199] The random copolymer for the underlayer further comprises a
third repeat unit of formula (A-3):
##STR00039##
wherein
[0200] R.sup.z is a monovalent radical selected from the group
consisting of H, methyl, ethyl, and trifluoromethyl
(*--CF.sub.3),
[0201] L'' is an independent divalent linking group comprising 1 to
10 carbons, and
[0202] K' is a monovalent electrophilic group capable of reacting
with a nucleophile to form a covalent bond.
[0203] Non-limiting L'' groups of formula (A-3) include ester,
amide, aryl, arylester and arylamide groups. Exemplary L'' groups
include those listed in Scheme 14 below, where the starred bond of
the carbonyl group or the aromatic ring (i.e., the left-most
starred bond in each structure) is linked to polymer backbone
carbon 1 of formula (A-3).
##STR00040## ##STR00041##
[0204] K' can comprise an electrophilic group selected from the
group consisting of active carboxylic ester groups (e.g.,
p-nitrophenyl ester, pentafluorophenyl ester), halide groups (e.g.,
chloride, bromide, and iodide), sulfonate esters (e.g.,
p-toluenesulfonates, mesylates), groups containing an epoxide
group, and the like. In an embodiment, K' comprises an epoxide
group.
[0205] More specific *-L''-K' groups include those of Scheme 15,
wherein the starred bond from the carbonyl group or the aromatic
ring is linked to carbon labeled 1 of formula (A-3).
##STR00042## ##STR00043##
[0206] In an embodiment, R.sup.z is methyl of formula (A-3) and
L''-K' is of formula (A-3) is
##STR00044##
[0207] More specific random copolymers for the underlayer have
structures in accordance with formula (A-4):
##STR00045##
wherein
[0208] each of subscripts x', y', and z' represents an average
number of repeat units enclosed in the respective parentheses and
independently has an average value greater than 1,
[0209] E' and E'' are monovalent end groups independently selected
from the group consisting of hydrogen, halides, and groups
comprising 1-10 carbons,
[0210] each K' is a monovalent radical capable of reacting with a
substrate surface to form a covalent bond,
[0211] L' is a divalent linking group comprising 2 to 10
carbons,
[0212] each L'' is an independent divalent linking group comprising
1 to 10 carbons,
[0213] Q.sup.a is *--O--* or *--N(H)--*,
[0214] Q.sup.b is *--O--* or *--N(H)--*,
[0215] each R.sup.b is an independent monovalent radical comprising
1 or more aromatic rings,
[0216] each of R.sup.x, R.sup.y, and R.sup.z is a monovalent
radical independently selected from the group consisting of
hydrogen, methyl, ethyl, and trifluoromethyl (*--CF.sub.3), and
[0217] W' is a group comprising at least one carbon.
[0218] In an embodiment, each R.sup.x is hydrogen, each R.sup.b is
phenyl, Q.sup.a is *--O--* and Q.sup.b is *--O--*. In another
embodiment, L' is ethylene (*--CH.sub.2CH.sub.2--*) and W' is
methyl.
[0219] Herein, formula A-4 can also be written as formula
(A-5):
##STR00046##
[0220] Other more specific random copolymers for the underlayer
have structures in accordance with formula (A-6):
##STR00047##
wherein
[0221] each of subscripts a', x', y', and z' represents an average
number of repeat units enclosed in the respective parentheses and
independently has an average value greater than 1,
[0222] E' and E'' are monovalent end groups independently selected
from the group consisting of hydrogen, halides, and groups
comprising 1-10 carbons,
[0223] E.sup.1 is a monovalent end group independently selected
from the group consisting of hydrogen and groups comprising 1 to 10
carbons,
[0224] each J' is an independent monovalent radical selected from
the group consisting of hydrogen and groups comprising 1 to 10
carbons,
[0225] each K' is a monovalent radical capable of reacting with a
substrate surface to form a covalent bond,
[0226] each L' is a divalent linking group comprising 2 to 10
carbons,
[0227] each L'' is an independent divalent linking group comprising
1 to 10 carbons,
[0228] Q.sup.a is *--O--* or *--N(H)--*,
[0229] Q.sup.b is *--O--* or *--N(H)--*,
[0230] each R.sup.a is an independent monovalent radical selected
from the group consisting of hydrogen, methyl, and ethyl,
[0231] each R.sup.b is an independent monovalent radical comprising
1 or more aromatic rings, and
[0232] each of R.sup.x, R.sup.y, and R.sup.z is a monovalent
radical independently selected from the group consisting of
hydrogen, methyl, ethyl, and trifluoromethyl (*--CF.sub.3).
[0233] In an embodiment, each R.sup.x is hydrogen, each R.sup.b is
phenyl, Q.sup.a is *--O--* and Q.sup.b is *--O--*, R.sup.a is
hydrogen, and J' is hydrogen. In another embodiment, L' is ethylene
(*--CH.sub.2CH.sub.2--*) and E.sup.1 is acetyl.
[0234] Formula A-6 can also be written as formula (A-7):
##STR00048##
[0235] Other more specific random copolymers for the underlayer
have a structure according to formula (A-8):
##STR00049##
wherein
[0236] each of x', y', and z' represents the average number of
respective repeat units enclosed in the respective parentheses, and
has an average value greater than 1,
[0237] a' represents the number of respective repeat units enclosed
in the parentheses, and has an average value of 1 or more,
[0238] E' and E'' are monovalent end groups independently selected
from the group consisting of hydrogen, halides, and groups
comprising 1-10 carbons, and
[0239] E.sup.1 is a monovalent end group independently selected
from the group consisting of hydrogen and groups comprising 1-10
carbons.
[0240] Preferably, x' is 20 to 80, y' is 1 to 20, z' is 1 to 5, and
a' is 1 to 40. In an embodiment, E.sup.1 is acetyl. In another
embodiment, a' is about 1 to about 10.
[0241] The structure of formula (A-8) can also be represented by
the formula (A-9):
##STR00050##
Preparation of Random Copolymers for Orientation Control Layers
[0242] A random copolymer for the underlayer can be prepared by
copolymerization of a mixture comprising a vinyl polymerizable
monomer comprising an aromatic ring, a second vinyl polymerizable
monomer comprising a pendant polycarbonate or polyestercarbonate
chain, and a third vinyl polymerizable monomer comprising an
electrophilic group capable of reacting with a nucleophile to
produce a covalent bond. This method is illustrated in Scheme 16
below using the monomers styrene (Sty), HEMA-PTMC, and glycidyl
methacrylate (GMA). Catalysts for the vinyl polymerization include
radical initiators (e.g., azobisisobutyronitrile (AIBN)).
##STR00051##
[0243] HEMA-PTMC can be prepared by an organocatalyzed ring opening
polymerization (ROP) of trimethylene carbonate (TMC) using
hydroxyethyl methacrylate (HEMA) as the polymerization initiator,
and endcapping the resulting polycarbonate with acetyl chloride, as
shown in Scheme 17 below. Catalysts for the ROP include organic
bases (e.g., 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU)) and
phosphate esters (e.g., diphenyl phosphate (DPP)).
##STR00052##
[0244] A second method of preparing the random copolymer for the
underlayer comprises growing a polycarbonate or polyestercarbonate
chain by ring opening polymerization from a nucleophilic site on a
side chain of a precursor random copolymer, as illustrated in
Scheme 18.
##STR00053##
In this example, the random copolymer of styrene (Sty),
hydroxyethyl methacrylate (HEMA), and glycidyl methacrylate GMA),
referred to as P(Sty-HEMA-GMA), is a macroinitiator for the ring
opening polymerization of TMC. Each nucleophilic hydroxy group of
the macroinitiator P(Sty-HEMA-GMA) serves as a potential initiating
site for ROP of TMC. The resulting polymer is a random graft
copolymer comprising a plurality of side chains bearing a
polycarbonate chain.
Block Copolymers for Self-Assembly
[0245] Block copolymer names can include a "-b-" or "-block-"
separating the abbreviated monomer names used to prepare the
polymer. The block copolymers for self-assembly can comprise two or
more blocks, preferably 2 to 4 blocks. At least one block comprises
a carbonate repeat unit. For example, the block copolymer can
comprise one polystyrene (PS) block and one polycarbonate (PC)
block joined by a linking group. As another example, the block
copolymer can comprise two PS blocks and one PC block joined by one
or two linking groups in the form of a linear polymer chain (i.e.,
not macrocyclic). As another example, the block copolymer can
comprise two PS blocks and two PC blocks joined by one to three
linking groups.
[0246] The following discussion is directed to diblock polymers
(A-B) but can be applied to triblock polymers and other block
polymer architectures (e.g., star polymers comprising 3 or more
polymer arms linked to a multi-valent core, mikto-arm star polymers
wherein or more arms comprise different repeat units compared to
the other arms).
[0247] A first block (block A) comprises a backbone comprising
repeating functionalized ethylenic units (e.g., as in a polystyrene
backbone). A second block (block B) comprises at least one
aliphatic carbonate repeat unit (i.e., comprising an aliphatic
carbonate group in the polymer backbone). The blocks are selected
so as to be substantially immiscible with each other. Additionally,
it is preferable that the first block and the second block of the
block polymer have the following solubility properties with respect
to a solvent mixture used to precipitate the block polymer: i) the
first block and the second block are substantially insoluble in a
first solvent of the solvent mixture, ii) the first block is
substantially insoluble in a second solvent of the solvent mixture,
and iii) the second block is soluble in a second solvent of the
solvent mixture. That is, the first solvent is a non-solvent for
the first block and the second block, the second solvent is a
non-solvent for the first block, and the second solvent is a
solvent for the second block.
[0248] The specific bulk structural units formed by self-assembly
of the block polymer are determined by the volume ratio of the
first block to the second block. The volume of a given block means
the volume occupied by the block, which depends on molecular mass
of the block. For example, when the volume ratio of the first block
A to the second block B is greater than about 80:20, the block
polymer can form an ordered array of spheres composed of the second
block in a matrix composed of the first block. When the volume
ratio of the first block to the second block is in a range greater
than about 80:20, the block copolymer can form an ordered array of
spheres of the second block in a matrix composed of the first
block. When the volume ratio of the first block to the second block
is in a range of about 80:20 to about 60:40, the block polymer can
form an ordered array of cylinders composed of the second block in
a matrix composed of the first block. When the volume ratio of the
first block to the second block is less than about 60:40 to about
40:60, the block polymer can form alternating lamellae (i.e., an
array of domains composed of the first block alternating with
domains composed of the second block). As an example, a
polystyrene-b-polymethylmethacrylate block copolymer (PS-b-PMMA)
comprising 20% or less by volume of the polystyrene (PS) block can
self-assemble to form PS spheres in a polymethylmethacrylate (PMMA)
matrix. As another example, a PS-b-PMMA block copolymer comprising
about 20% to 40% PS by volume can self-assemble to form PS
cylinders in a PMMA matrix. The volume ratio between the first
block and the second block can be adjusted by controlling the
average molecular weight of each block.
[0249] More specifically, the volume ratio of the first block to
the second block can be about 15:85 to about 85:15, based on the
average total volume of the block polymer macromolecule.
Preferably, for alternating lamellae formation, the volume ratio of
the first block to the second block can be about 40:60 to about
60:40, more preferably 45:55 to 55:45, and most preferably 48:52 to
52:48. For cylinder formation, the volume ratio of the first block
to second block can be about 74:26 to about 63:37, and more
preferably about 72:28 to about 65:35.
[0250] One of the blocks of the block polymer can be selectively
removed (e.g., by etching techniques) relative to the other block
to form structural features composed of the remaining block using
known dry and/or wet etching techniques. The structural features
can have any suitable form such as, for example, a line pattern, a
hole pattern, and/or other patterns.
[0251] The ROP polymeric initiator is preferably the product of a
vinyl polymerization. Vinyl polymerizable monomers include
styrenes, acrylates, methacrylates, substituted derivatives
thereof, and the like. The vinyl polymerizable monomers can be used
singularly or in combination to form the ROP polymeric initiator
using any suitable polymerization technique, including but not
limited to free radical polymerization, anionic polymerization,
cationic polymerization, atom transfer radical polymerization
(ATRP), nitroxide mediated polymerization (NMP), and/or reversible
addition-fragmentation chain transfer (RAFT) polymerization.
[0252] More specifically, the first block of the block copolymer
comprises a repeat unit of formula (B-1):
##STR00054##
wherein
[0253] R.sup.w is a monovalent radical selected from the group
consisting of H, methyl, ethyl, and trifluoromethyl (*--CF.sub.3),
and
[0254] R.sup.d is a monovalent radical comprising an aromatic ring
linked to carbon 1.
[0255] Non-limiting R.sup.d groups of formula (B-1) include
substituted and unsubstituted aryl groups. Exemplary R.sup.d groups
are listed in Scheme 19 below, where the starred bond of the
carbonyl group or the aromatic ring is linked to carbon labeled 1
of formula (B-1).
##STR00055## ##STR00056##
[0256] In an embodiment, R.sup.w of formula (B-1) is hydrogen, and
R.sup.d is phenyl. Repeat units of formula (B-1) can be present
singularly or in combination.
[0257] The first block can be a homopolymer of a repeat unit of
formula (B-1) or a random copolymer chain comprising a combination
of repeat units of formula (B-1) and/or a second repeat unit.
[0258] The second block of the diblock copolymer comprises at least
one aliphatic carbonate repeat unit of formula (B-2):
##STR00057##
wherein
[0259] R.sup.e is an independent monovalent radical selected from
the group consisting of hydrogen, methyl, and ethyl, and
[0260] B'' is an independent monovalent radical selected from the
group consisting of hydrogen and groups comprising 1 to 40
carbons.
[0261] In an embodiment, the polycarbonate block of the block
copolymer comprises an ester bearing carbonate repeat unit of
formula (B-3):
##STR00058##
[0262] wherein R.sup.g is monovalent hydrocarbon group comprising
1-20 carbons.
[0263] In an embodiment R.sup.g is a member selected from the group
consisting of methyl, ethyl, propyl, iso-propyl, n-butyl,
sec-butyl, tert-butyl, n-pentyl, neo-pentyl, iso-pentyl,
cyclopentyl, norbornyl, cyclohexyl, adamantyl, phenyl, and benzyl.
In another embodiment R.sup.g is methyl, ethyl, propyl, or
benzyl.
[0264] More specific block copolymers for self-assembly and
directed self-assembly have a structure according to formula (B-4),
wherein the square brackets represent separate blocks A and B of
the block copolymer:
##STR00059##
wherein
[0265] each subscript m' and n' represents the average number of
respective repeat units enclosed in parentheses, and independently
has an average value greater than 1,
[0266] E.sup.2 is a monovalent end group selected from the group
consisting of hydrogen and groups comprising 1-10 carbons,
[0267] G' is a monovalent end group selected from the group
consisting of hydrogen, halides, and groups comprising 1-10
carbons,
[0268] G'' is a divalent linking group comprising 1-20 carbons,
[0269] each B'' is an independent monovalent radical selected from
the group consisting of hydrogen and groups comprising 1 to 20
carbons,
[0270] each R.sup.d is an independent monovalent radical comprising
an aromatic ring,
[0271] each R.sup.w is an independent monovalent radical selected
from the group consisting of H, methyl, ethyl, and trifluoromethyl
(*--CF.sub.3),
[0272] each R.sup.e is an independent monovalent radical selected
from the group consisting of hydrogen, methyl, and ethyl, and
[0273] each X'' is an independent divalent radical selected from
the group consisting of *--O--*, *--S--*, *--N(H)--*, and
*--N(R'')--*, wherein R'' is a monovalent radical comprising 1 to 6
carbons.
[0274] In an embodiment, each B'' is hydrogen, each R.sup.e is
hydrogen, each R.sup.w is hydrogen, each R.sup.d is phenyl, E.sup.2
is acetyl, and X'' is *--O--*.
[0275] A more specific example of a block copolymer for
self-assembly has a structure according to formula (B-5):
##STR00060##
wherein
[0276] each subscript m' and n' represents the average number of
respective repeat units enclosed in parentheses, and independently
has an average value greater than 1,
[0277] each R.sup.e is an independent monovalent radical selected
from the group consisting of hydrogen, methyl, and ethyl, and
[0278] each B'' is an independent monovalent radical selected from
the group consisting of hydrogen and groups comprising 1 to 20
carbons.
[0279] In an embodiment, each R.sup.e is hydrogen and each B'' is
hydrogen. In another embodiment, each R.sup.e is methyl and each
B'' is *--CO.sub.2Me, *--CO.sub.2Et, *--CO.sub.2Pr (propyl ester),
or *--CO.sub.2Bn (benzyl ester).
Preparation of the Block Copolymers for Self-Assembly
[0280] The block copolymers for self-assembly are preferably
prepared by ring opening polymerization of a cyclic carbonate
monomer using a polymeric initiator having a backbone derived from
a vinyl polymerizable monomer. For diblock and triblock copolymer
formation, the polymeric initiator can comprise, respectively, 1
and 2 nucleophilic groups (e.g., *--OH, *--NH.sub.2) capable of
initiating the ROP of the cyclic carbonyl monomer. The ROP reaction
mixture comprises a cyclic carbonyl monomer, a ROP catalyst, a
solvent, and the polymeric initiator. The ROP catalyst is
preferably an acid catalyst (e.g., diphenyl phosphate).
[0281] The following methods of forming a diblock copolymer can be
applied to the preparations of triblock polymers and other block
polymer architectures. The methods provide a block copolymer that
is substantially free of any polycarbonate homopolymer and/or
polycarbonate random copolymer.
Method 1
[0282] This method utilizes a solvent mixture to fractionate an
initial block polymer formed when the ROP is conducted for a
duration time corresponding to about 50% to 100%, more particularly
about 85% to 100% consumption of a cyclic carbonate monomer. For a
given set of reaction conditions (e.g., temperature, solvent, type
of atmosphere, relative molar amounts, and other reaction
parameters), the consumption of the cyclic carbonate monomer can be
monitored using any suitable analytical technique (e.g., proton
nuclear magnetic resonance (.sup.1H NMR)).
[0283] The ROP produces an initial block polymer containing a
living end group, which is a nucleophilic group capable of
undergoing further chain growth and/or initiating a ROP of a
different cyclic carbonyl monomer. Preferably, the active living
end group is deactivated by addition of an endcapping agent to the
reaction mixture, thereby terminating the polymerization and
forming an endcapped initial block polymer containing a protected
nucleophilic end group. The endcapped initial block polymer is not
capable of initiating a ROP. As an example, a polycarbonate formed
by ROP of a cyclic carbonate monomer has a living end containing a
nucleophilic hydroxy group, which can be deactivated by addition of
a suitable acylating agent (e.g., acetic anhydride) to form a
protected hydroxy group (e.g., as an acetyl ester).
[0284] The isolated initial block polymer or the endcapped initial
block polymer ("crude block polymer") can contain polymeric
impurities derived from the cyclic carbonyl monomer that are not
covalently linked to the polymeric initiator. Polymeric impurities
can include polycarbonate homopolymer initiated by traces of water,
and/or cyclic polycarbonate formed by backbiting of the living
hydroxy end group on the polycarbonate backbone of the initial
block polymer. These impurities can adversely affect the
self-assembly properties of the initial block polymer.
[0285] The polymeric impurities can be removed by the following
fractionation process. A first solution is prepared containing the
initial block polymer dissolved in a minimal amount of a solvent
(e.g., THF) capable of dissolving each block of the block polymer.
The first solution contains the initial block polymer at a
concentration of about 20 wt % based on total weight of the first
solution. The first solution is then added to an excess amount
(about 200 to 400 times the amount of crude polymer by weight) of a
solvent mixture comprising a first solvent and a second solvent in
a volume ratio of about 40:60 to about 60:40, respectively, wherein
the first solvent is a non-solvent for the first block and the
second block, and the second solvent is a non-solvent for the first
block and a solvent for the second block. In an embodiment, the
first solvent is MeOH and the second solvent is acetonitrile. The
solvent mixture selectively dissolves the polymeric impurities,
allowing the final block polymer to precipitate as a solid that can
be substantially free of the polymeric impurities. The
fractionation procedure can be repeated one or more times as
necessary to form the block polymer used for self-assembly
applications.
Method 2
[0286] In a second method, a trial ROP is performed using the given
set of reaction conditions that includes the polymeric initiator.
The amount of consumed cyclic carbonyl monomer is monitored (e.g.,
% consumption) as a function of ROP duration time t as in Method 1,
allowing the ROP to proceed to 85% to 100% consumption of the
cyclic carbonyl monomer. A graph is plotted of the percent
consumption of the cyclic carbonate as a function of ROP duration
time t in minutes.
[0287] From the scatter plot of the collected data points, a second
order polynomial function F(t) (i.e., a trendline) can be fitted to
the plotted points, wherein F(t) expresses the amount of consumed
cyclic carbonyl monomer as a function of ROP duration time t. The
R.sup.2 (R-squared) coefficient for F(t) preferably has a value of
about 0.85 to 1.0, more preferably 0.9 to 1.0.
[0288] Using the expression of F(t), a time t.sub.1 corresponding
to 50% consumption of the cyclic carbonyl monomer can be
calculated.
[0289] The first derivative of F(t), denoted F'(t), is then
calculated for each measurement time t.
[0290] The value of F'(t) at 50% cyclic monomer conversion is then
determined. Using the value of F'(t.sub.1) at 50% cyclic monomer
conversion, ROP duration times t.sub.2 and t.sub.3 are determined
corresponding to a slope change of -10% and -20% relative to the
slope at 50% consumption of cyclic carbonyl monomer.
[0291] The ROP is then conducted using the given reaction
conditions, stopping the ROP at duration time (t'), wherein
t.sub.1.ltoreq.t'.ltoreq.t.sub.3, and more preferably
t.sub.2.ltoreq.t'.ltoreq.t.sub.3. Using these modified reaction
conditions, a block polymer for self-assembly can be obtained
directly that is free of, or substantially free of, polymer
impurities that do not comprise a block derived from the polymeric
initiator. Optionally, the block polymer can be further treated
with the solvent mixture as described above under Method 1 to
remove any remaining polymeric impurities.
Method 3
[0292] In Method 3, the mathematical expression for F'(t) is
obtained as described above under Method 2. The value of F'(t) is
then calculated for each ROP duration time t. Using the values of
F'(t), the change in F'(t) between adjacent ROP duration times is
calculated for each ROP duration time greater than 0. For example,
the change in F'(t) at duration time t.sub.n, denoted as
.DELTA.F'(t.sub.n), is equal to F'(t.sub.n)-F'(t.sub.n-1), where n
is a positive integer and t.sub.a>0.
[0293] A second order polynomial trendline D(t) is obtained for a
scatter plot of .DELTA.F'(t) as a function of t having the shape of
an inverted parabola. D(t) has a first derivative D'(t) equal to
zero at some ROP duration time t''>0 that is less than the
duration time corresponding to 100% consumption of the cyclic
carbonyl monomer.
[0294] The ROP is repeated using the given reaction conditions,
terminating the ROP at 0.8t'' to about t''. The resulting final
block polymer can be free of, or substantially free of, polymer
impurities that do not comprise a block derived from the polymeric
initiator. Optionally, the block polymer can be further treated
with the solvent mixture as described above under Method 1 to
remove any polymeric impurities present.
Cyclic Carbonyl Monomers
[0295] Exemplary cyclic carbonyl monomers include cyclic carbonate
compounds of Scheme 20, which can be used, for example, to form a
polycarbonate block of the initial block polymer.
##STR00061## ##STR00062## ##STR00063##
[0296] Other cyclic carbonyl monomers include cyclic esters
(lactones), such as the compounds of Scheme 21.
##STR00064## ##STR00065##
[0297] The above cyclic carbonyl monomers can be purified by
recrystallization from a solvent such as ethyl acetate or by other
known methods of purification, with particular attention being paid
to removing as much water as possible from the monomer.
ROP Initiators for the Block Copolymers
[0298] Initiators for ring opening polymerizations generally
include nucleophilic groups such as alcohols, primary amines,
secondary amines, and thiols. Herein, the ROP initiator for the
block copolymer is a polymeric initiator comprising a polymer
backbone derived from a polymerizable vinyl monomer (styrenes,
methacrylates, acrylates, methacrylamides, acrylamides, vinyl
esters). An exemplary polymeric initiator is the functionalized
polystyrene initiator PS--OH shown below.
##STR00066##
[0299] The polymeric initiator preferably comprises one or two
nucleophilic hydroxy groups for initiating a ROP and forming
diblock, triblock, and tetrablock copolymers, respectively. In an
embodiment, the polymeric initiator comprises two nucleophilic
initiating groups, and the block copolymer formed by the ROP is a
mikto-armed star polymer comprising 4 arms. A mikto-arm star
polymer has a chemical structure comprising 3 or more polymer arms
linked to a core of the star polymer, and at least one arm has a
different polymer composition compared to another of the arms.
[0300] The number average molecular weight of the polymeric
initiator can be from 1000 to 1,000,000, more specifically 1000 to
100,000, and even more specifically, 1000 to 50,000.
[0301] An exemplary non-limiting reaction to form a block copolymer
is illustrated in Scheme 22 using another macroinitiator
AZPS-OH.
##STR00067##
Ring Opening Polymerizations (ROP)
[0302] The following description of methods, conditions and
materials for ring opening polymerizations is applicable to the
preparation of the random copolymer for orientation control
material and/or the block polymer for self-assembly.
[0303] The ring-opening polymerization can be performed at a
temperature that is about ambient temperature or higher, 15.degree.
C. to 100.degree. C., and more specifically ambient temperature.
Reaction times vary with solvent, temperature, agitation rate,
pressure, and equipment, but in general the polymerizations are
complete within about 1 hour to about 48 hours.
[0304] The ROP reaction can be performed with or without the use of
a solvent, preferably with a solvent. Exemplary solvents include
dichloromethane, chloroform, benzene, toluene, xylene,
chlorobenzene, dichlorobenzene, benzotrifluoride, petroleum ether,
acetonitrile, pentane, hexane, heptane, 2,2,4-trimethylpentane,
cyclohexane, diethyl ether, t-butyl methyl ether, diisopropyl
ether, dioxane, tetrahydrofuran, or a combination comprising one of
the foregoing solvents. When a solvent is present, a suitable
monomer concentration is about 0.1 to 5 moles per liter, and more
particularly about 0.2 to 4 moles per liter.
[0305] Whether performed in solution or in bulk, the ROP
polymerizations are conducted using an inert (i.e., dry)
atmosphere, such as nitrogen or argon, and at a pressure of from
100 to 500 MPa (1 to 5 atm), more typically at a pressure of 100 to
200 MPa (1 to 2 atm). At the completion of the reaction, the
solvent can be removed using reduced pressure.
ROP Catalysts
[0306] No restriction is placed on the ROP catalyst. Less preferred
catalysts for the ROP polymerization include metal oxides such as
tetramethoxy zirconium, tetra-iso-propoxy zirconium,
tetra-iso-butoxy zirconium, tetra-n-butoxy zirconium,
tetra-t-butoxy zirconium, triethoxy aluminum, tri-n-propoxy
aluminum, tri-iso-propoxy aluminum, tri-n-butoxy aluminum,
tri-iso-butoxy aluminum, tri-sec-butoxy aluminum,
mono-sec-butoxy-di-iso-propoxy aluminum, ethyl acetoacetate
aluminum diisopropylate, aluminum tris(ethyl acetoacetate),
tetraethoxy titanium, tetra-iso-propoxy titanium, tetra-n-propoxy
titanium, tetra-n-butoxy titanium, tetra-sec-butoxy titanium,
tetra-t-butoxy titanium, tri-iso-propoxy gallium, tri-iso-propoxy
antimony, tri-iso-butoxy antimony, trimethoxy boron, triethoxy
boron, tri-iso-propoxy boron, tri-n-propoxy boron, tri-iso-butoxy
boron, tri-n-butoxy boron, tri-sec-butoxy boron, tri-t-butoxy
boron, tri-iso-propoxy gallium, tetramethoxy germanium, tetraethoxy
germanium, tetra-iso-propoxy germanium, tetra-n-propoxy germanium,
tetra-iso-butoxy germanium, tetra-n-butoxy germanium,
tetra-sec-butoxy germanium and tetra-t-butoxy germanium;
halogenated compounds such as antimony pentachloride, zinc
chloride, lithium bromide, tin(IV) chloride, cadmium chloride and
boron trifluoride diethyl ether; alkyl aluminum such as trimethyl
aluminum, triethyl aluminum, diethyl aluminum chloride, ethyl
aluminum dichloride and tri-iso-butyl aluminum; alkyl zinc such as
dimethyl zinc, diethyl zinc and diisopropyl zinc; tertiary amines
such as triallylamine, triethylamine, tri-n-octylamine and
benzyldimethylamine; heteropolyacids such as phosphotungstic acid,
phosphomolybdic acid, silicotungstic acid and alkali metal salts
thereof; zirconium compounds such as zirconium acid chloride,
zirconium octanoate, zirconium stearate and zirconium nitrate. More
particularly, the zirconium catalyst can be zirconium octanoate,
tetraalkoxy zirconium or a trialkoxy aluminum compound.
[0307] Preferred ROP catalysts are organocatalysts whose chemical
formulas contain no metal. Base organocatalysts for ROPs of cyclic
carbonyl monomers include tertiary amines such as triallylamine,
triethylamine, tri-n-octylamine and benzyldimethylamine
4-dimethylaminopyridine, phosphines, N-heterocyclic carbenes (NHC),
bifunctional aminothioureas, phosphazenes, amidines, and
guanidines.
[0308] A thiourea ROP organocatalyst is
N-(3,5-trifluoromethyl)phenyl-N'-cyclohexyl-thiourea (TU):
##STR00068##
[0309] Other ROP organocatalysts comprise at least one
1,1,1,3,3,3-hexafluoropropan-2-ol-2-yl (HFA) group. Singly-donating
hydrogen bond catalysts have the formula (C-1):
R.sup.2--C(CF.sub.3).sub.2OH (C-1),
wherein R.sup.2 represents a hydrogen or a monovalent radical
having from 1 to 20 carbons, for example an alkyl group,
substituted alkyl group, cycloalkyl group, substituted cycloalkyl
group, heterocycloalkyl group, substituted heterocycloalkyl group,
aryl group, substituted aryl group, or a combination thereof.
Exemplary singly-donating hydrogen bonding catalysts are listed in
Scheme 23.
##STR00069##
[0310] Doubly-donating hydrogen bonding catalysts have two HFA
groups, represented by the general formula (C-2):
##STR00070##
wherein R.sup.3 is a divalent radical bridging group containing
from 1 to 20 carbons, such as an alkylene group, a substituted
alkylene group, a cycloalkylene group, substituted cycloalkylene
group, a heterocycloalkylene group, substituted heterocycloalkylene
group, an arylene group, a substituted arylene group, or a
combination thereof. Representative double hydrogen bonding
catalysts of formula (C-2) include those listed in Scheme 24. In a
specific embodiment, R.sup.2 is an arylene or substituted arylene
group, and the HFA groups occupy positions meta to each other on
the aromatic ring.
##STR00071##
[0311] Preferred hydrogen bonding catalysts include 4-HFA-St,
4-HFA-Tol, HFTB, NFTB, HPIP, 3,5-HFA-MA, 3,5-HFA-St, 1,3-HFAB,
1,4-HFAB, and combinations thereof.
[0312] The HFA catalyst can be bound to a support. In one
embodiment, the support comprises a polymer, a crosslinked polymer
bead, an inorganic particle, or a metallic particle. HFA-containing
polymers can be formed by known methods including direct
polymerization of an HFA-containing monomer (for example, the
methacrylate monomer 3,5-HFA-MA or the styryl monomer 3,5-HFA-St).
Functional groups in HFA-containing monomers that can undergo
direct polymerization (or polymerization with a comonomer) include
acrylate, methacrylate, alpha, alpha, alpha-trifluoromethacrylate,
alpha-halomethacrylate, acrylamido, methacrylamido, norbornene,
vinyl, vinyl ether, and other groups known in the art. Examples of
linking groups include C.sub.1-C.sub.12 alkyl groups,
C.sub.1-C.sub.12 heteroalkyl groups, ether groups, thioether
groups, amino groups, ester groups, amide groups, and combinations
thereof. Also contemplated are catalysts comprising charged
HFA-containing groups bound by ionic association to oppositely
charged sites on a polymer or a support surface.
[0313] Most preferably, the ROP catalyst is an acid organocatalyst
(e.g., diphenylphosphate (DPP), triflic acid, and the like).
[0314] The ROP reaction mixture comprises at least one ROP catalyst
and, when appropriate, several ROP catalysts together. The ROP
catalyst is added in a proportion of 1/20 to 1/40,000 moles
relative to the cyclic carbonyl monomers, and preferably in a
proportion of 1/1,000 to 1/20,000 moles relative to the cyclic
carbonyl monomers.
ROP Accelerators.
[0315] The ROP polymerization can be conducted in the presence of
an optional accelerator, in particular a nitrogen base. Exemplary
nitrogen base accelerators are listed below and include pyridine
(Py), N,N-dimethylaminocyclohexane (Me.sub.2NCy),
4-N,N-dimethylaminopyridine (DMAP), trans
1,2-bis(dimethylamino)cyclohexane (TMCHD),
1,8-diazabicyclo[5.4.0]undec-7-ene (DBU),
1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD),
7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), (-)-sparteine,
(Sp) 1,3-bis(2-propyl)-4,5-dimethylimidazol-2-ylidene (Im-1),
1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (Im-2),
1,3-bis(2,6-di-i-propylphenyl(imidazol-2-ylidene (Im-3),
1,3-bis(1-adamantyl)imidazol-2-ylidene (Im-4),
1,3-di-i-propylimidazol-2-ylidene (Im-5),
1,3-di-t-butylimidazol-2-ylidene (Im-6),
1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene
(Im-7),
1,3-bis(2,6-di-i-propylphenyl)-4,5-dihydroimidazol-2-ylidene,
1,3-bis(2,6-di-i-propylphenyl)-4,5-dihydroimidazol-2-ylidene (Im-8)
or a combination thereof, shown in Scheme 25.
##STR00072## ##STR00073## ##STR00074##
[0316] In an embodiment, the accelerator has two or three
nitrogens, each capable of participating as a Lewis base, as for
example in the structure (-)-sparteine. Stronger bases generally
improve the polymerization rate.
[0317] The catalyst and the accelerator can be the same material.
For example, some ring opening polymerizations can be conducted
using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) alone, with no
another catalyst or accelerator present.
[0318] The catalyst is preferably present in an amount of about 0.2
to 20 mol %, 0.5 to 10 mol %, 1 to 5 mol %, or 1 to 2.5 mol %,
based on total moles of cyclic carbonyl monomer.
[0319] The nitrogen base accelerator, when used, is preferably
present in an amount of 0.1 to 5.0 mol %, 0.1 to 2.5 mol %, 0.1 to
1.0 mol %, or 0.2 to 0.5 mol %, based on total moles of cyclic
carbonyl monomer. As stated above, in some instances the catalyst
and the nitrogen base accelerator can be the same compound,
depending on the particular cyclic carbonyl monomer.
[0320] The amount of initiator is calculated based on the
equivalent molecular weight per nucleophilic initiator group in the
dinucleophilic initiator. The initiator groups are preferably
present in an amount of 0.001 to 10.0 mol %, 0.1 to 2.5 mol %, 0.1
to 1.0 mol %, and 0.2 to 0.5 mol %, based on total moles of cyclic
carbonyl monomer. For example, if the molecular weight of the
initiator is 100 g/mole and the initiator has 2 hydroxyl groups,
the equivalent molecular weight per hydroxyl group is 50 g/mole. If
the polymerization calls for 5 mol % hydroxyl groups per mole of
monomer, the amount of initiator is 0.05.times.50=2.5 g per mole of
monomer.
[0321] In a specific embodiment, the catalyst is present in an
amount of about 0.2 to 20 mol %, the nitrogen base accelerator is
present in an amount of 0.1 to 5.0 mol %, and the nucleophilic
initiator groups of the initiator are present in an amount of 0.1
to 5.0 mol % based on the equivalent molecular weight per
nucleophilic initiator group of the initiator.
[0322] The catalysts can be removed by selective precipitation or
in the case of the solid supported catalysts, simply by filtration.
The block polymer can comprise residual catalyst in an amount of 0
wt % (weight percent) or more, based on total weight of the block
copolymer and the residual catalyst. The amount of residual
catalyst can also be less than 20 wt %, less than 15 wt %, less
than 10 wt %, less than 5 wt %, less than 1 wt %, or most
specifically less than 0.5 wt % based on the total weight of the
block copolymer and the residual catalyst.
Endcap Agents
[0323] An endcap agent can prevent further chain growth and
stabilize the reactive end groups from unwanted side reactions,
such as chain scission. Endcap agents include, for example,
compounds for converting terminal hydroxyl groups to esters, such
as acid anhydrides (e.g., acetic anhydride), acid chlorides (acetyl
chloride), and/or active esters (e.g., p-nitrophenyl esters). Other
endcap agents include alkyl and aryl isocyanates, which form
carbamates (urethanes) with terminal hydroxy groups. Other endcap
agents include alkylating agents capable of forming alkyl ethers,
aromatic ethers including benzyl ethers, silyl ethers, acetals,
ketals, and the like. Still other endcap agents include
perhalogenated (e.g., perfluorinated) derivatives of any of the
foregoing endcap agents. In an embodiment, the endcap agent is
acetic anhydride, which converts reactive hydroxy end groups to
acetate ester groups.
Average Molecular Weight.
[0324] The block polymer used for self-assembly preferably has a
number average molecular weight Mn as determined by size exclusion
chromatography of at least 1500 g/mol, more specifically 1500 g/mol
to 1,000,000 g/mol, 4000 g/mol to 150000 g/mol, or 4000 g/mol to
50000 g/mol. In an embodiment, the final block polymer has a number
average molecular weight Mn of 8,000 to 40,000 g/mole.
[0325] The block polymer used for self-assembly also preferably has
a narrow polydispersity index (PDI), generally from 1.01 to 2.0,
more particularly 1.01 to 1.30, and even more particularly 1.01 to
1.25.
Layered Structures
[0326] The substrate is a layered structure, which can comprise an
orientation control layer (underlayer). The orientation control
layer of the substrate comprises a covalently bound form of the
above-described random copolymer of the underlayer linked to the
surface of the underlying layer of the substrate. The covalently
bound random copolymer comprises a divalent first repeat unit of
formula (A-1), a divalent second repeat unit of formula (A-2), and
a trivalent third repeat unit of formula (A-8):
##STR00075##
wherein
[0327] R.sup.z is a monovalent radical selected from the group
consisting of H, methyl, ethyl, and trifluoromethyl
(*--CF.sub.3),
[0328] L'' is an independent divalent linking group comprising 1 to
10 carbons, and
[0329] K'' is a divalent linking group, and the starred bond of K''
is covalently linked to a surface group of the substrate, and
[0330] the first repeat unit, second repeat unit, and third repeat
are randomly covalently bound in the chemical structure of the
random copolymer.
[0331] An orientation control layer can be formed by disposing on a
first layered structure (first substrate) a solution containing an
above-described random copolymer for the underlayer, a solvent, and
optionally a member of the group consisting of thermal acid
generators (TAGs), photo-acid generators (PAGs), catalysts, and
combinations thereof, and removing the solvent (e.g., by a thermal
bake and/or exposure to actinic light), thereby forming a second
layer structure (second substrate) comprising an top orientation
control layer. The orientation control layer comprises a covalently
bound form of the random copolymer linked to an underlying layer of
the first layered structure. Optionally, the second layered
structure can be rinsed with a solvent to remove any un-bound
random copolymer. The orientation control layer is neutral wetting
with respect to the high-chi block copolymer for self-assembly,
which comprises a polycarbonate block. The thermal bake can be
performed at a temperature of about 100.degree. C. to about
250.degree. C. for about 1 second to about 24 hours, preferably
about 120.degree. C. to about 250.degree. C. for 1 minute to 5
minutes.
[0332] Also disclosed are compositions for preparing the SA layers.
The compositions comprise a solvent, a high-chi block copolymer,
and an SAP. The block copolymer and the SAP are dissolved in the
solvent. The compositions are suitable for forming a film layer (SA
layer) comprising the block copolymer. The film layer is preferably
disposed on an orientation control layer (underlayer). The film
layer has a top surface in contact with the atmosphere. The film
layer comprises the block copolymer and the polymer additive in
non-covalent association.
[0333] The following schematic diagrams illustrate methods of
forming substrates comprising underlayers for orientation control
and their use in forming perpendicularly oriented lamellar domain
patterns with high-chi block copolymers.
[0334] FIGS. 1A to 1F are cross-sectional layer diagrams
illustrating a process of directed self-assembly of an SA layer
comprising a high-chi block copolymer and SAP additive, which
produces perpendicularly oriented lamellar domains without
employing a lithographically prepared topographic or chemical
pre-pattern. It should be understood that the layers and features
are not drawn to scale.
[0335] Layered of FIG. 1A comprises substrate 11 having substrate
surface 12. Substrate 11 can comprise one or more layers (not
shown). A solution comprising a disclosed random copolymer for
orientation control, which is dissolved in a suitable solvent, is
applied to substrate surface 12 (e.g., by spin coating), followed
by removal of any solvent, resulting in layered structure 20 (FIG.
1B), also referred to as a "modified substrate". Layered structure
20 comprises underlayer 21 for orientation control, which comprises
the random copolymer bound by at least one covalent bond to
substrate 11. Optionally, layered structure 20 can be rinsed with a
solvent to remove any un-bound random copolymer.
[0336] Underlayer 21 has underlayer surface 22. A solution
comprising a disclosed high-chi block copolymer comprising a
polycarbonate block for self-assembly (SA material), a disclosed
SAP, and a solvent is applied to underlayer surface 22 using any
suitable technique (e.g., spin coating). Removal of the solvent
followed by an optional post-application bake (PAB) (e.g.,
115.degree. C. for 1 minute) produces layered structure 30 (FIG.
1C). Layered structure 30 comprises SA layer 31 comprising the
block copolymer and SAP. SA layer 31 is disposed on underlayer
surface 22. SA layer 31 is then subjected to conditions effective
in inducing the block copolymer to self-assemble (e.g., annealing
layered structure 30 at a temperature of 120.degree. C. to
250.degree. C. for about 1 minute to about 24 hours), thereby
forming layered structure 40 (FIG. 1D). Layered structure 40
comprises perpendicularly oriented lamellar domain pattern 41 of
self-assembled block copolymer disposed on underlayer surface 22.
Domain pattern 41 comprises first lamellar domain 43 comprising a
first block of the block copolymer (e.g., block A, polystyrene) and
second lamellar domain 42 comprising a polycarbonate block (e.g.,
block B) of the high-chi block copolymer. Second lamellar domain 42
has a higher concentration of SAP than first lamellar domain 43
(not shown). In this instance the lamellae of each of the domains
formed by the block copolymer are in contact with atmosphere
interface 44 and underlayer surface 22. Self-assembly of SA layer
is conducted with the top surface of SA layer 31 in contact
atmosphere interface 44.
[0337] One of the domains can be selectively removed (e.g., etched)
or modified in the presence of the other domain. As an example, dry
etching using a suitable gas (O.sub.2) or wet/chemical etching
technique can be used to selectively etch second lamellar domain
42. As another example, first lamellar domain 43 (polystyrene
block) can be selectively etched by modifying second lamellar
domain 42 by i) sequential infiltration synthesis (SIS) to infuse
metal oxide precursors or ii) by solution infiltration of second
lamellar domain 42 with metal salts, followed by ion-etching of
first lamellar domain 43. Selective removal of one of the domains
can also remove underlying orientation control material of the
underlayer (not shown).
[0338] Selective removal of one of the domains produces layered
structure 50 (FIG. 1E) comprising etched domain pattern 51. In this
example, etched domain pattern 51 comprises first lamellar domain
43 disposed on underlayer surface 22, and openings 52 (shown).
Alternatively, first lamellar domain 43 can be selectively removed
leaving second lamellar domain 42 (not shown). Lamellae of first
lamellar domain 43 can have different dimensions after removing
second lamellar domain 42 compared to their dimensions before the
selective removal. Openings 52 can have a width w'' of about 0.5Lo,
(e.g., for low-chi SA materials, w'' is about 10 nm to about 100
nm). The selective removal process may be carried out by a thermal
bake (for thermally decomposable materials), a reactive ion etch
process, dissolution in a selective solvent, or a combination
thereof. A chemical modification can be accomplished by a variety
of known methods. For example, domains can be selectively reacted
with silanes or silyl chlorides to introduce silicon content into a
domain and thereby increase its plasma etch resistance.
Alternatively, chemical agents can be used to bind or chemically
couple to functional groups that are exclusively located in one
type of self-assembled domain, to effect, for example, increased
solubility property differences that can advantageously be used to
selectively remove one domain in the presence of the other
domain.
[0339] Lastly, etched domain pattern 51 can be transferred to
substrate 11, thereby forming layered structure 60 (FIG. 1F)
comprising transfer pattern 61. Patterned region 61 can be a
pattern of lines, holes, pits, and/or a chemically altered state of
the underlayer 21 and/or substrate 11, which are represented by
areas 62. Patterned region 61 can extend into one or more layers,
including the underlayer 21 and/or the substrate 11 (shown). The
pattern transfer process can further comprise removal of first
lamellar domain 43 (not shown).
[0340] FIGS. 2A to 2E are cross-sectional layer diagrams
illustrating a lithographic process utilizing a pre-formed
topographic pre-pattern with the disclosed underlayer and SA layer
comprising a high-chi block copolymer and SAP. Layered structure
100 (FIG. 2A) comprises substrate 110 comprising underlayer 102
disposed on surface 103 of bottom layer 101 (e.g., silicon wafer).
Topographic pre-pattern 104 is disposed on underlayer surface 105.
Underlayer 102 comprises a form of the disclosed random copolymer
bound by at least one covalent bond to surface 103. Bottom layer
101 can comprise one or more sub-layers (not shown). Topographic
pre-pattern 104 comprises features 106 (e.g., resist features).
Features 106 have sidewalls 107 of height h', and top surfaces 108
of width w'. Features 106 are separated by trenches 109 (recessed
areas) which include bottom surfaces 112 comprising material of
underlayer 102 in contact with an atmosphere. Pre-pattern 104 can
be formed by any suitable lithographic technique. Features 106 can
comprise any suitable material 111 for directing self-assembly. For
example, features 106 can comprise a resist material, which can be
a positive and/or negative tone resist material.
[0341] In the present invention, the topography of pre-pattern 104
is not essential for orientation control of the self-assembled
lamellar domains of the high-chi block copolymer. The SA layer is
allocated substantially or wholly within the trench areas 109 of
features 106. Height h' of features 106 is typically greater than
or comparable to the thickness of the SA layer. Bottom surface 112
is neutral wetting to the SA material (block copolymer), whereas
the air interface is not neutral to the SA material. In this
example, sidewalls 107 can be neutral wetting or non-neutral
wetting to the block copolymer, with the proviso that the surface
properties of the sidewalls do not adversely affect self-assembly
and orientation of the domains formed.
[0342] A coating mixture comprising the SA material (a high-chi
block copolymer) and SAP dissolved in a solvent is applied to
topographic pre-pattern 104 using any suitable technique (e.g.,
spin coating), thereby allocating the mixture substantially or
exclusively in trench areas 109. Topographic pre-pattern 104 is
insoluble in or substantially insoluble in the solvent used to
prepare the mixture. Removal of the solvent from the applied
coating mixture provides layered structure 120 comprising SA layer
121 (FIG. 2B). SA layer 121 comprises regions 122 comprising the SA
material (high-chi block copolymer) and SAP. SA layer 121 is
disposed on bottom surfaces 112 of trench areas 109.
[0343] Self-assembly of the high-chi block copolymer produces
layered structure 130 (FIG. 2C) comprising perpendicularly oriented
lamellar domain pattern 131. Self-assembly can be spontaneous
and/or assisted by a thermally treating (annealing) layer 121.
Domain pattern 131 comprises first lamellar domain 133 (e.g., PS)
having a width of v'', and second lamellar domain 132 (e.g.,
polycarbonate) having a width w'' and disposed on bottom surface
112 of trench areas 109. Atmosphere interface 134 is indicated by
the arrow. In this example, sidewalls 107 of features 106 have
preferential affinity for first lamellar domains 133. Therefore,
first lamellar domain 133 are positioned in contact with sidewalls
107. First lamellar domain 133 in contact with sidewalls 107 can
have a width of about 0.5v''. In an embodiment, v'' and w'' are
about equal to 0.5Lo.
[0344] One of the domains, for example second lamellar domain 132
(e.g., polycarbonate block), can be selectively removed (e.g.,
ion-etched) or modified in the presence of the first lamellar
domain 133 (e.g., PS block) to generate topographical or chemical
contrast. Selective removal of one of the domains can also remove
underlying orientation control material (not shown), producing
layered structure 140 comprising etched domain pattern 141 (FIG.
2D). Etched domain pattern 141 comprises first lamellar domain 133
disposed on underlayer surface 112, openings 142, and features 106.
Openings 142 can have a width w'' of about 0.5Lo (e.g., for a
high-chi block copolymer, w'' can be about 2 nm to about 10 nm).
The selective removal process may be carried out by a thermal bake
(for thermally decomposable materials), a reactive ion etch
process, dissolution in a selective solvent, or a combination
thereof. A chemical modification may be accomplished by a variety
of known methods as discussed above. The selective removal process
can further remove features 106 (not shown).
[0345] Finally, etched domain pattern 141 can be transferred to
underlayer 102 and/or bottom layer 101, thereby forming layered
structure 150 comprising patterned region 151 (FIG. 2E). Patterned
region 151 can be a pattern of lines, holes, pits, and/or a
chemically altered state of the substrate material represented by
altered areas 152. Patterned region 151 can extend into one or more
layers of bottom layer 101. The pattern transfer can be
accomplished, for example, by using a reactive ion etch process.
Features 106 and first lamellar domain 133 can be removed
concomitantly or subsequently to formation of altered areas 152.
The height of etched domain pattern 141 after the transfer can be
less than the height of etched domain pattern 141 before the
transfer.
[0346] The substrate, and more particularly the surface of the
substrate, can comprise inorganic or organic materials such as
metals, carbon, or polymers. More particularly, the substrate can
comprise a semiconducting material including, for example, Si,
SiGe, SiGeC, SiC, Ge alloys, GaAs, InAs, InP, silicon nitride,
titanium nitride, hafnium oxide, as well as other III-V or II-VI
compound semiconductors. The substrate can also comprise a layered
semiconductor such as Si/SiGe, or a semiconductor-on-insulator
(SOI). In particular, the substrate can contain a Si-containing
semiconductor material (i.e., a semiconductor material that
includes Si). The semiconductor material can be doped, non-doped or
contain both doped and non-doped regions therein.
[0347] The substrate can have an anti-reflection control layer (ARC
layer) or a bottom ARC layer (BARC layer) to reduce reflectivity of
the film stack. Many suitable BARCs are known in the literature
including single layer BARCs, dual layer BARCs, graded BARCs, and
developable BARCs (DBARCs). The substrate can also comprise a hard
mask, a transfer layer (e.g., planarizing layer, spin-on-glass
layer, spin-on carbon layer), and other materials as required for
the layered device.
Auxiliary Polymers
[0348] The substrate, the underlayer and/or the SA layer referred
to above can include other polymers, referred to as auxiliary
polymers. The auxiliary polymer can be a homopolymer, random
copolymer, or block copolymer.
[0349] The auxiliary polymers can comprise a hydroxyl group. These
include hydroxyl-terminated polymers (e.g., hydroxyl-terminated
poly(styrene-co-methyl methacrylate and blends of
hydroxyl-terminated poly(styrene), hydroxyl-terminated poly(methyl
methacrylate), and poly(styrene-b-methyl methacrylate)),
hydroxyl-functionalized polymers (e.g., poly(styrene-co-methyl
methacrylate-co-2-hydroxyethyl methacrylate)).
[0350] Other auxiliary polymers include materials comprising
reactive groups, such as those derived from epoxydicyclopentadiene
methacrylate, glycidyl methacrylate, or vinyl cinnamates. Exemplary
materials comprising reactive groups include
poly(styrene-co-epoxydicyclopentadiene methacrylate),
poly(styrene-co-methyl methacrylate-co-epoxydicyclopentadiene
methacrylate), poly(styrene-co-methyl methacrylate-co-glycidyl
methacrylate), poly(styrene-co-methyl methacrylate-co-vinyl
cinnamate) poly(styrene-co-methyl methacrylate-co-vinyl
benzocyclobutane), and poly(alpha-methyl styrene-co-methyl
methacrylate)). The reactive polymers may react as a result of
thermal or photochemical treatment either alone or in conjunction
with an additional crosslinking agent. In particular, a catalytic
species such as a strongly acidic species may be used to facilitate
reaction. The strongly acidic species may be directly incorporated
into a coating composition. Alternatively, a thermal acid generator
or photoacid generator molecule may be used to generate an acidic
species as a result of thermal or photochemical treatment,
respectively.
[0351] Other non-limiting examples of auxiliary polymers include
materials used in ARC layers, which can include homopolymers and
copolymers selected from the group consisting of polybisphenols,
polysulfones, polycarbonates, polyhydroquinones, polyphthalates,
polybenzoates, polyphenylethers, polyhydroquinone alkylates,
polycarbamates, polymalonates and mixtures thereof. These moieties
are typically functionalized in order to tune the required physical
properties of the polymer (optical constants, surface energy). The
polymer components can also contain a plurality of reactive sites
distributed along the polymer for reaction with a crosslinking
component. More specific materials used in ARC layers include
poly(4,4'-methylenebisphenol-co-epichlorohydrin),
poly(4,4'-ethylidenebisphenol-co-epichlorohydrin),
poly(4,4'-isopropylidenebisphenol-co-epichlorohydrin),
poly(4,4'-isopropylidenebis[2-methylphenol]-co-epichlorohydrin),
poly(4,4'-isopropylidenebis[2,6-dimethylphenol]-co-epichlorohydrin),
poly(4,4'-cyclohexylidenebisphenol-co-epichlorohydrin),
poly(4,4'-[1-phenylethylidene] bisphenol-co-epichlorohydrin),
poly(4,4'-trifluoroisopropylidenebisphenol-co-epichlorohydrin),
poly(4,4'-hexafluoroisopropylidenebisphenol-co-epichlorohydrin),
poly(4,4'-sulfonylbisphenol-co-epichlorohydrin), poly(bisphenol AF
adipic ester), poly(bisphenol AF succinic ester),
poly(4,4'-hexafluoroisopropylidenediphthalate-co-epichlorohydrin),
poly(4,4'-hexafluoroisopropylidenediphthalate-co-poly(bisphenol
AF)),
poly(4,4'-hexafluoroisopropylidenebisbenzoate-co-epichlorohydrin),
poly(3,3',4,4'-benzophenonetetracarboxylate-co-epichlorohydrin),
poly(4,4'-hexafluoroisopropylidenediphthalate-co-epichlorohydrin-co-2,6-b-
is[hydroxymethyl]-p-cresol),
poly(3,3',4,4'-benzophenonetetracarboxylate-co-epichlorohydrin-co-2,6-bis-
[hydroxymethyl]-p-cresol), poly(terephthalate-co-epichlorohydrin),
poly(2-nitroterephthalate-co-epichlorohydrin),
poly(2-nitrophthalate-co-epichlorohydrin),
poly(2-nitroisophthalate-co-epichlorohydrin),
poly(hydroquinone-co-epichlorohydrin),
poly(methylhydroquinone-co-epichlorohydrin),
poly(1,2,4-benzenetriol-co-epichlorohydrin),
poly(methylene-bis[4-aminophenyl]-co-glycerol carbamate),
poly(isopropylidene-bis[4-aminophenyl]-co-glycerol carbamate),
poly(isopropylidene-bis[3-carboxy-4-aminophenyl]-co-glycerol
carbamate), poly(methylene-bis[4-hydroxyphenyl]-co-glycerol
carbonate), poly(isopropylidene-bis[4-hydroxyphenyl]-co-glycerol
carbonate),
poly(isopropylidene-bis[3-carboxy-4-hydroxyphenyl]-co-glycerol
carbonate), poly(2-phenyl-1,3-propanediol malonate),
poly(2-phenyl-1,3-propanediol 2-methyl-malonate),
poly(1,3-propanediol benzylidene-malonate),
poly(2-phenyl-1,3-propanediol benzylidene-malonate), glycidyl
endcapped poly(bisphenol A-co-epichlorohydrin), and
silicon-containing anti-reflection coating A940 from Shin Etsu.
Another more specific auxiliary polymer is
poly(styrene-co-epoxydicyclopentadiene methacrylate) random
copolymer, P(Sty-r-EDCPMA):
##STR00076##
wherein x and y are each integers greater than 1. Other auxiliary
polymers include poly(styrene-co-methyl
methacrylate-co-epoxydicyclopentadiene methacrylate),
poly(styrene-co-methyl methacrylate-co-glycidyl methacrylate),
poly(styrene-co-methyl methacrylate-co-2-hydroxyethyl
methacrylate), poly(styrene-co-methyl methacrylate-co-4-vinyl
cinammate), poly(styrene-co-methyl methacrylate-co-vinyl
benzocyclobutane), poly(styrene-co vinyl benzocyclobutane,
poly(alpha-methyl styrene-co-methyl methacrylate), and poly(methyl
glutarimide) (PMGI). Other auxiliary polymers comprise polymer
brush layers including those formed by hydroxyl-terminated
poly(styrene-co-methyl methacrylate), poly(styrene-co-methyl
methacrylate-co-2-hydroxyethyl methacrylate), hydroxyl-terminated
poly(styrene), hydroxyl-terminated poly(methyl methacrylate),
poly(styrene-b-methyl methacrylate) block copolymer, and
combinations of the foregoing surface affinity materials. Other
auxiliary polymers include other block copolymers capable of
forming self-assembled monolayers.
[0352] The coating composition used to prepare the underlayer
comprises at least a solvent and a disclosed random copolymer.
[0353] The coating composition used to prepare the SA layer
comprising a disclosed block copolymer comprises at least a
solvent, a disclosed high-chi block copolymer comprising a
polycarbonate block, and a disclosed SAP.
[0354] The foregoing compositions can additionally comprise other
materials including surfactants, polymers, photoacid generators,
and thermal acid generators. For example, an organosilicate resin
can be included in the composition for preparing an underlayer.
[0355] The compositions for preparing the underlayer and SA layer
can be applied by any suitable method that is compatible with the
processes and equipment used in microelectronics fabrication
assembly lines. Exemplary non-limiting techniques include
spin-coating, dip-coating, doctor blading, and spray coating.
[0356] Exemplary non-limiting casting solvents for preparing the
above-described polymer base coating compositions include toluene,
propylene glycol monomethyl ether acetate (PGMEA), propylene glycol
monomethyl ether (PGME), ethoxyethyl propionate, anisole, ethyl
lactate, 2-heptanone, cyclohexanone, amyl acetate, n-butyl acetate,
.gamma.-butyrolactone (GBL), aqueous solutions, acetone, and
combinations of the foregoing solvents.
[0357] The random copolymer for the underlayer has a weight average
molecular weight (Mw) of 3,000 to 200,000 g/mol. Similarly, the
random copolymer has a number average molecular weight (Mn) of
1,000 to 80,000. The random copolymer can also have a
polydispersity (Mw/Mn) of 1.01 to about 3.0. Molecular weight, both
Mw and Mn, can be determined by, for example, gel permeation
chromatography (GPC) using a universal calibration method,
calibrated to polystyrene standards.
[0358] The high-chi block copolymer for the directed self-assembly
(SA material) has a weight-average molecular weight (Mw) of 3,000
to 200,000 g/mol. Similarly, the high-chi block copolymer can have
a number average molecular weight (Mn) of 1,000 to 80,000. The
high-chi block copolymer can also have a polydispersity (Mw/Mn) of
1.01 to 3.
[0359] The surface active polymer (SAP) for the SA layer has a
weight-average molecular weight (Mw) of 3,000 to 200,000 g/mol.
Similarly, the SAP can have a number average molecular weight (Mn)
of 1,000 to 80,000. The SAP can have a polydispersity (Mw/Mn) of
1.01 to 3.
[0360] The morphology (e.g., shape, dimension, and orientation) of
the self-assembled domains from block copolymer thin films is a
function of block copolymer architecture (diblock, triblock, star
polymer, bottlebrush block copolymer, mikto-arm polymer, and
others), composition (e.g., material, molecular weight, and volume
ratio of different blocks), annealing conditions (e.g.,
temperature, environment, and annealing time), the interface
properties (e.g., polymer-air interface and polymer substrate
interface) as well as the defined geometry (e.g., film thickness
and topography of the confinement). Therefore, by adjusting one or
more parameters, the morphology can be adjusted to the need of
specific applications.
[0361] Self-assembly of the high-chi block copolymer (i.e., phase
separation and alignment of domains) can occur during film
formation, during a post-application bake, or during a subsequent
annealing process. Suitable annealing processes include thermal
annealing, thermal gradient annealing, solvent vapor annealing or
annealing by other gradient fields. More particularly, the SA layer
comprising a high-chi block copolymer is thermally annealed at a
temperature that is above the glass transition temperature
(T.sub.g) of the block copolymer but below the decomposition or
degradation temperature (T.sub.d) of the block copolymer. The
thermal annealing step can be carried out at an annealing
temperature of about 80.degree. C. to about 300.degree. C. The
thermal annealing can be performed for a period of more than 0
hours to about 100 hours, and more particularly for about 1 hour to
about 15 hours. The thermally annealed block copolymer
self-assembles to form ordered domains whose orientation is
perpendicular to the underlying surface plane. In general, the SA
layer can have a thickness of 50 to 10000 angstroms, more
particularly 100 to 5000 angstroms, and even more particularly 100
to 3000 angstroms.
[0362] The difference in the etch rates between two ordered domain
regions of the block copolymer allows the generation of additional
patterns. Selectively removing by etching, solvent or other means,
at least one self-assembled domain, creates a nano-scale relief
pattern comprising, for example, a pattern of holes that can be
transferred into the underlying substrate. Types of etching include
any common etching applied in the manufacture of semiconductor
devices, for example, dry-etching such as plasma etching, or
wet-etching using selective solvents and/or vapors. Typically, dry
etching processes are employed for etching at sub-50 nm dimensions.
Prior to this pattern development/pattern transfer, the
self-assembled layer of SA material can be optionally chemically
modified to improve properties necessary for pattern transfer, such
as etch resistance or mechanical properties.
[0363] The relief pattern of openings formed by selective removal
of one of the domains can have a spatial frequency greater than
that of a topographic pre-pattern used with the high-chi block
copolymer.
[0364] Etch resistant materials can be applied to a substrate
surface, underlayer surface, surface of a resist feature, and/or a
domain pattern of the block copolymer for control of relative etch
rates. The etch-resistant material can be deposited from the vapor
phase by a process including, chemical vapor deposition (CVD),
plasma enhanced CVD, atomic layer deposition (ALD), sequential
infiltration synthesis (SIS), sequential infiltration of metal
salts, sputtering, thermal evaporation, electron beam evaporation,
pulsed laser deposition, or other suitable deposition method that
is compatible with the processes and equipment used in
microelectronics fabrication.
[0365] Also disclosed is a film comprising the self-assembled
high-chi block polymer, the film comprising lamellar domains having
a perpendicular orientation relative to the plane of the film.
Further disclosed is a layered structure comprising substrate that
includes an underlayer, and a film of self-assembled high-chi block
copolymer disposed on the underlayer, the film comprising lamellar
domains having a perpendicular orientation relative to the plane of
the film. In an embodiment, the layered structure is a
semiconductor device.
[0366] The above-described processes can be used to form layered
structures comprising metal wiring lines, holes for contacts or
vias, insulation sections (e.g., damascene trenches or shallow
trench isolation), and trenches for capacitor structures suitable
for the design of integrated circuit devices. The method is
especially useful in the context of creating patterned layers of
oxides, nitrides or polysilicon.
[0367] The above-described methods advantageously allow
self-assembled structures having reduced feature width and
increased periodicity. The domain feature width can be from 1 nm to
about 30 nm, from 5 nm to about 18 nm, or more particularly from 5
nm to about 15 nm.
[0368] The following non-limiting examples are provided to further
illustrate the disclosed polymers and their use in forming
self-assembled layers.
Examples
[0369] Materials used in the following examples are listed in Table
1.
TABLE-US-00001 TABLE 1 ABBREVIATION DESCRIPTION SUPPLIER AcCl
Acetyl Chloride Sigma-Aldrich AIBN Azobisisobutyronitrile
Sigma-Aldrich Anisole Anisole Sigma-Aldrich AZPS1-OH Hydroxyl-
end-functional AZ Electronic polystyrene, Mn 6200 Materials
AZPS2-OH Hydroxyl- end-functional AZ Electronic polystyrene, Mn
10000 Materials AZPS3-OH Hydroxyl- end-functional AZ Electronic
polystyrene, Mn 4200 Materials BisMPA Dimethylolpropionoic acid
Perstorp BriBr .alpha.-Bromoisobutyryl bromide Sigma-Aldrich BzOH
Benzyl alcohol Sigma-Aldrich CuBr Copper (I) bromide Sigma-Aldrich
DBU 1,8-Diazabicyclo[5,4,0]undec- Sigma-Aldrich 7-ene DCM
Dichloromethane Sigma-Aldrich DPP Diphenyl phosphate Sigma-Aldrich
EtG Ethylene glycol Sigma-Aldrich EtG Ethylene glycol Sigma-Aldrich
EtiBr Ethyl .alpha.-bromoisobutyrate Sigma-Aldrich GMA Glycidyl
methacrylate, Sigma-Aldrich MW 142.2 HEMA Hydroxyethyl
methacrylate, Sigma-Aldrich MW 130.14 HFA-Sty Hexafluoroalcohol
Styrene Central Glass Chemical Company Lac
3,6-Dimethyl-1,4-dioxane- Sigma-Aldrich 2,5-dione Me6TREN
Tris[2-(dimethylamino)ethyl] Sigma-Aldrich amine MeOH Methanol
Sigma-Aldrich p-NBT p-Nitrobenzyltosylate Sigma-Aldrich OH-PSI1-OH
Hydroxyl- end-functional Polymer Source polystyrene, Mn 11000,
Inc,, Montreal DP = 108 Pf-OH 1H,1H-Perfluorononan-1-ol Synquest
Labs PFS Pentafluoro styrene Sigma-Aldrich PHOST
Poly(4-hydroxystyrene) Nippon Soda Co. Mn 5480, PDI = 1.08. PMDETA
N,N,N',N',N''- Sigma-Aldrich pentamethyldiethylenetriamine Si Gel
Silica Gel Sigma-Aldrich Sty Styrene, MW 104.15 Sigma-Aldrich TEA
Triethylamine Sigma-Aldrich THF Tetrahydrofuran Sigma-Aldrich TMC
Trimethylene carbonate Richman Chemicals Tol Toluene Sigma-Aldrich
P(Sty-r-MMA)- Hydroxy-terminated poly AZ Electronics OH
(styrene-r-methylmethacrylate) random copolymer
[0370] Herein, Mn is the number average molecular weight, Mw is the
weight average molecular weight, and MW is the molecular weight of
one molecule.
[0371] Cyclic carbonate monomer MTC-Me was prepared as previously
reported (Y. Zoul et al., Polymer, 45(16), 5459-5463; 2004).
##STR00077##
Example 1
[0372] Synthesis of diblock polymer DBP1, n=57, m=75.
##STR00078##
[0373] Diblock polymer DBP1, n=57, m=75 was prepared by ring
opening polymerization (ROP) of trimethylene carbonate (TMC) using
mono-alcohol initiator AZPS1-OH and ROP acid catalyst
diphenylphosphate (DPP). To an oven dried 20 mL round bottom flask
equipped with a magnetic stir bar, AZPS1-OH (0.70 g, 0.113 mmol,
Mn=6200, PDI=1.02, n=57, obtained from AZ-Electronic Materials,
Branchburg, N.J.), TMC (1.76 g, 17.25 mmol), and dichloromethane
(DCM, 2.94 mL) were added. The reaction mixture was stirred until
the AZPS1-OH macroinitiator and TMC were completely dissolved in
DCM, upon which diphenylphosphate (DPP, 400 mg, 1.6 mmol, catalyst)
was added. The reaction mixture was stirred at room temperature
(r.t.) for 16 hours in a glove box. The reaction flask was brought
out of the glove box and cooled at 0.degree. C. by immersing it in
an ice-water bath. The reaction was stopped by adding DCM (6 mL),
triethylamine (TEA, 0.7 mL, 02.72 mmol) and acetyl chloride (0.25
ml, 3.52 mmol). The reaction was further stirred for two hours at
room temperature. The resulting polymer was isolated by
precipitating the reaction mixture in methanol. The product was
collected in a frit funnel by removing methanol under vacuum and
the resulting solids were redissolved in THF to form a 20 wt %
solution and reprecipitated in methanol. The solid was collected in
a frit funnel and dried under vacuum at 40.degree. C. for two hours
to obtain the resulting compound. Mn (GPC)=17200, Mw=17700,
PDI=1.029; Mn (NMR)=AZPS(6.2 k)-PMTC(7.8 k), n=57.4, m=75; TMC %
conversion: about 50%. The resulting polymer was dissolved in THF
to form a 20 wt % solution and the polymer was precipitated in
methanol:acetonitrile (200 mL, 60:40 v/v). The precipitated solids
and the solvents were collected in a centrifuge tube and the solids
were collected by centrifuging at 4000 RPM at 0.degree. C. followed
by decanting the solvent and drying the solids in a vacuum oven at
40.degree. C. for two hours to give DBP1. Mn (GPC)=17200, Mw=17600,
PDI=1.02; Mn (NMR)=PS(6.2 k)-b-PTMC(7.7 k), n=57, m=75. The
notation PS(6.2 k)-b-PTMC(7.7 k) means the poly(styrene) block (PS)
has an Mn=6200 and the poly(trimethylene carbonate) block (PTMC)
has an Mn=7700. This notation is also used in the examples that
follow.
Example 2
[0374] Synthesis of diblock polymer DBP2, n=96, m=82.
##STR00079##
[0375] Diblock polymer DBP2, n=96, m=82 was prepared by ring
opening polymerization (ROP) of methyl carbonate (MTC-Me), with
mono-alcohol initiator AZPS2-OH and ROP base catalyst DBU. To an
oven dried 4 mL glass vial equipped with a magnetic stir bar,
AZPS2-OH (0.10 g, 0.01 mmol, Mn=10000, PDI=1.05, n=96), obtained
from AZ-Electronic Materials, Branchburg, N.J.), MTC-Me (0.31 g,
1.80 mmol), and DCM (1.80 mL) were added. The reaction mixture was
stirred until the AZPS2-OH macroinitiator and MTC-Me were
completely dissolved in DCM, upon which catalyst (DBU, 1.5 mg, 0.01
mmol, 10 wt % solution in toluene) was added. The reaction mixture
was stirred at room temperature (r.t.) for 3 hours in a glove box.
The reaction flask brought out of the glove box and cooled at
0.degree. C. by immersing it in an ice-water bath. The reaction was
stopped by adding DCM (1 mL), TEA (0.1 mL, 0.39 mmol) and acetyl
chloride (0.025 ml, 0.352 mmol). The reaction was further stirred
for two hours at room temperature. The resulting polymer was
isolated by precipitating the reaction mixture in methanol. The
product was collected in a frit funnel by removing methanol under
vacuum and the resulting solids were redissolved in THF to form a
20 wt % solution and reprecipitated in methanol. The solid was
collected in a frit funnel and dried under vacuum at 40.degree. C.
for two hours to obtain the resulting compound. Mn (GPC)=24040,
Mw=26224, PDI=1.09; Mn (NMR)=AZPS(10.0 k)-PMTC-Me(16.9 k), n=96,
m=97; MTC-Me % conversion: about 57%. The resulting polymer was
dissolved in THF to form a 20 wt % solution and the polymer was
precipitated in methanol:acetonitrile (20 mL, 80:20 v/v). The
precipitated solids and the solvents were collected in a centrifuge
tube and the solids were collected by centrifuging at 4000 RPM at
0.degree. C. followed by decanting the solvent and drying the
solids in a vacuum oven at 40.degree. C. for two hours to give
DBP2. Mn (GPC)=25700, Mw=27400, PDI=1.06; Mn of each block by
NMR=PS(10 k)-b-PMTC-Me(14.2 k), n=96, m=84.
Example 3
Synthesis of Triblock Polymer TBP1
##STR00080##
[0377] To an oven dried 4 mL vial equipped with a magnetic stir
bar, OH-PSI1-OH (0.15 g, 0.013 mmol, Mn=11,500, n=108, obtained
from Polymer Source Incorporated, Montreal, Canada), TMC (0.378 g,
3.70 mmol), and DCM (1.85 mL) were added. The reaction mixture was
stirred until the HO-PSI1-OH macroinitiator and TMC were completely
dissolved in DCM, upon which DPP (65 mg, 0.26 mmol) was added. The
reaction mixture was stirred at room temperature for 15 hours in a
glove box. The reaction was stopped by adding DCM (1 mL), TEA (0.2
mL) and acetyl chloride (0.1 mL). The reaction was further stirred
for two hours at room temperature. The resulting polymer was
isolated by precipitating the reaction mixture in methanol. The
product was collected in a frit funnel by removing methanol under
vacuum and the resulting solids were redissolved in THF to form a
20 wt % solution and reprecipitated in methanol. The solid was
collected in a frit funnel and dried under vacuum at 40.degree. C.
for two hours to obtain the resulting compound. The resulting
polymer was dissolved in THF to form a 20 wt % solution and the
polymer was precipitated in methanol:acetonitrile (200 mL, 60:40
v/v). The precipitated solids and the solvents were collected in a
centrifuge tube and the solids were collected by centrifuging at
4000 RPM at 0.degree. C. followed by decanting the solvent and
drying the solids in a vacuum oven at 40.degree. C. for two hours.
Mn (GPC)=27900, Mw=30300, PDI=1.09; Mn of each block by
NMR=PTMC(7.05 k)-b-PS(11.5 k)-b-PTMC(7.05 k), n=108, m=138. The
volume fraction of the PTMC block, expressed as VfPTMC, was about
0.49.
[0378] Table 2 summarizes the preparations and properties of the
block copolymers of Examples 1-3.
TABLE-US-00002 TABLE 2 NMR GPC (Mn, kDa)) BCP Time Mn Mw PS
Carbonate Vf Example Name Monomer Catalyst Initiator Temp (hours)
(kDa) (kDa) PDI block block Carbonate 1 DBP1 TMC DPP AZPS1-OH r.t.
16 17.2 17.6 1.02 6.2 7.7 0.49 2 DBP2 MTC-Me DBU AZPS2-OH r.t. 3
25.7 27.4 1.06 10k 14.2 0.47 3 TBP1 TMC DPP OH-PSI1-OH r.t. 15 27.9
30.3 1.09 11.5 14.1 0.49
Underlayer random copolymers based on styrene, TMC, and GMA
Example 4
[0379] Synthesis of Intermediate Random Copolymer P-1, Sty:HEMA:GMA
mole ratio x:y:z=88:6:6, Sty:HEMA:GMA, DP ratio
x':y':z'=50.5:3.5:3.5, used as a macroinitiator further below.
##STR00081##
[0380] In the above notation, the vertical stacking of the repeat
units within the square brackets indicates a random distribution of
the repeat units in the polymer chain. End group E' is linked to
one of the starred bonds overlapping the left square bracket. End
group E'' is linked to one of the starred bonds overlapping the
right square bracket. It should be understood that for a given
repeat unit, a starred bond that overlaps the left square bracket
can be linked to a different repeat unit at the position indicated
by the right starred bond overlapping the right square bracket, or
to end group E'. Likewise, for a given repeat unit, a starred bond
that overlaps the right square bracket can be linked to a different
repeat unit at the position indicated by the left starred bond
overlapping the left square bracket, or to end group E''. Unless
otherwise indicated, subscripts x', y', and z' represent the
average number of the corresponding parenthesized repeat unit in
the polymer. For P-1, the end groups E' and E'' are not shown.
[0381] Styrene (Sty, 14.4 g, 138.0 mmol), hydroxy ethyl
methacrylate (HEMA, 1.0 g, 7.68 mmol), glycidyl methacrylate (GMA,
1.09 g, 7.66 mmol), THF (50 g), and azobisisobutyronitrile (AIBN,
0.757 g, 4.61 mmol, 3 mol % based on total moles of vinyl monomers)
were combined in a 250 mL round bottom flask (RBF) equipped with a
magnetic stir-bar and an overhead condenser. The reaction mixture
was stirred at 70.degree. C. for 18 hours and was stopped by
cooling the reaction to room temperature. The resulting polymer was
isolated by two precipitations in MeOH, and was dried under vacuum
at 50.degree. C. for 24 hours. Mn=6200, Mw=8700, PDI=1.40. The
product Sty:HEMA:GMA mole ratio x:y:z was calculated by .sup.13C
inverse gated NMR as x:y:z=88:6:6. Based on the Mn and the product
mole ratio, the degree of polymerization (DP) of each repeat units
Sty:HEMA:GMA was calculated for P-1 to be x':y':z'=50.5:3.5:3.5,
respectively.
[0382] The random copolymers of Examples 5-14 have the prefix "G1"
in the name were prepared from macroinitiator P-1.
Example 5
[0383] Synthesis of TMC-functional random graft copolymer G1-1 from
macroinitiator P-1 (Example 4, STY:HEMA:GMA molar ratio
x:y:z=88:6:6, DP ratio x':y':z'=50.5:3.5:3.5) for orientation
control.
##STR00082##
[0384] The quantity y'a' (i.e., y' multiplied by a') represents the
total average number of repeat units derived from TMC in the random
graft copolymer G1-1. In these calculations, Mn was not adjusted
for the mass of end groups E' and E'' when determining the DP of
each repeat unit.
[0385] P-1 (0.2 g, Example 4), trimethylene carbonate (TMC, 0.060
g, 0.588 mmol) and dichloromethane (DCM, 0.2 g) were added to an
oven dried 4 mL glass vial equipped with a magnetic stir bar. The
reaction mixture was stirred until the macroinitiator and TMC were
completely dissolved in DCM, upon which
1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, .about.10 mg) was added.
The reaction mixture was stirred at room temperature (r.t.) for 1
hour in a glove box. The reaction was stopped by bringing the
reaction vial out of the glove box and by adding DCM (0.5 ml),
triethylamine (TEA, 0.27 g, 2.72 mmol) and acetyl chloride
(.about.60 mg, 0.764 mmol). The reaction was further stirred for
two hours at room temperature. The resulting polymer was isolated
by precipitating the reaction mixture in methanol. The product was
collected in a frit funnel by removing methanol under vacuum and
the resulting solids were redissolved in THF to form a 20 wt %
solution and reprecipitated in methanol for two more times. The
solids were collected in a frit funnel and dried under vacuum at
40.degree. C. for two hours to obtain random graft copolymer G1-1,
where the Sty:TMC mole ratio x':y'a'=73:27 was determined by
.sup.1H NMR. The average value of a' was calculated as follows:
[0386] x'/y'=50.5/3.5 (DP ratio of the P-1 macroinitiator), [0387]
x'/(y'a')=73/27 (Sty:TMC mole ratio of G1-1 by .sup.1H NMR), [0388]
rearranging, x'/y'=73a'/27 [0389] substituting, 50.5/3.5=73a'/27,
and [0390] solving, a'=5.33. Therefore, G1-1 has a side chain
polycarbonate having an average number of carbonate repeat units
a'=5.33, based on the Mn of G1-1.
Examples 6-15
[0391] Preparation of underlayer random graft copolymers G1-2 to
G1-11 for orientation control. These polymers were prepared using
the general procedure of Example 5 and macroinitiator P-1 (Example
4) at various Sty:TMC molar ratios. G1-2 to G1-11 differ from G1-1
by a', the average number of repeat units of TMC in the side
chain.
[0392] Table 3 summarizes the preparation of Examples 5-15.
TABLE-US-00003 TABLE 3 Random Graft P-1 Polymer TMC DCM DBU
Initiator Time GPC Sty:TMC Monomer % Ex. Name (g) (g) (mg) (g) Temp
(hours) Mn Mw PDI Mole Ratio a'.sup.1 Conversion. 5 G1-1 0.06 0.2
~10 0.2 r.t. 1 -- -- -- 73:27 5.3 >99 6 G1-2 0.1 0.32 ~10 0.2
r.t. 1.5 -- -- -- 60:40 9.6 >99 7 G1-3 0.46 1.50 ~10 0.2 r.t. 2
23600 44000 1.87 24:76 45.7 >99 8 G1-4 0.035 0.52 ~10 0.2 r.t.
0.45 -- -- -- 88:12 2.0 >99 9 G1-5 0.06 0.37 ~13 0.2 r.t. 1 9300
13500 1.44 73:27 5.3 >99 10 G1-6 0.1 0.45 ~10 0.2 r.t. 1.5 11400
18000 1.57 59:41 10.0 >99 11 G1-7 0.06 0.72 ~10 0.2 r.t. 1 -- --
-- 73:27 5.3 >99 12 G1-8 0.1 0.9 ~10 0.2 r.t. 1.4 -- -- -- 66:34
7.4 ~90 13 G1-9 0.15 0.9 ~16 0.2 r.t. 1 12100 15900 1.31 62:38 8.8
~50 14 G1-10 0.15 0.9 ~14 0.2 r.t. 0.75 -- -- -- 62:38 8.8 ~50 15
G1-11 0.15 0.9 ~14 0.2 r.t. 1.4 -- -- -- 43:57 19.1 ~65 .sup.1a' is
based on Mn of the random graft copolymer, without correcting for
end groups Synthesis of underlayers based on styrene, AcEMA, and
GMA
[0393] These random copolymers (Examples 16-22) have the prefix
"GHS" in the name and have the general structure
##STR00083##
where average numbers of repeat units x', y' and z' are greater
than 0. End groups E' and E'' are not shown.
Example 16
[0394] Synthesis of poly(styrene-r-acetoxyethyl
methacrylate-r-glycidyl methacrylate) underlayer GHS-1,
x:y:z=77:19:4 (mole ratio), DP ratio x':y':z'=48.5:12.1:2.6.
[0395] Styrene (Sty, 4.0 g, 38.4 mmol, MW 104.2), acetoxyethyl
methacrylate (AcEMA, 1.21 g, 7.02 mmol, MW 172.2), glycidyl
methacrylate (GMA, 0.20 g, 1.40 mmol, MW 142.2), THF (22 g), and
azobisisobutyronitrile (AIBN, 0.31 g, 1.87 mmol, 4 mol % based on
total moles of vinyl monomers) were combined in a 250 mL round
bottom flask (RBF) equipped with a magnetic stir-bar and an
overhead condenser. The reaction mixture was stirred at 70.degree.
C. for 18 hours and was stopped by cooling the reaction to room
temperature. The resulting polymer was isolated by two
precipitations in MeOH, and was dried under vacuum at 50.degree. C.
for 24 hours to give GHS-1. Mn=7500, Mw=10,100, PDI=1.34. The
product mole ratio of Sty:AcEMA:GMA was calculated by .sup.13C
inverse gated NMR as x:y:z=77:19:4 (mole ratio). Based on Mn and
without adjusting for end groups E' and E'', the degree of
polymerization ratio of Sty:AcEMA:GMA was x':y':z'=48.5:12.1:2.6,
or 48:12:3 when rounded to zero decimal places.
Examples 17-22
[0396] Preparation of random graft copolymers GHS-2 to GHS-7 for
underlayer orientation control. These polymers were prepared using
the general procedure of Example 16 at various Sty:AcEMA:GMA molar
ratios.
[0397] Table 4 summarizes the preparations of Examples 16-22.
TABLE-US-00004 TABLE 4 Random Graft Polymer Sty AcEMA GMA AIBN THF
Temp Time Examples Name (g, mmol) (g, mmol) (g, mmol) (g, mmol) (g)
(.degree. C.) (hours) 16 GHS-1 4.0, 1.21, 0.20 0.31, 22 70 18 38.4
7.02 1.40 1.87 17 GHS-2 1.40, 1.61, 0.1, 0.154, 10 70 18 13.33 9.38
0.70 0.94 18 GHS-3 0.66, 2.82, 0.10, 0.154, 11 70 18 6.33 16.41
0.70 0.94 19 GHS-4 1.27, 1.82, 0.10, 0.154, 10 70 18 12.20 10.55
0.70 0.94 20 GHS-5 1.20, 1.94, 0.1, 0.154, 10 70 18 11.5 11.25 0.70
0.94 21 GHS-6 0.55, 1.05, 0.05, 0.077, 5 70 18 5.2 6.1 0.35 0.47 22
GHS-7 0.66, 0.87, 0.05, 0.077, 5 70 18 6.32 5.04 0.35 0.47 Feed
Product Product Mole Ratio Mole Ratio Sty:AcEMA:GMA GPC Examples
Sty:AcEMA:GMA Sty:AcEMA:GMA DP ratio Mn Mw PDI 16 82:15:3 77:19:4
49:12:3 7500 10100 1.34 17 57:40:3 55:42:2 29:22:1 6900 12100 1.74
18 27:70:3 29:68:3 15:36:2 8100 14600 1.79 19 52:45:3 50:47:3 7200
11870 1.64 20 49:48:3 48:49:3 7570 12860 1.69 21 42:52:3 45:50:4
27:30:2 8400 13700 1.63 22 54:43:3 53:44:3 31:26:2 7900 12900
1.62
Synthesis of surface active polymer additives (SAP)
Example 23
[0398] Synthesis of PSAP1-40, a protected random copolymer of
pentafluorostyrene (PFS) and acetoxystyrene (Ac-Sty).
##STR00084##
[0399] Pentafluorostyrene (PFS, 3.0 g, 15.45 mmol, MW 194),
acetoxystyrene (Ac-Sty, 3.75 g, 23.18 mmol, MW 162.19),
tetrahydrofuran (THF, 20 g), and azobisisobutyronitrile (AIBN, 0.25
g, 1.54 mmol, 4 mol % based on total moles of vinyl monomers) were
combined in a 100 mL round bottom flask (RBF) equipped with a
magnetic stir-bar and an overhead condenser. The reaction mixture
was stirred at 70.degree. C. for 18 hours and was stopped by
cooling the reaction to room temperature. The resulting polymer was
isolated by two precipitations in hexanes, and was dried under
vacuum at 50.degree. C. for 24 hours. The resulting polymer was
used directly for deprotection as described below (Example 28) and
was not further characterized.
Examples 24-26
[0400] Synthesis of PSAP1-60, PSAP1-80, and PSAP1-90, respectively.
These random copolymers of PFS and Ac-Sty were prepared using the
general procedure of Example 23 at various molar ratios of PFS and
Ac-Sty.
Example 27
Synthesis of PSAP2-60
##STR00085##
[0402] Tridecafluoro methacrylate (TDFMA, 1.50 g, 3.47 mmol, MW
432), acetoxystyrene (Ac-Sty, 0.375 g, 2.31 mmol, MW 162.19), THF
(7.50 g), and azobisisobutyronitrile (AIBN, 38 mg, 0.23 mmol, 4 mol
% based on total moles of vinyl monomers) were combined in a 100 mL
round bottom flask (RBF) equipped with a magnetic stir-bar and an
overhead condenser. The reaction mixture was stirred at 70.degree.
C. for 18 hours and was stopped by cooling the reaction to room
temperature. The resulting polymer was isolated by two
precipitations in methanol, and was dried under vacuum at
50.degree. C. for 24 hours. The polymer was not further
characterized and was used directly for deprotection as described
below.
[0403] Table 5 summarizes the preparations of protected surface
active polymer Examples 23-27 prepared by free radical
polymerization using AIBN initiator.
TABLE-US-00005 TABLE 5 PSAP Monomer 1 Monomer 2 additive Feed Feed
AIBN THF Time Ex. name Name (g, mmol) Mole % Name (g, mmol) Mole %
(g, mmol) (g) Temp (hours) 23 PSAP1-40 PFS 3.0, 40 Ac-Sty 3.75, 60
0.25, 20 70 18 15.45 23.18 0.1.54 24 PSAP1-60 PFS 4.50 60 Ac-Sty
2.52 40 0.25, 20 70 18 23.18 15.44 0.1.54 25 PSAP1-80 PFS 6.01 80
Ac-Sty 1.25, 20 0.25, 20 70 18 30.97 7.74 0.1.54 26 PSAP1-90 PFS
6.63, 90 Ac-Sty 0.63, 10 0.25, 20 70 18 34.89 3.87 0.1.54 27
PSAP2-60 TFDMA 1.50, 60 Ac-Sty 0.375, 40 0.038, 7.5 70 18 3.47 2.31
0.23
Example 28
Deprotection of PSAP1-40 of Example 23 to form SAP1-40
##STR00086##
[0405] To a 100 ml round bottom flask equipped with a magnetic stir
bar and a reflux condenser, PSAP1-40 (1.50 g, Example 23) was
added. To this flask, methanol (20 ml) was added to create a
suspension of the polymer. Ammonium hydroxide solution (2.1 g,
28.0-30.0 wt % solution in water) was added to the vessel and the
reaction was heated at 70.degree. C. for 18 hours. The resulting
polymer was precipitated in 1000 ml of water spiked with 2-3 ml of
acetic acid. The solids were collected and redissolved in THF
followed by re-precipitation in water. The resulting solid was
dried under vacuum at 80.degree. C. for 24 hours. Mn=16000,
Mw=26000, PDI=1.65. The product PFS:hydroxystyrene x:y mole ratio
was calculated by .sup.13C inverse gated NMR as x:y=44:56 (mole
ratio). Based on Mn and excluding end groups E' and E'', the DP
ratio x':y'=46:59.
Examples 29-32
[0406] Deprotection of PSAP1-60, PSAP1-80, PSAP1-90 and PSAP2-60,
respectively. These random copolymers were deprotected using the
general procedure of Example 28. The perfluorinated ester of
PSAP2-60 was stable to the hydrolysis conditions.
Example 33
Synthesis of SAP3-80
##STR00087##
[0408] Pentafluorostyrene (PFS, 1.50 g, 15.45 mmol, MW 194),
4-vinyl benzoic acid (4-VBA, 0.286 g, 23 mmol, MW 162.19), THF (20
g), and azobisisobutyronitrile (AIBN, 0.25 g, 1.54 mmol, 4 mol %
based on total moles of vinyl monomers) were combined in a 100 mL
round bottom flask (RBF) equipped with a magnetic stir-bar and an
overhead condenser. The reaction mixture was stirred at 70.degree.
C. for 18 hours and was stopped by cooling the reaction to room
temperature. The resulting polymer was isolated by two
precipitations in hexanes, and was dried under vacuum at 50.degree.
C. for 24 hours. Mn=11000, Mw=14900, PDI=1.35. The product PFS:4VBA
x:y mole ratio was calculated by .sup.13C inverse gated NMR as
x:y=84:16 (mole ratio). Based on Mn and excluding end groups E' and
E'', the DP ratio x':y'=49.5:9.4.
[0409] Table 6 summarizes the NMR and GPC analyses of surface
active polymer Examples 28-33.
TABLE-US-00006 TABLE 6 SAP SAP SAP Monomer Monomer additive Monomer
1 Monomer 2 1:Monomer2 1:Monomer 2 GPC Ex. name Name Name Mole
Ratio DP Ratio Mn Mw PDI 28 SAP1-40 PFS HOST 44:56 46:59 16.0k
26.0k 1.65 29 SAP1-60 PFS HOST 57:43 16.1k 24.7k 1.52 30 SAP1-80
PFS HOST 80:20 8.7k 14.2k 1.62 31 SAP1-90 PFS HOST 89:11 11.0k
15.6k 1.45 32 SAP2-60 TFDMA HOST 33 SAP3-80 PFS 4-VBA 84:16
49.5:9.4 11.0k 14.9k 1.35 HOST = repeat unit formed from
deprotection of acetoxystyrene ("hydroxystyrene").
Underlayer and Composite Layer Film Preparations
Examples 34-40
[0410] Thin film preparation of underlayers (ULs) with random graft
copolymers G1-2, G1-3, G1-7, G1-8 and G1-10 (see above Table
3).
[0411] The following general procedure was used to prepare a thin
film underlayer on a silicon wafer. A solution was prepared by
dissolving the random graft copolymer (95 parts by weight) and
p-nitrobenzyl tosylate (p-NBT, 5 parts by weight) in propylene
glycol monomethyl ether acetate (PGMEA, 10,000 parts by weight) to
form a 1.0 wt % solution based on total dry solids. p-NBT is a
thermal acid generator and was added to promote the grafting and
partial crosslinking of a thin film of the random graft copolymer
on the silicon wafer substrate when baked (annealed). The solutions
were passed through a 0.2 mm polytetrafluoroethylene (PTFE) filter
prior to spin coating the solution on a silicon wafer at 2000 rpm
spin rate. After forming the thin film, the coated wafer was baked
at 200.degree. C. for 3 minutes and cooled to room temperature. The
initial baked thin film (underlayer) had a thickness of 20 nm,
measured with a Nanospec Reflectometer. The underlayer was then
given a solvent rinse by casting PGMEA on top of the coated wafer,
letting the solvent puddle for 30 seconds, and spin drying the
treated wafer at 2000 rpm for 30 seconds. The rinse was intended to
remove any excess random graft copolymer that was not crosslinked
or grafted to the wafer surface. The final film thickness of the
underlayer was 10 nm after the solvent rinse. Table 7 summarizes
the underlayer films UL-1 to UL-5 and UL-13 to UL-14 prepared with
the random copolymers having a "G1" prefix in the name.
TABLE-US-00007 TABLE 7 DP.sup.1 UL Random Sty:TMC Sty HEMA TMC
Example Name Copolymer mole ratio (x') (y') (a') 34 UL-1 G1-3 24:76
50.5 3.5 45.7 35 UL-2 G1-2 60:40 50.5 3.5 9.6 36 UL-3 G1-10 62:38
50.5 3.5 8.8 37 UL-4 G1-8 66:34 50.5 3.5 7.4 38 UL-5 G1-7 73:27
50.5 3.5 5.3 39 UL-13 G1-11 43:57 50.5 3.5 8.8 40 UL-14 G1-4 88:12
50.5 3.5 19.1 .sup.1x', y', and a' are based on Mn of the random
graft copolymer
Examples 41-47
[0412] Thin film preparation of underlayers (ULs) using random
copolymers GHS-1 to GHS-7 (see above Table 4).
[0413] The following general procedure was used to prepare a thin
film underlayer on a silicon wafer. A solution was prepared by
dissolving the random graft copolymer (95 parts by weight) and
p-nitrobenzyl tosylate (p-NBT, 5 parts by weight) in propylene
glycol monomethyl ether acetate (PGMEA, 10,000 parts by weight) to
form a 1.0 wt % solution based on total dry solids. The solutions
were passed through a 0.2 mm polytetrafluoroethylene (PTFE) filter
prior to spin coating the solution on a silicon wafer at 2000 rpm
spin rate. After forming the thin film, the coated wafer was baked
at 190.degree. C. for 3 minutes and cooled to room temperature. The
initial baked thin film (underlayer) had a thickness of 20 nm,
measured with a Nanospec Reflectometer. The underlayer was then
given a solvent rinse by casting PGMEA on top of the coated wafer,
letting the solvent puddle for 30 seconds, and spin drying the
treated wafer at 2000 rpm for 30 seconds. The rinse was intended to
remove any excess random graft copolymer that was not crosslinked
or grafted to the wafer surface. The final film thickness of the
underlayer was 10 nm after the solvent rinse. Table 8 summarizes
the underlayer films UL-6 to UL-12 prepared with GHS-1 to GHS-7,
respectively.
TABLE-US-00008 TABLE 8 UL Random Sty:AcEMA:GMA Sty:AcEMA:GMA
Example Name Copolymer mole ratio DP ratio 41 UL-6 GHS-1 77:19:4
49:12:3 42 UL-7 GHS-2 55:43:2 29:22:1 43 UL-8 GHS-3 29:68:3 15:36:2
44 UL-9 GHS-4 50:47:3 45 UL-10 GHS-5 48:49:3 46 UL-11 GHS-6 45:50:4
27:30:2 47 UL-12 GHS-7 53:44:3 31:26:2
Examples 48-52
[0414] Thin film preparation of underlayers (ULs) using
P(Sty-r-MMA)-OH random copolymer brushes obtained from AZ
Electronic Materials.
[0415] The following general procedure was used to prepare a thin
film underlayer on a silicon wafer. P(Sty-r-MMA)-OH, a
hydroxy-terminated poly(styrene-r-methyl methacrylate) random
copolymer brush material, was received from AZ Electronic Materials
in the form of a solution in PGMEA (solution code NLD-303). The
solution was used as received. The polymer solution was spin coated
with 2000 rpm on a silicon wafer. The coated wafer was baked at
250.degree. C. for 2 minutes prior to a solvent rinse to form
UL-15. Table 9 summarizes the underlayer films UL-15 to UL-19
prepared with P(Sty-r-MMA)-OH random copolymer brush materials,
where Sty=styrene and MMA=methyl methacrylate.
TABLE-US-00009 TABLE 9 UL P(Sty-r-MMA)-OH Sty:MMA Example Name Name
mol % 48 UL-15 NLD-303 0:100 49 UL-16 NLD-328J 20:80 50 UL-17
NLD-320 30:70 51 UL-18 NLD-321 40:60 52 UL-19 NLD-322 47:53
Formulation of Block Copolymer and SAP Additives
Examples 53-65
[0416] Preparation of coating formulations for self-assembly using
block copolymers of Examples 1-3 and surface active polymers (SAP)
of Examples 28-33.
[0417] The following general procedure is representative. Separate
block copolymer solutions were prepared for one coating. The block
copolymer (0.01 g) for self-assembly was dissolved in PGMEA (0.823
g) to form a 1.2 wt % solution of the block copolymer. Surface
active polymer (0.1 g, one of SAP Examples 28-33) was dissolved in
PGMEA (8.23 g) to form a 1.2 wt % stock solution of the SAP polymer
based on total weight of the solution. The SAP solution was
filtered through 0.2 micrometer PTFE filter. A portion of the SAP
stock solution was then added to the entire block copolymer
solution containing to form a coating composition containing the
desired SAP concentration. This solution was stirred at room
temperature to form a homogeneous mixture upon which it was
filtered through a 0.2 micrometer PTFE filter. Table 10 summarizes
the prepared block copolymer coating formulations containing SAP
additives.
TABLE-US-00010 TABLE 10 Coating Formulation BCP SAP SAP Each Block
Stock Stock wt % of BCP BCP BCP Mn (NMR) SAP SAP Sol'n Sol'n SAP
BCP PGMEA total Example Ex. Name Type (k = .times.1000) Name
Example (g) (g) (mg) (g) (g) solids 53 1 DBP1 Diblock 6.2k-7.7k
SAP1-40 28 0.833 0.042 0.504 0.01 0.865 5 54 1 DBP1 Diblock
6.2k-7.7k SAP1-60 29 0.833 0.042 0.504 0.01 0.865 5 55 1 DBP1
Diblock 6.2k-7.7k SAP1-80 30 0.833 0.042 0.504 0.01 0.865 5 56 1
DBP1 Diblock 6.2k-7.7k SAP1-90 31 0.833 0.042 0.504 0.01 0.865 5 57
1 DBP1 Diblock 6.2k-7.7k SAP1-80 30 0.833 0.025 0.300 0.01 0.848 3
58 1 DBP1 Diblock 6.2k-7.7k SAP1-80 30 0.833 0.083 0.996 0.01 0.905
10 59 1 DBP1 Diblock 6.2k-7.7k SAP1-90 31 0.833 0.025 0.300 0.01
0.848 3 60 1 DBP1 Diblock 6.2k-7.7k SAP1-90 31 0.833 0.083 0.996
0.01 0.905 10 61 2 DBP2 Diblock 10.0k-14.3k SAP1-80 30 0.833 0.012
0.144 0.01 0.865 1.5 62 3 TBP1 Triblock 7.05k-11.5k-7.05k SAP1-80
30 0.833 0.008 0.096 0.01 0.831 1 63 3 TBP1 Triblock
7.05k-11.5k-7.05k SAP1-80 30 0.833 0.025 0.300 0.01 0.848 3 64 3
TBP1 Triblock 7.05k-11.5k-7.05k SAP2-60 32 0.833 0.025 0.300 0.01
0.848 3 65 3 TBP1 Triblock 7.05k-11.5k-7.05k SAP3-80 33 0.833 0.042
0.504 0.01 0.865 5
Thin film self-assembly of formulated block copolymer compositions
on UL-1 to UL-14.
Examples 66-78
[0418] The following general procedure was used to prepare thin
films of formulated block copolymers on UL-1 to UL-14 substrates. A
selected coating formulation prepared in Examples 53-65 was spin
coated on a selected underlayer coated substrate of Examples 34-47
at a spin rate of 2000 rpm. The coated wafer was then baked
(annealed) at a temperature of 140.degree. C. or 170.degree. C. for
5 minutes and immediately cooled to room temperature. The
formulated block copolymer films were characterized by atomic force
microscopy (AFM) using a Digital Instruments 3100 AFM with a 1 N/m
spring constant silicon nitride cantilever operated in a tapping
mode. Scan size and speed were set at 2 micrometer.times.2
micrometer area and 1 Hz respectively.
[0419] Table 11 summarizes the coating and annealing conditions of
the films prepared in Examples 66-78.
TABLE-US-00011 TABLE 11 BCP Thin Film layer for Self-Assembly
Coating/Annealing Conditions BCP Mn SAP Spin Spin Annealing
Annealing Film Underlayer Formulation BCP of each block SAP wt % of
Speed time Temp Time Example Name Example Name (k = .times.1000)
name dry solids RPM Sec .degree. C. (min) 66 UL-2 53 DBP1 6.2k-7.7k
SAP1-40 5 2000 30 170 5 67 UL-2 54 DBP1 6.2k-7.7k SAP1-60 5 2000 30
170 5 68 UL-2 55 DBP1 6.2k-7.7k SAP1-80 5 2000 30 170 5 69 UL-2 56
DBP1 6.2k-7.7k SAP1-90 5 2000 30 170 5 70 UL-2 57 DBP1 6.2k-7.7k
SAP1-80 3 2000 30 170 5 71 UL-2 58 DBP1 6.2k-7.7k SAP1-80 10 2000
30 170 5 72 UL-2 59 DBP1 6.2k-7.7k SAP1-90 3 2000 30 140 5 73 UL-2
60 DBP1 6.2k-7.7k SAP1-90 10 2000 30 140 5 74 UL-16 61 DBP2
10k-14.2k SAP1-80 1.5 2000 30 170 5 75 UL-2 62 TBP1
7.05k-11.5k-7.05k SAP1-80 1 2000 30 140 5 76 UL-2 63 TBP1
7.05k-11.5k-7.05k SAP1-80 3 2000 30 140 5 77 UL-2 64 TBP1
7.05k-11.5k-7.05k SAP2-60 3 2000 30 140 5 78 UL-2 65 TBP1
7.05k-11.5k-7.05k SAP3-80 5 2000 30 140 5
[0420] Table 12 summarizes the atomic force microscopy height
images obtained with the self-assembled films prepared on various
underlayers and the morphologies obtained by self-assembly. "I/H"
means islands/holes (not desirable). "Partially .perp. lamellae"
means about 20% to less than 70% of the regions of the film
contained perpendicular lamellae (not desirable). ".perp. lamellae"
means 95% to 100% of the regions of the film contained
perpendicular lamellae (most desirable). "Flat" means there was no
discernible structure in the film.
TABLE-US-00012 TABLE 12 Self-Assembled Thin Film Layer BCP Each SAP
Underlayer Underlayer Formulation BCP Block Mn SAP wt % of Thin
Film Example Name Polymer Example Name (k = .times.1000) Name dry
solids Morphology 66 UL-2 G1-2 53 DBP1 6.2k-7.7k SAP1-40 5 I/H 67
UL-2 G1-2 54 DBP1 6.2k-7.7k SAP1-60 5 I/H 68 UL-2 G1-2 55 DBP1
6.2k-7.7k SAP1-80 5 .perp. lamellae 69 UL-2 G1-2 56 DBP1 6.2k-7.7k
SAP1-90 5 Partially .perp. lamellae 70 UL-2 G1-2 57 DBP1 6.2k-7.7k
SAP1-80 3 Partially .perp. lamellae 71 UL-2 G1-2 58 DBP1 6.2k-7.7k
SAP1-80 10 I/H 72 UL-2 G1-2 59 DBP1 6.2k-7.7k SAP1-90 3 I/H 73 UL-2
G1-2 60 DBP1 6.2k-7.7k SAP1-90 10 .perp. lamellae 74 UL-16 NLD-328J
61 DBP-2 10k-14.2k SAP1-80 1.5 .perp. lamellae 75 UL-2 G1-2 62 TBP1
7.05k-11.5k-7.05k SAP1-80 1 Partially .perp. lamellae 76 UL-2 G1-2
63 TBP1 7.05k-11.5k-7.05k SAP1-80 3 .perp. lamellae 77 UL-2 G1-2 64
TBP1 7.05k-11.5k-7.05k SAP2-60 3 .perp. lamellae 78 UL-2 G1-2 65
TBP1 7.05k-11.5k-7.05k SAP3-80 5 .perp. lamellae
[0421] FIGS. 3-15 are atomic force microscopy (AFM) images of the
self-assembled block copolymer films of Examples 66-78,
respectively. Film layers containing SAP1-80, SAP1-90, SAP2-60 and
SAP3-80 produced perpendicular lamellae at SAP concentration of 1.5
wt % to 10 wt % based on total dry solids of the formulation used
to prepare the SA layer. SAP1-80 was effective in producing
perpendicular lamellae when used in amounts of 1.5 wt % with
diblock copolymer DBP2 on underlayer UL-16. SAP1-80, SAP2-60, and
SAP3-80 were effective in producing perpendicular lamellae when
used in amounts of 3 wt % with triblock copolymer TBP1 on
underlayer UL-2.
Graphoepitaxy Directed Self-Assembly (DSA)
Example 79
[0422] In this example, a topographic pre-pattern was formed on a
neutral underlayer (UL-2) using a negative tone photoresist,
followed by coating a thin film of formulated block copolymer onto
the pre-pattern. The block copolymer was substantially confined to
the trenches of the resist pre-pattern. The coated structure was
then annealed, allowing the pre-pattern to direct self-assembly of
the block copolymer.
[0423] An underlayer solution was prepared by dissolving the random
graft copolymer G1-2 (0.095 g, 95 parts by weight) and
p-nitrobenzyl tosylate (p-NBT, 0.005 g, 5 parts by weight) in
propylene glycol monomethyl ether acetate (PGMEA, 9.90 g, 10,000
parts by weight) to form a 1.0 wt % solution based on total weight
of the solution. The thermal acid generator p-NBT was added to
promote the grafting and partial crosslinking of a thin film of the
random graft copolymer on a silicon wafer substrate stack. The
silicon wafer substrate stack comprised a silicon wafer bottom
layer coated with .about.30 nm thick amorphous carbon layer and 10
nm thick silicon nitride (SiN.sub.x) layer. The underlayer solution
was passed through a 0.2 micrometer polytetrafluoroethylene (PTFE)
filter prior to spin coating the solution on the silicon wafer
stack at 2000 rpm spin rate. After forming the thin film, the
coated wafer was baked at 200.degree. C. for 3 minutes and cooled
to room temperature. The initial baked thin film (underlayer) had a
thickness of 20 nm, measured with a Nanospec Reflectometer. The
underlayer was then given a solvent rinse by casting PGMEA on top
of the coated wafer, letting the solvent puddle for 30 seconds, and
spin drying the treated wafer at 2000 rpm for 30 seconds. The rinse
was intended to remove any excess random graft copolymer that was
not crosslinked or grafted to the wafer surface. The final film
thickness of the underlayer was 10 nm after the solvent rinse.
[0424] Next, a 60 nm thick layer of a commercial 193 nm
negative-tone photoresist (JSR ARF7210JN-8) was disposed on this
underlayer coated substrate followed by post application bake at
80.degree. C. for 60 seconds. The photoresist layer was then
exposed using a 193 nm immersion interference tool (IBM NEMO) with
fixed dose of 4.67 mJ, baked at 95.degree. C. for 60 sec, and
developed for 60 seconds with 2-heptanone developer. The resulting
200 nm pitch patterned photoresist layer was then hard baked at
200.degree. C. for 3 min prior to coating a block copolymer
formulation.
[0425] The block copolymer formulation was prepared as follows.
Diblock copolymer DBP1 (0.01 g) was dissolved in PGMEA (1.24 g,
10,000 parts by weight) to form a 0.8 wt % stock solution of the
block copolymer based on total weight of the solution. The solution
was passed through a 0.2 micrometer polytetrafluoroethylene (PTFE)
filter. A separate stock solution was prepared by dissolving
SAP1-80 additive (0.1 g) in PGMEA (12.4 g) at 0.8 wt % SAP based on
total weight of the solution. The SAP solution was passed through a
0.2 micrometer PTFE filter. A desired amount of SAP stock solution
(see Table 13) was added to the block copolymer solution and the
mixture was stirred well to form a homogenous solution. The
resulting solution containing block copolymer and SAP was spin
coated on the patterned photoresist substrate described above.
After spin coating, the coated wafer was baked at a 170.degree. C.
for 5 minutes, and immediately cooled to room temperature. The
self-assembled domains of the block copolymer inside the guiding
pre-pattern trenches were analyzed with top down and cross section
SEM. The samples were etched with tetrafluoroethylene
(CF.sub.4/H.sub.2) gas using RIE for 5 seconds on the top surface
for top-down SEM and were subjected to perpendicular etch for 8
seconds at the cross section of the film for cross-section SEM. The
samples were subjected to 20 seconds of Au sputtering with 20 mA
current prior to SEM imaging.
[0426] Table 12 summarizes the block copolymer formulation of
Example 79.
TABLE-US-00013 TABLE 13 Coating Formulation SAP Stock Sol'n SAP BCP
Solution 0.8 wt % BCP Sol'n SAP UL BCP BCP SAP SAP Sol'n Amount BCP
SAP PGMEA wt % of Example Name Example. Name Ex. Name (g) (g) (g)
(mg) (g) dry solids 79 UL-2 1 DBP1 27 SAP1-80 1.250 0.1075 0.01
0.860 1.347 8.6
[0427] FIG. 16 is a set atomic force microscopy (AFM) images at two
magnifications of the self-assembled block copolymer film of
Example 79, showing perpendicular lamellae were formed in the
trench areas of the resist pattern.
Block Copolymer Formulations without SAP Additives
Examples 80-82
Comparative
[0428] Coating formulations using the block copolymers of Examples
1-3 were prepared without SAP additives. The following general
procedure is representative. A 1.2 wt % solution of block copolymer
in PGMEA was prepared as described above, and the resulting
solution was filtered through a 0.2 micrometer PTFE filter.
[0429] Table 14 summarizes the block copolymer formulations of
Examples 80-82 prepared without SAP additive.
TABLE-US-00014 TABLE 14 BCP Coating BCP BCP amount PGMEA
Formulation Example Example Name (g) (g) wt % BCP 80 1 DBP1 0.01
0.83 1.2 81 2 DBP-2 0.01 0.83 1.2 82 3 TBP1 0.01 0.83 1.2
Thin-Film Self-Assembly of Block Copolymers Formulations without
SAP Additives
Examples 83-85
Comparative
[0430] The following general procedure was used to prepare thin
films of block copolymer formulation Examples 80-82 lacking the SAP
additive on various underlayer coated substrates. The coating
formulation solution was spin coated on the underlayer coated
substrates at the desired spin rate (Table 15). After forming the
thin film, the coated wafer was baked at the specified time and
temperatures and immediately cooled to room temperature. The block
copolymer films were characterized by atomic force microscopy (AFM)
using a Digital Instruments 3100 AFM with a 1 N/m spring constant
silicon nitride cantilever operated in a tapping mode. Scan size
and speed were set at 2 micrometers.times.2 micrometers area and 1
Hz respectively.
[0431] Table 15 summarizes the coating and annealing conditions
used in Examples 83-85 and the resulting morphologies of the block
copolymer thin film after self-assembly.
TABLE-US-00015 TABLE 15 Coating and BCP Annealing conditions BCP
Spin Spin Annealing Annealing Formulation BCP speed time temp time
BCP Example Underlayer Example Name RPM (Sec) (.degree. C.) (min)
Morphology 83 UL-2 80 DBP1 2000 30 170 5 I/H 84 UL-16 81 DBP2 2000
30 170 5 I/H 85 UL-2 82 TBP1 2000 30 170 5 Flat
[0432] Each of the films of Table 15 displayed island/hole or
parallel cylinder morphology (undesirable). FIGS. 17-19 are AFM
height images of Examples 83-85, respectively.
Oleic Acid as Surface Active Material
Examples 86-93
Comparative
[0433] Thin film preparation and characterization of formulated
block copolymer compositions with oleic acid or decafluorosuberic
acid (DFS) as additives on substrates having underlayer UL-3.
[0434] The following general procedure was used to prepare thin
films of formulated diblock copolymer DBP1 (Example 1) with oleic
acid or decafluorosuberic acid (DFS) on UL-2 substrates. A solution
of DBP1 was prepared by dissolving the block copolymer (0.01 g) in
PGMEA (0.823 g) to form a 1.2 wt % solution based on total dry
solids. The solutions were passed through a 0.2 micrometer
polytetrafluoroethylene (PTFE) filter. A desired amount of oleic
acid or decafluorosuberic acid (DFS) was added to the block
copolymer solutions made above and the mixture was stirred well to
form a homogenous solution prior to spin coating the formulated
block copolymer solution on the underlayer coated substrates at the
desired spin rate. After forming the thin film, the coated wafer
was baked at a specified time and temperature (Table 16) and
immediately cooled to room temperature. The formulated block
copolymer films were characterized by atomic force microscopy (AFM)
using a Digital Instruments 3100 AFM with a 1 N/m spring constant
silicon nitride cantilever operated in a tapping mode. Scan size
and speed were set at 2 micrometer.times.2 micrometer area and 1 Hz
respectively.
[0435] Table 16 summarizes the formulated block copolymer thin film
self-assembly on UL-2 and the obtained morphologies. All the
samples of Table 16 showed island/hole (I/H) morphology. FIGS.
20-27 are AFM height images of Examples 86-93, respectively.
TABLE-US-00016 TABLE 16 Annealing Conditions Block Copol- Additive
Spin Spin Annealing Annealing UL Block ymer Conc. Additive wt % of
Speed time Temp Time Thin Film Example Name Copolymer (wt %) Name
dry solids RPM (Sec) .degree. C. (min) Morphology 86 UL-3 DBP1 1.2
Oleic Acid 1 2000 30 140 5 I/H 87 UL-3 DBP1 1.2 Oleic Acid 5 2000
30 140 5 I/H 88 UL-3 DBP1 1.2 Oleic Acid 10 2000 30 140 5 I/H 89
UL-3 DBP1 1.2 Oleic Acid 20 2000 30 140 5 I/H 90 UL-3 DBP1 1.2 DFS
5 2000 30 140 5 I/H 91 UL-3 DBP1 1.2 DFS 10 2000 30 140 5 I/H 92
UL-3 DBP1 1.2 DFS 20 2000 30 140 5 I/H 93 UL-3 TBP1 1.2 Oleic Acid
5 2000 30 170 5 I/H
[0436] These results indicate that the surface active
non-fluorinated carboxylic acid (oleic acid) and the fluorinated
carboxylic acid (DFS) were not effective additives in forming
perpendicular oriented lamellae.
Examples 94-95
Comparative
[0437] Thin film preparation using SAP additives having only
non-fluorinated hydrogen-bond donating groups (Example 94) or only
fluorinated non-hydrogen-bond donating groups (Example 95). The
substrates utilized underlayer UL-2.
[0438] A solution of DBP1 was prepared by dissolving the block
copolymer (0.01 g) in PGMEA (0.823 g) to form a 1.2 wt % solution
based on total dry solids. The solutions were passed through a 0.2
micrometer polytetrafluoroethylene (PTFE) filter. A desired amount
of poly(4-hydroxystyrene) (PHOST, Nippon Soda Company Ltd.,
Mn=5480, PDI=1.08) or PSAP1-80 from Example 25 (before
deprotection) was added to the block copolymer solutions made above
and the mixture was stirred well to form a homogenous solution
prior to spin coating the formulated block copolymer solution on
the underlayer coated substrates at the desired spin rate. After
forming the thin film, the coated wafer was baked at the desired
time and temperatures and immediately cooled to room temperature.
The formulated block copolymer films were characterized by atomic
force microscopy (AFM) using a Digital Instruments 3100 AFM with a
1 N/m spring constant silicon nitride cantilever operated in a
tapping mode. Scan size and speed were set at 2 micrometer.times.2
micrometer area and 1 Hz respectively. Table 17 summarizes the
formulated block copolymer thin film self-assembly on UL-2 and the
obtained morphologies. The samples of Table 17 showed either
island/hole or partially perpendicular lamellae morphology. FIGS.
28-29 are AFM height images of Examples 94-95, respectively.
TABLE-US-00017 TABLE 17 Annealing Conditions Block Copol- Additive
Spin Spin Annealing Annealing UL Block ymer Conc. Additive wt % of
Speed time Temp Time Thin Film Example Name Copolymer (wt %) Name
dry solids RPM Sec .degree. C. (min) Morphology 94 UL-2 DBP1 1.2
PHOST 5 2000 30 140 5 I/H 95 UL-2 DBP1 1.2 PSAP1-80 5 2000 30 140 5
Partially .perp. Example 25 lamellae
[0439] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
When a range is used to express a possible value using two
numerical limits X and Y (e.g., a concentration of X ppm to Y ppm),
unless otherwise stated the value can be X, Y, or any number
between X and Y.
[0440] The description of the present invention has been presented
for purposes of illustration and description, but is not intended
to be exhaustive or limited to the invention in the form disclosed.
Many modifications and variations will be apparent to those of
ordinary skill in the art without departing from the scope and
spirit of the invention. The embodiments were chosen and described
in order to best explain the principles of the invention and their
practical application, and to enable others of ordinary skill in
the art to understand the invention.
* * * * *