U.S. patent application number 10/054837 was filed with the patent office on 2002-09-19 for organic anti-reflective coating material and its preparation.
This patent application is currently assigned to Hyundai Electronics Industries Co., Ltd.. Invention is credited to Baik, Ki-Ho, Hong, Sung-Eun, Jung, Min-Ho.
Application Number | 20020132183 10/054837 |
Document ID | / |
Family ID | 19582078 |
Filed Date | 2002-09-19 |
United States Patent
Application |
20020132183 |
Kind Code |
A1 |
Jung, Min-Ho ; et
al. |
September 19, 2002 |
Organic anti-reflective coating material and its preparation
Abstract
Polymers are provided having the following formula I, II or III:
1 Polymers of the present invention can be used to provide an
anti-reflective coating (ARC) material useful for
submicrolithography processes using 248 nm KrF, 193 nm ArF and 157
nm F.sub.2 lasers. The polymers contain chromophore sub
substituents which exhibit sufficient absorbance at wavelengths
useful for such submicrolithography process. The ARC prevents back
reflection from the surface of or lower layers in the semiconductor
devices and solves the problem of the CD being altered by the
diffracted and reflected light from such lower layers. The ARC also
eliminates the standing waves and reflective notching due to the
optical properties of lower layers on the wafer, and due to the
changes in the thickness of the photosensitive film applied
thereon. This results in the formation of stable ultrafine patterns
suitable for 64M, 256M, 1G, 4G and 16G DRAM semiconductor devices
and a great improvement in the production yield.
Inventors: |
Jung, Min-Ho; (Icheon-shi,
KR) ; Hong, Sung-Eun; (Seongnam-shi, KR) ;
Baik, Ki-Ho; (Icheon-shi, KR) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Hyundai Electronics Industries Co.,
Ltd.
San 136-1, Ami-ri, Bubal-eup
Yicheon-shi
KR
|
Family ID: |
19582078 |
Appl. No.: |
10/054837 |
Filed: |
January 22, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10054837 |
Jan 22, 2002 |
|
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|
09501049 |
Feb 9, 2000 |
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6368768 |
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Current U.S.
Class: |
430/270.1 |
Current CPC
Class: |
C07C 69/54 20130101;
C08F 20/18 20130101; C07C 2603/24 20170501 |
Class at
Publication: |
430/270.1 |
International
Class: |
G03F 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 23, 1999 |
KR |
99-14763 |
Claims
What is claimed is:
1. 1. A 9-anthracene alkylacrylate compound, represented by the
following chemical formula 39: 45(chemical formula 39) wherein,
R.sup.1 is hydrogen or --CH.sub.3; R.sub.1 to R.sub.9, which are
the same or different, each represents hydrogen, hydroxy,
methoxycarbonyl, carboxyl, hydroxymethyl, or a substituted or
unsubstituted, linear or branched C.sub.1-C.sub.6alkyl, alkane,
alkoxyalkyl or alkoxyalkane; and m is an integer of 1 to 4.
2. A method for preparing a 9-anthracene alkylacrylate compound
which comprises reacting a 9-anthracene alkylalcohol with an
acryloyl chloride compound in tetrahydrofuran, as shown in the
following reaction formula 4: 46(reaction formula 4) wherein, R is
hydrogen or --CH.sub.3; R.sub.1 to R.sub.9, which are the same or
different, each represents hydrogen, hydroxy, methoxycarbonyl,
carboxyl, hydroxymethyl, or a substituted or unsubstituted, linear
or branched C.sub.1-C.sub.6 alkyl, alkane, alkoxyalkyl or
alkoxyalkane; and n is an integer of 1 to 4.
3. 4-formylphenylmethacrylate, having the structure of the
following chemical formula 40: 47(chemical formula 40)
4. A method for preparing 4-formylphenylmethacrylate which
comprises reacting methacryloyl chloride with
4-hydroxybenzaldehyde.
5. A polymer represented by the following general formula I:
48(general formula I) wherein, R and R.sup.1, which are the same or
different, each represents hydrogen or --CH.sub.3; R.sub.1 to
R.sub.9, which are the same or different, each represents hydrogen,
hydroxy, methoxycarbonyl, carboxyl, hydroxymethyl, or a substituted
or unsubstituted, linear or branched C.sub.1-C.sub.6 alkyl, alkane,
alkoxyalkyl or alkoxyalkane; x and y each is a mole fraction in the
range from 0.01 to 0.99; and m is 1 or 2 and n is an integer of 2
to 4.
6. A polymer as set forth in claim 5, wherein R.sub.1-R.sub.9 each
is hydrogen; R.sup.1 is hydrogen; x and y each is 0.5; and m is 1
and n is 2.
7. A polymer as set forth in claim 5, wherein R.sub.1-R.sub.9 each
is hydrogen; R.sup.1 is hydrogen; x and y each is 0.5; and m is 1
and n is 3.
8. A polymer as set forth in claim 5, wherein R.sub.1-R.sub.9 each
is hydrogen; R.sup.1 is hydrogen; x and y each is 0.5; and m is 1
and n is 4.
9. A polymer as set forth in claim 5, wherein R.sub.1-R.sub.9 each
is hydrogen; R.sup.1 is --CH.sub.3; x and y each is 0.5; and m is 1
and n is 2.
10. A polymer as set forth in claim 5, wherein R.sub.1-R.sub.9 each
is hydrogen; R.sup.1 is --CH.sub.3; x and y each is 0.5; and m is 1
and n is 3.
11. A polymer as set forth in claim 5, wherein R.sub.1-R.sub.9 each
is hydrogen; R.sup.1 is --CH.sub.3; x and y each is 0.5; and m is 1
and n is 4.
12. A polymer as set forth in claim 5, wherein R.sub.1-R.sub.9 each
is hydrogen; R.sup.1 is hydrogen; x and y each is 0.5; and m is 1
and n is 2.
13. A polymer as set forth in claim 5, wherein R.sub.1-R.sub.9 each
is hydrogen; R.sup.1 is hydrogen; x and y each is 0.5; and m is 2
and n is 3.
14. A polymer as set forth in claim 5, wherein R.sub.1-R.sub.9 each
is hydrogen; R.sup.1 is hydrogen; x and y each is 0.5; and m is 2
and n is 4.
15. A method for preparing a copolymer (III) which comprises
reacting a 9-anthracene alkylacrylate type monomer (I) with a
hydroxyalkylacrylate type monomer (II) in the presence of an
initiator in a solvent, as shown in the following reaction formula
5: 49(reaction formula 5) wherein, R; R.sub.1 to R.sub.9; and m and
n have the meanings set forth in claim 5.
16. A polymer represented by the following general formula II:
50(general formula II) wherein, R, R.sup.I and R.sup.II, which are
the same or different, each is hydrogen or --CH.sub.3; R.sub.1 to
R.sub.9, which are the same or different, each represents hydrogen,
hydroxy, methoxycarbonyl, carboxyl, hydroxymethyl, or a substituted
or unsubstituted, linear or branched C.sub.1-C.sub.6 alkyl, alkane,
alkoxyalkyl or alkoxyalkane; x, y and z each is an mole fraction in
the range from 0.01 to 0.99; and m is 1 or 2 and n is an integer of
2 to 4.
17. A polymer as set forth in claim 16, wherein R.sub.1-R.sub.9
each is hydrogen; R.sup.1 is hydrogen; x, y and z are 0.3, 0.5 and
0.2, respectively; and m is 1 and n is 2.
18. A polymer as set forth in claim 16, wherein R.sub.1-R.sub.9
each is hydrogen; R.sup.1 is hydrogen; x, y and z are 0.3, 0.5 and
0.2, respectively; and m is 1 and n is 3.
19. A polymer as set forth in claim 16, wherein R.sub.1-R.sub.9
each is hydrogen; R.sup.1 is hydrogen; x, y and z are 0.3, 0.5 and
0.2, respectively; and m is 1 and n is 4.
20. A polymer as set forth in claim 16, wherein R.sub.1-R.sub.9
each is hydrogen; R.sup.1 is --CH.sub.3; x, y and z are 0.3, 0.5
and 0.2, respectively; and m is 1 and n is 2.
21. A polymer as set forth in claim 16, wherein R.sub.1-R.sub.9
each is hydrogen; R.sup.1 is --CH.sub.3; x, y and z are 0.3, 0.5
and 0.2; and m is 1 and n is 3.
22. A polymer as set forth in claim 16, wherein R.sub.1-R.sub.9
each is hydrogen; R.sup.1 is --CH3; x, y and z are 0.3, 0.5 and
0.2, respectively; and m is 1 and n is 4.
23. A method for preparing a copolymer (IV) which comprises
reacting a 9-anthracene alkylacrylate type monomer (I), a
hydroxyalkylacrylate type monomer (II) and methylmethacrylate (III)
with each other in the presence of an initiator in a solvent, as
shown in the following reaction formula 6: 51(reaction formula 6)
wherein, R, R.sup.I, and R.sup.III; R1 to R9; and m and n have the
meanings set forth in claim 16.
24. A polymer having repeating units of the following general
formula III: 52(general formula III) wherein, R.sup.III is hydrogen
or --CH.sub.3 and R.sub.0 is --CH.sub.3 or --CH.sub.2CH.sub.3.
25. A method for preparing a copolymer which comprises polymerizing
formylphenylmethacrylate to form a polymer and then reacting said
polymer with methanol or ethanol.
26. A method as set forth in claim 15 or 23, wherein each of the
monomers range, in mole fraction, from 0.01 to 0.99.
27. A method as set forth in claim 15 or 23, wherein the initiator
is selected from the group consisting of
2,2-azobisisobutyronitrile, acetylperoxide, laurylperoxide, and
t-butylperoxide.
28. A method as set forth in claim 15 or 23, wherein the solvent is
selected from the group consisting of tetrahydrofuran, toluene,
benzene, methylethyl ketone and dioxane.
29. A method as set forth in claim 15 or 23, wherein the
polymerization is carried out at a temperature of 50-90.degree.
C.
30. An anti-reflective coating composition comprising a polymer of
claim 5, 16 or 24.
31. An anti-reflective coating composition as set forth in claim
30, further comprising an anthracene derivative.
32. An anti-reflective coating composition as set forth in claim
31, wherein the anthracene derivative is selected from the group
consisting of anthracene, 9-anthracene methanol, 9-anthracene
carbonitrile, 9-anthracene carboxylic acid, dithranol,
1,2,10-anthracenetriol, anthraflavic acid, 9-anthraldehyde oxime,
9-anthraldehyde,
2-amino-7-methyl-5-oxo-5H-[1]-benzopyrano[2,3-b]pyridine-3-carbonitrile,
1-aminoanthraquinone, anthraquinone-2-carboxylic acid,
1,5-dihydroxyanthraquinone, anthrone, 9-anthryl trifluoromethyl
ketone, 9-alkylanthracene derivatives represented by the following
chemical formula 16, 9-carboxyl anthracene derivatives represented
by the following chemical formula 17, 1-carboxyl anthracene
derivatives represented by the following chemical formula 18, and
the combination thereof: 53(chemical formula 16) (chemical formula
17) (chemical formula 18) wherein, R.sub.11, R.sub.12, R.sub.13,
R.sub.14, and R.sub.15, which are the same or different, each
represents --H, --OH, --CH.sub.3, --CH.sub.2OH,
--(CH.sub.2)pCH.sub.3 wherein p is an integer of 1 to 3, or a
substituted or unsubstituted, linear or branched alkyl, alkane,
alkoxyalkyl or alkoxyalkane containing 1-5 carbon atoms.
33. A method for preparing an anti-reflective coating composition,
which comprises dissolving a polymer of claim 5, 16 or 24 in an
organic solvent and then adding thereto, an anthracene derivative
additive selected from the group consisting of anthracene,
9-anthracene methanol, 9-anthracene carbonitrile, 9-anthracene
carboxylic acid, dithranol, 1,2,10-anthracenetriol, anthraflavic
acid, 9-anthraldehyde oxime, 9-anthraldehyde,
2-amino-7-methyl-5-oxo-5H-[1]-benzopyrano[2,3-b
)]pyridine-3-carbonitrile, 1-aminoanthraquinone,
anthraquinone-2-carboxyl- ic acid, 1,5-dihydroxyanthraquinone,
anthrone, 9-anthryl trifluoromethyl ketone, 9-alkylanthracene
derivatives of the following chemical formula 16, 9-carboxyl
anthracene derivatives of the following chemical formula 17,
1-carboxyl anthracene derivatives of the following chemical formula
18, and combinations thereof. 54(chemical formula 16) (chemical
formula 17) (chemical formula 18) wherein, R.sub.11, R.sub.12,
R.sub.13, R.sub.14 and R.sub.15, which are the same or different,
each represents --H, --OH, --CH.sub.3, --CH.sub.2OH,
--(CH.sub.2)pCH.sub.3 wherein p is an integer of 1 to 3, or a
substituted or unsubstituted, linear or branched alkyl, alkane,
alkoxyalkyl or alkoxyalkane containing 1-5 carbon atoms.
34. A method as set forth in claim 33, wherein the anthracene
derivative additive is used at an amount of 0.1 to 30% by
weight.
35. A method as set forth in claim 33, wherein the organic solvent
is selected from the group consisting of ethyl 3-ethoxypropionate,
methyl 3-ethoxypropionate, cyclohexanone, and propyleneglycolmethyl
ether acetate.
36. An anti-reflective coating composition, comprising a polymer of
either claim 5 or 16, and a polymer of claim 24.
37. An anti-reflective coating composition as set forth in claim
36, further comprising an anthracene derivative.
38. An anti-reflective coating composition as set forth in claim
37, wherein the anthracene derivative is selected from the group
consisting of anthracene, 9-anthracene methanol, 9-anthracene
carbonitrile, 9-anthracene carboxylic acid, dithranol,
1,2,10-anthracenetriol, anthraflavic acid, 9-anthraldehyde oxime,
9-anthraldehyde,
2-amino-7-methyl-5-oxo-5H-[1]-benzopyrano[2,3-b]pyridine-3-carbonitrile,
1-aminoanthraquinone, anthraquinone-2-carboxylic acid,
1,5-dihydroxyanthraquinone, anthrone, 9-anthryl trifluoromethyl
ketone, 9-alkylanthracene derivatives of the following chemical
formula 16, 9-carboxyl anthracene derivatives of the following
chemical formula 17, 1-carboxyl anthracene derivatives of the
following chemical formula 18, and combinations thereof:
55(chemical formula 16) (chemical formula 17) (chemical formula 18)
wherein, R.sub.11, R.sub.12, R.sub.13, R.sub.14 and R.sub.15, which
are the same or different, each represents --H, --OH, --CH.sub.3,
--CH.sub.2OH, --(CH.sub.2)pCH.sub.3 wherein p is an integer of 1 to
3, or a substituted or unsubstituted, linear or branched alkyl,
alkane, alkoxyalkyl or alkoxyalkane containing 1-5 carbon
atoms.
39. A method for preparing an anti-reflective coating composition,
which comprises dissolving a mixture of a polymer of either claim 5
or 16 and a polymer of claim 24 in an organic solvent and then,
adding thereto an anthracene derivative additive selected from the
group consisting of anthracene, 9-anthracene methanol, 9-anthracene
carbonitrile, 9-anthracene carboxylic acid, dithranol,
1,2,10-anthracenetriol, anthraflavic acid, 9-anthraldehyde oxime,
9-anthraldehyde, 2-amino-7-methyl-5-oxo-5H-[1]-benzopyrano
[2,3-b]pyridine-3-carbonitrile, 1 -aminoanthraquinone,
anthraquinone-2-carboxylic acid, 1,5-dihydroxyanthraquinone,
anthrone, 9-anthryl trifluoromethyl ketone, 9-alkylanthracene
derivatives of the following chemical formula 16, 9-carboxyl
anthracene derivatives of the following chemical formula 17,
1-carboxyl anthracene derivatives of the following chemical formula
18, and combinations thereof. 56(chemical formula 16) (chemical
formula 17) (chemical formula 18) wherein, R.sub.11,R.sub.12,
R.sub.13, R.sub.14 and R.sub.15, which are the same or different,
each represents --H, --OH, --CH.sub.3, --CH.sub.2OH,
--(CH.sub.2)pCH.sub.3 wherein p is an integer of 1 to 3, or a
substituted or unsubstituted, linear or branched alkyl, alkane,
alkoxyalkyl or alkoxyalkane containing 1-5 carbon atoms.
40. A method as set forth in claim 39, wherein the anthracene
derivative additive is used at an amount of 0.1 to 30% by
weight.
41. A method as set forth in claim 39, wherein the organic solvent
is selected from the group consisting of ethyl 3-ethoxypropionate,
methyl 3-ethoxypropionate, cyclohexanone, and propyleneglycolmethyl
ether acetate.
42. A method for forming an anti-reflective coating, in which an
anti-reflective coating composition of claim 30, 31, 36 or 37 is
coated on a wafer and the wafer is subjected to hard baking at
80-300.degree. C.
43. A semiconductor device, fabricated by using an anti-reflective
coating of claim 30, 31, 36 or 37.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is related to Korean Patent Application No.
99-14763, filed Apr. 23, 1999, and takes priority from that
date.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an organic anti-reflective
coating material which allows the stable formation of ultrafine
patterns suitable for 64M, 256M, 1G, 4G and 16G DRAM semiconductor
devices. More particularly, the present invention relates to an
organic anti-reflective coating material which contains a
chromophore with high absorbance at the wavelengths useful for
submicrolithography. A layer of said anti-reflection material can
prevent back reflection of light from lower layers or the surface
of the semiconductor chip, as well as eliminate the standing waves
in the photoresist layer, during a submicrolithographic process
using a 248 nm KrF, 193 nm ArF or 157 nm F.sub.2 laser light
sources. Also, the present invention is concerned with an
anti-reflective coating composition comprising such a material, an
anti-reflective coating therefrom and a preparation method
thereof.
[0004] 2. Description of the Prior Art
[0005] During a submicrolithographic process, one of the most
important processes for fabricating highly integrated semiconductor
devices, there inevitably occur standing waves and reflective
notching of the waves due to the optical properties of lower layers
coated on the wafer and to changes in the thickness of the
photosensitive film applied thereon. In addition, the
submicrolithographic process generally suffers from a problem of
the CD (critical dimension) being altered by diffracted and
reflected light from the lower layers.
[0006] To overcome these problems, it has been proposed to
introduce a film, called an anti-reflective coating (hereinafter
sometimes referred to as "ARC"), between the substrate and the
photosensitive film. Generally, ARCs are classified as "organic"
and "inorganic" depending on the materials used, and as
"absorptive" and "interfering" depending on the mechanism of
operation. In microlithographic processes using I-line (365 nm
wavelength) radiation, inorganic ARCs, for example TiN or amorphous
carbon coatings, are employed when advantage is taken of an
absorption mechanism, and SiON coatings are employed when an
interference mechanism is employed. The SiON ARCs are also adapted
for submicrolithographic processes which use KrF light sources.
[0007] Recently, extensive and intensive research has been and
continues to be directed to the application of organic ARCs for
such submicrolithography. In view of the present development
status, organic ARCs must satisfy the following fundamental
requirements to be useful:
[0008] First, the peeling of the photoresist layer due to
dissolution in solvents in the organic ARC should not take place
when conducting a lithographic process. In this regard, the organic
ARC materials have to be designed so that their cured films have a
crosslinked structure without producing by-products.
[0009] Second, there should be no migration of chemical materials,
such as amines or acids, into and from the ARCs. If acids are
migrated from the ARC, the photosensitive patterns are undercut
while the egress of bases, such as amines, causes a footing
phenomena.
[0010] Third, faster etch rates should be realized in the ARC than
in the upper photosensitive film, allowing an etching process to be
conducted smoothly with the photosensitive film serving as a
mask.
[0011] Finally, the organic ARCs should be as thin as possible
while playing an excellent role in preventing light reflection.
[0012] Despite the variety of ARC materials, those which are
satisfactorily applicable to submicrolithographic processes using
ArF light have not been found, thus far. As for inorganic ARCs,
there have been reported no materials which can control the
interference at the ArF wavelength, that is, 193 nm. As a result,
active research has been undertaken to develop organic materials
which act as superb ARCs. In fact, in most cases of
submicrolithography, photosensitive layers are necessarily
accompanied by organic ARCs which prevent the standing waves and
reflective notching occurring upon light exposure, and eliminate
the influence of the back diffraction and reflection of light from
lower layers. Accordingly, the development of such an ARC material
showing high absorption properties against specific wavelengths is
one of the hottest and most urgent issues in the art.
[0013] U.S. Pat. No. 4,910,122 discloses an ARC which is interposed
under photosensitive layers to eliminate defects caused by
reflected light. The coating described therein can be formed
thinly, smoothly and uniformly and includes a light absorbing dye
which eliminates many of the defects caused by reflected light,
resulting in increased sharpness of the images in photosensitive
materials. These types of ARCs, however, suffer from disadvantages
of being complicated in formulation, extremely limited in material
selection and difficult to apply for photolithography using Deep
Ultraviolet (DUV) radiation. For example, the ARC of the above
reference comprises 4 dye compounds, including polyamic acid,
curcumin, Bixin and Sudan Orange G, and 2 solvents, including
cyclohexanone and N-methyl-2-pyrrolidone. This multi-component
system is not easy to formulate and may intermix with the resist
composition coated thereover, bringing about undesired results.
SUMMARY OF THE INVENTION
[0014] Therefore, it is an object of the present invention to
overcome the problems encountered in the prior art and to provide a
novel organic compound which can be used as an ARC for
submicrolithography using 193 nm ArF, 248 nm KrF and 157 nm F.sub.2
lasers.
[0015] It is another object of the present invention to provide a
method for preparing an organic compound which prevents the
diffusion and reflection caused by the light exposure in
submicrolithography.
[0016] It is a further object of the present invention to provide
an-ARC composition containing such a
diffusion/reflection-preventive compound and a preparation method
therefor.
[0017] It is a still further object of the present invention to
provide an ARC formed from such a composition and a preparation
method therefor.
[0018] The present invention pertains to acrylate polymer resins
which can be used as an ARC. Preferred polymer resins contain a
chromophore which exhibits high absorbance at 193 nm and 248 nm
wavelengths. A crosslinking mechanism between alcohol groups and
other functional groups is introduced into the polymer resins, so
that a crosslinking reaction takes place when coatings of the
polymer resins are "hard baked", thereby greatly improving the
formation, tightness and dissolution properties of the ARCs. In
particular, optimum crosslinking reaction efficiency and storage
stability are realized in the present invention. The ARC resins of
the present invention show superior solubility in all hydrocarbon
solvents, but are of so high solvent resistance after hard baking
that they are not dissolved in any solvent at all. These advantages
allow the resins to be coated without any problem, and the coating
prevents the undercutting and footing problems which can occur upon
forming images on photosensitive materials. Furthermore, the
coatings made of the acrylate polymers of the present invention are
higher in etch rate than photosensitive films, improving the etch
selection ratio therebetween.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The ARC resins of the present invention are selected from
the group consisting of acrylate polymers represented by the
following general formulas I, II and III: 2
[0020] wherein,
[0021] R, R.sup.I, R.sup.II, and R.sup.III are independently
hydrogen or a methyl group;
[0022] R.sub.0 is a methyl group or an ethyl group;
[0023] R.sub.1 to R.sub.9, which are the same or different, each
represents hydrogen, hydroxy, methoxycarbonyl, carboxyl,
hydroxymethyl, or a substituted or unsubstituted, linear or
branched C.sub.1-C.sub.6 alkyl, alkane, alkoxyalkyl or
alkoxyalkane;
[0024] x, y and z each is a mole fraction in the range from 0.01 to
0.99; and
[0025] m and n are independently an integer of 1 to 4. In a
preferred compound of Formula I, m is 1 or 2 and n is an integer of
1 to 4. In a preferred compound of Formula II, m is 1 or 2 and n is
an integer from 2 to 4.
[0026] The polymers of the present invention are designed to
provide greater absorbance at 193 nm and 248 nm wavelengths. To
accomplish this result, a chromophore substituent which is able to
absorb light at a wavelength of 193 nm as well as 248 nm is grafted
to the backbone of the polymer.
[0027] The polymer of the general formula I, as illustrated in the
following reaction formula 1, can be prepared by polymerizing
9-anthracenemethyl acrylate type monomers (I) and hydroxy
alkylacrylate type monomers (II) with the aid of an initiator in a
solvent. Each of the monomers has a mole fraction ranging from 0.01
to 0.99. 3
[0028] (reaction formula 1)
[0029] wherein R, R.sup.1, R.sub.1 to R.sub.9, x, y, m and n each
is as defined above.
[0030] The polymers of the general formula II can be prepared in a
similar manner to the polymers of the general formula I, using
9-anthracenemethyl acrylate type monomers (I), hydroxy
alkylacrylate type monomers (II) and methylmethacrylate monomers
(III) at a mole fraction of 0.01 to 0.99 for each monomer, as
illustrated in the following reaction formula 2: 4
[0031] (reaction formula 2)
[0032] wherein R, R.sup.I, R.sup.II, R.sub.1 to R.sub.9, x, y, z, m
and n each is as defined above.
[0033] The preparation of the polymer of the general formula III is
illustrated in the following reaction formula 3. As shown, first,
methacryloyl chloride (IV) is reacted with 4-hydroxy benzaldehyde
(V) to give 4-formylphenylmethacrylate (VI) which is then
polymerized with the aid of an initiator in a solvent, followed by
substituting the 4-formylphenyl groups with methanol or ethanol:
5
[0034] (reaction formula 3)
[0035] wherein R.sup.III and R.sub.0 each is as defined above.
[0036] For initiating the polymerization reaction for the polymers
of the general formulas I, II and III, ordinary initiators may be
used, with preference given to 2,2-azobisisobutyronitrile (AIBN),
acetylperoxide, laurylperoxide and t-butylperoxide. Also, ordinary
solvents may be used for the polymerization. Preferably the solvent
is selected from the group consisting of tetrahydrofuran, toluene,
benzene, methylethyl ketone and dioxane.
[0037] Preferably, the polymerization of the polymers of the
general formulas I and II is carried out at 50-90.degree. C.
[0038] The 9-anthracene alkyl acrylate type monomers (I) used to
prepare the polymers of the general formulas I and II, are novel
compounds which can be prepared by the reaction of 9-anthracene
alcohol with acryloyl chloride type compounds in a solvent, as
illustrated in the following reaction formula 4: 6
[0039] (reaction formula 4)
[0040] wherein R, R.sub.1 to R.sub.9, and n each is as defined
above. The hydroxyalkylacrylate type monomers (II) and
methylmethacrylate monomers (III) used in the above reactions are
commercially available, or they may be prepared using known
preparation methods.
[0041] Also, the present invention pertains to an ARC composition
which is based on a polymer mixture comprising the polymer of the
general formula I or II and the polymer of the general formula III,
in combination with at least one additive selected from the group
consisting of the anthracene derivatives shown in Table 1,
below.
1TABLE 1 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
[0042] In Table 1, R.sub.11, R.sub.12, R.sub.13, R.sub.14 and
R.sub.15 independently represent hydrogen, hydroxy, hydroxymethyl,
or substituted or unsubstituted linear or branched C.sub.1-C.sub.5
alkyl, alkane, alkoxyalkyl or alkoxyalkane.
[0043] ARC compositions according to the present invention may be
prepared by (i) dissolving a polymer of the general formula I or II
and a polymer of general formula III in a solvent to form a
solution; (ii) optionally adding a compound selected from Table 1
to said solution, at an amount of 0.1 to 30% by weight, and (iii)
filtering the solution.
[0044] Ordinary organic solvents may be used in preparing the
composition, with preference given to ethyl 3-ethoxypropionate,
methyl 3-methoxy propionate, cyclohexanone and propylene
methyletheracetate. The solvent is preferably used at an amount of
200 to 5000% by weight based on the total weight of the ARC resin
polymers used.
[0045] In another aspect of the present invention, an ARC is formed
from the coating composition described above. After being filtered,
this coating composition may be applied on a wafer in a
conventional manner and then "hard-baked"(i.e., heated to a
temperature of 100-300.degree. C. for 10-1000 seconds) to form a
crosslinked ARC. Quality semiconductor devices can be fabricated
using ARCs of the present invention, because this crosslinked
structure of the ARC offers optically stable light exposure
conditions when forming an image in the photosensitive layer.
[0046] It has been found that the ARCs of the present invention
exhibit high performance in submicrolithographic processes using
248 nm KrF, 193 nm ArF and 157 nm F.sub.2 lasers as light sources.
The same was also true when 157 nm E-beams, EUV (extreme
ultraviolet) and ion beams are used as light sources.
[0047] A better understanding of the present invention may be
obtained in light of following examples which are set forth to
illustrate, but are not to be construed to limit, the present
invention.
EXAMPLE I
Synthesis of
Poly[9-Anthracenemethylacrylate-(2-Hydroxyethylacrylate)] Binary
Copoloymer
[0048] Synthesis of 9-Anthracenemethylacrylate
[0049] 0.5 moles of 9-anthracene methanol and 0.5 moles of pyridine
are dissolved in tetrahydrofuran and then, 0.5 moles of acryloyl
chloride are added. After completion of the reaction, the product
is filtered out and extracted with ethyl acetate. The extract is
washed many times with distilled water and dried by distillation
under vacuum, to give 9-anthracenemethylacrylate, represented by
the following chemical formula 19. Yield 84%. 25
[0050] (chemical formula 19)
[0051] Synthesis of
Poly9-anthracenemethvlacrylate-(2-hydroxvethylacrylate- )l binary
copolymer
[0052] In a 500 ml round-bottom flask are placed 0.5 moles of
9-anthracenemethylacrylate and 0.5 moles of 2-hydroxyethylacrylate.
This mixture is added to 300 g of separately prepared
tetrahydroftiran (THF) with stirring. Thereafter, in the presence
of 0.1-3 g of 2,2'-azobisisobutyronitrile (AIBN), the reaction is
subjected to polymerization at 60-75.degree. C. for 5-20 hours in a
nitrogen atmosphere. After completion of the polymerization, the
solution is precipitated in ethyl ether or normal-hexane and the
precipitate is filtered out and dried to produce a
poly[9-anthracenemethylacrylate-(2-hy- droxyethylacrylate)]
copolymer, a polymer according to the present invention,
represented by the following chemical formula 20, at a yield of
83%. 26
[0053] (chemical formula 20)
EXAMPLE II
Synthesis of
Poly[9-Anthracenemethylacrylate-(3-Hydroxypropylacrylate)] Binary
Copolymer
[0054] In a 500 ml round-bottom flask are placed 0.5 moles of the
9-anthracenemethylacrylate synthesized in Example I and 0.5 moles
of 3-hydroxypropylacrylate. This mixture is added to 300 g of
separately prepared THF with stirring. Thereafter, in the presence
of 0.1-3 g of AIBN, the reaction is subjected to polymerization at
60-75.degree. C. for 5-20 hours in a nitrogen atmosphere. After
completion of the polymerization, the solution is precipitated in
ethyl ether or normal-hexane and the precipitate is filtered out
and dried to produce a
poly[9-anthracenemethylacrylate-(3-hydroxypropylacrylate)]
copolymer, a polymer according to the present invention,
represented by the following chemical formula 21, at a yield of
82%. 27
[0055] (chemical formula 21)
EXAMPLE III
Synthesis of
Poly[9-Anthracenemethylacrylate-(4-Hydroxybutylacrylate)]
Copolymer
[0056] In a 500 ml round-bottom flask are placed 0.5 moles of
9-anthracenemethylacrylate and 0.5 moles of 4-hydroxybutylacrylate.
This mixture is added to 300 g of separately prepared THF with
stirring. Thereafter, in the presence of 0.1-3 g of AIBN, the
reaction is subjected to polymerization at 60-75.degree. C. for
5-20 hours in a nitrogen atmosphere. After completion of the
polymerization, the solution is precipitated in ethyl ether or
normal-hexane and the precipitate is filtered out and dried to
produce a poly[9-anthracenemethylacrylate-(4-hy-
droxybutylacrylate)] copolymer, a polymer according to the present
invention, represented by the following chemical formula 22. Yield
81%. 28
[0057] (chemical formula 22)
EXAMPLE IV
Synthesis of
Poly[9-Anthracenemethylmethacrylate-(2-Hydroxyethylacrylate)]
Binary Copolymer
[0058] Synthesis of 9-Anthracenemethylmethacrylate
[0059] 0.5 moles of 9-anthracene methanol and 0.5 moles of pyridine
are dissolved in THF and then, 0.5 moles of methacryloyl chloride
are added. After completion of the reaction, the product is
filtered out and extracted with ethyl acetate. The extract is
washed many times with distilled water and dried by distillation
under vacuum, to give 9-anthracenemethylmethacrylate, represented
by the following chemical formula 23. Yield 83%. 29
[0060] (chemical formula 23)
[0061] Synthesis of
Poly9-anthracenemethylmethacrylate-(2-hydroxyethylacry- late)l
binary copolymer
[0062] In a 500 ml round-bottom flask are placed 0.5 moles of
9-anthracenemethylmethacrylate and 0.5 moles of
2-hydroxyethylacrylate. This mixture is added to 300 g of
separately prepared THF with stirring. Thereafter, in the presence
of AIBN, the reaction is subjected to polymerization at
60-75.degree. C. for 5-20 hours in a nitrogen atmosphere. After
completion of the polymerization, the solution is precipitated in
ethyl ether or normal-hexane and the precipitate is filtered and
dried to produce a poly[9-anthracenemethylmethacrylate-(2-hy-
droxyethylacrylate)] copolymer, a resin according to the present
invention, represented by the following chemical formula 24, at a
yield of 79%. 30
[0063] (chemical formula 24)
EXAMPLE V
Synthesis of
Poly[9-Anthracenemethylmethacrylate-(3-Hydroxypropylacrylate)- ]
Binary Copolymer
[0064] In a 500 ml round-bottom flask are placed 0.5 moles of the
9-anthracenemethylmethacrylate synthesized in Example IV and 0.5
moles of 3-hydroxypropylacrylate. This mixture is added to 300 g of
separately prepared THF with stirring. Thereafter, in the presence
of 0. 1-3 g of AIBN, the reaction is subjected to polymerization at
60-75.degree. C. for 5-20 hours in a nitrogen atmosphere. After
completion of the polymerization, the solution is precipitated in
ethyl ether or normal-hexane and the precipitate is filtered and
dried to produce a
poly[9-anthracenemethylmethacrylate-(2-hydroxypropylacrylate)]
copolymer, a polymer according to the present invention,
represented by the following chemical formula 25. Yield 81%. 31
[0065] (chemical formula 25)
EXAMPLE VI
Synthesis of
Poly[9-Anthracenemethylmethacrylate-(4-Hydroxybutylacrylate)]
Binary Copolymer
[0066] In a 500 ml round-bottom flask are placed 0.5 moles of the
9-anthracenemethylacrylate synthesized in Example IV and 0.5 moles
of 4-hydroxybutylacrylate. This mixture is added to 300 g of
separately prepared THF with stirring. Thereafter, in the presence
of 0.1-3 g of AIBN, the reaction is subjected to polymerization at
60-75.degree. C. for 5-20 hours in a nitrogen atmosphere. After
completion of the polymerization, the solution is precipitated in
ethyl ether or normal-hexane and the precipitate is filtered and
dried to produce a
poly[9-anthracenemethylmethacrylate-(4-hydroxybutylacrylate)]
copolymer, a polymer according to the present invention,
represented by the following chemical formula 26, at a yield of
81%. 32
[0067] (chemical formula 26)
EXAMPLE VII
Synthesis of
Poly[9-Anthracenemethylacrylate-(2-Hydroxyethylacrylate)-Meth-
ylmethacrylate] Ternary Copolymer
[0068] In a 500 ml round-bottom flask are placed 0.3 moles of
9-anthracenemethylacrylate, 0.5 moles of 2-hydroxyethylacrylate and
0.2 moles of methylmethacrylate. This mixture is added to 300 g of
separately prepared THF with stirring, after which, in the presence
of 0.1-3 g of AIBN, the reaction was subjected to polymerization at
60-75.degree. C. for 5-20 hours in a nitrogen atmosphere. After
completion of the polymerization, the solution is precipitated in
ethyl ether or normal-hexane and the precipitate is filtered and
dried to produce a
poly[9-anthracenemethylacrylate-(2-hydroxyethyl)-methylmethacrylate]
copolymer, a polymer according to the present invention,
represented by the following chemical formula 27. Yield 80%. 33
[0069] (chemical formula 27)
EXAMPLE VIII
Synthesis of
Poly[9-Anthracenemethylacrylate-(3-Hydroxypropylacrylate)-Met-
hylmethacrylate] Ternary Copolymer
[0070] In a 500 ml round-bottom flask are placed 0.3 moles of
9-anthracenemethylacrylate, 0.5 moles of 3-hydroxypropylacrylate
and 0.2 moles of methylmethacrylate. This mixture is added to 300 g
of separately prepared THF with stirring, after which, in the
presence of 0.1-3 g of AIBN, the reaction was subjected to
polymerization at 60-75.degree. C. for 5-20 hours in a nitrogen
atmosphere. After completion of the polymerization, the solution is
precipitated in ethyl ether or normal-hexane and the precipitate is
filtered and dried to produce a
poly[9-anthracenemethylacrylate-(3-hydroxypropyl)-methylmethacrylate]
copolymer, a polymer according to the present invention,
represented by the following chemical formula 28, at a yield of
82%. 34
[0071] (chemical formula 28)
EXAMPLE IX
Synthesis of
Poly[9-Anyhracenemethylacrylate-(4-Hydroxybutylacrylate)-Meth-
ylmethacrylate] Ternary Copolymer
[0072] In a 500 ml round-bottom flask are placed 0.3 moles of
9-anthracenemethylacrylate, 0.5 moles of 4-hydroxybutylacrylate and
0.2 moles of methylmethacrylate. This mixture is added to 300 g of
separately prepared THF with stirring, after which, in the presence
of 0.1-3 g of AIBN, the reaction is subjected to polymerization at
60-75.degree. C. for 5-20 hours in a nitrogen atmosphere. After
completion of the polymerization, the solution is precipitated in
ethyl ether or normal-hexane and the precipitate is filtered and
dried to produce a poly[9-anthracenemethylacrylate-(
4-hydroxybutyl)-methylmethacrylate] copolymer, a polymer according
to the present invention, represented by the following chemical
formula 29. Yield 81%. 35
[0073] (chemical formula 29)
EXAMPLE X
Synthesis of
Poly[9-Anthracenemethylmethacrylate-(2-Hydroxyethylacrylate)--
Methylmethacrylate] Ternary Copolymer
[0074] In a 500 ml round-bottom flask are placed 0.3 moles of the
9-anthracenemethylmethacrylate synthesized in Example IV, 0.5 moles
of 2-hydroxyethylacrylate and 0.2 moles of methylmethacrylate. This
mixture is added to 300 g of separately prepared THF with stirring,
after which, in the presence of 0.1-3 g of A1BN, the reaction is
subjected to polymerization at 60-75.degree. C. for 5-20 hours in a
nitrogen atmosphere. After completion of the polymerization, the
solution is precipitated in ethyl ether or normal-hexane and the
precipitate is filtered and dried to produce a
poly[9-anthracenemethylmethacrylate-(2-hy-
droxyethyl)-methylmethacrylate] copolymer, a polymer according to
the present invention, represented by the following chemical
formula 30. Yield 82%. 36
[0075] (chemical formula 30)
EXAMPLE XI
Synthesis of
Poly[9-Anthracenemethylmethacrylate-(3-Hydroxypropylacrylate)-
-Methylmethacrylate] Ternary Copolymer
[0076] In a 500 ml round-bottom flask are placed 0.3 moles of the
9-anthracenemethylacrylate synthesized in Example IV, 0.5 moles of
3-hydroxypropylacrylate and 0.2 moles of methylmethacrylate. This
mixture is added to 300 g of separately prepared THF with stirring,
after which, in the presence of 0.1-3 g of AIBN, the reaction is
subjected to polymerization at 60-75.degree. C. for 5-20 hours in a
nitrogen atmosphere. After completion of the polymerization, the
solution is precipitated in ethyl ether or normal-hexane and the
precipitate is filtered and dried to produce a
poly[9-anthracenemethylmethacrylate-(3
-hydroxypropyl)-methylmethacrylate] copolymer, a polymer according
to the present invention, represented by the following chemical
formula 31, at a yield of 81%. 37
EXAMPLE XII
Synthesis of
Poly[9-Anthracenemethylmethacrylate-(4-Hydroxybutylacrylate)--
Methylmethacrylate] Ternary Copolymer
[0077] In a 500 ml round-bottom flask are placed 0.3 moles of the
9-anthracenemethylacrylate synthesized in Example IV, 0.5 moles of
4-hydroxybutylacrylate and 0.2 moles of methylmethacrylate. This
mixture is added to 300 g of separately prepared THF with stirring,
after which, in the presence of 0.1-3 g of AIBN, the reaction is
subjected to polymerization at 60-75.degree. C. for 5-20 hours in a
nitrogen atmosphere. After completion of the polymerization, the
solution is precipitated in ethyl ether or normal-hexane and the
precipitate is filtered and dried to produce a
poly[9-anthracenemethylmethacrylate-(4-hy-
droxybutyl)-methylmethacrylate] copolymer, a polymer according to
the present invention, represented by the following chemical
formula 32. Yield 80%. 38
[0078] (chemical formula 32)
EXAMPLE XIII
Synthesis of
Poly[9-Anthraceneethylacrylate-(2-Hdroxyethylacrylate)] Binary
Copolymer
[0079] Synthesis of 9-Anthraceneethylacrylate
[0080] 0.5 moles of 9-anthracene ethanol and 0.5 moles of pyridine
are dissolved in THF and then, 0.5 moles of acryloyl chloride are
added. After completion of the reaction, the product is filtered
out and extracted with ethyl acetate. The extract is washed many
times with distilled water and dried by distillation under vacuum,
to give 9-anthracenemethylacrylate, represented by the following
chemical formula 33. Yield 80%. 39
[0081] (chemical formula 33)
[0082] Synthesis of
Poly[9-anthraceneethylacrylate-(2-hydroxyethylacrylate- )]
copolymer
[0083] In a 500 ml round-bottom flask are placed 0.5 moles of
9-anthraceneethylacrylate and 0.5 moles of 2-hydroxyethylacrylate.
This mixture is added to 300 g of separately prepared THF with
stirring. Thereafter, in the presence of 0.1-3 g of AIBN, the
reaction is subjected to polymerization at 60-75.degree. C. for
5-20 hours in a nitrogen atmosphere. After completion of the
polymerization, the solution is precipitated in ethyl ether or
normal-hexane and the precipitate is filtered out and dried to
produce a poly[9-anthraceneethylacrylate-(2-hyd-
roxyethylacrylate)] copolymer, a resin according to the present
invention, represented by the following chemical formula 34, at a
yield of 82%. 40
[0084] (chemical formula 34)
EXAMPLE XIV
Synthesis of
Poly[9-Anthraceneethylacrylate-(3-Hydroxypropylacrylate)] Binary
Copolymer
[0085] In a 500 ml round-bottom flask are placed 0.5 moles of the
9-anthraceneethylacrylate synthesized in Example XIII and 0.5 moles
of 3-hydroxypropylacrylate. This mixture is added to 300 g of
separately prepared THF with stirring. Thereafter, in the presence
of 0.1-3 g of AIBN, the reaction is subjected to polymerization at
60-75.degree. C. for 5-20 hours in a nitrogen atmosphere. After
completion of the polymerization, the solution is precipitated in
ethyl ether or normal-hexane and the precipitate is filtered out
and dried to produce a
poly[9-anthraceneethylacrylate-(3-hydroxypropylacrylate)]
copolymer, a polymer according to the present invention,
represented by the following chemical formula 35, at a yield of
81%. 41
[0086] (chemical formula 35)
EXAMPLE XV
Synthesis of
Poly[9-Anthraceneethylacrylate-(4-Hydroxybutylacrylate)]
Copolymer
[0087] In a 500 ml round-bottom flask are placed 0.5 moles of
9-anthraceneethylacrylate and 0.5 moles of 4-hydroxybutylacrylate.
This mixture is added to 300 g of separately prepared THF with
stirring. Thereafter, in the presence of 0. 1-3 g of AIBN, the
reaction solution is subjected to polymerization at 60-75.degree.
C. for 5-20 hours in a nitrogen atmosphere. After completion of the
polymerization, the solution is precipitated in ethyl ether or
normal-hexane and the precipitate is filtered and dried to produce
a poly[9-anthraceneethylacrylate-(4-hydroxy- butylacrylate)]
copolymer, a polymer according to the present invention,
represented by the following chemical formula 36. Yield 80%. 42
[0088] (chemical formula 36)
EXAMPLE XVI
Synthesis of Poly[4-(1,1 -Dimethoxymethyl)Phenylmethacrylate)]
[0089] Synthesis of poly[4-formyphenylmethacrylate]
[0090] In a 300 ml round-bottom flask, 31.3 g of (0.3 moles) of
methacryloyl are completely dissolved in 200 g of THF by stirring
and 26 g of pyridine are added. To this solution 36.6 g (0.3 moles)
of 4-hydroxybenzaldehyde are added dropwise, after which these
reactants are allowed to react for 24 hours or longer. The product
solution is washed with deionized water to separate an aqueous
layer from which the desired compound is extracted and dried.
[0091] 0.4 moles of the 4-formylphenylmethacrylate thus obtained
are placed, together with 300 g of THF, in a 500 ml round-bottom
flask and 0.1-3 g of AIBN are added thereto with stirring.
Polymerization is conducted at 60-75.degree. C. for 5-20 hours in a
nitrogen atmosphere. After completion of the polymerization, the
solution is precipitated in ethyl ether or normal hexane and the
precipitate is filtered and dried to provide a
poly[4-formylphenylmethacrylate] polymer at a yield of 80%.
[0092] Synthesis of poly[4-( 1,1
-dimethoxvmethvl)phenylmethacrylate]
[0093] In a 400 ml Erlenmeyer flask are placed 15 g of the polymer
obtained above and 200 ml of THF and then, 100 g of methanol are
added, together with 0.5 g of HCl, after which these reactants are
allowed to react at 60.degree. C. for about 12 hours. The product
solution is precipitated in ethyl ether or normal hexane and the
precipitate is filtered and dried to give
poly[4-(1,1-dimethoxymethyl)phenylmethacrylate- ], a polymer
according to the present invention, represented by the following
chemical formula 37. Yield 82%. 43
[0094] (chemical formula 37)
EXAMPLE XVII
Synthesis of Poly[4-(1,1-Diethoxymethyl)Phenylmethacrylate]
[0095] In a 400 ml Erlenmeyer flask are placed 15 g of the
poly(4-formylmethacrylate synthesized in Example XVI and 200 ml of
THF and then, 150 g of ethanol are added, together with 0.5 g of
HCl, after which these reactants are allowed to react at 60.degree.
C. for about 12 hours. The product solution is precipitated in
ethyl ether or normal hexane and the precipitate is filtered and
dried to give poly[4-(1, 1 -diethoxymethyl)phenylmethacrylate], a
resin according to the present invention, represented by the
following chemical formula 38. Yield 80%. 44
[0096] (chemical formula 38)
EXAMPLE XVIII
Preparation of Arc
[0097] A polymer prepared in each of Examples I to XV and a polymer
prepared in Example XVI or XVII are dissolved in propyleneglycol
methylether acetate (PGMEA). This solution, alone or in combination
with 0.1-30% by weight of at least one additive selected from the
compounds of the chemical formulas 1 to 18 in Table 1, is filtered,
coated on a wafer, and hard-baked at 100-300.degree. C. for
10-1,000 sec to form an ARC. A photosensitive material may be
applied on the ARC thus formed and imaged to ultrafine patterns in
the conventional manner.
[0098] As described hereinbefore, the ARC of the present invention,
which is obtained from a mixture comprising a polymer of the
general formula I or II and a polymer of the general formula III,
alone or in combination with an additive of chemical formulas I to
18 in Table 1, contains chromophore substituents sufficient to
exhibit absorbance at the wavelengths useful for
submicrolithography.
[0099] Particularly, the ARC of the present invention provides
maximal crosslinking reaction efficiency and storage stability. The
ARC polymer resins of the present invention show superior
solubility in all hydrocarbon solvents, but are of such high
solvent resistance after hard baking that they are not dissolved in
any solvent at all. These advantages allow the resins to be coated
without any problem, and the resulting coating prevents
undercutting and footing problems which may occur when forming
images on photosensitive materials. Furthermore, coatings made of
the acrylate polymers of the present invention are higher in etch
rate than photosensitive films, improving the etch selection ratio
therebetween.
[0100] Thus, ARCs of the present invention can play an excellent
role in forming ultrafine patterns. For example, it can prevent the
back reflection of light from lower layers or the surface of the
semiconductor element, as well as eliminate the standing waves
caused by light and the thickness changes in the photoresist layer
itself, during a submicrolithographic process using a 248 nm KrF,
193 nm ArF or 157 nm F2 laser. This results in the stable formation
of ultrafine patterns suitable for 64M, 256M, 1G, 4G and 16G DRAM
semiconductor devices and a great improvement in the production
yield.
[0101] The present invention has been described in an illustrative
manner, and it is to be understood the terminology used is intended
to be in the nature of description rather than of limitation. Many
modifications and variations of the present invention are possible
in light of the above teachings. Therefore, it is to be understood
that within the scope of the appended claims, the invention may be
practiced otherwise than as specifically described.
* * * * *