Title: Photosensitive polymer having cyclic backbone and resist composition containing the same
Abstract: A photosensitive copolymer has a weight-average molecular weight of 3,000 to 100,000 ##STR1##
wherein R1 is a hydrogen atom or methyl, R2 is an acid-labile tertiary alkyl group, and m/(m+n) is 0.5 to 0.8.
Patent Number: 6,964,839 Issued on 11/15/2005 to Choi, et al.
| Inventors:
|
Choi; Sang-jun (Seoul, KR);
Kim; Hyun-woo (Seongnam, KR);
Woo; Sang-gyun (Suwon, KR);
Moon; Joo-tae (Suwon, KR)
|
| Assignee:
|
Samsung Electronics Co., Ltd. (Suwon-si, KR)
|
| Appl. No.:
|
715041 |
| Filed:
|
November 20, 2000 |
Foreign Application Priority Data
| Nov 23, 1999[KR] | 1999-52225 |
| Current U.S. Class: |
430/270.1; 430/326; 430/905; 430/910; 525/337 |
| Intern'l Class: |
G03F 007/03.9 |
| Field of Search: |
430/2701,326,905,910
525/337
|
References Cited [Referenced By]
U.S. Patent Documents
| 4986648 | Jan., 1991 | Kobayashi et al.
| |
| 5405720 | Apr., 1995 | Hosaka et al.
| |
| 5616667 | Apr., 1997 | Sezi et al.
| |
| 5703186 | Dec., 1997 | Sezi et al.
| |
| 5738975 | Apr., 1998 | Nakano et al.
| |
| 6103450 | Aug., 2000 | Choi.
| |
| 6103845 | Aug., 2000 | Choi et al.
| |
| 6110637 | Aug., 2000 | Sezi et al.
| |
| 6114084 | Sep., 2000 | Kang et al.
| |
| 6171754 | Jan., 2001 | Choi et al.
| |
| 6239231 | May., 2001 | Fujishima et al.
| |
| 6242153 | Jun., 2001 | Sato et al.
| |
| 6277538 | Aug., 2001 | Choi et al.
| |
| 6280897 | Aug., 2001 | Asakawa et al.
| |
| 6280903 | Aug., 2001 | Kang et al.
| |
| 6284429 | Sep., 2001 | Kinsho et al.
| |
| 6300036 | Oct., 2001 | Choi et al.
| |
| 6312867 | Nov., 2001 | Kinsho et al.
| |
| 2001/0014428 | Aug., 2001 | Uetani et al.
| |
| 2001/0024763 | Sep., 2001 | Choi et al.
| |
| 2001/0044071 | Nov., 2001 | Hasegawa et al.
| |
| Foreign Patent Documents |
| 2357775 | Jul., 2001 | GB.
| |
| 5-9231 | Jan., 1993 | JP.
| |
| 5-11450 | Jan., 1993 | JP.
| |
| 10-153864 | Jun., 1998 | JP.
| |
Other References
Definition of copolymer The American Heritage Dictionary of the English Language,
Third Edition copyright 1992 by Houghton Mifflin Company.
R.D. Allen et al., "Cyclic Olefin Resist Polymers and Polymerizations for Improved
Etch Resistance," Journal of Photopolymer Science and Technology, vol. 12, No.
3 (1999), pp. 501-507.
Koji Nozaki et al., "A Novel Polymer for a 193-nm Resist," Journal of Photopolymer
Science and Technology, vol. 9, No. 3 (1996), pp. 509-522.
Robert D. Allen et al., "Single Layer Resits With enhanced Etch Resistance for
193 nm Lithography," Journal of Photopolymer Science and Technology, vol. 7, No.
3 (1994), pp. 507-516.
|
Primary Examiner: Thornton; Yvette C.
Attorney, Agent or Firm: Volentine Francos & Whitt, PLLC
Claims
1. A photosensitive copolymer having a weight-average molecular weight of 3,000
to 100,000 and consisting essentially of first and second monomers represented
by the following formulae:
![embedded image]()
wherein R
1 is a hydrogen atom or methyl, R
2 is an acid-labile
tertiary alkyl group, and m/(m+n) is 0.5 to 0.8, and
wherein R
2 is 2-methyl-2-norbornyl, 2-ethyl-2-norbornyl, 2-methyl-2
isobornyl, 2-ethyl-2-isobornyl, 8-methyl-8-tricyclo[5.2.1.0
2,6]decanyl,
or 8-ethyl-8-tricyclo[5.2.1.0
2,6]decanyl.
2. The photosensitive copolymer according to claim 1, wherein the photosensitive
polymer has a weight-average molecular weight of 5,000 to 30,000.
3. The photosensitive copolymer according to claim 1, wherein R
2 is
an alicyclic hydrocarbon group.
4. A resist composition comprising:
(a) a photosensitive copolymer having a weight-average molecular weight of 3,000
to 100,000 and consisting essentially of first and second monomers represented
by the following formulae:
![embedded image]()
wherein R
1 is a hydrogen atom or methyl, R
2 is an acid-labile
tertiary alkyl group, and m/(m+n) is 0.5 to 0.8, and wherein R
2 is 2-methyl-2-norbornyl,
2-ethyl-2-norbornyl, 2-methyl-2-isobornyl, 2-ethyl-2-isobornyl, 8-methyl-8-tricyclo[5.2.1.0
2,6]decanyl,
or 8-ethyl-8-tricyclo[5.2.1.0
2,6]decanyl; and
(b) a photoacid generator (PAG).
5. The resist composition according to claim 4, wherein the photosensitive polymer
has a weight-average molecular weight of 5,000 to 30,000.
6. The resist composition according to claim 4, wherein the PAG is contained
in an amount of 1.0 to 15% by weight based on the total weight of the copolymer.
7. The resist composition according to claim 6, wherein the PAG is selected from
the group consisting of triarylsulfonium salts, diaryliodonium salts, sulfonates
or mixtures thereof.
8. The resist composition according to claim 7, wherein the PAG is triphenylsulfonium
triflate, diphenyliodonium triflate, triphenylsulfonium nonaflate, diphenyliodonium
nonaflate, triphenylsulfonium antimonate, diphenyliodonium antimonate, di-t-butyl
diphenyliodonium triflate, N-succinimidyl triflate, 2,6-dinitrobenzyl sulfonate,
or a mixture thereof.
9. The resist composition according to claim 4, further comprising an organic base.
10. The resist composition according to claim 9, wherein the organic base is
contained in an amount of 0.01 to 2.0% by weight based on the total weight of the copolymer.
11. The resist composition according to claim 10, wherein the organic base is
triethylamine, triisobutylamine, trioctylamine, diethanolamine, triethanolamine
or a mixture thereof.
12. The resist composition according to claim 4, further comprising a surfactant.
13. The resist composition according to claim 12, wherein the surfactant is contained
in an amount of 50 to 500 ppm.
14. The resist composition according to claim 12, wherein the surfactant is polyether
or polysulfonate.
15. The resist composition according to claim 14, wherein the surfactant is poly(ethylene glycol).
16. The resist composition according to claim 4, wherein R
2 is an
alicyclic hydrocarbon group.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chemically amplified resist composition, and
more particularly, to a photosensitive polymer having a cyclic backbone, and to
a resist composition for an ArF excimer laser obtained therefrom.
2. Description of the Related Art
As semiconductor devices become highly integrated, fine pattern formation is
required
from photolithography processes used in the fabrication of such devices. Further,
as the capacities of semiconductor devices increase beyond 1 giga bit, a pattern
size having a design rule of less than 0.2 μm becomes necessary. This places
limitations on the use of conventional resist materials adapted for the KrF excimer
laser (wavelength: 248 nm). Thus, to permit a lower wavelength operation, new resist
materials capable of being developed using an ArF excimer laser (wavelength: 193
nm) have been developed for use in lithography processes.
Present resist materials that are commercially used in lithography processes
employing the ArF excimer laser suffer certain drawbacks when compared with more
conventional resist materials. The most common problems relate to transmittance
of the polymer and resistance to dry etching.
As widely known ArF resist materials, (meth)acrylate polymers are generally used.
In particular, the most common resist material is poly(methyl methacrylate-tert-butyl
methacrylate-methacrylic acid) terpolymer system manufactured by IBM, Inc. However,
such polymers have very weak resistance to dry etching.
Accordingly, to increase the resistance to dry etching, a polymer having
a backbone composed of an alicyclic compound such as an isobornyl group, an adamantyl
group or a tricyclodecanyl group, is used. However, the resulting resist still
exhibits weak resistance to dry etching.
Also, since the alicyclic compound is hydrophobic, in the case where the alicyclic
compound is contained in the terpolymer, the adhesion to underlying layers is deteriorated.
In an attempt to overcome the above-described problem, a tetrapolymer represented
by the following formula in which a carboxylic acid group is introduced to the
backbone of the polymer has been proposed (see
J. Photopolym. Sci. Technol.,
7(3), 507 (1994).).
![embedded image]()
However, the resist layer obtained from the polymer having the above structure
still has poor adhesion to underlying layers, and resistance to dry etching is
poor. Also, a developing solution that is generally usable for development must
be diluted before being used.
Alternatively, a methacrylate copolymer having an alicyclic protecting
group represented by the following formula has been proposed (see
J. Photopolym.
Sci. Technol., 9(3), 509 (1996).).
![embedded image]()
The resist layer obtained from the polymer having the above structure still has
poor resistance to dry etching. Also, severe line edge roughness is observed when
a line pattern is formed from the resist layer. Also, the manufacturing cost for
raw materials for preparing the copolymer is very high. In particular, in order
to improve an adhesion characteristic, a monomer having a lactone group is introduced
thereto. However, the monomer generally to costly for practical use. Thus, it is
desirable to introduce a new monomer with which an expensive monomer can be replaced
to facilitate commercial use as a resist material.
As another conventional polymer, a cycloolefine-maleic anhydride (COMA) alternating
polymer represented by the following formula has been proposed (see
J. Photopolym.
Sci. Technol., 12(3), 501 (1999).).
![embedded image]()
The resist layer obtained from the polymer having the above structure is poor
in terms of resolution, transmission, adhesion characteristic and yield. Also,
due to the structural characteristic of the backbone, the resist layer has a high
glass transition temperature of about 200° C. or higher. Thus, several problems
may be encountered in processes using the resist layer.
SUMMARY OF THE INVENTION
To solve the above problems, it is a feature of the present invention to provide
a photosensitive polymer which is relatively inexpensive to fabricate and which
has sufficiently increased resistance to dry etching while exhibiting an improved
adhesion characteristic to underlying layers.
It is another feature of the present invention to provide a resist composition
which provides for improved lithographic performance in a lithography process using
an ArF excimer laser.
Accordingly, to achieve the above features, there is provided a photosensitive
copolymer having a weight-average molecular weight of 3,000 to 100,000 and represented
by the following formula:
![embedded image]()
wherein R
1 is a hydrogen atom or methyl, R
2 is an acid-labile
tertiary alkyl group, and m/(m+n) is 0.5 to 0.8.
Preferably, the photosensitive copolymer has a weight-average molecular
weight of 5,000 to 30,000.
Also, R
2 is preferably an alicyclic hydrocarbon group, and more
preferably R
2 is 2-methyl-2-norbornyl, 2-ethyl-2-norbornyl, 2-methyl-2-isobornyl,
2-ethyl-2-isobornyl, 8-methyl-8-tricyclo[5.2.1.0
2,6]decanyl, 8-ethyl-8-tricyclo[5.2.1.0
2,6]decanyl,
2-methyl-2-adamantyl, or 2-ethyl-2-adamantyl.
According to another aspect of the present invention, there is provided
a resist composition including the photosensitive copolymer and a photoacid generator (PAG).
The PAG is preferably contained in an amount of 1.0 to 15% by weight based on
the total weight of the copolymer.
Preferably, the PAG is selected from the group consisting of triarylsulfonium
salts, diaryliodonium salts, sulfonates or mixtures thereof. More preferably, the
PAG is triphenylsulfonium triflate, diphenyliodonium triflate, triphenylsulfonium
nonaflate, diphenyliodonium nonaflate, triphenylsulfonium antimonate, diphenyliodonium
antimonate, di-t-butyl diphenyliodonium triflate, N-succinimidyl triflate, 2,6-dinitrobenzyl
sulfonate, or a mixture thereof.
The resist composition may further include an organic base. Preferably, the organic
base is contained in an amount of 0.01 to 2.0% by weight based on the total weight
of the copolymer.
The organic base is preferably triethylamine, triisobutylamine, trioctylamine,
diethanolamine, triethanolamine or a mixture thereof.
Also, the resist composition may further include a surfactant.
The surfactant is preferably contained in an amount of 50 to 500 ppm.
Preferably, the surfactant is polyether or polysulfonate, and more preferably,
the surfactant is poly(ethylene glycol).
According to the present invention, a resist composition which consists
of a photosensitive copolymer having a considerably reduced manufacturing cost,
and which has improved adhesion to underlying layers and sufficiently increased
resistance to dry etching, can be attained. Also, since the photosensitive polymer
has an appropriate glass transition temperature, the resist composition obtained
from the polymer exhibits improved lithographical performance when it is applied
to a photolithography process.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A photosensitive polymer according to an embodiment of the present invention
is
represented by the following formula (1):
[Formula (1)]
![embedded image]()
wherein R
1 is a hydrogen atom or methyl, R
2 is an acid-labile
group using acid generated during exposure, in particular, a saturated or unsaturated
alicyclic hydrocarbon of a tert-alkyl type. Examples of R
2 are bulky
tertiary alkyl groups having a saturated alicyclic hydrocarbon ring, such as 2-methyl-2-norbornyl,
2-ethyl-2-norbornyl, 2-methyl-2-isobornyl, 2-ethyl-2-isobornyl, 8-methyl-8-tricyclo[5.2.1.0
2,6]decanyl,
8-ethyl-8-tricyclo[5.2.1.0
2,6]decanyl, 2-methyl-2-adamantyl, and 2-ethyl-2-adamantyl.
The photosensitive polymer is a copolymer including maleic anhydride or a (meth)acrylate
monomer, and the composition ratio of the respective monomers can be adjusted so
as to attain a polymer having desired characteristics such as excellent adhesion
and wettability. In other words, in the above formula, m and n are adjustable according
to the ratio of the respective monomers mixed. Preferably, m/(m+n) equals 0.5 to 0.8.
Also, in order to prepare a polymer having desired properties, another (meth)acrylate
monomer may be further added to form a terpolymer.
The photosensitive polymer is a copolymer including maleic anhydride and a (meth)acrylate
monomer having a bulky alicyclic protecting group. The photosensitive polymer may
employ a maleic anhydride monomer, instead of a lactone monomer, which is expensive,
thereby greatly reducing the manufacturing cost and mitigating problems encountered
by the conventional (meth)acrylate polymer. Thus, the resist composition obtained
from the photosensitive polymer has excellent adhesion to underlying layers and
excellent resistance to dry etching. Also, compared to the conventional COMA copolymer,
the transmittance is noticeably enhanced and the yield is increased.
Also, the photosensitive polymer according to the present invention has an
appropriate glass transition temperature in the range of 140 to 180° C. Thus,
the resist layer prepared using the photosensitive polymer according to the present
invention has a sufficiently high annealing effect during baking, thereby reducing
the free volume thereof. Therefore, the stability against the ambient atmosphere
of the resist layer can be improved even with post-exposure delay (PED), thereby
improving the lithographic performance.
EXAMPLE 1
Synthesis of 8-ethyl-8-tricyclodecanol
A solution of 200 ml (1.0 mol) of ethyl magnesium bromide dissolved in diethyl
ether was put into a 500 ml three-necked round-bottom flask, 30 g (0.2 mol) of
tricyclodecan-8-one dissolved in diethyl ether was slowly dropped thereinto at
room temperature using a dropping funnel, and was then reacted in a reflux condition
for about 12 hours.
After the reaction was completed, the reactant was poured into excess water
and neutralized using HCl. Thereafter, a crude product was extracted using diethyl
ether and dried using MgSO
4. Then, the solvent was evaporated and a
desired product was separated from the crude product using column chromatography
(yield: 65%).
EXAMPLE 2
Synthesis of 8-ethyl-8-tricyclodecanyl acrylate
18 g (0.1 mol) of 8-ethyl-8-tricyclodecanol synthesized in Example 1 and 11 g
(0.11 mol) of triethylamine were dissolved in 200 ml of anhydrous tetrahydrofuran
(THF) and 10 g (0.11 mol) of acryloyl chloride was slowly added thereto at room
temperature, and then the reactant was reacted for about 12 hours.
After the reaction was completed, excess solvent was evaporated, and the reactant
was poured into excess water and neutralized using HCl. Thereafter, a crude product
was extracted using diethyl ether and dried using MgSO
4. Then, the solvent
was evaporated and a desired product was separated from the crude product using
column chromatography (yield: 75%).
EXAMPLE 3
Synthesis of 8-ethyl-8-tricyclodecanyl methacrylate
18 g (0.1 mol) of 8-ethyl-8-tricyclodecanol synthesized in Example 1 and 11 g
(0.11 mol) of triethylamine were dissolved in 200 ml of anhydrous THF and 0.11
mol of methacryloyl chloride was reacted in the same manner as in Example 2. Then,
a desired product was separated in the same manner as in Example 2 (yield: 75%).
EXAMPLE 4
Synthesis of 8-methyl-8-tricyclodecanyl acrylate
8-ethyl-8-tricyclodecanol was synthesized in the same manner
as in Example 1 using a methyl magnesium bromide solution, and then a desired product
was separated using 8-ethyl-8-tricyclodecanol in the same manner as in Example 2.
EXAMPLE 5
Synthesis of 2-methyl-2-adamantyl acrylate
17 g (0.1 mol) of 2-methyl-2-adamantanol and 11 g (0.11 mol) of triethylamine
were dissolved in 250 ml of anhydrous THF and 10 g (0.11 mol) of acryloyl chloride
was slowly added thereto at room temperature, and then the reactant was reacted
for about 12 hours.
After the reaction was completed, excess solvent was evaporated, and the reactant
was poured into excess water and neutralized using HCl. Thereafter, a crude product
was extracted using diethyl ether and dried using MgSO
4. Then, the solvent
was evaporated and a desired product was separated from the crude product using
column chromatography (yield: 75%).
EXAMPLE 6
Synthesis of 2-methyl-2-adamantyl methacrylate
17 g (0.1 mol) of 2-methyl-2-adamantanol and 11 g (0.11 mol) of triethylamine
were dissolved in 250 ml of anhydrous THF and 0.11 mol of methacryloyl chloride
was slowly added thereto at room temperature, and then the reactant was reacted
for about 12 hours.
Thereafter, a desired product was separated in the same manner as in
Example 5 (yield: 75%).
EXAMPLE 7
Synthesis of 2-methyl-2-isobornyl acrylate
A solution of 0.2 mol of camphor dissolved in diethyl ether was slowly dropped
into 200 ml of a solution of 1.0 mol of methyllithium dissolved in diethyl ether
at room temperature using a dropping funnel and reacted for about 2 hours, and
then 20 g (0.22 mol) of acryloyl chloride was slowly added thereto at room temperature,
and then the reactant was reacted in a reflux condition for about 12 hours.
After the reaction was completed, the reactant was poured into excess water
and neutralized using H
2SO
4. Thereafter, a crude product
was extracted using diethyl ether and dried using MgSO
4. Then, the solvent
was evaporated and a desired product was separated from the crude product using
vacuum distillation (yield: 65%).
EXAMPLE 8
Synthesis of 2-methyl-2-norbornyl acrylate
A solution of 0.2 mol of norcamphor dissolved in diethyl ether was slowly dropped
into 200 ml of a solution of 1.0 mol of methyllithium dissolved in diethyl ether
at room temperature using a dropping funnel and reacted for about 2 hours, and
then 20 g (0.22 mol) of acryloyl chloride was slowly added thereto at room temperature,
and then the reactant was reacted in a reflux condition for about 12 hours.
After the reaction was completed, a desired product was separated in the same
manner as in Example 7 (yield: 65%).
EXAMPLE 9
Synthesis of copolymer
##STR2##
7.03 g (30 mmol) of 8-ethyl-8-tricyclodecanyl acrylate synthesized in Example
2, 5.88 g (60 mmol) of maleic anhydride and azobis(isobutyronitrile) (AlBN) (4
mol %) were dissolved in 13 g of anhydrous THF, and purged using nitrogen gas for
about 1 hour. Thereafter, the reactant was polymerized at 700° C. for about
24 hours.
After the polymerization was completed, the reactant was slowly dropped into
excess n-hexane to be precipitated, dissolved again in THF and reprecipitated twice
in a co-solvent (n-hexane:isopropylalcohol=1:1). Then, the precipitate was dried
in a vacuum oven maintained at 50° C. for about 24 hours to obtain a desired
polymer (yield: 70%).
The weight-average molecular weight (Mw) and polydispersity of the obtained product
were 8,900 and 1.8, respectively.
EXAMPLE 10
Synthesis of Copolymer
30 mmol of 8-ethyl-8-tricyclodecanyl methacrylate synthesized in Example 3, 60
mmol of maleic anhydride and AlBN (4 mol %) were dissolved in 15 g of anhydrous
THF and polymerization was carried out in the same manner as in Example 9.
After polymerization was completed, a desired polymer was obtained in the same
manner as in Example 9 (yield: 65%).
The weight-average molecular weight (Mw) and polydispersity of the obtained product
were 7,300 and 1.9, respectively.
EXAMPLE 11
Synthesis of Copolymer
30 mmol of 8-methyl-8-tricyclodecanyl acrylate synthesized in Example 4, 60 mmol
of maleic anhydride and AlBN (4 mol %) were dissolved in 15 g of anhydrous THF
and polymerization was carried out in the same manner as in Example 9.
After polymerization was completed, a desired polymer was obtained in the same
manner as in Example 9 (yield: 70%).
The weight-average molecular weight (Mw) and polydispersity of the obtained product
were 8,300 and 1.8, respectively.
EXAMPLE 12
Synthesis of Copolymer
##STR3##
6.61 g (30 mmol) of 2-methyl-2-adamantyl acrylate synthesized in Example 5,
5.88 g (60 mmol) of maleic anhydride and AlBN (4 mol %) were dissolved in 12 g
of anhydrous THF, and purged using nitrogen gas for about 1 hour. Thereafter, the
reactant was polymerized at 70° C. for about 24 hours.
After the polymerization was completed, the reactant was slowly dropped into
excess n-hexane to be precipitated, dissolved again in THF and reprecipitated twice
in a co-solvent (n-hexane:isopropylalcohol=1:1). Then, the precipitate was dried
in a vacuum oven maintained at 50° C. for about 24 hours to obtain a desired
polymer (yield: 70%).
The weight-average molecular weight (Mw) and polydispersity of the obtained product
were 9,100 and 1.8, respectively.
EXAMPLE 13
Synthesis of Copolymer
30 mmol of 2-methyl-2-isobornyl acrylate synthesized in Example 7, 60 mmol of
maleic anhydride and AlBN (4 mol %) were dissolved in 13 g of anhydrous THF and
then polymerization was carried out in the same manner as in Example 12, to obtain
a polymer (yield: 70%).
The weight-average molecular weight (Mw) and polydispersity of the obtained product
were 7,800 and 1.9, respectively.
EXAMPLE 14
Synthesis of Copolymer
30 mmol of 2-methyl-2-norbornyl acrylate synthesized in Example 8, 60 mmol of
maleic anhydride and AlBN (4 mol %) were dissolved in 13 g of anhydrous THF and
polymerization was carried out in the same manner as in Example 12, to obtain a
polymer (yield: 70%).
The weight-average molecular weight (Mw) and polydispersity of the obtained product
were 8,100 and 1.9, respectively.
EXAMPLE 15
Synthesis of Terpolymer
35 mmol of 8-ethyl-8-tricyclodecanyl methacrylate synthesized in Example 3, 50
mmol of maleic anhydride, 5 mmol of methacrylic acid and AlBN (4 mol %) were dissolved
in 15 g of anhydrous THF, and polymerization was carried out in the same manner
as in Example 12, to obtain a terpolymer represented by the following formula (yield:
70%).
![embedded image]()
The weight-average molecular weight (Mw) and polydispersity of the obtained product
were 7,400 and 1.9, respectively.
EXAMPLE 16
Patterning Process Using Resist Composition
Herein below, the following processes were used for preparing the resist compositions
used in a patterning process.
A polymer selected from the polymers synthesized in Examples 9 through 15 (12
to
15% by weight of solid matter based on the total weight of a solvent to be obtained)
and various types of photoacid generator (PAG) were dissolved in a solvent, and
0.01 to 2.0% by weight of an organic base made of amine (based on the total weight
of the polymer) was added thereto to completely dissolve the reactants.
Examples of the PAG include inorganic onium salts (0.5 to 3.0% by weight
based on the total weight of polymer) and organic sulfonates (1.0 to 10% by weight
based on the total weight of polymer), or a mixture of at least two of theses materials.
Examples of the solvent include propylene glycol monomethyl ether acetate
(PGMEA) and ethyl lactate (EL), or a mixture of at least two of these materials.
Thereafter, the solution was filtered using a 0.2 μm membrane filter
to obtain a resist composition.
Then, for a patterning process using the resist composition obtained by the
above method, the following processes were used.
A silicon wafer having a silicon oxide film formed thereon was prepared and treated
with hexamethyldisilazane (HMDS). Then, the resist composition was coated on the
silicon oxide film to a thickness of about 0.3 to 0.5 μm.
The wafer having the resist composition coated thereon was pre-baked at a temperature
of 100 to 140° C. for 60 to 120 seconds and exposed to light using a light
source such as DUV, E-beam or X-ray. Then, post exposure baking (PEB) was performed
at a temperature of 100 to 150° C. for 60 to 120 seconds.
Thereafter, the resultant was developed using 2.38 wt % of tetramethylammonium
hydroxide (TMAH) solution for about 10 to 90 seconds. As a result, the silicon
oxide film was etched with a predetermined etching gas, for example, halogen gas
or C
xF
y gas, using the obtained resist pattern as a mask.
Subsequently, the resist pattern remaining on the silicon wafer was removed using
a stripper to form a desired silicon oxide pattern.
Next, detailed examples of forming patterns using the resist composition prepared
in the same method as in Example 16 will be described.
EXAMPLE 16-1
A resist composition was prepared using 1.0 g of polymer synthesized in Example
9,15 mg of triphenylsulfonirum triflate (TPSOTf) as a PAG and 2 mg of triisobutylamine
as an organic base were completely dissolved in 8.0 g of PGMEA and then filtered
using a 0.2 μm membrane filter to obtain a resist composition. The obtained
resist composition was coated on a wafer to a thickness of about 0.3 μm.
Thereafter, the wafer having the resist composition coated thereon was
pre-baked at a temperature of 130° C. for 90 seconds and exposed to light
using an ArF excimer laser having a numerical aperture (NA) of 0.6 and a of 0.7.
Then, post exposure baking (PEB) was performed at a temperature of 130° C.
for 90 seconds.
The resultant was developed using 2.38 wt % of TMAH solution for about 60 seconds
to form a resist pattern.
When an exposure dose was about 15 mJ/cm
2, it was observed that a
0.20 μm line and space pattern was obtained.
EXAMPLE 16-2
A resist composition was prepared using 1.0 g of polymer synthesized in Example
9,10 mg of TPSOTf and 20 mg of N-succinimidyl triflate as PAGs and 4 mg of triisobutylamine
as an organic base were completely dissolved in 8.0 g of PGMEA and then filtered
using a 0.2 μm membrane filter to obtain a resist composition. The obtained
resist composition was coated on a wafer to a thickness of about 0.3 μm.
Thereafter, a resist pattern was formed in the same manner as in Example 16-1.
When an exposure dose was about 20 mJ/cm
2, it was observed that a
0.20 μm line and space pattern was obtained.
EXAMPLE 16-3
A resist composition was prepared using 1.0 g of polymer synthesized in Example
12, 15 mg of TPSOTf as a PAG and 2 mg of triisobutylamine as an organic base were
completely dissolved in 8.0 g of PGMEA and then filtered using a 0.2 μm membrane
filter to obtain a resist composition. The obtained resist composition was coated
on a wafer to a thickness of about 0.3 μm.
Thereafter, a resist pattern was formed in the same manner as in Example 16-1.
When an exposure dose was about 18 mJ/cm
2, it was observed that a
0.20 μm line and space pattern was obtained.
EXAMPLE 16-4
Poly(ethylene glycol) having a weight-average molecular weight of 2,000
as a surfactant was added to the resist compositions obtained in Examples 16-1
through 16-3 in an amount of about 200 ppm and then a resist pattern was prepared
in the same manner as in Example 16-1.
When an exposure dose was about 15 to 20 mJ/cm
2, it was observed
that a μm line and space pattern was obtained.
Photomechanism of Copolymer
The photomechanism of a copolymer forming the resist composition obtained in
Example 16-1 is as follows.
![embedded image]()
As shown in the above photomechanism, the resist composition according to the
present invention exhibits a low solubility to a developing solution in an unexposed
region by a bulky alicyclic protecting group having a dissolution inhibition effect
acting on an alkaline developing solution, while exhibiting a high solubility in
an exposed region by a decomposition of the bulky alicyclic protecting group in
the presence of acid (H
+). Thus, a resist composition having high contrast
can be obtained, thereby achieving a high-resolution, high-sensitivity resist pattern.
Since the photosensitive polymer employs a maleic anhydride monomer, which
is inexpensive, the manufacturing cost is substantially reduced, thus overcoming
cost related problems encountered by the conventional (meth)acrylate polymers.
Further, the resist composition obtained from the photosensitive polymer has improved
adhesion to underlying layers and improved resistance to dry etching. Also, the
transmittance is noticeably enhanced and the yield is increased.
Also, the photosensitive polymer according to the present invention has an
appropriate glass transition temperature in the range of 140 to 180° C. Thus,
a resist layer prepared using the photosensitive polymer according to the present
invention exhibits a sufficiently high annealing effect during baking, thereby
reducing the free volume thereof. Therefore, the stability against ambient atmosphere
of the resist layer can be improved even with post-exposure delay (PED), thereby
improving the lithographic performance. Thus, the resist composition according
to the present invention can be useful in the manufacture of next generation semiconductor devices.
Although the present invention has been described in detail through preferred
embodiments, the invention is not limited thereto, and various modifications and
alterations within the spirit and scope of the invention are possible by those
skilled in the art.
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