Title: Photosensitive polymer and chemically amplified photoresist composition containing the same
Abstract: The photosensitive polymer includes a first monomer which is norbornene ester having C1 to C12 aliphatic alcohol as a substituent, and a second monomer which is maleic anhydride. A chemically amplified photoresist composition, containing the photosensitive polymer, has an improved etching resistance and adhesion to underlying layer materials, and exhibits wettability to developing solutions.
Patent Number: 6,893,793 Issued on 05/17/2005 to Jung, et al.
| Inventors:
|
Jung; Dong-won (Yongin, KR);
Choi; Sang-jun (Seoul, KR);
Lee; Si-hyeung (Suwon, KR);
Lee; Sook (Seoul, KR)
|
| Assignee:
|
Samsung Electronics Co., Ltd. (Suwon-si, KR)
|
| Appl. No.:
|
383770 |
| Filed:
|
March 10, 2003 |
Foreign Application Priority Data
| Current U.S. Class: |
430/270.1; 430/905; 430/914 |
| Intern'l Class: |
G03F 007/00.4 |
| Field of Search: |
430/2701,905,914
|
References Cited [Referenced By]
U.S. Patent Documents
| 3715330 | Feb., 1973 | Nogami et al.
| |
| 6103450 | Aug., 2000 | Choi.
| |
| 6258508 | Jul., 2001 | Kim et al.
| |
| 6312868 | Nov., 2001 | Kong et al.
| |
| 6316162 | Nov., 2001 | Jung et al.
| |
| 2002/0091216 | Jul., 2002 | Lee et al.
| |
| Foreign Patent Documents |
| 2336845 | Mar., 1999 | GB.
| |
| 2332679 | Jun., 1999 | GB.
| |
| 11-2558802 | Sep., 1999 | JP.
| |
Primary Examiner: Ashton; Rosemary
Attorney, Agent or Firm: Volentine Francos, PLLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a divisional of and claims priority to application Ser. No. 10/218,637,
filed Aug. 15, 2002, now U.S. Pat. No. 6,593,441, which is a divisional of and
claims priority to application Ser. No. 09/628,499, filed Jul. 28, 2000, now U.S.
Pat. No. 6,472,120.
Claims
1. A chemically amplified photoresist composition comprising:
one or more photosensitive polymers each having an average-weight molecule weight
of 3,000 to 100,000, and selected from the group consisting of first through fifth
photosensitive polymers; and
a photoacid generator contained in an amount of 1 to 15% by weight based on the
total weight of the one or more photosensitive polymers, and
wherein the first photosensitive polymer includes a first monomer which is norbornene
ester having C
1 to C
12 aliphatic alcohol as a substituent,
a second monomer which is maleic anhydride, a third monomer selected from the group
consisting of norbornene carboxylic acid, norbornene ester having a C
6 to
C
20 alicyclic hydrocarbon group as a substituent, (meth)acrylic acid,
(meth)acrylate having C
1 to C
12 aliphatic alcohol as a substituent,
(meth)acrylate having an acid-labile group as a substituent, and (meth)acrylate
having a C
6 to C
20 alicyclic hydrocarbon group as a substituent;
wherein the second photosensitive polymer includes a first monomer selected from
the group consisting of norbornene ester having C
1 to C
12 aliphatic
alcohol as a substituent, norbornene carboxylic acid, norbornene having a C
1
to C
12 aliphatic hydrocarbon group with a carboxy group pendent
thereto a substituent, and norbornene having a C
1 to C
12 aliphatic
hydrocarbon group with a carboxylic anhydride group pendent thereto as a substituent,
a second monomer which is maleic anhydride, and a third monomer selected from the
group consisting of norbornene ester having a C
6 to C
20 aliphatic
hydrocarbon group as a substituent and (meth)acrylate having a C
6 to
C
20 aliphatic hydrocarbon group as a substituent;
wherein the third photosensitive polymer includes a first monomer which is norbornene
ester having C
1 to C
12 aliphatic alcohol as a substituent,
a second monomer which is maleic anhydride, a third monomer selected from the group
consisting of norbornene carboxylic acid, norbornene ester having a C
6 to
C
20 aliphatic hydrocarbon group as a substituent and norbornene ester
having an acid-labile group as a substituent, and a fourth monomer selected from
the group consisting of (meth)acrylic acid, (meth)acrylate having C
1 to
C
12 aliphatic alcohol as a substituent, (meth)acrylate having an acid-labile
group as a substituent and (meth)acrylate having an aliphatic hydrocarbon group
as a substituent;
wherein the fourth photosensitive polymer includes a first monomer which is norbornene
ester having C
1 to C
12 aliphatic alcohol as a substituent,
a second monomer which is maleic anhydride, a third monomer selected from the group
consisting of norbornene carboxylic acid, norbornene ester having a C
6 to
C
20 alicyclic hydrocarbon group as a substituent and an acid-labile
group pendent a the norbornene ester, and a fourth monomer which is (meth)acrylate
having a C
6 to C
20 alicyclic hydrocarbon group as a substituent;
and
wherein the fifth photosensitive polymer includes a first monomer selected from
the group consisting of norbornene having C
1 to C
2 aliphatic
alcohol a substituent, norbornene carboxylic acid, norbornene having a C
1
to C
12 aliphatic hydrocarbon group with a carboxy group pendent
thereto as a substituent, norbornene having a C
1 to C
12 aliphatic
hydrocarbon group with a carboxylic anhydride group pendent thereto as a substituent,
and norbornene ester having C
1 to C
12 aliphatic alcohol with
a carboxylic anhydride group pendent thereto as a substituent, a second monomer
which is maleic anhydride, a third monomer which is norbornene ester having an
acid-labile group as a substituent, and a fourth monomer which is norbornene ester
having a C
6 to C
20 alicyclic hydrocarbon group as a substituent.
2. The chemically amplified photoresist composition according to claim 1, wherein
the C
1 to C
12 aliphatic alcohol is secondary alcohol, wherein
the C
6 to C
20 alicyclic hydrocarbon group includes adamantyl,
norbornyl, isobornyl or naphtyl, wherein the acid-labile group pendent to the norbornene
ester includes t-butyl, 1-alkoxy ethyl or tetrahydropyranyl, wherein aliphatic
alcohol pendent to the (meth)acrylate as a substituent includes 2-hydroxyethyl,
and wherein the acid-labile group pendent to the (meth)acrylate includes t-butyl
or 2-methyladamantyl.
3. The chemically amplified photoresist composition according to claim 1, wherein
first monomer of the first photosensitive polymer is 2° propanol norbornene
ester, and wherein the third monomer of the second photosensitive polymer is adamantyl
(meth)acrylate, norbornyl (meth)acrylate, isobornyl (meth)acrylate, naphtyl (meth)acrylate,
t-butyl (meth)acrylate or 2-methyladamantyl (meth)acrylate;
wherein the third monomer of the second photosensitive polymer is adamantyl (meth)acrylate,
norbornyl (meth)acrylate, isobornyl (meth)acrylate, naphtyl (meth)acrylate or t-butyl
(meth)acrylate;
wherein the first monomer of the third photosensitive polymer is 2° propanol
norbornene ester, wherein the third monomer of the fourth photosenitive polymer
is t-butyl norbornene ester, and wherein the fourth monomer of the third photosensitive
polymer is adamantyl (meth)acrylate, norbornyl (meth)acrylate, isobornyl (meth)acrylate,
naphtyl (meth)acrylate, t-butyl (meth)acrylate or 2-methyladamantyl (meth)acrylate;
wherein the first monomer of the fourth photosensitive polymer is norbornene
methanol, wherein the third monomer of the fourth photosensitive polymer is t-butyl
norbornene ester, and wherein the fourth monomer of the fourth photosensitive polymer
is adamantyl (meth)acrylate, norbornyl (meth)acylate, isobornyl (meth)acrylate
or naphtyl (meth)acrylate; and
wherein the first monomer of the fifth photosensitive polymer is 2° propanol
norbornene ester, wherein the third monomer of the fifth photosenitive polymer
is t-butyl norbornene ester, and wherein the fourth monomer of the fifth photosensitive
polymer is adamantyl norbornene ester, norbornyl norbornene ester, isobornyl norbornene
ester or naphtyl norbornene ester.
4. The chemically amplified photoresist composition according to claim 1, wherein
the photoacid generator is a triarylsulfonium salt, a diaryliodonium salt, a sulfonate,
a N-hydroxysuccinimide salt or a mixture thereof.
5. The chemically amplified photoresist composition according to claim 4, wherein
triarylsulfonium salts include triphenylsulfonium triflate and triphenylsulfonium
antimonate, wherein diaryliodonium salts include diphenyliodonium triflate, diphenyliodonium
antimonate, methoxydiphenyliodonium triflate and di-t-butyldiphenyliodonium triflate,
and wherein sulfonates include 2,6-dinitro benzyl sulfonate and pyrogallol tris(alkyl-sulfonates).
6. The chemically amplified photoresist composition according to claim 1, further
comprising 0.01 to 2.0% by weight of an organic base based on the total weight
of the one or more photosensitive polymers.
7. The chemically amplified photoresist composition according to claim 6, wherein
the organic base is triethylamine, triisobutylamine, trioctylamine, diethanolamine
or triethanolamine.
8. The chemically amplified photoresist composition according to claim 1, further
comprising 1 to 50% by weight of a dissolution inhibitor based on the total weight
of the one or more photosensitive polymers.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photosensitive polymer and to a chemically
amplified photoresist composition containing the same.
This application is a counterpart of, and claims priority to, Korean Application
No. 99-31060, filed Jul. 29, 1999, the contents of which are incorporated herein
by reference.
2. Description of the Related Art
As semiconductor devices become highly integrated, photolithography processes
used in the fabrication of such devices must be capable of forming ultra-fine patterns.
For example, a sub-quarter micron or smaller sized pattern is needed in a semiconductor
memory device having a capacity exceeding 1 Gbit. As such, a photolithography technology
has been proposed which employs an argon fluoride (ArF) excimer laser as a new
type of light source. This is because the ArF laser exhibits a wavelength (193
nm) which is shorter than the wavelength (248 nm) of a conventional krypton fluoride
KrF excimer laser. Therefore, a demand has arisen for chemically amplified photoresist
polymers and photoresist compositions which are suitable for use with the ArF excimer laser.
In general, a chemically amplified photoresist composition for an ArF excimer
laser should exhibit the following characteristics: (1) transparency at a wavelength
of 193 nm; (2) excellent thermal properties (for example, high glass transition
temperature); (3) good adhesion to underlying (and overlying) film materials; (4)
high resistance to dry etching; and (5) easily capable of being developed using
developing solutions which are in widespread use in the manufacture of semiconductor
devices, for example, 2.38% by weight of tetramethyl ammonium hydroxide (TMAH).
However, a terpolymer comprising methylmethacrylate, t-butyl methacrylate
and methacrylic acid, which is a widely known chemically amplified photoresist
polymer for the ArF excimer laser, does not exhibit all of the above-mentioned
characteristics. In particular, the terpolymer has a very low resistance to dry
etching, a low adhesion to underlying film materials and low wettability for a
developing solution.
Recently, attempts have been made to increase the etching resistance of
a photosensitive polymer for the ArF excimer laser by introducing alicyclic compounds,
for example, isobornyl, adamantyl or tricyclodecanyl group, into the backbone of
the polymers. However, these polymers also have several disadvantages. For example,
their etching resistance is still not acceptable and their adhesion characteristics
to underlying films are still poor, which results in lifting of photoresist patterns.
SUMMARY OF THE INVENTION
It is an objective of the present invention to provide a photosensitive polymer
which is capable of being exposed using an ArF excimer laser, and which has an
improve etching resistance and an improved adhesion to an underlying film or substrate.
It is another objective of the present invention to provide a chemically amplified
photoresist composition containing the photosensitive polymer.
Accordingly, to achieve the above objective, there is provided a photosensitive
polymer including a first monomer which is norbornene ester having C
1
to C
12 aliphatic alcohol as a substituent, and a second monomer which
is maleic anhydride.
Preferably, the C
1 to C
12 aliphatic alcohol is
secondary alcohol.
The photosensitive polymer according to the present invention may further include
at least one third monomer selected from the group consisting of norbornene carboxylic
acid, norbornene ester having a C
6 to C
20 alicyclic ester
having C as a substituent, norbornene ester having an acid-labile group as a substituent,
(meth)acrylic acid, (meth)acrylate having C
1 to C
12 aliphatic
alcohol as a substituent, (meth)acrylate having an acid-labile group as a substituent,
and (meth)acrylate having a C
6 to C
20 alicyclic ester having
C as a substituent.
In the case where the third monomer is norbornene ester having a C
6
to C
20 alicyclic ester having a C group or (meth)acrylate having a C
6
to C
20 alicyclic ester as a substituent, the first monomer may
be norbornene having C
1 to C
12 aliphatic alcohol as a substituent,
norbornene carboxylic acid, norbornene having C
1 to C
12 aliphatic
ester having C group having carboxy group pendent thereto as a substituent, or
norbornene having C
1 to C
12 aliphatic ester having a C group
having a carboxylic anhydride group pendent thereto as a substituent.
According to another aspect of the present invention, there is provided
a photosensitive polymer including, in addition to the first and second monomers,
a third monomer selected from the group consisting of norbornene carboxylic acid,
norbornene ester having C
6 to C
20 aliphatic ester having
a C group as a substituent and norbornene ester having an acid-labile group as
a substituent, and a fourth monomer selected from the group consisting of (meth)acrylic
acid, (meth)acrylate having C
1 to C
12 aliphatic alcohol as
a substituent, (meth)acrylate having an acid-labile group as a substituent and(meth)acrylate
having an aliphatic ester having a C group as a substituent.
In the case where the third monomer is (meth)acrylate having C
6 to
C
20 alicyclic ester having a C group as a substituent, the first monomer
may be norbornene having C
1 to C
12 aliphatic alcohol as a
substituent, norbornene carboxylic acid, norbornene having C
1 to C
12
aliphatic ester having a C group having carboxy group pendent thereto as
a substituent, norbornene having C
1 to C
12 aliphatic ester
having a C group having a carboxylic anhydride group pendent thereto as a substituent,
and norbornene ester having C
1 to C
12 aliphatic alcohol having
a carboxylic anhydride group pendent thereto as a substituent.
Also, the present invention provides photosensitive polymer including a first
monomer selected from the group consisting of norbornene having C
1 to
C
12 aliphatic alcohol as a substituent, norbornene carboxylic acid,
norbornene having C
1 to C
12 aliphatic ester having a C group
having carboxy group pendent thereto as a substituent, norbornene having C
1
to C
12 aliphatic ester having a C group having a carboxylic anhydride
group pendent thereto as a substituent, and norbornene ester having C
1 to
C
12 aliphatic alcohol having a carboxylic anhydride group pendent thereto
as a substituent, a second monomer which is maleic anhydride, a third monomer which
is norbornene ester having an acid-labile group as a substituent, and a fourth
monomer which is norbornene ester having C
6 to C
20 alicyclic
ester having a C group as a substituent.
To accomplish another object of the present invention, there is provided a chemically
amplified photoresist composition including one or more photosensitive polymers
each having an average-weight molecular weight of 3,000 to 100,000, and selected
from the group consisting of first through sixth photosensitive polymers, and a
photoacid generator contained in an amount of 1 to 15% by weight based on the total
weight of the one or more photosensitive polymers.
The chemically amplified photoresist composition may further include 1 to 50%
by weight of a dissolution inhibitor based on the total weight of the one or more
photosensitive polymers. Also, the chemically amplified photoresist composition
may further include 0.01 to 2.0% by weight of an organic base based on the total
weight of the photosensitive polymer.
The photosensitive polymer according to the present invention has a cyclic backbone,
and a hydroxy group is bonded to the backbone. Thus, the etching resistance of
the photoresist composition containing the same is large and an adhesion to an
underlying film is excellent. In particular, in the case where a secondary alcohol
group is bonded to the backbone, the polymer is chemically stable so that it can
be stored for a long period of time.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A photosensitive polymer and a chemically amplified photoresist composition containing
the same according to the present invention will now be described. Also, a preferred
photolithography process using the chemically amplified photoresist composition
will be described. This invention may, however, be embodied in many different forms,
and these embodiments are provided so that this disclosure will be thorough and
complete, and will fully convey the scope of the invention to those skilled in
the art.
Photosensitive Polymer
A photosensitive polymer according to a first embodiment of the present invention
includes a first monomer which is norbornene ester having C
1 to C
12
aliphatic alcohol as a substituent and a second monomer which is maleic anhydride.
In order to increase the stability of the photosensitive polymer, the C
1 to
C
12 aliphatic alcohol is preferably secondary alcohol.
The photosensitive polymer according to a first embodiment of the present invention
is represented by the formula (1):
##STR1##
- wherein R1 is an oxycarbonyl having C1 to C12
aliphatic alcohol as a substituent and the weight average molecular weight
of the polymer is in the range of 3,000 to 100,000.
Preferably, the C
1 to C
12 aliphatic alcohol is
secondary alcohol. For example, 2° propanol can be used as the C
1 to
C
12 aliphatic alcohol.
The photosensitive polymer has a cyclic backbone, and a hydroxy group is bonded
to the backbone. Thus, the etching resistance of the photoresist composition containing
the same is large and an adhesion to an underlying film is excellent. In particular,
in the case where a secondary alcohol group is bonded to the backbone, the polymer
is chemically stable so that it has excellent durability.
A photosensitive polymer according to a second embodiment of the present invention
includes, in addition to the first monomer and the second monomer of the first
embodiment, at least one third monomer selected from the group consisting of norbornene
carboxylic acid, norbornene ester having a C
6 to C
20 alicyclic
ester having C as a substituent, norbornene ester having an acid-labile group as
a substituent, (meth)acrylic acid, (meth)acrylate having C
6 to C
20
aliphatic alcohol as a substituent, acid-labile group pendent to the (meth)acrylate,
and (meth)acrylate having a C
6 to C
20 alicyclic hydrocarbon
as a substituent.
Like in the first embodiment, the C
1 to C
12 aliphatic
alcohol is preferably secondary alcohol.
The C
6 to C
20 alicyclic hydrocarbon group is preferably
adamantyl, norbornyl, isobornyl or naphtyl, the acid-labile group pendent to the
norbornene ester is preferably t-butyl, 1-alkoxy ethyl or tetrahydropyranyl, the
(meth)acrylate having C
1 to C
12 aliphatic alcohol as a substituent
is preferably 2-hydroxyethyl, and the acid-labile group pendent to the (meth)acrylate
is preferably t-butyl or 2-methyladamantyl.
In particular, a suitable first monomer includes 2° propanol norbornene
ester,
and a suitable third monomer includes adamantyl (meth)acrylate, norbornyl (meth)acrylate,
isobornyl (meth)acrylate, naphtyl (meth)acrylate, t-butyl (meth)acrylate or 2-methyladamantyl (meth)acrylate.
The photosensitive polymer according to a third embodiment of the present invention
includes a first monomer selected from the group consisting of norbornene having
aliphatic alcohol as a substituent, norbornene carboxylic acid, norbornene having
a C
1 to C
12 aliphatic hydrocarbon group with a carboxy group
pendent thereto as a substituent; and norbornene having a C
1 to C
12
aliphatic hydrocarbon group with a carboxylic anhydride group pendent thereto
as a substituent; a second monomer which is maleic anhydride; and a third monomer
selected from the group consisting of norbornene ester having a C
6 to
C
20 alicyclic hydrocarbon group as a substituent and(meth)acrylate having
a C
6 to C
20 alicyclic hydrocarbon group as a substituent,
and the weight average molecular weight of the monomers is in the range of 3,000
to 100,000.
If the C
6 to C
20 alicyclic hydrocarbon group is bonded
to
the backbone of the polymer, the unexposed photosensitive polymer is not easily
dissolved in a developing solution. Thus, in the case where a photoresist layer
is made of such a photosensitive polymer, since the photoresist layer of the unexposed
region is not easily dissolved in a developing solution, a loss in the thickness
of a photoresist pattern (T
PR loss), which is encountered in the conventional
art, can be suppressed.
In particular, a suitable third monomer includes adamantyl (meth)acrylate, norbornyl
(meth)acrylate, isobornyl (meth)acrylate and naphtyl (meth)acrylate.
The photosensitive polymer according to a fourth embodiment of the present invention
includes a first monomer which is norbornene ester having C
1 to C
12
aliphatic alcohol as a substituent; a second monomer which is maleic anhydride;
a third monomer selected from the group consisting of norbornene carboxylic acid,
norbornene ester having a C
6 to C
20 alicyclic hydrocarbon
group as a substituent and acid-labile group pendent to the norbornene ester; and,
a fourth monomer selected from the group consisting of (meth)acrylic acid, (meth)acrylate
having C
1 to C
12 aliphatic alcohol as a substituent, (meth)acrylate
having an acid-labile group as a substituent, and (meth)acrylate having a C
6
to C
20 alicyclic hydrocarbon group as a substituent, and the weight
average molecular weight of the polymer is in the range of 3,000 to 100,000.
Preferably, a suitable first monomer includes 2° propanol norbornene
ester, a suitable third monomer includes t-butyl norbornene ester, and a suitable
fourth monomer includes adamantyl (meth)acrylate, norbornyl (meth)acrylate, isobornyl
(meth)acrylate, naphtyl (meth)acrylate, t-butyl (meth)acrylate or 2-methyladamantyl (meth)acrylate.
The photosensitive polymer according to a fifth embodiment of the present invention
includes a first monomer selected from the group consisting of norbornene having
C
1 to C
12 aliphatic alcohol as a substituent, norbornene
carboxylic acid, norbornene having a C
1 to C
12 aliphatic
hydrocarbon group with a carboxyl group pendent thereto as a substituent, and norbornene
having a C
1 to C
12 aliphatic hydrocarbon group with a carboxylic
anhydride pendent thereto as a substituent; a second monomer which is maleic anhydride;
a third monomer selected from the group consisting of norbornene carboxylic acid,
norbornene ester having a C
6 to C
20 alicyclic hydrocarbon
group as a substituent, and norbornene ester having an acid-labile group as a substituent;
and a fourth monomer which is (meth)acrylate having a C
6 to C
20
alicyclic hydrocarbon group as a substituent, and the weight average molecular
weight of the polymer is in the range of 3,000 to 100,000.
Preferably, a suitable first monomer includes norbornene methanol, and
a suitable third monomer includes t-butyl norbornene ester, suitable fourth monomer
includes adamantyl (meth)acrylate, norbornyl (meth)acrylate, isobornyl (meth)acrylate
or naphtyl (meth)acrylate.
The photosensitive polymer according to a sixth embodiment of the present invention
includes a first monomer which is norbornene having C
1 to C
12 aliphatic
alcohol as a substituent, norbornene carboxylic acid, norbornene having a C
1
to C
12 aliphatic hydrocarbon group with a carboxylic group pendent
thereto as a substituent, norbornene having a C
1 to C
12 aliphatic
hydrocarbon group with a carboxylic anhydride group pendent thereto as a substituent,
or norbornene ester having C
1 to C
12 aliphatic alcohol as
a substituent; a second monomer which is maleic anhydride; a third monomer which
is norbornene ester having an acid-labile group as a substituent; and a fourth
monomer which is norbornene ester having a C
6 to C
20 alicyclic
hydrocarbon group as a substituent, and the weight average molecular weight of
the polymer is in the range of 3,000 to 100,000.
Preferably, a suitable first monomer includes 2° propanol norbornene
ester, a suitable third monomer includes t-butyl norbornene ester, and a suitable
fourth monomer includes adamantyl norbornene ester, norbornyl norbornene ester,
isobornyl norbornene ester or naphtyl norbornene ester.
The photosensitive polymers according to the first through sixth embodiments
of the present invention can be represented by the formula (2):
##STR2##
- wherein R1 is a carboxy group, a C1 to C12
aliphatic alcohol group, a C1 to C12 aliphatic hydrocarbon
group having a carboxy group pendent thereto as a substituent, a C1 to
C12 aliphatic hydrocarbon group having a carboxylic anhydride group
pendent thereto as a substituent or a C1 to C12 aliphatic
alcohol oxycarbonyl; R2 is hydrogen, a C6 to C20 alicyclic
hydrocarbon group or an acid-labile group; R3 is hydrogen or methyl;
R4 is hydrogen, a C1 to C12 aliphatic alcohol,
an acid-labile group or a C6 to C20 alicyclic hydrocarbon
group; l, m, n, and p are integers, where l/(l+m+n+p) equals 0.05 to 0.5, m/(l+m+n+p)
equals 0.3 to 0.5, n/(l+m+n+p) equals 0.0 to 0.3, p/(l+m+n+p) equals to 0.0 to
0.4; and the weight average molecular weight of the polymers is preferably in the
range of 3,000 to 100,000.
As described in the first through sixth embodiments, R
1 is preferably
a hydroxymethyl group or a C
1 to C
12 aliphatic alcohol oxycarbonyl
group to improve adhesion to an underlying film. In particular, the C
1 to
C
12 aliphatic alcohol is secondary alcohol, preferably 2° hydroxypropyloxycarbonyl,
to improve the stability of the polymer.
Also, R
2 or R
4 is preferably a C
6 to C
20
alicyclic hydrocarbon group so that the photoresist layer of an unexposed
region may not be easily dissolved in a developing solution.
Usable C
6 to C
20 alicyclic hydrocarbon groups include
adamantyl, norbornyl, isobornyl or naphtyl.
Also, a monomer in which R
2 is an acid-labile group such as t-butyl
and a monomer in which R
2 is a C
6 to C
20 alicyclic
hydrocarbon group may be simultaneously used to further increase the etching resistance.
In order to increase a difference in the solubility of the photosensitive polymer
for a developing solution before and after exposure, that is, contrast, at least
one of R
2 and R
4 is preferably an acid-labile group. In R
2,
examples of the acid-labile group include t-butyl, 1-alkoxyethyl or tetrahydropyranyl,
and in R
4, examples of the acid-labile group include t-butyl or 2-methyladamantyl.
Since the backbone of the photosensitive polymer according to the present invention
has a cyclic structure, the etching resistance thereof is large. In the case where
a hydroxy group is bonded to the backbone, the polymer exhibits good adhesion to
underlying layers and high wettability to a developing solution. Also, in the case
where the alicyclic hydrocarbon group is bonded to the backbone, the etching resistance
is further increased and the solubility of the photoresist layer of an unexposed
region to the developing solution is reduced. Thus, it is possible to prevent the
thickness of a photoresist pattern from decreasing.
Chemically Amplified Photoresist Composition
A chemically amplified photoresist composition of the present invention includes
the above-described photosensitive polymer and a photoacid generator. The photoacid
generator is preferably contained in an amount of 1 to 15% by weight based on the
total weight of the photosensitive polymer. The photoacid generator is preferably
a substance that has high thermal stability. Therefore, suitable photoacid generators
include triarylsulfonium salts, diaryliodonium salts, sulfonates or N-hydroxysuccinimide
triflates. Examples of triarylsulfonium salts include triphenylsulfonium triflate
and triphenylsulfonium antimonate. Examples of diaryliodonium salts include diphenyliodonium
triflate, diphenyliodonium antimonate, methoxydiphenyliodonium triflate and di-t-butyldiphenyliodonium
triflate. Examples of sulfonates include 2,6-dinitro benzyl sulfonate and pyrogallol tris(alkyl-sulfonates).
Preferably, the photoresist composition of the present invention further
includes 0.01 to 2.0% by weight of organic base based on the total weight of the
photosensitive polymer. Suitable organic bases include triethylamine, triisobutylamine,
triisooctylamine, diethanolamine or triethanolamine. The organic base is added
for preventing a pattern from being deformed due to acidolysis of photoresist composition
forming unexposed regions after exposure, which results from diffusion of the acid
generated at the exposed regions into the unexposed regions.
Also, the photoresist composition according to the present invention preferably
further includes 1 to 50% by weight of a dissolution inhibitor based on the weight
of the photosensitive polymer. A material which has an acid-labile group is used
as the dissolution inhibitor such that the dissolution inhibitor in the exposed
region is easily dissolved in a developing solution.
In the case where the composition contains a dissolution inhibitor, an acid-labile
group is not necessarily contained in the photosensitive polymer. In the case where
the composition contains a photosensitive polymer having the acid-labile group
pendent thereto and a dissolution inhibitor, a difference in the solubility between
an exposed region and an unexposed region is noticeably increased, thereby improving
the contrast. Examples of the dissolution inhibitor include t-butyl lithocholate.
Method for Preparing Photosensitive Polymer
Synthesis of Monomer
1. Synthesis of Norbornene Ester Having C
1 to C
12 Aliphatic
Alcohol as a Substituent
Cyclopentadiene (I) is dissolved in an organic solvent and then C
1
to C
12 aliphatic alcohol substituted acrylate (II) is added thereto
to prepare norbornene ester (III) as expressed in the following reaction scheme
(1):
##STR3##
- wherein R0 is C1 to C12 aliphatic alcohol.
2. Synthesis of Norbornene Having C1 to C12 Aliphatic Alcohol
as a Substituent
5-norbornene-2-aldehyde (V) is dissolved in aliphatic alcohol
magnesium bromide (IV) solution to prepare norbornene having C
1 to C
12
aliphatic alcohol as a substituent (VI) by a substitution reaction, as expressed
in the following reaction scheme (2):
##STR4##
- wherein R0′ is an aliphatic hydrocarbon and y is an
integer from 1 to 10.
3. Synthesis of Norbornene Ester Having C6 to C20 Alicyclic
Hydrocarbon or an Acid-Labile Group as a Substituent
Cyclopentadiene is dissolved in an organic solvent and then acrylate
having C
6 to C
20 alicyclic hydrocarbon as a substituent or
acrylate having an acid-labile group as a substituent is added thereto to prepare
norbornene ester.
Synthesis of Polymer
A first monomer (VII) synthesized in the first or second method, a second monomer
(VIII), a third monomer (IX) synthesized by the third method, and a fourth monomer
(X) are dissolved in an organic solvent, for example, toluene, in a mixture ratio
of l:m:n:p, and then a polymerization initiator, for example, azobisisobutyronitrile
(AIBN) is added to carry out polymerization, thereby preparing a polymer, as expressed
in the following reaction scheme (3):
##STR5##
- wherein, in the case where n and p are each zero, l and m are equal
to each other, and R1 is a C1 to C12 aliphatic
alcohol oxycarbonyl group, and a polymer represented by the formula (1) is prepared.
Method for Preparing Chemically Amplified Photoresist Composition and Photolithography
Process Using the Same
The chemically amplified photoresist composition according to the present invention
is prepared by dissolving the photosensitive polymer prepared in the above-described
manner and a photoacid generator in an appropriate solvent and mixing the same.
Here, the photoacid generator is mixed in an amount of 1 to 15% by weight based
on the weight of the polymer. Also, it is preferable to complete the photoresist
composition by further dissolving 0.01 to 2.0% by weight of an organic base based
on the weight of the polymer.
The chemically amplified photoresist composition prepared in the above-described
manner can be used for a general photolithography process, and is particularly
suitable for forming a fine pattern to satisfy a design rule of 0.20 μm or
smaller when using an ArF excimer laser as an exposure light source.
First, the photoresist composition is coated on a substrate where a patterning
object material layer is formed to form a photoresist layer having a predetermined
thickness, preferably 0.2 to 2 μm. Since the photoresist composition according
to the present invention comprise a hydroxy group, it can be easily coated on the
substrate. Subsequently, pre-baking is carried out on the photoresist layer. The
pre-baking step is performed at a temperature of 70 to 160° C. for 30 to 360
seconds. After the pre-baking step, the photoresist layer is exposed using a mask
having a predetermined pattern, using an exposure light source having a wavelength
of 248 nm or less, preferably an ArF excimer laser having a wavelength of 193 nm.
Acid is generated from the photoacid generator contained in the photoresist layer
by exposure. The photosensitive polymer is acidolyzed by the catalytic action of
the thus-generated acid to form a lot of carboxy groups, as expressed in reaction
scheme 4. As a result, a large amount of hydrophilic groups, e.g., carboxy groups,
are produced in the exposed region of the photoresist layer. Thus, a noticeable
difference in the polarity of the photoresist layer is created between an exposed
region and an unexposed region. That is to say, contrast is noticeably increased.
##STR6##
The parentheses represent that R
2 and R
4 are not acidolyzed,
but are retained after exposure in the case where they are C
6 to C
20
alicyclic hydrocarbons.
After exposure, the photoresist layer is thermally treated for a short time
before development, which is referred to as a post-exposure-thermal treatment.
The post-exposure-thermal treatment is performed for the purpose of activating
acidolysis by the acidic catalyst, that is, for the purpose of increasing contrast
by further activating acidolysis of exposed regions by the acidic catalyst to acidolyze
ester contained in the photosensitive polymer into carboxy groups.
Next, development is performed using an appropriate developing solution to
complete a photoresist pattern. Here, the developing solution used is a developing
solution for general development processes, for example, 2.38% by weight of tetramethylammonium
hydroxide (TMAH). In the case where a C
6 to C
20 alicyclic
hydrocarbon is bonded to the backbone of the photosensitive polymer constituting
the photoresist layer, since the photoresist layer in the unexposed region is not
easily dissolved in the developing solution, the thickness of the photoresist layer
in the unexposed region is not reduced, unlike the conventional art.
After forming the photoresist pattern, a patterning object layer is etched
to form a desired pattern. The photoresist pattern of the present invention is
formed of a photoresist layer including a photosensitive polymer having a cyclic
backbone and a tertiary alicyclic hydrocarbon bonded as a substituent, and thus
the etching resistance thereof is large. Therefore, a pattern having a good profile,
that is, having a precise critical dimension, can be formed.
The present invention will now be described in more detail with reference to
the following examples. However, the invention should not be construed as limited
to these examples.
Synthesis of Monomer
EXAMPLE 1
Synthesis of 2-hydroxypropyl-5-norbornene ester
100 mL of THF is put in a round-bottom flask and then cooled to -24° C.
using an ice-salt bath, and 66.10 g (1 mol) of cyclopentadiene derived from dicyclopentadiene
by simple distillation was added thereto. Next, 130.14 g (1 mol) of 2 hydroxypropyl
acrylate was slowly dropped to be reacted at -24° C. for about 4 hours. Then,
the temperature of the reactant was slowly raised to room temperature to then be
reacted for about 24 hours and then a reactant product was separated using vacuum
distillation (yield: 85%).
EXAMPLE 2
Synthesis of t-butyl 5-norbornene ester
The reactant product was obtained in the same manner as in Example 1, except
that 128.17 g (1 mol) of t-butyl acrylate was used, instead of 2-hydroxypropyl
acrylate (yield: 87%).
EXAMPLE 3
Synthesis of 2-methyladamantyl acrylate
200 mL of diethyl ether was put into a round-neck flask, 41.5 g of 2-methyl-2-adamantanol
and 27.6 g of tetraethyl amine were added thereto and then 22.6 g of acryloyl chloride
was dropped. The reactant was reacted at room temperature for about 12 hours and
then filtered using diethyl ether. Subsequently, the solvent was removed by an
evaporator and then the reactant product was obtained using vacuum distillation
(yield: 55%).
Synthesis of Polymer
EXAMPLE 4
Synthesis of poly(2-hydroxypropyl-5-norbornene ester-maleic anhydride)
5.89 g of 2-hydroxypropyl-5-norbornene ester prepared in Example 1 and 2.94
g of maleic anhydride were completely dissolved in 4.27 g of anhydrous ethyl acetate.
0.15 g of AIBN Was added to the resultant, purged using nitrogen gas for about
2 hours and polymerized at a temperature of about 65° C. for about 24 hours.
After the polymerization was complete, the reactant material was precipitated
in an excess mixed solution (about 10 times) of n-hexane and diethyl ether in a
ratio of 2:1 and the precipitate was dissolved again in THF. Then, the resultant
was reprecipitated again in a mixed solution of n-hexane and diethyl ether in a
ratio of 2:1. The precipitate was filtered using a glass filter and then dried
in a vacuum oven maintained at about 50° C. for about 24 hours to separate
6.3 g of a polymer. The weight average molecular weight and polydispersity of the
obtained reactant product were 15,500 and 2.1, respectively.
EXAMPLE 5
Synthesis of poly(2-hydroxypropyl-5-norbornene ester-maleic anhydride-t-butyl methacrylate)
5.89 g of 2-hydroxypropyl-5-norbornene ester prepared in Example 1, 2.94 g of
maleic anhydride and 4.27 g of t-butyl methacrylate were completely dissolved in
50 g of anhydrous ethyl acetate. 0.15 g of AIBN was added to the resultant, purged
using nitrogen gas for about 2 hours and polymerized at a temperature of about
65° C. for about 24 hours.
Separation was carried out in the same manner as in Example 4 to separate
6.3 g of a polymer. The weight average molecular weight and polydispersity of the
obtained polymer were 16,500 and 2.1, respectively.
EXAMPLE 6
Synthesis of poly(5-norbornene-2-ol-maleic anhydride-t-butyl methacrylate)
Polymerization and separation were carried out in the same manner
as in Example 5 to separate a polymer, except that 50 mmol of 5-norbornene-2-ol
was used, instead of 2-hydroxypropyl-5-norbornene ester (yield: 55%). The weight
average molecular weight and polydispersity of the obtained polymer were 14,600
and 2.1, respectively.
EXAMPLE 7
Synthesis of poly(2-hydroxypropyl-5-norbornene ester-maleic anhydride-2-methyladamantyl acrylate)
With the exception that 6.6 g of 2-methyladamantyl acrylate prepared in Example
3 was used, instead of t-butyl methacrylate, the same procedure was carried out
in the same manner as in Example 5 to separate 10.2 g of a polymer. The weight
average molecular weight and polydispersity of the obtained reactant product were
17,100 and 1.9, respectively.
EXAMPLE 8
Synthesis of poly(2-hydroxypropyl-5-norbornene ester-maleic anhydride-t-butyl-5-norbornene ester)
1.96 g of 2-hydroxypropyl-5-norbornene ester prepared in Example 1, 6.86 g of
maleic anhydride and 11.66 g of t-butyl norbornene ester were completely dissolved
in 10 g of anhydrous ethyl acetate. 0.23 g of AIBN was added to the resultant,
purged using nitrogen gas for about 2 hours and polymerized at a temperature of
about 65° C. for about 24 hours.
Thereafter, separation was carried out in the same manner as in Example
4 to separate 9.1 g of a polymer. The weight average molecular weight and polydispersity
of the obtained polymer were 12,600 and 1.9, respectively.
EXAMPLE 9
Synthesis of poly(2-hydroxypropyl-5-norbornene ester-maleic anhydride-t-butyl
5-norbornene ester-t-butyl acrylate)
With the exception that 1.0 g of t-butyl acrylate was further used in addition
to three monomers of Example 8, and 11 g of anhydrous ethyl acetate and 0.24 g
of AIBN were used, the same procedure was carried out in the same manner as in
Example 8 to separate 11.2 g of a polymer. The weight average molecular weight
and polydispersity of the obtained reactant product were 17,100 and 1.9, respectively.
EXAMPLE 10
Synthesis of poly(2-hydroxypropyl-5-norbornene ester-maleic anhydride-t-butyl
5-norbornene ester-isobornyl acrylate)
3.96 g of 2-hydroxypropyl-5-norbornene ester, 13.73 g of maleic anhydride, 23.31
g of t-butyl 5-norbornene ester and 2.92 g of isobornyl acrylate were completely
dissolved in 22 g of anhydrous ethyl acetate. 0.48 g of AIBN was added to the resultant,
purged using nitrogen gas for about 2 hours and polymerized at a temperature of
about 65° C. for about 24 hours.
Thereafter, separation was carried out in the same manner as in Example
4 to separate 19.8 g of a polymer. The weight average molecular weight and polydispersity
of the obtained reactant product were 15,700 and 1.8, respectively.
EXAMPLE 11
Synthesis of poly(2-hydroxypropyl-5-norbornene ester-maleic anhydride-t-butyl
5-norbornene ester-2-methyladamantyl acrylate)
1.96 g of 2-hydroxypropyl-5-norbornene ester, 6.86 g of maleic anhydride, 11.66
g of t-butyl 5-norbornene ester and 1.54 g of 2-methyladamantyl acrylate were completely
dissolved in 21 g of anhydrous ethyl acetate. 0.24 g of AIBN was added to the resultant,
purged using nitrogen gas for about 2 hours and polymerized at a temperature of
about 65° C. for about 24 hours.
Thereafter, separation was carried out in the same manner as in Example
4 to separate 29.3 g of a polymer. The weight average molecular weight and polydispersity
of the obtained reactant product were 14,500 and 2.0, respectively.
EXAMPLE 12
Synthesis of poly(2-hydroxypropyl-5-norbornene ester-maleic anhydride-t-butyl
5-norbornene ester-isobornyl-5-norbornene ester)
1.96 g of 2-hydroxypropyl-5-norbornene ester, 6.86 g of maleic anhydride, 11.66
g of t-butyl 5-norbornene ester and 1.15 g of isobornyl-5-norbornene ester were
completely dissolved in 11 g of anhydrous ethyl acetate. 0.24 g of AIBN was added
to the resultant, purged using nitrogen gas for about 2 hours and polymerized at
a temperature of about 65° C. for about 24 hours.
Thereafter, separation was carried out in the same manner as in Example
4 to separate 7.59 g of a polymer. The weight average molecular weight and polydispersity
of the obtained reactant product were 11,200 and 1.9, respectively.
EXAMPLE 13
Synthesis of poly(5-norbornene-2-ol-maleic anhydride-t-butyl 5-norbornene ester-isobornyl acrylate)
With the exception that 5-norbornene-2-ol was used, instead of 2-hydroxypropyl-5-norbornene
ester, the same procedure was carried out in the same manner as in Example 10 to
separate a polymer (yield: 40%). The weight average molecular weight and polydispersity
of the obtained reactant product were 14,200 and 1.9, respectively.
EXAMPLE 14
Synthesis of poly(5-norbornene-2-methanol-maleic anhydride-t-butyl 5-norbornene
ester-isobornyl acrylate)
With the exception that 5-norbornene-2-methanol was used, instead of 2-hydroxypropyl-5-norbornene
ester, the same procedure was carried out in the same manner as in Example 10 to
separate a polymer (yield: 40%). The weight average molecular weight and polydispersity
of the obtained reactant product were 13,200 and 1.8, respectively.
EXAMPLE 15
Synthesis of poly(norbornene ester-maleic anhydride-t-butyl 5-norbornene ester-2-hydroxyethyl acrylate)
Except that norbornene, instead of 2-hydroxypropyl-5-norbornene ester, was
used, and 2-hydroxyethyl acrylate, instead of isobornyl acrylate, was used, the
same procedure was carried out in the same manner as in Example 10 to separate
a polymer (yield: 45%). The weight average molecular weight and polydispersity
of the obtained reactant product were 12,700 and 2.1, respectively.
Method for Preparing Photoresist Composition and Photolithography Process Using
the Same
EXAMPLE 16
1.0 g of a terpolymer prepared in Example 5 by polymerizing 2-hydroxypropyl-5-norbornene
ester, maleic anhydride and t-butyl methacrylate in a ratio of 1:1:1, 0.02 g of
triphenylsulfornium triflate as a photoacid generator and 2 mg of triisobutylamine
as an organic base were dissolved in 8.0 g of propylene glycol monomethyl ether
acetate (PGMEA). Subsequently, the mixture was filtered using a 0.2 μm filter,
resulting in a photoresist composition.
An anti-reflection layer was coated on a wafer where a patterning object material
layer and then the acquired photoresist composition was spin coated to a thickness
of about 0.4 μm. The photoresist composition coated wafer was pre-baked at
a temperature of about 140° C. for about 90 seconds, exposed using a mask
defining a predetermined pattern and an ArF excimer laser (NA: 0.6) as an exposure
light source, and post-baked at a temperature of about 110° C. for about 90
seconds. Thereafter, the resultant was developed using 2.38% by weight of TMAH
for about 60 seconds, thereby forming a photoresist pattern.
As a result, a 0.20 μm line and space photoresist pattern was obtained
at
an exposure dose of about 10 mJ/cm
2.
EXAMPLE 17
A photoresist composition was prepared using 1.0 g of a terpolymer prepared in
Example 7 by polymerizing 2-hydroxypropyl-5-norbornene ester, maleic anhydride
and 2-methyladamantyl acrylate in a ratio of 1:1:1, and then a photolithography
process was performed in the same manner as in Example 16.
As a result, a 0.22 μm line and space photoresist pattern was obtained
at
an exposure dose of about 11 mJ/cm
2.
EXAMPLE 18
A photoresist composition was prepared using 1.0 g of terpolymer prepared in
Example
8 by polymerizing 2-hydroxypropyl-5-norbornene ester, maleic anhydride and t-butyl
5-norbornene ester in a ratio of 1:7:6, and then a photolithography process was
performed in the same manner as in Example 16.
As a result, a 0.20 μm line and space photoresist pattern was obtained
at
an exposure dose of about 11 mJ/cm
2.
EXAMPLE 19
A photoresist composition was prepared using 1.0 g of a tetrapolymer prepared
in
Example 9 by polymerizing 2-hydroxypropyl-5-norbornene ester, maleic anhydride,
t-butyl 5-norbornene ester and t-butyl acrylate in a ratio of 1:7:6:1.4, and then
a photolithography process was performed in the same manner as in Example 16.
As a result, a 0.24 μm line and space photoresist pattern was obtained
at
an exposure dose of about 12 mJ/cm
2.
EXAMPLE 20
A photoresist composition was prepared using 1.0 g of a tetrapolymer prepared
in
Example 10 by polymerizing 2-hydroxypropyl-5-norbornene ester, maleic anhydride,
t-butyl 5-norbornene ester and isobornyl acrylate in a ratio of 1:7:6:0.7, and
then a photolithography process was performed in the same manner as in Example 16.
As a result, a 0.18 μm line and space photoresist pattern was obtained
at
an exposure dose of about 11 mJ/cm
2.
EXAMPLE 21
A photoresist composition was prepared using 1.0 g of a tetrapolymer prepared
in
Example 11 by polymerizing 2-hydroxypropyl-5-norbornene ester, maleic anhydride,
t-butyl 5-norbornene ester and 2-methyladamantyl acrylate in a ratio of 1:7:6:0.7,
and then a photolithography process was performed in the same manner as in Example 16.
As a result, a 0.20 μm line and space photoresist pattern was obtained
at
an exposure dose of about 10 mJ/cm
2.
EXAMPLE 22
A photoresist composition was prepared using 1.0 g of a tetrapolymer prepared
in
Example 12 by polymerizing 2-hydroxypropyl-5-norbornene ester, maleic anhydride,
t-butyl 5-norbornene ester and isobornyl-5-norbornene ester in a ratio of 1:7:6:0.7,
and then a photolithography process was performed in the same manner as in Example 16.
As a result, a 0.24 μm line and space photoresist pattern was obtained
at
an exposure dose of about 10 mJ/cm
2.
EXAMPLE 23
A photoresist composition was prepared using 1.0 g of a tetrapolymer prepared
as
a photosensitive polymer in Example 13 by polymerizing 5-norbornene-2-ol, maleic
anhydride, t-butyl 5-norbornene ester and isobornyl acrylate in a ratio of 1:5:4:0.5
and 0.02 g of triphenylsulfonium nonaflate, and then a photolithography process
was performed in the same manner as in Example 16.
As a result, a 0.22 μm line and space photoresist pattern was obtained
at
an exposure dose of about 13 mJ/cm
2.
EXAMPLE 24
A photoresist composition was prepared using 1.0 g of a tetrapolymer prepared
as
a photosensitive polymer in Example 14 by polymerizing 5-norbornene-2-methanol,
maleic anhydride, t-butyl 5-norbornene ester and isobornyl acrylate in a ratio
of 1:5:4:0.5, 0.02 g of triphenylsulfonium nonaflate and 2 mg of triethanolamine
as an organic base, and then a photolithography process was performed in the same
manner as in Example 16.
As a result, a 0.20 μm line and space photoresist pattern was obtained
at
an exposure dose of about 14 mJ/cm
2.
EXAMPLE 25
A photoresist composition was prepared using 1.0 g of a tetrapolymer prepared
in
Example 15 by polymerizing norbornene, maleic anhydride, t-butyl 5-norbornene ester
and 2-hydroxy ethyl acrylate in a ratio of 1:5:4:0.5, 0.01 g of a mixture of 0.01
g of succinimidyl triflate and 0.01 g of triphenylsulfonium triflate as a photoacid
generator, and 2 mg of triisobutylamine as an organic base, and then a photolithography
process was performed in the same manner as in Example 16.
As a result, a 0.22 μm line and space photoresist pattern was obtained
at
an exposure dose of about 13 mJ/cm
2.
According to the present invention, since the backbone of a photosensitive
polymer is a cyclic structure, the etching resistance thereof is large. Also, since
an alcohol group is bonded to the backbone of the polymer, adhesion to underlying
layer materials is excellent. Further, since wettability to a developing solution
is large, development can be carried out using a conventional developing solution,
for example, 2.38 wt % of TMAH. In particular, in the case where a secondary alcohol
group is bonded to the backbone, the stability of the polymer is also increased.
Thus, if a photoresist composition is formed using the photosensitive polymer
according to the present invention, the etching resistance of the photoresist composition
is increased and adhesion to an underlying film becomes excellent. Also, development
can be performed using a conventional developing solution of a widely adopted concentration,
for example, 2.38 wt % of TMAH. Further, in the case where a C
6 to C
20
