U.S. patent application number 09/102916 was filed with the patent office on 2001-09-13 for photosensitive resin composition and patterning method using the same.
This patent application is currently assigned to Kaichiro Nakano. Invention is credited to HASEGAWA, ETSUO, IWASA, SHIGEYUKI, MAEDA, KATSUMI, NAKANO, KAICHIRO.
Application Number | 20010021482 09/102916 |
Document ID | / |
Family ID | 26490580 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010021482 |
Kind Code |
A1 |
NAKANO, KAICHIRO ; et
al. |
September 13, 2001 |
PHOTOSENSITIVE RESIN COMPOSITION AND PATTERNING METHOD USING THE
SAME
Abstract
There is disclosed a sensitive resin composition in accordance
with the present invention has a 75 to 99.8 weight part of polymer
having a repetition units expressed by a general formula (1): 1
where R.sup.1, R.sup.3 and R.sup.5 represent one of a hydrogen atom
and a methyl group, R.sup.2 represents a bridged cyclic hydrocarbon
group having a carbon number in the range of 7 to 12 inclusive,
R.sup.4 represents a hydrocarbon group including an epoxy group,
x+y+z=1, 0<x.ltoreq.0.7, 0.ltoreq.y<1, 0<z.ltoreq.1), the
polymer having a weight averaged molecular weight of 1000 to
500000, and 0.2 to 25 weight part of photo acid generator. This
composition may include a multifunctional epoxy compound. This
composition is deposited on a substrate to be worked, and after
heating, the composition is exposed to an activating irradiation,
and then, a heat treatment is carried out, and further, the
composition is developed so as to form a pattern. This is excellent
in the transparency to a far ultraviolet ray, and shows a high
sensitivity and a high resolution to the exposure light of the far
ultraviolet ray.
Inventors: |
NAKANO, KAICHIRO; (TOKYO,
JP) ; MAEDA, KATSUMI; (TOKYO, JP) ; IWASA,
SHIGEYUKI; (TOKYO, JP) ; HASEGAWA, ETSUO;
(TOKYO, JP) |
Correspondence
Address: |
SUGHRUE MION ZINN MACPEAK & SEAS
2100 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
200373202
|
Assignee: |
Kaichiro Nakano
|
Family ID: |
26490580 |
Appl. No.: |
09/102916 |
Filed: |
June 23, 1998 |
Current U.S.
Class: |
430/280.1 ;
430/325; 430/330 |
Current CPC
Class: |
G03F 7/0382
20130101 |
Class at
Publication: |
430/280.1 ;
430/325; 430/330 |
International
Class: |
G03F 007/038; G03F
007/38 |
Claims
1. A sensitive resin composition in accordance with the present
invention has a 75 to 99.8 weight part of polymer having a
repetition units expressed by a general formula (1): 32where
R.sup.1, R.sup.3 and R.sup.5 represent one of a hydrogen atom and a
methyl group, R.sup.2 represents a bridged cyclic hydrocarbon group
having a carbon number in the range of 7 to 1,2 inclusive, R.sup.4
represents a hydrocarbon group including an epoxy group, x+y+z=1,
0<x.ltoreq.0.7, 0.ltoreq.y<l, 0<z.ltoreq.1), the polymer
having a weight averaged molecular weight of 1000 to 500000, and
0.2 to 25 weight part of photo acid generator
2. A sensitive resin composition claimed in claim 1 wherein R.sup.2
in the general formula (1) is composed of one selected from the
group consisting of tricyclo [5.2.1.0.sup.2,6] decyl group,
norbornyl group, methylnorbornyl group, isobornyl group, tetracyclo
[4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group, methyltetracyclo
[4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group, 2,7-dimethyltetracyclo
[4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group,
2,10-dimethyltetracyclo [4.4,0.1.sup.2,5. 1.sup.7,10] dodecyl
group, 11,12,-dimethyltetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10]
dodecyl group, hexacyclo [6.6.1.1.sup.3,6. 1.sup.10,13, 0.sup.2,7.
0.sup.9,14] heptadecyl group, octacyclo [8.8.1.sup.2,9. 1.sup.4,7.
1.sup.11,18, 1.sup.13,16. 0..sup.3,8. 0.sup.12,17] dococyl group,
and adamantanyl group.
3. A sensitive resin composition claimed in claim 2 wherein R.sup.4
in the general formula (1) is composed of one selected from the
group consisting of glycidyl group, 3,4-epoxy-1-cyclohexylmethyl
group, 5,6-epoxy-2-bicyclo- [2.2.1] heptyl group, 5
(6)-epoxyethyl-2-bicyclo-[2.- 2.1] heptyl group,
5,6-epoxy-2-bicyclo- [2.2.1] heptylmethyl group,
3,4-epoxytricyclo-[5.2.1.0.sup.2,6] decyl group,
3,4-epoxytricyclo-[5.2.1- .0.sup.2,6] decyloxyethyl group,
3,4-epoxytetracyclo-[4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group,
and 3,4-epoxytetracyclo-[4.4.0.1.sup.2,5. 1.sup.7,10] dodecylmethyl
group.
4. A sensitive resin composition in accordance with the present
invention has a 75 to 99.8 weight part of polymer having a
repetition units expressed by a general formula (1): 33where
R.sup.1, R.sup.3 and R.sup.5 represent one of a hydrogen atom and a
methyl group, R.sup.2 represents a bridged cyclic hydrocarbon group
having a carbon number in the range of 7 to 12 inclusive, R.sup.4
represents a hydrocarbon group including an epoxy group, x+y+z=1,
0<x.ltoreq.0.7, 0.ltoreq.y<1, 0<z.ltoreq.1), the polymer
having a weight averaged molecular weight of 1000 to 500000, and
0.2 to 25 weight part of photo acid generator, and a
multifunctional epoxy compound of 0.5 to 60 weight parts per 100
parts of the whole composition including the multifunctional epoxy
compound itself.
5. A sensitive composition claimed in claim 4 wherein R.sup.2 in
the general formula (1) is composed of one selected from the group
consisting of tricyclo [5.2.1.0.sup.2,6] decyl group, norbornyl
group, methylnorbornyl group, isobornyl group, tetracyclo
[4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group, methyltetracyclo
[4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group, 2,7-dimethyltetracyclo
[4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group,
2,10-dimethyltetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl
group, 11,12,-dimethyltetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10]
dodecyl group, hexacyclo [6.6.1.1.sup.3,6. 1.sup.10,13, 0.sup.2,7.
0.sup.9,14] heptadecyl group, octacyclo [8.8.1.sup.2,9.
1.sup.4,7.1.sup.11,18.sup.13,16. 0.0.sup.3,8. 0.sup.12,17] dococyl
group, and adamantanyl group.
6. A sensitive resin composition claimed in claim 5 wherein R.sup.4
in the general formula (1) is composed of one selected from the
group consisting of glycidyl group, 3,4-epoxy-1-cyclohexylmethyl
group, 5,6-epoxy-2-bicyclo- [2.2.1] heptyl group, 5 (6)-
epoxyethyl-2-bicyclo-[2- .2.1] heptyl group, 5,6-epoxy-2-bicyclo-
[2.2.1] heptylmethyl group, 3,4-epoxytricyclo-[5.2.1.0.sup.2,6]
decyl group, 3,4-epoxytricyclo [5.2.1.0.sup.2,6] decyloxyethyl
group, 3,4-epoxytetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl
group, and 3,4-epoxytetracyclo-[4.4- .0.1.sup.2,5. 1.sup.7,10]
dodecylmethyl group.
7. A patterning method including the steps of depositing one a
substrate to be worked, a sensitive resin composition in accordance
with the present invention has a 75 to 99.8 weight part of polymer
having a repetition units expressed by a general formula (1):
34where R.sup.1, R.sup.3 and R.sup.5 represent one of a hydrogen
atom and a methyl group, R.sup.2 represents a bridged cyclic
hydrocarbon group having a carbon number in the range of 7 to 12
inclusive, R.sup.4 represents a hydrocarbon group including an
epoxy group, x+y+z=1, 0<x.ltoreq.0.7, 0.ltoreq.y<1,
0<z.ltoreq.1), the polymer having a weight averaged molecular
weight of 1000 to 500000, and 0.2 to 25 weight part of photo acid
generator, exposing the deposited sensitive resin composition to an
activating irradiation after heating, a conducting a heat
treatment, and developing the exposed sensitive resin composition
so as to form a pattern.
8. A patterning method claimed in claim 7 wherein said activating
irradiation has the wavelength of not greater than 248 nm.
9. A patterning method claimed in claim 8 wherein said activating
irradiation is an ArF excimer laser.
10. A patterning method claimed in claim 7 wherein said
photosensitive resin composition further includes a multifunctional
epoxy compound of 0.5 to 60 weight parts per 100 parts of the whole
composition including the multifunctional epoxy compound
itself.
11. A patterning method claimed in claim 10 wherein said activating
irradiation has the wavelength of not greater than 248 nm.
12. A patterning method claimed in claim 11 wherein said activating
irradiation is an ArF excimer laser.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a photosensitive resin
composition suitable to a photolithography using an activating
radiation such as a far ultraviolet ray, an electron beam, an ion
beam and an X-ray in a semiconductor manufacturing process, and a
patterning method using the same.
[0003] 2. Description of Related Art
[0004] In the manufacturing of various semiconductor devices
typified by a dynamic random access memory (DRAM), the demand for
elevation of the density and the integration of the device is now
increased more and more. In order to fulfill this demand, it is
indispensable to microminiaturize the pattern. Therefore, the
request for the photolithography is now becoming severe more and
more.
[0005] One means for microminiaturizing the pattern is to shorten
the wave length of an exposing light used in the patterning. At
present, the manufacturing of DRAMs having the integration degree
of not less than 1 G bits (patterning size of not larger than 0.2
.mu.m) requires a fine patterning, which requires a light source
having a short wavelength. The photolithography using an ArF
excimer laser (wavelength is 193 nm) is now actively
researched.
[0006] A resist material, which is a pattern forming material used
in this fine patterning, is required to have high sensitivity in
addition to a high resolution corresponding to the size of the fine
patterning. The reason for this is that, in order to reduce a
damage to optical members such as lens in an exposure machine, it
is necessary to form a desired pattern with a relatively low
exposure amount. In addition, particularly when the exposure light
source such as the excimer laser is used, since the life of the gas
which is a laser oscillation material is short, and since the laser
apparatus is expensive, it is necessary to elevate the cost
performance of the laser.
[0007] As a method for enhancing the sensitivity of the resist,
there is used a chemically amplified resist using a photo acid
generating agent such as a photo cation generating agent, which
generates acid in response to exposure of the activating radiation,
as a photosensitive agent. For example, Japanese Patent Application
Postexamination Publication No. JP-B-02-027660 discloses a resist
composed of a combination of triphenylsulfoniumhexafluoroaresenate
and poly(p-ter-butoxycarbonyloxy-.a- lpha.-methylstrene. The
chemically amplified resist is characterized in that the photo acid
generating agent, which is a material included in the photo acid
generating agent and generating acid in response to the light
radiation, generates a proton acid, and with a heating treatment
after the exposure, the proton acid thus generated is caused to
move in a resist solid state, to amplify a chemical reaction of the
resist resin by a catalytic reaction up to hundreds times to
thousands times. Thus, a remarkably high sensitivity can be
attained in comparison with the prior art having the optical
reaction efficiency (reaction per one photon) of smaller than 1
(one). At present, most of newly developed resist is a chemical
amplified resist, and a chemical amplification mechanism has to be
adopted in developing a high sensitive material meeting with a
shortened wavelength of the exposure light source.
[0008] In the prior art lithography technique using an exposure
light having the wavelength longer than that of an KrF excimer
laser (248 nm), the photosensitive resin composition includes the
resin component typified by a resin, such as a novolak resin and
poly(p-vinylphenol), containing an aromatic ring in unit
structures. However, the light absorption by the aromatic ring of
the light having the wavelength of not greater than 220 nm is
extremely strong, and therefore, these prior art resins cannot be
used as they are, for the exposure light having the wavelength of
not greater than 220 nm. (Namely, a major portion of the exposure
light is absorbed at a surface of the resist, so that the exposure
light does not reach a substrate, with the result that a fine
patterning of the resist cannot be attained) (Sasago et al "ArF
excimer laser lithography (3) -Evaluation of Resist-", 36th Applied
Physics Institution Conference Manuscripts, 1p-K-4, 1989).
Therefore, a resin material having no aromatic ring but having an
etching resistance.
[0009] For example, as a polymer having a transparency to the light
having the wavelength of 193 nm and a dry etching resistance, there
are proposed a copolymer having adamantylmethacrylate units which
are alicyclic polymer (S. Takechi et al, Journal of Photopolymer
Science and Technology, Vol. 5, No. 3, pp439-446, 1992, and
Japanese Patent Application Pre-examination Publication No.
JP-A-05-265212), a poly(norbornylmethacrylate (M. Endo et al,
Proceedings of IEDM, CA14-18, 1992 (San Francisco)), a copolymer
having isobornylmethacrylate units (G. M. Wallraff et al, Journal
of Vacuum Science and Technology, B11(6), pp2783-2788, 1993), and a
copolymer having poly(menthylmethacrylate) units (Japanese Patent
Application Pre-examination Publication No. JP-A-08-08-2925).
Furthermore, the co-inventors of this application proposes a
polymer having a transparency to the light having the wavelength of
not greater than 200 nm and a dry etching resistance and also
having a difference in solubility between a pre-exposure and a
post-exposure, and a photosensitive resin composition using the
same (Japanese Patent Application Pre-examination Publication No.
JP-A-08-259626). In addition, a 0.16 .mu.m line-and-space pattern
was formed on this photosensitive resin by using a ArF excimer
laser experimental machine (Nikon lens, numerical aperture=0.6) (K.
Maeda et a, Proceedings of SPIE, Vol.2724, pp377-395).
[0010] However, all of the above mentioned resist materials are a
positive resist, and no negative resist of chemical amplification
type for an ArF excimer laser exposure has not yet been reported.
In a future development of DRAMs, it is required to develop a
negative resist on a rush basis The background of requiring the
negative resist is that a recent elevated expectation of a
multimedia information society needs a DRAM having a large capacity
and a high operation speed, with the result that it is considered
to be of necessity to install the DRAM and a logic circuit on the
same single chip so as to realize a high speed operation and a high
performance. Namely, since the negative resist is more advantageous
than the positive resist, in a forming of an isolated pattern, it
is indispensable to form the logic pattern. Furthermore, in the
lithography in the process of manufacturing a DRAM of 1 giga bits
or more, use of a phase shift mask is indispensable, and a phase
shift mask can be easily formed in the negative resist, in
comparison with the positive resist. As mentioned above, the
negative resist is required more and more in fuiture. However, as
mentioned above, there is no report of the negative resist having a
high transparency to the light having the wavelength of 193 nm and
a high resolution, and an early development is required. Many
negative resists meeting with the KrF excimer laser having
wavelength of 193 nm have been reported and developed, however,
since those negative resists include an unsaturated bond such as
aromatic ring in the resin and a crosslinking agent, those negative
resists are not transparent to the light having the wavelength of
193 nm which is the wavelength of the ArF excinier laser, and
therefore, cannot be used.
SUMMARY OF THE INVENTION
[0011] Accordingly, the present invention has an object to provide
a sensitive resin composition which has a high transparency to the
light in a far ultraviolet region and a high sensitivity and a high
resolution to an exposure light of a far ultraviolet ray.
[0012] The present invention also has an object to provide a
sensitive resin composition suitable to a negative photoresist
using the ArF excimer laser as an exposure light.
[0013] Furthermore, the present invention has an object to provide
a patterning method capable of forming a fine pattern necessary for
a semiconductor manufacturing.
[0014] The co-inventors found out that the above mentioned objects
can be achieved by the sensitive resin composition and patterning
method which will be described in the following, and invented the
present invention.
[0015] The sensitive resin composition in accordance with the
present invention has a 75 to 99.8 weight part of polymer having a
repetition units expressed by a general formula (1): 2
[0016] where R.sup.1, R.sup.3 and R.sup.5 represent one of a
hydrogen atom and a methyl group, R.sup.2 represents a bridged
cyclic hydrocarbon group having a carbon number in the range of 7
to 12 inclusive, R.sup.4 represents a hydrocarbon group including
an epoxy group, x+y+z=1, 0<0.7, 0.ltoreq.y<1,
0<z.ltoreq.1), the polymer having a weight averaged molecular
weight of 1000 to 500000, and 0.2 to 25 weight part of photo acid
generator
[0017] Furthermore, the sensitive resin composition in accordance
with the present invention has a 75 to 99.8 weight part of polymer
having a repetition units expressed by a general formula (1): 3
[0018] where R.sup.1, R.sup.3 and R.sup.5 represent one of a
hydrogen atom and a methyl group, R.sup.2 represents a bridged
cyclic hydrocarbon group having a carbon number in the range of 7
to 12 inclusive, R.sup.4 represents a hydrocarbon group including
an epoxy group, x+y+z=1, 0<x.ltoreq.0.7, 0.ltoreq.y<1,
0<z.ltoreq.1), the polymer having a weight averaged molecular
weight of 1000 to 500000, and 0.2 to 25 weight part of photo acid
generator, and a multifunctional epoxy compound of 0.5 to 60 weight
parts per 100 parts of the whole composition including the
multifumctional epoxy compound itself.
[0019] Furthermore, the patterning method in accordance with the
present invention is characterized by depositing the sensitive
resin composition in accordance with the present invention on a
substrate to be worked, and heating it, and thereafter, exposing it
to an activating light, conducting a heat treatment, developing it
so as to form a pattern.
[0020] In the sensitive resin composition in accordance with the
present invention, an aliphatic hydrocarbon residue is introduced
in the repetition units of the polymer, so that the transparency to
the light having the wavelength of 180 nm to 248 nm and an etching
resistance is given, and the epoxy group is introduced in the
repetition units of the polymer, and if necessary, the
multifunctional epoxy compound is included, so that a crosslinking
reaction occurs due to an acid generated by the exposure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIGS. 1A to 1D are diagrammatic sectional views for
illustrating a negative pattern forming method using the sensitive
resin composition in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] In the general formula (1) of the present invention, as
shown in the following table 1, the bridged hydrocarbon group of
R.sup.2 is exemplified by tricyclo [5.2.1.0.sup.2,6] decyl group,
norbornyl group, methylnorbornyl group, isobornyl group, tetracyclo
[4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group, methyltetracyclo
[4.4.0. 1.sup.2,5. 1.sup.7,10] dodecyl group,
2,7-dimethyltetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group,
2,10-dimethyltetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl
group, 11,12,-dimethyltetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10]
dodecyl group, hexacyclo [6.6.1. 1.sup.3,6. 1.sup.10,13, 0.sup.2,7.
0.sup.9,14] heptadecyl group, octacyclo [8.8.1.sup.2,9. 1.sup.4,7.
1.sup.11,18, 1.sup.13,16. 0. 0.sup.3,8. 0.sup.12,17] dococyl group,
and adamantanyl group (tricyclo [3.3.1.1.sup.3,7] decyl group).
However, R.sup.2 is in no way limited to these materials.
1TABLE 1 Name of R.sup.2 Chemical Structure of R.sup.2 Norbornyl
Group 4 Methylnorbornyl Group 5 Isobornyl Group 6
Tricyclo[5.2.1.0.sup.2,6]decyl Group 7
Tricyclo[5.2.1.0.sup.2,6]decylmethyl Group 8
Tetracyclo[4.4.0.1.sup.2,5.1.sup.,10]dodecyl Group 9
Methyltetracyclo[4.4.0.1.sup.2,5.1.sup.,10]dodecyl Group 10
2,7-dimethyltetracyclo[4.4.0.1.sup.2,5.1.sup.,10]dodecyl Group 11
2,10-dimethyltetracyclo[4.4.0.1.sup.2,5.1.sup.,10]dodecyl Group 12
11,12-dimethyltetracyclo[4.4.0.1.sup.2,5.1.sup.,10]dod- ecyl Group
13 Hexacyclo[6.6.1.1.sup.3,6.1.sup.10,13.0.sup.-
2,7.0.sup.9,14]heptadecyl Group 14 Octacyclo[8.8.1.sup.2,9-
.1.sup.4,7.1.sup.11,18.1.sup.13,16.0.0.sup.3,6.0.sup.12,17]dococyl
Group 15
[0023] In addition, as shown in the following table 2, the
hydrocarbon group including an epoxy group, represented by R.sup.4
is exemplified by glycidyl group, 3,4-epoxy-1-cyclohexylmethyl
group, 5,6-epoxy-2-bicyclo-[2.2.1] heptyl group, 5
(6)-epoxyethyl-2-bicyclo-[2.2- .1]heptyl group,
5,6-epoxy-2-bicyclo- [2.2.1]heptylmethyl group,
3,4-epoxytricyclo-[5.2.1.0.sup.2,6] decyl group,
3,4-epoxytricyclo-[5.2.1- .0.sup.2,6] decyloxyethyl group,
3,4-epoxytetracyclo-[4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl group,
and 3,4-epoxytetracyclo-[4.4.0.1.sup.2,5. 1.sup.7,10] dodecylmethyl
group. However, R.sup.4 is in no way limited to these
materials.
2TABLE 2 Name of R.sup.4 Chemical Structure of R.sup.4 Glycidyl
Group 16 3,4-epoxy-1-cyclohexylmethyl Group 17
5,6-epoxy-2-bicyclo-[2.2.1]heptyl Group 18
5(6)-epoxyethyl-2-bicyclo-[2.2.1]heptyl Group 19
5,6-epoxy-2-bicyclo-[2.2.1]heptylmethyl Group 20
3.4-epoxytricyclo-[5.2.1.0.sup.2,6]decyl Group 21
3,4-epoxytricyclo-[5.2.1.0.sup.2,6]decyloxyethyl Group 22
3,4-epoxytetracyclo-[4.4.0.1.sup.2,51.sup.7,10]dodecyl Group 23
3,4-epoxytetracyclo-[4.4.0.1.sup.2,51.sup.7,10]dodecylmethyl Group
24
[0024] The polymer expressed by the general formula (1) can be
prepared by adding, into a tetrahydrofuran solution under
atmosphere of an inert gas such as argon or nitrogen, a monomer and
a radical initiator such as azobisisobutyronitrile, with a
molecular ratio of monomer to initiator being 10 to 200, and
heating it while agitating at a temperature of 50.degree. C. to
70.degree. C. for a time of 0.5 hours to 10 hours. The polymer thus
obtained has an averaged polymerization degree of 10 to 500,
preferably, 10 to 200, and the weight averaged molecular weight is
1000 to 500000.
[0025] A thin film of the polymer expressed by the general formula
(1) (film thickness is 1.0 .mu.m) has an excimer laser light (193
nm) transparency as high as 65% to 81%, which is practically
usable.
[0026] In a thin film of the polymer having the repetition units in
which in the general formula (1), R.sup.1 is hydrogen atom, R.sup.3
is a methyl group, and R.sup.2 is tricyclo [5.2.1.0.sup.2,6] decyl,
an etching rate of a CF.sub.4 gas reactive ion etching is about 185
.ANG./min, which is comparable to that of poly(p-vinylphenol),
which is a basic polymer of the chemically amplified resist for the
KrF excimer laser exposure.
[0027] Furthermore, it was confirmed that this polymer has a good
adhesive property to a silicon substrate.
[0028] A basic constituents of the photosensitive resin composition
in accordance with the present invention is the polymer having the
repetition units expressed the general formula (1), and the photo
acid generating agent generating acid in response to exposure,
(which are ordinarily added with solvent), and the multifunctional
epoxy compound added if necessary. The contents of the polymer and
the photo acid generating agent are that the former is 75 to 99.8
weight parts and the latter is 0.2 to 25 weight parts. Preferably,
the former is 85 to 99 weight parts and the latter is 1 to 15
weight parts. When the photo acid generating agent is less than 0.2
weight parts, the photosensitivity remarkably drops so that the
patterning becomes difficult. When the photo acid generating agent
is greater than 25 weight parts, it becomes difficult to form a
uniform deposited film, and scum is easy to occur after
development.
[0029] The photo acid generating agent preferably used in the
present invention is a photo acid generator which generates aid in
response to light having the wavelength of not greater than 248 nm.
On the other hand, any photo acid generator can be used if a
mixture of the polymer in the present invention and the photo acid
generator can be sufficiently dissolved in an organic solvent and
if the solution thus obtained can be deposited to form a uniform
coating film by means of a film depositing method such as a spin
coating. A single photo acid generator or a mixture of two or more
photo acid generators can be used, and also can be used in
combination with a suitable sensitizing agent.
[0030] When the ArF excimer laser is used, a transparency of the
photo acid generating agent to the exposure light is important,
similarly to the resin. The prior art photo acid generating agent
having the aromatic ring typified by
triphenylsulfoniumhexafluoroaresenate disclosed by JP-B-02-027660,
has a strong absorption, and therefore, it is considered that the
amount of usage is limited in some cases. The coinventors of this
application already developed the photo acid generating agent which
is relatively transparent to the ArF excimer laser and which
generates aid at a high efficiency (Japanese Patent Application No.
Heisei 05-174528 which was laid open as Japanese Patent Application
Pre-examination Publication No. JP-A-07-025846 and Japanese Patent
Application No. Heisei 05-174532 which was laid open as Japanese
Patent Application Pre-examination Publication No. JP-A-07-028237,
both of which corresponds to U.S. Pat. No. 5,585,507
specification).
[0031] Usable photo acid generators can be exemplified by for
example usable by triphenylsulfonium salt derivatives proposed by
J. V. Crivello et al in Journal of the Organic Chemistry, Vol. 43,
No. 15, pp 3055-3058, 1978, and other onium salts (compound such as
sulfonium salt, iodonium salt, phosphonium salt, diazonium salt and
ammonium salt, (c) 2,6-dinitrobenzyl ester proposed by T. X. Neenan
et al in SPIE Proceedings, Vol. 1262, pp 32, 1990, 1,2,3-tri
(methanesulfonyloxy) benzene proposed by Takumi Ueno et al in
Proceedings of PME '89, pp 413-424, published through Kodansha,
1990, sulfosuccinimide disclosed in Japanese Patent Application
Pre-examination Publication No. JP-A-05--134416, or the photo acid
generators which are disclosed by Japanese Patent Application Nos.
Heisei 05-174528 and Heisei 05-174532 and expressed by the
following general formulas (2) and (3): 25
[0032] where R.sup.6 and R.sup.7 are a linear, branched or cyclic
alkyl group, R.sup.8 is a linear, branched or cyclic alkyl group,
2-oxocycloalkyl group, and 2-oxo linear or branched alkyl group,
A.sup.- represents a counter ion such as BF.sub.4.sup.-,
ASF.sub.6.sup.-, SbF.sub.6.sup.-, PF.sub.6.sup.-,
CF.sub.3COO.sup.-, CIO.sub.4.sup.-, CF.sub.3SO.sub.3.sup.-,
alkylsulfonate, and arylsulfonate. 26
[0033] where R.sup.9 and R.sup.10 are hydrogen, or a linear,
branched or cyclic alkyl group, R .sup.11 is a linear, branched or
cyclic alkyl group, or haloalkyl group typified by perfluoroalkyl
such as trifluoromethyl.
[0034] When the exposure light having the wavelength of not greater
than 220 nm is used, in order to elevate the light transparency of
the photosensitive resin composition, it is preferred to use the
photo aid generating agent expressed by the general formula (2) or
(3) of the above mentioned photo aid generating agents. Namely,
those photo aid generating agents have less light absorption in a
far ultraviolet region from 185.4 nm to 220 nm, and therefore,
those are more preferable as the constituent of the resist for the
ArF excimer laser lithography from the viewpoint of the
transparency to the exposure light. Specifically, there are
exemplified cyclohexylmethyl(2-oxocyclohexyl) sulfonium
trifluoromethanesulfonate, dicyclohexyl(2-oxocyclohexyl)sulfonium
trifluoromethanesulfonate, dicyclohexylsulfonylcyclohexanone,
dimethyl(2-oxocyclohexyl) sulfonium trifluoromethanesulfonate,
triphenylsulfonium trifluoromethanesulfonate, diphenyliodonium
trifluoromethanesulfonate, or N-hydroxysucciimide
trifluoromethanesulfona- te. However, the photo aid generating
agents are in no way limited to these materials.
[0035] The multifunctional epoxy compound used in the present
invention can be exemplified by hydorgenbisphenol A
diglycidylether, ethyleneglycolglycidylether,
diethyleneglycoldiglycidylether, propyleneglycoldiglycidylether,
tripropyleneglycoldiglycidylether, neopentylglycoldiglycidylether,
1,6-hexanedioldiglycidylether, glycerinediglycidylether,
trimethylolpropanetriglycidylether, 1,2-cyclohexancarboxylic acid
diglycidylester, 3,4-epoxycyclohexanecarbox- ylic acid,
3,4-epoxycyclohexylmethyl, trisepoxypropylisocyanurate,
2-epoxyethylbicyclo[2.2.1] heptylglycidylether,
ethylenegylcolbis(2-epoxy- ethylbicyclo[2.2.1] heptyl)ether,
bis(2-diepoxyethylbicyclo[2.2.1] heptyl)ether. However, the
multifunctional epoxy compound is in no way limited to these
materials. The contents of the multifunctional epoxy compound is
ordinarily 0.5 to 60 weight parts per 100 weigh parts of the whole
composition including the multifunctional epoxy compound itself,
and preferably, is 1 to 50 weight parts. The multifunctional epoxy
compound may be composed of either a single multifunctional epoxy
compound or a combination of two or more multifunctional epoxy
compounds.
[0036] The solvent preferably used in the present invention may be
any organic solvent if the solvent can sufficiently dissolve the
polymer and an alkylsulphonium salt, and if the solution thus
obtained can be deposited to form a uniform coating film by means
of a spin coating and another. The may be composed of either a
single solvent or a combination of two or more solvents.
Specifically, the solvent can be exemplified by n-propyl alcohol,
isopropyl alcohol, n-butyl alcohol, terbutyl alcohol,
methylcellosolve acetate, ethylcellosolve acetate, propyleneglycol
monoethylether acetate, methyl lactate, ethyl lactate,
2-ethoxybutyl acetate, 2ethoxyethyl acetate, pyrubic acid methyl,
pyrubic acid ethyl, 3-methoxypropionatemethyl,
3-methoxypropionateethyl, N-methyl-2-pyrrolidinone, cyclohexanone,
cyclopentanone, cyclohexanol, methylethylketone, 1,4dioxan,
ethyleneglycolmonomethylether, ethyleneglycolmonomethylether
acetate, ethyleneglycolmonoethylether,
ethyleneglycolmonoisopropylether, diethyleneglycolmonomethylether,
and diethyleneglycoldimethylether. However, the solvent is in now
way limited to these materials.
[0037] If necessary, the photosensitive resin composition in
accordance with the present invention can include other
constituents such as surface activating agent, pigment, stabilizer,
agent for enhancing application property, and dye.
[0038] When a fine patterning is conducted using the photosensitive
resin composition in accordance with the present invention, a
development agent is selected from a suitable organic solvent in
accordance with the dissolving property to the polymer used in the
present invention, or a mixture of those solvents, a alkaline
solvent having a suitable concentration, a water solution including
the alkaline solvent, or a mixture of the alkaline solvent. A
usable organic solvent can be exemplified by ketones such as
acetone, methylketone, methylisobutylketone, cyclopentanone, and
cyclohexanone, alcohol such as methyl alcohol, ethyl alcohol,
npropyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl
alcohol, terbutyl alcohol, cyclopentanol, cyclohexanol, and ethers
such as tetrahydrofuran, dioxane, ethyl acetate, butyl acetate,
isoamyl acetate, toluene, xylene, and phenol. In addition, a usable
alkaline solution can be exemplified by an aqueous solution or
organic solvent, containing an inorganic alkali such as sodium
hydroxide, potassium hydroxide, sodium silicate, and ammonia; an
organic amine such as ethylamine, propylamine, diethylamine,
dipropylamine, trimethylamine and triethylamine; or an organic
ammonium salt such as tetramethylammonium hydroxide,
tetraethylammonium hydroxide, trimethylhydroxymethylammonium
hydroxide, triethylhydroxymethylammonium hydroxide, and
trimethylhydroxyethylammonium hydroxide, or alternatively, their
mixture. However, the developer is in no way limited to these
materials.
[0039] According to the present invention, there is provided a
method forming a negative pattern on a substrate to be worked, by
using the photosensitive resin composition in accordance with the
present invention. As shown n FIG. 1A, first, the photosensitive
resin composition in accordance with the present invention is
coated on a substrate 1 to be worked, by means of a spin coating,
and then, a heat treatment is conducted by a hot plate at a
temperature of 60.degree. C. to 170.degree. C. for 30 seconds to
240 seconds, so that a deposited film 2 of the photosensitive resin
composition is formed. Thereafter, the ArF excimer laser is
selectively irradiated by a mask 3 as shown in FIG. 1B.
Succeedingly, the post exposure baking is conducted to the
deposited film 2 of the photosensitive resin composition by means
of the hot plate (PEB=postexposure baking). As a result, in an
exposed region of the deposited film 2 of the photosensitive resin
composition, the epoxy groups causes a ring-opening polymerization
by action of acid generated from the photo acid generating agent,
so that the crosslinking of the resin advances (FIG. 1C).
Furthermore, by using the alkaline developing liquid such as a
tetramethylammonium hydroxide (TMAH) aqueous solution, the
unexposed portion in the deposited film 2 of the photosensitive
resin composition is dissolved and removed, so that a negative
pattern is formed (FIG. 1D).
[0040] The photosensitive resin composition in accordance with the
present invention can exhibit a patterning performance for the
other activating ray such as a g-line and i-line of a mercury vapor
lamp, an KrF excimer laser, or an electron beam, an X-ray, if a
suitable photo acid generating agent or a suitable pigment for
light absorption are introduced.
[0041] Now, the present invention will be described with reference
to embodiments and comparative examples, but it is to be noted that
the present invention is in no way limited to those
embodiments.
[0042] Embodiment 1
[0043] Preparation of the polymer having the following structure
(in the general formula (1), R.sup.1, R.sup.3 and R.sup.5 are
methyl group, R.sup.2 is norbomyl group, and R.sup.4 is
5,6-epoxy-2-bicyclo [2.2.1] heptyl group, x=0.2, y=0.3, z=0.5)
27
[0044] In a 100 ml round bottomed glass flask coupled with a
feedback pipe having a calcium chloride pipe, 2.1 g of
norbonylmethacrylate, 3.57 g of 5,6-epoxy-2-bicyclo [2.2.1] heptyl
methacrylate, and 3.25 g of methacrylic acid are dissolved in 27 ml
of dry tetrahydrofuran, and furthermore, 223 mg (50 mmol/l) of AIBN
is added thereto and stirred at 60.degree. C. to 65.degree. C.
After two hours, it is cooled down and the reaction mixture is
poured into 300 ml of ligroin, and a separated-out precipitate is
filtered. Furthermore, precipitation purification is carried out
once more, so that 6.24 g of a target matter is obtained (yield of
70%). At this time, it was confirmed by .sup.1HNMR that
copolymerization ratio is as calculated. The weight averaged
molecular weight (Mw) was 21500 and the degree of dispersion
(Mw/Mn) was 2.08.
[0045] Embodiment 2
[0046] Preparation of the polymer having the following structure
(in the general formula (1), R.sup.1, R.sup.3 and R.sup.5 are
methyl group, R.sup.2 is tricyclo [5.2.1.0.sup.2,6] decylmethyl
group, and R.sup.4 is glycidyl group, x=0.3, y=0.3, z=0.4) 28
[0047] This is prepared similarly to the embodiment 1, excepting
that tricyclo [5.2.1.0.sup.2,6] decylmethyl methacrylate (made by
Hitachi Kasei Kogyo K. K.) is used in place of the
norbonylmethacrylate, and glycidyl methacrylate ("Light Ester G"
made by Kyoei-Sha Kagaku K. K.) is used in place of
5,6-epoxy-2-bicyclo [2.2.1] heptyl methacrylate. The weight
averaged molecular weight (Mw) was 26000 and the degree of
dispersion (Mw/Mn) was 2.21.
[0048] Embodiment 3
[0049] Preparation of the polymer having the following structure
(in the general formula (1), R.sup.1, R.sup.3 and R.sup.5 are
methyl group, R.sup.2 is tetracyclo [4. 4.0.1.sup.2,5. 1.sup.7,10]
dodecyl group, R.sup.4 is 3.4-epoxytricyclo [5.2.1.0.sup.2,6] decyl
group, x=0.03, y=0.75, z=0.247) 29
[0050] This is prepared similarly to the embodiment 1, excepting
that tetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl methacrylate
is used in place of the norbonylmethacrylate, and 3.4-epoxytricyclo
[5.2.1.0.sup.2,6] decyl methacrylate is used in place of
5,6-epoxy-2-bicyclo [2.2.1] heptyl methacrylate. The weight
averaged molecular weight (Mw) was 12050 and the degree of
dispersion (Mw/Mn) was 1.70.
[0051] Embodiment 4
[0052] Preparation of the polymer having the following structure
(in the general formula (1), R.sup.1, R.sup.3 and R.sup.5 are
methyl group, R.sup.2 is tetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10]
dodecyl group, R.sup.4 is 3.4-epoxytetracyclo [4.4.0.1.sup.2,5.
1.sup.7,10] decyl group, x=0.25, y=0.25, z=0.50) 30
[0053] This is prepared similarly to the embodiment 1, excepting
that tetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10] dodecyl methacrylate
is used in place of the norbonylmethacrylate, and
3.4-epoxytetracyclo [4.4.0.1.sup.2,5. 1.sup.7,10] decyl
methacrylate is used in place of 5,6-epoxy-2-bicyclo [2.2.1] heptyl
methacrylate. The weight averaged molecular weight (Mw) was 27800
and the degree of dispersion (Mw/Mn) was 1.98.
[0054] Embodiment 5
[0055] Preparation of the polymer having the following structure
(in the general formula (1), R.sup.1, R.sup.3 and R.sup.5 are
methyl group, R.sup.2 is hexacyclo [6.6.1.1.sup.3.6. 0.sup.10,13.
0.sup.9,14] heptadecyl group, R.sup.4 is glycidyl group, x=0.3,
y=0.3, z=0.4) 31
[0056] This is prepared similarly to the embodiment 1 excepting
that hexacyclo [6.6.1.1.sup.3,6. 0.sup.10,13. 0.sup.9,14]
heptadecyl methacrylate is used in place of the
norbonylmethacrylate, and glycidyl methacrylate ("Lito Ester G"
made by KyoekiSha Kagaku K. K.) is used in place of
5,6-epoxy-2--bicyclo [2.2.1] heptyl methacrylate. The weight
averaged molecular weight (Mw) was 28620 and the degree of
dispersion (Mw/Mn) was 2.45. Embodiments 6 to 10 and Comparable
examples 1 and 2.
[0057] 2 g of the respective polymers obtained in the Embodiments 1
to 5 are dissolved in 10 g of ethyl lactate, and is filtered by a
Teflon filter having a pore diameter of 0.2 .mu.m, and then, is
spincoated on a 3-inch silicon substrate, and further, is baked on
a hot plate at 90.degree. C. for 60 seconds, so that a thin film
having a film thickness of 0.7 .mu.m was formed. An etching rate of
the film thus obtained to a CF.sub.4 gas was measured by using a
reactive ion etching (RE) machine DEM451 made by Nichiden Aneruba
(under the etching condition of power=100 W, pressure=5 Pa and gas
flow rate=30 sccm). The result is shown in the following table
3.
[0058] Incidentally, as a comparative example 1, when the deposited
film was formed by poly(p-vinylphenol) which is frequently used as
a basic resin for the resist of the KrF excimer laser lithography,
the result is shown in the table 3. As a comparative example 2,
when the deposited film was formed by polymethylmethacrylate which
is a polymer having no bridged cyclic hydrocarbon group in its
molecular structure, the result is also shown in the table 3. The
polymer obtained in accordance with the present invention shows the
etching rate slower than that of the poly(methylmethacrylate). In
addition, the polymer obtained in accordance with the present
invention shows the etching rate comparable to or slower than that
of poly(p-vinylphenol). In other words, it would be apparent that
the polymer obtained in accordance with the present invention has a
sufficient etching resistance as the resist material.
3TABLE 3 Embodiment Polymer Etching rate (.ANG./min) 6 polymer of
Embodiment 1 175 7 polymer of Embodiment 2 170 8 polymer of
Embodiment 3 177 9 poLymer of Embodiment 4 166 10 polymer of
Embodiment 5 163 comparative 1 poly(p-vinylphenol) 167 comparative
2 poly(methylmethacrylate) 262 Embodiment 11
[0059] The resist material having the following composition was
prepared and the following experiment was carried out by using a
yellow lamp:
4 (a) polymer (Embodiment 1) 0.950 g (b)
cyclohexylmethyl(2-oxocyclohexyl)sulfonium
trifluoromethanesulfonate 0.050 g (photo acid generating agent =
compound of the general formula (2) (3) ethyl lactate (solvent)
4.000 g
[0060] The above mixture is filtered by a 0.2 .mu.m Teflon filter,
so that the resist was prepared. The resist was spincoated on a
3-inch silicon substrate, and baked at a hot plate at 80.degree. C.
for 60 seconds so that a thin film having a film thickness of 0.71
.mu.m was formed (FIG. 1A). The wavelength dependency of the
transmittance of the film thus obtained was measured by using a
ultraviolet and visible light spectrometer. The transmittance of
this thin film at the wavelength of 193.4 nm was 68%, and
therefore, it was confirmed that it has a sufficient transparency
as a single layer resist.
[0061] Embodiment 12
[0062] The resist shown in the Embodiment 11 was exposed by using
an ArF reduction exposure experimental machine (NA=0.55,
.sigma.=0.7, made by NIKON). Immediately after the exposure, the
resist is baked at a hot plate at 130.degree. C. for 90 seconds,
and is immerse in an alkaline developing liquid (aqueous solution
containing 2.3 weight parts of tetramethylammonium hydroxide) of
23.degree. C. for 60 minutes, and succeedingly, is rinsed with a
pure water for 60 seconds. As a result, only the exposed portion of
the resist film has become insoluble, and the unexposed portion is
dissolved and removed by the developing liquid, so that a negative
pattern was obtained. In this experiment, when the exposure energy
was about 38mJ/cm.sup.2, a resolution of a 0.25 .mu.m
line-and-space pattern could be obtained. Furthermore, the obtained
pattern was observed by a scan electron microscope (SEM, SE-4100
made by HITACHI). Neither an undeveloped portion nor a pealing-off
of the pattern was found out.
[0063] Embodiments 13-16
[0064] The resist solution was prepared similarly to the Embodiment
11, and the exposure experiment was carried out similarly to the
Embodiment 12. The result is shown in the following table 4;
5TABLE 4 Added amount of multifunctional epoxy Sensitivity
Resolution Embodiment Polymer (g) (mJ/cm.sup.2) (.mu.m) 13 Polymer
of 0 55 0.24 Embodiment 2 14 Polymer of 0 5 0.3 Embodiment 3 15
Polymer of trimethylolpropane 23 0.22 Embodiment 4 triglycidylether
0.25 16 Polymer of 1,2-cyclohexancarboxylic 19 0.20 Embodiment 5
acid diglycidylester 0.25
[0065] As will be apparent from the above description, the
photosensitive resin position in accordance with the present
invention has a high transparency in a far ultraviolet region, and
shows a high sensitivity and a high resolution to an exposure light
of far ultraviolet ray. In other words, it is suitable to a
negative photoresist using the far ultraviolet ray having the
wavelength of not greater than 248 nm, particularly, the ArF
excimer laser having the wavelength of 193 nm. Furthermore, by
using the fine patterning method in accordance with the present
invention using the photosensitive resin composition in accordance
with the present invention, it is possible to form a fine pattern
required in a semiconductor device manufacturing.
* * * * *