U.S. patent application number 09/812583 was filed with the patent office on 2001-12-13 for positive resist composition.
Invention is credited to Lee, Sang-Ho, Tomioka, Jun, Uetani, Yasunori.
Application Number | 20010051313 09/812583 |
Document ID | / |
Family ID | 18598513 |
Filed Date | 2001-12-13 |
United States Patent
Application |
20010051313 |
Kind Code |
A1 |
Uetani, Yasunori ; et
al. |
December 13, 2001 |
Positive resist composition
Abstract
A positive resist composition which gives improved profile
without lowering other properties such as sensitivity and
resolution, and comprises an alkali-soluble novolak resin, a
quinone diazide type radiation-sensitive agent and
N-(n-octylsulfonyloxy) succinimide
Inventors: |
Uetani, Yasunori; (Osaka,
JP) ; Tomioka, Jun; (Osaka, JP) ; Lee,
Sang-Ho; (Suwon-Shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
18598513 |
Appl. No.: |
09/812583 |
Filed: |
March 21, 2001 |
Current U.S.
Class: |
430/191 ;
430/165; 430/192; 430/193; 430/326 |
Current CPC
Class: |
G03F 7/0226 20130101;
G03F 7/0045 20130101 |
Class at
Publication: |
430/191 ;
430/192; 430/193; 430/165; 430/326 |
International
Class: |
G03F 007/023; G03F
007/30 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2000 |
JP |
2000-081599 |
Claims
What is claimed is:
1. A positive resist composition comprising an alkali-soluble
novolak resin, a quinone diazide type radiation-sensitive agent and
N-(n-octylsulfonyloxy) succinimide.
2. The positive resist composition according to claim 1 wherein the
content of N-(n-octylsulfonyloxy) succinimide is 0.01 to 25 percent
by weight based on the total solid content in the composition.
3. The positive resist composition according to claim 1 wherein the
content of N-(n-octylsulfonyloxy) succinimide is 0.1 to 10 percent
by weight based on the total solid content in the composition.
4. The positive resist composition according to claim 1 wherein,
when expressed in a gel permeation chromatography (GPC) pattern,
the pattern area of the components of the alkali-soluble novolak
resin with a molecular weight not higher than 1000 is not higher
than 25% based on the total pattern area of the alkali-soluble
novolak resin except for the unreacted phenolic compounds.
5. The positive resist composition according to claim 4 which
further comprises a low molecular weight alkali-soluble phenol
compound with a molecular weight of not higher than 1,000 at 3 to
40 percent by weight based on the total amount of the novolak resin
and the low molecular weight alkali-soluble phenol compound.
6. The positive resist composition according to claim 1 wherein the
radiation-sensitive agent is present in 10 to 100 percent by weight
based on the amount of the novolak resin.
7. The positive resist composition according to claim 5 wherein the
radiation-sensitive agent is present in 10 to 100 percent by weight
based on the total amount of the novolak resin and the low
molecular weight alkali-soluble phenol compound.
8. The positive resist composition according to claim 1 wherein the
radiation-sensitive agent is present in 10 to 50 percent by weight
based on the amount of the novolak resin.
9. The positive resist composition according to claim 5 wherein the
radiation-sensitive agent is present in 10 to 50 percent by weight
based on the total amount of the novolak resin and the low
molecular weight alkali-soluble phenol compound.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a positive resist
composition used in providing resist patterns through irradiation
of rays such as ultra violet rays followed by alkaline development
and in producing semiconductor integrated circuits and the
like.
[0002] In a positive resist containing a novolak resin as an
alkaline-soluble component and a quinone diazide compound as a
radiation-sensitive component, the quinone diazide compound
decomposes by irradiation of a ray to produce carboxyl group and
turns from alkaline-insoluble to alkaline-soluble in nature. This
phenomenon is utilized for providing a positive type pattern by
irradiation of the ray through a mask (the so-called patterning
exposure) followed by alkaline development in an alkaline medium.
The above described positive resist containing a novolak/quinone
diazide is generally excellent in resolution, and is widely used in
the manufacture of integrated circuits.
[0003] In recent years, the integrated circuit has become
micronized as the degree of integration increases and the formation
of submicron patterns is required. As a result, the positive resist
with higher resolution and excellent patterning capability
(profile) is required. When circuit pattern becomes finer the top
surface tends to be rounded or the slant between the top and bottom
tends to be conspicuous. As a result, it becomes more difficult to
reflect faithfully the mask pattern on the resist pattern to be
formed during pattern exposure. Therefore, a positive resist
composition is desired which solves those problems and gives a good
profile.
[0004] The inventors of the present invention have conducted
intensive studies to develop a positive resist composition which
gives a good profile. As a result, the inventors have found that a
positive resist containing an acid generating agent, such as
sulfonate of N-hydroxy succinimide, which decomposes to give an
acid in an alkaline developer provides an excellent profile, and
have disclosed it (JP-A-10-213905, SPIE Vol. 3333, 1280P-1287P,
1998).
[0005] After conducting further studies, the inventors have found
that a positive resist composition containing a specific
composition among sulfonates of N-hydroxy succinimide, namely N -
(n-octylsulfonyloxy) succinimide, gives a specifically excellent
profile. Thus, the present invention was completed.
SUMMARY OF THE INVENTION
[0006] The present invention provides a positive resist composition
comprising an alkali-soluble novolak resin, a quinone diazide type
radiation-sensitive agent and N-(n-octylsulfonyloxy)
succinimide.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0007] An alkali-soluble novolak resin generally used as an
alkaline-soluble component of a known positive resist can also be
used as the alkali-soluble novolak resin used in the present
invention. The alkali-soluble novolak resin used in the present
invention can generally be made by condensing a phenolic compound
and an aldehyde in the presence of an acid catalyst. Examples of
the phenolic compound include phenol, o-, m- or p-cresol, 2, 3 -,
2, 5 -, 3, 4 - or 3, 5-xylenol, 2, 3, 5 - trimethylphenol, 2 -, 3 -
or 4 - tert-butyphenol, 2 - tert-butyl - 4 - or 5 -methylphenol,
2-, 4- or 5-methyl resorcinol, 2-, 3 - or 4 - methoxyphenol, 2,3-,
2, 5- or 3, 5-dimethoxyphenol, 2-methoxyresorcinol, 4 - tert-butyl
catechol, 2 -, 3 - or 4 - ethylphenol, 2, 5 - or 3, 5 -
diethylphenol, 2, 3, 5 - triethylphenol, 2 - naphthol, 1, 3 -, 1, 5
- or 1, 7 - dihydroxylnaphthalene and polyhydroxytriphenyl methane
type compounds obtained by condensing xylenol and
hydroxybenzaldehyde. These phenolic compounds can be used alone or
in combination of two or more.
[0008] Examples of the aldehyede include aliphatic aldehyedes such
as formaldehyde, acetoaldehyde, propyonaldehyde, n-butylaldehyde,
isobutylaldehyde, pivalic aldehyde, n-hexylaldehyde, acrolein- and
crotonaldehyde; alicyclic compounds such as cyclohexyaldehyde,
cyclopentanaldehyde, furfural and furylacrolein; aromatic aldehydes
such as benzaldehyde, o-, m- or p-methylbenzaldehyde,
p-ethylbenzaldehyde, 2, 4 -, 2, 5 -, 3, 4 - or 3, 5 -
dimethylbenzaldehyde, o-, m- or p-hydroxybenzaldehyde, o-, m- or
p-anisic aldehyde and vanillin; and aromoaliphic aldehydes such as
phenyl acetaldehyde, and cinnamic aldehyde. These aldehydes can
also be used alone or in combination of two or more. Among them,
formaldehyde is preferable because it is readily available in the
industry.
[0009] Examples of the acid catalysts usable in condensing the
phenolic compound and aldehyde include inorganic acids such as
hydrochloric acid, sulfuric acid, perchloric acid and phosphoric
acid; organic acids such as formic acid, acetic acid, oxalic acid,
trichloroacetic acid and p-toluenesulfonic acid; bivalent metallic
salts such as zinc acetate, zinc chloride and magnesium acetate.
Those acid catalysts can be used alone or in combination of two or
more. The condensation reaction can be carried out in a usual way,
for example, for 2 to 30 hours at 60 to 120.degree. C.
[0010] A novolak resin obtained by the condensation is preferably
subjected to a fractionation to increase high molecular weight
component. It is preferable that, when expressed in a gel
permeation chromatography (GPC) pattern, the pattern area of the
components with a molecular weight not higher than 1000 is not
higher than 25%, more preferably not higher than 20%, based on the
total pattern area except for the unreacted phenolic compounds.
Here, the GPC pattern is measured using a 254 nm UV detector, and
the molecular weight is in terms of the molecular weight of
polystyrene.
[0011] It is useful to add a low molecular weight alkali-soluble
phenol compound, for example the one with a molecular weight of not
higher than 1,000, to the novolak resin in which the high molecular
weight component was increased. Such alkali-soluble low molecular
weight phenol compounds have preferably at least two phenolic
hydroxyl groups as disclosed in JP-A-2-275955 (U.S. Pat. No.
5,456,995 and U.S. Pat. No. 5,456,996) and JP-A-2-2560. In case an
alkali-soluble phenol compound with a molecular weight of not
higher than 1,000 is used, it is desirable that the compound is
present in 3 to 40 percent by weight based on the total amount of
the novolak resin and the alkali-soluble phenol compound.
[0012] A quinone diazo-type radiation-sensitive agent generally
used in the positive resist field can be used as the quinone
diazo-type radiation-sensitive agent used in the present invention.
Generally, an o-quinone diazosulfonic acid ester of a compound
having one or more phenolic hydroxyl groups can be used. Preferable
are 1, 2 -naphthoquinonediazo-5- or 4-sulfonic acid ester or 1,
2-benzoquinone diazo-4-sulfonic acid ester of polyhydroxy compounds
having at least three phenol hydroxyl groups. Such esters can be
made by reacting the compounds having the aforesaid hydroxyl groups
with o-quinone diazosulfonic acid halide in the presence of a base
such as triethyl amine. Among O-quinone diazosulfonic acid halides,
1, 2-naphthoquinone diazo-5-sulfonic acid chloride is especially
preferable. Such quinone diazo-type radiation-sensitive agents can
be used alone as combination of one or two agents. It is preferable
that the radiation-sensitive agent is present in 10 to 100 percent
by weight, more preferably 10 to 50 percent by weight based on the
total amount of the novolak resin and the aforesaid low molecular
weight alkali-soluble phenol compound used as necessary.
[0013] The positive resist composition of the present invention
comprises N-(n-octylsulfonyloxy) succinimide in addition to the
alkali-soluble novolak resin and the quinone diazo-type
radiation-sensitive agent mentioned above. This compound can be
prepared by condensation of N-hydroxy succinimide with
n-octylsulfonyl chloride under basic medium.
[0014] The content of N-(n-octylsulfonyloxy) succinimide is
generally 0.01 to 25 percent by weight, preferably 0.1 to 10
percent by weight based on the total solid content in the
composition.
[0015] The positive resist composition of the present invention is
generally applied as a resist solution on a substrate such as
silicon wafer. That is, the above-mentioned respective components
are dissolved in a solvent to prepare a resist solution and this
solution is applied. Any solvents may be used which dissolve the
respective components, have a proper drying rate and give a uniform
and smooth coat. The solvents which are generally used in this
field may be used. Example thereof include glycol ether esters such
as ethyl cellosolve acetate, methyl cellosolve acetate, propylene
glycol monomethyl ether acetate and propyleneglycol monoethyl ether
acetate; glycol ethers such as ethyl cellusolve, methyl cellusolve,
propylene glycol monomethyl ether and propylene glycol monoethyl
ether; esters such as ethyl lactate, butyl acetate, amyl acetate
and ethyl pyruvate; ketones such as 2-heptanone and cyclohexanone;
and cyclic esters such as .gamma.-butyrolactone. Those solvents can
be used alone or in combination of two or more. Also, this resist
solution can contain small quantities of additives such as other
resins than novolak resin and dyestuffs used in this field.
[0016] The resist solution applied on the substrate and dried to
form a resist film is subjected to a patterning exposure through a
mask. This patterning exposure is generally effected by visible
rays of shorter wavelengths to near ultraviolet rays such as g line
of a wavelength of 436 nm and i line with a wavelength of 365 nm.
The patterning exposure is followed by development in an alkaline
developer. As the alkaline developer, a variety of alkaline
solutions employed in this field may be used. Generally,
tetramethyl ammonium hydroxide and (2-hydroxy ethyl) trimethyl
ammonium hydroxide (generally called choline) are used in the form
of an aqueous solution.
[0017] The present invention will now be described in more
specifically by means of Examples, which by no means should be
construed as a limitation upon the scope of the present invention.
In Examples, parts mean parts by weight.
[0018] The following materials were used in Examples:
[0019] (a) Novolak resin A
[0020] The resin was prepared this way: m-cresol, p-cresol and
formaldehyde at a molar ratio of 60/40/80 were reacted under reflux
in the presence of oxalic acid catalyst in the usual method. Then,
the reaction product was subjected to a fractionation. The novolak
resin thus obtained had a molecular weight of about 8000 in terms
of polystyrene. In GPC pattern, the area ratio of the area for the
components with a molecular weight of not higher than 6000 in terms
of polystyrene to the total pattern area except for the pattern
area of unreacted cresol was 34% and the area ratio of the area for
the components with a molecular weight of not higher than 1000 in
terms of polystyrene was 15%.
[0021] (b) Novolak resin B
[0022] The resin prepared this way: m-cresol, p-cresol and
formaldehyde at a molar ratio of 40/60/80 were reacted under reflux
in the presence of oxalic acid catalyst in the usual method. Then,
the reaction product was subjected to a fractionation. The novolak
resin thus obtained had a molecular weight of about 8000 in terms
of polystyrene. In GPC pattern, the area ratio of the area for the
components with a molecular weight of not higher than 6000 in terms
of polystyrene to the total pattern area except for the pattern
area for unreacted cresol was 34% and the area ratio of the area
for the components with a molecular weight of not higher than 1000
in terms of polystyrene was 15%.
[0023] (c) Quinone diazo-type sensitizer 1
[0024] A condensate having a structural formula shown above was
used which was prepared by reacting 2, 4, 4-trimethyl-2', 4',
7-trihydroxyflavan and 1, 2-naphthoquinone diazide-5-sulfonic acid
chloride at molar ratio of 1:2.6.
[0025] (d) Additives
[0026] The following compounds were used:
[0027] C1: N-(n-octylsulfonyloxy)succinimide
[0028] C2: N-(n-hexylsufonyloxy)succinimide
[0029] C3: N-(10-camphorsulfonyloxy)succinimide
[0030] C4: N-(n-dodecylsulfonyloxy)succinimide
[0031] C5: 4-[1, 2', 3', 4' 4'a, 9'a -hexahydro-6'-hydroxyspiro
(cyclohexane-1, 9'-xantene)-4'a-il]-resorcinol
[0032] Those additives have the following structural formulas:
2
Examples 1 to 3 and Comparative Examples 1 to 4
[0033] 10 parts of the above-mentioned resins, the ratio of the
novolac resin A and B being shown in Table 1, 3 parts of the
above-mentioned sensitizer and a composition of additives, their
kinds and amounts being shown in Table 1, were mixed with 46 parts
of 2-heptanone. After the mixture was completely dissolved, the
solution was filtered through a 0.2 .mu.m fluororesin filter to
prepare a resist solution.
1TABLE 1 No. Resin Additive Example 1 A/B = 85/15 C1 = 0.1 part C5
= 3.9 part Example 2 A/B = 85/15 C1 = 0.2 part C5 = 3.8 part
Example 2 A/B = 90/10 C1 = 0.2 part C5 = 3.8 part Comparative A/B =
85/15 -- C5 = 4.0 part example 1 Comparative A/B = 85/15 C2 = 0.2
part C5 = 3.8 part example 2 Comparative A/B = 85/15 C3 = 0.2 part
C5 = 3.8 part example 3 Comparative A/B = 85/15 C4 = 0.2 part C5 =
3.8 part example 4
[0034] The respective resist solutions thus obtained were
spin-coated on silicon wafers treated with hexamethyldisilazane
(HMDS) so that the film thickness after drying was 1.065 .mu.m. The
pre-bake was carried out on a direct hot plate for 60 seconds at
90.degree. C. The wafers with a resist film thus formed thereon
were exposed to light through line and space patterns of various
sizes by changing the amount of exposure stepwise using an i-line
stepper "NSR-2005 i 9C" (NA=0.57, .sigma.=0.60) manufactured by
Nikon. Then, post-exposure bake was performed for 60 seconds at
110.degree. C., followed by paddle development in an aqueous
solution of 2.38% by weight of tetramethyl ammonium hydroxide for
60 seconds. The evaluation results are shown in Table 2.
[0035] Effective sensibility: Expressed by an amount of exposure
which gives a sectional area of 1:1 in 1.0 .mu.m line and space
pattern.
[0036] Resolution: Expressed by the minimum line width of line and
space pattern splitting by the amount of exposure at the effective
sensibility.
[0037] Profile (T/B): Expressed by the ratio of the size at the top
(T) of 1.0 .mu.m line and space pattern to the size of at the
bottom (B). The larger T/B is, the better the profile is.
2 TABLE 2 Effective Resolution No. sensibility (msec) (pm) T/B
Example 1 55 0.50 0.75 Example 2 65 0.475 0.89 Example 3 55 0.50
0.78 comparative 50 0.50 0.67 example 1 comparative 55 0.50 0.71
example 2 comparative 50 0.50 0.72 example 3 comparative 75 0.475
0.71 example 4
[0038] According to the present invention, it has become possible
to improve the profile without lowering other properties such as
sensitivity and resolution.
* * * * *