Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
1993-12-02
2002-05-07
Young, Christopher G. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S192000, C430S193000
Reexamination Certificate
active
06383708
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a positive resist composition which comprises a quinone diazide compound, an alkali-soluble resin and a specific solvent system. 2. Description of the Related Art
A composition containing a compound having a quinone diazide group (a quinone diazide compound) and an alkali-soluble resin finds use as a positive resist in the production of integrated circuits.
Recently, with integrated circuits, miniaturization has proceeded with a rise in the integration level, which results in demands for formation of patterns of sub-micron order. To form such minute patterns with good reproducibility, the positive resist composition should achieve high resolution, a large &ggr;-value and a good profile and also have high qualities in various process margins such as an exposure margin and a depth of focus.
Since the width of wiring is miniaturized with the increase of the integration level, dry etching is employed in addition to wet etching. For dry etching, the resist is required to have higher resistance to dry etching, namely heat resistance than ever.
In these years, instead of a conventional mask contact printing method, a reduction projection exposure system attracts attention. One of the serious problems in this new system is low throughput. Namely, in this system, the total exposure time to expose a wafer is very long because of divided and repeated light exposure unlike a batch light exposure system which is employed in the conventional mask contact printing methods.
To solve this problem, an increase in sensitivity of the resist is most-important. If the exposure time can be shortened by an increase in the sensitivity, the throughput and in turn a yield can be improved.
One measure to increase the sensitivity is a decrease of the molecular weight of an alkali-soluble resin contained in the resist composition. However, the decrease of the molecular weight encounters some problems, for example, a large film thickness loss in an unexposed area (reduction of so-called film thickness retention), a worsening of a profile and various process margins, and a decrease of the &ggr;-value because of a small difference in the dissolving rates in the developing solution between the exposed area and the unexposed area. In addition, the heat resistance of the resist is deteriorated and adhesion of the resist to a substrate is decreased disadvantageously.
Other measures to increase the sensitivity include prolongation of the developing time and increase of the concentration of an alkali in the developing liquid. However, they are not preferable since the film thickness retention and in turn the resolution are decreased.
To increase the &ggr;-value, it is contemplated to increase the amount of the quinone diazide compound. But, the increase of the amount of the quinone diazide compound may lead to precipitation of fine particles of the quinone diazide compound and the alkali-soluble resin and therefore a decrease in the yield of the integrated circuits.
To solve such problems, it may be possible to use a monohydroxycarboxylate ester such as ethyl lactate which has a large dissolving capability for the quinone diazide compound and is safer with respect to human beings than the conventional resist solvent such as ethyleneglycol monoalkyl ether acetate. However, such a solvent will increase striations or cause some problem in coating such that the edge of a wafer is not coated.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a positive resist composition which has a large &ggr;-value and provides a good profile and a large depth of focus while maintaining other properties required for a resist such as good heat resistance, high resolution, good sensitivity and a good coating property.
According to the present invention, there is provided a positive resist composition comprising, in admixture, an alkali-soluble resin, a quinone diazide compound and a mixed solvent of (B) at least one organic solvent selected from the group consisting of &ggr;-butyrolactone, 3-methoxybutanol and cyclohexanone and (A) an organic solvent other than the solvents (B) which does not have simultaneously an alkylcarbonyl group and an alkoxy group in a molecule and has a boiling point of from 140 to 180° C. under atmospheric pressure.
DETAILED DESCRIPTION OF THE INVENTION
In the positive resist composition of the present invention, a quinone diazide compound may be any one of conventionally used compounds. For example, a quinone diazide compound is an ester of a below described hydroxyl group-containing compound with a quinone diazide sulfonic acid such as 1,2-benzoquinone diazide-4-sulfonic acid, 1,2-naphthoquinone diazide-4-sulfonic acid or 1,2-naphthoquinone diazide-5-sulfonic acid. Preferably, a quinone diazide compound is an ester of a hydroxyl group-containing compound of the formula:
wherein Y
1
′, Y
2
′, Z
1
′, Z
2
′, Z
3
′, Z
4
′, Z
5
′, Z
6
′ and Z
7
′ are the same and different and each a hydrogen atom, a hydroxyl group or a C
1
-C
4
alkyl group provided that at least one of Y
1
′ and Y
2
′ is a hydroxyl group and at least two of Z
1
′, Z
2
′, Z
3
′, Z
4
′, Z
5
′, Z
6
′ and Z
7
′ are hydroxyl groups; and R
1
′, R
2
′, R
3
′, R
4
′, R
5
′ and R
6
′ are the same or different and each a hydrogen atom, a C
1
-C
10
alkyl group, a C
2
-C
4
alkenyl group, a C
5
-C
8
cycloalkyl group or an aryl group, or an oxyflavan compound of the formula:
wherein Y
1
and Y
2
are the same or different and each a hydrogen atom, a hydroxyl group or a C
1
-C
4
alkyl group provided that at least one of them is a hydroxyl group; Z
1
, Z
2
, Z
3
, Z
4
, Z
5
, Z
6
and Z
7
are the same or different and each a hydrogen atom, a halogen atom, a hydroxyl group, a C
1
-C
4
alkyl group, a C
5
-C
8
cycloalkyl group or an aryl group provided that at least two of them are hydroxyl groups; and R
1
, R
2
, R
3
, R
4
and R
5
are the same or different and each a hydrogen atom, a C
1
-C
10
alkyl group, a C
2
-C
4
alkenyl group, a cyclohexyl group or an aryl group provided that at least one of R
4
and R
5
is a C
1
-C
10
alkyl group, a C
2
-C
4
alkenyl group, a cyclohexyl group or an aryl group with the above quinone diazide sulfonic acid.
Among them, the quinone diazide sulfonic acid ester of the oxyflavan (II) is preferred.
The quinone diazide compound may be prepared by a per se conventional method. For example, the quinone diazide sulfonic acid and the hydroxyl group-containing compound are condensed in the presence of a weak alkali.
Examples of the hydroxyl group-containing compound are hydroquinone, resorcinol, phloroglucin, 2,4-dihydroxybenzophenone, trihydroxybenzophenones (e.g. 2,3,4-trihydroxybenzophenone, 2,2′,3-trihydroxybenzophenone, 2,2′,4-trihydroxybenzophenone, 2,2′,5-trihydroxybenzophenone, 2,3,3′-trihydroxybenzophenone, 2,3,4′-trihydroxybenzophenone, 2,3′,4-trihydroxybenzophenone, 2,3′,5-trihydroxybenzophenone, 2,4,4′-trihydroxybenzophenone, 2,4′,5-trihydroxybenzophenone, 2′,3,4-trihydroxybenzophenone, 3,3′,4-trihydroxybenzophenone, 3,4,4′-trihydroxybenzophenone, etc.), tetrahydroxybenzophenones (e.g. 2,3,3′,4′-tetrahydroxybenzophenone, 2,3,4,4′-tetrahydroxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone, 2,2′,3,4-tetrahydroxybenzophenone, 2,2′,3,4′-tetrahydroxybenzophenone, 2,2′,5,5′-tetrahydroxybenzophenone, 2,3′,4′,5-tetrahydroxybenzophenone, 2,3′,5,5′-tetrahydroxybenzophenone, etc.), pentahydroxybenzophenones (e.g. 2,2′,3,4,4′-pentahydroxybenzophenone, 2,2′,3,4,5′-pentahydroxybenzophenone, 2,2′,3,3′,4-pentahydroxybenzophenone, 2,3,3′,4,5′-pentahydroxybenzophenone, etc.), hexahydroxybenzophenones (e.g. 2,3,3′,4,4′,5-hexahydroxybenzophenone, 2,2′,3,3′,
Doi Yasunori
Hanawa Ryotaro
Hashimoto Kazuhiko
Osaki Haruyoshi
Uetani Yasunori
Birch & Stewart Kolasch & Birch, LLP
Sumitomo Chemical Company Limited
Young Christopher G.
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