Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2000-06-22
2001-08-14
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S191000, C430S192000
Reexamination Certificate
active
06274287
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a positive type resist composition which is sensitive to a radiation such as ultra violet ray, deep ultra violet ray, including eximer laser, electron beam, ion beam and X-rays, and is suitably used in producing semiconductor integrated circuits.
A lithography process using a resist composition has usually been adopted in a fine processing of semiconductor integrated circuit. Among the resist composition, positive working types are widely used because of their generally superior resolution. The positive resists contain generally an alkali-soluble ingredient and a radiation-sensitive ingredient. Specifically, novolak-quinonediazide type resists are known which contain a novolak resin as an alkali-soluble ingredient and a quinonediazide compound as a radiation-sensitive ingredient, and utilize the decomposition of the quinonediazide compound by the action of radiation to generate a carboxylic group, which changes the compound from alkali-insoluble to alkali-soluble.
In recent years, according to the demand for higher integration level, an integrated circuit having a finer circuit and a pattern formation at a sub-micron level has become required. As the result, a positive resist composition having a still higher resolution has become demanded. For satisfying this demand, so-called chemical amplification type resists, which utilize the chemical amplifying action of acid-generator, have also been used in some field. There is still, however, a persistent need for the novolak-quinonediazide resists.
The resolving power of the novolak-quinonediazide type positive resists may be improved by increasing the amount of the radiation-sensitive quinonediazide compound. However, there is a limitation, since the light absorption of the resist becomes so large that the profile is deteriorated and a rectangular pattern shape can not be obtained, when the amount of quinonediazide compound is too much. JP-A-61-141441 discloses an improvement in the sensitivity, heat resistance and others by adding an unesterified 2,3,4-trihydroxybenzophenone in addition to 1,2-naphthoquinonediazidesulfonic acid ester of 2,3,4-trihydroxybenzophenone which is a radiation-sensitive ingredient. Moreover, JP-A-1-289947, JP-A-2-2560, JP-A-3-191351 and others disclose an improvement in sensitivity, resolution and others by adding various polyhydric phenol compounds in addition to an alkali-soluble resin and a radiation-sensitive ingredient.
An object of the present invention is to further improve the resolution of the positive resists containing an alkali-soluble resin and a radiation-sensitive ingredient without deteriorating other resist performances. As the result of studies, the present inventors have found that the resolution of a positive resist composition which contains an alkali-soluble resin and a radiation-sensitive ingredient can be further improved by adding a certain compound. Thus, the present invention has been completed.
SUMMARY OF THE INVENTION
The present invention provides a positive resist composition comprising an alkali-soluble resin, a radiation-sensitive ingredient and a hydroxyphenyl ketone compound represented by the following formula (I):
wherein R
1
, R
2
, R
3
, R
4
and R
5
independently represent hydrogen, alkyl or alkoxy and n represents an integer of 1 to 3.
PREFERRED EMBODIMENT OF THE INVENTION
In the formula (I), R
1
, R
2
, R
3
, R
4
and R
5
are the same or different from each other, and are hydrogen, alkyl or alkoxy, respectively. The alkyl may generally have about 1 to 5 carbon atoms; the alkoxy may generally have about 1 to 3 carbon atoms and is preferably methoxy or ethoxy; n, representing the number of hydroxyl groups on the benzene ring, may be 1 to 3. In addition, it is preferred that two of R
1
, R
2
and R
3
are hydrogen. The remaining one is suitably hydrogen or alkyl. It is preferred that R
4
and R
5
positioned on the benzene ring are hydrogen, respectively.
Specific example of the hydroxyphenyl ketone compound represented by the formula (I) include the following compounds:
A: 2′-hydroxyacetophenone,
B: 3′-hydroxyacetophenone,
C: 4′-hydroxyacetophenone,
D: 2′-hydroxypropiophenone,
E: 3′-hydroxypropiophenone,
F: 4′-hydroxypropiophenone,
G: 2′,4′-dihydroxyacetophenone,
H: 2′,5′-dihydroxyacetophenone,
I: 2′,6′-dihydroxyacetophenone,
J: 3′,4′-dihydroxyacetophenone,
K: 3′,5′-dihydroxyacetophenone,
L: 2′,3′,5′-trihydroxyacetophenone,
M: 4′-hydroxy-3′-methylacetophenone,
N: 2′-hydroxy-5′-methylacetophenone,
and the like.
Among them, when n representing the number of hydroxyl groups on the benzene ring in the formula (I) is 1, compounds in which the hydroxyl group is positioned on 3- or 4-position in respect to the carbonyl, such as 3′-hydroxyacetophenone, 4′-hydroxyacetophenone and 4′-hydroxypropiophenone, are preferred. When n is 2 or 3, compounds in which one of the hydroxyl groups is positioned on 2-position, such as 2′,4′-dihydroxyacetophenone, 2′,5′-dihydroxyacetophenone, 2′,6′-dihydroxyacetophenone and 2′,3′,5′- 5 trihydroxyacetophenone, are preferred.
The positive resist composition of the invention comprises an alkali-soluble resin and a radiation-sensitive ingredient. Those commonly used in this technical field of the invention may be used as an alkali-soluble resin or a radiation-sensitive ingredient. As examples of the alkali-soluble resin, a polyvinyl phenol, a novolac resin, and the like may be mentioned. Among them, a novolac resin is preferred. A novolac resin can usually be obtained by condensing a phenol compound and an aldehyde in the presence of an acid catalyst.
Examples of the phenol compound used in the preparation of the novolac resin include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphenol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 2,3-dimethoxyphenol, 2,5-dimethoxyphenol, 3,5-dimethoxyphenol, 2-methoxyresorcinol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, 2,5-diethylphenol, 3,5-diethylphenol, 2,3,5-triethylphenol and a polyhydroxytriphenylmethane compound obtainable by condensation of xylenol and hydroxybenzaldehyde. These phenol compounds can be used singly or in combination of two or more.
Examples of the aldehyde used in the preparation of the novolac resin include aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butylaldehyde, iso-butylaldehyde and pivalaldehyde; licyclic aldehydes such as cyclohexanealdehyde, clopentanealdehyde and furfural; aromatic aldehydes such as benzaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-anisaldehyde, m-anisaldehyde and p-anisaldehyde; and aromatic-aliphatic aldehydes such as phenylacetaldehyde. These aldehydes can be used singly or in combination of two or more. Among these aldehydes, formaldehyde is preferably used because of easy availability in the industry.
Examples of the acid catalyst used for condensation of the phenol compound with the aldehyde compound 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; and bivalent metal salts such as zinc acetate, zinc chloride and magnesium acetate. These acid catalysts can be used singly or in combination of two or more. The condensation reaction can be carried out according to the usual manner, for example, at a temperature within a range of 60 to 120° C. for 2 to 30 hours.
It is preferred that the content of lower molecular weight fraction in the novolak resin obtained by the condensation reaction is lowered, for example, by fractiona
Moriuma Hiroshi
Takata Yoshiyuki
Birch & Stewart Kolasch & Birch, LLP
Chu John S.
Sumitomo Chemical Company Limited
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