Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-07-31
2003-09-16
Chu, John S. (Department: 1752)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S717000, C568S718000, C430S193000
Reexamination Certificate
active
06620978
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to positive photoresist compositions which can form a variety of resist patterns such as dense patterns, isolation patterns, and dot patterns with good shapes under the same exposure conditions.
2. Description of the Related Art
Logic integrated circuits (ICs) have highly added values and have received attention in recent years. In production of highly integrated logic ICs where a high definition of not more than half a micron is required, demands have been made to provide photoresist compositions which can form resist patterns including various patterns such as dense patterns, isolation patterns, and dot patterns with good shapes.
In addition, such photoresist compositions are required to form individual resist patterns with good shapes even under the same exposure conditions.
However, conventional photoresist compositions cannot satisfactorily form isolation patterns or dot patterns even though they satisfactorily form dense patterns. Even if they can form such patterns, the resulting individual patterns have greatly varied focal depth range properties under the same exposure conditions. The exposure conditions or mask pattern dimensions must be therefore changed or adjusted depending on the shapes of patterns to obtain satisfactory patterns.
In this connection, Japanese Patent Laid-Open No.6-167805 (conventional technology 1) and Japanese Patent Laid-Open No. 7-168355 (conventional technology 2) each disclose quinonediazide esters having specific structures as photosensitizers, and describe high-definition positive photoresist compositions containing the esters.
However, such positive photoresist compositions as concretely described in the conventional technologies 1 and 2 cannot form a variety of resist patterns with good shapes without changing exposure conditions.
Japanese Patent Laid-Open No. 9-110751 (conventional technology 3) describes phenol compounds shown by a wide-ranging general formula, and mentions that quinonediazide esters of the phenol compounds are useful as photosensitizers.
However, the conventional technology 3 lacks concrete description of esters according to the present invention. In addition, the conventional technology 3 describes a process for synthesizing a pentanuclear phenol compound, but this process is liable to form by-products and a target compound cannot be isolated in a high yield.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a positive photoresist composition which can form dense patterns, isolation patterns, dot patterns, and other various resist patterns with good shapes even under the same exposure conditions, and has satisfactory focal depth range properties in the formation of ultrafine resist patterns of not more than half a micron.
Another object of the invention is to provide a process for synthesizing a phenol compound shown by the following formula (I) in a high yield with minimized formation of by-products.
After intensive investigations, the present inventors found that a positive photoresist composition containing a quinonediazide ester of a compound of the following formula (I) in which the ester has an average degree of esterification of 20% to 80% can form dense patterns, isolation patterns, dot patterns, and other various resist patterns with good shapes even under the same exposure conditions and has satisfactory focal depth range properties.
Specifically, the invention provides, in an aspect, a positive photoresist composition including (A) an alkali-soluble resin, and (B) a photosensitizer. In this composition, the photosensitizer (B) includes a quinonediazide ester of acompound shown by the following formula (I), and the quinonediazide ester has an average degree of esterification of 20% to 80%:
wherein each of R
1
to R
7
is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group.
The invented positive photoresist composition may include a quinonediazide ester of 2,6-bis[4-hydroxy-3-(2-hydroxy-3,5-dimethylbenzyl)-2,5-dimethylbenzyl]-4-methylphenol shown by the following formula (II) as the ingredient (B):
The invented positive photoresist composition preferably includes a quinonediazide ester of a compound shown by the following formula (III) as the ingredient (B):
wherein each of x and y is, identical to or different from each other, an integer of 0 or 1.
The invention provides, in a further aspect, the positive photoresist composition wherein the photosensitizer (B) includes a quinonediazide ester of a compound shown by the following formula (VI):
each of R
1
to R
9
is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group.
The invented positive photoresist composition may include a quinonediazide ester of 2,6-bis[4-hydroxy-3-(2-hydroxy-4,6-dimethylbenzyl)-2,5-dimethylbenzyl]-4-methylphenol shown by the following formula (VII) as the ingredient (B):
In another aspect, the invention provides a process for synthesizing a polyphenol compound. This process includes the steps of adding, in the presence of an acid catalyst, a solution of a methylol-group-containing compound of the following formula (V) in an organic solvent:
wherein each of R
3
to R
7
is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group, to a phenol compound shown by the following formula (IV):
wherein each of R
1
and R
2
is, identical to or different form each other, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group, or to a solution of the phenol compound in an organic solvent, and performing a reaction to yield a polyphenyl compound shown by the following formula (I):
wherein each of R
1
to R
7
is, identical to or different from one another, an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group.
In the above process, the organic solvents for use in dissolving the phenol compound and the methylol-group-containing compound are preferably good solvents for the polyphenol compound shown by the formula (I).
Each of the invented positive photoresist compositions may further include (C) a sensitizer (intensifier).
In the invented positive photoresist compositions, the proportion of the photosensitizer (B) may range from 10% to 60% by weight relative to the total weight of the ingredient (A) and the ingredient (C), where the ingredient (C) is added according to necessity.
Preferably, in the invented positive photoresist compositions, the quinonediazide ester may have an average degree of esterification of 40% to 60%.
DETAILED DESCRIPTION OF THE INVENTION
(A) Alkali-soluble Resin
Alkali-soluble resins for use as the ingredient (A) are not limited and can be chosen from those generally used as film-forming substances in positive photoresist compositions. Of these resins, condensates of aromatic hydroxy compounds and aldehydes or ketones, polyhydroxystyrenes and derivatives thereof are preferable.
Such aromatic hydroxy compounds include, but are not limited to, phenol, m-cresol, p-cresol, o-cresol, 2,3-xylenol, 2,5-xylenol, 3,5-xylenol, 3,4-xylenol, and other xylenols; m-ethylphenol, p-ethylphenol, o-ethylphenol, 2,3,5-trimethylphenol, 2,3,5-triethylphenol, 4-tert-butylphenol, 3-tert-butylphenol, 2-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphenol, and other alkyl-substituted phenols; p-methoxyphenol, m-methoxyphenol, p-ethoxyphenol, m-ethoxyphenol, p-propoxyphenol, m-propoxyphenol, and other alkoxy-substituted phenols; o-isopropenylphenol, p-isopropenylphenol, 2-methyl-4-isopropenylphenol, 2-ethyl-4-isopropenylphenol, and other isopropenyl-substituted phenols; phenylphenol, and other aryl-substituted phenols; 4,4′-dihydroxybiphenyl, bisphenol A, resorcinol, hydroquinone, pyrogallol, and other polyhydroxyphenols. Each of these compounds can be used alone or in combination.
The aldehydes include, but are not limited to, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propion
Kohara Hidekatsu
Miyagi Ken
Nakayama Toshimasa
Niikura Satoshi
Shimatani Satoshi
Chu John S.
Tokyo Ohka Kogyo Co. Ltd.
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