Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2000-08-16
2001-08-07
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, C430S196000
Reexamination Certificate
active
06270939
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a radiation-sensitive resin composition comprising a solution of an alkali-soluble resin and a radiation-sensitive compound dissolved in a solvent, which composition is sensitive to radiations such as ultraviolet rays, far-ultraviolet rays, X-rays, electron beams, molecular beams, gamma-rays, synchrotron radiations, proton beams and the like.
2. Description of the Invention
The resist compositions currently used in making integrated circuits comprises an alkali-soluble resin and a radiation-sensitive compound, and more specifically known are (a) positive type resist compositions comprising an alkali-soluble resin and a 1,2-quinonediazide compound and (b) negative type resist compositions comprising an alkali-soluble resin and an azide compound.
When these resist compositions comprising an alkali-soluble resin and a radiation-sensitive compound are exposed to a radiation through a mask and then subjected to development with a developer consisting of an aqueous alkaline solution, the exposed portions in the case of the positive type resist compositions or the non-exposed portions in the case of the negative type resist compositions are dissolved in the developer, whereby a resist pattern which is faithful to the mask and has a high resolution is obtained. Therefore, resist compositions comprising an alkali-soluble resin, which are excellent in resolution, have been often used in recent years during which higher integration of integrated circuits has been demanded.
However, resist compositions comprising a solution of an alkali-soluble resin and a radiation-sensitive compound in a solvent have the following drawbacks: When the resist compositions are filtered through a filter having a pore diameter of, for example, 0.2 &mgr;m and then allowed to stand, it happens in some cases that fine particles which are too fine to observe visually are formed in the compositions, and when the compositions containing the resulting fine particles are further stored for a long period of time, precipitation comes to be observed. In such resist compositions, the fine particles have, in some cases, a particle diameter of at least 0.5 &mgr;m. When a resist composition containing fine particles having such a large particle diameter is used to form a resist pattern of about 1 &mgr;m on a wafer, the fine particles remain at the substrate portion where the resist is removed by development, resulting in a reduction of resolution. Further, when a substrate is etched through a resist pattern formed from a resist composition containing such fine particles, pin holes appear also at the substrate portion covered with the resist pattern, resulting in a reduction of yield in the manufacture of integrated circuits.
SUMMARY OF THE INVENTION
This invention aims at solving the above-mentioned problems to provide a radiation-sensitive resin composition which is very low in formation of fine particles and suited for use as a resist.
According to this invention, there is provided a radiation-sensitive resin composition comprising a solution of an alkali-soluble resin and a radiation-sensitive compound in a solvent, characterized in that the solvent comprises a monooxymonocarboxylic acid ester.
DETAILED DESCRIPTION OF THE INVENTION
The monooxymonocarboxylic acid ester used as the solvent in this invention is preferably a compound represented by the formula (I):
R
1
O—R
2
—COOR
3
(I)
wherein R
1
is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or an acyl group having 1 to 4 carbon atoms; R
2
is an alkylene group having 1 to 4 carbon atoms; and R
3
is an alkyl group having 1 to 4 carbon atoms.
Specific examples of the monooxymonocarboxylic acid ester include alkyl oxyacetates such as methyl oxyacetate, ethyl oxyacetate, butyl oxyacetate and the like; alkyl alkoxyacetates such as methyl methoxyacetate, ethyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate and the like; alkyl 3-oxypropionates such as methyl 3-oxypropionate, ethyl 3-oxypropionate and the like; alkyl 3-alkoxypropionates such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate and the like; alkyl 2-oxypropionates such as methyl 2-oxypropionate, ethyl 2-oxypropionate, propyl 2-oxypropionate and the like; alkyl 2-alkoxypropionates such as ethyl 2-methoxypropionate, propyl 2-methoxypropionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate and the like; alkyl 2-oxy-2-methyl propionates such as methyl 2-oxy-2-methylpropionate, ethyl 2-oxy-2-methylpropionate and the like; alkyl 2-alkoxy-2-methylpropionates such as methyl 2-methoxy-2-methylpropionate, methyl 2-ethoxy-2-methylpropionate and the like; alkyl 2-oxy-3-methylbutanoates such as methyl 2-oxy-3-methylbutanoate, ethyl 2-oxy-3-methylbutanoate and the like; and alkyl 2-alkoxy-3-methylbutanoates such as methyl 2-methoxy-3-methylbutanoate, methyl 2-ethoxy-3-methylbutanoate, ethyl 2-ethoxy-3-methylbutanoate and the like. Alkyl 2-oxypropionates are preferred, and methyl 2-oxypropionate and ethyl 2-oxypropionate are particularly preferred. These monooxymonocarboxylic acids may be used alone or in combination of two or more.
In this invention, the solvent may be a mixture of the monooxymonocarboxylic acid ester and at least one other solvent in an amount of, for example, less than 70% by weight, preferably less than 50% by weight and more preferably less than 30% by weight, based on the weight of the mixture. Most preferably, only the monooxymonocarboxylic acid esters are used as the solvent.
In this invention, the content of the solvent comprising a monooxymonocarboxylic acid ester in the radiation-sensitive resin composition is usually 40 to 90%, preferably 50 to 85%, by weight based on the weight of the composition.
Said other solvent includes ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, benzyl ethyl ether, dihexyl ether and the like; esters such as methyl cellosolve acetate, ethyl cellosolve acetate, ethyl acetate, butyl acetate, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, ethylene carbonate, propylene carbonate, &ggr;-butyrolactone and the like; ketones such as methyl ethyl ketone, cyclohexanone, diisobutyl ketone, acetonylacetone, isophorone and the like; fatty acids such as caproic acid, capric acid and the like; alcohols such as 1-octanol, 1-nonanol, benzyl alcohol and the like; aromatic hydrocarbons such as toluene, xylene and the like; and so forth. These solvents may be used alone or in combination of two or more.
Typical examples of the alkali-soluble resin used in this invention are alkali-soluble novolak resins (hereinafter referred to simply as “novolaks”). These novolaks can be obtained by subjecting a phenol and an aldehyde to addition condensation in the presence of an acid catalyst.
The phenol includes, for example, phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, m-butylphenol, p-butylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, p-phenylphenol, hydroquinone, catechol, resorcinol, 2-methylresorcinol, pyrogallol, &agr;-naphthol, bisphenol A, dihydroxybenzoic acid esters and gallic acid esters. Preferred as these compounds are phenol, o-cresol, m-cresol, p-cresol, 2,5-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, resorcinol, 2-methylresorcinol and bisphenol A. These phenols may be used alone or in combination of two or more.
The aldehyde includes, for example, formaldehyde, paraformaldehyde, acetaldehyde, propyl aldehyde, benzaldehyde, phenylacetaldehyde, &agr;-phenylpropyl aldehyde, &bgr;-phenylpropyl aldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde and p-n-butylbenzaldehyde. Preferre
Harita Yoshiyuki
Hosaka Yoshihiro
Nozue Ikuo
Takatori Masashige
JSR Corporation
Kelber Steven B.
Piper Marbury Rudnick & Wolfe LLP
Young Christopher G.
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