Composition for lithographic anti-reflection coating, and...

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

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C430S271100

Reexamination Certificate

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06416930

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition for lithographic anti-reflection coating, and a resist laminate using the composition.
2. Description of the Related Art
Photolithography technique is employed in the manufacture of a semiconductor device, in which a photoresist film is formed on a substrate such as silicon wafer, the photoresist film is subjected to selective irradiation with an active ray or radiation such as ultraviolet ray, far ultraviolet ray, excimer laser, X-ray, and electron beam, is subjected to development to thereby form a resist pattern on the substrate. Such photoresists include a negative photoresist in which unexposed portions to the active ray or radiation are dissolved and removed in development, and a positive photoresist in which, in contrast, exposed portions to the active ray or radiation are dissolved and removed in development. In photolithography, these negative and positive photoresists are appropriately selected and used according to intended purpose.
In the photolithographic formation of a resist pattern, it is known that multiple interference of light occurs in a photoresist film, and the width of the resist pattern varies with a varying thickness of the photoresist film. The multiple interference of light occurs because irradiated light of single wavelength coming into the photoresist film formed on a substrate interferes with reflected light from the substrate, and the quantity of absorbed light energy varies in the thickness direction of the photoresist film. The variation in the thickness of photoresist film affects the width of the resulting resist pattern after development, to thereby deteriorate the dimensional precision of the resist pattern. Particularly, the deteriorated dimensional precision of the resist pattern becomes a significant problem when a fine pattern is formed on a substrate having steps, as the thickness of the photoresist film inevitably varies on projections and depressions of the steps. Demands have been made to develop a technique that can avoid the interferential action and can prevent deterioration in dimensional precision even in a fine pattern formed on a substrate having steps.
A conventional approach to reduce the interferential action includes the formation of an anti-reflection coating on the photoresist film, as described in, for example, Japanese Patent Laid-Open Nos. 5-188598 and 8-15859. In these conventional technologies, an anti-reflection coating is formed by using a coating solution mainly containing a water-soluble film-forming component and a fluorine-containing surfactant.
However, the conventional coating solution yields a precipitate when it is dissolved with a photoresist in an edge bead remover. When the application of the photoresist composition and the formation of an anti-reflection coating by the application of the coating solution are sequentially performed using one coater, a waste fluid pipe is plugged with waste fluids of the photoresist composition and the coating solution formed by rinsing with the edge bead remover. This problem has been conventionally solved by the arrangement of a coater for the composition for anti-reflection coating and a waste fluid pipe separately, in addition to a coater for the photoresist composition and a waste fluid pipe therefor. However, this type of equipment configuration requires extra time and effort in operations, and is not efficient, and is an obstacle to save space in a clean room.
Materials for anti-reflection coating are also proposed in, for example, Japanese Patent laid-Open Nos. 8-95253 and 10-69091, in addition to the above conventional technologies. These technologies, however, have not yet solved the above problems.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a composition for lithographic anti-reflection coating which has balanced compatibility with conventional photoresist composition, as well as to provide a resist laminate using the composition. By using the composition, a semiconductor device can be efficiently produced without the clogging of waste fluids of a coating solution and photoresist composition produced by the rinsing with an edge bead remover in a waste fluid pipe, even when the application of the photoresist composition and the formation of the anti-reflection coating are sequentially performed using one coater. This composition is also advantageous for saving space in a clean room.
Specifically, the present invention provides, in one aspect, a composition for lithographic anti-reflection coating, which includes a copolymer of vinylimidazole with a water-soluble film-forming monomer other than vinylimidazole; and a fluorine-containing surfactant.
In the composition, the water-soluble film-forming monomer may be at least one selected from among vinyl monomers, cellulosic monomers, and acrylic monomers.
The water-soluble film-forming monomer in the composition is preferably a vinyl monomer such as vinylpyrrolidone.
In the aforementioned composition, the weight ratio of vinylimidazole to the water-soluble film-forming component other than vinylimidazole is preferably in a range from 1:99 to 40:60, and is more preferably in a range from 5:95 to 20:80.
In another aspect, the present invention provides a resist laminate which is obtained by forming an anti-reflection coating on the surface of a photoresist film, which anti-reflection coating is prepared by the use of the composition.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described in detail below.
A composition of the present invention comprises a copolymer of vinylimidazole with a water-soluble film-forming monomer other than vinylimidazole.
The water-soluble film-forming monomer is not specifically limited and includes any of water-soluble film-forming monomers as far as they are soluble in water and have transparency to irradiated light. A preferred water-soluble film-forming monomer can form a uniform coating by a conventional coating means such as spin coating, does not form an altered or deteriorated layer between a photoresist film even when the resulting coating solution is applied on the photoresist film, and can form a coating which is sufficiently transparent to an active ray or radiation, has a small absorption coefficient and has a high transparency.
Such water-soluble film-forming monomers include, but are not limited to, vinyl alcohol, vinylpyrrolidone, vinyl acetate, and other vinyl monomers; hydroxypropylmethylcellulose phthalate, hydroxypropylmethylcellulose acetate phthalate, hydroxypropylmethylcellulose acetate succinate, hydroxypropylmethylcellulose hexahydrophthalate, hydroxypropylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, cellulose acetate hexahydrophthalate, carboxymethyl cellulose, ethyl cellulose, methyl cellulose, and other cellulosic monomers; N,N-dimethylacrylamide, N,N-dimethylaminopropylmethacrylamide, N,N-dimethylaminopropylacrylamide, N-methylacrylamide, diacetone acrylamide, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, N,N-dimethylaminoethyl acrylate, acryloyl morpholine, acrylic acid, and other acrylic monomers. Among these, vinyl monomers are preferred, of which vinylpyrrolidone is advantageous. Each of these water-soluble film-forming monomers can be used alone or in combination.
The weight ratio of vinylimidazole to the water-soluble film-forming monomer other than vinylimidazole preferably falls in a range from 1:99 to 40:60, and more preferably from 5:95 to 20:80.
The invented composition further comprises a fluorine-containing surfactant (surface active agent). The fluorine-containing surfactant is not specifically limited as far as it contains at least one fluorine atom and has surface active effect. The fluorine-containing surfactant is preferably composed of at least one selected from a salt of an alkanolamine or quaternary ammonium compound with a compound represented by the following formula (I):
RfCOOH  (I)
wherein Rf is a fluorinat

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