JP3628010B2 - Resin pattern refinement coating forming agent and fine resist pattern forming method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating forming agent for refining a resist pattern used for forming a fine resist pattern by bringing the distance between the patterns closer to each other by applying heat on a resist pattern formed using a photoresist and then heating the resist pattern. The present invention relates to a method for forming a fine resist pattern using a coating forming agent.
[0002]
[Prior art]
In recent years, with the progress of miniaturization of semiconductor elements, further miniaturization is required in the lithography process in the manufacture thereof. That is, in the lithography process, microfabrication of 0.20 μm or less is currently required, and a photoresist material corresponding to irradiation light with a short wavelength such as KrF excimer laser light, ArF excimer laser light, or F ₂ excimer laser light is used. Various methods for forming fine patterns have been studied.
[0003]
In such a lithography technique, there is an unavoidable limit on the miniaturization due to the limitation of the exposure wavelength, so far, research has been conducted to enable the formation of fine patterns exceeding the wavelength limit. . That is, for example, after patterning an electron beam resist such as polymethyl methacrylate and applying a positive resist on the resist pattern, a heat treatment is performed to provide a reaction layer at the boundary between the resist pattern and the positive resist layer. A method of refining a resist pattern by removing a non-reacting portion of a mold resist (Patent No. 2723260), and using an acid generator or thermal crosslinking with an acid between a lower resist pattern and an upper resist A method for forming a reaction layer (Japanese Patent Laid-Open No. 6-250379), as an upper layer resist coating solution, a fine solution in which a water-soluble resin, a water-soluble crosslinking agent, or a mixture thereof is dissolved in a water-soluble solvent without containing a photosensitive component Method of manufacturing semiconductor device using pattern forming material (Japanese Patent Laid-Open No. 10-73927), chemical amplification on substrate A photosensitive layer made of resist is provided, and after image formation exposure, development processing is performed to form a resist pattern. On this resist pattern, a water-soluble resin such as polyvinyl acetal and a water-soluble resin such as tetra (hydroxymethyl) glycoluril are formed. After applying a film-forming agent containing a crosslinking agent, a water-soluble nitrogen-containing organic compound such as an amine, and optionally a fluorine- and silicon-containing surfactant, a heat treatment is performed to form a resist pattern and a resist pattern refinement coating film. A method of forming a water-insoluble reaction layer at the interface with the substrate and then removing a non-reacted portion of the resist pattern refinement coating film with a solvent (Japanese Patent Laid-Open No. 2000-347414) has been proposed.
[0004]
These methods are preferable in that the wavelength limit of the photosensitive resist (lower layer resist) is exceeded and the pattern can be easily miniaturized with the fine pattern forming material (upper layer resist). Cross-linking of the fine pattern forming material up to the unnecessary part of the bottom part, a skirted shape, the perpendicularity of the cross-sectional shape of the fine pattern forming material is poor, or the upper resist pattern size is cross-linked However, it is not satisfactory enough because it is affected by mixing baking, which is heating. In addition, these processes are highly dependent on heat of several tens of nm / ° C., and it is difficult to maintain a uniform temperature in the wafer surface when the substrate is enlarged and the pattern is miniaturized. There is a drawback in that the dimensional controllability is reduced.
[0005]
In addition, a so-called thermal flow process has been proposed in which a photoresist pattern is formed on a substrate and then subjected to heat or radiation to fluidize the photoresist pattern to make the pattern dimension smaller than the resolution limit (Japanese Patent Laid-Open No. Hei. 1-307228 and JP-A-4-364221).
[0006]
However, this method has a drawback that it is difficult to control the flow of the resist by heat or radiation, and a product having a constant quality cannot be obtained. Further, as a method of developing this heat flow process, there is a method (Japanese Patent Laid-Open No. 7-45510) in which a photoresist pattern is formed on a substrate and then a water-soluble resin film is provided thereon to control the flow of the photoresist. Although proposed, a water-soluble resin such as polyvinyl alcohol used in this method has a drawback that it has insufficient solubility and stability over time required when removed with water, and a residue is generated.
[0007]
[Problems to be solved by the invention]
The present invention is, under such circumstances, photoresist is coated on a resist pattern formed by using, is brought closer the distance between the patterns by heat treatment, for use in forming a fine resist pattern A coating formation agent for refining a resist pattern, which can smoothly shrink a resist pattern by heat treatment, and can be easily removed by washing with water after the heat treatment of the resist pattern, and the like The object of the present invention is to provide a method for efficiently forming a fine resist pattern.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the inventors of the present invention have developed a coating forming agent for refining a resist pattern, which contains a water-soluble resin composed of a copolymer of vinylpyrrolidone and another specific monomer. As a result, it has been found that a fine resist pattern can be efficiently formed by using the water-soluble resin, and the present invention has been completed based on this finding.
[0009]
That is, the present invention provides a resist pattern comprising an aqueous solution containing a copolymer of (A) vinyl pyrrolidone and (B) at least one monomer selected from vinyl alcohol, vinyl acetate and vinyl imidazolidinone. A coating forming agent for refining a resist pattern to be removed after applying a heat treatment to bring the distance between the resist patterns closer, and a step of forming a resist pattern on the substrate, the whole or part of the resist pattern In the fine pattern forming method comprising a step of providing a water-soluble resin film on the substrate, a step of heat-treating the substrate to bring the distance between the resist patterns closer, and a step of washing and removing the water-soluble resin film, A) vinylpyrrolidone and (B) vinyl alcohol, vinyl acetate and vinyl imidazolidinone The use of the copolymer of at least one monomer selected from those which provide a fine resist pattern forming method comprising.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Resist for pattern fining coating formation agent of the present invention, which comprises a water soluble resin comprising a copolymer, as component (A) monomer starting materials in the copolymer, vinylpyrrolidone is used.
On the other hand, as the component (B) monomer Another raw material, polyvinyl alcohol, at least one selected from among vinyl acetate and vinyl imidazolidinone is used.
[0011]
The copolymer used in the present invention has a high effect of bringing the resist patterns close to each other and a high effect of maintaining the pattern shape as compared with the case of using a homopolymer. In such a copolymer, the component (A) and the component (B) are usually selected in a molar ratio of 1: 9 to 9: 1.
When stability over time is required for the copolymer, the stability over time can be improved by adding an acidic compound such as p-toluenesulfonic acid or dodecylbenzenesulfonic acid.
[0012]
Although there is no restriction | limiting in particular as molecular weight of this copolymer, From points, such as a film formation property and the heat resistance at the time of heat processing, it is the mass mean molecular weight of polymethylmethacrylate conversion measured by the gel permeation chromatography method (GPC method). A range of 10,000 to 50,000 is preferred.
[0013]
The coating-forming agent of the present invention is an aqueous solution containing the above-mentioned copolymer, but can optionally contain other water-soluble resins as long as the object of the present invention is not impaired. Examples of the other water-soluble resins include cellulose derivatives, alkylene glycol polymers, urea polymers, melamine polymers, and the like.
[0014]
Here, as the cellulose derivative, for example, hydroxypropylmethylcellulose phthalate, hydroxypropylmethylcellulose acetate phthalate, hydroxypropylmethylcellulose hexahydrophthalate, hydroxypropylmethylcellulose acetate succinate, hydroxypropylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, cellulose Acetate hexahydrophthalate, carboxymethylcellulose, ethylcellulose, methylcellulose, etc., as alkylene glycol polymers, for example, addition polymers or addition copolymers such as ethylene glycol, propylene glycol, butylene glycol, etc., as urea polymers For example, methylolated urea, dimethylo Le urea, polymers such as ethylene urea, the melamine polymer, such as methoxymethyl melamine, methoxymethylated isobutoxymethyl melamine, polymers such as methoxyethyl melamine may be mentioned, respectively. In addition, water-soluble epoxy polymers and amide polymers can be used. These water-soluble resins may be used alone or in combination of two or more.
[0015]
As the solvent in the coating forming agent of the present invention, water is used, but if desired, a mixed solvent of water and an alcohol solvent can be used. Examples of such alcohol solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3- Butylene glycol. These alcohol solvents are used by mixing up to 30% by mass with respect to water. The concentration of the resin component in this aqueous solution is usually 3 to 50% by mass, preferably 5 to 20% by mass, from the viewpoint of applicability and the like.
[0016]
The fine resist pattern forming method of the present invention comprises (a) a resist pattern forming step, (b) a water-soluble resin film forming step, (c) a heat treatment step, and (d) a water washing step, which are desired by sequentially performing these steps. The fine resist pattern can be efficiently formed.
[0017]
(A) step;
This step is a step of forming a resist pattern on the substrate using a photoresist. The formation of the resist pattern in the production of semiconductor devices, fine pattern forming method commonly used, on a substrate such as a silicon wafer, a chemical amplification resist, electron beam resist or F ₂ resist solution spinner etc. And dried to form a photosensitive layer, which is irradiated with a reduction projection exposure apparatus or the like through a desired mask pattern such as ultraviolet light, deep-UV, excimer laser light, or drawn by an electron beam, This can be carried out by a method of forming a resist pattern by heating and then developing with a developer, for example, an alkaline aqueous solution such as an aqueous solution of 1 to 10% by mass of tetramethylammonium hydroxide.
[0018]
(B) step;
This step is a step of providing a water-soluble resin film on the entire surface or part of the resist pattern formed in the step (a). The water-soluble resin film is formed by using the above-described coating forming agent for refining a resist pattern of the present invention. As a film forming method, the coating forming agent is applied to the entire surface or a part of the resist pattern by a spinner or the like according to a method usually performed in a conventional heat flow process to form a coating layer. In this case, a heat drying process may be added as necessary. The thickness of this coating film is advantageously about 0.1 to 0.5 μm.
[0019]
(C) step;
This step is a step in which the resist pattern having the water-soluble resin film provided in the step (b) is heat-treated to bring the distance between the resist patterns closer. The heat treatment of the resist pattern is usually performed by heat treatment at a temperature in the range of 80 to 160 ° C. for about 30 to 120 seconds. At this time, if the heat treatment is performed at a temperature lower than the softening point of the resist pattern, This is preferable because the pattern is pulled by the resin, the holes or trenches are further miniaturized, and the shrinkage rate does not vary due to the difference in duty ratio.
By this process, for example, the distance between the resist patterns is reduced from about 220 nm to 160 nm in the case of a trench, and from about 180 nm to 160 nm in the case of a hole.
[0020]
(D) step;
This step is a step of washing and removing the water-soluble resin film present on the resist pattern heat-treated in the step (c). The water-soluble resin film can be completely removed by washing with an aqueous solvent, preferably pure water, for about 10 to 60 seconds.
In this manner, a finer pattern can be formed from the fine resist pattern formed by the lithography technique. The resist pattern at this time may be a trench type pattern or a hole type pattern.
[0021]
【Example】
Next, the present invention will be described in more detail with reference to examples .
[0022]
Example 1
A coating forming agent comprising a water-soluble resin aqueous solution in which 5 g of a copolymer of vinylpyrrolidone and vinylimidazolidinone (mass ratio 1: 3) was dissolved in 45 g of water was prepared.
A positive photoresist (trade name “TDUR-P036PM” manufactured by Tokyo Ohka Kogyo Co., Ltd., softening point: about 122 ° C. ) is applied onto a silicon wafer substrate by spinner coating and baked at 80 ° C. for 90 seconds to obtain a film thickness of 560 nm. A photoresist film was formed.
Next, the photoresist film was subjected to an exposure process using an exposure apparatus (trade name “Canon FPA-3000EX3” manufactured by Canon Inc.), followed by heat treatment at 120 ° C. for 90 seconds, and then 2.38 mass% tetramethylammonium hydroxy. A photoresist pattern having a size of 180.3 nm was formed by developing with an aqueous solution.
Next, the coating forming agent was applied on the resist pattern thus obtained, and the resist film was thermally contracted by heat treatment at 120 ° C. for 60 seconds. Subsequently, the film was washed with pure water at 23 ° C. for 60 seconds. As a result, the coating forming agent was completely removed, and a photoresist pattern (hole pattern) having a vertical dimension of 170.1 nm was obtained.
[0023]
Comparative Example 1
In Example 1, except that the coating forming agent was not applied, the same operation as in Example 1 was performed to form a photoresist pattern, but no change was observed in the pattern shape.
[0024]
Example 2
On the silicon wafer substrate, a photoresist (trade name “TDMR-AR2000” manufactured by Tokyo Ohka Kogyo Co., Ltd., softening point: about 130 ° C. ) is applied with a spinner and baked at 90 ° C. for 90 seconds to obtain a film thickness of 1.3 μm. A photoresist film was formed.
Next, the photoresist film was subjected to an exposure process using an exposure apparatus (trade name “Nikon NSR-2205i14E” manufactured by Nikon Corporation), followed by heat treatment at 110 ° C. for 90 seconds, and then 2.38 mass% tetramethylammonium hydroxy. A photoresist pattern having a size of 411.1 nm was formed by development using an aqueous solution.
Thereafter, by performing the same operation as in Example 1, a photoresist pattern (trench pattern) having a vertical dimension of 345.3 nm was obtained.
[0025]
Comparative Example 2
In Example 2, except that the coating forming agent was not applied, the same operation as in Example 2 was performed to form a photoresist pattern, but no change was observed in the pattern shape.
[0026]
Comparative Example 3
In Example 2, a photoresist pattern was formed by performing the same operation as in Example 2 except that a 5% by weight aqueous solution of polyvinyl alcohol was used as the coating forming agent. As a result, a residue was clearly observed on the substrate. It was.
[0027]
Example 3
When the same treatment as in Example 1 was performed using a coating forming agent comprising a water-soluble resin aqueous solution in which 5 g of a copolymer of vinyl pyrrolidone and vinyl acetate (mass ratio 3: 2) was dissolved in 45 g of water, The time was 1 second, and a photoresist pattern having a dimension of 171.5 nm was obtained.
In addition, the dimension of the photoresist pattern before apply | coating a coating formation agent and heat-processing was 180.3 nm.
[0028]
Comparative Example 4
A positive photoresist (trade name “TDUR-P036PM”, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied onto a silicon wafer substrate by spinner coating and baked at 80 ° C. for 90 seconds to form a photoresist film having a thickness of 560 nm. .
Next, the photoresist film was subjected to an exposure process using an exposure apparatus (trade name “Canon FPA-3000EX3” manufactured by Canon Inc.), followed by heat treatment at 120 ° C. for 90 seconds, and then 2.38 mass% tetramethylammonium hydroxy. A hole-type resist pattern having a size of 178.1 nm was obtained by developing with a developing aqueous solution.
Next, a coating forming agent comprising a water-soluble resin aqueous solution in which 5.0 g of polyvinyl pyrrolidone was dissolved in 45 g of water was applied, and the resist film was thermally contracted by heat treatment at 120 ° C. for 60 seconds. Subsequently, it was washed with pure water at 23 ° C. for 60 seconds to remove the coating forming agent, thereby obtaining a hole type photoresist pattern having a vertical dimension of 168.7 nm .
[0029]
【The invention's effect】
According to the present invention, when a fine resist pattern is formed by forming a fine resist pattern by applying a heat treatment to the resist pattern without forming a cross-link with an acid, and making the distance between the resist patterns close by heat treatment. A coating formation agent for refining a resist pattern, which can make the distance between resist patterns close by heat treatment and can be easily removed by water washing after the heat treatment of the resist pattern. Can do.
By using this coating forming agent, a fine resist pattern exceeding the limit of the optical means can be obtained, and can be widely used in the field of manufacturing semiconductor devices, liquid crystal display elements, magnetic heads and the like.

Claims (3)

Coating on a resist pattern comprising an aqueous solution containing a copolymer of (A) vinyl pyrrolidone and (B) at least one monomer selected from vinyl alcohol, vinyl acetate and vinyl imidazolidinone, and heat treatment A resist pattern miniaturization coating-forming agent for removing the resist pattern after making the distance between the resist patterns approach by. The coating forming agent for refining a resist pattern according to claim 1, wherein the molar ratio of the component (A) to the component (B) is 1: 9 to 9: 1. A step of forming a resist pattern on the substrate, a step of providing a water-soluble resin coating on the entire surface or a part of the resist pattern, a step of heat-treating the substrate to bring the distance between the resist patterns close, and washing the water-soluble resin coating with water In the method for forming a fine pattern comprising the step of removing, as the water-soluble resin, (A) vinylpyrrolidone and (B) at least one monomer selected from vinyl alcohol, vinyl acetate and vinylimidazolidinone. A method for forming a fine resist pattern, comprising using a copolymer.