JP2000267268A - Fine pattern forming material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fine pattern forming material and a method to form a fine pattern using this material so that the material shows good storage stability and proper crosslinking reaction property when used to form a finer resist pattern by an usual lithographic technique. SOLUTION: The fine pattern forming material is prepared by dissolving a crosslinking agent completely soluble with water selected from glycol lauryl having at least one imino group with hydroxyalkyl group substituted for a hydrogen atom, and a water-soluble resin in a water-based solvent. In the process to form a fine pattern, a resist pattern is formed from a chemically amplifying resist containing an acid producing agent on a substrate, forming a coating film of the fine pattern forming material thereon, heating to form a water- insoluble reaction layer on the interface between the resist pattern and the coating film and then removing the unreacted part of the coating film with a water-based solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for further miniaturizing a resist pattern formed by a usual lithography technique using a chemically amplified resist containing an acid generator, and has excellent storage stability. The present invention relates to a fine pattern forming material having appropriate cross-linking reactivity and capable of cross-linking only necessary portions, and a method for efficiently forming a fine pattern using the material.

[0002]

2. Description of the Related Art In recent years, in the field of semiconductor device manufacturing, the wiring and isolation width required for the manufacturing process have become extremely fine as the degree of integration of devices increases.
For this reason, the wavelength of active rays used in lithography techniques has been shortened, and techniques using i-rays (365 nm), far ultraviolet rays, excimer laser light, and the like are becoming core. On the other hand, in the lithography technique, a chemically amplified resist has been used as a photoresist. This chemically amplified resist is a resist that utilizes the catalytic action of an acid generated by irradiation of radiation, has high sensitivity and resolution, and is a compound that generates an acid by irradiation of radiation, a so-called acid generator. It has the advantage that the amount used may be small.

However, even in such a lithography technique, there is an unavoidable limitation in miniaturization due to the limitation of the exposure wavelength. Therefore, in order to enable formation of a fine pattern exceeding the wavelength limit, many improvements have been proposed for a fine pattern forming material provided on a resist pattern formed by a lithography technique and a fine pattern forming method using the same. (Patent No. 2723)
No. 260, JP-A-5-241348, JP-A-6-250379, JP-A-7-281449
JP-A-10-73927, JP-A-10-73927
No. 163093).

[0004] For example, Japanese Patent No. 2723260 discloses that an electron beam resist such as polymethyl methacrylate is patterned, a positive resist is applied on the resist pattern, and the resist pattern is heated and treated. A method of providing a reaction layer at the boundary of a resist layer and removing a non-reactive portion of a positive resist to make a resist pattern finer is described. JP-A-6-250379 describes the use of an acid generator or thermal crosslinking by an acid to form a reaction layer between a lower resist pattern and an upper resist. Further, JP-A-10-73927 discloses, as an upper layer resist coating solution, a fine pattern-forming material containing no photosensitive component, a water-soluble resin or a water-soluble crosslinking agent, or a mixture thereof dissolved in a water-soluble solvent. A method for manufacturing a semiconductor device using this is described.

[0005] These methods are preferable in that the resist pattern can be miniaturized beyond the wavelength limit of the photosensitive resist at low cost, but there are some problems for practical use. For example, in the method described in JP-A-10-73927, when a fine pattern forming material (upper resist coating solution) is applied on a lower resist pattern, a water-soluble material is used so as not to dissolve the lower resist pattern. Melamine aqueous solution and ethylene urea aqueous solution do not completely dissolve the water-soluble cross-linking agent, so it is necessary to contain a small amount of isopropanol.If the amount of the lower alcohol is small, the stability over time is poor. The cross-linking agent precipitates, and if the lower alcohol content is increased so as not to precipitate, the resist pattern also dissolves. Therefore, it is necessary to use a completely water-soluble crosslinking agent as the water-soluble crosslinking agent.

As such a completely water-soluble crosslinking agent,
Alkoxymethylated urea is known, but although this is improved in terms of water solubility, the crosslinking reactivity is large, and when left in an aqueous solution for a few days, a crosslinked product precipitates out, so that the stability over time is also observed. Not enough. Further, when this is applied on a lower resist pattern and heated, the resist pattern is entirely covered, causing a disadvantage that unnecessary portions are crosslinked and lack reproducibility.

[0007]

SUMMARY OF THE INVENTION Under the above circumstances, the present invention provides good storage stability when used for further miniaturizing a resist pattern formed by a usual lithography technique. The object of the present invention is to provide a fine pattern forming material having appropriate cross-linking reactivity and capable of cross-linking only necessary portions, and a method for efficiently forming a fine pattern using the material. Things.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies on materials suitable for forming fine patterns, and as a result,
As a completely water-soluble crosslinking agent, a glycoluril in which a hydrogen atom of an imino group is substituted with a hydroxyalkyl group,
This and a material in which a water-soluble resin is dissolved in an aqueous medium,
It has been found that a good result can be obtained as a material for forming a fine pattern, and that a good fine pattern can be formed by using this material, and the present invention has been completed based on this finding.

That is, the present invention provides (A) at least one
A completely water-soluble cross-linking agent selected from glycoluril in which hydrogen atoms of two imino groups have been substituted with hydroxyalkyl groups, (B) a fine pattern-forming material obtained by dissolving a water-soluble resin in an aqueous medium, and Providing a photosensitive layer comprising a chemically amplified resist containing an acid generator on a substrate, after selective exposure, a developing process to form a resist pattern,
A step of forming a coating film made of the fine pattern forming material on the resist pattern, a step of forming a water-insoluble reaction layer at an interface between the resist pattern and the coating film made of the fine pattern forming material by heat treatment, and An object of the present invention is to provide a method for forming a fine pattern, which comprises sequentially performing a step of removing unreacted portions of a coating film made of a fine pattern forming material with an aqueous solvent.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the fine pattern forming material of the present invention, the hydrogen atom of at least one of the four imino groups is a hydroxyalkyl group as the completely water-soluble crosslinking agent of the component (A). Glycoluril substituted with is used. The hydroxyalkyl group is preferably a hydroxymethyl group, and such N-hydroxymethyl group-substituted glycoluril is water-soluble, thermally crosslinkable, miscible with the water-soluble resin as the component (B), and has good storage stability. From the viewpoint of properties and the like, tetra (hydroxymethyl) glycoluril in which all hydrogen atoms of four imino groups are substituted with hydroxymethyl groups is preferred. This product can be obtained, for example, as a commercial product “Cymel 1172” (trade name, manufactured by Mitsui Cytec). Such N-hydroxymethyl group-substituted glycoluril can be easily produced by a known method, for example, by reacting glycoluril with formalin in an aqueous medium to form methylol. In the present invention, as the component (A), the complete water-soluble crosslinking agent may be used alone or in combination of two or more.

On the other hand, as the water-soluble resin of the component (B),
For example, polyvinyl acetal, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethylene imine, polyethylene oxide, polyvinyl amine, polyallyl amine, styrene-maleic anhydride copolymer, oxazoline group-containing water-soluble resin, water-soluble melamine resin, water-soluble A urea resin, a water-soluble alkyd resin and the like can be mentioned, and among them, polyvinyl acetal is particularly preferable. This polyvinyl acetal is commercially available, for example, “S-LEC KW-1”, “S-LEC KW”
-3 "(all manufactured by Sekisui Chemical Co., Ltd., trade name). In the present invention, as the component (B), the water-soluble resin may be used alone or in combination of two or more.

The material for forming a fine pattern according to the present invention comprises an aqueous solution obtained by dissolving the components (A) and (B) in an aqueous medium. As the aqueous medium, water is generally used. Although water is used, if necessary, water containing an organic solvent miscible with water can be used as long as the object of the present invention is not impaired. From the viewpoint of the effect of the present invention, the use ratio of the component (A) and the component (B) is preferably in a range of 5:95 to 35:65 by weight, and particularly preferably in a range of 10:90 to 30:70. It is. The concentration of the components (A) and (B) in the aqueous solution is preferably such that the total amount thereof is 2 to 20% by weight, particularly 3 to 10% by weight.

In the fine pattern forming material of the present invention, if necessary, component (C) may be used in order to improve coatability.
A surfactant having a fluorine atom and a silicon atom in the molecule is added to the total amount of the components (A) and (B),
0.01-1.0% by weight, preferably 0.03-0.1%
It can be contained in the range of weight%. Preferred examples of the surfactant include a nonionic fluorine / silicone surfactant in which a perfluoroalkyl ester group, an alkylsiloxane group, and an oxyalkylene group are bonded. Such a surfactant can be obtained, for example, as a commercial product “MegaFac R-08” (trade name, manufactured by Dainippon Ink and Chemicals, Inc.).

Next, the fine pattern forming method of the present invention comprises:
It comprises a resist pattern forming step, a coating film forming step of a fine pattern forming material, a heat treatment step, and a step of removing non-reacted portions.

In the resist pattern forming step, a photosensitive layer made of a chemically amplified resist containing an acid generator is provided on a substrate, and after a selective exposure, a developing process is performed to form a resist pattern. As the chemically amplified resist containing the acid generator, any one of a positive type or a negative type conventionally used as a chemically amplified resist can be appropriately selected and used. This chemically amplified resist generally comprises, as basic components, an acid generator and a film-forming component whose solubility in an alkaline aqueous solution changes due to the action of the generated acid. Usually, polyhydroxystyrene or the like in which a part of a hydroxyl group is protected by a dissolution inhibiting group such as a tert-butoxycarbonyl group or a tetrahydropyranyl group is used. On the other hand, in the negative resist, as a film-forming component, usually a resin component such as polyhydroxystyrene or a polyhydroxystyrene or a novolak resin in which a part of the hydroxyl group is protected by the above-mentioned dissolution inhibiting group, such as a melamine resin or a urea resin. A combination of acid-crosslinkable substances is used. As a method of forming a resist pattern using such a chemically amplified resist, a conventionally used method of forming a resist pattern can be used. For example, a solution of a chemically amplified resist is applied on a substrate such as a silicon wafer with a spinner or the like, and dried to form a photosensitive layer, which is then exposed to ultraviolet light, deep-UV, excimer laser light by a reduction projection exposure apparatus or the like. Irradiation via a desired mask pattern, or drawing and heating with an electron beam. Then
This is developed using a developing solution, for example, an alkaline aqueous solution such as a 1 to 10% by weight aqueous solution of tetramethylammonium hydroxide to form a resist pattern.

Next, the coating film forming step is a step of forming a coating film made of the fine pattern forming material of the present invention on the resist pattern obtained in the resist pattern forming step. As a method for forming a coating film, usually, the material for forming a fine pattern is applied on a resist pattern by a spinner or the like, and then is applied at a temperature of about 80 to 90 ° C. for 30 minutes.
Heat drying for about 90 seconds to form a coating film.
The thickness of the coating is advantageously about 0.1 to 0.5 μm.

The heat treatment step is called mixing baking, and is a step of forming a water-insoluble reaction layer at the interface between the resist pattern and the coating film made of the fine pattern forming material by heat treatment. At this time, the heat treatment is generally performed at a temperature of about 100 to 110 ° C. for about 60 to 120 seconds. Thereby, the acid is leached from the resist pattern into the fine pattern forming material to cause a crosslinking reaction, and a water-insoluble reaction layer is formed at the interface between the resist pattern and the coating film.

The final removal step is a step of removing an unreacted portion of the coating film made of the fine pattern material with an aqueous solvent, while leaving a water-insoluble reaction layer formed in the heat treatment step. At this time, pure water is generally used as the aqueous solvent, and the unreacted portion is removed by rinsing with the pure water for 10 to 60 seconds. Through the above steps, a pattern finer than the resist pattern is formed. The resist pattern may be a line and space pattern or a hole pattern.

[0019]

The material for forming a fine pattern according to the present invention is excellent in storage stability, has appropriate crosslinking reactivity, can crosslink only necessary portions, and contains a chemically amplified resist containing an acid generator. Is used to further miniaturize a resist pattern formed by a normal lithography technique.

[0020]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 20 parts by weight of tetra (hydroxymethyl) glycoluril (manufactured by Mitsui Cytec Co., Ltd., trade name "Cymel 1172"), and polyvinyl acetal resin (manufactured by Sekisui Chemical Co., Ltd., trade name "ESLEK KW-1") 80 Part by weight and 0.1 part by weight of a nonionic fluorine / silicone surfactant (manufactured by Dainippon Ink and Chemicals, Inc., trade name "MegaFac R-08") are dissolved in 1900 parts by weight of water, and the solid content is 5 parts by weight. % Aqueous solution. Then, the solution was filtered using a membrane filter having a pore size of 0.2 μm to obtain a solution of a fine pattern forming material. When this solution was allowed to stand at 25 ° C. in a closed brown bottle, no precipitate was generated even after 180 days. Next, a trade name “TDUR-P0” which is a solution of a chemically amplified positive resist on a silicon wafer.
15 "(manufactured by Tokyo Ohka Kogyo Co., Ltd., containing an acid generator and polyhydroxystyrene substituted with a dissolution inhibiting group), and dried at 80 ° C. for 90 seconds to form a film having a thickness of 0.7 μm. A resist layer was formed. Next, after selectively irradiating an excimer laser beam through a mask with a reduction projection exposure apparatus FPA-3000EX3 (manufactured by Canon Inc.), heat treatment was performed at 120 ° C. for 90 seconds, and then 2.38 wt% tetramethylammonium Paddle development with an aqueous hydroxide solution for 65 seconds yields a 0.
A positive resist hole pattern of 25 μm was obtained. Next, a solution of the fine pattern forming material is spin-coated on the resist hole pattern,
A drying treatment was performed for 0 seconds to form a coating film having a thickness of 0.2 μm. Next, mixing baking is performed at 115 ° C. for 90 seconds,
Then, by rinsing with pure water for 20 seconds, 0.20μ
An m-hole pattern was formed in a good shape.

Example 2 The procedure of Example 1 was repeated, except that the amounts of tetra (hydroxymethyl) glycoluril and polyvinyl acetal resin were changed to 10 parts by weight and 90 parts by weight, respectively. % By weight aqueous solution. Subsequently, the solution was filtered using a membrane filter having a pore size of 0.2 μm to obtain a solution of a fine pattern forming material. When this solution was left at 25 ° C. in a closed brown bottle, no precipitate was generated even after 180 days. Next, in the same manner as in Example 1, 0.2
After a 5 μm positive resist hole pattern was formed, the solution of the fine pattern forming material was used to prepare a first example.
By performing the same operation as in the above, a hole pattern of 0.19 μm was formed in a good shape.

Comparative Example 1 In Example 1, methoxymethylolated melamine (trade name "Cymel 327" manufactured by Mitsui Cytec Co., Ltd.) was used in place of tetra (hydroxymethyl) glycoluril, and water was used instead of 1900 parts by weight of water. An isopropanol-water solution having a solid content of 5% by weight was prepared in the same manner as in Example 1 except that a mixture of 1805 parts by weight and 95 parts by weight of isopropanol was used. Then, the pore size is 0.2 μm
The solution of the fine pattern forming material was obtained by filtration using a membrane filter of No. When this solution was allowed to stand at 25 ° C. in a closed brown bottle, a precipitate was generated in one day.

Comparative Example 2 Example 1 was repeated except that methoxymethylolated urea (trade name “Nikarac MX-290”, manufactured by Sanwa Chemical Co., Ltd.) was used in place of tetra (hydroxymethyl) glycoluril. In the same manner as described above, an aqueous solution having a solid content of 5% by weight was obtained. Subsequently, the solution was filtered using a membrane filter having a pore size of 0.2 μm to obtain a solution of a fine pattern forming material. When this solution was allowed to stand at 25 ° C. in a closed brown bottle, a precipitate was generated in 3 days. Next, in the same manner as in Example 1, a 0.25 μm positive resist hole pattern was formed on a silicon wafer, and then a solution of the fine pattern forming material was used.
When the same operation as in Example 1 was performed, crosslinking was performed up to the bottom of the resist hole pattern.

Claims (6)

[Claims] 1. An aqueous medium comprising: (A) a completely water-soluble crosslinking agent selected from glycoluril in which at least one hydrogen atom of an imino group is substituted with a hydroxyalkyl group; and (B) a water-soluble resin in an aqueous medium. Fine pattern forming material obtained by melting. 2. The component (A) wherein the completely water-soluble crosslinking agent is tetra (hydroxymethyl) glycoluril.
The material for forming a fine pattern according to the above. 3. The fine pattern forming material according to claim 1, wherein the water-soluble resin as the component (B) is polyvinyl acetal. 4. The composition according to claim 1, wherein component (A) and component (B) are contained in a weight ratio of 5:95 to 35:65.
4. The fine pattern forming material according to 2 or 3. 5. A surfactant having a fluorine atom and a silicon atom in the molecule as the component (C),
0.01 to 1.0 with respect to the total amount of the component and the component (B).
The material for forming a fine pattern according to any one of claims 1 to 4, wherein the material is contained in a proportion of% by weight. 6. A step of providing a photosensitive layer made of a chemically amplified resist containing an acid generator on a substrate, forming a resist pattern by performing a selective exposure and a developing process, and forming a resist pattern on the resist pattern. 5, a step of forming a coating film made of the fine pattern forming material according to any one of the above, a step of forming a water-insoluble reaction layer at an interface between the resist pattern and the coating film made of the fine pattern forming material by heat treatment, and A method for forming a fine pattern, comprising sequentially performing a step of removing an unreacted portion of a coating film made of a fine pattern forming material with an aqueous solvent.