JP4535374B2 - COATING FORMING AGENT FOR PATTERN REFINEMENT AND METHOD FOR FORMING FINE PATTERN USING THE - Google Patents

Description

    The present invention relates to a coating forming agent for pattern miniaturization in the field of photolithography and a method for forming a fine pattern using the same. More specifically, the present invention relates to a coating forming agent for pattern miniaturization that can cope with recent integration and miniaturization of semiconductor devices, and a method for forming a micropattern using the same.

  In the manufacture of electronic components such as semiconductor devices and liquid crystal devices, a coating (photoresist layer) is provided on the substrate using a so-called radiation-sensitive photoresist that is sensitive to actinic radiation when the substrate is subjected to processing such as etching. Selectively irradiate with actinic radiation to expose, develop, and selectively dissolve and remove the photoresist layer to form an image pattern (photoresist pattern) on the substrate, which is used as a protective layer (mask pattern) Photolithographic techniques for forming various patterns such as a contact pattern such as a hole pattern and a trench pattern on a substrate are used.

In recent years, the trend toward integration and miniaturization of semiconductor devices has increased, and the miniaturization of these patterns has progressed. Currently, ultra-fine processing with a pattern width of 0.20 μm or less is required, and the activity used for mask pattern formation For light, KrF, ArF, F ₂ excimer laser light and short-wavelength irradiation light such as electron beams are used. Photoresist materials as mask pattern forming materials also have physical properties corresponding to these irradiation light.・ Development is in progress.

  In addition to measures for ultra-miniaturization from the viewpoint of photoresist materials, research and development of pattern miniaturization techniques that exceed the resolution limit of photoresist materials are also being conducted from the aspect of pattern formation methods.

  For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 5-166717), after a pattern is formed on a pattern forming resist applied on a substrate, a mixing generation resist that is mixed with the pattern forming resist is applied to the entire surface of the substrate. Then, baking is performed to form a mixing layer on the side wall to the surface of the pattern forming resist, and a non-mixing portion of the resist for generating the mixing is removed to reduce the size of the mixing layer. Is disclosed. Further, in Patent Document 2 (Japanese Patent Laid-Open No. 5-241348), a resin that is insolubilized in the presence of an acid is deposited on a substrate on which a resist pattern containing an acid generator is formed, and then heat-treated. After the acid is diffused from the resist to form a resist having a constant thickness near the resin / resist pattern interface, development is performed to remove the resin portion where the acid is not diffused, thereby obtaining the above-mentioned constant thickness dimension. A pattern forming method for miniaturization of the pattern is disclosed.

  However, in these methods, it is difficult to control the thickness of the layer formed on the side wall of the resist pattern, and the thermal dependence in the wafer surface is as large as about 10 nm / ° C., and the heating apparatus used in the manufacture of current semiconductor devices. However, it is very difficult to keep the wafer surface uniform, and there is a problem that variations in pattern dimensions are noticeable.

  On the other hand, a method is also known in which a resist pattern is fluidized by heat treatment or the like to reduce a pattern dimension. For example, Patent Document 3 (Japanese Patent Laid-Open No. 1-307228) discloses a method of forming a fine pattern by forming a resist pattern on a substrate and then performing heat treatment to deform the cross-sectional shape of the resist pattern. Has been. In Patent Document 4 (Japanese Patent Laid-Open No. 4-340221), a resist pattern is formed and then heated before and after its softening temperature, and the pattern dimensions are changed by fluidizing the resist to form a fine pattern. Is disclosed.

  In these methods, the thermal dependence within the wafer surface is about several nm / ° C, and although there are few problems in this respect, it is difficult to control the deformation and flow of the resist by heat treatment. There is a problem that it is difficult to provide a simple resist pattern.

  As a further developed method, for example, in Patent Document 5 (Japanese Patent Laid-Open No. 7-45510), after a resist pattern is formed on a substrate, the resist pattern is prevented from flowing too much on the substrate. A method is disclosed in which a resin as a stopper is formed, then heat-treated, the resist is fluidized to change the pattern dimensions, and then the resin is removed to form a fine pattern. And as the resin, a water-soluble resin, specifically polyvinyl alcohol, is used alone, but polyvinyl alcohol alone has insufficient solubility in water, so it is difficult to remove completely by washing and is good. In addition to being difficult to form a good profile pattern and not always satisfactory in terms of stability over time, there are problems such as poor coatability, and it has not been put into practical use.

  As a technique for solving these conventional problems, the present applicant has disclosed Patent Documents 6 to 11 (JP 2003-084459 A, JP 2003-084460 A, JP 2003-107752 A, JP 2003-142381 A). JP, JP-A 2003-195527, JP-A 2003-202679) and the like propose a technique relating to a pattern forming coating forming agent and a method for forming a fine pattern. With the techniques shown in Patent Documents 6 to 11 and the like, it is possible to obtain a fine pattern having controllability of pattern dimensions, a good profile, and required characteristics in a semiconductor device.

  In the fine pattern formation technique using this pattern refinement coating forming agent, a photoresist layer is first provided on a substrate, and this is exposed and developed to form a photoresist pattern. Next, after coating the pattern forming coating forming agent over the entire surface of the substrate, heating is performed to make the photoresist pattern wide by utilizing the heat shrinking action of the pattern miniaturizing coating forming agent. The width of the pattern (various patterns such as a hole pattern and a trench pattern) defined by the photoresist pattern interval is narrowed, and a finer pattern can be obtained.

  That is, the pattern miniaturization is affected by pattern dimension control in two stages, a photoresist pattern formation stage (first stage) and a thermal contraction stage (second stage) of the pattern miniaturization coating forming agent. In forming a photoresist pattern using such a technique, it is necessary to shrink the pattern shape formed in the first stage with a uniform thermal shrinkage rate while maintaining the pattern shape in the second stage heat shrinking process. It is. In particular, when forming a non-circular hole pattern such as an elliptical shape, it is heat-shrinked while maintaining the ratio of the minor axis diameter to the major axis diameter of the ellipse while maintaining a high thermal shrinkage rate. It is necessary to obtain an elliptical hole pattern. The present invention is for solving this problem.

  In Patent Document 12 (Japanese Patent Laid-Open No. 2001-281886), an acid film made of a resist pattern reducing material containing a water-soluble resin is coated on the resist pattern surface, and then the resist pattern surface layer is converted to alkali-soluble. Then, a method of reducing the resist pattern by removing the surface layer and the acidic film with an alkaline solution is disclosed, and Patent Document 13 (Japanese Patent Application Laid-Open No. 2002-184673) discloses a resist pattern on a substrate. After forming a coating film containing a water-soluble film-forming component on the resist pattern, heat-treating the resist pattern and the coating film, and then submerging in an aqueous solution of tetramethylammonium hydroxide to refine the film without going through a dry etching process Although methods for forming a resist pattern have been disclosed, all of them are resist patterns. A method of refining the emissions themselves, the present invention and its purpose is completely different.

JP-A-5-166717 JP-A-5-241348 JP-A-1-307228 Japanese Patent Laid-Open No. 4-364221 Japanese Unexamined Patent Publication No. 7-45510 JP 2003-084459 A JP 2003-084460 A JP 2003-107752 A JP 2003-142381 A JP 2003-195527 A JP 2003-202679 A JP 2001-281886 A JP 2002-184673 A

  The present invention has been made in view of the above circumstances, and intends to form a pattern that is contracted at a uniform heat shrinkage rate while maintaining the pattern shape, and particularly in the formation of an elliptical hole pattern, it has a high heat shrinkage rate. While maintaining the ratio of the ellipse minor axis diameter to the major axis diameter, heat shrinking in a state where the ratio of the minor axis diameter to the major axis diameter was maintained, and a refined coating forming agent capable of obtaining a refined elliptical hole pattern and the same were used An object of the present invention is to provide a fine pattern forming method.

In order to solve the above-mentioned problems, the present invention is applied to a substrate having a photoresist pattern. After the photoresist pattern interval is narrowed by utilizing the thermal shrinkage action of the coating, the coating is removed substantially completely. A coating forming agent for forming a fine pattern, comprising: (a) a water-soluble polymer; and (b) a monomer of an imidazole compound. Provide the agent.

  In the present invention, the component (a) is an alkylene glycol polymer, a cellulose derivative, a vinyl polymer, an acrylic polymer, a urea polymer, an epoxy polymer, a melamine polymer, and an amide polymer. The above-mentioned coating forming agent for pattern miniaturization, which is at least one selected from coalescence, is provided.

  In addition, the present invention provides the above-described pattern refining coating-forming agent, wherein the component (a) is at least one selected from alkylene glycol polymers, cellulose derivatives, vinyl polymers, and acrylic polymers. To do.

  Moreover, this invention provides the said coating formation agent for pattern refinement | miniaturization whose coating formation agent for pattern refinement | purification is 3-50 mass% solid content aqueous solution.

  Moreover, this invention provides the said coating formation agent for pattern refinement | miniaturization containing 1-15 mass% of (b) component with respect to 100 mass% of (a) component.

  In the present invention, the substrate having a photoresist pattern is coated with the coating forming agent for pattern miniaturization, and then the coating forming agent is thermally contracted by heat treatment, and the spacing between the photoresist patterns is utilized by utilizing the thermal contraction action. A method for forming a fine pattern is provided, which includes the step of narrowing the width and then substantially completely removing the coating forming agent for pattern miniaturization.

  The present invention also provides a method for forming the fine pattern, wherein the heat treatment is performed by heating at a temperature that does not cause thermal flow in the photoresist pattern on the substrate.

  In a technique using a fine pattern forming method in which a coating forming agent (coating film) is provided on a substrate having a photoresist pattern, the photoresist pattern interval is narrowed using the shrinkage force of the coating film, and then the coating film is removed. Especially, in the formation of an elliptical hole pattern, while maintaining a high heat shrinkage rate, heat shrinkage is performed while maintaining the ratio of the minor axis diameter to the major axis diameter of the ellipse to obtain a refined elliptical hole pattern And a fine pattern forming method using the same.

  The pattern refinement coating forming agent of the present invention is coated on a substrate provided with a photoresist pattern, and widens the photoresist pattern by the heat shrinking action of the coating, thereby forming a hole pattern, a trench defined by a photoresist pattern interval. After the width of the pattern such as a pattern is narrowed, the coating is substantially completely removed to form a fine pattern.

  Here, “substantially completely removing the coating” means that the space between the photoresist patterns is narrowed using the heat shrinking action of the coating forming agent for pattern miniaturization, and then the interface with the photoresist pattern This means that all of the pattern refinement coating forming agent is removed without leaving a significant thickness. Therefore, the present invention does not include a method of making the pattern finer coating forming agent remain in the vicinity of the photoresist pattern interface at a certain thickness and miniaturizing the pattern by the remaining predetermined thickness.

  The coating refinement agent for pattern refinement of the present invention contains (a) a water-soluble polymer and (b) a heterocyclic compound having at least two nitrogen atoms in at least the same ring.

  The water-soluble polymer as the component (a) is not particularly limited as long as it is a polymer that can be dissolved in water at room temperature, but is not limited to an acrylic polymer, a vinyl polymer, a cellulose derivative, an alkylene glycol type. A polymer, a urea polymer, a melamine polymer, an epoxy polymer, an amide polymer and the like are preferably used.

  Examples of the acrylic polymer include acrylic acid, methyl acrylate, methacrylic acid, methyl methacrylate, N, N-dimethylacrylamide, N, N-dimethylaminopropyl methacrylamide, N, N-dimethylaminopropylacrylamide, N -A polymer or copolymer comprising monomers such as methyl acrylamide, diacetone acrylamide, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate, acryloylmorpholine A polymer is mentioned.

  Examples of the vinyl polymer include a polymer or a copolymer having a constituent component such as N-vinylpyrrolidone, vinylimidazolidinone, vinyl acetate, or the like.

  Examples of cellulose derivatives include hydroxypropylmethylcellulose phthalate, hydroxypropylmethylcellulose acetate phthalate, hydroxypropylmethylcellulose hexahydrophthalate, hydroxypropylmethylcellulose acetate succinate, hydroxypropylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, cellulose acetate hexahydro. Examples include phthalate, carboxymethylcellulose, ethylcellulose, methylcellulose and the like.

  Examples of the alkylene glycol polymer include addition polymers or addition copolymers such as ethylene glycol and propylene glycol.

  Examples of the urea polymer include those having methylol urea, dimethylol urea, ethylene urea or the like as a constituent component.

  Examples of the melamine polymer include those containing methoxymethylated melamine, methoxymethylated isobutoxymethylated melamine, methoxyethylated melamine and the like as constituent components.

  Further, water-soluble ones such as epoxy polymers and amide polymers can be used.

  Among them, it is preferable to include at least one selected from an alkylene glycol polymer, a cellulose polymer, a vinyl polymer, and an acrylic polymer, and in particular, pH adjustment is easy. The acrylic polymer is most preferable. Furthermore, making a copolymer of an acrylic polymer and a water-soluble polymer other than an acrylic polymer increases the shrinkage efficiency of the photoresist pattern spacing while maintaining the shape of the photoresist pattern during heat treatment. It is preferable from the point that can be performed. (A) A component can use 1 type (s) or 2 or more types.

  When the component (a) is used as a copolymer, the blending ratio of the constituent components is not particularly limited. However, when emphasis is placed on the stability over time, the blending ratio of the acrylic polymer is set to other values. The amount is preferably larger than that of the constituent polymer. The improvement in stability over time can be solved by adding an acidic compound such as p-toluenesulfonic acid and dodecylbenzenesulfonic acid in addition to excessively adding the acrylic polymer as described above. is there.

  In the present invention, as the component (b), a monomer of a heterocyclic compound having at least two nitrogen atoms in at least the same ring is used.

  As component (b), pyrazole, 3,5-dimethylpyrazole, 2-pyrazoline, 5-pyrazolone, 3-methyl-1-phenyl-5-pyrazolone, 2,3-dimethyl-1-phenyl-5-pyrazolone, Pyrazole compounds such as 2,3-dimethyl-4-dimethylamino-1-phenyl-5-pyrazolone and benzopyrazole; imidazole, methylimidazole, 2,4,5-triphenylimidazole, 4- (2-aminoethyl) Imidazole compounds such as imidazole and 2-amino-3- (4-imidazolyl) propionic acid; 2-imidazoline, 2,4,5-triphenyl-2-imidazoline, 2- (1-naphthylmethyl) -2-imidazoline Imidazoline compounds such as: imidazolidine, 2-imidazolidone, 2,4-imidazolidine di 1-methyl-2,4-imidazolidinedione, 5-methyl-2,4-imidazolidinedione, 5-hydroxy-2,4-imidazolidinedione-5-carboxylic acid, 5-ureido-2,4 -Imidazolidine compounds such as imidazolidinedione, 2-imino-1-methyl-4-imidazolidone, 2-thioxo-4-imidazolidone; benzimidazoles such as benzimidazole, 2-phenylbenzimidazole, 2-benzimidazolinone Compound; Diazine-based compound such as 1,2-diazine, 1,3-diazine, 1,4-diazine, 2,5-dimethylpyrazine; 2,4 (1H, 3H) pyrimidinedione, 5-methyluracil, 5- Ethyl-5-phenyl-4,6-perhydropyrimidinedione, 2-thioxo-4 (1H, 3H) -pyrim Hydropyrimidine compounds such as non, 4-imino-2 (1H, 3H) -pyrimidine, 2,4,6 (1H, 3H, 5H) -pyrimidinetrione; benzodiazines such as cinnoline, phthalazine, quinazoline, quinoxaline and luminol Compound: Dibenzodiazine compounds such as benzocinoline, phenazine, 5,10-dihydrophenazine; 1H-1,2,3-triazole, 1H-1,2,4-triazole, 4-amino-1,2,4- Triazole compounds such as triazole; benzotriazole compounds such as benzotriazole and 5-methylbenzotriazole; 1,3,5-triazine, 1,3,5-triazine-2,4,6-triol, 2,4 6-trimethoxy-1,3,5-triazine, 1,3,5-triazine-2,4,6- Examples include trithiol, 1,3,5-triazine-2,4,6-triamine, triazine compounds such as 4,6-diamino-1,3,5-triazin-2-ol, and the like. It is not limited.

  Among these, from the viewpoints of easy handling and availability, imidazole compound monomers are preferably used, and imidazole is particularly preferably used.

  The blending amount of the component (b) is preferably about 1 to 15% by mass, more preferably about 2 to 10% by mass with respect to the component (a) of the present invention. If it is less than 1% by mass, it is difficult to obtain a desired effect in the present invention. On the other hand, if it exceeds 15% by mass, it is difficult to obtain the desired effect in the present invention, and at the same time, the risk of occurrence of foreign matter (defect) increases.

  The coating refining agent for pattern refinement of the present invention is preferably used as an aqueous solution having a solid concentration of 3 to 50% by mass, and particularly preferably 5 to 20% by mass. If the concentration is less than 3% by mass, the substrate may be poorly coated. On the other hand, if it exceeds 50% by mass, an improvement in the effect commensurate with the increased concentration is not recognized, which is not preferable from the viewpoint of handling.

  In addition, although the coating formation agent for pattern refinement | miniaturization of this invention is normally used as aqueous solution using water as a solvent as mentioned above, the mixed solvent of water and an alcohol solvent can also be used. Examples of alcohol solvents include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 2,3-butylene glycol. It is done. These alcohol solvents are used by mixing with water at an upper limit of about 30% by mass.

  In addition to the component (a) and the component (b), a water-soluble amine, a surfactant, and the like may be blended in the coating forming agent for pattern miniaturization of the present invention as desired.

  Examples of the water-soluble amine include amines having a pKa (acid dissociation constant) of 7.5 to 13 in an aqueous solution at 25 ° C. Specifically, for example, monoethanolamine, diethanolamine, triethanolamine, 2- (2-aminoethoxy) ethanol, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamine , Alkanolamines such as N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-methyldiethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine; diethylenetriamine, triethylenetetramine, propylenediamine, N, N-diethylethylenediamine, 1,4-butanediamine, N-ethyl-ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,6-hexane Polyalkylene polyamines such as amines; aliphatic amines such as 2-ethyl-hexylamine, dioctylamine, tributylamine, tripropylamine, triallylamine, heptylamine, cyclohexylamine; aromatic amines such as benzylamine and diphenylamine Is mentioned. Among them, those having a boiling point of 140 ° C. or higher (760 mmHg) are preferable, and for example, monoethanolamine, triethanolamine and the like are preferably used. The addition of a water-soluble amine is effective in terms of preventing the generation of impurities and adjusting pH.

  When the water-soluble amine is blended, it is preferably blended at a ratio of about 0.1 to 30% by mass, particularly about 2 to 15% by mass with respect to the coating refining agent for pattern refinement (solid content). If it is less than 0.1% by mass, the liquid may be deteriorated with time. On the other hand, if it exceeds 30% by mass, the shape of the photoresist pattern may be deteriorated.

  Although it does not specifically limit as surfactant, The characteristic of being highly soluble with respect to (a) component contained in this invention, and not generating suspension is required. By using a surfactant that satisfies these characteristics, it is possible to suppress the generation of bubbles (microfoam), particularly when coating materials are applied, and the occurrence of defects that are related to the occurrence of microfoam. Prevention can be achieved.

  From the above points, at least one selected from N-alkylpyrrolidone surfactants, quaternary ammonium salt surfactants, and polyoxyethylene phosphate ester surfactants is preferably used.

  As the N-alkylpyrrolidone surfactant, the following general formula (I)

(Wherein R ₁ represents an alkyl group having 6 or more carbon atoms)
The thing represented by these is preferable.

  Specific examples of such N-alkylpyrrolidone surfactants include N-hexyl-2-pyrrolidone, N-heptyl-2-pyrrolidone, N-octyl-2-pyrrolidone, N-nonyl-2-pyrrolidone, N -Decyl-2-pyrrolidone, N-decyl-2-pyrrolidone, N-undecyl-2-pyrrolidone, N-dodecyl-2-pyrrolidone, N-tridecyl-2-pyrrolidone, N-tetradecyl-2-pyrrolidone, N-pentadecyl -2-pyrrolidone, N-hexadecyl-2-pyrrolidone, N-heptadecyl-2-pyrrolidone, N-octadecyl-2-pyrrolidone and the like. Among them, N-octyl-2-pyrrolidone (“SURFADONE LP100”; manufactured by ISP) is preferably used.

  As the quaternary ammonium salt surfactant, the following general formula (II)

[Wherein R ₂ , R ₃ , R ₄ and R ₅ each independently represents an alkyl group or a hydroxyalkyl group (however, at least one of them represents an alkyl group or a hydroxyalkyl group having 6 or more carbon atoms) X ⁻ represents a hydroxide ion or a halogen ion]
The thing represented by these is preferable.

  Specific examples of the quaternary ammonium salt surfactant include dodecyltrimethylammonium hydroxide, tridecyltrimethylammonium hydroxide, tetradecyltrimethylammonium hydroxide, pentadecyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide. , Heptadecyltrimethylammonium hydroxide, octadecyltrimethylammonium hydroxide, and the like. Of these, hexadecyltrimethylammonium hydroxide is preferably used.

  Polyoxyethylene phosphate ester surfactants include the following general formula (III)

Wherein R ₆ represents an alkyl group having 1 to 10 carbon atoms or an alkylallyl group; R ₇ represents a hydrogen atom or (CH ₂ CH ₂ O) R ₆ (where R ₆ is as defined above) N represents an integer of 1 to 20)
Is preferred.

  Specifically, such polyoxyethylene phosphate ester surfactants are commercially available as "Plisurf A212E", "Plysurf A210G" (all of which are manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). A thing can be used suitably.

  When the surfactant is blended, the blending amount is preferably about 0.1 to 10% by weight, particularly 0.2 to 2% by weight, based on the pattern forming coating forming agent (solid content). Degree. By blending a surfactant, it is possible to improve coating properties, in-plane uniformity, prevention of variation in pattern shrinkage, prevention of microfoam, prevention of defects, and the like.

  In the fine pattern forming method according to the present invention, a substrate having a photoresist pattern is coated with the above-described pattern refinement coating forming agent, and then the pattern refinement coating forming agent is thermally contracted by heat treatment. The process includes the step of narrowing the interval between the photoresist patterns by the action, and then substantially completely removing the pattern forming coating forming agent.

  The production of a substrate having a photoresist pattern is not particularly limited, and can be performed by a conventional method used in the production of semiconductor devices, liquid crystal display elements, magnetic heads, microlenses and the like. For example, a chemically amplified photoresist composition is applied onto a substrate such as a silicon wafer using a spinner and dried to form a photoresist layer, which is then subjected to ultraviolet, deep-UV, excimer laser using a reduction projection exposure apparatus. Actinic rays such as light are irradiated through a desired mask pattern or drawn with an electron beam, and then heated, and then heated with a developer, for example, a 1 to 10% by mass tetramethylammonium hydroxide (TMAH) aqueous solution. A photoresist pattern can be formed on the substrate by development using an alkaline aqueous solution such as the above.

As the material to become photoresist composition of the photoresist pattern, is not particularly limited, i-line, g-line photoresist composition, KrF, ArF, excimer laser photoresist composition, such as F _2, further EB A widely used photoresist composition such as a photoresist composition for EUV (electron beam) can be used.

  Among these, in particular, when a photoresist pattern is formed, a photoresist composition that does not form a mixing layer in the vicinity of the interface between the photoresist pattern and the coating forming agent for pattern miniaturization of the present invention is preferable. When the mixing layer is formed, defects are likely to occur as described in the above-mentioned section of the prior art, and further, the thermal dependency in the substrate plane becomes more than 10 nm, which is not preferable.

  In general, when using a photoresist composition for i-line or g-line (for example, a positive-type photoresist composition containing a novolak resin and a naphthoquinonediazide-based photosensitizer), the above problem may not occur. Although it is not necessary to consider, when using a chemically amplified photoresist composition containing a compound (acid generator) that generates an acid upon exposure, such as a photoresist composition for excimer laser, a photoresist composition for electron beam, Since a mixing layer may be formed near the interface between the coating forming agent and the photoresist pattern due to the acid generated from the acid generator, this point needs to be considered. The formation of the mixing layer depends on the diffusion length (diffusion distance) of the acid generated from the acid generator, the amount of basic substance added, and the like. Therefore, when using a photoresist composition for excimer laser, a photoresist composition for electron beam, etc., it is desirable to select and use a photoresist composition that does not generate the mixing layer.

a. Pattern Refinement Coating Forming Agent Application Step Next, the pattern refinement coating forming agent is applied and coated over the entire surface of the substrate having the photoresist pattern as the mask pattern. In addition, after apply | coating the coating formation agent for pattern refinement | miniaturization, you may pre-bake a board | substrate for about 30 to 90 second at the temperature of about 80-100 degreeC.

  The coating method can be performed in accordance with a method usually performed in a conventional heat flow process. That is, for example, the aqueous solution of the pattern refinement coating forming agent is applied onto the substrate by a spinner or the like.

b. Heat Treatment (Heat Shrinkage) Step Next, a heat treatment is performed to shrink the coating film made of the pattern refinement coating forming agent. Under the influence of the heat shrinkage force of the coating film, the dimension of the photoresist pattern in contact with the coating film is increased by an amount corresponding to the thermal shrinkage of the coating film, the photoresist pattern becomes wide and wide, and the interval between the photoresist patterns is narrowed. . Since the distance between the photoresist patterns defines the diameter and width of the finally obtained pattern, the diameter of the hole pattern and the width of the trench pattern can be narrowed and narrowed. Can be miniaturized.

  The heating temperature is not particularly limited as long as it is a temperature that can cause thermal shrinkage of a coating film made of a coating forming agent for pattern miniaturization, and is a temperature sufficient to perform pattern miniaturization. It is preferable to heat at a temperature that does not cause heat flow. The temperature at which heat flow does not occur in the photoresist pattern means that when a coating film made of a pattern refinement coating agent is not formed and a substrate on which only the photoresist pattern is formed is heated, a dimensional change occurs in the photoresist pattern. This is the temperature that is not allowed. The heat treatment at such a temperature makes it possible to more effectively form a fine pattern with a good profile, and particularly depend on the duty ratio in the wafer surface, that is, the pattern interval in the wafer surface. This is extremely effective in that the property can be reduced. Considering the softening point of various photoresist compositions used in the current photolithography technology, a preferable heat treatment is usually in the temperature range of about 80 to 160 ° C., but at a temperature at which the photoresist does not cause thermal flow, 30 to It takes about 90 seconds.

  The thickness of the coating film made of the pattern refinement coating forming agent is preferably about the same as or covering the height of the photoresist pattern.

c. Pattern Refinement Coating Forming Agent Removal Step Thereafter, the coating film made of the pattern refinement coating forming agent remaining on the pattern is removed by washing with an aqueous solvent, preferably pure water, for 10 to 60 seconds. Prior to the water removal, if necessary, the removal treatment may be performed with an alkaline aqueous solution (for example, tetramethylammonium hydroxide (TMAH), choline, etc.). The pattern refinement coating forming agent according to the present invention can be easily removed by washing with water and can be completely removed from the substrate and the photoresist pattern.

  Then, a substrate having a miniaturized pattern defined between the wide and wide photoresist patterns is obtained on the substrate.

  The fine pattern obtained by the present invention has a finer pattern size than the resolution limit of the photoresist material, a good profile, and physical properties that can sufficiently satisfy the required required characteristics. is there.

  The a. ~ C. The process may be repeated a plurality of times. Thus, a. ~ C. By repeating the process a plurality of times, the photoresist pattern (mask pattern) can be gradually widened and widened.

  The technical field to which the present invention is applied is not limited to the semiconductor field, and can be widely used for manufacturing liquid crystal display elements, magnetic heads, and microlenses.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. The blending amount is mass% unless otherwise specified.

[Example]
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. The blending amount is mass% unless otherwise specified.

  3 g of copolymer of acrylic acid and vinylpyrrolidone (polymerization ratio = 2: 1), 0.12 g of imidazole, and polyoxyethylene phosphate ester surfactant (“Plysurf A210G”; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.03 g was dissolved in 40 g of water to prepare a coating forming agent for pattern refinement.

  On the other hand, a positive photoresist “TArF-7a-70 EM” (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is spin-coated on the substrate and baked at 95 ° C. for 90 seconds to form a 0.25 μm-thick photoresist layer. Formed.

  The photoresist layer was exposed using an exposure apparatus (“NSR-S306”; manufactured by Nikon Corporation), and subjected to a heat treatment at 85 ° C. for 90 seconds to obtain 2.38 mass% TMAH (tetramethylammonium). A photoresist pattern was formed by development using a hydroxide aqueous solution. By forming this photoresist pattern, an elliptical hole pattern (major axis diameter: minor axis diameter = 1.85: 1) having a major axis diameter of 188 nm and a minor axis diameter of 102 nm was formed.

Next, on the substrate having this hole pattern, the above-mentioned coating forming agent for pattern miniaturization was applied, and heat treatment was performed at 145 ° C. for 60 seconds to perform the hole pattern miniaturization process. Subsequently, the coating forming agent for pattern miniaturization was removed using pure water at 23 ° C. The hole pattern at that time is an elliptical hole pattern (major axis diameter: minor axis diameter = 1.85: 1) having a major axis diameter of 159 nm and a minor axis diameter of 86 nm, and is refined while maintaining the initial ellipse shape. The process could be done. Also, the pattern shape was good with a rectangular cross section.
[Comparative Example 1]

  3 g of copolymer of acrylic acid and vinyl pyrrolidone (polymerization ratio = 2: 1), 0.18 g of triethylamine, and polyoxyethylene phosphate ester surfactant (“Plysurf A210G”; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) A coating forming agent was prepared by dissolving 0.03 g in 40 g of water.

  Next, the coating forming agent was applied onto an elliptical hole pattern (major axis diameter 188 nm, minor axis diameter 102 nm, major axis diameter: minor axis diameter = 1.85: 1) formed in the same manner as in Example 1. The hole pattern was refined by heat treatment at 155 ° C. for 60 seconds. Subsequently, the coating forming agent was removed using pure water at 23 ° C. The hole pattern at that time was satisfactory in terms of the pattern cross-sectional shape, but the formed elliptical shape was an elliptical hole pattern having a major axis diameter of 147 nm and a minor axis diameter of 86 nm (major axis diameter: minor axis diameter). = 1.71: 1), and the initial elliptical shape could not be maintained.

Claims (7)

It is coated on a substrate having a photoresist pattern, and is used to form a fine pattern by removing the coating substantially completely after narrowing the interval of the photoresist pattern by utilizing the heat shrinkage action of the coating. A coating forming agent for pattern miniaturization, comprising: (a) a water-soluble polymer; and (b) a monomer of an imidazole compound .   The component (a) is selected from alkylene glycol polymers, cellulose derivatives, vinyl polymers, acrylic polymers, urea polymers, epoxy polymers, melamine polymers, and amide polymers. The coating formation agent for pattern refinement | miniaturization of Claim 1 which is at least 1 sort (s) selected.   The coating forming agent for pattern miniaturization according to claim 2, wherein the component (a) is at least one selected from an alkylene glycol polymer, a cellulose derivative, a vinyl polymer, and an acrylic polymer. The coating forming agent for pattern miniaturization according to any one of claims 1 to 3 , wherein the coating forming agent for pattern miniaturization is an aqueous solution having a solid content concentration of 3 to 50% by mass. The coating formation agent for pattern refinement | miniaturization of any one of Claims 1-4 which contains 1-15 mass% of (b) component with respect to 100 mass% of (a) component. On a substrate having a photoresist pattern, after coating the fine patterns for coating formation agent according to any one of claims 1 to 5 the coating formation agent and heat-shrunk by heat treatment, by utilizing the heat shrinkage action A method for forming a fine pattern, comprising a step of narrowing a space between photoresist patterns and then substantially completely removing the coating forming agent for pattern miniaturization. 7. The method for forming a fine pattern according to claim 6 , wherein the heat treatment is performed by heating at a temperature that does not cause heat flow in the photoresist pattern on the substrate.