JP5879101B2 - Photoresist composition - Google Patents

Description

  The present invention relates to a photoresist composition, and more specifically, after vacuum drying with a co-solvent, it is excellent in coating uniformity and pattern profile, excellent in stain suppression ability after coating, and easily applied to actual industrial sites. In addition, the present invention relates to a photoresist composition capable of satisfactorily changing the working environment by effects such as reduction in use amount and reduction in mass production time in mass production.

  In order to form a fine circuit pattern such as a liquid crystal display device circuit or a semiconductor integrated circuit, first, a photoresist composition is uniformly coated or applied to an insulating film or a conductive metal film formed on a substrate, and a predetermined pattern is formed. The coated photoresist composition is exposed and developed in the presence of a shape mask to form a pattern of the desired shape. Thereafter, the photoresist film with the pattern formed thereon is used as a mask to etch the metal film or the insulating film, and then the remaining photoresist film is removed to form a fine circuit on the substrate.

  For the coating or coating, a spin coating method or a slit coating method is generally used. These coating methods have the advantage that a uniform photoresist film can be formed, and the coating uniformity indicates how uniform the thickness of the applied photoresist is covered on the entire substrate. The higher the coating uniformity is, the safer the physical properties can be secured in the subsequent processes. Therefore, many solvents were applied to form a more uniform and stain-free photoresist film.

  In general, a photoresist composition includes a polymer resin, a photosensitive compound, and a solvent, and the coating uniformity, the photosensitive speed, the development contrast, the resolution, and the photoresist film formed using the photoresist composition so far. There have been many attempts to improve human safety.

  Specifically, U.S. Pat. No. 3,666,473 discloses the use of a mixture of two phenol formaldehyde novolac resins and a typical photosensitive compound, and U.S. Pat. No. 4,115,128. Discloses the addition of an organic acid cyclic anhydride to a phenolic resin and a naphthoquinone diazide photosensitizer to increase the photosensitivity. US Pat. No. 4,550,069 discloses coating uniformity and photosensitivity. The use of propylene glycol alkyl ether acetate as a novolak resin, o-quinonediazide photosensitive compound and solvent is disclosed in order to increase the safety and improve human safety.

  In addition, in order to improve physical properties and work stability of a photoresist composition for liquid crystal display devices, various solvents in a spin coating method have been developed. Examples thereof include ethylene glycol monoethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate and the like. However, in the case of ethylene glycol monoethyl ether acetate, serious side effects on human safety have been reported. When propylene glycol monoethyl ether acetate is used, a pin is used after a baking process on a large substrate such as a TFT-LCD. There is a problem that the flattening characteristics are deteriorated when used as a single solvent and a defect due to the mark, and when ethyl lactate is used, the adhesive strength of the composition to the substrate is bad and uniform coating is difficult There is.

  In addition, in the case of the slit coating method, the centrifugal force due to the existing spin coating method does not act, so the use of a solvent having uniform coating characteristics and excellent flatness and uniform pattern performance during vacuum drying after coating is required. Yes.

  In particular, since the surface of the film is more likely to be dried than the inside during vacuum drying, the pattern shape often has a reverse taper shape, which increases the possibility of causing a defect in a subsequent process.

  Therefore, such as coating uniformity, coating stain characteristics, pattern shape, photosensitive speed, residual film ratio, development contrast, resolution, polymer resin solubility, adhesion to the substrate, circuit line width uniformity, etc. There is a continuing need for photoresist compositions suitable for each industrial process without sacrificing any one of the desirable properties of the resist composition.

  The object of the present invention is not only to significantly improve the pattern shape, including a co-solvent with a specific structure so as to reduce the stain at the time of coating, improve the coating uniformity, and avoid reverse taper shape during vacuum drying. A photoresist composition that does not cause the non-uniformity of width will be provided.

The present invention
(A) 5-30% by weight of novolac resin,
(B) 2 to 10% by weight of a diazide photosensitive compound,
(C) A photoresist composition comprising 1 to 70% by weight of a compound represented by the following chemical formula (1) and (d) a remaining amount of an organic solvent is provided.
In the above formula, R ₁ is hydrogen or an alkyl group having 1 to 10 linear or side chain carbon atoms, and R ₂ has 1 to 10 linear or side chain carbon atoms. An alkyl group or an allyl group;

  The present invention also provides a pattern forming method including a step of coating a substrate with the photoresist composition, then heat-treating to form a photoresist film having a predetermined thickness, and exposing and developing to form a pattern. provide.

  The photoresist composition of the present invention has a preferable pattern shape that reduces coating stain at the time of coating, improves coating uniformity, and does not become reversely tapered when vacuum dried. In particular, in the case of the present invention, there is no problem that the width of the pattern becomes non-uniform as in the conventional methods such as the ratio depending on the amount and type of the photosensitizer and the reduction of the contrast enhancer for improving the pattern shape. .

The characteristic evaluation criteria of the coating stain with respect to a photoresist film film are shown. The evaluation criteria with respect to the photoresist pattern shape are shown.

  Hereinafter, the present invention will be described in more detail. The present invention satisfies all of the physical properties required for a photoresist composition such as photosensitive speed, residual film ratio, development contrast, resolution, polymer resin solubility, adhesion to a substrate, and circuit line width uniformity. In particular, the present invention relates to a photoresist composition that has excellent coating uniformity, prevents coating stains, and has an excellent pattern shape.

Such a photoresist composition of the present invention contains a novolak resin, a diazide-based photosensitive compound and an organic solvent, and contains a co-solvent represented by the above chemical formula (1) for improving the coating property. Features.
In the above formula, R1 is hydrogen or an alkyl group having 1 to 10 linear or side chain carbon atoms, and R2 is an alkyl group having 1 to 10 linear or side chain carbon atoms or An allyl group.

  The co-solvent represented by the chemical formula (1) includes dimethyl-2-methyl glutarate, dimethyl adipate, dimethyl glutarate, and dimethyl succinate. succinate, diisobutyl adipate, diisobutyl glutarate, diisobutyl succinate, or a mixture of one or more of them, and dimethyl having good coating uniformity and stain characteristics More preferably, 2-methylglutarate is used.

  In the photoresist composition of the present invention, the content of the co-solvent of the above chemical formula (1) may be appropriately added in consideration of coating uniformity, for example, 1 to 70 wt% with respect to the entire photoresist composition. %, More preferably 5 to 50% by weight. At this time, if the content is less than 1% by weight, there is a problem that stain at the time of vacuum drying occurs or a reverse taper pattern is formed, and if it exceeds 70% by weight, the remaining film ratio is lowered. There is a problem that the vacuum drying time becomes long.

  Further, the novolak resin is alkali-soluble, and ordinary ones used in conventional photoresist compositions can be used. Specifically, the novolak resin can be obtained by subjecting a phenol compound and an aldehyde compound or a ketone compound to a condensation polymerization reaction in the presence of an acid catalyst. For example, the novolak resin includes a novolak resin synthesized with metacresol alone, a novolak resin synthesized with paracresol alone, a novolak resin using resorcinol, a novolak resin produced by reacting salicylaldehyde with benzylaldehyde, Any novolak resin using a mixture of cresol, para-cresol, resorcinol, etc. can be used.

  Examples of the phenol compound include phenol, orthocresol, metacresol, paracresol, 2,3-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6- Dimethylphenol, 2,3,6-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol, 4-t-butylphenol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, 4-t-butyl Catechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylpheno Le, thymol, and the like Isochimoru. These can be used alone or in combination.

  Examples of the aldehyde compounds include formaldehyde, formalin, paraformaldehyde, trioxane, acetaldehyde, propylaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p- Hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde, terephthalic acid aldehyde, etc. Can be mentioned. These can be used alone or in combination.

  Examples of the ketone compound include acetone, methyl ethyl ketone, diethyl ketone, and diphenyl ketone. These can be used alone or in combination.

  Examples of the acid catalyst include sulfuric acid, hydrochloric acid, formic acid acetic acid, and oxalic acid.

  The novolak resin preferably has a weight average molecular weight in terms of monodisperse polystyrene measured by gel permeation chromatography (GPC) of 3,000 to 30,000.

  Preferably, the novolak resin has a weight ratio of metacresol to paracresol of 2: 8 to 8: 2, and two or more of these are used in combination. The novolak resin is more preferably a mixture of a novolak resin having a weight ratio of metacresol: paracresol of 8: 2 and a novolak resin having a weight ratio of metacresol: paracresol of 6: 4.

  In the photoresist composition of the present invention, the content of the novolak resin is preferably 5 to 30% by weight with respect to the total photoresist composition. At this time, if the content is less than 5% by weight, a coating film having a certain thickness or more cannot be obtained, or there is a problem that the fluidity inside the coating film is large and stains are likely to occur. If the weight percentage is exceeded, there is a problem that a coating film having a certain thickness or less cannot be obtained, or the film is applied unevenly.

  The diazide-based photosensitive compound can be produced by reacting a compound such as polyhydroxybenzophenone, 1,2-naphthoquinonediazide, and 2-diazo-1-naphthol-5-sulfonic acid. For example, the b) diazide-based photosensitive compound is 2,3,4-trihydroxybenzophenone-1,2 produced by esterification of trihydroxybenzophenone and 2-diazo-1-naphthol-5-sulfonic acid. -Naphthoquinonediazide-5-sulfonate; or 2,3,4,4'-tetrahydroxybenzophenone-1 produced by esterification of tetrahydroxybenzophenone and 2-diazo-1-naphthol-5-sulfonic acid , 2-naphthoquinonediazide-5-sulfonate, which can be used alone or in admixture. Further, when the above-exemplified diazide compounds are mixed and used, the mixing ratio is not particularly limited, and can be mixed at a ratio well known to those skilled in the art.

  In the photoresist composition of the present invention, the content of the diazide-based photosensitive compound is preferably 2 to 10% by weight based on the entire photoresist composition. At this time, if the content is less than 2% by weight, there is a problem that the remaining film rate is low and the adhesion to the substrate is lowered. If it exceeds 10% by weight, the photosensitive speed is slowed and the development contrast is high. There is a problem.

  The organic solvent is used together with a co-solvent to improve the solubility of the photoresist, is excellent in solubility and reactivity with each component, and is easy to form a coating film. Acetate streams, diethylene glycol streams, and the like can be used. Preferably, the organic solvent is selected from the group consisting of propylene glycol methyl ether acetate, ethyl lactate, 2-methoxyethyl acetate, propylene glycol monomethyl ether, methyl ethyl ketone, methyl isobutyl ketone, and 1-methyl-2-pyrrolidinone. Can be used.

  In the photoresist composition of the present invention, the content of the organic solvent can be included as a balance in the entire photoresist composition, and preferably 70 to 90% by weight based on the entire photoresist composition. it can.

  In addition, the photoresist composition of the present invention may further include a general sensitivity enhancer, if necessary, in order to improve the sensitivity of the photoresist and improve the pattern flow during the hard baking process. The photoresist composition may further include additives such as a colorant, a dye, a plasticizer, an adhesion promoter, a surfactant, and an anti-scratch agent. When these additives are added to the photoresist composition of the present invention, the content thereof is not particularly limited and can be added within a normal range.

  In the present invention, a pattern can be formed using the photoresist composition.

  As a preferred example, the present invention includes a step of coating a substrate with the photoresist composition, followed by heat treatment to form a photoresist film having a predetermined thickness, and exposing and developing to form a pattern. A forming method can be provided. In addition, the present invention may further include performing an etching process on the substrate having the pattern using an etchant.

  Examples of the substrate include silicon, aluminum, indium tin oxide (ITO), indium zinc oxide (IZO), molybdenum, silicon dioxide, doped silicon dioxide, silicon nitride, tantalum, copper, polysilicon, ceramic, and aluminum / copper mixture. And those selected from the group consisting of polysynthetic resins can be used, and are not particularly limited.

  The coating method can be performed by a normal coating method including dipping, spraying, rotation, and spin coating, and the method is not particularly limited. For example, when spin coating is performed, a film having a desired thickness can be formed by appropriately changing the solid content of the photoresist solution depending on the type and method of the spinning device.

  The heat treatment can be performed by ordinary soft baking and hard baking. The heat treatment is performed to evaporate the solvent without thermally decomposing solid components of the photoresist composition. In general, it is preferable to minimize the concentration of the solvent by a soft baking process, and it is preferable to carry out until the photoresist film having a thickness of 3 μm or less remains on the substrate.

  In the exposure, a substrate having a photoresist film formed thereon is exposed to light, particularly ultraviolet rays, using an appropriate mask or a template, thereby forming a desired pattern.

  The exposed substrate is sufficiently immersed in an alkaline developing aqueous solution, and then left until all or almost most of the photoresist film exposed to light is dissolved. At this time, the developing aqueous solution is preferably an aqueous solution containing alkali hydroxide, ammonium hydroxide or tetramethylammonium hydroxide.

  The substrate having the exposed portion dissolved and removed as described above is taken out of the developer, and then further heat-treated by a hard bake process to improve the adhesion and chemical resistance of the photoresist film. Can do. Such heat treatment is preferably carried out at a temperature below the softening point of the photoresist film, particularly preferably at a temperature of 90 to 140 ° C.

  In addition, the exposed and developed pattern can treat the exposed substrate portion by etching with a normal copper etching solution or gas plasma. At this time, the unexposed portion of the substrate is protected by a photoresist film. Is done. In this way, a fine circuit pattern can be formed on the substrate by removing the photoresist film with an appropriate stripper after the substrate is processed.

  The pattern manufactured by the above method is excellent in pattern shape because the film surface by vacuum drying is dried simultaneously with the inside due to the improvement of printability, so that defects in subsequent processes can be minimized. Therefore, the pattern using the photoresist composition of the present invention is suitable for use in the production of fine circuits such as liquid crystal display circuits and semiconductor integrated circuits.

  Hereinafter, the present invention will be described with reference to the following examples and comparative examples. However, these examples are merely for illustrating the present invention, and the present invention is not limited thereto.

[Examples 1-4] and [Comparative Examples 1-3]
A novolak resin having a weight ratio of metacresol: paracresol of 6: 4, 2,3,4-trihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonate and 2,3,4,4-tetrahydroxybenzophenone -1,2-naphthoquinonediazide-5-sulfonate mixed at 5: 5 parts by weight, dimethyl-2-methylglutarate as a co-solvent, propylene glycol methyl ether acetate (PGMEA) as a solvent, ethyl lactate Using normal butyl acetate, each component was uniformly mixed with the composition and content shown in Table 1 below to prepare photoresist compositions of Examples and Comparative Examples.

Experimental example 1

<Evaluation of thickness uniformity and coating stain>
The photoresist composition for a liquid crystal display device circuit manufactured in the examples and comparative examples was slit-coated on a molybdenum-attached glass substrate having a size of 400 mm in width and 300 mm in length, and then reduced in pressure for 60 seconds at 0.5 Torr or less. Then, the substrate was heated and dried at 110 ° C. for 90 seconds to form a film film having a thickness of 1.50 μm. Thereafter, the film thickness uniformity and coating stain characteristics were measured by the following methods, and the results are shown in Table 2 below.

(1) Thickness uniformity The thickness of the photoresist film is measured 20 times horizontally and 15 times vertically, for a total of 300 times, and the maximum thickness and the minimum thickness are measured. Asked.

(2) Characteristics of coating stain The photoresist film film was observed with the naked eye under the application of a halogen lamp for surface observation, and evaluated by the degree of the horizontal stripe pattern. At this time, the evaluation criteria for the characteristics of the coating stain are as shown in FIG.

  If the result of the said Table 2 is seen, it will be understood that Examples 1-4 of the present invention have no stain and very excellent coating uniformity compared to Comparative Examples 1-3.

Experimental example 2

<Pattern shape>
The photoresist composition for a liquid crystal display device circuit manufactured in the above examples and comparative examples was spin-coated on a 3-inch silicon wafer, and then dried under reduced pressure for 60 seconds at 0.5 Torr or less, and the substrate was 110. Heat drying at 90 ° C. for 90 seconds to form a film film having a thickness of 1.50 μm.

  Exposure was performed using an exposure device, and an aqueous solution containing 2.38% tetramethylammonium hydroxide was developed at room temperature for 60 seconds to form a pattern. The profile of the formed pattern was observed with SEM. At this time, the evaluation criteria for the pattern shape are as shown in FIG. 2, and the results are shown in Table 3.

  As can be seen from Table 3, Examples 1 to 4 using the specific co-solvent were superior in pattern shape as compared with Comparative Examples 1 to 3.

Claims (6)

(A) 5-30% by weight of novolac resin,
(B) 2 to 10% by weight of a diazide photosensitive compound,
(C) A photoresist composition comprising 1 to 70% by weight of a co-solvent represented by the following chemical formula (1) and (d) a remaining amount of organic solvent.
In the above formula, R ₁ is hydrogen or an alkyl group having 1 to 10 linear or side chain carbon atoms, and R ₂ has 1 to 10 linear or side chain carbon atoms. An alkyl group or an allyl group;   The co-solvent represented by the chemical formula (1) is selected from the group consisting of dimethyl-2-methyl glutarate, dimethyl adipate, dimethyl glutarate, dimethyl succinate, diisobutyl adipate, diisobutyl glutarate, and diisobutyl succinate. The photoresist composition of claim 1, wherein the photoresist composition is one or more selected from the above.   3. The photoresist composition according to claim 1, wherein the novolak resin is a mixture of two or more novolak resins having a weight ratio of metacresol to paracresol of 2: 8 to 8: 2. 4.   The photosensitive compound is 2,3,4-trihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonate, 2,3,4,4′-tetrahydroxybenzophenone-1,2-naphthoquinonediazide-5. The photoresist composition according to claim 1, which is a sulfonate or a mixture thereof.   The organic solvent is one or more selected from the group consisting of propylene glycol methyl ether acetate, ethyl lactate, 2-methoxyethyl acetate, propylene glycol monomethyl ether, methyl ethyl ketone, methyl isobutyl ketone, and 1-methyl-2-pyrrolidinone. The photoresist composition according to any one of claims 1 to 4, wherein   A pattern comprising the steps of: coating a photoresist composition according to any one of claims 1 to 5 on a substrate; then heat-treating to form a photoresist film having a predetermined thickness; and exposing and developing to form a pattern. Forming method.