TWI546620B - Photoresist composition - Google Patents

Description

Photoresist composition

The present invention relates to a photoresist composition, and more particularly to a photoresist composition which has excellent coating uniformity and pattern profile after vacuum drying, and has superior suppression after coating. The ability to produce spots can be easily used in the actual processing environment, and in the case of mass production, the processing environment can be further improved by reducing the amount of use and reducing the time required for 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 coated on an insulating film or a conductive metal film which has been formed on a substrate, and then has a predetermined The shaped reticle is a mask that exposes and develops the coated photoresist composition to form a pattern of a predetermined shape. Thereafter, the photoresist film formed with the above-described pattern is used as a mask, and the metal film or the insulating film is etched to remove the residual photoresist film to form a fine circuit on the substrate.

The aforementioned coating is generally by a spin coating method or a slit coating method. The foregoing coating method has the advantage that a uniform photoresist film can be formed, and the coating uniformity means that the thickness of the applied photoresist is uniformly covered on the entire substrate, and the higher the coating uniformity, the more capable The physical properties are ensured in the subsequent process. Therefore, when a uniform and non-spotted (uneven) photoresist film is to be formed, it is preferred to use a plurality of solvents.

The photoresist composition generally contains a polymer resin, a photosensitive compound, and a solvent. Many proposals have been made in the past for improving the coating uniformity, the photospeed, and the development of the photoresist film formed by the photoresist composition. Contrast, image resolution and human safety.

In particular, for example, U.S. Patent No. 3,666,473 discloses the use of a mixture of two phenol formaldehyde novolaks and a typical photosensitive compound. U.S. Patent No. 4,115,128 discloses a phenolic phenol in order to increase the sensitization speed. A technique for adding a composition of an organic acid cyclic anhydride to a resin and a naphthoquinone diazide sensitizer. U.S. Patent No. 4,550,069 discloses the use of a coating for uniformity, speed, and safety. A technique of a novolac resin, an o-quinone diazide photosensitive compound, and a photoresist composition of a propylene glycol alkyl ether acetate as a solvent.

Further, in order to improve the physical properties and processing stability of the photoresist composition for a liquid crystal display device, various solvents for spin coating methods such as ethylene glycol monoethyl ether acetate and propylene glycol monoethyl ether have been developed. Acetate, ethyl lactate, etc. However, when ethylene glycol monoethyl ether acetate is used, it has been reported that there is a strong side effect on human safety. When propylene glycol monoethyl ether acetate is used, a large substrate such as a TFT-LCD is baked. After the baking step, problems such as pin marks are caused, and problems such as deterioration of planarization characteristics when used alone as a solvent occur, and when ethyl lactate is used, adhesion of the composition to the substrate is also poor, and it is difficult to perform uniformity. Problems such as coatings exist.

Further, in the case of the slit coating method, since the centrifugal force of the conventional spin coating method is not applied, it is necessary to use a solvent having excellent flatness and uniform pattern performance when vacuum-dried after application in order to apply uniformly.

In particular, since the surface of the film is more easily dried than the inside during vacuum drying, the pattern is easily deformed into a reverse taper shape, resulting in defective products in subsequent processes.

Therefore, there is still a need for a photoresist composition that can be adapted to various industrial processes without sacrificing any of its preferred characteristics. Preferred characteristics of the photoresist composition include coating uniformity, suppression of coating spot (unevenness) characteristics, photospeed, residual film ratio, development contrast, image resolution, solubility of polymer resin, and substrate Adhesion, and uniformity of circuit line width.

It is an object of the present invention to provide a photoresist composition comprising a co-solvent of a specific structure, which can reduce speckle generation and improve coating uniformity during coating, and prevent generation of a reverse tapered pattern during vacuum drying, thereby significantly The shape of the pattern is improved without causing uneven pattern width.

The present invention provides a photoresist composition comprising: (a) 5 to 30 weight percent (wt%) of a novolac resin; (b) 2 to 10 weight percent (wt%) of a diazide compound; (c) 1 to 70% by weight (wt%) of the compound represented by the following Chemical Formula 1; and (d) the balance of the organic solvent.

In the above Chemical Formula 1, R ₁ is hydrogen or a linear or branched alkyl group having 1 to 10 carbon atoms, and R ₂ is a linear or branched alkyl group or allyl group having 1 to 10 carbon atoms.

Further, the present invention provides a pattern forming method comprising the steps of first coating a photoresist composition on a substrate, followed by heat treatment to form a photoresist film having a predetermined thickness, and then performing exposure and development to form a pattern. .

[Simple description of the map]

The first figure is a criterion for evaluating the characteristics of the coating spots of the photoresist film.

The second figure is an evaluation criterion for the shape of the photoresist pattern.

The invention is described in detail below.

The present invention relates to a photoresist composition which satisfies the required photospeed, residual film ratio, development contrast, image resolution, solubility of a polymer resin, adhesion to a substrate, and the adhesion of a photoresist composition. The physical properties such as the uniformity of the circuit line width, in particular, excellent coating uniformity, and the occurrence of coating spots can be avoided, thereby forming an excellent pattern shape.

The photoresist composition of the present invention is characterized by comprising a novolak resin, a diazide-based photosensitive compound, and an organic solvent, and further contains a co-solvent represented by the following Chemical Formula 1 for improving coatability.

In the above Chemical Formula 1, R ₁ is hydrogen or a linear or branched alkyl group having 1 to 10 carbon atoms, and R ₂ is a linear or branched alkyl group or allyl group having 1 to 10 carbon atoms.

The cosolvent represented by the above Chemical Formula 1 uses dimethyl-2-methylglutarate, dimethyladipate, dimethylglutarate, and dibutyl glutarate. Preferably, at least one mixture of dimethylsuccinate, diisobutyladipate, diisobutylglutarate, diisobutylsuccinate or the aforementioned cosolvent is preferred. Among them, dimethyl 2-methylglutarate which is excellent in coating uniformity or speckle-inhibiting property is particularly preferable.

The co-solvent represented by the above Chemical Formula 1 can be appropriately added to the photoresist composition of the present invention in consideration of coating uniformity. For example, 1 to 70% by weight (wt%) may be added with respect to the total amount of the photoresist composition, preferably 5 to 50% by weight (wt%). At this time, if the amount of the co-solvent added is less than 1% by weight (wt%), spots may be formed or an inverted tapered pattern may be formed during vacuum drying, and if the amount added exceeds 70% by weight (wt%), the residual film ratio may be Reduced, and the vacuum drying time will become longer.

Further, the novolac resin is an alkali-soluble resin, and a general novolac resin used in a conventional photoresist composition can be used. Specifically, the novolak resin can be obtained by subjecting a phenol compound to a polycondensation reaction with an aldehyde compound or a ketone compound in the presence of an acid catalyst. For example, the novolak resin may be a novolak resin synthesized from m-cresol alone; or a novolac resin synthesized from p-cresol alone; or a novolac resin using resorcin; or salicylic acid (salicylic) A novolac resin produced by reacting with benzylaldehyde; or a novolak resin such as m-cresol, p-cresol or resorcin.

The phenol compound may, for example, be phenol, ortho-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 3,4-dimethylphenol or 3,5-dimethyl. Phenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,6-trimethylphenol, 2-tert-butylphenol, 3-tert-butyl 3-tert-butylphenol, 4-tert-butylphenol, 2-methylresorcinol, 4-methylresorcinol, 5-methyl 5-methylresorcinol, 4-tert-butylcatechol, 2-methoxy phenol, 3-methoxy phenol ), 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 2-A Oxy-5-methylphenol, 2-tert-butyl-5-methylphenol, thymol, or isothymol. These compounds may be used singly or in combination.

The aldehyde compound may, for example, be formaldehyde, formalin, paraformaldehyde, trioxane, acetaldehyde, propylaldehyde, benzaldehyde or phenylacetaldehyde. ), α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p- P-hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-methylbenzaldehyde (o -methylbenzaldehyde), m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde ), or terephthalic aldehyde or the like. These compounds may be used singly or in combination.

The ketone compound may, for example, be acetone, methyl ethyl ketone, diethyl ketone or diphenyl ketone. These compounds may be used singly or in combination.

The acid catalyst may, for example, be sulfuric acid, hydrochloric acid, formic acid, acetic acid or oxalic acid.

Preferably, the novolak resin is a novolac resin having a weight average molecular weight of 3,000 to 30,000, and the molecular weight is measured by gel permeation chromatography (GPC), and is obtained by converting monodisperse polystyrene as a standard sample. .

The weight ratio of cresol to p-cresol between the novolac resins is preferably from 2:8 to 8:2, and at least two kinds of these novolak resins are used in combination. Preferably, the novolac resin is a mixture of a novolak resin having a weight ratio of m-cresol:p-cresol of 8:2 and a novolac resin having a weight ratio of m-cresol:p-cresol of 6:4. .

In the photoresist composition of the present invention, the content of the novolak resin is preferably from 5 to 30% by weight (% by weight) based on the total amount of the photoresist composition. In this case, if the content of the novolak resin is less than 5 weight percent (wt%), a coating film having a film thickness larger than a certain thickness cannot be obtained, or a speckle is likely to be generated due to a large fluidity inside the coating film, and if the content exceeds 30% by weight (wt%), a coating film having a film thickness of less than a certain thickness or a film thickness unevenness could not be obtained.

The above-mentioned diazide compound can be produced by a reaction of a compound such as polyhydroxybenzophenone, 1,2-naphthoquinonediazide or 2-diazo-1-naphthol-5-sulfonic acid. For example, the above diazide compound may be a 2,3,4-trihydroxy group produced by esterification of trihydroxybenzophenone with 2-diazo-1-naphthol-5-sulfonic acid. Dibenzophenone-1,2-nahydroxybenzophenone-1, 2-naphthoquinonediazido-5-sulfonic acid ester; or tetrahydroxybenzophenone 2,3,4,4'-tetrahydroxybenzophenone-1,2-naphthoquinonediazide produced by esterification with 2-diazo-1-naphthol-5-sulfonic acid 5-sulfonate (2,3,4,4'-tetrahydroxybenzophenone-1, 2-naphthoquinonediazido-5-sulfonic acid ester). These compounds may be used singly or in combination. Further, in the case of mixing the above-described examples of the diazide-based compound, the mixing ratio thereof is not particularly limited, and it may be mixed in a ratio known to those skilled in the art.

The content of the aforementioned diazide compound in the photoresist composition of the present invention is preferably from 2% by weight (% by weight) to 10% by weight (% by weight). In this case, when the content of the above-mentioned diazide-based photosensitive compound is less than 2% by weight (% by weight), there is a problem that the residual film ratio is lowered and the adhesion to the substrate is deteriorated, and if the content exceeds 10% by weight (wt) %), there is a problem that the light speed is too slow and the development contrast is too high.

The use of the above-mentioned organic solvent together with a co-solvent can improve the solubility of the photoresist, and the solvent can use a glycol ether having excellent solubility, good reactivity with each component, and easy formation of a coating film, and ethylene glycol. Ethylene glycol alkyl ether acetate and diethylene glycol. Preferably, the aforementioned 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 isobutylene. At least one of a ketone and 1-methyl-2-pyrrolidone.

In the photoresist composition of the present invention, the organic solvent may be contained in the total photoresist composition in a balance of 70 to 90% by weight based on the total amount of the photoresist composition. %) is better.

Further, the photoresist composition of the present invention may further contain a generally used sensitivity improving agent as needed to improve the sensitivity of the photoresist and the formation of a pattern during hard baking. Further, the photoresist composition may further contain an additive such as a colorant, a dye, a plasticizer, an adhesion promoter, a surfactant, and an anti-wear agent. When the aforementioned additive is added to the photoresist composition of the present invention, the content thereof is not particularly limited, and may be an addition amount in a generally usual range.

The present invention can utilize the aforementioned photoresist composition to form a pattern.

As a preferred embodiment, the present invention can provide a pattern forming method comprising the steps of: coating the foregoing photoresist composition on a substrate, followed by heat treatment to form a photoresist film having a predetermined thickness, and then performing exposure and development To form a pattern. Moreover, the present invention may further comprise the step of etching the substrate having the aforementioned pattern using an etching solution.

The substrate may be made of tantalum, aluminum, indium tin oxide (ITO), indium zinc oxide (IZO), molybdenum, hafnium oxide, doped ceria, tantalum nitride, hafnium, copper, polycrystalline germanium, ceramic, aluminum/ A material such as a copper mixture or various polymerizable resins is not particularly limited.

The coating method may be a usual coating method including a dip coating method, a spray coating method, a roll coating method, and a spin coating method, and is not particularly limited. For example, when the spin coating method is employed, the film of a desired thickness can be obtained by appropriately adjusting the solid content in the photoresist solution according to the type and method of the spinning device.

The aforementioned heat treatment can be generally used for soft baking and hard baking. The purpose of the above heat treatment is to evaporate the solvent in a state where the solid component in the photoresist composition is not thermally decomposed. Generally, the concentration of the solvent is minimized by the soft baking step until the thickness of the photoresist film remaining on the substrate does not exceed 3 μm.

The substrate on which the photoresist film is formed is subjected to the aforementioned exposure using an appropriate mask, template, or the like, in particular, ultraviolet exposure to form a pattern having a desired shape.

The substrate thus exposed is sufficiently immersed in an alkaline developing aqueous solution until all or most of the photoresist film of the exposed portion is dissolved. In this case, it is preferred that the developing aqueous solution contains an alkali hydroxide, ammonium hydroxide or tetramethyl ammonium hydroxide.

After removing the substrate from which the photoresist of the exposed portion is dissolved and removed from the developer, heat treatment can be performed by a hard bake step to enhance the adhesion and chemical resistance of the photoresist film. Such heat treatment is preferably carried out at a temperature lower than the softening point of the photoresist film, particularly at a temperature of from 90 ° C to 140 ° C.

The exposed portion of the substrate is etched by a commonly used copper etchant or gas plasma to form the exposed portion of the substrate. At this time, the unexposed portion of the substrate is protected by the photoresist film. After the substrate is treated in this manner, the photoresist film is removed by a suitable stripper to form a fine circuit pattern on the substrate.

The pattern produced by the above method is improved in printing performance, and the surface of the film and the inside are simultaneously dried during vacuum drying, and has an excellent pattern shape, thereby minimizing defects occurring in subsequent processes. Therefore, the pattern formed by the photoresist composition of the present invention is suitably used in the manufacture of a fine circuit such as a circuit of a liquid crystal display device or a semiconductor integrated circuit.

The photoresist composition of the present invention can reduce the generation of spots during coating and improve coating uniformity, and does not form a reverse-conical pattern during vacuum drying to form a preferred pattern shape. In particular, in the prior art, in order to improve the pattern shape, the amount of the sensitizer used, the ratio of the different types of sensitizers, or the method of reducing the contrast enhancer, the pattern width is not uniform, but the present invention does not generate these questions.

Hereinafter, the present invention will be described with reference to examples and comparative examples. However, the embodiments and comparative examples are merely examples of the invention, and the invention is not limited thereto.

<Examples 1 to 2 and Comparative Examples 1 to 3>

A novolak resin having a m-cresol:p-cresol weight ratio of 6:4; 2,3,4-trihydroxybenzophenone-1,2-naphthoquinonediazide in a weight ratio of 5:5 a photosensitive compound prepared by using -5-sulfonate and 2,3,4,4'-tetrahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonate; as a cosolvent Dimethyl 2-methylglutarate; Propylene Glycol Monomethyl Ether Acetate (PGMEA), ethyl lactate, normal butylacetate as solvent, and shown in Table 1 below The components and contents were uniformly mixed, and the photoresist compositions of the examples and the comparative examples were prepared.

The photoresist composition for the liquid crystal display device circuit manufactured by the foregoing examples and comparative examples was slit-coated on a glass substrate having a width of 400 mm and a length of 300 mm attached to molybdenum in a slit coating manner, followed by 0.5. The substrate was dried under reduced pressure for 60 seconds under the conditions of Torr, and then the substrate was dried by heating at 110 ° C for 90 seconds to form a film having a thickness of 1.50 μm. Next, physical properties such as uniformity of the film thickness and uniformity of coating were measured by the following methods, and the results are shown in Table 3 below.

(1) Thickness uniformity: The thickness is measured 20 times in the width direction, 15 times in the length direction, and 300 times in total, and the maximum thickness and the minimum thickness of the photoresist film are evaluated, and the thickness is uniform by the following formula Sex.

[calculation]

Thickness uniformity (%) = (maximum thickness - minimum thickness) / (maximum thickness + minimum thickness)

(2) Coating uniformity: The photoresist film was visually observed under a halogen lamp for surface observation, and evaluated according to the lateral grain condition. At this time, the evaluation criteria for coating uniformity are shown in Table 2 below.

From the results of the above Table 2, it was confirmed that Examples 1 to 4 of the present invention have no spots as compared with Comparative Examples 1 to 3, and the coating uniformity is extremely excellent.

<Experimental Example 2> - Pattern shape

The photoresist composition for liquid crystal display device circuits manufactured in the foregoing Examples and Comparative Examples was spin-coated on a 3 inch tantalum wafer by spin coating, and then reduced under 0.5 Torr. The film was dried by pressure for 60 seconds, and then the substrate was dried by heating at 110 ° C for 90 seconds to form a film having a thickness of 1.50 μm.

Exposure was carried out using an exposure machine, and then developed with an aqueous solution containing 2.38% of tetramethyl ammonium hydroxide at room temperature for 60 seconds to form a pattern. The pattern profile formed was observed by SEM. At this time, the evaluation criteria for the pattern shape are as shown in the second figure, and the results are shown in the following Table 3.

As shown in the above Table 3, the pattern shapes of Examples 1 to 4 using a specific co-solvent were also superior to Comparative Examples 1 to 3.

The first figure is a criterion for evaluating the characteristics of the coating spots of the photoresist film.

The second figure is an evaluation criterion for the shape of the photoresist pattern.

Claims (6)

A photoresist composition comprising: (a) 5 to 30 weight percent (wt%) of a novolak resin; (b) 2 to 10 weight percent (wt%) of a diazide compound; (c) 5 ~50% by weight (wt%) of the cosolvent represented by the following Chemical Formula 1; and (d) the balance of the organic solvent, In the chemical formula 1, R ₁ is hydrogen or a linear or branched alkyl group having 1 to 10 carbon atoms, and R ₂ is a linear or branched alkyl group or allyl group having 1 to 10 carbon atoms. The photoresist composition according to claim 1, wherein the cosolvent represented by the chemical formula 1 is selected from the group consisting of dimethyl 2-methylglutarate, dimethyl adipate, and glutaric acid At least one compound of the group consisting of methyl ester, dimethyl succinate, diisobutyl adipate, diisobutyl glutarate, and diisobutyl succinate. The photoresist composition according to claim 1, wherein the novolac resin comprises at least two novolak resin mixtures obtained by mixing m-cresol and p-cresol, the m-cresol and p-cresol The mixing weight ratio ranges from 2:8 to 8:2. The photoresist composition according to claim 1, wherein the photosensitive compound is 2,3,4-trihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonate 2,3,4,4'-tetrahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonate or a mixture thereof. The photoresist composition according to claim 1, wherein the organic solvent is selected from the group consisting of propylene glycol methyl ether acetate, ethyl lactate, ethylene glycol methyl ether acetate, propylene glycol monomethyl ether, methyl At least one compound of the group consisting of ethyl ketone, methyl isobutyl ketone, and 1-methyl-2-pyrrolidone. A pattern forming method comprising the steps of: coating a photoresist composition according to any one of claims 1 to 5 on a substrate, followed by heat treatment to form a photoresist having a predetermined thickness. The film is then exposed and developed to form a pattern.