KR20100069304A - A positive photoresist composition - Google Patents

Abstract

PURPOSE: A positive photoresist composition is provided to obtain excellent heat resistance and improved residual film rate and to be used for a process of manufacturing a semiconductor and a liquid crystal display device. CONSTITUTION: A positive photoresist composition comprises; 10 ~ 25 weight% of an alkali-soluble resin; 1 ~ 10 weight% of a dissolution inhibitor; 0.01 ~ 10 weight% of an additive including a diisocyanate compound which is marked as a chemical formula 1; and a solvent. In the chemical formula 1, R is an aromatic compound having a carbon number of 6 ~ 24 and an aliphatic compound having a carbon number of 1 ~ 12. The compound, which is marked as the chemical formula 1, is toluene 2,4-diisocyanate(TDI) which is marked as a chemical formula 2.

Description

Positive photoresist composition {A POSITIVE PHOTORESIST COMPOSITION}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive photoresist composition, and more particularly, to a positive photoresist composition which can be used in the manufacturing process of semiconductors and liquid crystal displays, and has excellent heat resistance, sensitivity, pattern shape, and improved residual film ratio.

Generally as a positive photoresist composition, the composition containing the binder resin which is soluble in alkaline developing solutions, such as a resol or cresol novolak resin, and the dissolution inhibitor which has a quinonediazide group is suitable. Such compositions are widely used in lithography using g-rays, i-rays, and the like.

Such lithography technology is widely used in the field of semiconductor and liquid crystal display device manufacturing in that it is relatively inexpensive and can form a pattern of resist having excellent resolution and shape. However, in the four-sheet mask process, the photoresist composition currently used typically results in a narrow angle of the channel by forming a low angle profile when the heat is applied to 125 ° C. or higher during the baking process.

As a method of strengthening heat resistance in a resist for overcoming the above-mentioned problem, there is generally a method of introducing a high molecular weight resin or adding a high heat resistant material. There is also a method of adding a resin in which carboxylic acids are introduced in order to maintain the dissolution rate of the resin in the developer.

However, this is a good way to enhance the heat resistance of the positive photoresist, but slows down the sensitivity of the photoresist. In addition, by reducing the developing speed of the non-exposed areas where the pattern remains, it is not easily dissolved in the developing solution and residues remain, thereby making it difficult to obtain a processable pattern.

An object of the present invention is to solve the problem of the reflow phenomenon during the four-sheet mask process, positive photoresist composition that can improve the adhesion to the lower substrate, high sensitivity, chemical resistance, heat resistance, strip properties, residual film ratio, etc. To provide.

In order to achieve the above object, the present invention is an alkali-soluble resin; Dissolution inhibitors; An additive comprising a diisocyanate compound represented by the formula (1); And it provides a positive photoresist composition comprising a solvent.

<Formula 1>

In Chemical Formula 1, R is an aromatic compound having 6 to 24 carbon atoms or an aliphatic compound having 1 to 12 carbon atoms.

The positive photoresist composition of the present invention can solve the problem of the reflow phenomenon in the four-mask process, and can improve the adhesion to the lower substrate, high sensitivity, chemical resistance, heat resistance, strip characteristics, residual film ratio and the like.

Hereinafter, the present invention will be described in detail.

Ⅰ. Positive photoresist composition

The positive photoresist composition of the present invention comprises an alkali soluble resin, a dissolution inhibitor, an additive, and a solvent.

Alkali-soluble resin contained in the positive photoresist composition of this invention is not specifically limited, What is known in the art can be used, It is preferable to use a novolak resin. The said novolak resin is obtained by addition-condensation reaction of a phenol compound and an aldehyde compound. Examples of the phenolic compound include phenol, o-, m- and p-cresol, 2,5-xylenol, 3,5-xylenol, 3,4-xylenol, 2,3,5-trimethylphenol, 4-t-butylphenol, 2-t-butylphenol, 3-t-butylphenol, 3-ethylphenol, 2-ethylphenol, 4-ethylphenol, 3-methyl-6-t-butylphenol, 4-methyl 1 type, or 2 or more types selected from the group consisting of 2-t-butylphenol, 2-naphthol, 1,3-dihydroxynaphthalene, 1,7-dihydroxynaphthalene and 1,5-dihydroxynaphthalene Can be mentioned. Examples of the aldehyde compounds include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, phenylaldehyde, α- and β-phenylpropyl aldehydes, o-, m- and p-hydroxybenzaldehyde, glutaraldehyde, glyoxal 1 type, or 2 or more types chosen from the group which consists of o- and p-methylbenzaldehyde.

The addition-condensation reaction between the phenol compound and the aldehyde compound is carried out in a conventional manner in the presence of an acid catalyst. As reaction conditions, a temperature is 60-250 degree in general, and reaction time is 2 to 30 hours in general. Examples of the acid catalyst include organic acids such as oxalic acid, formic acid, trichloroacetic acid, p-toluenesulfonic acid, and the like; Inorganic acids such as hydrochloric acid, sulfuric acid, perchloric acid, phosphoric acid and the like; And one or two or more selected from the group consisting of divalent metal salts such as zinc acetate, magnesium acetate, and the like. The addition-condensation reaction is carried out in a suitable solvent or in bulk. The alkali-soluble resin produced by the addition-condensation reaction preferably has a weight average molecular weight of 2,000 to 50,000 in terms of polystyrene.

In the present invention, the alkali-soluble resin is preferably included in 10 to 25% by weight based on the total amount of the composition. If the alkali-soluble resin is contained in less than 10% by weight may cause a problem that the pattern is not formed well, when included in excess of 25% by weight is the sensitivity is slow, scum may occur, the appropriate sensitivity is slowed Problems can occur with throughput.

It is preferable to use the ester compound of the phenolic compound which has a hydroxyl group, and the quinonediazide sulfonic-acid compound in the dissolution inhibitor contained in the positive photoresist composition of this invention. Here, specific examples of the quinonediazide sulfonic acid compound include o-quinonediazide sulfonic acid. Specific examples of the ester compound include phenolic polyhydroxy compounds having at least three hydroxy groups, 1,2-naphthoquinone diazide-5-sulfonic acid and 1,2-naphthoquinone diazide-4-sulfonic acid. Or ester compounds of 1,2-benzoquinonediazide-4-sulfonic acid.

The ester compound can be obtained by reacting the phenolic compound having the hydroxyl group with o-quinonediazidesulfonyl halide in the presence of a base of triethylamine in a suitable solvent. After completion of the reaction, suitable workup can be carried out to separate the desired quinonediazidesulfonic acid ester. Such post-treatment may include, for example, a method of mixing a reactant with water to precipitate a desired compound, filtering and drying to obtain a powdery product; The reaction is treated with a resist solvent such as 2-heptanone, washed with water, phase separated, and the solvent is removed by distillation or equilibrium flash distillation to obtain the product in the form of a solution in the resist solvent. Equilibrium flash distillation here refers to a kind of continuous distillation that distills a portion of the liquid mixture and separates the vapor into liquid phase when the resulting vapor is brought into sufficient contact with the liquid phase. This method is suitable for the concentration of the thermosensitive material because it has a very good vaporization rate, vaporization takes place in an instant, and the equilibrium between the vapor and the liquid phase is rapid.

The dissolution inhibitor is preferably included in 1 to 10% by weight based on the total weight of the composition. If it is included in less than 1% by weight, the pattern is not formed, the problem is that most of the resist is dissolved, if more than 10% by weight there is a problem that scum and the like may exist between the patterns.

An additive included in the positive photoresist composition of the present invention is a diisocyanate compound represented by the following Chemical Formula 1 to impart high heat resistance to the positive photoresist composition of the present invention and to improve the residual film ratio.

<Formula 1>

In Chemical Formula 1, R is an aromatic compound having 6 to 24 carbon atoms or an aliphatic compound having 1 to 12 carbon atoms.

The additive is preferably toluene 2,4-diisocyanate (TDI) represented by the following formula (2).

<Formula 2>

The additive is preferably included in an amount of 0.01 to 10% by weight, and more preferably 0.1 to 5% by weight based on the total weight of the composition. If it is included in less than 0.01% by weight, it is difficult to implement the high heat resistance characteristics, when it exceeds 10% by weight, the aging characteristics are lowered. The additive is high molecular weight by premixing with the alkali-soluble resin for 25 to 60 ℃, 1 to 6 hours.

The positive photoresist composition of the present invention may further include a low molecular weight phenolic compound and / or a surfactant as an additive in addition to the compound represented by Chemical Formula 1.

The solvent included in the positive photoresist composition of the present invention dissolves additives including an alkali-soluble resin, a dissolution inhibitor, and a compound represented by Formula 1, and allows the positive photoresist composition of the present invention to exist in the form of a solution. The solvent is not particularly limited as long as it is capable of dissolving the components of the present invention, has a suitable drying speed, and can form a uniform and smooth coating film after evaporation of the solvent. Examples of the solvent include glycol ether esters such as ethyl cellosolve acetate, methyl cellosolve acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; Glycol ethers such as ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether and propylene glycol monoethyl ether; Esters such as ethyl acetate, butyl acetate, amyl acetate and ethyl pyruvate; Ketones such as acetone, methyl isobutyl ketone, 2-heptone and cyclohexanone; And cyclic ester, such as (gamma) -butyrol acetone, etc. are mentioned. The said solvent can be used individually or in combination of 2 or more types.

II. Pattern Forming Method Using Positive Photoresist Composition

The positive photoresist composition of the present invention may be applied to a substrate in conventional manner, including dipping, spraying, spinning and spin coating. For example, in the case of spin coating, a coating having a desired thickness can be formed by appropriately changing the solid content of the photoresist solution according to the type and method of the spinning apparatus. The substrate includes silicon, aluminum, silicon dioxide, doped silicon dioxide, silicon nitride, tantalum, copper, polysilicon, ceramics, aluminum / copper mixtures, and various polymerizable resins.

The coated positive photoresist composition may be soft baked at a temperature of 20 ° C to 100 ° C. The soft bake is to evaporate the solvent without pyrolyzing the solid component in the photoresist composition. It is generally desirable to minimize the concentration of the solvent through a soft bake process, so this treatment is performed until most of the solvent has evaporated leaving a thin coating of photoresist composition on the substrate.

Next, the substrate on which the photoresist film is formed is exposed using a suitable mask or template. At the time of exposure, it is preferable to expose with a short wavelength high energy ray, X-ray, or an electron beam of wavelength 500nm or less.

The substrate including the exposed photoresist film is sufficiently immersed in the alkaline developing aqueous solution, and then left until all or almost all of the exposed photoresist film is dissolved. Although it does not specifically limit as said alkaline developing aqueous solution, The aqueous solution containing alkali hydroxide, ammonium hydroxide, tetramethylammonium hydroxide (TMAH), (2-hydroxyethyl) trimethyl ammonium hydroxide (also called choline) can be used. Can be.

After the exposed portion is dissolved and removed to remove the substrate on which the photoresist pattern is formed, a hard bake process may be performed to enhance adhesion and chemical resistance of the photoresist film. The hard bake process is preferably performed at a temperature below the softening point of the photoresist film, preferably at a temperature of about 100 to 150 ℃.

Subsequently, the substrate on which the photoresist pattern is formed is etched by wet etching using an etching solution or dry etching using a gas plasma. At this time, the substrate located under the photoresist pattern is protected. After the substrate is treated in this manner, a fine circuit pattern is formed on the substrate by removing the photoresist pattern with an appropriate stripper.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited thereto. In the examples, the percentages, parts and ratios indicating content or amount used are all by weight unless otherwise indicated. The weight average molecular weight is a value measured by GPC using polystyrene as a standard.

Synthesis Example 1 Preparation of Novolac Resin A-1

m-cresol and p-cresol were mixed at a weight ratio of 60:40, formalin was added thereto, and condensed by a conventional method using an oxalic acid catalyst to obtain a cresol novolak resin. This resin was fractionated and cut except for the polymer region and the low molecular region to obtain a novolac resin having a weight average molecular weight of 15,000. Hereinafter, this novolak resin is called A-1.

Synthesis Example 2 Preparation of Novolac Resin A-2

m-cresol and p-cresol were mixed at a weight ratio of 50:50, formalin was added thereto, and condensed by a conventional method using an oxalic acid catalyst to obtain a cresol novolak resin. This resin was fractionated and cut except for the polymer region and the low molecular region to obtain a novolac resin having a weight average molecular weight of 16,000. Hereinafter, this novolak resin is called A-2.

Examples 1-3 and Comparative Example 1: Preparation of Positive Photoresist Composition

The novolak resin and toluene 2,4-diisocyanate shown in Table 1 were premixed according to the composition ratio shown in Table 1, and the premixed novolak resin and toluene 2,4-diisocyanate were dissolved inhibitors and low molecular weight phenols. A positive photoresist composition was prepared by mixing in a solvent with a compound and a surfactant. At this time, the content of the component except the surfactant and the solvent is based on the conversion in solid content.

Suzy
(Parts by weight) Dissolution inhibitor
(Parts by weight) additive
(Parts by weight) Low molecular weight
Phenolic Compound
(Parts by weight) Surfactants
(Parts by weight) menstruum
(Parts by weight) Example 1 A-1 / A-2 12/8 = 20 B-1 7 C-1 0.75 D-1 4 E-1 0.2 F-1 / F-2 30 / 35.8 = 65.8 Example 2 A-1 / A-2 12/8 = 20 B-1 7 C-1 1.5 D-1 4 E-1 0.2 F-1 / F-2 30 / 35.8 = 65.8 Example 3 A-1 / A-2 12/8 = 20 B-1 7 C-1 2.25 D-1 4 E-1 0.2 F-1 / F-2 30 / 35.8 = 65.8 Comparative Example 1 A-1 / A-2 12/8 = 20 B-1 7 C-1 0 D-1 4 E-1 0.2 F-1 / F-2 30 / 35.8 = 65.8

A-1: the novolak resin prepared by Synthesis Example 1

A-2: Novolak Resin Prepared in Synthesis Example 2

B-1: 2,6-bis [4-hydroxy-3- (2-hydroxy-5-methylbenzyl) -2,5-dimethylbenzyl] -4-methylphenol 1 having a reaction molar ratio of 1: 2.2. , 2-naphthoquinonediazide5-fonyl chloride condensate (powder form)

C-1: toluene 2,4-diisocyanate

D-1: 4,4 '-(2-hydroxybenzylidene) di-2,6-xylenol

F-1: Propylene Glycol Methyl Ether Acetate (PGMEA)

F-2: ethyl lactate (EL)

Test Example: Evaluation of Characteristics of Positive Photoresist Composition

Examples 1 to 3 and Comparative Example 1 were filtered through a fluororesin filter to obtain a resist solution. The resist solutions were spin-coated onto a silicon wafer treated with hexamethyldisilazane and pre-baked at 90 ° C. for 60 seconds directly on a hot plate to form a resist film having a thickness of 1.50 μm. A wafer with a resist film was used with a line-and-space pattern while using a i-line stepper ("NSR-2005 i9C", manufactured by Nikon Co., Ltd., NA = 0.57, δ = 0.60) to gradually change the exposure dose. The exposure was carried out. The wafer was then subjected to post-exposure bake for 60 seconds at 110 ° C. on a hot plate and then puddle developed for 60 seconds using an aqueous 2.38% tetramethylammonium hydroxide solution. The developed pattern was observed by visual and scanning electron microscopy and is shown in FIGS. 1 to 4.

In addition, the remaining film rate, strip, and heat resistance were evaluated for each pattern by the following method. The results are shown in Table 2 below.

Remnant Rate

The ratio of the resist film thickness after development to the resist film thickness after development.

Residual film ratio = (film thickness after development ÷ film thickness before development) X 100

<Resolution>

When exposed with effective sensitivity (exposure amount when the cross section of the 3.0 µm line-and-space pattern is 1: 1), the minimum line width that separates the line-and-space pattern is shown.

<Strip>

The surface after the strip was observed using PRS2000 (manufacturer: Dongwoo Finechem).

<Heat resistance>

After treatment at 150 ° C. and 150 sec on a hot plate, the results were evaluated by comparing the profiles with the results before the treatment using a scanning electron microscope.

Residual rate (%) resolution strip Heat resistance Example 1 98 ○ ○ △ Example 2 99 ○ ○ ○ Example 3 99 ○ ○ ◎ Comparative Example 1 96 ○ ○ X

Strip: ◎: Very good, ○: Good, △: Normal, X: Bad

Heat resistance: ◎: Unchanged, ○: Slightly changed, △: Normal, X: Poor

Referring to Table 2 and Figures 1 to 4, the resist pattern prepared from the composition of Examples 1 to 3 to which toluene 2,4-diisocyanate was added to the resist, the heat resistance and the residual film rate characteristics of Comparative Example 1 It was superior to the resist pattern made of the composition.

1 is a scanning micrograph of the resist pattern formed in Example 1. FIG.

FIG. 2 is a scanning micrograph of the resist pattern formed in Example 2. FIG.

3 is a scanning micrograph of the resist pattern formed in Example 3. FIG.

4 is a scanning micrograph of the resist pattern formed in Comparative Example 1.

Claims (6)

Alkali-soluble resins; Dissolution inhibitors; An additive comprising a diisocyanate compound represented by the formula (1); And A positive photoresist composition comprising a solvent: <Formula 1>

In Chemical Formula 1, R is an aromatic compound having 6 to 24 carbon atoms or an aliphatic compound having 1 to 12 carbon atoms. The method according to claim 1, 10 to 25% by weight of the alkali-soluble resin; 1 to 10 wt% of the dissolution inhibitor; 0.01 to 10 wt% of the additive; And A positive photoresist composition comprising the remaining amount of the solvent. The method according to claim 1, The compound represented by Formula 1 is a toluene 2,4-diisocyanate (Toluene 2,4-diisocyanate: TDI) represented by the following formula (2). <Formula 2>

The method according to claim 1, The alkali soluble resin is a novolak resin, characterized in that the positive photoresist composition. The method according to claim 1, The dissolution inhibitor is a positive photoresist composition, characterized in that the ester compound of the phenolic compound having a hydroxyl group and the quinonediazide sulfonic acid compound. The method according to claim 1, The solvent is a positive photoresist composition, characterized in that one or two or more selected from the group consisting of glycol ether esters, glycol ethers, esters, ketones and cyclic esters.

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