KR20110035528A - A positive photoresist composition - Google Patents

Abstract

PURPOSE: A positive photo-resist composition is provided to overcome the damage of substrates and metal films in a four masks-based dry etching process by forming patterns into a nearly vertical shape. CONSTITUTION: A positive photo-resist composition includes an alkaline soluble resin, a photo-resist agent, an additive containing a compound represented by chemical formula 1, and a solvent. In the chemical formula 1, R1, R2, and R3 are respectively H or a group represented by chemical formula 2. The alkaline soluble resin is a novolak resin. The photo-resist agent is the ester compound of a phenolic compound containing hydroxyl group and a quinone diazide sulfonic acid compound. The solvent is one or more, or two or more selected from a group including glycol ether ester, glycol ether, ester, ketone, and cyclic ester.

Description

Positive photoresist composition {A POSITIVE PHOTORESIST COMPOSITION}

The present invention relates to a positive photoresist composition, and more particularly, can be used in the manufacturing process of semiconductors and liquid crystal display devices, and has excellent sensitivity and pattern shape, excellent semi-exposed residual film uniformity, and improved residual film ratio after development. It relates to a photoresist composition.

Generally, a positive photoresist composition is suitable for a composition containing a binder resin soluble in an alkaline developer such as a resol or cresol novolak resin and a dissolution inhibitor having a quinonediazide group. 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, currently used photoresist compositions generally have poor pattern shapes. In addition, the semi-exposure part remaining film uniformity is not good, if the wet wet after coating, exposure, development after development, there is a disadvantage that the metal film or the substrate of the substrate is damaged.

In order to overcome the above-mentioned problem, it is necessary to shape the pattern shape close to the vertical and to improve the semi-exposed part residual film uniformity. In order to shape the pattern close to vertical, there is a method of adding a photosensitive agent containing a large amount of a photosensitive member to the photoresist. 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 method is a good way to shape the pattern shape of the positive photoresist close to the vertical, but slows the sensitivity of the photoresist. In addition, the development speed of the non-exposure region in which the pattern remains 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 provide a positive photoresist composition capable of shaping the shape of the pattern close to vertical in order to solve the problem of damage to the substrate and the metal film during the dry etching of the four mask process.

It is also an object of the present invention to provide a positive photoresist composition which is excellent in semi-exposure residual film uniformity, and can improve adhesion with a lower substrate, high sensitivity, chemical resistance, strip properties, and residual film ratio.

The present invention is an alkali-soluble resin; Photosensitizers; An additive comprising a compound represented by the formula (1); And it provides a positive photoresist composition comprising a solvent.

<Formula 1>

In Formula 1, R ₁ , R _2, and R ₃ are each independently H or a group represented by Formula 2 below.

<Formula 2>

The positive photoresist composition of the present invention can shape the shape of the pattern close to the vertical, thereby solving the problem of damage to the substrate and the metal film during the dry etching of the four-sheet mask process.

In addition, the positive photoresist composition of the present invention has excellent semi-exposure residual film uniformity, and can improve adhesion to the lower substrate, high sensitivity, chemical resistance, strip characteristics, and residual film ratio.

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 photosensitizer, an additive and a solvent.

It is preferable that alkali-soluble resin contained in the positive photoresist composition of this invention is contained in 10 to 25weight% with respect to the total amount of a composition. If less than the above-described range may cause a problem that the pattern formation is not good. If the above range is exceeded, sensitivity may be slowed, scum may occur, and appropriate sensitivity may be slowed, thereby causing problems in throughput.

The alkali-soluble resin is not particularly limited, and those known in the art may be used. It is preferable to use a novolak resin as said alkali-soluble 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 2-t-butylphenol, 2-naphthol, 1, 3- dihydroxy naphthalene, 1, 7- dihydroxy naphthalene, 1, 5- dihydroxy naphthalene, etc. are 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 , 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 on 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.

The photosensitive agent included in the positive photoresist composition of the present invention is preferably included in 1 to 10% by weight based on the total weight of the composition. If it is less than the above-mentioned range, a pattern will not be formed and the problem that a resist melt | dissolves most occurs. If the above range is exceeded, scums and the like may exist between the patterns.

It is preferable to use the ester compound of the phenolic compound which has a hydroxyl group, and the quinonediazide sulfonic-acid compound. 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 a 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.

Additives included in the positive photoresist composition of the present invention includes a compound represented by the following formula (1). The compound represented by the following Chemical Formula 1 forms a pattern shape close to the vertical, and improves the semi-exposed part residual film uniformity.

<Formula 1>

In Formula 1, R ₁ , R _2, and R ₃ are each independently H or a group represented by Formula 2 below.

<Formula 2>

The additive is preferably included in an amount of 0.01 to 10% by weight, and more preferably 0.1 to 8% by weight based on the total weight of the composition. If included within the above-described range, it is difficult to implement the pattern shape vertically. When it exceeds the above-mentioned range, a sensitivity characteristic will fall and scum will generate | occur | produce.

The additive may further include a low molecular weight phenol 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 the alkali-soluble resin, photosensitive agent, and additives, and causes 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 esters such as γ-butyrol acetone, ethyl lactate, and the like. 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 130 ° 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 novolak resin having a weight average molecular weight of 7,000. 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 novolak resin having a weight average molecular weight of 8,000. Hereinafter, this novolak resin is called A-2.

Example 1, Example 2, Comparative Example 1 and Comparative Example 2: Preparation of Positive Photoresist Composition

A positive photoresist composition was prepared by mixing a novolak resin, a photosensitive agent, a compound represented by Chemical Formula 1, a low molecular weight phenolic compound, and a surfactant with a solvent as described in Table 1 below. 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) Photosensitizer
(Parts by weight) Formula 1
compound
(Parts by weight) Low molecular weight
Phenolic Compound
(Parts by weight) Interface
Active agent
(Parts by weight) menstruum
(Parts by weight) Example 1 A-1 / A-2 12/8 = 20 B-1 4 B-2 3 C-1 4 D-1 0.2 E-1 / E-2 30 / 35.8 = 65.8 Example 2 A-1 / A-2 12/8 = 20 B-1 3 B-2 4 C-1 4 D-1 0.2 E-1 / E-2 30 / 35.8 = 65.8 Comparative Example 1 A-1 / A-2 12/8 = 20 B-1 7 B-2 - C-1 4 D-1 0.2 E-1 / E-2 30 / 35.8 = 65.8 Comparative Example 2 A-1 / A-2 12/8 = 20 B-1 - B-2 7 C-1 4 D-1 0.2 E-1 / E-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 having a reaction molar ratio of 1: 2.2 Condensate of 1,2-naphthoquinonediazide 5-sulfonyl chloride (powder form)

B-2: In the formula (1), R ₁ is H, and R ₂ and R ₃ are groups represented by the formula (2).

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

E-1: Propylene Glycol Monomethyl Ether Acetate (PGMEA)

E-2: ethyl lactate (EL)

Test Example: Evaluation of Characteristics of Positive Photoresist Composition

Example 1, Example 2, Comparative Example 1 and Comparative Example 2 were filtered through a fluororesin filter to obtain a resist solution. The resist solutions were spin-coated on a copper sputtered glass wafer and pre-baked at 110 ° 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 visually observed with a scanning electron microscope to show the resist patterns formed in the Examples and Comparative Examples 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.

<Remaining rate after development>

Ratio of residual film thickness after development to resist film thickness before development

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

<Effectiveness>

Exposure dose in msec when the cross section of a 3.0 µm line-and-space pattern is 1: 1

<Verticality of pattern>

Observed developed pattern under scanning electron microscope

Semi-exposure residual film uniformity

The UV irradiation time was the same as the effective sensitivity, and UV irradiation was carried out using a 20% transmittance mask, followed by a puddle development for 60 seconds using a 2.38% aqueous tetramethylammonium hydroxide solution.

Residual film uniformity = average residual film thickness of the semi-exposed portion-residual film thickness at an arbitrary position

Post-development residual rate (%) Effective Sensitivity (msec) Semi-exposure residual film uniformity Example 1 98 60 1000 to 2000 Example 2 99 60 1500-2600 Comparative Example 1 97 60 4000-5500 Comparative Example 2 96 60 3000-4300

Referring to Table 2 and FIGS. 1 to 4, the resist pattern prepared from the composition of Example 1 and Example 2, in which the compound of Formula 1 was added to the resist, the semi-exposed portion remaining film was formed from the pattern of Comparative Example 1 and Comparative Example 2. Uniformity and pattern perpendicularity were excellent.

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 Comparative Example 1.

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

Claims (5)

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

In Formula 1, R ₁ , R _2, and R ₃ are each independently H or a group represented by Formula 2 below. <Formula 2>

The method according to claim 1, Regarding the total weight of the composition, 10 to 25% by weight of the alkali-soluble resin; 1 to 10% by weight of the photosensitizer; 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 alkali soluble resin is a novolak resin, characterized in that the positive photoresist composition. The method according to claim 1, The photosensitive agent 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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