KR20090069875A - Salt for controlling acid-diffusion and photoresist composition including the same - Google Patents

Abstract

A salt for the acid diffusion adjustment, and a photoresist composition containing the salt are provided to adjust the diffusion of an acid generated at the exposure part, thereby enhancing the contrast at the boundary of the exposure part and the unexposure part. A salt for the acid diffusion adjustment is one component constituting a photoresist composition and is represented by the formula 1, wherein R1 is a carbonyl group (-CO-), an alkyl group of the carbon number 1 ~ 10 or an alkylcarbonyl group; R2 and R3 are independently a hydrogen atom, -OH, or an alkyl group of the carbon number 1 ~ 10; and R- is an anion of a strong acid.

Description

Salt for controlling acid-diffusion and photoresist composition including the same}

The present invention relates to an acid-diffusion adjusting salt and a photoresist composition comprising the same, and more particularly, to an acid-diffusion adjusting salt, which can control diffusion of an acid generated in an exposed portion of a photolithography process. And a photoresist composition comprising the same.

In order to manufacture a semiconductor chip or a display element by processing a semiconductor wafer or display glass, a circuit structure of a predetermined pattern must be formed by using a photolithography process. The photosensitive material used in the photolithography process is called a photoresist composition. Recently, as the circuit pattern of a semiconductor or a display device is miniaturized, a photoresist composition having a high resolution is required.

Conventional chemically amplified photoresist compositions include photoresist polymers, photoacid generators (PAGs), organic solvents and basic compounds. In such a chemically amplified photoresist, when a predetermined pattern of light from an exposure source is irradiated onto the photoresist composition, an acid component is generated in the exposed photoacid generator, and a protecting group bonded to the photoresist polymer by the generated acid is chained. Decomposition, and the solubility of the photoresist polymer is changed. Thus, after changing the solubility of a photoresist film according to an exposure pattern, and developing a photoresist film, a desired photoresist pattern can be formed. In such a photolithography process, a post exposure bake (PEB) process is usually performed to activate and diffuse an acid component present in the exposed photoresist. In addition, in order to control the diffusion of the acid component, a basic compound may be added to the photoresist composition.

In addition, as the formation of the fine photoresist pattern having a line width of 60 nm or less is required, the sidewall roughness and the line edge roughness (LER) of the photoresist pattern are reduced, and the contrast between the exposed portion and the non-exposed portion boundary is reduced. Research to improve the contrast is being conducted in various fields. In order to improve the contrast between the exposed portion and the non-exposed portion, smooth interaction of photoresist polymers, photoacid generators, basic compounds, and the like must be performed. Therefore, these actions are effectively assisted to improve the contrast between the exposed portion and the non-exposed portion. The development of additives that can be made is required.

An object of the present invention is to provide an acid-diffusion salt (Salt) and a photoresist composition comprising the same, which can control the diffusion of acid generated in the exposed portion of the photolithography process.

Another object of the present invention is to provide an acid-diffusion adjusting salt and a photoresist composition comprising the same, which can improve contrast at the exposed and non-exposed interface, thereby improving sidewall roughness and line edge roughness of the photoresist pattern. It is.

In order to achieve the above object, the present invention, as one of the components constituting the photoresist composition, provides an acid-diffusion control salt represented by the following formula (1).

 [Formula 1]

In Formula 1, R ₁ is a carbonyl group (-CO-) or an alkyl group or alkylcarbonyl group having 1 to 10 carbon atoms, R ₂ and R ₃ are each independently a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, R ⁻ represents an anion of a strong acid.

In addition, the present invention is an acid-diffusion adjusting salt represented by the formula (1) of 0.01 to 10% by weight based on the total photoresist composition; 0.05 to 20 parts by weight of the photoacid generator based on 100 parts by weight of the photosensitive compound; And it provides a photoresist composition comprising the remaining organic solvent. In addition, the present invention comprises the steps of: a) applying the photoresist composition on the substrate to form a photoresist film; b) exposing the photoresist film in a predetermined pattern; And c) heating the exposed photoresist film after exposure; And d) developing the heated photoresist film to obtain a pattern.

The salt for acid-diffusion control according to the present invention effectively controls the diffusion of acid generated in the exposed portion of the photolithography process to improve the contrast at the interface between the exposed portion and the non-exposed portion, and the sidewall roughness and line of the photoresist pattern. Edge roughness can be improved. In addition, the acid-diffusion adjusting salt according to the present invention has an effect of increasing the activation of the acid in a region where the distribution of the acid is small, so that the acid is uniformly distributed throughout.

Hereinafter, the present invention will be described in detail.

The salt for acid-diffusion control according to the present invention is a salt having a strong acid generated from a photoacid generator and a salt group, and is represented by the following Chemical Formula 1.

In Formula 1, R ₁ is a carbonyl group (-CO-) or an alkyl group or alkylcarbonyl group having 1 to 10, preferably 1 to 5 carbon atoms, R ₂ and R ₃ are each independently a hydrogen atom, a hydroxy group, It is a C1-C10, preferably C1-C5 alkyl group, and R <^-> represents the anion of a strong acid.

,

,

,

,

,

,

,

,

,

등을 예시할 수 있다.If necessary, R ₁ , R ₂ and / or R ₃ may be connected to each other to form a mono-cyclic or multi-cyclic ring structure, preferably, R ₂ and R ₃ may be connected to each other to form a piperidine structure, or R ₂ and R ₁ may be connected to each other to form a piperidine structure, and R ⁻ may be an anion generated from a photoacid generator. Preferably, more preferably,

,

,

,

,

,

,

,

,

,

Etc. can be illustrated.

Representative examples of the acid-diffusion control salt compound represented by Chemical Formula 1 are as follows.

(화학식 2a),

(화학식 2b),

(Formula 2a),

(Formula 2b),

(화학식 2c),

(화학식 2d),

(Formula 2c),

(Formula 2d),

(화학식 2e),

(화학식 2f),

(Formula 2e),

(Formula 2f),

(화학식 2g),

(화학식 2h),

(Formula 2g),

(Formula 2h),

(화학식 2i),

(화학식 2j),

(Formula 2i),

(Formula 2j),

(화학식 2k),

(화학식 2l)

(Formula 2k),

Formula 2l

The salt for acid-diffusion control according to the present invention is a salt in the form of a combination of a strong acid and a base generated from a photoacid generator, and has the performance of an acid and a base at the same time. I can regulate it.

Acid-diffusion control salts according to the invention can be prepared by a variety of conventional organic synthesis methods. For example, as shown in the following Schemes 1 to 3, when the basic compound and the anion substance of the photoacid generator are mixed in an aqueous solution at room temperature, the acid-diffusion control salt according to the present invention is formed by acid-base neutralization reaction. Is generated. The salt thus produced is purified several times with an organic solvent such as ethyl acetate (EA) and dried to obtain a salt for acid-diffusion control in solid form.

The photoresist composition according to the present invention includes an acid-diffusion adjusting salt, a photosensitive compound, a photoacid generator, and an organic solvent represented by Chemical Formula 1, and, as necessary, a basic compound, a surfactant, etc. as a resist stabilizer. It may further include. In the photoresist composition according to the present invention, the amount of the acid-diffusion adjusting salt represented by Formula 1 is 0.01 to 10% by weight, preferably 0.1 to 5% by weight, more preferably 0.1 to the total photoresist composition. To 3% by weight. Here, if the content of the acid-diffusion control salt represented by the formula (1) is too small, there is a concern that the resolution of the photoresist pattern, the improvement of the lie-edge roughness, etc. may not be enough, if the content of the basic compound is too high, the resolution Not only improves further, but the photoresist pattern may be deformed or defects may occur in the photoresist pattern.

In the photoresist composition of the present invention, as the photosensitive compound, a conventional photoresist polymer, a photosensitive monomolecular compound, and the like, which react with an acid and change in solubility in a developer, can be used without limitation. The photoresist polymer may be a block copolymer or a random copolymer having an acid sensitive protecting group, and the weight average molecular weight (Mw) is preferably 3,000 to 20,000. The content of the photosensitive compound is preferably 1 to 30% by weight, more preferably 1 to 20% by weight based on the total photoresist composition. If the content of the photoresist polymer is less than 1% by weight, the resist layer remaining after coating is too thin to form a pattern having a desired thickness, and if it exceeds 30% by weight, coating uniformity may be degraded.

The photoacid generator generates acid by exposure, deprotects the protecting group of the photoresist polymer, or converts the structure of the basic compound, and may generate acid by light. Any compound may be used as long as the compound is present. Preferably, sulfide salt compounds such as organic sulfonic acid, onium salt compounds such as onium salt, and the like may be used alone or in combination. Non-limiting examples of the photoacid generator include phthalimidotrifluoromethane sulfonate, dinitrobenzyl tosylate, n-decyl disulfone, naphthylimidotrifluoro Rhomethanesulfonate (naphthylimido trifluoromethane sulfonate), diphenylureta hexafluorophosphate, diphenylureate hexafluoroarsenate, diphenylureate hexafluoroantimonate, diphenylparamethoxyphenylsulfonium triflate, diphenylparamethoxyphenylsulfonium triflate Phenylparatoluenylsulfonium triflate, diphenylparaisobutylphenylsulfonium triflate, triphenylsulfonium hexafluoroarsenate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium triflate, di Butyl naphthyl sulfonium triflate, a triphenylsulfonium nona plate, a mixture thereof, etc. can be illustrated. The content of the photoacid generator is preferably 0.05 to 20 parts by weight, and more preferably 0.1 to 10 parts by weight based on 100 parts by weight of the photosensitive compound. If the content of the photoacid generator is less than 0.05 part by weight, the sensitivity to light of the photoresist composition may be lowered, thereby making it difficult to deprotect the protecting group or to convert the structure of the basic compound. There is a possibility that a large amount of acid is generated in the cross section of the resist pattern to be poor.

As the organic solvent constituting the remaining components of the photoresist composition according to the present invention can be used a wide variety of organic solvents commonly used in the preparation of the photoresist composition, non-limiting examples, ethylene glycol monomethylethyl, ethylene Glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoethyl ether, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol, propylene glycol monoacetate, toluene, xylene, Methyl ethyl ketone, methyl isoamyl ketone, cyclohexanone, dioxane, methyl lactate, ethyl lactate, methyl pyruvate, ethyl pyruvate, methyl methoxy propionate, ethyl ethoxy propionate, N, N Dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 3-e Ethyl ethyl propionate, 2-heptanone, gamma-butyrolactone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy 2-methylpropionate, ethyl ethoxy acetate, ethyl hydroxy acetate, 2-hydroxy 3- Methyl methyl butyrate, methyl 3-methoxy 2-methylpropionate, ethyl 3-ethoxy propionate, ethyl 3-methoxy 2-methylpropionate, ethyl acetate, butyl acetate, and mixtures thereof. The content of the organic solvent is preferably 300 to 5000 parts by weight based on 100 parts by weight of the total photosensitive compound. If the content of the organic solvent is out of the above range, there is a fear that the photoresist film forming process may not be performed smoothly.

In addition, to control acid diffusion, triethylamine, trioctylamine, triisobutylamine, triisooctylamine, diethanolamine, triethanol, which are commonly used in photoresist compositions, when conventional basic compounds are used Organic bases such as amines and mixtures thereof can be used. It is preferable that the usage-amount of the said basic compound is 0.01 to 10 weight% with respect to the whole photoresist composition. The surfactant contained in the photoresist composition according to the present invention as needed is added for the purpose of improving the uniform mixing of the photoresist composition components, the coatability of the photoresist composition, the developability after exposure of the photoresist film, and the like. As such a surfactant, conventional surfactants used in the photoresist composition can be used without limitation, for example, fluorine-based surfactants, fluorine-silicone-based surfactants and the like can be used. The amount of the surfactant used is 0.001 to 2 parts by weight, preferably 0.01 to 1 part by weight based on 100 parts by weight of the solid content of the photoresist composition, and when the amount is too small, the function as a surfactant cannot be sufficiently expressed. In addition, too much may adversely affect resist characteristics other than applicability | paintability, such as shape stability and storage stability of a composition.

In order to form a photoresist pattern using the photoresist composition of the present invention, (a) first, a photoresist composition is coated on a substrate such as a silicon wafer or an aluminum substrate using a spin coater, and the photoresist. A film is formed, (b) the photoresist film is exposed in a predetermined pattern, (c) the post exposure bake (PEB) is exposed, and (d) the heated photoresist film is developed to develop a pattern. To obtain a conventional photolithography process. The exposure process includes ArF (193 nm), KrF (248 nm), F ₂ (157 nm), EUV (Extreme Ultra Violet, 13.5 nm), VUV (Vacuum Ultra Violet), E-beam, X-ray, immersion It may be performed using lithography (Immersion lithography) or ion beam. In addition, as the developer used in the developing step, an alkaline aqueous solution in which alkaline compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate and tetramethylammonium hydroxide (TMAH) are dissolved at a concentration of 0.1 to 10% by weight may be used. In accordance with the present invention, an appropriate amount of a water-soluble organic solvent such as methanol or ethanol and a surfactant may be added to the developer. In addition, after the development process, the cleaning process for cleaning the substrate with ultrapure water may be further performed.

Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples. The following examples are intended to illustrate the present invention more specifically, but the present invention is not limited by the following examples.

Example 1-1 to 1-12 Synthesis of Acid-Diffusion Control Salts

The basic compound and acid material (anionic material) constituting the acid-diffusion control salt represented by Formulas 2a to 2l are each made into an aqueous solution having a concentration of 30% by weight, and then, at room temperature, each of the basic compound and acid material is equivalent to 1 equivalent. By mixing and stirring for 2 hours, an exothermic process gave a salt substance dissolved in water. After completion of the reaction, the reaction solution was dried in vacuo to remove water to obtain a salt in solid form, and the salt in solid form was recovered with ethyl acetate (EA) of 7 times (weight ratio) based on the amount of solids obtained. It was dissolved, filtered through a filter paper to remove impurities, and then dried in vacuo to give a salt in purified solid form. This purification process was repeated three times. The amount and yield of the raw material used to prepare the acid-diffusion control salt are shown in Table 1 below.

Example salt substance Basic compound Acid substance yield Kinds Input amount (g) Kinds Input amount (g) Weight (g) % One Formula 2a Formula 3a 18.32 Formula 4a 42.9 19.4 31.7% 2 Formula 2b Formula 3a 18.32 Formula 4b 58.9 25.4 32.9% 3 Formula 2c Formula 3a 18.32 Formula 4c 41.9 22.1 36.7% 4 Formula 2d Formula 3a 18.32 Formula 4d 83.0 35.4 34.9% 5 Formula 2e Formula 3b 18.31 Formula 4a 42.9 20.4 33.3% 6 Formula 2f Formula 3b 18.31 Formula 4b 58.9 28.2 36.5% 7 Formula 2g Formula 3b 18.31 Formula 4c 41.9 22.1 36.7% 8 Formula 2h Formula 3b 18.31 Formula 4d 83.0 38.4 37.9% 9 Formula 2i Formula 3c 18.31 Formula 4a 42.9 20.4 33.3% 10 Formula 2j Formula 3c 18.31 Formula 4b 58.9 30.1 39.0% 11 Formula 2k Formula 3c 18.31 Formula 4c 41.9 25.4 42.2% 12 Formula 2l Formula 3c 18.31 Formula 4d 83.0 36.2 35.7%

(분자량: 128.22), 화학식 3b는

(분자량: 128.17), 화학식 3c는

(분자량: 128.17), 화학식 4a는

(분자량: 300.1), 화학식 4b는

(분자량: 412.23), 화학식 4c는

(분자량: 293.16), 화학식 4d는

(분자량: 412.23)를 나타낸다.In Table 1, Formula 3a is

(Molecular weight: 128.22), Formula 3b is

(Molecular weight: 128.17), Formula 3c

(Molecular weight: 128.17), Formula 4a is

(Molecular weight: 300.1), Formula 4b is

(Molecular weight: 412.23), Formula 4c

(Molecular weight: 293.16), the chemical formula 4d

(Molecular weight: 412.23) is indicated.

[Examples 2-1 to 2-12, Comparative Example 1] Preparation of Photoresist Composition and Formation of Pattern

10% by weight of the photoresist polymer (a / b / c = 40/40/20, unit: mol%) represented by Chemical Formula 5 to confirm the effect of improving the line edge roughness (LER) of the salt for acid-diffusion control, 3.5 parts by weight of triphenylsulfonium nonaplate (TPS-NF) based on 100 parts by weight of the polymer, 0.2% by weight of trioctylamine (TOA) as a basic compound and propylene glycol monomethyl ether acetate (PGMEA) as the remaining solvent Using to prepare a photoresist composition. Here, 0.5 parts by weight and 1 part by weight of the acid-diffusion adjusting salts prepared in Examples 1-1 to 1-12 were added to 100 parts by weight of the polymer, respectively. After coating the prepared photoresist composition on a substrate with a thickness of 2700Å, using a ASML 1100 equipment (0.75 NA), a 1: 1 line / space (L / S) pattern having a line width of 90nm was formed (SOB, PEB = 120 ° C./60 seconds), at which time the LER value was measured using Hitachi SEM (S8820), and the results are shown in Table 2 (Examples 2-1 to 2-12). In addition, the same experiment was performed without adding the acid-diffusion adjusting salt, and the LER value was measured, and the results are shown together in Table 2 (Comparative Example 1).

Acid-Diffusion Control Salts Usage (part by weight) LER value (nm) Pattern shape Comparative Example 1 none none 9.8 right angle Example 2-1 Formula 2a 0.5 5.4 right angle Example 2-1 Formula 2a One 4.3 right angle Example 2-2 Formula 2b 0.5 6.2 right angle Example 2-2 Formula 2b One 5.8 right angle Example 2-3 Formula 2c 0.5 6.6 right angle Example 2-3 Formula 2c One 6.0 right angle Example 2-4 Formula 2d 0.5 6.4 right angle Example 2-4 Formula 2d One 6.1 right angle Example 2-5 Formula 2e 0.5 5.0 right angle Example 2-5 Formula 2e One 4.2 right angle Example 2-6 Formula 2f 0.5 6.2 right angle Example 2-6 Formula 2f One 5.9 right angle Example 2-7 Formula 2g 0.5 6.7 right angle Example 2-7 Formula 2g One 5.9 right angle Example 2-8 Formula 2h 0.5 6.6 right angle Example 2-8 Formula 2h One 6.0 right angle Example 2-9 Formula 2i 0.5 4.5 right angle Example 2-9 Formula 2i One 4.0 right angle Example 2-10 Formula 2j 0.5 5.8 right angle Example 2-10 Formula 2j One 5.2 right angle Example 2-11 Formula 2k 0.5 6.0 right angle Example 2-11 Formula 2k One 5.7 right angle Example 2-12 Formula 2l 0.5 6.2 right angle Example 2-12 Formula 2l One 5.4 right angle

From Table 2, it can be seen that when using the acid-diffusion control salt according to the present invention, the LER can be effectively improved, and the shape of the pattern is formed into a rectangle.

Claims (6)

An acid-diffusion adjusting salt represented by the following Chemical Formula 1 as one of the components constituting the photoresist composition.  [Formula 1]

In Formula 1, R ₁ is a carbonyl group (-CO-) or an alkyl group or alkylcarbonyl group having 1 to 10 carbon atoms, R ₂ and R ₃ are each independently a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, R ⁻ represents an anion of a strong acid. The salt of claim 1, wherein R ₁ , R ₂ and / or R ₃ are linked to each other to form a monocyclic or polycyclic ring structure. The salt of claim 1, wherein R ₂ and R ₃ or R ₁ are connected to each other to form a piperidine structure. According to claim 1, wherein the acid-diffusion control salt,

(Formula 2a),

(Formula 2b),

(Formula 2c),

(Formula 2d),

(Formula 2e),

(Formula 2f),

(Formula 2g),

(Formula 2h),

(Formula 2i),

(Formula 2j),

(Formula 2k), and

Acid-diffusion control salt is selected from the group consisting of (Formula 2l). 0.01 to 10% by weight of the acid-diffusion adjusting salt represented by the following Chemical Formula 1, based on the total photoresist composition, [Formula 1]

In Formula 1, R ₁ is a carbonyl group (-CO-) or an alkyl group or alkylcarbonyl group having 1 to 10 carbon atoms, R ₂ and R ₃ are each independently a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, R- represents an anion of a strong acid; 1 to 30% by weight of the photosensitive compound based on the total photoresist composition; 0.05 to 20 parts by weight of the photoacid generator based on 100 parts by weight of the photosensitive compound; And Photoresist composition comprising the remaining organic solvent. a) 0.01 to 10% by weight of the acid-diffusion adjusting salt represented by the following Chemical Formula 1, based on the total photoresist composition, 1 to 30% by weight of the total photoresist composition; 0.05 to 20 parts by weight of the photoacid generator based on 100 parts by weight of the photosensitive compound; And applying a photoresist composition including the remaining organic solvent on the substrate to form a photoresist film. [Formula 1]

In Formula 1, R ₁ is a carbonyl group (-CO-) or an alkyl group or alkylcarbonyl group having 1 to 10 carbon atoms, R ₂ and R ₃ are each independently a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, R- represents an anion of a strong acid; b) exposing the photoresist film in a predetermined pattern; And c) heating the exposed photoresist film after exposure; And d) developing the heated photoresist film to obtain a pattern.