An additive for 193nm wet photoresist, its preparation method and application

Abstract

The present invention discloses an additive for 193 nm wet photoresist, its preparation method and application. Specifically, an additive as shown in Formula I is disclosed; the weight-average molecular weight of the additive is 1000-3000; the ratio of the weight-average molecular weight to the number-average molecular weight of the additive is 1-5. The additive of the present invention has at least the following advantages: the photoresist containing the additive can improve the problem of material leaching in water during the immersion lithography exposure process, so that a photoresist film micropattern with excellent sensitivity and high resolution can be formed.

Description

Technical Field

[0001] The present invention relates to an additive for 193 nm wet photoresist, a preparation method thereof, and an application thereof. Background Art

[0002] With the higher integration and higher speed of large-scale integrated circuits (LSIs) in recent years, accurate micropatterning of photoresists is required. As an exposure light source used in forming a resist pattern, an ArF light source (193 nm) or a KrF light source (248 nm) has been widely used.

[0003] In an ArF immersion lithography method using an ArF excimer laser as a light source, the space between a projection lens and a wafer substrate is filled with water. According to this method, even when using a lens with an NA of more than 1.0, a pattern can be formed by using the refractive index of water at 193 nm, and this method is generally referred to as an immersion lithography method. However, since the photoresist film is directly in contact with water, the photoresist pattern may be deformed or may collapse due to swelling, or various defects such as bubbles and watermarks may be generated. Therefore, it is urgent to develop a photoresist resin or an additive that can improve this situation. Summary of the Invention

[0004] Aiming at the above problems existing in the prior art, the present invention aims to provide an additive for 193 nm wet photoresist, a preparation method thereof, and an application thereof. The additive of the present invention has at least the following advantages: the photoresist containing this additive can improve the problem of material leaching in water during the immersion lithography exposure process, so that a micropattern of a photoresist film with excellent sensitivity and high resolution can be formed.

[0005] The present invention provides an additive represented by Formula I; the weight-average molecular weight of the additive is 1000 - 3000, preferably 1500 - 2500, more preferably 2010; the ratio of the weight-average molecular weight to the number-average molecular weight of the additive is 1 - 5, preferably 1 - 2, more preferably 1.3;

[0006]

[0007] In a certain embodiment, the preparation method of the additive includes the following steps:

[0008] S1: In an organic solvent, subject compound B1 to an acetal reaction with dimethyl L-tartrate and p-toluenesulfonic acid to obtain compound C1 (dicyclopentadienone-L-tartaric acid diethyl ester); compound B1 is

[0009] S2: In a solvent, subject compound C1 to an ester hydrolysis reaction under the action of a base to obtain compound D1 (dicyclopentadienone-L-tartaric acid).

[0010] S3: In an organic solvent, polymerize the compound D1 with 4-dimethylaminopyridine to obtain the additive shown in Formula I.

[0011] In S1, the organic solvent can be a conventional organic solvent for this type of reaction in the art, preferably an aromatic solvent, such as toluene.

[0012] In S1, the molar ratio of the compound B1 to the dimethyl L-tartrate can be conventional for this type of reaction in the art, preferably 1:(1 - 1.5), such as 1:1.

[0013] In S1, the molar ratio of the compound B1 to the p-toluenesulfonic acid can be conventional for this type of reaction in the art, preferably 1:(20 - 60), such as 1:34.5.

[0014] In S1, the post-treatment step of the acetal reaction can be a conventional post-treatment step in the art, preferably including operations such as washing, drying, filtering, and removing the solvent. The solvent for washing can be conventional for this type of reaction in the art, preferably washing successively with an aqueous sodium bicarbonate solution, water, and brine. The drying is preferably carried out with magnesium sulfate.

[0015] In S1, the reaction time of the acetal reaction is based on the complete reaction of the reactants, preferably 26 hours to 60 hours, such as 48 hours.

[0016] In S1, the temperature of the acetal reaction is preferably the reflux temperature of the solvent at normal temperature and pressure.

[0017] In S2, the solvent can be a conventional solvent for this type of reaction in the art, preferably a ketone solvent, such as N-methylpyrrolidone.

[0018] In S2, the base can be a conventional base for this type of reaction in the art, preferably an inorganic base, such as potassium hydroxide and / or sodium hydroxide, preferably potassium hydroxide.

[0019] In S2, the molar volume ratio of the compound C1 to the solvent can be conventional for this type of reaction in the art, preferably 0.1 - 0.7 mol / L, such as 0.5 mol / L.

[0020] In S2, the base preferably participates in the reaction in the form of an aqueous base solution. The mass ratio of the base to water is preferably 0.1:1 - 0.6:1, such as 0.3:1.

[0021] After the ester hydrolysis reaction in S2, a post-treatment step can also be included. The post-treatment step can be conventional for this type of reaction in the art, for example, including operations such as neutralization and purification. The purification step preferably uses column chromatography, and more preferably ethyl acetate is used as the eluent in the column chromatography.

[0022] In S2, the time of the ester hydrolysis reaction is determined by the cessation of the reaction, preferably 3 to 15 hours, such as 6 hours.

[0023] In S2, the temperature of the ester hydrolysis reaction is preferably the reflux temperature of the solvent at normal temperature and pressure.

[0024] In S3, the organic solvent can be a commonly used organic solvent in this type of reaction in the art, preferably an acid anhydride solvent, such as acetic anhydride.

[0025] In S3, the molar ratio of 4-dimethylaminopyridine to compound D1 can be conventional in this type of reaction in the art, preferably 1:0.9 to 1.5, such as 1:1.3.

[0026] In S3, the molar ratio of the organic solvent to compound D1 can be conventional in this type of reaction in the art, preferably 3:1 to 7:1, such as 5:1.

[0027] In S3, the time of the polymerization reaction is determined by the cessation of the reaction, preferably 3 to 15 hours, such as 6 hours.

[0028] In S3, the temperature of the polymerization reaction can be conventional in this type of reaction in the art, preferably 100 to 200 °C, such as 130 °C to 190 °C.

[0029] In S3, the temperature of the polymerization reaction is preferably to react at 130 °C first and then raise the temperature to 190 °C.

[0030] In S3, the polymerization reaction may further include a post-treatment step. The post-treatment step can be conventional in this type of reaction in the art, preferably including operations of dissolution and purification.

[0031] The present invention also provides a preparation method of an additive, and the preparation method of the additive is as described above.

[0032] The present invention also provides a photoresist, which comprises the following raw materials: the additive shown in formula I as described above, a resin shown in formula (L), a photoacid generator, and a solvent;

[0033]

[0034] In the photoresist, the parts by weight of the photoacid generator can be conventional in this type of reaction in the art, preferably 2 to 10 parts, such as 4 parts.

[0035] In the photoresist, the photoacid generator can be conventional in this type of reaction in the art, preferably a sulfonium salt, such as

[0036] In the photoresist described above, the weight-average molecular weight of the resin represented by formula (L) may be conventional in this type of reaction in the art, preferably 8,000 - 9,000, such as 8,500.

[0037] In the photoresist described above, the parts by weight of the resin represented by formula (L) may be conventional in this type of reaction in the art, preferably 20 - 120 parts, such as 100 parts.

[0038] In the photoresist described above, the parts by weight of the additive represented by formula I may be conventional in this type of reaction in the art, preferably 0.1 - 1 part, such as 0.5 part.

[0039] In the photoresist described above, the parts by weight of the solvent may be conventional in this type of reaction in the art, preferably 500 - 2,000 parts, such as 1,000 parts.

[0040] In the photoresist described above, the solvent may be conventional in this type of reaction in the art, preferably an ester solvent, such as propylene glycol monomethyl ether acetate.

[0041] The photoresist described above comprises the following raw materials by weight: 4 parts of a photoacid generator, 100 parts of the resin represented by formula (L), 0.5 part of the additive represented by formula I above, and 1,000 parts of a solvent.

[0042] The photoresist described above is composed of the following raw materials: the compound represented by formula I, the resin, the photoacid generator, and the solvent.

[0043] In the photoresist described above, the resin represented by formula L is prepared by the following method: in an organic solvent, under the action of an initiator, polymerize an unsaturated acid.

[0044] In the photoresist described above, the unsaturated acid may be conventional in this type of reaction in the art, preferably one or more of the following compounds, such as: tert-butyl 3-bicyclo[2.2.1]hept-5-en-2-yl-3-hydroxypropionate, 1-methyladamantyl acrylate, and γ-butyrolactone acrylate.

[0045] In the photoresist described above, the resin represented by formula L is prepared by the following method: dissolve tert-butyl 3-bicyclo[2.2.1]hept-5-en-2-yl-3-hydroxypropionate, 1-methyladamantyl acrylate, and γ-butyrolactone acrylate in 1,4-dioxane, add azobisisobutyronitrile as an initiator, precipitate with n-hexane, and dry.

[0046] The present invention also provides a method for preparing the photoresist described above, which comprises the following steps: in a solvent, mix the resin, the photoacid generator, and the additive represented by formula I uniformly.

[0047] In the described preparation method, the solvent, the resin, the photoacid generator, and the additive shown in Formula I are as described above.

[0048] In the described preparation method, the mixing method can be a conventional mixing method in the art, and shaking is preferred.

[0049] In the described preparation method, after the mixing step, filtration through a filter membrane is preferably further included, for example, filtration through a 0.2 μm filter membrane.

[0050] The present invention also provides an application of the above-mentioned photoresist in a lithography process.

[0051] Among them, the lithography process preferably includes the following steps: coating the photoresist on a pretreated substrate, drying (for example, drying at 110 °C for 90 seconds), exposure, and development (for example, using a developer solution of aqueous tetramethylammonium hydroxide).

[0052] On the basis of conforming to the common knowledge in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain various preferred examples of the present invention.

[0053] In the present invention, normal temperature refers to 10 - 40 °C, and normal pressure refers to 98 kPa - 103 kPa.

[0054] The reagents and raw materials used in the present invention are all commercially available.

[0055] The positive and progressive effects of the present invention are that: the photoresist additive improves the problem of leaching of materials in water during the immersion lithography exposure process, so that a photoresist film micropattern with excellent sensitivity and high resolution can be formed. Specific Embodiments

[0056] The present invention will be further illustrated below by way of examples, but the present invention is not limited to the scope of the described examples. The experimental methods without specific conditions noted in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0057] In the following operations, unless otherwise specified, the temperature and pressure are both carried out at normal temperature and normal pressure.

[0058] Example 1 Preparation of Additive

[0059] 1. Acetal Reaction

[0060] Dimethyl L-tartrate (9.18 g, 1 equivalent, 0.05 mol), Compound B1 (1 equivalent, 0.05 mol) and p-toluenesulfonic acid (250 mg) were refluxed in toluene for 48 h (Dean-Stark water separator, 0.6 mL of water). The solution was cooled and washed with aqueous sodium bicarbonate solution (5%, 2 × 100 mL), water (100 mL) and brine (100 mL). The organic layer was dried (MgSO 4 ), filtered and the solvent was removed under reduced pressure to give compound C1 (dicyclopentadienone-L-tartaric acid diethyl ester) as an anhydrous liquid in 91% yield.

[0061] 2. Ester hydrolysis reaction

[0062] Compound C1 (0.01 mol) prepared in Example 1 was dissolved in a mixture of NMP (20 mL) and 30% aqueous potassium hydroxide solution (potassium hydroxide (3 g), water (10 g)). The reaction mixture was heated to reflux for 6 h, and the mixture was neutralized by slowly adding dilute hydrochloric acid. The product was separated by column chromatography to give compound D1 (dicyclopentadienone-L-tartaric acid). Ethyl acetate was used as the eluent, and the product was a white waxy solid, which could be directly used for the next step.

[0063] 3. Polymerization reaction

[0064] Compound D1 (0.01 mol) prepared in Example 2 and 4-dimethylaminopyridine (12 mg, 0.01 mmol) were dissolved in acetic anhydride (5 g, 0.05 mol). The mixture was stirred at 130 °C for 6 h. Then the temperature was raised to 190 °C and stirred for about 10 h, and then acetic acid was removed under reduced pressure. After cooling to room temperature, the solid product was dissolved in DMSO and purified by precipitation into toluene to give polymer A1 (the additive shown in formula I). The molecular weight Mw detected by GPC was 1970, and Mw / Mn = 1.3.

[0065] Preparation of the resin of Example 2

[0066] tert-Butyl 3-bicyclo[2.2.1]hept-5-en-2-yl-3-hydroxypropionate (hereinafter referred to as BHP), 1-methyladamantyl acrylate and γ-butyrolactone acrylate were added in a molar ratio of 1:1:1. 300 parts by weight of 1,4-dioxane was added as a polymerization reaction solvent relative to 100 parts by weight of the total amount of the reaction monomers, and 4 parts by mole of azobisisobutyronitrile was added as an initiator relative to 100 mole parts of the total amount of the reaction monomers, and the mixture was reacted at 65 °C for 16 h. After the reaction, the reaction solution was precipitated with n-hexane, the precipitate was removed and dried in vacuo. Thus, a resin represented by formula (L) was obtained, and its weight-average molecular weight was about 8500 g / mol.

[0067]

[0068]

[0069] Embodiment of Photoresist Preparation

[0070] Dissolve 100 parts by weight of the resin shown in formula (L), 4 parts by weight of photoacid generator PAGX, and 0.5 parts by weight of the additive shown in formula I in 1000 parts by weight of propylene glycol monomethyl ether acetate, and then filter the solution through a 0.2 μm membrane filter. Thus, the photoresist is prepared.

[0071] Comparative Example 1

[0072] Replace compound B1 in step 1 of Example 1 with compound B2 to obtain compound C2, and successively refer to steps 2 and 3 in Example 1 for ester hydrolysis and polymerization reactions to obtain polymer A2. The molecular weight Mw detected by GPC is 2100, and Mw / Mn = 1.2.

[0073]

[0074] Comparative Example 2

[0075] Replace compound B1 in step 1 of Example 1 with B3 to obtain compound C3, and successively refer to steps 2 and 3 in Example 1 for ester hydrolysis and polymerization reactions to obtain polymer A3. The molecular weight Mw detected by GPC is 1840, and Mw / Mn = 1.0.

[0076]

[0077] Effect Example

[0078] Form an antireflective bottom coating (BARC, AR40A - 900, Rohm and Haas Electronic Materials Co., Ltd.) with a thickness of 90 nm on a silicon substrate, and coat the above-prepared photoresist composition on the substrate with BARC. Bake the substrate at 110 °C for 60 seconds to form a photoresist film with a thickness of 120 nm.

[0079] Develop the silicon substrate with a photoresist film using a 2.38 wt% aqueous solution of trimethylammonium hydroxide (TMAH), and measure the thickness change of each photoresist film before and after development by measuring the thickness of the photoresist film.

[0080] Measure the sliding angle and receding contact angle of the photoresist film respectively.

[0081] Specifically, drop 50 μl of pure water on the silicon substrate with the photoresist film held horizontally to form a droplet. While gradually tilting the silicon substrate, measure the angle (sliding angle) when the droplet starts to slide down and the receding contact angle.

[0082] Then, in order to implement liquid immersion lithography, the exposed photoresist film was washed with pure water for 5 minutes. That is, exposure was performed using an ArF scanner 306C (Nikon Corp., NA = 0.78, 6% halftone mask), and the substrate was washed with pure water for 5 minutes. The exposure was carried out at 110 °C for 60 seconds, PEB was performed, and development was carried out for 60 seconds using a 2.38 wt% TMAH developer.

[0083] The silicon substrate was diced to evaluate the sensitivity. The sensitivity corresponds to the exposure dose used to form a line width and line pitch (line-and-space, L / S) pattern with a line width to line pitch ratio of 1:1 and a line width of 65 nm.

[0084] Table 1

[0085]

[0086] Conclusion: Referring to Table 1, the photoresist film formed using the photoresist containing the additive prepared in the examples has a higher sliding angle and a higher receding contact angle than the photoresist film formed using the photoresist composition prepared in the comparative example. In addition, the photoresist film prepared in the examples has excellent sensitivity after liquid immersion lithography, but the pattern was not formed on the photoresist film formed in the comparative example.

Claims

1. An additive as shown in Formula I; the weight-average molecular weight of the additive is 1000 - 3000; the ratio of the weight-average molecular weight to the number-average molecular weight of the additive is 1 - 5; 2. The additive according to claim 1, wherein, the weight-average molecular weight of the additive is 1500 - 2500; and / or, the ratio of the weight-average molecular weight to the number-average molecular weight of the additive is 1 - 2.

3. The additive according to claim 1, wherein, the preparation method of the additive comprises the following steps: S1: In an organic solvent, react compound B1 with dimethyl L-tartrate and p-toluenesulfonic acid to carry out an acetal reaction to obtain compound C1; the compound B1 is S2: In a solvent, under the action of a base, subject the compound C1 to an ester hydrolysis reaction to obtain the compound D1; S3: In an organic solvent, polymerize the compound D1 with 4-dimethylaminopyridine to obtain the additive as shown in Formula I.

4. The additive according to claim 3, wherein, in S1, the organic solvent is an aromatic hydrocarbon solvent; and / or, in S1, the molar ratio of the compound B1 to the dimethyl L-tartrate is 1:(1 - 1.5); and / or, in S1, the molar ratio of the compound B1 to the p-toluenesulfonic acid is 1:(20 - 60); and / or, in S1, the post-treatment steps of the acetalization reaction include washing, drying, filtering and removing the solvent; and / or, in S1, the reaction time of the acetalization reaction is 26 hours - 60 hours.

5. The additive according to claim 3, wherein, in S2, the solvent is a ketone solvent; and / or, in S2, the base is an inorganic base; and / or, in S2, the molar volume ratio of the compound C1 to the solvent is 0.1 - 0.7 mol / L; and / or, in S2, the base participates in the reaction in the form of an aqueous base solution, and the mass ratio of the base to water is 0.1:1 - 0.6:1; and / or, in S2, after the ester hydrolysis reaction, there are post-treatment steps; the post-treatment steps include neutralization and purification operations; and / or, in S2, the reaction time of the ester hydrolysis reaction is 3 hours - 15 hours.

6. The additive according to claim 3, wherein, in S3, the organic solvent is an acid anhydride solvent; and / or, in S3, the molar ratio of 4-dimethylaminopyridine to the compound D1 is 1:0.9 - 1.5; and / or, in S3, the molar ratio of the organic solvent to the compound D1 is 3:1 - 7:1; and / or, in S3, the reaction time of the polymerization reaction is 3 hours - 15 hours; and / or, in S3, the temperature of the polymerization reaction is 100 - 200 °C; and / or, in S3, the polymerization reaction also includes post-treatment steps.

7. The additive according to any one of claims 4 - 6, wherein, in S1, the organic solvent is toluene; and / or, in S1, the molar ratio of the compound B1 to the dimethyl L-tartrate is 1:1.3; and / or, in S1, the molar ratio of the compound B1 to the p-toluenesulfonic acid is 1:34.5; And / or, in S1, the post-treatment steps of the acetalization reaction include washing, drying, filtration, and solvent removal operations; the solvents for washing are successively washed with an aqueous sodium bicarbonate solution, water, and brine, and the drying is performed with magnesium sulfate. And / or, in S1, the reaction time of the acetalization reaction is 48 hours. And / or, in S2, the solvent is N-methylpyrrolidone. And / or, in S2, the base is potassium hydroxide and / or sodium hydroxide. And / or, in S2, the molar volume ratio of compound C1 to the solvent is 0.5 mol / L. And / or, in S2, the base participates in the reaction in the form of an aqueous base solution, and the mass ratio of the base to water is 0.3:

1. And / or, in S2, after the ester hydrolysis reaction is completed, there are post-treatment steps; the post-treatment steps include neutralization and purification operations; the purification step uses column chromatography. And / or, in S2, the reaction time of the ester hydrolysis reaction is 6 hours. And / or, in S3, the organic solvent is acetic anhydride. And / or, in S3, the molar ratio of 4-dimethylaminopyridine to compound D1 is 1:

1. And / or, in S3, the molar ratio of the organic solvent to compound D1 is 5:

1. And / or, in S3, the reaction time of the polymerization reaction is 6 hours. And / or, in S3, the temperature of the polymerization reaction is 130 °C. And / or, in S3, the polymerization reaction also includes post-treatment steps; the post-treatment steps include dissolution and purification operations.

8. The additive according to any one of claims 4 to 6, wherein, in S1, the temperature of the acetalization reaction is the reflux temperature of the solvent at normal temperature and pressure. And / or, in S2, the base is potassium hydroxide. And / or, in S2, the temperature of the ester hydrolysis reaction is the reflux temperature of the solvent at normal temperature and pressure. And / or, in S2, after the ester hydrolysis reaction is completed, there are post-treatment steps; the post-treatment steps include neutralization and purification operations; the purification step uses column chromatography; ethyl acetate is used as the eluent in the column chromatography. And / or, in S3, the temperature of the polymerization reaction is to first react at 130 °C and then raise the temperature to 190 °C.

9. The additive according to any one of claims 4 to 6, wherein, in S2, after the ester hydrolysis reaction is completed, there are also post-treatment steps; the post-treatment steps include neutralization and purification operations; the purification step uses column chromatography, and ethyl acetate is used as the eluent in the column chromatography.

10. A method for preparing an additive, wherein, the additive as claimed in any one of claims 3 to 9 is prepared.

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