Additive for 193 nm wet photoresist and preparation method and application thereof

Abstract

This invention discloses an additive for 193nm wet photoresist, its preparation method, and its application. Specifically, a photoresist is disclosed, comprising the following raw materials: an additive as shown in Formula I, a resin as shown in Formula (L), a photoacid-generating agent, and a solvent. The weight-average molecular weight of the additive is 1000–3000; the weight-average molecular weight / number-average molecular weight ratio of the additive is 1–5. The photoresist of this invention can improve the problem of material leaching in water during immersion photolithography, thereby enabling the formation of photoresist film micropatterns with excellent sensitivity and high resolution.

Description

Technical Field

[0001] This invention relates to an additive for 193nm wet photoresist, its preparation method, and its application. Background Technology

[0002] With the increasing integration density and speed of large-scale integrated circuits (LSI) in recent years, there is a need for accurate micropatterning of photoresists. ArF light sources (193nm) or KrF light sources (248nm) have been widely used as exposure light sources for forming resist patterns.

[0003] In ArF immersion lithography, which uses an ArF stimulated excimer laser as the light source, the space between the projection lens and the wafer substrate is filled with water. According to this method, even using lenses with a refractive index (NA) greater than 1.0, patterns can be formed using the refractive index of water at 193 nm, and this method is commonly referred to as immersion lithography. However, because the photoresist film is in direct contact with water, the photoresist pattern may deform or collapse due to swelling, or various defects such as bubbles and watermarks may occur. Therefore, there is an urgent need to develop photoresist resins or additives that can improve these conditions. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention aims to provide an additive for 193nm wet photoresist, its preparation method, and its application. The photoresist of this invention can improve the problem of material leaching in water during immersion lithography exposure, thereby enabling the formation of photoresist film micropatterns with excellent sensitivity and high resolution.

[0005] The present invention also provides a photoresist comprising the following raw materials: an additive as shown in Formula I, a resin as shown in Formula (L), a photoacid generator, and a solvent; wherein the weight-average molecular weight of the additive is 1000-3000, preferably 1500-2500, more preferably 2010; and the weight-average molecular weight / number-average molecular weight ratio of the additive is 1-5, preferably 1-2, more preferably 1.3.

[0006]

[0007] The additive shown in Formula I is:

[0008]

[0009] In one embodiment, the method for preparing the additive includes the following steps:

[0010] S1: In an organic solvent, compound B1 is reacted with dimethyl L-tartrate and p-toluenesulfonic acid in an acetal reaction to obtain compound C1 (dicyclopentadienone-diethyl L-tartrate); compound B1 is... ;

[0011] S2: In a solvent, under the action of an alkali, the compound C1 is subjected to an ester hydrolysis reaction to obtain compound D1 (dicyclopentadienone-L-tartaric acid);

[0012] S3: In an organic solvent, the compound D1 is polymerized with 4-dimethylaminopyridine to obtain the additive shown in Formula I.

[0013] 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.

[0014] In S1, the molar ratio of compound B1 to dimethyl L-tartrate can be conventional for this type of reaction in the art, preferably 1:(1-1.5), for example 1:1.

[0015] In S1, the molar ratio of compound B1 to p-toluenesulfonic acid can be conventional for this type of reaction in the art, preferably 1:(20-60), for example 1:34.5.

[0016] In S1, the post-treatment steps of the acetal reaction can be conventional post-treatment steps in the art, preferably including washing, drying, filtering, and solvent removal. The washing solvent can be conventional for this type of reaction in the art, preferably washing with an aqueous sodium bicarbonate solution, water, and brine in sequence. The drying is preferably done with magnesium sulfate.

[0017] In S1, the reaction time of the acetal reaction is based on the complete reaction of the reactants, preferably 26 to 60 hours, for example 48 hours.

[0018] In S1, the preferred temperature for the acetal reaction is the solvent reflux temperature at room temperature and pressure.

[0019] 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.

[0020] 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, with potassium hydroxide being preferred.

[0021] In S2, the molar volume ratio of compound C1 to the solvent can be conventional for this type of reaction in the art, preferably 0.1 to 0.7 mol / L, for example 0.5 mol / L.

[0022] In step S2, the alkali preferably participates in the reaction in the form of an aqueous solution. The mass ratio of the alkali to water is preferably 0.1:1 to 0.6:1, for example, 0.3:1.

[0023] In step S2, a post-treatment step may be included after the ester hydrolysis reaction is completed. The post-treatment step can be routine for this type of reaction in the art, such as including neutralization and purification operations. The purification step preferably employs column chromatography, and more preferably, ethyl acetate is used as the eluent in the column chromatography.

[0024] In S2, the time for the ester hydrolysis reaction is determined by whether the reaction can no longer proceed, preferably 3 to 15 hours, for example 6 hours.

[0025] In S2, the preferred temperature for the ester hydrolysis reaction is the reflux temperature of the solvent at room temperature and pressure.

[0026] In S3, the organic solvent can be a commonly used organic solvent for this type of reaction in the art, preferably an acid anhydride solvent, such as acetic anhydride.

[0027] In S3, the molar ratio of 4-dimethylaminopyridine to compound D1 can be conventional for this type of reaction in the art, preferably 1:0.9 to 1.5, for example 1:1.3.

[0028] In S3, the molar ratio of the organic solvent to the compound D1 can be conventional for this type of reaction in the art, preferably 3:1 to 7:1, for example 5:1.

[0029] In S3, the polymerization reaction time is based on the point at which the reaction ceases to occur, preferably 3 to 15 hours, for example 6 hours.

[0030] In S3, the temperature of the polymerization reaction can be conventional for this type of reaction in the art, preferably 100-200°C, for example 130°C-190°C.

[0031] In S3, the polymerization reaction is preferably carried out at 130°C first, and then the temperature is raised to 190°C.

[0032] In step S3, the polymerization reaction may further include a post-processing step. The post-processing step may be conventional for this type of reaction in the art, and preferably includes dissolution and purification operations.

[0033] The present invention also provides a method for preparing an additive, wherein the method for preparing the additive is as described above.

[0034] In the photoresist, the amount of photoacid-generating agent by weight can be conventional for this type of reaction in the art, preferably 2-10 parts, for example 4 parts.

[0035] In the photoresist, the photoacid-generating agent can be a conventional reaction agent in this field, preferably a sulfur salt, for example... .

[0036] In the photoresist, the weight-average molecular weight of the resin as shown in formula (L) can be conventional for this type of reaction in the art, preferably 8000-9000, for example 8500.

[0037] In the photoresist, the amount of the resin as shown in formula (L) by weight can be conventional for this type of reaction in the art, preferably 20-120 parts, for example 100 parts.

[0038] In the photoresist, the additive shown in Formula I, by weight, can be the conventional amount for this type of reaction in the art, preferably 0.1-1 parts, for example 0.5 parts.

[0039] In the photoresist, the solvent, by weight, can be in the conventional form for this type of reaction in the art, preferably 500-2000 parts, for example 1000 parts.

[0040] In the photoresist, the solvent can be a conventional solvent for this type of reaction in the art, preferably an ester solvent, such as propylene glycol methyl ether acetate.

[0041] The photoresist comprises the following raw materials in parts by weight: 4 parts photoacid generator, 100 parts resin as shown in formula (L), 0.5 parts additive as shown in formula I above, and 1000 parts solvent.

[0042] The photoresist is composed of the following raw materials: the compound shown in Formula I, the resin, the photoacid generator, and the solvent.

[0043] In the photoresist, the resin shown in Formula L is prepared by the following method: unsaturated acid is polymerized in an organic solvent under the action of an initiator.

[0044] In the photoresist, the unsaturated acid can be a conventional reaction in the art, preferably one or more of the following compounds, for example: one or more of 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, the resin shown in Formula L is prepared by the following method: tert-butyl 3-bicyclo[2.2.1]hept-5-en-2-yl-3-hydroxypropionate, 1-methyladamantane acrylate and γ-butyrolactone acrylate are dissolved in 1,4-dioxane, azobisisobutyronitrile is added as an initiator, and hexane is precipitated and dried.

[0046] The present invention also provides a method for preparing the photoresist, which includes the following steps: mixing the resin, the photoacid generator, and the additive shown in Formula I uniformly in a solvent.

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

[0048] In the preparation method described above, the mixing method can be a conventional mixing method in the art, preferably oscillation.

[0049] In the preparation method described above, the mixing step is preferably followed by membrane filtration, for example, using a 0.2 μm membrane.

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

[0051] The photolithography process preferably includes the following steps: coating the photoresist onto a pretreated substrate, drying (e.g., drying at 110°C for 90 seconds), exposure, and development (e.g., using a tetramethylammonium hydroxide aqueous solution as the developer).

[0052] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0053] In this invention, ambient temperature refers to 10–40°C, and ambient pressure refers to 98 kPa–103 kPa.

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

[0055] The positive and progressive effects of the present invention are that the photoresist additive improves the problem of material being leached out in water during immersion photolithography, thereby enabling the formation of photoresist film micropatterns with excellent sensitivity and high resolution. Detailed Implementation

[0056] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0057] Unless otherwise specified, all operations described below are performed at room temperature and pressure.

[0058] Example 1: Preparation of Additives

[0059] 1. Acetal reaction

[0060] Dimethyl L-tartrate (9.18 g, 1 equivalent, 0.05 mol), compound B1 A mixture of (1 equivalent, 0.05 mol) and p-toluenesulfonic acid (250 mg) was refluxed in toluene for 48 hours (Dean-Stark water separator, 0.6 mL water). The solution was cooled and washed with an aqueous solution of sodium bicarbonate (5%, 2 × 100 mL), water (100 mL), and brine (100 mL). The organic layer was dried (MgSO4), filtered, and the solvent was removed under reduced pressure to give compound C1 (dicyclopentadienone-L-diethyl tartrate) as an anhydrous liquid in 91% yield.

[0061] 2. Ester hydrolysis reaction

[0062] The 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 under reflux for 6 hours, and the mixture was slowly neutralized by adding dilute hydrochloric acid. Compound D1 (dicyclopentadienone-L-tartaric acid) was separated by column chromatography using ethyl acetate as the eluent. The product was a white, waxy solid and could be used directly in 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), and the mixture was stirred at 130 °C for 6 hours. The temperature was then raised to 190 °C and stirred for approximately 10 hours, followed by removal of acetic acid under reduced pressure. After cooling to room temperature, the solid product was dissolved in DMSO and purified by precipitation in toluene to obtain polymer A1 (an additive as shown in Formula I). ​​GPC analysis showed a molecular weight Mw of 1970 and Mw / Mn = 1.3.

[0065] Example 2: Preparation of Resin

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

[0067]

[0068] Photoresist preparation examples

[0069] 100 parts by weight of the resin shown in formula (L), 4 parts by weight of the photoacid generator PAGX, and 0.5 parts by weight of the additive shown in formula I were dissolved in 1000 parts by weight of propylene glycol methyl ether acetate, and the solution was then filtered through a 0.2 μm membrane filter. This process was used to prepare the photoresist.

[0070] Comparative Example 1

[0071] Compound B1 in step 1 of Example 1 was replaced with compound B2 to obtain compound C2. Then, ester hydrolysis and polymerization reactions were carried out in sequence according to steps 2 and 3 of Example 1 to obtain polymer A2. The molecular weight Mw was 2100 and Mw / Mn = 1.2 as determined by GPC.

[0072]

[0073] Comparative Example 2

[0074] Compound B1 in step 1 of Example 1 was replaced with B3 to obtain compound C3. Then, ester hydrolysis and polymerization reactions were carried out in sequence according to steps 2 and 3 of Example 1 to obtain polymer A3. The molecular weight Mw was 1840 and Mw / Mn = 1.0 as determined by GPC.

[0075]

[0076] Effect Example

[0077] An anti-reflective undercoat (BARC, AR40A-900, Rohm and Haas Electronic Materials Co., Ltd.) with a thickness of 90 nm was formed on a silicon substrate, and the photoresist composition prepared above was coated on the substrate having BARC. The substrate was baked at 110°C for 60 seconds to form a photoresist film with a thickness of 120 nm.

[0078] The thickness change of each photoresist film before and after development was measured by developing a silicon substrate with a photoresist film in a 2.38 wt% aqueous solution of trimethylammonium hydroxide (TMAH) and measuring the thickness of the photoresist film.

[0079] The sliding angle and the retreating contact angle of the photoresist film were measured respectively.

[0080] Specifically, 50 μl of pure water was dropped onto a horizontal silicon substrate containing the photoresist film to form a droplet. While the silicon substrate was gradually tilted, the angle at which the droplet began to slide down (sliding angle) and the retreat contact angle were measured.

[0081] Then, to achieve liquid immersion lithography, the exposed photoresist film was rinsed with pure water for 5 minutes. Specifically, exposure was performed using an ArF scanner 306C (Nikon Corp., NA = 0.78, 6% halftone mask), and the substrate was rinsed with pure water for 5 minutes. Exposure was performed at 110°C for 60 seconds, followed by PEB treatment and development with 2.38% by weight TMAH developer for 60 seconds.

[0082] The silicon substrate was diced to evaluate sensitivity. Sensitivity corresponds to the exposure required to form a 65 nm line-and-space (L / S) pattern with a linewidth to line spacing ratio of 1:1.

[0083] Table 1

[0084]

[0085] Conclusion: Referring to Table 1, the photoresist film formed using the photoresist containing the additives prepared in the examples has a higher sliding angle and a higher retraction contact angle than the photoresist film formed using the photoresist composition prepared in the comparative examples. Furthermore, the photoresist film prepared in the examples exhibits excellent sensitivity after liquid immersion lithography, but a pattern was not formed on the photoresist film formed in the comparative examples.

Claims

1. A photoresist comprising the following raw materials: an additive as shown in Formula I, a resin as shown in Formula (L), a photoacid generator, and a solvent; wherein the weight-average molecular weight of the additive is 1000-3000; and the weight-average molecular weight / number-average molecular weight ratio of the additive is 1-5. ； The additive shown in Formula I is: 。 2. The photoresist as described in claim 1, characterized in that, The method for preparing the additive includes the following steps: S1: Compound B1 is prepared by reacting it with dimethyl L-tartrate and p-toluenesulfonic acid in an organic solvent to form an acetal, thereby obtaining compound C1; wherein compound B1 is... ; S2: In a solvent, under the action of an alkali, the compound C1 is subjected to an ester hydrolysis reaction to obtain compound D1; S3: In an organic solvent, the compound D1 is polymerized with 4-dimethylaminopyridine to obtain the additive shown in Formula I; And / or, in the photoresist, the photoacid-generating agent is 2-10 parts by weight; And / or, in the photoresist, the photoacid-generating agent is a sulfide; And / or, in the photoresist, the weight-average molecular weight of the resin as shown in formula (L) is 8000-9000; And / or, in the photoresist, the resin as shown in formula (L) is in the amount of 20-120 parts by weight. And / or, in the photoresist, the additive shown in Formula I is 0.1-1 parts by weight; And / or, in the photoresist, the solvent is in the amount of 500-2000 parts by weight; And / or, in the photoresist, the solvent is an ester solvent; And / or, the photoresist comprises the following raw materials in parts by weight: 4 parts photoacid generator, 100 parts resin as shown in formula (L), 0.5 parts additive as shown in formula I above, and 1000 parts solvent. And / or, the photoresist is composed of the following raw materials: the compound as shown in Formula I, the resin, the photoacid generator, and the solvent; And / or, in the photoresist, the resin as shown in Formula L is prepared by polymerizing an unsaturated acid in an organic solvent under the action of an initiator.

3. The photoresist as described in claim 2, characterized in that, The unsaturated acid is one or more of 3-bicyclo[2.2.1]hept-5-en-2-yl-3-hydroxypropionate tert-butyl ester, 1-methyladamantyl acrylate, and γ-butyrolactone acrylate.

4. The photoresist as described in claim 1, characterized in that, The weight-average molecular weight of the additive is 1500~2500; And / or, the weight-average molecular weight / number-average molecular weight ratio of the additive is 1 to 2; And / or, in the photoresist, the photoacid-generating agent is 4 parts by weight; And / or, in the photoresist, the photoacid-generating agent is... ; And / or, in the photoresist, the weight-average molecular weight of the resin as shown in formula (L) is 8500; And / or, in the photoresist, the resin as shown in formula (L) is 100 parts by weight; And / or, in the photoresist, the additive shown in Formula I is 0.5 parts by weight; And / or, in the photoresist, the solvent is 1000 parts by weight; And / or, in the photoresist, the solvent is propylene glycol methyl ether acetate.

5. The photoresist as described in claim 2, characterized in that, In the photoresist preparation method described above, in step S1, the organic solvent is an aromatic hydrocarbon solvent; And / or, in the photoresist preparation method, in S1, the molar ratio of compound B1 to dimethyl L-tartrate is 1:(1-1.5). And / or, in the photoresist preparation method, in S1, the molar ratio of compound B1 to p-toluenesulfonic acid is 1:(20-60). And / or, in the photoresist preparation method, in S1, the post-processing step of the acetal reaction includes washing, drying, filtering and solvent removal operations; And / or, in the photoresist preparation method, in S1, the reaction time of the acetal reaction is 26 hours to 60 hours; And / or, in the photoresist preparation method, in S1, the temperature of the acetal reaction is the solvent reflux temperature at room temperature and pressure; And / or, in the photoresist preparation method, in S2, the solvent is a ketone solvent; And / or, in the method for preparing the photoresist, in S2, the alkali is an inorganic alkali; And / or, in the method for preparing the photoresist, in step S2, the molar volume ratio of compound C1 to the solvent is 0.1~0.7 mol / L; And / or, in the photoresist preparation method, in S2, the alkali participates in the reaction in the form of an alkaline aqueous solution, and the mass ratio of the alkali to water is 0.1:1 to 0.6:1; And / or, in the photoresist preparation method, in step S2, after the ester hydrolysis reaction is completed, a post-processing step is included, which includes neutralization and purification operations; And / or, in the photoresist preparation method, in S2, the ester hydrolysis reaction time is 3 hours to 15 hours; And / or, in the photoresist preparation method, in S2, the temperature of the ester hydrolysis reaction is the reflux temperature of the solvent at room temperature and pressure; And / or, in the photoresist preparation method, in S3, the organic solvent is an acid anhydride solvent; And / or, in the method for preparing the photoresist, in step S3, the molar ratio of 4-dimethylaminopyridine to compound D1 is 1:0.9~1.5; And / or, in the photoresist preparation method, in S3, the molar ratio of the organic solvent to the compound D1 is 3:1 to 7:1; And / or, in the photoresist preparation method, in S3, the polymerization reaction time is 3 hours to 15 hours; And / or, in the photoresist preparation method, in S3, the polymerization reaction temperature is 100~200℃; And / or, in the photoresist preparation method, in S3, the polymerization reaction includes a post-processing step; the post-processing step includes dissolution and purification operations; And / or, in the photoresist, the resin shown in Formula L is prepared by the following method: tert-butyl 3-bicyclo[2.2.1]hept-5-en-2-yl-3-hydroxypropionate, 1-methyladamantane acrylate and γ-butyrolactone acrylate are dissolved in 1,4-dioxane, azobisisobutyronitrile is added as an initiator, and hexane is precipitated and dried.

6. The photoresist as described in claim 2, characterized in that, In the photoresist preparation method described above, in step S1, the organic solvent is toluene; And / or, in the photoresist preparation method, in S1, the molar ratio of compound B1 to dimethyl L-tartrate is 1:1.3; And / or, in the photoresist preparation method, in S1, the molar ratio of compound B1 to p-toluenesulfonic acid is 1:34.5; And / or, in the photoresist preparation method, in S1, the post-processing step of the acetal reaction includes washing, drying, filtering and solvent removal operations; the solvent for washing is sequentially washed with sodium bicarbonate aqueous solution, water and brine, and the drying is performed using magnesium sulfate drying; And / or, in the photoresist preparation method, in S1, the reaction time of the acetal reaction is 48 hours; And / or, in the photoresist preparation method, in S2, the solvent is N-methylpyrrolidone; And / or, in the method for preparing the photoresist, in S2, the alkali is potassium hydroxide and / or sodium hydroxide; And / or, in the photoresist preparation method, in S2, the molar volume ratio of compound C1 to the solvent is 0.5 mol / L; And / or, in the photoresist preparation method, in S2, the alkali participates in the reaction in the form of an alkaline aqueous solution, and the mass ratio of the alkali to water is 0.3:1; And / or, in the photoresist preparation method, in S2, after the ester hydrolysis reaction is completed, a post-processing step is included, the post-processing step includes neutralization and purification operations, and the purification step adopts the column chromatography method; And / or, in the method for preparing the photoresist, in S2, the ester hydrolysis reaction time is 6 hours; And / or, in the method for preparing the photoresist, in S3, the organic solvent is acetic anhydride; And / or, in the photoresist preparation method, in S3, the molar ratio of 4-dimethylaminopyridine to compound D1 is 1:1; And / or, in the photoresist preparation method, in S3, the molar ratio of the organic solvent to the compound D1 is 5:1; And / or, in the photoresist preparation method, in S3, the polymerization reaction time is 6 hours; And / or, in the photoresist preparation method, the polymerization reaction in S3 is carried out at a temperature of 130°C first, and then the temperature is raised to 190°C.

7. The photoresist as described in claim 2, characterized in that, In the photoresist preparation method described above, in step S2, the alkali is potassium hydroxide; And / or, in the photoresist preparation method, in S2, after the ester hydrolysis reaction is completed, a post-processing step is included, the post-processing step includes neutralization and purification operations, the purification step adopts column chromatography, and ethyl acetate is used as the eluent in column chromatography.

8. A method for preparing a photoresist as described in any one of claims 1 to 7, comprising the following steps: The resin, the photoacid-generating agent, and the additive shown in Formula I are mixed evenly in a solvent.

9. The preparation method according to claim 8, characterized in that, The mixing method described is oscillation; And / or, the mixing step may be followed by membrane filtration.

10. The preparation method according to claim 9, characterized in that, The filter membrane used is a 0.2μm filter membrane.

11. An application of a photoresist in a photolithography process, wherein the photoresist is as described in any one of claims 1 to 7.

12. The application as described in claim 11, characterized in that, The photolithography process includes the following steps: coating the photoresist onto a pretreated substrate, drying, exposing, and developing.

13. The application as described in claim 12, characterized in that, The drying process involves drying at 110°C for 90 seconds; the developing process uses a tetramethylammonium hydroxide aqueous solution as the developing agent.

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