CN115960341A

CN115960341A - Additive for ArF immersion photoresist and photoresist containing additive

Info

Publication number: CN115960341A
Application number: CN202111172184.6A
Authority: CN
Inventors: 王溯; 方书农; 徐森; 邹琴峰
Original assignee: Shanghai Xinke Micro Material Technology Co Ltd
Current assignee: Shanghai Xinke Micro Material Technology Co Ltd
Priority date: 2021-10-08
Filing date: 2021-10-08
Publication date: 2023-04-14
Anticipated expiration: 2041-10-08
Also published as: CN115960341B

Abstract

The invention discloses an additive for an ArF immersion photoresist and a photoresist containing the same. Specifically discloses an additive shown as a 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. The additive of the invention has at least the following advantages: the photoresist containing the additive can improve the problem that materials are leached in water during immersion lithography exposure, so that a photoresist film micro-pattern having excellent sensitivity and high resolution can be formed.

Description

Additive for ArF immersion photoresist and photoresist containing additive

Technical Field

The invention relates to an additive for an ArF immersion photoresist and a photoresist containing the same.

Background

With higher integration and higher speed of large scale integrated circuits (LSIs) in recent years, accurate micro-patterning 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.

In ArF immersion lithography using an ArF excimer laser as a light source, the space between the projection lens and the wafer substrate is filled with water. According to this method, even if a lens having an NA of 1.0 or more is used, a pattern can be formed with the refractive index of water at 193nm, and this method is generally called immersion lithography. However, since the photoresist film is directly contacted 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. For this reason, it is urgently required to develop a photoresist resin or an additive capable of improving such a situation.

Disclosure of Invention

In view of the above problems in the prior art, the present invention is directed to an additive for ArF immersion photoresist and a photoresist containing the same, wherein the additive has at least the following advantages: the photoresist containing the additive can improve the problem that materials are leached in water during immersion lithography exposure, so that a photoresist film micro-pattern having excellent sensitivity and high resolution can be formed.

The invention provides application of a compound shown as a formula I as an additive in a photoresist; the weight average molecular weight of the additive may be 1000 to 3000, preferably 1500 to 2500 (e.g., 1940); the additive may have a weight average molecular weight/number average molecular weight ratio of 1 to 5, preferably 1 to 2 (e.g. 1.1);

in one embodiment, the preparation method of the additive comprises the following steps:

s1, in an organic solvent, carrying out an acetal reaction on the compound B1, L-dimethyl tartrate and p-toluenesulfonic acid to obtain a compound C1 (2, 3-bicyclo [2, 1)]hept-5-en-2-one-L-diethyl tartrate); the compound B1 is

S2, in a solvent, under the action of alkali, carrying out ester hydrolysis reaction on the compound C1 to obtain a compound D1 (2, 3-bicyclo [2, 1] hept-5-ene-2-one-L-tartaric acid);

and S3, in an organic solvent, carrying out polymerization reaction on the compound D1 and 4-dimethylaminopyridine to obtain the additive shown in the formula I.

In S1, the organic solvent may be an organic solvent conventional in the art for such reactions, preferably an aromatic hydrocarbon solvent, such as toluene.

The molar ratio of said compound B1 to said L-tartaric acid dimethyl ester in S1 can be conventional in the art for such reactions, preferably 1 (1-1.5), such as 1.

In S1, the molar ratio of said compound B1 to said p-toluenesulfonic acid may be conventional in reactions of this type in the art, preferably 1: (20-60), for example 1:38.5.

in S1, the post-treatment step of the acetalization reaction may be a post-treatment step conventional in the art, and preferably includes operations of washing, drying, filtering, and removing a solvent. The washing solvent may be conventional in the art for such reactions, and is preferably washed with aqueous sodium bicarbonate, water, and brine in that order. The drying is preferably magnesium sulfate drying.

In S1, the reaction time of the aldolization is preferably 26 to 60 hours, for example, 48 hours, based on the completion of the reaction of the reactants.

In S1, the temperature of the acetalization reaction is preferably a solvent reflux temperature at normal temperature and pressure.

In S2, the solvent may be a solvent conventional in such reactions in the art, preferably a ketone solvent, such as N-methylpyrrolidone.

In S2, the base may be a base conventional to such reactions in the art, preferably an inorganic base, such as potassium hydroxide and/or sodium hydroxide, preferably potassium hydroxide.

The molar volume ratio of said compound C1 to said solvent in S2 may be conventional in the art for such reactions, preferably between 0.1 and 0.7mol/L, for example 0.5mol/L.

In S2, the base is preferably present in the reaction in the form of an aqueous base solution. The mass ratio of the base to water is preferably 0.1 to 0.6, for example 0.3.

In S2, a post-treatment step can be included after the ester hydrolysis reaction is finished. The work-up step may be conventional in the art for such reactions, and may include, for example, neutralization and purification operations. The purification step preferably employs a chromatographic column, more preferably ethyl acetate as eluent in the chromatographic column.

In S2, the ester hydrolysis reaction is preferably carried out for a time period of 3 to 15 hours, for example, 6 hours, based on the time period when the reaction is not carried out.

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

In S3, the organic solvent may be an organic solvent commonly used in the reaction of this type in the art, preferably an acid anhydride solvent, such as acetic anhydride.

In S3, the molar ratio of the 4-dimethylaminopyridine to the compound D1 can be conventional in such reactions in the art, preferably from 0.0006 to 0.0012, e.g. 0.001.

In S3, the molar ratio of the organic solvent to the compound D1 may be conventional in such reactions in the art, preferably 3.

In S3, the polymerization reaction is not allowed to proceed any longer, and is preferably carried out for 3 to 15 hours, for example, for 6 to 10 hours.

In S3, the temperature of the polymerization reaction may be a temperature conventional in such reactions in the art, preferably 100 to 200 ℃.

In S3, the polymerization reaction is preferably carried out at 130 ℃ for 6 hours and then at 190 ℃ for 10 hours.

In S3, the polymerization reaction may further include a post-treatment step. The work-up step may be conventional in the art for such reactions, and preferably includes operations of dissolution and purification.

The invention also provides a preparation method of the additive, which is as described above.

The invention also provides a photoresist, which comprises the following raw materials: the additive shown in the formula I, the resin shown in the formula (L), the photoacid generator and the solvent are added;

the photoacid generator may be used in the photoresist in amounts conventional for such reactions in the art, preferably in amounts of 2 to 10 parts, for example 4 parts, by weight.

In the photoresist, the photoacid generator may be conventional in the art, preferably a sulfur salt, e.g., as in the case of the reaction

In the photoresist, the weight average molecular weight of the resin represented by formula (L) may be conventional in the art, and is preferably 8000 to 9000, for example 8500.

In the photoresist, the resin shown in the formula (L) can be used in the conventional manner, wherein the parts by weight are preferably 20-120 parts, for example 100 parts.

The additive of formula I may be used in the photoresist in an amount conventional in the art, wherein the parts by weight are preferably 0.1 to 1 part, for example 0.5 part.

The amount of the solvent used in the photoresist may be conventional in the art, wherein the parts by weight are preferably 500 to 2000 parts, for example 1000 parts.

In the photoresist, the solvent can be conventional in the field, and is preferably an ester solvent, such as propylene glycol methyl ether acetate.

The photoresist comprises the following raw materials in parts by weight: 4 parts of a photoacid generator, 100 parts of a resin represented by the formula (L), 0.5 part of an additive represented by the formula I and 1000 parts of a solvent.

The photoresist consists of the following raw materials: the compound shown as the formula I, the resin, the photoacid generator and the solvent.

In the photoresist, the resin shown as the formula L is prepared by the following method: polymerizing unsaturated acid ester in organic solvent under the action of initiator.

In the photoresist, the unsaturated acid ester may be conventional in the art for such reactions, preferably one or more of the following compounds, for example: one or more of 3-bicyclo [2.2.1] hept-5-en-2-yl-3-hydroxy butyl acrylate, 1-methyladamantyl acrylate and gamma-butyrolactone acrylate; more preferably a mixture of tert-butyl 3-bicyclo [2.2.1] hept-5-en-2-yl-3-hydroxypropionate, 1-methyladamantyl acrylate and gamma-butyrolactone acrylate. Wherein, in the mixture, the molar ratio of the three is preferably 1.

The organic solvent may be an organic solvent conventional in the art, preferably an ethereal solvent, such as 1, 4-dioxane.

The initiator may be an initiator conventional in the art, such as azobisisobutyronitrile.

In the photoresist, the resin shown as the formula L is prepared by the following method, and the method comprises the following steps: mixing 3-bicyclo [2.2.1] hept-5-ene-2-yl-3-hydroxy-propionic acid tert-butyl ester, 1-methyl adamantane acrylate, gamma-butyrolactone acrylate and 1, 4-dioxane, adding azodiisobutyronitrile as initiator, precipitating with n-hexane, and drying.

The invention also provides a preparation method of the photoresist, which comprises the following steps: and (2) in a solvent, uniformly mixing the resin, the photoacid generator and the additive shown in the formula I.

In the preparation method, the solvent, the resin, the photoacid generator and the additive shown in the formula I are as described above.

In the preparation method, the mixing mode can be a mixing mode conventional in the field, and shaking is preferred.

In the preparation method, the mixing step preferably further comprises membrane filtration, for example, filtration with a 0.2 μm membrane.

The invention also provides an application of the photoresist in a photoetching process.

Wherein, the photoetching process preferably comprises the following steps: the photoresist is coated on a pretreated substrate, dried (e.g., at 110 ℃ for 90 seconds), exposed, and developed (e.g., using a developer solution of aqueous tetramethylammonium hydroxide).

In the present invention, the weight average molecular weight and the molecular weight distribution index can be measured by a conventional test method in the art, such as Gel Permeation Chromatography (GPC).

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

In the present invention, the normal temperature means 10 to 40 ℃. The normal pressure is 98kPa to 103kPa.

The reagents and starting materials used in the present invention are commercially available.

The positive progress effects of the invention are as follows: the photoresist additive improves the problem that a material is leached in water during immersion lithography exposure, so that a photoresist film micro-pattern having excellent sensitivity and high resolution can be formed.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the invention thereto. Experimental procedures without specifying specific conditions in the following examples were selected in accordance with conventional procedures and conditions, or in accordance with commercial instructions.

In the following operations, the temperature and pressure are not particularly specified, and they are carried out at normal temperature and normal pressure.

EXAMPLE 1 preparation of the additive

1. Acetal reaction

L-tartaric acid dimethyl ester (9.18 g, 1 eq, 0.05 mol), compound B1

(1 eq, 0.05 mol) and p-toluene sulfonic 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 (5%, 2X 100 ml)) Water (100 ml) and brine (100 ml). The organic layer was dried (MgSO ₄ ) Filtration and removal of the solvent under reduced pressure gave compound C1 (2, 3-bicyclo [2, 1)]hept-5-en-2-one-L-diethyl tartrate) as an anhydrous liquid in 91% yield.

2. Ester hydrolysis reaction

Compound C1 (0.01 mol) prepared in example 1 was dissolved in a mixture of NMP (20 ml) and 30% aqueous potassium hydroxide (3 g), water (10 g)). The reaction mixture was heated to reflux for 6 hours and the mixture was slowly neutralized by addition of dilute hydrochloric acid. Separating by column chromatography to obtain compound D1 (2, 3-bicyclo [2, 1] hept-5-en-2-one-L-tartaric acid), ethyl acetate as eluent, and the product is white waxy solid which can be directly used in the next step.

3. Polymerisation reaction

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 ℃ for 6 hours. The temperature was then raised to 190 ℃ and stirred for about 10 hours, then the acetic acid was removed under reduced pressure. Cooling to room temperature, dissolving the solid product in DMSO, precipitating into toluene, and purifying to obtain polymer A1 (additive shown in formula I), wherein the molecular weight Mw is 1970 and Mw/Mn =1.1 according to GPC detection.

EXAMPLE 2 preparation of the resin

Tert-butyl 3-bicyclo [2.2.1] hept-5-en-2-yl-3-hydroxypropionate (hereinafter referred to as BHP), 1-methyladamantane acrylate and gamma-alkene butyrolactone acrylate were added in a molar ratio of 1. 300 parts by weight of 1, 4-dioxane as a polymerization solvent was added with respect to 100 parts by weight of the total amount of the reactive monomers, 4 parts by mole of azobisisobutyronitrile as an initiator was added with respect to 100 parts by mole of the total amount of the reactive monomers, and the mixture was reacted at 65 ℃ for 16 hours. After the reaction, the reaction solution was precipitated with n-hexane, and the precipitate was removed and dried in vacuo. Thus, a resin having a weight average molecular weight of about 8500g/mol was obtained as shown in formula (L).

Examples of Photoresist preparation

100 parts by weight of a resin represented by the formula (L), 4 parts by weight of a photoacid generator PAXX and 0.5 part by weight of an additive represented by the formula I were dissolved in 1000 parts by weight of propylene glycol methyl ether acetate, and the solution was filtered through a 0.2 μm membrane filter. Thereby preparing a photoresist.

Comparative example 1

Compound C2 was obtained by replacing compound B1 in step 1 of example 1 with compound B2, and ester hydrolysis and polymerization were carried out in the order of steps 2 and 3 with reference to steps 1 and 2 in example 1 to obtain polymer A2 having a molecular weight Mw of 2100,Mw/Mn =1.2 as determined by GPC.

Comparative example 2

Compound C3 was prepared by replacing compound B1 with B3 in step 1 of example 1, and ester hydrolysis and polymerization were carried out successively in steps 2 and 3 of example 1 to obtain polymer A3 having a molecular weight Mw of 1840 as determined by GPC and Mw/Mn =1.0.

Effects of the embodiment

An antireflective undercoat layer (BARC, AR40A-900, rohm and Haas electronic materials Co., ltd.) having a thickness of 90nm was formed on a silicon substrate, and the above-prepared photoresist composition was coated on the BARC-bearing substrate. The substrate was baked at 110 ℃ for 60 seconds to form a photoresist film having a thickness of 120 nm.

The thickness change of each photoresist film before and after development was measured by developing the silicon substrate having the photoresist film with a 2.38 wt% aqueous solution of trimethyl ammonium hydroxide (TMAH) and measuring the thickness of the photoresist film.

The sliding angle and receding contact angle of the photoresist film were measured, respectively.

Specifically, 50 μ l of pure water was dropped on a silicon substrate having the photoresist film held horizontally to form a droplet. While the silicon substrate was gradually tilted, the angle (sliding angle) and receding contact angle at which the droplet started to slide down were measured.

Then, to realize liquid immersion lithography, the exposed photoresist film was rinsed 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 ℃ for 60 seconds, PEB was carried out, and development was carried out for 60 seconds using 2.38 wt% TMAH developer.

The silicon substrate was cut to evaluate sensitivity. The sensitivity corresponds to the exposure amount for forming a line-and-space (L/S) pattern of 65nm with a ratio of line width to line spacing of 1.

TABLE 1

And (4) conclusion: referring to table 1, the photoresist film formed using the photoresist containing the additives prepared in the examples had 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 films prepared in examples had excellent sensitivity after liquid immersion lithography, but patterns were not formed on the photoresist film formed in comparative example.

Claims

1. An additive represented by 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. additive according to claim 1, wherein the additive has a weight average molecular weight of 1500 to 2500, such as 1940;

and/or the additive has a weight average molecular weight/number average molecular weight ratio of 1 to 2, for example 1.1.

3. The additive of claim 1, wherein the additive is prepared by a process comprising the steps of:

s1, in an organic solvent, carrying out an acetal reaction on a compound B1, L-dimethyl tartrate and p-toluenesulfonic acid to obtain a compound C1; the compound B1 is

S2, in a solvent, under the action of alkali, carrying out ester hydrolysis reaction on the compound C1 to obtain a compound D1;

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 L-dimethyl 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 reaction time of the acetalization reaction is 26 to 60 hours.

5. The additive of claim 3, wherein in S2, the solvent is a ketone solvent;

and/or, in S2, the base is an inorganic base, and preferably participates in the reaction in the form of an aqueous base solution, and the mass ratio of the base to water may be 0.1;

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 time of the ester hydrolysis reaction is 3 hours to 15 hours.

6. The additive according to claim 3, wherein in S3, the organic solvent is an acid anhydride-based solvent;

and/or, in S3, the molar ratio of the 4-dimethylaminopyridine to the compound D1 is 0.0006 to 0.0012;

and/or, in S3, the molar ratio of the organic solvent to the compound D1 is 3;

and/or in S3, the time of the polymerization reaction is 3 to 15 hours;

and/or in S3, the temperature of the polymerization reaction is 100-200 ℃.

7. The additive according to any one of claims 4 to 6, wherein in S1, the organic solvent is toluene;

and/or, in S1, the molar ratio of the compound B1 to the L-tartaric acid dimethyl ester is 1;

and/or, in S1, the molar ratio of the compound B1 to the p-toluenesulfonic acid is 1:38.5;

and/or, in S1, the reaction time of the acetalization reaction is 48 hours;

and/or, in S2, the solvent is N-methyl pyrrolidone;

and/or, in S2, the alkali is potassium hydroxide and/or sodium hydroxide; the alkali is preferably participated in the reaction in the form of alkali aqueous solution, and the mass ratio of the alkali to the water can be 0.3;

and/or, in S2, the molar volume ratio of the compound C1 to the solvent is 0.5mol/L;

and/or, in S2, the 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 the 4-dimethylaminopyridine to the compound D1 is 0.001;

and/or, in S3, the molar ratio of the organic solvent to the compound D1 is 5;

and/or in S3, the time of the polymerization reaction is 6 to 10 hours;

and/or in S3, the temperature of the polymerization reaction is 130-190 ℃.

8. The additive according to any one of claims 4 to 6, wherein in S1, the temperature of the acetalization reaction is the solvent reflux temperature at normal temperature and pressure;

and/or, in S2, the alkali is potassium hydroxide;

and/or in S2, the temperature of the ester hydrolysis reaction is the solvent reflux temperature under normal temperature and normal pressure;

and/or, in S3, the polymerization reaction is carried out at 130 ℃ for 6 hours and then at 190 ℃ for 10 hours.

9. A method for producing an additive, characterized in that each operation and each condition in the production method are the same as those of the method for producing an additive according to any one of claims 3 to 8.