KR20010011767A - Novel photoresist polymer and photoresist composition containing it - Google Patents

Abstract

PURPOSE: A novel photoresist copolymer suitable for use in a lithography process using a light source in an area of deep ultraviolet rays in the manufacture of a fine circuit of highly integrated semiconductors, photoresist composition using the same and process for producing the same are provided, which can be effectively applied to an ArF photoresist film. CONSTITUTION: A photoresist copolymer of formula 6 comprises a compound of formula 1, one or more compounds of formula 2 and maleic anhydride copolymer of formula 3, and has a molecular weight of 3,000 to 100,000. In formula, w, x, y and z represent a mole equivalent ratio of w : x : y : z of 0.1 to 0.9 : 0.1 to 0.9 : 0.9 : 0.1 based on the z; R1 is C1-10 substituted or nonsubstituted straight or side chained alkyl, preferably t-butyl as a protecting group; R2 is H, C1-10 substituted or nonsubstituted straight or side chained alkyl; R is H, C1-10 substituted or nonsubstituted straight or side chained alkyl or alcohol; m and n are the same or different 1 or 2; and n is 1 or 2. The process for forming a photoresist pattern comprises the steps of: forming a photoresist film by coating a photoresist composition on a wafer; exposing the photoresist film with an exposure source; and obtaining a desired pattern by developing the photoresist film, optionally executing a baking process at 70 to 200deg.C before and/or after the exposing process.

Description

Novel photoresist polymer and photoresist composition containing it

The present invention relates to a novel photoresist polymer and a photoresist composition using the polymer, and more particularly, to a photoresist suitable for use in a lithography process using a light source in the far ultraviolet region in the manufacture of a microcircuit of a highly integrated semiconductor device. The present invention relates to a polymer, a photoresist composition using the polymer, and a production method thereof.

In order to achieve high sensitivity in the microfabrication process of semiconductor manufacturing, photolithography is suitable for lithography using a light source in a chemically amplified deep ultra violet (DUV) region such as KrF (249 nm), ArF (193 nm) or EUV. The resist is in the spotlight, and such a photoresist is prepared by combining a photoacid generator and a polymer for photoresist having a structure sensitive to acid.

The mechanism of action of the photoresist is that the photoacid generator that receives ultraviolet light from the light source generates an acid, and the polymer main chain or side chain of the exposed portion is decomposed by the acid, and then dissolved in the developer, while the non-exposed site is dissolved. Since the film retains its original structure after the developer treatment, the mask image remains as a positive image on the substrate. In such a lithography process, the resolution is dependent on the wavelength of the light source, and as the wavelength of the light source becomes smaller, a fine pattern can be formed. Accordingly, a photoresist suitable for such a light source is required.

In addition, photoresists generally have to have excellent etching resistance, heat resistance and adhesion, and can be developed in a known developer, for example, an aqueous solution of 2.38% tetramethylammonium hydroxide (TMAH), in view of reducing process costs. Do. However, it is very difficult to produce a polymer that satisfies all these properties, especially photoresist for far ultraviolet rays. For example, polymers having a main chain of polyacrylate are easy to synthesize, but have problems in securing etching resistance and developing processes. In order to secure etching resistance, a method of adding an aliphatic cyclic unit to the main chain may be considered, but it is very difficult to configure all of the main chains with aliphatic cyclic units.

In order to solve the above problems, polymers having the following structures in which main chains are substituted with noborane, acrylate, and maleic anhydride have been developed in Bell Labs.

But. This resin has a problem that the maleic anhydride portion (A) used to polymerize aliphatic cyclic olefin groups is very well soluble in 2.38% TMAH even when unexposed. Therefore, in order to suppress the dissolution of the polymer in the non-exposed part, the proportion of the Y-substituted part of t-butyl should be increased, but then the proportion of the Z part which increases the adhesion with the substrate is reduced. There was a problem that the photoresist fell during patterning. In order to solve this problem, a cholesterol dissolution inhibitor was added to the resin as a two-component system, but since these dissolution inhibitors must be added in a large amount of 30% by weight of the resin, the reproducibility is low and the manufacturing cost is increased. It was difficult to use as a photoresist resin because of the disadvantages.

In addition, many studies have been reported to increase the etching resistance of photoresist resins (Journal of photopolymer science and Technology Vol. 10, No. 3, 511-520 (1997)), but are essential for the formation of ultrafine patterns of 0.10 μm or less. As a result, the thickness of the photoresist should be 0.3 μm or less, and a photoresist capable of withstanding the etching gas at this thickness has not yet been developed.

Accordingly, the present inventors have been trying to solve the above-mentioned problems of the prior art, and focus on the fact that the compounds of the formulas (1), (2) and (3) have an aliphatic olefin structure with excellent adhesion and excellent etching resistance. The present invention was completed by synthesizing polymers containing these compounds in the main chain, and confirming that these polymers not only had etching resistance and adhesion, but also had a significant difference in solubility at exposed and non-exposed sites for the developer.

It is an object of the present invention to provide a novel photoresist copolymer and a photoresist composition containing the copolymer.

In order to achieve the above object, in the present invention, a novel photoresist copolymer and a method of manufacturing the same; A photoresist composition containing the copolymer; And it provides a semiconductor device manufactured using the photoresist composition.

Hereinafter, the present invention will be described in detail.

The present invention first provides a copolymer for photoresist comprising (a) a compound of formula (1), (b) at least one compound of formula (2), and (c) maleic anhydride of formula (3) .

Wherein m is 1 or 2.

Wherein R is hydrogen, substituted or unsubstituted straight or branched chain alkyl or alcohol having 1 to 10 carbon atoms, and n is 1 or 2.

In the above, the compound of formula 1 is cis-5-norbornene-endo-2,3-dicarboxylic anhydride or cis-bicyclo- [2.2.2] oct-5-ene-endo-2,3 -Dicarboxylic anhydride; The compound of formula 2 is 2-hydroxyethyl 5-norbornene-2-carboxylate, t-butyl 5-norbornene-2-carboxylate, 2-hydroxyethyl bicyclo [2.2.2] oct-5 Preference is given to those selected from the group consisting of -ene-2-carboxylate and t-butyl bicyclo [2.2.2] oct-5-ene-2-carboxylate.

In this case, the compound of Formula 2 may be further classified into two groups of Formula 4 and Formula 5, and the photoresist copolymer according to the present invention preferably includes one or more monomers selected from each of these groups.

Wherein R ₁ is an acid sensitive protecting group, which is substituted or unsubstituted linear or branched alkyl having 1 to 10 carbon atoms, preferably t-butyl.

Wherein R ₂ is substituted or unsubstituted straight or branched alkyl having 1 to 10 carbon atoms.

In addition, the copolymer has a structure of Formula 6, and preferably has a molecular weight of 3,000 to 100,000.

In the above formula, when w, x, y and z are each based on z, the molar equivalence ratio is w: x: y: z = 0.1 to 0.9: 0.1 to 0.9: 0.1 to 0.9: 1, and R ₁ represents acid. As sensitive protecting groups, substituted or unsubstituted straight or branched chain alkyl having 1 to 10 carbon atoms, preferably t-butyl, R ₂ is substituted or unsubstituted straight or branched chain alkyl having 1 to 10 carbon atoms, m and n are Equal or different, 1 or 2, respectively.

Preferred examples of the copolymer

Poly (maleic anhydride / cis-5-norbornene-endo-2,3-dicarboxylic anhydride / 2-hydroxyethyl 5-norbornene-2-carboxylate / t-butyl 5- Norbornene-2-carboxylate); And

Poly (maleic anhydride / cis-5-norbornene-endo-2,3-dicarboxylic anhydride / 2-hydroxyethyl bicyclo [2.2.2] oct-5-en-2-car Carboxylate / t-butyl 5-norbornene-2-carboxylate).

The copolymer of the present invention is a radical polymerization by dissolving the compound of Formula 1, at least one compound of Formula 2, and maleic anhydride of Formula 3 in an organic solvent, and then adding a radical polymerization initiator thereto. It is prepared by the process, which consists of the following steps;

(a) dissolving the compound of Formula 1, at least one compound of Formula 2, and maleic anhydride of Formula 3 in an organic solvent;

(b) adding a polymerization initiator to the resultant solution of step (a); And

(c) reacting the resultant solution of step (b) for 4 to 24 hours at a temperature of 60 to 70 ° C. under a nitrogen or argon atmosphere.

In the preparation process, radical polymerization is carried out by bulk polymerization or solution polymerization, and the organic solvent which is a polymerization solvent is cyclohexanone, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dioxane, methyl ethyl ketone, benzene, toluene And a single solvent or a mixed solvent selected from the group consisting of xylene;

The polymerization initiator is benzoyl peroxide, 2,2'-azobisisobutyronitrile (AIBN), acetyl peroxide, lauryl peroxide, t-butyl peracetate, t-butyl hydroperoxide and di-t-butylper Preference is given to using those selected from the group consisting of oxides.

The present invention also provides a photoresist composition comprising the copolymer of the present invention, an organic solvent and a photoacid generator.

Examples of the photoacid generator include diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxy phenyl triflate, diphenyl paratoluenyl triflate and diphenyl Paraisobutylphenyl triflate, diphenylpara-t-butylphenyl triflate, triphenylsulfonium hexafluoro phosphate, triphenylsulfonium hexafluoro arsenate, triphenylsulfonium hexafluoro antimonate, triphenylsulfonium Sulfur-based or onium salt-based compounds selected from triflate and dibutylnaphthylsulfonium triflate are mainly used, and are preferably contained in a proportion of 0.1 to 10% by weight based on the copolymer.

The organic solvent is also selected from the group consisting of methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate and cyclohexanone.

The photoresist composition is prepared by dissolving the copolymer of the present invention in an amount of 10 to 30% by weight with respect to an organic solvent, by adding a photoacid generator in an amount of 0.1 to 10% by weight with respect to a resist polymer and filtering with an ultrafine filter. do.

The photoresist composition of the present invention prepared as described above is not only excellent in etching resistance, heat resistance and adhesion, but also developable in an aqueous 2.38% aqueous solution of TMAH, and thus may be used as an ArF photosensitive film.

The present invention also provides a method of forming a photoresist pattern consisting of the following steps;

(a) applying the photoresist composition of the present invention onto a wafer to form a photoresist film;

(b) exposing the photoresist film to an exposure source; And

(c) developing the photoresist film with a developer to obtain a desired pattern.

In the process, i) before and after exposure of step (b); Or ii) pre- or post-exposure each of which may further comprise a baking process, which is carried out at 70 to 200 ° C.

In addition, the exposure process is performed using an exposure energy of 0.1 to 10 mJ / cm ² using a deep ultra violet (DUV; E-beam, X-ray or ion beam including ArF, KrF and EUV as a light source It is desirable to be.

Specifically, for example, the photoresist pattern forming method; The photoresist composition of the present invention was spin-coated onto a silicon wafer to prepare a thin film, and then soft-baked in an oven or hot plate at 80 to 150 ° C. for 1 to 5 minutes, and exposed using an ultraviolet ray exposure apparatus or an excimer laser exposure apparatus. Then, it bakes after exposure at 100-200 degreeC. The wafer thus exposed is immersed in a 2.38% TMAH aqueous solution for 1 minute 30 seconds to obtain an ultrafine positive resist image.

The present invention also provides a semiconductor device manufactured using the photoresist composition of the present invention.

Hereinafter, the present invention will be described in detail by examples. However, the examples are only to illustrate the invention and the present invention is not limited by the following examples.

I. Preparation of Polymer for Photoresist

Example 1 poly (maleic anhydride / cis-5-norbornene-endo-2,3-dicarboxylic anhydride / 2-hydroxyethyl 5-norbornene-2-carboxylate / t -Butyl 5-norbornene-2-carboxylate)

1.0 mol maleic anhydride, 0.2 mol cis-5-norbornene-endo-2,3-dicarboxylic anhydride, 0.2 mol 2-hydroxyethyl 5-norbornene-2-carboxylate, t 0.6 mol of -butyl 5-norbornene-2-carboxylate was dissolved in tetrahydrofuran, and 0.5 to 15 g of AIBN, a polymerization initiator, was added, followed by reaction at a temperature of about 60 to 70 ° C. under nitrogen or argon for 4 to 24 hours. I was.

The polymer thus formed was precipitated in ethyl ether or hexane and dried to afford the title compound.

Example 2 Poly (maleic anhydride / cis-5-norbornene-endo-2,3-dicarboxylic anhydride / 2-hydroxyethyl bicyclo [2.2.2] oct-5-ene -2-carboxylate / t-butyl 5-norbornene-2-carboxylate)

In Example 1, instead of 0.2 mol of 2-hydroxyethyl 5-norbornene-2-carboxylate, 0.2 mol of 2-hydroxyethyl bicyclo [2.2.2] oct-5-ene-2-carboxylate was added. Except for using the reaction in the same manner as in Example 1 to give the title compound.

II. Preparation and Pattern Formation of Photoresist Composition

Example 3

10 g of the polymer prepared in Example 1 was dissolved in 70 g of propylene glycol methyl ether acetate solvent, 0.2 g of triphenylsulfonium triflate as a photoacid generator was added thereto, stirred, and filtered with a 0.10 μm filter to prepare a photoresist composition. It was.

The photoresist composition was spin-coated on the etched layer of the silicon wafer to prepare a thin film, then soft baked for 90 seconds in an oven or hot plate at 150 ° C., and baked at 140 ° C. for 90 seconds using an 193 nm ArF light source. . The wafer thus exposed was immersed in a 2.38% TMAH aqueous solution for 1 minute to form an ultrafine photoresist pattern. At this time, when the thickness of the photoresist was about 0.45 mu m, a vertical L / S pattern of 0.15 mu m was obtained.

Example 4

A photoresist composition was prepared in the same manner as in Example 3, except that the polymer prepared in Example 2 was used instead of the polymer of Example 1, thereby forming a photoresist pattern. At this time, when the thickness of the photoresist was about 0.45 mu m, a vertical L / S pattern of 0.15 mu m was obtained.

The photoresist composition prepared by using the copolymer according to the present invention is not only excellent in etching resistance, heat resistance and adhesion to the substrate, but also developable in a 2.38% TMAH aqueous solution which is a developer, which can be usefully applied as an ArF photosensitive film. There is this.

In particular, when the photoresist composition of the present invention having excellent adhesion to the substrate was used, even when the thickness of the photoresist was 0.45 µm, the resolution and the focus viscosity of the L / S pattern of 0.15 µm were obtained. Therefore, by using the photoresist composition of the present invention it is possible to reliably manufacture a highly integrated semiconductor device.

Claims (22)

A copolymer for a photoresist comprising (a) a compound of formula (1), (b) at least one compound of formula (2), and (c) maleic anhydride of formula (3). Formula 1 Wherein m is 1 or 2. Formula 2 Wherein R is hydrogen, substituted or unsubstituted straight or branched chain alkyl or alcohol having 1 to 10 carbon atoms, and n is 1 or 2. Formula 3 The method of claim 1, The polymer is a copolymer for photoresist, characterized in that having a molecular weight of 3,000 to 100,000. The method of claim 1, The copolymer is a photoresist copolymer, characterized in that it comprises at least one monomer each selected from the group consisting of the formula (4) and formula (5) belonging to the compound of formula (2). Formula 4 Wherein R ₁ is an acid sensitive protecting group, which is substituted or unsubstituted linear or branched alkyl having 1 to 10 carbon atoms, preferably t-butyl. Formula 5 Wherein R ₂ is substituted or unsubstituted straight or branched alkyl having 1 to 10 carbon atoms. The method of claim 1, The copolymer is a photoresist copolymer, characterized in that the compound of formula (6). Formula 6 In the above formula, when w, x, y and z are each based on z, the molar equivalence ratio is w: x: y: z = 0.1 to 0.9: 0.1 to 0.9: 0.1 to 0.9: 1, and R ₁ represents acid. As sensitive protecting groups, substituted or unsubstituted straight or branched chain alkyl having 1 to 10 carbon atoms, preferably t-butyl, R ₂ is substituted or unsubstituted straight or branched chain alkyl having 1 to 10 carbon atoms, m and n are Equal or different, 1 or 2, respectively. The method of claim 1, Compounds of formula (I) may be cis-5-norbornene-endo-2,3-dicarboxylic anhydride or cis-bicyclo- [2.2.2] oct-5-ene-endo-2,3-dicar Cyclic anhydride; The compound of formula 2 is 2-hydroxyethyl 5-norbornene-2-carboxylate, t-butyl 5-norbornene-2-carboxylate, 2-hydroxyethyl bicyclo [2.2.2] oct-5 -Ene-2-carboxylate and t-butyl bicyclo [2.2.2] oct-5-ene-2-carboxylate. Copolymer for photoresist, characterized in that selected from the group consisting of. The method of claim 1, The copolymer is poly (maleic anhydride / cis-5-norbornene-endo-2,3-dicarboxylic anhydride / 2-hydroxyethyl 5-norbornene-2-carboxylate / t -Butyl 5-norbornene-2-carboxylate) or poly (maleic anhydride / cis-5-norbornene-endo-2,3-dicarboxylic anhydride / 2-hydroxyethyl bicyclo [2.2.2] Oct-5-ene-2-carboxylate / t-butyl 5-norbornene-2-carboxylate). (a) dissolving a compound of Formula 1, at least one compound of Formula 2, and maleic anhydride of Formula 3 in an organic solvent; (b) adding a polymerization initiator to the resultant solution of step (a); And (C) the method of producing a copolymer for a photoresist comprising the step of reacting the resulting solution of step (b) for 4 to 24 hours at a temperature of 60 to 70 ℃ under nitrogen or argon atmosphere. Formula 1 Wherein m is 1 or 2. Formula 2 Wherein R is hydrogen, substituted or unsubstituted straight or branched chain alkyl or alcohol having 1 to 10 carbon atoms, and n is 1 or 2. Formula 3 The method of claim 7, wherein The organic solvent is a photoresist characterized in that it is a single solvent or a mixed solvent selected from the group consisting of cyclohexanone, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dioxane, methyl ethyl ketone, benzene, toluene and xylene Method for producing a copolymer for use. The method of claim 7, wherein The polymerization initiators are benzoyl peroxide, 2,2'-azobisisobutyronitrile (AIBN), acetyl peroxide, lauryl peroxide, t-butyl peracetate, t-butyl hydroperoxide and di-t-butyl Method for producing a photoresist copolymer, characterized in that selected from the group consisting of peroxides. The method of claim 7, wherein The radical polymerization is a method for producing a copolymer for photoresist, characterized in that the bulk polymerization or solution polymerization. A photoresist composition comprising a photoresist resin, an organic solvent, and a photoacid generator, wherein the photoresist resin is a copolymer represented by the following formula (6). Formula 6 In the above formula, when w, x, y and z are each based on z, the molar equivalence ratio is w: x: y: z = 0.1 to 0.9: 0.1 to 0.9: 0.1 to 0.9: 1, and R ₁ represents acid. As sensitive protecting groups, substituted or unsubstituted straight or branched chain alkyl having 1 to 10 carbon atoms, preferably t-butyl, R ₂ is substituted or unsubstituted straight or branched chain alkyl having 1 to 10 carbon atoms, m and n are Equal or different, 1 or 2, respectively. The method of claim 11, The photoresist composition is a photoresist composition, characterized in that the sulfur salt or onium salt. The method of claim 12, The photoacid generator is diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxyphenyl triflate, diphenyl paratoluenyl triflate, diphenyl Paraisobutylphenyl triflate, diphenylpara-t-butylphenyl triflate, triphenylsulfonium hexafluoro phosphate, triphenylsulfonium hexafluoro arsenate, triphenylsulfonium hexafluoro antimonate, triphenylsulfonium A photoresist composition comprising one or more selected from the group consisting of triflate and dibutylnaphthylsulfonium triflate. The method of claim 11, The photoresist composition is a photoresist composition, characterized in that used in 0.1 to 10% by weight relative to the resin. The method of claim 11, The organic solvent is selected from the group consisting of methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate and cyclohexanone. The method of claim 11, The photoresist resin is a photoresist composition, characterized in that used in 10 to 30% by weight relative to the organic solvent. (a) applying the photoresist composition of claim 11 onto a wafer to form a photoresist film; (b) exposing the photoresist film to an exposure source; And (c) developing the photoresist film with a developer to obtain a desired pattern. The method of claim 17, I) pre-exposure and post-exposure of step (b); Or ii) performing a baking process before or after exposure, respectively. The method of claim 18, The baking process is a photoresist pattern forming method, characterized in that performed at 70 to 200 ℃. The method of claim 17, The exposure source is a method of forming a photoresist pattern, characterized in that selected from the group consisting of deep ultra violet (DUV; E-beam, X-ray and ion beam including ArF, KrF and EUV. The method of claim 17, The exposure process is a photoresist pattern forming method, characterized in that carried out with an exposure energy of 1 to 10 mJ / cm ² . A semiconductor device manufactured by the method of claim 17.