KR20030001784A - Novel photoresist polymer and photoresist composition containing it - Google Patents

Abstract

PURPOSE: Provided are a novel photoresist polymer which can be used at light source of VUV(vacuum ultraviolet)(157 nm) and EUV(extreme ultraviolet)(13 nm), and a photoresist composition comprising the same. CONSTITUTION: The photoresist comprises a repeating unit of the formula 3. In the formula 3, R1 represents an acid labile protecting group, R2 represents an alicyclic pendant group, and a:b is 10-90:10-90(mole%). The acid labile protecting group is selected from the group consisting of t-butyl, 1-ethoxyethyl, 1-cyclohexyloxyethyl, tetrahydropyran-2-yl, 2-methyl tetrahydropyran-2-yl, tetrahydrofuran-2-yl, 2-methyl tetrahydrofuran-2-yl, 1-methoxypropyl, 1-methoxy-1-methylethyl, 1-ethoxypropyl, 1-ethoxy1-methylethyl, 1-methoxyethyl, t-butoxyethyl, 1-isobutoxyethyl, and 2-acetylment-1-yl.

Description

Novel photoresist polymer and photoresist composition containing it

The present invention relates to a novel photoresist polymer and a photoresist composition containing the polymer, and more particularly to light sources in the far ultraviolet region, in particular VUV (157 nm) and EUV (13 nm) light sources, in the manufacture of microcircuits of highly integrated semiconductor devices. A photoresist polymer suitable for use in a photolithography process using a photoresist, a photoresist composition containing the polymer, and a method of manufacturing the same

To be used as a photoresist for ArF and VUV (vacuum ultraviolet), it has to have low light absorption at wavelengths of 193 nm and 157 nm, have excellent etching resistance and adhesion to the substrate, and 2.38 wt% and 2.6 wt% tetramethylammonium hydride. Many requirements must be met, such as developing with an aqueous solution of hydroxide (TMAH).

The main research direction so far has been to search for resins having a high transparency at 193 nm and etching resistance at the same level as the novolak resin. However, most of these photoresists show strong absorbance in the wavelength region of 157 nm, which is not suitable for VUV photoresists. In order to compensate for this, researches on developing photoresists including fluorine and silicon have been intensively conducted.

Among them, when the fluorine is contained in the main chain of the polymer, it is known to have a particularly low absorbance. However, acrylate polymers containing only fluorine have too low etching resistance and thus have many problems in actual commercialization. .

The present inventors have completed the present invention by finding that a photoresist containing a photoresist polymer containing fluorine in the main chain and having an alicyclic pendant group has a low absorbance at a wavelength of 157 nm.

It is an object of the present invention to provide novel photoresist polymers which can be used in VUV (157 nm) and EUV (13 nm) light sources and photoresist compositions containing the polymers.

1 is a photoresist pattern photo formed by Example 4.

2 is a photoresist pattern photo formed by Example 5.

3 is a photoresist pattern photo formed by Example 6.

In order to achieve the above object, the present invention provides a novel photoresist polymer and a preparation method thereof; A photoresist composition containing the polymer; A photoresist pattern forming method using the photoresist composition; And it provides a semiconductor device manufactured by the photoresist composition.

Hereinafter, the present invention will be described in detail.

The present invention firstly provides a photoresist polymer comprising a repeating unit of formula (3) containing fluorine in the main chain and having an alicyclic pendant group.

[Formula 3]

Where

R ₁ is an acid labile protecting group;

R ₂ is an alicyclic pendant group;

a: b is 10-90 mol%: 10-90 mol%.

At this time, an acid-sensitive protecting group is a group that can be detached by an acid. When an acid-sensitive protecting group is attached, the photoresist is prevented from being dissolved by an alkaline developer, and the protecting group is sensitive to acid generated by exposure. Desorption can dissolve in alkaline developer.

Such acid-sensitive protecting groups can be any one which can play such a role, which is US 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (1996. 11. 28), EP 0 794 458 (September 10, 1997), EP 0 789 278 (August 13, 1997) and US 6,132,926 (October 17, 2000) and the like. Preferably t-butyl, 1-ethoxyethyl, 1-cyclohexyloxyethyl, tetrahydropyran-2-yl, 2-methyl tetrahydropyran-2-yl, tetrahydrofuran-2-yl, 2-methyl Tetrahydrofuran-2-yl, 1-methoxypropyl, 1-methoxy-1-methylethyl, 1-ethoxypropyl, 1-ethoxy-1-methylethyl, 1-methoxyethyl, t-butoxy Ethyl, 1-isobutoxyethyl, 2-acetylment-1-yl and the like.

R ₂ also acts as an acid sensitive protecting group, but must be an alicyclic pendant group to ensure etch resistance. Preferably aryl or cycloalkoxy alkyl of C ₁ -C ₁₅ .

Preferred examples of the repeating unit of Chemical Formula 3 include compounds represented by the following Chemical Formulas 3a to 3c.

[Formula 3a]

[Formula 3b]

[Formula 3c]

In another aspect, the present invention provides a method for producing a photoresist polymer comprising a repeating unit of the formula (3).

The polymerization repeating unit of the present invention is prepared by radical addition polymerization of a compound of Formula 1 and a compound of Formula 2, the process consisting of the following steps;

(a) mixing a compound of Formula 1 and a compound of Formula 2; And

(b) obtaining a polymerization repeating unit of Chemical Formula 3 by adding and polymerizing a radical polymerization initiator to the resultant of step (a).

[Formula 1]

[Formula 2]

Where

R ₁ is a protecting group sensitive to acid;

R ₂ is an alicyclic pendant group, as described above.

The compound of Formula 1 is prepared by reacting trifluoromethyl acrylic acid with a compound having a protecting group sensitive to the acid as a monomer having a protecting group sensitive to an acid. Representative compounds having an acid-sensitive protecting group include t-butyl vinyl ether, ethyl vinyl ether or cyclohexyl vinyl ether.

Preferred examples of the compound of Formula 1 include compounds represented by the following Formulas 1a to 1c.

[Formula 1a]

[Formula 1b]

[Formula 1c]

The compound of Formula 2 is a monomer containing fluorine in the main chain and having an alicyclic pendant group, and is prepared by reacting trifluoromethyl acrylic acid with an alicyclic compound.

Preferred examples of the compound of Formula 2 include a compound of Formula 2a.

[Formula 2a]

In the preparation process, radical polymerization is carried out by bulk polymerization or solution polymerization, in the case of solution polymerization, cyclohexanone, cyclopentanone, 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.

In addition, the polymerization initiator may be selected from the group consisting of 2,2'-azobisisobutyronitrile (AIBN), benzoyl peroxide, acetyl peroxide, lauryl peroxide, t-butyl peracetate and di-t-butyl peroxide. It is preferable to use the selected one.

On the other hand, the repeating unit of the present invention may also be obtained using a metal catalyst as disclosed in WO 96/37526 (Nov. 28, 1996).

In addition, the resulting polymer is more preferably crystallized using diethyl ether, petroleum ether, alkane, alcohol, water or a mixed solvent thereof.

The photoresist polymer of the present invention comprises the above repeating units in the main chain, and other comonomers or additives as necessary.

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

As described above, the photoresist polymer of the present invention is a compound of Chemical Formula 3.

As the photoacid generator, any compound capable of generating an acid by light may be used, for example, US 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (1996. 11. 28), EP 0 794 458 (September 10, 1997), EP 0 789 278 (August 13, 1997), and US 6,132,926 (October 17, 2000) and the like, and are mainly sulfur-based or sludge Umo-based compounds are used.

Preferably, phthalimidotrifluoromethanesulfonate, dinitrobenzyltosylate, n-decyldisulfone or naphthylimidotrifluoromethanesulfonate having relatively low absorbance at 157 nm and 193 nm is used, together with di Phenylureate hexafluorophosphate, diphenylureate hexafluoro arsenate, diphenylureate hexafluoro antimonate, diphenylparamethoxyphenyl triflate, diphenylparatoluenyl triflate, diphenylparaisobutyl Phenyl triflate, triphenylsulfonium hexafluoro arsenate, triphenylsulfonium hexafluoro antimonate, triphenylsulfonium triflate or dibutylnaphthylsulfonium triflate, and the photoresist polymer It is preferably used at a ratio of 0.1 to 10% by weight relative to. When the photoacid generator is used in an amount of 0.1 wt% or less, the photosensitive sensitivity of the photoresist becomes weak. When the photoacid generator is used in an amount of 10 wt% or more, the photoacid generator absorbs a lot of ultraviolet rays and generates a large amount of acid, thereby obtaining a pattern having a bad cross section. .

In addition, the organic solvent may be any organic solvent commonly used in the photoresist composition, US 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (Nov. 28, 1996), EP 0 794 458 (September 10, 1997), EP 0 789 278 (August 13, 1997) and US 6,132,926 (October 17, 2000) and the like, preferably Methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate, cyclohexanone, n-heptanone or ethyl lactate, 400 to 1500 weight based on the photoresist polymer The ratio is used to obtain a photoresist film having a desired thickness, and according to the present invention, the photoresist thickness when the organic solvent is used in an amount of 1000% by weight based on the photoresist polymer is 0.2 탆.

The present invention also provides a method of forming a photoresist pattern comprising the following steps:

(a) coating the photoresist composition according to the present invention on the etched layer to form a photoresist film;

(b) exposing the photoresist film; And

(c) developing the result to obtain a desired pattern.

I) before and after exposure in step (b); Or ii) performing a baking process before or after the exposure, respectively, and the baking process is preferably performed at 70 to 200 ° C.

In addition, the exposure process is preferably performed with an exposure energy of 1 to 30 mJ / cm ² using not only VUV but also ArF, KrF, E-beam, EUV (extreme ultraviolet) or ion beam.

On the other hand, the developing step (c) in the above may be performed using an alkaline developer, the alkali developer is preferably 0.01 to 5% by weight of TMAH aqueous solution.

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 Photoresist Polymer

Example 1 Preparation of a Compound of Formula 3a

(Step 1) Preparation of Compound of Formula 1a

Trifluoromethylacrylic acid (0.2M), t-butylalcohol (0.2M) and dicyclohexylcarbodiimide (0.2M) were mixed in 50 ml of tetrahydrofuran, which had been completely dehydrated, and reacted at room temperature for 12 hours. The white salt produced after the reaction was filtered, extracted with ethyl ether, washed several times with pure water, and the solution was collected and vacuum distilled to obtain t-butyltrifluoromethylacrylate of Chemical Formula 1a. (Yield 78%).

(Step 2) Preparation of Compound of Formula 2a

Trifluoromethylacrylic acid (0.2M), isobonolol (0.2M), and dicyclohexylcarbodiimide (0.2M) were mixed in 50 ml of tetrahydrofuran, which had been completely dehydrated, and reacted at room temperature for 12 hours. The white salt produced after the reaction was filtered, extracted with ethyl ether, washed with pure water several times, and the solution was collected and vacuum distilled to obtain the isobornyltrifluoromethyl acrylate of Chemical Formula 2a (yield 78%). .

(Step 3) Preparation of Compound of Formula 3a

The compound of Formula 1a prepared in Step 1 (0.05mol), the compound of Formula 2a prepared in Step 2 (0.05mol), and 0.1 g of AIBN were dissolved in 100 ml of tetrahydrofuran and reacted at 70 ° C. for 6 hours. After the reaction, the resulting solution was distilled to remove tetrahydrofuran, precipitated in petroleum ether, and filtered. The resulting resin was dried in vacuo to give the compound of formula 3a (yield 80%).

Example 2. Preparation of Compound of Formula 3b

(Step 1) Preparation of Compound of Formula 1b

Trifluoromethylacrylic acid (0.2M), ethyl vinyl ether (0.2M), and p-toluenesulfonic acid (10 mg) were dissolved in 100 ml of dehydrated tetrahydrofuran and reacted at low temperature (10 ° C) for 12 hours. After the reaction, the resultant solution was distilled to remove tetrahydrofuran, extracted with ethyl ether, washed with 5% Na ₂ CO ₃ aqueous solution, which was weak base, and washed again with distilled water to completely remove the base. The solution was collected and distilled under vacuum to obtain the ethoxyethyl trifluoromethyl acrylate of Chemical Formula 1b (yield 84%).

(Step 2) Preparation of Compound of Formula 3b

The compound of formula 1b prepared in step 1 (0.05mol), the compound of formula 2a prepared in step 2 of Example 1 (0.05mol) and 0.1 g of AIBN were dissolved in 100 ml of tetrahydrofuran and then dried at 70 ° C. The reaction was time. After the reaction, the resulting solution was distilled to remove tetrahydrofuran, precipitated in petroleum ether, and filtered. The resulting resin was dried in vacuo to give the compound of formula 3b (yield 82%).

Example 3. Preparation of Compound of Formula 3c

(Step 1) Preparation of Compound of Formula 1c

Trifluoromethylacrylic acid (0.2M), cyclohexyl vinyl ether (0.2M), and p-toluenesulfonic acid (10 mg) were dissolved in 100 mL of dehydrated tetrahydrofuran and reacted at low temperature (10 ° C) for 12 hours. After the reaction, the resultant solution was distilled to remove tetrahydrofuran, extracted with ethyl ether, washed with 5% Na ₂ CO ₃ aqueous solution, which was weak base, and washed again with distilled water to completely remove the base. The solution was collected and distilled under vacuum to obtain cyclohexyloxyethyl trifluoromethyl acrylate of Chemical Formula 1c (yield 80%).

(Step 2) Preparation of a Compound of Formula 3c

The compound of Formula 1c prepared in Step 1 (0.05 mol), the compound of Formula 2a prepared in Step 2 of Example 1 (0.05 mol) and 0.1 g of AIBN were dissolved in 100 ml of tetrahydrofuran and then dried at 70 ° C. The reaction was time. After the reaction, the resulting solution was distilled to remove tetrahydrofuran, precipitated in petroleum ether, and filtered. The resulting resin was dried in vacuo to give the compound of formula 3c (yield 82%).

II. Preparation and Pattern Formation of Photoresist Composition

Example 4 Preparation of Photoresist Composition and Formation of Photoresist Pattern (1)

10 g of the compound of formula 3a, a photoresist polymer obtained in Example 1, 0.06 g of phthalimidotrifluoromethanesulfonate as a photoacid generator, and 0.06 g of triphenylsulfonium triflate were used as an organic solvent, propylene glycol methyl ethyl acetate (PGMEA). ) Dissolved in 100 g and filtered through a 0.20 μm filter to obtain a photoresist composition.

The photoresist composition was spin-coated on a silicon wafer and then soft baked at 130 ° C. for 90 seconds, exposed with an ArF laser exposure equipment, and then baked again at 130 ° C. for 90 seconds. After baking was completed in 40 seconds for 2.38% by weight tetramethylammonium hydroxide aqueous solution to obtain an L / S pattern of 0.08㎛ (see Figure 1).

Example 5 Preparation of Photoresist Composition and Formation of Photoresist Pattern (2)

10 g of the compound of formula 3b, a photoresist polymer obtained in Example 2, 0.06 g of phthalimidotrifluoromethanesulfonate as a photoacid generator, and 0.06 g of triphenylsulfonium triflate were used as an organic solvent, propylene glycol methyl ethyl acetate ) Dissolved in 100 g and filtered through a 0.20 μm filter to obtain a photoresist composition.

The photoresist composition was spin-coated on a silicon wafer and then soft baked at 130 ° C. for 90 seconds, exposed to ArF laser exposure equipment, and baked at 130 ° C. for 90 seconds. After baking was completed, 40 seconds of development in a 2.38% by weight tetramethylammonium hydroxide aqueous solution gave an L / S pattern of 0.09 μm (see FIG. 2).

Example 6 Preparation of Photoresist Composition and Formation of Photoresist Pattern (3)

10 g of the compound of Formula 3c, a photoresist polymer obtained in Example 3, 0.06 g of phthalimidotrifluoromethanesulfonate as a photoacid generator, and 0.06 g of triphenylsulfonium triflate were used as an organic solvent, propylene glycol methyl ethyl acetate ) Dissolved in 100 g and filtered through a 0.20 μm filter to obtain a photoresist composition.

The photoresist composition was spin-coated on a silicon wafer and then soft baked at 130 ° C. for 90 seconds, exposed with an ArF laser exposure equipment, and then baked again at 130 ° C. for 90 seconds. After completion of the bake, the L / S pattern of 0.10 μm was obtained after developing for 40 seconds in an aqueous 2.38 wt% tetramethylammonium hydroxide solution (see FIG. 3).

As described above, the photoresist composition containing the photoresist polymer of the present invention is excellent in etching resistance, heat resistance and adhesion, and is not only developable in aqueous tetramethylammonium hydroxide (TMAH) solution, but also in 193nm and 157nm. The low light absorption at the wavelength can be very useful for the photolithography process using a light source in the far ultraviolet region, especially VUV (157 nm) and EUV (13 nm) light source in the production of microcircuits of highly integrated semiconductor devices. In addition, the photoresist composition containing the photoresist polymer of the present invention may be resolved at a thickness of 100 nm or less as well as 200 nm or more.

Claims (20)

A photoresist polymer comprising a repeating unit of the formula (3). [Formula 3] Where R ₁ is an acid labile protecting group; R ₂ is an alicyclic pendant group; a: b is 10-90 mol%: 10-90 mol%. The method of claim 1, The acid sensitive protecting groups include t-butyl, 1-ethoxyethyl, 1-cyclohexyloxyethyl, tetrahydropyran-2-yl, 2-methyl tetrahydropyran-2-yl, tetrahydrofuran-2-yl, 2-methyl tetrahydrofuran-2-yl, 1-methoxypropyl, 1-methoxy-1-methylethyl, 1-ethoxypropyl, 1-ethoxy-1-methylethyl, 1-methoxyethyl, t -Butoxyethyl, 1-isobutoxyethyl and 2-acetylment-1-yl. The method of claim 1, The alicyclic pendant group is selected from the group consisting of C ₁ -C ₁₅ aryl and cycloalkoxy alkyl. The method of claim 1, The repeating unit of Formula 3 is a photoresist polymer, characterized in that selected from the group consisting of the following formula (3a to 3c). [Formula 3a] [Formula 3b] [Formula 3c] (a) mixing a compound of Formula 1 and a compound of Formula 2; And (b) adding a radical polymerization initiator to the resultant of step (a) to polymerize to obtain a polymerization repeating unit represented by the following formula (3). [Formula 1] [Formula 2] [Formula 3] Where R ₁ is a protecting group sensitive to acid; R ₂ is an alicyclic pendant group; a: b is 10-90 mol%: 10-90 mol%. The method of claim 5, The polymerization is carried out in a solvent selected from the group consisting of cyclohexanone, cyclopentanone, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dioxane, methyl ethyl ketone, benzene, toluene, xylene and mixed solutions thereof. Method for producing a photoresist polymer, characterized in that. The method of claim 5, The polymerization initiator is selected from the group consisting of 2,2'-azobisisobutyronitrile (AIBN), benzoyl peroxide, acetyl peroxide, lauryl peroxide, t-butyl peracetate and di-t-butyl peroxide Method for producing a photoresist polymer, characterized in that. A photoresist composition comprising the photoresist polymer of claim 1, a photoacid generator and an organic solvent. The method of claim 8, The photoresist is selected from the group consisting of phthalimido trifluoromethanesulfonate, dinitrobenzyltosylate, n-decyldisulfone and naphthylimidotrifluoromethanesulfonate. The method of claim 9, In addition to the photoacid generator, diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxyphenyl triflate, diphenyl paratoluenyl tri Plate, diphenylparaisobutylphenyl triflate, triphenylsulfonium hexafluoro arsenate, triphenylsulfonium hexafluoro antimonate, triphenylsulfonium triflate and dibutylnaphthylsulfonium triflate The photoresist composition further comprises at least one photoacid generator selected from. The method of claim 8, The photoresist composition is a photoresist composition, characterized in that used in 0.05 to 10% by weight relative to the photoresist polymer. The method of claim 8, As the organic solvent, one selected from the group consisting of methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate, cyclohexanone, n-heptanone and ethyl lactate alone or Photoresist composition, characterized in that used for mixing. The method of claim 8, The organic solvent is a photoresist composition, characterized in that used at 400 to 1500% by weight relative to the photoresist polymer. (a) coating the photoresist composition of claim 8 on the etched layer to form a photoresist film; (b) exposing the photoresist film; And (c) developing the resultant to obtain a desired pattern. The method of claim 14, I) pre-exposure and post-exposure of step (b); Or ii) performing a baking process before or after exposure, respectively. The method of claim 15, The baking process is a photoresist pattern forming method, characterized in that performed at 70 to 200 ℃. The method of claim 14, And the exposure process is performed using a light source selected from the group consisting of VUV (vacuum ultraviolet), ArF, KrF, E-beam, extreme ultraviolet (EUV) and ion beam. The method of claim 14, The exposure process is a photoresist pattern forming method, characterized in that carried out with an exposure energy of 1 to 30 mJ / cm ² . The method of claim 14, The developing step (c) is a photoresist pattern forming method, characterized in that carried out using an alkaline developer. A semiconductor device manufactured using the method of claim 14.