KR20060070649A - Photoresist monomer, photoresist polymer and photoresist composition containing it - Google Patents

Abstract

The present invention relates to a photoresist monomer, a photoresist polymer, and a photoresist composition comprising the same, and more particularly, in all pattern formation processes using immersion lithography, a photoresist monomer of Formula 1, the monomers It is to provide a photoresist polymer comprising a repeating unit and a photoresist composition that can form a pattern with improved line edge roughness (LER) using the same.

[Formula 1]

Where

A is cyclohexane (C ₆ H ₉ ) which is substituted at the 1, 3 or 5 position, or benzene (C ₆ H ₃ ) which is substituted at the 1, 3, 5 position, and R ₁ is H, CH ₃ or CF ₃ and n is an integer of 1 to 5.

Description

Photoresist Monomer, Photoresist Polymer and Photoresist Composition Comprising the Same {Photoresist Monomer, Photoresist Polymer and Photoresist Composition Containing it}

1 is a photoresist pattern photo formed by Example 5.

2 is a photoresist pattern photo formed by Example 6.

3 is a photoresist pattern photo formed by Example 7.

4 is a photoresist pattern photo formed by Example 8.

The present invention relates to a photoresist monomer, a photoresist polymer, and a photoresist composition comprising the same, and more particularly, in all pattern formation processes using immersion lithography, a photoresist monomer of Formula 1, the monomers By using a photoresist polymer containing a repeating unit and by using the same, to provide a photoresist composition capable of forming a pattern with improved line edge roughness (LER).

At present, as semiconductor devices become more and more highly integrated, the ultra-fine processing technology essential for semiconductor production requires the development of an exposure process capable of forming sub-micron-class fine patterns.

Accordingly, a lithography process technology has been developed that introduces a shorter wavelength of deep ultra violet (DUV) light source instead of the g-line (436 nm) and i-line (365 nm) light sources used in the conventional lithography process. It became. Examples of the light source in the far ultraviolet region include KrF (248 nm), ArF (193 nm), VUV (vacuum ultraviolet (157 nm)), EUV (Extremely Ultraviolet (13 nm)), and the like. Use more ArF laser stepper.

The liquid immersion exposure technique is a technique in which a high precision process is enabled on a substrate by filling a liquid in the space between the stepper projection lens and the silicon substrate in order to greatly refract the light passing through the lens during exposure.

The immersion exposure technique can be applied to an ArF light source up to 45 nm node. For this purpose, a chemically amplified photoresist having high sensitivity and high resolution with respect to the ArF laser stepper: CAP) needs to be developed.

In order to be used as the CAP material, the light absorption at the wavelength of 193nm and 157nm should be low, the etching resistance and the adhesion to the substrate should be excellent, and 2.38% by weight and 2.6% by weight of tetramethyl ammonium hydroxide (TMAH) aqueous solution Many of the requirements must be met.                         

The main research direction to date has been to search for resins with high transparency at 248 nm and 193 nm with the same etching resistance as novolak resin.

However, since the photoresist formation thickness of most photoresists decreases as the circuit of the device becomes smaller, the LER of the pattern worsens.

Furthermore, conventional photoresist materials for I-line or KrF contain acidic alcohol groups inside, while most ArF CAP materials do not contain acidic alcohol groups inside, resulting in low affinity for basic developer. Has The ArF photoresist pattern thus obtained has more severe LER than conventional KrF or I-line photoresist patterns.

In addition, the CAP material for ArF diffuses into the non-exposed area during the baking process in which the acid generated from the photoacid generator in the exposed area during the exposure process further lowers the LER of the pattern.

In order to improve this problem at present, it was intended to prevent the acid diffusion into the non-exposed area by including a basic compound such as amine in the CAP material for ArF used in the conventional immersion exposure technology, the basic compound in water during the baking process Dissolution causes another problem that contaminates the exposure lens.

Accordingly, the present inventors completed the present invention by developing a new concept photoresist material that overcomes the conventional problems while studying the above problems.

 It is an object of the present invention to provide a monomer and a photoresist polymer comprising the monomer having the ability to control the acid to obtain an improved pattern LER.

In addition, an object of the present invention is to provide a photoresist composition comprising the photoresist polymer and a pattern forming method with improved LER using the same.

In order to achieve the above object, the present invention provides a photoresist monomer, a photoresist polymer and a photoresist composition comprising the same having the ability to control acid.

Hereinafter, the present invention will be described in detail.

The present invention provides a photoresist monomer represented by the compound of formula (1).

[Formula 1]

Where                     

A is cyclohexane (C ₆ H ₉ ) substituted with 1, 3, or 5 positions or benzene (C ₆ H ₃ ) substituted with 1, 3, or 5 positions,

R ₁ is H, CH ₃ or CF ₃ and n is an integer from 1 to 5.

For example, in the case of cyclohexane (C ₆ H ₉ ) in which A is 1, 3, and 5 substituted with the substituent in Formula 1, it is preferably represented by the following Formula 1a or 1b.

[Formula 1a]

[Formula 1b]

In addition, in Formula 1, when A is benzene (C ₆ H ₃ ) to which the 1, 3, and 5 positions are substituted, the compound is preferably represented by the following Formula 1c or 1d.

[Formula 1c]

[Formula 1d]

In addition, in the present invention, the main chain (phenol), cycloolefin-based, vinylene-based or acrylate-based polymerization repeating unit (polymerization repeating unit), and further comprising a compound of Formula 1 as a polymerization repeating unit It provides a resist polymer.

At this time, the compound of Formula 1 is contained in 1 to 10% by weight, preferably 1 to 5% by weight based on the total weight of the photoresist polymer of the present invention.                     

It is preferable that the total molecular weight of the photoresist polymer of this invention containing the compound of Formula 1 including a polymerization repeating unit is 6000-15000.

In the present invention,

(a) mixing a compound of Formula 2 or 3 with an ethylene glycol ditosylate derivative of Formula 4 to an organic solvent; And

(b) polymerizing the mixture in the presence of a basic compound to obtain a compound of the formula (5) or (6).

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

Where

R ₁ is H, CH ₃ or CF ₃ , n is an integer from 1 to 5,

p is an integer of 1-5.

At this time, the organic solvent is not particularly limited as long as it is an organic solvent capable of dissolving the compound of Formula 2 or 3, preferably triethylamine is used.

The basic compound used in the polymerization reaction is a variety of amine (amine) and sodium hydride (NaH), butyl lithium (n-BuLi), lithium diisopropylamine (LDA) or lithium hydride (LiH) desirable.

Since the photoresist polymer of the present invention comprising a compound having an ethylene oxy group as described above can control the acid during post-exposure bake by a non-covalent electron pair of oxygen, the photoresist composition is included in the photoresist composition. Even if the amine compound is not further included, the acid diffused from the exposure region can be effectively controlled.

In addition, in general, in the case of the photoresist polymer containing a hydrocarbon group, it is almost impossible to reduce the refractive index n value to 1.6 to 1.7, whereas the photoresist polymer containing a fluorine element such as the compound of Formula 1 In the case of the photoresist polymer, it is possible to reduce the high light absorption, which is a problem of the conventional hybrid photoresist polymer, and thus it is possible to lower the refractive index value to 1.6 or less.

In addition, the photoresist composition of the present invention containing the compound having such a structure has a high affinity for the developer while having excellent transmittance, etching resistance and adhesion, and therefore, uses a 248 nm, 193 nm and 157 nm light source. It can be used for all immersion exposure techniques.

In addition, the present invention provides a photoresist composition comprising a photoresist polymer prepared by the above method, a photoacid generator and an organic solvent, instead of including a basic compound.

The photoacid generator is not particularly limited as long as it is a compound capable of generating an acid by light, US 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (1996. 11.28), EP 0794458 (September 10, 1997), EP 0789278 (August 13, 1997), US 5,750,680 (May 12, 1998), US 6,051,678 (April 18, 2000), GB 2,345,286 A (2000) 7. 5), US 6,132,926 (October 17, 2000), US 6,143,463 (11/7/2000), US 6,150,069 (11/21/2000), US 6.180.316 B1 (January 30, 2001), US Sulfur-based or onium salt-based compounds disclosed in 6,225,020 B1 (May 1, 2001), US 6,235,448 B1 (May 22, 2001) and US 6,235,447 B1 (May 22, 2001). In particular, the photoacid generator has a low absorbance at 157 nm and 193 nm phthalimidotrifluoromethane sulfonate, dinitrobenzyltosylate, n-decyl disulfone and naphthyl Preference is given to using those selected from the group consisting of naphthylimido trifluoromethane sulfonate, together with diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo salt hexafluoro Rho antimonate, diphenylparamethoxyphenylsulfonium triflate, diphenylparatoluenylsulfonium triflate, diphenylparaisobutylphenylsulfonium triflate, triphenylsulfonium hexafluoro arsenate, triphenyl Sulfonium hexafluoro antimonate, triphenylsulfonium triflate and dibutane Naphthyl tilseol phosphonium tree can also be used for the photo acid generator selected from the group consisting of a plate, is preferably used in a ratio of 0.05 to 10% by weight of the photoresist polymer. When the photoacid generator is used in an amount of 0.05% by weight or less, the sensitivity of the photoresist to light is weak. When the photoacid generator is used at 10% by weight or more, the photoacid generator absorbs a lot of ultraviolet rays and generates a large amount of acid. You get a bad pattern.

In addition, the organic solvent is not particularly limited, but US 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (Nov. 28, 1996), EP 0 794 458 ( 1997. 9. 10) EP 0 789 278 (August 13, 1997), US 5,750,680 (May 12, 1998), US 6,051,678 (April 18, 2000), GB 2,345,286 A (August 5, 2000), US 6,132,926 (October 17, 2000), US 6,143,463 (11/7/2000), US 6,150,069 (11/21/2000), US 6.180.316 B1 (January 30, 2001), US 6,225,020 B1 (2001. 5. 1), US 6,235,448 B1 (May 22, 2001) and US 6,235,447 B1 (May 22, 2001) and the like, preferably diethylene glycol diethyl ether, ethyl 3- Ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, cyclohexanone, propylene glycol methyl ether acetate, n-heptanone, ethyl Lactate, cyclopentanone, etc. can be used individually or in mixture.

The organic solvent is used at a ratio of 500 to 2000% by weight based on the photoresist polymer, which is to obtain a photoresist film having a desired thickness, for example, a photo obtained when 1000% by weight of the organic solvent is used to the photoresist polymer. The resist thickness is about 0.25 mu m.

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

(a) forming a photoresist film by applying the photoresist composition of the present invention described above on the etched layer;

(b) exposing the photoresist film;

(c) baking the exposed photoresist film; And

(d) developing the resultant to obtain a desired pattern.

In the above process, it may further comprise the step of performing a baking process before exposure, the baking process and the baking process of step (c) is carried out at 70 to 200 ℃.

The exposure process is performed using an exposure energy of 1 to 100 mJ / cm ² using Ar, as well as KrF, Extreme Ultra Violet (EUV), Vacuum Ultra Violet (VUV), E-beam, X-ray or ion beam. desirable.

On the other hand, the development of step (d) is preferably carried out using an alkaline developer, for example 0.01 to 5% by weight of TMAH aqueous solution.

The present invention also provides a semiconductor device manufactured using the pattern formation method described above.

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

I. Preparation of Photoresist Polymer

Example 1 Synthesis of Polymer of Formula 1a

Tetraethylene di (p-toluenesulfonate) (p = 4) (0.1 mol) in tetrahydrofuran (THF) (0.5 ml) in a solution of Formula 2 (R ₁₎ = H) compound (0.1mol) and triethylamine (triethylamine) (0.2mol) was added to the solution in THF (0.5ml) with stirring for 30 minutes, and then reacted for 5 hours at room temperature. After completion of the reaction, THF was removed, washed with water, the water layer was removed and the remaining mixture was dried in vacuo to give the compound of formula 1a (yield 88%).

Example 2. Synthesis of Polymer of Formula 1b

Tetraethylene glycol di (p-toluenesulfonate) (0.1 mol) in THF (0.5 ml) was dissolved in THF (0.5 ml) to the compound of formula 2 (R ₁ = CH ₃ ) (0.1 mol) and triethylamine (0.2 mol) Was added to the solution dissolved in THF (0.5ml) for 30 minutes with stirring, and the reaction was further stirred at room temperature for 5 hours. After completion of the reaction, THF was removed, washed with water, the water layer was removed and the remaining mixture was dried in vacuo to give the compound of formula 1b (yield 86%).

Example 3 Synthesis of Polymer of Formula 1c

Tetraethylene glycol di (p-toluenesulfonate) (0.1 mol) was dissolved in THF (0.5 ml) in a solution of formula 3 (R ₁ = H) (0.1 mol) and triethylamine (0.2 mol) Was added to the solution dissolved in THF (0.5ml) for 30 minutes with stirring, and the reaction was further stirred at room temperature for 5 hours. After completion of the reaction, THF was removed, washed with water, the water layer was removed and the remaining mixture was dried in vacuo to give the compound of formula 1c (yield 89%).

Example 4 Synthesis of Polymer of Formula 1d

In a solution of tetraethylene glycol di (p-toluenesulfonate) (0.1 mol) in THF (0.5 ml), a compound of formula 3 (R ₁ = CH ₃ ) (0.1 mol) and triethylamine (0.2 mol) Was added to the solution dissolved in THF (0.5ml) for 30 minutes with stirring, and the reaction was further stirred at room temperature for 5 hours. After completion of the reaction, THF was removed, washed with water, the water layer was removed and the remaining mixture was dried in vacuo to give the compound of formula 1d (yield 87%).

II. Preparation and Pattern Formation of Photoresist Composition

Example 5.

The polymer (1 g) prepared in Example 1, phthalimidotrifluoromethanesulfonate (0.024 g) and triphenylsulfonium triflate (0.06 g), which are photoacid generators, were prepared using propylene glycol methyl ethyl acetate (PGMEA) ( 30 g) and then filtered through a 0.20 ㎛ filter to obtain a photoresist composition.

The photoresist composition thus obtained was spin coated on the etched layer of the silicon wafer to prepare a photoresist thin film, followed by soft baking for 90 seconds in an oven or a hot plate at 130 ° C., and exposure at 130 ° C. for 90 seconds after exposure with an ArF laser exposure apparatus. Bake again. The baked wafer was immersed in a 2.38 wt% TMAH aqueous solution for 40 seconds and developed to form a 70 μm L / S pattern (see FIG. 1).

Example 6.

A photoresist composition was prepared in the same manner as in Example 5, except that 1b of Polymer (2g) prepared in Example 2 was used instead of the polymer prepared in Example 1, and the composition was 70 μm in size. L / S patterns were formed (see FIG. 2).

Example 7.

A photoresist composition was prepared in the same manner as in Example 5, except that 1c of Polymer (2g) prepared in Example 3 was used instead of the polymer prepared in Example 1, and the composition was 65 μm in size. An L / S pattern was formed (see FIG. 3).

Example 8.

A photoresist composition was prepared in the same manner as in Example 5, except that 1d of Polymer (2 g) prepared in Example 4 was used instead of the polymer prepared in Example 1, and the composition was 65 μm in size. An L / S pattern was formed (see FIG. 4).

As described above, the present invention provides a polymer of the present invention comprising the compound of Formula 1 having an ethylene oxy group and fluorine so as to perform an immersion exposure process, by using 193nm And by providing a photoresist composition having low absorbance and durability, etching resistance, reproducibility, and high resolution in the 157 nm region, the LER can form an improved ultrafine pattern.

Claims (18)

A photoresist monomer, characterized in that represented by the compound of formula [Formula 1]

(Wherein A is cyclohexane (C ₆ H ₉ ) substituted with 1, 3, or 5 positions or benzene (C ₆ H ₃ ) substituted with 1, 3, or 5 positions, R ₁ is H, CH ₃ or CF ₃ , and n is an integer from 1 to 5). The method of claim 1, The compound of Formula 1 is a photoresist monomer, characterized in that represented by the formula 1a or 1b. [Formula 1a]

[Formula 1b]

The method of claim 1, The compound of Formula 1 is a photoresist monomer, characterized in that represented by the formula 1c or 1d. [Formula 1c]

[Formula 1d]

In the main chain, including at least one polymerization repeating unit selected from the group consisting of phenolic, cycloolefinic, vinylene-based and acrylate-based, A photoresist polymer further comprising a compound of Formula 1 as a polymerization repeating unit: [Formula 1]

(Wherein A is cyclohexane (C ₆ H ₉ ) substituted with 1, 3, or 5 positions or benzene (C ₆ H ₃ ) substituted with 1, 3, or 5 positions, R ₁ is H, CH ₃ or CF ₃ , and n is an integer from 1 to 5). The method of claim 4, wherein The compound of Formula 1 is a photoresist polymer, characterized in that contained in 1 to 10% by weight relative to the total weight of the photoresist polymer. The method of claim 4, wherein The total molecular weight of the photoresist polymer is 6000 to 15000, characterized in that the photoresist polymer. (a) mixing the compound of Formula 2 and the compound of Formula 4 with an organic solvent; And (b) polymerizing the mixture in the presence of a basic compound to obtain a compound of formula (5): [Formula 2]

[Formula 4]

[Formula 5]

(Wherein R ₁ is H, CH ₃ or CF ₃ , n is an integer from 1 to 5, p is an integer of 1-5.). (a) mixing the compound of Formula 3 and the compound of Formula 4 with an organic solvent; And (b) polymerizing the mixture in the presence of a basic compound to obtain a compound of formula (6): [Formula 3]

[Formula 4]

[Formula 6]

(Wherein R ₁ is H, CH ₃ or CF ₃ , n is an integer from 1 to 5, p is an integer of 1-5.). The method of claim 7 or 8. The basic compound is selected from the group consisting of an amine compound, sodium hydride (NaH), butyl lithium (n-BuLi), lithium diisopropylamine (LDA) and lithium hydride (LiH). The manufacturing method of the photoresist polymer made into. A photoresist composition comprising the photoresist polymer of claim 4, a photoacid generator and an organic solvent. The method of claim 10, The photoacid generator is phthalimido trifluoromethane sulfonate, dinitrobenzyltosylate, n-decyldisulfone, naphthyl imidotrifluoro methanesulfonate, diphenyl iodo salt hexafluorophosphate, diphenyl iodo salt hexafluoro Arsenate, Diphenyl iodo hexafluoro antimonate, Diphenyl paramethoxyphenyl triflate, Diphenyl paratoluenyl triflate, Diphenyl paraisobutyl phenyl triflate, Triphenylsulfonium hexafluoro arse Photoresist composition, characterized in that at least one selected from the group consisting of nitrate, triphenylsulfonium hexafluoro antimonate, triphenylsulfonium triflate and dibutylnaphthylsulfonium triflate. The method of claim 10, The photoresist composition is characterized in that the photoresist composition is used in an amount of 0.05 to 10% by weight relative to the photoresist polymer The method of claim 10, The organic solvent is diethylene glycol diethyl ether, ethyl-3-ethoxy propionate, methyl 3-methoxy propionate, cyclohexanone, propylene glycol methyl ether acetate, n-heptanone, ethyl lactate and cyclo A photoresist composition, characterized in that at least one selected from the group consisting of pentanone. The method of claim 10, The organic solvent is a photoresist composition, characterized in that used in an amount of 500 to 2000% by weight relative to the photoresist polymer. (a) coating the photoresist composition of claim 10 on the etched layer to form a photoresist film; (b) exposing the photoresist film; (c) baking the exposed photoresist film; And (d) developing the resultant to obtain a desired pattern. The method of claim 15, And performing a bake process prior to the exposure. The method of claim 15 or 16, The baking process is a photoresist pattern forming method, characterized in that performed at 70 to 200 ℃. A semiconductor device manufactured using the method of claim 15.

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