JP2850627B2 - Alkali-soluble nitrone compound and photobleachable material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel photobleaching material suitable as a main component of a photobleachable material for enhancing the contrast of an image of a subject, such as a photolithography process mask in the manufacture of semiconductor integrated circuits. The present invention relates to a nitrone compound and a photobleachable material containing the nitrone compound.

[0002]

2. Description of the Related Art In a lithography technique, a photoresist image formed by exposing and developing a photoresist to a desired pattern shape has a shape having walls that are closer to vertical as the contrast of the exposed image is larger. However, when performing exposure with a very high resolution, there is a problem that the contrast of the exposed image is reduced and a clear resist image cannot be obtained.

Therefore, as a method for achieving resolution and resolution of a pattern shape, a photobleachable layer for enhancing contrast having a maximum absorption for light having a wavelength of 300 to 450 nm (Japanese Patent Publication No. 62-40697, Japanese Patent Application Laid-Open No. 62-234148
A resist pattern forming method using the above method has been proposed, and a nitrone compound which is a main component of the photobleachable material has the following structure.

[0004]

Embedded image

[0005] However, since the above-mentioned nitrone compound is insoluble in water and only dissolved in an organic solvent, the photobleachable material containing the above-mentioned nitrone compound as a main component cannot be made water-soluble. For this reason, a step of removing the photobleachable layer with an organic solvent is required before the step of developing the photoresist, or, in the case of using an intervening layer, a step of repelling the intervening layer and the photobleachable layer using pure water. Is required. The former removal method using an organic solvent cannot be carried out with existing equipment, which complicates the process.In addition, the latter method, in which pure water is used together with the intervening layer, completely removes the photobleachable layer. And there is a problem that scum is generated. Accordingly, a photobleachable material (CEM: Contrast Enh) that can be dissolved in pure water without complicating the process.
There is a need for a nitrone compound that is useful as a main component of advanced materials.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a novel alkali-soluble nitrone compound useful as a main component of a photobleachable material for enhancing contrast, which can be dissolved in pure water, and a photobleachable material containing the nitrone compound.

[0007]

The present inventors have made intensive studies to achieve the above object, and as a result, for example, after hydrogenating an alkylnitrobenzoic acid represented by the following general formula (2), By reacting the compound with the compound represented by the following general formula (3), a novel alkali-soluble nitrone compound represented by the following general formula (1) is obtained, and this compound is a photobleachable material for enhancing contrast. Is useful as the main component of
It has been found that it can be very effective in contrast-enhanced lithography at m light.

[0008]

Embedded image (Where R ¹ , R ² , and R ³ are the same or different alkyl groups, aryl groups, or hydrogen atoms, and R ^{4 to} R ⁸ are the same or different alkyl groups, hydrogen atoms, or carboxy groups. , R ^{4 to} R ⁸ are a carboxy group, X is an alkoxy group represented by R ⁹ O—, R ¹⁰
R ¹¹ is a dialkylamino group or a hydrogen atom represented by N—, R ⁹ is an alkyl group, and R ¹⁰ and R ¹¹ are the same or different alkyl groups. n has a value of 0, 1 or 2. )

[0009]

Embedded image (Wherein R ¹ , R ² , and R ³ are the same or different alkyl groups, aryl groups, or hydrogen atoms, and R ^{4 to} R ⁸ are the same or different alkyl groups, hydrogen atoms, or carboxy groups. , R ^{4 to} R ⁸ are a carboxy group, X is an alkoxy group represented by R ⁹ O— or a dialkylamino group represented by R ¹⁰ R ¹¹ N—, and R ⁹ is an alkyl group , R ¹⁰ and R ¹¹ are the same or different alkyl groups. N has a value of 0, 1 or 2.)

Now, the present invention will be described in further detail. The novel nitrone compound of the present invention has the following general formula (1)
Is a nitrone compound represented by the formula:

Here, R ¹ , R ² and R ³ in the above formula (1) are an alkyl group, an aryl group or a hydrogen atom.
As the alkyl group, for example, those having 1 to 8 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group and cyclohexyl group are preferable. Groups, ethyl groups, propyl groups, and butyl groups are more preferably used.
Examples of the aryl group include a phenyl group, a substituted phenyl group, a naphthyl group, a substituted naphthyl group and the like having 6 to 15 carbon atoms.
Are preferable, and among them, a phenyl group, a methylphenyl group, and an ethylphenyl group are more preferably used. R
⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are the same or different alkyl groups, hydrogen atoms or carboxy groups,
At least one of R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ is a carboxy group. Examples of the alkyl group in this case include the same alkyl groups as those exemplified for R ¹ , R ² , and R ³ . X is an alkoxy group represented by R ⁹ O— or a dialkylamino group represented by R ¹⁰ R ¹¹ N—, R ⁹ is an alkyl group, and R ¹⁰ and R ¹¹ are the same or different alkyl groups. . Examples of the alkyl group in this case include the same alkyl groups as those exemplified for R ¹ , R ² , and R ³ . Also, n has a value of 0, 1 or 2, and is preferably 0 or 1.

Here, R ¹ , R ² and R in the above formula (1)
³ is an alkyl group, an aryl group or a hydrogen atom. As the alkyl group, for example, those having 1 to 8 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group and cyclohexyl group are preferable. Groups, ethyl groups, propyl groups, and butyl groups are more preferably used.
Examples of the aryl group include a phenyl group, a substituted phenyl group, a naphthyl group, a substituted naphthyl group and the like having 6 to 15 carbon atoms.
Are preferable, and among them, a phenyl group, a methylphenyl group, and an ethylphenyl group are more preferably used. R
^{4, R 5, R 6,} R 7 and R ⁸ are each the same or different alkyl group, is a hydrogen atom or carboxy group, R ^4,
At least one of R ⁵ , R ⁶ , R ⁷ and R ⁸ is a carboxy group. In this case, as the alkyl group, R ¹ , R ² ,
The same as those exemplified for R ³ can be mentioned. X is an alkoxy group represented by R ⁹ O—, R ¹⁰ R ¹¹ N
-Is a dialkylamino group or a hydrogen atom,
R ⁹ is an alkyl group, and R ¹⁰ and R ¹¹ are the same or different alkyl groups. In this case, the alkyl group is R
^The same as those exemplified for ¹ , R ² and R ³ can be mentioned. Also, n has a value of 0, 1 or 2, and is preferably 0 or 1.

The nitrones of the formula (1) include the nitrones of the following formula.

[0014]

Embedded image

A specific example of the nitrone compound of the above formula (1) is α- [p- (dimethylamino) phenyl]
-N- (4-carboxyphenyl) nitrone, α- [p
-(Diethylamino) phenyl] -N- (4-carboxyphenyl) nitrone, α- [p- (dibutylamino)
Phenyl] -N- (4-carboxyphenyl) nitrone, α- [p- (diethylamino) phenyl] -N-
(3-carboxyphenyl) nitrone, α- [p- (diethylamino) phenyl] -N- (2-carboxyphenyl) nitrone, α- [p- (diethylamino) phenyl] -N- (2-methyl-4-carboxy) Phenyl) nitrone, α- [p- (diethylamino) phenyl] -N
-(2-methyl-3-carboxyphenyl) nitrone,
α- (p-methoxyphenyl) -N- (4-carboxyphenyl) nitrone, α- (p-ethoxyphenyl)-
N- (4-carboxyphenyl) nitrone, α- (o-
Methoxyphenyl) -N- (4-carboxyphenyl)
Nitrone, α- (p-methoxyphenyl) -N- (3-
Carboxyphenyl) nitrone, α- (p-methoxyphenyl) -N- (2-carboxyphenyl) nitrone,
α- (p-methoxyphenyl) -N- (2-methyl-4
-Carboxyphenyl) nitrone, α- (p-ethoxyphenyl) -N- (3-methyl-2-carboxyphenyl) nitrone, α- [p- (dimethylamino) styryl] -N- (4-carboxyphenyl) nitrone , Α-
[P- (Diethylamino) styryl] -N- (4-carboxyphenyl) nitrone, α- [p- (dimethylamino) styryl] -N- (3-carboxyphenyl) nitrone, α- [p- (dimethylamino) Styryl] -N-
(2-carboxyphenyl) nitrone, α- [p- (dimethylamino) styryl] -N- (2-methyl-4-carboxyphenyl) nitrone, α- [p- (diethylamino) styryl] -N- (4- Methyl-2-carboxyphenyl) nitrone, α- (o-methoxystyryl)-
N- (4-carboxyphenyl) nitrone, α- (o-
Methoxystyryl) -N- (3-carboxyphenyl)
Nitrone, α- (p-methoxystyryl) -N- (4-
Carboxyphenyl) nitrone, α- (p-methoxystyryl) -N- (3-carboxyphenyl) nitrone,
α- (o-Methoxystyryl) -N- (2-methyl-4
-Carboxyphenyl) nitrone, α- (p-methoxystyryl) -N- (2-methyl-3-carboxyphenyl) nitrone and the like.

The nitrone compound of the formula (1) of the present invention is obtained from an alkylnitrobenzoic acid represented by the following general formula (2), which is easily available industrially, as a starting material, as shown in the following reaction formula (2). After hydrogenation is performed on the alkylnitrobenzoic acid of the formula to obtain a compound represented by the following general formula (4), the compound can be synthesized by reacting the compound with the compound represented by the following general formula (3).

[0017]

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In this case, the above reaction is preferably performed in an organic solvent such as methanol. In addition, hydrogenation to the alkylnitrobenzoic acid of the formula (2) is performed by adding 1.7 to 2.3 equivalents of hydrogen to the alkylnitrobenzoic acid for 1 to 10 k.
The reaction can be performed at room temperature in the presence of a catalyst such as platinum on carbon in a catalytic amount by filling at a pressure of g / cm ² .

Further, when the compound of the formula (3) is reacted with the hydrogenated alkylnitrobenzoic acid, the compound of the formula (3) is added in an amount of 0.8 to 1 to 1 mol of the alkylnitrobenzoic acid.
It is desirable to add at a ratio of 2 mol and carry out in the presence of an acid such as acetic acid. The reaction conditions are 20 to 50 ° C. for 3 hours.
It is preferable to set it to 8 hours. After completion of the reaction, the precipitated crystals are separated by filtration, and the crystals are washed with an appropriate solvent to obtain the desired nitrone compound of the formula (1).

The photobleachable material of the present invention contains the nitrone compound of the above formula (1), and the nitrone compound is mixed with a binder, an organic base, a surfactant and the like in water or an organic solvent or a water-organic solvent mixture. Dissolve in the liquid and mix
It can be used as a photobleachable material that can be cast in rotation. This photobleachable material comprises (A) 0-100 parts of water (parts by weight, the same applies hereinafter), preferably 50-100 parts, (B) 0-100 parts of an organic solvent, preferably 0-50 parts, (C) 1 to 30 parts, preferably 1 to 15 parts of a water-soluble polymer binder,
(D) 1 to 30 parts of the above nitrone compound, preferably 1 to 30 parts
15 parts, (E) 1 to 30 parts of an organic base, preferably 1 to 1
5 parts and 0 to 2 parts of (F) surfactant, preferably 0 to 1
A mixture of parts is preferred.

Here, as the organic solvent of the component (B),
Examples include alcohols such as ethanol, 1-propanol and 2-propanol, and ethers such as tetrahydrofuran and 1,4-dioxane.

Examples of the binder as the component (C) include partially saponified vinyl acetate polymers, polyvinyl alcohol, water-soluble cellulose ethers and cellulose esters, homopolymers or copolymers of polyvinylpyrrolidone, and pullulans. .

Examples of the organic base as the component (E) include tetramethylammonium hydroxide solution, tetrabutylammonium hydroxide solution, tris (hydroxymethyl) aminomethane, 2,2 ′, 2 ″ -nitrilotriethanol, pyridine, triethylamine and the like. Is mentioned.

As the surfactant of the component (F), a fluorine-containing surfactant and the like can be mentioned.

A resist pattern using the photobleachable material of the present invention can be formed by the lithography process shown in FIGS. FIG. 1 shows an example in which a photobleachable layer is directly formed on a photoresist layer. First,
A photoresist layer 2 is formed on a substrate 1 such as a silicon wafer by a method such as spin coating, and the photobleachable material of the present invention is applied on the photoresist layer 2 by a method such as spin coating to form a photobleachable layer 3. Is formed, and the photobleachable layer 3 is exposed to ultraviolet rays 4 having a predetermined wavelength in a desired pattern shape by a reduced projection method, that is, the portion A in FIG. 1 is exposed, the photobleachable layer 3 is removed with water, and development is performed. The resist pattern 5 can be formed by a method of developing using a liquid.

FIG. 2 shows an example in which a thin intervening layer 6 made of a neutral substance such as polyvinyl alcohol is provided between the photobleachable layer and the photoresist layer in order to isolate the photobleachable layer from the photoresist layer. In this case, since the photobleachable material of the present invention is water-soluble, the photobleachable layer 3 and the intervening layer 6 can be simultaneously washed away with water, and no scum is generated.

[0027]

The nitrone compound of the above formula (1) of the present invention has a photobleaching property especially for g-line and i-line, is soluble in alkali, and has high contrast, high resolution, high precision and fineness. It is possible to provide a water-soluble photobleachable material capable of forming a resist pattern, and thus is useful as a main component of a water-soluble photobleachable material for contrast enhancement that enables formation of a fine resist pattern. is there.

[0028]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 In a 1-liter autoclave, 122.2 g (731 mmol) of p-nitrobenzoic acid was added.
l), 11.3 g of dimethylsulfoxide, 2.0 g of a 5% platinum-supported catalyst and 260 g of methanol were added, and the system was filled with hydrogen at a pressure of about 4 kg / cm ² , and an equivalent amount of hydrogen relative to p-nitrobenzoic acid was added. The mixture was stirred at room temperature until the reaction was completed. After filtering the reaction mixture and removing the catalyst, 4
120.0 g of diethylaminobenzaldehyde (67
7 mmol), 30.0 g of acetic acid and 100 g of methanol were added, and the mixture was stirred at room temperature for 5 hours. After filtering out the precipitated crystals,
Washing with methanol yielded yellow crystals, which were dried and yielded 187.6 g (88.7% yield) of α- [p- (diethylamino) phenyl] -N- (4-
(Carboxyphenyl) nitrone was isolated. Obtained α
Mass spectrum of-[p- (diethylamino) phenyl] -N- (4-carboxyphenyl) nitrone (M
The results of S), nuclear magnetic resonance spectrum (NMR), infrared spectrum (IR) and elemental analysis are shown below.

< MS: m / e (spectral intensity ratio)> 312 (16.5), 297 (8.1), 296 (1
5.1), 281 (24.6), 176 (100.
0), 32 (31.5)

[0031]

Embedded image

<IR: (cm ⁻¹ )> 3437, 2976, 2900, 1705, 1605,
1572, 1523, 1410, 1275, 1180,
1155, 1122, 1080, 1036, 1011,
879, 860, 817

<Elemental analysis value: (%) C ₁₈ H ₂₀ N ₂ O ₃ > Theoretical value C: 69.2 H: 6.4 N:
9.0 Found C: 68.1 H: 6.2 N:
8.5

Example 2 Instead of p-nitrobenzoic acid, 132.4 g of 3-methyl-4-nitrobenzoic acid (7
Synthesis was carried out in the same manner as in Example 1 except that 31 mmol) was used. As a result, 211.3 g (yield 95.6 g) was obtained.
%), 95% pure α- [p- (diethylamino) phenyl] -N- (2-methyl-4-carboxyphenyl)
Nitron was isolated. The analysis results of the obtained compound are shown below.

< MS: m / e (spectral intensity ratio)> 326 (20.3), 311 (15.3), 310
(6.7), 295 (8.9), 176 (100.
0), 32 (26.0)

[0036]

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<IR: (cm ⁻¹ )> 3435, 3053, 2974, 2902, 1703,
1591, 1524, 1408, 1273, 1176,
1155, 1122, 1078, 1039, 1009,
877, 854, 817

<Elemental analysis value: (%) C ₁₉ H ₂₂ N ₂ O ₃ > Theoretical value C: 69.9 H: 6.7 N:
8.6 Actual value: C: 67.4 H: 6.4 N:
8.0

Example 3 Instead of 4-diethylaminobenzaldehyde, 92.2 g of p-anisaldehyde
(677 mmol), and the synthesis was carried out in the same manner as in Example 1, yielding 162.0 g (yield 8
8.2%) and 96% pure α- (p-methoxyphenyl) -N- (4-carboxyphenyl) nitrone. The analysis results of the obtained compound are shown below.

[0040]

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<IR: (cm ⁻¹ )> 3456, 3109, 3157, 2968, 2841,
2673, 2551, 1703, 1686, 1603,
1508, 1431, 1323, 1292, 1251,
1169, 1070, 1028, 870, 841, 8
06

<Elemental analysis value: (%) C₁₅H₁₃N O_Four> Theoretical value C: 66.4 H: 4.8 N:
5.2 Actual value: C: 66.1 H: 4.9 N:
4.8

Example 4 132.4 g of 3-methyl-4-nitrobenzoic acid (73) instead of p-nitrobenzoic acid
1 mmol), 4-dimethylaminocinnamaldehyde 11 instead of 4-diethylaminobenzaldehyde
Synthesis was carried out in the same manner as in Example 1 except that 8.6 g (677 mmol) was used, and the yield was 213.8 g.
(Yield 97.4%), α- [p- (dimethylamino) styryl] -N- (2-methyl-4-carboxyphenyl) nitrone having a purity of 96% was isolated. The analysis results of the obtained compound are shown below.

[0044]

Embedded image

<IR: (cm ⁻¹ )> 3446, 3037, 2891, 2812, 1701,
1593, 1524, 1487, 1435, 1367,
1329, 1275, 1234, 1232, 1165,
1126, 1105, 1018, 984, 945, 92
4,920,860,841,810

<Elemental analysis value: (%) C ₁₉ H ₂₀ O ₃ N ₂ > Theoretical value C: 70.4 H: 6.2 N:
8.6 Observed value C: 69.9 H: 6.3 N:
8.4

[Example 5] α- [p
-(Diethylaminophenyl) -N- (4-carboxyphenyl) nitrone 4.5%, polyvinylpyrrolidone-vinyl acetate copolymer having a molecular weight of about 3,000 and a component ratio of 6: 4 3.5%, 10% tetrahydroxide 1 using an aqueous solution of 38.0% of n-butylammonium solution and 0.25% of Florado FC-430 (manufactured by Sumitomo 3M).
A resist pattern was formed according to the lithography process shown in FIG. First, S-1 was added to a substrate 1 made of a silicon wafer.
813 (Shipley Corp., positive resist) is spin-coated to form a resist layer 2 (FIG. 1 (a)), and then the photobleachable material is spin-coated on the resist layer 2 to form a photobleachable layer 3 (FIG. 1B), and the portion A was selectively exposed to ultraviolet light 4 of 436 nm by the reduced projection method (FIG. 1).
(C)). Thereafter, the photobleachable layer 3 was removed using pure water, and development was performed using an alkaline developer to form a resist pattern 5 (FIG. 1D). The obtained resist pattern had a 0.5 μm resolution with enhanced contrast.

Example 6 As a photobleachable material, α- [p
-(Diethylaminophenyl) -N- (2-methyl-4
4.5% of carboxyphenyl) nitrone, 3.5% of polyvinylpyrrolidone-vinyl acetate copolymer having a molecular weight of about 3,000 and a component ratio of 6: 4, 2.0% of tris (hydroxymethyl) aminomethane and Florad FC- 430
Using a 0.25% aqueous solution (manufactured by Sumitomo 3M Limited), a resist pattern was formed according to the lithography process shown in FIG. First, a substrate 1 consisting of a silicon wafer
To THMR-iP1800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.
A positive resist is spin-coated to form a resist layer 2 (FIG. 1A), and then the photo-bleachable material is spin-coated on the resist layer 2 to form a photo-bleachable layer 3 (FIG. 1).
(B)) 365n is selectively applied to the portion A by the reduced projection method.
m ultraviolet rays 4 were exposed (FIG. 1 (c)). Thereafter, the photobleachable layer 3 was removed using pure water, and development was performed using an alkaline developer to form a resist pattern 5 (FIG. 1).
(D)). The obtained resist pattern had a 0.36 μm resolution with enhanced contrast.

Example 7 α- [p- (Diethylamino) phenyl] -N- (2-methyl-4-carboxyphenyl) nitrone was replaced with α- (p-methoxyphenyl) -N- (4-carboxy) When a resist pattern was formed in the same manner as in Example 6 except that (phenyl) nitrone was used, the obtained resist pattern had a 0.4 μm resolution with enhanced contrast.

Example 8 As a photobleachable material, α- [p
-(Dimethylamino) styryl] -N- (2-methyl-
4-carboxyphenyl) nitrone 4.5%, polyvinylpyrrolidone having a molecular weight of about 3,000 and a component ratio of 6: 4, vinyl acetate copolymer 3.5%, tris (hydroxymethyl) aminomethane 2.0% and Florard FC -430
A resist pattern was formed in the same manner as in Example 5 using a 0.25% pure water-1-propanol solution (weight ratio 65:35) (manufactured by Sumitomo 3M Limited).
The obtained resist pattern had a 0.5 μm resolution with enhanced contrast.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a lithography process using a photobleachable material of the present invention.

FIG. 2 is a process chart showing another example of a lithography process using the photobleachable material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Photoresist layer 3 Photobleachable layer 4 Ultraviolet light 5 Resist pattern 6 Intermediate layer 7 Photobleachable layer

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenichi Ito 28-1, Nishifukushima, Oku-ku, Nikushiro-mura, Nakakibijo-gun, Niigata Prefecture Synthetic Technology Research Laboratory, Shin-Etsu Chemical Co., Ltd. (56) References US Patent No. (58) Field surveyed (Int. Cl. ⁶ , DB name) C07C 291/02 C09K 9/02 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. An alkali-soluble nitrone compound represented by the following general formula (1). Embedded image (Wherein R ¹ , R ² , and R ³ are the same or different alkyl groups, aryl groups, or hydrogen atoms, and R ^{4 to} R ⁸ are the same or different alkyl groups, hydrogen atoms, or carboxy groups. , R ^{4 to} R ⁸ are a carboxy group, X is an alkoxy group represented by R ⁹ O— or a dialkylamino group represented by R ¹⁰ R ¹¹ N—, and R ⁹ is an alkyl group , R ¹⁰ and R ¹¹ are the same or different alkyl groups. N has a value of 0, 1 or 2.) 2. A photobleachable material containing the alkali-soluble nitrone compound according to claim 1.