JPH0543538A - Alpha-(p-(diethylamino)styryl)-n-phenylnitrone and photodecoloring material - Google Patents

Abstract

PURPOSE:To provide the title new nitrone compound high in optical density, getting transparent slowly, thus useful as the main component for photodecoloring materials for contrast enhancement enabling fine resist pattern formation. CONSTITUTION:The objective compound of formula I, which can be obtained by hydrogenation of a compound of formula II followed by reaction with a compound of formula III. The present compound, which is high in optical density for the ray at a wavelength of 436nm (g-ray) and gets transparent slowly, has photodecoloring effect in the form of a thin film about 0.1mum thick; therefore, using this compound, the other objective photodecoloring material with high contrast, resolution and accuracy, capable of forming fine resist patterns, can be obtained. Hence, the present compound is suitable as the main component for the above-mentioned photodecoloring materials for enhancing the image contrast for an object to be taken like a mask for photograph-etching process e.g. in the production of semiconductor integrated circuits.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use as a main component of a photobleaching material for enhancing the contrast of an image of an object such as a mask for a photo-etching process in manufacturing a semiconductor integrated circuit. The present invention relates to a nitrone compound and a photobleaching material containing the nitrone compound.

[0002]

2. Description of the Related Art In lithography technology, a resist image formed by exposing a photoresist to a desired pattern shape and developing it has a shape having a wall that is closer to vertical as the contrast of the exposure image is larger. However, if you are exposing at a very high resolution,
There is a problem that the contrast of the exposed image is lowered and it becomes impossible to obtain a clear resist image.

Therefore, as a method for improving the resolution and the pattern shape, a photobleaching layer for contrast enhancement having an absorption maximum for light having a wavelength of 300 to 450 nm (Japanese Patent Publication No. 40697/1987). -234148
A method for forming a resist pattern using the method described in Japanese Patent Laid-Open Publication No. 2003-242242 has been proposed. Further, in order to improve the resolution, the NA of the stepper lens has been increased (NA: the numerical aperture of the lens). However, although the resolution is improved by increasing the NA, there is a drawback in that the depth of focus cannot be deepened and therefore it is difficult to form a fine resist pattern.

As a means for solving the above problems and forming a fine resist pattern, it is preferable to make the photobleaching layer for contrast enhancement thin, and to make the thin film have a contrast enhancement effect, A photobleachable layer with high optical density and slow transparency is essential. Therefore, a photobleaching material (CEM: having a high optical density and a low transparency rate)
Contrast Enhanced Material
ls) is useful, but none of the conventional ones can be said to be satisfactory, and therefore a nitrone compound useful as a main component of such a photobleaching material is desired.

The present invention has been made in view of the above circumstances.
A novel nitrone compound useful as a main component of a photobleaching material for contrast enhancement, which has a high optical density and a low transparency rate and enables formation of a fine resist pattern, and a photobleaching agent containing the nitrone compound Intended to provide material.

[0006]

Means for Solving the Problems and Actions The inventors of the present invention have conducted extensive studies in order to achieve the above object. As a result, for example, after hydrogenating nitrobenzene, it is reacted with 4-diethylaminocinnamaldehyde. Α- [p- (diethylamino) styryl] -N-phenylnitrone represented by the following formula (1) that can be synthesized is useful as a main component of a photobleaching material for contrast enhancement,
In particular, it has been found that it can exert great power in contrast-enhanced lithography with light having a wavelength of 436 nm (g-line).

[0007]

[Chemical 2]

That is, the novel nitrone compound of the above formula (1) has a photobleaching property for g-line and has an optical density for g-line of about 1.3 to 1.5 times that of known nitrone compounds. It is very large, and the clearing speed is as slow as half or less, and unexpectedly the depth of focus is more than doubled. Therefore, using the nitrone compound of formula (1), photobleaching is possible. It has been found that it is possible to form a fine resist pattern with high contrast, high resolution, and high precision by preparing a conductive material and performing g-line contrast-enhanced lithography using a stepper lens having a high NA. The present invention has been completed.

The present invention will be described in more detail below. The novel nitrone compound of the present invention is represented by the following formula (1): α- [p- (diethylamino) styryl] -N-
It is a phenyl nitrone, and this nitrone compound has a high optical density in the g-line and a low transparency rate,
It is a thin film with a thickness of about 0.1 μm (it is conventionally about 0.5 μm) and has a photobleaching effect.

[0010]

[Chemical 3]

The nitrone compound represented by the above formula (1) is a red crystal having a melting point of 105 to 106 ° C. at room temperature.

The α- [p- (diethylamino) styryl] -N-phenylnitrone of the formula (1) of the present invention is prepared by hydrogenating nitrobenzene and then adding 4- It can be synthesized by reacting diethylaminocinnamaldehyde.

[0013]

[Chemical 4]

In this case, the above reaction is preferably carried out in an organic solvent such as methanol. In addition, hydrogen addition to nitrobenzene is 1.7 to 2.3 with respect to nitrobenzene.
It can be carried out at room temperature in the presence of a catalytic amount of a catalyst such as platinum on carbon, filled with an equivalent amount of hydrogen at a pressure of 1 to 10 kg / cm ² .

Further, when reacting 4-diethylaminocinnamaldehyde with hydrogenated nitrobenzene, 4-diethylaminocinnamaldehyde is added at a ratio of 0.8 to 1.2 mol to 1 mol of nitrobenzene, and an acid such as acetic acid is added. Is preferably performed in the presence of The reaction conditions are preferably 20 to 50 ° C. and 3 to 8 hours. After completion of the reaction, the solvent layer is neutralized and concentrated, followed by recrystallization to obtain the desired α- [p- (diethylamino) styryl] -N-phenylnitrone of the formula (1).

The photobleachable material of the present invention is the above α- [p-
(Diethylamino) styryl] -N-phenyl nitrone, which may be used alone, and the nitrone compound and the binder are dissolved in an organic solvent and mixed,
It can also be used as a rotationally castable photobleaching material. This mixture contains 100 parts (A) of organic solvent (parts by weight,
The same shall apply hereinafter), (B) 0-30 inert organic polymer binder
Parts, preferably 0 to 15 parts, and (C) the above nitrone compound, 1 to 30 parts, preferably 1 to 15 parts are preferably mixed.

Here, as the solvent of the component (A), aromatic hydrocarbons such as toluene, xylene and ethylbenzene,
Examples thereof include a mixture of aromatic hydrocarbons and aliphatic hydrocarbons such as cyclohexane, and a mixture of aromatic hydrocarbons and alcohols such as propanol and butanol.

As the binder of the component (B), a homopolymer or copolymer of vinyl acetate or a partially saponified product thereof, a copolymer of styrene or its derivative, a homopolymer of acrylic acid or methacrylic acid ester, or Examples thereof include copolymers, hydrocarbon-soluble cellulose ethers and cellulose esters, polyvinylpyrrolidone homopolymers and copolymers, polyvinyl alcohols and pullulans having a triorganosilyl group introduced therein.

When the above components (A), (B) and (C) are mixed, the components (B) and (C) may be dissolved in the component (A) to form a solution. preferable.

The resist pattern using the photobleaching material of the present invention can be formed by the lithographic process shown in FIGS. FIG. 1 shows an example in which a photobleaching 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 photobleaching material of the present invention is applied on the photoresist layer 2 by a method such as spin coating to obtain a photobleaching property. The layer 3 is formed, and the photobleachable layer 3 is exposed to ultraviolet rays 4 having a predetermined wavelength by a reduction projection method in a desired pattern shape, that is, the portion A in FIG. 1 is exposed, the photobleachable layer 3 is removed, and development is performed. The resist pattern 5 can be formed by a developing method 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 two in order to separate the photobleaching layer from the photoresist layer.

In the examples shown in FIGS. 1 and 2, since a positive type resist is used as the photoresist layer 2, the portion B remains as the resist pattern 5, but the photoresist has a predetermined level of contrast for light of a predetermined wavelength. Either a positive type or a negative type can be used as long as it shows a threshold value.

[0023]

The α- [p- (diethylamino) styryl] -N-phenylnitrone of the above formula (1) of the present invention is
Especially in the g-line, the optical density is high and the speed of transparency is slow, so it has a photobleaching effect with a thin film of about 0.1 μm, and is capable of forming a fine resist pattern with high contrast, high resolution and high accuracy. Can provide a functional material,
Therefore, it is useful as a main component of a photobleaching material for contrast enhancement which enables formation of a fine resist pattern.

[0024]

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] 90.0 g (731 mmol) of nitrobenzene, 11.3 g of dimethyl sulfoxide, and 29% ammonia water in a 1 liter autoclave.
0 g, 5% platinum-supported catalyst 2.0 g, methanol 260 g
Was added, and the system was charged with hydrogen at a pressure of about 4 kg / cm ² , and the mixture was stirred at room temperature until 2 equivalents of hydrogen with respect to nitrobenzene were completely reacted. Thereafter, further 137.6 g (677 mmol) of 4-diethylaminocinnamaldehyde,
Add 30.0 g of acetic acid and 400 g of methanol, and add 3 at room temperature.
Stir for hours. After filtering the reaction mixture and removing the catalyst, 1000 g of toluene and 1000 g of water were added to extract the toluene layer. To this was added 1000 g of saturated aqueous sodium hydrogen carbonate solution to obtain a toluene layer after neutralization, and the mixture was concentrated under reduced pressure to about 400 g. About 100 g of hexane was added to the concentrated solution for recrystallization to obtain red crystals, which were dried to give 156.4 g (yield 78.4%) and 97% pure α- [p- (diethylamino) styryl. ] -N
-Phenylnitrone was isolated. The obtained α- [p-
(Diethylamino) styryl] -N-phenylnitrone mass spectrum (MS), nuclear magnetic resonance spectrum (N
MR), infrared spectrum (IR) and elemental analysis (CH
The results of N) are shown below. MS: m / e (spectral intensity ratio) 294 (45), 278 (47), 277 (100),
233 (27), 188 (23), 77 (42)

[0026]

[Chemical 5] (A) 6.5-8.0 multiplet 12H (b) 3.46 quartet 4H (c) 1.28 triplet 6H IR: (cm ^-1 ) 3080, 2970, 2940, 2870, 1620,
1585, 1280, 1185, 1050, 820, 7
70 CHN: (%) C ₁₉ H ₂₂ N ₂ O theoretical value C: 77.52 H: 7.53 N: 9.52 measured value C: 77.25 H: 7.57 N: 9.55

Example 2 As a photobleaching material, α- [p
2.5% of each of-(diethylamino) styryl] -N-phenylnitrone and polyvinylpyrrolidone-vinyl acetate copolymer having a molecular weight of about 3,000 and a component ratio of 6: 4.
Ethylbenzene-1-butanol solution (weight ratio 1: 1)
And a 5% aqueous solution of polyvinyl alcohol having a molecular weight of about 10,000 was used as an intervening layer to form a resist pattern according to the lithography process shown in FIG. First, S-181 was formed on the substrate 1 made of a silicon wafer.
3 (manufactured by Shipley Corporation, positive resist) is spin-coated to form a resist layer 2 (FIG. 2A), and then the intervening layer 6 is spin-coated on the resist layer 2 (FIG. 2A).
(B)), and further, the photobleaching material is spin-coated thereon to form a photobleaching layer 7 (FIG. 2 (c)), and ultraviolet rays 4 of 436 nm are selectively applied to the A portion by the reduction projection method. It was exposed (FIG. 2 (d)). Thereafter, the intervening layer 6 and the photobleaching layer 7 were simultaneously removed using pure water, and development was performed using an alkali developing solution to form a resist pattern 5 (FIG. 2).
(E)). The obtained resist pattern had a resolution of 0.50 μm, in which the contrast was enhanced and the depth of focus was doubled or more.

[Brief description of drawings]

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

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

[Explanation of symbols]

 1 substrate 2 photoresist layer 3 photobleaching layer 4 ultraviolet light 5 resist pattern 6 intervening layer 7 photobleaching layer

Claims (2)

[Claims] 1. An α- [p- (diethylamino) styryl] -N-phenylnitrone represented by the following formula (1). [Chemical 1] 2. A photobleaching material containing α- [p- (diethylamino) styryl] -N-phenylnitrone according to claim 1.