JPH04365048A - Photosensitive composition material - Google Patents

Abstract

PURPOSE:To provide a photosensitive composition material with high photosensitivity and usable for the light with the wide-range wavelength by containing a specific compound and alkali-soluble polymer. CONSTITUTION:A compound expressed by the formula is contained in an alkali- soluble polymer such as cresol resin, where R<1> indicates alkyl group, substituted alkyl group, allyl group or substituted allyl group, R<2> indicates alkyl group, substituted alkyl group, allyl group or substituted allyl group, stil group, substituted stil group, vinyl group or substituted vinyl group, and R<3>-R<6> independently indicate hydrogen atom, alkyl group, allyl group, substituted allyl group, halogen atom or alkoxy group respectively. R<3> and R<4>, R<4> and R<5>, R<6> and R<6> may be bound to each other to form a benzene ring or a heterocycle together with carbon atom bound to them. The added quantity of the compound expressed by the formula in a photosensitive composition material is preferably set to 1-50wt.% against the whole solid of the photosensitive composite material.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is capable of forming fine resist patterns when manufacturing lithographic printing plates, proof sheets for multicolor printing, drawings for overhead projectors, and even integrated circuits of semiconductor devices. This invention relates to a positive photosensitive composition.

0002

[Prior Art] Orthoquinonediazide compounds are conventionally known as photosensitive substances that act positively and are solubilized by actinic rays in applications such as lithographic printing plates, and are actually widely used in lithographic printing plates. It's here. Examples of such orthoquinonediazide compounds include those described in U.S. Pat. Nos. 2,766,118 and 2,767.
, No. 092, No. 2,772,972, No. 2,
No. 859,112, No. 2,907,665, No. 3,046,110, No. 3,046,111, No. 3,046,115, No. 3,046,1
No. 18, No. 3,046,119, No. 3,04
No. 6,120, No. 3,046,121, No. 3
, No. 046,122, No. 3,046,123, No. 3,061,430, No. 3,102,809
No. 3,106,465, No. 3,635,
It is described in numerous publications including the specifications of No. 709 and No. 3,647,443.

These orthoquinonediazide compounds are
These methods take advantage of the fact that irradiation with actinic light causes decomposition to produce a five-membered ring carboxylic acid, which becomes alkali-soluble, but none of them showed sufficient sensitivity. This is because it is difficult to achieve photochemical sensitization with some orthoquinone diazide compounds, and their quantum yield essentially does not exceed 1. In addition, because the photosensitive wavelength is fixed, it has poor light source suitability, making it difficult to provide white light safety.Furthermore, since absorption in the deep UV region is large, it is difficult to improve the resolution of photoresists by using low wavelength light. Not suitable for this purpose.

[0004] In order to overcome these drawbacks, for example, Japanese Patent Publication No. 48-12242, Japanese Patent Application Laid-Open No. 52-40125,
Although methods described in various publications and specifications such as US Pat. No. 4,307,173 have been attempted, improvements have remained insufficient. Recently, several proposals have been made for the purpose of developing new positive-working photosensitive materials to replace orthoquinone diazide compounds. One such example is a polymer compound having an orthonitrocarbinol ester group, which is described in Japanese Patent Publication No. 56-2696. However, even in this case, sufficient sensitivity could not be obtained.

On the other hand, as a pattern forming method for manufacturing electronic components such as semiconductor elements, magnetic valve memories, and integrated circuits, a method using photoresist is generally used. There are two types of photoresists: negative type, in which the irradiated area becomes insoluble in a developer when exposed to light, and positive type, in which the irradiated area becomes soluble in a developer. Negative type has better sensitivity than positive type,
Until recently, it has been the mainstream photoresist because it has excellent adhesion to the substrate and chemical resistance necessary for wet etching. However, with the increasing density and integration of semiconductor devices, the line width and spacing of patterns have become extremely small, and dry etching has come to be used for substrate etching. Nowadays, high resolution and high dry etching resistance are desired, and positive photoresists are now the mainstream. In particular, among positive photoresists, it has excellent sensitivity, resolution, and dry etching resistance.
(1976) (J.C. Strieter, K.
odak Microelectronics Se
Minor Proceedings, 116 (197
Alkali-developable positive photoresists based on alkali-soluble novolak resins, such as those described in 6)), are currently widely used.

However, in recent years, electronic devices have become multi-functional,
As sensitivity increases, there is a strong demand for finer patterns in order to achieve higher density and higher integration. In response to these demands, photosensitive compositions that combine conventional orthoquinone diazide photosensitivity with alkali-soluble polysiloxane or silicone polymers such as polysilmethylene, such as JP-A-61-256347 and JP-A-61-61- 14
No. 4639, No. 62-159141, No. 62-191
No. 849, No. 62-220949, No. 62-2291
Photosensitive compositions described in publications such as No. 36, No. 63-90534, and No. 63-91654, JP-A-62-136
A photosensitive composition is proposed in which the polysiloxane/carbonate black copolymer described in the publication No. 638 is combined with an effective amount of an onium salt. However, these silicone polymers are extremely difficult to manufacture due to the addition of alkali-soluble functions, and their stability over time is also insufficient.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel positive-working photosensitive composition in which the above-mentioned problems are solved. That is, the object of the present invention is to provide a novel positive photosensitive composition that has high photosensitivity and can be used with light of a wide range of wavelengths.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present inventor searched for a new positive photosensitive composition to replace orthoquinone diazide, and found that It has been discovered that a clear positive image can be obtained by containing the compound represented by the general formula (I), and the present invention has been completed.

That is, the present invention is a positive photosensitive composition characterized by containing a compound represented by the following general formula (I) and an alkali-soluble polymer.

0010

[Case 2]

In the formula, R1 represents an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group, and R2 represents an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, a styryl group, a substituted styryl group, a vinyl group, or It represents a substituted vinyl group, and R3, R4, R5 and R6 each independently represent a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, a halogen atom or an alkoxy group.

[0012] Also, R3 and R4, R4 and R5, R
5 and R6 may be bonded to each other to form a benzene ring or a heterocycle together with the carbon atom to which they are bonded. At present, the reason why a clear positive image is obtained is not clear, but in the unexposed area, the compound represented by general formula (I) and the alkali-soluble polymer interact, and the solubility of the photosensitive layer in the alkaline developer increases. On the other hand, in the exposed area, when exposed to light, the compound of general formula (I) decomposes and generates acid, increasing its solubility in an alkaline developer, resulting in a positive image. Presumed.

The positive-working photosensitive composition of the present invention will be explained in detail below. The compound of general formula (I) used in the present invention is described in the literature of Dee Harrison et al.
on et al., Journal of the Chemi
calSociety, pp. 2157-2160 (1
General formula (II) synthesized according to the method described in 960))
2-substituted-3-hydroxy-4(3H)-quinazolinone derivative represented by

[0014]

[Chemical 3]

(In the formula, R2, R3, R4, R5
and R6 are defined as in the general formula (I)) and R1 -SO2 -Cl (wherein R1 is defined as in the general formula (I))
It can be synthesized by carrying out a dehydrochlorination condensation reaction of an organic sulfonic acid chloride (defined in the same manner as in case I)) in the presence of a dehydrochlorinating agent. General formula (I
The alkyl groups of R1 and R2 in ) may be linear, branched, or cyclic, and preferably have 1 to 1
It has 0 carbon atoms. For example, methyl group, ethyl group,
Examples include butyl group, hexyl group, octyl group, and the like.

The substituted alkyl groups of R1 and R2 are:
The above-mentioned alkyl group is a halogen atom such as a chlorine atom, a carbon atom number of 1 to 1, such as a methoxy group, etc.
5, which is substituted with an alkoxy group or the like. Specifically, 2-chloroethyl group, 2-methoxyethyl group, etc. are included. Further, the aryl group of R1 and R2 is preferably a monocyclic or bicyclic group, and includes, for example, a phenyl group, an α-naphthyl group, a β-naphthyl group, and the like. R
The substituted aryl group of 1 and R2 is an aryl group as described above, for example, an alkyl group having 1 to 5 carbon atoms such as a methyl group or an ethyl group, or an alkyl group having 1 to 5 carbon atoms such as a methoxy group or an ethoxy group. Included are alkoxy groups, for example those substituted with halogen atoms such as chlorine atoms. Specific examples include methylphenyl group, dimethylphenyl group, methoxyphenyl group, chlorophenyl group, methoxyphenyl group, and methoxynaphthyl group. Substituents for the substituted vinyl group and substituted styryl group for R2 include an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a halogen atom. Specific examples include p-methoxystyryl group, p-chlorostyryl group, p-methylstyryl group, and 2-propenyl group. In general formula (I), R3, R4, R5 and R6 are each independently selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, a halogen atom, and an alkoxy group. The alkyl group preferably has 1 to 5 carbon atoms, and includes methyl, ethyl, propyl, butyl, and the like.

The substituted alkyl group is a group in which the above-mentioned alkyl group is substituted with a halogen atom, an alkoxy group having 1 to 5 carbon atoms, or the like. Specifically, 2-chloroethyl group, 2-methoxyethyl group, etc. are included. The aryl group is preferably a monocyclic group, and includes, for example, a phenyl group. The substituted aryl group is an aryl group having 1 to 1 carbon atoms, such as a methyl group or an ethyl group.
5 alkyl groups, for example, alkoxy groups having 1 to 5 carbon atoms such as methoxy groups and ethoxy groups, and groups substituted with halogen atoms such as chlorine atoms. Specific examples include methylphenyl group, dimethylphenyl group, methoxyphenyl group, and chlorophenyl group. Also R3
and R4, R4 and R5, and R5 and R6 may be bonded to each other to form a benzene ring or a heterocycle with the carbon atom to which they are bonded. Examples of the above include a benzene ring, a pyridine ring, a furan ring, a piperidine ring, and the like.

Examples of compounds of general formula (I) used in the present invention are listed below, but the scope of the present invention is not limited thereto.

[0019]

[C4]

[0020]

[C5]

[0021]

[C6]

[0022]

[C7]

[0023]

[Chemical formula 8]

The compound represented by the general formula (I) can be used singly or as a mixture of several kinds. The amount of the compound represented by general formula (I) added to the photosensitive composition is preferably in the range of 1 to 50% by weight, more preferably 5 to 30% by weight based on the total solid content of the photosensitive composition. .

The alkali-soluble polymer used in the present invention preferably has a phenolic hydroxy group, a carboxylic acid group, a sulfonic acid group, an imide group, a sulfonamide group, an N
- A polymer having an acidic group with a pKa of 11 or less, such as a sulfonylamide group, an N-sulfonylurethane group, or an active methylene group. Suitable alkali-soluble polymers include novolac type phenolic resins, specifically phenol-formaldehyde resins, o-cresol-formaldehyde resins, m-cresol-formaldehyde resins,
Examples include p-cresol-formaldehyde resin, xylenol-formaldehyde resin, and cocondensates thereof. Furthermore, as described in JP-A-50-125806, in addition to the above-mentioned phenol resins, 3-carbon resins such as t-butylphenol-formaldehyde resins are also used.
A condensate of formaldehyde and phenol or cresol substituted with an alkyl group of 1 to 8 may be used in combination. Also, polymers containing phenolic hydroxy group-containing monomers such as N-(4-hydroxyphenyl)methacrylamide, p-hydroxystyrene, o-
Hydroxystyrene, m-isopropenylphenol,
Single or copolymerized polymers such as p-isopropenylphenol, and partially etherified or partially esterified polymers of these polymers can also be used.

Further, polymers containing carboxyl group-containing monomers such as acrylic acid and methacrylic acid as copolymerization components, carboxyl group-containing polyvinyl acetal resins described in JP-A-61-267042, and JP-A-63-124047
The carboxyl group-containing polyurethane resin described in the above publication is also preferably used. Furthermore, polymers containing N-(4-sulfamoylphenyl)methacrylamide, N-phenylsulfonylmethacrylamide, and maleimide as copolymerization components, and active methylene group-containing polymers described in JP-A-63-127237 can also be used. .

These alkali-soluble polymers can be used singly or as a mixture of several types. The amount of the alkali-soluble polymer added to the photosensitive composition is preferably 10 to 90% by weight, more preferably 30 to 80% by weight based on the total solid content of the photosensitive composition.

[0028] If necessary, dyes, pigments, plasticizers, and compounds (sensitizers) that increase the acid generation efficiency of the acid-generating compound may be added to the positive photosensitive composition of the present invention. be able to. Such sensitizers include
Merocyanine dyes, cyanine dyes, etc. can be used, but are not limited to these.

The ratio of these sensitizers to the compound represented by general formula (I) is preferably 0.01/1 to 0.01/1 in molar ratio.
It is used in a weight ratio of 0.1/1 to 5/1. Further, dyes can be used as colorants in the positive photosensitive composition of the present invention, and suitable dyes include oil-soluble dyes and basic dyes. Specifically, for example, Oil Yellow #101, Oil Yellow #130,
Oil pink #312, oil green BG, oil blue BOS, oil black BY, oil black BS
, Oil Black T-505 (manufactured by Oriental Chemical Industry Co., Ltd.), Crystal Violet (CI4255)
5), methyl violet (CI42535), rhodamine B (CI45170B), malachite green (C
I42000), methylene blue (CI52015), and the like.

These dyes can be added to the photosensitive composition in an amount of 0.01 to 10% by weight, preferably 0.1 to 3% by weight, based on the total solid content of the photosensitive composition. A cyclic acid anhydride and other fillers can be added to the composition of the present invention in order to further increase sensitivity. As a cyclic acid anhydride, U.S. Patent No. 4,115,128
Phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3, as described in No.
6-endoxy-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride,
Examples include pyromellitic acid. By preferably containing these cyclic acid anhydrides in an amount of 1 to 15% by weight based on the total solid content of the photosensitive composition, the sensitivity can be increased up to about 3 times.

When the positive-working photosensitive composition of the present invention is used as a material for a lithographic printing plate, it is dissolved in a solvent that dissolves the above-mentioned components and coated on a support. Furthermore, for resist materials such as semiconductors, it is used as it is dissolved in a solvent. The solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, 1-methoxy- 2-propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N,N-dimethylacetamide, N,N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyl lactone, toluene, acetic acid Examples include ethyl, and these solvents can be used alone or in combination. The concentration of the above components (total solid content including additives) in the solvent is preferably 2 to 50% by weight. In addition, when applied and used,
The coating amount varies depending on the application, but for example, for photosensitive planographic printing plates, the solid content is generally 0.5 to 3.0 g.
/m2, and in the case of photoresists, the solid content is generally preferably 0.1 to 3.0 g/m2. As the coating amount decreases, the photosensitivity increases, but the film properties of the photosensitive film deteriorate.

When producing a lithographic printing plate using the positive-working photosensitive composition of the present invention, the support may be, for example,
Paper, paper laminated with plastic (e.g. polyethylene, polypropylene, polystyrene, etc.), metal plates such as aluminum (including aluminum alloys), zinc, copper, etc., e.g. cellulose diacetate, cellulose triacetate, cellulose propionate. Plastic films such as cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc., paper laminated or vapor-deposited with the above metals, or plastic films, etc. included. Among these supports, aluminum plates are particularly preferred because they are extremely dimensionally stable and inexpensive. In addition, special public service 1977-183
Also preferred are composite sheets in which an aluminum sheet is bonded onto a polyethylene terephthalate film, such as that described in Publication No. 27. Brush graining, which roughens the surface of an aluminum plate with a nylon brush while pouring slurry of abrasive particles on the surface of the aluminum plate, ball graining, and graining by liquid honing.
Mechanical methods such as buff graining, HF and AlCl3
, chemical graining using HCl as an etchant,
After the surface is grained by electrolytic graining using nitric acid or hydrochloric acid as the electrolyte, or by composite graining by combining these surface roughening methods, it is etched with acid or alkali as necessary, and then etched with sulfuric acid, Preferably, the aluminum is anodized in phosphoric acid, boric acid, chromic acid, sulfamic acid, or a mixed acid thereof using a direct current or alternating current power source to form a strong passive film on the aluminum surface. Although the aluminum surface becomes hydrophilic with such a passive film itself, if necessary, the aluminum surface may be further hydrophilized.
No. 714,066 and U.S. Patent No. 3,181,4
Silicate treatment (sodium silicate, potassium silicate) as described in US Pat. No. 61, US Pat. No. 2,946,63
8, the phosphomolybdate treatment described in U.S. Pat. No. 3,201,247, and the phosphomolybdate treatment described in U.S. Pat.
Alkyl titanate treatment as described in German Patent No. 1,108,559, polyacrylic acid treatment as described in German Patent No. 1,091,443, German Patent No. 1,134,093 Book and British Patent Nos. 1 and 23
0,447, phosphonic acid treatment described in Japanese Patent Publication No. 44-6409, and phytic acid treatment described in U.S. Pat. No. 3,307,951. Processing, JP-A-58-
Composite treatment consisting of a hydrophilic organic polymer compound and a divalent metal described in JP-A No. 16893 and JP-A-58-16291, and a sulfonic acid group described in JP-A-59-101651. Particularly preferred are those which have been subjected to hydrophilic treatment by undercoating with a water-soluble polymer having the following. Other hydrophilic treatment methods include U.S. Patent No. 3,658,
Mention may be made of the silicate electrodeposition described in No. 662.

[0033] Also, it is preferable to use a material that has been subjected to graining treatment, anodization, and then sealing treatment. Such a sealing treatment is performed by immersion in hot water and a hot aqueous solution containing an inorganic or organic salt, a steam bath, and the like. When the positive photosensitive composition of the present invention is used as a photoresist, substrates made of various materials such as copper plates or copper-plated plates, silicon plates, stainless steel plates, glass plates, etc. can be used as supports.

The positive photosensitive composition of the present invention is coated on the above-mentioned support by a known coating technique. Examples of the above coating techniques include spin coating, wire bar coating, dip coating, air knife coating, roll coating, blade coating, curtain coating, and spray coating. The positive photosensitive composition layer coated as described above is dried at 40 to 150° C. for 30 seconds to 10 minutes using a hot air dryer, an infrared dryer, or the like.

Photosensitive lithographic printing plates, photoresists, etc. containing the positive-working photosensitive composition of the present invention are usually subjected to imagewise exposure and development steps. Examples of active light sources used for imagewise exposure include mercury lamps, metal halide lamps, xenon lamps, chemical lamps, and carbon arc lamps. Examples of radiation include electron beams, X-rays, ion beams, and deep ultraviolet rays. As a light source for photoresist, g-line, i-line, and deep-UV light are preferably used. Scanning exposure with a high-density energy beam (laser beam or electron beam) can also be used in the present invention. Examples of such laser beams include helium/neon lasers, argon lasers, krypton ion lasers, helium/cadmium lasers, and KrF excimer lasers.

The developing solution used for developing the positive photosensitive composition of the present invention includes sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, tribasic sodium phosphate, and dibasic sodium phosphate. Aqueous solutions of inorganic alkaline agents such as tertiary ammonium phosphate, diammonium phosphate, sodium metasilicate, sodium bicarbonate, aqueous ammonia, etc. and organic alkaline agents such as tetraalkylammonium hydride, etc. are suitable; is added so that the concentration thereof is 0.1 to 10% by weight, preferably 0.5 to 5% by weight.

[0037] Furthermore, a surfactant or an organic solvent such as alcohol can be added to the alkaline aqueous solution, if necessary.

[0038]

Effects of the Invention The positive photosensitive composition of the present invention has high photosensitivity and can be used with light of a wide range of wavelengths.

[0039]

[Examples] The present invention will be explained in more detail with reference to Examples below, but the content of the present invention is not limited thereto. [Examples 1 to 8] A 0.24 mm thick 2S aluminum plate was degreased by immersing it in a 10% aqueous solution of tribasic sodium phosphate kept at 80°C for 3 minutes, and then grained with a nylon brush. The film was etched for about 10 minutes, and then desmutted with a 3% aqueous solution of sodium hydrogen sulfate. This aluminum plate was anodized in 20% sulfuric acid at a current density of 2 A/dm2 for 2 minutes.

Next, using the compounds shown in Table 1 below,
Eight types of photosensitive liquids [A]-1 to [A] as disposed of below.
-8 was prepared. This photosensitive solution was applied onto an anodized aluminum plate and dried at 100° C. for 2 minutes to produce each photosensitive lithographic printing plate. The coating amount at this time was adjusted to 1.5 g/m2 in terms of dry weight. Photosensitive liquid formulation [A] Compound of general formula (I)
0.2g Cresol formaldehyde novolac resin 1
．． 0g Oil Blue #603 (manufactured by Orient Kogyo Co., Ltd.) 0.01g Methyl ethyl ketone

5g methyl cellosolve
A gray scale with a density difference of 0.15 was brought into close contact with the photosensitive layer of the lithographic printing plate obtained in an amount of 15 g, and exposed for 2 minutes from a distance of 50 cm using a 2 KW high pressure mercury lamp. The exposed planographic printing plate is DP-4
(Product name: manufactured by Fuji Photo Film Co., Ltd.) was immersed in an 8-fold diluted aqueous solution for 60 seconds at 25° C., and all clear positive images were obtained. It is shown in Table 1.

[0041]
Table 1──────────
──────────────────────────
─ Example Photosensitive liquid Compound of general formula (I) Number of gray scale steps ──
──────────────────────────
───────── 1 [A]
-1 Compound (1)
5 2 [A]-
2 〃 (2)
4 3 [A]
-3 〃 (3)
5 4 [A
〃-4 〃 (4)
6 5 [
A]-5 (5)
7 6
[A]-6 〃 (6)
3 7
[A]-7 〃 (7)
3 8
[A]-8 〃 (8)
3──────────
──────────────────────────
[Examples 9 to 13] The following photosensitive liquid [B] was applied with a spinner onto a silicon wafer with a thickness of 2 mm, and dried on a hot plate at 90°C for 2 minutes so that the film thickness when dried was 1 μm. It was adjusted. Photosensitive liquid formulation [B] Compound of general formula (I)
0.2g Cresol formaldehyde novolac resin 1
．． 0g perylene
0
．． 003g ethyl cellosolve acetate
7.5g

Table 2 ────────
────────────────────
Example Photosensitive liquid
Compound of general formula (I) ──────
────────────────────────
9 [B]-1
Compound (1)
10 [B]-2
〃 (4) 11
[B]-3
〃 (5) 12
[B]-4 〃 (
8) 13 [B]-5
(12)
──────────────────────
────────Next, the obtained resist was heated to a wavelength of 436 nm.
A resist pattern was formed by exposing the resist to light using a reduction projection exposure device (stepper) using monochromatic light, and developing with a 2.4% aqueous solution of tetramethylammonium hydroxide for 60 seconds. As a result, good patterns of 0.8 μm lines and spaces were obtained in all samples. [Example 14] The resist of Example 11 was irradiated with 254 nm ultraviolet rays using a contact exposure method through a glass mask.
Thereafter, development was performed in the same manner as in Example 11, and a good pattern of 0.7 μm lines and spaces was obtained in all samples.

The above results revealed that clear positive images can be obtained by using a positive photosensitive composition comprising a combination of the compound of general formula (I) and an alkali-soluble binder.

Claims (1)

[Claims] 1. A positive photosensitive composition comprising a compound represented by the following general formula (I) and an alkali-soluble polymer. [Formula 1] In the formula, R1 represents an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group, and R2 represents an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, a styryl group, a substituted styryl group, or a vinyl group. or a substituted vinyl group, and R3, R4, R5 and R6 each independently represent a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, a halogen atom or an alkoxy group. Also, R3 and R4, R4 and R5, R5 and R6
may be bonded to each other to form a benzene ring or a heterocycle together with the carbon atoms to which they are bonded.