JP2003131375A - Method for forming patterned insulating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a method for forming a patterned insulating film having high transmittance in the visible region and having high heat resistance and high dry etching durability and to improve the performance of a display device. SOLUTION: A radiation-sensitive resin composition containing an alkali- soluble copolymer consisting of indene and maleimide, a 1,2-naphthoquinone diazide compound and a crosslinking agent is used. By this method, the luminance of an LCD device and the driving rate of the liquid crystal can be improved.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a pattern forming method using a radiation-sensitive resin composition, and more particularly to a method for forming an insulating film in a display device such as a liquid crystal display (LCD) and an organic electroluminescence display device.

[0002]

2. Description of the Related Art Conventionally, an inorganic thin film such as silicon nitride or silicon dioxide has been used for an insulating film of LCD. The following process is adopted as a method of processing this inorganic thin film into a pattern according to the circuit of the TFT. First, an inorganic thin film having a film thickness of several hundred nanometers is formed on a substrate by a CVD (Chemical Vapor Deposition) method. A photoresist coating film is formed on the inorganic thin film by a spin coating method, and a resist pattern is formed by a photolithography process including irradiation with patterned ultraviolet rays and alkali development. Next, the inorganic thin film is etched using an aqueous solution of an inorganic acid such as hydrobromic acid using the resist pattern as an etching mask. The patterned insulating film is formed on the substrate by removing the resist after the etching.

The method of forming an inorganic interlayer insulating film has a problem that productivity is poor because a CVD apparatus requiring a high vacuum as described above must be used. Further, in order to improve the driving speed of the liquid crystal, it is necessary to make the capacitance of the insulating film as small as possible, but there is a problem that the dielectric constant of the inorganic thin film is as large as 6 or more. As a method for solving the problems of these inorganic insulating films, a photosensitive organic material (dielectric constant: 3 to 4) having a dielectric constant smaller than that of an inorganic material is used,
A method of forming a patterned insulating film by a photolithography method has been studied.

As a photosensitive organic material for forming an insulating film, for example, a material composed of an acrylic resin and diazonaphthoquinone as described in JP-A-7-248629 and JP-A-8-262709 is known. However, the photosensitive organic materials described in these known examples have insufficient heat resistance and dry etching resistance, and the dissolution contrast (developing rate of the coating film of the exposed portion relative to the developing rate [Ro] of the coating film of the unexposed portion). Since the [Re] ratio: Re / Ro) is not sufficiently large, it is difficult to apply it to the formation of a patterned insulating film for a display device that requires high heat resistance, high dry etching resistance, and high resolution. There was a problem.

On the other hand, as a photosensitive organic material having high heat resistance and dry etching resistance, Journal of Photopolymer Science and Technology Vol. 10,
Issue 2, p. 535 (J. Photopolym. Sci. Techno
L., Vol10, No2, 1997), a material composed of a polybenzoxazole precursor and diazonaphthoquinone is known. However, since polybenzoxazole has a strong light absorption in the visible region, it is difficult to apply this material to an insulating film material for an LCD that requires high transmittance.

As a photosensitive material having excellent heat resistance,
A negative photoresist composition comprising an indene / maleimide copolymer and a bisazide compound described in JP-A-6-43646 is known. This composition has higher heat resistance than a photosensitive material containing an acrylic resin as a main component, but when used as an insulating film for a display device, it has a problem that the light transmittance in the visible region is low. There is. Further, in order to form a contact hole pattern using a negative photosensitive material, it is necessary to use a mask having a large opening (transparent part) area of the mask, and it is inevitable that dust on the mask causes patterning. There is also a problem that hole-like defects are likely to occur in the insulating film.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a pattern having high light transmittance in the visible region (wavelength of 400 nm or more), high heat resistance, high dry etching resistance, and free from the defect occurrence seen in the prior art. To provide a positive type photosensitive organic material capable of forming a patterned insulating film and a method for forming a high performance patterned insulating film using the photosensitive organic material.

[0008]

The above-mentioned object is to provide an alkali-soluble copolymer of indene and maleimide,
A radiation sensitive resin composition containing a naphthoquinonediazide compound and a crosslinking agent is used to achieve an insulating film forming method for a display device.

Since the alkali-soluble copolymer of indene and maleimide has a cyclic structure in the main chain of the polymer, it has a high polymer main chain composed of carbon-carbon single bonds like acrylic polymers. It has higher heat resistance than the molecule.
In addition, the alkali-soluble copolymer composed of indene and maleimide is suitable as a material for forming a patterned insulating film that requires dry etching because the aromatic ring of indene has high dry etching resistance. .

In the present invention, an alkali-soluble polymer composed of indene, maleimide and N-substituted maleimide may be used instead of the alkali-soluble copolymer composed of indene and maleimide. N as the N-substituted maleimide
-Alkylated maleimides and N-arylated maleimides can be used. In particular, when a maleimide polymer containing an alkyl group such as a methyl group, an ethyl group, a propyl group or a benzyl group, or a cycloalkyl group such as a cyclohexyl group or a cyclopentyl group is used as the N-alkylated maleimide, A high patterned insulating film can be formed. Further, when a maleimide polymer containing a phenyl group, a tolyl group, a xylyl group, a biphenyl group, etc. is used as the N-arylated maleimide, a patterned insulating film having a high resolution can be formed.

When the 1,2-naphthoquinonediazide compound used as the photosensitizer of the present invention is mixed with an alkali-soluble copolymer composed of indene and maleimide, the solubility of the above copolymer in an alkali developing solution is significantly impaired.
This dissolution inhibiting ability disappears when the photosensitizer is converted to indenecarboxylic acid by exposure. Therefore, since the photosensitive organic material of the present invention functions as a positive type,
When the patterned insulating film is formed using the photosensitive material of the present invention, there is an advantage that pattern defects due to dust generated when a negative type material is used do not occur.

An example of 1,2-naphthoquinonediazide applicable to the present invention is 4,4 '-(1- (4- (1
-(4-hydroxyphenyl) -methylethyl) phenyl) ethylidene) bisphenol-tris (1,2-naphthoquinonediazide-5-sulfonic acid ester), bisphenol A-bis (1,2-naphthoquinonediazide-
5-sulfonic acid ester), 2,3,4-trihydroxybenzophenone-tris (1,2-naphthoquinonediazide-5-sulfonic acid ester), 2,3,4,4'-
Tetrahydroxybenzophenone-tetrakis (1,2
-Naphthoquinonediazide-5-sulfonic acid ester),
4,4 '-(1- (4- (1- (4-hydroxyphenyl) -methylethyl) phenyl) ethylidene) bisphenol-tris (1,2-naphthoquinonediazide-4-
Sulfonic acid ester), bisphenol A-bis (1,
2-naphthoquinonediazide-4-sulfonic acid ester), 2,3,4-trihydroxybenzophenone-tris (1,2-naphthoquinonediazide-4-sulfonic acid ester), 2,3,4,4'-tetrahydroxybenzophenone -Tetrakis (1,2-naphthoquinonediazide-4-sulfonic acid ester) and the like. These 1, 2
-The naphthoquinonediazide may be used alone or in combination of two or more kinds.

The cross-linking agent used in the present invention has the function of improving the organic solvent resistance of the patterned insulating film by cross-linking the copolymer of maleimide and indene by heat treatment after pattern formation. Usually, a wiring pattern of aluminum or chrome is formed on the LCD insulating film. Therefore, the patterned insulating film formed by using the photosensitive organic material needs to have resistance to the organic solvent. A patterned insulating film formed by using a photosensitive organic material composed of a copolymer composed of maleimide and indene and 1,2-naphthoquinonediazide is dissolved in an organic solvent such as monoethanolamine or N-methylpyrrolidone. The cross-linking agent used in the present invention has a function of cross-linking the copolymer composed of maleimide and indene by the heat treatment after pattern formation to make the patterned insulating film insoluble in the organic solvent.

As a compound effective as such a crosslinking agent, an amino resin such as hexamethoxymethylmelamine and benzoguanamine, a urea resin, an epoxy compound, an acrylate compound such as dipentaerythritol hexaacrylate and the like are preferable.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION <Example 1> Maleimide 9.1
g, indene 12.1 g (purity 90%), and a polymerization initiator azobisisobutyronitrile (AIBN) 200 mg were dissolved in dioxane 180 g, and the mixture was dissolved in nitrogen atmosphere at 75 ° C. for 5
Hold for time to obtain a copolymer. After completion of the polymerization, the reaction solution was poured into a large amount of methanol to precipitate and separate the produced copolymer. The resin yield after vacuum drying was 16 g (80% yield). When the molecular weight of the produced resin was measured by gel permeation chromatography, the number average molecular weight (M
n) = 9400, weight average molecular weight (Mw) = 2130
0 and the degree of dispersion (Mw / Mn) = 2.3.

The resulting maleimide-indene copolymer was dissolved in 1-methoxy-2-propanol (PGME) to prepare a 13 wt% solution, and 20 wt% of the photosensitizer 4,4 '-(1- ( 4- (1- (4-hydroxyphenyl) -methylethyl) phenyl) ethylidene) bisphenol-tris (1,2-naphthoquinonediazide-5)
-Sulfonic acid ester), hexamethoxymethyl melamine (manufactured by Mitsui Cyanamid, trade name Cymel 303) as a cross-linking agent, and a small amount of a surfactant were added and stirred until a homogeneous solution was obtained. This was filtered using a 0.2 μm filter to obtain a positive photosensitive composition.

After spin-coating the photosensitive composition on a glass substrate, it was baked on a hot plate at 90 ° C. for 2 minutes to give about 1 μm.
m coating film was formed.

The photosensitivity was evaluated as follows. Using a 500 W ultra-high pressure Xe-He lamp (manufactured by Ushio), i-line (wavelength 365 nm) optical filter and aperture 1 m
The coating film was exposed through a slit of m at an illuminance of 3 mW / cm ² with a stepwise change in time. 0.2% NM after exposure
It was developed for 60 seconds with a D-3 aqueous solution (manufactured by Tokyo Ohka), rinsed in water, and the thickness of the coating film remaining on the glass substrate was measured by a stylus type film thickness measuring device. A sensitivity curve was created by plotting the logarithm of the residual film thickness ratio (residual film ratio) of the exposed portion with respect to the initial film thickness and the exposure dose. The exposure amount when the residual film ratio of the exposed portion becomes 0 was taken as the sensitivity, and the slope of the sensitivity curve near the residual film ratio of 0 was taken as the contrast.

The sensitivity curve obtained by the above method is shown in FIG.
Shown in. Sensitivity 150 mJ / cm ² , contrast 0.9
Then, it was confirmed that the photosensitive composition according to the present invention had positive sensitivity characteristics of high sensitivity and high contrast.

The resolution was evaluated as follows.
A chrome mask having a line / space pattern was brought into close contact with the coating film, and an i-line was irradiated at 270 mJ / cm ² .
After exposure, develop with 0.2% NMD-3 aqueous solution for 70 seconds,
Rinse in water. Lines formed on a glass substrate /
The sample is cut so that a vertical cross-section appears in the line of the space pattern, and the sample is deposited by an evaporation system (ion sputtering E101
Au was vapor-deposited on the cross section of the sample using Hitachi). The cross section of the sample was observed with a scanning electron microscope S570 (manufactured by Hitachi Ltd.) to evaluate the resolution. As a result of evaluation of resolution by the above method, line / space = 1 μm by contact exposure method.
It was confirmed that a fine pattern of / 1 μm could be formed.

The light transmittance was evaluated as follows. 768 mJ / cm ^{2 on the} coating film through an i-line filter
And the baking was performed at 230 ° C. for 30 minutes.
After that, the UV absorption spectrum was measured, and the light transmittance per 1 μm of film thickness at a wavelength of 400 nm was calculated. As a result of measuring the light transmittance by the above method, the coating film has a light transmittance of 9
It was confirmed to have a high transparency of 2.5%.

The heat resistance was evaluated as follows.
The coating film was given an exposure amount of 768 mJ / cm ² through an i-line filter and then baked at 230 ° C. for 30 minutes. The coating film on the glass substrate was peeled off to obtain a powder. About 5 mg of the obtained powder was filled in an Al pan, and the differential type differential thermal balance TG8 was used.
4 using 120 (manufactured by Rigaku) at a rate of 10 ° C / min
The temperature was raised to 00 ° C. and the decomposition start temperature was measured. By the above method, it was confirmed that the photosensitive composition according to the present invention has a high decomposition initiation temperature of 317 ° C.

The electrical characteristics were evaluated as follows. 768 mJ / cm ^{2 on the} coating film through an i-line filter
And then baked at 230 ° C. for 30 minutes.
An aluminum electrode was vapor-deposited with a thickness of about 40 nm on the coating film using a high-speed vapor deposition device SVC-700 (manufactured by Sanyu Denshi Co., Ltd.). A dielectric constant / resistivity measuring device (YHP4061 manufactured by Yokogawa Hewlett-Packard Co., Ltd.) was used to measure the dielectric constant (ε) at 10 kHz and the specific resistance (ρ) near 100,000 V / cm. As a result of measuring the dielectric constant and the specific resistance by the above method, ε = 3.5, ρ = 5.05 × 10
It was confirmed that the photosensitive composition according to the present invention had an electric property of ¹⁵ (Ω · cm) so that it could be used as an insulating film.

The organic solvent resistance of the coating film was evaluated as follows. 768mJ through the i-line filter on the coating film
After giving an exposure amount of / cm ^2, the substrate was baked at 230 ° C for 30 minutes. This was immersed in monoethanolamine (MEA) heated to 60 ° C. for 15 minutes, and the change in film thickness before and after the immersion was measured. For comparison, the same experiment was performed on a photosensitive composition prepared in the same manner as the above photosensitive composition except that Cymel 303 was not added, and the two were compared. As a result of evaluating the MEA resistance by the above method, when the cymel 303 was not added, the coating film was completely dissolved in the MEA, whereas when the cymel 303 was added, it was applied even after the MEA was dipped. It was confirmed that the film remained. <Example 2> Instead of the resin used in Example 1, maleimide-methylmaleimide-indene resin, maleimide-
A pattern was formed in the same manner as in Example 1 except that a phenylmaleimide-indene resin and a maleimide-cyclohexylmaleimide-indene were used, and the developer concentration, the developing time, and the exposure amount were changed according to the alkali solubility of the resin. A patterned insulating film having substantially the same characteristics as the insulating film of Example 1 was formed. <Example 3> Instead of the photosensitizer used in Example 1, bisphenol A-bis (1,2-naphthoquinonediazide-
5-sulfonic acid ester), 2,3,4-trihydroxybenzophenone-tris (1,2-naphthoquinonediazide-5-sulfonic acid ester), 2,3,4,4'-
Tetrahydroxybenzophenone-tetrakis (1,2
-Naphthoquinonediazide-5-sulfonic acid ester),
4,4 '-(1- (4- (1- (4-hydroxyphenyl) -methylethyl) phenyl) ethylidene) bisphenol-tris (1,2-naphthoquinonediazide-4-
Sulfonic acid ester), bisphenol A-bis (1,
2-naphthoquinonediazide-4-sulfonic acid ester), 2,3,4-trihydroxybenzophenone-tris (1,2-naphthoquinonediazide-4-sulfonic acid ester), 2,3,4,4'-tetrahydroxybenzophenone -Using tetrakis (1,2-naphthoquinonediazide-4-sulfonic acid ester),
A pattern was formed in the same manner as in Example 1 except that the developing time and the exposure amount were changed. As a result, a patterned insulating film having substantially the same characteristics as in Example 1 could be formed. <Example 4> The cross-linking agent tetramethoxymethyl melamine used in Example 1 (manufactured by Mitsui Cyanamid: Cymel 30
Instead of 3), an amino resin such as benzoguanamine, a urea resin, an epoxy compound, an acrylate compound such as dipentaerythritol hexaacrylate, etc. were used, and the developer concentration, the developing time, and the exposure amount were changed. When a pattern was formed by the same method, a patterned insulating film having substantially the same characteristics as in Example 1 could be formed.

[0025]

EFFECTS OF THE INVENTION By applying the present invention, it becomes possible to form a patterned insulating film having high heat resistance and high dry etching resistance, and to improve the performance and reduce the manufacturing cost of LCD and EL display devices. You can

[Brief description of drawings]

FIG. 1 is a sensitivity curve of a photosensitive composition film according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/312 H01L 21/30 502R (72) Nobuaki Hayashi 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Display Group (72) Inventor Tetsuya Nishio 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Display Group F-term (reference) 2H025 AA09 AA10 AA20 AB14 AB17 AC01 AD03 BE01 CB10 CB25 CB41 CC17 FA17 4J100 AM43Q AM45R AM47R AM48R AR10P BC03R BC04R BC43R BC44R CA04 CA05 JA38 5F058 AC07 AF04 AH01

Claims (8)

[Claims] 1. A method of forming an insulating film for a display device, which comprises using a radiation-sensitive resin composition containing an alkali-soluble copolymer of indene and maleimide, a 1,2-naphthoquinonediazide compound, and a crosslinking agent. . 2. An insulating film for a display device comprising a radiation-sensitive resin composition containing an alkali-soluble polymer composed of indene, maleimide and N-substituted maleimide, a 1,2-quinonediazide compound, and a crosslinking agent. Forming method. 3. A method for forming an insulating film for a display device, wherein the N-substituted maleimide, which is one component of the alkali-soluble polymer according to claim 2, is an N-alkylated maleimide. 4. The N-alkylmaleimide according to claim 3, wherein N-methylmaleimide, N-ethylmaleimide,
N-propyl maleimide, N-benzyl maleimide, N
-A method for forming an insulating film of a display device, which comprises using at least one compound selected from cyclohexylmaleimide and N-cyclopentylmaleimide. 5. A method for forming an insulating film in a display device, wherein the N-substituted maleimide, which is one component of the alkali-soluble polymer according to claim 2, is an N-arylated maleimide. 6. The N-arylated maleimide according to claim 5, wherein at least one compound selected from N-phenylmaleimide, N-tolylmaleimide, N-xylylmaleimide and N-biphenylmaleimide is used. A method for forming an insulating film in a display device, comprising: 7. The radiation-sensitive resin composition according to claim 1, wherein the crosslinking agent is at least one compound selected from amino resins, epoxy compounds and acrylate compounds. Film forming method. 8. A method for forming an insulating film in a display device, wherein the amino resin according to claim 7 is hexaalkoxymethylmelamine.