JP2002116715A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To pattern an insulation layer consisting of polybezoxazole with a simple process and further to easily obtain a normal tapered sectional shape desirable for the insulation layer. SOLUTION: In the display device comprises a first electrode formed on a substrate, the insulation layer formed on the first electrode so as to partly expose the first electrode and a second electrode placed opposite to the first electrode, the insulation layer consists essentially of a polymer having a structural unit expressed by a general formula (1) and a photo acid generating agent. In the formula (1), R1 expresses a divalent organic group with at least two or more carbon atoms, R2 expresses a di- to tetravalent organic group with at least two or more carbon atoms and m expresses an integer of 3 to 100,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a display device having a first electrode formed on a substrate and a second electrode provided opposite to the first electrode.

[0002]

2. Description of the Related Art As an image display device (display) replacing a large and heavy cathode ray tube, a light and thin so-called flat panel display has attracted attention.

A liquid crystal display (LCD) has become widespread as a flat panel display. An electrochromic display (ECD) has been used as a similar non-emissive display, and a plasma display panel (PDP) has recently been attracting attention. )
And an electroluminescent display (ELD). Among the electroluminescent displays, organic electroluminescent devices are particularly active in research and development because of their high luminance and the possibility of full-color displays.

[0004] These flat panel displays are:
It operates by applying a voltage between the opposing first and second electrodes or by passing a current. At this time, since an electric field tends to concentrate on the edge portion of the electrode having a small radius of curvature, undesirable phenomena such as dielectric breakdown and generation of leak current are likely to occur at the edge portion.

[0005] In order to suppress such development, it is known to cover the edge portion of the first electrode with an insulating layer. This makes it possible to reduce the electric field concentration at the edge of the electrode. Japanese Patent Application Laid-Open No. H11-97182 discloses an insulating layer at a boundary portion where the insulating layer exposes the first electrode so that an organic insulating layer and a second electrode formed after the formation of the insulating layer are smoothly deposited. A technique has been disclosed in which the above problem is further suppressed by gradually increasing the thickness as the distance from the boundary increases, that is, by forming the cross section into a forward tapered shape.

Generally, polyimide or polybenzoxazole is used for the insulating layer, and non-photosensitive, negative photosensitive, and positive photosensitive are known.

When a non-photosensitive polyimide is used, the insulating layer is patterned by coating a polyimide precursor on a substrate, pre-baking the polyimide precursor (also called drying or semi-curing), and photoresist on the polyimide precursor. Coating, photoresist baking (also called drying or pre-baking), photoresist exposure, photoresist development, polyimide precursor etching, photoresist removal, and polyimide precursor curing (also called post-baking). Photolithography process was required. Therefore, there is a problem that the process is complicated and the yield is poor. Furthermore, in order for the cross section of the insulating layer to have a forward tapered shape, it is necessary to optimize many parameters such as a developing condition of the photoresist and an etching condition of the polyimide precursor, and there is a problem that setting the conditions is complicated. Was.

When a photosensitive type such as a negative photosensitive polyimide or a positive photosensitive polyimide is used, the insulating layer can be patterned without using a photoresist, so that the process is complicated and the yield is reduced. Can be. However, the negative photosensitive polyimide tends to have a reverse tapered shape or a rectangular shape rather than a forward tapered shape, and cannot obtain the effect of reducing the electric field concentration at the edge portion. As for the positive photosensitive polyimide, a technique in which an o-nitrobenzyl ester group is introduced into a carboxyl group of a polyamic acid is disclosed in JP-A-8-171989. However, when a general-purpose 2.38% TMAH aqueous solution is used as a developer, this positive photosensitive polyimide has problems such as poor pattern workability, and cannot perform fine patterning as in the present invention.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to pattern an insulating layer made of polybenzoxazole by a simple process. It is another object of the present invention to easily obtain a forward tapered shape which is a desirable cross section of the insulating layer.

[0010]

According to the present invention, there is provided a display device comprising: a first electrode formed on a substrate; an insulating layer formed on the first electrode so as to partially expose the first electrode; A display device comprising: a second electrode provided to face a first electrode, wherein the insulating layer comprises a polymer having a structural unit represented by the following general formula (1) as a main component and a photoacid generator. A display device characterized as being an essential component.

[0011]

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(R ¹ represents a divalent organic group having at least two or more carbon atoms, and R ² represents a divalent to tetravalent organic group having at least two or more carbon atoms. M represents 3 to 100,000 Indicates an integer up to.)

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a display device including a first electrode formed on a substrate and a second electrode provided opposite to the first electrode. For example, an LCD, an ECD, an ELD, a display device using an organic electroluminescent element (organic electroluminescent device), and the like are applicable. An organic electroluminescent device includes a first electrode formed on a substrate, a thin film layer including a light emitting layer formed of at least an organic compound formed on the first electrode, and a second electrode formed on the thin film layer. Is a display device comprising an organic electroluminescent element including: LC
In the case of D or ELD, the distance between the first electrode and the second electrode is about several μm, but in the case of an organic electroluminescent device, the thickness of the thin film layer is 0.1 μm.
And the distance between the first electrode and the second electrode is only about sub-μm. Therefore, undesired phenomena such as dielectric breakdown and generation of leak current due to electric field concentration at the electrode edge are more likely to occur than in LCDs and ELDs, and the cross-sectional shape of the insulating layer is more likely to affect the characteristics of the display device. As such, the presence of an insulating layer becomes increasingly important. The insulating layer made of the positive photosensitive polyimide of the present invention functions more effectively in a display device in which the distance between the first electrode and the second electrode is relatively small, such as an organic electroluminescent device.

The insulating layer of the present invention is formed so as to cover at least a part of the first electrode and to partially expose the first electrode, and the insulating layer covers an edge portion of the first electrode. It is preferable to form it. An example of a particularly suitable shape of the insulating layer is shown in FIGS. There is an opening 15 on the substrate 10 where the first electrode 11 formed in a stripe shape is exposed, and the portion other than the exposed portion is covered with the insulating layer 14. That is, the insulating layer 14 is formed so as to cover the edge of the first electrode 11. Further, it is preferable that the insulating layer is formed so as to block an edge portion of the second electrode facing the first electrode as needed. Opening 1
5 is, for example, one light emitting region in an organic electroluminescent device,
That is, it can correspond to a pixel.

In the present invention, as shown in FIG.
It is preferable that the cross section of the insulating layer at the boundary portion 16 where the first electrode 11 is exposed has a forward tapered shape.
Here, the forward tapered shape corresponds to the angle θ in the figure being less than 90 °. Taking an organic electroluminescent device as an example, when the cross section of the insulating layer has a forward tapered shape, even when the organic thin film layer and the second electrode are formed after the formation of the insulating layer, these films are smoothly formed at the boundary portion. Formed,
It is possible to reduce unevenness in film thickness caused by steps,
A light-emitting device having stable characteristics can be obtained. The taper angle θ is 80 ° or less, further 60 ° or less, and 4
It is preferable that it is 5 ° or less.

The insulating layer is often formed in contact with and directly on the first electrode. However, when a guide electrode is attached to the first electrode to reduce the resistance of the first electrode, the first electrode may be formed so as to be in contact with the guide electrode. In this case, the electric field concentration can be effectively suppressed by forming the insulating layer so as to cover not only the first electrode but also the edge portion of the guide electrode.

The thickness of the insulating layer is not particularly limited.
It is preferably in the range of from 50 to 50 µm, and more preferably in the range of from 0.2 to 50 µm, and more preferably in the range of from 0.5 to 10 µm. When the insulating layer is relatively thin, high-precision patterning becomes possible. In addition, when the insulating layer is relatively thick, a shadow mask may damage a layer already formed on a substrate, for example, when patterning a light emitting layer or a second electrode by a mask vapor deposition method in manufacturing an organic electroluminescent device. A role as a spacer for preventing scratches) can be added.

Since the insulating layer is formed so as to straddle the adjacent first electrodes, good electrical insulation is required. The volume resistivity of the insulating layer is 5 × 10 ⁶ Ωcm or more.
It is preferably at least 10 ⁷ Ωcm. Note that the insulating layer can be blackened in order to improve the contrast of the display device; however, in that case, care must be taken so as not to impair the electrical insulation.

In the present invention, as the first electrode material, a transparent conductive material is preferable, and tin oxide, zinc oxide, vanadium oxide, indium oxide, indium tin oxide (IT
O) can be used. In display applications where patterning is performed, it is preferable to use ITO having excellent workability for the base electrode. ITO may contain a small amount of metal such as silver or gold to improve conductivity.

The present invention is characterized in that the insulating layer is made of a positive photosensitive polybenzoxazole. The photosensitive polybenzoxazole is a general term for a material that can be directly patterned by utilizing the fact that the solubility of a polybenzoxazole precursor in a developer in an energy-irradiated portion is different from that in a non-irradiated portion. After curing, polybenzoxazole can be obtained. As the energy for irradiation, an electron beam or the like can be used, but in many cases, electromagnetic waves, particularly from blue to ultraviolet (U
V) Since the light in the region is used, the energy irradiation is called exposure. In addition, removing a desired portion of the polybenzoxazole precursor film using the difference in solubility is referred to as development. By using a photosensitive polybenzoxazole for the insulating layer, coating, exposing and developing a resist on a non-photosensitive polyimide precursor and removing the resist after etching the non-photosensitive polyimide precursor, which were conventionally required Is unnecessary, and the number of steps required for patterning the insulating layer can be greatly reduced.

The photosensitive polybenzoxazole has two types: a positive type in which the solubility is increased by exposure to light, and a type in which an exposed portion is removed; and a negative type in which light exposure cures and removes an unexposed portion. There are two types. When the photosensitive polybenzoxazole precursor is exposed, light is strongly absorbed at the surface portion of the film, and the amount of light absorbed tends to decrease toward the inside. That is, in the positive type, the solubility of the surface portion of the film tends to be larger than that in the inner portion, and in the negative type, the solubility tends to be opposite. In the present invention, it is preferable that the insulating layer is made of a positive photosensitive polybenzoxazole precursor from which a forward tapered shape is easily obtained in principle.

Examples of the resin composition of the present invention include, but are not limited to, polybenzoxazole and its precursor polyhydroxyamide, imide ring, and other polymers having a cyclic structure.
Preferably, the polymer represented by the above general formula (1) is used.

The solvent used in the present invention includes N-methyl-2-pyrrolidone, γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide,
Polar aprotic solvents such as dimethyl sulfoxide,
Ethers such as tetrahydrofuran, dioxane and propylene glycol monomethyl ether; ketones such as acetone, methyl ethyl ketone and diisobutyl ketone; esters such as ethyl acetate, propylene glycol monomethyl ether acetate and ethyl lactate; and aromatic hydrocarbons such as toluene and xylene Such solvents can be used alone or as a mixture.

In order to enhance the adhesiveness to the substrate, a silane coupling agent, a titanium chelating agent and the like can be used in combination. Methyl methacryloxydimethoxysilane, 3-
It is preferable to add 0.5 to 10 parts by weight of a silane coupling agent such as aminopropyltrimethoxysilane, a titanium chelating agent, or an aluminum chelating agent to the polymer.

By treating the substrate, it is possible to further improve the adhesiveness. Solution obtained by dissolving 0.5 to 20 parts by weight of the above-described coupling agent in a solvent such as isopropanol, ethanol, methanol, water, tetrahydrofuran, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, and diethyl adipate. Is subjected to surface treatment by spin coating, dipping, spray coating, steam treatment, or the like. In some cases, then 50 ° C to 300 ° C
The reaction between the substrate and the coupling agent proceeds by applying a temperature up to.

The material of the substrate in the present invention includes, for example, all materials on which metal for an electrode can be provided on the surface, such as metal, glass, semiconductor, metal oxide insulating film, silicon nitride, and polymer film. Preferably, glass is used. The material of the glass is not particularly limited, but alkali zinc borosilicate glass, sodium borosilicate glass, soda lime glass, low alkali borosilicate glass, barium borosilicate glass, borosilicate glass, aluminosilicate glass, molten Quartz glass, synthetic quartz glass, or the like is used. Usually, soda lime glass, which has a small amount of ions eluted from glass and is provided with a barrier coat such as alkali-free glass or SiO _2, is used. In addition, since the thickness may be any thickness that is sufficient to maintain mechanical strength, the thickness is 0.1 mm or more, preferably 0.5 mm
That is all.

If necessary, surfactants, esters such as ethyl lactate and propylene glycol monomethyl ether acetate, alcohols such as ethanol, cyclohexanone, methyl for the purpose of improving the wettability between the composition of the present invention and the substrate. Ketones such as isobutyl ketone and ethers such as tetrahydrofuran and dioxane may be mixed. In addition, inorganic particles such as silicon dioxide and titanium dioxide, or powder of polyimide can also be added.

The polymer having the structural unit represented by the general formula (1) as a main component has a hydroxyl group, and has higher solubility in an aqueous alkali solution than polyamic acid having no hydroxyl group. In particular, among the hydroxyl groups, phenolic hydroxyl groups are preferable from the viewpoint of solubility in an aqueous alkaline solution.

In the present invention, the polymer represented by the general formula (1) can be a polymer having an oxazole ring, an imide ring or another cyclic structure by heating or an appropriate catalyst. By having a ring structure, heat resistance,
The solvent resistance is dramatically improved.

The photosensitive polybenzoxazole of the present invention may be composed of only the structural unit represented by the general formula (1), or may be a copolymer or a blend with another structural unit. Is also good. In that case, it is preferable that the structural unit represented by the general formula (1) is contained in an amount of 90 mol% or more. What are the types and amounts of structural units used for copolymerization or blending? It is preferable to select the range within a range that does not impair the heat resistance of the polymer obtained by the final heat treatment temperature.

In the general formula (1), R ¹ represents a divalent organic group having at least two carbon atoms. In view of the heat resistance of the polymer according to the invention, R ¹ is preferably a divalent organic group containing an aromatic or aromatic heterocyclic ring and having 6 to 30 carbon atoms. Preferred specific examples of R ¹ include diphenyl ether-3,3′-dicarboxylic acid,
Diphenyl ether-3,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, isophthalic acid, benzophenone-3,3'-dicarboxylic acid, benzophenone-3,4'-dicarboxylic acid, benzophenone-
4,4′-dicarboxylic acid, diphenylsulfone-3,
3'-dicarboxylic acid, diphenylsulfone-3,4'-
Residues such as, but not limited to, dicarboxylic acids, diphenylsulfone-4,4'-dicarboxylic acids. In addition, R ¹ may be composed of ^one of these, or may be a copolymer composed of two or more.

In the general formula (1), R ² represents a divalent to tetravalent organic group having at least two or more carbon atoms. In view of the heat resistance of the polymer in the present invention, R ² is preferably a tetravalent organic group containing an aromatic or aromatic heterocyclic ring and having 6 to 30 carbon atoms. Preferred specific examples of R ² include 3,3′-diamino-4,4′-dihydroxydiphenyl ether, 4,4′-diamino-3,
Residues such as 3′-dihydroxydiphenyl ether and 3,4′-diamino-3,4′-dihydroxydiphenyl ether are exemplified. Such examples include those having the following structures, but the present invention is not limited thereto. Further, R ² may be composed of one of these, or may be a copolymer composed of two or more.

[0033]

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The polybenzoxazole precursor represented by the general formula (1) is obtained by condensation of dihydroxydiamine and halogenated dicarboxylic acid or condensation of dihydroxydiamine and dicarboxylic acid in the presence of a dehydrating condensing agent such as dicyclohexylcarbodiimide. And the like.

It is desirable that the polymer represented by the general formula (1) is as transparent as possible to the actinic radiation to be exposed. Therefore, the absorbance of the polymer at 365 nm is preferably 0.1 or less per 1 μm. It is more preferably 0.08 or less. It is 365 when it exceeds 0.1
The sensitivity to exposure to nm actinic radiation is reduced.

The polymer having a structural unit represented by the general formula (1) as a main component can be imparted with photosensitivity by adding a photoacid generator.

The photoacid generator used in the present invention includes diazonium salts, diazoquinonesulfonic acid amides, diazoquinonesulfonic acid esters, diazoquinonesulfonic acid salts, and the like.
Nitrobenzyl esters, onium salts, halides,
Halogenated isocyanates, halogenated triazines, bisarylsulfonyldiazomethanes, disulfones, and other compounds that decompose upon irradiation with light to generate an acid are exemplified. In particular, an o-quinonediazide compound is desirable because it has an effect of suppressing the water solubility of an unexposed portion. Such compounds include 1,2-benzoquinone-2-azido-4-sulfonic acid ester or sulfonic acid amide, 1,2-naphthoquinone-2-diazido-5-sulfonic acid ester or sulfonic acid amide, -Naphthoquinone-2-diazide-4-sulfonic acid ester or sulfonic acid amide. These include, for example, 1,2-benzoquinone-2-azido-4-sulfonyl chloride, 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride, 1,2-naphthoquinone-2-diazide-4-sulfonyl chloride and the like. By subjecting o-quinonediazidosulfonyl chlorides to a polyhydroxy compound or a polyamino compound in the presence of a dehydrochlorination catalyst.

Examples of the polyhydroxy compound include hydroquinone, resorcinol, pyrogallol, bisphenol A, bis (4-hydroxyphenyl) methane, 2,2-
Bis (4-hydroxyphenyl) hexafluoropropane, 2,3,4-trihydroxybenzophenone, 2,
3,4,4'-tetrahydroxybenzophenone, 2,
2 ', 4,4'-tetrahydroxybenzophenone, tris (4-hydroxyphenyl) methane, 1,1,1-
Tris (4-hydroxyphenyl) ethane, 1- [1-
(4-hydroxyphenyl) isopropyl] -4-
[1,1-bis (4-hydroxyphenyl) ethyl] benzene, 4-phenylmethyl-1,2,3-benzenetriol, 4-ethyl-1,3-benzenediol,
-Phenylmethyl-1,3-benzenediol, 4-
(1-methyl-1-phenylethyl) -1,3-benzenediol, (2,4-dihydroxyphenyl) phenylmethanone, 4-diphenylmethyl-1,2,3-benzenetriol, 2,4 ′, 4 "-Trihydroxytriphenylmethane, 2,6-bis [(2-hydroxy-5
-Methylphenyl) methyl] -4-methylphenol,
4,4 '-[1- [4- [1- (4-hydroxyphenyl) -1-methylethyl] phenyl] ethylidene] bisphenol, 1,1,1-tris (4-hydroxyphenyl) ethane, 4,6 -Bis [(4-hydroxyphenyl) methyl] -1,3-benzenediol, 4,4 ′,
4 ", 4 '"-(1,2-ethanediylidene) tetrakisphenol, 2,6-bis [(4-hydroxyphenyl) methyl] -4-methylphenol, 4,4'-[4
-(4-hydroxyphenyl) cyclohexylidene] bisphenol, 2,4-bis [(4-hydroxyphenyl) methyl] -6-cyclohexylphenol, 2,2 ′
-Methylenebis [6-[(2 / 4-hydroxyphenyl) methyl] -4-methylphenol], 2,2′-biphenol, 4,4′-cyclohexylidenebisphenol 4,4′-cyclopentylidenebisphenol 2,
2'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl ether, 4,4 '-[1,4-
Phenylenebis (1-methylethylidene)] bis [benzene-1,2-diol], 5,5 '-[1,4-phenylenebis (1-methylethylidene)] bis [benzene-1,2,3-triol ] 4- [1- (4-hydroxyphenyl) -1-methylethyl] -1,3-benzenediol, 4- [1- (4-hydroxyphenyl) cyclohexyl] -1,2-benzenediol, 4- [ 1-
(4-hydroxyphenyl) cyclohexyl] -1,3
-Benzenediol, 4-[(4-hydroxyphenyl) cyclohexylidene] -1,2,3-benzenetriol methyl gallate, ethyl gallate and the like.

Examples of the polyamino compound include 1,4-phenylenediamine, 1,3-phenylenediamine,
4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide and the like.

Examples of the polyhydroxypolyamino compound include 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane and 3,3'-dihydroxybenzidine.

Specific examples of the photoacid generator used in the present invention include methyl 3,4,5-trihydroxybenzoate and 4,4 '-[1- [4- [1- (4-hydroxyphenyl). ) -1-Methylethyl] phenyl] ethylidene] bisphenol, 4,4 ′, 4 ″ -ethylidenetrisphenol,
4,6-bis [(4-hydroxyphenyl) methyl] -1,
3-benzenediol, 4,4,4 ', 4'-tetrakis
[(1-methylethylidene) bis (1,4-cyclohexylidene)] phenol, 4,4 ′-[4- (4-hydroxyphenyl) cyclohexylidene] bisphenol, wherein at least one hydroxyl group is 1,2-naphthoquinonediazide-4-sulfonyl group or 1,2-
An o-quinonediazide compound which is a naphthoquinonediazide-5-sulfonyl group is exemplified.

The o-quinonediazide compound is blended in an amount of preferably 5 to 100 parts by weight, more preferably 5 to 40 parts by weight, based on 100 parts by weight of the polymer represented by the general formula (1). If the amount is less than 5 parts by weight, sufficient sensitivity cannot be obtained, and if the amount exceeds 100 parts by weight,
It is difficult to form a pattern by light irradiation and subsequent development, and the heat resistance of the resin composition may be reduced.

For the purpose of adjusting the dissolution rate ratio between the unexposed portion and the exposed portion, a dissolution regulator can be used. As the dissolution regulator, any compound such as a polyhydroxy compound, a sulfonamide compound, and a urea compound can be preferably used. In particular, a polyhydroxy compound which is a raw material for synthesizing a quinonediazide compound is preferably used. Specifically, methyl 3,4,5-trihydroxybenzoate, 4,4 ′-[1- [4- [1- (4
-Hydroxyphenyl) -1-methylethyl] phenyl]
Ethylidene] bisphenol, 4,4 ′, 4 ″ -ethylidene trisphenol, 4,6-bis [(4-hydroxyphenyl) methyl] -1,3-benzenediol, 4,4
4 ', 4'-tetrakis [(1-methylethylidene) bis
(1,4-cyclohexylidene)] phenol.

The dissolution regulator is preferably blended in an amount of 1 to 100 parts by weight, more preferably 5 to 40 parts by weight, based on 100 parts by weight of the polymer represented by the general formula (1). If the amount is less than 1 part by weight, sufficient effects cannot be obtained, and if it exceeds 100 parts by weight, the heat resistance of the resin composition may be reduced.

The patterning of the insulating layer using the positive photosensitive polybenzoxazole can be carried out in the following steps. On the substrate 10 on which the first electrode 11 is patterned (FIG. 4), a positive photosensitive polybenzoxazole precursor film is applied on the entire surface (FIG. 5). The application method is
Spin coating, slit die coating, spraying,
Known techniques such as a roll coating method and a dipping method can be used. Further, the coating film thickness is 0.1 to 150 after drying.
It is applied to a thickness of μm. Preferably, 0.5 to 2
0 μm.

After pre-baking the applied polybenzoxazole precursor film as required, the photomask 18
Exposure is carried out through (FIG. 6). As the solubility of the exposed portion 17 increases, the substrate is immersed in a developing solution to dissolve the exposed portion.
By removing and curing as necessary, a desired polybenzoxazole pattern can be obtained (FIG. 7).

The prebaking of the positive photosensitive polybenzoxazole precursor of the present invention is preferably carried out at 50 ° C. to 150 ° C. for 1 minute to several hours using an oven, a hot plate, infrared rays or the like. 80 if necessary
After drying at 2 ° C. for 2 minutes, drying at 120 ° C. for 2 minutes or two or more stages can be used.

As the actinic radiation used for exposure, ultraviolet rays,
There are visible light, electron beam, X-ray, etc., but i-line (365 nm), h-line (405 nm), and g-line (436n) of mercury lamp.
It is preferred to use m). Light of these wavelengths is preferably used singly or as a mixture of two or more.

The resolution of the pattern at the time of development is improved,
When the allowable range of the developing conditions increases, a step of performing a baking process before the development may be adopted. This temperature is preferably in the range of 50 to 180 ° C., particularly 60 to 180 ° C.
A range of 150 ° C. is more preferred. The time is preferably from 10 seconds to several hours. If the ratio is out of this range, the reaction may not proceed or all the regions may not be dissolved.

As a developing solution, an aqueous solution of tetramethylammonium, diethanolamine, diethylaminoethanol, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, diethylamine, methylamine, dimethylamine, dimethylaminoethyl acetate, dimethylaminoethyl An aqueous solution of an alkaline compound such as ethanol, dimethylaminoethyl methacrylate, cyclohexylamine, ethylenediamine, or hexamethylenediamine is preferred. An aqueous solution of tetramethylammonium hydroxide (TMAH) is a particularly suitable developer.

In some cases, a polar solvent such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, γ-butyrolactone, dimethylacrylamide, or the like may be added to these aqueous alkali solutions. Addition of alcohols such as ethanol, ethanol, isopropanol, esters such as ethyl lactate, propylene glycol monomethyl ether acetate, ketones such as cyclopentanone, cyclohexanone, isobutyl ketone, methyl isobutyl ketone, alone or in combination of several kinds May be.

After the development, a rinsing treatment is performed with water. Here, rinsing treatment may be performed by adding alcohols such as ethanol and isopropyl alcohol, and esters such as ethyl lactate and propylene glycol monomethyl ether acetate to water. Ultrasonic treatment can be applied to development and rinsing.

The curing temperature is preferably in the range of 200 ° C. to 500 ° C., more preferably in the range of 250 ° C. to 350 ° C. This heat treatment is carried out for 5 minutes to 5 hours while selecting the temperature and increasing the temperature stepwise or while selecting a certain temperature range and continuously increasing the temperature. As an example, 140 ° C., 2
Heat treatment is performed at 00 ° C. and 350 ° C. for 30 minutes each. Alternatively, a method of linearly raising the temperature from room temperature to 400 ° C. over 2 hours may be used. The glass transition temperature of the photosensitive polybenzoxazole of the present invention is more preferably from 250 ° C to 350 ° C, and more preferably from 280 ° C to 350 ° C. The 5% thermal weight loss temperature is preferably 350 ° C. or higher. The refractive index is not particularly limited.
It is preferably 8 or less.

[0054]

Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited by these.

Synthesis Example 1 Synthesis of hydroxyl group-containing diamine compound 18.3 g (0.05 mol) of BAHF was added to 100 parts of acetone.
and propylene oxide (17.4 g, 0.3 mol), and cooled to -15 ° C. A solution obtained by dissolving 20.4 g (0.11 mol) of 3-nitrobenzoyl chloride in 100 ml of acetone was added dropwise. After dropping,
The reaction was carried out at −15 ° C. for 4 hours, and then returned to room temperature. The solution was concentrated with a rotary evaporator, and the obtained solid was recrystallized with a mixed solution of tetrahydrofuran and ethanol.

30 g of the recrystallized solid collected was 300 ml
Was dispersed in 250 ml of methyl cellosolve, and 2 g of 5% palladium-carbon was added. Here, hydrogen was introduced by a balloon, and the reduction reaction was performed at room temperature. After about 4 hours, it was confirmed that the balloon did not deflate any more, and the reaction was terminated. After completion of the reaction, the mixture was filtered to remove the palladium compound as a catalyst, and concentrated by a rotary evaporator to obtain a diamine compound. This is shown below. The obtained solid was directly used for the reaction.

[0057]

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Synthesis Example 2 Synthesis of quinonediazide compound (1) 16.1 g (0.05 mol) of BisRS-2P (trade name, manufactured by Honshu Chemical Industry Co., Ltd.) and 5-naphthoquinonediazidosulfonyl chloride in a dry nitrogen stream 26.9g
(0.1 mol) was dissolved in 450 g of 1,4-dioxane and brought to room temperature. Here, 10.1 g of triethylamine mixed with 50 g of 1,4-dioxane was charged at 35 ° C.
It dripped so that it might not become above. After the dropwise addition, the mixture was stirred at 30 ° C. for 2 hours. The triethylamine salt was filtered, and the filtrate was poured into water. Thereafter, the deposited precipitate was collected by filtration. The precipitate was dried with a vacuum drier to obtain a quinonediazide compound (1).

[0059]

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Synthesis Example 3 Synthesis of quinonediazide compound (2) 15.3 g (0.05 mol) of TrisP-HAP (trade name, manufactured by Honshu Chemical Industry Co., Ltd.) and 5-
Naphthoquinone diazide sulfonyl chloride 40.3g
(0.15 mol) was dissolved in 450 g of 1,4-dioxane and brought to room temperature. Here, 50 g of 1.4-dioxane
Quinonediazide compound (2) was obtained in the same manner as in Synthesis Example 3 using 15.2 g of triethylamine mixed with the above.

[0061]

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Synthesis Example 4 43 g (0.17 mol) of diphenyl ether-4,4'-dicarboxylic acid and 44.7 g (0.33 mol) of 1-hydroxybenzotriazole were mixed with N, N under a stream of dry nitrogen.
-Reacted in 300 g of dimethylacetamide. 73.9 g (0.15 mol) of the obtained dicarboxylic acid derivative and 61.1 g (0.17 mol) of hexafluoro-2,2-bis (3-amino-4-hydroxyphenyl) propane
Was dissolved in 500 g of NMP under a stream of dry nitrogen.
Thereafter, the mixture was stirred at 80 ° C. for 10 hours. The resulting solution 4
0 g of the quinonediazide compound (1) obtained in Synthesis Example 2
2 g were dissolved to obtain a photosensitive resin composition varnish A.

Synthesis Example 5 In Synthesis Example 4, hexafluoro-2,2-bis (3
Instead of (-amino-4-hydroxyphenyl) propane, the hydroxyl group-containing diamine 1 obtained in Synthesis Example 1
Varnish B was prepared in the same manner as in Synthesis Example 4 except that 22.7 g (0.17 mol) of the quinonediazide compound (2) obtained in Synthesis Example 2 was dissolved instead of the quinonediazide compound (1). Got.

Example 1 A glass substrate having a 130-nm-thick ITO transparent electrode film formed on a 1.1-mm-thick non-alkali glass surface by sputtering was cut into a size of 120 × 100 mm. Apply photoresist on the ITO substrate,
Patterning was performed by exposure and development using a normal photolithography method. After removing unnecessary portions of the ITO by etching, the photoresist is removed, so that the ITO is removed.
The film was patterned into a stripe shape having a length of 90 mm and a width of 80 μm. This striped first electrode is 100 μm
816 are arranged at a pitch.

Next, the concentration of varnish A was adjusted, applied to the substrate on which the first electrode was formed by spin coating, and prebaked on a hot plate at 120 ° C. for 2 minutes. After UV exposure of this film through a photomask, 2.38
Developing by dissolving only the exposed portion with a% TMAH aqueous solution, and rinsing with pure water. 170 ° C. under a nitrogen atmosphere in a clean oven the obtained polyimide precursor pattern,
It was cured by heating at 320 ° C. for 60 minutes and further for 30 minutes. In this manner, 816 openings having a width of 70 μm and a length of 250 μm are arranged in the width direction at a pitch of 100 μm, and 200 openings are arranged at a pitch of 300 μm in the length direction. As shown in FIG. An insulating layer made of photosensitive polyimide was formed so as to expose the center of the electrode and to cover the edge of the first electrode. The thickness of the insulating layer is about 1 μm and the volume resistivity is at least 5 × 1
0 ⁷¹⁰ Ωcm was confirmed. The cross section of the boundary portion of the insulating layer had a forward tapered shape as shown in FIG. 3, and the taper angle θ was about 45 °. When the infrared absorption spectrum of the insulating layer was measured in a reflection configuration, an absorption peak near 1477 cm ^{−1 of} the oxazole structure was detected.

Next, an organic electroluminescent device was manufactured using the substrate on which the insulating layer was formed. The thin film layer including the light emitting layer,
It was formed by a vacuum evaporation method using a resistance wire heating method. The degree of vacuum at the time of vapor deposition was 2 × 10 ⁻⁴ Pa or less, and the substrate was rotated with respect to the vapor deposition source during vapor deposition. First, copper phthalocyanine was converted to 15 nm bis (N-ethylcarbazole).
Was deposited over the entire effective area of the substrate to form a hole transport layer.

For patterning the light emitting layer, a shadow mask in which a mask portion and a reinforcing line were formed in the same plane was used as schematically shown in FIG. The outline of the shadow mask is 120 × 84 mm, and the thickness of the mask portion 31 is 25.
μm, 272 stripe-shaped openings having a length of 64 mm and a width of 100 μm are arranged at a pitch of 300 μm. Reinforcing lines 33 each having a width of 20 μm and a thickness of 25 μm, which are orthogonal to the openings, are formed in each stripe-shaped opening 32 at 1.8 mm intervals. The shadow mask is fixed to a stainless steel frame 34 having the same outer shape and a width of 4 mm.

A shadow mask for a light emitting layer was arranged in front of the substrate so that they were in close contact with each other, and a ferrite plate magnet (YBM-1B, manufactured by Hitachi Metals, Ltd.) was arranged behind the substrate. On this occasion,
The stripe-shaped first electrode is located at the center of the stripe-shaped opening of the shadow mask, the reinforcing line is located on the insulating layer, and the reinforcing line and the insulating layer are arranged to be in contact with each other. Since the shadow mask comes into contact with the thick insulating layer and does not come into contact with the previously formed organic layer, mask flaws are prevented. In this state, 0.3% by weight of 1,3,5,7,8-pentamethyl-4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene (PM546) was doped.
-Hydroxyquinoline-aluminum complex (Alq3)
Was deposited to a thickness of 21 nm to pattern a green light-emitting layer.

Next, the shadow mask was aligned with the first electrode pattern at a position shifted by one pitch, and
Alq3 doped with 4- (dicyanomethylene) -2-methyl-6- (julolidylstyryl) pyran (DCJT) was deposited to a thickness of 15 nm to pattern the red light emitting layer.

Further, the shadow mask is aligned with the first electrode pattern at a position shifted by one pitch, and 4,4 ′
-Bis (2,2'-diphenylvinyl) diphenyl (D
PVBi) was deposited to a thickness of 20 nm to pattern the blue light-emitting layer. The green, red, and blue light emitting layers are arranged for every three stripe-shaped first electrodes, and completely cover the exposed portions of the first electrodes.

Next, DPVBi was deposited to a thickness of 35 nm and Alq3 was deposited to a thickness of 10 nm over the entire effective area of the substrate. Thereafter, the thin film layer was exposed to lithium vapor to dope (0.5 nm in film thickness conversion).

For patterning the second electrode, a shadow mask having a structure in which a gap exists between one surface of the mask portion and the reinforcing line as shown schematically in FIG. 9 was used. The outline of the shadow mask is 120 x 84 mm, mask part 3
1, the thickness is 100 μm, the length is 100 mm, and the width is 25.
200 stripe-shaped openings 32 of 0 μm are arranged at a pitch of 300 μm. On the mask part, width 40
μm, thickness 35 μm, interval between two opposing sides is 200 μm
The mesh-shaped reinforcing wire 33 having a regular hexagonal structure is formed. The height of the gap is equal to the thickness of the mask part and 1
00 μm. Shadow mask is 4m in width with the same outer shape
m is fixed to a stainless steel frame 34.

The second electrode was formed by a vacuum evaporation method using a resistance wire heating method. The degree of vacuum at the time of vapor deposition was 3 × 10
⁻⁴ Pa or less, and the substrate was rotated with respect to two evaporation sources during the evaporation. Similarly to the patterning of the light emitting layer, a shadow mask for the second electrode was arranged on the front of the substrate so that they were in close contact with each other, and a magnet was arranged on the rear of the substrate. At this time, both are arranged such that the insulating layer matches the position of the mask portion. In this state, aluminum was deposited to a thickness of 240 nm to pattern the second electrode. The second electrode is patterned in a stripe pattern arranged at an interval in a direction orthogonal to the plurality of striped first electrodes arranged at an interval.

The substrate was taken out of the vapor deposition machine, kept in a reduced pressure atmosphere by a rotary pump for 20 minutes, and then transferred to an argon atmosphere having a dew point of -90 ° C. or less. Under this low humidity atmosphere, the substrate and the glass plate for sealing were sealed by bonding using a curable epoxy resin.

Thus, the width of 80 μm and the pitch of 100
A patterned green light emitting layer, a red light emitting layer and a blue light emitting layer are formed on a 816 ITO stripe-shaped first electrode having a width of 2 μm and a width of 2 μm perpendicular to the first electrode.
A simple matrix type color organic electroluminescent device in which 200 stripe-shaped second electrodes having a pitch of 50 μm and a pitch of 300 μm were arranged was fabricated. Since the three light emitting regions of red, green and blue form one pixel, the light emitting device of the present invention has two light emitting regions at a pitch of 300 μm.
It has 72 × 200 pixels. Since only the portion where the insulating layer exposes the first electrode emits light, one light emitting region has a width of 7
It is a rectangle having a length of 0 μm and a length of 250 μm.

When this display was driven line-sequentially, good display characteristics could be obtained. Since the edge portion of the first electrode was covered with the insulating layer, no short circuit due to electric field concentration was observed. In addition, since the cross section is a forward tapered shape, the thin film layer and the second electrode are formed smoothly without thinning or disconnection at the boundary portion of the insulating layer. No luminance unevenness was observed, and stable light emission was obtained. In addition, as a durability test,
When the light emission characteristics after holding at 85 ° C. for 250 hours were evaluated, good light emission was exhibited without a light emission region becoming smaller than in the initial stage.

Example 2 The procedure was the same as in Example 1 until an insulating layer made of varnish A was formed. Next, a negative photosensitive polyimide precursor (manufactured by Toray Industries, Inc.) is formed on the substrate on which the first electrode and the insulating layer are formed.
(UR-3100) was spin-coated and prebaked at 80 ° C. for 1 hour in a clean oven under a nitrogen atmosphere. After this film was exposed to UV through a photomask, it was developed by dissolving only the non-exposed portion with a developer (DV-505, manufactured by Toray Industries, Inc.) and rinsed with pure water. Then, under nitrogen atmosphere in a clean oven at 180 ° C for 30 minutes,
It was further heated at 220 ° C. for 30 minutes to cure. A partition orthogonal to the first electrode was formed. This electrically insulating partition is located on the insulating layer and has a length of 104 mm and a width of 30 μm.
m, the height is 4 μm, and 201 are arranged at a pitch of 300 μm.

The formation of the thin film layer was the same as in the first embodiment. The partitioning method was used to form the second electrode. That is, oblique deposition is performed in a state where the substrate is installed at an angle to the deposition source, and 2
40 nm of aluminum was deposited. Since the deposited material did not adhere to the portion of the partition wall which was shaded with respect to the deposited material, the stripe-shaped second electrode was patterned. Sealing was performed in the same manner as in Example 1.

Thus, the width of 80 μm and the pitch of 10
A patterned green light-emitting layer, a red light-emitting layer, and a blue light-emitting layer are formed on a 0 μm, 816 ITO stripe-shaped first electrode, and have a width of about 270 μm and a pitch of 300 μm perpendicular to the first electrode. A simple matrix type color organic electroluminescent device in which 200 second electrodes were arranged was produced. As in the first embodiment, this light emitting device also has 272 × 200 pixels at a pitch of 300 μm, and one light emitting region is a rectangle having a width of 70 μm and a length of 250 μm.

When this display device was driven line-sequentially, good display characteristics could be obtained as in the first embodiment. Since the edge portion of the first electrode was covered with the insulating layer, no short circuit due to electric field concentration was observed. In addition, since the cross section is a forward tapered shape, the thin film layer and the second electrode are formed smoothly without thinning or disconnection at the boundary portion of the insulating layer. No luminance unevenness was observed, and stable light emission was obtained. In addition, as a durability test, the light emission characteristics after holding at 85 ° C. for 250 hours were evaluated. As a result, good light emission was obtained without reducing the light emission region compared to the initial stage.

Example 3 The procedure was the same as in Example 1 up to the patterning of the first electrode.
Next, the concentration of the varnish A was adjusted, and patterning was performed in the same manner as in Example 1, whereby an insulating layer made of photosensitive polyimide was formed in the same manner as in Example 1 except that the thickness was about 3 μm.

Thereafter, a simple matrix type color organic electroluminescent device was manufactured in the same manner as in Example 1. When the present display device was driven line-sequentially, the same good display characteristics as in Example 1 could be obtained. Since the edge portion of the first electrode was covered with the insulating layer, no short circuit due to electric field concentration was observed. Further, since the cross section is a forward tapered shape, the thin film layer and the second electrode are thinned or cut off at the boundary between the insulating layers, even though the thickness of the insulating layer is thicker than in the first embodiment. The film was formed smoothly without occurrence of unevenness, and no luminance unevenness was observed in the light emitting region, and stable light emission was obtained. Further, since the thickness of the insulating layer was larger, the influence of mask flaws in mask deposition was less likely than in Example 1, and a light emitting region where light emission became unstable due to mask flaws was hardly observed. In addition, as a durability test, the light emission characteristics after holding at 85 ° C. for 250 hours were evaluated. As a result, good light emission was obtained without reducing the light emission region compared to the initial stage.

Example 4 Example 4 was repeated, except that varnish B was used instead of varnish A. When this display device was driven line-sequentially, good display characteristics could be obtained. Since the edge portion of the first electrode was covered with the insulating layer, no short circuit due to electric field concentration was observed. Further, since the cross section is a forward tapered shape, the thin film layer and the second electrode at the boundary portion of the insulating layer do not become thin or cause disconnection,
Since the film was formed smoothly, no luminance unevenness was observed in the light emitting region, and stable light emission was obtained. In addition, as a durability test, the light emission characteristics after holding at 85 ° C. for 250 hours were evaluated. As a result, good light emission was obtained without reducing the light emission region compared to the initial stage.

Example 5 The same procedure as in Example 3 was carried out except that varnish B was used instead of varnish A. When this display was driven line-sequentially, good display characteristics could be obtained as in Example 3.

Comparative Example 1 A negative photosensitive polyimide precursor (Toray Industries, Inc.)
UR-3100), and an insulating layer made of negative photosensitive polyimide was formed in the same manner as in the formation of the partition wall in Example 2. The thickness of the insulating layer was about 3 μm, the same as in Example 3, and the same insulating layer as in Example 3 was obtained except that the taper angle θ of the cross section at the boundary was about 90 °.

Thereafter, a simple matrix type color organic electroluminescent device was manufactured in the same manner as in Example 1. When this display device was driven line-sequentially, no short circuit due to electric field concentration was observed because the edge portion of the first electrode was covered with the insulating layer, but since the cross section of the insulating layer was almost rectangular, In addition, the thin film layer and the second electrode tended to be thinner at the boundary between the insulating layers, and luminance unevenness was observed in the light emitting region.

Comparative Example 2 Example 1 was repeated except that a varnish A was replaced with a polyimide-based positive photoresist having an o-nitrobenzyl group.
The pattern processing of the insulating layer was performed in the same manner as described above. However, the pattern workability was poor, and a desired insulating layer pattern could not be obtained.

Thereafter, a simple matrix type color organic electroluminescent device was manufactured in the same manner as in Example 1. When the display device was driven line-sequentially, the insulating layer pattern was defective, so that the thin film layer and the second electrode were thinned or cut off at the boundary of the insulating layer, short-circuiting due to electric field concentration, poor shape of the light emitting region, Brightness unevenness was observed in the light emitting region.

Comparative Example 3 Positive resist OFPR-800 instead of varnish A
(Manufactured by Tokyo Ohka Kogyo Co., Ltd.), spin-coating is applied to the substrate on which the first electrode is formed, and 8
The pattern processing of the insulating layer was performed in the same manner as in Example 1 except that the film was prebaked at 0 ° C. for 2 minutes, exposed, developed and rinsed, and then cured at 180 ° C. for 8 minutes on a hot plate.

Thereafter, a simple matrix type color organic electroluminescent device was manufactured in the same manner as in Example 1. When this display device was driven line-sequentially, good light emission was shown at the initial stage. However, when the light-emitting characteristics after holding at 85 ° C. for 250 hours were evaluated as a durability test, the light-emitting region was found to be about 80% as compared with the initial state. Has become smaller.

[0091]

[Table 1]

[0092]

According to the present invention, the display device in which the insulating layer is made of a positive photosensitive polybenzoxazole does not require the use of a photoresist unlike the prior art, and the insulating layer made of polybenzoxazole is used. The layers can be patterned in a simpler and fewer steps.
Furthermore, since the cross section of the boundary portion of the insulating layer can be easily formed into a forward tapered shape, for example, a thin film layer formed thereon can be formed smoothly, and the operation stability of the display device is not impaired. .

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of the shape of an insulating layer of the present invention.

FIG. 2 is a sectional view taken along line X-X ′ of FIG. 2;

FIG. 3 is an enlarged sectional view of a boundary portion of an insulating layer in FIG. 2;

FIG. 4 is a cross-sectional view showing a substrate on which a first electrode is patterned.

FIG. 5 is a cross-sectional view showing a state where a positive photosensitive polyimide is applied on a substrate.

FIG. 6 is a cross-sectional view showing how a polyimide precursor film is exposed.

FIG. 7 is a cross-sectional view showing a state where the polyimide precursor film after exposure is developed.

FIG. 8 is a plan view schematically showing a shadow mask for patterning a light emitting layer.

FIG. 9 is a plan view schematically showing a shadow mask for patterning a second electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 11 1st electrode 14 Insulating layer 15 Opening 16 Boundary part 17 Exposure part 18 Photomask 31 Mask part 32 Shadow mask opening 33 Reinforcement line 34 Frame

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/22 H05B 33/22 Z (72) Inventor Masao Tomikawa 1-1-1 Sonoyama, Otsu-shi, Shiga No. Toray Co., Ltd. Shiga Plant F-term (reference) 2H090 HA03 HB07X HC05 3K007 AB02 AB04 AB15 AB17 AB18 CA01 CA03 CA04 CB01 DA00 DB03 EB00 FA01 5C094 AA43 BA03 BA27 CA19 DA15 EA04 EA07

Claims (5)

[Claims] A first electrode formed on the substrate, an insulating layer formed on the first electrode so as to partially expose the first electrode, and a first electrode provided opposite to the first electrode. A display device comprising two electrodes, wherein the insulating layer has the following general formula (1)
A display device comprising, as essential components, a polymer having a structural unit represented by the following as a main component and a photoacid generator. Embedded image (R ¹ represents a divalent organic group having at least 2 or more carbon atoms, R ² represents a divalent to tetravalent organic group having at least 2 or more carbon atoms, and m represents 3 to 100,000.
Indicates an integer up to. ) 2. The display device according to claim 1, wherein said photoacid generator is an o-quinonediazide compound. 3. The display device according to claim 1, wherein the insulating layer is formed so as to cover an edge portion of the first electrode. 4. The display device according to claim 1, wherein a section of the insulating layer at a boundary where the insulating layer exposes the first electrode has a forward tapered shape. 5. A display device comprising: a first electrode formed on a substrate; a thin film layer formed on the first electrode, the light emitting layer including at least an organic compound; and a second electrode formed on the thin film layer. 2. The display device according to claim 1, wherein the display device comprises an organic electroluminescent element including an electrode.