JP2008034198A - Forming method of thin film pattern, manufacturing method of organic el display, and organic el display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forming method of a thin film pattern which has solved various problems of a conventional lift-off method, an organic EL display panel of low cost and with high reliability utilizing this method, its manufacturing method. <P>SOLUTION: The forming method of a thin film pattern comprises a process to form an insulating thin film on a substrate on which a resist pattern is formed on the surface and a process to form the insulating thin film by lifting-off the thin film formed on the resist, and the crown part of the resist formed on the substrate has an overhang portion and in the process of forming the insulating thin film pattern, the top end of the overhang portion of the resist is deformed so as to come closer to the substrate. A manufacturing method of an organic EL display using this thin film forming method and an organic EL display having a narrow width of the taper region at the end part of the insulating thin film are provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for forming a thin film pattern using a lift-off method, a method for manufacturing an organic electroluminescence (hereinafter referred to as organic EL) display, and an organic EL display.

  One of organic EL display panels using electroluminescence of organic compounds is a passive matrix (simple matrix) type display panel. The passive matrix display panel includes a first electrode composed of a plurality of conductive layers having a line pattern, a second electrode composed of a plurality of conductive layers having a line pattern orthogonal to the first electrode, and an organic sandwiched between the two electrodes. It is composed of a light emitting layer. A display unit is formed by forming one pixel with a light emitting unit in a crossing region of the first electrode and the second electrode as a unit and arranging a plurality of pixels.

  In the passive matrix display panel, a color conversion filter is formed between the first electrode and the transparent substrate in order to enable full color display.

  Each of the first electrode and the second electrode is patterned in a stripe shape, and each electrode has an edge. This edge portion is a portion where the electrode shape is changing rapidly, and is a portion where electric field concentration is likely to occur. In the portion where the electric field is concentrated, the organic EL layer causes dielectric breakdown, causing a short circuit (crosstalk) between the first electrode and the second electrode. As a result, a display defect such that all pixels in the short-circuited first electrode or second electrode portion always emit light occurs.

There is a proposal to prevent a short circuit between the first electrode and the second electrode (see, for example, Patent Document 1).
In this proposal, an electroluminescent element comprising a plurality of electrode pairs facing each other and an organic EL layer disposed between the electrodes, the electrode being sandwiched between the organic EL layer and at least one electrode, Disclosed is an insulating layer extending along an edge. This insulating layer blocks the leakage current between the electrode pairs.

  In addition, since the material for forming the organic EL layer is vulnerable to moisture, the second electrode cannot be formed by a photolithographic method, which is a wet process, and is generally formed by a vapor deposition method. At this time, an insulating film for ensuring insulation between the second electrode and the first electrode is provided, and the stripe length of the second electrode is secured to ensure insulation between the plurality of stripe-shaped second electrodes. There is also a proposal of providing a partition extending in parallel with the direction (see, for example, Patent Document 2).

  FIG. 3 shows a schematic perspective view and a schematic partial cross-sectional view of the bottom emission type organic EL display of the present invention. The structure of the organic EL display proposed in Patent Document 2 is not limited to the material of the insulating film formed on the substrate. Further, except for the shape details, the structure is the same, and the organic EL display described in Patent Document 2 will be described with reference to FIG.

  As shown in FIG. 3, a plurality of first electrodes are formed in parallel stripes on a substrate 101 having a color filter and a planarizing film covering the color filters, and a direction orthogonal to the stripe longitudinal direction of the first electrodes 102 and An insulating film 103 is formed so as to extend in a direction parallel to the longitudinal direction of the stripe of the first electrode between the adjacent first electrodes. Then, after an inversely tapered partition 104 is formed on the insulating film 103 extending in a direction orthogonal to the stripe longitudinal direction of the first electrode, an organic EL layer 105 and a second electrode 106 are formed by vapor deposition, and organic The insulation between the second electrodes 106 formed on the EL layer 105 and between the second electrode 106 and the first electrode 102 is ensured. The insulating film 103 and the partition wall 104 are formed of a photoresist resin. 3A is a schematic perspective view illustrating a state in which the formation of the first electrode 102, the insulating film 103, and the partition wall 104 is completed on the substrate 101. FIGS. 3B and 3C illustrate the second electrode 106. FIG. FIG. 2 shows a partial schematic cross-sectional view in a state where the formation of is completed.

The organic EL layer 105 is formed on the first electrode 102 by vapor deposition as a very thin thin film. Therefore, if fine particles are adhered on the first electrode 102, the organic EL layer 105 is not formed well, and the organic EL element in that portion becomes defective. The adhesion of the fine particles or the like may occur when the first electrode is formed of a conductive transparent material such as ITO or when the insulating film 103 and the partition wall 104 are subsequently formed. Therefore, recently, a process of performing plasma treatment or UV / O ₃ treatment before the formation of the organic EL layer 105 is provided.

  As a material for the insulating film, an organic material such as polyimide or novolac resin is used. An advantage of using such an organic material is that an insulating film can be easily formed with a film thickness having a sufficient withstand voltage by using a photolithography method or the like. However, since these materials have high hygroscopicity, there is a high possibility that moisture that causes alteration of the organic light emitting layer is contained, and it is necessary to sufficiently remove the water before forming the organic light emitting layer.

  When high reliability is required as a display, for example, in an in-vehicle display, an organic EL display is required to have a small decrease in luminance even under adverse conditions such as high temperature and high humidity. In particular, when driving at a high temperature, the release of moisture from the organic material is accelerated as the temperature rises and diffuses into the organic EL layer. This release of moisture causes alteration of the organic EL layer and becomes a factor of reducing the light emitting area.

In addition, an insulating film made of an organic material may be etched at the surface and end portions in a plasma treatment or UV / O ₃ treatment step before forming the organic EL layer. When the surface or edge of the insulating film is etched, the etched organic matter may reattach and contaminate the first electrode surface, thereby degrading the performance of the organic EL element.

  As a method for solving such a problem, it is conceivable to use an inorganic material for the insulating film material. As one of such methods, there is a proposal of using silicon oxide or silicon nitride as an insulating film material (see, for example, Patent Document 3). Wet etching and dry etching have been proposed as a method for patterning an insulating film using these inorganic materials. However, when silicon oxide and silicon nitride are processed by wet etching, the supporting substrate glass is also eroded at the same time. As a result, there arises a problem that the glass substrate becomes clouded. Further, dry etching requires an expensive vacuum device, and there is a problem that the manufacturing cost is increased.

  There is also a proposal for producing an inorganic insulating film pattern using a photosensitive inorganic resist (see, for example, Patent Document 4). The inorganic resist uses water as a solvent, and it is necessary to perform a baking process at a high temperature of 200 ° C. or higher in order to sufficiently remove moisture in the film. For this reason, when a substrate having a color conversion filter layer formed thereon is used as a support substrate for a display, the dye in the color conversion filter is thermally decomposed during baking, thereby impairing the color conversion ability. In addition, there are still problems with inorganic resists, such as residues that are likely to remain, and sufficient sensitivity has not been obtained.

  On the other hand, there is a proposal of forming a pattern of an inorganic insulating film using a lift-off method (see, for example, Patent Document 5). When the lift-off method is used, a physical vapor deposition method such as a vacuum heating deposition method, an electron beam deposition method, an ion plating method, or a sputtering method can be used as a method for forming an insulating film. From this point of view, it is preferable to use an ion plating method or a magnetron sputtering method, and productivity and yield can be improved by using these methods.

  However, in these film formation methods, gas such as argon, oxygen, and nitrogen is introduced and discharged, so that the pressure of the film formation atmosphere is higher than that in the vacuum evaporation method, and the particles that protrude from the source and target are It will reach the substrate while colliding with the gas and being scattered, and the film-forming particles will enter under the lift-off resist overhang part or into the undercut region, which tends to form a continuous film from the substrate to the resist sidewall. When a continuous film is formed, there arises a problem that lift-off becomes difficult and a residue called “burr” remains.

  As a method for avoiding such a problem related to the lift-off method, there is a proposal to make the shape of the lift-off resist satisfy 3y−2x + 1 ≦ 0 when the undercut amount is x and the undercut height is y (patent) Reference 6). In addition, as a method for controlling the resist shape, a proposal for a two-layer resist using polymethylglutarimide (PMGI), polyimide resin or the like as a lower layer resist, and a resist using a novolac resin not mixed with these as an upper layer (patent document) 6, 7, 8)), a resin composed of a radical polymer having a hydroxyl group and / or a carboxyl group and a quinonediazide group-containing compound in the lower layer, and a radical polymer having a phenolic hydroxyl group and a quinonediazide group-containing compound as the upper layer. There is also a proposal of a two-layer resist using a resin (see Patent Document 9).

In addition, the power applied to the target during sputtering is 100 mW / m ² or less, the film forming pressure is 0.1 Pa or less, the distance between the target and the substrate is 150 mm or more, or a collimator is installed. There is also a proposal of a method for controlling the incident angle to the substrate (see Patent Document 10).

  On the other hand, after forming a lift-off resist pattern and then forming a metal thin film, instead of lifting off the resist and the metal film on the resist with a solvent or the like, carbon dioxide dry ice particles are sprayed onto the substrate at a high speed to form the resist and the resist on the resist film. There is also a proposal to lift off by blowing off a metal thin film (see Patent Document 11).

Japanese Patent No. 2911552 JP-A-8-315981 Japanese Patent Laid-Open No. 9-330792 JP 2003-229251 A JP 2004-319143 A Japanese Patent Laid-Open No. 7-161711 JP-A-6-267843 JP-A-9-92605 JP 2003-287905 A JP 2002-43248 A JP 2000-58546 A

  However, as shown in FIG. 6B and FIG. 6C, if the lift-off resist overhang amount or undercut amount is controlled to suppress the entry of film-forming particles into the side surface of the lift-off resist. In addition, the width of the taper that is naturally formed at the end of the thin film pattern formed on the substrate is increased, which makes it difficult to form a fine pattern with a predetermined film thickness. More specifically, when the undercut amount of the lift-off resist (the width of the undercut portion in the direction perpendicular to the end face) is required to form a linear pattern, the width of the tapered portion is 5 μm or more, and 10 μm. When a pattern with the following line width is formed, there is no flat part with a uniform thickness at the center part in the line width direction, the center part in the line width direction is the thickest, and the film thickness is non-uniform only consisting of tapered parts on both sides. End up. When such a thin film pattern is used as the insulating film on the first electrode of the organic EL display, as shown in FIG. 7, the film thickness of the insulating film becomes thin at the end of the first electrode, which may cause dielectric breakdown. . Alternatively, the dielectric breakdown can be avoided by forming a thin tapered portion inside the pixel, but the opening of the insulating film, that is, the light emitting region becomes narrow, and the light emission luminance of the organic EL display is reduced. Cause problems.

  The method described in Patent Document 10 has a problem in that productivity is reduced at the expense of film formation speed.

The lift-off method described in Patent Document 11 is effective for removing “burrs”, but requires heating of the substrate to prevent the substrate from being cooled by dry ice, and further processing in a dry atmosphere. I need. In addition, when the substrate is an insulating material such as glass, there is a problem that enormous static electricity is generated due to friction with CO ₂ and the substrate is charged and collected. A CO ₂ dry ice treatment apparatus for solving these problems is expensive.

  That is, the present invention has been made in view of the above-described problem that exists in the lift-off method as a method for inexpensively forming an insulating film on the first electrode of an organic EL display with an inorganic material. An object of the present invention is to provide a method for forming a thin film pattern by the lift-off method, which is inexpensive and free from the above-described problems, a method for manufacturing an organic EL display using the thin film formation method, and a highly reliable organic EL display panel.

That is, the method for forming a thin film pattern of the present invention comprises a step of forming a resist pattern on a substrate,
Forming an insulating thin film on a substrate having a resist pattern formed on the surface;
The step of forming the insulating thin film pattern by removing the resist with a solvent and lifting off the thin film formed on the resist, and the top of the resist formed in the step of forming the pattern made of the resist on the substrate In contrast, in the step of forming the insulating thin film pattern having an overhang portion protruding in a parallel direction, the resist is deformed so that the tip of the resist overhang portion approaches the substrate.

In the method for forming a thin film pattern of the present invention, when the thickness of the central portion of the insulating thin film is t, and the height of the overhang portion bottom after deformation is y ′,
t ≧ y ′ ≧ 0.5t
It is preferable that

Further, when the length of the overhang portion of the resist formed in the step of forming the resist pattern is x, and the height from the substrate at the bottom of the overhang portion is y,
10t ≧ x ≧ 5.5t, 2t ≧ y> t
More preferably.

The method for producing an organic EL display of the present invention is a method for producing an organic EL display in which at least a first electrode, an insulating thin film, an organic EL layer and a second electrode are sequentially laminated on a substrate,
(1) forming a first electrode on a substrate;
(2) forming an insulating thin film on the substrate on which the first electrode is formed, having an opening on the first electrode and covering at least the first electrode end;
(3) forming an organic EL layer;
(4) forming a second electrode, wherein the formation of the insulating thin film in the step (2) is the above-described thin film forming method.

  The organic EL display according to the present invention is formed by sequentially laminating at least a first electrode, an insulating thin film, an organic EL layer, and a second electrode on a substrate, and the insulating thin film has an opening on the first electrode. A thin film made of an inorganic material so as to cover the end of the first electrode, and the thickness of the insulating thin film near the opening is 0.9 t or less, where t is the thickness of the central portion of the insulating thin film The width is 10t or less.

  According to the method for forming a thin film pattern of the present invention, the occurrence of “burrs” at the time of lift-off can be suppressed, and the width of the tapered region at the end of the thin film formed by the resist shielding effect can be reduced. When such a thin film pattern is used as an insulating film on the electrode, the thickness of the insulating film is reduced at the end of the first electrode as shown in FIG. By forming the portion inside the pixel, it is possible to form a fine pattern that does not require the opening of the insulating film, that is, the light emitting region to be excessively narrow.

  Moreover, according to the manufacturing method of the organic EL display of the present invention in which the insulating film on the first electrode is formed by using the thin film pattern forming method, the inorganic insulating thin film can be formed at a low cost. The display can be stably driven for a long time while suppressing the expansion of the non-light emitting portion of the organic EL display.

  Hereinafter, the insulating thin film pattern forming method, the organic EL display and the manufacturing method thereof of the present invention will be described with reference to the drawings as appropriate. The insulating thin film pattern forming method, the organic EL display and the manufacturing method thereof shown in the drawings are as follows. It is an illustration and this invention is not limited to these.

  FIG. 1 is an enlarged schematic cross-sectional view (however, not a uniform magnification) showing a thin film pattern forming step by an insulating thin film pattern forming method of the present invention. FIG. 1A is a view showing a state in which a lift-off resist is formed on a substrate. Here, the lift-off resist pattern is formed so that the top of the resist has an overhang portion projecting parallel to the substrate so that the cross-section becomes a T-shape as seen in FIG. This lift-off resist pattern may be formed by laminating two kinds of resists so as to have such a shape. If the resist can form an overhang structure with a single layer, the lift-off resist pattern is formed with a single layer. Also good. When laminating two types of resist, it is possible to use two types of photoresist materials with different development speeds, or a laminate of a resin and a photoresist that is not photosensitive and soluble in an alkaline developer, and controls the resist shape. Becomes easy.

  In the case of two layers, first, as a lower layer, a PMGI resin or a polyimide resin is applied and dried so as to have a predetermined film thickness, and a photoresist that does not mix with the lower layer material is laminated thereon, and a desired shape is obtained. Irradiation with ultraviolet light is performed using the resulting photomask. Next, by developing, a resist pattern is obtained, and at the same time, the lower layer resin is etched with a developer using the resist pattern as a mask.

  A resist pattern having the structure of FIG. 1A having an overhang portion can be obtained by etching the lower layer resin so that the line width of the lower layer resin pattern is narrower than the line width of the upper layer resist pattern. If the lower layer resin is insoluble in the solvent used for dissolving the upper layer resist, the upper and lower layers are not mixed. As such an upper layer resist material, a novolak resist or an acrylic resist can be used.

  In the case of a single layer resist, a novolak-type chemically amplified resist can be used.

As shown in FIG. 1B, the resist pattern shown in FIG. 1A is the thickness of the central portion of the insulating thin film formed in the thin film forming process described later (average thickness of the thin film excluding the end portion). T, where y ′ is the height from the substrate at the bottom of the overhang tip after the lift-off resist deformation in the thin film formation step as shown in FIG.
t ≧ y ′ ≧ 0.5t
It is preferable that

  When y ′ falls within the above range, the penetration of the thin film under the lift-off resist overhang portion can be greatly suppressed, and as a result, the thin portion of the insulating thin film end on the substrate can be greatly reduced. Become. Specifically, the width of the portion of the end portion of the insulating thin film on the substrate where the film thickness is 0.9 t or less can be 10 t or less.

  If y ′ is larger than t, deformation is insufficient and the thin film lifts off the resist overhang part, and a continuous film is formed on the resist side wall. The width of the portion of 0.9 t or less becomes wide, and when applied to an organic EL display, there is a risk that dielectric breakdown at the end portion is likely to occur or the light emitting portion area is unnecessarily narrowed, and y ′ is 0 If it is smaller than 0.5 t, the resist overhang portion may come into contact with the insulating thin film during the formation of the insulating thin film, which may make it difficult to lift off or form burrs at the contact portion with the insulating thin film.

In order to set y ′ within the above range, the length of the overhang portion of the resist formed in the step of forming the resist pattern as shown in FIG. Where y is the height of
10t ≧ x ≧ 5.5t, 2t ≧ y> t
It is preferable that

  By setting x and y within such a range, when the overhang portion is deformed during the formation of the insulating thin film, y ′ in the above range can be obtained.

  When x is larger than 10 t, the bottom of the lift-off resist overhang contacts the substrate due to deformation during thin film formation, and when the lift-off resist is removed, the lift-off resist and the thin film are not completely removed, and a predetermined opening is obtained. Even if the lift-off is successful, the width of the insulating film with a film thickness of 0.9 t or less becomes wide, and there is a risk of causing an insulation failure. On the other hand, when x is smaller than 5.5 t, the deformation of the overhang portion during the thin film formation is insufficient, and the thin film lifts up under the resist overhang portion, and a continuous film is formed on the resist sidewall. When it is applied to an organic EL display, there is a risk that dielectric breakdown at the end portion is likely to occur or the area of the light emitting portion is unnecessarily narrowed.

  If y is larger than 2t, it may be difficult to make y 'after deformation of the overhang portion during thin film formation less than t. If y is less than t, deformation of the lift-off resist may occur due to deformation during thin film formation. There is a possibility that the bottom of the overhang tip may come into contact with the substrate.

  As will be described later, an insulating thin film is formed on the substrate with the lift-off resist pattern. In order to control the deformation amount of the lift-off resist at the time of forming the thin film, it is preferable to perform post-baking after developing the lift-off resist. Since the lift-off resist may be deformed by post-baking, the post-baking temperature is preferably 90 ° C. or higher and lower than 120 ° C. If the post-baking temperature is less than 90 ° C., the adjustment of the deformation amount of the lift-off resist at the time of forming the thin film becomes insufficient.

  A thin film having electrical insulation is formed on a substrate with a lift-off resist pattern having the shape shown in FIG. This insulating thin film is formed by physical vapor deposition (PVD). Any insulating thin film material can be formed by PVD, and any material having sufficient withstand voltage can be used. Specifically, silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, tantalum oxide, aluminum nitride Etc. can be used.

  As the PVD, a sputtering method or an ion plating method is preferably used, and a magnetron sputtering method is more preferable as the sputtering method because the film forming speed is high and the productivity is excellent.

  During the formation of this insulating thin film, the substrate is exposed to plasma or heated by receiving source heating radiation, but this heating and the formation of the thin film cause the tip of the lift-off resist overhang to approach the substrate. After the film formation, the cross-sectional structure shown in FIG. The temperature reached by the substrate during film formation is preferably set to a temperature within an appropriate range in order to control changes in the resist pattern shape. This preferred temperature varies depending on the type of resist material used, but it is 120 to 150 ° C. when a two-layer resist is used to form a resist pattern and a novolac resist or an acrylic resist is used for the upper layer. Is desirable. In the case of a single-layer resist pattern using a novolak-type chemically amplified resist for lift-off (for example, ZPN1100 manufactured by Nippon Zeon or SIPR-9684 manufactured by Shin-Etsu Chemical), the substrate arrival temperature is preferably 100 to 120 ° C.

  The substrate arrival temperature at the time of film formation can be controlled by the discharge power and the substrate transport speed in the case of the sputtering method, and can be controlled by the discharge power, the source heating temperature, and the substrate transport speed in the case of the ion plating method.

The substrate as shown in FIG. 1B obtained as described above is peeled off using a resist-soluble solvent and the thin film on the resist is lifted off to obtain the structure shown in FIG. 1C. Examples of the resist-soluble solvent include acetone, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL) and the like, as well as commercially available resist stripping solutions such as stripping solutions 104 and 105 manufactured by Tokyo Ohka Kogyo Co., Ltd. 106, AZ Electronic Materials AZ remover series, etc. can also be used.
In the insulating thin film on the substrate thus obtained, when the thickness of the central portion of the thin film is t, the width of the portion where the thickness of the peripheral portion is 0.9 t or less is 10 t or less, and there are few portions with low withstand voltage. It is a film. When the peripheral portion has a thickness of 0.9 t or less and a width of 10 t or less, the display has a high aperture ratio.

Next, the organic EL display of the present invention will be described with reference to FIGS.
FIG. 2 is an enlarged schematic cross-sectional view showing a process of forming an insulating thin film by the organic EL display manufacturing method of the present invention. 3A is a schematic partial perspective view of the organic EL display of the present invention, and FIGS. 3B and 3C are schematic cross-sectional views showing the configuration of one embodiment of the organic EL display of the present invention. FIG. 4 is a schematic sectional view showing the configuration of another embodiment of the organic EL display of the present invention. FIG. 5A is a cross-sectional SEM image of the lift-off resist formed on the first electrode, and FIG. 5B is a cross-sectional SEM image of the first electrode, the lift-off resist, and the insulating film after the formation of the insulating thin film.

First, a bottom emission type EL display as shown in FIG. 3 will be described.
The first electrode is provided on the transparent substrate, and the transparent substrate preferably has a patterned color conversion filter layer, a planarization layer, and a passivation layer on the surface. When the first electrode is formed, the color conversion filter layer, the planarization layer, and the passivation layer formed in this order on the substrate are formed, and the first electrode is formed on the passivation layer. Means that In these drawings, components other than the first electrode, the insulating film, the organic EL layer, the second electrode, and the second electrode separation partition are not shown, and the color conversion filter layer formed on the transparent substrate, and these The polymer film layer for planarization and the passivation layer for moisture prevention, etc. provided on this layer are collectively referred to as a “first electrode substrate”.

  The color conversion filter layer is a general term for a color filter layer, a color conversion layer, and a laminate of a color filter layer and a color conversion layer.

  The color conversion layer is a layer that absorbs light in the near-ultraviolet region or visible region, particularly light in the blue or blue-green region, emitted from the organic EL layer, and converts the wavelength distribution into visible light having a different wavelength. . Examples of the dye or pigment used in the color conversion layer include organic fluorescent dyes. For example, examples of fluorescent dyes that absorb blue to blue-green light emitted from the organic EL layer and emit red light include the following organic fluorescent dyes. That is, rhodamine B, rhodamine 6G, rhodamine 3B, rhodamine 101, rhodamine 110, sulforhodamine, basic violet 11, basic red 2, and other rhodamine dyes, cyanine dyes, 1-ethyl-2- [4- (p -Dimethylaminophenyl) -13-butadienyl] -pyridium-perchlorate (pyridine 1) and other pyridine dyes or oxazine dyes. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used as long as they can emit desired fluorescence. Examples of fluorescent dyes that absorb blue to blue-green light emitted from the organic EL layer and emit green fluorescent light include the following organic fluorescent dyes. That is, 3- (2-benzothiazolyl) -7-diethylaminocoumarin (coumarin 6), 3- (2′-benzoimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 7), 3- (2′-N-methyl) Benzimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 30), 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidine (9,9a, 1-gh) coumarin (coumarin 153 Or the like, or basic yellow 51 which is a coumarin dye-based dye, and naphthalimide dyes such as solvent yellow 11 and solvent yellow 116. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used as long as they can emit desired fluorescence.

  In addition, the organic fluorescent dye is applied to polymethacrylic acid ester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer resin, alkyd resin, aromatic sulfonamide resin, urea resin, melamine resin, benzoguanamine resin, and a mixture of these resins. An organic fluorescent pigment may be prepared by kneading in advance.

  The color filter layer can be formed using a material (for example, a color filter material for a liquid crystal display) in which any pigment known in the art is dispersed in a matrix resin.

  In order to enable full color display, it is desirable to have at least a blue (B) conversion filter layer, a green (G) conversion filter layer, and a red (R) conversion filter layer.

  The red conversion filter layer is preferably a laminate of a red conversion layer and a red color filter layer. This is because, when an organic EL layer that emits light in the blue or blue-green region is used as a light source, if light from the organic EL layer is passed through a simple red filter to obtain light in the red region, the wavelength of the red region is originally This is because the output light becomes extremely dark due to the small amount of light. By converting the wavelength distribution of light in the blue or blue-green region into red light by the red conversion layer, it is possible to output light in the red region having sufficient intensity.

  The green conversion filter layer is preferably a laminate of a green conversion layer and a green color filter layer. However, when the light emitted from the organic EL layer contains a sufficiently strong green component, only the green color filter layer may be used.

  The blue conversion filter layer may include a blue conversion layer that performs wavelength distribution conversion of near-ultraviolet light or blue-green light emitted from the organic EL layer and outputs blue light, and a blue color filter layer. However, when the organic EL layer emits blue to blue-green light, it is preferable to use only the blue color filter layer.

  When the organic EL layer emits white light, it is possible to obtain a desired color using only the color filter layer for each color, but by using each color conversion layer, the three primary colors with higher efficiency than the case of only the color filter layer. Can be obtained.

This color conversion filter layer is patterned.
Here, the color conversion filter layer being patterned means that one or a plurality of color conversion filter layers are formed, and each of the color conversion filter layers is divided into a plurality of portions. To do. An example of such a pattern is a line pattern.

  In the present invention, the planarization layer is a layer for substantially eliminating and flattening the surface irregularities formed for the patterned color conversion filter layer provided on the transparent support substrate. It can be formed of any material known in the art. Preferably, it is formed from polyimide or acrylic resin.

For the passivation layer, materials such as inorganic oxides and inorganic nitrides such as SiO _x , SiN _x , SiN _x O _y , AlO _x , TiO _x , TaO _x , and ZnO _x can be used. In addition, polymer materials such as an imide-modified silicone resin and a material in which an inorganic metal compound (TiO, Al ₂ O ₃ , SiO ₂ or the like) is dispersed in acrylic, polyimide, silicone resin, or the like can also be used.

  The first electrode is composed of a plurality of conductive layers having a line pattern, and each of the conductive layers is formed of a display portion provided on the first electrode substrate described above, a connection portion between the external drive circuit, and a lead portion. Yes. As the material for the first electrode, ITO, In—Zn oxide, ATO, or the like can be used. In particular, with In—Zn oxide, a relatively low resistance film can be obtained by film formation at room temperature, and patterning with a weak acid can be performed. Is preferable. Patterning can be performed by wet etching using a commercially available photoresist.

  Next, an insulating thin film is formed on the patterned first electrode. The insulating thin film has an opening necessary for light emission. Although the lift-off method is used to form the opening of the insulating thin film according to the present invention, it is not necessary to use strong acid or strong alkali to remove the inorganic insulating thin film in the opening, and there is an advantage that the surface of the first electrode is not roughened.

  First, a lift-off resist is formed on the first electrode in a region where an insulating thin film is not formed, and then the inorganic insulating thin film is formed to a desired film thickness by physical vapor deposition (PVD) such as sputtering or ion plating. Finally, the resist is peeled off with a solvent, and the inorganic insulating thin film on the resist is lifted off to obtain an inorganic insulating thin film pattern.

  The materials and shapes of the lift-off resist and the inorganic insulating film are as described in the thin film pattern forming method.

  By setting the values of x and y before film formation of the insulating thin film to 10t ≧ x ≧ 5.5t, 2t ≧ y> t, the insulating film material can be prevented from wrapping around the side surface of the lift-off resist. By deforming and setting the value of y ′ after film formation to be t ≧ y ′ ≧ 0.5 t, the deposition of the insulating thin film material on the side wall of the wrist-off resist is prevented, and the end of the inorganic insulating thin film on the first electrode The film thickness increases abruptly as it goes from the center to the center, and the region where the film thickness is 0.9 t or less can be within 10 t from the end.

  5A, the values corresponding to x and y in FIG. 1 are 2.4 μm and 0.60 μm, respectively. In FIG. 5B, the values corresponding to t and y ′ in FIG. 33 μm and 0.18 μm, and the relationship between x, y, y ′ and t is within the above range.

  In this way, as shown in FIGS. 3B and 3C, it is possible to form the inorganic insulating thin film with a substantially uniform film thickness except for the end portion of the first electrode processed into a tapered shape. .

  A partition is formed on the insulating thin film formed on the first electrode. An organic EL layer is provided on the first electrode between the partition walls. The organic EL layer includes at least an organic light emitting layer, and contains a hole injection layer, a hole transport layer, an electron transport layer and / or an electron injection layer as necessary.

That is, the organic EL layer may consist of only (A) the organic light emitting layer, and from the first electrode side,
(B) Hole injection layer / organic light emitting layer (C) organic light emitting layer / electron transport layer (D) hole injection layer / organic light emitting layer / electron transport layer (E) hole injection layer / hole transport layer / organic The light emitting layer / electron transport layer (F) hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection layer may be employed.

    As the material of each layer of the organic EL layer, known materials can be used. In order to obtain light emission from blue to blue-green, in the organic light emitting layer, for example, a fluorescent whitening agent such as benzothiazole, benzimidazole, and benzoxazole, a metal chelated oxonium compound, a styrylbenzene compound, Aromatic dimethylidin compounds are preferably used. Examples of the electron injection layer include alkali metals such as lithium and sodium, alkaline earth metals such as potassium, calcium, magnesium, and strontium, or electron injecting metals such as fluorides thereof, and alloys with other metals. Or a material such as a compound can be used. As the electron transport layer, a metal complex such as an aluminum quinoline complex, oxadiazole, a triazole compound, or the like can be used. For the hole injection layer, aromatic amine compounds, starburst amines, benzidine amine multimers, copper phthalocyanine (CuPc), and the like can be used. As the hole transport layer, a starburst amine, an aromatic diamine, or the like can be used.

  The second electrode may be, for example, an electron injecting metal made of an alkali metal such as lithium or sodium, an alkaline earth metal such as potassium, calcium, magnesium, or strontium, or an alloy of these fluorides and other metals. It can be obtained by using a material such as a compound, followed by organic EL layer formation, and vapor deposition using a heating vapor deposition apparatus without breaking the vacuum.

  Although the embodiment of the organic EL display of the present invention described above is an example of a bottom emission type, there is a top emission type organic EL display as another embodiment of the present invention. In this top emission type organic EL display, a first electrode, an insulating film, an organic EL layer, and a second electrode are provided on a substrate, and at least a color conversion filter layer is provided on a transparent substrate on the second electrode side. A color conversion filter substrate is provided. A passivation layer is preferably provided on the color conversion filter layer, and a planarization layer may be provided between the color conversion filter layer and the passivation layer so as not to impair the gas barrier properties of the passivation layer. The second electrode is provided on the passivation layer.

  The first electrode is preferably reflective, such as high reflectivity metals such as Al, Ag, Mo, W, Ni and Cr, high reflectivity amorphous alloys such as NiP, NiB, CrP and CrB, and NiAl. A highly crystalline microcrystalline alloy can be mentioned. When the first electrode is in contact with the electron transport layer, for example, an alkali metal such as lithium or sodium, an electron injecting metal such as an alkaline earth metal such as potassium, calcium, magnesium, or strontium, or these and other metals. An alloy is preferably provided between the electron transport layers. When the first electrode is electron-injecting, the second electrode needs to be made by hole injection, and it is a bottom emission type display except that a transparent electrode material such as ITO, In-Zn oxide, ATO is used. The same material as used is used.

  A top emission type organic EL display using a color conversion filter sequentially forms a first electrode, an insulating thin film, an organic EL layer, and a second electrode on a first substrate, while on a second substrate (transparent substrate). Then, a color conversion filter is formed to produce a color conversion filter substrate. The color conversion filter substrate also serves as a sealing substrate. At the time of bonding, it is necessary to align the first electrode pattern and the color conversion filter pattern so that they match.

  Hereinafter, an example of producing an organic EL display according to the present invention will be described with reference to the drawings. The organic EL display was formed with a pixel number of 160 × 120 × RGB and a pixel pitch of 0.33 mm.

[Production of blue filter]
Blue filter material (manufactured by Fuji Film Electronic Materials; Color Mosaic CB-7001) is applied onto Corning glass 1737 (50 x 50 x 1.1 mm) as a transparent substrate using a spin coating method, and by photolithography Patterning was performed to obtain a blue filter line pattern having a line width of 0.1 mm, a pitch of 0.33 mm, and a film thickness of 10 μm.

[Production of green conversion filter]
Coumarin 6 (0.7 parts by weight) as a fluorescent dye was dissolved in 120 parts by weight of propylene glycol monomethyl ether acetate (PGMEA) as a solvent. Further, 100 parts by weight of a photopolymerizable resin “VPA100 / P5” (trade name, manufactured by Nippon Steel Chemical Co., Ltd.) was added and dissolved uniformly to obtain a coating solution. This coating solution is applied onto a transparent substrate on which a blue filter line pattern has been formed by using a spin coating method, and patterned by a photolithographic method, so that the line width is 0.1 mm, the pitch is 0.33 mm, and the film thickness is 10 μm. A green conversion filter line pattern was obtained.

[Production of red conversion filter]
Coumarin 6 (0.6 parts by weight), rhodamine 6G (0.3 parts by weight), and basic violet 11 (0.3 parts by weight) were dissolved in 120 parts by weight of propylene glycol monomethyl ether acetate (PGMEA) as a solvent. . Further, 100 parts by weight of a photopolymerizable resin “VPA100 / P5” (trade name, manufactured by Nippon Steel Chemical Co., Ltd.) was added and dissolved uniformly to obtain a coating solution. This coating solution is applied onto a transparent substrate on which a line pattern of a blue filter and a green conversion filter has been formed by using a spin coating method, and patterned by a photolithographic method, with a line width of 0.1 mm and a pitch of 0.33 mm. A line pattern of a red color conversion filter having a film thickness of 10 μm was obtained.

[Fabrication of planarization layer]
On the color conversion filter layer thus formed, a UV curable resin (epoxy-modified acrylate) was applied by spin coating, and a high-pressure mercury lamp was irradiated to form a planarizing layer having a thickness of 8 μm on the glass substrate. . At this time, the pattern of the color conversion filter was not deformed, and the upper surface of the planarization layer was flat.

[Preparation of passivation layer]
As the gas barrier layer, a 300 nm SiOx film was formed by RF magnetron sputtering at room temperature. Si was used as a target, and a mixed gas of Ar and oxygen was used as a sputtering gas.

[Formation of first electrode]
An In—Zn oxide pattern was formed as the first electrode. The first electrode is formed as a pattern connected from the connection part with the external drive circuit to the center in the display panel. That is, an In—Zn oxide film having a thickness of 200 nm was formed by DC magnetron sputtering at room temperature. An In—Zn oxide target was used as the sputtering target, and a mixed gas of Ar and oxygen was used as the sputtering gas. Next, after patterning the resist by photolithography, the In—Zn oxide thin film was patterned using oxalic acid as an etchant to form a line pattern having a width of 100 μm.

[Formation of insulating film]
As the insulating film, a silicon oxide film was formed by a lift-off method. For the formation of the lift-off resist, first, a resin based on PMGI (manufactured by Microchem: LOR 3A) is spin-coated on the entire surface of the substrate on which the first electrode is formed to a film thickness of 0.4 μm, and is applied to the hot plate. And dried at 100 ° C. for 5 minutes. Next, a positive type photoresist made of novolak resin (Tokyo Ohka: TFR-1150) is spin-coated to a film thickness of 1.2 μm, dried on a hot plate at 110 ° C. for 90 seconds, and then on the first electrode. Irradiate ultraviolet light with a high-pressure mercury lamp through a photomask that shields a region not forming an insulating film such as an insulating film opening and a junction with an external drive circuit, and then tetramethylammonium hydroxide (TMAH) 2. Photoresist development and PMGI resin etching were performed using a 2.38% aqueous solution, and the cross-sectional shape of FIG. 5A (resist overhang portion length 2.4 μm, substrate at the bottom of the overhang portion tip) The lift-off resist having a height of 0.60 μm was obtained.

  Thereafter, the substrate on which the lift-off resist was formed was heated at 100 ° C. for 150 seconds using a hot plate. Thereafter, a silicon oxide film having a thickness of 300 nm was formed by RF magnetron sputtering without heating the substrate. The substrate arrival temperature during film formation was 140 ° C. When the silicon oxide film was formed, as shown in FIG. 5B, the tip of the overhang portion was deformed so as to hang down, and the height of the bottom portion of the overhang portion from the substrate became 0.18 μm. Next, the lift-off resist and the silicon oxide film on the resist are removed by immersing the substrate on which the silicon oxide film is formed in a resist stripping solution (Tokyo Ohka: stripping solution 104), and an opening is formed on the first electrode. A substrate on which an insulating film was formed was obtained. The width of the portion having a thickness of 270 nm or less at the end of the insulating film was about 2.9 μm.

[Partition formation]
A partition for separating the second electrodes from each other was formed on the substrate on which the insulating film was formed, perpendicular to the lines of the first electrodes. The partition wall material is a novolac negative chemical amplification resist (manufactured by Nippon Zeon: ZPN1168), applied by spin coating, formed a 3.5 μm thick resist film, and heated at 110 ° C. for 90 seconds using a hot plate After that, ultraviolet light was irradiated with a high-pressure mercury lamp through a photomask having a stripe pattern with a line width of 20 μm and a pitch of 330 μm. Next, after heating at 110 ° C. for 60 seconds using a hot plate, development was performed using a 2.38% aqueous solution of TMAH, and heat drying was performed on the hot plate at 180 ° C. for 10 minutes to form partition walls.

[Production of organic EL element]
Next, the substrate on which the barrier ribs are formed is mounted in a resistance heating vapor deposition apparatus, and a hole injection layer, a hole transport layer, an organic light emitting layer, and an electron transport layer are sequentially formed without breaking the vacuum. The tank internal pressure was reduced to 1 × 10 ⁻⁴ Pa. As the hole injection layer, copper phthalocyanine (CuPc) was laminated to 100 nm. As the hole transport layer, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) was laminated to 20 nm. The light emitting layer was formed by laminating 30 nm of 4,4′-bis (2,2-diphenylvinyl) biphenyl (DPVBi). The electron transport layer was formed by laminating 20 nm of aluminum chelate (Alq).

  Subsequent to the film formation from the hole injection layer to the electron transport layer, the electron injection layer and the second electrode were formed by resistance heating vapor deposition without breaking the vacuum. Lithium fluoride was formed to a thickness of 1 nm for the electron injection layer, and aluminum was formed to a thickness of 200 nm for the second electrode material. The second electrode was separated into stripes arranged in parallel by the partition wall.

  FIG. 8 shows a light emission photograph after the organic EL display produced in this way and the organic EL display using the conventional photosensitive resin as an insulating film are held in a high temperature bath at 115 ° C. for 500 hours. FIG. 8A is a light emission photograph of an organic EL display according to the present invention, and FIG. 8B is a light emission photograph of an organic EL display using a conventional photosensitive resin as an insulating film. In FIG. As shown in FIG. 8B, no decrease in the light emitting region due to diffusion of moisture or the like from the insulating film was observed. That is, in FIG. 8A, the width between the pixels is relatively narrow and uniform, whereas in FIG. 8B, the width between the pixels is wide, and the width is not uniform but is wide. There is a place that is not wide. Compared to FIG. 8 (a), the widened portion in FIG. 8 (b) is a portion that should originally emit light due to diffusion of moisture or the like but cannot emit light, and moisture from the insulating film. It shows that the light emitting region is lowered due to diffusion of the same.

  According to the method of forming a thin film pattern of the present invention, the width of the tapered region at the end of the thin film to be formed is narrow, the organic EL display using this thin film pattern as an insulating film is less likely to break down, and the light emitting region. According to the present invention, it is possible to provide a display having excellent reliability in a high temperature environment and an improved driving life.

It is an expanded sectional view which shows the thin film pattern formation process by the lift-off method of this invention. It is an expansion schematic sectional drawing which shows the formation process of the insulating thin film by the manufacturing method of the organic electroluminescent display of this invention. 1 is a schematic partial perspective view and a schematic cross-sectional view of a bottom emission type organic EL display of the present invention. It is a schematic sectional drawing of the top emission type organic EL display of this invention. It is a figure which shows the cross-sectional SEM image of the lift-off resist formed on the 1st electrode, and the lift-off resist after insulating thin film formation, and an insulating thin film. It is an expanded sectional view which shows the formation process of the lift-off thin film pattern by a prior art. It is a figure which shows the shape of the insulating thin film on the 1st electrode formed by the lift-off method of the prior art. It is the light emission photograph of the organic electroluminescent display after heat-holding, (a) is the organic electroluminescent display by this invention, (b) is the organic electroluminescent display which used photosensitive resin for the insulating film material.

Explanation of symbols

1: substrate 2, 112: lift-off resist 3, 103: insulating thin film 101: first electrode substrate 102: first electrode 104: partition 105: organic EL layer 106: second electrode 107: sealing substrate 150: light

Claims (13)

Forming a resist pattern on the substrate;
Forming an insulating thin film on a substrate having a resist pattern formed on the surface;
The step of forming the insulating thin film pattern by removing the resist with a solvent and lifting off the thin film formed on the resist, and the top of the resist formed in the step of forming the pattern made of the resist on the substrate A method of forming a thin film pattern, comprising: an overhang portion protruding in a parallel direction, wherein the resist is deformed so that a tip of the overhang portion of the resist approaches a substrate in the step of forming the insulating thin film pattern . When the thickness of the central portion of the insulating thin film is t, and the height from the substrate at the bottom of the overhang portion after deformation is y ′,
t ≧ y ′ ≧ 0.5t
The method for forming a thin film pattern according to claim 1, wherein: When the length of the overhang portion of the resist formed in the step of forming the resist pattern is x, and the height from the substrate at the bottom of the overhang portion is y,
10t ≧ x ≧ 5.5t, 2t ≧ y> t
The method for forming a thin film pattern according to claim 2, wherein:   The method for forming a thin film pattern according to claim 1, wherein the resist is a single layer resist.   The method for forming a thin film pattern according to claim 1, wherein the resist is made of a laminate of two kinds of resin materials.   6. The method of forming a thin film pattern according to claim 1, wherein the formation of the insulating thin film in the step of forming the insulating thin film on the substrate having the resist pattern formed on the surface is performed by a sputtering method. .   The thin film pattern according to any one of claims 1 to 5, wherein the formation of the insulating thin film in the step of forming the insulating thin film on the substrate having the resist pattern formed on the surface is performed by an ion plating method. Forming method. A method for producing an organic EL display comprising at least a first electrode, an insulating thin film, an organic EL layer, and a second electrode sequentially laminated on a substrate,
(1) forming a first electrode on a substrate;
(2) forming an insulating thin film on the substrate on which the first electrode is formed, having an opening on the first electrode and covering at least the first electrode end;
(3) forming an organic EL layer;
(4) forming a second electrode, and forming the insulating thin film in the step (2) is the method for forming a thin film according to any one of claims 1 to 7. Manufacturing method of organic EL display.   9. The method of manufacturing an organic EL display according to claim 8, wherein the substrate is a first electrode substrate on which at least a patterned color conversion filter layer, a planarization layer, and a passivation layer are formed. .   9. The method of manufacturing an organic EL display according to claim 8, further comprising a step of forming a color conversion filter substrate including at least a color conversion filter layer after the step (4).   At least a first electrode, an insulating thin film, an organic EL layer, and a second electrode are sequentially stacked on the substrate, and the insulating thin film has an opening on the first electrode so as to cover at least the end of the first electrode. A thin film made of an inorganic material formed on the surface of the insulating film, the angle formed by the first electrode surface and the side surface of the insulating film is not less than 1 degree and less than 5 degrees, and the thickness of the central part of the insulating thin film is t. An organic EL display characterized in that the width of the portion where the film thickness in the vicinity of the opening of the thin film is 0.9 t or less is 10 t or less.   12. The organic EL display according to claim 11, wherein the substrate is a first electrode substrate on which at least a patterned color conversion filter layer, a planarization layer, and a passivation layer are formed. 12. The organic EL display according to claim 11, wherein a color conversion filter substrate including at least a transparent substrate and a color conversion filter layer is provided on the second electrode side.

Images