JP2004319119A - Display device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device and its manufacturing method, whereby the manufacturing yield can be enhanced. <P>SOLUTION: This manufacturing method for the display device provided with an organic EL element 40 holding an organic active layer 64 between a first electrode 60 and a second electrode 66 for every picture element disposed in a matrix shape, and a barrier plate 70 to separated each picture element disposed along the peripheral rim of the first electrode 60, is characterised in that a first organic material having lyophilicity is formed into a film on a wiring board 120 having the first electrode 60, a second organic material having lyophobicity is formed into a film on the first organic material, and the barrier plate 70 structured by laminating a first insulating layer 71 comprising the first organic material and the second insulating layer 72 comprising the second organic material is formed by developing the first organic material and the second organic material after simultaneously exposing them. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a display device and a method of manufacturing the same, and more particularly, to a display device including a plurality of self-luminous elements and a method of manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, an organic electroluminescence (EL) display device has attracted attention as a flat display device. Since this organic EL display device is a self-luminous element, it has a wide viewing angle, can be made thin without a backlight, has low power consumption, and has a fast response speed. ing.
[0003]
Due to these features, the organic EL display device has attracted attention as a promising candidate for a next-generation flat panel display device that can replace the liquid crystal display device. Such an organic EL display device is configured by arranging organic EL elements each having an organic active layer containing an organic compound having a light emitting function between an anode and a cathode as an array substrate in a matrix. Organic EL elements include an element configuration using a low molecular material for an organic active layer and an element configuration using a polymer material.
[0004]
In many cases, a low-molecular element is formed by a dry process such as a vacuum evaporation method, and a laminated structure is easily formed. On the other hand, polymer-based devices are often formed by a wet process such as an ink-jet method, and the ink-jet method has an advantage that the use efficiency of a light-emitting material is extremely high.
[0005]
That is, the organic active layer using a polymer material is formed by applying a liquid light emitting material for each pixel by an ink jet method and drying. In this case, each pixel is partitioned by a partition for separating (insulating) between adjacent pixels. In addition, each pixel includes a lyophilic insulating film having lyophilic property on a partition wall so that a droplet of the applied luminescent material is evenly applied to the inside of the pixel (for example, see Patent Document 1).
[0006]
In forming such a lyophilic insulating film, after forming an inorganic insulating material by a CVD method or the like, a photoresist is applied, the photoresist is patterned by a photo etching process, and the inorganic insulating material exposed from the photoresist is exposed. It is conceivable to form by removing the material and then removing the photoresist. Therefore, the number of manufacturing steps is large, and not only the manufacturing cost is increased, but also the manufacturing yield is reduced.
[0007]
In the case where the partition wall is composed of only the lyophobic film without the lyophilic film, the luminescent material does not adapt to the partition wall, and the luminescent material does not conform to the boundary between the electrode (anode) and the partition wall that are independently formed for each pixel. The film thickness may become extremely thin. In such a case, a short circuit may occur between the electrode (cathode) and the anode on which a film is formed later, and a non-lighted pixel may be generated. For this reason, there arises a problem that the production yield is reduced.
[0008]
[Patent Document 1]
JP 2002-202735 A
[0009]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to provide a display device and a method for manufacturing the same, which can improve the production yield.
[0010]
[Means for Solving the Problems]
The method for manufacturing a display device according to the first aspect of the present invention includes:
A first electrode formed in an independent island shape for each pixel arranged in a matrix, a second electrode arranged opposite to the first electrode and commonly formed for all pixels, A method for manufacturing a display device, comprising: an organic active layer held between a first electrode and a second electrode; and a partition disposed along a periphery of the first electrode to separate pixels.
Forming a first organic film made of a first organic material having lyophilicity on a substrate having the first electrode;
Forming a second organic film made of a second organic material having lyophobicity on the first organic film;
The first organic film and the second organic film are exposed in the same process through the same mask in the same process, and then developed to form a first insulating layer made of the first organic material and a second insulating layer made of the second organic material Wherein the partition walls having a structure in which are laminated are formed.
[0011]
The display device according to the second aspect of the present invention includes:
A first electrode formed on the substrate in an independent island shape for each pixel arranged in a matrix, a second electrode arranged opposite to the first electrode and commonly formed on all pixels, An organic active layer held between one electrode and the second electrode; and a partition wall arranged along the periphery of the first electrode to separate pixels.
The partition is configured to include a first insulating layer made of a lyophilic organic material, and a second insulating layer stacked on the first organic insulating layer and made of a lyophobic organic material. ,
An angle formed between an end surface of the first insulating layer along a periphery of the first electrode and a main surface of the substrate is 45 ° or less.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a display device and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a self-luminous display device, for example, an organic EL (electroluminescence) display device will be described as an example of the display device.
[0013]
As shown in FIGS. 1 and 2, the organic EL display device 1 includes an array substrate 100 having a display area 102 for displaying an image, and a sealing substrate 200 for sealing at least the display area 102 of the array substrate 100. It is configured. The display area 102 of the array substrate 100 includes a plurality of pixels PX (R, G, B) arranged in a matrix.
[0014]
Each pixel PX (R, G, B) is supplied via a pixel switch 10 and a pixel switch 10 having a function of electrically separating an ON pixel and an OFF pixel and holding a video signal to the ON pixel. A drive transistor 20 for supplying a desired drive current to the display element based on the video signal, and a storage capacitor element 30 for holding the gate-source potential of the drive transistor 20 for a predetermined period. The pixel switch 10 and the driving transistor 20 are constituted by, for example, a thin film transistor, and here, polysilicon is used for the semiconductor layer. Further, each pixel PX (R, G, B) includes an organic EL element 40 (R, G, B) as a display element. That is, the red pixel PXR includes an organic EL element 40R that emits red light, the green pixel PXG includes an organic EL element 40G that emits green light, and the blue pixel PXB includes an organic EL element 40B that emits blue light. Have.
[0015]
The various organic EL elements 40 (R, G, B) are basically the same, and the organic EL element 40 includes a first electrode 60 formed as an independent island in each pixel PX, and a first electrode 60. It is constituted by a second electrode 66 which is arranged opposite to and is formed in common to all the pixels PX, and an organic active layer 64 held between the first electrode 60 and the second electrode 66.
[0016]
The array substrate 100 includes a plurality of scanning lines Ym (m = 1, 2,...) Arranged along the row direction of the pixels PX (that is, the Y direction in FIG. 1) and a direction substantially orthogonal to the scanning lines Ym. A plurality of signal lines Xn (n = 1, 2,...) Arranged along the X direction in FIG. 1 and a power supply line for supplying power to the first electrode 60 side of the organic EL element 40 P. Further, the array substrate 100 includes, in a peripheral area 104 along the outer periphery of the display area 102, a scanning line driving circuit 107 for supplying a scanning signal to the scanning line Ym and a signal line driving circuit 108 for supplying a video signal to the signal line Xn. And
[0017]
All the scanning lines Ym are connected to the scanning line driving circuit 107. All the signal lines Xn are connected to the signal line driving circuit 108. Here, the pixel switch 10 is arranged near the intersection of the scanning line Ym and the signal line Xn. The drive transistor 20 is connected in series with the organic EL element 40. The storage capacitor 30 is connected in series with the pixel switch 10 and in parallel with the drive transistor 20. Both electrodes of the storage capacitor 30 are connected to the gate electrode and the source electrode of the drive transistor 20, respectively. I have.
[0018]
The power supply line P is connected to a first electrode power line (not shown) arranged around the display area 102. The end of the organic EL element 40 on the second electrode 66 side is connected to a second electrode power supply line (not shown) which is arranged around the display area 102 and supplies a common potential, here, a ground potential.
[0019]
More specifically, the gate electrode of the pixel switch 10 is connected to the scanning line Ym, the source electrode is connected to the signal line Xn, and the drain electrode is connected to one end of the storage capacitor 30 and the gate electrode of the driving transistor 20. I have. The source electrode of the drive transistor 20 is connected to the other end of the storage capacitor 30 and the power supply line P, and the drain electrode is connected to the first electrode 60 of the organic EL element 40.
[0020]
The pixel switch 10 writes the video signal of the corresponding signal line Xn to the storage capacitor 30 when selected via the corresponding scanning line Ym, and controls the driving of the driving transistor 20.
[0021]
The array substrate 100 and the sealing substrate 200 are sealed with a sealing material 400. The sealing material 400 is formed of, for example, an ultraviolet curable resin. A sealed space formed in a predetermined gap between the array substrate 100 and the sealing substrate 200 is filled with an inert gas such as a nitrogen gas. In addition, a desiccant is disposed inside the closed space, and is kept in a dry state that does not adversely affect the organic EL element 40.
[0022]
As shown in FIG. 2, the array substrate 100 includes an organic EL element 40 arranged on a wiring substrate 120. Note that the wiring substrate 120 is composed of a pixel switch 10, a driving transistor 20, a storage capacitor 30, a scanning line driving circuit 107, a signal line driving circuit 108, and various wirings (scanning) on an insulating support substrate such as a glass substrate or a plastic sheet. Line, signal line, power supply line, etc.).
[0023]
The first electrode 60 constituting the organic EL element 40 is disposed on the insulating film on the surface of the wiring board 120. The first electrode 60 is formed of a light transmitting conductive member such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) here, and functions as an anode.
[0024]
The organic active layer 64 includes at least an organic compound having a light-emitting function, and may be formed of a three-layer stack of a hole buffer layer, an electron buffer layer, and an organic light-emitting layer formed for each color. It may be composed of two layers or a single layer that are functionally combined. For example, the hole buffer layer is disposed between the anode and the organic light emitting layer, and is formed by a thin film of an aromatic amine derivative, a polythiophene derivative, a polyaniline derivative, or the like. The light-emitting layer is formed of an organic compound having a light-emitting function of emitting red, green, or blue light. This light-emitting layer is formed of a thin film such as PPV (polyparaphenylenevinylene), a polyfluorene derivative, or a precursor thereof when a polymer-based light-emitting material is used, for example.
[0025]
The second electrode 66 is arranged on the organic active layer 64 in common with each organic EL element 40. The second electrode 66 is formed of a metal film having an electron injection function such as Ca (calcium), Al (aluminum), Ba (barium), Ag (silver), and Yb (ytterbium), and functions as a cathode. I have. The second electrode 66 may have a two-layer structure in which a surface of a metal film functioning as a cathode is covered with a cover metal. The cover metal is formed of, for example, aluminum.
[0026]
In the organic EL element 40 configured as described above, electrons and holes are injected into the organic active layer 64 sandwiched between the first electrode 60 and the second electrode 66, and exciton is generated by recombining them. It is generated and emits light by emission of light of a predetermined wavelength generated when the exciton is deactivated. Here, the EL light is emitted from the lower surface side of the array substrate 100, that is, from the first electrode 60 side.
[0027]
By the way, the array substrate 100 includes a partition 70 for separating each pixel RX (R, G, B) in the display area 102. The barrier ribs 70 are arranged in a grid along the periphery of the first electrode 60. The partition 70 is formed of a first insulating layer 71 formed of a lyophilic organic material, and a second insulating layer formed on the first insulating layer 71 and formed of a lyophobic organic material. 72 are stacked. Both the first organic material forming the first insulating layer 72 and the second organic material forming the second insulating layer 72 have a predetermined sensitivity in a predetermined wavelength band.
[0028]
That is, the first insulating layer 71 is formed of a first organic material having an affinity for a polymer-based light emitting material for forming the organic active layer 64. For example, the first insulating layer 71 is formed of a first organic material such as an acrylic resin, a polyimide resin, and a novolak resin.
[0029]
In addition, the second insulating layer 72 is formed of a second organic material having no affinity with a polymer-based light emitting material for forming the organic active layer 64. For example, the second insulating layer 72 contains fluorine (F), silicon (Si), or the like in a main chain, and has a methyl group (CH) in a side chain. ₃ -) Formed of a second organic material containing, for example,
[0030]
The first insulating layer 71 defines a first opening AP1 that substantially contributes to display in each pixel PX. That is, the first insulating layer 71 is disposed so as to cover the periphery of the first electrode 60 formed in an independent island shape on the wiring substrate 120 with a width of about 1 to 4 μm, and electrically connects the first electrode 60 for each pixel. To separate. In addition, the first opening AP1 surrounded by the peripheral end surface 71A of the first insulating layer 71 exposes the first electrode 60, and allows the organic active layer 64 to be disposed on the first electrode 60.
[0031]
The second insulating layer 72 defines a second opening AP2 having a larger diameter than the first opening AP1 in each pixel PX. That is, the second insulating layer 72 is arranged along the peripheral end surface 71A of the first insulating layer 71 that defines the first opening AP1. Further, the second opening AP2 surrounded by the peripheral end face 72A of the second insulating layer 72 exposes the first opening AP1 and the peripheral end face 71A of the first insulating layer 71, and the organic active layer on the first electrode 60 is exposed. The arrangement of the layer 64 is enabled.
[0032]
The opening peripheral end surface of the first insulating layer 71 having lyophilic property, that is, the surface 71A that contacts the organic active layer 64, has an angle (that is, a taper angle) θ between the main surface 120A of the wiring substrate 120 of 45 ° or less. It is desirable to be formed so that it becomes. Here, the angle formed between at least the peripheral end face 71A of the first insulating layer 71 and the main surface 120A of the wiring board constituting the partition 70 is set to 45 ° or less, but the peripheral end face 72A of the second insulating layer 72 and the main surface of the wiring board are set to 45 ° or less. It is desirable that the angle formed with 120A be 45 ° or less. This makes it possible to flatten the film thickness of the organic active layer 64 disposed in the first opening AP1.
[0033]
When the film thickness of the entire partition 70 is set to about 3 μm, it is desirable that the first insulating layer 71 be formed to have a thickness of 1000 Å or more and 5000 Å or less. Further, it is desirable that the second insulating layer 72 be formed to have a thickness of not less than 25,000 angstroms and not more than 29000 angstroms. With such a film thickness configuration, the light-emitting material in a solution state can be flattened. That is, the luminescent material is stored in the partition so as to swell in a dome shape immediately after the discharge. In order for this liquid not to mix with adjacent pixels, a partition having a height of at least 1/5 of the dome-shaped liquid is required. Further, the thickness of the film after evaporating the solvent is 1000 to 3000 angstroms including the hole transport layer and the light emitting layer, so that the thickness of the light emitting layer formed immediately after discharging the first insulating layer 71 is ２. When the thickness is less than the above, the thickness of the formed light emitting layer becomes very uniform.
[0034]
Although it is difficult to form the first insulating layer 71 to have a uniform film thickness smaller than 3000 Å depending on the material and viscosity thereof, it is necessary to surely cover the periphery of the first electrode 60. If it is possible and the film thickness can be sufficiently controlled, the film thickness may be made smaller, for example, smaller than the film thickness of the first electrode 60 (for example, 500 Å).
[0035]
Even when the entire thickness of the partition 70 is set to be larger than 3 μm, the thickness of the first insulating layer 71 is set to 5000 Å or less, and the thickness of the second insulating layer 72 is set to 25000 Å or more. The thickness of the entire partition 70 is controlled by the thickness of the second insulating layer 72.
[0036]
(First structural example)
First, a first structural example of the partition 70 will be described. That is, the pixels of the organic EL element 40 are separated by the partition 70 having the structure shown in FIG. The partition 70 has a structure in which two layers of a lyophilic first insulating layer 71 and a lyophobic second insulating layer are stacked. Further, the peripheral end face 71A of the first insulating layer 71 and the peripheral end face 72A of the second insulating layer 72 are arranged so as to be flush with each other so as to form the same plane, and both have a taper angle θ with respect to the wiring board main surface 120A. It is formed so as to be 45 ° or less. That is, the upper surface of the first insulating layer 71 and the lower surface of the second insulating layer 72 are formed to have the same shape.
[0037]
In order to form the partition 70 having such a structure, for example, both the first insulating layer 71 and the second insulating layer 72 are of a positive type which becomes soluble in a developing solution when exposed, and And a photosensitive organic material having the same sensitivity to a predetermined wavelength band.
[0038]
That is, a first organic film made of a first organic material having lyophilicity is formed on the wiring substrate 120 having the first electrode 60, and then a second organic film having lyophobicity is formed on the first organic film. A second organic film made of a material is formed. Then, the first organic film and the second organic film are simultaneously exposed through a photomask using a light source in a predetermined wavelength band, and are simultaneously developed. By adjusting the lamp output at the time of exposure, the amount of exposure can be controlled around the exposure region, and a tapered shape can be formed on the side surface of the opening of the partition. As a result, a partition wall 70 having a structure in which the first insulating layer 71 made of the first organic material and the second insulating layer 72 made of the second organic material are stacked is formed.
[0039]
According to the organic EL display device 1 including the partition wall 70 of the first structure example, the taper angle of the first insulating layer 71 and the second insulating layer 72 is set to 45 ° or less, and the periphery of the first electrode 60 is reduced. Is formed of a lyophilic first organic material. Therefore, even when the organic active layer 64 is formed by an inkjet method using a polymer-based light emitting material, the thickness of the organic active layer 64 in the first opening AP1 can be made substantially uniform. Thereby, a short circuit between the first electrode 60 and the second electrode 66 can be prevented, and the manufacturing yield can be improved.
[0040]
Further, by forming both the first insulating layer 71 and the second insulating layer 72 from a photosensitive organic material having the same sensitivity to a predetermined wavelength band, the first organic film and the second organic film forming these are formed. Are simultaneously exposed and developed at the same time, thereby forming the partition 70 having a two-layer laminated structure. For this reason, the number of manufacturing steps can be significantly reduced as compared with the case where the partition is formed using the inorganic insulating layer. Thereby, the manufacturing cost can be reduced, and the manufacturing yield can be improved.
[0041]
Further, even when the organic active layer 64 is dried and adhered to the side wall of the partition, the side of the opening of the partition is formed in a tapered shape. The thickness of the organic active layer in the region can be made substantially uniform, and the display quality can be improved.
[0042]
(Second structural example)
Next, a second structural example of the partition 70 will be described. That is, the organic EL element 40 is separated into pixels by the partition 70 having a structure as shown in FIG. The partition 70 has a structure in which two layers of a lyophilic first insulating layer 71 and a lyophobic second insulating layer are stacked. Further, the peripheral end face 72A of the second insulating layer 72 is disposed so as to be recessed from the peripheral end face 71A of the first insulating layer 71. Here, the peripheral end surface 72A of the second insulating layer 72 is recessed, for example, by a width of 1 to 1.5 μm from the peripheral end surface 71A of the first insulating layer 71. Thus, a step is formed by the first insulating layer 71 and the second insulating layer 72.
[0043]
Further, in such a second structure example, the peripheral end surface 71A of the first insulating layer 71 is formed such that the taper angle θ1 with the main surface 120A of the wiring board is 45 ° or less. The peripheral end surface 72A of the layer 71 does not necessarily need to have a taper angle θ2 of 45 ° or less.
[0044]
In order to form the partition 70 having such a structure, for example, the first insulating layer 71 and the second insulating layer 72 are both formed of a positive-type photosensitive organic material, and the second insulating layer 72 is It is formed of a second organic material having a higher sensitivity than the first organic material forming the first insulating layer 71 in a predetermined wavelength band, for example, a sensitivity higher by 20% or more. That is, by providing a sensitivity difference of 20% or more between the first organic material and the second organic material, the second insulating layer 72 can be receded from the first insulating layer 71 by 1 μm or more.
[0045]
That is, a first organic film made of a first organic material having lyophilicity is formed on the wiring substrate 120 having the first electrode 60, and then a second organic film having lyophobicity is formed on the first organic film. A second organic film made of a material is formed. Then, the first organic film and the second organic film are simultaneously exposed through a photomask using a light source in a predetermined wavelength band. At this time, since the second organic material has higher sensitivity than the first organic material, the second organic material is exposed over a wider area than the pattern of the photomask. Thereafter, the first organic film and the second organic film are simultaneously developed. As a result, a partition wall 70 having a structure in which the first insulating layer 71 made of the first organic material and the second insulating layer 72 made of the second organic material are stacked is formed.
[0046]
According to the organic EL display device 1 having the partition wall 70 of the second structure example, the second insulating layer 72 is formed of a photosensitive organic material having higher sensitivity than the first insulating layer 71 in a predetermined wavelength band. I do. For this reason, the first organic film and the second organic film forming these are simultaneously exposed and developed simultaneously using the same mask, so that the second insulating layer 72 is receded from the periphery of the first insulating layer 71 and laminated. It is possible to form the partition 70 having the above structure. For this reason, the number of manufacturing steps can be significantly reduced as compared with the case where the partition is formed using the inorganic insulating layer. Thereby, the manufacturing cost can be reduced, and the manufacturing yield can be improved.
[0047]
Further, at least the taper angle of the first insulating layer 71 is set to 45 ° or less, and the first insulating layer 71 disposed on the periphery of the first electrode 60 is formed of a lyophilic first organic material. Therefore, in the case where the organic active layer 64 is formed by an inkjet method using a polymer-based light emitting material, the taper angle of the peripheral end surface 72A of the second insulating layer 72 does not necessarily need to be controlled to 45 ° or less. The thickness of the organic active layer 64 in the first opening AP1 can be made substantially uniform. Further, even when the first insulating layer 71 and the second insulating layer 72 are heated in a later heating step, the upper second insulating layer 72 is softened and covers the peripheral end surface 71A of the first insulating layer 71. Can be prevented. Thereby, the first insulating layer 71 having a lyophilic property is reliably arranged along the periphery of the first electrode 60, and a short circuit between the first electrode 60 and the second electrode 66 can be prevented. The yield can be improved.
[0048]
(Third structural example)
Next, a third structural example of the partition 70 will be described. That is, the pixels of the organic EL element 40 are separated by the partition 70 having the structure as shown in FIG. The partition 70 is formed by laminating three or more insulating layers, has a first insulating layer 71 made of a lyophilic organic material in the lowermost layer (on the side of the wiring board 120), and has an uppermost layer (sealed). It has a multilayer structure having a second insulating layer 72 made of a lyophobic organic material on the stop substrate 200 side).
[0049]
According to the organic EL display device 1 including the barrier ribs 70 of the third structural example, the same effects as those of the above-described first and second structural examples can be obtained, and the thickness of the barrier ribs can be easily increased. Becomes possible.
[0050]
Note that it is also possible to combine the third structural example with the second structural example.
[0051]
(Production method)
Next, a method for manufacturing the organic EL display device will be described. Here, a description will be given of a manufacturing method for forming an organic EL element having a partition of the second structure example.
[0052]
First, a wiring substrate 120 having the first electrode 60 is prepared. That is, processes such as formation and patterning of a metal film and an insulating film are repeated, and a pixel switch 10, a driving transistor 20, a storage capacitor 30, a scanning line driving circuit 107, a signal line driving circuit 108, and the like are formed on an insulating substrate. A wiring substrate 120 having a total of 920,000 pixels of 480 pixels vertically and 640 × 3 pixels (R, G, B), on which various wirings such as signal lines Xn, scanning lines Ym, and power supply lines P are also formed. Form. Then, a first electrode 60 made of ITO and having a thickness of 500 angstroms is formed on each pixel. The first electrode 60 may be generally formed by a photolithography process or may be formed by a mask sputtering method.
[0053]
Subsequently, as shown in FIG. 5A, a first organic film 81 having lyophilicity is formed on such a wiring board 120. That is, a positive type acrylic photosensitive resin is applied as a first organic material for forming the first organic film 81 by a spinner or the like so as to have a thickness of 5000 Å. Then, the first organic material 81 is dried at a high temperature of about 90 ° C. for 120 seconds.
[0054]
Subsequently, as shown in FIG. 5B, a second organic film 82 having lyophobicity is formed on the first organic material 81. That is, the second organic material forming the second organic film 82 has silicon (Si) in the main chain and a methyl group (CH ₃ A liquid-phobic, positive-type photosensitive resin mainly containing-) is applied by a spinner or the like so as to have a thickness of 25,000 angstroms. Then, the second organic material 82 is dried at a high temperature of 90 ° C. for 120 seconds.
[0055]
Subsequently, as shown in FIG. 5C, the first organic film 81 and the second organic film 82 are simultaneously exposed. That is, using a powerful lamp having an output of 75 mW having an ultraviolet wavelength band (approximately 365 nm) as a light source for exposure, for example, through a photomask PM that irradiates light to a portion corresponding to a pixel, and outputs 250 mJ of light. The first organic film 81 and the second organic film 82 are collectively exposed with the irradiation energy. As described above, if it is possible to use a light source with a large output, it is desirable that the exposure process be performed by collective exposure that can reduce the exposure time. However, the wiring substrate 120 is divided into a plurality of regions and sequentially exposed. It may be performed by divided exposure. .
[0056]
Subsequently, as shown in FIG. 6A, the first organic film 81 and the second organic film 82 are simultaneously developed. That is, the first organic material 81 and the second organic material 82 are developed using a 2.38% TMAH (tetramethyl ammonium hydroxide) solution. Then, a bake treatment is performed at a high temperature of 220 ° C. for 30 minutes. As a result, a partition 70 having a structure in which the first insulating layer 71 made of the first organic material and the second insulating layer 72 made of the second organic material are stacked is formed.
[0057]
At this time, by selecting a material in which the second organic material 82 is set to have a sensitivity about 20% higher than that of the first organic material 81 in the ultraviolet wavelength band, the second organic material 82 can be exposed even with the same irradiation energy. 82 is exposed to a wider range than the first organic material 81 and becomes soluble in a developing solution. For this reason, the second organic material 82 remaining after the development is receded from the first organic material 81 by a width W of 1 μm or more. As a result, a step is formed between the first organic material 81 and the second organic material 82.
[0058]
Further, since the periphery of the mask pattern to be exposed is also exposed with weak irradiation energy, the peripheral end surfaces of the first organic material 81 and the second organic material 82 remaining after the development are likely to have a taper angle. The taper angle can be controlled by adjusting the selection of the organic material, the setting of the irradiation energy, the setting of the developing speed, and the like.
[0059]
Subsequently, as shown in FIG. 6B, an organic active layer 64 including a hole buffer layer and the like in addition to the organic light emitting layer is applied to each pixel. That is, a 2.0% by weight solution of a high molecular weight light emitting polymer material forming a hole buffer layer, an organic light emitting layer, and the like is sprayed toward the inside of the pixel partitioned by the partition wall 70, and is applied on the first electrode 60. . The application of this solution is performed using a piezo type inkjet nozzle at a supply amount of the light emitting polymer material of 0.05 ml / min.
[0060]
The solution of the light-emitting polymer material applied in this manner is prevented from spreading in the pixel by the lyophilic first insulating layer 71 exposed below the partition 70 disposed around each pixel. No, spreads evenly.
[0061]
Then, the solvent contained in the solution is removed by performing a drying process at a high temperature of 100 ° C. for 15 seconds. The organic active layer 64 of each pixel thus formed is formed to have a uniform film thickness after the removal of the solvent, and here has a film thickness of about 1500 angstroms. Therefore, the second electrode 66 and the first electrode 60, which are formed later, are reliably electrically insulated from each other, and the occurrence of a short circuit can be prevented.
[0062]
Subsequently, as shown in FIG. 6C, a second electrode 66 is formed on the organic active layer 64. That is, barium (Ba) is used as a metal film functioning as a cathode. ^-7 At a degree of vacuum of Pa, evaporation is performed to a thickness of 600 Å, and subsequently, aluminum (Al) is evaporated as a metal film functioning as a cover metal to a thickness of 1500 to 3000 Å. Thereby, the organic EL element 40 is formed.
[0063]
Subsequently, in order to seal the display area 102 on the array substrate 100, an ultraviolet-curable sealing material 400 is applied along the outer periphery of the sealing substrate 200, and the sealing material 400 is placed in an inert gas atmosphere such as nitrogen gas or argon gas. In, the array substrate 100 and the sealing substrate 200 are attached to each other. As a result, the organic EL element 40 is sealed in a sealed space in an inert gas atmosphere. After that, the sealing material 300 is cured by irradiating ultraviolet rays.
[0064]
In the bottom emission type color display type active matrix organic EL display device formed in this way, good display was obtained without display defects caused by abnormal film thickness of the organic active layer 64. Further, since the inkjet method is used for forming the organic active layer 64, the use efficiency of the light emitting polymer material is as high as about 80%, and all of the light emitting polymer material except for those remaining in the supply system is effectively used for film formation. I knew it was done.
[0065]
Here, a structure in which the opening side surface of the partition wall 70 is tapered so as to form an acute angle with respect to the substrate surface as in the above embodiment, and a structure in which the opening side surface is parallel to the normal direction of the substrate surface The film formation state of the organic active layer 64 of the organic EL element 40 will be compared. FIG. 7A shows, as an example, the film thickness distribution of the organic active layer of the first structural example. This film thickness distribution is defined by the peripheral end face 71A of the first insulating layer 71 for one pixel. It is the result of measuring the film thickness of the organic active layer 64 disposed in the first opening and on the periphery thereof. Here, the position of “0” corresponds to the boundary between the first insulating layer 71 and the organic active layer 64 disposed on the first electrode 60, and the position having a positive intra-pixel distance is the position in the first opening. , And a position having a negative intra-pixel distance corresponds to a position on the partition wall 70 (first insulating layer 71). This film thickness distribution can be obtained by photographing a cross-sectional image of each layer from a partition edge inside a pixel at intervals of 10 to 15 μm by FIB processing SEM photograph and measuring the film thickness.
[0066]
Here, the first insulating layer 71 was formed to have a thickness of about 5000 Å, and the taper angle θ1 of the peripheral end face 71A was formed to be about 40 °. The second insulating layer 72 was formed so as to have a thickness of about 25000 angstroms, and the taper angle θ2 of the peripheral end face 72A was formed at about 40 °. The peripheral end surface 72A of the second insulating layer 72 is flush with the peripheral end surface 71A of the first insulating layer, that is, the opening diameter of the upper surface of the first insulating layer and the opening diameter of the lower surface of the second insulating layer. Are formed to be the same. Further, the organic active layer 64 was formed to have a thickness of about 1500 angstroms.
[0067]
As shown in FIG. 7A, according to the organic EL element 40 described above, it was confirmed that the organic active layer 64 disposed in the first opening AP1 was formed to have a substantially uniform film thickness. .
[0068]
On the other hand, in the comparative example, the first insulating layer 71 was formed so as to have a film thickness of about 5000 angstroms, and the taper angle θ1 of the peripheral end face 71A was formed at about 90 °. The second insulating layer 72 was formed so as to have a thickness of about 25,000 angstroms, and the taper angle θ2 of the peripheral end face 72A was formed at about 90 °. Further, the peripheral end face 72A of the second insulating layer 72 was formed so as to be flush with the peripheral end face 71A of the first insulating layer. The organic active layer 64 was formed to have a thickness of about 1500 angstroms in the same manner as described above.
[0069]
As shown in FIG. 7B, according to the organic EL element of the comparative example, although the film thickness becomes almost uniform near the center of the first opening, the center becomes closer toward the periphery of the first opening. It was confirmed that the film thickness was larger than that of the portion and the surface was not sufficiently flattened.
[0070]
In this manner, by providing the partition walls with a taper, an organic active layer having a substantially uniform thickness can be formed in the region substantially contributing to light emission and in the first opening.
[0071]
As described above, according to the display device and the method of manufacturing the same according to this embodiment, the organic active layer of the organic EL element can be selectively formed by the inkjet method by applying the polymer-based light emitting polymer material. A method of forming a film can be adopted. This film forming method has the advantages that the number of steps is small and the use efficiency of the light emitting polymer material is remarkably good.
[0072]
Further, a partition wall for separating each pixel has a laminated structure composed of a plurality of layers, a lyophilic organic insulating layer is disposed so as to cover the periphery of the first electrode in the lowest layer, and a lyophobic organic insulating layer is formed in the uppermost layer. A structure in which an insulating layer is provided. Since such a lyophilic organic insulating layer is well compatible with a polymer-based light-emitting polymer material, it is necessary to make the thickness of the organic active layer in a pixel uniform even without a lyophilic film made of an inorganic insulating film. Can be.
[0073]
Further, the plurality of organic insulating layers constituting the partition are not formed individually but are formed using an organic material having photosensitivity of the same property at the same wavelength. Thereby, after forming each organic material, it is possible to form a partition having a desired laminated structure by simultaneously exposing through a single type of photomask and then developing. Therefore, no misalignment occurs between the layers, and the number of manufacturing steps can be reduced.
[0074]
In addition, by setting at least the completed taper angle of the lyophilic organic insulating layer to 45 ° or less, it is possible to suppress the nonuniformity of the film thickness generated when the injected light emitting polymer material is dried.
[0075]
It should be noted that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention at the stage of implementation. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Further, components of different embodiments may be appropriately combined.
[0076]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a display device and a method for manufacturing the same, which can improve the manufacturing yield.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a configuration of an organic EL display device according to one embodiment of the present invention.
FIG. 2 is a cross-sectional view schematically showing a first structural example for one pixel of the organic EL display device shown in FIG.
FIG. 3 is a sectional view schematically showing a second structure example for one pixel of the organic EL display device shown in FIG. 1;
FIG. 4 is a sectional view schematically showing a third structural example for one pixel of the organic EL display device shown in FIG. 1;
FIGS. 5A to 5C are diagrams for explaining a manufacturing process for forming an organic EL element partitioned by a partition on a wiring board.
FIGS. 6A to 6C are views for explaining a manufacturing process for forming an organic EL element partitioned by a partition on a wiring board.
FIGS. 7A and 7B are diagrams showing a film thickness distribution of an organic active layer disposed in a first opening and at a periphery thereof. FIGS.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Organic EL display device, 10 ... Pixel switch, 20 ... Driving transistor, 30 ... Storage capacitance element, 40 ... Organic EL element, 60 ... 1st electrode, 64 ... Organic active layer, 66 ... 2nd electrode, 70 ... Partition , 71: first insulating layer, 72: second insulating layer, 100: array substrate, 200: sealing substrate, 400: sealing material, PX: pixel,

Claims (8)

A first electrode formed in an independent island shape for each pixel arranged in a matrix, a second electrode arranged opposite to the first electrode and commonly formed for all pixels, A method for manufacturing a display device, comprising: an organic active layer held between a second electrode; and a partition disposed along a periphery of the first electrode and separating each pixel.
Forming a first organic film made of a first organic material having lyophilicity on a substrate having the first electrode;
Forming a second organic film made of a second organic material having lyophobicity on the first organic film;
The first organic film and the second organic film are exposed in the same process through the same mask in the same process, and then developed to form a first insulating layer made of the first organic material and a second insulating layer made of the second organic material A method of manufacturing a display device, comprising forming the partition wall having a structure in which are laminated. 2. The display device according to claim 1, wherein an angle formed between an end surface of the first insulating layer along a periphery of the first electrode and a main surface of the substrate is 45 ° or less. 3. Production method. The method according to claim 1, wherein the first insulating layer has a thickness of 1000 Å or more and 5000 Å or less. 2. The method according to claim 1, wherein the second insulating layer has a thickness of 25,000 Å or more and 29000 Å or less. 3. The method according to claim 1, wherein both the first organic material and the second organic material have sensitivity in a predetermined wavelength band. The first insulating layer and the second insulating layer are formed of a positive type photosensitive organic material that becomes soluble in a developing solution when exposed to light, and the second insulating layer has a predetermined wavelength band. The method according to claim 5, wherein the first insulating layer is formed of an organic material having a sensitivity higher than that of the first insulating layer by 20% or more. A first electrode formed on the substrate in an independent island shape for each pixel arranged in a matrix, a second electrode arranged opposite to the first electrode and commonly formed on all pixels, An organic active layer held between one electrode and the second electrode; and a partition wall arranged along the periphery of the first electrode to separate pixels.
The partition is configured to include a first insulating layer made of a lyophilic organic material, and a second insulating layer stacked on the first organic insulating layer and made of a lyophobic organic material. ,
A display device, wherein an angle formed between an end surface of the first insulating layer along a periphery of the first electrode and a main surface of the substrate is 45 ° or less. 8. The device according to claim 7, wherein the first insulating layer has a first opening exposing the first electrode, and the second insulating layer has a second opening larger than the first opening. A display device according to claim 1.

Images