JP3744766B2 - ORGANIC LIGHT-EMITTING ELEMENT, ITS MANUFACTURING METHOD, DISPLAY DEVICE AND ITS MANUFACTURING METHOD - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic light-emitting element such as an organic electroluminescence element having a light-emitting layer made of an organic material, a manufacturing method thereof, a display device using such an organic light-emitting element, and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, with the diversification of information equipment, there is an increasing demand for flat display elements that consume less power and have a smaller capacity than commonly used CRTs (cathode ray tubes). As one of such flat display elements, an electroluminescence element (hereinafter referred to as an EL element) has attracted attention. Such EL elements are roughly classified into inorganic EL elements having a light emitting layer made of an inorganic material and organic EL elements having a light emitting layer made of an organic material.
[0003]
An inorganic EL element generally emits light by exciting a light emission center by applying a high electric field to a light emitting portion and accelerating the electric field in the high electric field to collide with the light emission center. In contrast, the organic EL element injects electrons and holes from the electron injection electrode and the hole injection electrode, respectively, into the light emitting part, recombines these electrons and holes at the light emission center, and makes the organic molecule excited. This organic molecule generates fluorescence when it returns from the excited state to the ground state. Such an organic EL element has a structure in which a plurality of light emitting portions are arranged in a matrix on a substrate.
[0004]
An inorganic EL element requires a high electric field, and therefore requires a high voltage of 100 V to 200 V as a driving voltage, whereas an organic EL element has an advantage that it can be driven at a low voltage of about 5 V to 20 V.
[0005]
Further, in an organic EL element, a light emitting portion that emits light in an appropriate color can be obtained by selecting a fluorescent material that is a light emitting material, and is expected to be used as a multi-color or full-color display device. Furthermore, since the organic EL element can emit light at a low voltage, it can be used as a backlight for a display device such as a liquid crystal display device.
[0006]
FIG. 16 is a schematic view showing a method for manufacturing an organic EL element. When manufacturing an organic EL element, first, as shown in FIG. 16A, a transparent electrode 51 is formed on a glass substrate 50. Subsequently, as illustrated in FIG. 16B, a multilayer organic thin film layer 52 including a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer is formed on the transparent electrode 51. Further, an electrode layer 53 is formed on the multilayer organic thin film layer 52. In this manner, an organic EL element having a structure in which the multilayer organic thin film layer 52 and the electrode layer 53 are laminated on the transparent electrode 51 is produced.
[0007]
As shown in FIG. 16C, light is extracted from the back surface of the glass substrate 50 by applying a voltage to the organic EL element through the driving circuit 54.
[0008]
In practice, a plurality of transparent electrodes 51 are arranged on the glass substrate 50 at a predetermined interval, and a multilayer organic thin film layer 52 and an electrode layer 53 are sequentially formed on each transparent electrode 51. Thereby, a plurality of organic EL elements are formed on the glass substrate 50. Each element is separated by an element isolation insulating layer made of a resist material. The separation between the elements affects the reliability of the organic EL element. When the separation between the light emitting elements is insufficient, the reliability of the organic EL element is reduced.
[0009]
In order to use such an organic EL element as a display device, it is essential to extend the life of the organic EL element.
[0010]
In the organic EL element, when moisture enters, the moisture is absorbed into the multilayer organic thin film layer 52. Thereby, the deterioration of the light emitting part is caused and the life of the organic EL element is shortened. Therefore, after continuously forming a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and an electrode layer 53 on the transparent electrode 51, a sealing member in which these layers are filled with a desiccant By sealing with, the moisture is prevented from entering the multilayer organic thin film layer 52 from the outside air.
[0011]
On the other hand, when such an organic EL element is specifically used as a full-color flat display device, the element driving method is very important together with the above-described element separation technique.
[0012]
17A and 17B are cross-sectional views showing an example of an active matrix display device using an organic EL element developed for full-color display. As shown in FIGS. 17A and 17B, in an active matrix display device, a plurality of thin film transistors (TFTs) 70 are first formed on a glass substrate 50, and driving circuits for individual pixels are formed on the same substrate. It is made to accumulate in.
[0013]
When manufacturing the thin film transistor 70 for driving the active matrix, the active layer 61 is formed on a predetermined region of the glass substrate 50, and the gate insulating film 62 covering the active layer 61 is formed. Further, a gate electrode 63 is formed on the gate insulating film 62, and an insulating film 64 covering the gate electrode 63 is formed. Subsequently, the insulating film 64 and the gate insulating film 62 on both sides of the gate electrode 63 are removed, and a source electrode 65 and a drain electrode 66 are formed. Further, a protective film 67 is formed so as to cover the insulating film 64, the source electrode 65 and the drain electrode 66.
[0014]
After producing the plurality of thin film transistors 70 as described above, the transparent electrode 51 is formed in a region between the thin film transistors 70 on the glass substrate 50. Further, a contact wiring 68 connecting the transparent electrode 51 and the drain electrode 66 is formed. Subsequently, a multilayer organic thin film layer 52 including a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer, and an electrode layer 53 are continuously formed on the transparent electrode 51. As described above, the organic EL element 40 is formed corresponding to the plurality of thin film transistors 70, and a thin film transistor driving pixel is manufactured.
[0015]
In an active matrix type display device in which an organic EL element driven by a thin film transistor 70 is fabricated on a glass substrate 50 having a limited surface area as described above, high definition and high brightness are achieved for practical use. It is necessary to plan.
[0016]
[Problems to be solved by the invention]
As described above, in the organic EL element, sealing is performed with a sealing member filled with a desiccant in order to prevent moisture from entering the multilayer organic thin film layer 52 from the outside air. However, when such sealing is performed, heat is generated from the light-emitting layer as the light-emitting layer emits light, and thus the temperature of the light-emitting layer rises due to energization for a long time. As a result, the light emitting layer is deteriorated, and the light emission intensity is rapidly reduced. Therefore, the lifetime of the organic EL element cannot be extended.
[0017]
On the other hand, in order to improve luminance in the above active matrix display device, it is preferable to increase the area of the transparent electrode 51 as much as possible as shown in FIG. In the display device shown in FIG. 17A, a transparent electrode 51 having a large area is formed in the drain side region of the thin film transistor 70. In this case, since the area of the transparent electrode 51 is large, the multilayer organic thin film layer 52 having a uniform area and a large area can be formed. Thereby, since the light emission area of the organic EL element 40 becomes large, the brightness of the display device can be increased.
[0018]
However, in this case, the formation region of the thin film transistor 70 is reduced, and the contact wiring 68 connecting the drain electrode 66 and the transparent electrode 51 is lengthened. For this reason, it is difficult to achieve high integration of the thin film transistor 70. Therefore, it is difficult to achieve high integration of pixels, and a high-definition image cannot be obtained.
[0019]
On the other hand, in order to obtain a high-definition image in an active matrix display device, as shown in FIG. 17B, the area of the transparent electrode 51 is reduced and the thin film transistor 70 is highly integrated. Is preferred. In the display device illustrated in FIG. 17B, the formation region of the thin film transistor 70 is larger than that in the display device illustrated in FIG. Thereby, high integration of the thin film transistor 70 is achieved. Therefore, high integration of pixels is achieved and a high-definition image is realized.
[0020]
However, in this case, since the area of the transparent electrode 51 cannot be secured sufficiently, the area of the multilayer organic thin film layer 52 is also reduced. Thereby, the light emission area of the organic EL element 40 becomes small. Moreover, since the area of the transparent electrode 51 is small, it becomes difficult to form the multilayer organic thin film layer 52 on the transparent electrode 51 with a uniform film thickness. In the organic EL element 40 having variations in the film thickness of the multilayer organic thin film layer 52 as described above, uneven emission occurs. In particular, since the region of the multilayer organic thin film layer 52 in contact with the protective film 67 has a large film thickness, light emission does not occur in this portion. From the above, the luminance is reduced in the display device.
[0021]
An object of the present invention is to provide a long-life organic light-emitting device in which a sudden decrease in emission intensity due to heat generation is prevented, and a method for manufacturing the same.
[0022]
Another object of the present invention is to provide an active matrix display device and a method for manufacturing the same that can simultaneously achieve improvement in luminance and high definition.
[0023]
[Means for Solving the Problems and Effects of the Invention]
In the organic light-emitting device according to the first invention, a plurality of first electrode layers are arranged at predetermined intervals on a substrate, and an organic material layer and a second electrode layer are sequentially stacked on the plurality of first electrode layers. The organic light-emitting device has an inorganic insulating layer formed between a plurality of first electrode layers on a substrate.
[0024]
Note that the plurality of first electrode layers may be formed directly on the substrate, or may be formed on the substrate via another element such as a thin film transistor and a planarization film.
[0025]
In the organic light emitting device according to the present invention, the inorganic insulating layer formed between the plurality of first electrode layers on the substrate has better thermal conductivity than the organic material. Therefore, the heat generated in the organic material layer is dissipated to the substrate through the first electrode layer and the inorganic insulating layer, and is further released to the outside from the substrate. Thereby, the temperature rise of the organic material layer is suppressed, and crystallization of the organic material layer is prevented. As a result, the light emission intensity does not drop sharply due to energization for a long time, and the life is extended.
[0026]
The inorganic insulating layer may be made of ceramics. Since ceramics has high insulation and high thermal conductivity, the heat dissipation characteristics can be improved while ensuring sufficient insulation characteristics.
[0027]
The ceramic may be made of a nitride material or an oxide material. Since the nitride material or the oxide material has higher insulation and thermal conductivity, higher insulation characteristics and heat dissipation characteristics can be obtained.
[0028]
The ceramic is preferably made of one or more materials selected from aluminum nitride, silicon nitride, titanium nitride, aluminum oxide and silicon oxide. Since these materials have particularly high insulation and thermal conductivity, higher insulation characteristics and heat dissipation characteristics can be obtained. Thereby, the lifetime can be further extended.
[0029]
A plurality of element regions are provided at predetermined intervals on each first electrode layer, the organic material layer is formed on the plurality of element regions on each first electrode layer, and the inorganic insulating layer is a plurality of first electrodes. You may extend between several element area | regions on each 1st electrode layer from an interlayer.
[0030]
In this case, the element regions on the first electrode layer are separated by the inorganic insulating layer. Heat generated in the organic material layer in each element region on each first electrode layer is dissipated to the substrate through the inorganic insulating layer between the element regions and the first electrode layer, and is further released to the outside from the substrate. Thereby, the heat dissipation of the organic material layer is further improved, and the crystallization of the organic material layer is sufficiently prevented.
[0031]
A method for manufacturing an organic light-emitting element according to a second invention is a method for manufacturing an organic light-emitting element in which a plurality of first electrode layers, an organic material layer, and a second electrode layer are sequentially stacked on a substrate. A plurality of first electrode layers are formed on the substrate at predetermined intervals, and an inorganic insulating layer is formed between the plurality of first electrode layers on the substrate.
[0032]
In the organic light emitting device manufactured by the manufacturing method according to the present invention, the inorganic insulating layer formed between the plurality of first electrode layers on the substrate has better thermal conductivity than the organic material. Therefore, the heat generated in the organic material layer is dissipated to the substrate through the first electrode layer and the inorganic insulating layer, and is further released to the outside from the substrate. Thereby, the temperature rise of the organic material layer is suppressed, and crystallization of the organic material layer is prevented. As a result, the light emission intensity does not drop sharply due to energization for a long time, and the life is extended.
[0033]
The inorganic insulating layer may be formed by a sputtering method. In this case, since the inorganic insulating layer can be formed at a relatively low temperature, the insulating layer can be patterned using a resist pattern that is deformed at a high temperature.
[0034]
A display device according to a third invention is a display device comprising a plurality of organic light emitting elements and a plurality of transistors for selectively driving the plurality of organic light emitting elements on the substrate, wherein the plurality of transistors are the substrate. A planarization film is formed on the plurality of transistors, and a plurality of organic light emitting elements are formed on the planarization film corresponding to the plurality of transistors.
[0035]
The display device according to the present invention is an active matrix display device in which a plurality of organic light emitting elements and a plurality of transistors are formed on a substrate. In this display device, the organic light emitting elements are respectively formed on the corresponding transistors via a planarizing film.
[0036]
In the display device described above, since the organic light emitting element is formed on the planarizing film, the organic light emitting element forming region can be widened, and the area of the organic light emitting element can be increased. For this reason, it becomes possible to ensure a sufficient light emitting area. Further, in this case, since the layers constituting the organic light emitting element are formed with a uniform film thickness, the occurrence of uneven light emission can be prevented. From the above, it is possible to improve the luminance in the display device.
[0037]
In the above display device, since the organic light emitting element is formed on the planarization film, a sufficient transistor formation region can be secured on the substrate. Therefore, high integration of transistors can be achieved. Thereby, in the above display device, a high-definition image can be obtained.
[0038]
From the above, in the display device according to the present invention, high luminance and high definition can be achieved at the same time.
[0039]
Each organic light emitting element is formed by sequentially laminating a first electrode layer, an organic material layer, and a second electrode layer on a planarizing film, and the planarizing film has an opening on the drain electrode of each transistor. The first electrode layer of each organic light emitting element may be electrically connected to the drain electrode of the corresponding transistor through the opening.
[0040]
In this case, a wiring for connecting the drain electrode of the transistor and the first electrode layer of the organic light emitting element corresponding to the transistor becomes unnecessary. Therefore, it is possible to make a wide area for forming the organic light emitting element on the planarizing film, and it is possible to make a wide area for forming the transistor on the substrate.
[0041]
The first electrode layer may be made of a light transmissive material, the planarizing film may be made of a light transmissive material, and the substrate may be made of a light transmissive material. In such a display device having the first electrode layer, the planarization film, and the substrate, the light generated in the organic material layer of the organic light-emitting element is transmitted to the other of the substrate through the first electrode layer, the planarization film, and the substrate. It can be taken out from the surface side.
[0042]
The second electrode layer may be made of a light transmissive material. In a display device having such a second electrode layer, light generated in the organic material layer of the organic light emitting element can be extracted from the opposite side of the substrate through the second electrode layer.
[0043]
Furthermore, an inorganic insulating layer may be formed between the first electrode layers on the planarization film. In this case, since the inorganic insulating layer has better thermal conductivity than the organic material, the heat generated in the organic material layer is dissipated to the substrate through the first electrode layer and the inorganic insulating layer, and further from the substrate to the outside To be released. Thereby, the temperature rise of the organic material layer is suppressed, and crystallization of the organic material layer is prevented. As a result, in the organic light-emitting element, the light emission intensity does not rapidly decrease due to energization for a long time, and the life is extended. Thereby, a display device with high reliability can be realized.
[0044]
A display device manufacturing method according to a fourth aspect of the present invention is a method for manufacturing a display device including a plurality of organic light emitting elements and a plurality of transistors for selectively driving the plurality of organic light emitting elements on a substrate. A step of forming a plurality of transistors on the substrate, a step of forming a planarization film on the plurality of transistors, and a step of forming a plurality of organic light emitting elements on the planarization film corresponding to each of the plurality of transistors. Is provided.
[0045]
The method for manufacturing a display device according to the present invention is a method for manufacturing an active matrix display device. In this display device manufacturing method, a planarization film is formed over a transistor, and an organic light emitting element is formed over the planarization film. Thereby, it becomes possible to take a wide area for forming the organic light emitting element on the planarizing film. For this reason, it becomes possible to ensure a sufficient light emitting area. In this case, the layers constituting the organic light emitting element can be formed with a uniform film thickness. For this reason, generation | occurrence | production of light emission nonuniformity can be prevented. From the above, according to the method for manufacturing a display device described above, it is possible to manufacture a display device with high brightness.
[0046]
In the display device manufacturing method described above, since the organic light emitting element is formed on the planarization film, a sufficient transistor formation region can be secured on the substrate. Therefore, high integration of transistors can be achieved. Thus, according to the method for manufacturing a display device described above, a display device with high definition can be manufactured.
[0047]
From the above, according to the method for manufacturing a display device according to the present invention, it is possible to manufacture a display device in which high luminance and high definition are simultaneously achieved.
[0048]
The step of forming the organic light emitting element includes a step of forming an opening on the planarizing film on the drain electrode of each transistor and a step of forming a first electrode layer extending from the drain electrode in the opening to the planarizing film. And a step of sequentially forming an organic material layer and a second electrode layer on the first electrode layer.
[0049]
In this case, it becomes possible to electrically connect the drain electrode of the transistor and the first electrode layer of the organic light emitting element through the opening of the planarization film. Therefore, wiring for connecting the drain electrode of the transistor and the first electrode layer of the organic light emitting element is not necessary. As a result, it is possible to widen the organic light emitting element formation region on the planarization film, and to widen the transistor formation region on the substrate.
[0050]
The step of forming the organic light emitting element may further include a step of forming an inorganic insulating layer between the first electrode layers. In this case, since the inorganic insulating layer has better thermal conductivity than the organic material layer, the heat generated in the organic material layer is dissipated on the substrate through the first electrode layer and the inorganic insulating layer, and further the substrate Can be discharged to the outside. Thereby, the temperature rise of the organic material layer is suppressed, and crystallization of the organic material layer is prevented. As a result, in the organic light-emitting device, the light emission intensity does not rapidly decrease due to a long-time energization, and the lifetime is extended. For this reason, a highly reliable display device can be realized.
[0051]
DETAILED DESCRIPTION OF THE INVENTION
1 to 7 are process cross-sectional views showing a method of manufacturing an organic electroluminescence element (hereinafter abbreviated as an organic EL element) in the first embodiment of the present invention, and (a) is parallel to the hole injection electrode. A cross section along the direction is shown, and (b) shows a cross section along the direction perpendicular to the hole injection electrode. FIG. 8 is a plan view of the substrate in the process of FIG.
[0052]
In FIGS. 1A and 1B, a glass substrate is used as the substrate 1. A transparent conductive film made of ITO (indium tin oxide) and having a thickness of 0.1 μm is formed on the substrate 1 by sputtering. Then, after applying a resist on the transparent conductive film and performing pre-baking (pre-exposure baking), the resist is exposed to a predetermined pattern and developed. After development, post-baking (post-development baking) is performed, and etching is performed by immersing the substrate 1 in a ferric chloride solution. After the etching is completed, the resist is peeled off. In this way, a plurality of hole injection electrodes 2 made of a transparent conductive film having a thickness of 0.1 μm are formed on the substrate 1 at predetermined intervals.
[0053]
After cleaning the substrate 1, a PMGI film is formed by applying PMGI (Poly di-Methyl Glutar Imide) and baking on the substrate 1 and the plurality of hole injection electrodes 2. Further, a photosensitive positive resist is applied on the PMGI film, prebaked at a predetermined temperature, a predetermined pattern is exposed on the resist, and development is performed. In this way, as shown in FIGS. 2A and 2B, the undercut pattern 12 composed of the PMGI layer 10 and the photosensitive positive resist layer 11 having a tapered cross section is formed on the hole injection electrode 2 at a predetermined interval. It is formed.
[0054]
Thereafter, an inorganic insulating film having a thickness of 0.2 μm made of AlN (aluminum nitride) is formed between the plurality of hole injection electrodes 2 on the substrate 1 and on the plurality of hole injection electrodes 2 by sputtering. As a result, a step of 0.1 μm depending on the film thickness of the hole injection electrode 2 is buried with the inorganic insulating film to ensure flatness.
[0055]
After the formation of the inorganic insulating film, the substrate 1 is immersed in an NMP (N-Methyl-2-Pyrrolidone) solution, and the PMGI layer 10 and the photosensitive positive resist layer 11 are removed. In this way, as shown in FIGS. 3A and 3B, the inorganic insulating layer 3 made of AlN having openings at predetermined intervals on each hole injection electrode 2 is formed between the hole injection electrodes 2 on the substrate 1. And formed on the hole injection electrode 2.
[0056]
Next, after applying a resist to the surfaces of the inorganic insulating layer 3 and the hole injection electrode 2 and performing pre-baking, the resist is exposed to a predetermined pattern and developed. As a result, as shown in FIGS. 4A and 4B, the partition wall separation layer 4 made of resist is formed on the inorganic insulating layer 3 as ribs.
[0057]
FIG. 8 is a plan view of the substrate 1 in the steps of FIGS. 4 (a) and 4 (b). 4A shows a cross section taken along line AA in FIG. 8, and FIG. 4B shows a cross section taken along line BB in FIG.
[0058]
In this case, in order to cause step breakage in the multilayer organic thin film layer, the electron injection electrode and the protective film formed in the subsequent process, a reverse taper type resist is used, and the thickness of the resist is further reduced to the multilayer organic thin film layer, the electron The thickness is made larger than the total thickness of the injection electrode and the protective film. Thereby, a high step is formed. In this embodiment, the total film thickness of the multilayer organic thin film layer, the electron injection electrode, and the protective film is about 0.6 μm, and the film thickness of the partition wall separation layer 4 is 4 μm.
[0059]
Next, as shown in FIGS. 5A and 5B, a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport are formed on the hole injection electrode 2, the inorganic insulating layer 3 and the partition wall separation layer 4 by vapor deposition. A multilayer organic thin film layer 5 made of layers is formed.
[0060]
In this example, CuPc (copper (II) phthalocyanine) with a thickness of 200 mm is used as the hole injection layer, and NPB (N, N′-Di (naphthalene-1-) with a thickness of 1200 mm is used as the hole transport layer. yl) -N, N'-Di (phenyl-benzidine)). In addition, as the light emitting layer, Alq having a thickness of 300 mm _Three (Tris (8-quinolinolato) aluminum) to which 2% of coumarin-6 was added was used as the electron transport layer, and an Alq film having a thickness of 200 mm was used. _Three Is used.
[0061]
Next, as shown in FIGS. 6A and 6B, an electron injection electrode 6 having a thickness of 2000 mm made of an alloy of Mg and In is formed on the multilayer organic thin film layer 5 by vapor deposition. In this manner, a plurality of organic EL elements that emit green light are formed on the substrate 1.
[0062]
Finally, as shown in FIGS. 7A and 7B, a protective film (not shown) is formed on the plurality of organic EL elements by vapor deposition, and then on the substrate 1 using the sealant 7. A plurality of organic EL elements are sealed. In this case, the multilayer organic thin film layer 5 easily absorbs moisture, and when moisture is absorbed, the light emission intensity is likely to deteriorate. Therefore, sealing is performed in a dry nitrogen atmosphere.
[0063]
As described above, in the organic EL element of this example, the inorganic insulating layer 3 made of AlN is formed between the plurality of hole injection electrodes 2 between the substrates 1 and between the light emitting elements on the hole injection electrodes 2.
[0064]
AlN has a higher thermal conductivity than resins such as acrylic resins and polyimide resins. For example, the thermal conductivity of acrylic resin is 0.17 to 0.25 W / m · K (Rika Chronological Table (1997 edition), National Astronomical Observatory, 485 pages). In contrast, the thermal conductivity of AlN is 320 W / m · K (Gihodo Publishing Co., Ltd., Ceramic Engineering Handbook (1989), p. 2022). Therefore, in the case where the inorganic insulating layer 3 made of AlN is formed between the hole injection electrodes 2 and on the hole injection electrodes 2, a multilayer is formed as compared with the case where the hole injection electrodes 2 are coated with an acrylic resin or a polyimide resin. The heat generated in the organic thin film layer 5 is easily dissipated to the substrate 1 through the hole injection electrode 2 and the inorganic insulating layer 3, and is further favorably released from the substrate 1 to the outside. Thereby, the temperature rise of the multilayer organic thin film layer 5 is suppressed, and the crystallization of the multilayer organic thin film layer 5 is prevented. As a result, the light emission intensity does not drop sharply due to energization for a long time, and the life is extended.
[0065]
In addition, as a material of the inorganic insulating layer 3, instead of AlN, SiN (silicon nitride), TiN (titanium nitride), Al ₂ O _Three (Aluminum oxide), SiO ₂ Other ceramics such as (silicon oxide) may be used. Alternatively, as the material of the inorganic insulating layer 3, AlN, SiN, TiN, Al ₂ O _Three , SiO ₂ Two or more materials selected from a plurality of ceramics may be used.
[0066]
For example, the thermal conductivity of SiN is 9.6 W / m · K (Gihodo Publishing Co., Ltd., Ceramic Engineering Handbook (1989), page 2016). Al ₂ O _Three Has a thermal conductivity of 25 to 31 W / m · K (Gihodo Publishing Co., Ltd., Ceramic Engineering Handbook (1989), 2006). Furthermore, SiO ₂ Has a thermal conductivity of 1.4 W / m · K (Rika Chronology (1997 edition), National Astronomical Observatory, 485 pages).
[0067]
Here, in order to compare the reliability of the organic EL element of the said Example and the organic EL element of a comparative example, the time-dependent change of the brightness | luminance was evaluated at room temperature. In the organic EL element of the comparative example, an insulating layer formed by curing a resist by heat treatment in a nitrogen atmosphere was used instead of the inorganic insulating layer 3 in the organic EL element of the example. The curing temperature is 200 ° C. and the curing time is 20 minutes. Other configurations of the organic EL element of the comparative example are the same as those of the organic EL element of the example.
[0068]
FIG. 9 is a diagram showing evaluation results of changes with time in the luminance of the organic EL elements of Examples and Comparative Examples.
[0069]
As shown in FIG. 9, in the organic EL element of the example, a decrease in luminance is suppressed as compared with the organic EL element of the comparative example, and after 1000 hours or more, the difference in luminance decrease is noticeable. ing. Thus, it can be seen that in the organic EL element of the example, high reliability is ensured and the lifetime is extended.
[0070]
FIGS. 10A to 10D, FIGS. 11E and 11F, and FIGS. 12G to 12I are process sectional views showing a method for manufacturing a display device according to the second embodiment of the present invention. is there.
[0071]
As shown in FIG. 10A, a glass substrate is used as the substrate 20. An active layer 21 is formed on the substrate 20, and a gate insulating film 22 covering the active layer 21 is formed. Further, a gate electrode 23 is formed on the gate insulating film 22, and an insulating film 24 that covers the gate electrode 23 is formed.
[0072]
Next, the insulating film 24 and the gate insulating film 22 on both sides of the gate electrode 23 are removed, and contact holes are formed. An aluminum film having a thickness of 0.6 μm is formed by sputtering so as to fill the contact hole. After a resist is applied to the aluminum film and prebaked, a predetermined pattern is exposed to the resist and developed. After post-baking the resist, the aluminum film is etched using the resist as a mask. After the etching is completed, the resist is peeled off. Thereby, the source electrode 25 and the drain electrode 26 are formed. In this way, a thin film transistor 15 for selectively driving an organic EL element described later is formed.
[0073]
Here, since the organic EL element is a power-driven element, in this embodiment, the thin film transistor 15 having the active layer 21 made of low-temperature polycrystalline silicon having a high electron mobility is formed. In the thin film transistor 15, the source electrode 25 and the gate electrode 23 are arranged in a line so that random access is possible, and wirings are extended from the electrodes 25 and 23. In this case, the source electrode 25 and the gate electrode 23 are arranged orthogonal to each other. On the other hand, since the drain electrode 26 is in direct contact with the hole injection electrode 29 as will be described later, only the pad is arranged.
[0074]
In the display device of this embodiment, holes are injected from the thin film transistor 15 into the hole injection electrode of the organic EL element as will be described later. For this reason, in this embodiment, a P-channel type thin film transistor is formed as the thin film transistor 15.
[0075]
Next, as shown in FIG. 10B, a protective film 27 made of SiN having a thickness of 0.8 μm is formed by low pressure plasma CVD (chemical vapor deposition) so as to cover the insulating film 24, the source electrode 25, and the drain electrode 26. ) Method. Further, in order to connect the drain electrode 26 and the hole injection electrode formed in a later step, a resist is patterned on the protective film 27 and the protective film 27 is dry-etched using this resist, A contact hole is formed in the protective film 27.
[0076]
Thereafter, as shown in FIG. 10C, an acrylic photosensitive planarizing film 28 is applied to a film thickness of about 1 μm by spin coating on the thin film transistor 15 on the substrate 20, and then on the hot plate. Pre-bake at 80 ° C. for 10 minutes. In this embodiment, UHP-010 manufactured by Nissan Chemical is used as the photosensitive planarizing film 28. Further, in order to form a contact hole in the planarizing film 28 on the drain electrode 26 of the thin film transistor, energy 120 mJ / cm dispersed from a high pressure mercury lamp is used. ² The i-line is irradiated onto the planarizing film 28 for exposure. After the exposure, development is performed by immersing the substrate 20 in an aqueous sodium carbonate solution for 90 seconds. After development, the substrate 20 is washed with pure water. In this way, a contact hole is formed in the planarization film 28 on the drain electrode 26. After the contact holes are formed, the substrate 20 is baked on a hot plate at 190 ° C. for 15 minutes.
[0077]
As will be described later, in this embodiment, light generated by the organic EL element 16 formed on the planarizing film 28 is extracted from the back surface side of the substrate 20 through the planarizing film 28 (FIG. 12I). ). Therefore, it is preferable that the visible light transmittance of the planarizing film 28 is high. When light is extracted through the planarization film 28 and the substrate 20 as described above, the planarization film 28 and the substrate 20 are made of a translucent material.
[0078]
Further, when moisture enters the organic EL element 16 formed on the planarizing film 28, the life of the organic EL element 16 is reduced. Therefore, in order to prevent moisture from entering the organic EL element 16, it is preferable that the planarization film 28 has a low water absorption.
[0079]
Further, unevenness of light emission occurs when the film thickness of the layer constituting the organic EL element 16 is non-uniform. Therefore, in order to form the layer constituting the organic EL element 16 with a uniform film thickness, the planarization film 28 is formed. Higher flatness is preferable. Therefore, the material of the planarizing film 28 is preferably a material having a low viscosity and capable of being applied uniformly.
[0080]
Next, a transparent conductive film made of ITO and having a thickness of 0.1 μm is formed on the planarizing film 28 by sputtering. After applying a resist on the transparent conductive film and performing pre-baking, the resist is exposed to a predetermined pattern and developed. After development, post-baking is performed, and the substrate 20 is immersed in a ferric chloride solution for etching. After completion of the etching, the substrate 20 is washed and dried, and the substrate 20 is immersed in an NMP solution heated to about 100 ° C. to remove the resist. Thereafter, it is washed with IPA heated to about 70 ° C. and dried. In this manner, as shown in FIG. 10D, a hole injection electrode 29 made of a transparent conductive film extending from the drain electrode 26 in the contact hole of the planarization film 28 to the planarization film 28 is formed.
[0081]
After cleaning the substrate 20, a PMGI film is formed by applying and baking PMGI on the planarizing film 28 and the hole injection electrode 29. Further, a photosensitive positive resist is applied on the PMGI film, prebaked at a predetermined temperature, a predetermined pattern is exposed to the resist, and development is performed. In this way, as shown in FIG. 11E, an undercut pattern 32 composed of the PMGI layer 30 and the photosensitive positive resist layer 31 having a tapered cross section is formed on the hole injection electrode 29 at a predetermined interval.
[0082]
Thereafter, as shown in FIG. 11F, an inorganic insulating film made of AlN having a thickness of 0.2 μm is formed between the plurality of hole injection electrodes 29 on the planarizing film 28 and on the plurality of hole injection electrodes 29 by sputtering. 33 is formed. As a result, a step of 0.1 μm due to the hole injection electrode 29 is filled with the inorganic insulating film 33 to ensure flatness.
[0083]
After the formation of the inorganic insulating film 33, the substrate 20 is immersed in an NMP solution, and the PMGI layer 30 and the photosensitive positive resist layer 31 are removed. In this way, as shown in FIG. 12G, the inorganic insulating layer 33a made of AlN having openings at predetermined intervals on the hole injection electrodes 29 is formed between the hole injection electrodes 29 on the planarizing film 28 and the holes. It is formed on the injection electrode 29.
[0084]
Next, as shown in FIG. 12 (H), a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer are sequentially formed on the hole injection electrode 29 and the inorganic insulating layer 33a by a vapor deposition method. Layer 34 is formed.
[0085]
In this example, CuPc with a thickness of 200 mm is used as the hole injection layer, and NPB with a thickness of 1200 mm is used as the hole transport layer. In addition, as the light emitting layer, Alq having a thickness of 300 mm _Three And 2% of coumarin-6 added thereto, and as an electron transport layer, Alq having a thickness of 200 mm _Three Is used. The light emitting layer having the above composition emits green light.
[0086]
Next, an electron injection electrode 35 having a thickness of 2000 mm made of Mg and In alloy is formed on the multilayer organic thin film layer 34 by vapor deposition. In this way, a plurality of organic EL elements 16 that emit green light are formed on the planarizing film 28.
[0087]
Finally, as shown in FIG. 12I, after a protective film (not shown) is formed on the plurality of organic EL elements 16 by vapor deposition, a plurality of layers on the planarizing film 28 are formed using a sealant 36. The organic EL element 16 is sealed. In this case, the multilayer organic thin film layer 34 easily absorbs moisture, and when moisture is absorbed, the light emission intensity is likely to deteriorate. Therefore, sealing is performed in a dry nitrogen atmosphere.
[0088]
As described above, an active matrix display device in which a plurality of thin film transistors 15 and organic EL elements 16 are formed on the substrate 20 is manufactured. In this display device, light generated in the light emitting layer of the organic EL element 16 is extracted from the back side of the substrate 20 through the hole injection electrode 29, the planarization film 28 and the substrate 20. In this case, since the hole injection electrode 29, the planarization film 28, and the substrate 20 are made of a translucent material, the loss of light is small.
[0089]
As described above, in the display device of this embodiment, the inorganic insulating layer 33a made of AlN is formed between the plurality of hole injection electrodes 29 on the planarization film 28 and between the organic EL elements 16 on the hole injection electrodes 29. ing. As described above, the inorganic insulating layer 33a made of AlN has a higher thermal conductivity than resins such as acrylic resins and polyimide resins. Therefore, the heat generated in the multilayer organic thin film layer 34 is easily dissipated to the planarizing film 28 via the hole injection electrode 29 and the inorganic insulating layer 33a, and is further favorably released from the planarizing film 28 to the outside. Thereby, the temperature rise of the multilayer organic thin film layer 34 is suppressed, and the crystallization of the multilayer organic thin film layer 34 is prevented. As a result, in the organic EL element 16, the light emission intensity is not sharply lowered by energization for a long time, and the life is extended.
[0090]
Further, in this embodiment, by forming the planarizing film 28, it is possible to secure an organic EL element forming region having a flat and large area on the thin film transistor 15. Therefore, by forming the hole injection electrode 29 having a large area in this region, the multilayer organic thin film layer 34 can be formed with a uniform film thickness and a large area. Therefore, a sufficient light emitting area can be obtained in the organic EL element 16, and uneven light emission can be reduced. Therefore, in the display device including such an organic EL element 16, the luminance is improved.
[0091]
Here, in this case, since the organic EL element 16 is formed on the thin film transistor 15 through the planarizing film 28, a sufficient thin film transistor formation region can be secured on the substrate 20. Further, in such a structure, the hole injection electrode 29 of the organic EL element 16 is brought into direct contact with the drain electrode 26 of the thin film transistor 15 in the contact hole, so that the wiring for connecting the drain electrode 26 and the hole injection electrode 29 is connected. Is no longer necessary. Therefore, in the display device of this embodiment, the thin film transistors 15 can be integrated. As a result, a high-definition image can be obtained on the display device.
[0092]
From the above, in the display device of this embodiment, high reliability can be stably maintained, and high definition and high luminance can be achieved at the same time.
[0093]
In the above embodiment, a display device in which a plurality of organic EL elements 16 that emit green light is formed on the substrate 20 has been described. However, organic EL elements that emit green light, blue light, and red light are formed on the substrate. By forming a plurality, a display device for full color display can be manufactured. When manufacturing such a full-color display device, light-emitting layers having different compositions are formed using a metal mask when the multilayer organic thin film layer of each organic EL element is formed (light-emitting layer is separately applied). This case will be described below.
[0094]
FIG. 13 is a schematic process cross-sectional view illustrating a method for manufacturing a display device according to a third embodiment of the present invention. In the third embodiment, the steps prior to the step shown in FIG. 13 are the same as those shown in FIGS. 10A to 10D, FIGS. 11E, 11F, and 12G in the second embodiment. ).
[0095]
In the present embodiment, after the steps shown in FIGS. 10A to 10D, FIGS. 11E, 11F, and 12G are performed, as shown in FIG. A metal mask 80 a having an opening on the hole injection electrode 29 is formed on the inorganic insulating layer 33 a and the remaining hole injection electrode 29. Using this metal mask 80a, a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer are sequentially laminated on the hole injection electrode 29 exposed in the opening to form a multilayer organic thin film layer 34a.
[0096]
Here, CuPc with a film thickness of 200 mm is used as the hole injection layer, and NPB with a film thickness of 500 mm is used as the hole transport layer. Further, as the light emitting layer, Alq having a thickness of 400 mm. _Three Alq with a film thickness of 300 mm as the electron transport layer _Three Is used. Note that the light emitting layer having such a composition emits green light. After forming the multilayer organic thin film layer 34a in this way, the metal mask 80a is removed.
[0097]
Next, as shown in FIG. 13B, a metal mask 80 b having an opening on the predetermined hole injection electrode 29 is formed on the inorganic insulating layer 33 a and the remaining hole injection electrode 29. In this case, the predetermined hole injection electrode 29 is a hole injection electrode 29 adjacent to the hole injection electrode 29 on which the multilayer organic thin film layer 34a is formed. Using this metal mask 80b, a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer are sequentially laminated on the hole injection electrode 29 exposed in the opening to form a multilayer organic thin film layer 34b.
[0098]
The multilayer organic thin film layer 34b is made of Alq having a thickness of 400 mm. _Three The multilayer organic thin film layer 34a has the same configuration as that described above except that perylene is added as a light emitting layer. In this case, the light emitting layer emits blue light. After forming the multilayer organic thin film layer 34b, the metal mask 80b is removed.
[0099]
Further, as shown in FIG. 13C, a metal mask 80 c having an opening on the predetermined hole injection electrode 29 is formed on the inorganic insulating layer 33 a and the remaining hole injection electrode 29. In this case, the predetermined hole injection electrode 29 is a hole injection electrode 29 adjacent to the hole injection electrode 29 on which the multilayer organic thin film 34b is formed. Using this metal mask 80c, a multilayer organic thin film layer 34c is formed by laminating a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer in this order on the hole injection electrode 29 exposed in the opening.
[0100]
The multilayer organic thin film layer 34c is made of Alq having a thickness of 400 mm. _Three The multilayer organic thin film layer 34a has the same structure as that described above except that a material obtained by adding DCM2 to the light emitting layer is used. DCM2 is 4-Dicyanomethylene-2-methyl-6- [2- (2,3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolizin-8-yl) vinyl] -4H-pyran. is there. In this case, the light emitting layer emits red light. After forming the multilayer organic thin film layer 34c, the metal mask 84c is removed.
[0101]
Next, as shown in FIG. 13D, an electron injection electrode 35 having a thickness of 2000 mm made of an alloy of Mg and In is formed on the multilayer organic thin film layers 34a to 34c. In this way, a plurality of organic EL elements 16 a to 16 c that respectively emit green, blue, and red light are formed on the planarizing film 28.
[0102]
Finally, the plurality of organic EL elements 16a to 16c on the planarization film 28 are sealed using the sealing agent 36 by a method similar to the method shown in FIG.
[0103]
As described above, an active matrix type full-color display device in which the thin film transistor 15 is formed on the substrate 20 and the three types of organic elements 16a to 16c that respectively emit green, blue, and red light are formed. Make it. In such a display device, one pixel is configured with three types of organic EL elements 16a to 16c as one unit.
[0104]
As described above, in this embodiment, the inorganic insulating layer 33 a made of AlN is formed between the plurality of hole injection electrodes 29 on the planarizing film 28 and between the organic EL elements 16 a to 16 c on the hole injection electrode 29. Yes. As described above, the inorganic insulating layer 33a made of AlN has a higher thermal conductivity than resins such as acrylic resins and polyimide resins. Therefore, the heat generated in the multilayer organic thin film layers 34a to 34c is easily dissipated to the planarizing film 28 through the hole injection electrode 29 and the inorganic insulating layer 33a, and is further favorably released from the planarizing film 28 to the outside. Thereby, the temperature rise of multilayer organic thin film layers 34a-34c is suppressed, and crystallization of multilayer organic thin film layers 34a-34c is prevented. As a result, in the organic EL elements 16a to 16c, the light emission intensity does not rapidly decrease due to energization for a long time, and the life is extended.
[0105]
Further, in this embodiment, by forming the planarizing film 28, it is possible to secure an organic EL element forming region having a flat and large area on the thin film transistor 15. Therefore, by forming the hole injection electrode 29 having a large area in this region, the multilayer organic thin film layers 34a to 34c can be formed with a uniform film thickness and a large area. Therefore, a sufficient light emitting area can be obtained in the organic EL elements 16a to 16c, and uneven light emission can be reduced. Therefore, in a display device including such organic EL elements 16a to 16c, the luminance can be improved.
[0106]
Here, in this case, since the organic EL elements 16 a to 16 c are formed on the thin film transistor 15 via the planarizing film 28, a sufficient thin film transistor formation region can be secured on the substrate 20. Further, in such a structure, the hole injection electrode 29 of the organic EL elements 16a to 16c is brought into direct contact with the drain electrode 26 of the thin film transistor 15 in the contact hole, so that the drain electrode 26 and the hole injection electrode 29 are connected. Wiring is not required. Therefore, in the display device of this embodiment, the thin film transistors 15 can be integrated. As a result, a high-definition image can be obtained on the display device.
[0107]
As described above, in this embodiment, it is possible to realize a full-color display device capable of stably maintaining high reliability and simultaneously achieving high definition and high luminance. It becomes.
[0108]
In the second and third embodiments, the display device having a structure in which the light generated in the organic EL elements 16, 16a to 16c is extracted from the back surface side of the substrate 20 through the planarization film 28 and the substrate 20 has been described. However, a display device having a structure in which light is extracted from the opposite side of the substrate 20, that is, the sealing side, without using the planarizing film 28 and the substrate 20 is also possible. This case will be described below.
[0109]
FIGS. 14A to 14C and FIGS. 15D to 15F are schematic process cross-sectional views showing a method for manufacturing a display device according to the fourth embodiment of the present invention. In the fourth embodiment, the steps before the step shown in FIG. 14A are the same as the steps shown in FIGS. 10A to 10C of the first embodiment.
[0110]
As will be described later, in the display device of this embodiment, the drain electrode 26 of the thin film transistor 15 and the electron injection electrode 35 of the organic EL element 16 are brought into direct contact, and electrons are injected from the thin film transistor 15 into the electron injection electrode 35. For this reason, in this embodiment, an N-channel transistor is formed as the thin film transistor 15.
[0111]
In this embodiment, as will be described later, light generated by the organic EL element 16 formed on the planarizing film 28 is extracted from the opposite side of the substrate 20 without passing through the planarizing film 28 and the substrate 20 (FIG. 15 (F)). Therefore, in this embodiment, even if the visible light transmittance of the planarization film 28 and the substrate 20 is lower than that of the second and third embodiments in which light is extracted through the planarization film 28 and the substrate 20. Good.
[0112]
Also in this embodiment, as in the second and third embodiments, it is preferable that the planarization film 28 has a low water absorption in order to prevent moisture from entering the organic EL element 16. Moreover, in order to form the layer which comprises the organic EL element 16 with a uniform film thickness, the material of the planarization film | membrane 28 has a low viscosity and can apply | coat uniformly.
[0113]
In this embodiment, after the steps shown in FIGS. 10A to 10C are performed, as shown in FIG. 14A, an opening is formed on the drain electrode 26 exposed in the contact hole and in the peripheral region. A metal mask (not shown) having a portion is formed on the planarizing film 28. Using this metal mask, an electron injection electrode 35 made of an alloy of Mg and In and extending from the drain electrode 26 in the contact hole of the planarization film 28 onto the planarization film 28 is formed by an evaporation method and a lift-off method.
[0114]
After removing the metal mask, the substrate 20 is cleaned. Further, as shown in FIG. 14B, a PMGI film is formed on the planarizing film 28 and the electron injection electrode 35 by applying PMGI and baking. Further, a photosensitive positive resist is applied on the PMGI film, prebaked at a predetermined temperature, a predetermined pattern is exposed to the resist, and development is performed. In this manner, the undercut pattern 32 composed of the PMGI layer 30 and the photosensitive positive resist 31 having a tapered cross section is formed on the electron injection electrode 35 at predetermined intervals.
[0115]
Thereafter, as shown in FIG. 14C, an inorganic insulating film made of AlN and having a thickness of 0.5 μm is formed between the plurality of electron injection electrodes 35 on the planarizing film 28 and on the plurality of electron injection electrodes 35 by sputtering. 33 is formed. As a result, a step of 0.5 μm due to the electron injection electrode 35 is filled with the inorganic insulating film 33 to ensure flatness.
[0116]
After the formation of the inorganic insulating film 33, the substrate 20 is immersed in an NMP solution, and the PMGI layer 30 and the photosensitive positive resist layer 31 are removed. In this manner, as shown in FIG. 15D, the inorganic insulating layer 33a made of AlN having openings at predetermined intervals on each electron injection electrode 35 is formed between the electron injection electrodes 35 on the planarizing film 28 and the electrons. It is formed on the injection electrode 35.
[0117]
Next, as shown in FIG. 15E, an electron transport layer, a light emitting layer, a hole transport layer, and a hole injection layer are sequentially formed on the electron injection electrode 35 and the inorganic insulating layer 33a by vapor deposition. Thereby, the multilayer organic thin film layer 34A is formed.
[0118]
In this example, as in the third example, when the multilayer organic thin film layer 34A is formed, three types of light emission that emit green light, blue light, and red light by the same method as shown in FIG. Form a layer.
[0119]
In this case, as the electron transport layer, Alq having a thickness of 300 mm. _Three , NPB having a thickness of 500 mm is used as the hole transport layer, and CuPc having a thickness of 200 mm is used as the hole injection layer. In addition, as the light emitting layer emitting green light, Alq _Three As a light-emitting layer that emits blue light using a material obtained by adding coumarin-6 to _Three As a light emitting layer that emits red light using a material in which perylene is added, Alq _Three To which DCJT is added. In addition, the film thickness of each light emitting layer is about 400 mm.
[0120]
Next, a 0.3 μm-thick transparent conductive film made of ITO is formed on the multilayer organic thin film layer 34 </ b> A by sputtering to form a hole injection electrode 29. In this way, a plurality of three types of organic EL elements 16 that emit green light, blue light, and red light are formed on the planarizing film 28.
[0121]
Finally, as shown in FIG. 15F, the plurality of organic EL elements 16 on the planarizing film 28 are sealed using an insulating film 36A made of a light-transmitting material and capable of being formed at a low temperature. To do. In this embodiment, an alumina film is formed as the insulating film 36A. The alumina film is formed by sputtering using ECR (electron cyclotron resonance) plasma with the substrate temperature maintained at 80 ° C.
[0122]
As described above, an active matrix full-color display device in which a plurality of thin film transistors 15 and organic EL elements 16 that emit green light, blue light, and red light are formed on the substrate 20 is manufactured. In this display device, light generated in the light emitting layer of the organic EL element 16 is extracted from the opposite side of the substrate 20, that is, the sealing side, through the hole injection electrode 29 and the insulating film 36A. In this case, since the hole injection electrode 29 and the insulating film 36A are made of a translucent material, there is little light loss.
[0123]
As described above, in the display device of this example, the inorganic insulating layer 33a made of AlN is formed between the plurality of electron injection electrodes 35 on the planarization film 28 and between the organic EL elements 16 on the electron injection electrodes 35. ing. As described above, the inorganic insulating layer 33a made of AlN has a higher thermal conductivity than resins such as acrylic resins and polyimide resins. Therefore, the heat generated in the multilayer organic thin film layer 34A is easily dissipated to the planarizing film 28 via the electron injection electrode 35 and the inorganic insulating layer 33a, and is further favorably released from the planarizing film 28 to the outside. Thereby, the temperature rise of the multilayer organic thin film layer 34A is suppressed, and the crystallization of the multilayer organic thin film layer 34A is prevented. As a result, in the organic EL element 16, the light emission intensity is not sharply lowered by energization for a long time, and the life is extended.
[0124]
Further, in this embodiment, by forming the planarizing film 28, it is possible to secure an organic EL element forming region having a flat and large area on the thin film transistor 15. Therefore, by forming the electron injection electrode 35 having a large area in this region, the multilayer organic thin film layer 34A can be formed with a uniform film thickness and a large area. Therefore, a sufficient light emitting area can be obtained in the organic EL element 16, and uneven light emission can be reduced. Therefore, in the display device including such an organic EL element 16, the luminance is improved.
[0125]
Here, in this case, since the organic EL element 16 is formed on the thin film transistor 15 through the planarizing film 28, a sufficient thin film transistor formation region can be secured on the substrate 20. Further, in such a structure, since the electron injection electrode 35 of the organic EL element 16 is brought into direct contact with the drain electrode 26 of the thin film transistor 15 in the contact hole, wiring for connecting the drain electrode 26 and the electron injection electrode 35 is provided. Is no longer necessary. Therefore, in the display device of this embodiment, the thin film transistors 15 can be integrated. As a result, a high-definition image can be obtained on the display device.
[0126]
As described above, in this embodiment, it is possible to realize a full-color display device capable of stably maintaining high reliability and simultaneously achieving high definition and high luminance. .
[0127]
In the first to fourth embodiments, the material of the inorganic insulating layer 33a is SiN, TiN, Al instead of AlN. ₂ O _Three , SiO ₂ Other ceramics may be used. Alternatively, as the material of the inorganic insulating layer 33a, AlN, SiN, TiN, Al ₂ O _Three , SiO ₂ Two or more materials selected from a plurality of ceramics may be used.
[0128]
In the first to fourth embodiments, by using the sputtering method, the inorganic insulating layers 3 and 33a can be formed at a temperature near room temperature at which resist deformation does not occur. Therefore, the inorganic insulating layers 3 and 33a can be formed by patterning using a resist. In the case where a resist is not used for patterning the inorganic insulating layers 3 and 33a, the inorganic insulating layers 3 and 33a may be formed by using another film forming method such as a CVD (chemical vapor deposition) method. .
[0129]
Further, in the first to fourth embodiments, AlN is formed by a lift-off method using a two-layer resist process for forming undercut patterns 12 and 32 composed of PMGI layers 10 and 30 and photosensitive positive resist layers 11 and 31. The inorganic insulating layers 3 and 33a are formed, but the inorganic insulating layers 3 and 33a can be formed even if a resist capable of forming a reverse taper shape is used.
[0130]
In the second to fourth embodiments, the planarizing film 28 made of an acrylic material is formed. However, the material of the planarizing film 28 is not limited to this. For example, the planarizing film 28 made of a polyimide material or the like may be formed.
[0131]
The material of the planarizing film 28 is preferably a material having low water absorption as described above, and a material having a low viscosity and capable of being applied uniformly.
[0132]
In particular, in the display device in which light is extracted through the planarization film 28 as in the second and third embodiments, the planarization film 28 is preferably made of a material having a high visible light transmittance.
[0133]
In the second to fourth embodiments, the protective film 27 made of SiN is formed. However, a protective film made of other than SiN, for example, SiO ₂ , Al ₂ O _Three You may form the protective film which consists of etc. Further, the method for forming the protective film is not limited to the voltage plasma CVD method. The protective film may be formed by a method using a sputter deposition method or a lift-off method.
[Brief description of the drawings]
FIG. 1 is a process cross-sectional view illustrating a method for manufacturing an organic EL element in a first embodiment of the present invention.
FIG. 2 is a process cross-sectional view illustrating a method for manufacturing an organic EL element in a first example of the invention.
FIG. 3 is a process cross-sectional view illustrating a method for manufacturing an organic EL element in a first example of the invention.
FIG. 4 is a process cross-sectional view illustrating a method for manufacturing an organic EL element in a first example of the invention.
FIG. 5 is a process cross-sectional view illustrating a method of manufacturing an organic EL element in a first example of the invention.
FIG. 6 is a process sectional view showing a method for manufacturing an organic EL element in a first example of the invention.
FIG. 7 is a process cross-sectional view illustrating a method for manufacturing an organic EL element in a first example of the invention.
FIG. 8 is a plan view of a substrate in the process of FIG. 4;
FIG. 9 is a diagram showing evaluation results of changes with time in luminance of organic EL elements of examples and comparative examples.
FIG. 10 is a process cross-sectional view illustrating the method for manufacturing the display device in the second example of the present invention.
FIG. 11 is a process cross-sectional view illustrating the method for manufacturing the display device in the second example of the present invention.
FIG. 12 is a process sectional view showing the method for manufacturing the display device in the second example of the present invention.
FIG. 13 is a process cross-sectional view illustrating the method for manufacturing the display device according to the third example of the present invention.
FIG. 14 is a process sectional view showing a method for manufacturing a display device in a fourth example of the present invention.
FIG. 15 is a process cross-sectional view illustrating the method for manufacturing the display device according to the fourth example of the present invention.
FIG. 16 is a schematic view showing a method for producing an organic EL element.
FIG. 17 is a cross-sectional view illustrating an example of a conventional display device.
[Explanation of symbols]
2,29 hole injection electrode
3,33a Inorganic insulating layer
4 Separation layer
7,36 Sealant

Claims (2)

A display device comprising a plurality of organic light emitting elements and a plurality of transistors for selectively driving the plurality of organic light emitting elements on a substrate,
The plurality of transistors are formed on a substrate, a planarization film is formed on the plurality of transistors, and the organic light emitting element is formed on the planarization film corresponding to each of the plurality of transistors, and the organic light emission A display device, wherein an inorganic insulating layer made of aluminum nitride is formed between first electrode layers constituting an element and disposed on the planarizing film . In a method of manufacturing a display device including a plurality of organic light emitting elements and a plurality of transistors for selectively driving the plurality of organic light emitting elements on a substrate,
Forming the plurality of transistors on the substrate;
Forming a planarization film on the plurality of transistors;
A step of forming the plurality of organic light emitting elements on the planarizing film corresponding to the plurality of transistors, respectively,
The method of manufacturing a display device, wherein the step of forming the organic light emitting element further comprises a step of forming an inorganic insulating layer made of aluminum nitride between the first electrode layers .

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