JP4363374B2 - Manufacturing method of color organic EL display - Google Patents

Description

  The present invention relates to a method for manufacturing a color organic EL display in which a gas barrier layer is interposed between an organic EL (electroluminescence) structure and a color filter.

  This type of color organic EL display generally has a configuration in which a color filter layer, an overcoat layer, a gas barrier layer, and an organic EL structure are sequentially laminated on a substrate.

  Here, the gas barrier layer acts as a barrier that prevents the water vaporized from the color filter layer made of resin or the overcoat layer from entering the organic EL structure thereon, and is caused by such moisture. This prevents problems such as a dark spot of the organic EL structure and a decrease in luminous efficiency.

  As a manufacturing method of a color organic EL display having such a gas barrier layer, the present applicant has previously proposed Japanese Patent Application No. 2004-212593.

  This manufacturing method is for improving the gas barrier property of the gas barrier layer. After the color filter layer is formed on the substrate and the overcoat layer is formed thereon by photopolymerization, before the gas barrier layer is formed. The base portion of the gas barrier layer is subjected to a dehydration process, and then the gas barrier layer is formed by an atomic layer epitaxial growth method (hereinafter referred to as ALE method) at a temperature lower than the decomposition start temperature of the color filter layer and the overcoat layer. An organic EL structure is formed.

  According to this, water contained in the base portion of the gas barrier layer such as a color filter and an overcoat is removed by dehydration, and the gas barrier layer is formed by the ALE method having excellent coverage, thereby reducing pinholes. A gas barrier layer with excellent gas barrier properties is realized.

  However, as a result of further studies by the present inventor, the above manufacturing method can initially prevent dark spots, but prevents dark spots with time, that is, dark spots that occur during driving and storage. Was found to be insufficient.

  As a result of investigation by the present inventor, it was found that sulfur or a sulfur compound present in the surface layer portion of the overcoat layer, which is the base of the gas barrier layer, is the main cause of the dark spot. Specifically, the inventor cut the cross section of the dark spot generation portion and observed it with a transmission electron microscope.

  FIG. 4 is a schematic cross-sectional view of a dark spot generation portion based on the microscopic observation. The gas barrier layer 20 and the anode 31 are laminated on the overcoat layer 14. Here, it can be seen that there is a void B in the surface layer portion of the overcoat layer 14 and the gas barrier layer 20 on the upper portion is missing in a tapered shape. And this defect | deletion part is a location which becomes a dark spot with time.

  FIG. 5 is also a schematic cross-sectional view of the vicinity of the overcoat layer 14 based on microscopic observation, and it can be seen that the foreign matter K exists in the vicinity of the surface layer of the overcoat layer 14. When the present inventor conducted surface elemental analysis using EDX or the like, the foreign matter K was found to be a sulfur component, that is, sulfur or a sulfur compound.

  Further, according to the observation of the present inventor, it has been found that the foreign matter K is concentrated on the surface layer portion of the overcoat layer 14 and is not present on the inner side of the surface. And it confirmed that the said dark spot had generate | occur | produced corresponding to the location where such a foreign material K exists.

  Usually, the overcoat layer 14 is formed by photopolymerization of a resin such as an acrylic resin. In the resin, a generally known photopolymerization initiator or sensitizer containing a sulfur component is contained. It has been added.

  This sulfur component cannot be completely reacted when the overcoat layer 14 is formed, and a part of the sulfur component remains as the foreign matter K in the surface layer portion of the overcoat layer 14. It is considered that the sulfur component is volatilized and a defective portion of the gas barrier layer 20 as described above is generated.

  The present invention has been made in view of the above problems, and in a color organic EL display in which a color filter layer, an overcoat layer, a gas barrier layer, and an organic EL structure are sequentially laminated on a substrate, The purpose is to prevent the generation of dark spots due to sulfur components remaining in the steel as much as possible.

  In order to achieve the above object, the present invention provides a sulfur removal step of removing sulfur or a sulfur compound in the surface layer portion of the overcoat layer between the overcoat formation step and the dehydration step in the production method shown in the prior application. It is characterized by performing.

  According to this, since the sulfur component remaining in the surface layer portion of the overcoat layer, which is the base portion of the gas barrier layer, can be removed, the generation of dark spots due to the sulfur component can be prevented as much as possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic cross-sectional configuration of a color organic EL display 100 according to an embodiment of the present invention.

  The substrate 11 is made of a transparent substrate such as a glass substrate or a resin substrate. On one surface of the substrate 11, there are provided color filter layers 13 of red, blue, and green, which are the three primary colors of light.

  Here, a shadow mask 12 for separating the color filter layer 13 is formed on one surface of the substrate 11, and the color filter layer 13 is provided thereon. The shadow mask 12 is configured as a black matrix that blocks light, and is made of resin or metal and is provided as necessary.

  A transparent overcoat layer 14 formed by photopolymerization such as UV is formed on the upper portion as a planarizing layer. The color filter layer 13 and the overcoat layer 14 are mainly formed of an acrylic resin. A gas barrier layer 20 is formed on the overcoat layer 14 so as to cover the overcoat layer 14.

  The gas barrier layer 20 is formed by the ALE method at a temperature equal to or lower than the decomposition start temperature of the color filter layer 13 and the overcoat layer 14. In this example, the decomposition start temperature of the color filter layer 13 and the overcoat layer 14 is about 230 ° C.

Further, the gas barrier layer 20 is specifically an inorganic film composed of one or more selected from Al ₂ O ₃ , TiO ₂ , SiN, SiO ₂ , SiON, ZrO ₂ , MgO, CaO, GeO ₂ , HfO ₂ and ZnO. It can be. In this example, the gas barrier layer 20 is an alumina (Al ₂ O ₃ ) film.

  An organic EL structure 30 is formed on one surface of the substrate 11, that is, on the gas barrier layer 20. The organic EL structure 30 is a structure in which an organic layer 32 containing an organic light emitting material is disposed between a pair of electrodes 31 and 33 facing each other. As the organic EL structure 30, a material and a film configuration used for a normal organic EL structure can be adopted. A specific example shown in FIG. 1 will be described.

  An anode 31 made of a transparent conductive film such as ITO is formed on the gas barrier layer 20. In this example, the anode 31 is formed in a stripe shape extending in the left-right direction in FIG.

  Further, an insulating film 40 made of an insulating material is formed in order to prevent a short circuit at the edge of the anode 31. Similarly, a partition wall 41 for separating the cathode 33 is formed of resin or the like.

  An organic layer 32 including a light emitting layer made of an organic light emitting material is formed on the anode 31, and a cathode 33 made of Al or the like is formed on the organic layer 32. In this example, the cathode 33 has a stripe shape orthogonal to the anode 31, and is formed in a stripe shape extending in the direction perpendicular to the paper surface in FIG.

  As described above, in the organic EL structure 30 of this example, the stripe-shaped anodes 31 orthogonal to each other and the cathodes 33 separated by the partition walls 41 intersect and overlap each other, and the regions where these electrodes 31 and 33 overlap each other. Constitutes a pixel which is a portion to perform light-emitting display.

  In such a color organic EL display 100, by applying a driving DC voltage between the anode 31 and the cathode 33, the light emitting layer in the organic layer 32 emits light in a desired pixel. ing. The emitted light is extracted from the substrate 11 side through the color filter layer 13.

  Next, a method for manufacturing the color organic EL display 100 will be described with reference to FIG. FIG. 2 is a process flow diagram showing the flow of steps S1 to S10 of the manufacturing method.

  This manufacturing method is obtained by adding a sulfur removing step S3 to the manufacturing method shown in the above-mentioned prior application, and performing the sulfur removing step S3 between the overcoat layer forming step S2 and the dehydrating step S4.

  First, in the color filter layer forming step S1, a color filter layer 13 made of a photopolymerizable acrylic resin or the like is formed on one surface of a substrate 10 made of an alkali-free glass substrate by spin coating or photolithography, for example, with a film thickness of 1 .5 μm. Further, a shadow mask 12 is formed between the color filter layers 13 separated for each color by a photolithographic method.

  Next, in the overcoat layer forming step S2, a resin that becomes the overcoat layer 14, such as a photopolymerizable transparent acrylic resin, is disposed thereon by a spin coat method, a photolithography method, or the like. Is photopolymerized by irradiation. Thereby, the overcoat layer 14 is formed with a film thickness of, for example, 2.0 μm. Through the steps so far, the base portion of the gas barrier layer 20 is completed.

  Next, in sulfur removal process S3, the sulfur or sulfur compound of the surface layer part of the overcoat layer 14 is removed. Here, the sulfur or the sulfur compound is generated from a sulfur component used for a general photopolymerization initiator or sensitizer added to the resin constituting the overcoat layer 14, and is a simple substance of sulfur or a sulfur oxide. is there.

As specific methods for removing these sulfur components, the surface of the overcoat layer 14 is polished by lapping or the like, the surface of the overcoat layer 14 is irradiated with UV, or in an atmosphere containing H ₂ O gas. Examples of the method include heating the overcoat layer 14 and performing plasma irradiation on the surface of the overcoat layer 14 with an argon-oxygen mixed gas.

  Here, the polishing, UV irradiation, and plasma irradiation described above remove a part of the surface layer portion of the overcoat layer 14 by these methods, whereby the sulfur contained in the removed portion and the portion included therein. The component is removed.

  When the present inventor examined by microscopic observation and the like, the detailed mechanism is unknown, but in the overcoat layer 14, a sulfur component may remain in a portion having a depth of about 20 nm from the surface. all right.

  Therefore, in the above-described polishing, UV irradiation, and plasma irradiation, the surface of the overcoat layer 14 is removed to a region where there is substantially no sulfur component, for example, to a depth of about 0.1 μm.

In addition, in the method of heating the overcoat layer 14 in an atmosphere containing H ₂ O gas, the detailed mechanism is unknown, but the sulfur component present in the surface layer portion of the overcoat layer 14 contains H ₂ O gas and It is thought to be removed by chemical reaction and volatilization.

  In this example, in the sulfur removal step S3, the surface portion of the overcoat layer 14 was removed by a thickness of 0.1 μm by general lapping. In addition, the specific example of sulfur removal methods other than grinding | polishing is mentioned later.

  Next, in the dehydration step S4, a dehydration process is performed on the base portion of the gas barrier layer 20. This dehydration processing temperature is set to a temperature equal to or higher than the temperature applied to the substrate 11 in steps S4 to S10 after the dehydration processing step S4 and equal to or lower than the decomposition start temperature of the color filter layer 13. For example, in this example, the temperature is set to 200 ° C. to 230 ° C.

  Next, in the gas barrier layer forming step S5, the substrate 11 is set in an ALE apparatus, and the gas barrier layer 20 is formed by the ALE method. Here, the gas barrier layer 20 is formed at a temperature equal to or lower than the decomposition start temperature of the color filter layer 13 and the overcoat layer 14. For example, the film formation temperature of the gas barrier layer 20 can be about 100 to 250 ° C.

  Next, the organic EL structure 30 is formed on one surface of the substrate 11, that is, on the gas barrier layer 20. In this example, first, an anode 31 is formed by patterning an ITO film formed by sputtering on the gas barrier layer 20 by etching or the like in an anode forming step S6.

  Next, in an insulating film forming step S7, an insulating film 40 is formed between the anodes 31 by a photolithography method. Subsequently, in a partition forming step S8, a partition wall 41 is formed thereon by a photolithography method. Next, in the organic layer forming step S9, the organic layer 32 is formed on the anode 31 by a vacuum deposition method.

  Next, in the cathode forming step S10, the cathode 33 is formed on the organic layer 32 by a vacuum evaporation method. The film formation temperature of these organic layer 32 and cathode 33 by vacuum deposition is about room temperature. Thus, the color organic EL display 100 shown in FIG. 1 is completed.

  After that, in order to block moisture from the surface of the organic EL structure 30, the outer surface side of the organic EL structure 30 is sealed with dry nitrogen or the like by a stainless or glass sealing can with a desiccant. You may make it stop.

  As described above, in the manufacturing method of the present embodiment, the sulfur removal step S3 is performed between the overcoat formation step S2 and the dehydration step S4. Therefore, according to the present embodiment, since the sulfur component remaining in the surface layer portion of the overcoat layer 14 that is the base portion of the gas barrier layer 20 can be removed, the generation of dark spots due to the sulfur component can be prevented as much as possible.

  Here, in the example of the manufacturing method described above, after the overcoat layer 14 is formed, the surface layer portion in which the sulfur component remains in the overcoat layer 14 is polished and removed by lapping in the sulfur removing step S3.

  And when the light emission state was confirmed about the color organic EL display 100 manufactured in this example, the dark spot did not exist by initial stage light emission. Moreover, when surface elemental analysis was performed about the surface layer part of the overcoat layer 14, it was confirmed that the sulfur component was not detected but removed.

  Thereafter, the sample of this example was allowed to stand at 65 ° C. for 200 hours, and the light emission state was confirmed again. As shown in FIG. 3A, no dark spot was generated. 3A is a plan view showing a pixel in which no dark spot is generated, and FIG. 3B is a plan view showing a pixel in which a dark spot D is generated. These are based on microscopic observation. FIG.

  As a comparative example, a color organic EL display was produced in the same manner as in the above production method except that the sulfur removal step S3 was omitted. In this comparative example, there was no dark spot in the initial light emission, but after leaving it to stand at 65 ° C. for 200 hours, the light emission state was confirmed. As shown in FIG. Occurred.

  In this example, it can also be expected that unevenness on the surface of the overcoat layer 14 is reduced by performing the sulfur removal step S3 by lapping. In addition to the lapping, a general surface polishing method may be employed as the polishing method.

Next, as a method for removing sulfur other than polishing, the above-described UV irradiation, heating in an H ₂ O gas atmosphere, and plasma irradiation will be described with reference to specific examples.

[Specific Example 1]
In this example, it was performed in the same manner as the above manufacturing method except that in the sulfur removal step S3, UV irradiation was performed instead of lapping.

After the overcoat layer 14 was formed on the substrate 11, the substrate 11 was set in a UV irradiation apparatus, and the surface of the overcoat layer 14 was irradiated with UV having an illuminance of 20 mW / cm ² in an oxygen atmosphere for 120 seconds. The overcoat layer 14 after the UV treatment had an average film thickness reduced by 0.1 μm as compared with that before the treatment.

  Thereafter, the dehydration step S4 to the cathode formation step S10 were performed to produce the color organic EL display 100 of this example. Then, as in the case of the above polishing, surface elemental analysis was performed. As a result, sulfur components were not detected, and the light emission state after being allowed to stand at 65 ° C. for 200 hours was investigated, but no dark spots were observed.

[Specific Example 2]
In this example, in sulfur removal step S3, except that was carried out heating during the H ₂ O gas atmosphere instead of lapping was performed in the same manner as the above-described manufacturing method.

After the overcoat layer 14 was formed on the substrate 11, the substrate 11 was set in a gas barrier layer deposition apparatus, that is, an ALE apparatus. Then, the degree of vacuum in the apparatus was 10 ⁻² Torr, and the substrate 11 was heated to a temperature 10 ° C. lower than the heat resistance temperature of the color filter layer 13 and the overcoat layer 14.

While maintaining the degree of vacuum and the state of heating, nitrogen carrier gas was passed through the water tank and then introduced into the apparatus at a flow rate of 400 SCCM for 30 minutes. As a result, the overcoat layer 14 is heated while being exposed to an atmosphere containing H ₂ O gas.

  Thereafter, the dehydration step S4 to the cathode formation step S10 were performed to produce the color organic EL display 100 of this example. Also in this example, no sulfur component was detected, and no dark spots were observed even after being left at 65 ° C. for 200 hours.

In addition, when the introduction time of the nitrogen carrier gas containing H ₂ O gas, that is, the treatment time in which the overcoat layer 14 is heated in an atmosphere containing H ₂ O gas is 10 minutes or 20 minutes. When the same evaluation was made, dark spots as shown in FIG. 3B were observed. The processing time in this example requires about 30 minutes.

[Specific Example 3]
In this example, it was performed in the same manner as the above manufacturing method except that, in the sulfur removal step S3, plasma irradiation with an argon-oxygen mixed gas was performed instead of lapping.

  After the overcoat layer 14 is formed on the substrate 11, the substrate 11 is set in a plasma irradiation apparatus, the inside of the apparatus is adjusted to a pressure of 20 Pa, argon gas is flowed at 80 SCCM, oxygen gas is flowed at 20 SCCM, and output is 40 W for 20 seconds. The plasma treatment was performed. The overcoat layer 14 after the plasma treatment had an average film thickness reduced by 0.1 μm on average compared with that before the treatment.

  Thereafter, the dehydration step S4 to the cathode formation step S10 were performed to produce the color organic EL display 100 of this example. Also in this example, no sulfur component was detected, and no dark spots were observed even after being left at 65 ° C. for 200 hours.

The specific method for removing the sulfur component is not limited to the above-described polishing, UV irradiation, heating in an H ₂ O gas atmosphere, and plasma irradiation, but sulfur in the surface layer portion of the overcoat layer 14. Alternatively, other methods may be used as long as they can remove sulfur compounds.

  The sulfur component contained in the photopolymerization initiator and photosensitizer added to the overcoat layer 14 is one that sublimes by heating in the dehydration step S4 that is the next step of the sulfur removal step S3. preferable. If such a thing is used, even if some sulfur components remain after sulfur removal process S3, the remainder can be volatilized and removed in dehydration process S4.

  Further, the configuration of the color organic EL display 100 shown in FIG. 1 is merely an embodiment, and is not limited thereto.

1 is a schematic cross-sectional view of a color organic EL display according to an embodiment of the present invention. It is a process flow figure showing a flow of each process in a manufacturing method of a color organic EL display concerning the above-mentioned embodiment. (A) is a plan view of a pixel where a dark spot is not generated, and (b) is a plan view of a pixel where a dark spot is generated. It is a schematic sectional drawing of the generation | occurrence | production part of the dark spot based on microscope observation. It is a schematic sectional drawing of the vicinity part of the overcoat layer based on microscope observation.

Explanation of symbols

11 ... Substrate, 13 ... Color filter layer, 14 ... Overcoat layer,
20 ... Gas barrier layer, 30 ... Organic EL structure.

Claims (5)

In the method of manufacturing a color organic EL display in which a color filter layer (13), an overcoat layer (14), a gas barrier layer (20), and an organic EL structure (30) are sequentially formed on a substrate (11).
After the overcoat layer (14) is formed by photopolymerization on the color filter layer (13), a sulfur removal step of removing sulfur or sulfur compounds in the surface layer portion of the overcoat layer (14);
Subsequently, a dehydration step of performing a dehydration process on the base portion of the gas barrier layer (20),
Thereafter, the gas barrier layer (20) is formed on the overcoat layer (14) by an atomic layer epitaxial growth method at a temperature not higher than the decomposition start temperature of the color filter layer (13) and the overcoat layer (14). And a gas barrier forming step of forming a color organic EL display. 2. The method of manufacturing a color organic EL display according to claim 1, wherein, in the sulfur removal step, the surface of the overcoat layer is polished to remove sulfur or a sulfur compound. 2. The method of manufacturing a color organic EL display according to claim 1, wherein, in the sulfur removal step, the surface of the overcoat layer (14) is subjected to UV irradiation to remove sulfur or a sulfur compound. _2. The color organic according to claim 1, wherein in the sulfur removal step, the overcoat layer (14) is heated in an atmosphere containing H ₂ O gas to remove sulfur or a sulfur compound. Manufacturing method of EL display. The color organic EL according to claim 1, wherein in the sulfur removal step, the surface of the overcoat layer (14) is subjected to plasma irradiation with an argon-oxygen mixed gas to remove sulfur or a sulfur compound. Display manufacturing method.

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