JP2005243428A - Manufacturing method of electroluminescent display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress damages of a pixel electrode in manufacturing a display panel using electroluminescence. <P>SOLUTION: Patterning is applied to color filters 3R, 3G, 3B in a lattice shape on a transparent substrate 2, the lower part electrode 4 is film-formed on the color filters 3R, 3G, 3B, an electroluminescent layer 5 is film-formed on the lower part electrode 4, the upper part electrode 6 is film-formed on the electroluminescent layer 5, and a conductive protection film 7 is film-formed on the upper part electrode 6. Then, a resist mask 8 is formed on the conductive protection film 7 by a photo-resist method, and ions are doped on the conductive protection film 7 and the upper part electrode 6 through an opening part between the resist masks 8. A conductive spacer 14 is pinched between obtained electroluminescent element array substrate 1 and a transistor array substrate 10, and the electroluminescent element array substrate 1 is pasted to the transistor array substrate 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an electroluminescence display panel using an electroluminescence element that emits light.

  Self-luminous electroluminescent elements are used in display devices. In particular, the organic electroluminescence element has a laminated structure in which an anode, an electroluminescence layer, and a cathode are laminated in this order. When a forward bias voltage is applied between the anode and the cathode, light is emitted from the electroluminescence layer. An electroluminescence display panel that displays images by arranging such organic electroluminescence elements as pixels in a matrix on a substrate and causing each organic electroluminescence element to emit light at a predetermined gradation luminance is realized. .

In the electroluminescence display panel, it is necessary to pattern at least one of the anode and the cathode. At this time, since the cathode is selected from a material having a low work function for electron injection, it is difficult to use the cathode because it is oxidized by the etchant in photolithography. For this reason, in the case of patterning the cathode, vapor deposition was performed using a metal mask, but it cannot be formed with high definition.
Also, as a method of performing the light emitting region other than the patterning of the cathode, a light emitting layer incident on the slit of the mask is lost by irradiating ultraviolet rays after placing a mask on the light emitting layer formed on the substrate. Some patterning is performed on an area shielded by a mask (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 4-255692

  However, since the patterning of the ultraviolet rays is performed using a mask other than photolithography, it cannot be patterned with high definition.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to pattern high-definition pixels when manufacturing a display panel using electroluminescence.

  In order to solve the above problems, an electroluminescent display panel manufacturing method of the present invention includes an electroluminescent layer forming step of forming an electroluminescent layer on a lower electrode formed on a substrate, and the electroluminescent layer. An upper electrode film forming step for forming an upper electrode on the upper electrode and an ion doping step for doping ions in a predetermined pattern with respect to the upper electrode are included.

  As described above, the conductivity of the portion of the upper electrode doped with ions is lowered, and the conductivity of the portion not doped with ions is maintained. Therefore, the electroluminescence layer emits light in a region that overlaps with a portion doped with ions, and does not emit light in a region that overlaps with a portion not doped with ions. Therefore, the upper electrode can be patterned for each pixel.

  Preferably, as the substrate, a transparent substrate covered with a plurality of color filters arranged in a two-dimensional array is used, and as the lower electrode, a transparent electrode covering the whole of the plurality of color filters is used, In the ion doping process, ions are doped into the upper electrode in a pattern corresponding to each of the color filters of the plurality of colors.

Since the substrate and the lower electrode are transparent, and the color filter is formed between the substrate and the lower electrode, the light emitted from the electroluminescence layer passes through the lower electrode, the color filter and the substrate, and is opposite to the substrate. Emanates from.
Here, the electroluminescence layer does not emit light in the region overlapping the ion-doped portion, emits light in the region overlapping the non-ion-doped portion, and has a pattern corresponding to each of the color filters with respect to the upper electrode. Therefore, it is possible to provide an electroluminescence display panel in which a color filter is arranged for each pixel.
Moreover, since the lower electrode and the electroluminescence layer are not patterned for each pixel, the electroluminescence display panel can be manufactured in a short time and easily.

  Preferably, the method further includes a conductive protective film forming step of forming a conductive protective film on the upper electrode between the upper electrode film forming step and the ion doping step. Along with the upper electrode, the conductive protective film is doped with ions in a predetermined pattern.

  As described above, by forming a conductive protective film on the upper electrode, the upper electrode can be protected even if the upper electrode is easily deteriorated.

  Preferably, in the ion doping step, a plurality of masks are arranged on the upper electrode so as to be spaced apart, and ions are doped into the upper electrode through the plurality of masks.

  As described above, since the portion of the upper electrode that overlaps the mask is not doped with ions, the conductivity is maintained, and the portion of the upper electrode that does not overlap with the mask is doped with ions, so that the conductivity is reduced. descend. Therefore, the upper electrode can be patterned for each pixel.

  Preferably, the plurality of masks are arranged in a grid pattern.

  As described above, an electroluminescence display panel in which pixels are arranged in a grid can be manufactured by arranging the masks in a grid.

  According to the present invention, the upper electrode can be patterned for each pixel without using an etchant by partially doping the upper electrode with ions. Since the upper electrode is patterned without using the etchant, the pixel can be patterned with high definition without damaging the portion of the upper electrode that is not doped with ions by the etchant.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, although various technically preferable limitations for implementing the present invention are given to the embodiments described below, the scope of the invention is not limited to the following embodiments and illustrated examples.

  FIGS. 1-7 shows in order each process of the electroluminescent display panel in embodiment to which this invention is applied. 1 to 7 are cross-sectional views along a plane orthogonal to the transparent substrate 2.

  First, as shown in FIG. 1, an insulating transparent substrate 2 is prepared. The transparent substrate 2 is formed in a plate shape or a sheet shape with a transparent material such as borosilicate glass, quartz glass, other glass, PMMA (polymethyl methacrylate), polycarbonate, and other resins.

  On one surface of the transparent substrate 2, a red color filter 3R, a green color filter 3G, and a blue color filter 3B are patterned in a two-dimensional array. For example, when the transparent substrate 2 is viewed in plan, color filters of the same color are arranged in a row in the vertical direction of the transparent substrate 2, and the color filters are repeated in the order of red, green, and blue in the horizontal direction of the transparent substrate 2. Are arranged in a row, and the color filters 3R, 3G, and 3B are patterned in a lattice shape as a whole. The color filters 3R, 3G, 3B may be patterned in a delta arrangement or a stripe arrangement. Further, a black mask may be provided between the color filters 3R, 3G, 3B corresponding to adjacent pixels.

  Next, as shown in FIG. 2, the lower electrode 4 is formed on the entire surface of the color filters 3R, 3G, and 3B through a protective film (not shown) by the PVD method, the CVD method, the sputtering method, and other vapor deposition methods. The entire color filters 3R, 3G, and 3B are covered with a lower electrode 4 made of a transparent metal oxide. Specifically, from indium oxide, zinc oxide or tin oxide or a mixture containing at least one of these (eg, tin-doped indium oxide (ITO), zinc-doped indium oxide, cadmium-tin oxide (CTO)). This film is formed as the lower electrode 4. Here, the lower electrode 4 is an electrode common to all the pixels, and functions as an anode.

  Next, as shown in FIG. 3, an electroluminescence layer 5 made of a white light emitting material that is an organic compound is formed on the entire surface of the lower electrode 4. Here, when the organic compound of the electroluminescent layer 5 is a low molecular organic compound, the electroluminescent layer 5 is formed by vapor deposition, and when the organic compound of the electroluminescent layer 5 is a high molecular organic compound. The electroluminescence layer 5 is formed by a wet coating method (for example, spin coating method, dip coating method, die coating method, ink jet method (droplet discharge method)). In addition, the electroluminescent layer 5 has a laminated structure (for example, a hole transport layer, a narrowly-defined light emitting layer, a three-layer structure serving as an electron transport layer in order from the lower electrode 4, a hole transport layer, and a narrowly defined light-emitting layer sequentially from the lower electrode 4 In the case of forming the two-layer structure, the electroluminescent layer 5 is formed by sequentially forming each layer. For example, the electroluminescence layer 5 is laminated in the order of a hole injection layer made of PEDOT (polythiophene) which is a conductive polymer and PSS (polystyrene sulfonic acid) which is a dopant, and a light emitting layer in a narrow sense made of a polyfluorene-based light emitting material. In the case of forming a two-layer structure, a hole transport layer is formed by coating an organic solution containing PEDOT and PSS on the lower electrode 4, and then an organic solution containing a polyfluorene-based luminescent material. Is applied on the hole transport layer to form a light-emitting layer in a narrow sense. The spin coating method, the dip coating method, and the die coating method can form the electroluminescent layer 5 in a shorter time than the ink jet method, and the spin coating method can be applied to the transparent substrate 2 that is larger than the vapor deposition method. The electroluminescence layer 5 can be formed.

  Next, as shown in FIG. 4, an upper electrode 6 made of a material having a low work function is formed on the entire surface of the electroluminescence layer 5 by PVD, CVD, sputtering, or other vapor deposition methods. . Specifically, it is formed of a metal made of magnesium, calcium, lithium, barium or rare earth, or an alloy containing at least one of these metals. Here, the upper electrode 6 functions as a cathode. As described above, after the electroluminescence layer 5 is formed, the upper electrode 6 is formed without etching the electroluminescence layer 5 by the photolithography method, so that the electroluminescence layer 5 does not deteriorate.

  Next, as shown in FIG. 5, a conductive protective film 7 made of a conductive polymer such as polyacetylene, polypyrrole, polythiophene, polyphenylene vinylene, etc. A film is formed on the entire surface of the electrode 6. As described above, after the upper electrode 6 is formed, the conductive protective film 7 is formed without etching the upper electrode 6 by photolithography, so that the upper electrode 6 is not damaged.

  Next, as shown in FIG. 6, a plurality of resist masks arranged apart from each other by applying a photosensitive resin on the conductive protective film 7 and exposing and developing the applied photosensitive resin (photoresist method). 8 forms the photosensitive resin. In particular, the applied photosensitive resin is exposed and developed so that the plurality of resist masks 8 are arranged in a state corresponding to the color filters 3R, 3G, and 3B. In the case where the color filters 3R, 3G, 3B are arranged in a grid pattern, the resist mask 8 is arranged in a grid pattern, and an opening between the resist masks 8 corresponding to the boundary between the color filters 3R, 3G, 3B. 8a is formed in a mesh shape. Thus, when forming the resist mask 8, since the conductive protective film 7 is formed, deterioration of the upper electrode 6 can be suppressed.

  Next, the conductive protective film 7 is doped with ions while the conductive protective film 7 is masked with the resist mask 8. Since the conductive protective film 7 is masked by the resist mask 8, the region 7a (the region exposed in the opening 8a) of the conductive protective film 7 that is not covered with the resist mask 8 is altered by the doped ions. High resistance. On the other hand, since the region 7b covered with the resist mask 8 in the conductive protective film 7 is not doped with ions, the conductivity is maintained. Further, the ions diffuse to the upper electrode 6, and the region 6 a of the upper electrode 6 that does not overlap with the resist mask 8 in plan view is altered by the ions to deteriorate the electron injectability, and the resist mask 8 in plan view. The region 6b that overlaps maintains the electron injection property.

  As described above, by dividing the upper electrode 6 into the region 6a and the region 6b by the ion doping method, the region 6b maintains the function as a cathode, but the region 6a does not function as a cathode. 6 can be divided for each pixel. The conductive protective film 7 is also divided into a region 7a and a region 7b by ion doping, and the region 7b maintains conductivity, but the region 7a has a high resistance.

  Further, instead of doping the conductive protective film 7 with ions, a laser such as an excimer laser may be used. That is, the conductive protective film 7 is not covered with the resist mask 8 by irradiating the conductive protective film 7 and the upper electrode 6 with laser while the conductive protective film 7 is masked with the resist mask 8. The region 7a is melted, and the region 6a of the upper electrode 6 that does not overlap the resist mask 8 in plan view is melted. By melting the region 6a and the region 7a, the conductive protective film 7 and the upper electrode 6 are cut and divided for each pixel.

  It should be noted that the resist mask 8 may be formed directly on the upper electrode 6 without forming the conductive protective film 7 whether ion doping or laser irradiation is performed. In a state where the upper electrode 6 is masked with the resist mask 8, the upper electrode 6 can be divided into the region 6a and the region 6b by ion doping or laser irradiation.

After the upper electrode 6 is separated by ion doping or laser irradiation, the resist mask 8 is removed with a removing liquid, and the surface of the conductive protective film 7 (or the upper electrode 6) is washed with a cleaning liquid (for example, water). When the conductive protective film 7 is formed, the upper electrode 6 can be protected from the removal liquid or the cleaning liquid.
As described above, the electroluminescence element array substrate 1 is completed.

  On the other hand, as shown in FIG. 7, a transistor array substrate 10 is prepared. The transistor array substrate 10 is formed on the substrate 13 so as to be twisted with respect to the substrate 13, the plurality of signal lines formed on the substrate 13, and the signal lines in plan view. And a plurality of thin film transistors 11 that are formed for each pixel and are switched by inputting signals from the scan lines and the signal lines, and are connected to the thin film transistor 11 for each pixel and exposed. It consists of a plurality of contact electrodes 12 formed. Here, the contact electrodes 12 are arranged so as to correspond to the region 6 b of the upper electrode 6 (region 7 b of the conductive protective film 7). If the region 6b of the upper electrode 6 is formed in a grid pattern, the contact electrodes 12 are arranged in a grid pattern.

Then, the conductive spacer 14 is dispersed on the conductive protective film 7 or the contact electrode 12. Next, of the both surfaces of the transistor array substrate 10, the surface on which the contact electrode 12 is exposed is directed to the transparent substrate 2, the conductive protective film 7 of the electroluminescence element array substrate 1 is directed to the transistor array substrate 10, and the conductive spacer 14 is sandwiched between the electroluminescence element array substrate 1 and the transistor array substrate 10. Here, the transistor array substrate 10 and the electroluminescence element array substrate 1 are positioned so that one contact electrode 12 overlaps one region 6b (one region 7b), and the contact electrode 12 and the conductive spacer 14 are opposed to each other. The contact electrode 12 is made to conduct to the region 7b by the conductive spacer 14 in contact with the region 7b. As described above, a load acts on the conductive protective film 7 when the conductive spacer 14 is sandwiched. When the conductive protective film 7 is deformed, the conductive protective film 7 functions as a buffer material, and the upper electrode 6 And a large load does not act on the electroluminescence layer 5.
Instead of applying the conductive spacer 14, a conductive projection may be formed on the contact electrode 12, and the contact electrode 12 and the region 7b may be made conductive by the projection.

  Then, the periphery of the transistor array substrate 10 and the electroluminescence element array substrate 1 is sealed. Thus, the electroluminescence display panel is completed.

  In the electroluminescence display panel manufactured as described above, the conductivity of the region 6a of the upper electrode 6 is lowered, and the electron injection property of the region 6a is lost. Therefore, the electroluminescence layer 5 emits light at the portion overlapping the region 6b. However, no light is emitted in the portion overlapping the region 6a. The light emitted from the electroluminescence layer 5 passes through the lower electrode 4, the color filters 3 R, 3 G, 3 B and the transparent substrate 2 and is emitted from the back surface of the transparent substrate 2.

  In the manufacturing method of this embodiment, since the electroluminescent layer 5 is formed on the entire surface, the number of processes is reduced as compared with the case where the electroluminescent layer is patterned for each pixel, and the electroluminescent layer 5 is easily formed. can do. Furthermore, since the electroluminescence layer 5 is not patterned, the electroluminescence layer 5 is not deteriorated by a resist, a resist removing solution, a residual resist washing solution, or the like.

  In addition, the upper electrode 6 is divided into a region 6a having a low conductivity and a region 6b having a high conductivity by irradiating the upper electrode 6 with ions or irradiating the upper electrode 6 with a laser. The damage to the region 6b of the upper electrode 6 can be suppressed as compared with the case where the upper electrode 6 is patterned by, for example.

  Further, since the ion doping method or the laser irradiation method is used, the upper electrode 6 is divided into the region 6a having low conductivity and the region 6b having high conductivity even when the conductive protective film 7 is formed on the upper electrode 6. can do. Since the conductive protective film 7 is thus formed on the upper electrode 6, the upper electrode 6 can be protected from the resist mask 8, the resist mask 8 removal liquid, and the resist mask 8 cleaning liquid.

The present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.
For example, in the above embodiment, the upper electrode 6 is a cathode and the lower electrode 4 is an anode, but the upper electrode 6 may be an anode made of a high work function material and the lower electrode 4 may be a cathode made of a low work function material. good.

  Moreover, although the organic compound was used as the electroluminescent layer 5, you may form the electroluminescent layer 5 into a film by vapor-depositing an inorganic compound. In the case where the electroluminescent layer 5 is an inorganic compound, an insulating film such as silicon oxide or silicon nitride is formed on the entire surface of the lower electrode 4 before the electroluminescent layer 5 is formed, and the electroluminescent layer 5 is formed. After the film formation, an insulating film is further formed on the electroluminescence layer 5. Thereafter, as in the case of the above-described embodiment, the upper electrode 6 and the conductive protective film 7 are formed in this order, and the upper electrode 6 is doped with ions or irradiated with a laser while the resist mask 8 is formed. Then, the conductive protective film 7 is patterned.

It is sectional drawing for demonstrating one process at the time of manufacturing an electroluminescent display panel. FIG. 2 is a cross-sectional view for explaining a step subsequent to FIG. 1. FIG. 3 is a cross-sectional view for explaining a step subsequent to FIG. 2. FIG. 4 is a cross-sectional view for explaining a step subsequent to FIG. 3. FIG. 5 is a cross-sectional view for explaining a step subsequent to FIG. 4. It is sectional drawing for demonstrating the next process of FIG. FIG. 7 is a cross-sectional view for explaining a step subsequent to FIG. 6.

Explanation of symbols

2 Transparent substrate 3R, 3B, 3G Color filter 4 Lower electrode 5 Electroluminescence layer 6 Upper electrode 7 Conductive protective film 8 Resist mask

Claims (5)

An electroluminescence layer forming step of forming an electroluminescence layer on the lower electrode formed on the substrate;
An upper electrode film forming step of forming an upper electrode on the electroluminescence layer;
And an ion doping step of doping ions with a predetermined pattern with respect to the upper electrode.   As the substrate, a transparent substrate covered with a plurality of color filters arranged in a two-dimensional array is used, and as the lower electrode, a transparent electrode covering the entire color filters of the plurality of colors is used, and the ion doping step The method for manufacturing an electroluminescent display panel according to claim 1, wherein ions are doped into the upper electrode in a pattern corresponding to each of the color filters of the plurality of colors. A conductive protective film forming step of forming a conductive protective film on the upper electrode between the upper electrode film forming step and the ion doping step;
3. The method of manufacturing an electroluminescence display panel according to claim 1, wherein, in the ion doping step, ions are doped in a predetermined pattern with respect to the conductive protective film together with the upper electrode.   4. The ion doping process according to claim 1, wherein a plurality of masks are arranged on the upper electrode in a state of being separated from each other, and ions are doped into the upper electrode through the plurality of masks. 5. A method for producing an electroluminescent display panel according to claim 1.   The method of manufacturing an electroluminescent display panel according to claim 4, wherein the plurality of masks are arranged in a grid pattern.

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