Display device and manufacturing method therefor

Abstract

A first electrode (30ar) of a first sub-pixel is disposed by sequentially laminating a first reflection layer (Rr), a first transparent conductive layer (24r), a second transparent conductive layer (25r), and a third transparent conductive layer (26r); a first electrode (30ag) of a second sub-pixel is disposed by sequentially laminating a second reflection layer (Rg), a fourth transparent conductive layer (24g), and a fifth transparent conductive layer (26g); and a first electrode (30ab) of a third sub-pixel is disposed by sequentially laminating a third reflection layer (Rb) and a sixth transparent conductive layer (24b). The first, fourth, and sixth transparent conductive layers (24r, 24g, 24b) are formed of a material having an etching rate lower than that of the second, third, and fifth transparent conductive layers (25r, 26r, 26g).

Description

Display device and manufacturing method thereof

[0001] The present invention relates to a display device and a manufacturing method thereof.

[0002] In recent years, self-luminous organic electroluminescence (EL) display devices using organic electroluminescence (EL) elements have been attracting attention as a display device that can replace liquid crystal display devices. These organic EL display devices include, for example, a base substrate, a thin film transistor (TFT) layer provided on the base substrate, an organic EL element layer provided on the TFT layer and including a plurality of organic EL elements arranged corresponding to a plurality of subpixels, and a sealing film provided on the organic EL element layer. Here, the organic EL element includes, for example, a first electrode provided on the TFT layer, an organic EL layer provided on the first electrode, and a second electrode provided on the organic EL layer.

[0003] For example, Patent Document 1 discloses an organic EL display device having, on one surface of a substrate, a driving element, a reflective layer, an optical path adjustment layer, a transparent first electrode layer, an organic EL layer including a light-emitting layer, and a transparent and reflective second electrode layer, in that order, and the thickness of the optical path adjustment layer varies for each subpixel, and the optical path adjustment layer is a single layer.

[0004] Japanese Patent Application Laid-Open No. 2019-179716

[0005] Incidentally, in self-luminous display devices such as organic EL display devices, a cavity structure has been proposed in which the optical path length is set to match the wavelength of each of the three primary colors, red, green, and blue, to improve light extraction efficiency by the optical resonance effect, as in the above-mentioned Patent Document 1. Here, if the first electrode is configured with a laminated structure in which a metal layer and a transparent conductive layer are laminated in order, and the thickness of the transparent conductive layer is optimized for each color depending on the number of layers, thereby configuring the cavity structure, there is a risk that the surface of the metal layer will become rough when etching the transparent conductive film that becomes the transparent conductive layer, thereby reducing the brightness of the subpixel, and there is room for improvement.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to suppress the roughness of the surface of the metal layer that constitutes the first electrode.

[0007] In order to achieve the above object, a display device according to the present invention includes a base substrate, a thin film transistor layer provided on the base substrate, and a light emitting element layer provided on the thin film transistor layer, in which a plurality of first electrodes, a plurality of light emitting functional layers, and a common second electrode are laminated in this order corresponding to a plurality of sub-pixels constituting a display area, the plurality of sub-pixels having first, second, and third sub-pixels that display colors different from one another, and the first electrode corresponding to the first sub-pixel includes a first reflective layer including a first metal layer, a first transparent conductive layer, and a second the first electrode corresponding to the second sub-pixel is formed by sequentially stacking a second reflective layer including a second metal layer, a fourth transparent conductive layer, and a fifth transparent conductive layer; the first electrode corresponding to the third sub-pixel is formed by sequentially stacking a third reflective layer including a third metal layer, and a sixth transparent conductive layer; and the first transparent conductive layer, the fourth transparent conductive layer, and the sixth transparent conductive layer are formed by sequentially stacking a material having a lower etching rate than the second transparent conductive layer, the third transparent conductive layer, and the fifth transparent conductive layer.

[0008] According to the present invention, it is possible to suppress the roughness of the surface of the metal layer that constitutes the first electrode.

[0009] FIG. 1 is a plan view showing a schematic configuration of an organic EL display device according to a first embodiment of the present invention. FIG. 2 is a plan view showing a schematic configuration of a display region of the organic EL display device according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of the display region of the organic EL display device according to the first embodiment of the present invention. FIG. 4 is a plan view of first electrodes arranged in pixels of the display region of the organic EL display device according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view of first electrodes specifically arranged in pixels of the display region along line V-V in FIG. 4. FIG. 6 is an equivalent circuit diagram of a TFT layer constituting the organic EL display device according to the first embodiment of the present invention. FIG. 7 is a cross-sectional view of an organic EL layer constituting the organic EL display device according to the first embodiment of the present invention. FIG. 8 is a cross-sectional view showing the first half of a first step of a first electrode formation process in a manufacturing method for an organic EL display device according to the first embodiment of the present invention, and corresponds to FIG. 5. FIG. 9 is a cross-sectional view showing the second half of a first electrode formation process in a manufacturing method for an organic EL display device according to the first embodiment of the present invention, and corresponds to FIG. 5. FIG. 10 is a cross-sectional view showing a second step of a first electrode formation process in a manufacturing method for an organic EL display device according to the first embodiment of the present invention, and corresponds to FIG. 5. FIG. 11 is a cross-sectional view showing the first half of the third step of the first electrode formation process in the method for manufacturing an organic EL display device according to the first embodiment of the present invention, and corresponds to FIG. 5 . FIG. 12 is a cross-sectional view showing the second half of the third step of the first electrode formation process in the method for manufacturing an organic EL display device according to the first embodiment of the present invention, and corresponds to FIG. 5 . FIG. 13 is a cross-sectional view showing the first half of the fourth step of the first electrode formation process in the method for manufacturing an organic EL display device according to the first embodiment of the present invention, and corresponds to FIG. 5 . FIG. 14 is a cross-sectional view of a display region of an organic EL display device according to a second embodiment of the present invention. FIG. 15 is a cross-sectional view of a first electrode arranged in a pixel of the display region of an organic EL display device according to the second embodiment of the present invention, and corresponds to FIG. 5 . FIG. 16 is a cross-sectional view showing the first half of the first step of the first electrode formation process in the method for manufacturing an organic EL display device according to the second embodiment of the present invention, and corresponds to FIG. 15 .FIG. 17 is a cross-sectional view showing the second half of the first step of the first electrode formation process in the method for manufacturing an organic EL display device according to the second embodiment of the present invention, and corresponds to FIG. 15 . FIG. 18 is a cross-sectional view showing the first half of the second step of the first electrode formation process in the method for manufacturing an organic EL display device according to the second embodiment of the present invention, and corresponds to FIG. 15 . FIG. 19 is a cross-sectional view showing the second half of the second step of the first electrode formation process in the method for manufacturing an organic EL display device according to the second embodiment of the present invention, and corresponds to FIG. 15 . FIG. 20 is a cross-sectional view showing the third step of the first electrode formation process in the method for manufacturing an organic EL display device according to the second embodiment of the present invention, and corresponds to FIG. 15 . FIG. 21 is a cross-sectional view showing the first half of the fourth step of the first electrode formation process in the method for manufacturing an organic EL display device according to the second embodiment of the present invention, and corresponds to FIG. 15 . FIG. 22 is a cross-sectional view showing the second half of the fourth step of the first electrode formation process in the method for manufacturing an organic EL display device according to the second embodiment of the present invention, and corresponds to FIG. 15 . FIG. 23 is a cross-sectional view showing the first half of the fifth step of the first electrode formation process in the method for manufacturing an organic EL display device according to the second embodiment of the present invention, and corresponds to FIG. 15 .

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0011] First Embodiment FIGS. 1 to 13 illustrate a first embodiment of a display device and a manufacturing method thereof according to the present invention. In the following embodiments, an organic EL display device including an organic EL element layer is exemplified as a display device including a light-emitting element layer. FIG. 1 is a plan view showing a schematic configuration of an organic EL display device 50a according to this embodiment. FIG. 2 is a plan view showing a schematic configuration of a display region D of the organic EL display device 50a. FIG. 3 is a cross-sectional view of the display region D of the organic EL display device 50a. FIG. 4 is a plan view of first electrodes 30a arranged in pixels of the display region D of the organic EL display device 50a. FIG. 5 is a cross-sectional view of first electrodes 30a specifically arranged in pixels of the display region 50a along line V-V in FIG. 4. FIG. 6 is an equivalent circuit diagram of a TFT layer 20 constituting the organic EL display device 50a. FIG. 7 is a cross-sectional view of an organic EL layer 32 constituting the organic EL display device 50a.

[0012] 1, the organic EL display device 50a includes, for example, a rectangular display area D for displaying images, and a frame area F provided in a frame shape around the display area D. Note that, although the present embodiment illustrates a rectangular display area D, this rectangular shape also includes, for example, a substantially rectangular shape with arc-shaped sides, arc-shaped corners, or a shape with a notch in one of the sides.

[0013] 2, a plurality of sub-pixels P are arranged in a matrix in the display region D. Also, in the display region D, for example, a first sub-pixel Pr having a red light-emitting region Lr for displaying red, a second sub-pixel Pg having a green light-emitting region Lg for displaying green, and a third sub-pixel Pb having a blue light-emitting region Lb for displaying blue are provided adjacent to each other, as shown in FIG. 2. Note that in the display region D, one pixel is configured by three adjacent sub-pixels, the first sub-pixel Pr, the second sub-pixel Pg, and the third sub-pixel Pb, each having a red light-emitting region Lr, a green light-emitting region Lg, and a blue light-emitting region Lb, and displaying different colors. Furthermore, Figure 2 schematically shows a pixel array in which first sub-pixels Pr, second sub-pixels Pg, and third sub-pixels Pb (whose first electrodes have the same planar shape and the same size) are arranged in a striped pattern, but the specific first sub-pixels Pr, second sub-pixels Pg, and third sub-pixels Pb have first electrodes 30a (30ar, 30ag, and 30ab, described later) that have different planar shapes and different sizes, and are arranged in a non-striped pattern, as shown in Figure 4.

[0014] A terminal portion T is provided to extend in one direction (X direction in Fig. 1) at the end of the frame region F on the positive side in the Y direction in Fig. 1. Furthermore, as shown in Fig. 1, between the display region D and the terminal portion T, that is, in the frame region F, on the display region D side of the terminal portion T, a folding portion B is provided to extend in one direction (X direction in Fig. 1) that can be folded, for example, 180° (in a U-shape) with the X direction in the drawing as the folding axis.

[0015] As shown in FIG. 3, the organic EL display device 50a includes a resin substrate 10 provided as a base substrate, a TFT layer 20 provided on the resin substrate 10, an organic EL element layer 40a provided as a light-emitting element layer on the TFT layer 20, and a sealing film 45 provided on the organic EL element layer 40a.

[0016] The resin substrate 10 is made of, for example, polyimide resin.

[0017] As shown in FIG. 3 , the TFT layer 20 includes a base coat film 11 provided on a resin substrate 10, a plurality of first TFTs 9 a, a plurality of second TFTs 9 b, and a plurality of capacitors 9 c provided on the base coat film 11, and a planarization film 19 provided on each of the first TFTs 9 a, each of the second TFTs 9 b, and each of the capacitors 9 c. As shown in FIG. 2 , the TFT layer 20 includes a plurality of gate lines 14 g extending parallel to each other in the X direction. As shown in FIG. 2 , the TFT layer 30 includes a plurality of source lines 18 f extending parallel to each other in a direction intersecting (orthogonal to) the gate lines 14 g, i.e., in the Y direction. As shown in FIG. 2 , the TFT layer 30 includes a plurality of power supply lines 18 g extending parallel to each other in the Y direction. As shown in FIG. 2 , each power supply line 18 g is adjacent to each of the source lines 18 f. 6, the TFT layer 20 includes a first TFT 9a, a second TFT 9b, and a capacitor 9c in each subpixel P. In the TFT layer 20, as shown in Fig. 3, a base coat film 11, a semiconductor film that will become a semiconductor layer 12a (described later) and the like, a gate insulating film 13, a second metal film that will become a gate line 14g and the like, a first interlayer insulating film 15, a third metal film that will become an upper conductive layer 16c (described later) and the like, a second interlayer insulating film 17, a fourth metal film that will become a source line 18f, a power line 18g and the like, and a planarization film 19 are stacked in this order on a resin substrate 10.

[0018] The base coat film 11, the gate insulating film 13, the first interlayer insulating film 15, and the second interlayer insulating film 17 are each composed of a single layer or a multilayer film of an inorganic insulating film such as silicon nitride, silicon oxide, or silicon oxynitride.

[0019] 6, the first TFT 9a is electrically connected to the corresponding gate line 14g, source line 18f, and second TFT 9b in each subpixel P. Here, as shown in Fig. 3, the first TFT 9a includes a semiconductor layer 12a provided on a base coat film 11, a gate electrode 14a provided on the semiconductor layer 12a via a gate insulating film 13, and a source electrode 18a and a drain electrode 18b provided on a second interlayer insulating film 17 so as to be spaced apart from each other.

[0020] The semiconductor layer 12a and the semiconductor layer 12b described later are formed of a semiconductor film made of polysilicon such as LTPS (low temperature polysilicon), and include a source region and a drain region that are defined to be spaced apart from each other, and a channel region that is defined between the source region and the drain region.

[0021] The gate electrode 14a is provided so as to overlap the channel region of the semiconductor layer 12a and is configured to control conduction between the source region and the drain region of the semiconductor layer 12a. Here, the gate electrode 14a is formed of a second metal film, similar to the gate line 14g.

[0022] 3, the source electrode 18a and the drain electrode 18b are electrically connected to the source region and the drain region of the semiconductor layer 12a, respectively, through contact holes formed in the gate insulating film 13, the first interlayer insulating film 15, and the second interlayer insulating film 17. Here, the source electrode 18a and the drain electrode 18b are formed of a fourth metal film, similar to the source line 18f and the power supply line 18g.

[0023] 6, the second TFT 9b is electrically connected to the corresponding first TFT 9a, a power supply line 18g, and an organic EL element 35 (described later) in each subpixel P. Here, the second TFT 9b includes a semiconductor layer 12b provided on the base coat film 11, a gate electrode 14b provided on the semiconductor layer 12b via a gate insulating film 13, and a source electrode 18c and a drain electrode 18d provided spaced apart from each other on the second interlayer insulating film 17, as shown in FIG.

[0024] The gate electrode 14b is provided so as to overlap the channel region of the semiconductor layer 12b and is configured to control conduction between the source region and the drain region of the semiconductor layer 12b. The gate electrode 14b is formed of a second metal film, similar to the gate line 14g.

[0025] 3, the source electrode 18c and the drain electrode 18d are electrically connected to the source region and the drain region of the semiconductor layer 12b, respectively, through contact holes formed in the stacked film of the gate insulating film 13, the first interlayer insulating film 15, and the second interlayer insulating film 17. Here, the source electrode 18c and the drain electrode 18d are formed of a fourth metal film, similar to the source line 18f and the power supply line 18g.

[0026] In this embodiment, the semiconductor layers 12a and 12b are formed of a semiconductor film made of polysilicon, but the semiconductor layers 12a and 12b may be formed of a semiconductor film made of an oxide semiconductor such as In-Ga-Zn-O. Furthermore, the TFT layer 20 may have a hybrid structure in which a TFT having a semiconductor layer made of polysilicon and a TFT having a semiconductor layer made of an oxide semiconductor are provided.

[0027] As shown in Fig. 6, the capacitor 9c is electrically connected to the corresponding first TFT 9a and power supply line 18g in each subpixel P. Here, as shown in Fig. 3, the capacitor 9c includes a lower conductive layer 14c formed of a second metal film, an upper conductive layer 16c formed of a third metal film, and a first interlayer insulating film 15 provided between the lower conductive layer 14c and the upper conductive layer 16c. Note that, as shown in Fig. 3, the upper conductive layer 16c is electrically connected to the power supply line 18g via a contact hole formed in the second interlayer insulating film 17.

[0028] The planarization film 19 has a flat surface in the display region D and is made of an organic resin material such as polyimide resin.

[0029] 3, the organic EL element layer 40a includes a plurality of first electrodes 30a, a common edge cover 31, a plurality of organic EL layers 32, and a common second electrode 33, which are stacked in order corresponding to a plurality of subpixels P. Here, in each subpixel P, the first electrode 30a, the organic EL layer 32, and the second electrode 33 constitute an organic EL element 35, as shown in FIG. 3, and in the organic EL element layer 40a, the plurality of organic EL elements 35 provided corresponding to the plurality of subpixels P are arranged in a matrix.

[0030] As shown in FIG. 3 , the first electrode 30 a is electrically connected to the drain electrode 18 d of the second TFT 9 b of each subpixel P through a contact hole formed in the planarization film 19. The first electrode 30 a also has a function of injecting holes (positive holes) into the organic EL layer 32. To improve the efficiency of hole injection into the organic EL layer 32, the first electrode 30 a is preferably formed of a material with a large work function. Here, the first electrode 30 a is formed of a laminated film in which a transparent conductive film such as an indium tin oxide (hereinafter also referred to as “ITO”) film or an indium zinc oxide (hereinafter also referred to as “IZO”) film, a metal film such as a silver film or a silver alloy film, and a transparent conductive film such as an ITO film or an IZO film are sequentially stacked, and has light reflectivity.

[0031] Specifically, as shown in Figures 4 and 5, the first electrode 30a is composed of a first electrode 30ar provided in the first sub-pixel Pr, a first electrode 30ag provided in the second sub-pixel Pg, and a first electrode 30ab provided in the third sub-pixel Pb.

[0032] As shown in Figures 4 and 5, the first electrode 30ar is formed by stacking a first reflective layer Rr, a first transparent conductive layer 24r, a second transparent conductive layer 25r, and a third transparent conductive layer 26r in this order on the planarization film 19 of the TFT layer 20.

[0033] 5, the first reflective layer Rr includes a first metal layer 22r and a tenth transparent conductive layer 21r provided on the TFT layer 20 side of the first metal layer 22r. The first metal layer 22r and a second metal layer 22g and a third metal layer 22b (described later) are formed of a metal film such as a silver film or a silver alloy film. The tenth transparent conductive layer 21r and an eleventh transparent conductive layer 21g and a twelfth transparent conductive layer 21b (described later) are formed of a transparent conductive film such as a crystalline ITO film or an (amorphous) IZO film.

[0034] The first transparent conductive layer 24r and the fourth transparent conductive layer 24g and sixth transparent conductive layer 24b described below are formed of a crystalline transparent conductive film such as a crystalline ITO film.

[0035] The second transparent conductive layer 25r is formed of an amorphous transparent conductive film such as an amorphous ITO film or an IZO film.

[0036] The third transparent conductive layer 26r and a fifth transparent conductive layer 26g, which will be described later, are formed of an amorphous transparent conductive film, such as an amorphous ITO film or an IZO film.

[0037] Here, the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b are formed from materials that have a lower etching rate with respect to oxalic acid than the second transparent conductive layer 25r, the third transparent conductive layer 26r, and the fifth transparent conductive layer 26g.

[0038] 4 and 5, the first electrode 30ag is provided by laminating a second reflective layer Rg, a fourth transparent conductive layer 24g, and a fifth transparent conductive layer 26g in this order on the planarization film 19 of the TFT layer 20. Here, as shown in Fig. 5, the second reflective layer Rg includes a second metal layer 22g and an eleventh transparent conductive layer 21g provided on the TFT layer 20 side of the second metal layer 22g.

[0039] 4 and 5, the first electrode 30ab is provided by laminating a third reflective layer Rb and a sixth transparent conductive layer 24b in this order on the planarization film 19 of the TFT layer 20. Here, as shown in Fig. 5, the third reflective layer Rb includes a third metal layer 22b and a twelfth transparent conductive layer 21b provided on the TFT layer 20 side of the third metal layer 22b.

[0040] 5, in the first electrode 30a, the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b are made of the same material and provided in the same layer, and therefore have the same thickness. Also, in the first electrode 30a, the third transparent conductive layer 26r and the fifth transparent conductive layer 26g are made of the same material and provided in the same layer, and therefore have the same thickness. Therefore, in the first electrode 30a, as shown in FIG. 5, the optical path length can be set for each of the first sub-pixel Pr, the second sub-pixel Pg, and the third sub-pixel Pb depending on the number and thicknesses of the transparent conductive layers above the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, and a cavity structure can be formed that improves light extraction efficiency by the optical resonance effect.

[0041] The edge cover 31 is provided in a grid pattern over the entire display area D, and is provided so as to cover the peripheral edges of the first electrodes 30a (30ar, 30ag, 30ab) as shown in Fig. 3. Here, the edge cover 31 is made of, for example, an organic resin material such as polyimide resin or acrylic resin, or a polysiloxane-based SOG (spin on glass) material.

[0042] 7, the organic EL layer 32 is provided as a light-emitting functional layer, and includes a hole injection layer 1, a hole transport layer 2, a light-emitting layer 3, an electron transport layer 4, and an electron injection layer 5, which are stacked in this order on the first electrode 30a. Note that, although the present embodiment illustrates a configuration in which each of the plurality of light-emitting functional layers is an organic EL layer 32, at least one of the plurality of light-emitting functional layers may be an organic EL layer 32.

[0043] The hole injection layer 1, also called an anode buffer layer, has the function of bringing the energy levels of the first electrode 30a and the organic EL layer 32 closer to each other and improving the efficiency of hole injection from the first electrode 30a to the organic EL layer 32. Examples of materials that form the hole injection layer 1 include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, phenylenediamine derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, and stilbene derivatives.

[0044] The hole transport layer 2 has a function of improving the efficiency of transporting holes from the first electrode 30a to the organic EL layer 32. Examples of materials constituting the hole transport layer 2 include porphyrin derivatives, aromatic tertiary amine compounds, styrylamine derivatives, polyvinylcarbazole, poly-p-phenylenevinylene, polysilane, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amine-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, hydrogenated amorphous silicon, hydrogenated amorphous silicon carbide, zinc sulfide, and zinc selenide.

[0045] The light-emitting layer 3 is a region into which holes and electrons are injected from the first electrode 30 a and the second electrode 33, respectively, and where the holes and electrons recombine when a voltage is applied by the first electrode 30 a and the second electrode 33. Here, the light-emitting layer 3 is made of a material with high luminous efficiency. Examples of materials that can be used to form the light-emitting layer 3 include metal oxinoid compounds [8-hydroxyquinoline metal complexes], naphthalene derivatives, anthracene derivatives, diphenylethylene derivatives, vinylacetone derivatives, triphenylamine derivatives, butadiene derivatives, coumarin derivatives, benzoxazole derivatives, oxadiazole derivatives, oxazole derivatives, benzimidazole derivatives, thiadiazole derivatives, benzothiazole derivatives, styryl derivatives, styrylamine derivatives, bisstyrylbenzene derivatives, trisstyrylbenzene derivatives, perylene derivatives, perinone derivatives, aminopyrene derivatives, pyridine derivatives, rhodamine derivatives, aquidin derivatives, phenoxazone, quinacridone derivatives, rubrene, poly-p-phenylenevinylene, and polysilane.

[0046] The electron transport layer 4 has a function of efficiently transferring electrons to the light-emitting layer 3. Examples of materials constituting the electron transport layer 4 include organic compounds such as oxadiazole derivatives, triazole derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, tetracyanoanthraquinodimethane derivatives, diphenoquinone derivatives, fluorenone derivatives, silole derivatives, and metal oxinoid compounds.

[0047] The electron injection layer 5 has a function of bringing the energy levels of the second electrode 33 and the organic EL layer 32 closer to each other and improving the efficiency of electron injection from the second electrode 33 to the organic EL layer 32, and this function can reduce the driving voltage of the organic EL element 35. The electron injection layer 5 is also called a cathode buffer layer. Here, examples of materials constituting the electron injection layer 5 include lithium fluoride (LiF), magnesium fluoride (MgF ２ ), calcium fluoride (CaF ２ ), strontium fluoride (SrF ２ ), barium fluoride (BaF ２inorganic alkali compounds such as aluminum oxide (Al ２ O ３ ), strontium oxide (SrO), etc.

[0048] 3, the second electrode 33 is provided so as to cover each organic EL layer 32 and the edge cover 31. The second electrode 33 has a function of injecting electrons into the organic EL layer 32. The second electrode 33 is preferably made of a material with a small work function in order to improve the efficiency of injecting electrons into the organic EL layer 32. Here, the second electrode 33 is formed of a transparent conductive film such as an ITO film or an IZO film, and has high light transmittance.

[0049] 3 , the sealing film 45 is provided so as to cover the second electrode 33, and includes a first inorganic sealing film 41, an organic sealing film 42, and a second inorganic sealing film 43 laminated in this order on the second electrode 33, and has the function of protecting the organic EL layer 32 of the organic EL element 35 from moisture, oxygen, etc. Here, the first inorganic sealing film 41 and the second inorganic sealing film 43 are made of inorganic insulating films such as a silicon nitride film, a silicon oxide film, or a silicon oxynitride film. Moreover, the organic sealing film 42 is made of an organic resin material such as an acrylic resin, an epoxy resin, a silicone resin, a polyurea resin, a parylene resin, a polyimide resin, or a polyamide resin.

[0050] The organic EL display device 50a described above is configured such that, in each subpixel P, a gate signal is input to the first TFT 9a via the gate line 14g to turn the first TFT 9a on, a voltage corresponding to the source signal is written to the gate electrode 14b and capacitor 9c of the second TFT 9b via the source line 18f, and a current defined based on the gate voltage of the second TFT 9b is supplied to the organic EL element 35 from the power supply line 18g, causing the light-emitting layer 3 of the organic EL element 35 to emit light, thereby displaying an image. In the organic EL display device 50a, even if the first TFT 9a is turned off, the gate voltage of the second TFT 9b is held by the capacitor 9c, so that light emission by the light-emitting layer 3 is maintained until the gate signal for the next frame is input.

[0051] Next, a method for manufacturing the organic EL display device 50a of this embodiment will be described. The method for manufacturing the organic EL display device 50a of this embodiment includes a TFT layer formation process, an organic EL element layer formation process including a first electrode formation process, and a sealing film formation process. FIGS. 8 and 9 are cross-sectional views illustrating the first and second halves of a first step of the first electrode formation process in the method for manufacturing the organic EL display device 50a, respectively, and correspond to FIG. 5 . FIG. 10 is a cross-sectional view illustrating the second step of the first electrode formation process in the method for manufacturing the organic EL display device 50a, and corresponds to FIG. 5 . FIGS. 11 and 12 are cross-sectional views illustrating the first and second halves of a third step of the first electrode formation process in the method for manufacturing the organic EL display device 50a, and correspond to FIG. 5 . FIG. 13 is a cross-sectional view illustrating the first half of a fourth step of the first electrode formation process in the method for manufacturing the organic EL display device 50a, and corresponds to FIG. 5 .

[0052] <TFT Layer Forming Process> First, for example, a non-photosensitive polyimide resin (about 6 μm thick) is applied onto a glass substrate, and then the applied film is pre-baked and post-baked to form a resin substrate 10 .

[0053] Next, a silicon oxide film (approximately 500 nm thick) and a silicon nitride film (approximately 100 nm thick) are sequentially formed on the surface of the substrate on which the resin substrate 10 is formed, for example, by plasma CVD (chemical vapor deposition) method, thereby forming a base coat film 11.

[0054] Thereafter, an amorphous silicon film (about 50 nm thick) is formed by plasma CVD on the surface of the substrate on which the base coat film 11 has been formed, and the amorphous silicon film is crystallized by laser annealing or the like to form a semiconductor film of polysilicon film, and then the semiconductor film is patterned to form semiconductor layers 12 a and 12 b, etc.

[0055] Furthermore, a silicon oxide film (about 100 nm) or the like is formed by, for example, plasma CVD on the substrate surface on which the semiconductor layer 12a and the like are formed, to form a gate insulating film 13 so as to cover the semiconductor layer 12a and the like.

[0056] Next, a second metal film such as a molybdenum film (about 250 nm thick) is formed on the surface of the substrate on which the gate insulating film 13 has been formed, for example, by sputtering, and then the second metal film is patterned to form the gate line 14g, gate electrodes 14a and 14b, lower conductive layer 14c, etc.

[0057] Thereafter, impurity ions are doped using the gate electrodes 14a and 14b as a mask to make parts of the semiconductor layers 12a and 12b conductive.

[0058] Furthermore, a silicon nitride film (about 100 nm thick) is formed by, for example, plasma CVD on the substrate surface where parts of the semiconductor layer 12a etc. have been made conductive, thereby forming a first interlayer insulating film 15.

[0059] Next, a third metal film such as a molybdenum film (approximately 250 nm thick) is formed on the substrate surface on which the first interlayer insulating film 15 is formed, for example, by sputtering, and then the third metal film is patterned to form the upper conductive layer 16c, etc.

[0060] Thereafter, a silicon oxide film (approximately 300 nm thick) and a silicon nitride film (approximately 200 nm thick) are sequentially formed on the substrate surface on which the upper conductive layer 16c and the like are formed, for example, by plasma CVD, thereby forming a second interlayer insulating film 17.

[0061] Furthermore, the gate insulating film 13, the first interlayer insulating film 15 and the second interlayer insulating film 17 are appropriately patterned to form contact holes.

[0062] Next, a titanium film (thickness: about 50 nm), an aluminum film (thickness: about 600 nm), and a titanium film (thickness: about 50 nm) are sequentially formed by, for example, sputtering on the surface of the substrate on which the contact holes have been formed, to form a fourth metal film, and then the fourth metal film is patterned to form source electrodes 18a and 18c, drain electrodes 18b and 18d, source line 18f, power line 18g, etc.

[0063] Finally, a photosensitive polyimide resin (about 2.5 μm thick) is applied to the substrate surface on which the source electrode 18 a and the like are formed, for example, by spin coating or slit coating, and then the applied film is pre-baked, exposed to light, developed, and post-baked to form a planarization film 19.

[0064] In this manner, the TFT layer 20 can be formed.

[0065] <Organic EL element layer forming process> First, on the surface of the substrate on which the TFT layer 20 has been formed in the TFT layer forming process, a fourth transparent conductive film 21 (thickness: about 5 nm) such as an amorphous ITO film, a first metal film 22 (thickness: about 95 nm) such as an Ag film, and a first transparent conductive film 24 (thickness: about 60 nm) such as an amorphous ITO film are formed in this order by, for example, a sputtering method, as shown in FIG. 8 , and then, as shown in FIG. 9 , the stacked film of the fourth transparent conductive film 21, the first metal film 22, and the first transparent conductive film 24 is patterned by wet etching using a mixed solution of phosphoric acid, nitric acid, and acetic acid (first process / first electrode forming process). 8 and 9, in this first step, a tenth transparent conductive layer 21r, an eleventh transparent conductive layer 21g, and a twelfth transparent conductive layer 21b are formed by the fourth transparent conductive film 21, and a first metal layer 22r, a second metal layer 22g, and a third metal layer 22b are formed by the first metal film 22, thereby forming a first reflective layer Rr, a second reflective layer Rg, and a third reflective layer Rb. Furthermore, in the first step, a thirteenth transparent conductive layer 24br, a fourteenth transparent conductive layer 24bg, and a fifteenth transparent conductive layer 24bb are formed by the first transparent conductive film 24, thereby forming the thirteenth transparent conductive layer 24br, the fourteenth transparent conductive layer 24bg, and the fifteenth transparent conductive layer 24bb on the first reflective layer Rr, the second reflective layer Rg, and the third reflective layer Rb, respectively. The first electrode forming step of forming the plurality of first electrodes 30a includes a first step, and a second step, a third step, and a fourth step, which will be described later.

[0066] Next, the substrate on which the 13th transparent conductive layer 24br and the like are formed is baked, for example, at about 220°C, to crystallize the 13th transparent conductive layer 24br, the 14th transparent conductive layer 24bg, and the 15th transparent conductive layer 24bb, thereby forming the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b, as shown in Figure 10 (second process / first electrode formation process).

[0067] Thereafter, on the surface of the substrate on which the first transparent conductive layer 24r and the like have been formed, an amorphous second transparent conductive film 25 (with a thickness of approximately 60 nm) such as an IZO film is formed, for example, by a sputtering method, so as to cover the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b, as shown in FIG. 11, and then the second transparent conductive film 25 is patterned by wet etching with oxalic acid to form a second transparent conductive layer 25r as shown in FIG. 12 (third process / first electrode formation process). Here, in this third step, the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b formed on the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, respectively, are formed from crystalline ITO films that are difficult to etch with oxalic acid, so that the surfaces (top surfaces in the figure) of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b are prevented from being exposed to oxalic acid, and roughness of the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b can be prevented.

[0068] Furthermore, on the surface of the substrate on which the second transparent conductive layer 25r has been formed, an amorphous third transparent conductive film 26 (with a thickness of about 60 nm) such as an IZO film is formed by, for example, a sputtering method so as to cover the second transparent conductive layer 25r, as shown in FIG. 13 , and then the third transparent conductive film 26 is patterned by wet etching with oxalic acid to form the third transparent conductive layer 26r and the fifth transparent conductive layer 26g as shown in FIG. 5 , thereby forming the first electrodes 30a (30ar, 30ag, 30ab) (fourth step / first electrode formation step). Here, even in this fourth step, the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b formed on the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, respectively, are formed of crystalline ITO films that are difficult to etch with oxalic acid, so that the surfaces (top surfaces in the figure) of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b are prevented from being exposed to oxalic acid, and roughening of the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b can be prevented.

[0069] Next, an acrylic photosensitive resin film (approximately 2.5 μm thick) is applied to the substrate surface on which the first electrode 30a is formed, for example, by spin coating or slit coating, and then the applied film is pre-baked, exposed to light, developed, and post-baked to form the edge cover 31 (edge ​​cover formation process).

[0070] Furthermore, on the surface of the substrate on which the edge cover 31 is formed, a hole injection layer 1, a hole transport layer 2, a light-emitting layer 3, an electron transport layer 4, and an electron injection layer 5 are sequentially formed by, for example, a vacuum deposition method, each having a thickness of about several tens of nanometers to 50 nanometers, to form an organic EL layer 32 (organic EL layer formation process).

[0071] Finally, a transparent conductive film such as an ITO film (thickness: about 100 nm) is formed by sputtering using a mask on the surface of the substrate on which the organic EL layer 32 is formed, to form a second electrode 33 (second electrode formation process).

[0072] In this manner, the organic EL element layer 40a can be formed.

[0073] <Sealing film forming process> Using a film formation mask, an inorganic insulating film such as a silicon nitride film, a silicon oxide film, or a silicon oxynitride film is formed by plasma CVD on the organic EL element layer 40a formed in the organic EL element layer forming process so as to cover each organic EL element 35, thereby forming a first inorganic sealing film 41.

[0074] Subsequently, an organic resin material such as an acrylic resin is deposited on the first inorganic sealing film 41 by, for example, an inkjet method to form the organic sealing film 42 .

[0075] Then, using a film formation mask, an inorganic insulating film such as a silicon nitride film, a silicon oxide film, or a silicon oxynitride film is formed by plasma CVD to cover the organic sealing film 42, thereby forming a second inorganic sealing film 43, thereby forming a sealing film 45.

[0076] Finally, a protective sheet (not shown) is attached to the surface of the substrate on which the sealing film 45 is formed, and then laser light is irradiated from the glass substrate side of the resin substrate 10 to peel the glass substrate from the underside of the resin substrate 10, and further a protective sheet (not shown) is attached to the underside of the resin substrate 10 from which the glass substrate has been peeled.

[0077] In this manner, the organic EL display device 50a of this embodiment can be manufactured.

[0078] As described above, according to the organic EL display device 50a and its manufacturing method of this embodiment, the first electrode 30ar corresponding to the first subpixel Pr that displays red is provided by sequentially stacking a first reflective layer Rr including a tenth transparent conductive layer 21r and a first metal layer 22r, a first transparent conductive layer 24r, a second transparent conductive layer 25r, and a third transparent conductive layer 26r. The first electrode 30ag corresponding to the second subpixel Pg that displays green is provided by sequentially stacking a second reflective layer Rg including an eleventh transparent conductive layer 21g and a second metal layer 22g, a fourth transparent conductive layer 24g, and a fifth transparent conductive layer 26g. The first electrode 30ab corresponding to the third subpixel Pb that displays blue is provided by sequentially stacking a third reflective layer Rb including a twelfth transparent conductive layer 21b and a third metal layer 22b, and a sixth transparent conductive layer 24b. Here, the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b are formed of a crystalline transparent conductive film that is difficult to etch with oxalic acid, and are formed of a material with a lower etching rate than the second transparent conductive layer 25r, the third transparent conductive layer 26r, and the fifth transparent conductive layer 26g, which are made of an amorphous transparent conductive film that is easily etched with oxalic acid. Therefore, in the third and fourth steps of the first electrode formation process in which the first electrodes 30ar, 30ag, and 30ab are formed, the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b formed on the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b are difficult to etch with oxalic acid, and therefore, exposure of the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b to oxalic acid can be suppressed. This can suppress roughness of the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, which constitute the first electrode 30a (30ar, 30ag, 30ab), and can also suppress roughness of the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b. Furthermore, this can suppress roughness of the surfaces of the light-reflective first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, which constitute the first electrode 30a (30ar, 30ag, 30ab), and can also suppress a decrease in the luminance of each subpixel (first subpixel Pr, second subpixel Pg, third subpixel Pb).

[0079] Furthermore, according to the organic EL display device 50a and its manufacturing method of this embodiment, in the first step of the first electrode formation process, the fourth transparent conductive film 21, the first metal film 22, and the first transparent conductive film 24 are formed in this order on the TFT layer 20, and then the fourth transparent conductive film 21, the first metal film 22, and the first transparent conductive film 24 are patterned. In this patterning, the fourth transparent conductive film 21 forms the tenth transparent conductive layer 21r, the eleventh transparent conductive layer 21g, and the twelfth transparent conductive layer 21b, and the first metal film 22 forms the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, thereby forming the first reflective layer Rr, the second reflective layer Rg, and the third reflective layer Rb. Furthermore, in this patterning, a thirteenth transparent conductive layer 24br, a fourteenth transparent conductive layer 24bg, and a fifteenth transparent conductive layer 24bb, which become the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b, are formed on the first reflective layer Rr, the second reflective layer Rg, and the third reflective layer Rb, respectively, by the first transparent conductive film 24. This makes it possible to form the first reflective layer Rr, the second reflective layer Rg, the third reflective layer Rb, the thirteenth transparent conductive layer 24br, the fourteenth transparent conductive layer 24bg, and the fifteenth transparent conductive layer 24bb by a single photolithography process, thereby reducing manufacturing costs and forming the first electrode 30a having a cavity structure.

[0080] Second Embodiment Figures 14 to 23 show a second embodiment of a display device and a manufacturing method thereof according to the present invention. Here, Figure 14 is a cross-sectional view of a display region D of an organic EL display device 50b of this embodiment. Also, Figure 15 is a cross-sectional view of a first electrode 30b arranged in a pixel of the display region D of the organic EL display device 50b, and corresponds to Figure 5 described in the first embodiment. Note that in the following embodiments, parts that are the same as those in Figures 1 to 13 are assigned the same reference numerals, and detailed descriptions thereof will be omitted.

[0081] In the first embodiment described above, an organic EL display device 50a is exemplified in which the side surfaces of the first reflective layer Rr, the second reflective layer Rg, and the third reflective layer Rb are exposed from the first transparent conductive layer 24r, the fourth transparent conductive layer 24g, and the sixth transparent conductive layer 24b. However, in the present embodiment, an organic EL display device 50b is exemplified in which the side surfaces of the first reflective layer Rr, the second reflective layer Rg, and the third reflective layer Rb are covered with the first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b.

[0082] The organic EL display device 50b, like the organic EL display device 50a of the first embodiment described above, includes, for example, a rectangular display area D for displaying images, and a frame area F arranged in a frame shape around the display area D.

[0083] As shown in FIG. 14, the organic EL display device 50b includes a resin substrate 10 provided as a base substrate, a TFT layer 20 provided on the resin substrate 10, an organic EL element layer 40b provided as a light-emitting element layer on the TFT layer 20, and a sealing film 45 provided on the organic EL element layer 40b.

[0084] 14, the organic EL element layer 40b includes a plurality of first electrodes 30b, a common edge cover 31, a plurality of organic EL layers 32, and a common second electrode 33, which are stacked in order corresponding to a plurality of subpixels P. Here, in each subpixel P, the first electrode 30b, the organic EL layer 32, and the second electrode 33 constitute an organic EL element 35, as shown in Fig. 14, and in the organic EL element layer 40b, the plurality of organic EL elements 35 provided corresponding to the plurality of subpixels P are arranged in a matrix.

[0085] As shown in FIG. 14 , the first electrode 30b is electrically connected to the drain electrode 18d of the second TFT 9b of each subpixel P through a contact hole formed in the planarization film 19. The first electrode 30b also has a function of injecting holes (positive holes) into the organic EL layer 32. In order to improve the efficiency of hole injection into the organic EL layer 32, the first electrode 30b is preferably formed from a material with a large work function. Here, the first electrode 30b is formed from a laminated film in which, for example, a transparent conductive film such as an ITO film or an IZO film, a metal film such as a silver film or a silver alloy film, and a transparent conductive film such as an ITO film or an IZO film are laminated in this order, and has light reflectivity.

[0086] Specifically, as shown in FIG. 15, the first electrode 30b is composed of a first electrode 30br provided in the first sub-pixel Pr, a first electrode 30bg provided in the second sub-pixel Pg, and a first electrode 30bb provided in the third sub-pixel Pb.

[0087] As shown in Figure 15, the first electrode 30br is formed by stacking a first reflective layer Rr, a first transparent conductive layer 27r, a second transparent conductive layer 28r, and a third transparent conductive layer 29r in this order on the planarization film 19 of the TFT layer 20.

[0088] 15, the first reflective layer Rr includes a first metal layer 22r, a tenth transparent conductive layer 21r provided on the TFT layer 20 side of the first metal layer 22r, and a seventh transparent conductive layer 23r provided on the first metal layer 22r. Here, the seventh transparent conductive layer 23r and an eighth transparent conductive layer 23g and a ninth transparent conductive layer 23b, which will be described later, are formed of a transparent conductive film such as a crystalline ITO film or an (amorphous) IZO film.

[0089] 15, the first transparent conductive layer 27r is provided so as to cover the surface (top surface in the drawing) and both side surfaces of the first reflective layer Rr. Here, the first transparent conductive layer 27r and a fourth transparent conductive layer 27g and a sixth transparent conductive layer 27b, which will be described later, are formed of a crystalline transparent conductive film, such as a crystalline ITO film.

[0090] The second transparent conductive layer 28r is formed of an amorphous transparent conductive film such as an amorphous ITO film or an IZO film.

[0091] The third transparent conductive layer 29r and a fifth transparent conductive layer 29g, which will be described later, are formed of an amorphous transparent conductive film, such as an amorphous ITO film or an IZO film.

[0092] Here, the first transparent conductive layer 27r, the fourth transparent conductive layer 27g and the sixth transparent conductive layer 27b are formed from materials that have a lower etching rate with oxalic acid than the second transparent conductive layer 28r, the third transparent conductive layer 29r and the fifth transparent conductive layer 29g.

[0093] 15, the first electrode 30bg is provided by sequentially stacking a second reflective layer Rg, a fourth transparent conductive layer 27g, and a fifth transparent conductive layer 29g on the planarization film 19 of the TFT layer 20. Here, as shown in FIG. 5, the second reflective layer Rg includes a second metal layer 22g, an eleventh transparent conductive layer 21g provided on the TFT layer 20 side of the second metal layer 22g, and an eighth transparent conductive layer 23g provided on the second metal layer 22g. Furthermore, as shown in FIG. 15, the fourth transparent conductive layer 27g is provided so as to cover the surface (top surface in the drawing) and both side surfaces of the second reflective layer Rg.

[0094] 15, the first electrode 30bb is provided by sequentially stacking a third reflective layer Rb and a sixth transparent conductive layer 27b on the planarization film 19 of the TFT layer 20. Here, as shown in Fig. 15, the third reflective layer Rb includes a third metal layer 22b, a twelfth transparent conductive layer 21b provided on the TFT layer 20 side of the third metal layer 22b, and a ninth transparent conductive layer 23b provided on the third metal layer 22b. Furthermore, as shown in Fig. 15, the sixth transparent conductive layer 27b is provided so as to cover the surface (top surface in the figure) and both side surfaces of the third reflective layer Rb.

[0095] 15 , in the first electrode 30b, the first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b are made of the same material and provided in the same layer, and therefore have the same thickness. Also, in the first electrode 30b, the third transparent conductive layer 29r and the fifth transparent conductive layer 29g are made of the same material and provided in the same layer, and therefore have the same thickness. Therefore, in the first electrode 30b, as shown in FIG. 15 , the optical path length can be set for each of the first sub-pixel Pr, the second sub-pixel Pg, and the third sub-pixel Pb depending on the number and thicknesses of the transparent conductive layers above the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, and a cavity structure can be formed that improves light extraction efficiency by the optical resonance effect.

[0096] The organic EL display device 50b described above is flexible, similar to the organic EL display device 50a of the first embodiment, and is configured to display an image by appropriately causing the light-emitting layer 3 of the organic EL element 35 to emit light in each sub-pixel P via the first TFT 9a and the second TFT 9b.

[0097] Next, a manufacturing method for the organic EL display device 50b of this embodiment will be described. The manufacturing method for the organic EL display device 50b of this embodiment includes a TFT layer formation process, an organic EL element layer formation process including a first electrode formation process, and a sealing film formation process. However, the TFT layer formation process and the sealing film formation process are substantially the same as those of the manufacturing method of the first embodiment, so the following description will focus on the organic EL element layer formation process. FIGS. 16 and 17 are cross-sectional views illustrating the first and second halves of the first step of the first electrode formation process in the manufacturing method for the organic EL display device 50b, respectively, and correspond to FIG. 15 . FIGS. 18 and 19 are cross-sectional views illustrating the first and second halves of the second step of the first electrode formation process in the manufacturing method for the organic EL display device 50b, respectively, and correspond to FIG. 15 . FIG. 20 is a cross-sectional view illustrating the third step of the first electrode formation process in the manufacturing method for the organic EL display device 50b, and corresponds to FIG. 15 . 21 and 22 are cross-sectional views showing the first and second halves, respectively, of the fourth step of the first electrode formation step in the manufacturing method of the organic EL display device 50b, and correspond to Fig. 15. Fig. 23 is a cross-sectional view showing the first half of the fifth step of the first electrode formation step in the manufacturing method of the organic EL display device 50b, and corresponds to Fig. 15.

[0098] <Organic EL element layer forming process> First, on the surface of the substrate on which the TFT layer 20 has been formed in the TFT layer forming process of the first embodiment, a fourth transparent conductive film 21 (thickness: about 5 nm) such as an amorphous ITO film, a first metal film 22 (thickness: about 95 nm) such as an Ag film, and a fifth transparent conductive film 23 (thickness: about 5 nm) such as an amorphous ITO film are formed in this order by, for example, a sputtering method, as shown in FIG. 16 , and then, as shown in FIG. 17 , the stacked film of the fourth transparent conductive film 21, the first metal film 22, and the fifth transparent conductive film 23 is patterned by wet etching with a mixed solution of phosphoric acid, nitric acid, and acetic acid (first process / first electrode forming process). 16 and 17 , in this first step, a tenth transparent conductive layer 21r, an eleventh transparent conductive layer 21g, and a twelfth transparent conductive layer 21b are formed by the fourth transparent conductive film 21, a first metal layer 22r, a second metal layer 22g, and a third metal layer 22b are formed by the first metal film 22, and a seventh transparent conductive layer 23r, an eighth transparent conductive layer 23g, and a ninth transparent conductive layer 23b are formed by the fifth transparent conductive film 23, thereby forming a first reflective layer Rr, a second reflective layer Rg, and a third reflective layer Rb. Note that the first electrode formation step of forming a plurality of first electrodes 30b includes a first step, and a second, third, fourth, and fifth steps, which will be described later.

[0099] Next, on the substrate surface on which the first reflective layer Rr and the like have been formed, a first transparent conductive film 27 (about 60 nm thick) such as an amorphous ITO film is formed by, for example, sputtering, as shown in Fig. 18, and then the first transparent conductive film 27 is patterned by wet etching with oxalic acid to form a thirteenth transparent conductive layer 27br, a fourteenth transparent conductive layer 27bg, and a fifteenth transparent conductive layer 27bb (second step / first electrode formation step), as shown in Fig. 19. Here, in this second step, the thirteenth transparent conductive layer 27br, the fourteenth transparent conductive layer 27bg, and the fifteenth transparent conductive layer 27bb are formed so as to cover the surfaces (top surfaces in the figure) and both side surfaces of the first reflective layer Rr, the second reflective layer Rg, and the third reflective layer Rb, respectively, as shown in Fig. 19.

[0100] Thereafter, the substrate on which the thirteenth transparent conductive layer 27br, the fourteenth transparent conductive layer 27bg, and the fifteenth transparent conductive layer 27bb have been formed is baked, for example, at about 220°C, thereby crystallizing the thirteenth transparent conductive layer 27br, the fourteenth transparent conductive layer 27bg, and the fifteenth transparent conductive layer 27bb, and forming the first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b, as shown in Figure 20 (third process / first electrode formation process).

[0101] Furthermore, on the surface of the substrate on which the first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b have been formed, an amorphous second transparent conductive film 28 (with a thickness of approximately 60 nm) such as an IZO film is formed, for example, by a sputtering method, so as to cover the first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b, as shown in FIG. 21 , and then the second transparent conductive film 28 is patterned by wet etching with oxalic acid to form a second transparent conductive layer 28r as shown in FIG. 22 (fourth process / first electrode formation process). Here, in this fourth step, the first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b, which are formed on the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, respectively, via the seventh transparent conductive layer 23r, the eighth transparent conductive layer 23g, and the ninth transparent conductive layer 23b, are formed of a crystalline ITO film that is difficult to etch with oxalic acid. Therefore, the surfaces (top surfaces in the figure) and both side surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b are prevented from being exposed to oxalic acid, and roughness of the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b can be further prevented.

[0102] Next, on the surface of the substrate on which the second transparent conductive layer 28r has been formed, an amorphous third transparent conductive film 29 (with a thickness of approximately 60 nm) such as an IZO film is formed by, for example, a sputtering method so as to cover the second transparent conductive layer 28r, as shown in FIG. 23 , and then the third transparent conductive film 29 is patterned by wet etching with oxalic acid to form the third transparent conductive layer 29r and the fifth transparent conductive layer 29g as shown in FIG. 15 , thereby forming first electrodes 30b (30br, 30bg, 30bb) (fifth step / first electrode formation step). Here, even in this fifth step, the first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b, which are formed on the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, respectively, via the seventh transparent conductive layer 23r, the eighth transparent conductive layer 23g, and the ninth transparent conductive layer 23b, are formed of a crystalline ITO film that is difficult to etch with oxalic acid. Therefore, the surfaces (top surfaces in the figure) and both side surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b are prevented from being exposed to oxalic acid, and roughening of the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b can be further prevented.

[0103] Then, an acrylic photosensitive resin film (approximately 2.5 μm thick) is applied to the substrate surface on which the first electrode 30b is formed, for example, by spin coating or slit coating, and the applied film is then pre-baked, exposed to light, developed, and post-baked to form the edge cover 31 (edge ​​cover formation process).

[0104] Furthermore, on the surface of the substrate on which the edge cover 31 is formed, a hole injection layer 1, a hole transport layer 2, a light-emitting layer 3, an electron transport layer 4, and an electron injection layer 5 are sequentially formed by, for example, a vacuum deposition method, each having a thickness of about several tens of nanometers to 50 nanometers, to form an organic EL layer 32 (organic EL layer formation process).

[0105] Finally, a transparent conductive film such as an ITO film (thickness: about 100 nm) is formed by sputtering using a mask on the surface of the substrate on which the organic EL layer 32 is formed, to form a second electrode 33 (second electrode formation process).

[0106] In this manner, the organic EL element layer 40b can be formed.

[0107] Thereafter, the sealing film forming step of the first embodiment is carried out, whereby the organic EL display device 50b of this embodiment can be manufactured.

[0108] As described above, according to the organic EL display device 50b and the manufacturing method thereof of this embodiment, the first electrode 30br corresponding to the first sub-pixel Pr that displays red is provided by sequentially stacking the first reflective layer Rr, which is formed by sequentially stacking the tenth transparent conductive layer 21r, the first metal layer 22r, and the seventh transparent conductive layer 23r, the first transparent conductive layer 27r, the second transparent conductive layer 28r, and the third transparent conductive layer 29r. Also, the first electrode 30bg corresponding to the second sub-pixel Pg that displays green is provided by sequentially stacking the second reflective layer Rg, which is formed by sequentially stacking the eleventh transparent conductive layer 21g, the second metal layer 22g, and the eighth transparent conductive layer 23g, the fourth transparent conductive layer 27g, and the fifth transparent conductive layer 29g. The first electrode 30bb corresponding to the third sub-pixel Pb that displays blue is provided by sequentially stacking a third reflective layer Rb, which is formed by sequentially stacking a twelfth transparent conductive layer 21b, a third metal layer 22b, and a ninth transparent conductive layer 23b, and a sixth transparent conductive layer 27b. The first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b are formed of a crystalline transparent conductive film that is difficult to etch with oxalic acid, and are formed of a material with a lower etching rate than the second transparent conductive layer 28r, the third transparent conductive layer 29r, and the fifth transparent conductive layer 29g, which are formed of an amorphous transparent conductive film that is easily etched with oxalic acid. Therefore, in the fourth and fifth steps of the first electrode formation process for forming the first electrodes 30br, 30bg, and 30bb, the first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b formed on the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, respectively, via the seventh transparent conductive layer 23r, the eighth transparent conductive layer 23g, and the ninth transparent conductive layer 23b, are difficult to etch with oxalic acid, thereby preventing the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b from being exposed to oxalic acid. This prevents the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b from becoming rough, thereby preventing the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b constituting the first electrode 30b (30br, 30bg, 30bb) from becoming rough.Furthermore, since it is possible to suppress roughness of the surfaces of the light-reflective first metal layer 22r, second metal layer 22g, and third metal layer 22b that constitute the first electrode 30b (30br, 30bg, 30bb), it is possible to suppress a decrease in the brightness of each subpixel (first subpixel Pr, second subpixel Pg, third subpixel Pb).

[0109] Furthermore, according to the organic EL display device 50b of this embodiment and its manufacturing method, the first transparent conductive layer 27r, the fourth transparent conductive layer 27g, and the sixth transparent conductive layer 27b are arranged so as to cover the side surfaces of the first reflective layer Rr, the second reflective layer Rg, and the third reflective layer Rb, respectively, and therefore roughness of the surfaces of the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b that constitute the first reflective layer Rr, the second reflective layer Rg, and the third reflective layer Rb can be further suppressed.

[0110] Furthermore, according to the organic EL display device 50b of this embodiment and its manufacturing method, the first reflective layer Rr is formed by sequentially stacking the tenth transparent conductive layer 21r, the first metal layer 22r, and the seventh transparent conductive layer 23r, the second reflective layer Rg is formed by sequentially stacking the eleventh transparent conductive layer 21g, the second metal layer 22g, and the eighth transparent conductive layer 23g, and the third reflective layer Rb is formed by sequentially stacking the twelfth transparent conductive layer 21b, the third metal layer 22b, and the ninth transparent conductive layer 23b. This shortens the exposure time during the manufacturing process of the first metal film 22, such as an Ag film constituting the first metal layer 22r, the second metal layer 22g, and the third metal layer 22b, and thus makes it possible to suppress surface oxidation of the first metal film 22, thereby suppressing a decrease in light reflectance and an increase in electrical resistance. Other Embodiments In the above-described embodiments, an organic EL layer having a five-layer stacked structure of a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer has been exemplified, but the organic EL layer may also have a three-layer stacked structure of, for example, a hole injection layer / hole transport layer, a light-emitting layer, and an electron transport layer / electron injection layer.

[0111] In addition, in each of the above embodiments, an organic EL display device in which the first electrode is an anode and the second electrode is a cathode is exemplified. However, the present invention can also be applied to an organic EL display device in which the stacked structure of the organic EL layer is reversed, and the first electrode is a cathode and the second electrode is an anode.

[0112] Furthermore, in each of the above embodiments, an organic EL display device is exemplified in which the electrode of the TFT connected to the first electrode is used as the drain electrode, but the present invention can also be applied to an organic EL display device in which the electrode of the TFT connected to the first electrode is called the source electrode.

[0113] Furthermore, in each of the above embodiments, an organic EL display device has been described as an example of a display device. However, the present invention can be applied to a display device including a plurality of light-emitting elements driven by current, and can be applied to, for example, a display device including QLEDs (Quantum-dot light emitting diodes), which are light-emitting elements using a quantum dot-containing layer.

[0114] As described above, the present invention is useful for flexible display devices.

[0115] D Display area P Subpixel Pr First subpixel Pg Second subpixel Pb Third subpixel Rr First reflective layer Rg Second reflective layer Rb Third reflective layer 10 Resin substrate (base substrate) 20 TFT layer (thin film transistor layer) 21r Tenth transparent conductive layer 21g Eleventh transparent conductive layer 21b Twelfth transparent conductive layer 22 First metal film 22r First metal layer 22g Second metal layer 22b Third metal layer 23r Seventh transparent conductive layer 23g Eighth transparent conductive layer 23b Ninth transparent conductive layer 24, 27 First transparent conductive film 24r, 27r First transparent conductive layer 24br, 27br Thirteenth transparent conductive layer 24g, 27g Fourth transparent conductive layer 24bg, 27bg Fourteenth transparent conductive layer 24b, 27b Sixth transparent conductive layer 24bb, 27bb Fifteenth transparent conductive layer 25, 28 Second transparent conductive film 25r, 28r Second transparent conductive layer 25g, 28g Fifth transparent conductive layer 26, 29 Third transparent conductive film 26r, 29r Third transparent conductive layer 30a, 30ar, 30ab, 30ag First electrode 30b, 30br, 30bg, 30bb First electrode 32 Organic EL layer (organic electroluminescence layer, light-emitting function layer) 33 Second electrode 40a, 40b Organic EL element layer (light-emitting element layer) 45 Sealing film 50a, 50b Organic EL display device

Claims

1. A display device comprising: a base substrate; a thin film transistor layer provided on the base substrate; and a light emitting element layer provided on the thin film transistor layer, the light emitting element layer including a plurality of first electrodes, a plurality of light emitting functional layers, and a common second electrode laminated in this order corresponding to a plurality of subpixels constituting a display area, the plurality of subpixels having first, second, and third subpixels that display different colors from one another, wherein the first electrode corresponding to the first subpixel is provided by sequentially laminating a first reflective layer including a first metal layer, a first transparent conductive layer, a second transparent conductive layer, and a third transparent conductive layer, the first electrode corresponding to the second subpixel is provided by sequentially laminating a second reflective layer including a second metal layer, a fourth transparent conductive layer, and a fifth transparent conductive layer, the first electrode corresponding to the third subpixel is provided by sequentially laminating a third reflective layer including a third metal layer, and a sixth transparent conductive layer, A display device characterized in that the first transparent conductive layer, the fourth transparent conductive layer, and the sixth transparent conductive layer are formed from a material having a lower etching rate than the second transparent conductive layer, the third transparent conductive layer, and the fifth transparent conductive layer.

2. A display device according to claim 1, wherein the first transparent conductive layer, the fourth transparent conductive layer and the sixth transparent conductive layer are formed from a crystalline transparent conductive film, and the second transparent conductive layer, the third transparent conductive layer and the fifth transparent conductive layer are formed from an amorphous transparent conductive film.

3. A display device according to claim 2, wherein the crystalline transparent conductive film is formed from crystalline indium tin oxide, and the amorphous transparent conductive film is formed from indium zinc oxide or amorphous indium tin oxide.

4. A display device according to any one of claims 1 to 3, characterized in that the first transparent conductive layer, the fourth transparent conductive layer and the sixth transparent conductive layer are provided so as to cover the respective side surfaces of the first reflective layer, the second reflective layer and the third reflective layer.

5. A display device according to any one of claims 1 to 4, characterized in that the first reflective layer includes a seventh transparent conductive layer provided on the first metal layer, the second reflective layer includes an eighth transparent conductive layer provided on the second metal layer, and the third reflective layer includes a ninth transparent conductive layer provided on the third metal layer.

6. A display device according to claim 5, wherein the first reflective layer includes a tenth transparent conductive layer provided on the thin film transistor layer side of the first metal layer, the second reflective layer includes an eleventh transparent conductive layer provided on the thin film transistor layer side of the second metal layer, and the third reflective layer includes a twelfth transparent conductive layer provided on the thin film transistor layer side of the third metal layer.

7. The display device according to any one of claims 1 to 6, further comprising a sealing film provided on the light emitting element layer.

8. The display device according to any one of claims 1 to 7, wherein at least one of the plurality of light-emitting functional layers is an organic electroluminescence layer.

9. A method for manufacturing a display device according to any one of claims 1 to 8, wherein the first electrode forming step of forming the plurality of first electrodes comprises: a first step of sequentially forming a first metal film and an amorphous first transparent conductive film on the thin film transistor layer, and then patterning the first metal film and the first transparent conductive film to form the first metal layer, the second metal layer, and the third metal layer from the first metal film, thereby forming the first reflective layer, the second reflective layer, and the third reflective layer, and also forming a thirteenth transparent conductive layer, a fourteenth transparent conductive layer, and a fifteenth transparent conductive layer from the first transparent conductive film, which will become the first transparent conductive layer, the fourth transparent conductive layer, and the sixth transparent conductive layer; and a second step of crystallizing the thirteenth transparent conductive layer, the fourteenth transparent conductive layer, and the fifteenth transparent conductive layer formed in the first step by baking to form the first transparent conductive layer, the fourth transparent conductive layer, and the sixth transparent conductive layer. a third step of forming an amorphous second transparent conductive film so as to cover the first transparent conductive layer, the fourth transparent conductive layer, and the sixth transparent conductive layer formed in the second step, and then patterning the second transparent conductive film to form the second transparent conductive layer; and a fourth step of forming an amorphous third transparent conductive film so as to cover the second transparent conductive layer formed in the third step, and then patterning the third transparent conductive film to form the third transparent conductive layer and the fifth transparent conductive layer.

10. A method for manufacturing a display device according to any one of claims 1 to 8, wherein the first electrode forming step of forming the plurality of first electrodes comprises: a first step of forming a first metal film on the thin film transistor layer, and then patterning the first metal film to form the first metal layer, the second metal layer, and the third metal layer, thereby forming the first reflective layer, the second reflective layer, and the third reflective layer; and a second step of forming an amorphous first transparent conductive film so as to cover the first reflective layer, the second reflective layer, and the third reflective layer formed in the first step, and then patterning the first transparent conductive film to form a thirteenth transparent conductive layer, a fourteenth transparent conductive layer, and a fifteenth transparent conductive layer, which will become the first transparent conductive layer, the fourth transparent conductive layer, and the sixth transparent conductive layer, from the first transparent conductive film. a third step of forming the first transparent conductive layer, the fourth transparent conductive layer, and the sixth transparent conductive layer by crystallizing the thirteenth transparent conductive layer, the fourteenth transparent conductive layer, and the fifteenth transparent conductive layer formed in the second step by firing; a fourth step of forming an amorphous second transparent conductive film so as to cover the first transparent conductive layer, the fourth transparent conductive layer, and the sixth transparent conductive layer formed in the third step, and then patterning the second transparent conductive film to form the second transparent conductive layer; and a fifth step of forming an amorphous third transparent conductive film so as to cover the second transparent conductive layer formed in the third step, and then patterning the third transparent conductive film to form the third transparent conductive layer and the fifth transparent conductive layer.

11. A method for manufacturing a display device according to claim 10, characterized in that in the second step, the thirteenth transparent conductive layer, the fourteenth transparent conductive layer and the fifteenth transparent conductive layer are formed so as to cover the side surfaces of the first reflective layer, the second reflective layer and the third reflective layer, respectively.

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