13. Such a conductive oxide layer can be formed of, for example, a transparent conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), or indium gallium zinc oxide (IGZO).

The upper electrodes UE1, UE2, and UE3 are formed of, for example, a metal material such as an alloy (MgAg) of magnesium and silver. For example, the lower electrodes LE1, LE2, and LE3 correspond to anodes, and the upper electrodes UE1, UE2, and UE3 correspond to cathodes.

The cap layers CP1, CP2, and CP3 have refractive indices different from the upper electrodes UE1, UE2, and UE3 and the sealing layers SE1, SE2, and SE3. The cap layers CP1, CP2 and CP3 can be constituted by, for example, a multilayer body of a plurality of transparent thin films. As the thin films, the multilayer body may include a thin film formed of an inorganic material and a thin film formed of an organic material. In addition, the plurality of thin films have refractive indices different from each other. The materials of the thin films constituting the multilayer body are different from the materials of the upper electrodes UE1, UE2 and UE3 and are also different from the materials of the sealing layers SE1, SE2 and SE3. Incidentally, the cap layers CP1, CP2, and CP3 may be omitted.

The lower portion 61 of the partition 6 is formed of, for example, aluminum (Al). The lower portion 61 may be formed of an aluminum alloy such as aluminum-neodymium (AlNd) or may have a multilayer structure of an aluminum layer and an aluminum alloy layer. Furthermore, the lower portion 61 may include a thin film formed of a metallic material different from aluminum and an aluminum alloy, under the aluminum layer or the aluminum alloy layer. Such a thin layer can be formed of, for example, molybdenum (Mo).

The upper portion 62 of the partition 6 has, for example, a multilayer structure of a thin film formed of a metal material such as titanium (Ti) and a thin film formed of a conductive material such as ITO. The upper portion 62 may have a single-layer structure of a metal material such as titanium.

A common voltage is supplied to the partition 6. This common voltage is supplied to each of the upper electrodes UE1, UE2, and UE3 that are in contact with the side surfaces of the lower portion 61. A pixel voltage is supplied to the lower electrodes LE1, LE2, and LE3 through the pixel circuits 1 included in the respective sub-pixels SP1, SP2, and SP3.

FIG. 4 is a view showing an example of a layer structure applicable to the organic layers OR1, OR2, and OR3. Each of the organic layers OR1, OR2, and OR3 has a structure in which, for example, a hole-injection layer HIL, a hole-transport layer HTL, an electron blocking layer EBL, a light emitting layer EML, a hole blocking layer HBL, an electron-transport layer ETL, and an electron-injection layer EIL are stacked in this order in the third direction Z. The organic layers OR1, OR2, and OR3 may have a so-called tandem structure including a plurality of light emitting layers EML.

When a potential difference is formed between the lower electrode LE1 and the upper electrode UE1, the light emitting layer EML of the organic layer OR1 emits light of the blue wavelength range. When a potential difference is formed between the lower electrode LE2 and the upper electrode UE2, the light emitting layer EML of the organic layer OR2 emits light of the green wavelength range. When a potential difference is formed between the lower electrode LE3 and the upper electrode UE3, the light emitting layer EML of the organic layer OR3 emits light of the red wavelength range.

The thickness of the organic layers OR1, OR2, and OR3 is desirably adjusted in accordance with the wavelength of the light emitted from the light emitting layer EML, from the viewpoint of improving the light outcoupling efficiency of the display elements DE1, DE2, and DE3. In the example shown in FIG. 3, a thickness T1 of the organic layer OR1, a thickness T2 of the organic layer OR2, and a thickness T3 of the organic layer OR3 are different from each other. More specifically, the thickness T2 is greater than the thickness T1, and the thickness T3 is greater than the thickness T2 (T1<T2<T3). The difference among the thicknesses T1, T2, and T3 is caused by, for example, the difference in thickness among the hole-transport layers HTL in the respective organic layers OR1, OR2, and OR3, but is not limited to this example.

FIG. 5 is an expanded cross-sectional view schematically showing the partition 6 arranged between the sub-pixels SP1 and SP3 and a vicinity of the partition 6. The first rib layer 51 has a pair of side surfaces SF1. A width of the first rib layer 51 is smaller than a width of the second rib layer 52. The second rib layer 52 thereby protrudes from each of the side surfaces SF1 in a width direction (first direction X or second direction Y) of the rib 5 and the partition 6. A gap G is formed between the portion of the second rib layer 52, which protrudes from the side surface SF1, and the inorganic insulating layer 13.

The lower portion 61 has a pair of side surfaces SF2. A width of the upper portion 62 is larger than a width of the lower portion 61. In addition, the width of the second rib layer 52 is also larger than the width of the lower portion 61. The upper portion 62 and the second rib layer 52 thereby protrude from each of the side surfaces SF2 in the width direction.

The lower electrode LE1 includes an end portion EP having a thickness reduced toward the first rib layer 51. In the example shown in FIG. 5, a part of the end portion EP is located in the gap GP. The end portion EP may be in contact with or separated from the side surface SF1 of the first rib layer 51. Alternatively, the end portion EP may be entirely located outside the gap G.

The organic layer OR1 includes a first layer L1 covering the lower electrode LE1 and a second layer L2 covering the first layer L1. At least the hole-injection layer HIL of each layer shown in FIG. 4 is included in the first layer L1, and the layers which are not included in the first layer L1 are included in the second layer L2. As an example, the first layer L1 is constituted by the hole-injection layer HIL, and the second layer L2 is constituted by the hole-transport layer HTL, the electron blocking layer EBL, the light emitting layer EML, the hole blocking layer HBL, the electron-transport layer ETL, and the electron-injection layer EIL.

For example, the organic layer OR1 fills the gap G. In the example shown in FIG. 5, parts of the first layer L1 and the second layer L2 fill the gap G. As another example, a gap which is not filled with the lower electrode LE1, the first layer L1, or the second layer L2 may be formed inside the gap G.

In the example shown in FIG. 5, parts of the lower electrode LE1 and the first layer L1 are located on the second rib layer 52. These parts are separated from parts located on the inorganic insulating layer 13, of the lower electrode LE1 and the first layer L1 (i.e., parts constituting the display element DE1).

For example, the second layer L2 covers the lower electrode LE1 and the first layer L1 located on the second rib layer 52 without being interrupted by the gap G. The second layer L2 may be in contact with or separated from the side surface SF2 as shown in FIG. 5.

The upper electrode UE1 entirely covers the second layer L2 of the organic layer OR1 without being interrupted in the vicinity of the gap G. Furthermore, the upper electrode UE1 is in contact with the side surface SF2.

The cap layer CP1 includes a high refractive index layer HR covering the upper electrode UE1 and a low refractive index layer LR covering the high refractive index layer HR. The low refractive index layer LR has a refractive index smaller than the high refractive index layer HR. The high refractive index layer HR and the low refractive index layer LR are examples of a plurality of transparent thin films constituting the above-described multilayer body. The cap layer CP1 may include more thin films.

Similarly to the end portion EP of the lower electrode LE1, the thickness of the organic layer OR1 may be reduced toward the side surfaces SF1 and SF2, and the thicknesses of the upper electrode UE1 and the cap layer CP1 may be reduced toward the side surface SF2.

An area which is not covered with the upper electrode UE1, of the side surface SF2 facing the sub-pixel SP1, is covered with the sealing layer SE1. The sealing layer SE1 also continuously covers a lower surface of the upper portion 62, and the stacked layer body of the lower electrode LE1, the organic layer OR1, the upper electrode UE1, and the cap layer CP1, which is arranged on the upper portion 62.

If the lower electrode LE1 is brought into contact with the lower portion 61, the lower electrode LE1 becomes electrically conductive with the upper electrode UE1, and the light emitting layer EML of the organic layer OR1 does not emit light. The lower electrode LE1 therefore needs to be separated from the lower portion 61. Then, a thickness Ta of the first rib layer 51 (i.e., the height of the gap G) is desirably larger than a thickness Tb of the lower electrode LE1 (Ta>Tb). Thus, the lower electrode LE1 can hardly surmount the gap G, and can suppress a short circuit between the lower electrode LE1 and the lower portion 61. As an example, the thickness Ta is 150 nm, and the thickness Tb is 100 nm. A depth of the gap G, i.e., a length of the protrusion of the second rib layer 52 from the side surface SF1 is equivalent to, for example, the thickness Ta.

When the hole-injection layer HIL of the organic layer OR1 is brought into contact with the lower portion 61, an undesired current leakage path can easily be formed. For this reason, the hole-injection layer HIL of the organic layer OR1 also needs to be separated from the lower portion 61. Then, the thickness Ta is desirably larger than a total thickness Tc of the lower electrode LE1 and the hole-injection layer HIL (Ta>Tc). A short circuit between the hole-injection layer HIL and the lower portion 61 can also be thereby suppressed desirably.

In contrast, the upper electrode UE1 needs to be in contact with the lower portion 61. Thus, the thickness Ta is desirably smaller than a total thickness Td of the lower electrode LE1 and the organic layer OR1 (Ta<Td). The gap G can easily be thereby filled with the organic layer OR1. If the gap G is filled with the organic layer OR1, the upper electrode UE1 on the organic layer OR1 is brought into contact with the side surface SF2 without being interrupted by the gap G.

Incidentally, each of the thicknesses Tb, Tc, and Td is, for example, an average thickness measured based on parts excluding a vicinity of an end portion whose thickness is reduced, of the lower electrode LE1 and the organic layer OR1.

The configuration of the lower electrode LE3, the organic layer OR3, the upper electrode UE3, the cap layer CP3, and the sealing layer SE3 shown in FIG. 5 is the same as the configuration of the lower electrode LE1, the organic layer OR1, the upper electrode UE1, the cap layer CP1, and the sealing layer SE1. In addition, the configuration of the lower electrode LE2, the organic layer OR2, the upper electrode UE2, the cap layer CP2, and the sealing layer SE2 is also the same as the configuration of the lower electrode LE1, the organic layer OR1, the upper electrode UE1, the cap layer CP1, and the sealing layer SE1. For example, the thickness of each of the lower electrodes LE2 and LE3 is the same as the thickness Tb of the lower electrode LE1.

FIG. 6 is a schematic cross-sectional view showing another structure that can be applied to the partition 6 and its vicinity. In the above-described example shown in FIG. 5, the width of the second rib layer 52 is larger than the width of the upper portion 62. In contrast, in the example shown in FIG. 6, the width of the second rib layer 52 is smaller than the width of the upper portion 62.

As described later, the lower electrode LE1 is formed by vapor deposition. In this deposition process, part of the deposition material released from a deposition source toward a vicinity of a proximal part of the lower portion 61 is blocked by the upper portion 62, and the end portions EP having a thickness reduced toward the first rib layer 51 are formed. As shown in the example of FIG. 6, the thickness of the end portion EP in the vicinity of the gap G is reduced as the width of the upper portion 62 is made larger. Therefore, a short circuit between the lower electrode LE1 and the lower portion 61 can be suppressed more reliably. The lower electrodes LE2 and LE3 are constituted in the same manner.

In the example shown in FIG. 6, the thickness Ta may be smaller than or equal to the thickness Tb or the thickness Tc. More specifically, when the thickness Tb is 100 nm, the thickness Ta can be set to approximately 75 nm. Even in this case, if the thicknesses of the lower electrodes LE1, LE2, and LE3 are sufficiently reduced below the upper portion 62, the lower electrodes LE1, LE2, and LE3 are separated by the gap G. Therefore, a short circuit between the lower electrodes LE1, LE2, and LE3 and the lower portion 61 can be prevented.

Next, a method of manufacturing the display device DSP will be described.

FIG. 7 is a flowchart showing an example of a method of manufacturing the display device DSP. Each of FIG. 8 to FIG. 23 is a schematic cross-sectional view showing parts of the manufacturing process of the display device DSP. In FIG. 8 to FIG. 23, the substrate 10 and the circuit layer 11 are omitted.

In manufacturing the display device DSP, the circuit layer 11 and the organic insulating layer 12 are first formed on the substrate 10 (process P1). Furthermore, as shown in FIG. 8, the inorganic insulating layer 13 is formed on the organic insulating layer 12 (process P2).

After process P2, the rib 5 and the partition 6 are formed on the inorganic insulating layer 13 (process P3). More specifically, as shown in FIG. 9, a first thin film 51a of an inorganic insulating material which is to be the first rib layer 51 is first formed on the inorganic insulating layer 13 by Chemical Vapor Deposition (CVD). Furthermore, as shown in FIG. 10, a second thin film 52a of an inorganic insulating material which is to be the second rib layer 52 is formed on the first thin film 51a by CVD.

Next, as shown in FIG. 11, a metal layer 61a which is to be the lower portion 61 is formed on the second thin film 52a, and a thin film 62a which is to be the upper portion 62 is formed on the metal layer 61a. Furthermore, a resist R1 corresponding to the shape of the partition 6 is formed on the thin film 62a.

After the formation of the resist R1, a portion of the thin film 62a, which is exposed from the resist R1, is removed by, for example, wet etching as shown in FIG. 12. The upper portion 62 is thereby formed.

Then, anisotropic dry etching is executed to remove the part of the metal layer 61a, which is exposed from the resist R1, as shown in FIG. 13. In the dry etching, the part of the metal layer 61a, which is exposed from the resist R1, may be thinned to remain.

Next, isotropic wet etching is executed such that the width of the metal layer 61a is reduced to be smaller than the width of the upper portion 62 as shown in FIG. 14. Thus, the lower portion 61 having a width smaller than the upper portion 62 is formed, and the partition 6 is completed.

After that, the first thin film 51a and the second thin film 52a are patterned. More specifically, anisotropic dry etching is executed to remove the part of the second thin film 52a, which is exposed from the lower portion 61, as shown in FIG. 15. In the dry etching, since the upper portion 62 acts as a mask, the portion of the second thin film 52a, which is located under the upper portion 62, remains. The second rib layer 52 having a width greater than the lower portion 61 is thereby formed.

Furthermore, isotropic dry etching is executed to remove the part of the first thin film 51a, which is exposed from the second rib layer 52, as shown in FIG. 16. In the dry etching, the width of the first thin film 51a is reduced to be smaller than the width of the second rib layer 52. Thus, the first rib layer 51 having a width smaller than the second rib layer 52 is formed, and the rib 5 is completed. After that, the resist R1 is removed as shown in FIG. 17.

For example, anisotropic dry etching in FIG. 15 and isotropic dry etching in FIG. 16 can be executed in the same chamber. In this case, anisotropic dry etching may be first executed with a high bias power and then isotropic dry etching may be executed by switching the bias power to a low bias power.

To suppress erosion of the inorganic insulating layer 13 and the second rib layer 52 by isotropic dry etching shown in FIG. 16, the inorganic insulating layer 13 and the second rib layer 52 are desirably formed of a material in which an etching rate of the dry etching is slower than the first rib layer 51 (first thin film 51a). For example, when the inorganic insulating layer 13 and the second rib layer 52 are formed of a silicon oxide or a silicon oxynitride and the first rib layer 51 is formed of a silicon nitride as described above, the relationship in etching rate is implemented.

The method of forming the rib 5 and the partition 6 is not limited to that shown in FIG. 8 to FIG. 17. For example, the resist R1 may be removed before executing the dry etching in FIG. 15 and FIG. 16, and a new resist having a plane shape corresponding to the second rib layer 52 may be arranged. If the dry etching in FIG. 15 and FIG. 16 is executed using this resist as a mask, the second rib layer 52 and the first rib layer 51 located under the second rib layer 52 can be formed with a good accuracy.

After process P3, the display element DE1 is formed (process P4). More specifically, as shown in FIG. 18, the lower electrode LE1 is formed on the inorganic insulating layer 13 and the partition 6 by vapor deposition (process P11), the organic layer OR1 is formed on the lower electrode LE1 by vapor deposition (process P12), the upper electrode UE1 is formed on the organic layer OR1 by vapor deposition (process P13), and the cap layer CP1 is formed on the upper electrode UE1 by vapor deposition (process P14). Furthermore, the sealing layer SE1 is formed by CVD (process P15).

Incidentally, process P12 includes a process of sequentially forming the thin films constituting the organic layer OR1, such as the hole-injection layer HIL, the hole-transport layer HTL, the electron blocking layer EBL, the light emitting layer EML, the hole blocking layer HBL, the electron-transport layer ETL, the electron-injection layer EIL, and the like shown in FIG. 4. In addition, process P14 includes a process of sequentially forming the thin films constituting the cap layer CP1, such as the high refractive index layer HR and the low refractive index layer LR shown in FIG. 5.

The lower electrode LE1, the organic layer OR1