Method for manufacturing display device, and display device

Abstract

Provided is a method for manufacturing a microcavity-type display device (101), the method comprising: a first step (S1) for forming a reflective film (6); a second step (S2) for forming a transparent film on a layer above the reflective film (6) and patterning the transparent film to form a transparent electrode unit (2); and a third step (S3) for removing the reflective film (6) exposed from the transparent electrode unit (2) to form a reflective electrode (1).

Description

Display device manufacturing method and display device

[0001] The present disclosure relates to a method for manufacturing a display device and the display device.

[0002] Patent Document 1 discloses a light emitting device including a light reflective layer, a transparent dielectric layer formed on a substrate so as to cover the light reflective layer, and a light emitting element having a transparent pixel electrode.

[0003] Japanese Patent Publication No. 2007-280677

[0004] In the light-emitting device disclosed in Patent Document 1, the pixel electrode has a larger area than the light-reflecting layer, and the light-reflecting layer is covered with a dielectric layer, so the size of the light-reflecting layer is small. Therefore, the light-emitting device disclosed in Patent Document 1 has a problem of low light emission brightness.

[0005] A manufacturing method of a display device according to one aspect of the present disclosure is a manufacturing method of a microcavity type display device, and includes a first step of forming a reflective film, a second step of forming a transparent film above the reflective film and patterning the transparent film to form a transparent electrode portion, and a third step of removing the reflective film exposed from the transparent electrode portion to form a reflective electrode.

[0006] According to one aspect of the present disclosure, a display device that emits light with high luminance can be realized.

[0007] FIG. 1 is a cross-sectional view showing a schematic configuration of a display device according to a first embodiment of the present disclosure. FIG. 2 is an exploded view showing a schematic configuration of a display device according to the first embodiment of the present disclosure. FIG. 3 is a flowchart showing major steps in a manufacturing method of a display device according to the first embodiment of the present disclosure. FIG. 4 is a view explaining a first step. FIG. 5 is a view explaining step S21 according to the first embodiment of the present disclosure. FIG. 6 is a view explaining steps S22 to S24. FIG. 7 is a view explaining steps S25. FIG. 8 is a view explaining steps S26 to S28. FIG. 9 is a view explaining step S29. FIG. 10 is a view explaining step S2a. FIG. 11 is a view explaining steps S2b to step a. FIG. 12 is a cross-sectional view showing a schematic configuration of a plurality of reflective electrodes and a plurality of transparent electrode portions according to a first example of a third embodiment of the present disclosure. FIG. 13 is a schematic view of a reflective electrode, a transparent electrode portion, and a light-emitting layer of an optical function portion according to a second example of the third embodiment of the present disclosure. FIG. 14 is a cross-sectional view showing a schematic configuration of a display device according to a fourth embodiment of the present disclosure. FIG. 15 is a flowchart showing major steps in a manufacturing method of a display device according to the fourth embodiment of the present disclosure. FIG. 16 is a view explaining step S21 according to the fourth embodiment of the present disclosure.

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of the present disclosure. For convenience of explanation, the same reference numerals are used to designate components having the same functions as those previously described, and the description thereof may not be repeated.

[0009] [Embodiment 1] Fig. 1 is a cross-sectional view showing a schematic configuration of a display device 101 according to embodiment 1 of the present disclosure. Fig. 2 is an exploded view showing a schematic configuration of the display device 101 according to embodiment 1 of the present disclosure. The display device 101 is a microcavity type display device. The display device 101 includes a TFT substrate 51, a plurality of reflective electrodes 1, a plurality of transparent electrode portions 2, a plurality of optical function portions 52, and a plurality of counter electrodes 53. TFT is an abbreviation for Thin Film Transistor.

[0010] The display device 101 includes a first sub-pixel 54, a second sub-pixel 55, and a third sub-pixel 56. Each of the first sub-pixel 54, the second sub-pixel 55, and the third sub-pixel 56 has a stacked structure of a reflective electrode 1, a transparent electrode portion 2, an optical function portion 52, and a counter electrode 53.

[0011] The TFT substrate 51 is a substrate having TFTs (not shown) electrically connected to a plurality of reflective electrodes 1 .

[0012] Each of the plurality of reflective electrodes 1 is an electrode that reflects light. Each of the plurality of reflective electrodes 1 may be either an anode or a cathode. An example of the material of each of the plurality of reflective electrodes 1 is silver.

[0013] The thicknesses of the multiple transparent electrode portions 2 may differ from one another. FIG. 1 illustrates the following configuration. The transparent electrode portion 2 of the first sub-pixel 54 is made up of a first transparent electrode layer 3, a second transparent electrode layer 4, and a third transparent electrode layer 5. The transparent electrode portion 2 of the second sub-pixel 55 is made up of the second transparent electrode layer 4 and the third transparent electrode layer 5. The transparent electrode portion 2 of the third sub-pixel 56 is made up of the third transparent electrode layer 5. As a result, the thickness of the transparent electrode portion 2 of the first sub-pixel 54 is greater than the thickness of the transparent electrode portion 2 of the second sub-pixel 55, and the thickness of the transparent electrode portion 2 of the second sub-pixel 55 is greater than the thickness of the transparent electrode portion 2 of the third sub-pixel 56.

[0014] The transparent electrode portion 2 is located in a layer above the reflective electrode 1. The plurality of transparent electrode portions 2 are each located in a layer above the plurality of reflective electrodes 1. In other words, for each reflective electrode 1, one transparent electrode portion 2 is located in a layer above it.

[0015] The plurality of optical function units 52 are each located above the plurality of transparent electrode units 2. Each of the plurality of optical function units 52 includes a light-emitting layer. Examples of the light-emitting layer include an OLED layer and a QLED layer. OLED is an abbreviation for Organic Light Emitting Diode. QLED is an abbreviation for Quantum Light Emitting Diode. Each of the plurality of optical function units 52 may include at least one of a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer.

[0016] The plurality of counter electrodes 53 are each located above the plurality of optical function units 52. Each of the plurality of counter electrodes 53 is a transparent or semi-transparent electrode. Each of the plurality of counter electrodes 53 may be the other of an anode and a cathode. An example of the material of each of the plurality of counter electrodes 53 is an alloy of silver and magnesium.

[0017] In each of the first sub-pixel 54 , the second sub-pixel 55 , and the third sub-pixel 56 , light can be emitted by the light-emitting layer of the optical function section 52 when a current flows between the reflective electrode 1 and the counter electrode 53 .

[0018] 3 is a flowchart showing main steps in a method for manufacturing the display device 101 according to the first embodiment of the present disclosure. The method for manufacturing the display device 101 includes a first step S1, a second step S2, and a third step S3.

[0019] 4 is a diagram illustrating the first step S1. The first step S1 is a step of forming a reflective film 6. The second step S2 is a step of forming a transparent film above the reflective film 6 and patterning the transparent film to form the transparent electrode portion 2. The third step S3 is a step of removing the reflective film 6 exposed from the transparent electrode portion 2 to form the reflective electrode 1.

[0020] According to the manufacturing method of the display device 101, the transparent electrode portion 2 does not need to have a larger area than the reflective electrode 1, and further, the transparent electrode portion 2 does not need to cover the reflective electrode 1, so it is possible to increase the size of the reflective electrode 1. Therefore, according to the manufacturing method of the display device 101, it is possible to realize a display device 101 that emits light with high brightness.

[0021] In the second step S2, a plurality of transparent electrode portions 2 may be formed, and in the third step S3, a plurality of reflective electrodes 1 may be formed below each of the plurality of transparent electrode portions 2. In the second step S2, the plurality of transparent electrode portions 2 may be formed to have different thicknesses.

[0022] Fig. 5 is a diagram illustrating step S21 according to the first embodiment of the present disclosure. Fig. 6 is a diagram illustrating steps S22 to S24. Fig. 7 is a diagram illustrating step S25. Fig. 8 is a diagram illustrating steps S26 to S28. Fig. 9 is a diagram illustrating step S29. Fig. 10 is a diagram illustrating step S2a. Fig. 11 is a diagram illustrating steps S2b to the a-th step Sa. The second step S2 may include steps S21 to S2b.

[0023] Step S21 is a process of forming a first transparent film 7 above the reflective film 6. At least one first transparent electrode layer 3 included in the plurality of transparent electrode portions 2 is formed by photolithography in step S22, etching in step S23, and peeling and cleaning in step S24. In steps S22 to S24, at least one portion of the first transparent film 7 is left, and the rest is removed.

[0024] Step S25 is a process of forming a second transparent film 8 above the reflective film 6, including on at least one first transparent electrode layer 3. At least two second transparent electrode layers 4 included in the plurality of transparent electrode portions 2 are formed by photolithography in step S26, etching in step S27, and peeling and cleaning in step S28. In steps S26 to S28, at least two locations on the second transparent film 8, including on at least one first transparent electrode layer 3, are left, and the rest are removed. In other words, the portion of the second transparent film 8 located on the first transparent electrode layer 3 is left, and a portion of the other portions is left, while the rest is removed.

[0025] Step S29 is a process of forming a third transparent film 9 above the reflective film 6, including above at least two second transparent electrode layers 4. At least three third transparent electrode layers 5 included in the plurality of transparent electrode portions 2 are formed by photolithography in step S2a and etching the third transparent film 9 in step S2b. In steps S2a and S2b, at least three locations on the third transparent film 9, including locations above at least two second transparent electrode layers 4, are left, and the rest is removed. In other words, the portions of the third transparent film 9 located above the second transparent electrode layers 4 are left, and some of the other portions are left, while the rest are removed. In FIG. 10 , the member shown above the third transparent film 9 is a photoresist 61.

[0026] In step S3, the reflective film 6 is etched to form the reflective electrode 1. After step S3, peeling and cleaning in the a-th process Sa is performed.

[0027] 1 shows an example in which the first sub-pixel 54, which has the thickest transparent electrode portion 2, emits red light, the second sub-pixel 55, which has the second thickest transparent electrode portion 2 after the first sub-pixel 54, emits green light, and the third sub-pixel 56, which has the thinnest transparent electrode portion 2, emits blue light. This example shows that the following configuration may also be used. In the second step S2, for each of the multiple transparent electrode portions 2, the transparent electrode portion 2 is formed to be thicker the longer the emission wavelength corresponding to that transparent electrode portion 2. This makes it possible to manufacture a display device 101 in which the transparent electrode portions 2 have different thicknesses (optical path lengths) corresponding to the emission colors, in other words, a display device 101 that is compatible with microcavity display devices.

[0028] (Additional Notes) The manufacturing method of the display device 101 can be interpreted as reducing the number of photolithography steps by one by changing the order of manufacturing steps in a microcavity type display device. In addition, by forming the reflective electrode 1 after forming the transparent electrode portion 2, the area of ​​the reflective electrode 1 can be maximized.

[0029] The pixel electrode portion of the backplane (BP) substrate of an OLED display device usually has a front plane (FP) structure formed on a reflective electrode 1. If a microcavity structure is not formed on the BP substrate side, the BP process is completed by forming the reflective electrode 1.

[0030] When a microcavity structure is formed on a BP substrate, the microcavity structure is formed between the reflective electrode 1 and the hole injection layer of the FP structure. Because the optimal thickness of the transparent electrode portion 2 differs depending on the emission color of the subpixel, the transparent electrode portion 2 is formed in three steps. The thickest film is formed three times, the next thickest film is formed twice, and the thinnest film is formed once. In this structure, it is necessary to ensure that the edge of the reflective electrode 1 is not damaged during etching of the transparent electrode portion 2. For this reason, the size of the transparent electrode portion 2 needs to be formed larger than the size of the reflective electrode 1. In this structure, in order to cover the reflective electrode 1 with the transparent electrode portion 2, the size of the reflective electrode 1 must be made smaller.

[0031] In the manufacturing method of the display device 101, the reflective electrode 1 is formed after the transparent electrode portion 2 is formed. By forming the transparent electrode portion 2 and the reflective electrode 1 using the photoresist 61 used when forming the third transparent electrode layer 5, it is possible to form the reflective electrode 1 and the transparent electrode portion 2 flush with each other without any misalignment. This eliminates the need to worry about misalignment between the reflective electrode 1 and the transparent electrode portion 2, and makes it possible to increase the size of the reflective electrode 1. Furthermore, as described above, by also using the photoresist 61 used when forming the third transparent electrode layer 5 when forming the reflective electrode 1, it is possible to omit photolithography for forming the reflective electrode 1 and shorten the manufacturing process of the display device 101.

[0032] In the display device 101, the BP substrate having a microcavity structure may have the edge of the reflective electrode 1 flush with the edge of the transparent electrode portion 2. Forming the reflective electrode 1 large can contribute to improving the display brightness of the display device 101.

[0033] 12 is a cross-sectional view showing a schematic configuration of a plurality of reflective electrodes 1 and a plurality of transparent electrode portions 2 according to a second embodiment of the present disclosure. The display device 101 may include a bank 57 that separates the first sub-pixel 54, the second sub-pixel 55, and the third sub-pixel 56 from one another.

[0034] 13 is a cross-sectional view showing a schematic configuration of a plurality of reflective electrodes 1 and a plurality of transparent electrode portions 2 according to a first example of a third embodiment of the present disclosure. In the second step S2, the transparent electrode portions 2 may be formed in an inversely tapered shape with the lower ends 10 of the transparent electrode portions 2 as their bases. In the display device 101, the transparent electrode portions 2 have an inversely tapered shape with the lower ends 10 of the transparent electrode portions 2 as their bases.

[0035] This makes it easier for light incident on the transparent electrode section 2 from the light-emitting layer of the optical function section 52 to be reflected by the side surface 11 of the transparent electrode section 2, thereby realizing a display device 101 that emits light with high brightness and with little light loss.

[0036] In the third step S3, the width W1 of the reflective electrode 1 may be made larger than the width W10 of the lower end 10 of the transparent electrode portion 2. The width W1 of the reflective electrode 1 may be made larger than the width W10 of the lower end 10 of the transparent electrode portion 2.

[0037] The angle θ formed between the upper surface 12 of the reflective electrode 1 and the side surface 11 of the transparent electrode portion 2 may be 30° or more and 89° or less. The angle θ formed between the upper surface 12 of the reflective electrode 1 and the side surface 11 of the transparent electrode portion 2 may be 30° or more and 89° or less.

[0038] The distance D between the edge 13 of the reflective electrode 1 and the lower end 10 of the transparent electrode portion 2 in the width direction HW of the display device 101 may be 0.05 μm or more and 0.50 μm or less. The distance D between the edge 13 of the reflective electrode 1 and the lower end 10 of the transparent electrode portion 2 in the width direction HW of the display device 101 may be 0.05 μm or more and 0.50 μm or less. The distance D may be defined as the distance in a direction parallel to the width direction HW, regardless of the position in the thickness direction HT of the display device 101.

[0039] 14 is a schematic diagram of a reflective electrode 1, a transparent electrode portion 2, and a light-emitting layer 58 of an optically functional portion 52 according to a second example of the third embodiment of the present disclosure. The display device 101 may include a bank 57 that separates a first sub-pixel 54, a second sub-pixel 55, and a third sub-pixel 56 from one another. FIG. 14 is a schematic diagram based on the third sub-pixel 56, and also illustrates emitted light 59 from the light-emitting layer 58 and reflected light 60 obtained when the emitted light 59 is reflected by a side surface 11.

[0040] 3, the side surfaces of the first transparent electrode layer 3, the second transparent electrode layer 4, and the third transparent electrode layer 5 are slightly etched in this order from the interface between the reflective electrode 1 and the transparent electrode portion 2. This makes it possible to manufacture a display device 101 in which the transparent electrode portion 2 has an inversely tapered shape with the lower end 10 of the transparent electrode portion 2 as its base.

[0041] 15 is a cross-sectional view showing a schematic configuration of a display device 101 according to a fourth embodiment of the present disclosure. The display device 101 may include a protective layer 14 located on the reflective electrode 1 and below the transparent electrode portion 2.

[0042] 16 is a flowchart showing main steps in a method for manufacturing a display device 101 according to the fourth embodiment of the present disclosure. The method for manufacturing the display device 101 may include a 1.5th step S1.5.

[0043] Fig. 17 is a diagram illustrating step S1.5. Fig. 18 is a diagram illustrating step S21 according to the fourth embodiment of the present disclosure. Step S1.5 is a step of forming a protective film 15 on the reflective film 6 between step S1 and step S2. In the manufacturing method of the display device 101 according to the fourth embodiment of the present disclosure, the transparent electrode portion 2 may be formed above the protective film 15 in step S2.

[0044] As a result, the upper surface of the reflective film 6 is not exposed when the transparent electrode portion 2 is formed, so that the upper surface of the reflective film 6 can be protected, and the risk of the light reflection characteristics of the reflective electrode 1 being unintentionally changed can be reduced.

[0045] In the second step S2, the transparent electrode portion 2 is formed by etching the transparent film using an etchant, and the etching rate of the protective film 15 with the etchant may be lower than the etching rate of the transparent film with the etchant. The transparent film may be the first transparent film 7, the second transparent film 8, or the third transparent film 9. An example of the etchant is oxalic acid. This makes the protective film 15 less likely to be removed by etching, thereby improving the protective function of the protective film 15 on the upper surface of the reflective film 6.

[0046] The transparent film may be made of an indium oxide amorphous material such as ITO or IZO, and the protective film 15 may be made of an indium oxide polycrystalline material such as ITO or IZO. ITO is an abbreviation for Indium Tin Oxide. IZO is an abbreviation for Indium Zinc Oxide. The transparent electrode portion 2 may be made of an indium oxide amorphous material, and the protective layer 14 may be made of an indium oxide polycrystalline material. This makes it easy to make the etching rate of the protective film 15 with respect to the etchant lower than the etching rate of the transparent film with respect to the etchant.

[0047] The manufacturing method of the display device 101 may include a step 2.5 S2.5 in addition to the step 1.5 S1.5. The step 2.5 S2.5 is etching the protective film 15. The protective layer 14 may be formed by etching the protective film 15 in the step 2.5 S2.5.

[0048] By using the photoresist 61 used when forming the third transparent electrode layer 5 also when forming the protective layer 14, photolithography for forming the protective layer 14 can be omitted, and the manufacturing process of the display device 101 can be shortened.

[0049] With respect to the second step S2 and subsequent steps in the manufacturing method of the display device 101 according to the fourth embodiment of the present disclosure, some parts are omitted from the illustration. These parts may be the same as the corresponding steps or steps in the manufacturing method of the display device 101 according to the first embodiment of the present disclosure, except that a protective film 15 (protective layer 14) is present between the reflective film 6 (reflective electrode 1) and the transparent film (transparent electrode portion 2).

[0050] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0051] DESCRIPTION OF SYMBOLS 1 Reflective electrode 2 Transparent electrode portion 3 First transparent electrode layer 4 Second transparent electrode layer 5 Third transparent electrode layer 6 Reflective film 7 First transparent film 8 Second transparent film 9 Third transparent film 10 Lower end of transparent electrode portion 11 Side surface of transparent electrode portion 12 Upper surface of reflective electrode 13 Edge of reflective electrode 14 Protective layer 15 Protective film 101 Display device D Distance between the edge of the reflective electrode and the lower end of the transparent electrode portion in the width direction of the display device HW Width direction of the display device W1 Width of the reflective electrode W10 Width of the lower end of the transparent electrode portion θ Angle formed between the upper surface of the reflective electrode and the side surface of the transparent electrode portion

Claims

1. A method for manufacturing a microcavity type display device, comprising: a first step of forming a reflective film; a second step of forming a transparent film above the reflective film and patterning the transparent film to form a transparent electrode portion; and a third step of removing the reflective film exposed from the transparent electrode portion to form a reflective electrode.

2. The method for manufacturing a display device according to claim 1, wherein a plurality of transparent electrode portions are formed in the second step, and a plurality of reflective electrodes are formed below each of the plurality of transparent electrode portions in the third step.

3. The method for manufacturing a display device according to claim 2, wherein in the second step, the plurality of transparent electrode portions are formed to have thicknesses different from one another.

4. A method for manufacturing a display device as described in claim 3, wherein in the second step, a first transparent film is formed above the reflective film, and at least one first transparent electrode layer included in the plurality of transparent electrode portions is formed by leaving at least one portion of the first transparent film and removing the rest.

5. A method for manufacturing a display device as described in claim 4, wherein in the second step, a second transparent film is formed above the reflective film, including above the at least one first transparent electrode layer, and at least two locations on the second transparent film, including above the at least one first transparent electrode layer, are left, and the rest are removed, thereby forming at least two second transparent electrode layers included in the multiple transparent electrode portions.

6. A method for manufacturing a display device as described in claim 5, wherein in the second step, a third transparent film is formed above the reflective film, including above the at least two second transparent electrode layers, and at least three third transparent electrode layers are formed to be included in the multiple transparent electrode portions, so as to leave at least three locations on the third transparent film, including above the at least two second transparent electrode layers, and remove the rest.

7. A method for manufacturing a display device according to any one of claims 2 to 6, wherein in the second step, for each of the plurality of transparent electrode portions, the longer the emission wavelength corresponding to the transparent electrode portion, the thicker the transparent electrode portion is formed.

8. A method for manufacturing a display device according to any one of claims 1 to 7, wherein in the second step, the transparent electrode portion is formed in an inversely tapered shape with the lower end of the transparent electrode portion as the base.

9. The method for manufacturing a display device according to claim 8, wherein in the third step, the width of the reflective electrode is made larger than the width of the lower end of the transparent electrode portion.

10. The method for manufacturing a display device according to claim 9, wherein the angle formed between the upper surface of the reflective electrode and the side surface of the transparent electrode portion is 30° or more and 89° or less.

11. The method for manufacturing a display device according to claim 9 or 10, wherein the distance between the edge of the reflective electrode and the lower end of the transparent electrode portion in the width direction of the display device is 0.05 μm or more and 0.50 μm or less.

12. A method for manufacturing a display device according to any one of claims 1 to 11, wherein a protective film is formed on the reflective film between the first step and the second step, and the transparent electrode portion is formed above the protective film in the second step.

13. A method for manufacturing a display device as described in claim 12, wherein in the second step, the transparent electrode portion is formed by etching the transparent film using an etchant, and the etching rate of the protective film with the etchant is made lower than the etching rate of the transparent film with the etchant.

14. The method for manufacturing a display device according to claim 13, wherein the transparent film is made of an amorphous indium oxide material, and the protective film is made of a polycrystalline indium oxide material.

15. A microcavity type display device comprising: a reflective electrode; and a transparent electrode portion located above the reflective electrode, wherein the transparent electrode portion has an inverse tapered shape with its base located at the lower end of the transparent electrode portion.

16. The display device according to claim 15, wherein the width of the reflective electrode is greater than the width of the lower end of the transparent electrode portion.

17. The display device according to claim 16, wherein the angle formed between the top surface of the reflective electrode and the side surface of the transparent electrode portion is 30° or more and 89° or less.

18. The display device according to claim 16 or 17, wherein the distance between the edge of the reflective electrode and the lower end of the transparent electrode portion in the width direction of the display device is 0.05 μm or more and 0.50 μm or less.

19. The display device according to any one of claims 15 to 18, further comprising a protective layer located on the reflective electrode and below the transparent electrode portion.

20. The display device according to claim 19, wherein the transparent electrode portion is made of an amorphous indium oxide material, and the protective layer is made of a polycrystalline indium oxide material.

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