Micro light-emitting element and image display element

Abstract

The micro-light-emitting element includes a main body on which a P-side layer, a light-emitting layer and an N-side layer are deposited in sequence from the light release surface side, a common P electrode on the light release surface side, an N electrode on the side opposite to the light release surface, and a reflective material covering the side surface. The light-emitting layer is arranged on the light release surface side of the main body, and the side surface is inclined in an open manner relative to the light release direction. The surface of the main body side of the N electrode and the reflective material is a reflective surface that reflects visible light.

Description

Technical Field

[0001] The present invention relates to a micro-light emitting element and an image display element comprising the micro-light emitting element. Background Art

[0002] In the past, a display element has been proposed in which a plurality of micro-light-emitting elements constituting pixels are arranged on a driving circuit substrate. For example, in the technology disclosed in Japanese Patent Publication No. 2002-141492, a driving circuit is formed on a silicon substrate, and an array of micro-light-emitting diodes (LEDs) emitting ultraviolet light is arranged on the driving circuit. In addition, in the aforementioned technology, a small display element is disclosed, which displays a color image by providing a wavelength conversion layer (wavelength conversion layer) on the LED array to convert ultraviolet light into red, green and blue visible light.

[0003] This type of display element is not only small, but also has characteristics such as high brightness and high durability. Therefore, it is expected to be used as a display element for display elements such as glasses-like devices and head-up displays (HUD).

[0004] Since the materials of the driving circuit substrate and the micro-light-emitting elements are different, a method of manufacturing such a display element is usually to form them separately and then bond them together.

[0005] However, the structure of the micro-light-emitting element and the display element disclosed in the above-mentioned Japanese Patent Publication No. 2002-141492 has the following problems. First, among the light generated in the light-emitting layer of a certain micro-light-emitting element, a large proportion (tens of%) of the light is released from the side of the micro-light-emitting element toward the micro-light-emitting element adjacent to the micro-light-emitting element. Such light is absorbed by the adjacent micro-light-emitting element and then released again from the adjacent micro-light-emitting element that absorbed the light, causing optical crosstalk in which micro-light-emitting elements other than the micro-light-emitting element that should release light appear to emit light.

[0006] When micro-light emitting elements are connected to each other via compound semiconductors, light leaks to adjacent micro-light emitting elements via the compound semiconductors, and similar optical crosstalk occurs. This optical crosstalk causes problems such as reduced contrast and reduced color purity.

[0007] In addition, in the technology disclosed in the above-mentioned Japanese Patent Gazette No. 2002-141492, in addition to a large amount of light loss caused by the light release from the side of the above-mentioned micro-light-emitting element, the light generated in the light-emitting layer of the micro-light-emitting element is confined to the inside of the micro-light-emitting element. This is because the refractive index of the compound semiconductor constituting the micro-light-emitting element is greater than that of air and resin, so when light is incident on the interface between the compound semiconductor and the outside of the compound semiconductor, total reflection occurs within a wide range of incident angles. Due to these reasons, the light extraction efficiency of the micro-light-emitting element is reduced, and therefore, the luminous efficiency is reduced. Here, the light extraction efficiency represents the ratio of the light generated inside the micro-light-emitting element to the light released outside the micro-light-emitting element, and the luminous efficiency represents the efficiency of converting the current or power input into the micro-light-emitting element into light released to the outside of the display element. The reduction in luminous efficiency causes problems such as increased power consumption and temperature rise due to heat generation. Summary of the invention

[0008] Technical Problems to be Solved by the Invention

[0009] One aspect of the present invention is designed in view of the above-mentioned problems and aims to prevent optical crosstalk between adjacent micro-light-emitting elements and improve the light-emitting efficiency of the micro-light-emitting elements.

[0010] Technical solutions for solving technical problems

[0011] In order to solve the above-mentioned problem, a micro-light-emitting element in one form of the present invention comprises: a main body, which comprises a compound semiconductor layer on which a first conductive layer, a light-emitting layer and a second conductive layer are deposited in sequence from the light-releasing surface side, wherein the second conductive layer has a conductivity type opposite to that of the first conductive layer; a first electrode, which comprises a transparent electrode on the light-releasing surface side; a second electrode, which comprises a metal film on the side opposite to the light-releasing surface side; and a first reflective material, which covers the side surface of the main body, the light-emitting layer is arranged on the light-releasing surface side of the main body, the side surface of the main body is inclined in a manner open relative to the light-releasing direction, and the surfaces of the second electrode and the first reflective material on the side of the main body are reflective surfaces that reflect visible light.

[0012] Beneficial Effects

[0013] According to one aspect of the present invention, optical crosstalk between adjacent micro-light emitting elements can be prevented and the light emission efficiency of the micro-light emitting elements can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1It is a schematic cross-sectional view of the image display element according to the first embodiment of the present invention.

[0015] Figure 2 It is a schematic plan view of an image region of the image display element according to the first embodiment of the present invention.

[0016] Figure 3 It is a schematic cross-sectional view showing the manufacturing process (manufacturing flow) of the micro light-emitting element according to the first embodiment of the present invention.

[0017] Figure 4 is a schematic cross-sectional view showing the manufacturing process of the micro-light emitting element, and Figure 3 Continuation of the picture.

[0018] Figure 5 is a schematic cross-sectional view showing the manufacturing process of the micro-light emitting element, and Figure 4 Continuation of the picture.

[0019] Figure 6 It is a schematic cross-sectional view showing the manufacturing process of the image display element according to the first embodiment of the present invention.

[0020] Figure 7 is a schematic cross-sectional view showing the manufacturing process of the image display element, and is a schematic view showing Figure 6 Continuation of the picture.

[0021] Figure 8 is a schematic cross-sectional view showing the manufacturing process of the image display element, and is a schematic view showing Figure 7 Continuation of the picture.

[0022] Fig. 9 It is a schematic cross-sectional view of a structure (reverse truncated pyramid type structure) simulated in simulation of the first embodiment of the present invention.

[0023] Fig.10 Q1 and Q2 are used with Fig. 9 A schematic cross-sectional view of another structure subjected to simulation for comparison.

[0024] Fig.11 R1 is a graph showing the simulation result of the dependence of the light extraction efficiency on the film thickness of the transparent insulating film. Figure 1 The graph is a simulation result of the dependence of the light extraction efficiency on the inclination angle of the body side surface in the image display element shown.

[0025] Fig.12The figure shows the simulation result of the tilt angle dependency of the red light emitting efficiency in the red sub-pixel of the image display element according to the first embodiment of the present invention.

[0026] Fig.13 It is a schematic cross-sectional view of an image display element according to a second embodiment of the present invention.

[0027] Fig.14 It is a schematic cross-sectional view showing the manufacturing process of the micro light-emitting element according to the second embodiment of the present invention.

[0028] Fig.15 is a schematic cross-sectional view showing the manufacturing process of the micro-light emitting element, and Fig.14 Continuation of the picture.

[0029] Fig.16 1 is a schematic cross-sectional view showing a manufacturing process of an image display element according to a second embodiment of the present invention.

[0030] Fig.17 is a schematic cross-sectional view showing the manufacturing process of the image display element, and Fig.16 Continuation of the picture.

[0031] Fig.18 is a schematic cross-sectional view showing the manufacturing process of the image display element, and Fig.17 Continuation of the picture.

[0032] Fig.19 It is a schematic cross-sectional view of a structure simulated by simulating the second embodiment of the present invention.

[0033] Fig. 20 It is a cross-sectional simulation diagram of an image display element according to the third embodiment of the present invention.

[0034] Fig.21 It is a schematic cross-sectional view of a structure simulated by simulating the third embodiment of the present invention.

[0035] Fig. 22 It is a schematic plan view of a pixel constituting an image display element according to a fourth embodiment of the present invention.

[0036] Fig.23 FIG. 4 is a schematic cross-sectional view of a micro light-emitting element mounting portion of an image display element according to a fourth embodiment of the present invention.

[0037] Fig.24 It is a schematic cross-sectional view showing the manufacturing process of the micro light-emitting element according to the fourth embodiment of the present invention.

[0038] Fig.25 is a schematic cross-sectional view showing the manufacturing process of the micro-light emitting element, and Fig.24 Continuation of the picture.

[0039] Fig.26 is a schematic cross-sectional view showing the manufacturing process of the micro-light emitting element, and Fig.25 Continuation of the picture.

[0040] Fig. 27 It is a schematic cross-sectional view showing a manufacturing process of an image display element according to a fourth embodiment of the present invention, and shows a micro light-emitting element mounting portion.

[0041] Fig.28 It is a schematic cross-sectional view showing a modified example of the micro light emitting element according to the first embodiment of the present invention.

[0042] Fig.29 FIG. 1 is a schematic cross-sectional view showing another modified example of the micro light emitting element according to the first embodiment of the present invention. DETAILED DESCRIPTION

[0043] [First embodiment]

[0044] [Configuration of Image Display Element 200]

[0045] Figure 1 FIG. 1 is a schematic cross-sectional view of an image display device 200 according to the first embodiment of the present invention. Figure 2 FIG. 2 is a schematic plan view of an image region of an image display element 200 according to a first embodiment of the present invention. Figures 1 to 8 The image display element 200 will be described.

[0046] In the description of the structure of the image display element 200, the light emitting surface is called the upper surface, the surface opposite to the light emitting surface is called the lower surface, and the side surfaces other than the upper surface and the lower surface are called the side surfaces. In addition, in the micro-light emitting element 100, the light emitting surface side is the upper side, and the side opposite to the light emitting surface side is the lower side, so as to indicate the up and down directions. In addition, the up and down directions shown below are for the convenience of description, and the embodiments of the present invention are not limited to these directions.

[0047] In addition, when distinguishing the micro-light emitting elements of each light emitting color, letters indicating the color are added to the back in the form of 100R, 100G and 100B. If no letters are added, it represents the whole. The same is true for other components of the micro-light emitting element 100.

[0048] like Figure 1As shown, the image display element 200 includes a plurality of micro-light emitting elements 100 (micro-light emitting elements 100B, micro-light emitting elements 100R, and micro-light emitting elements 100G) and a driving circuit substrate 50. The driving circuit substrate 50 includes a driving circuit that supplies current to the micro-light emitting elements 100B, micro-light emitting elements 100R, and micro-light emitting elements 100G in a pixel region 1 and controls light emission. The pixel region 1 is a region where the micro-light emitting elements 100 are arranged in a two-dimensional array on the driving circuit substrate 50, and the image display element 200 has a pixel region 1.

[0049] In pixel area 1, as Figure 2 As shown, the pixels 5 are arranged in an array, and each pixel 5 includes a blue sub-pixel 6, a red sub-pixel 7, and a green sub-pixel 8. The blue sub-pixel 6, the red sub-pixel 7, and the green sub-pixel 8 emit blue light, red light, and green light, respectively, and by adjusting their respective intensities, light of various colors can be emitted as the pixel 5. Figure 1 The pixel area 1 in Figure 2 A cross-sectional view of the AA' line portion.

[0050] The blue sub-pixel 6, the red sub-pixel 7, and the green sub-pixel 8 include a micro-light emitting element 100B, a micro-light emitting element 100R, and a micro-light emitting element 100G, respectively. The micro-light emitting element 100B, the micro-light emitting element 100R, and the micro-light emitting element 100G have the same structure and emit blue light. Hereinafter, when the micro-light emitting element 100B, the micro-light emitting element 100R, and the micro-light emitting element 100G are referred to as a micro-light emitting element 100 as described above.

[0051] In addition, Figure 2 In the embodiment, the green sub-pixel is composed of two micro-light emitting elements 100G, but the number of micro-light emitting elements 100 constituting each sub-pixel may be one or more. Figure 2 In the figure, the micro-light emitting element 100 is drawn as a shape close to a square, but the shape of each micro-light emitting element 100 when viewed from above may be a rectangle, a polygon, a circle, an ellipse, etc. As described above, various planar shapes may be used as the shape of the micro-light emitting element 100 when viewed from above, but the maximum length along the long side direction of the upper surface of the micro-light emitting element 100 is 60 μm or less. In the image display element 200, more than 3,000 micro-light emitting elements 100 are integrated in the pixel region 1.

[0052] [Micro light emitting element 100]

[0053] Each micro-light emitting element 100 includes a micro-light emitting element body 16 (hereinafter referred to as body 16) made of a nitride semiconductor, an N-electrode 23N (second electrode) and a common P-electrode 30 (first electrode, light-releasing surface electrode), wherein the common P-electrode 30 is arranged on the light-releasing surface side of the body 16, and the N-electrode 23N is arranged on the driving circuit substrate 50 side. The body 16 is a structure in which each micro-light emitting element 100 is divided by dividing grooves 15 to divide a compound semiconductor layer 14 described later.

[0054] In the configuration of this embodiment, the P-side layer 13 of the compound semiconductor layer 14 is arranged on the light-releasing surface side, and the N-side layer 11 is arranged on the driving circuit substrate 50 side. The thickness of the P-side layer 13 is about 1 / 5 to 1 / 10 of the thickness of the N-side layer 11. Therefore, the light-emitting layer 12 is arranged at a position close to the light-releasing surface (the upper surface of the compound semiconductor layer 14) in the compound semiconductor layer 14. In other words, the light-emitting layer 12 is arranged at a position closer to the upper surface than the lower surface of the compound semiconductor layer 14 in the stacking direction of the compound semiconductor layer 14. That is, the light-emitting layer 12 is located between the light-releasing surface and the middle of the body 16. Therefore, the light-emitting layer 12 is unevenly arranged on the light-releasing surface side of the compound semiconductor layer 14.

[0055] The N electrode 23N is connected to the N driving electrode 51 on the driving circuit substrate 50. The common P electrode 30 is connected to the P driving electrode 52 on the driving circuit substrate 50 in the P connection area 3 outside the pixel area 1. Each micro-light-emitting element 100 is supplied with current from the corresponding N driving electrode 51 and emits light. The light release direction is the opposite direction to the driving circuit substrate 50 with respect to the main body 16, and is the common P electrode 30 side. The micro-light-emitting element 100B, the micro-light-emitting element 100R, and the micro-light-emitting element 100G are individually divided, and the space between each micro-light-emitting element 100 is filled with a filling material 60 as an insulating material.

[0056] The blue light released from the micro-light-emitting element 100B passes through the transparent portion 31 on the upper surface of the micro-light-emitting element 100B, and is released to the outside as it is. On the other hand, the blue light emitted by the micro-light-emitting element 100R is absorbed by the red wavelength conversion layer 32, and converted into red light, and released to the outside. Similarly, the blue light emitted by the micro-light-emitting element 100G is absorbed by the green wavelength conversion layer 33, and converted into green light, and released to the outside. In other words, the red wavelength conversion layer 32 and the green wavelength conversion layer 33 (wavelength conversion layer) absorb the excitation light (blue light) emitted by the micro-light-emitting element 100, and convert it into long-wavelength light (red or green) longer than the excitation light, and release it to the outside. Figure 1The transparent portion 31 , the red wavelength conversion layer 32 , the green wavelength conversion layer 33 , and the common P electrode 30 are shown in FIG. 3 , but a thin film may be further provided therebetween.

[0057] The transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 are separated by the partition wall 34. The blue light from the compound semiconductor layer 14 of each micro-light-emitting element 100 passes through the opening 37 formed between the partition walls 34 on the upper portion of each micro-light-emitting element 100, and enters the transparent portion 31, the red wavelength conversion layer 32, or the green wavelength conversion layer 33. In addition, the light reflected inside the transparent portion 31, the red wavelength conversion layer 32, or the green wavelength conversion layer 33 passes through the opening 37 and enters the compound semiconductor layer 14.

[0058] A light diffusion layer, a color filter, a microlens, etc. may be arranged on the transparent portion 31, the red wavelength conversion layer 32, the green wavelength conversion layer 33, and the partition wall 34; however, since these are not directly related to one embodiment of the present invention, they are not shown in the drawings.

[0059] (Compound Semiconductor Layer 14)

[0060] As described above, each micro-light-emitting element 100 includes a compound semiconductor layer 14. The compound semiconductor layer 14 is formed by stacking a P-side layer 13 (first conductive layer), a light-emitting layer 12, and an N-side layer 11 (second conductive layer) in order from the light-releasing surface side. The P-side layer 13 has a conductivity type opposite to that of the N-side layer 11, that is, has an opposite polarity.

[0061] In the following, the configuration in which the compound semiconductor layer 14 and the P-side layer 13 are arranged on the light-releasing surface side is described, but the configuration in which the N-side layer 11 is arranged on the light-releasing surface side may also be described. The N-side layer 11, the light-emitting layer 12, and the P-side layer 13 are generally not single layers but preferably include multiple layers, but since they are not directly related to one form of the present invention, the detailed structures of the N-side layer 11, the light-emitting layer 12, and the P-side layer 13 are not described in detail.

[0062] Generally, the light emitting layer 12 is sandwiched between an N-type layer and a P-type layer, but there is also a case where the N-type layer or the P-type layer includes a non-doped layer or a layer having opposite conductivity (conductivity type) depending on the situation. Therefore, in this specification, for the two layers sandwiching the light emitting layer 12, the semiconductor layer including the N-type layer side is referred to as the N-side layer 11, and the semiconductor layer including the P-type layer side is referred to as the P-side layer 13. In addition, in GaN-based compound semiconductors, Si is generally used as an N-type dopant included in the N-type layer, and Mg is used as a P-type dopant included in the P-type layer.

[0063] Adding a dopant with "opposite conductivity" to the N-side layer 11 or the P-side layer 13 is equivalent to, for example, adding Si to a portion of the P-type layer. That is, although the entire layer is a P-type layer, there is also a case where a portion of the P-type layer contains a low concentration of N-type dopant.

[0064] (Drive Circuit Substrate 50)

[0065] The driving circuit substrate 50 is composed of a micro light emitting element driving circuit, a row selection circuit, a column signal output circuit, an image processing circuit, and an input / output circuit. The micro light emitting element driving circuit controls the current supplied to each micro light emitting element 100. The row selection circuit selects each row of the micro light emitting elements 100 arranged in a two-dimensional matrix. The column signal output circuit outputs a light emitting signal to each column. The image processing circuit calculates a light emitting signal based on an input signal.

[0066] The surface of the driving circuit substrate 50 on the side of the bonding surface 53 is provided with an N-drive electrode 51 (N-drive electrode) and a P-drive electrode 52 (P-drive electrode) connected to the micro-light-emitting element 100. That is, the surface of the driving circuit substrate 50 faces the surface of the micro-light-emitting element 100 opposite to the light-releasing surface side. The driving circuit substrate 50 may generally be a silicon substrate (semiconductor substrate) on which an LSI (integrated circuit) is formed, or may be a glass substrate or a resin substrate on which a circuit of a thin film transistor (TFT) is formed. Since either one can be manufactured by a known technique, their functions and configurations will not be described in detail.

[0067] N driving electrodes 51 for supplying current to the micro light-emitting element 100 are arranged in a two-dimensional array on the surface of the pixel region 1 of the driving circuit substrate 50. In addition, P driving electrodes 52 are arranged on the surface outside the pixel region 1 of the driving circuit substrate 50 (the surface of the P connection region 3). The P driving electrode 52 is electrically connected to the common P electrode 30 via the dummy element 101. In the dummy element 101, the common P electrode 30 and the P electrode 23P are electrically connected via the connection portion 40. The dummy element 101 is connected to the P driving electrode 52 by the same connection method as the connection method between the main body 16 and the N driving electrode 51 in the micro light-emitting element 100.

[0068] The surface of the driving circuit substrate 50 is a bonding surface 53 to which the plurality of micro-light-emitting elements 100 are bonded, and is bonded to the plurality of micro-light-emitting elements 100. In the present embodiment, the micro-light-emitting elements 100 are of a so-called vertical type. The micro-light-emitting elements 100 have an N electrode 23N on one surface and a common P electrode 30 on the other surface.

[0069] Specifically, in the micro-light emitting element 100, a common P electrode 30 is arranged on the light release surface side, and an N electrode 23N is arranged on the surface on the side opposite to the light release surface side. The light release surface of the micro-light emitting element 100 is the upper surface of the micro-light emitting element 100, and the surface on the side opposite to the light release surface of the micro-light emitting element 100 is the lower surface of the micro-light emitting element 100. The N electrode 23N and the N driving electrode 51 are connected in a one-to-one relationship.

[0070] In the pixel region 1, an N electrode 23N connected to the N-side layer 11 is arranged on the lower surface of the micro-light-emitting element 100, and the N electrode 23N is connected to the N driving electrode 51 on the driving circuit substrate 50. The N electrode 23N transmits the current supplied from the driving circuit substrate 50 to the N-side layer 11. In this embodiment, only the structure in which the N electrode 23N and the N driving electrode 51 are directly connected is shown, but a member for connection such as a bump, glue, or nanoparticles may be interposed between the two. The same is true for the P electrode 23P and the P driving electrode 52.

[0071] The current that has passed through the N-side layer 11 further passes through the light-emitting layer 12 and the P-side layer 13, flows to the common P electrode 30, and flows into the P driving electrode 52 of the driving circuit substrate 50 in the P connection region 3 outside the pixel region 1. In this way, the micro light-emitting element 100 emits light at a predetermined intensity according to the amount of current supplied by the driving circuit substrate 50.

[0072] Preferably, a metal layer with a large reflectivity relative to visible light is arranged on the side of the N electrode 23N in contact with the N side layer 11. For example, the N electrode 23N has a metal layer M1 (not shown) with silver or aluminum as a main component on the N side layer 11 side. Preferably, good ohmic contact is achieved between these metal layers M1 and the N side layer 11. On the other hand, preferably, a metal material that is easily connected to the N driving electrode 51 is arranged on the side of the N electrode 23N in contact with the driving circuit substrate 50. For example, gold or copper. In this way, the N electrode 23N is composed of multiple metal layers and barrier layers.

[0073] (Common P electrode 30)

[0074] The common P electrode 30 is composed of a transparent conductive layer (transparent conductive layer) that is conductive to the P side layer 13, that is, a transparent conductive film. The common P electrode 30 can be an oxide semiconductor such as ITO (Indium-Tin-Oxide) and IZO (Indium-Zinc-Oxide), or a silver nanofiber film. The common P electrode 30 is preferably as thin as possible to reduce the absorption of blue light. Although the wiring resistance is increased by making the common P electrode 30 thin, in the configuration of this embodiment, the partition wall 34 as a conductive material is electrically connected to the common P electrode 30 and is arranged in the entire pixel area 1, so that the wiring resistance between the P driving electrode 52 and the micro-light-emitting element 100 can be kept low.

[0075] (Side 16S of the main body)

[0076] The compound semiconductor layer 14 constituting the micro-light emitting element 100 is divided into the main body 16 by the dividing groove 15. Therefore, adjacent micro-light emitting elements 100 are not connected to each other via a part of the compound semiconductor layer 14. Figure 1 As shown, the side surface 16S of the body 16 extends from one surface (the lower surface of the N-side layer 11) to the other surface (the surface of the P-side layer 13) of the compound semiconductor layer 14. Therefore, light leakage between adjacent micro light-emitting elements 100 can be prevented.

[0077] In this embodiment, if Figure 2 As shown, the planar shape of the micro-light emitting element 100 is a quadrilateral, and the side 16S of the body 16 includes four surfaces. When the planar shape of the micro-light emitting element 100 is a polygon and the number of angles is N (N is a natural number), N side surfaces 16S are formed. In addition, when the planar shape of the micro-light emitting element 100 is a circle, the side surface 16S is formed by the side surface of a truncated cone.

[0078] The side surface 16S is preferably inclined in an open manner relative to the light release direction. In addition, the inclination angle θe of the side surface 16S is constant (same). The inclination angle θe is an angle formed by the side surface 16S and the horizontal plane H1 (upper surface) of the light release surface. Preferably, the inclination angle θe of the side surface 16S is greater than or equal to 30° and less than or equal to 80°. Preferably, the inclination angle θe is constant, but there is a case where the inclination angle θe varies depending on the manufacturing process.

[0079] In the configuration of the present embodiment, the light-emitting layer 12 is close to the light-releasing surface. Therefore, even if the inclination angle θe is set to be small in order to improve the light extraction efficiency, it is difficult to reduce the area of ​​the horizontal plane of the light-emitting layer 12. On the other hand, when the light-emitting layer 12 is disposed at the bottom (the side opposite to the light-releasing surface side), when the inclination angle θe decreases, the area of ​​the horizontal plane of the light-emitting layer 12 decreases. When the area of ​​the horizontal plane of the light-emitting layer 12 decreases, the current density of the current passing through the light-emitting layer 12 increases, and the internal quantum efficiency decreases. Therefore, when the size of the micro-light-emitting element 100 is small (for example, when the long side of the upper surface of the micro-light-emitting element 100 is less than 10 μm), as in the configuration of the present embodiment, the characteristics of the micro-light-emitting element can be improved by configuring the light-emitting layer 12 on the light-releasing surface side.

[0080] The side surface 16S is covered by the transparent insulating film 17, and the transparent insulating film 17 is covered by the reflective material 20. That is, the side surface 16S is covered by the reflective material 20 (first reflective material) opposite to the side surface 16S via the transparent insulating film 17. The reflective material 20 and the N electrode 23N are made of a metal material having a high reflectivity with respect to visible light, and the surface on the main body 16 side is a reflective surface that reflects visible light.

[0081] The transparent insulating film 17 is disposed between the side surface 16S of the main body 16 and the reflective material 20. Preferably, the transparent insulating film 17 is made of SiO 2 The transparent insulating film 17 is disposed between the side surface 16S and the reflective material 20. The transparent insulating film 17 preferably has a thickness of 75 nm or more, more preferably 400 nm or more.

[0082] In the configuration of this embodiment, the reflective material 20 covering the side 16S is formed by extending the N electrode 23N onto the side 16S to simplify the manufacturing process. However, the reflective material 20 does not necessarily have to be connected to the N electrode 23N. The reflective material 20 can be composed of a single layer or a plurality of layers. Preferably, the reflective material 20 has a metal layer M2 (not shown) on the side of the transparent insulating film 17, that is, the side of the compound semiconductor layer 14, and the metal layer M2 is a metal layer with silver or aluminum as a main component having a large reflectivity relative to visible light. The metal layer M2 can also be made of the same material as the above-mentioned metal layer M1. The reflective material 20 needs to shield light, and preferably, its overall thickness is more than several tens of nm.

[0083] Preferably, the N electrode 23N and the reflective material 20 are arranged so as to cover the entire micro-light-emitting element 100 when viewed from the side opposite to the light-releasing surface. If there is an exposed portion of the compound semiconductor layer 14 when viewed from the side opposite to the light-releasing surface, light is released to the outside and optical crosstalk occurs, so it is preferable not to have such an exposed portion.

[0084] In the configuration of this embodiment, most of the bottom and side surfaces of the micro LED 100 are covered by the N electrode 23N and the reflective material 20, and light leakage is very small. However, there is a portion that is not covered by the reflective material 20 in the side surface 16S on the light-releasing side of the micro light-emitting element 100. Therefore, in order to prevent light crosstalk through this portion, the embedding material 60 is preferably a light-shielding material.

[0085] As such a filling material 60, a light absorbing material such as carbon black, a material containing TiO 2 White resin particles, etc. In addition, Figure 1 The same effect can be obtained by configuring a light-shielding material on the upper part of the embedding material 60 and a transparent material on the lower part. When the exposed portion of the transparent insulating film 17 not covered by the reflective material 20 is thin and the optical crosstalk is small, the embedding material 60 can also be a transparent material.

[0086] (Partition wall 34 and partition wall side surface 34S)

[0087] The partition wall 34 that delimits the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 is made of a metal material. The partition wall side surface 34S, which is a side surface thereof, is formed of a metal material having a high reflectivity with respect to visible light, similarly to the reflective material 20. In addition, the partition wall side surface 34S is inclined in a manner open toward the light release direction. That is, the partition wall side surface 34S is inclined from the upper side to the lower side in the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 in a forward cone shape.

[0088] The inclination angle θw of the side surface 34S of the partition wall is preferably less than 90°, and more preferably about 45° to 80°. The inclination angle θw is the angle formed by the side surface 34S of the partition wall and the upper surface of the common P electrode 30. Since the bottom width of the partition wall 34 increases if the inclination angle θw decreases, the width of the partition wall 34 on the length of one side of the sub-pixel (blue sub-pixel 6, red sub-pixel 7 and green sub-pixel 8) increases, and the micro-light-emitting element 100 becomes smaller. When the area of ​​the sub-pixel is smaller, the area of ​​the micro-light-emitting element 100 is also reduced, and the effective area of ​​the light-emitting layer 12 is further reduced. Therefore, the current density through the light-emitting layer 12 increases, the luminous efficiency decreases or the temperature rise increases.

[0089] Inside the red wavelength conversion layer 32, blue light is absorbed and red light is generated. Among the generated red light, not much red light is directly released into the air. A portion of the generated red light is lost due to reflection within the red wavelength conversion layer 32. Most of the generated red light is incident on the body 16, is reflected within the body 16, and returns to the red wavelength conversion layer 32 again. A portion of the red light that returns to the red wavelength conversion layer 32 is released into the air, and the rest is lost due to reflection within the red wavelength conversion layer 32 or is incident on the body 16 again. As described above, when the red light is released to the outside, it is very important that the loss caused by reflection within the red wavelength conversion layer 32 is reduced, and the red light incident on the body 16 is effectively returned to the red wavelength conversion layer 32. The same is true for green light.

[0090] Furthermore, a considerable portion of the blue light incident on the transparent portion 31 from the micro-light emitting element 100B is also reflected at the interface between the transparent portion 31 and the air. Part of the blue light reflected in this way is lost due to reflection in the transparent portion 31, and the remaining part is incident on the body 16, and is reflected in the body 16 and returns to the transparent portion 31 again. Therefore, as with the red light, it is very important to reduce the loss caused by reflection in the transparent portion 31 and to effectively return the blue light incident on the body 16 to the transparent portion 31.

[0091] In order to reduce the light loss caused by reflection inside the transparent part 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33, it is necessary to cover the transparent part 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 with a material having a high reflectivity, except for the connection part with the micro-light-emitting element 100. For this purpose, it is important that the side surface 34S of the partition wall is composed of a high-reflectivity metal film, and the opening 37 of the partition wall 34 is located on the inner side compared with the inner edge of the upper end of the reflective material 20 of the micro-light-emitting element 100. The high-reflectivity metal film refers to a metal film that reflects visible light (including long-wavelength light (red light and green light) or excitation light (blue light)) and has a high reflectivity.

[0092] By forming the partition wall side surface 34S with a high reflectivity metal film, the partition wall 34 functions as a reflective surface that reflects red light, green light, and blue light, and while preventing light from leaking to the partition wall 34, the reflectivity on the partition wall side surface 34S is increased and light loss is reduced. By arranging the opening 37 of the partition wall 34 on the inner side compared to the inner edge of the upper end of the reflective material 20 of the micro-light-emitting element 100, when the micro-light-emitting element 100 is viewed from above, the embedding material 60 is not exposed from the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33. As a result, the loss and optical crosstalk caused by the leakage of light from the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 to the embedding material 60 can be reduced. Therefore, all the light released downward can be guided from the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 to the micro-light-emitting element 100, and returned to the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 through the micro-light-emitting element 100.

[0093] [Manufacturing process of micro light emitting device 100]

[0094] Next, use Figure 3 to Figure 5 Steps L1 to L10 of the present invention describe the manufacturing process of the micro light-emitting element 100 . Figure 3 to Figure 5 Schematic cross-sectional view showing the manufacturing process of the microluminescent element 100 according to the first embodiment of the present invention. In the description of the manufacturing process of the microluminescent element 100, the N-side layer 11 side is the upper side and the P-side layer 13 side is the lower side.

[0095] Figure 3 to Figure 5 The right side of the steps L1 to L10 in FIG. 1 shows a cross-sectional view of the pixel region 1. Figure 3 to Figure 5 The left side of the steps L1 to L10 in FIG. 1 shows a cross-sectional view of the P connection region 3. Figure 3 As shown in step L1 , the compound semiconductor layer 14 is formed by sequentially stacking the N-side layer 11 , the light-emitting layer 12 , and the P-side layer 13 on the growth substrate 9 .

[0096] Then, if Figure 3 As shown in step L2, the P-side layer 13 of the compound semiconductor layer 14 is attached to the LED processing substrate 10 via the adhesive layer 19. Figure 3 The growth substrate 9 is removed as shown in step L3. The growth substrate 9 can be removed by various methods such as grinding, lapping, plasma etching, wet etching, wet etching of sacrificial layer, and laser lift-off. At this time, a part of the N-side layer 11 is removed, and the thickness of the compound semiconductor layer 14 is adjusted.

[0097] Then, if Figure 4As shown in step L4, the N-side layer 11, the light-emitting layer 12, and the P-side layer 13 are etched to form a dividing groove 15. The dividing groove 15 divides the entire layer of the compound semiconductor layer 14 from the surface of the N-side layer 11 to the interface between the P-side layer 13 and the bonding layer 19. Figure 2 As shown, the dividing grooves 15 are formed at equal intervals in the vertical and horizontal directions in a plan view, and the compound semiconductor layer 14 is divided into quadrangular pyramid-shaped bodies 16. In the P connection region 3, dummy bodies 16D are similarly formed.

[0098] However, the shape of the main body 16 is not limited to a quadrangular pyramid, and may be a circular pyramid or other polygonal pyramid. The dividing groove 15 divides the micro-light emitting element 100 in the pixel region 1, but a P contact trench 15P is formed in the P connection region 3 simultaneously with the division. The dummy main body 16 does not need to be divided as finely as the main body 16, and may also be connected to the main body 16. Figure 4 Vertical direction of the paper.

[0099] The side surface 16S of the main body 16 is processed and formed in such a manner that the angle formed by the side surface 16S and the horizontal plane H1 of the light-emitting layer 12, that is, the inclination angle θe, is, for example, 45°. In addition, it is preferable that the side surface 16S is formed in such a manner that the inclination angle θe is greater than or equal to 30° and less than or equal to 80°. Since light is released isotropically from the light-emitting layer 12, more light travels in a direction parallel to the horizontal plane H1 of the light-emitting layer 12 than in a direction perpendicular to the horizontal plane H1 of the light-emitting layer 12. By reflecting the light traveling in such a direction parallel to the horizontal plane H1 toward the light-releasing surface by the side surface 16S, the light extraction efficiency of the micro-light-emitting element 100 can be improved. In addition, the inclination angle θe may be different for each of the multiple side surfaces 16S of the main body 16. In this case, it is more preferable that there are multiple inclination angles θe, and all of the inclination angles θe are greater than or equal to 30° and less than or equal to 80°. Preferably, the side surface of the dummy main body 16D is also inclined in the same manner as the side surface 16S.

[0100] After forming the dividing grooves 15, Figure 4 As shown in step L5 of the embodiment, a transparent insulating film 17 is laminated to cover the exposed portion of the N-side layer 11, the light-emitting layer 12, the P-side layer 13, and the adhesive layer 19. Here, a 400 nm thick SiO2 layer is laminated by CVD (Chemical Vapor Deposition). 2 The transparent insulating film 17 may be made of SiN, SiON or SiCO instead of SiO. 2A film may be used as the transparent insulating film 17, or a laminated film of these films may be used as the transparent insulating film 17. In order to make the thickness of the transparent insulating film 17 covering the side surface of the micro light-emitting element 100 uniform, the transparent insulating film 17 is preferably formed by a CVD method.

[0101] After laminating the transparent insulating film 17, as Figure 4 As shown in step L6 of the embodiment, an opening is provided in the transparent insulating film 17. In the pixel region 1, an N contact hole 18N is provided in the upper part of the body 16 to expose the surface of the N-side layer 11. In the P connection region 3, a P connection hole 18P is provided around the bottom of the dummy body 16D to expose the adhesive layer 19. The opening can be provided by combining ordinary photolithography technology and dry etching technology.

[0102] Then, if Figure 5 As shown in step L7 of the embodiment, the metal layer 20L is stacked in a manner covering the main body 16, the dummy main body 16D, the side surface 16S, the dividing groove 15, the bottom of the P contact groove 15P, etc. The stacking of the metal layer 20L can be formed by sputtering or evaporation. The metal layer 20L contacts the N-side layer 11 in the N contact hole 18N, and contacts the adhesive layer 19 in the P connection portion hole 18P.

[0103] Then, if Figure 5 As shown in step L8, in the pixel region 1, the metal layer 20L at the bottom of the dividing groove 15 is removed, and the metal layer 20L is divided for each micro-light-emitting element 100. As a result, an N electrode 23N is formed on the main body of the micro-light-emitting element 100, and a reflective material 20 is formed in a manner covering the compound semiconductor layer 14. In this embodiment, the N electrode 23N and the reflective material 20 are connected to each other and are made of the same material.

[0104] In the P connection region 3, at least the region covering the P connection hole 18P is left from the upper part of the dummy body 16D, and the metal layer 20L is removed. Thus, the P electrode 23P covering the upper part of the dummy body 16D from the P connection hole 18P is formed. The P connection hole 18P becomes the connection part 40. A part of the metal layer 20L can be removed by combining the ordinary photolithography technology and the dry etching technology. Alternatively, the metal layer 20L can be laminated and a part removed at the same time by using a lift-off method.

[0105] Then, if Figure 5As shown in step L9, in the pixel region 1, the transparent insulating film 17 at the bottom of the dividing groove 15 is removed. The transparent insulating film 17 in the region between the reflective materials 20 of the adjacent micro-light-emitting elements 100 is removed. Thus, it is possible to prevent the occurrence of optical crosstalk between the adjacent micro-light-emitting elements 100 via the transparent insulating film 17. In addition, this step can be omitted when the transparent insulating film 17 is thinner than the emission wavelength of the micro-light-emitting element 100 or when optical crosstalk occurs.

[0106] Then, if Figure 5 As shown in step L10, a filler material 60 is disposed around the main body 16 and the dummy main body 16D. The surfaces of the N electrode 23N and the P electrode 23P must be exposed. Preferably, the filler material 60 is filled between the main bodies 16 and between the main body 16 and the dummy main body 16D.

[0107] Preferably, the embedding material 60 has a light shielding property to prevent optical crosstalk. Since optical crosstalk occurs on the cut surface of the transparent insulating film 17 at the bottom of the embedding material 60, a two-layer structure can be configured in which the cut surface of the transparent insulating film 17 at the bottom of the embedding material 60 is covered with a light shielding material and a transparent material is configured thereon. In addition, when the transparent insulating film 17 is thinner than the emission wavelength of the micro-light-emitting element 100 and when optical crosstalk is allowed, the embedding material 60 can also be a light-transmitting material.

[0108] In the manufacturing process of this structure, the embedding material 60 is formed on the LED processing substrate 10, but the embedding material 60 may also be formed on the driving circuit substrate 50. Figure 5 In the state of step L9, the embedding material 60 can be formed after the LED processing board 10 is bonded to the driving circuit substrate 50 and peeled off.

[0109] [Manufacturing process of image display element 200]

[0110] Next, use Figures 6 to 8 Steps N1 to N9 illustrate the manufacturing process of the image display element 200. Figure 6 to Figure 8 Schematic cross-sectional views showing the manufacturing process of the image display element 200 according to the first embodiment of the present invention. In the description of the manufacturing process of the image display element 200, the LED processing substrate 10 side is the upper side and the driving circuit substrate 50 side is the lower side.

[0111] First, if Figure 6As shown in step L1, the drive circuit substrate 50 is manufactured. The drive circuit substrate 50 is formed, for example, on a single crystal silicon substrate (wafer) by a conventional CMOS (Complementary metal-oxide semiconductor) process. Here, the micro-light emitting element 100 and the drive circuit substrate 50 may be in a wafer state, and the micro-light emitting element 100 may be monolithic per image display element 200. In addition, both the micro-light emitting element 100 and the drive circuit substrate 50 may be monolithic per image display element 200.

[0112] like Figure 6 As shown, for example, the driving circuit substrate 50 is separated by a groove element separation region 76 on a silicon substrate 71, a gate electrode 72, a contact plug 73, a through-hole plug 74, an interlayer insulating film 75, and a silicon substrate 71, and has a diffusion layer 77 including a source 78 and a drain 79. The contact plug 73 electrically connects the gate electrode 72 and the first wiring layer, and electrically connects the diffusion layer 77 and the first wiring layer. The through-hole plug 74 is electrically connected to the first wiring layer and the second wiring layer. In addition, since the driving circuit substrate 50 is manufactured using a well-known technology, its function and structure will not be described in detail. In addition, in Figure 6 Figure after step N2 ( Figure 6 to Figure 8 In the steps N2 to N9 in FIG. 1 , only the N driving electrode 51 and the P driving electrode 52 are shown on the driving circuit substrate 50 , and other structures are omitted.

[0113] After manufacturing the driving circuit substrate 50, Figure 6 As shown in step N2, the micro light-emitting element 100 in the pixel region 1 and the dummy element 101 and the driving circuit substrate 50 in the P connection region 3 are bonded together. At this time, the N electrode 23N and the P electrode 23P are precisely aligned so as to overlap with the corresponding N driving electrode 51 and P driving electrode 52, respectively.

[0114] Depending on the material of the bonding surface between the micro-light emitting element 100 and the driving circuit substrate 50, the two wafers are bonded together by plasma surface cleaning, activation by ion radiation, heating and pressurization. Figure 6 As shown in step N3, the LED processing substrate 10 is removed and the adhesive layer is also removed.

[0115] like Figure 7As shown in step N4, the common P electrode 30 is stacked to cover the P side layer 13, the transparent insulating film 17, the buried material 60 and the exposed portion of the connection portion 40. Here, for example, an ITO film is used as the common P electrode 30. Preferably, in order to reduce light absorption and avoid optical crosstalk through the common P electrode 30, the common P electrode 30 is as thin as possible, and preferably, the thickness of the common P electrode 30 is 10nm to 300nm.

[0116] Then, if Figure 7 As shown in step N5, a metal layer 34L is deposited, and as Figure 7 As shown in step N6, the metal layer 34L is etched using photolithography and dry etching techniques to form the partition wall 34. The portion where the metal layer 34L is removed becomes the opening 37, and light propagates up and down through the opening 37. The partition wall 34 can also be formed by a lift-off method.

[0117] By controlling the side wall inclination angle of the photoresist and the anisotropy of the dry etching in this process, the inclination angle θw of the partition wall side surface 34S of the partition wall 34 can be controlled to various values. Figure 7 As in the P connection area 3 shown in step N6 of the embodiment, most of the metal layer 34L can be retained and used as a part of the common P electrode 30. In the pixel area 1, since the metal layer 34L is connected vertically and horizontally (vertical direction and left-right direction of the paper) and retained as the partition wall 34, the wiring resistance of the common P electrode 30 can be reduced even if the ITO film is very thin.

[0118] Then, if Figure 8 Process N7~ Figure 8 As shown in step N9, the transparent portion 31, the green wavelength conversion layer 33 and the red wavelength conversion layer 32 are sequentially formed on the upper portion of the micro-light emitting element 100 divided by the partition wall 34. The formation order of each is not limited to Figure 8 The transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 are prepared as positive resist materials or negative resist materials, respectively, and patterned by photolithography technology, or patterned by printing technology such as inkjet printing and screen printing. Nanoparticles, etc., which absorb blue light as excitation light and convert it into red light or green light, or phosphors, quantum dots, or quantum rods, etc., can be applied to the red wavelength conversion layer 32 and the green wavelength conversion layer 33.

[0119] Although not shown in the figure, after the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 are formed, a silicon nitride film, a SiO2 film, and a SiO2 film are disposed on the surfaces of the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33. 2 Film, silicone resin, etc. are used as passivation materials. Thus, moisture and oxygen can be blocked.

[0120] [Luminous efficiency of micro-light emitting device 100]

[0121] The luminous efficiency of the micro-light-emitting element 100 formed as described above was evaluated. In the evaluated micro-light-emitting element 100, the configuration pitch was 10 μm, the shape was square, the inclination angle θe was 45°, the thickness of the P-side layer 13 was 200 nm, and the thickness of the N-side layer 11 after grinding was 3 μm. In addition, the size of the upper surface of the N-side layer 11 was 8 μm×8 μm. The thickness of the transparent portion 31 was 2.5 μm, the inclination angle θw of the partition wall side 34S was 70°, and the refractive index of the transparent resin was 1.6. In addition, the N-side layer 11 was mainly a GaN layer, the light-emitting layer 12 was a multiple quantum well layer made of InGaN and GaN, and the peak wavelength of the light emitted from the light-emitting layer 12 was 450 nm. The P-side layer 13 was mainly a GaN layer. On the side 16S of the main body 16, there was a 400nm SiO 2 The film is configured with an aluminum film, and an aluminum film is also configured on the bottom surface. The reflective material 20 and the N electrode 23N are both configured with an aluminum film on the main body side. The material of the partition wall side surface 34S is also an aluminum film.

[0122] In addition, for comparison, the main body 16 has a rectangular parallelepiped shape and the existing micro light-emitting element (corresponding to Fig.10 The Q1 in FIG. 1 and the main body shape are the same as those of the micro-light-emitting element 100, but the light-emitting layer 12 is arranged on the side opposite to the light-releasing surface (corresponding to Fig.10 In either case, the size of the light-releasing surface is set to 8 μm×8 μm, and the same material is used as the compound semiconductor layer 14. Except for the difference in shape and the position of the light-emitting layer 12, the constituent materials and the formation process are the same. However, in the case of a rectangular parallelepiped shape, the dividing groove 15 is processed in a manner that is not inclined as much as possible.

[0123] A transparent resin layer (transparent portion 31) is disposed on the upper surface of the micro-light emitting element 100. In addition, 10,000 micro-light emitting elements 100 are disposed in 100 rows × 100 columns, and the 10,000 micro-light emitting elements 100 are lit at the same time to evaluate the total luminous flux intensity. The current flowing through one micro-light emitting element 100 is 5 μA. The same is true for the comparative structure.

[0124] Fig. 9 : is a schematic cross-sectional view of a simulated structure (inverted quadrangular pyramid structure) simulating the first embodiment of the present invention. Fig. 9, the main body 16 and the transparent portion 31 of the micro-light emitting element 100 are shown. In addition, as described above, the inclination angle θw is the angle formed by the partition wall side surface 34S and the upper surface of the common P electrode 30, but Fig. 9 and Fig.10 The common P electrode 30 is omitted. Fig. 9 and Fig.10 , the tilt angle θw is shown as the angle formed by the light emitting surface parallel to the common P electrode 30 and the partition wall side surface 34S. The body 16 has a shape of a quadrangular pyramid inverted upside down, and the light emitting layer 12 is arranged on the light emitting surface side.

[0125] Fig.10 The components Q1 and Q2 in the simulation are used to Fig. 9 Schematic cross-sectional view of the comparative structure. Specifically, Fig.10 The configuration Q1 is an example of a conventional type of micro light emitting element for comparison, in which the main body 16 has a rectangular parallelepiped shape and the light emitting layer 12 is on the bottom surface side. Fig.10 The composition Q2 is when the shape of the main body 16 is Fig. 9 The shape of the same and the light-emitting layer 12 is on the bottom side. Fig. 9 The micro-light emitting element shown is Fig.10 The composition of Q1 and Fig.10 The micro light-emitting element of the composition Q2 is compared.

[0126] The measurement results are shown in Table 1 below.

[0127] [Table 1]

[0128]

[0129]

[0130] As shown in Table 1, in this structure, there is an inverted quadrangular pyramid structure (corresponding to Fig. 9 ), and the simple rectangular structure (corresponding to Fig.10 Compared with Q1), about 2 times the external quantum efficiency can be obtained. For the inverted tetrahedral pyramid structure having the light-emitting layer 12 on the side opposite to the light-releasing surface (corresponding to Fig.10 Q2), and an external quantum efficiency of about 1.6 times can also be obtained.

[0131] Table 2 shows the results of simulating light extraction efficiency using the ray trace method. The estimated internal quantum efficiency values ​​in Table 1 are estimated values ​​calculated using the light extraction efficiency in Table 2 and the external quantum efficiency in Table 1. The values ​​shown in Table 2 are simulated values.

[0132] [Table 2]

[0133]

[0134]

[0135] The light extraction efficiency represents the ratio of the amount of light released into the air through the transparent resin layer (transparent portion 31) disposed on the upper surface of the micro-light-emitting element 100, and the body side absorption represents the amount of light absorbed by the reflective material 20 (see Figure 1 ). The absorption amount on the lower surface of the body indicates the ratio of the amount of light absorbed on the lower surface side of the micro-luminescent element 100, and the absorption amount inside the body indicates the ratio of the amount of light absorbed inside the body 16. The absorption amount on the side of the transparent portion indicates the ratio of the amount of light absorbed in the side 34S of the partition wall of the transparent portion 31. The average number of reflections inside the body indicates the average number of reflections inside the body 16 of the light emitted from the light-emitting layer 12 before being released into the transparent portion 31 or absorbed. The average number of reflections in the transparent portion indicates the average number of reflections before the light incident on the transparent portion 31 is released into the air or absorbed by the side 34S of the partition wall and returns to the body 16.

[0136] The tendency of the light extraction efficiency in Table 2 is very consistent with the tendency of the external quantum efficiency in Table 1, and the difference in external quantum efficiency is considered to be the main reason for the difference in light extraction efficiency. Only light incident on the upper surface of the micro-light-emitting element 100 at an angle below the critical angle of total reflection (critical total reflection angle) is released to the outside from the upper surface of the micro-light-emitting element 100. In the case where light is incident from GaN constituting the body 16 onto the transparent resin of the transparent portion 31, the critical angle of total reflection is about 37°.

[0137] exist Fig.10 In the rectangular parallelepiped structure constituting Q1, the incident angle to the upper surface of the micro-light-emitting element 100 is the same regardless of the number of reflections inside the main body 16. Therefore, the light emitted from the light-emitting layer 12 in the horizontal direction will not be released to the outside. Fig. 9 and Fig.10 In the quadrangular pyramid structure constituting Q2, light emitted from the light-emitting layer 12 in the horizontal direction is reflected upward by the side surface 16S, and is incident on the light-releasing surface at an angle below the critical angle of total reflection, and is released to the outside.

[0138] Further, even when the light is not released to the outside in the initial state when the light is emitted from the light emitting layer 12, the incident angle of the light emitted from the light emitting layer 12 onto the upper surface of the micro-light emitting element 100 changes each time the light is reflected by the side surface 16S. Therefore, the light emitted from the light emitting layer 12 is released to the outside after repeating internal reflection in the body 16. Fig. 9 and Fig.10 The tetrahedral pyramid structure that constitutes Q2 can significantly improve the light extraction efficiency.

[0139] exist Fig.10 In the configuration Q2 of the present embodiment, Fig. 9 The external quantum efficiency is significantly lower than that of the light extraction efficiency of the structure). This is believed to be due to Fig. 9 Compared with the structure of the embodiment, the area of ​​the light emitting layer 12 is reduced, so the internal quantum efficiency is reduced. As the area is reduced, the current density increases, and the internal quantum efficiency is reduced due to the droop effect. In addition, when the body 16 is processed, crystal defects may occur and the internal quantum efficiency may be reduced. In the structure of this embodiment, such problems can be reduced and high performance can be achieved.

[0140] (Influence of the transparent insulating film 17)

[0141] Next, in order to adjust the influence of the transparent insulating film 17, the dependence of the light extraction efficiency on the thickness of the transparent insulating film 17 in the micro-light emitting element 100 according to the first embodiment of the present invention was simulated. Fig.11 The curve R1 shows the use of SiO 2 The result when it is used as the transparent insulating film 17. Fig.11 The curve R1 is a graph showing the simulation result of the dependence of the light extraction efficiency on the film thickness of the transparent insulating film 17 .

[0142] exist Fig.11 In the graph R1 of FIG. 1 , the horizontal axis is the film thickness of the transparent insulating film 17, and the vertical axis represents the percentage of each graph. When the transparent insulating film 17 is not provided, the light extraction efficiency (release amount in the air) is 32%. Therefore, the rectangular parallelepiped structure ( Fig.10 Compared with the structure Q1), the light extraction efficiency is higher in the tetrahedral pyramid structure without the transparent insulating film 17, and it is shown that the shape of the main body 16 is very important.

[0143] As the thickness of the transparent insulating film 17 increases, the light extraction efficiency increases, but there is little change when the thickness of the transparent insulating film 17 is 400 nm or more. Therefore, it is most preferred that the thickness of the transparent insulating film 17 is 400 nm or more, but since the reduction rate of the light extraction efficiency is within 5% even if the thickness is 75 nm or more, the thickness only needs to be at least 75 nm or more.

[0144] In summary, it is considered that the effect of the transparent insulating film 17 is to improve the light extraction efficiency by increasing the reflectivity on the side surface 16S of the micro-light-emitting element 100. In addition, in the rectangular parallelepiped structure, the effect of the transparent insulating film 17 is very weak. This is considered to be that even if the reflectivity of the side surface of the micro-light-emitting element of the rectangular parallelepiped structure is improved, the angle of incidence on the upper surface of the micro-light-emitting element does not change, and the light totally reflected on the upper surface is totally reflected no matter how many times it is repeatedly reflected, and the light extraction efficiency is not improved. Therefore, in the present embodiment, it is important that the micro-light-emitting element 100 has the side surface 16S, which can change the incident angle of the micro-light-emitting element 100.

[0145] Fig.11 Graph R2 shows the results of studying the change in light extraction efficiency at the tilt angle θe relative to the side surface 16S using the simulation. The size of the light release surface, i.e., the upper surface of the main body 16, is 8 μm×8 μm, the thickness of the N-side layer 11 is 3 μm, and the thickness of the P-side layer 13 is 200 nm. The transparent portion 31 has Fig. 9 Same conditions.

[0146] Fig.11 The horizontal axis of the graph R2 represents the inclination angle θe, and the vertical axis represents the percentage of each graph. Fig.11 As shown in the curve R2, as the inclination angle θe of the side surface 16S decreases from 90°, the amount of light released into the air increases, reaching a peak value near 55°, a minimum value near 45°, and increasing below 45°.

[0147] From these results, it is found that when the inclination angle θe is 80° or less, the micro-luminescent element 100 of the first embodiment of the present invention achieves a light release amount into the air of at least 25%. This is about 1.3 times that of the rectangular structure shown in Table 2. Further, if the inclination angle θe is 70° or less, a light release amount into the air of more than 40% can be achieved. Further, between 50° and 65°, a light release amount into the air of at least 45% can be achieved. In addition, below 40°, a light release amount of more than 50% can be achieved.

[0148] In the micro-light emitting element 100 of the first embodiment of the present invention, the side surface 16S of the main body 16 is inclined and covered with the reflective material 20. Therefore, optical crosstalk between the micro-light emitting elements 100 can be prevented, and the light extraction efficiency can be significantly improved. Furthermore, by configuring the transparent insulating film 17 between the side surface 16S and the reflective material 20, the light extraction efficiency can be further improved.

[0149] (Conversion efficiency of the red wavelength conversion layer 32)

[0150] Next, the red sub-pixel 7 (see Figure 2 ). The red wavelength conversion layer 32 absorbs the blue light emitted by the micro-light-emitting element 100R, converts the wavelength into red light, and releases it to the outside. The absorption distribution of the blue light inside the red wavelength conversion layer 32 is simulated, red light is generated according to the absorption distribution, and the light extraction efficiency of releasing the generated red light into the air is simulated. The conversion efficiency of converting blue light into red light (internal quantum efficiency of the conversion material) is highly material-dependent, so it is assumed to be 100% in the simulation. Fig.12 The red wavelength conversion layer 32 is used instead of Fig. 9 , Fig.10 The composition of Q1 and Fig.10 The result of simulating the dependency of the side surface 16S on the inclination angle θe is obtained by using the transparent portion 31 constituting Q2. Fig.12 The horizontal axis represents the tilt angle θe, and the vertical axis represents the efficiency. The thickness of the red wavelength conversion layer 32 is 2.5 μm, the tilt angle θw of the partition wall side 34S is 70°, the complex refractive index of blue light is 1.713±0.023i, and the complex refractive index of red light is 1.671±0.0i. It is set to be non-absorbent for red light.

[0151] Table 3 shows the Fig. 9 , Fig.10 The composition of Q1 and Fig.10 Simulation results of the structure constituting Q2.

[0152] [Table 3]

[0153]

[0154] The blue light absorption amount (A) indicates the proportion of blue light absorbed by the red wavelength conversion layer 32 in the light generated by the main body 16. The red light extraction efficiency (B) indicates the proportion of red light released into the air in the red light generated in the red wavelength conversion layer 32. The red light release efficiency (C) is the product of (A) and (B), and indicates the efficiency with which blue light is converted into red light and released into the air. The blue light leakage amount (D) indicates the proportion of blue light that is not absorbed by the red wavelength conversion layer 32 and is directly released into the air.

[0155] and Fig.10Compared with Q1, Fig. 9 and Fig.10 The blue light absorption (A) of Q2 is more than twice as large. Fig. 9 and Fig.10 The side surface 16S of Q2 is tilted, and the blue light is effectively captured in the red wavelength conversion layer 32 and absorbed. This is the same as the case of the transparent portion 31. Fig.10 Compared with Q1, Fig. 9 and 10 The red light extraction efficiency (B) of Q2 is also higher by more than 15%. This indicates that, among the red light generated in the red wavelength conversion layer 32, the red light entering the body 16 is returned to the red wavelength conversion layer 32 with higher efficiency. That is, due to the inclination of the side surface 16S, the red light is also captured from the body 16 to the red wavelength conversion layer 32.

[0156] Due to Fig.10 Compared with Q2 Fig. 9 The blue light absorption (A) is slightly smaller, so the red light emission efficiency (C) is also slightly smaller. However, as can be seen in the case of blue light, Fig.10 In Q2, the reduction in the area of ​​the light-emitting layer 12 leads to a decrease in the internal quantum efficiency, so in fact, it can be expected that Fig. 9 The red light emission efficiency is high.

[0157] The red light emission efficiency (E) taking the internal quantum efficiency into consideration is the product of the estimated internal quantum efficiency value in Table 1 and the red light emission efficiency (C). Fig. 9 Can be achieved relative to Figure 8 The efficiency of Q2 is 1.8 times. In addition, Fig. 9 The advantage is that Fig.10 Compared with Q2, the blue light leakage (D) is small. The leakage of blue light from the red sub-pixel 7 reduces the color purity of red, so it must be reduced by absorption by a color filter or reflection by a dielectric multilayer film. This absorption or reflection of blue light has the side effect of reducing the release amount even for red light. If the blue light leakage (D) is small, the side effect can be reduced.

[0158] Fig.12 Indicated in Fig. 9 The results of simulating the dependence of the inclination angle θe of the side 16S in the structure are shown in FIG. Fig.12As shown, as the tilt angle θe decreases, the amount of blue light absorbed (A) in the red wavelength conversion layer 32 increases. This tendency is similar to the efficiency of releasing blue light from the transparent portion 31 into the air. On the other hand, the red light extraction efficiency (B) peaks at a tilt angle θe of 55°. About two-thirds of the red light generated in the red wavelength conversion layer 32 is incident on the body 16, but most of the red light incident on the body 16 is reflected inside the body 16 and returns to the red wavelength conversion layer 32. Since the efficiency of returning from the body 16 to the red wavelength conversion layer 32 has the same value as that of the red light generated in the red wavelength conversion layer 32, the red light absorption rate (A) in the red wavelength conversion layer 32 is increased. Fig.11 , it is estimated that the peak appears near 55° because the angle dependence is similar to that of the graph R2 in FIG. However, since the red light is incident from the red wavelength conversion layer 32 toward the body 16, even if the tilt angle θe is large, the red light is reflected by the bottom of the body 16 and returns to the red wavelength conversion layer 32. Therefore, the probability of returning from the body 16 to the red wavelength conversion layer 32 is high, and the tilt angle θe dependence becomes weak.

[0159] When the tilt angle θe is less than 60°, the red light emission efficiency (C) of 30% or more can be achieved. Fig.11 The amount of blue light released into the air in the graph R2 is calculated, and the tilt angle θe is preferably less than 60°. In addition, as the tilt angle θe decreases, the amount of blue light released into the air, i.e., the amount of blue light leakage (D), increases, but it is not a big problem if it is less than about 5%. Color filters can also absorb blue light.

[0160] [Second embodiment]

[0161] [Configuration of Image Display Element 200a]

[0162] The following uses Figures 13 to 19 A second embodiment of the present invention is described. In addition, for the sake of convenience, components having the same functions as those described in the first embodiment are assigned the same reference numerals, and their descriptions are not repeated. The image display element 200a of the second embodiment is different from the image display element 200 of the first embodiment in the shape of the main body 16a of the micro-luminescent element 100a, the structure of the partition wall 34a, and the structure of the common P electrode 30a.

[0163] In this embodiment, if Fig.13 As shown, the side surface 16Sa of the main body 16a of the micro-light-emitting element 100a has a first side surface 16Sa1 and a second side surface 16Sa2. The first side surface 16Sa1 is located at the bottom side of the side surface 16Sa, and a first inclination angle θe1 ​​is formed by the light-releasing surface of the main body 16a and the first side surface 16Sa1. The first inclination angle θe1 ​​is 70° or less, and preferably in the range of 30° to 60°.

[0164] The second side surface 16Sa2 is located on the light release direction side of the side surface 16Sa, and the light release surface of the main body 16a and the second side surface 16Sa2 form a second tilt angle θe2. The second tilt angle θe2 is greater than 60°, preferably greater than 70°. That is, the micro-light emitting element 100a is configured in such a way that the second tilt angle θe2 is greater than the first tilt angle θe1.

[0165] In addition, preferably, the thickness th1 of the body 16a at the first tilt angle θe1 ​​portion is 2 μm or less, and the thickness th2 of the body 16a at the second tilt angle θe2 portion is 2 μm or more. Since it is difficult to process a thick compound semiconductor layer 14 on the tilted surface at the first tilt angle θe1, setting the second tilt angle θe2 portion in this way facilitates manufacturing when the body 16a is relatively thick.

[0166] Furthermore, in the configuration of this embodiment, the partition wall 34a is made of SiO 2 The partition wall substrate 35 is made of an inorganic material such as SiN or a resin material such as a photoresist material, and a partition wall reflective film 36 (second reflective material). The partition wall reflective film 36 is a high reflectivity metal film or the like.

[0167] Similar to the first embodiment, the partition wall side surface 34S is formed of a high reflectivity metal film, and the opening 37a of the partition wall reflective film 36 is located inside the inner edge of the upper end of the reflective material 20, and the opening 37a covers the light release surface of the body 16a.

[0168] When the metal layer 34L is deposited as in the first embodiment (see Figure 7 Process N5 and Figure 7 In the process N6), when processing the partition wall 34 with an inclined surface by photolithography and dry etching technology, a metal layer 34L higher than the height of the partition wall 34 must be deposited. Since the height of the partition wall 34 can be several μm, a very thick metal layer 34L is required, but the surface of such a thick metal layer 34L has large unevenness and is difficult to align accurately with the underlying layer. In the present invention, the bottom of the partition wall 34 needs to cover the upper end of the reflective material 20, and as the pixel size of the image display element 200 becomes smaller, the partition wall 34 needs to be accurately aligned with the reflective material 20. Here, in the present embodiment, the central portion of the partition wall 34a (partition wall substrate 35) is formed by a material that is easy to align accurately, has few surface unevenness and is transparent, and its surface is covered by a partition wall reflective film 36 to avoid the above problems.

[0169] In addition, in this embodiment, the common P electrode 30a is composed of a partition wall reflective film 36 and a transparent electrode 38. The partition wall reflective film 36 and the transparent electrode 38 are conductive. By connecting the pixel area 1 and the P connection area 3, as well as between the pixels 5 and between the sub-pixels, the wiring resistance of the common P electrode 30a can be reduced through the partition reflective film 36 which is a good conductor. Since the transparent electrode 38 is mainly connected to the P side layer 13 of the main body 16a and the partition wall reflective film 36, the transparent electrode 38 can be made thinner, the light absorption caused by the transparent electrode 38 can be reduced, and the light output can be improved.

[0170] [Method for manufacturing micro light emitting element 100a]

[0171] Next, use Figure 14-15 Steps S1 to S5 of the present invention are used to explain the method for manufacturing the micro-light emitting element 100a. Figure 3 Process L1~ Figure 3 After step L3, Fig.14 As shown in step S1, a dividing groove 15a is formed. A first side surface 16Sa1 having a first inclination angle θe1 ​​is formed at the upper portion of the dividing groove 15a, and a second side surface 16Sa2 having a second inclination angle θe2 is formed at the lower portion. Therefore, the side surface 16Sa includes a first side surface 16Sa1 and a second side surface 16Sa2 having different inclination angles θe. In the P connection region 3, a P contact groove 15Pa is formed, and a dummy body 16Da is formed in the same cross-sectional shape as the micro-light-emitting element body 16a. However, the dummy body 16Da may also be continuous in the vertical direction of the paper.

[0172] like Fig.14 As shown in step S2, a transparent insulating film 17 is deposited, and as Fig.14 As shown in step S3, an N contact hole 18N and a P connection hole 18P are formed. Fig.15 As shown in step S4, a metal layer 20L (metal layer for reflective material) is deposited, and as Fig.15 As shown in step S5, the metal layer 20L is processed to form the N electrode 23N, the reflective material 20 and the P electrode 23P. Fig.15 As shown in step S5, the metal layer 20L is processed so as to cover the cut surface of the transparent insulating film 17 at the bottom of the dividing groove 15a. Thus, the metal layer 20L can prevent light from leaking through the transparent insulating film 17. Therefore, optical crosstalk between the micro-light-emitting elements 100a can be prevented.

[0173] [Method for manufacturing image display element 200a]

[0174] Next, use Figure 16 to Figure 18Steps T1 to T8 of the present embodiment will be used to explain the method for manufacturing the image display element 200a. In the configuration of this embodiment, unlike the first embodiment, the embedding material 60a is formed after the micro light emitting element 100a is bonded to the driving circuit substrate 50. Fig.16 Step S1 and Fig.16 The process S2 is respectively Figure 6 Process N2 and Figure 6 The same as step N3. Fig.16 As shown in step T3, a filler material 60a is formed. The filler material 60a is an insulating material, and may be a transparent resin. This is because the cut surface of the transparent insulating film 17 is covered by the metal layer 20L, so that light is unlikely to leak through the filler material 60a.

[0175] Then, if Fig.17 As shown in step T4, a partition wall substrate 35 is formed between sub-pixels in the pixel region 1. The partition wall substrate 35 can be formed of, for example, a negative resist. Alternatively, SiO can be deposited and processed by photolithography and dry etching techniques. 2 Preferably, the side wall of the partition wall substrate 35 is controlled to form a predetermined inclination angle θw. In addition, the inclination angle θw in the second embodiment and the third embodiment is an angle formed by the extension line of the light release surface of the main body 16a of each micro-light-emitting element 100a and the partition wall side 34S. The bottom of the partition wall substrate 35 needs to cover the upper end of the reflective material 20. The bottom side of the partition wall substrate 35 can also be formed of a light-shielding material. In this way, light can be prevented from leaking through the partition wall substrate 35.

[0176] Furthermore, if Fig.17 As shown in step T5, a partition wall reflective film 36 is deposited. At this time, in the P connection region 3, the partition wall reflective film 36 and the P electrode 23P are connected at the connection portion 40. The partition wall reflective film 36 is similar to the reflective material 20, and the partition wall reflective film 36 is preferably a metal thin film having high reflectivity with respect to visible light or a material having the same properties.

[0177] Then, if Fig.17As shown in step T6, the partition wall reflective film 36 is provided with an opening 37a at a portion overlapping with the light release surface of the main body 16a when viewed from above. The opening 37a can be formed by photolithography technology and wet or dry etching technology. The opening 37a is preferably located on the inner side of the micro-light-emitting element 100a compared to the upper end of the reflective material 20 when viewed from above. In addition, in order to facilitate the reciprocation of light between the micro-light-emitting element 100a, the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33, the opening 37a preferably occupies as wide a range as possible within the range of the light release surface of the micro-light-emitting element 100a. In particular, the opening 37a preferably overlaps with the entire light release surface of the main body 16a.

[0178] Then, if Fig.18 As shown in step T7, a transparent electrode 38 is deposited. The transparent electrode 38 is formed of the same material as the common P electrode 30 of the first embodiment. The subsequent steps are the same as those in the first embodiment, such as Fig.18 As shown in step S8, the transparent portion 31, the red wavelength conversion layer 32, and the green wavelength conversion layer 33 are sequentially formed. Fig.17 In the cross-sectional view of step T6, the end of the partition reflective film 36 covers a portion of the light-releasing surface of the main body 16a. In this case, the transparent electrode 38 can be omitted by making the partition reflective film 36 and the P-side layer 13 conductive.

[0179] Table 4 shows the configuration corresponding to this embodiment. Fig.19 The results of the simulated light extraction efficiency are shown. Fig.19 In the structure shown in the figure, the same as that corresponding to the first embodiment is obtained. Fig. 9 In the configuration of this embodiment, since the inclination angle near the side of the light-emitting layer 12 is large, the area of ​​the light-emitting layer 12 can be made larger than that of the first embodiment. In addition, although the second inclination angle θe2 is greater than 70° in the above description, Fig.19 In order to simplify the description, the second inclination angle θe2 is set to 70°.

[0180] [Table 4]

[0181]

[0182]

[0183] As described above, also in the configuration of the image display element 200 a , the same effects as those of the first embodiment can be achieved.

[0184] [Third embodiment]

[0185] [Configuration of Image Display Element 200b]

[0186] use Fig. 20 The third embodiment of the present invention is described. In addition, for the sake of convenience, the same reference numerals are given to components having the same functions as those described in the above embodiment, and their description is not repeated. The image display element 200b of the third embodiment has a similar structure to that of the second embodiment, but the shape of the main body 16b is different.

[0187] In the second embodiment, the inclination angle is θe1<θe2, and the first side surface 16Sa1 inclined at the small first inclination angle θe1 ​​is arranged on the side opposite to the light release surface side relative to the second side surface 16Sa2 inclined at the large second inclination angle θe2. On the other hand, in the present embodiment, the first side surface 16Sb11 inclined at the small first inclination angle θe11 is arranged on the light release surface side relative to the second side surface 16Sb12 inclined at the large second inclination angle θe12.

[0188] In more detail, the first side surface 16Sb11 is located on the light release direction side of the side surface 16Sb, and a first inclination angle θe11 is formed by the light release surface of the main body 16b and the first side surface 16Sb11. The first inclination angle θe11 is 70° or less, preferably in the range of 30° to 60°. In addition, the second side surface 16Sb12 is located on the bottom side of the side surface 16Sb, and a second inclination angle θe12 is formed by the light release surface of the main body 16b and the second side surface 16Sa12. The second inclination angle θe12 is 60° or more, preferably greater than 70°.

[0189] The manufacturing process of this embodiment is the same as that of the second embodiment, except that Fig.14 The shape of the dividing groove 15a is changed in S1 of FIG. Fig.13 As shown, the side surface 16Sa of the main body 16a is processed in such a way that the bottom (driving circuit substrate 50 side) has a small first inclination angle θe1 ​​and the top (light release direction side) has a large second inclination angle θe2. Fig. 20 As shown, the side surface 16Sb of the main body 16b is processed so that the bottom (driving circuit substrate 50 side) has a large second inclination angle θe12 and the top (light release direction side) has a small first inclination angle θe11.

[0190] In this embodiment, by configuring a first side surface 16Sb1 having a first inclination angle θe11 of 30° to 60° near the light-emitting layer 12 on the side surface 16Sb, the light extraction efficiency can be further improved. Table 5 shows the results of simulating the light extraction efficiency in this embodiment. Fig.21In the simulation of the configuration shown in FIG. 1 , a better performance than that of the second embodiment was obtained. Fig.19 The light extraction efficiency is 20% higher than the light extraction efficiency.

[0191] [Table 5]

[0192]

[0193] In Table 5, the second embodiment Fig.19 Compared with the structure of the third embodiment, Fig.21 The structure reduces the average number of reflections in the main body 16b and greatly reduces the amount of light absorbed on the side 16Sb of the main body 16b. This means that the structure of the third embodiment effectively releases light to the transparent portion 31. The reason can be explained as follows. That is, since the light-emitting layer 12 emits light isotropically, most of the light is released in a direction parallel to the light-emitting layer 12. Therefore, by configuring the first side surface 16Sb11 having a first inclination angle θe11 that is smaller than the second inclination angle θe12 of the second side surface 16Sb12 on the light-releasing surface side, light traveling in the horizontal direction is reflected in the direction of the light-releasing surface. In other words, by reducing the inclination angle on the light-releasing surface direction side in the side surface 16Sb, light can be more effectively introduced into the transparent portion 31. As a result, the amount of light released into the air increases.

[0194] In addition, Fig.19 Similarly, to simplify the explanation, Fig.21 , the second inclination angle θe12 is set to 70°.

[0195] As described above, also in the configuration of the image display element 200 b , the same effects as those of the first embodiment can be achieved.

[0196] [Fourth embodiment]

[0197] The following will use Fig. 22 , 23 , Figure 24 to Figure 26 Process U1 to process U9 and Fig. 27 The fourth embodiment of the present invention will be described with reference to steps V1 to V4. For the sake of convenience, components having the same functions as those described in the above embodiment are denoted by the same reference numerals, and their description will not be repeated.

[0198] In the above embodiment, light is released to the side opposite to the driving circuit substrate 50. On the other hand, in the present embodiment, light is released to the driving circuit substrate 50c side. The driving circuit substrate 50c is a transparent substrate. In addition, in the above embodiment, wavelength conversion is performed by using blue light as excitation light to generate red light and green light. On the other hand, in the present embodiment, a red light-emitting compound semiconductor such as InGaAlP or gallium nitride doped with europium (Eu) (GaN:Eu) is used for red light emission, and a green light-emitting compound semiconductor such as InGaAlN is used for green light emission. Further, the micro-light-emitting elements 100c according to the present embodiment are respectively mounted on the driving circuit substrate 50c by the so-called Pick&Place method.

[0199] [Configuration of Image Display Element 200b]

[0200] Fig. 22 Schematic plan view of a pixel 5c constituting the image display element 200c is shown. Fig.23 A schematic cross-sectional view of a mounting portion of the micro light-emitting element 100c is shown. Fig.23 yes Fig. 22 The pixel 5c is provided with a micro-light emitting element 100Rc, a micro-light emitting element 100Gc, and a micro-light emitting element 100Bc, which emit red light, green light, and blue light, respectively.

[0201] A predetermined current is supplied to the micro-light-emitting element 100c through the pixel driving circuit 2. The pixel driving circuit 2 may be a circuit composed of thin-film transistors formed on the driving circuit substrate 50c, or may be a microchip mounted in the same manner as the micro-light-emitting element 100c. The power line Vcc, the ground line GND, the column signal line CS-B, the column signal line CS-R, the column signal line CS-G, and the row selection line RS are wired in the pixel 5c. The N electrode 23Nc of the micro-light-emitting element 100c is connected to the GND line via the N driving electrode 51c. The P electrode 23Pc is connected to the pixel driving circuit 2 via the P driving electrode 52c. In addition, the wiring connecting the power line Vcc, the column signal line CS-B, the column signal line CS-R, the column signal line CS-G and the pixel driving circuit 2 and the row selection line RS are first-layer wiring, and the other wiring is second-layer wiring located above or below the first-layer wiring.

[0202] like Fig.23As shown, the micro-light-emitting element 100c is bonded to the driving circuit substrate 50c composed of a transparent substrate in a manner that the light-releasing surface faces the driving circuit substrate 50c. The light-emitting layer 12 is arranged on the light-releasing surface side, and the side surface 16Sc of the main body 16c is inclined in a manner open to the light-emitting side. The inclination of the side surface 16Sc is the same as that of other embodiments. In addition, the side surface 16Sc is covered by a transparent insulating film 17, and further, its outer side is covered by an N electrode 23Nc and a P electrode 23Pc composed of a high-reflectivity metal film. In addition, in the configuration of this embodiment, the area separating the N electrode 23Nc and the P electrode 23Pc is not covered by the high-reflectivity metal film, but is covered by the P driving electrode 52c. Fig. 22 In the top view shown, the main body 16c is entirely covered by the N electrode 23Nc, the reflective material 20, and the P driving electrode 52c. Even if the reflective property of the P driving electrode 52c is not as good as that of the N electrode 23Nc or ​​the P electrode 23Pc, the area covered by the P driving electrode 52c is small compared to the entire side 16Sc of the micro-light-emitting element 100c, and a sufficient light output improvement effect can be obtained. In addition, by covering the area separating the N electrode 23Nc and the P electrode 23Pc with the P driving electrode 52c, light can be prevented from leaking from the micro-light-emitting element 100c to the back side (the side opposite to the light release direction).

[0203] The micro-light emitting element 100c is different from the micro-light emitting element 100 of another embodiment in that the micro-light emitting element 100c has a P-electrode connecting portion 42. The P-electrode connecting portion 42 is a wiring for connecting the transparent electrode 41 and the P driving electrode 52c. Fig.23 As shown, it contacts the surface of the transparent electrode 41 on the light release direction side and extends from the main body 16c to the outside, and is connected to the P electrode 23Pc at the extended portion.

[0204] [Method for manufacturing micro light emitting element 100c]

[0205] Next, use Figure 24 to Figure 26 Steps U1 to U9 of the present invention illustrate a method for manufacturing the micro-light emitting element 100c. Fig.24 As shown in step U1, similarly to other embodiments, after forming the compound semiconductor layer 14 on the growth substrate 9, the transparent electrode layer 41L and the metal electrode layer 42L are deposited. The transparent electrode layer 41L is electrically connected to the P-side layer 13. Fig.24 As shown in step U2, the P electrode connection portion 42 is retained and the metal electrode layer 42L is removed. The P electrode connection portion 42 is a wiring for connecting the transparent electrode layer 41L and the P electrode 23Pc. In other words, the P electrode connection portion 42 is a part of the wiring connecting the transparent electrode layer 41L and the P driving electrode 52c.

[0206] Then, if Fig.24 As shown in step U3, the structure formed on the growth substrate 9 is bonded to the LED processing substrate 10 via the adhesive layer 19. Fig.25 As shown in step U4, the growth substrate 9 is peeled off. Fig.25 As shown in step U5, the dividing groove 15 is formed. A portion of the P-electrode connecting portion 42 is exposed at the bottom of the dividing groove 15. At this time, the area of ​​the P-electrode connecting portion 42 covering the light-releasing surface of the main body 16c needs to be set to the necessary minimum value to prevent interference with light emission. In addition, the dividing groove 15 must be processed so that the side 16Sc of the main body 16c is appropriately inclined. The transparent electrode layer 41L is preferably thin so that it does not remain at the bottom of the dividing groove 15. As a result, the transparent electrode layer 41L is retained only in the portion in contact with the P-side layer 13 and becomes the transparent electrode 41.

[0207] Next, if Fig.25 As shown in step U6, a transparent insulating film 17 is deposited. Fig.26 As shown in step U7, a contact hole 18N is opened in the transparent insulating film 17 of the main body 16c to expose the N-side layer 11. In addition, a P contact hole 18Pc is opened in the P-electrode connecting portion 42 at the bottom of the dividing groove 15 to expose the P-electrode connecting portion 42.

[0208] Then, if Fig.26 As shown in step U8, a metal layer 20L (highly reflective metal layer) serving as a reflective material is deposited. At this time, the metal layer 20L is connected to the N-side layer 11 through the N contact hole 18N, and is connected to the P-electrode connecting portion 42 through the P contact hole 18Pc. Fig.26 As shown in step U9 of the embodiment, the metal layer 20L is processed into the N electrode 23Nc, the P electrode 23Pc and the reflective material 20. Thus, the micro light-emitting element 100c is formed. In addition, in this configuration, the P electrode 23Pc connected to the P electrode connection portion 42 is formed at the same time as the N electrode 23Nc, but the P electrode 23Nc can be omitted. If omitted, the P electrode connection portion 42 and the P driving electrode 52c are directly connected, and the P electrode connection portion 42 also serves as the P electrode 23Pc. In addition, as Fig. 22 As shown, in the plan view, the main body 16c is entirely covered by the N electrode 23Nc, the reflective material 20, and the P driving electrode 52c, so that light does not leak to the back side.

[0209] [Method for manufacturing image display element 200c]

[0210] Since the formation of the signal line on the driving circuit substrate 50c and the formation of the pixel driving circuit 2 are well known, the description thereof will be omitted, and only the mounting method of the micro-light emitting element 100c will be described. In addition, in the configuration of this embodiment, after the first layer wiring of the driving circuit substrate 50c is formed, the micro-light emitting element 100c is mounted by the Pick & Place method, and after the micro-light emitting element 100c is mounted, the formation of the interlayer insulating film 62 and the formation of the second layer wiring will be described, but the manufacturing method is not limited to this.

[0211] like Fig. 27 As shown in step V1, the micro-light emitting element 100c is mounted and fixed on the driving circuit substrate 50c via the transparent adhesive layer 61. Fig. 27 As shown in step V2, an interlayer insulating film 62 is formed. The adhesive layer 61 is insulating. Fig. 27 As shown in step V3, the N contact hole 63N and the P contact hole 63P are opened on the N electrode 23Nc and the P electrode 23Pc, respectively, so that the surfaces of the N electrode 23Nc and the P electrode 23Pc are exposed. The N contact hole 63N and the P contact hole 63P can be formed simultaneously with the through holes connecting the single-layer wiring and the double-layer wiring of the drive circuit substrate 50c, or they can be formed separately. Fig. 27 As shown in step V4, two layers of wiring are deposited and processed into N driving electrodes 51c and P driving electrodes 52c.

[0212] Thus, the P-side layer 13 is electrically connected to the P driving electrode 52c via the transparent electrode 41, the P-electrode connecting portion 42, and the P-electrode 23Pc. The N-side layer 11 is electrically connected to the N driving electrode 51c via the N-electrode 23Nc.

[0213] As described above, the micro light emitting element 100c is mounted on the transparent driving circuit substrate 50c, and a highly efficient display element can be provided by the driving circuit substrate 50c. According to the configuration of this embodiment, the same effects as those of the first embodiment can be achieved.

[0214] (Variation Example)

[0215] exist Fig.28 and Fig.29 The configurations W1 to W6 of the embodiment show variations of the above-mentioned embodiment. The difference of the variations is that the micro-light emitting element is Fig.28 and Fig.29 In the figure, only the micro-light emitting element portion is shown. Even if the micro-light emitting elements 100 to 100c shown in the first to fourth embodiments are replaced with Fig.28 and Fig.29 The same effects as those of the first embodiment can be obtained by using some different micro-light emitting elements shown in the configurations W1 to W6. Fig.28 and Fig.29 In the embodiment, the transparent electrode 38 is arranged on the P-side layer as a common P-electrode.

[0216] exist Fig.28 In the micro-light emitting element 100d shown in the configuration W1, the side surface 16Sd of the main body 16d is a curved surface. This is a case where the inclination angle of the side surface 16Sd changes continuously, and is equivalent to the case where the side surface 16Sa includes two surfaces with different inclination angles in the second embodiment, and a surface with different inclination angles is added. In the configuration of this embodiment, the same effect as the second embodiment can also be obtained.

[0217] Fig.28 The micro-light emitting element 100e shown in the configuration W2 is a case where the dielectric multilayer film 17e is used as the transparent insulating film 17 in the first embodiment. By using a dielectric multilayer film having a DBR (Distributed Bragg Reflector) function to increase the reflectivity on the side 16Se, light absorption on the side 16Se can be reduced and the light extraction effect can be further improved. In this case, the dielectric multilayer film 17e preferably has a high reflectivity for the light emitted by the micro-light emitting element 100e. Furthermore, it is preferred that the dielectric multilayer film 17e also has a high reflectivity for the light generated by wavelength conversion.

[0218] In addition, Figure 1 different, Fig.28 The composition W2 shows two N contact holes 18Ne, but the number of N contact holes 18Ne may be one or more. When the area of ​​the N contact hole 18 is small relative to the lower surface of the body 16e (the surface on the driving circuit substrate 50 side), light absorption is small and light extraction efficiency is high. Therefore, it is important to reduce the total area of ​​the N contact hole 18, and sometimes it is better to set a plurality of small holes such as the N contact hole 18Ne. For N contact holes with a small diameter and a deep depth, the metal layer 20L can be deposited after the metal plug is embedded (refer to Figure 5 ).

[0219] Fig.28 The micro-light emitting element 100f shown in the constitution W3 is different from the micro-light emitting element of the first embodiment in that a compound semiconductor multilayer film 43 is included in the N-side layer 11e. The compound semiconductor multilayer film 43 has a DBR function. For example, in the case of the compound semiconductor layer 14 shown in the micro-light emitting element 100f, the reflectivity with respect to visible light is improved by stacking a plurality of AlGaN layers and InGaN layers. In this way, a high reflectivity is maintained for light in the visible light range, so that light absorption on the lower surface of the body 16f can be reduced, and the light extraction efficiency can be further improved.

[0220] Fig.29The micro-light emitting element 100g shown in the structure W4 is different from the first embodiment in that the P-side layer 13g includes a compound semiconductor multilayer film 44. The compound semiconductor multilayer film 44 has a DBR function. For example, in the case of the compound semiconductor layer 14 shown in the micro-light emitting element 100g, by stacking a plurality of AlGaN layers and InGaN layers, the compound semiconductor layer 14 has high transmittance with respect to the emission wavelength of the micro-light emitting element 100g, and on the other hand, has high reflectivity with respect to wavelength-converted light. By configuring a film having such characteristics on the light-releasing surface side, it is possible to prevent wavelength-converted light from being incident on the main body 16g and being absorbed by the side 16Sg and bottom surface of the main body 16g, thereby reducing light output.

[0221] Depend on Fig.29 The micro-light emitting element 100h shown in the structure W5 in FIG. 1 is different from the above-mentioned embodiments in that the reflective material 20h and the N electrode 23Nh are separated. In the first to third embodiments, since the reflective material 20 and the N electrode 23N are integrated, it is necessary to prevent the reflective material 20 and the common P electrode 30 from being electrically connected. In the micro-light emitting element 100h, the reflective material 20h and the N electrode 23Nh are separated, so that the reflective material 20h can be in electrical contact with the common P electrode 30 and used as a part of the wiring.

[0222] In addition, in the micro-light-emitting element 100h, an N contact electrode 45 is arranged on the lower surface of the body 16h to connect the N contact electrode 45 and the N electrode 23Nh, but the N contact electrode 45 may be omitted. Preferably, a high-reflectivity metal film is arranged on the surface of the N contact electrode 45 on the body 16h side. When the N contact electrode 45 is omitted, a high-reflectivity metal film is preferably arranged on the surface of the N electrode 23Nh on the body 16h side. By covering the side surface 16Sh with the reflective material 20h and covering the lower surface with the N electrode 23Nh, the body 16h can suppress light leakage from the body 16h to the outside.

[0223] Depend on Fig.29 The micro-light emitting element 100i shown in the configuration W6 in the embodiment 1 is different from the first embodiment in that the P electrode 23Pi is provided in the pixel region 1. The P electrode 23Pi (third electrode) is provided at the periphery of the micro-light emitting element 100i, and the P electrode 23Pi is connected to the common P electrode 30 on the light-releasing surface side. By using the micro-light emitting element 100i, the P driving electrode 52 is provided in the pixel region 1 of the driving circuit substrate 50, and by connecting to the P electrode 23Pi, there is no need to provide an area outside the pixel region 1 for connecting the common P electrode 30 and the P driving electrode 52.

[0224] If a high reflectivity metal film is disposed on the surface of the main body 16i side of the P electrode 23Pi, it is not necessary to extend the N electrode 23Ni to the light release surface side. In this case, the reflective material 20i is composed of two components: the extended portion of the N electrode 23Ni and the P electrode 23Pi. This is also different from the first embodiment.

[0225] [Summarize]

[0226] A micro-luminescent element (100) according to the first embodiment of the present invention comprises: a main body (16), which comprises a compound semiconductor layer (14) on which a first conductive layer (P-side layer 13), a light-emitting layer (12) and a second conductive layer (N-side layer 11) are deposited in sequence from the light-releasing surface side, wherein the second conductive layer has a conductivity type opposite to that of the first conductive layer; a first electrode (common P-electrode 30), which comprises a transparent electrode on the light-releasing surface side; a second electrode (N-electrode 23N), which comprises a metal film on the side opposite to the light-releasing surface side; and a first reflective material (reflective material 20), which covers a side surface (16S) of the main body, wherein the light-emitting layer is arranged on the light-releasing surface side of the main body, the side surface of the main body is inclined in an open manner relative to the light-releasing direction, and the surfaces of the second electrode and the first reflective material on the side of the main body are reflective surfaces for reflecting visible light.

[0227] According to the above configuration, in the micro-light-emitting element, in the body composed of the compound semiconductor layer in which the first conductive layer, the light-emitting layer, and the second conductive layer are stacked, the light-emitting layer is arranged on the light-releasing surface side of the body. Thus, in the micro-light-emitting element tilted so as to be open at the side of the body, the area of ​​the light-releasing surface of the light-emitting layer can be increased compared to the case where the light-emitting layer is arranged on the side opposite to the light-releasing surface side of the body. As a result, the internal quantum efficiency of the micro-light-emitting element can be improved, and the external quantum efficiency can be improved.

[0228] In addition, the side surface of the body is inclined in a manner open relative to the light release direction. Therefore, inside the micro-light-emitting element, light traveling in a direction parallel to the horizontal plane can be reflected toward the light release surface through the side surface of the body. As a result, the light extraction efficiency of the micro-light-emitting element can be improved.

[0229] Furthermore, in the micro-light emitting element, the surfaces of the second electrode and the first reflective material on the main body side are reflective surfaces that reflect visible light. Thus, this can prevent the light emitted by the micro-light emitting element from leaking to the outside of the micro-light emitting element. As a result, optical crosstalk can be prevented.

[0230] As described above, according to the micro-light emitting element, optical crosstalk between adjacent micro-light emitting elements can be prevented, and the luminous efficiency of the micro-light emitting element can be improved by improving the light extraction efficiency of the micro-light emitting element. In addition, by preventing the optical crosstalk between adjacent micro-light emitting elements, the contrast ratio can be prevented from being reduced and the color purity can be prevented from being reduced. Further, the power consumption can be reduced by improving the luminous efficiency of the micro-light emitting element.

[0231] According to the second aspect of the present invention, the micro-light emitting element (100) may also be configured such that, in the first aspect, the reflecting surface is made of a metal material that reflects the visible light.

[0232] According to the above configuration, it is possible to more reliably prevent light emitted from the micro light emitting element from leaking to the outside of the micro light emitting element.

[0233] According to the third aspect of the present invention, the micro-light emitting element (100) may also be configured such that, in the first or second aspect, a transparent insulating film (17) is provided between the side surface (16S) of the main body (16) and the first reflecting material (reflecting material 20).

[0234] According to the above configuration, in the micro light emitting element, the reflectivity of light emitted by the micro light emitting element can be increased by providing the transparent insulating film between the side surface of the body and the first reflective material, thereby further improving the light extraction efficiency.

[0235] According to the fourth aspect of the present invention, the micro-light emitting element (100) may be configured such that, in the third aspect, the thickness of the transparent insulating film (17) is greater than 75 nm.

[0236] According to the above configuration, the light extraction efficiency can be effectively improved by the transparent insulating film.

[0237] According to the fifth aspect of the present invention, the micro-light emitting element (100) may be configured such that, in the third aspect, the film thickness of the transparent insulating film (17) is greater than 400 nm.

[0238] According to the above configuration, the light extraction efficiency can be optimally improved by the transparent insulating film.

[0239] According to the sixth aspect of the present invention, the micro-light emitting element (100) may be configured such that, in the first to fifth aspects, the second electrode (N electrode 23N) and the first reflective material (reflective material 20) may be made of the same material.

[0240] According to the above configuration, the second electrode and the first reflective material can be formed simultaneously in one process, so that the manufacturing process of the micro light-emitting element can be shortened.

[0241] According to the seventh aspect of the present invention, the micro-light emitting element (100) may also be configured such that, in the first to sixth aspects, the inclination angle (θe) of the side surface (16S) of the main body (16) may be less than 70°.

[0242] According to the above configuration, the light extraction efficiency can be optimally improved.

[0243] According to the eighth aspect of the present invention, the micro-light emitting element (100) may be configured such that, in the seventh aspect, the inclination angle (θe) of the side surface (16S) of the main body (16) is constant.

[0244] According to the above configuration, compared with a case where the side surface of the body has a plurality of side surfaces having different inclination angles, the process of forming dividing grooves for dividing the micro light emitting elements after forming the compound semiconductor layer is simplified.

[0245] According to the ninth aspect of the present invention, the micro-luminescent element (100a, 100b) can also be constructed as follows: in the seventh aspect, the side surface of the main body (16a, 16b) has at least a first side surface (16Sa1, 16Sb11) having an inclination angle (first inclination angle θe1, θe11) of less than 70° and a second side surface (16Sa2, 16Sb12) having an inclination angle (second inclination angle θe2, θe12) greater than 70°.

[0246] According to the above configuration, the side surface of the main body has a plurality of side surfaces with different inclination angles. Therefore, the light extraction efficiency can be improved by adjusting the reflection of light on the side surface of the main body while adjusting the area of ​​the light emitting layer.

[0247] According to the tenth aspect of the present invention, the micro-light emitting element (100a) may be configured such that, in the ninth aspect, the second side surface (16Sa2) is arranged on the light-releasing surface side of the first side surface (16Sa1).

[0248] According to the above configuration, since the inclination angle near the side surface of the light emitting layer can be increased, the area of ​​the light emitting layer can be increased.

[0249] According to the eleventh aspect of the present invention, the micro-light emitting element (100b) may be configured such that, in the ninth aspect, the first side surface (16Sb11) is arranged on the light-releasing surface side of the second side surface (16Sb12).

[0250] According to the above configuration, the light extraction efficiency can be further improved by reducing the inclination angle near the side surface of the light emitting layer.

[0251] The image display element (200) of form 12 of the present invention is constructed to include: a plurality of pixels (5), which have the micro-luminescent elements (100) described in forms 1 to 11 and are arranged in an array; a driving circuit substrate (50), which includes a driving circuit for supplying current to the micro-luminescent elements to make the micro-luminescent elements emit light; and a wavelength conversion layer (red wavelength conversion layer 32, green wavelength conversion layer 33), which absorbs the excitation light emitted by the micro-luminescent elements, converts the excitation light into long-wavelength light longer than the excitation light, and releases it to the outside, the wavelength conversion layer is arranged on the first electrode (common P electrode 30) and releases the long-wavelength light to the opposite side of the driving circuit substrate, the wavelength conversion layer is surrounded by a partition wall (34), the partition wall is inclined in a manner open relative to the light release direction, and has a side (partition wall side 34S) that reflects the long-wavelength light.

[0252] According to the above configuration, in the image display element, the wavelength conversion layer that converts the excitation light emitted by the micro-light-emitting element into long-wavelength light longer than the excitation light and releases it to the outside is tilted in an open manner relative to the light release direction, and is surrounded by a partition wall, and the surrounding has a side that reflects the long-wavelength light. In this way, while preventing light from leaking from the wavelength conversion layer to the partition wall, the long-wavelength light can be reflected by the side of the partition wall to reduce the loss of light released to the outside of the wavelength conversion. As a result, an image display element that achieves the effect of form 1 and can reduce the loss of light released to the outside of the image display element can be achieved.

[0253] The image display element (200) of form thirteen of the present invention is constructed to include: a plurality of pixels (5), which have the micro-luminescent elements (100a) described in forms one to eleven and are arranged in an array; a driving circuit substrate (50), which includes a driving circuit for supplying current to the micro-luminescent elements to make the micro-luminescent elements emit light; a transparent portion (31), which releases the light emitted by the micro-luminescent elements to the outside, the transparent portion is arranged on the first electrode (common P electrode 30) and releases the light to the opposite side of the driving circuit substrate, the transparent portion is surrounded by a partition wall (34a), the partition wall is inclined in a manner open relative to the light release direction, and has a side (partition wall side 34S) that reflects the light.

[0254] According to the above configuration, in the image display element, the transparent portion that releases the light emitted by the micro-light-emitting element to the outside of the micro-light-emitting element is inclined in an open manner relative to the light release direction, and is surrounded by a partition wall having a side surface that reflects light. Therefore, while preventing light from leaking from the transparent portion to the partition wall, the light can be reflected by the side surface of the partition wall, thereby reducing the loss of light released to the outside of the transparent portion. As a result, an image display element that achieves the effect of the first form and can reduce the loss of light released to the outside of the image display element can be achieved.

[0255] The image display element (200) of form fourteen of the present invention may also be configured such that, in form twelve or form thirteen, the side surface of the partition wall (34a) is covered by a second reflective material (partition wall reflective film 36) that reflects the long wavelength light or the light.

[0256] According to the above configuration, it is possible to more reliably prevent light from leaking from the wavelength conversion layer or the transparent portion to the partition wall.

[0257] The image display element (200) according to the fifteenth aspect of the present invention may be configured such that, in the fourteenth aspect, the second reflective material (partition wall reflective film 36) is electrically connected to the first electrode (common P electrode 30).

[0258] According to the above configuration, the second reflective film and the first electrode are electrically connected and arranged on the entire drive circuit substrate. Therefore, the wiring resistance between the drive circuit substrate and the micro light-emitting element can be kept low.

[0259] In the sixteenth aspect of the present invention, the image display element (200) may be configured such that, in the twelfth or thirteenth aspect, the partition wall (34) is electrically connected to the first electrode (common P electrode 30).

[0260] According to the above configuration, the partition wall and the first electrode are electrically connected and arranged on the entire drive circuit substrate, so that the wiring resistance between the drive circuit substrate and the micro light-emitting element can be kept low.

[0261] In the seventeenth form of the present invention, the image display element (200) is composed of a plurality of pixels (5), which have the micro-luminescent elements (100c) described in the first to thirteenth forms and are arranged in an array; and a driving circuit substrate (50c), which includes a driving circuit for supplying current to the micro-luminescent elements to make the micro-luminescent elements emit light, and the micro-luminescent elements are arranged with the light release surface facing the driving circuit substrate, and release light to the driving circuit substrate side.

[0262] According to the above structure, since the driving circuit substrate is transparent, even if the micro-light-emitting element is configured with the light-releasing surface facing the driving circuit substrate, the following image display element can be realized: it has the effect of form one and can reduce the loss of light released to the outside of the image display element.

[0263] The present invention is not limited to the above-mentioned embodiments, and various changes can be made within the scope indicated by the claims. The embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Moreover, new technical features can be formed by combining the technical methods disclosed in each embodiment.

[0264] The micro-light emitting element (100d) according to the eighteenth aspect of the present invention may be configured such that, in the first to fifth aspects, the side surface (16Sd) is a curved surface.

[0265] According to the above configuration, the area of ​​the light emitting layer can be adjusted by adjusting the curvature of the curved surface, and the reflection of light on the side surface of the body can be adjusted, thereby improving the light extraction efficiency.

[0266] The micro-light emitting element (100e) according to the nineteenth aspect of the present invention may be configured such that, in the third aspect, the transparent insulating film (17e) is a dielectric multilayer film having a DBR function.

[0267] According to the above configuration, light absorption on the side surface can be reduced, and thus the light extraction effect can be further improved.

[0268] The micro light emitting element (100f) of the twenty-second aspect of the present invention may be configured such that, in the first to eighth aspects, the second conductive layer (N-side layer 11e) includes a compound semiconductor multilayer film (43) having a DBR function.

[0269] According to the above configuration, since the reflectivity of the visible light in the second conductive layer can be increased, light absorption on the lower surface of the main body can be reduced, and light extraction efficiency can be further improved.

[0270] The micro light-emitting element (100g) of form twenty-one of the present invention may be configured such that, in the forms one to eight, the first conductive layer (P-side layer 13g) includes a compound semiconductor multilayer film (44) having a DBR function.

[0271] According to the above configuration, for example, by stacking a plurality of AlGaN layers and InGaN layers on the compound semiconductor multilayer film, the compound semiconductor multilayer film has high transmittance for the emission wavelength of the micro-light-emitting element, and on the other hand, has high reflectivity for the wavelength-converted light. By configuring the film having such characteristics on the light-releasing surface side, it is possible to prevent the wavelength-converted light from entering the body and being absorbed by the side and bottom surfaces of the body and reducing the light output.

[0272] The micro light emitting element (100h) of the twenty-second aspect of the present invention may be configured such that, in the first to eighth aspects, the first reflecting material (reflecting material 20h) and the second electrode (N electrode 23Nh) are arranged to be separated from each other.

[0273] According to the above configuration, by making the first reflecting material electrically contact with the first electrode, the first reflecting material can be used as a part of the wiring.

[0274] The micro-light emitting element (100i) of the twenty-third aspect of the present invention may be configured such that, in the above-mentioned aspects one to eight, it further includes a third electrode (P electrode 23Pi) connected to the first electrode (common P electrode 30).

[0275] According to the above configuration, since the P driving electrode can be provided in the micro light emitting element and connected to the third electrode, there is no need to provide a region for connecting the first electrode and the P driving electrode outside the pixel region.

Claims

1. An image display element, It is characterized in that It includes: A plurality of pixels, each of which has a micro light-emitting element and is arranged in an array; a driving circuit substrate, comprising a driving circuit for supplying current to the micro-light emitting element to cause the micro-light emitting element to emit light; as well as a wavelength conversion layer that absorbs the excitation light emitted by the micro-light-emitting element, converts the excitation light into long-wavelength light having a longer wavelength than the excitation light, and releases the long-wavelength light to the outside, The micro-light emitting element comprises: A main body, comprising a compound semiconductor layer on which a first conductive layer, a light-emitting layer, and a second conductive layer are sequentially deposited from a light-releasing surface side, wherein the second conductive layer has a conductivity type opposite to that of the first conductive layer; A first electrode including a transparent electrode on the light-releasing surface side; a second electrode including a metal film on a side opposite to the light-releasing surface; and a first reflective material, which covers the sides of the body, The light emitting layer is arranged on the light releasing surface side of the main body, The side surface of the body is inclined in a manner open relative to the light release direction, The second electrode and the first reflective material are configured such that the surface of the main body side is a reflective surface that reflects visible light. The wavelength conversion layer is provided on the light-releasing surface side of the first electrode in contact with the first electrode, and releases the long-wavelength light to the side opposite to the driving circuit substrate. The wavelength conversion layer is surrounded by a partition wall, the partition wall is inclined in a manner open to the light release direction and has a side surface that reflects the long wavelength light. The micro-light emitting element further includes a second reflective material, and the second reflective material covers the side surface of the wavelength conversion layer. The inner side surface of the second reflective material is inclined in a manner to be open toward the light release direction, The opening of the second reflecting material is arranged on the inner side of the inner edge of the upper end portion of the first reflecting material.

2. The image display element according to claim 1, It is characterized in that In a plan view, the second electrode and the first reflective material cover the entire body.

3. The image display element according to claim 1, It is characterized in that The side surface of the main body at least has a first side surface with an inclination angle of less than 70° and a second side surface with an inclination angle of greater than 70°. The first side surface is arranged on the light release surface side of the second side surface.

4. The image display element according to claim 1, It is characterized in that The side surface of the main body at least has a first side surface with an inclination angle of less than 70° and a second side surface with an inclination angle of greater than 70°. The second side surface is arranged on the light release surface side of the first side surface.

5. The image display element according to claim 1, It is characterized in that The inclination angle of the side surface of the body is constant.

6. The image display element according to claim 1, It is characterized in that The reflective surface is made of a metal material that reflects the visible light.

7. The image display element according to claim 1, It is characterized in that A transparent insulating film is provided between the side surface of the main body and the first reflective material.

8. The image display element according to claim 7, It is characterized in that The transparent insulating film has a thickness of 75 nm or more.

9. The image display element according to claim 8, It is characterized in that The transparent insulating film has a thickness of 400 nm or more.

10. The image display element according to claim 1, It is characterized in that The second electrode and the first reflective material are made of the same material.

11. The image display element according to claim 5, It is characterized in that The inclination angle of the side surface of the main body is less than 70°.

12. The image display element according to claim 1, It is characterized in that Each of the pixels has a transparent portion, and the transparent portion releases the light emitted by the micro-light emitting element to the outside. The transparent portion is arranged in contact with the first electrode and releases the light to a side opposite to the driving circuit substrate. The transparent portion is surrounded by the partition wall, and the partition wall has a side surface that reflects the light.

13. The image display element according to claim 1, It is characterized in that The side surfaces of the partition walls are covered with the second reflective material, and the second reflective material reflects the long-wavelength light or the light.

14. The image display element according to claim 13, It is characterized in that The second reflective material is electrically connected to the first electrode.

15. The image display element according to claim 1, It is characterized in that The partition wall is electrically connected to the first electrode.

Images