Classifications

• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
  • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
  • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
  • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
  • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
  • G09F9/302—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements characterised by the form or geometrical disposition of the individual elements
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
  • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
  • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
  • G09F9/33—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being semiconductor devices, e.g. diodes
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/81—Bodies
  • H10H20/813—Bodies having a plurality of light-emitting regions, e.g. multi-junction LEDs or light-emitting devices having photoluminescent regions within the bodies
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/851—Wavelength conversion means
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/855—Optical field-shaping means, e.g. lenses
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/857—Interconnections, e.g. lead-frames, bond wires or solder balls

Definitions

• This disclosure relates to a light-emitting device and an image display device equipped with the same.
• Patent Document 1 discloses a microLED formed by covering a crystal growth substrate with a mask layer having multiple openings and selectively growing one or more semiconductor rods having a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type using a metalorganic chemical vapor deposition (MOCVD) method.
• MOCVD metalorganic chemical vapor deposition
• the light emitting device of one embodiment of the present disclosure includes a drive circuit board, and an element substrate having a first surface that is a light emitting surface and a second surface opposite the first surface and facing the drive circuit board, a pixel array section in which a plurality of pixels are arranged in an array, and two or more light emitting elements having a mesa structure are arranged for each pixel.
• An image display device includes a light-emitting device, and the light-emitting device includes the light-emitting device according to one embodiment of the present disclosure.
• two or more light-emitting elements having a mesa structure are arranged for each pixel. This provides redundancy to each pixel.
• FIG. 1 is a schematic cross-sectional view illustrating an example of a configuration of a light-emitting device according to an embodiment of the present disclosure.
• FIG. 2 is a schematic diagram showing an example of the overall planar configuration of the light emitting device shown in FIG.
• FIG. 3 is a schematic diagram showing an enlarged part of the planar configuration of the light emitting device shown in FIG.
• FIG. 4 is a schematic plan view showing an example of the arrangement of light-emitting elements in each pixel of the light-emitting device shown in FIG.
• FIG. 5 is a diagram for explaining an example of a method for controlling the luminance of each pixel in the light emitting device shown in FIG. FIG.
• FIG. 7A is a schematic cross-sectional view illustrating an example of a manufacturing process for the light emitting device shown in FIG.
• FIG. 7B is a schematic cross-sectional view showing a step subsequent to FIG. 7A.
• FIG. 7C is a schematic cross-sectional view showing a step subsequent to FIG. 7B.
• FIG. 7D is a schematic cross-sectional view showing a step subsequent to FIG. 7C.
• FIG. 7E is a schematic cross-sectional view showing a step subsequent to FIG. 7D.
• FIG. 7F is a schematic cross-sectional view showing a step subsequent to FIG. 7E.
• FIG. 7A is a schematic cross-sectional view illustrating an example of a manufacturing process for the light emitting device shown in FIG.
• FIG. 7B is a schematic cross-sectional view showing a step subsequent to FIG. 7A.
• FIG. 7C is a schematic cross-sectional view showing a step subsequent to FIG. 7B.
• FIG. 7D
• FIG. 7G is a schematic cross-sectional view showing a step subsequent to FIG. 7F.
• FIG. 7H is a schematic cross-sectional view showing a step subsequent to FIG. 7G.
• FIG. 7I is a schematic cross-sectional view showing a step subsequent to FIG. 7H.
• FIG. 8A is a schematic cross-sectional view showing a step subsequent to FIG. 7F.
• FIG. 8B is a schematic cross-sectional view showing a step subsequent to FIG. 8A.
• FIG. 8C is a schematic cross-sectional view showing a step subsequent to FIG. 8B.
• FIG. 8D is a schematic cross-sectional view showing a step subsequent to FIG. 8C.
• FIG. 8E is a schematic cross-sectional view showing a step subsequent to FIG. 8D.
• FIG. 8F is a schematic cross-sectional view showing a step subsequent to FIG. 8E.
• FIG. 8G is a schematic cross-sectional view showing a step subsequent to FIG. 8F.
• FIG. 8H is a schematic cross-sectional view showing a step subsequent to FIG. 8G.
• FIG. 8I is a schematic cross-sectional view showing a step subsequent to FIG. 8H.
• FIG. 8J is a schematic cross-sectional view showing a step subsequent to FIG. 8I.
• FIG. 8K is a schematic cross-sectional view showing a step subsequent to FIG. 8J.
• FIG. 8L is a schematic cross-sectional view showing a step subsequent to FIG. 8K.
• FIG. 8M is a schematic cross-sectional view showing a step subsequent to FIG. 8L.
• FIG. 8N is a schematic cross-sectional view showing a step subsequent to FIG. 8M.
• FIG. 9 is a diagram illustrating the luminance before correction (A) and the luminance after correction (B) of each pixel in a typical light emitting device as a comparative example.
• FIG. 10 is a diagram for explaining the relationship between the luminance of each light-emitting element and the luminance of each pixel in a typical light-emitting device.
• FIG. 11 is a diagram for explaining the relationship between the luminance of each light-emitting element and the luminance of each pixel in the light-emitting device shown in FIG.
• FIG. 12 is a diagram illustrating the luminance (A) of each light-emitting element in each pixel of the light-emitting device shown in FIG.
• FIG. 13 is a schematic diagram illustrating an example of the overall planar configuration of a light emitting device according to a modified example of the present disclosure.
• FIG. 14 is a schematic diagram showing an enlarged portion of the planar configuration of the light emitting device shown in FIG.
• FIG. 15 is a perspective view illustrating an example of a configuration of an image display device according to an application example of the present disclosure.
• FIG. 16 is a schematic diagram showing an example of a wiring layout of the image display device shown in FIG.
• FIG. 17 is a perspective view illustrating an example of a configuration of an image display device according to an application example of the present disclosure.
• FIG. 18 is a perspective view illustrating the configuration of the mounting board illustrated in FIG.
• FIG. 19 is a perspective view illustrating the configuration of the unit board shown in FIG.
• FIG. 20 is a diagram illustrating an example of an image display device according to an application example of the present disclosure.
• Fig. 1 is a schematic diagram showing an example of a cross-sectional configuration of a light-emitting device (light-emitting device 1) according to an embodiment of the present disclosure.
• Fig. 2 is a schematic diagram showing an example of an overall planar configuration of the light-emitting device 1 shown in Fig. 1.
• the light-emitting device 1 is suitably applicable to an image display device (e.g., image display device 100, see Fig. 15) that is a so-called LED display.
• the light emitting device 1 is a hybrid joint of an element substrate 10 and a drive circuit substrate 30. As shown in FIG. 3, the light emitting device 1 has a display region 100A in which a plurality of pixels (e.g., red pixels Pr, green pixels Pg, and blue pixels Pb) having a rectangular shape are arranged in a two-dimensional array, and a frame region 100B provided around the display region 100A.
• the element substrate 10 has a surface 10S1 that is a light emitting surface and a surface 10S2 opposite to the surface 10S1, and the drive circuit substrate 30 is laminated on the surface 10S2 side of the element substrate 10.
• the drive circuit substrate 30 has a surface 30S1 facing the element substrate 10 and a surface 30S2 opposite to the surface 30S1, and is provided with a drive circuit or the like that controls the drive of a plurality of light emitting elements 11 arranged in the display region 100A.
• a drive circuit or the like that controls the drive of a plurality of light emitting elements 11 arranged in the display region 100A.
• two or more (e.g., four) light emitting elements 11 having a mesa structure are arranged for each of the color pixels Pr, Pg, and Pb.
• the element substrate 10 corresponds to a specific example of an "element substrate” in the embodiment of the present disclosure
• the surface 10S1 corresponds to a "first surface” in the embodiment of the present disclosure
• the surface 10S2 corresponds to a "second surface” in the embodiment of the present disclosure.
• the display area 100A corresponds to a specific example of a "pixel array portion” in the embodiment of the present disclosure
• the red pixel Pr, the green pixel Pg, and the blue pixel Pb correspond to specific examples of "multiple pixels” in the embodiment of the present disclosure.
• the drive circuit substrate 30 corresponds to a specific example of a "drive circuit substrate” in the embodiment of the present disclosure.
• the element substrate 10 has a plurality of light-emitting elements 11 formed by separating the compound semiconductor layer 110 (see FIG. 7A) extending in the display area 100A.
• the plurality of light-emitting elements 11 have a substantially circular planar shape, for example, as shown in FIG. 4, and are arranged in an array in the display area 100A, for example, in the row direction (for example, the X-axis direction) and the column direction (for example, the Y-axis direction).
• the plurality of light-emitting elements 11 arranged in an array in the row direction and the column direction for example, four light-emitting elements arranged in two rows and two columns are arranged in each of the color pixels Pr, Pg, and Pb.
• an electrode layer 12 continuous with the plurality of light-emitting elements 11 is formed on the light extraction surface (surface 11S1) side of the plurality of light-emitting elements 11.
• an electrode layer 115, an insulating layer 116, and a protective layer 117 provided for each element, and an insulating film 118A and a reflective film 118B continuous with the plurality of light-emitting elements 11 are formed on the surface 11S2 side of the plurality of light-emitting elements 11.
• the element substrate 10 further includes an embedding layer 119 that embeds the multiple light-emitting elements 11 from the surface 10S2 side, and insulating layers 17 and 18 on the drive circuit substrate 30 side.
• the embedding layer 119 includes a plug 15 provided for each element, and the insulating layer 17 includes a pad portion 16A provided for each element in the display region 100A and a pad electrode 16B provided in the frame region 100B.
• the insulating layer 18 includes a plurality of pad portions 19 that form a bonding surface with the drive circuit substrate 30 and electrically and physically bond the element substrate 10 and the drive circuit substrate 30 together.
• the light-emitting element 11 corresponds to one specific example of a "light-emitting element" in the embodiment of the present disclosure.
• the light-emitting element 11 is a solid-state light-emitting element that emits light in a predetermined wavelength band from surface 11S1, for example, an LED (Light Emitting Diode) chip.
• the LED chip refers to an element cut out from a wafer used for crystal growth, and is not a packaged type covered with molded resin or the like.
• the LED chip is, for example, 5 ⁇ m or more and 100 ⁇ m or less in size, and is a so-called micro LED.
• the light-emitting element 11 is made up of a first conductive type layer 111, an active layer 112, and a second conductive type layer 113 stacked in this order, with the upper surface of the second conductive type layer 113 being the light-emitting surface (surface 11S1).
• the first conductive type layer 111 is formed, for example, from an n-type GaN-based semiconductor material.
• the active layer 112 has a multiple quantum well structure in which, for example, InGaN and GaN are alternately stacked, and has a light-emitting region within the layer. Light in the blue band of, for example, 430 nm or more and 500 nm or less is extracted from the active layer 112. In addition, light with a wavelength corresponding to, for example, the ultraviolet region (ultraviolet light) may also be extracted from the active layer 112.
• the second conductive type layer 113 is formed, for example, from a p-type GaN-based semiconductor material.
• the electrode layer 12 is formed continuously on the surface 11S1 of each of the light-emitting elements 11 as a common electrode for the light-emitting elements 11.
• the electrode layer 12 is in ohmic contact with the second conductive type layer 113 and is formed of a transparent electrode material such as zinc oxide (ZnO), ITO, indium zinc oxide (IZO), tin oxide (SnO) or TiO.
• the electrode layer 12 is electrically connected to the pad electrode 16B, for example, in the frame region 100B, via an opening H1 that penetrates the protective layer 117 and the embedded layer 119 and exposes the pad electrode 16B at its bottom.
• An electrode layer 115 is formed on the lower surface (surface 11S2) of the first conductivity type layer 111 of the light emitting element 11.
• the electrode layer 115 is in ohmic contact with the first conductivity type layer 111, and is formed using a transparent conductive material such as a multilayer film (Ni/Au) of nickel (Ni) and gold (Au) or ITO.
• the insulating layer 116 is provided on the electrode layer 115.
• the insulating layer 116 is made of, for example, silicon oxide (SiO) or silicon nitride (SiN).
• the light-emitting element 11 has a mesa structure on the drive circuit board 30 side, including the first conductive type layer 111, the active layer 112, and a part of the second conductive type layer 113.
• the surface 11S2 of the light-emitting element 11 processed into a mesa shape and the side surfaces of the first conductive type layer 111, the active layer 112, and a part of the second conductive type layer 113 are covered with a protective layer 117.
• the protective layer 117 is formed of, for example, silicon oxide (SiO) or silicon nitride (SiN).
• the protective layer 117 and the side surface of the second conductive type layer 113 exposed from the protective layer 117 are covered with a laminated film consisting of an insulating film 118A and a reflective film 118B.
• the laminated film is continuously formed on the multiple light-emitting elements 11.
• the laminated film has an opening 118H on the surface 11S2 side of the light-emitting element 11, and a plug 15 is formed in the opening 118H.
• the plug 15 applies a voltage to the first conductive layer 111 of each of the multiple light-emitting elements 11.
• the plug 15 is formed using, for example, copper (Cu), aluminum (Al), tungsten (W), silver (Ag), or an alloy thereof.
• the embedding layer 119 embeds the multiple light-emitting elements 11 and forms a flat layered surface across the display area 100A and frame area 100B on the drive circuit board 30 side.
• the embedding layer 119 further forms a flat surface in the frame area 100B that is continuous with the surface 11S1 of the multiple light-emitting elements 11.
• the embedding layer 119 is formed of, for example, silicon oxide (SiO) or silicon nitride (SiN).
• An insulating layer 17 is provided on the drive circuit board 30 side of the embedded layer 119.
• a plurality of pad portions 16A are provided for each light emitting element 11A in the display region 100A, and pad electrodes 16B and vias are provided in the frame region 100B.
• the insulating layer 17 is formed of, for example, silicon oxide (SiO) or silicon nitride (SiN).
• the pad portions 16A, pad electrodes 16B and vias are formed of, for example, copper (Cu), aluminum (Al), tungsten (W), silver (Ag) or alloys thereof.
• An insulating layer 18 is further formed on the side of the insulating layer 17 facing the drive circuit board 30, forming a bonding surface with the drive circuit board 30. As described above, the insulating layer 18 is embedded with a plurality of pad portions 19 that form a bonding surface with the drive circuit board 30 and electrically and physically bond the element substrate 10 and the drive circuit board 30 together.
• the insulating layer 18 is formed from, for example, silicon oxide (SiO) or silicon nitride (SiN).
• the pad portions 19 are formed from, for example, copper (Cu).
• the element substrate 10 further includes, on the surface 10S1 side, a planarization layer 21, a partition layer 22 having openings 22H for each of the color pixels Pr, Pg, and Pb, and a wavelength conversion layer 23 formed in the openings 22H.
• a reflective film 24 is further provided between the partition layer 22 and the wavelength conversion layer 23.
• the planarization layer 21 is intended to planarize the light extraction surface (surface 11S1) of the display area 100A, in which a plurality of light-emitting elements 11 are arranged in an array.
• the planarization layer 21 is formed of, for example, silicon oxide (SiO) or silicon nitride (SiN).
• the partition layer 22 is intended to suppress the occurrence of color mixing due to light leakage between adjacent pixels of different colors when the light emitting device 1 is applied to the image display device 100.
• the partition layer 22 has, for example, a substantially rectangular opening 22H for each of the color pixels Pr, Pg, and Pb arranged in an array.
• the opening 22H has, for example, an inclined surface that is less than 90° with respect to the surface of the partition layer 22 facing the light emitting element 11.
• the partition layer 22 has a forward tapered side surface between adjacent color pixels Pr, Pg, and Pb.
• the partition layer 22 is preferably formed using a material with high thermal conductivity and electrical conductivity, and is formed using a metal material such as copper (Cu), aluminum (Al), gold (Au), nickel (Ni), and platinum (Pt).
• the wavelength conversion layer 23 is formed in an opening 22H provided for each color pixel Pr, Pg, Pb, to convert the light emitted from the light-emitting elements 11 arranged in each color pixel Pr, Pg, Pb into a desired wavelength (e.g., red (R)/green (G)/blue (B)) and emit the light.
• a desired wavelength e.g., red (R)/green (G)/blue (B)
• the red pixel Pr is provided with a red wavelength conversion layer 23R that converts the light emitted from, for example, the four light-emitting elements 11 into light in the red band (red light)
• the green pixel Pg is provided with a green wavelength conversion layer 23G that converts the light emitted from, for example, the four light-emitting elements 11 into light in the green band (green light)
• the blue pixel Pb is provided with a blue wavelength conversion layer 23B that converts the light emitted from, for example, the four light-emitting elements 11 into light in the blue band (blue light).
• Each of the wavelength conversion layers 23R, 23G, and 23B can be formed using quantum dots corresponding to each color.
• the quantum dots can be selected from, for example, InP, GaInP, InAsP, CdSe, CdZnSe, CdTeSe, or CdTe.
• the quantum dots can be selected from, for example, InP, GaInP, ZnSeTe, ZnTe, CdSe, CdZnSe, CdS, or CdSeS.
• the quantum dots can be selected from, for example, ZnSe, ZnTe, ZnSeTe, CdSe, CdZnSe, CdS, CdZnS, and CdSeS.
• the blue wavelength conversion layer 23B may be formed from a transparent resin layer having optical transparency.
• the reflective film 24 is provided on the side of the opening 22H to efficiently extract the colored light emitted from the multiple light-emitting elements 11 and converted in each of the wavelength conversion layers 23R, 23G, 23B from the light extraction surface (surface 23S1) of the wavelength conversion layer 23.
• the reflective film 24 is formed using a metal material that has light reflectivity.
• the metal material that forms the reflective film 24 include metals that have a high reflectivity in the visible light range. Specific examples of the material include silver (Ag), aluminum (Al), copper (Cu), gold (Au), platinum (Pt), rhodium (Rh), and alloys thereof.
• the reflective film 24 does not necessarily need to be formed if the partition layer 22 is formed using the above-mentioned light-reflective metal material.
• An optical structure 40 may be further formed on the light emission surface S1 side of the element substrate 10.
• the optical structure 40 has a protective layer 41 formed across the display region 100A and the frame region 100B, and an on-chip lens layer 42 provided on the protective layer 41.
• the protective layer 41 is intended to protect the surface of the wavelength conversion layer 23 and is made of, for example, silicon oxide (SiO) or silicon nitride (SiN).
• the on-chip lens layer 42 is provided so as to cover the entire display area 100A and the frame area 100B.
• the on-chip lens layer 42 has a plurality of on-chip lenses 42L that have a predetermined curvature and emit incident light in a predetermined direction. As shown in FIG. 4, each on-chip lens 42L is arranged for each color pixel Pr, Pg, Pb.
• the on-chip lens layer 42 is made of a light-transmitting material, and is made of, for example, a single layer film made of any of silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiCN), etc., or a laminated film made of two or more of these materials.
• the drive circuit board 30 is provided with a plurality of constant current drive circuits that pass a constant current through a plurality of light emitting elements 11 arranged in the display area 100A.
• the drive circuit board 30 has a support substrate 31, an interlayer insulating layer 32 provided on the support substrate 31 and including a plurality of wiring layers (e.g., wiring layers M1, M2, M3, M4, M5) and vias that electrically connect the wiring layers, an insulating layer 33 that forms a bonding surface with the element substrate 10, and a pad portion 34 that is embedded in the insulating layer 33.
• Each of the multiple constant current drive circuits includes a control element 35 that controls the current flowing to the light emitting element 11, and is electrically connected to the multiple light emitting elements 11 via pad portions 19, 34 provided on the respective bonding surfaces (surface 10S2 and surface 30S1) of the element substrate 10 and the drive circuit substrate 30.
• FIGS. 5 and 6 each explain an example of a method for controlling the luminance of each pixel (e.g., red pixel Pr and green pixel Pg) in the light-emitting device 1 shown in FIG. 1.
• the arrows in FIG. 5 and FIG. 6 indicate the amount of current flowing through each light-emitting element 11.
• the multiple light-emitting elements 11 provided for each color pixel Pr, Pg are each individually connected to a constant current drive circuit.
• the control element 35 connected to that light-emitting element 11 is turned off and the current flowing to the other light-emitting elements 11 is controlled (here, increased), making it possible to maintain the brightness per pixel.
• the multiple light-emitting elements 11 provided for each color pixel Pr, Pg are wired together and connected to one constant current drive circuit.
• the multiple light-emitting elements 11 provided for each color pixel Pr, Pg cause a bright spot defect, for example due to a defect, no current flows through that light-emitting element 11 by trimming it, but a large current flows through the other light-emitting elements 11, so the brightness per pixel can be kept constant.
• the interlayer insulating layer 32 is formed, for example, from silicon oxide (SiO) or silicon nitride (SiN).
• the wiring layers M1, M2, M3, M4, and M5 and the vias electrically connecting each wiring layer are formed using, for example, copper (Cu), aluminum (Al), tungsten (W), silver (Ag), or alloys thereof.
• the insulating layer 33 is formed using, for example, silicon oxide (SiO) or silicon nitride (SiN).
• the pad portion 34 is formed using, for example, copper (Cu).
• the light emitting device 1 of this embodiment can be manufactured, for example, as follows: Figures 7A to 7I and Figures 8A to 8N show an example of a manufacturing process for the light emitting device 1.
• a compound semiconductor layer 110 is formed by epitaxial crystal growth using a method such as Metal Organic Chemical Vapor Deposition (MOCVD) or Molecular Beam Epitaxy (MBE) on a sapphire substrate 114 as a growth substrate.
• MOCVD Metal Organic Chemical Vapor Deposition
• MBE Molecular Beam Epitaxy
• an electrode layer 115 and an insulating layer 116 are formed on the compound semiconductor layer 110 by, for example, chemical vapor deposition (CVD).
• CVD chemical vapor deposition
• the surface of the insulating layer 116 is planarized by, for example, chemical mechanical polishing (CMP).
• the insulating layer 116, the electrode layer 115, and the compound semiconductor layer 110 are etched and patterned using, for example, photolithography technology.
• the sapphire substrate 114 is transferred to the support substrate 51 so that the insulating layer 116 faces the support substrate 51, and the sapphire substrate 114 is then cut into individual pieces.
• each individual sapphire substrate 114 is bonded to the support substrate 52 so that the insulating layer 116 faces the support substrate 52.
• the sapphire substrate 114 is removed by, for example, grinding and polishing, and the surface of the compound semiconductor layer 110 is planarized.
• the buried layer 119 is formed on the support substrate 52 by, for example, CVD, and planarized, and then the ends are trimmed as shown in Figure 7G.
• the buried layer 119 is bonded to the support substrate 53 by, for example, plasma bonding, and then the support substrate 52 is peeled off as shown in Figure 7I.
• the inside of the frame X shown in Figure 7I is enlarged and explained below.
• the insulating layer 116 and the electrode layer 115 provided on the compound semiconductor layer 110 are etched and patterned using, for example, photolithography.
• a part of the compound semiconductor layer 110 is etched using, for example, photolithography to form a mesa structure including the first conductive type layer 111, the active layer 112, and a part of the second conductive type layer 113.
• an AlO film is formed, for example, by atomic layer deposition (ALD), on the top surface of the insulating layer 116 and on the side and bottom surfaces of the insulating layer 116, the electrode layer 115, and the first conductive type layer 111, the active layer 112, and the second conductive type layer 113 that constitute the mesa structure, and then a SiN film is further formed, for example, by CVD.
• the SiN film is etched, for example, by photolithography, to form a protective layer 117 as a sidewall on the top surface and side surface of the mesa structure, as shown in FIG. 8C.
• the second conductive type layer 113 exposed from the protective layer 117 is separated, for example, by photolithography to form a plurality of light emitting elements 11.
• an AlO film is formed, for example, by ALD, to cover the upper surface of the protective layer 117 and the exposed side surfaces of the light emitting elements 11.
• an insulating film 118A and a reflective film 118B are formed in this order, for example, by CVD, and then an opening 118H is formed in the upper surface of the mesa structure.
• a buried layer 119 is formed again by, for example, CVD and planarized, and then an insulating layer 17 is formed for each light-emitting element 11, in which a plug 15, a plurality of pad portions 16A, and a pad electrode 16B are buried, as shown in Fig. 8G.
• the insulating layer 17 is thickened, and an insulating layer 18 is formed on the insulating layer 17, and then the ends are trimmed as shown in Fig. 8I.
• openings 18H are formed on each pad portion 16A and pad electrode 16B, and then, as shown in FIG. 8K, multiple pad portions 19 are formed by filling the openings 18H with, for example, Cu. Thereafter, the surfaces of the insulating layer 18 and the multiple pad portions 19 are polished, for example, by CMP, to flatten the bonding surface with the drive circuit board 30.
• FIG. 8L a plurality of pads 34 of a separately formed driving circuit board 30 and a plurality of pads 19 are bonded together by hybrid bonding, and then the support substrate 53 is peeled off as shown in FIG. 8M.
• an ITO film is formed by, for example, a CVD method, and then the ITO film is patterned by, for example, a photolithography technique to form an electrode layer 12.
• an insulating layer 13 is formed by, for example, a CVD method, and then an opening between adjacent light emitting elements 11 and an opening H1 reaching the pad electrode 16B are formed by, for example, a photolithography technique.
• a laminated film of, for example, Ti/W is formed by, for example, a CVD method, and then the laminated film is patterned by, for example, a photolithography technique to form an extraction electrode 14.
• the planarization layer 21 and the partition layer 22 are formed in order, for example, by CVD, and then the openings 22H are formed in the partition layer 22 for each pixel, for example, by photolithography.
• an Al film is formed on the top surface of the partition layer 22 and the side and bottom surfaces of the openings 22H, for example, by CVD, and then the Al film formed on the top surface of the partition layer 22 and the bottom surface of the openings 22H is removed by etch-back to form a reflective film 24 on the side surfaces of the openings 22H.
• the wavelength conversion layers 23 (23R, 23G, 23B) of each color are formed in the openings 22H, for example, by a coating method such as an inkjet method.
• a protective layer 41 is formed on the partition layer 22 and the wavelength conversion layer 23, and then an on-chip lens layer 42 is bonded to them.
• two or more (for example, four) light emitting elements 11 having a mesa structure are arranged for each of the color pixels Pr, Pg, and Pb. This provides redundancy to each pixel. This will be described below.
• Mesa refers to the light-emitting part (or independent light-emitting element) in an image display device.
• miniaturizing the LED mesa structure causes a sudden drop in light-emitting efficiency in areas of 1 ⁇ m or less due to the Pelipper effect, resulting in large variations in internal quantum efficiency (IQE).
• IQE internal quantum efficiency
• multiple LED mesa structures for one pixel.
• multiple LED mesas can be formed by covering the crystal growth substrate with a mask layer with multiple openings and selectively growing one or more semiconductor rods using the MOCVD method.
• MOCVD method it is difficult to control the height with the MOCVD method, and when fine LED mesas are formed, the variation in brightness between mesas due to variations in height becomes a major issue.
• the mesa itself grows perpendicular to the crystal growth substrate, this is disadvantageous in terms of light collection.
• a single pixel e.g., a red pixel Pr, a green pixel Pg, and a blue pixel Pb
• a single pixel is provided with multiple light-emitting elements 11 separated by etching the compound semiconductor layer 110. This provides redundancy to each pixel, and reduces the variation in brightness between pixels.
• FIG. 9 shows the luminance variation (A) among pixels P1, P2, P3, and P4 in a general light-emitting device 1000 as a comparative example, and the luminance of pixels P1, P2, P3, and P4 after correction (B).
• a light-emitting device 1000 in which one light-emitting element 11 is arranged in each pixel if there is luminance variation among pixels P, the luminance variation among pixels P is corrected, for example, by adjusting the luminance levels of the other pixels to the luminance level of the pixel with the lowest luminance. That is, as shown in FIG. 8A, if four pixels P1, P2, P3, and P4 arranged in two rows and two columns have luminance levels of 30, 100, 50, and 70, respectively, as shown in FIG. 8B, the luminance levels of P2, P3, and P4 are adjusted to the luminance level of pixel P1, which has the lowest luminance level, 30, as shown in FIG. 8B.
• the luminance of the light-emitting element 11 arranged in each pixel P becomes the luminance of the pixel P as it is.
• the luminance level of the light-emitting device 1000 becomes 30 because the luminance levels of the other pixels are adjusted to the luminance level of the pixel with the lowest luminance.
• the luminance of each pixel P1, P2, P3, P4 becomes the average of the four light-emitting elements 11 provided in the pixel. Therefore, as shown in FIG. 11, the luminance of each of the four pixels P1, P2, P3, P4 becomes 62.5, which is higher than that of the light-emitting device 1000.
• a single wavelength conversion layer 23 (e.g., red wavelength conversion layer 23R, green wavelength conversion layer 23G, or blue wavelength conversion layer 23B) is arranged for adjacent light-emitting elements 11, so that the variation and unevenness in brightness between pixels caused by the miniaturization of the mesa structure can be improved. In addition, the occurrence of defective pixels that become bright spots can be eliminated, which makes it possible to improve the manufacturing yield.
• a constant current drive circuit is connected to each of the multiple light-emitting elements 11 arranged in each color pixel Pr, Pg, and Pb, making it possible to control the emission of each light-emitting element 11 independently.
• FIG. 12 shows the luminance (A) of each light-emitting element 11 in each pixel P of the light-emitting device 1 before correction and the luminance (B) of each light-emitting element 11 after correction.
• the average luminance of the four light-emitting elements 11 arranged in pixel P1 is 47.5, which is the lowest average luminance.
• a light-emitting element 11 with high luminance (high IQE) is selected, and if the luminance of pixel P1 with the lowest average luminance can be satisfied by the light-emitting element 11, the luminance may be adjusted by selectively operating some of the multiple light-emitting elements arranged in each pixel P2, P3, and P4. Specifically, as shown in FIG. 12B, for example, in pixel P2, two of the four light-emitting elements 11 with a luminance level of 100 may be selectively operated, and the other two may not be operated. Also, for example, in pixel P4, three of the four light-emitting elements 11 with a luminance level of 70 may be selectively operated, and one may not be operated.
• the amount of current is adjusted by the control element 35 so that the luminance of the light-emitting element 11 becomes that of pixel P1. In this way, by selectively operating a highly efficient light-emitting element 11, the load on the correction circuit can be reduced. It is also possible to reduce the amount of power used.
• Fig. 13 is a schematic diagram showing an example of the overall planar configuration of a light-emitting device (light-emitting device 1A) according to a modified example of the present disclosure.
• Fig. 14 is an enlarged view of a portion of the planar configuration of the light-emitting device 1A shown in Fig. 13.
• the color pixels Pr, Pg, and Pb each have a substantially rectangular shape and have four light-emitting elements 11 arranged in two rows and two columns, but this is not limiting.
• the light emitting device 1A of this modified example has a display area 100A in which a plurality of pixels (e.g., red pixels Pr, green pixels Pg, and blue pixels Pb) having a substantially regular hexagonal shape are arranged in a honeycomb pattern, and a frame area 100B provided around the display area 100A.
• a plurality of pixels e.g., red pixels Pr, green pixels Pg, and blue pixels Pb
• Each of the color pixels Pr, Pg, and Pb has, for example, seven light emitting elements each having a mesa structure arranged therein. With this configuration, it is possible to obtain the same effects as in the above embodiment.
• FIG. 15 is a perspective view showing an example of a schematic configuration of an image display device (image display device 100).
• the image display device 100 is a so-called LED display, and uses the light-emitting device of the present disclosure (e.g., the light-emitting device 1) as a display pixel.
• the image display device 100 includes a display panel 120 and a control circuit 140 that drives the display panel 120, as shown in Fig. 15, for example.
• the display panel 120 is made by stacking a mounting substrate 120A and an opposing substrate 120B on top of each other.
• the surface of the opposing substrate 120B is the image display surface, with a display area 100A in the center and a frame area 100B, which is a non-display area, around it.
• FIG. 16 shows an example of a wiring layout in the area corresponding to the display area 100A on the surface of the mounting substrate 120A facing the counter substrate 120B.
• a plurality of data wirings 121 are formed extending in a predetermined direction and arranged in parallel at a predetermined pitch, for example, as shown in FIG. 16.
• a plurality of scan wirings 122 are further formed extending in a direction intersecting (for example, perpendicular to) the data wirings 121 and arranged in parallel at a predetermined pitch.
• the data wirings 121 and the scan wirings 122 are made of a conductive material such as Cu.
• the scan wiring 122 is formed, for example, in the outermost layer, for example, on an insulating layer (not shown) formed on the surface of the substrate.
• the substrate of the mounting board 120A is made of, for example, a silicon substrate or a resin substrate, and the insulating layer on the substrate is made of, for example, SiN, SiO, aluminum oxide (AlO) or a resin material.
• the data wiring 121 is formed in a layer different from the outermost layer including the scan wiring 122 (for example, a layer below the outermost layer), for example, in an insulating layer on the substrate.
• the display pixels 123 are located near the intersections of the data wiring 121 and the scan wiring 122, and multiple display pixels 123 are arranged in a matrix in the display area 100A.
• Each display pixel 123 is implemented with, for example, each of the color pixels Pr, Pg, and Pb of the light-emitting device 1.
• the light emitting device 1 is provided with a pair of terminal electrodes, for example, for each color pixel Pr, Pg, Pb, or one common and the other for each color pixel Pr, Pg, Pb.
• One of the terminal electrodes is electrically connected to the data wiring 121
• the other terminal electrode is electrically connected to the scan wiring 122.
• one of the terminal electrodes is electrically connected to the pad electrode 121B at the tip of the branch 121A provided on the data wiring 121.
• the other terminal electrode is electrically connected to the pad electrode 122B at the tip of the branch 122A provided on the scan wiring 122.
• Each pad electrode 121B, 122B is formed, for example, on the outermost layer, and is provided at the location where each light emitting device 1 is mounted, as shown in FIG. 16.
• the pad electrodes 121B, 122B are made of a conductive material, for example, Au (gold).
• the mounting substrate 120A is further provided with, for example, a number of support pillars (not shown) that regulate the distance between the mounting substrate 120A and the opposing substrate 120B.
• the support pillars may be provided in the opposing region to the display region 100A, or in the opposing region to the frame region 100B.
• the counter substrate 120B is made of, for example, a glass substrate or a resin substrate.
• the surface of the counter substrate 120B facing the light emitting device 1 may be flat, but is preferably rough.
• the rough surface may be provided over the entire area facing the display area 100A, or may be provided only in the area facing the display pixels 123.
• the rough surface has fine irregularities that allow the light emitted from the color pixels Pr, Pg, and Pb to enter the rough surface.
• the irregularities on the rough surface can be created by, for example, sandblasting or dry etching.
• the control circuit 140 drives each display pixel 123 (each light-emitting device 1) based on a video signal.
• the control circuit 140 is composed of, for example, a data driver that drives the data wiring 121 connected to the display pixels 123, and a scan driver that drives the scan wiring 122 connected to the display pixels 123.
• the control circuit 140 may be provided separately from the display panel 120 and connected to the mounting substrate 120A via wiring, or may be mounted on the mounting substrate 120A, as shown in FIG. 15, for example.
• FIG. 17 is a perspective view showing another configuration example (image display device 200) of an image display device using a light-emitting device (e.g., light-emitting device 1) according to the present disclosure.
• the image display device 200 is a so-called tiling display that uses a plurality of light-emitting devices that use LEDs as light sources.
• the image display device 200 includes a display panel 220 and a control circuit 240 that drives the display panel 220.
• the display panel 220 is formed by stacking a mounting substrate 220A and a counter substrate 220B on top of each other.
• the surface of the counter substrate 220B serves as an image display surface, with a display area in the center and a frame area, which is a non-display area, around it (neither is shown).
• the counter substrate 220B is disposed in a position opposite the mounting substrate 220A, for example, with a predetermined gap therebetween.
• the counter substrate 220B may be in contact with the upper surface of the mounting substrate 220A.
• FIG. 18 is a schematic diagram showing an example of the configuration of the mounting board 220A.
• the mounting board 220A is composed of a plurality of unit boards 250 arranged in a tiled pattern. Note that while FIG. 18 shows an example in which the mounting board 220A is composed of nine unit boards 250, the number of unit boards 250 may be ten or more, or eight or less.
• FIG. 19 shows an example of the configuration of the unit board 250.
• the unit board 250 has, for example, a plurality of light emitting devices 1 arranged in a tile-like pattern, and a support board 260 that supports each of the light emitting devices 1.
• Each unit board 250 further has a control board (not shown).
• the support board 260 is, for example, composed of a metal frame (metal plate) or a wiring board. If the support board 260 is composed of a wiring board, it can also serve as the control board. In this case, at least one of the support board 260 and the control board is electrically connected to each of the light emitting devices 1.
• the transparent display 300 has, for example, a display unit 310, an operation unit 311, and a housing 312.
• the light-emitting device of the present disclosure (for example, the light-emitting device 1) is used for the display unit 310.
• This transparent display 300 is capable of displaying images and text information while allowing the background of the display unit 310 to be seen through.
• a light-transmitting substrate is used as the mounting substrate.
• Each electrode provided in the light-emitting device 1 is formed using a light-transmitting conductive material, just like the mounting substrate.
• each electrode is structured to be difficult to see by supplementing the wiring width or reducing the wiring thickness.
• the transparent display 300 can display black by, for example, overlapping a liquid crystal layer equipped with a driving circuit, and switching between transparent and black display is possible by controlling the light distribution direction of the liquid crystal.
• the present technology has been described above by giving embodiments, modifications, and application examples, but the present technology is not limited to the above embodiments, etc., and various modifications are possible.
• the light emitted from the light-emitting element 11 is blue light or ultraviolet light, but this is not limited to this.
• the light-emitting device 1 can also use a light-emitting element that emits two or more types of light, such as blue light and green light, or ultraviolet light and green light.
• each component constituting the light emitting device 1 etc. is specifically described, but it is not necessary to include all components, and other components may also be included.
• the present technology can also be configured as follows. According to the present technology configured as follows, two or more light-emitting elements having a mesa structure are arranged for each pixel. This provides redundancy to each pixel, making it possible to achieve both miniaturization and high brightness.
• a drive circuit board a pixel array portion having a plurality of pixels arranged in an array, and an element substrate having two or more light-emitting elements each having a mesa structure arranged for each pixel, the pixel array portion having a first surface that serves as a light-emitting surface and a second surface opposite to the first surface and facing the drive circuit substrate, the pixel array portion having a plurality of pixels arranged in an array, and an element substrate having two or more light-emitting elements each having a mesa structure arranged for each pixel.
• the light emitting device according to (1) wherein the element substrate further has a wavelength conversion layer provided for each pixel and configured to convert the wavelength of light emitted from two or more of the light emitting elements arranged for each pixel.
• the drive circuit board has a plurality of constant current drive circuits that supply a constant current;
• the drive circuit board has a plurality of constant current drive circuits that supply a constant current;
• the element substrate further includes a plurality of first pad portions on the second surface, the first pad portions being electrically connected to the plurality of light-emitting elements via plugs;
• the drive circuit board further includes a plurality of second pads on the third surface, the second pads being electrically connected to the plurality of constant current drive circuits, respectively;
• a light emitting device comprises: A drive circuit board; an element substrate having a first surface which serves as a light emitting surface and a second surface opposite to the first surface and facing the drive circuit substrate, the element substrate having a pixel array portion in which a plurality of pixels are arranged in an array, and two or more light emitting elements having a mesa structure are arranged for each pixel.

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  • 2024-02-02 JP JP2025502227A patent/JPWO2024176785A1/ja active Pending
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  • 2024-02-02 CN CN202480006193.3A patent/CN120435933A/zh active Pending

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