JP2010040937A - Semiconductor light emitting element, light emitting device, illuminating apparatus, and display - Google Patents

Abstract

A semiconductor light-emitting element, a light-emitting device, a lighting device, and a display device that can extract light more efficiently than before.
On a surface of a substrate, a semiconductor layer is formed by laminating an undoped GaN layer, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer in this order. An ohmic electrode 9 is formed on a part of the semiconductor layer 30 on the surface of the n-type semiconductor layer 3 exposed by removing the p-type semiconductor layer 5 and the active layer 4 by etching or the like. A bonding electrode (n pad) 7 is formed on the substrate 1. The bonding electrode 7 extends so as to cover the ohmic electrode 9 and is connected to the ohmic electrode 9. A coating film 11 that covers the outer peripheral side surface of the semiconductor layer 30 is formed on another side surface of the semiconductor layer 30. In the vicinity of the semiconductor layer 30 on which the coating film 11 is formed, the substrate 1 A bonding electrode (p pad) 8 is formed thereon.
[Selection] Figure 2

Description

  The present invention relates to a semiconductor light emitting element used for a light emitting diode or a laser diode, a light emitting device including the semiconductor light emitting element, an illumination device including the light emitting device, and a display device.

  Gallium nitride (GaN) -based compound semiconductors are widely used in various fields because of their high luminous efficiency in the ultraviolet to blue wavelength region. For example, application to the illumination field using a white light source in which a light emitting diode using a gallium nitride compound semiconductor is combined with a phosphor has begun. However, replacing fluorescent lamps of several tens to 100W used in ordinary homes and offices with light-emitting diodes requires further improvements in light-emitting diodes such as high cost and heat dissipation. It has been.

Conventionally, techniques for improving light extraction efficiency by crystal growth, active layer structure, electrode material, arrangement of electrodes on a chip, surface microfabrication, and the like have been developed. For example, a semiconductor light-emitting element that can improve the light-emitting efficiency of a light-emitting element by disposing bonding electrodes in the corners of the light-emitting element is disclosed (see Patent Document 1).
Japanese Patent No. 2748818

  However, in the semiconductor light emitting device of Patent Document 1 and the conventional semiconductor light emitting device, a semiconductor layer in which an n-type layer, an active layer, and a p-type layer are stacked in this order is formed on the substrate surface, and the p-type layer and the active layer are removed. One bonding electrode was provided on the surface of the exposed n-type layer. The light emitted from the semiconductor layer is extracted from the surface of the semiconductor layer, the surface or the side surface of the substrate, and the like. However, of the light emitted from the semiconductor layer, the light that has entered the lower side of the electrode is highly likely to be absorbed by the lower surface of the electrode, which is one of the factors that reduce the luminous efficiency of the entire device. For this reason, it has been desired to further improve the light emission efficiency as compared with the prior art.

  The present invention has been made in view of such circumstances, and a semiconductor light emitting device capable of extracting light more efficiently than the prior art by providing a bonding electrode on a substrate surface on which a semiconductor layer is not formed or removed. An object of the present invention is to provide a light-emitting device including the semiconductor light-emitting element, a lighting device including the light-emitting device, and a display device.

  Another object of the present invention is to provide a semiconductor light emitting device capable of further improving the light emission efficiency by separating the portion where electrical connection with the n-type layer or the p-type layer is separated from the position of the bonding electrode, and the semiconductor A light-emitting device including a light-emitting element, an illumination device including the light-emitting device, and a display device are provided.

  The semiconductor light emitting device according to the first aspect of the present invention is a semiconductor light emitting device in which a semiconductor layer in which an n-type layer, an active layer, and a p-type layer are stacked in order is formed on a part of a substrate surface. It is characterized in that at least one of an n-type layer and a p-type layer bonding electrode is provided on the substrate surface portion from which the semiconductor layer is removed, which is higher than the optical refractive index of the substrate.

  A semiconductor light emitting device according to a second invention is the semiconductor light emitting device according to the first invention, wherein an undoped semiconductor layer is formed on the substrate surface including the lower side of the n-type layer, and the bonding electrode is provided on the surface of the undoped semiconductor layer. It is characterized by being.

  A semiconductor light emitting device according to a third invention is the n-type layer junction electrode formed on the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer in the first invention or the second invention. And a conductive film that connects the n-type layer bonding electrode and the n-type layer bonding electrode.

  A semiconductor light emitting device according to a fourth invention is the n-type layer junction electrode formed on the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer in the first invention or the second invention. The n-type layer bonding electrode extends to the bonding electrode for the n-type layer and is connected to the bonding electrode.

  A semiconductor light emitting device according to a fifth invention is the n-type layer junction electrode formed on the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer in the first invention or the second invention. The n-type layer bonding electrode extends to the n-type layer bonding electrode and is connected to the n-type layer bonding electrode.

  According to a sixth aspect of the present invention, there is provided the semiconductor light emitting device according to the first or second aspect, wherein the n-type layer bonding electrode is exposed by removing a part of the p-type layer and the active layer. It extends to the surface and is directly connected to the n-type layer, and the bonding electrode for the n-type layer also serves as an n-type bonding electrode.

  A semiconductor light emitting device according to a seventh invention is the semiconductor light emitting device according to the first invention or the second invention, wherein a current diffusion layer is formed on the surface of the p-type layer, and the bonding electrode for the p-type layer is at least a p-type layer, an active layer A layer, an undoped layer exposed by removing the n-type layer, or a substrate surface, a coating film covering an outer peripheral side surface exposed by etching of the semiconductor layer, and the current diffusion layer on the surface of the coating film And a conductive film for connecting the bonding electrode for the p-type layer.

  According to an eighth aspect of the present invention, there is provided the semiconductor light emitting device according to the first or second aspect, wherein a current diffusion layer is formed on the surface of the p-type layer, and the bonding electrode for the p-type layer includes at least the p-type layer, the active layer A layer, an undoped layer exposed by removing the n-type layer, or a substrate surface, and a current diffusion auxiliary wiring connected to the current diffusion layer and a coating covering the outer peripheral side surface exposed by etching of the semiconductor layer And a conductive film connecting the current diffusion auxiliary wiring and the p-type layer bonding electrode to the surface of the coating film.

  According to a ninth aspect of the present invention, in the seventh or eighth aspect, the conductive film and the n-type layer junction electrode are metal films made of the same material.

  According to a tenth aspect of the present invention, there is provided a semiconductor light emitting device according to the seventh aspect of the present invention, further comprising: a current diffusion layer formed on the surface of the p-type layer, and a coating film covering an outer peripheral side surface exposed by etching of the semiconductor layer; The bonding electrode for the p-type layer extends over the surface of the coating film to the current diffusion layer and is connected to the current diffusion layer.

  According to an eleventh aspect of the present invention, there is provided the semiconductor light emitting device according to the eighth aspect, wherein a current diffusion layer is formed on the surface of the p-type layer, a current diffusion auxiliary wiring connected to the current diffusion layer, and etching of the semiconductor layer. And the p-type layer bonding electrode extends to the current diffusion auxiliary wiring and is connected to the current diffusion auxiliary wiring. It is characterized by being.

  A semiconductor light-emitting device according to a twelfth aspect of the present invention is the semiconductor light-emitting element according to the eighth aspect of the present invention, wherein a current diffusion layer is formed on the surface of the p-type layer, a current diffusion auxiliary wiring connected to the current diffusion layer, and etching of the semiconductor layer A coating film covering the outer peripheral side surface exposed by the step, wherein the current diffusion auxiliary wiring extends on the surface of the coating film to the bonding electrode for the p-type layer and is connected to the bonding electrode. It is characterized by being.

  A semiconductor light emitting device according to a thirteenth aspect of the present invention is the semiconductor light emitting device according to any one of the first to twelfth aspects of the present invention, wherein the bonding electrode is a metal film of an alloy mainly composed of Ag, Al, Au, or Pd, or any one of them. It is characterized by having.

  According to a fourteenth aspect of the present invention, in the thirteenth aspect, the thickness of the metal film is 100 nm or more.

  A semiconductor light emitting device according to a fifteenth invention is characterized in that, in the thirteenth or fourteenth invention, a separation dimension between the lowermost surface of the metal film and the substrate surface is 50 nm or less.

  A light-emitting device according to a sixteenth aspect of the present invention includes the semiconductor light-emitting element according to any one of the first to fifteenth aspects of the present invention and a housing portion that houses the semiconductor light-emitting element.

  An illuminating device according to a seventeenth aspect includes the light emitting device according to the sixteenth aspect.

  A display device according to an eighteenth aspect of the invention includes the light emitting device according to the sixteenth aspect of the invention.

  In the first invention, the optical refractive index of the semiconductor layer on the substrate surface is higher than the optical refractive index of the substrate. For example, when the semiconductor layer is a gallium nitride compound semiconductor, the optical refractive index is about 2.5, and when the substrate is a sapphire substrate, the optical refractive index is about 1.77. At least one of the n-type and p-type bonding electrodes is provided on the substrate surface where the semiconductor layer is not formed or removed. Conventionally, for example, a semiconductor layer in which an n-type layer, an active layer, and a p-type layer are stacked in this order is formed on a sapphire substrate, and a part of the p-type layer and the active layer are removed to expose the surface of the n-type layer. In this configuration, a bonding electrode for the n-type layer is provided. In this case, a Gan-based semiconductor layer having a high optical refractive index (for example, about 2.5) is provided below the bonding electrode, and a sapphire substrate having a low optical refractive index (for example, about 1.77) is provided below the bonding electrode. Is placed. Since there is a difference in the optical refractive index at the boundary between the Gan-based semiconductor layer and the substrate, the light entering the substrate side from the Gan-based semiconductor layer side may be totally reflected at the boundary surface depending on the incident angle. As the GaN-based semiconductor layer under the portion where the n-type bonding electrode is provided is thicker, light becomes easier to enter thereunder. The incident light travels while being repeatedly reflected at the boundary surface between the semiconductor layer and the substrate and the boundary surface between the semiconductor layer and the bonding electrode. However, because of the absorption at the lower surface of the bonding electrode, the thicker the semiconductor layer, the higher the bonding. The amount of light absorbed by the lower surface of the electrode increases, and the light extraction efficiency decreases. On the other hand, when the bonding electrode is provided on the surface of the substrate, the light density in the substrate below the bonding electrode is smaller than that of the GaN-based semiconductor layer, so that the light absorbed by the lower surface of the bonding electrode is reduced and the light is extracted. Efficiency is improved.

  In the second invention, the undoped semiconductor layer is formed on the substrate surface, and the semiconductor layer is formed on the surface. The bonding electrode is provided on the surface of the undoped semiconductor layer exposed by removing a part of the p-type layer, the active layer, and the n-type layer. As a result, the thickness of the semiconductor layer below the bonding electrode can be reduced, the light entering the lower side of the bonding electrode is reduced, the light absorbed on the lower surface of the bonding electrode is reduced, and the light extraction efficiency is improved. Can be improved. In this case, the undoped semiconductor layer can be removed and a bonding electrode can be provided on the substrate surface.

  In the third invention, the n-type layer junction electrode is formed on the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer. The n-type layer junction electrode is a portion that performs electrical junction (ohmic junction) with the n-type layer. The n-type layer bonding electrode and the n-type layer bonding electrode are connected by a conductive film. As a result, it is possible to physically separate the bonding electrode and the portion that performs electrical bonding with the semiconductor layer, and the material of the n-type layer bonding electrode and the material of the bonding electrode can be separated. For example, the material of the n-type layer junction electrode can be a metal having a low contact resistance, and the material of the bonding electrode having a relatively large occupied area on the substrate can be a metal having a high optical reflectivity. Can be improved. Alternatively, the bonding electrode may be a metal having excellent mechanical strength.

  In the fourth invention, the n-type layer junction electrode is formed on the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer. The n-type layer junction electrode is a portion that performs electrical junction (ohmic junction) with the n-type layer. The n-type layer bonding electrode extends to the bonding electrode for the n-type layer and is connected to the bonding electrode. As a result, it is possible to physically separate the bonding electrode and the portion that performs electrical bonding with the semiconductor layer, and the material of the n-type layer bonding electrode and the material of the bonding electrode can be separated. For example, the material of the n-type layer junction electrode can be a metal having a low contact resistance, and the material of the bonding electrode having a relatively large occupied area on the substrate can be a metal having a high optical reflectivity. Can be improved. Alternatively, the bonding electrode may be a metal having excellent mechanical strength. In addition, since the n-type layer bonding electrode extends to the bonding electrode for the n-type layer and is connected to the bonding electrode, a process of forming a conductive film for connecting the n-type layer bonding electrode and the bonding electrode becomes unnecessary. The manufacturing process can be simplified.

  In the fifth invention, the n-type layer junction electrode is formed on the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer. The n-type layer junction electrode is a portion that performs electrical junction (ohmic junction) with the n-type layer. The bonding electrode for the n-type layer extends to the n-type layer bonding electrode and is connected to the n-type layer bonding electrode. As a result, it is possible to physically separate the bonding electrode and the portion that performs electrical bonding with the semiconductor layer, and the material of the n-type layer bonding electrode and the material of the bonding electrode can be separated. For example, the material of the n-type layer junction electrode can be a metal having a low contact resistance, and the material of the bonding electrode having a relatively large occupied area on the substrate can be a metal having a high optical reflectivity. Can be improved. Alternatively, the bonding electrode may be a metal having excellent mechanical strength. In addition, since the bonding electrode for the n-type layer extends to the n-type layer bonding electrode and is connected to the n-type layer bonding electrode, there is a process of forming a conductive film for connecting the n-type layer bonding electrode and the bonding electrode. It becomes unnecessary, and the manufacturing process can be simplified.

  In the sixth invention, the bonding electrode for the n-type layer is extended to the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer and directly connected to the n-type layer. It is. The n-type layer bonding electrode also serves as an n-type junction electrode. This eliminates the need for an n-type layer bonding electrode forming step for electrical bonding with the n-type layer and a conductive film forming step for connecting the n-type layer bonding electrode and the bonding electrode, further simplifying the manufacturing process. Can be

  In the seventh invention, a current diffusion layer is formed on the surface of the p-type layer, and a coating film for covering the outer peripheral side surface exposed by etching of the semiconductor layer is formed. For example, a transparent dielectric film can be used as the coating film, and an electrical short circuit between the n-type layer and active layer exposed on the side surface of the semiconductor layer and the p-type bonding electrode is prevented. A conductive film for connecting the current diffusion layer and the p-type bonding electrode is formed on the surface of the coating film. As a result, it is possible to physically separate the bonding electrode and the portion that is electrically connected to the current diffusion layer, and to separate the bonding electrode material and the wiring material that connects the bonding electrode and the current diffusion layer. It becomes possible. For example, the wiring material can be a metal having a low contact resistance with the current diffusion layer, and the bonding electrode material having a relatively large occupation area on the substrate can be a metal having a high optical reflectance. The extraction efficiency can be improved. Alternatively, the bonding electrode may be a metal having excellent mechanical strength.

  In the eighth invention, the current diffusion layer is formed on the surface of the p-type layer, and the current diffusion auxiliary wiring is connected to the current diffusion layer. The current diffusion auxiliary wiring may be provided on the surface of the current diffusion layer, may be provided on the surface of the p-type layer, or may be configured so as to straddle both the surface of the p-type layer and the surface of the current diffusion layer. A coating film is formed to cover the outer peripheral side surface exposed by etching of the semiconductor layer. For example, a transparent dielectric film can be used as the coating film, and an electrical short circuit between the n-type layer and active layer exposed on the side surface of the semiconductor layer and the p-type bonding electrode is prevented. A conductive film for connecting the current diffusion auxiliary wiring and the p-type bonding electrode is formed on the surface of the coating film. As a result, it is possible to physically separate the bonding electrode from the portion that is electrically connected to the current diffusion auxiliary wiring, and the material of the current diffusion auxiliary wiring and the material of the bonding electrode can be separated. For example, the material of the current diffusion auxiliary wiring can be a metal having a low contact resistance with the current diffusion layer, and the material of the bonding electrode having a relatively large occupation area on the substrate can be a metal having a high optical reflectance. The light extraction efficiency can be improved. Alternatively, the bonding electrode may be a metal having excellent mechanical strength.

  In the ninth invention, the n-type layer bonding electrode and the conductive film formed on the surface of the coating film are metal films made of the same material. Thereby, the conductive film and the n-type layer junction electrode can be formed at the same time, and the manufacturing process can be further simplified.

  In the tenth invention, a current diffusion layer is formed on the surface of the p-type layer, and a coating film is formed to cover the outer peripheral side surface exposed by etching of the semiconductor layer. For example, a transparent dielectric film can be used as the coating film, and an electrical short circuit between the n-type layer and active layer exposed on the side surface of the semiconductor layer and the p-type bonding electrode is prevented. A p-type bonding electrode is extended to the current diffusion layer on the surface of the coating film and connected to the current diffusion layer. This eliminates the need for a conductive film forming step for connecting the current diffusion layer and the p-type bonding electrode, thereby simplifying the manufacturing process.

  In the eleventh invention, the current diffusion layer is formed on the surface of the p-type layer, and the current diffusion auxiliary wiring is connected to the current diffusion layer. The current diffusion auxiliary wiring may be provided on the surface of the current diffusion layer, may be provided on the surface of the p-type layer, or may be configured so as to straddle both the surface of the p-type layer and the surface of the current diffusion layer. A coating film is formed to cover the outer peripheral side surface exposed by etching of the semiconductor layer. For example, a transparent dielectric film can be used as the coating film, and an electrical short circuit between the n-type layer and active layer exposed on the side surface of the semiconductor layer and the p-type bonding electrode is prevented. On the surface of the coating film, a p-type bonding electrode is extended to the current diffusion auxiliary wiring and connected to the current diffusion auxiliary wiring. This eliminates the need for a conductive film forming step for connecting the current diffusion auxiliary wiring and the p-type bonding electrode, thereby simplifying the manufacturing process.

  In the twelfth invention, the current diffusion layer is formed on the surface of the p-type layer, and the current diffusion auxiliary wiring is connected to the current diffusion layer. The current diffusion auxiliary wiring may be provided on the surface of the current diffusion layer, may be provided on the surface of the p-type layer, or may be configured so as to straddle both the surface of the p-type layer and the surface of the current diffusion layer. A coating film is formed to cover the outer peripheral side surface exposed by etching of the semiconductor layer. For example, a transparent dielectric film can be used as the coating film, and an electrical short circuit between the n-type layer and active layer exposed on the side surface of the semiconductor layer and the p-type bonding electrode is prevented. On the surface of the coating film, a current diffusion auxiliary wiring extends to the p-type bonding electrode and is connected to the p-type bonding electrode. This eliminates the need for a conductive film forming step for connecting the current diffusion auxiliary wiring and the p-type bonding electrode, thereby simplifying the manufacturing process.

  In the thirteenth invention, the bonding electrode has a metal film of Ag, Al, Au, Pd, or an alloy mainly composed of any one of them. In this case, the entire bonding electrode may be a metal film of an alloy mainly composed of Ag, Al, Au, or Pd, or one of them, or a part of the bonding electrode may be the metal film. Thereby, the light reflectance at the bonding electrode can be increased, the amount of light absorbed at the lower surface of the bonding electrode can be reduced, and the light extraction efficiency can be improved.

  In the fourteenth invention, the thickness of the metal film is 100 nm or more. When the film thickness is less than 100 nm, the light reflectance cannot be increased, and the amount of light absorbed by the lower surface of the bonding electrode increases. The light extraction efficiency can be improved by setting the film thickness to 100 nm or more.

  In the fifteenth aspect of the invention, the distance between the lowermost surface of the metal film and the substrate surface is 50 nm or less. If the lowermost layer of the bonding electrode is not a metal film composed mainly of Ag, Al, Au, Pd, or any one of them, the light reflectance decreases when the separation dimension exceeds 50 nm and is absorbed by the lower surface of the bonding electrode. The amount of light that is increased. The light extraction efficiency can be improved by setting the separation dimension to 50 nm or less.

  In the sixteenth invention, a light-emitting device accommodates the above-described semiconductor light-emitting element. Thereby, the light-emitting device which can improve the extraction efficiency of light can be provided.

  According to the seventeenth aspect of the present invention, it is possible to provide an illumination device with improved light extraction efficiency by including the above-described light emitting device.

  In the eighteenth aspect of the invention, a display device with improved light extraction efficiency can be provided by including the above-described light emitting device.

  According to the present invention, it is possible to reduce the light that enters the lower side of the bonding electrode, the amount of light absorbed by the lower surface of the bonding electrode is reduced, and light can be extracted more efficiently than in the past.

Embodiment 1
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof. FIG. 1 is a plan view of a semiconductor light emitting device 100 according to the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. A semiconductor light emitting device (hereinafter, referred to as a light emitting device) 100 is obtained by cutting a wafer on which a plurality of light emitting devices are formed into a rectangular parallelepiped shape with a predetermined size, and separating each light emitting device, for example, an LED chip. 1 and 2, reference numeral 1 denotes a sapphire substrate. The vertical and horizontal dimensions of the sapphire substrate 1 (hereinafter referred to as a substrate) are, for example, approximately 0.1 mm to 1 mm.

  At the center of the upper surface (upper surface) of the substrate 1, an AlN buffer layer (not shown), an undoped GaN layer 2, an n-type semiconductor layer 3, an active layer 4, and a p-type semiconductor layer 5 are laminated in this order. The film thickness of the undoped GaN layer 2 is, for example, about 2 μm. The n-type semiconductor layer 3 is composed of, for example, an n-GaN (gallium nitride) layer of about 2 μm, an n-AlGaInN cladding layer, and the like. The active layer 4 is composed of a GaN / InGaN-MQW (Multi-quantum Well) type active layer or the like. The p-type semiconductor layer 5 includes a p-AlGaInN layer, a p-GaN layer of about 0.3 μm, a p-InGaN layer as a contact layer, and the like. Thereby, the compound semiconductor layer is formed, and the LED structure as the semiconductor layer 30 is formed. In addition, the structure which does not form the undoped GaN layer 2 may be sufficient.

  A current diffusion layer 6 is formed on the upper surface of the p-type semiconductor layer 5. The current diffusion layer 6 is, for example, an ITO film (indium tin oxide film) that is a conductive transparent film. An ohmic electrode 9 is formed on a part of the semiconductor layer 30 on the surface of the n-type semiconductor layer 3 exposed by removing the p-type semiconductor layer 5 and the active layer 4 by etching or the like.

  The ohmic electrode 9 is formed, for example, by depositing V / Al / V / Au by vacuum deposition, patterning by a lift-off method, and heating to about 500 ° C. by RTA (Rapid Thermal anneal) in an Ar atmosphere. Can do. The ohmic electrode 9 is a part that performs electrical junction with the n-type semiconductor layer 3.

  A bonding electrode (n pad) 7 is formed on the substrate 1 in the vicinity of the semiconductor layer 30 on which the ohmic electrode 9 is formed. The bonding electrode 7 extends so as to cover the ohmic electrode 9 and is connected to the ohmic electrode 9. Thereby, the ohmic electrode 9 and the bonding electrode 7 are electrically connected.

  A coating film 11 that covers the outer peripheral side surface of the semiconductor layer 30 is formed on the side surface in a location different from the ohmic electrode in the vicinity of the semiconductor layer 30. As the coating film 11, for example, a transparent dielectric film can be used. A bonding electrode (p pad) 8 is formed on the substrate 1 in the vicinity of the semiconductor layer 30 on which the coating film 11 is formed.

  The bonding electrode 8 extends on the surface of the coating film 11 to the current diffusion layer 6, is connected to the current diffusion layer 6, and constitutes the current diffusion auxiliary wiring 10 on the surface of the current diffusion layer 6. is doing. Thereby, the bonding electrode 8 and the current diffusion layer 6 are electrically connected. The coating film 11 prevents the bonding electrode 8 from being in electrical contact with the N-type semiconductor layer 3 and the active layer 4.

  As shown in FIG. 1, the bonding electrodes 7, 8 are circular in plan view, and are arranged at substantially the center of the peripheral part of the opposing sides of the rectangular substrate 1.

  The bonding electrodes 7 and 8 have a metal film made of Ag, Al, Au, Pd, or an alloy mainly composed of any one of them. In this case, the bonding electrodes 7 and 8 as a whole may be Ag, Al, Au, Pd, or an alloy metal film mainly composed of any one of them, or a part of the bonding electrodes 7 and 8 may be the above-described metal film. It is good. The film thickness of the metal film is 100 nm or more. When a layer having a composition different from that of the above-described metal film such as an AlN buffer layer is present on the lowermost surface of the bonding electrodes 7 and 8, the thickness of the layer is set to 50 nm or less.

  Wires (not shown) are bonded to the bonding electrodes 7 and 8, and positive and negative voltages are applied from the outside. Thereby, the current from the bonding electrode 8 flows through the current diffusion auxiliary wiring 10, flows through the entire current diffusion layer 6 to the p-type semiconductor layer 5, the active layer 4, and the n-type semiconductor layer 3, and then through the ohmic electrode 9 to the bonding electrode 7. Thus, light can be emitted in a wide range of the active layer 4.

  When the light emitting element 100 has the above-described configuration, light emitted from the active layer 4 inside the light emitting element 100 can be extracted from the upper surface side and the side surface side of the light emitting element 100. In the case where an LED package (light emitting device) is configured by incorporating the light emitting element 100 into, for example, a shell type or surface mount type package, a reflection structure that reflects light on the upper surface of the package is provided on the package side. It is possible to emit light efficiently.

  FIG. 3 is a schematic diagram showing a state of light emitted from the semiconductor layer 30. FIG. 3A shows the case of a conventional semiconductor light emitting device, and FIG. 3B shows the case of the light emitting device 100 of the present invention. When the substrate 1 is a sapphire substrate, the optical refractive index is about 1.77. When the semiconductor layer composed of the n-type semiconductor layer 3, the active layer 4, and the p-type semiconductor layer 5 is a gallium nitride compound semiconductor, the optical refractive index is about 2.5.

  As shown in FIG. 3A, the conventional light emitting device has a configuration in which the bonding electrode 7 is provided on the surface of the n-type semiconductor layer 3 exposed by removing the p-type semiconductor layer 5 and the active layer 4 by etching or the like. It was. In this case, the n-type semiconductor layer 3 having a high light refractive index (for example, about 2.5) is provided below the bonding electrode 7 and a substrate having a low light refractive index (for example, about 1.77) is further provided therebelow. 1 is arranged. Since there is a difference in optical refractive index at the boundary between the n-type semiconductor layer 3 and the substrate 1, the light entering the substrate 1 from the n-type semiconductor layer 3 may be totally reflected at the boundary surface depending on the incident angle. is there. Then, light entering the n-type semiconductor layer 3 below the bonding electrode 7 increases. For this reason, more light is absorbed by the lower surface of the bonding electrode 7 and the light extraction efficiency is reduced.

  On the other hand, as shown in FIG. 3B, in the light emitting device 100 of the present invention, since the bonding electrode 7 is provided on the surface of the substrate 1, the n-type semiconductor layer 3 is disposed below the bonding electrode 7. As in the case where the bonding electrode 7 is present, there is not much light that enters the lower side of the bonding electrode 7, and less light is absorbed by the lower surface of the bonding electrode 7, thereby improving the light extraction efficiency.

  3, the undoped semiconductor layer on the surface of the substrate 1 is omitted. However, when the undoped semiconductor layer is present, the p-type semiconductor layer 5, the active layer 4, and the n-type semiconductor layer 3 are removed. The bonding electrode 7 may be provided on the surface of the exposed undoped semiconductor layer (not shown). In this case, the thickness of the semiconductor layer below the bonding electrode 7 can be reduced, the light entering the lower side of the bonding electrode 7 is reduced, and the light absorbed on the lower surface of the bonding electrode 7 is reduced. The light extraction efficiency can be improved.

  Although the case of the bonding electrode 7 has been described with reference to FIG. 3, the same applies to the bonding electrode 8.

  Next, a method for manufacturing the light emitting device 100 according to the present invention will be described. 4 and 5 are explanatory views showing manufacturing steps of the light emitting device 100. FIG. As shown in FIG. 4A, an AlN buffer layer (not shown) is first grown at about 400 ° C. on a substrate (sapphire substrate) 1 by metal organic chemical vapor deposition (MO-CVD). Thereafter, an undoped GaN layer 2 of about 2 μm, an n-GaN layer of about 2 μm, an n-type semiconductor layer 3 made of an n-AlGaInN cladding layer, a GaN / InGaN-MQW type active layer 4, a p-AlGaInN layer, An LED structure in which a p-type semiconductor layer 5 including a p-GaN layer of about 0.3 μm and a p-InGaN layer as a contact layer is formed in this order is generated. While irradiating the substrate 1 taken out from the MO-CVD apparatus with ultraviolet rays, the substrate 1 is heated to about 400 ° C. to activate the p-type semiconductor layer 5.

  As shown in FIG. 4B, by photolithography and dry etching, the outer peripheral portion of the light emitting element 100, the portion where the bonding electrode (n pad) 7 and the bonding electrode (p pad) 8 are arranged are formed using the photoresist as a mask. Dry etching is performed with a chlorine-based gas until the surface of the substrate 1 is exposed.

  Next, as shown in FIG. 4C, the p-type semiconductor layer 5 and the active layer 4 are removed by dry etching and etching is performed until the n-type semiconductor layer 3 is exposed, and an ohmic electrode (n-ohmic electrode) 9 is formed. A region 31 to be provided is formed.

  Next, as shown in FIG. 4D, a current diffusion layer 6 is formed by depositing an ITO film, which is a conductive transparent film, on the surface of the p-type semiconductor layer 5 by vacuum deposition and sputtering to about 200 nm.

  Next, as shown in FIG. 5 (e), V / Al / V / Au is deposited by vacuum deposition, patterned by the lift-off method, and heated to about 500 ° C. by RTA (Rapid Thermal Anneal) in an Ar atmosphere. The ohmic electrode 9 and the ITO film are annealed simultaneously by heating. Thereby, the ohmic electrode 9 is formed.

Next, a SiO ₂ film is formed on the entire surface by plasma CVD. As shown in FIG. 5F, a portion where the bonding electrodes 7 and 8 are provided by diluted hydrofluoric acid, the current diffusion layer 6 and the bonding electrode (p The bonding portion with the pad 8 and the SiO ₂ film at the element isolation portion (end portion of the substrate 1) are removed. In FIG. 5F and subsequent figures, a coating film (SiO2) covering the side surface of the semiconductor layer formed by laminating the undoped GaN layer 2, the n-type semiconductor layer 3, the active layer 4, the p-type semiconductor layer 5, and the like. Only _two films 11 are shown, and the other SiO ₂ films are omitted.

  Further, as shown in FIG. 5G, in order to form the bonding electrodes 7 and 8 and the current diffusion auxiliary wiring 10, a Ti / Au film is formed by vacuum deposition and patterned by lift-off. Thereafter, element separation is performed by laser scribing to complete an LED wafer (semiconductor light emitting element). The coating film 11 prevents an electrical short circuit between the bonding electrode 8 and the n-type semiconductor layer 3 and the active layer 4 exposed on the side surface of the semiconductor layer.

  In this case, the bonding electrode (n pad) 7 extends to the ohmic electrode (n-type layer bonding electrode) 9 and is connected to the ohmic electrode 9. Thereby, the part (ohmic electrode 9) and the bonding electrode 7 which electrically connect with a semiconductor layer can be physically separated, and the material of the ohmic electrode 9 and the material of the bonding electrode 7 can be separated. It becomes. For example, the material of the ohmic electrode 9 is a metal having a low contact resistance (for example, V / Al / V / Au), and the material of the bonding electrode 7 having a relatively large occupation area on the substrate is a metal having a high optical reflectance (for example, Ni / Al), the amount of light absorbed by the lower surface of the bonding electrode 7 can be reduced, and the light extraction efficiency can be improved. Alternatively, the material of the bonding electrode 7 may be a metal having excellent mechanical strength (for example, Ti / Au, Ni / Au, etc.). Thereby, it becomes easy to bond and it becomes difficult to peel off. In addition, since the bonding electrode 7 extends to the ohmic electrode 9 and is connected to the ohmic electrode 9, a process of forming a conductive film for connecting the ohmic electrode 9 and the bonding electrode 7 becomes unnecessary, and the manufacturing process is simplified. be able to.

  Further, on the surface of the coating film 11, the bonding electrode 8 extends to the current diffusion layer 6 and is connected to the current diffusion layer 6. Thereby, the formation process of the electrically conductive film for connecting the electric current diffusion layer 6 and the bonding electrode 8 becomes unnecessary, and a manufacturing process can be simplified. Further, the bonding electrode 8 and the current diffusion auxiliary wiring 10 can be formed simultaneously.

  In the above example, the current diffusion auxiliary wiring 10 may not be provided.

  Since the light emitting element 100 has a configuration in which the bonding electrode 7 is provided on the surface of the substrate 1, the light entering the lower side of the bonding electrode 7 as in the case where the n-type semiconductor layer 3 is disposed below the bonding electrode 7. The amount of light absorbed by the lower surface of the bonding electrode 7 is reduced, and the light extraction efficiency is improved. Further, since the bonding electrode 8 is also provided on the surface of the substrate 1, light absorbed by the lower surface of the bonding electrode 8 is reduced, and light extraction efficiency is improved.

Embodiment 2
6 is a plan view of the semiconductor light emitting device 110 according to the second embodiment, and FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. The same parts as those in the first embodiment are denoted by the same reference numerals. A semiconductor light emitting device (hereinafter, referred to as a light emitting device) 110 is obtained by cutting a wafer on which a plurality of light emitting devices are formed into a rectangular parallelepiped shape with a predetermined size, and separating each light emitting device, for example, an LED chip. 6 and 7, reference numeral 1 denotes a sapphire substrate. The vertical and horizontal dimensions of the sapphire substrate 1 (hereinafter referred to as a substrate) are, for example, approximately 0.1 mm to 1 mm.

  Similar to the first embodiment, an AlN buffer layer (not shown), an undoped GaN layer 2, an n-type semiconductor layer 3, an active layer 4, and a p-type semiconductor layer 5 are provided at the center of the upper surface (upper surface) of the substrate 1. They are stacked in this order. Thereby, the compound semiconductor layer is formed, and the LED structure as the semiconductor layer 30 is formed. In addition, the structure which does not form the undoped GaN layer 2 may be sufficient.

  A current diffusion layer 6 is formed on the upper surface of the p-type semiconductor layer 5. The current diffusion layer 6 is, for example, an ITO film (indium tin oxide film) that is a conductive transparent film. In the approximate center of the semiconductor layer 30, there is a portion where the semiconductor layer 30 is removed by etching in order to provide an n-type bonding electrode, and the substrate 1 is exposed around the p-type semiconductor layer 5 and the active layer 4. An ohmic electrode 9 is formed on the surface of the n-type semiconductor layer 3 exposed by being removed by etching or the like.

  The ohmic electrode 9 is formed, for example, by depositing V / Al / V / Au by vacuum deposition, patterning by a lift-off method, and heating to about 500 ° C. by RTA (Rapid Thermal anneal) in an Ar atmosphere. Can do. The ohmic electrode 9 is a part that performs electrical junction with the n-type semiconductor layer 3.

  A bonding electrode (n pad) 7 is formed on the substrate 1 inside the semiconductor layer 30 on which the ohmic electrode 9 is formed. The bonding electrode 7 extends so as to cover the ohmic electrode 9 and is connected to the ohmic electrode 9. Thereby, the ohmic electrode 9 and the bonding electrode 7 are electrically connected.

  A coating film 11 that covers the outer peripheral side surface of the semiconductor layer 30 is formed on the side surface of the semiconductor layer 30 that faces the p-type bonding electrode 8. As the coating film 11, for example, a transparent dielectric film can be used. A bonding electrode (p pad) 8 is formed on the substrate 1 in the vicinity of the semiconductor layer 30 on which the coating film 11 is formed.

  A current diffusion auxiliary wiring 12 is formed on the surface of the current diffusion layer 6. The current diffusion auxiliary wiring 12 is formed, for example, by depositing V / Al / V / Au by vacuum deposition, patterning by a lift-off method, and heating to about 500 ° C. by RTA (Rapid Thermal Anneal) in an Ar atmosphere. can do. The current diffusion auxiliary wiring 12 is a portion that performs electrical junction with the p-type semiconductor layer 5 via the current diffusion layer 6.

The bonding electrode 8 extends to the current diffusion auxiliary wiring 12 on the surface of the coating film 11 and is connected to the current diffusion auxiliary wiring 12. Thereby, the bonding electrode 8 and the current diffusion auxiliary wiring 12 are electrically connected. The coating film 11 prevents the bonding electrode 8 from being in electrical contact with the N-type semiconductor layer 3 and the active layer 4.

  As shown in FIG. 6, the bonding electrodes 7 and 8 have a circular shape in plan view, and the bonding electrode (n-pad) 7 is disposed at a substantially central portion of the rectangular substrate 1, and the bonding electrode (p The pad) 8 is disposed at the corner of the substrate 1.

  The bonding electrodes 7 and 8 have a metal film made of Ag, Al, Au, Pd, or an alloy mainly composed of any one of them. In this case, the bonding electrodes 7 and 8 as a whole may be Ag, Al, Au, Pd, or an alloy metal film mainly composed of any one of them, or a part of the bonding electrodes 7 and 8 may be the above-described metal film. It is good. The film thickness of the metal film is 100 nm or more. Further, when an undoped GaN layer exists between the bonding electrodes 7 and 8 and the substrate 1, the thickness of the layer is set to 50 nm or less.

  Wires (not shown) are bonded to the bonding electrodes 8 and 7, and positive and negative voltages are respectively applied from the outside. Thereby, the current from the bonding electrode 8 flows through the current diffusion auxiliary wiring 12, flows through the entire current diffusion layer 6 to the p-type semiconductor layer 5, the active layer 4, and the n-type semiconductor layer 3, and then through the ohmic electrode 9 to the bonding electrode 7. Thus, light can be emitted in a wide range of the semiconductor layer 30.

  Also in the second embodiment, as in the first embodiment, since the light emitting element 110 has a configuration in which the bonding electrode 7 is provided on the surface of the substrate 1, the n-type semiconductor layer 3 is disposed below the bonding electrode 7. As in the case where the bonding electrode 7 is present, there is not much light that enters the lower side of the bonding electrode 7, and less light is absorbed by the lower surface of the bonding electrode 7, thereby improving the light extraction efficiency. Further, since the bonding electrode 8 is also provided on the surface of the substrate 1, light absorbed by the lower surface of the bonding electrode 8 is reduced, and light extraction efficiency is improved.

  Next, a method for manufacturing the light-emitting element 110 of Embodiment 2 will be described. 8 and 9 are explanatory views showing a manufacturing process of the light emitting element 110 of the second embodiment. As shown in FIG. 8A, an AlN buffer layer (not shown) is first grown at about 400 ° C. on a substrate (sapphire substrate) 1 by metal organic chemical vapor deposition (MO-CVD). Thereafter, an undoped GaN layer 2 of about 2 μm, an n-GaN layer of about 2 μm, an n-type semiconductor layer 3 made of an n-AlGaInN cladding layer, a GaN / InGaN-MQW type active layer 4, a p-AlGaInN layer, An LED structure in which a p-type semiconductor layer 5 including a p-GaN layer of about 0.3 μm and a p-InGaN layer as a contact layer is formed in this order is generated. While irradiating the substrate 1 taken out from the MO-CVD apparatus with ultraviolet rays, the substrate 1 is heated to about 400 ° C. to activate the p-type semiconductor layer 5.

  As shown in FIG. 8B, by photolithography and dry etching, a portion where the outer peripheral portion of the light emitting element 110, the bonding electrode (n pad) 7 and the bonding electrode (p pad) 8 are arranged using the photoresist as a mask. Dry etching is performed with a chlorine-based gas until the surface of the substrate 1 is exposed.

  Next, as shown in FIG. 8C, the p-type semiconductor layer 5 and the active layer 4 are removed by dry etching and etching is performed until the n-type semiconductor layer 3 is exposed, and an ohmic electrode (n-ohmic electrode) 9 is formed. A region 31 to be provided is formed.

  Next, as shown in FIG. 8D, a current diffusion layer 6 is formed by depositing an ITO film, which is a conductive transparent film, on the surface of the p-type semiconductor layer 5 by vacuum deposition and sputtering to a thickness of about 200 nm.

Next, a SiO ₂ film is formed on the entire surface by plasma CVD, and as shown in FIG. 9E, a portion where the bonding electrodes 7 and 8 are provided, a portion where the current diffusion auxiliary wiring 12 is provided, using diluted hydrofluoric acid, The portion where the n-type ohmic electrode is provided and the SiO ₂ film at the element isolation portion (end portion of the substrate 1) are removed. In FIG. 9E and subsequent figures, a coating film (SiO 2) covering the side surface of the semiconductor layer formed by laminating the undoped GaN layer 2, the n-type semiconductor layer 3, the active layer 4, the p-type semiconductor layer 5, and the like. Only _two films 11 are shown, and the other SiO ₂ films are omitted.

  Next, as shown in FIG. 9F, a V / Al / V / Au film is formed by vacuum deposition and patterned by a lift-off method. Thus, the ohmic electrode 9 is formed on the surface of the n-type semiconductor layer 5 and the current diffusion auxiliary wiring 12 is formed on the surface of the current diffusion layer 6. Thereafter, the ohmic electrode 9, the current diffusion auxiliary wiring 12, and the ITO film are simultaneously annealed by heating to about 500 ° C. by RTA (Rapid Thermal Anneal) in an Ar atmosphere.

  The current diffusion auxiliary wiring 12 may be provided on the surface of the current diffusion layer 6, may be provided on the surface of the p-type semiconductor layer 5, or the surface of the p-type semiconductor layer 5 and the surface of the current diffusion layer 6. It may be configured to straddle both.

  Thereafter, as shown in FIG. 9 (g), in order to form bonding electrodes 7 and 8, after photolithography, an Ag—Pd—Cu alloy is formed by sputtering, and Ni / Au is formed by vacuum deposition, and then lift-off is performed. Perform patterning.

Next, an SiO ₂ film is formed on the entire surface by plasma CVD, and the upper surfaces of the bonding electrodes 7 and 8 and the SiO ₂ film on the element isolation portion (end portion of the substrate 1) are removed by diluted hydrofluoric acid. Only the coating film (SiO ₂ film) 11 covering the side surface of the semiconductor layer formed by laminating the undoped GaN layer 2, the n-type semiconductor layer 3, the active layer 4, the p-type semiconductor layer 5 and the like is shown. Other SiO ₂ films are omitted.

  Thereafter, element separation is performed by laser scribing to complete an LED wafer (semiconductor light emitting element).

  In the second embodiment, the bonding electrode 8 is extended to the current diffusion auxiliary wiring 12 and connected to the current diffusion auxiliary wiring 12 on the surface of the coating film 11. As a result, it is possible to physically separate the bonding electrode 8 from the portion where the current diffusion auxiliary wiring 12 is electrically connected, and the material of the current diffusion auxiliary wiring 12 and the material of the bonding electrode 8 can be separated. It becomes. For example, the material of the current diffusion auxiliary wiring 12 is a metal having a low contact resistance (for example, V / Al / V / Au), and the material of the bonding electrode 8 having a relatively large occupied area on the substrate 1 is high in optical reflectance. A metal (for example, Ag—Pd—Cu alloy in the lowermost layer) can be used, and the amount of light absorbed by the bonding electrode 8 can be reduced to improve the light extraction efficiency. In addition, since the bonding electrode 8 extends to the current diffusion auxiliary wiring 12 and is connected to the current diffusion auxiliary wiring 12, a process of forming a conductive film for connecting the current diffusion auxiliary wiring 12 and the bonding electrode 8 becomes unnecessary. The manufacturing process can be simplified.

  Since the light emitting element 110 has a configuration in which the bonding electrode 7 is provided on the surface of the substrate 1, the light entering the lower side of the bonding electrode 7 as in the case where the n-type semiconductor layer 3 is disposed on the lower side of the bonding electrode 7. The amount of light absorbed by the lower surface of the bonding electrode 7 is reduced, and the light extraction efficiency is improved. Further, since the bonding electrode 8 is also provided on the surface of the substrate 1, light absorbed by the lower surface of the bonding electrode 8 is reduced, and light extraction efficiency is improved.

Embodiment 3
10 is a plan view of the semiconductor light emitting device 120 according to the third embodiment, and FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. The same parts as those in the first and second embodiments are denoted by the same reference numerals and the description thereof is omitted.

  In the third embodiment, a bonding electrode (n pad) 7 having a circular shape in plan view is arranged at the substantially center of the peripheral portion of one side of the rectangular substrate 1, and a bonding electrode (p pad) 8 having a circular shape in plan view is provided. It is located at the corner of the substrate 1 at a position facing the bonding electrode (n pad) 7. The ohmic electrode 9 is arranged in an arc shape along the circumferential direction of the bonding electrode (n pad) 7.

  Since the light emitting element 120 has a configuration in which the bonding electrode 7 is provided on the surface of the substrate 1, the light entering the lower side of the bonding electrode 7 as in the case where the n-type semiconductor layer 3 is disposed below the bonding electrode 7. The amount of light absorbed by the lower surface of the bonding electrode 7 is reduced, and the light extraction efficiency is improved. Further, since the bonding electrode 8 is also provided on the surface of the substrate 1, light absorbed by the lower surface of the bonding electrode 8 is reduced, and light extraction efficiency is improved.

Embodiment 4
FIG. 12 is a plan view of the semiconductor light emitting device 130 of the fourth embodiment. In the fourth embodiment, a bonding electrode (n pad) 7 having a circular shape in plan view is arranged at the substantially center of the peripheral portion of one side of the rectangular substrate 1, and a bonding electrode (p pad) 8 having a circular shape in plan view is provided. It is located at the corner of the substrate 1 at a position facing the bonding electrode (n pad) 7. The ohmic electrode 9 is arranged in an arc shape along the circumferential direction of the bonding electrode (n-pad) 7 and extends along the periphery of one side of the substrate 1. In addition, the same code | symbol is attached | subjected to the location similar to Embodiment 3, and description is abbreviate | omitted. A current diffusion auxiliary wiring 12 is formed on the surface of the current diffusion layer 6. The current diffusion auxiliary wiring 12 may be disposed so as to surround the entire current diffusion layer 6, and the shape, dimensions, and the like can be set as appropriate.

Embodiment 5
FIG. 13 is a plan view of the semiconductor light emitting device 140 of the fifth embodiment. In the fifth embodiment, bonding electrodes (n-pads) 7 and bonding electrodes (p-pads) 8 having a circular shape in plan view are arranged at diagonal corners of the rectangular substrate 1. The ohmic electrode 9 is arranged in an arc shape along the circumferential direction of the bonding electrode (n-pad) 7 and extends along the periphery of one side of the substrate 1. In addition, the same code | symbol is attached | subjected to the location similar to Embodiment 1-4, and description is abbreviate | omitted.

Embodiment 6
FIG. 14 is a longitudinal sectional view of an essential part of the semiconductor light emitting device 150 of the sixth embodiment. As shown in FIG. 14, the ohmic electrode 9 extends to the bonding electrode (n pad) 7 and is connected to the bonding electrode 7. As a result, the ohmic electrode 9 and the bonding electrode 7 that are electrically connected to the semiconductor layer can be physically separated, and the material of the ohmic electrode 9 and the material of the bonding electrode 7 can be separated. For example, the material of the ohmic electrode 9 can be a metal having a low contact resistance, and the material of the bonding electrode 7 having a relatively large occupation area on the substrate can be a metal having a high optical reflectance, thereby improving the light extraction efficiency. be able to. Further, since the ohmic electrode 9 extends to the bonding electrode 7 and is connected to the bonding electrode 7, a process for forming a conductive film for connecting the ohmic electrode 9 and the bonding electrode 7 is not required, and the manufacturing process is simplified. be able to. In addition, the same code | symbol is attached | subjected to the location similar to the above-mentioned embodiment, and description is abbreviate | omitted.

Embodiment 7
FIG. 15 is a longitudinal sectional view of an essential part of the semiconductor light emitting device 160 of the seventh embodiment. As shown in FIG. 15, the bonding electrode (n pad) 7 is extended to the surface of the n-type semiconductor layer 3 exposed by removing the p-type semiconductor layer 5 and the active layer 4 to form the n-type semiconductor layer 4. Connected directly. The bonding electrode 7 also serves as an n-type bonding electrode. This eliminates the need for an ohmic electrode forming step for electrical connection with the n-type semiconductor layer 3 and a conductive film forming step for connecting the ohmic electrode and the bonding electrode 7, thereby further simplifying the manufacturing process. Can do. In addition, the same code | symbol is attached | subjected to the location similar to the above-mentioned embodiment, and description is abbreviate | omitted.

Embodiment 8
FIG. 16 is a longitudinal sectional view of a main part of a semiconductor light emitting device 170 according to the eighth embodiment. As shown in FIG. 16, the ohmic electrode 9 and the bonding electrode (n pad) 7 are connected by a conductive film 13. As a result, the ohmic electrode 9 and the bonding electrode 7 that are electrically connected to the semiconductor layer can be physically separated, and the material of the ohmic electrode 9 and the material of the bonding electrode 7 can be separated. For example, the material of the ohmic electrode 9 can be a metal with a low contact resistance, and the material of the bonding electrode 7 having a relatively large occupied area on the substrate can be a metal with a high optical reflectance, further improving the light extraction efficiency. Can be made. Alternatively, the material of the bonding electrode 7 may be a metal having excellent mechanical strength (for example, Ti / Au, Ni / Au, etc.).

Embodiment 9
FIG. 17 is a longitudinal sectional view of a main part of the semiconductor light emitting device 180 of the ninth embodiment. As shown in FIG. 17, an undoped GaN layer 2 is formed on the surface of the substrate 1. The bonding electrode 7 is provided on the surface of the undoped GaN layer 2 exposed by removing the p-type semiconductor layer 5, the active layer 4 and the n-type semiconductor layer 3. This makes it possible to reduce the thickness of the entire lower semiconductor layer on the bonding electrode 7 as compared with the conventional case where the bonding electrode is formed on the upper side of the undoped GaN layer 2 and the n-type semiconductor layer 3. The light that enters the lower side of the bonding electrode 7 can be reduced, the light absorbed by the lower surface of the bonding electrode 7 can be reduced, and the light extraction efficiency can be improved.

Embodiment 10
FIG. 18 is a longitudinal sectional view of an essential part of the semiconductor light emitting device 190 of the tenth embodiment. As shown in FIG. 18, the current diffusion auxiliary wiring 12 is formed so as to straddle both the surface of the current diffusion layer 6 and the surface of the p-type semiconductor layer 5. The bonding electrode 8 extends to the current diffusion auxiliary wiring 12 on the surface of the coating film 11 and is connected to the current diffusion auxiliary wiring 12. Thereby, the bonding electrode 8 and the current diffusion auxiliary wiring 12 are electrically connected.

  In this case, a process of forming a conductive film for connecting the current diffusion auxiliary wiring 12 and the bonding electrode 8 becomes unnecessary, and the manufacturing process can be simplified.

Embodiment 11
FIG. 19 is a longitudinal sectional view of a main part of the semiconductor light emitting device 200 of the eleventh embodiment. As shown in FIG. 19, the current diffusion auxiliary wiring 12 is extended to the bonding electrode 8 on the surface of the coating film 11 and connected to the bonding electrode 8. This eliminates the need for a conductive film forming step for connecting the current diffusion auxiliary wiring 12 and the bonding electrode 8, thereby simplifying the manufacturing process.

Embodiment 12
FIG. 20 is a longitudinal sectional view of main parts of the semiconductor light emitting device 210 of the twelfth embodiment. As shown in FIG. 20, the current diffusion layer 6 is formed on the surface of the p-type semiconductor layer 5, and the coating film 11 covering the outer peripheral side surface of the semiconductor layer is formed. A conductive film 14 for connecting the current diffusion layer 6 and the bonding electrode (p pad) 8 is formed on the surface of the coating film 11. As a result, the conductive film 14 and the bonding electrode 8 that are electrically connected to the current diffusion layer 6 can be physically separated, and the material of the conductive film 14 and the material of the bonding electrode 8 can be separated. Become. For example, the material of the conductive film 14 can be a metal having a low contact resistance with the current diffusion layer 6, and the material of the bonding electrode 8 having a relatively large occupation area on the substrate 1 can be a metal having a high optical reflectance. The light extraction efficiency can be further improved. Alternatively, the material of the bonding electrode 8 may be a metal having excellent mechanical strength (for example, Ti / Au, Ni / Au, etc.).

Embodiment 13
FIG. 21 is a longitudinal sectional view of an essential part of the semiconductor light emitting device 220 of the thirteenth embodiment. As shown in FIG. 21, the current diffusion layer 6 is formed on the surface of the p-type semiconductor layer 5 and the current diffusion auxiliary wiring 12 is in contact with both the surface of the current diffusion layer 6 and the surface of the p-type semiconductor layer 5. Is formed. Moreover, the coating film 11 which coat | covers the outer peripheral side surface of a semiconductor layer is formed. A conductive film 14 for connecting the current diffusion auxiliary wiring 12 and the bonding electrode (p pad) 8 is formed on the surface of the coating film 11. Thereby, the current diffusion auxiliary wiring 12 and the bonding electrode 8 can be physically separated, and the material of the current diffusion auxiliary wiring 12 and the material of the bonding electrode 8 can be separated. For example, the material of the current diffusion auxiliary wiring 12 is a metal having a low contact resistance with the current diffusion layer 6, and the material of the bonding electrode 8 having a relatively large occupied area on the substrate 1 is a metal having a high optical reflectance. And the light extraction efficiency can be further improved. Alternatively, the material of the bonding electrode 8 may be a metal having excellent mechanical strength (for example, Ti / Au, Ni / Au, etc.).

  As described above, in the present invention, the GaN-based semiconductor layer under the bonding electrode (n pad, p pad) is thinned or completely removed, so that it is absorbed by the lower surface of the bonding electrode. The emitted light is reduced, light is emitted from the side surface of the light emitting element, and the light reflected by the side surface is emitted from the upper surface of the light emitting element or any one of the side surfaces while being subjected to multiple reflection in the light emitting element. For this reason, the light extraction efficiency can be improved as compared with the prior art.

  In addition, the bonding electrode (n pad) can be separated from the ohmic electrode for electrical bonding with the n-type semiconductor layer and locally (physical), and the bonding electrode (p pad) can be separated from the p-type semiconductor layer or current diffusion. It can be separated from the current spreading auxiliary wiring for electrical connection with the layer in a location (physical). For this reason, different materials can be used for the ohmic electrode or the current diffusion auxiliary wiring and the lower surface of the bonding electrode, and it becomes easy to select the optimum material for the function of each part. For example, in the conventional configuration in which the bonding electrode (n-pad) is provided on the exposed portion of the n-type semiconductor layer, since the ohmic contact with the semiconductor layer is performed on the lower surface of the bonding electrode, the contact resistance is low and the reflectance However, in the present invention, a material that is optimal for the functions of the bonding electrode and the ohmic electrode may be selected. That is, V / Al / V / Au or the like having a low contact resistance is used for the ohmic electrode or the like, and Ag, Al, Au, or Pd having excellent light reflectivity is provided at least on the lower side or the lowermost layer of the bonding electrode, or any one of them. By using an alloy composed mainly of one, light absorbed by the lower surface of the bonding electrode is reduced, and the light extraction efficiency can be further improved.

  The light emitting device (LED package) can be incorporated into the semiconductor light emitting element (for example, LED chip) package described in each of the above embodiments, and can be incorporated into an illumination device or a display device using the light emitting device as a light source. Accordingly, it is possible to provide a lighting device or a display device with favorable light emission efficiency.

  In the above-described embodiment, the ohmic electrode 9 and the conductive film 14 can be made of the same metal film. Thereby, the ohmic electrode 9 and the conductive film 14 can be formed at the same time, and the manufacturing process can be further simplified.

  In the above-described embodiment, in the case of the p-pad, the GaN-based semiconductor grown on the sapphire substrate has a higher carrier concentration in the background even when undoped than the other semiconductors. It is desirable to etch. In addition, since the undoped layer also has slight conductivity, an insulating film may be provided between the bonding electrode and the undoped layer in order to ensure electrical insulation.

  In the manufacturing process of the semiconductor light emitting device of the present invention described above, when the step of etching the periphery of the light emitting device to the sapphire substrate is already included for separating the light emitting device, the bonding electrode disposed around the substrate is patterned. The light-emitting device of the present invention can be manufactured with only slight changes without adding other changes. For this reason, the light emitting element of this invention can be manufactured, without increasing manufacturing cost.

  In the above-described embodiment, the case where both the p pad and the n pad are formed on the substrate surface has been described. However, only the n pad or only the p pad may be formed on the substrate surface. In addition, when the semiconductor layer is etched up to the substrate, light is emitted from the side surface of the step (side surface of the semiconductor layer). In order to extract the light above the light emitting element, the side surface of the bonding electrode is inclined in a tapered shape. Thus, the light emitted from the side surface of the semiconductor layer can be reflected upward.

  In the above-described embodiment, the position of the bonding electrode (p pad and n pad) in plan view is an example, and is not limited to these. By disposing the bonding electrode at the periphery of the substrate or at the corner of the substrate, the area of the bonding electrode and the portion that does not contribute to light emission around the bonding electrode can be reduced as much as possible, and the light emission efficiency per area of the light emitting element can be improved. it can.

1 is a plan view of a semiconductor light emitting device according to the present invention. It is the II-II sectional view taken on the line of FIG. It is a schematic diagram which shows the mode of the light radiate | emitted from a semiconductor layer. It is explanatory drawing which shows the manufacturing process of a light emitting element. It is explanatory drawing which shows the manufacturing process of a light emitting element. FIG. 6 is a plan view of a semiconductor light emitting element according to a second embodiment. It is the VII-VII sectional view taken on the line of FIG. 11 is an explanatory diagram showing a manufacturing process of the light-emitting element of Embodiment 2. FIG. 11 is an explanatory diagram showing a manufacturing process of the light-emitting element of Embodiment 2. FIG. FIG. 6 is a plan view of a semiconductor light emitting element according to a third embodiment. It is the XI-XI sectional view taken on the line of FIG. FIG. 6 is a plan view of a semiconductor light emitting element in a fourth embodiment. FIG. 10 is a plan view of a semiconductor light emitting element in a fifth embodiment. FIG. 10 is a longitudinal sectional view of a main part of a semiconductor light emitting element in a sixth embodiment. FIG. 10 is a longitudinal sectional view of a main part of a semiconductor light emitting element according to a seventh embodiment. FIG. 10 is a longitudinal sectional view of a main part of a semiconductor light emitting element according to an eighth embodiment. FIG. 22 is a longitudinal sectional view of main parts of a semiconductor light emitting element according to a ninth embodiment. FIG. 44 is a longitudinal sectional view of a main part of a semiconductor light emitting element according to the tenth embodiment. FIG. 38 is a longitudinal sectional view of a main part of a semiconductor light emitting element according to an eleventh embodiment. FIG. 34 is a longitudinal sectional view of a main part of a semiconductor light emitting element according to a twelfth embodiment. FIG. 34 is a longitudinal sectional view of a main part of a semiconductor light emitting element according to a thirteenth embodiment.

Explanation of symbols

1 substrate 2 undoped GaN layer 3 n-type semiconductor layer 4 active layer 5 p-type semiconductor layer 6 current diffusion layer 7 bonding electrode (n-pad)
8 Bonding electrode (p-pad)
9 Ohmic electrode 10, 12 Current diffusion auxiliary wiring 11 Coating film 13, 14 Conductive film
30 Semiconductor layer

Claims (18)

In a semiconductor light emitting device in which a semiconductor layer in which an n-type layer, an active layer, and a p-type layer are stacked in this order is formed on a part of a substrate surface.
The refractive index of the semiconductor layer is higher than the refractive index of the substrate,
A semiconductor light-emitting element, wherein at least one of an n-type layer and a p-type layer bonding electrode is provided on a substrate surface portion from which the semiconductor layer has been removed. An undoped semiconductor layer is formed on the substrate surface including the lower side of the n-type layer;
The bonding electrode is
The semiconductor light emitting element according to claim 1, wherein the semiconductor light emitting element is provided on a surface of the undoped semiconductor layer. An n-type layer junction electrode formed on the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer;
The semiconductor light-emitting device according to claim 1, further comprising: a conductive film connecting the n-type layer bonding electrode and the n-type layer bonding electrode. An n-type layer junction electrode formed on the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer;
The n-type layer junction electrode is
3. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device extends to the bonding electrode for the n-type layer and is connected to the bonding electrode. An n-type layer junction electrode formed on the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer;
The bonding electrode for the n-type layer is
3. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device extends to the n-type layer junction electrode and is connected to the n-type layer junction electrode. The bonding electrode for the n-type layer extends to the surface of the n-type layer exposed by removing a part of the p-type layer and the active layer, and is directly connected to the n-type layer;
The semiconductor light emitting element according to claim 1, wherein the bonding electrode for the n-type layer also serves as an n-type bonding electrode. A current diffusion layer is formed on the surface of the p-type layer;
The bonding electrode for the p-type layer is
At least the p-type layer, the active layer, and the n-type layer are removed and provided on the undoped layer or the substrate surface exposed,
A coating film covering an outer peripheral side surface exposed by etching of the semiconductor layer;
The semiconductor light emitting device according to claim 1, further comprising: a conductive film connecting the current diffusion layer and the p-type layer bonding electrode to a surface of the coating film. A current diffusion layer is formed on the surface of the p-type layer;
The bonding electrode for the p-type layer is
At least the p-type layer, the active layer, and the n-type layer are removed and provided on the undoped layer or the substrate surface exposed,
A current spreading auxiliary wiring connected to the current spreading layer;
A coating film covering an outer peripheral side surface exposed by etching of the semiconductor layer;
3. The semiconductor light emitting device according to claim 1, further comprising: a conductive film connecting the current diffusion auxiliary wiring and the p-type layer bonding electrode on a surface of the coating film.   9. The semiconductor light emitting element according to claim 7, wherein the conductive film and the n-type layer junction electrode are metal films made of the same material. A current diffusion layer is formed on the surface of the p-type layer;
A coating film covering the outer peripheral side surface exposed by etching of the semiconductor layer;
The bonding electrode for the p-type layer is
8. The semiconductor light emitting device according to claim 7, wherein the surface of the coating film is extended to the current diffusion layer and connected to the current diffusion layer. A current diffusion layer is formed on the surface of the p-type layer;
Current spreading auxiliary wiring connected to the current spreading layer;
A coating film covering the outer peripheral side surface exposed by etching of the semiconductor layer,
The bonding electrode for the p-type layer is
9. The semiconductor light emitting device according to claim 8, wherein the surface of the coating film is extended to the current diffusion auxiliary wiring and connected to the current diffusion auxiliary wiring. A current diffusion layer is formed on the surface of the p-type layer;
Current spreading auxiliary wiring connected to the current spreading layer;
A coating film covering the outer peripheral side surface exposed by etching of the semiconductor layer,
The current spreading auxiliary wiring is
9. The semiconductor light emitting device according to claim 8, wherein the surface of the coating film extends to the bonding electrode for the p-type layer and is connected to the bonding electrode. The bonding electrode is
13. The semiconductor light emitting element according to claim 1, comprising a metal film of Ag, Al, Au, Pd, or an alloy mainly composed of any one thereof.   The semiconductor light emitting element according to claim 13, wherein the metal film has a thickness of 100 nm or more.   The semiconductor light emitting element according to claim 13 or 14, wherein a distance between the lowermost surface of the metal film and the surface of the substrate is 50 nm or less.   A light-emitting device comprising: the semiconductor light-emitting element according to claim 1; and a housing portion that houses the semiconductor light-emitting element.   An illumination device comprising the light-emitting device according to claim 16.   A display device comprising the light-emitting device according to claim 16.

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