JP7828190B2 - Semiconductor light emitting element and semiconductor light emitting device - Google Patents

Description

The present invention relates to semiconductor light-emitting elements and semiconductor light-emitting devices, particularly semiconductor light-emitting elements such as light-emitting diodes (LEDs) and semiconductor light-emitting devices having such semiconductor light-emitting elements.

In recent years, semiconductor light-emitting elements such as light-emitting diodes (LEDs) have been arranged and used within multiple devices in order to achieve higher output and light distribution control.

For example, adaptive driving beam (ADB) headlamps are known for their variable light distribution, controlling light distribution according to the driving environment. Other well-known LED packages include high-output LED packages for lighting and LED packages for information and communication devices with high-density LED arrangements.

However, there is an increasing demand for high-output semiconductor light-emitting elements that have high luminous efficiency and can emit uniform light. There is also a demand for semiconductor light-emitting devices that are less susceptible to element damage, while preventing performance degradation of the light-emitting element and incorporating additional functions such as protective elements.

For example, Patent Document 1 describes a light-emitting device that has multiple holes that penetrate the active layer and expose the first semiconductor layer, and first and second solder pads formed in areas other than the locations of the multiple holes, thereby equalizing the light field distribution and reducing the forward voltage of the light-emitting device.

Patent Document 2 also describes a light-emitting element structure that includes multiple semiconductor stacks, each stack including multiple grooves and a flat base with an upper surface, and in which an electrode is provided on a first semiconductor layer exposed from the bottom of the multiple grooves.

Patent document 3 also discloses a semiconductor light-emitting device that has a mesa structure and prevents the current flowing between the p-electrode and n-electrode from concentrating in the area near the mesa edge, thereby suppressing a decrease in light-emitting efficiency.

Furthermore, Non-Patent Document 1 discloses lateral current crowding in GaN-based LEDs grown on sapphire.

JP 2017-92477 A JP 2014-150188 A Japanese Patent Application Laid-Open No. 2017-28032

“Current crowding in GaN/InGaN light emitting diodes on insulating substrates”, X. Guo et al., J. Appl. Phys.,Vol. 90, No.8, 15 October 2001

The present invention was made in consideration of the above points, and aims to provide a semiconductor light-emitting element and semiconductor light-emitting device that achieve uniform current injection and light emission, and have high light-emitting efficiency.

A semiconductor light emitting device according to one embodiment of the present invention comprises:
an insulating or semi-insulating substrate;
a light-emitting functional layer in which a first semiconductor layer of a first polarity, a light-emitting layer, and a second semiconductor layer of a second polarity are sequentially stacked on the substrate;
a first electrode layer provided on the first semiconductor layer of the light-emitting functional layer;
a second electrode layer provided on the second semiconductor layer of the light-emitting functional layer;
a first insulating layer that covers the light-emitting functional layer and exposes a portion of the first electrode layer and the second electrode layer;
a covering metal layer that covers the light-emitting functional layer and is connected to the first electrode layer;
a second insulating layer covering the covering metal layer;
a first pad electrode connected to the first electrode layer and covering the light emitting function layer and the first and second insulating layers;
a second pad electrode connected to the covering electrode layer and covering the light-emitting function layer and the first and second insulating layers,
the light-emitting functional layer has a pair of sides facing each other and a pair of connection portions at which the first semiconductor layer is exposed along the pair of sides;
The first electrode layer is in Schottky contact with the pair of connection portions of the first semiconductor layer.

A semiconductor light emitting device according to another embodiment of the present invention includes:
a light emitting element assembly including the semiconductor light emitting element and a light guiding member bonded to the semiconductor light emitting element by an adhesive layer;
a light-shielding layer made of an inorganic material that is a light reflector covering a side surface of the light-emitting element assembly;
It has the following characteristics.

1 is a top view schematically showing a semiconductor light emitting element 10 according to a first embodiment of the present invention as viewed from above. FIG. 1B is a cross-sectional view schematically showing a cross section taken along line AA in FIG. 1A. FIG. 2 is a top view schematically showing the top surface of the semiconductor light emitting element 10. 2B is a partially enlarged cross-sectional view showing a cross section of an end portion of the semiconductor light-emitting element 10 taken along line BB in FIG. 2A. 2B is a partially enlarged cross-sectional view showing a cross section of the end portion of the semiconductor light-emitting element 10 taken along line CC in FIG. 2A. 2B is a partially enlarged cross-sectional view showing a cross section of the end portion of the semiconductor light-emitting element 10 taken along line DD in FIG. 2A. 2B is a partially enlarged cross-sectional view showing a cross section of the end portion of the semiconductor light-emitting element 10 taken along line EE in FIG. 2A. FIG. 2 is a top view schematically showing a Schottky contact portion and an ohmic contact portion. 3A to 3C are cross-sectional views showing steps of a method for manufacturing the semiconductor light-emitting element 10. 3A to 3C are cross-sectional views showing steps of a method for manufacturing the semiconductor light-emitting element 10. 3A to 3C are cross-sectional views showing steps of a method for manufacturing the semiconductor light-emitting element 10. 1 is a perspective view showing a method of mounting the semiconductor light emitting element 10 on a circuit board. FIG. 10 is a perspective view for explaining the discharge of flux that has evaporated during reflow. FIG. 5B is a cross-sectional view taken along line DD in FIG. 5A. FIG. 1 is a top view showing a semiconductor light emitting device 10A which is a modified example of the first embodiment of the present invention. FIG. 4 is a cross-sectional view schematically showing a cross section of a semiconductor light-emitting device 50 according to a second embodiment of the present invention.

The following describes preferred embodiments of the present invention, which may be modified and combined as appropriate. Furthermore, in the following description and accompanying drawings, substantially identical or equivalent parts are designated by the same reference numerals.

[First embodiment]
(1) Structure of the Semiconductor Light Emitting Device FIG. 1A is a top view schematically showing a semiconductor light emitting device 10 according to a first embodiment of the present invention as viewed from above (also referred to as a top view). For ease of explanation and understanding, the internal structure of electrodes and the like is also shown. FIG. 1B is a cross-sectional view schematically showing a cross section taken along line A-A in FIG. 1A. The structure of the semiconductor light emitting device 10 will be described in detail below.

As shown in FIG. 1A, the semiconductor light-emitting element 10 has a rectangular prism shape with four mutually perpendicular side surfaces (side surfaces along the x and y directions). The semiconductor light-emitting element 10 also has multiple light-emitting functional portions 15M, which are light-emitting regions separated from each other by grooves 15G.

In this specification, the multiple light-emitting functional sections 15M and the separation grooves are collectively referred to as the light-emitting functional layer 15. The multiple light-emitting functional sections 15M extend in a direction (y direction) perpendicular to a pair of opposing sides SF1 and SF3 of the light-emitting functional layer 15. In other words, the multiple light-emitting functional sections 15M extend parallel to a pair of sides SF2 and SF4.

As shown in FIG. 1B, the semiconductor light-emitting element 10 has a light-transmitting, insulating substrate 11. Substrate 11 can be made of sapphire, AlN (aluminum nitride), or the like.

Alternatively, substrate 11 may be formed from an insulating substrate, semi-insulating, or highly resistive material. Note that in this specification, a semi-insulating substrate includes a highly resistive semiconductor substrate such as GaN. Specifically, it refers to a material that exhibits a high resistivity of 1 MΩ/□ or more.

On the substrate 11, an n-type semiconductor layer 12 (first semiconductor layer), a light-emitting layer 13, and a p-type semiconductor layer 14 (second semiconductor layer) are stacked in this order to form a mesa-shaped light-emitting functional section 15M.

The mesa-shaped light-emitting function section 15M is made of a GaN-based semiconductor layer and can be formed, for example, by MOCVD (metal organic chemical vapor deposition). Note that the crystal growth method is not limited to MOCVD; other methods such as MBE (molecular beam epitaxy) can also be used.

The n-type semiconductor layer 12 is exposed at the bottom of the grooves 15G between the light-emitting functional sections 15M. An n-electrode 21A is formed on each of the n-type semiconductor layers 12 exposed at the bottom of the multiple grooves 15G. As shown in FIG. 1A, the multiple n-electrodes 21A extend along the light-emitting functional section 15M and are formed in the shape of strips parallel to the light-emitting functional section 15M.

The n-electrode 21A is formed as an ohmic electrode in which Ti and Al are formed in that order on the n-type semiconductor layer 12. It should be noted that the n-electrode 21A is not limited to a Ti/Al layer, and may be formed from a material that forms ohmic contact with the n-type semiconductor layer 12, such as Ti/Rh or Ti/Au.

Auxiliary wiring 21B is formed on and along the n-electrode 21A. Auxiliary wiring 21B is formed as wiring made of Ni, Au, Ti, and Pt, in that order. The n-electrode 21A and auxiliary wiring 21B are collectively referred to as the first electrode layer 22.

The auxiliary wiring 21B is made of a material that forms a Schottky barrier when it comes into contact with the n-type semiconductor layer 12. The auxiliary wiring 21B is not limited to a Ni/Au/Ti/Pt layer. For example, Pd or Rh can be used instead of Pt. It is also possible to provide a Ni, Ti, or W layer on top of Pt.

A strip-shaped p-electrode 23 (second electrode layer) consisting of an ohmic electrode, a reflective layer, and a protective layer is formed on the p-type semiconductor layer 14 above the mesa of the light-emitting functional section 15M. Specifically, an ITO (indium tin oxide) film is formed as the ohmic electrode, and Ni/Ag/Ti/Au layers are formed as the reflective layer and protective layer.

The sidewalls and upper surfaces of the mesa-shaped light-emitting functional portion 15M and the p-electrode 23 are covered and protected by a first insulating film 25 made of SiO _2. On the first insulating film 25, a covering metal layer 26 is formed.

The covering metal layer 26 is a light-reflective n-wiring layer that is formed to cover the sidewalls and top surface of the light-emitting function section 15M via the first insulating film 25. The covering metal layer 26 is also electrically connected to the auxiliary wiring 21B and the n-electrode 21A through openings in the first insulating film 25.

Specific examples of the coating metal layer 26 include, but are not limited to, Ni/Al/Ti/Pt layers or Ti/Al/Ti/Pt layers. For example, Pd or Rh can be used instead of Pt. It is also possible to provide a Ti, Ni, or W layer on top of Pt.

The metal coating layer 26 is covered and insulated by a second insulating film 27 made of SiO ₂ formed on the metal coating layer 26 .

As shown in FIG. 1A, two pad electrodes, i.e., a first pad electrode 28A and a second pad electrode 28B, spaced apart in the extension direction (y direction) of the light-emitting function section 15M are formed on the second insulating film 27. Specifically, the first pad electrode 28A is formed on one side (referred to as the first region RC1) of a center line CL that is perpendicular to the extension direction of the light-emitting function section 15M, and the second pad electrode 28B is formed on the other side (referred to as the second region RC2) spaced apart from the first pad electrode 28A.

The first pad electrode 28A and the second pad electrode 28B are used as the anode electrode and cathode electrode, respectively, when mounting the semiconductor light emitting element 10 on a circuit board or the like.

As shown in FIG. 1B, the first pad electrode 28A (anode electrode) is electrically connected to the p-electrode 23 through the opening in the second insulating film 27 and the first insulating film 25, forming a p-electrode connection portion 23C. Also, as shown in FIG. 1A, the opening in the first insulating film 25 is provided in the region on one side of the center line CL.

The second pad electrode 28B (cathode electrode) is electrically connected to the first electrode 22, consisting of the auxiliary wiring 21B and the n-electrode 21A, via the coating metal layer 26 exposed in the opening of the second insulating film 27 at the bottom of the groove 15G, forming an n-electrode connection portion 22C (first electrode connection portion). As shown in FIG. 1A, the opening of the second insulating film 27 is provided in the region on the other side of the center line CL.

The first pad electrode 28A and the second pad electrode 28B are preferably spaced apart at a constant linear distance DG perpendicular to the extension direction (y direction) of the light-emitting function portion 15M. Note that, although this embodiment shows a case in which the first pad electrode 28A and the second pad electrode 28B are rectangular in top view, this is not limiting.

A portion of the light emitted from the light-emitting functional unit 15M is emitted from the light-emitting surface 11E of the translucent substrate 11 as direct light Ld, and a portion is emitted from the light-emitting surface 11E as reflected light Lr by the p-electrode 23.

(2) Connection Configuration Between First Semiconductor and Electrode Next, the electrical connection between the covering metal layer 26 at the end of the semiconductor light emitting element 10 and the n-electrode 21A and auxiliary wiring 21B will be described with reference to Figures 2A and 2B to 2E. Figure 2A is a top view schematically showing the top surface of the semiconductor light emitting element 10. For ease of explanation and understanding, the internal structure of the electrodes, etc. is also shown.

Furthermore, Figures 2B to 2E are partially enlarged cross-sectional views showing the end of the semiconductor light-emitting element 10 along lines BB, CC, DD, and EE in Figure 2A, respectively.

Figure 2B shows a cross section of the edge (first region RC1) of the semiconductor light emitting element 10 along line B-B, which intersects with the first pad electrode 28A. At the edge along side SF4 of the semiconductor light emitting element 10, the n-electrode 21A is formed so as to cover the end of the n-type semiconductor layer 12, i.e., to cover the side and top surfaces of the end.

This structure prevents current from concentrating at the end of the n-type semiconductor layer 12, which would cause deterioration of the light-emitting functional section 15M and reduce light output.

The covering metal layer 26, which is an n-type wiring layer, is formed so as to contact the auxiliary wiring 21B and cover the sides of the light-emitting function section 15M. This structure not only protects the light-emitting function section 15M, but also functions to increase light output by reflecting light emitted from the light-emitting function section 15M toward the light-emitting surface 11E of the substrate 11.

Furthermore, as shown in FIG. 2C, the cross section of the edge portion (second region RC2) of the semiconductor light emitting element 10 taken along a line intersecting the second pad electrode 28B also has a structure similar to that shown in FIG. 2B. That is, at the edge portion along side SF4 of the semiconductor light emitting element 10, the n-electrode 21A is formed so as to cover the end portion of the n-type semiconductor layer 12. Furthermore, the n-electrode 21A is in ohmic contact with the n-type semiconductor layer 12.

As shown in FIG. 3, a connection portion is provided along the side SF4 of the semiconductor light-emitting element 10 that is aligned with the extension direction of the light-emitting function portion 15M, where the p-type semiconductor layer 14 and the light-emitting layer 13 are removed to expose the n-type semiconductor layer 12, and the n-electrode 21A is connected to this connection portion to form an ohmic connection portion OC1.

This structure suppresses current concentration along the entire edge along side SF4 in the extension direction of the light-emitting function unit 15M (hereinafter simply referred to as side SF4, and the same applies below), and prevents deterioration of the light-emitting function unit 15M.

The above has described side SF4 of the semiconductor light-emitting element 10, but the edge along side SF2 opposite side SF4 also has a similar structure. That is, along side SF2 of the semiconductor light-emitting element 10, the p-type semiconductor layer 14 and light-emitting layer 13 have been removed to provide a connection portion where the n-type semiconductor layer 12 is exposed, and an n-electrode 21A is connected to this connection portion to form an ohmic connection portion OC2. Furthermore, the n-electrode 21A is formed so as to cover the end of the n-type semiconductor layer 12.

Figure 2D shows a cross section of side SF1 (x direction) of the semiconductor light emitting element 10, which is perpendicular to the extension direction (y direction) of the light emitting function portion 15M. On side SF1, the n-electrode 21A is not provided on the n-type semiconductor layer 12, and the auxiliary wiring 21B is in direct contact with the exposed n-type semiconductor layer 12.

As described above, the auxiliary wiring 21B is made of a material that forms a Schottky barrier when in contact with the n-type semiconductor layer 12, and the auxiliary wiring 21B forms a Schottky contact with the n-type semiconductor layer 12. The auxiliary wiring 21B is also electrically connected to the overlying metal layer 26.

That is, as shown in FIG. 3, a Schottky contact connection (Schottky connection) SC1 is formed along side SF1 of semiconductor light emitting element 10. Schottky connection SC1 prevents current from concentrating at the end of light emitting function unit 15M, which would deteriorate the crystal layer of light emitting function unit 15M and reduce light output.

As shown in Figure 2E, the same is true for side SF3 opposite side SF1. Therefore, as shown in Figure 3, a Schottky junction SC2 extending along side SF3 is formed on side SF3 of the semiconductor light emitting element 10. The Schottky junction SC2 prevents current from concentrating at the end of the light emitting function unit 15M, which could cause deterioration of the light emitting function unit 15M and a decrease in light output.

As explained above, the light-emitting functional layer 15, which includes multiple light-emitting functional sections 15M, has at least one pair of opposing sides, and a pair of connection sections along the pair of sides where the p-type semiconductor layer 14 and the light-emitting layer 13 have been removed to expose the n-type semiconductor layer 12 (first semiconductor layer).

A pair of opposing sides SF1, SF3 in a direction perpendicular to the extension direction of the light-emitting function section 15M has a pair of connection sections where the p-type semiconductor layer 14 and light-emitting layer 13 extending along the sides SF1, SF3 have been removed to expose the n-type semiconductor layer 12 (first semiconductor layer), and auxiliary wiring 21B is in Schottky contact with the n-type semiconductor layer 12 at these connection sections.

Furthermore, the other pair of opposing sides SF4, SF2 of the substrate 11 extend in a direction along the light-emitting functional section 15M and have a pair of connection portions where the p-type semiconductor layer 14 and light-emitting layer 13 extending along the sides SF4, SF2 have been removed to expose the n-type semiconductor layer 12 (first semiconductor layer), and the n-electrode 21A is in ohmic contact with the n-type semiconductor layer 12 (first semiconductor layer) at these connection portions.

(3) Manufacturing Method of Semiconductor Light Emitting Device The manufacturing method of the semiconductor light emitting device 10 will be described below with reference to the drawings. Figures 4A to 4C are cross-sectional views showing steps S1 to S9 of the manufacturing method. Note that Figures 4A to 4C schematically show cross sections taken along line A-A in Figure 1A. That is, the left side of the figure is a cross section of the first region RC1, and the right side is a cross section of the second region RC2.

(S1) Preparation of epitaxial wafer An epitaxial wafer 10E is prepared, in which an n-type semiconductor layer 12, a semiconductor light emitting layer 13, and a p-type semiconductor layer 14 are sequentially crystal-grown on a substrate 11. The layer consisting of the n-type semiconductor layer 12, the semiconductor light emitting layer 13, and the p-type semiconductor layer 14 functions as a light-emitting functional layer 15. Here, sapphire is used for the substrate 11, and GaN-based crystals are used for the semiconductor layers.

(S2) Dividing the Light-Emitting Region A resist mask covering the portion that will become the light-emitting region is formed on the epitaxial wafer 10E. Next, the semiconductor layer in the openings of the resist mask is etched by RIE (reactive ion etching) until the n-type semiconductor layer 12 is exposed. Using a similar method, the n-type semiconductor layer 12 at the edge of the semiconductor light-emitting element 10 is etched until the substrate 11 is exposed.

The light-emitting functional layer 15 is divided by the grooves 15G formed by etching, forming one or more mesa-shaped light-emitting functional portions 15M. The edges of the sides SF1 to SF4 that define the semiconductor light-emitting element 10 are also formed. The resist mask is then removed. Note that the final removal of the resist mask in each of the following steps will not be described here.

(S3) Formation of p-electrode A resist mask is formed with an opening in the area where the p-electrode will be formed, i.e., the top surface of the light-emitting function section 15M. Next, an ITO film 23A is formed by sputtering. Next, a Ni/Ag layer 23B is formed on the ITO film 23A by EB (electron beam) method. Subsequently, a Ti/Au layer 23C is formed by EB method.

This results in the formation of a reflective p-electrode 23 consisting of an ITO film 23A, which is a transparent conductive film, an Ni/Ag layer 23B, which is a light-reflecting film, and a Ti/Au layer 23C, which is a protective layer.

In addition, Pt, Pd, or Rh can be used instead of the Au layer in the Ti/Au layer 23C. A small amount of Ni, Ti, W, etc. can also be deposited on the top layer.

(S4) Formation of n-electrode A resist mask is formed with an opening at the bottom of the groove 15G where the n-electrode will be formed. Subsequently, a Ti/Al layer is formed by the EB method to form the n-electrode 21A. Note that Pt, Pd, or Rh can also be used instead of the Al layer.

(S5) Formation of auxiliary wiring A resist mask is formed with openings in the areas where the auxiliary wiring 21B other than the light-emitting function portion 15M will be formed. Subsequently, a Ni/Au layer is formed by the EB method. The part of this metal layer that contacts the n-type semiconductor layer 12 forms a Schottky junction.

Next, a Ti/Au layer is deposited on the Ni/Au layer using the EB method to form the auxiliary wiring 21B. Note that Pt, Pd, or Rh can also be used instead of the Au layer. A small amount of Ni, Ti, or W can also be deposited on the top layer.

(S6) Formation of First Insulating Film A _SiO2 film is formed by sputtering over the entire processed surface of the wafer that has undergone the above steps. Next, a resist mask is formed with openings in the areas that will become the n-electrode connection portion 22C and the p-electrode connection portion 23C. Subsequently, the _SiO2 layer film in the areas where the resist mask opens is removed using buffered hydrofluoric acid to form the first insulating film 25. At this time, the Au layer (or Pt, Pd, or Rh layer) of the p-electrode 23 and auxiliary wiring 21B functions as an etching stop layer.

(S7) Formation of Metallic Coating Layer A resist mask is formed with openings in the areas where the metallic coating layer is to be formed. Next, a Ni/Al/Ti/Pt layer is formed by EB to form the metallic coating layer 26. Ni, Ti, or W can also be formed on the top surface of the Pt layer. This improves the adhesion of the second insulating film 27.

(S8) Formation of second insulating film A resist mask is formed to cover the n-electrode connection portion 22C and the p-electrode connection portion 23C. Subsequently, a _SiO2 film is formed by sputtering. After that, the n-electrode connection portion 22C and the p-electrode connection portion 23C are exposed by lifting off the resist.

(S9) Formation of Pad Electrodes A resist mask is formed with openings corresponding to the shapes of the first pad electrode 28A and the second pad electrode 28B. Subsequently, a Ti/Au layer is formed by the EB method to form the first pad electrode 28A and the second pad electrode 28B.

The semiconductor light-emitting element 10 is manufactured through the above process. Note that the film formation method and materials for each layer can be modified as appropriate.

(4) Mounting on a Circuit Board Mounting of the semiconductor light emitting element 10 on a circuit board will be described below. Fig. 5A is a perspective view showing a method of mounting the semiconductor light emitting element 10 on a circuit board.

With the first pad electrode 28A (anode) and the second pad electrode 28B (cathode) facing downward, the semiconductor light emitting element 10 is bonded to the anode wiring 43A and the cathode wiring 43B of the circuit board using bonding members 41A and 41B.

More specifically, first, solder paste solder, which serves as the bonding material, is printed on the circuit board wiring. Next, the semiconductor light-emitting element 10 is mounted on the solder paste. Next, it is heated in a reflow furnace to bond it.

Figures 5B and 5C are a top perspective view and a cross-sectional view taken along line D-D in Figure 5A, respectively, to illustrate the discharge of volatilized flux during reflow.

The solder paste solder that forms the joining members 41A and 41B contains volatile flux, which volatilizes during reflow. At this time, as shown in Figure 5B, the slit between the first pad electrode 28A and the second pad electrode 28B serves as a gas exhaust path. When heated from the outside, the solder melts and progresses from the outside to the inside. Therefore, by providing an exhaust path that passes through the final melting point, it is possible to exhaust flux gas, making it possible to form joining members without voids. This enables mounting with high heat dissipation.

(5) Modification Example 1
Although the above description has been given of the case where the light-emitting functional layer 15 has a plurality of light-emitting functional portions 15M, the light-emitting functional layer 15 may be configured to have one light-emitting functional portion 15M.

That is, the light-emitting functional layer 15 may be configured to have a plateau shape with grooves or steps that expose the n-type semiconductor layer 12 (first semiconductor layer) along a pair of opposing sides (edges). In this case, the first electrode layer 22 can be configured to be in Schottky contact with the n-type semiconductor layer 12 (first semiconductor layer) exposed along the pair of sides.

(6) Modification Example 2
6 is a top view showing a semiconductor light emitting device 10A according to a modification of the first embodiment of the present invention, which includes insulating pads 29A and 29B in addition to a first pad electrode 28A and a second pad electrode 28B.

More specifically, the insulating pads 29A and 29B are provided between the first pad electrode 28A and the second pad electrode 28B, spaced apart by a distance DG from the first pad electrode 28A and the second pad electrode 28B. The insulating pads 29A and 29B are also arranged side by side in a direction perpendicular to the extension direction of the light-emitting function section 15M.

The insulating pads 29A, 29B are electrically insulated and spaced apart by a gap that passes through the final melting point (see Figure 5B). This allows for effective evacuation of volatile gases from the solder paste.

In addition, by joining the insulating pad to a heat dissipation means provided on the circuit board, the light-emitting element (light-emitting device) can be cooled without going through a submount or package substrate.

Furthermore, the first pad electrode 28A and the second pad electrode 28B are formed with their pad ends offset by a distance DP inward from the end of the light-emitting function portion 15M so as not to extend beyond the end 15E of the light-emitting function portion 15M. This structure prevents stress from being applied to the light-emitting function portion 15M during soldering. Note that even if insulating pads 29A and 29B are not provided, it is preferable to form the first pad electrode 28A and the second pad electrode 28B offset from the end 15E of the light-emitting function portion 15M.

Second Embodiment
7 is a cross-sectional view schematically illustrating a semiconductor light-emitting device 50 according to a second embodiment of the present invention. The semiconductor light-emitting device 50 is a light-emitting device that emits mixed color light, and includes the semiconductor light-emitting element 10 of the first embodiment and a light-guiding member 51. In the following, an example in which the light-guiding member 51 is a phosphor plate will be described.

More specifically, a phosphor plate 51 is adhered to the semiconductor light-emitting element 10 by an adhesive layer 48. The semiconductor light-emitting element 10 is a light-emitting element (LED) that emits blue light, and the phosphor plate 51 is made of, for example, YAG:Ce, and white mixed color light LM is emitted from the upper surface of the phosphor plate 51. The adhesive layer 48 is made of a translucent adhesive, for example, a translucent silicone resin.

The semiconductor light-emitting element 10 and the phosphor plate 51 have the same outer shape and size, e.g., a rectangular plate shape. In other words, the semiconductor light-emitting element 10 and the phosphor plate 51 share a common outer surface.

The semiconductor light-emitting element 10, adhesive layer 48, and phosphor plate 51 therefore constitute a light-emitting element assembly 53. The side surfaces of the light-emitting element assembly 53 are covered with a light-shielding layer 55, which is a coating that adheres closely to the side surfaces.

The light-shielding layer 55 may be any layer that blocks light from the semiconductor light-emitting element 10, adhesive layer 48, and phosphor plate 51. For example, an alumina layer formed by thermal spraying, a white resin layer, or a dielectric multilayer film layer formed by atomic layer deposition (ALD) can be used.

For example, the light-shielding layer 55 can be formed from a coating made of an inorganic material that is a light reflector. It is preferable that the light-shielding layer 55 be a ceramic binder (essentially a sintered body) formed by thermal spraying and containing white ceramic, or a silicate-based binder, which is an inorganic adhesive whose aggregate (main skeleton material) is alumina, zirconia, or other ceramic particles that bond with siloxane.

Note that the semiconductor light-emitting element 10 and the phosphor plate 51 do not need to be the same shape or size. It is preferable that the entire side surface of the light-emitting element assembly 53 is covered with a light-shielding layer 55. Furthermore, when multiple semiconductor light-emitting devices 50 are arranged in contact with each other on a circuit board or the like, it is preferable that they have flat side surfaces that can be tightly attached to each other.

Furthermore, the phosphors of the phosphor plate 51 are not limited to those mentioned above. For example, a green light-emitting device can be formed by using an LuAG:Ce phosphor plate, and a red light-emitting device can be formed by using an α-sialon phosphor plate. Furthermore, optical plates and light-guiding members such as lenses and diffractive optical elements can also be used instead of the phosphor plate 51.

The above describes in detail an embodiment of the present invention, but the semiconductor layer configuration, crystal system, materials, and other details are merely examples. Appropriate modifications can be made without departing from the scope of the present invention.

As explained in detail above, the present invention makes it possible to provide a semiconductor light-emitting element and a semiconductor light-emitting device that achieve uniform current injection and light emission, and have high light-emitting efficiency.

10, 10A: Semiconductor light-emitting element, 11: Substrate, 12: First semiconductor layer, 13: Light-emitting layer, 14: Second semiconductor layer, 15: Light-emitting functional layer, 15G: Groove, 15M: Light-emitting functional portion, 21A: n-electrode, 21B: Auxiliary wiring, 22: First electrode layer, 23: Second electrode layer (p-electrode), 25: First insulating film, 26: Covering metal layer, 27: Second insulating film, 28A: First pad electrode, 28B: Second pad electrode, 29A, 29B: Insulating pads, OC1, OC2: Ohmic contact, SC1, SC2: Schottky contact, 50: Semiconductor light-emitting device, 51: Light-guiding member, 53: Light-emitting element assembly, 55: Light-shielding layer

Claims (9)

an insulating or semi-insulating substrate;
a light-emitting functional layer in which a first semiconductor layer of a first polarity, a light-emitting layer, and a second semiconductor layer of a second polarity are sequentially stacked on the substrate;
a first electrode layer provided on the first semiconductor layer of the light-emitting functional layer;
a second electrode layer provided on the second semiconductor layer of the light-emitting functional layer;
a first insulating layer that covers the light-emitting functional layer and exposes a portion of the first electrode layer and the second electrode layer;
a covering metal layer that covers the light-emitting functional layer and is connected to the first electrode layer;
a second insulating layer covering the covering metal layer;
a first pad electrode connected to the second electrode layer and covering the light emitting function layer and the first and second insulating layers;
a second pad electrode connected to the covering metal layer and covering the light emitting function layer and the first and second insulating layers;
the light-emitting functional layer has a pair of sides facing each other and a pair of connection portions at which the first semiconductor layer is exposed along the pair of sides;
The first electrode layer is in Schottky contact with the pair of connection portions of the first semiconductor layer. the light-emitting functional layer has another pair of sides perpendicular to the pair of sides, and has another pair of connection portions along the other pair of sides at which the first semiconductor layer is exposed,
the first electrode layer is in ohmic contact with the other pair of connection portions of the first semiconductor layer;
The semiconductor light emitting device according to claim 1 . the light emitting functional layer has a plurality of mesa-shaped light emitting functional portions separated by grooves in which the first semiconductor layer is exposed and extending in a direction perpendicular to the pair of sides,
3. The semiconductor light-emitting element according to claim 1, wherein the first electrode layer has a first electrode piece extending parallel to the light-emitting function portion at the bottom of the groove, and the second electrode layer has a second electrode piece extending parallel to the light-emitting function portion on the top surface of the light-emitting function portion. A semiconductor light-emitting element according to any one of claims 1 to 3, wherein the first pad electrode and the second pad electrode are spaced apart at a constant interval in a direction perpendicular to the pair of sides. 5. The semiconductor light emitting element according to claim 3, wherein the first pad electrode and the second pad electrode are arranged such that pad ends are offset inward from ends of the plurality of light emitting function portions. A semiconductor light-emitting element according to any one of claims 1 to 5, further comprising an insulating pad disposed between the first pad electrode and the second pad electrode and spaced apart from the first pad electrode and the second pad electrode. The semiconductor light-emitting element described in any one of claims 1 to 6, wherein the second electrode layer has a transparent conductive film provided on the second semiconductor layer and a light-reflecting film provided on the transparent conductive film. a light-emitting element assembly including the semiconductor light-emitting element according to claim 1 and a light-guiding member bonded to the semiconductor light-emitting element by an adhesive layer;
a light-shielding layer made of an inorganic material that is a light reflector covering a side surface of the light-emitting element assembly;
A semiconductor light emitting device comprising: The semiconductor light-emitting device described in claim 8, wherein the light-shielding layer is a ceramic binder formed by thermal spraying, or a silicate-based binder, which is an inorganic adhesive having siloxane bonds and which uses ceramic particles as aggregate.