JP2005159035A - Light emitting diode and light emitting device - Google Patents

Abstract

A light-emitting diode and a light-emitting device that can be easily mounted and can improve light extraction efficiency.
A light emitting diode includes a substrate made of an n-type GaN compound semiconductor. The light emitting diode 3 includes an n-type cladding layer 7, an active layer 9, a p-type cladding layer 11, a p-type contact layer 13, and an anode electrode 15 that are sequentially formed on the main surface 5 a of the substrate 5. The cathode electrode 17 is formed on the side surface 5 c of the substrate 5. Thus, the light L1 generated in the active layer 9 can be emitted from the back surface 5b of the substrate 5 without being blocked by the cathode electrode 17. Therefore, according to the light emitting diode 3, the light extraction efficiency can be improved.
[Selection] Figure 1

Description

  The present invention relates to a light emitting diode and a light emitting device including the light emitting diode.

  In recent years, LEDs having relatively short wavelengths such as blue light emitting diodes (LEDs) and ultraviolet LEDs have been actively developed. As a conventional form of such an LED, for example, the light emitting device shown in FIGS. 16A to 16C can be cited. In the light emitting device 100a shown in FIG. 16A, the LED 101a has an n-type buffer layer made of, for example, an n-type GaN semiconductor. An n-type cladding layer, an active layer, and a p-type cladding layer are sequentially stacked on the n-type buffer layer. An anode electrode 103a is provided on the p-type cladding layer, and a cathode electrode 102a is provided on a part of the back surface of the n-type buffer layer. The LED 101a having such a configuration is formed by sequentially stacking an n-type buffer layer, an n-type cladding layer, an active layer, and a p-type cladding layer on a sapphire substrate, and peeling the n-type buffer layer and the subsequent layers from the sapphire substrate. Can be formed. The LED 101 a is mounted face-down on the conductive package 104 so that the anode electrode 103 a faces the package 104. The cathode electrode 102a is connected to a post 105 insulated from the package 104 via a wire. The LED 101a emits light generated in the active layer from the back surface of the n-type buffer layer.

  In the light emitting device 100b shown in FIG. 16B, the LED 101b has, for example, an insulating sapphire substrate. An n-type cladding layer, an active layer, and a p-type cladding layer are sequentially stacked on the sapphire substrate. Since the sapphire substrate is insulative, the cathode electrode 102b and the anode electrode 103b are formed on the same surface of the sapphire substrate. That is, the cathode electrode 102b is provided on the n-type cladding layer exposed by etching away a part of the p-type cladding layer, and the anode electrode 103b is provided on the remaining p-type cladding layer. The LED 101 b is mounted on the package 104 so that the back surface of the sapphire substrate faces the package 104. The cathode electrode 102b and the anode electrode 103b are connected to the package 104 and the post 105 through wires, respectively. The LED 101b emits light generated in the active layer from a surface where the cathode electrode 102b and the anode electrode 103b are provided.

  In the light emitting device 100c shown in FIG. 16C, the configuration of the LED 101c is the same as that of the LED 101b described above. In the light emitting device 100 c, the LED 101 c is placed on the package 106 so that the cathode electrode 102 c and the anode electrode 103 c face the package 106. The package 106 is provided with wiring patterns 107a and 107b, which are connected to the anode electrode 103c and the cathode electrode 102c via solder, respectively. The LED 101c emits light generated in the active layer from the back surface of the sapphire substrate.

Configurations such as the light emitting devices 100a to 100c described above are disclosed in, for example, the following Patent Documents 1 to 4.
Japanese Patent Laid-Open No. 07-111343 Japanese Patent Application Laid-Open No. 07-235696 JP 07-254731 A Japanese Patent Laid-Open No. 07-283441

  However, each of the above light emitting devices has the following problems. That is, in the light emitting device 100a shown in FIG. 16A and the light emitting device 100b shown in FIG. 16B, the cathode electrodes 102a and 102b (and the anode electrode 103b) are provided on the light emitting surface. Therefore, part of the light generated in the active layer is blocked by the electrode, and the light extraction efficiency is lowered. In particular, when the size of the LED is relatively small, the size of the electrode is relatively large, and the light extraction efficiency is further reduced.

  Further, in the light emitting device 100c shown in FIG. 16C, since the electrode is not provided on the light emitting surface, the above-described problem does not occur. However, when the LED 101c is mounted on the package 106, it is necessary to align the cathode electrode 102c and the anode electrode 103c with respect to the wiring patterns 107a and 107b. Since the cathode electrode 102c and the anode electrode 103c are generally provided close to each other, this alignment operation is difficult and causes a reduction in production efficiency. Also, the solder for connecting the cathode electrode 102c and the wiring pattern 107b and the solder for connecting the anode electrode 103c and the wiring pattern 107a are likely to contact (short) each other.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a light emitting diode and a light emitting device that can be easily mounted and can improve the light extraction efficiency.

  In order to solve the above-described problems, a first light emitting diode according to the present invention includes (1) an n-type semiconductor substrate made of a GaN-based compound, and (2) a nitride semiconductor, on the main surface of the n-type semiconductor substrate. An n-type semiconductor layer provided on the n-type semiconductor layer; (3) a p-type semiconductor layer made of a nitride semiconductor; and (4) a n-type semiconductor layer made of a nitride semiconductor. An active layer provided between the semiconductor layer, (5) an anode electrode provided on the p-type semiconductor layer and ohmically coupled to the p-type semiconductor layer, and (6) provided on a side surface of the n-type semiconductor substrate. And an n-type semiconductor substrate and an ohmic-coupled cathode electrode.

  The second light emitting diode according to the present invention includes (7) an n-type semiconductor substrate made of a GaN-based compound and (8) an n-type semiconductor made of a nitride semiconductor and provided on the main surface of the n-type semiconductor substrate. A layer, (9) a p-type semiconductor layer made of a nitride semiconductor and provided on the n-type semiconductor layer, and (10) a nitride semiconductor made between the n-type semiconductor layer and the p-type semiconductor layer. And (11) an anode electrode provided on the p-type semiconductor layer and ohmically coupled to the p-type semiconductor layer, and (12) provided on a surface connecting the side surface and the back surface of the n-type semiconductor substrate. And a cathode electrode ohmic-coupled to the n-type semiconductor substrate.

  In the first and second light emitting diodes described above, the n-type semiconductor substrate is made of a GaN-based compound and thus has good conductivity. In general, the substrate is sufficiently thicker than a semiconductor layer formed by, for example, epitaxial growth. Therefore, even if the cathode electrode is provided on the side surface instead of the back surface of the n-type semiconductor substrate, the current is diffused in the n-type semiconductor substrate, so that a sufficient current can flow in a wide range of the active layer. According to the first and second light emitting diodes described above, since the cathode electrode is provided not on the back surface of the n-type semiconductor substrate but on the side surface or on the surface connecting the back surface and the side surface, the light generated in the active layer Can be emitted from the back surface of the n-type semiconductor substrate without being blocked by the cathode electrode. In addition, since the anode electrode and the cathode electrode are provided on different surfaces of the n-type semiconductor substrate, alignment work during mounting can be facilitated. From the above, according to this light emitting diode, the mounting operation becomes easy and the light extraction efficiency can be improved.

  The light emitting diode may be characterized in that the thickness of the n-type semiconductor substrate is 50 μm or more and 400 μm or less. By setting the thickness of the n-type semiconductor substrate to 50 μm or more, the current from the cathode electrode provided on the side surface of the n-type semiconductor substrate or the surface connecting the back surface and the side surface is sufficiently generated in the n-type semiconductor substrate. It can diffuse and reach a wide range of the active layer. Further, by setting the thickness of the n-type semiconductor substrate to 400 μm or less, it is possible to sufficiently ensure the transmittance of the light generated in the active layer in the n-type semiconductor substrate.

  The light emitting diode may be characterized in that the resistivity of the n-type semiconductor substrate is 0.5 Ωcm or less. As a result, the current from the cathode electrode is sufficiently diffused in the n-type semiconductor substrate and can reach a wide range of the active layer.

  The light emitting diode may be characterized in that cathode electrodes are provided on all side surfaces of the substrate. Thereby, the current from the cathode electrode can reach a wide range of the active layer. Moreover, since the light from the active layer is reflected at the cathode electrode, the light can be extracted more efficiently from the back surface of the substrate.

  The light-emitting device according to the present invention is provided on one of the above-described light-emitting diodes and the back surface of the n-type semiconductor substrate, and receives light from the active layer and generates light having a wavelength different from that of the light from the active layer. And a fluorescent material. According to any one of the light emitting diodes described above, since it is not necessary to provide a cathode electrode on the back surface of the n-type semiconductor substrate, the phosphor can be disposed close to the back surface of the n-type semiconductor substrate. Therefore, according to this light-emitting device, the light from the active layer can be uniformly irradiated to the phosphor, so that the color unevenness of the emitted light including the light from the active layer and the light from the phosphor can be reduced. Can do.

  According to the light emitting diode and the light emitting device of the present invention, the mounting operation is facilitated and the light extraction efficiency can be improved.

  Hereinafter, embodiments of a light emitting diode and a light emitting device according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a cross-sectional view showing a first embodiment of a light emitting device equipped with a light emitting diode according to the present invention. Referring to FIG. 1, the light emitting device 1 includes a light emitting diode 3 and a package 20. First, the light emitting diode 3 will be described, and then the package 20 will be described.

  FIG. 2 is an enlarged cross-sectional view showing the light emitting diode 3. Referring to FIG. 2, the light emitting diode 3 includes a substrate 5. The light-emitting diode 3 includes an n-type semiconductor layer such as an n-type cladding layer 7 stacked on the substrate. The light emitting diode 3 includes an active layer 9 provided on the n-type cladding layer 7. The light emitting diode 3 includes a p-type semiconductor layer such as a p-type cladding layer 11 and a p-type contact layer 13 that are sequentially stacked on the active layer 9.

  The substrate 5 is made of a GaN compound doped with n-type impurities. In the present embodiment, the substrate 5 is made of GaN doped with Si. The substrate 5 can transmit the light L1 generated in the active layer 9. The specific resistivity of the substrate 5 is preferably 0.5 Ωcm or less. The thickness of the substrate 5 is preferably 50 μm or more and 400 μm or less.

The n-type cladding layer 7 is made of a nitride semiconductor doped with n-type impurities. For example, in the present embodiment, the n-type cladding layer 7 is made of Al _X1 Ga _1-X1 N (0 ≦ X1 <1) doped with Si. The n-type cladding layer 7 is formed on the main surface 5 a of the substrate 5.

  The active layer 9 is a layer that generates light L1 when current (carriers) is injected. In the present embodiment, the wavelength band of the light L1 is a wavelength band that becomes blue light, for example. The active layer 9 is formed on the n-type cladding layer 7 and has a multiple quantum well structure. Here, FIG. 3 is a cross-sectional view showing the configuration of the active layer 9 in the present embodiment. Referring to FIG. 3, the active layer 9 has barrier layers 37a to 37c and well layers 39a and 39b. That is, the active layer 9 is configured by sequentially stacking a barrier layer 37a, a well layer 39a, a barrier layer 37b, a well layer 39b, and a barrier layer 37c.

Barrier layer 37a~37c and the well layers 39a and 39b _are made of _{Al X2 In Y2 Ga 1-X2} -Y2 N (0 ≦ X2 <1,0 ≦ Y2 <1,0 ≦ X2 + Y2 <1) GaN -based semiconductor such as . In the present embodiment, the compositions of the barrier layers 37a to 37c are 0 <X2 <1 and Y2 = 0, and the compositions of the well layers 39a and 39b are 0 <X2 <1 and 0 <Y2 <1. The compositions of the barrier layers 37a to 37c and the well layers 39a and 39b are adjusted so that the band gaps of the barrier layers 37a to 37c are larger than those of the well layers 39a and 39b. With this configuration, carriers injected into the active layer 9 are confined in the well layers 39a and 39b.

Referring to FIG. 2 again, p-type cladding layer 11 is made of a nitride semiconductor doped with a p-type impurity. For example, in this embodiment, the p-type cladding layer 11 is made of Al _X1 Ga _1-X1 N (0 ≦ X1 <1) doped with Mg. The p-type cladding layer 11 is formed on the active layer 9, and the active layer 9 is provided between the n-type cladding layer 7 and the p-type cladding layer 11.

  The p-type contact layer 13 is a layer for electrically connecting the p-type cladding layer 11 and an anode electrode (described later), and is made of a nitride semiconductor doped with a p-type impurity. For example, in this embodiment, the p-type contact layer 13 is made of GaN doped with Mg. The p-type contact layer 13 is formed on the p-type cladding layer 11.

  The anode electrode 15 is provided on the surface of the p-type contact layer 13 opposite to the surface facing the active layer 9. In the present embodiment, the anode electrode 15 is provided over the entire surface on the p-type contact layer 13. The anode electrode 15 is formed by sequentially laminating metals such as Ni / Au / Al / Au, and ohmic contact is realized between the anode electrode 15 and the p-type contact layer 13. The anode electrode 15 also has a function of reflecting the light L1 generated in the active layer 9.

  The cathode electrode 17 is provided on the side surface 5 c of the substrate 5. In the present embodiment, the cathode electrode 17 is provided on a portion of the side surface 5c of the substrate 5 excluding a portion close to the main surface 5a. In other words, the cathode electrode 17 is formed such that a predetermined gap is provided between the portion of the cathode electrode 17 closest to the main surface 5a and the main surface 5a. The cathode electrode 17 is formed by sequentially laminating metals such as Ti / Al / Au, and ohmic contact is realized between the cathode electrode 17 and the substrate 5. The cathode electrode 17 also has a function of reflecting the light L1 generated in the active layer 9.

  Referring again to FIG. 1, the package 20 includes a base body 21, a reflector 23, package outer electrodes 25 a and 25 b, and a wiring pattern 27. The base 21 has a main surface 21a, and a wiring pattern 27 is formed on the main surface 21a. The wiring pattern 27 is formed in a shape corresponding to the planar shape of the light emitting diode 3. The light emitting diode 3 is placed on the wiring pattern 27 via the conductive adhesive 31 so that the anode electrode 15 faces the wiring pattern 27. The wiring pattern 27 is electrically connected to the package outer electrode 25b. The package outer electrode 25 b is made of Cu, for example, and extends toward the outside of the package 20. The package outer electrode 25b is electrically connected to a pattern wiring on a wiring board on which the light emitting device 1 is mounted, for example.

  Further, the cathode electrode 17 of the light emitting diode 3 is electrically connected to the package outer electrode 25 a through the conductive adhesive 32. In the present embodiment, the package outer electrode 25 a is a metal bar that extends along the main surface 21 a of the base 21 and is fixed to the reflector 23. The light emitting diode 3 is positioned on the main surface 21a of the base 21 so that the cathode electrode 17 contacts the package outer electrode 25a (more precisely, the conductive adhesive 32). The package outer electrode 25a is made of Cu, for example, and extends toward the outside of the package 20 like the package outer electrode 25b. The package outer electrode 25a is electrically connected to a pattern wiring on a wiring board on which the light emitting device 1 is mounted, for example.

  The reflector 23 is a member that reflects the light L1 emitted from the light emitting diode 3 and efficiently emits the light L1 in a predetermined direction. The reflector 23 is provided around the light emitting diode 3 on the main surface 21 a of the base 21. The reflector 23 has a light reflecting surface 23 a that reflects light from the active layer 9 (see FIG. 2) of the light emitting diode 3. The light reflecting surface 23a is provided so as to obliquely intersect the direction in which the active layer 9 extends.

  In addition, the base | substrate 21 and the reflector 23 can be formed by shape | molding an epoxy resin using a metal mold | die, for example. At this time, the package 20 can be easily manufactured by setting the wiring pattern 27 and the package outer electrodes 25a and 25b in a mold and molding them. The base 21 and the reflector 23 may be formed of other resin materials, ceramics, glass, or the like in addition to the epoxy resin. As the conductive adhesives 31 and 32, a conductive resin such as an Ag paste may be used in addition to a solder material such as AuSn solder.

  The operation of the light-emitting device 1 having the above configuration is as follows. When a driving voltage is applied between the package outer electrodes 25 a and 25 b from the outside of the light emitting device 1, an electric field is generated between the anode electrode 15 and the cathode electrode 17. Then, carriers are concentrated in the well layers 39a and 39b in the active layer 9. Thereby, light L1 is generated in the active layer 9. Of the light L 1 generated in the active layer 9, the light toward the anode electrode 15 is reflected by the anode electrode 15. The light L <b> 1 is emitted from the back surface 5 b of the substrate 5 to the outside of the light emitting diode 3.

  Next, the method for manufacturing the light emitting diode 3 according to the present embodiment will be described. 4 and 5 are diagrams for explaining a method of manufacturing the light emitting diode 3. First, as shown in FIG. 4A, a wafer 28 made of GaN doped with n-type impurities is prepared. 4B, the n-type cladding layer 7, the active layer 9, the p-type cladding layer 11, and the p-type contact layer 13 are epitaxially grown on the main surface 28a of the wafer 28 in this order. Subsequently, as shown in FIG. 4C, an anode electrode 15 is formed on the p-type contact layer 13 by vapor deposition or the like.

  Subsequently, as shown in FIG. 5A, the wafer 28 and each layer are cut in the thickness direction to form chips 19 having a predetermined size. At this time, the wafer 28 is cut to form the substrate 5, and the side surface 5c of the substrate 5 is formed. Subsequently, as shown in FIG. 5B, the chips 19 are adjacent to each other so that one of the four side surfaces 5 c of the chip 19 faces down and the anode electrode 15 faces in the same direction. Then, a mask having a predetermined pattern is applied to the upward side surface 5c of the side surface 5c of the substrate 5, and Ti / Al / Au is sequentially deposited to form the cathode electrode 17. Thus, the light emitting diode 3 is completed.

  The light emitting diode 3 according to the present embodiment described above has the following effects. That is, the light emitting diode 3 has good conductivity because the substrate 5 is an n-type semiconductor made of a GaN-based compound. Further, the substrate 5 in this embodiment is sufficiently thicker than semiconductor layers such as the n-type cladding layer 7, the active layer 9, and the p-type cladding layer 11 formed by, for example, epitaxial growth. Therefore, in the present embodiment, the cathode electrode 17 is provided on the side surface 5c, not on the back surface 5b of the substrate 5. However, since the current is suitably diffused in the substrate 5, a sufficient current flows in a wide range of the active layer 9. It is possible.

  According to the light emitting diode 3 according to the present embodiment, since the cathode electrode 17 is provided on the side surface 5 c of the substrate 5, the light L <b> 1 generated in the active layer 9 is not blocked by the cathode electrode 17 and the back surface of the substrate 5. 5b can be emitted. Further, since the anode electrode 15 and the cathode electrode 17 are provided on different surfaces of the substrate 5, it is not necessary to strictly align the wiring pattern during mounting, and the alignment operation is facilitated. From the above, according to the light emitting diode 3, the mounting operation becomes easy and the light extraction efficiency can be improved.

  Further, according to the light emitting diode 3 according to the present embodiment, the light L1 can be emitted from the back surface 5b of the substrate 5 without being blocked by the cathode electrode 17, so that the planar dimension of the light emitting diode 3 can be reduced. Become. In addition, the anode electrode 15 can be provided over the entire main surface 5a of the substrate 5 and the entire surface of the anode electrode 15 can be bonded to the wiring pattern 27 via the conductive adhesive 31. The generated heat can be released efficiently.

  Further, as in this embodiment, the thickness of the substrate 5 is preferably 50 μm or more and 400 μm or less. By setting the thickness of the substrate 5 to 50 μm or more, the current from the cathode electrode 17 provided on the side surface 5 c of the substrate 5 is sufficiently diffused in the substrate 5 and reaches a wide range of the active layer 9. it can. Further, by setting the thickness of the substrate 5 to 400 μm or less, it is possible to sufficiently secure the transmittance of the light L1 generated in the active layer 9 in the substrate 5.

  Further, as in this embodiment, the resistivity of the substrate 5 is preferably 0.5 Ωcm or less. As a result, the current from the cathode electrode 17 is further sufficiently diffused in the substrate 5 and can reach a wider range of the active layer 9.

(First modification)
Next, a second manufacturing method of the light-emitting diode 3 will be described as a first modification of the above-described first embodiment. FIGS. 6A and 6B are diagrams showing a method for manufacturing the light-emitting diode 3 in the present modification. First, as shown in FIG. 6A, the wafer 28 on which the anode electrode 15 and each semiconductor layer (not shown) are stacked is cut into strip-shaped chips along one certain direction.

  Subsequently, as shown in FIG. 6 (b), one of the two cut surfaces of the strip-shaped chip 36 is positioned downward, and the longitudinal direction of the strip-shaped chip 36 is along a predetermined direction. In addition, a plurality of strip-shaped chips 36 are arranged. Then, the cathode electrode 17 is formed on the side surface 33 c of the wafer 33 among the other cut surfaces of the strip-shaped chip 36. At this time, the cathode electrode 17 is formed by applying a mask having a pattern along the longitudinal direction of the strip-shaped chip 36 on the other cut surface of the strip-shaped chip 36 and sequentially depositing Ti / Al / Au. Finally, the strip-shaped chip 36 on which the cathode electrode 17 is formed is cut into a predetermined size, whereby the light emitting diode 3 is completed.

(Second modification)
Next, the 3rd manufacturing method of the light emitting diode 3 is demonstrated as a 2nd modification of above-described 1st Embodiment. FIG. 7A to FIG. 7C and FIG. 8 are diagrams showing a method for manufacturing the light-emitting diode 3 in the present modification. First, as shown in FIG. 7A, a chip 19 (see FIG. 5A) in which an anode electrode 15 and each semiconductor layer are formed on a substrate 5 and a transfer jig 41 are prepared. Here, the transfer jig 41 is a plate-like jig provided with a plurality of depressions 41 a for accommodating the chips 19. By placing the plurality of chips 19 on the transfer jig 41 and swinging the transfer jig 41, the plurality of chips 19 are accommodated in the recesses 41a as shown in FIG. 7B. At this time, the plurality of chips 19 are accommodated such that one side surface 5c of the substrate 5 is in contact with the bottom surface of the recess 41a and the anode electrode 15 faces in the same direction.

  Subsequently, as shown in FIG. 7C, the L-shaped jig 43 is inserted into the gap between the recess 41 a and the chip 19. The L-shaped jig 43 has a metal mask 43a and a positioning member 43b, and the back surface of the metal mask 43a is joined to the upper surface of the positioning member 43b. If this L-shaped jig 43 is used, the positioning member 43b is inserted into the gap between the recess 41a and the chip 19 to fix the chip 19, and a part of the side surface of the substrate 5 is removed from the upward side surface of the chip 19. The portion can be covered with the metal mask 43a.

  Subsequently, Ti / Al / Au is sequentially deposited on the upward side surface of the chip 19 through the metal mask 43a. Thus, as shown in FIG. 8, the cathode electrode 17 is formed on the side surface of the substrate 5 to complete the light emitting diode 3.

(Third Modification)
Next, light emitting diodes 3a to 3c and a manufacturing method thereof will be described as a third modified example of the first embodiment. FIGS. 9A to 9C are perspective views showing the light emitting diodes 3a to 3c, respectively. The light emitting diodes 3a to 3c are different from the light emitting diode 3 of the first embodiment in the shapes of the substrate and the cathode electrode. First, referring to FIG. 9A, the substrate 5 of the light emitting diode 3a has a surface 5f connecting the side surface 5c and the back surface 5b. Four surfaces 5f are formed along the four sides of the back surface 5b. The cathode electrode 16 is formed on the surface 5f of the substrate 5 so as to surround the back surface 5b.

  Referring to FIG. 9B, the substrate 5 of the light emitting diode 3b has a surface 5g connecting the side surface 5c and the back surface 5b. Two surfaces 5g are formed adjacent to two opposing side surfaces 5c of the four side surfaces 5c of the substrate 5. Two cathode electrodes 16a are formed on the surface 5g of the substrate 5 so as to sandwich the back surface 5b.

  Referring to FIG. 9C, a surface 5h connecting the side surface 5c and the back surface 5b is formed on the substrate 5 of the light emitting diode 3c. One surface 5 h is formed adjacent to one side surface 5 c of the four side surfaces 5 c of the substrate 5. A cathode electrode 16b is formed on the surface 5h of the substrate 5 along one side of the back surface 5b.

  10A to 10D are views showing a method for manufacturing the above-described light emitting diode 3a. First, a wafer 28 is prepared, and an n-type cladding layer 7, an active layer 9, a p-type cladding layer 11, a p-type contact layer 13, and an anode electrode 15 are sequentially formed on the main surface 28a of the wafer 28 (FIG. 4 ( a) to FIG. 4C). Then, as shown in FIG. 10A, a groove 45 is formed on the back surface 28 b of the wafer 28. At this time, the groove 45 may be formed by digging the back surface 28b of the wafer 28 to a predetermined depth with a dicing blade or a scriber. Alternatively, a mask having an opening in a portion where the groove 45 is to be formed may be applied to the back surface 28b of the wafer 28, and the groove 45 may be formed by dry etching or wet etching. In addition, when the groove | channel 45 is formed by wet etching, the cross section of the groove | channel 45 becomes triangular shape as shown to Fig.10 (a). On the other hand, when the groove 45 is formed by dry etching, the cross section of the groove is rectangular.

  Subsequently, as shown in FIG. 10B, the cathode electrode 16 is embedded by sequentially depositing Ti / Al / Au in the groove 45 formed on the back surface 28 b of the wafer 28. Subsequently, as shown in FIG. 10C, the wafer 28, each semiconductor layer, and each electrode are cut along the groove 45 in the thickness direction. As a cutting method at this time, for example, a method in which the blade 28 is pressed from the anode electrode 15 side along the groove 45 to break the wafer 28, each semiconductor layer, and each electrode (braking), or a wafer with a diamond needle is used. There are a method of scratching the surface (scribing) and then splitting by pressing the blade (braking), or a method of cutting the wafer 28, each semiconductor layer, and each electrode along the groove 45 using a dicing blade. . Thus, the light emitting diode 3a is formed (FIG. 10D). Note that the light emitting diodes 3b and 3c shown in FIGS. 9B and 9C can be formed by changing the shape of the groove 45. FIG.

  According to the light emitting diodes 3a to 3c according to this modification, the same effects as those of the light emitting diode 3 of the first embodiment described above can be obtained. That is, according to the light emitting diodes 3a to 3c according to this modification, the cathode electrodes 16, 16a and 16b are provided not on the back surface 5b of the substrate 5 but on the surfaces 5f to 5h connecting the back surface 5b and the side surface 5c. . Therefore, the light generated in the active layer 9 can be emitted from the back surface 5b of the substrate 5 without being blocked by the cathode electrodes 16, 16a, and 16b. Further, since the anode electrode 15 and the cathode electrodes 16, 16a, and 16b are provided on different surfaces of the substrate 5, alignment work at the time of mounting can be facilitated. From the above, according to the light emitting diodes 3a to 3c according to the present modification, the mounting operation is facilitated and the light extraction efficiency can be improved.

  Note that in the light emitting diodes 3a to 3c according to the present embodiment, the surfaces 5f to 5h are not limited to flat surfaces, and may be curved surfaces. Further, the surfaces 5f to 5h may be composed of a plurality of planes.

(Fourth modification)
Next, as a fourth modification of the first embodiment described above, a method for manufacturing the light emitting diode 3d will be described. FIG. 11A to FIG. 11D are diagrams showing a method for manufacturing the light emitting diode 3d in the present modification. First, a wafer 28 is prepared, and an n-type cladding layer 7, an active layer 9, a p-type cladding layer 11, a p-type contact layer 13, and an anode electrode 15 are sequentially formed on the main surface 28a of the wafer 28 (FIG. 4 ( a) to FIG. 4 (c)). Then, as shown in FIG. 11A, a resist 47 is applied on the back surface 28 b of the wafer 28. Subsequently, as shown in FIG. 11B, the resist 47, the wafer 28, each semiconductor layer, and the anode electrode 15 are cut from the back surface 28b side of the wafer 28 using a dicing blade to form the chip 24. At this time, by using a dicing blade having a cutting edge having a relatively large angle, the side surface 5d of the substrate 5 is formed to be inclined with respect to the thickness direction. In other words, the cross section of the substrate 5 has a trapezoidal shape with the major surface 5a as the long side, the back surface 5b as the short side, and the side surface 5d as the oblique side.

  Subsequently, as shown in FIG. 11C, the chip 24 is placed on the work table 51 with the anode electrode 15 facing down. Then, a resist 49 is formed over the work table 51 from the side surface of the chip 24, and the chip 24 is fixed to the work table 51. At this time, a resist 49 is formed so as to cover the anode electrode 15 and each semiconductor layer. Subsequently, as shown in FIG. 11D, Ti / Al / Au is sequentially deposited on the surface of the chip 24 that is not covered with the resists 47 and 49 (that is, the side surface 5d of the substrate 5). A cathode electrode 18 is formed. Thereafter, if the resists 47 and 49 are removed, the light emitting diode 3d is completed.

(Fifth modification)
Next, as a fifth modification of the first embodiment described above, a method for manufacturing a light emitting diode will be described. FIG. 12A to FIG. 12D are diagrams showing a method for manufacturing a light emitting diode in the present modification. First, as shown in FIG. 12A, a wafer 28 is prepared, and the n-type cladding layer 7, the active layer 9, the p-type cladding layer 11, the p-type contact layer 13, and the anode electrode 15 are arranged on the main surface of the wafer 28. It forms in order on 28a. Then, as shown in FIG. 12B, the anode electrode 15 and each semiconductor layer are cut from the main surface 28a side of the wafer 28 using a dicing blade, and the wafer 28 is cut halfway. At this time, by using a dicing blade having a cutting edge having a relatively large angle, the side surface 28e of the groove of the wafer 28 is formed to be inclined with respect to the thickness direction.

  Subsequently, as shown in FIG. 12C, a resist 53 is formed so as to cover the anode electrode 15 and each semiconductor layer. Subsequently, as shown in FIG. 12D, Ti / Al / Au is sequentially deposited on the side surface 28 e of the groove of the wafer 28 not covered with the resist 53, thereby forming the cathode electrode 22. Thereafter, the resist 53 is removed and the wafer 28 is completely cut along the groove to complete the light emitting diode.

  According to the light emitting diode 3d according to the fourth modified example and the light emitting diode according to the fifth modified example, the same effects as those of the light emitting diode 3 according to the first embodiment can be obtained, and the side surface 5d and the side surface 28e of the substrate 5 can be obtained. Is inclined with respect to the thickness direction, the light extraction efficiency can be further improved.

(Second Embodiment)
FIG. 13 is a cross-sectional view showing a second embodiment of a light emitting device equipped with a light emitting diode according to the present invention. Referring to FIG. 13, the light emitting device 1 a according to the present embodiment includes a light emitting diode 3 f and a package 60. Here, the light emitting diode 3 f is different from the light emitting diode 3 of the first embodiment in the shapes of the anode electrode 35 and the cathode electrode 34. Since the configuration of the light emitting diode 3f other than the anode electrode 35 and the cathode electrode 34 is the same as the configuration of the light emitting diode 3 of the first embodiment, a detailed description thereof is omitted.

  The anode electrode 35 is formed such that a portion closest to the cathode electrode 34 is separated from the cathode electrode 34 by a predetermined distance. That is, the anode electrode 35 is formed on the surface of the p-type contact layer at a predetermined distance (for example, about several tens of μm) from the side surface 5c of the substrate 5 on which the cathode electrode 34 is provided. This is to prevent a short circuit between the anode electrode 35 and the cathode electrode 34.

  The cathode electrode 34 is provided on all the side surfaces 5 c of the substrate 5. Further, the cathode electrode 34 has a light reflection function, and reflects the light L1 from the active layer and collects the light L1 on the back surface 5b of the substrate 5.

  The package 60 includes a base 61, a reflector 63, package outer electrodes 65a and 65b, and wiring patterns 67a and 67b. The base 61 has a main surface 61a, and a wiring pattern 67a is formed on the main surface 61a. The wiring pattern 67 a is formed in a shape corresponding to the planar shape of the anode electrode 35. The base 61 has a wall surface 61b whose normal direction intersects the normal direction of the main surface 61a, and a wiring pattern 67b is formed on the wall surface 61b.

  The light emitting diode 3f is placed on the wiring pattern 67a so that the anode electrode 35 faces the wiring pattern 67a and the cathode electrode 34 on one side surface 5c of the cathode electrode 34 faces the wiring pattern 67b. Has been. The anode electrode 35 is electrically connected to the wiring pattern 67 a through the conductive adhesive 31. The cathode electrode 34 is electrically connected to the wiring pattern 67 b through the conductive adhesive 32. The wiring patterns 67a and 67b are electrically connected to the package outer electrodes 65a and 65b, respectively. The package outer electrodes 65a and 65b respectively extend along the outer wall of the base 61 and are electrically connected to, for example, a pattern wiring on a wiring board on which the light emitting device 1a is mounted.

  The reflector 63 is a member for reflecting the light L1 emitted from the light emitting diode 3f and the light L2 from the phosphor 26 and efficiently extracting the lights L1 and L2 in a predetermined direction. About the structure and shape of the reflector 63, since it is the same as that of the reflector 23 of 1st Embodiment, detailed description is abbreviate | omitted.

  In addition, the light emitting device 1 a according to the present embodiment includes a phosphor 26. The phosphor 26 is formed by solidifying a fluorescent material that receives the light L1 and generates light L2 having a wavelength longer than that of the light L1. In the present embodiment, the light L1 is light in a wavelength band that becomes blue light, and the light L2 is light in a wavelength band that becomes yellow light. An example of the fluorescent material that emits such light L2 is ZnSSe. The phosphor 26 is stuck on the back surface 5b of the substrate 5 via an adhesive. The thickness of the phosphor 26 is adjusted so that the amount of fluorescence (yellow light) L2 generated in the phosphor 26 becomes white light of a desired color by the yellow light L2 and the blue light L1. . Further, a buffer member having a refractive index between the refractive index of the phosphor 26 and the refractive index of the substrate 5 may be provided between the phosphor 26 and the substrate 5. By providing such a buffer member, the loss of the light L1 when the light L1 enters the phosphor 26 from the substrate 5 can be reduced.

  Next, the method for manufacturing the light emitting device 1a according to the present embodiment will be described. 14-15 is a figure for demonstrating the manufacturing method of the light-emitting device 1a. First, as shown in FIG. 14A, a package 60 is formed. That is, the wiring patterns 67a and 67b and the package outer electrodes 65a and 65b are set in a mold having a predetermined shape, and, for example, an epoxy resin is poured into the mold. And after an epoxy resin hardens | cures, it takes out from a metal mold | die. Thus, the package 60 including the base 61, the reflector 63, the wiring patterns 67a and 67b, and the package outer electrodes 65a and 65b is formed.

  Subsequently, as shown in FIG. 14B, the light emitting diode 3 f in which each semiconductor layer, the anode electrode 35, and the cathode electrode 34 are formed on the substrate 5 is placed on the main surface 61 a of the base 61. In addition, about the manufacturing method of the light emitting diode 3f, it is the same as that of the manufacturing method of the light emitting diode 3 of 1st Embodiment mentioned above. At this time, the light emitting diode 3f is moved to a predetermined position while the light emitting diode 3f is suspended from the collet 71 by the vacuum chuck function (arrow 77 in the figure) of the die bonder. At this time, conductive adhesives 31 and 32 are applied to the anode electrode 35 and the cathode electrode 34, respectively.

  Subsequently, as shown in FIG. 15A, the side surface 71a of the collet 71 is pressed against the cathode electrode 34 to determine the position of the light emitting diode 3f. Alternatively, as shown in FIG. 15B, a fixing jig 75 having an inclined surface 75a along the light reflecting surface 63a of the reflector 63 is prepared, and this fixing jig 75 is placed in the gap between the reflector 63 and the light emitting diode 3f. The position of the light emitting diode 3f may be determined by insertion. In this state, the package 60 and the light emitting diode 3f are placed in a nitrogen atmosphere, and the package 60 is heated to 300 ° C. The conductive adhesives 31 and 32 are melted, the anode electrode 35 and the wiring pattern 67a are fixed to each other, and the cathode electrode 34 and the wiring pattern 67b are fixed to each other. Finally, the phosphor 26 is stuck on the back surface 5 b of the substrate 5. Thus, the light emitting device 1a is completed.

  The light emitting device 1a according to the present embodiment has the following effects. That is, since the light emitting device 1 a includes the light emitting diode 3 f having the same configuration as that of the first embodiment, it is not necessary to provide a cathode electrode on the back surface 5 b of the substrate 5, and the phosphor 26 is attached to the substrate 5. It can arrange | position close to the back surface 5b. Therefore, according to the light emitting device 1a, the light L1 from the active layer 9 can be uniformly irradiated onto the phosphor 26. Therefore, the light L1 from the active layer 9 and the light L2 from the phosphor 26 are included. Color unevenness of incident light (for example, white light) can be reduced.

  In the light emitting diode 3 f according to the present embodiment, the cathode electrode 34 is provided on all the side surfaces 5 c of the substrate 5. Thereby, the current from the cathode electrode 34 can reach a wide range of the active layer 9. In addition, since the cathode electrode 34 has a light reflection function, the light L1 from the active layer 9 is reflected by the cathode electrode 34, so that the light L1 can be extracted from the back surface 5b of the substrate 5 more efficiently. In particular, since the phosphor 26 is provided on the back surface 5b of the substrate 5 in the present embodiment, the light L1 can be efficiently applied to the phosphor 26, and the light L1 leaks without entering the phosphor 26. Can be prevented.

FIG. 1 is a cross-sectional view showing a first embodiment of a light emitting device equipped with a light emitting diode according to the present invention. FIG. 2 is an enlarged cross-sectional view showing a light emitting diode. FIG. 3 is a cross-sectional view showing the configuration of the active layer in the present embodiment. FIG. 4A to FIG. 4C are views for explaining the method for manufacturing the light emitting diode in the first embodiment. FIG. 5A and FIG. 5B are views for explaining a method of manufacturing the light emitting diode in the first embodiment. FIG. 6A and FIG. 6B are diagrams showing a method for manufacturing a light emitting diode in the first modification. FIG. 7A to FIG. 7C are views showing a method for manufacturing a light emitting diode in the second modified example. FIG. 8 is a diagram showing a method for manufacturing a light emitting diode in the second modification. FIG. 9A to FIG. 9C are perspective views showing light emitting diodes according to a third modification. FIG. 10A to FIG. 10D are views showing a light emitting diode manufacturing method according to a third modification. FIG. 11A to FIG. 11D are diagrams showing a method for manufacturing a light emitting diode in a fourth modification. FIG. 12A to FIG. 12D are diagrams showing a method for manufacturing a light emitting diode in the fifth modification. FIG. 13 is a cross-sectional view showing a second embodiment of a light emitting device equipped with a light emitting diode according to the present invention. FIG. 14A and FIG. 14B are views for explaining a method of manufacturing the light emitting device according to the second embodiment. FIG. 15A and FIG. 15B are views for explaining a method of manufacturing the light emitting device according to the second embodiment. FIG. 16A to FIG. 16C are diagrams showing a conventional light emitting device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 1a ... Light-emitting device, 3, 3a-3f ... Light-emitting diode, 5 ... Board | substrate, 5a ... Main surface, 5b ... Back surface, 5c, 5d ... Side surface, 7 ... N-type clad layer, 9 ... Active layer, 11 ... p Type cladding layer, 13 ... p-type contact layer, 15, 35 ... anode electrode, 16-18, 34 ... cathode electrode, 19, 24 ... chip, 20, 60 ... package, 21, 61 ... substrate, 22, 34 ... cathode Electrodes 23, 63 ... reflectors, 25a, 25b, 65a, 65b ... package outer electrodes, 26 ... phosphors, 27 ... wiring patterns, 28, 33 ... wafers, 31, 32 ... conductive adhesives, 36 ... strip chips 37a to 37c ... barrier layers, 39a, 39b ... well layers, 45 ... grooves, 47, 49, 53 ... resists, 67a, 67b ... wiring patterns.

Claims (6)

An n-type semiconductor substrate made of a GaN-based compound;
An n-type semiconductor layer made of a nitride semiconductor and provided on the main surface of the n-type semiconductor substrate;
A p-type semiconductor layer made of a nitride semiconductor and provided on the n-type semiconductor layer;
An active layer made of a nitride semiconductor and provided between the n-type semiconductor layer and the p-type semiconductor layer;
An anode electrode provided on the p-type semiconductor layer and ohmically coupled to the p-type semiconductor layer;
A cathode electrode provided on a side surface of the n-type semiconductor substrate and ohmically coupled to the n-type semiconductor substrate;
A light emitting diode comprising:   The light emitting diode according to claim 1, wherein the cathode electrode is provided on all side surfaces of the substrate. An n-type semiconductor substrate made of a GaN-based compound;
An n-type semiconductor layer made of a nitride semiconductor and provided on the main surface of the n-type semiconductor substrate;
A p-type semiconductor layer made of a nitride semiconductor and provided on the n-type semiconductor layer;
An active layer made of a nitride semiconductor and provided between the n-type semiconductor layer and the p-type semiconductor layer;
An anode electrode provided on the p-type semiconductor layer and ohmically coupled to the p-type semiconductor layer;
A cathode electrode provided on a surface connecting the side surface and the back surface of the n-type semiconductor substrate, and ohmic coupled to the n-type semiconductor substrate;
A light emitting diode comprising:   The light emitting diode according to claim 1, wherein the n-type semiconductor substrate has a thickness of 50 μm or more and 400 μm or less.   The light emitting diode as described in any one of Claims 1-4 whose resistivity of the said n-type semiconductor substrate is 0.5 ohm-cm or less. The light emitting diode according to any one of claims 1 to 5,
A phosphor that is provided on the back surface of the n-type semiconductor substrate and receives light from the active layer and generates light having a wavelength different from that of the light from the active layer;
A light emitting device comprising:

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