JP4065655B2 - Flip-chip type semiconductor light-emitting device, manufacturing method thereof, light-emitting diode lamp, display device, and electrode for flip-chip type semiconductor light-emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor light emitting device and a light emitting diode lamp that extract light from the surface of a transparent semiconductor layer, and more particularly to a flip chip type semiconductor light emitting device and a light emitting diode lamp that do not use wire bonds.
[0002]
[Prior art]
Conventionally, semiconductor light-emitting diodes are generally assembled by wire-bonding gold or aluminum fine wires to gold or aluminum electrodes on the surface of the semiconductor light-emitting element. In order to improve the luminance of the light emitting diode, a technique using a transparent substrate is disclosed. For example, Japanese Patent Application Laid-Open No. 61-102786 discloses a method of forming a light emitting structure on a transparent substrate. Japanese Patent Laid-Open No. 6-302857 discloses a method for forming a light emitting structure on an opaque substrate, further forming a transparent layer, and then removing the opaque substrate. Japanese Patent Laid-Open No. 8-130326 discloses a method in which a light emitting structure is formed on an opaque substrate, a transparent substrate is bonded to the opaque substrate, and then the opaque substrate is removed. Further, as described in Japanese Patent Application Laid-Open No. 9-186365, a technique using a reflection effect by a metal electrode on the back surface using a transparent substrate has been proposed.
In addition, a so-called flip-chip type semiconductor light emitting device has been proposed that eliminates the wire bonding step and has excellent productivity and does not cause defects such as wire breakage. These semiconductor light emitting elements utilize a thick AlGaAs semiconductor layer that is transparent to light emission formed by a liquid phase epitaxial method (see Japanese Patent Laid-Open No. 9-27498). In addition, a GaN-based light emitting device often uses a transparent and insulating sapphire substrate, and a technology of a flip chip type light emitting device is disclosed that uses silver white metal on the surface for the purpose of improving the brightness by reflected light. (See JP-A-11-191641).
[0003]
[Problems to be solved by the invention]
As described above, the flip chip type semiconductor light emitting device having excellent productivity and reliability and having two electrodes on one side has been put to practical use because there are many restrictions on the material and structure of the available semiconductor light emitting device. At present, there are few light emitting diodes. In recent years, a high-intensity light emitting diode having an AlGaInP-based light emitting layer that has been put into practical use has not been put into practical use because of many problems.
The present invention solves these problems and provides a structure of a flip-chip type semiconductor light-emitting element that can be used in a high-intensity AlInGaP-based semiconductor light-emitting element, and a light-emitting diode lamp using the same.
The first problem with conventional flip-chip type semiconductor light-emitting devices is that, except for materials that can form transparent electrodes, such as GaN-based light-emitting devices, the interface between the ohmic electrode and the semiconductor becomes a light-absorbing layer and the light emission intensity is reduced. It is a point to do.
The second problem is that if the distance from the light emitting layer to the back surface is too large, the step between the first electrode and the second electrode becomes large, and a problem that wiring defects are likely to occur occurs. Here, the back surface refers to a surface opposite to a surface (light emitting surface) from which light from the semiconductor light emitting element is extracted.
A third problem is that when the distance between the back surface and the light emitting layer is too short, the current cannot be sufficiently diffused to reach the light emitting layer, and the light emission efficiency of the light emitting layer is lowered.
The fourth problem is that when the semiconductor light emitting element is thin, the mechanical strength is weak and defects frequently occur due to cracks during handling.
[0004]
Further, in the case of using an insulating substrate, there is a problem that a current flowing region is narrow and resistance is high, a forward voltage is high, and power consumption is increased.
The present invention has been proposed in view of the above-described problems, and can be manufactured with high productivity, has high luminance and low power consumption, and further reduces the assembly cost by reducing the number of wiring steps by wire bonding. An object of the present invention is to provide a chip-type semiconductor light-emitting device and a light-emitting diode lamp using the same.
[0005]
[Means for Solving the Problems]
As a result of researches to solve the above problems, the inventors of the present invention limited the material used for the substrate and the thickness of the light emitting element, and the current diffusion layer reduced the luminance even when the distance between the back surface and the light emitting layer was reduced. We have developed a device structure that does not degrade.
[0006]
  In order to solve the above problems, the present invention has a second conductive type, a transparent semiconductor layer that is transparent to light emitted from the light emitting portion, and a second layer that is sequentially laminated on one surface of the transparent semiconductor layer. A semiconductor layer made of AlGaInP, which includes a conductive semiconductor layer and a first conductive semiconductor layer and has a light emitting portion with a pn junction structure, and a part of the surface of the first conductive semiconductor layer opposite to the transparent semiconductor layer A first electrode in ohmic contact with the first conductivity type semiconductor layer formed in a dispersed manner, and a first conductivity type semiconductor layer on the surface of the first conductivity type semiconductor layer on which the first electrode is formed, A current spreading layer formed over the first electrode;Formed on one surface of the transparent semiconductor layer exposed by removing a part of the semiconductor layer;A second electrode electrically isolated from the current diffusion layer and in ohmic contact with the transparent semiconductor layer, wherein the current diffusion layer forms a reflective layer that reflects light emitted from the light emitting portion; A plurality of first electrodes are disposed on the surface of the first conductivity type semiconductor layer, and the total area of the first electrodes is 2% to 30% of the surface area of the first conductivity type semiconductor layer, A contact resistance between the first electrode and the first conductivity type semiconductor layer is smaller than a contact resistance between the current diffusion layer and the first conductivity type semiconductor layer, and the first electrode and the first conductivity type semiconductor layer are The contact resistance of the semiconductor layer is 50Ω or less, the thickness of the first electrode is in the range of 0.2 to 1.0 μm, the thickness of the second electrode is in the range of 2 to 6 μm, The thickness is in the range of 2 to 5 μm, and the first electrode surface and the second electrode surface The bell difference is within 4 μm, the contact resistance between the second electrode and the transparent semiconductor layer or the second conductivity type semiconductor layer is 50Ω or less, and the second electrode is provided in a sector shape at the corner portion of the element. The carrier concentration of the transparent semiconductor layer is 2 × 10¹⁶cm^-3The flip-chip type semiconductor light emitting device in which the specific resistance of the transparent semiconductor layer is 1 Ωcm or less, the thickness of the transparent semiconductor layer is in the range of 50 to 100 μm, and the transparent semiconductor layer is made of GaP. .
  By forming the semiconductor light emitting device having such a structure, the current applied to the semiconductor light emitting device spreads over the entire surface of the device through the first electrode formed by being dispersed in a part of the surface of the semiconductor layer, so that the light emitting region This increases the light emission efficiency and effectively reflects the light emitted in the direction of the back surface by the current diffusion layer, and the emitted light can be extracted outside without being absorbed by the substrate. The light emitting element is obtained. In addition, since a current can be applied from one side of the element, when the semiconductor light emitting element is mounted on another electronic device, the work becomes easy and the efficiency can be improved.
[0007]
  The present inventionIn,As above,The current spreading layer is preferably a reflective layer that reflects light emitted from the light emitting portion.
  Such a current spreading layer can be composed of a metal thin film containing gold or a gold alloy. Alternatively, it can be formed of a metal thin film containing a refractory metal. As the refractory metal, one of chromium, platinum or titanium or an alloy thereof can be used.
  The current spreading layer in the present invention may be composed of a multilayer film of two or more kinds of metals.
  The thickness of the current spreading layer is suitably about 0.5 μm to 3 μm.
  These metal thin films have the effect of diffusing the applied current over a wide range because of their high electrical conductivity, and also have the function of reflecting the light emitted from the light emitting layer because of the high light reflectivity, and the light from the light emitting surface. It can be taken out efficiently.
[0008]
  In addition, the present inventionIn,As above,A plurality of first electrodes are preferably arranged on the surface of the first conductivity type semiconductor layer. The total area of the first electrodes is preferably 2% to 30% of the surface area of the first conductivity type semiconductor layer.
  By adopting such a configuration, the applied current diffuses almost evenly throughout the light emitting layer, and the light emitted in the direction of the current diffusion layer can be effectively reflected without being significantly absorbed. The luminance of the semiconductor light emitting device is improved.
[0009]
  Furthermore,In the present invention,As above,It is preferable that the contact resistance between the first electrode and the first conductivity type semiconductor layer is smaller than the contact resistance between the current diffusion layer and the first conductivity type semiconductor layer. The contact resistance between the first electrode and the first conductivity type semiconductor layer is preferably 50Ω or less.
  If the contact resistance between the first electrode and the first conductivity type semiconductor layer is smaller than the contact resistance between the current diffusion layer and the first conductivity type semiconductor layer, the operating current of the light emitting element is from the current diffusion layer. Since it flows preferentially to the semiconductor layer through the first electrode, there is an effect of spreading over the entire surface of the element according to the arrangement of the first electrode.
  Further, if the total area of the first electrodes is ensured to be 2% or more of the surface area of the first conductive semiconductor layer, the contact resistance between the first electrode and the first conductive semiconductor layer is 50Ω. As a result, the current can be supplied smoothly and the field of view is sufficiently secured.
[0010]
  Furthermore,In the semiconductor light emitting device of the present invention,As above,The level difference between the first electrode surface and the second electrode surface is preferably within 4 μm. In the semiconductor light emitting device of the present invention, a difference in level between the surface of the first electrode and the surface of the second electrode is unavoidable in terms of structure and manufacturing method. However, if the level difference becomes too large, connection failure may occur in the mounting process for assembling the lamp. If the level difference is within 4 μm, the level difference can be absorbed in the process of assembling the lamp by using, for example, solder bumps, etc., and contact failure can be prevented, so that product failure can be prevented.
  Further, as described above, it is preferable that the light emitting portion is made of AlGaInP. Since the AlGaInP quaternary mixed crystal semiconductor is a direct transition type semiconductor, the light emission output is high, and the emission wavelength can be changed by changing the mixed crystal ratio of Al and Ga. Further, there is an advantage that lattice matching with a commercially available GaAs single crystal substrate can be easily obtained.
[0011]
In the semiconductor light emitting device of the present invention, the carrier concentration of the transparent semiconductor layer is 2 × 10.¹⁶cm^-3The above is preferable. The specific resistance of the transparent semiconductor layer is preferably 1 Ωcm or less.
The specific resistance of the semiconductor layer is determined by the carriers in the semiconductor layer, and the specific resistance decreases as the number of carriers increases. Carrier concentration is 2 × 10¹⁶cm^-3If a transparent semiconductor layer having a specific resistance of 1 Ωcm or less is used as described above, there is an advantage that it can be operated with a low forward voltage.
[0012]
GaP can be used as a semiconductor layer having a high carrier concentration and a low specific resistance as described above. Since GaP has a large band gap energy, when AlGaInP has a light emitting portion structure, it has a transparent property with respect to a wide range of emission wavelengths. GaP also has an advantage that high-quality crystals can be easily obtained.
[0014]
Furthermore, in the semiconductor light emitting device of the present invention, it is preferable that the first conductivity type is n-type and the second conductivity type is p-type.
As for a commercially available GaAs single crystal substrate, a high-quality substrate with fewer crystal defects is available for n-type, and generally, n-type electrode has lower resistance, and considering the stacking order, the area of the first electrode is reduced. This is because it can be made smaller.
[0015]
In the flip-chip type semiconductor light emitting device of the present invention, the total thickness of the semiconductor light emitting device is preferably 50 μm or more and 100 μm or less.
Instead of an opaque semiconductor substrate, a transparent and low-resistance semiconductor layer is used as a support layer, but if this transparent and low-resistance semiconductor layer is formed thick and the total thickness is increased, a transparent support layer can be obtained. It is also convenient when assembling a light emitting diode lamp described later. However, if it is too thick, it will be uneconomical.
[0016]
  Next, the manufacturing method of the flip chip type semiconductor light emitting device of the present invention is as follows.Made of GaAsOn a semiconductor substrateMade of AlGaInPA semiconductor layer including a light emitting portion and a transparent semiconductor layer are sequentially stacked, and then the semiconductor substrate is removed, and then a first electrode and a current diffusion layer are formed on the surface of the semiconductor layer on the side from which the semiconductor substrate is removed. In the manufacturing method, the second electrode is formed on the surface of the transparent semiconductor layer or the second conductivity type semiconductor layer. The semiconductor substrate used here is preferably a GaAs substrate, and the GaAs substrate is a semiconductor that generally serves as an absorption layer for green to red light emission from the AlGaInP light emitting portion.
  Therefore, in the manufacturing method of the present invention, an epitaxial growth layer is formed on a high-quality GaAs substrate, and then a method of removing the GaAs substrate that becomes the light absorption layer is adopted.
[0017]
In the method for manufacturing a semiconductor light emitting device of the present invention, a light emitting portion made of AlGaInP is epitaxially grown. As a means for epitaxial growth, a metal organic chemical vapor deposition method (MOCVD method) was adopted. According to the MOCVD method, it is easy to control the composition, layer thickness, and electrical properties of the growth layer.
In the method for producing a semiconductor light emitting device of the present invention, the transparent semiconductor layer can be laminated by a vapor phase epitaxial growth method (VPE method).
Since the VPE method can increase the growth rate compared to the MOCVD method, a thick transparent semiconductor layer can be formed efficiently.
[0018]
  The light-emitting diode lamp of the present invention includes a base material, first and second electrode terminals formed on the base material so as to be electrically isolated from each other, and current diffusion layers on the first and second electrode terminals, respectively. And the second electrode is electrically connected.8A light-emitting diode lamp comprising the flip-chip type semiconductor light-emitting device according to any one of the above and a sealing material for sealing the semiconductor light-emitting device.
  In the light-emitting diode lamp of the present invention, it is preferable that the first and second electrode terminals are formed on the same plane of the substrate surface, and the semiconductor light-emitting element is placed on the plane of the substrate. .
  Further, it is preferable that the first and second electrode terminals are electrically connected to the current diffusion layer and the second electrode by bumps made of gold or solder.
  With such a structure, since two electrodes are provided on one surface of the semiconductor light emitting element, the semiconductor light emitting element is merely placed at a predetermined position of the electrode terminal on the electronic device, and wire bonding is not used. It is possible to assemble a light emitting diode lamp. In addition, if an electrode terminal is extended on the surface opposite to the surface on which the semiconductor light-emitting element is mounted on the base material, the light-emitting diode lamp can be connected simply by placing it at a predetermined position when mounting it on other electronic devices. Wiring becomes possible.
[0019]
The display device of the present invention is a display device using the above-described light emitting diode lamp according to the present invention. If the light emitting diode lamp according to the present invention is used, since the connection terminals are arranged on one side, the mounting operation becomes extremely easy and the production efficiency is greatly improved.
[0020]
The electrode for a flip-chip type light emitting element of the present invention is formed by dispersing a part of the surface of the semiconductor layer having a light emitting portion, the first electrode being in ohmic contact with the semiconductor layer, and the surface of the semiconductor layer In addition, an electrode for a light-emitting element comprising the semiconductor layer and a current diffusion layer formed so as to cover the first electrode.
In the electrode for a light emitting device of the present invention, the current diffusion layer preferably also serves as a reflective layer that reflects light emitted from the light emitting portion.
Furthermore, it is preferable that a plurality of the first electrodes are arranged on the surface of the semiconductor layer.
With such an electrode structure, since the current spreads over the entire light emitting surface through the current diffusion layer, there is an advantage that uniform light emission can be obtained over the entire light emitting surface and luminance can be improved. In addition, since the current diffusion layer also serves as a light reflection layer, the luminance can be further improved.
[0021]
In the light-emitting element electrode according to the present invention, it is preferable that the contact resistance between the first electrode and the semiconductor layer is smaller than the contact resistance between the current diffusion layer and the semiconductor layer.
By configuring the electrodes in this way, there is an advantage that the operating current can be spread over the entire semiconductor light emitting device as described above.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2 are diagrams schematically showing a schematic configuration of a flip chip type semiconductor light emitting device of the present invention, FIG. 1 is a plan view thereof, and FIG. 2 is a cross section taken along line AA ′ of FIG. FIG.
In the following drawings, the scale of each layer and each member in each direction is changed in order to display each layer and each member with a size that can be recognized on the drawing.
[0023]
As shown in FIG. 1, the planar structure of the semiconductor light emitting device of the present invention is such that a second electrode 16 having a quarter circle shape is formed at one corner of the surface of the square semiconductor light emitting device 10, and four circles are formed in the remaining range. The first electrodes (distribution electrodes) 15 are formed in a distributed manner. Both the first electrode 15 and the second electrode 16 are formed so as to form an ohmic junction with the lower semiconductor layer, and the first electrode 15 and the second electrode 16 are electrically isolated from each other. ing.
Further, the cross-sectional structure of the semiconductor light emitting device 10 of the present invention is a laminated structure including a first conductive type semiconductor layer and a second conductive type semiconductor layer having the light emitting part 12 on one surface of the transparent semiconductor layer 135 as shown in FIG. A semiconductor layer 13 made of a structure is formed, and a second electrode 16 that forms an ohmic junction is formed on the same surface of the transparent semiconductor layer 135. Further, a first electrode (distribution electrode) 15 that makes ohmic contact is formed on the surface of the semiconductor layer 13 opposite to the surface in contact with the transparent semiconductor layer 135. A current diffusion layer 14 is formed so as to cover the entire surface of the semiconductor layer 13 including the semiconductor layer 13. Note that the current diffusion layer 14 and the second electrode 16 are electrically separated. In the semiconductor light emitting device of the present invention, the light extraction direction is the direction of the transparent semiconductor layer 135.
[0024]
The semiconductor layer 13 is composed of a stacked body of semiconductor epitaxial growth layers including the light emitting portion 12. In addition to the light emitting unit 12, the semiconductor layer 13 can include a buffer layer, a contact layer, a protective layer, and the like. The light emitting section 12 is not particularly limited as long as it includes a light emitting structure composed of a pn junction, but an AlGaInP quaternary mixed crystal semiconductor having a wide emission wavelength adjustment range and high emission luminance is preferably used. In particular, if a double heterojunction structure (DH) of an AlGaInP quaternary mixed crystal semiconductor is used as a light emitting part, the light emission output is high because it is a direct transition type semiconductor, and the emission wavelength can be increased by changing the Al mixed crystal ratio. There is an advantage that can be changed. Further, by changing the mixed crystal ratio of Al and Ga, it is easy to achieve lattice matching with different semiconductor crystal substrates, and there is an advantage that an epitaxially grown layer having good crystallinity can be obtained.
[0025]
The light emitting portion made of an AlGaInP double heterojunction includes, for example, a buffer layer made of n-type GaAs doped with Si, a contact layer made of Si-doped n-type AlGaAs or AlGaInP, and a Si-doped n-type (Al_0.7Ga_0.3)_0.In_0.5Lower cladding layer made of P, undoped (Al_0.2Ga_0.8)_0.5In_0.5A light-emitting layer made of P, and p-type (Al_0.7Ga_0.3)_0.5In_0.5A structure in which upper clad layers made of P are sequentially laminated can be exemplified. According to this configuration, red light emission having a wavelength of about 620 nm can be obtained.
[0026]
The semiconductor light emitting device 10 of the present invention has a light emitting portion formed on a semiconductor substrate, as will be described in detail later. If a very general GaAs substrate is used as the semiconductor substrate, it can be easily lattice-matched with the AlGaInP epitaxial layer, and an AlGaInP epitaxial layer having excellent crystallinity can be obtained.
However, since the GaAs substrate acts as an absorption layer for the light emission from the AlGaInP light emitting part, the light emitted to the GaAs substrate side cannot be effectively extracted outside with the GaAs substrate remaining, and the luminance Can not increase.
[0027]
Therefore, in the present invention, a light emitting portion made of, for example, an AlGaInP double heterojunction is formed on a GaAs substrate, and a transparent semiconductor layer transparent to the light emission of AlGaInP is formed thereon thickly. The opaque GaAs substrate is removed, and the semiconductor layer 13 is maintained using the transparent semiconductor layer 135 that is transparent to the light emission of AlGaInP as a support layer. Thereafter, a part of the semiconductor layer 13 is removed by etching, and the second electrode 16 that forms an ohmic junction with the transparent semiconductor layer 135 is formed on a part of the surface of the exposed transparent semiconductor layer 135. When a part of the semiconductor layer 13 is removed by etching, a part of the epitaxially grown layer of the semiconductor layer 13, for example, a cladding layer is left without removing the transparent semiconductor layer 135, and the second electrode 16 is provided on the epitaxially grown layer. May be.
A first electrode 15 having an ohmic junction is formed on the surface in contact with the etched GaAs substrate, and the entire surface of the semiconductor layer 13 including the first electrode 15 is covered with a current diffusion layer 14. .
At this time, if the electrical resistance of the transparent semiconductor layer is high, the current path from the light emitting portion to the second electrode 16 is limited to the thin film on the transparent semiconductor layer side of the semiconductor layer 13, so that the circuit resistance becomes high, and as a result, the forward direction. This is not preferable because the voltage becomes high. Therefore, a low resistance semiconductor layer having a high carrier concentration and a low specific resistance is used for the transparent semiconductor layer. The carrier concentration of the transparent semiconductor layer 135 is 2 × 10.¹⁶cm^-3It is preferable to use the above, and the specific resistance at this time is 10^-FiveIt becomes about Ωcm or less.
In the present invention, the first conductivity type is preferably n-type, and the second conductivity type is preferably p-type. This is because the n-type electrode generally has a lower resistance.
[0028]
As the semiconductor layer that is transparent to light emission, a compound semiconductor layer such as GaP, AlGaAs, GaAsP, ZnTe, or ZnSe that generally has a larger forbidden band than the light emitting layer can be selected.
When an AlInGaP quaternary mixed crystal semiconductor is used for the light emitting portion, the material of the transparent semiconductor layer 135 that is transparent to such light emission and has good conductivity is, for example, from the viewpoint of growth cost, stability, and moisture resistance. GaP is mentioned as the most preferable material. The conductivity type of the transparent semiconductor layer 135 is the same as the conductivity type of the semiconductor layer of the light emitting portion in contact therewith, and the carrier concentration is 2 × 10.¹⁶cm^-3The above is preferable. Considering that it is easy to form an ohmic junction of the second electrode, the carrier concentration of the transparent semiconductor layer 135 is desirably 1 × 10 6.¹⁷cm^-3The above is necessary. On the other hand, the carrier concentration of the transparent semiconductor layer 135 is 1 × 10 6 because the crystallinity may be lowered if the carrier concentration is too high depending on the combination of the semiconductor material and the dopant.¹⁹cm^-3Hereinafter, in view of completely eliminating light absorption by the dopant, 2 × 10 in the case of p-type¹⁸cm^-3Hereinafter, in the case of n-type, 6 × 10¹⁷cm^-3The following is particularly desirable:
As thickness of the transparent semiconductor layer 135, 50-100 micrometers is suitable. Since the thickness of the semiconductor layer 13 supported by the transparent semiconductor layer 135 is at most about 4 to 10 μm, the thickness of the transparent semiconductor layer 135 is almost the entire thickness of the semiconductor light emitting device 10.
[0029]
FIG. 3 shows the relationship between the thickness of the semiconductor element 10 and the defect rate of the element. From the figure, it is difficult to handle when the thickness of the semiconductor element 10 is 50 μm or less, and the defect rate in the process of manufacturing the semiconductor light emitting element is remarkably increased. Further, when the thickness is thick, the warp after the epitaxial growth of the transparent semiconductor layer 135 is large, and it is difficult to process the semiconductor light emitting device (chip) from the epitaxial wafer state, and there is a tendency that the defects slightly increase. In view of the cost of epitaxial growth, the thickness of the semiconductor element 10, that is, the thickness of the transparent semiconductor layer 135 is preferably 100 μm or less.
[0030]
As shown in FIG. 1, the first electrodes (distribution electrodes) 15 are preferably distributed evenly on the light emitting surface. For example, as shown in FIG. 1, the plurality of first electrodes 15 are equally arranged. Alternatively, non-independent radial, donut, spiral, frame, lattice, or branch electrodes may be evenly distributed on the light emitting surface. Forming the first electrode in a dispersed manner on the surface of the semiconductor layer means that the electrode is disposed on the surface of the element without deviation so that the operating current of the light emitting element spreads over the entire surface of the element. The contact resistance between the first electrode 15 and the light emitting surface differs depending on the combination of the type of metal used as the electrode and the type of semiconductor crystal to be joined, and the area of the first electrode 15. The contact resistance with 13 is preferably about 50Ω or less. If the area of the first electrode 15 is too small, the contact resistance increases and the forward voltage (Vf) of the light emitting element increases. Therefore, the total area of the first electrode 15 is preferably 2% or more of the area of the light emitting surface. On the other hand, if the area of the first electrode 15 is too large, the light emitted from the light emitting portion is absorbed by the metal layer formed as the first electrode 15 and cannot be extracted outside, and the light emission intensity decreases. Therefore, the area of the first electrode 15 is desirably 30% or less of the area of the light emitting surface.
The material of the first electrode 15 is AuZn alloy or AuBe alloy when the outermost surface layer of the semiconductor layer 13 forming the first electrode 15 is a p-type layer, and AuGeNi alloy or AuSi when it is an n-type layer. Known techniques such as alloys can be applied.
The thickness of the first electrode 15 is suitably about 0.2 to 1.0 μm, and after forming a metal thin film by vapor deposition or sputtering, it is patterned into a predetermined shape.
[0031]
In order to supply input power from the external electric circuit to the first electrodes 15 that are dispersedly arranged, the current diffusion layer 14 covers the entire surface of the semiconductor layer 13 including the first electrodes 15 so as to connect the first electrodes 15. cover.
As the current diffusion layer 14, an oxide conductive film such as indium tin oxide or zinc oxide, or a conductive thin film such as a metal thin film can be used. In the case of an oxide conductive film, wiring is further provided on the current diffusion layer. It is necessary to form a metal electrode for connecting the two. From this point, it is most desirable to use a current diffusion layer made of a metal thin film having a simple structure and formation method.
The region where the current diffusion layer 14 is formed may be partial because the first electrode 15 is covered so as to perform a connection function between the electrodes. However, since the light reflection effect described later can be used, it is advantageous for high luminance. It is desirable to form the entire surface of the semiconductor layer 13.
[0032]
In the semiconductor light emitting device 10 having the above configuration, when the first electrode (distribution electrode) 15 that makes ohmic contact is provided on a part of the surface of the semiconductor layer 13, the electrical resistance between the current diffusion layer 14 and the semiconductor layer 13 is reduced. In comparison, since the electrical resistance between the first electrode 15 and the semiconductor layer 13 is significantly small, the drive current supplied from the current diffusion layer 14 is mostly current diffusion layer 14 having a lower electrical resistance. → The first electrode 15 → the semiconductor layer 13 (→ the light emitting part 12) → the second electrode 16 flows. Therefore, it is possible to cause the light emitting unit 12 to emit light around the first electrode 15. Since the first electrode 15 is distributed over the entire surface of the semiconductor layer 13, light is emitted from the entire surface of the semiconductor layer 13 to achieve high luminance.
[0033]
Furthermore, the metal thin film used as the current diffusion layer also has a function as a light reflection film. In regions other than the first electrode 15, the current diffusion layer 14 made of a metal thin film reflects light from the light emitting unit 12 and rebounds toward the transparent semiconductor layer 135, and light from the surface also passes through the transparent semiconductor layer 135. The emission efficiency can be greatly improved.
Further, when the current diffusion layer 14 and the first electrode 15 are used, the light on the light extraction surface of the semiconductor layer 13 can be made uniform.
[0034]
Examples of the metal used as the current spreading layer 14 include gold (Au), silver (Ag), aluminum (Al), nickel (Ni), zinc (Zn), chromium (Cr), platinum (Pt), or Metals that reflect light well, such as titanium (Ti), tantalum (Ta), or alloys of these metals, and that have good electrical conductivity can be used. Among metals, gold and gold alloys that hardly corrode, and metals having good adhesion to semiconductors, that is, refractory metals are desirable, and for example, chromium, platinum, or titanium is particularly preferable. By making use of the advantages of these metals and forming a multilayer film, a more stable current diffusion layer can be formed.
When the light emitting elements are connected by solder or the like, an alloy such as solder can also be used as the current diffusion layer.
[0035]
The thickness of the current spreading layer 14 is suitably about 0.5 μm to 3 μm. This is because the electric resistance is low and the light is sufficiently reflected.
If the thickness of the current diffusion layer 14 is thinner than 0.5 μm, the electric resistance is high, and current spreading is insufficient. On the other hand, even if the thickness of the current diffusion layer 14 is made too thick, the effect is not improved for the time required for film formation.
[0036]
Next, the second electrode 16 will be described.
The second electrode 16 is formed on the surface of the second conductive type transparent semiconductor layer 135 or the surface of the second conductive type layer in contact with the transparent semiconductor layer 135 of the semiconductor layer 13. The second electrode 16 also forms an ohmic junction with the second conductive type semiconductor layer. For example, in the case where the semiconductor layer has a light emitting part structure having a double hetero structure, the second electrode 16 may be formed on a part of the cladding layer having the second conductivity type.
Examples of the material used as the second electrode 16 include an AuZn alloy and an AuBe alloy when the semiconductor layer forming the second electrode 16 is a p-type layer, and an AuGeNi alloy or an AuSi alloy when the semiconductor layer is an n-type layer. The known techniques can be applied.
Since the second electrode 16 serves as one electrode for supplying electric power from the outside, an area where the contact resistance is about 50Ω or less may be secured in a part of the transparent semiconductor layer 135. For example, as shown in FIG. 1, it is provided in a sector shape at the corner portion of the element so as to ensure the area of the light emitting portion region as wide as possible.
[0037]
If the thickness of the second electrode 16 is usually 0.2 to 1.0 μm, an electrical contact can be formed. However, in the present invention, the first electrode 15 and the second electrode 16 are formed on the same surface of the support substrate. In order to form both, it is formed a little thicker. Considering the case where the semiconductor light emitting element is mounted on another electronic component, it is necessary to bring the surfaces of the first electrode 15 and the second electrode 16 close to the same level. The thickness is about 2 to 6 μm. For this reason, the second electrode is formed by forming the metal film slightly thicker using vapor deposition or the like and patterning it into a predetermined shape.
[0038]
The first electrode 15 is formed on one surface of the semiconductor layer 13, and the thickness of the semiconductor layer 13 is at most 2 to 5 μm. Therefore, in the example of FIG. 2, the height (h1) of the surface of the first electrode 15 is at most 6 μm from the surface of the transparent semiconductor layer 135.
Therefore, if the height (h2) of the surface of the second electrode 16 is also set to a position of about 6 μm from the surface of the transparent semiconductor layer 135, the surfaces of both electrodes become substantially the same level. convenient.
When the level difference (d) between the first electrode 15 and the second electrode 16 becomes large, it causes connection failure during mounting.
[0039]
FIG. 4 shows the relationship between the level difference (d) between the surface of the first electrode 15 and the surface of the second electrode 16 and the product defect rate. As shown in FIG. 4, when the level difference (d) between the two electrodes is 4 μm or less, the defect rate during assembly such as disconnection due to a step difference in height between the first and second electrodes and poor contact is significantly reduced.
In order to reduce the level difference (d) between the surface of the first electrode 15 and the surface of the second electrode 16, the thickness of the semiconductor layer 13 is reduced, or the thickness of the second electrode 16 is increased. Means can be used.
In order to reduce the thickness of the semiconductor layer 13, it is necessary to control the thickness of each layer when the semiconductor layer 13 is formed. In terms of thickness control, the liquid phase epitaxial growth method is a thin film of 4 μm or less. It is difficult to control the thickness. In contrast, the vapor phase epitaxial growth method (VPE) can be controlled even with a film thickness of 4 μm or less, but the material that can be grown is limited, and a high-luminance light emitting portion cannot be formed. The MOCVD method is optimal as a method for forming a light emitting portion with high luminous efficiency such as the control of film thickness and AlInGaP having a DH structure.
[0040]
On the other hand, in order to form the second electrode 16 thick, it is suitable to use a vacuum deposition method. According to the vacuum evaporation method, film formation on the order of μm can be relatively easily performed.
Of course, means for adjusting both the surface of the first electrode 15 and the surface of the second electrode 16 may be used in combination. By making full use of these means and setting the level difference (d) between the surface of the first electrode 15 and the surface of the second electrode 16 to 4 μm or less, the product defect rate in the mounting process can be kept low. .
[0041]
The semiconductor light emitting device thus completed has a light emitting part and one electrode on one side of a thick semiconductor layer transparent to the emission wavelength, and the other electrode on the surface of the light emitting part. In the mounting operation, connection wiring is possible without using wire bonding simply by placing the light emitting element at a predetermined position. In addition, since the electrode provided in the light emitting part is composed of an electrode that forms an ohmic junction with the light emitting layer and a current diffusion layer that connects these ohmic electrodes, the input power spreads over the entire light emitting part, and the area of the light emitting region Therefore, high brightness can be obtained. Furthermore, since the current diffusion layer also has a light reflection function, the light emitted to the current diffusion layer side is also reflected and returned to the transparent semiconductor layer side, and most of the light excited by the light emitting part is a transparent semiconductor. Since the light is radiated from the layer side to the outside, a semiconductor light emitting device with still higher luminance can be obtained.
[0042]
Next, the structure of the light emitting diode lamp will be described.
FIG. 5 shows a planar structure of the light-emitting diode lamp of the present invention, and FIG. 6 shows a cross-sectional structure taken along line B-B ′ of FIG.
The light emitting diode lamp 40 of the present invention is manufactured as follows using the flip chip type semiconductor light emitting device 10 according to the present invention.
First, a base material 45 on which first electrode terminals 43 and second electrode terminals 44 are formed using a conductive paste or copper foil, for example, is prepared at predetermined positions on the front and back surfaces of a synthetic resin plate or the like. The first electrode terminal 43 and the second electrode terminal 44 are electrically isolated from each other and are formed from the front surface to the back surface of a synthetic resin plate or the like. As shown in FIG. 5, the first electrode terminal 43 is formed to have a width corresponding to the diagonal line of the square semiconductor light emitting element 10. The second electrode terminal 44 is formed in the width of the sector-shaped second electrode 16 of the semiconductor light emitting element 10.
[0043]
Formed on the first electrode terminal 43 and the second electrode terminal 44 formed on the base material 45 is a bump 46 made of gold, solder, or the like, which is normally used in flip chip type assembly. To do. Then, one of the semiconductor light emitting elements 10 according to the present invention is superposed on the base material 45, and the current diffusion layer 14 and the second electrode 16 of the semiconductor light emitting element 10 are brought into contact with the bumps 46 to be connected by pressure bonding. . Finally, the periphery of the semiconductor light emitting device 10 is sealed with a sealing material 41 such as a transparent epoxy resin or silicon resin to obtain the light emitting diode lamp 40 shown in FIG.
[0044]
If the light-emitting diode lamp 40 is configured as described above, when the light-emitting diode lamp 40 is mounted on another electronic device to produce a display device, the first electrode terminal 43 formed on the back side of the base material 45 and By simply superimposing the second electrode terminal 44 on the terminal 47 of another electronic device, the surface mounting work can be performed, so that the mounting work efficiency can be improved, and a display device that is inexpensive and has few failures can be manufactured. it can.
[0045]
【Example】
(Example)
In this example, a flip-chip type semiconductor light emitting device according to the present invention and a light emitting diode lamp using the flip chip type semiconductor light emitting device were manufactured.
The semiconductor light emitting device (LED) fabricated in this example is an undoped (Al_0.2 Ga_0.8)_0.5In_0.5 The LED has a light emitting layer made of P and emits red light having a wavelength of about 620 nm.
[0046]
First, the laminated structure of the semiconductor epitaxial wafer 20 will be described with reference to FIG. FIG. 7 is a detailed sectional view showing a laminated structure of the semiconductor epitaxial wafer 20 used in the semiconductor light emitting device of the present invention.
A buffer layer 130 made of n-type GaAs doped with Si and a contact layer made of n-type AlGaAs doped with Si on a semiconductor substrate 11 made of GaAs single crystal having an n-type (001) plane doped with Si. 131, Si-doped n-type (Al_0.7Ga_0.3)_0.5In_0.5Lower cladding layer 132 made of P, undoped (Al_0.2Ga_0.8)_0.5In_0.5Light-emitting layer 133 made of P, Zn-doped p-type (Al_0.7Ga_0.3)_0.5In_0.5The epitaxial wafer 20 is configured by sequentially laminating an upper cladding layer 134 made of P and a transparent semiconductor layer 135 made of p-type GaP doped with Zn. The light emitting portion 12 of the epitaxial wafer has a double heterojunction structure including a lower cladding layer 132, a light emitting layer 133, and an upper cladding layer 134. Therefore, the semiconductor crystal of the light emitting portion 12 is made of AlGaInP quaternary mixed crystal.
[0047]
(Epitaxial wafer manufacturing process)
The manufacturing method of this epitaxial wafer will be described. In this example, first, trimethylaluminum ((CH_Three)_ThreeAl), trimethylgallium ((CH_Three)_ThreeGa) and trimethylindium ((CH_Three)_ThreeIn) is used as a raw material for group III constituent elements, and the raw material for group V constituent elements is phosphine (PH_Three ) Or arsine (AsH)_ThreeThe semiconductor layers 130 to 134 are stacked on the semiconductor substrate 11 made of GaAs by a low pressure metal organic chemical vapor deposition method (MOCVD method), and then vapor phase epitaxial growth is performed thereon. The epitaxial wafer 20 was formed by growing the transparent semiconductor layer 135 made of GaP thick by the method (VPE method). Diethyl zinc ((C₂H_Five)₂ Zn) was used. Disilane (Si₂H₆)It was used. The lamination temperature of each layer constituting the epitaxial wafer 20 in the MOCVD method and the VPE method was unified to 700 ° C.
[0048]
The carrier concentration of the buffer layer 130 made of GaAs is about 5 × 10 5.¹⁸cm^-3The layer thickness was about 0.2 μm. The contact layer 131 is formed by laminating an AlGaAs thin film having an Al mixed crystal ratio of 0.4 and a carrier concentration of about 3 × 10 6.¹⁸cm^-3The layer thickness was about 0.8 μm. The carrier concentration of the lower cladding layer 132 made of AlInGaP is about 1 × 10 6.¹⁸cm^-3The layer thickness was about 1 μm. The thickness of the light emitting layer 133 made of AlInGaP is about 0.5 μm, and the carrier concentration is about 5 × 10.¹⁶cm^-3It was. Furthermore, the carrier concentration of the upper cladding layer 134 made of AlInGaP is about 2 × 10 10.¹⁷cm^-3The layer thickness was 1.5 μm. As a result, the total thickness of the epitaxially grown semiconductor layer 13 was about 4 μm.
The GaP transparent semiconductor layer 135 serving as a support in place of the semiconductor substrate 11 made of GaAs has a layer thickness of 70 μm and a carrier concentration of about 8 × 10.¹⁷cm^-3It was.
[0049]
(Substrate removal process)
Next, the semiconductor substrate 11 made of GaAs opaque to the emission wavelength and the buffer layer 130 made of GaAs were entirely removed by chemical etching. Further, a part of the contact layer 131 in the remaining semiconductor layer 13 was also removed by selective etching as indicated by a chain line X-X ′ in FIG.
[0050]
(Electrode formation process)
Next, in order to form the first electrode 15 which is an n-type ohmic electrode on the exposed surface of the contact layer 131, a thin film made of an Au / Ge alloy is formed by vacuum vapor deposition so that the thickness becomes 0.3 μm. did. Patterning was performed using a general photolithography means, and four circular first electrodes 15 having a diameter of 30 μm were formed as shown in FIG. The total area of the first electrode with respect to the area of the light emitting surface was about 3.6%.
On the surface of the first electrode 15 and the surface of the contact layer 131, a current diffusion layer 14 was formed by vacuum deposition of Cr with a thickness of 0.1 μm and gold with a thickness of about 1 μm. Next, patterning is performed to remove the current diffusion layer 14 and the semiconductor layer 13 in the region indicated by the chain line YY ′ in FIG. 7, so that a second electrode can be formed. One side of the transparent semiconductor layer 135 has a side of 130 μm. The fan-shaped area was exposed.
[0051]
Next, in order to form the second electrode 16, first, a gold / zinc alloy film having a thickness of 0.5 μm and a gold thin film having a thickness of 2 μm are formed on the transparent semiconductor layer 135 and the resist surface of the patterning. The entire surface was deposited by a general vacuum deposition method. Subsequently, the resist was removed by a known lift-off method to form a fan-shaped second electrode 16 having a radius of 125 μm as shown in FIG.
Next, after forming the first and second electrodes, an alloying heat treatment is performed at 420 ° C. for 15 minutes in an argon (Ar) stream, and the first and second electrodes and each semiconductor layer are subjected to heat treatment. Formed ohmic contact.
[0052]
(LED manufacturing process)
As described above, the epitaxial wafer on which the first electrode 15 and the second electrode 16 and the current diffusion layer 14 made of the metal multilayer film are formed is cut into the shape of the element by a normal scribing method and individually divided. A semiconductor light emitting device was obtained. The flip-chip type semiconductor light emitting device thus obtained was a square having a side of 300 μm as viewed in plan as shown in FIG. 1 and a thickness of 74 μm.
[0053]
(Light-emitting diode lamp assembly process)
Furthermore, a light emitting diode lamp shown in FIGS. 5 and 6 was assembled using the semiconductor light emitting element 10.
First, the base material 45 which formed the 1st electrode terminal 43 and the 2nd electrode terminal 44 in the predetermined position of the front and back of a synthetic resin board using the electrically conductive paste was prepared. The first electrode terminal 43 and the second electrode terminal 44 are electrically isolated from each other and are formed from the front surface to the back surface of the synthetic resin plate. As shown in FIG. 5, the first electrode terminal 43 was formed to have a width corresponding to the diagonal line of the square semiconductor light emitting element 10. Further, the second electrode terminal 44 was formed in the width of the sector-shaped second electrode 16 of the semiconductor light emitting element 10.
Bumps 46 made of gold were formed on the first electrode terminal 43 and the second electrode terminal 44 formed on the substrate 45. One of the semiconductor light emitting elements 10 was superposed on the base material 45, and the current diffusion layer 14 of the semiconductor light emitting element 10 and the second electric electrode 16 were brought into contact with the bumps 46 and connected by pressure bonding. Finally, the periphery of the semiconductor light emitting device 10 was sealed with a sealing material 41 made of a transparent epoxy resin, and the light emitting diode lamp 40 shown in FIGS. 5 and 6 was completed.
[0054]
When a current was applied in the forward direction to the first electrode terminal 43 and the second electrode terminal 44 of the light emitting diode lamp 40 produced as described above, red light having a wavelength of about 620 nm was emitted from the light emitting layer. . A part of the emitted light was reflected by the current diffusion layer 14 made of a metal film and emitted to the outside through the surface and side surfaces of the transparent semiconductor layer 135. Reflecting the good ohmic characteristics of the first electrode, the forward voltage (V) when a current of 20 mA is passed in the forward direction._f: Per 20 mA) was about 2.0V. The light emission intensity at this time was as high as 150 mcd, reflecting the high light emission efficiency of the light emitting part and the improvement of the external extraction efficiency.
[0055]
(Comparative Example 1)
The flip-chip type semiconductor light emitting device according to the comparative example 1 is structurally different from the above example in that only one first electrode is formed larger and no metal current diffusion layer is used. Is a point. Therefore, the point using the epitaxial wafer shown in FIG. 7 is the same as that of the Example. The semiconductor light emitting device of Comparative Example 1 was a semiconductor light emitting device having a square of 300 μm on a side and a thickness of 74 μm. The structure of the semiconductor light emitting device fabricated in this Comparative Example 1 is shown in FIGS. FIG. 8 is a plan view of the semiconductor light emitting device manufactured in the first comparative example, and FIG. 9 is a cross-sectional view taken along line C-C ′ in FIG. 8. The portions indicated by reference numerals 22, 25, 26, and 235 in FIGS. 8 and 9 correspond to the portions indicated by reference numerals 12, 15, 16, and 135 in FIGS.
[0056]
In the first comparative example, the shape of the first electrode 25 formed on the contact layer 131 is different from that of the previous example. That is, in the first comparative example, in order to obtain a necessary area for connection with the gold bump, the first electrode 25 is formed in a circular shape having a diameter of 130 μm, and only one is formed.
As the first electrode 25, an n-type ohmic electrode made of an Au / Ge alloy was formed to a thickness of 0.3 μm, and a gold thin film was formed thereon to a thickness of 1 μm by vacuum deposition. . Patterning was performed using general photolithography means to form a circular first electrode 25 having a diameter of 130 μm as shown in FIG. The area ratio of the first electrode to the area of the light emitting surface is about 33%.
[0057]
Thereafter, a light-emitting diode lamp was manufactured in the same manner as in the example, and a current was passed in the forward direction between the first electrode terminal and the second electrode terminal of the light-emitting diode lamp. Thus, red light having a wavelength of about 620 nm was emitted. The forward voltage (V) when a current of 20 mA (mA) flows in the forward direction._f: Per 20 mA) was about 2.1 volts (V), which was equivalent to the example. The emission intensity at this time was 90 mcd. The emission intensity was about 60% with respect to the example of the present invention. This is because there is no current diffusion layer, the current flowing to the light emitting part is non-uniform, the light emission efficiency of the entire light emitting part is reduced, and the light is lost because there is no reflection of light from the current spreading layer, This is because the electrode area of the first electrode 25 is large and the light absorption at the interface between the electrode and the semiconductor layer is increased, so that the extraction efficiency to the outside is also reduced.
[0058]
(Comparative Example 2)
In Comparative Example 2, a semiconductor light emitting device having a light emitting area the same as that of the example was manufactured using an epitaxial wafer on which a semiconductor layer having the structure shown in FIG. 10 was formed.
The difference from the embodiment is that the transparent semiconductor layer 335 is a p-type high resistance GaP layer. The carrier concentration of the transparent semiconductor layer 335 is about 8 × 10.¹⁵cm^-3The layer thickness was 70 μm. The total thickness of the semiconductor layer 33 is about 4 μm.
[0059]
The method for fabricating the semiconductor light emitting device fabricated in Comparative Example 2 is different from that in the embodiment. The semiconductor layer 33 is etched away to the upper cladding layer 334 along the line YY ′ in FIG. A second electrode was formed on the surface. Other structures are the same as those shown in FIGS. Therefore, the parts indicated by reference numerals 31, 32, 33, 330, 331, 332, 333, and 334 in FIG. 10 are the parts indicated by reference numerals 11, 12, 13, 130, 131, 132, 133, and 134 in FIG. And corresponding.
In this comparative example 2, the transparent semiconductor layer 335 is p-type GaP with low resistance and high resistance, which is different from the example.
Thereafter, in the same manner as in the example, the epitaxial wafer on which the first electrode, the current diffusion layer, and the second electrode are formed is cut into element shapes by a normal scribing method, and is individually subdivided. An LED was assembled in the same manner.
[0060]
As in the example, when a forward current was passed between the first and second electrode terminals, the forward voltage at 20 mA energization was 3.5V. Compared to the embodiment, the forward voltage is high. This is because the resistance of the transparent semiconductor layer 335 is high, and most of the current flows through the thin upper cladding layer 334, so that the resistance is high. Further, the light emission intensity of the LED of Comparative Example 2 was 105 mcd, and the light emission state in the device was non-uniform. This is because not only the resistance in the semiconductor layer is high and the current flow in the light emitting portion is not uniform, but also the power consumption is large and the efficiency of the light emitting portion is reduced.
[0061]
【The invention's effect】
As described above, in the flip-chip type semiconductor light emitting device of the present invention, since wire bonding is not used, the assembly of the light emitting device is easy, the wire is not disconnected, and the reliability is improved. Furthermore, by providing the ohmic electrode and the current diffusion layer on a part of the rear surface of the light emitting part of the semiconductor layer, a current can be supplied uniformly to the light emitting part, and the efficiency of the entire light emitting part is increased and the light emission intensity is increased.
[0062]
In addition, the current spreading layer reflects the light of the light emitting part to increase the light extraction efficiency, increases the connectable area when the light emitting element is assembled, facilitates assembly, and has an effect of improving productivity. The transparent semiconductor layer on the surface side of the light emitting element is transparent to light emission, and has an effect of reducing power consumption by improving light emission intensity and reducing forward voltage by imparting conductivity.
The thickness of the semiconductor element greatly affects the productivity and product yield, and a low-cost element can be obtained if an appropriate range is selected.
[0063]
In this embodiment, an LED is manufactured using an n-type semiconductor substrate. However, an LED manufactured using a p-type semiconductor substrate can achieve the effects of the present invention.
In addition, although AlGaInP quaternary mixed crystal was used as the semiconductor material of the light emitting part of the LED of the embodiment, a known technique is used for the material and composition of the semiconductor crystal of the light emitting part, the laminated structure, or dopants such as Mg, Te, S, and Se. The effect of the present invention can also be obtained by using.
[0064]
In particular, the effect of the present invention is particularly effective in a semiconductor light emitting device in which the thickness of a semiconductor layer in which semiconductor layers are stacked by the MOCVD method is thin, for example, the light emitting portion is made of an AlInGaP-based, AlGaInN-based, or AlGaAs-based semiconductor large.
Although GaP is used as the conductive transparent semiconductor layer, high brightness can be achieved with AlGaAs. However, when it contains a large amount of Al, its use is limited because it has poor moisture resistance. In the embodiments, a general flip-chip type light emitting diode lamp is shown. However, the same effect can be obtained by using a so-called bullet type having a different shape or a light emitting diode lamp incorporating a plurality of light emitting elements having different emission wavelengths. . Further, an inexpensive display device with few failures can be manufactured using these light emitting diode lamps.
[0065]
In addition, to increase the brightness of semiconductor light emitting devices, surface roughening treatment improves the light extraction efficiency and forms a window layer with a lower refractive index than the semiconductor used in the light emitting part. However, if a technique used in a conventional light emitting element, such as improving the light extraction efficiency to the outside, is added, the light emission characteristics are further improved.
[Brief description of the drawings]
FIG. 1 is a plan view of a semiconductor light emitting device of the present invention.
FIG. 2 is a diagram showing a cross section taken along line A-A ′ of FIG. 1;
FIG. 3 is a diagram showing a relationship between a thickness of a semiconductor light emitting element and a defect rate.
FIG. 4 is a diagram showing a relationship between a level difference between a first electrode and a second electrode and a defect rate.
FIG. 5 is a plan view of a light-emitting diode lamp according to the present invention.
6 is a cross-sectional view taken along line B-B ′ of FIG. 5;
FIG. 7 is a view showing a cross section of an epitaxial wafer used in the semiconductor light emitting device of the present invention.
8 is a plan view of a semiconductor light emitting element according to Comparative Example 1. FIG.
FIG. 9 is a diagram showing a cross section taken along line C-C ′ of FIG. 8;
10 is a view showing a cross section of an epitaxial wafer according to Comparative Example 2. FIG.
[Explanation of symbols]
10... Semiconductor light emitting device
11, 31 ... Semiconductor substrate
12, 22 ... Light emitting part
13, 33 ... Semiconductor layer
14 ... Current diffusion layer
15, 25... First electrode
16, 26... Second electrode
40 ... Light-emitting diode lamp
41 .. Sealing material
43... First electrode terminal
44... Second electrode terminal
45 ・ ・ ・ ・ ・ Base material
46 ... Bump
130, 330 ... buffer layer
131,331 ... contact layer
132,332 ... lower cladding layer
133,333 ... Light emitting layer
134,334 ... upper cladding layer
135, 235, 335 ... Transparent semiconductor layer

Claims (16)

A transparent semiconductor layer having a second conductivity type and transparent to light emitted from the light emitting portion;
A semiconductor layer made of AlGaInP having a light emitting part having a pn junction structure, comprising a second conductive type semiconductor layer and a first conductive type semiconductor layer sequentially stacked on one surface of the transparent semiconductor layer;
A first electrode in ohmic contact with the first conductivity type semiconductor layer, formed dispersed in a part of the surface of the first conductivity type semiconductor layer opposite to the transparent semiconductor layer;
A current diffusion layer formed on the surface of the first conductive type semiconductor layer on which the first electrode is formed, covering the first conductive type semiconductor layer and the first electrode;
A second electrode formed on one surface of the transparent semiconductor layer exposed by removing a part of the semiconductor layer and electrically isolated from the current diffusion layer and in ohmic contact with the transparent semiconductor layer. With electrodes,
The current spreading layer forms a reflective layer that reflects light emitted from the light emitting unit,
A plurality of the first electrodes are disposed on the surface of the first conductivity type semiconductor layer, and the total area of the first electrodes is 2% to 30% of the surface area of the first conductivity type semiconductor layer,
The contact resistance between the first electrode and the first conductivity type semiconductor layer is smaller than the contact resistance between the current diffusion layer and the first conductivity type semiconductor layer, and the first electrode and the first conductivity type semiconductor layer. The contact resistance with is 50Ω or less,
The thickness of the first electrode is in the range of 0.2 to 1.0 μm, the thickness of the second electrode is in the range of 2 to 6 μm, the thickness of the semiconductor layer is in the range of 2 to 5 μm, The level difference between the first electrode surface and the second electrode surface is within 4 μm,
The contact resistance between the second electrode and the transparent semiconductor layer or the second conductivity type semiconductor layer is 50Ω or less, the second electrode is provided in a sector shape at the corner portion of the element, and the carrier of the transparent semiconductor layer The concentration is 2 × 10 ¹⁶ cm ⁻³ or more, the specific resistance of the transparent semiconductor layer is 1 Ωcm or less, the thickness of the transparent semiconductor layer is in the range of 50 to 100 μm, and the transparent semiconductor layer is GaP A flip-chip type semiconductor light emitting device comprising: 2. The flip-chip type semiconductor light emitting device according to claim 1, wherein the current diffusion layer is made of a metal thin film containing gold or a gold alloy. 2. The flip chip type semiconductor light emitting device according to claim 1, wherein the current diffusion layer is made of a metal thin film containing a refractory metal. 4. The flip-chip type semiconductor light emitting device according to claim 3, wherein the refractory metal is one of chromium, platinum or titanium or an alloy thereof. 5. The flip-chip type semiconductor light emitting device according to claim 1, wherein the current diffusion layer is made of a multilayer film of two or more kinds of metals. 6. The flip-chip type semiconductor light emitting device according to claim 1, wherein the current diffusion layer has a thickness of 0.5 μm to 3 μm. 7. The flip-chip type semiconductor light emitting device according to claim 1, wherein the first conductivity type is n-type and the second conductivity type is p-type. 8. The flip-chip type semiconductor light emitting device according to claim 1, wherein the total thickness of the semiconductor light emitting device is not less than 50 μm and not more than 100 μm. A semiconductor layer including a light emitting portion made of AlGaInP and a transparent semiconductor layer are sequentially stacked on a semiconductor substrate made of GaAs, then the semiconductor substrate is removed, and then the surface of the semiconductor layer on the side where the semiconductor substrate is removed is 9. The flip according to claim 1, wherein the first electrode and the current diffusion layer are formed, and the second electrode is formed on the surface of the transparent semiconductor layer or the second conductivity type semiconductor layer. A method for manufacturing a chip-type semiconductor light emitting device. The method for manufacturing a flip-chip type semiconductor light emitting element according to claim 9, wherein the semiconductor substrate is a semiconductor that functions as an absorption layer for light emission from the light emitting portion. The method of manufacturing a flip-chip type semiconductor light emitting device according to claim 9 or 10, wherein the semiconductor layer is laminated by metal organic chemical vapor deposition (MOCVD). 11. The method for manufacturing a flip-chip type semiconductor light emitting device according to claim 9, wherein the transparent semiconductor layer is laminated by a vapor phase epitaxial growth method (VPE method). A base material, first and second electrode terminals formed on the base material electrically isolated from each other, and a current diffusion layer and a second electrode electrically connected to the first and second electrode terminals, respectively. A light-emitting diode lamp comprising: the flip-chip type semiconductor light-emitting device according to any one of claims 1 to 8; and a sealing material for sealing the semiconductor light-emitting device. The light emission according to claim 13, wherein the first and second electrode terminals are formed on the same plane of the substrate surface, and the semiconductor light emitting element is placed on the plane of the substrate. Diode lamp. The light emitting diode according to claim 13 or 14, wherein the first and second electrode terminals are electrically connected to the current diffusion layer and the second electrode by bumps made of gold or solder. lamp. A display device using the light-emitting diode lamp according to claim 13.

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