JP2002151739A - Flip chip type semiconductor light emitting device, method of manufacturing the same, light emitting diode lamp, display device, and electrode for flip chip type semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flip-chip type semiconductor light emitting device and a light emitting diode lamp which are high in luminance and easy to mount and wire. SOLUTION: On one surface of a transparent semiconductor layer, there is provided a light emitting portion structure composed of a stack of semiconductor layers, and a second electrode which makes ohmic contact with the transparent semiconductor layer, and on the opposite side of the light emitting portion structure. A first electrode in ohmic contact with the semiconductor layer on the outermost surface of the light emitting unit structure, and a current diffusion layer made of a metal thin film having a reflection ability for light emission on the surface of the first electrode. A flip-chip type semiconductor light emitting device having a structure provided. The light-emitting diode lamp has a structure in which the semiconductor light-emitting element is mounted on a base material provided with electrode connection terminals by turning over the semiconductor light-emitting element and sealed with a sealing material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device and a light emitting diode lamp for extracting 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]

2. Description of the Related Art Conventionally, a semiconductor light emitting diode has generally been assembled by wire bonding a gold or aluminum thin wire to a gold or aluminum electrode on the surface of a semiconductor light emitting element. In order to improve the brightness 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. JP-A-6-302
No. 857 discloses a method of forming a light emitting structure on an opaque substrate, further forming a transparent layer, and then removing the opaque substrate. Also, JP-A-8-1
No. 30326 discloses a method in which a light emitting structure is formed on an opaque substrate, a transparent substrate is bonded to the light emitting structure, and then the opaque substrate is removed. Further, as described in JP-A-9-186365,
A technique using the reflection effect of the metal electrode on the back surface using a transparent substrate has also been proposed. In addition, a so-called flip-chip type semiconductor light emitting device has been proposed in which the wire bonding step is omitted, the productivity is excellent, and no problems such as wire breakage occur. These semiconductor light emitting devices use a thick AlGaAs semiconductor layer which is transparent to light emission formed by a liquid phase epitaxial method (Japanese Patent Application Laid-Open No. H9-1997).
-27498). In addition, a GaN-based light-emitting element often uses a transparent and insulative sapphire substrate, and a flip-chip type light-emitting element technology using a silver-white metal on the surface to improve the luminance by reflected light is disclosed. (See JP-A-11-191641).

[0003]

As described above, a flip-chip type semiconductor light emitting device having excellent productivity and reliability and having two electrodes on one side has many available materials and structures for the semiconductor light emitting device. Due to restrictions, few light emitting diodes have been put into practical use at present. recent years,
In the case of a high-brightness light-emitting diode whose light-emitting layer has been put into practical use and is based on AlGaInP, a flip-chip type semiconductor light-emitting device has not been put into practical use due to many problems. The present invention solves these problems, and provides a structure of a flip-chip type semiconductor light emitting device that can be adopted even for a high-luminance AlInGaP-based semiconductor light emitting device, and a light emitting diode lamp using the same. The first problem of the conventional flip-chip type semiconductor light-emitting device is that, except for a material that can form a transparent electrode, such as a GaN-based light-emitting device, the interface between the ohmic electrode and the semiconductor becomes a light-absorbing layer and the luminous intensity decreases. It is a point to do. The second problem is that if the distance between the light-emitting layer and the back surface is too large, the step between the first electrode and the second electrode becomes large, and a wiring problem is likely to occur. Here, the back surface is a surface (light emitting surface) from which light of the semiconductor light emitting element is extracted.
And the opposite side. A third problem is that if 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 emitting efficiency of the light emitting layer is reduced. The fourth problem is that when the thickness of the semiconductor light-emitting element is small, the mechanical strength is weak and there are many defects due to cracks in handling.

In addition, when an insulating substrate is used, there is a problem that a region where a current flows is narrow, resistance is high, a forward voltage is high, and power consumption is increased. The present invention has been proposed in view of the above problems, and can be manufactured with high productivity, has high brightness and low power consumption, and furthermore, can reduce the number of wiring steps by wire bonding to reduce the assembly cost. 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 The inventors of the present invention have studied to solve the above problems, and as a result, have limited the material used for the substrate and the thickness of the light emitting element, and have set the distance between the back surface and the light emitting layer. We have developed an element structure that does not cause a decrease in brightness due to the current diffusion layer even when approached.

[0006] In order to solve the above problems, the present invention provides a second method.
A transparent semiconductor layer having a conductivity type and transparent to light emission from the light emitting portion; and a second conductivity type semiconductor layer and a first conductivity type semiconductor layer sequentially laminated on one surface of the transparent semiconductor layer. A first semiconductor layer having a light emitting portion having a pn junction structure and a first semiconductor layer in ohmic contact with the first conductive semiconductor layer dispersedly formed on a part of the surface of the first conductive 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; and a transparent semiconductor layer or The second conductive type semiconductor layer is formed on a part of the surface on the side where the first conductive type semiconductor layer is located, is electrically separated from the current diffusion layer, and is in ohmic contact with the transparent semiconductor layer or the second conductive type semiconductor layer. Flip-chip type semiconductor light emitting device having a second electrode With the semiconductor light-emitting element having such a structure, the current applied to the semiconductor light-emitting element spreads over the entire surface of the element through the first electrode formed by being dispersed on a part of the surface of the semiconductor layer. The light emission efficiency is increased by the expansion of the light, and the light emitted in the back direction is effectively reflected by the current diffusion layer, and the emitted light can be extracted to the outside without being absorbed by the substrate. 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 operation becomes easy, and the efficiency can be improved.

In the semiconductor light emitting device of the present invention, it is preferable that the current diffusion layer forms a reflection layer for reflecting light emitted from a light emitting portion. Such a current spreading layer can be made of a metal thin film containing gold or a gold alloy.
Alternatively, it may be formed of a metal thin film containing a high melting point metal. As the high melting point metal, one of chromium, platinum, and titanium or an alloy thereof can be used. In the present invention, the current diffusion layer may be constituted by a multilayer film of two or more kinds of metals. The thickness of the current spreading layer is preferably about 0.5 μm to 3 μm. These metal thin films have a high electrical conductivity and thus have the effect of diffusing the applied current over a wide range, and also have a high light reflectance, so that they also have the function of reflecting the light emitted by the light emitting layer, allowing the light to pass from the light emitting surface. It is possible to efficiently take out to the outside.

In the semiconductor light emitting device of the present invention, it is preferable that a plurality of first electrodes are arranged on the surface of the first conductivity type semiconductor layer. The total area of the first electrodes is preferably 2% or more and 30% or less of the surface area of the first conductivity type semiconductor layer. With such a configuration, the applied current is diffused almost uniformly throughout the light emitting layer, and the light emitted in the direction of the current spreading layer can be effectively reflected without being significantly absorbed. The brightness of the semiconductor light emitting device is improved.

In the present invention, the first electrode and the first electrode
The contact resistance between the conductive type semiconductor layer and the current spreading layer
It is preferable to make the contact resistance smaller than the contact resistance with the conductive semiconductor layer. The contact resistance between the first electrode and the first conductivity type semiconductor layer is preferably set to 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 reduced from the current diffusion layer. Since the semiconductor layer flows preferentially through the first electrode to the semiconductor layer, there is an effect that the element spreads 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 conductivity type semiconductor layer,
The contact resistance between the electrode and the first conductivity type semiconductor layer becomes 50Ω or less, the current is smoothly supplied, and the visual field is sufficiently secured.

[0010] In the semiconductor light emitting device of the present invention, the level difference between the first electrode surface and the second electrode surface is determined by:
It is preferable that the thickness be within 4 μm. In the semiconductor light emitting device of the present invention, it is inevitable that a level difference occurs between the first electrode surface and the second electrode surface due to the structure and the manufacturing method. However, if the level difference is too large, a connection failure may occur in a 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 using, for example, solder bumps and the like, and the contact failure can be prevented, so that the occurrence of product failure can be prevented.

In the semiconductor light emitting device of the present invention, the transparent semiconductor layer preferably has a carrier concentration of 2 × 10 ¹⁶ cm ⁻³ or more. Preferably, the transparent semiconductor layer has a specific resistance of 1 Ωcm or less. The specific resistance of the semiconductor layer is determined by the carriers in the semiconductor layer, and the more carriers, the lower the specific resistance. Carrier concentration is 2 × 1
The use of a transparent semiconductor layer having a specific resistance of 0 ¹⁶ cm ⁻³ or more and a specific resistance of 1 Ωcm or less has an advantage that the device can be operated at a low forward voltage.

As a semiconductor layer having a high carrier concentration and a low specific resistance as described above, GaP can be used. Since GaP has a large band gap energy, AlGaIn
When P has a light-emitting portion structure, it has a property of being transparent to a wide range of emission wavelengths. GaP also has the advantage that high quality crystals can be easily obtained.

In the semiconductor light emitting device of the present invention, it is preferable that the light emitting portion is made of AlGaInP. A
Since the 1GaInP quaternary mixed crystal semiconductor is a direct transition semiconductor, it has a high emission output, and the emission wavelength can be changed by changing the mixed crystal ratio between Al and Ga. Also,
There is an advantage that lattice matching with a commercially available GaAs single crystal substrate can be easily achieved.

Further, 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. Commercially available GaAs single-crystal substrates have a n-type with fewer crystal defects and a good quality substrate can be obtained. In general, the n-type electrode has a lower resistance, and the area of the first electrode is reduced in consideration of the lamination order. This is because it can be made smaller.

In the flip-chip type semiconductor light emitting device of the present invention, the total thickness of the semiconductor light emitting device is set to 50 μm or more.
The thickness is preferably not more than 00 μm. Instead of an opaque semiconductor substrate, a transparent, low-resistance semiconductor layer is used as a support layer.If the transparent, low-resistance semiconductor layer is formed thick and the overall thickness is increased, a transparent support layer can be obtained. It is also convenient when assembling into a light emitting diode lamp described later. However, too thick is uneconomical.

Next, in a method of manufacturing a flip-chip type semiconductor light emitting device according to the present invention, a semiconductor layer including a light emitting portion and a transparent semiconductor layer are sequentially laminated on a semiconductor substrate, and then the semiconductor substrate is removed. A first electrode and a current diffusion layer are formed on the surface of the semiconductor layer from which the substrate has been removed, and a 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
It is a semiconductor that generally acts as an absorption layer for green or red light emission from the lGaInP light emitting unit. Therefore, according to the manufacturing method of the present invention, after forming an epitaxial growth layer on a high-quality GaAs substrate, Ga
The method of removing the As substrate was adopted.

In the method for manufacturing a semiconductor light emitting device according to the present invention,
The light emitting portion made of AlGaInP was epitaxially grown. As a means for epitaxial growth, a metal organic chemical vapor deposition (MOCVD) method was employed. According to the MOCVD method, it is easy to control the composition, thickness, and electrical properties of the grown layer. Further, in the method for manufacturing a semiconductor light emitting device of the present invention, the transparent semiconductor layer may be laminated by a vapor phase epitaxial growth method (VPE method). Since the VPE method can increase the growth rate as compared with the MOCVD method, it is possible to efficiently form a thick transparent semiconductor layer.

A light emitting diode lamp according to the present invention comprises a base material, first and second electrode terminals formed on the base material so as to be electrically isolated from each other, and 19. The flip-chip type semiconductor light emitting device according to claim 1, wherein the current diffusion layer and the second electrode are electrically connected to each other, and a sealing material for sealing the semiconductor light emitting device. Light emitting diode lamp.
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 on the surface of the base material, and the semiconductor light-emitting element is placed on the flat surface of the base material. . In addition, electrical connection between the first and second electrode terminals and the current diffusion layer and the second electrode,
It is preferable to use a bump made of gold or solder. According to such a structure, since two electrodes are provided on one surface of the semiconductor light emitting element, the semiconductor light emitting element is only mounted at a predetermined position of the electrode terminal on the electronic device, without using wire bonding. Thus, it is possible to assemble the light emitting diode lamp. In addition, if electrode terminals are extended on the surface opposite to the surface on which the semiconductor light emitting element is mounted on the base material, it can be connected to a light emitting diode lamp simply by placing it in a predetermined position when mounting on other electronic equipment Wiring becomes possible.

The display device of the present invention is a display device using the light emitting diode lamp according to the present invention described above. When the light emitting diode lamp according to the present invention is used, since the connection terminals are arranged on one side, the mounting operation is extremely easy, and there is an advantage that the production efficiency is greatly improved.

An electrode for a flip-chip type light emitting element according to the present invention comprises: a first electrode formed in a part of the surface of a semiconductor layer having a light emitting portion and in ohmic contact with the semiconductor layer; A light-emitting element electrode comprising a current diffusion layer formed on the surface of the semiconductor layer so as to cover the semiconductor layer and the first electrode. Further, in the electrode for a light emitting element of the present invention, it is preferable that the current diffusion layer also serves as a reflection layer that reflects light emitted from the light emitting portion. Further, 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 via the current diffusion layer, uniform light emission can be obtained over the entire light emitting surface, and there is an advantage that the luminance can be improved. Further, since the current diffusion layer also functions as a light reflection layer, the luminance can be further improved.

In the light emitting device 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 manner, there is an advantage that the operating current can be extended to the entire semiconductor light emitting device as described above.

[0022]

Embodiments of the present invention will be described below 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.
It is a figure showing the section along A '. 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 in a size that can be recognized in the drawings.

The planar structure of the semiconductor light emitting device of the present invention is as follows:
As shown in FIG. 1, at one corner of the surface of the semiconductor light emitting device 10 having a square shape, a second electrode 16 having a quarter circle shape is formed, and four circular first electrodes (distribution electrodes) 15 are formed in the remaining area. They are formed in a distributed arrangement. Both the first electrode 15 and the second electrode 16 are formed so as to form an ohmic junction with the underlying semiconductor layer, and the first electrode 15 and the second electrode 16 are electrically isolated from each other. ing. The cross-sectional structure of the semiconductor light emitting device 10 according to the present invention has a structure in which a transparent semiconductor layer 135 has a light emitting portion 12 on one surface as shown in FIG.
A semiconductor layer 13 composed of a laminated structure including a semiconductor layer of a conductivity type and a semiconductor layer of a second conductivity type is formed, and a second electrode 16 forming an ohmic junction is formed on the same surface on the transparent semiconductor layer 135. Are formed. On the surface of the semiconductor layer 13 opposite to the surface in contact with the transparent semiconductor layer 135, a first electrode (distribution electrode) 15 which makes ohmic contact is provided.
Are formed in a dispersed manner, and a current diffusion layer 14 is formed so as to cover the entire surface of the semiconductor layer 13 including the first electrode 15. 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.

The semiconductor layer 13 is composed of a stack of epitaxially grown semiconductor layers including the light emitting section 12. The semiconductor layer 13 can include a buffer layer, a contact layer, a protective layer, and the like in addition to the light emitting unit 12. The light emitting unit 12 is pn
There is no particular limitation as long as it includes a light-emitting structure consisting of a junction, but AlGa with a wide range of adjustment of emission wavelength and high emission luminance is available.
InP quaternary mixed crystal semiconductors are preferably used. In particular, Al
Double heterojunction structure of GaInP quaternary mixed crystal semiconductor (D
If the light-emitting portion is made of double hetero junction structure (DH), the light-emitting portion is a direct transition type semiconductor, so that the light-emitting output is high, and the light-emitting wavelength can be changed by changing the Al mixed crystal ratio. Also, by changing the mixed crystal ratio of Al and Ga, it is easy to obtain lattice matching with different semiconductor crystal substrates,
There is an advantage that an epitaxially grown layer having good crystallinity can be obtained.

The light-emitting portion composed of the AlGaInP double heterojunction includes, for example, a buffer layer composed of n-type GaAs doped with Si, a contact layer composed of n-type AlGaAs or AlGaInP doped with Si, and an n-type doped with Si ( Al _0.7 Ga _0.3 ) _0. Lower cladding layer made of In _0.5 P, undoped (Al _0.2 Ga _0.8 ) _0.5 I
An example is a structure in which a light-emitting layer made of n _0.5 P and an upper clad layer made of p-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P doped with Zn are sequentially stacked. According to this configuration, red light emission with a wavelength of about 620 nm can be obtained.

The semiconductor light emitting device 10 of the present invention has a light emitting portion formed on a semiconductor substrate, as described in detail later. When a very common GaAs substrate is used as a semiconductor substrate, lattice matching with an AlGaInP epitaxial layer can be easily performed, and AlGaIn having excellent crystallinity can be obtained.
A P epitaxial layer is obtained. However, since the GaAs substrate functions as an absorption layer for the light emitted from the AlGaInP light-emitting portion, if the GaAs substrate remains,
The light emitted to the GaAs substrate cannot be effectively extracted to the outside, and the brightness cannot be increased.

Therefore, according to the present invention, a light emitting portion composed 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. The opaque GaAs substrate is removed to remove AlGa.
The structure is such that the semiconductor layer 13 is maintained using the transparent semiconductor layer 135 transparent to the emission of InP as a support layer. Thereafter, a part of the semiconductor layer 13 is removed by etching, and a second surface forming an ohmic junction with the transparent semiconductor layer 135 is formed on the surface of the exposed part of the transparent semiconductor layer 135.
Is formed. When a part of the semiconductor layer 13 is removed by etching, the transparent semiconductor layer 135 is removed.
The second electrode 16 may be provided on a part of the epitaxial growth layer of the semiconductor layer 13, for example, a cladding layer without being removed. A first electrode 15 forming 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 electric 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 of the semiconductor layer 13 on the transparent semiconductor layer side, so that the circuit resistance increases, and as a result, the forward direction It is not preferable because the voltage increases. Therefore, the transparent semiconductor layer has a high carrier concentration,
A low-resistance semiconductor layer with low specific resistance is used. Transparent semiconductor layer 1
It is preferable to use a carrier having a carrier concentration of 2 × 10 ¹⁶ cm ⁻³ or more, and at this time, the specific resistance becomes about 10 ⁻⁵ Ωcm or less. In the present invention, the first conductivity type is n
Preferably, the second conductivity type is a p-type.
This is because the resistance of the n-type electrode is generally lower.

As a semiconductor layer transparent to light emission,
Generally, GaP or AlGaAs having a larger forbidden band width than the light emitting layer
Compounds such as s, GaAsP, ZnTe or ZnSe
A semiconductor layer can be selected. AlInGaP quaternary mixed crystal semiconductor
When used in the light emitting part, it is transparent to such light emission.
As a material of the transparent semiconductor layer 135 having good conductivity,
Is, for example, Ga from the viewpoint of growth cost, stability, and moisture resistance.
P is mentioned as the most preferred material. Transparent semiconductor layer
The conduction type of 135 is the conduction type of the semiconductor layer of the light emitting portion in contact with this.
And the carrier concentration is 2 × 10¹⁶cm^-3And above
Is preferred. Form ohmic junction of second electrode
In consideration of ease of carrying, the carry of the transparent semiconductor layer 135 is considered.
The concentration is desirably 1 × 10¹⁷cm^-3Need more
You. On the other hand, depending on the combination of semiconductor material and dopant,
Crystallinity decreases when the carrier concentration is too high
Therefore, the carrier concentration of the transparent semiconductor layer 135 is
1 × 10¹⁹cm^-3The light absorption by the dopant is completely
Considering the elimination, 2 × 10 for p-type ¹⁸cm^-3
Hereinafter, 6 × 10 for n-type¹⁷cm^-3The following are particularly desirable
No. The thickness of the transparent semiconductor layer 135 is 50 to 100.
μm is suitable. The half supported by the transparent semiconductor layer 135
Is the thickness of the conductor layer 13 at most about 4 to 10 μm
The thickness of the transparent semiconductor layer 135 is substantially the same as that of the semiconductor light emitting device 1.
0 is the total thickness.

FIG. 3 shows the relationship between the thickness of the semiconductor device 10 and the defect rate of the device. The figure shows that the thickness of the semiconductor element 10 is 50.
If it is less than μm, it is difficult to handle, and the defective rate in the process of manufacturing the semiconductor light emitting device increases significantly. When the thickness is thick, the transparent semiconductor layer 135 has a large warp after epitaxial growth, and it is difficult to process the semiconductor wafer from an epitaxial wafer state into a semiconductor light emitting device (chip), and the defect tends to increase slightly. Also, from the viewpoint of the cost of epitaxial growth, it is desirable that the thickness of the semiconductor element 10, that is, the thickness of the transparent semiconductor layer 135 be 100 μm or less.

As shown in FIG. 1, it is preferable that the first electrodes (distribution electrodes) 15 are uniformly distributed on the light emitting surface.
For example, as shown in FIG. 1, a plurality of first electrodes 15 are arranged evenly. Alternatively, non-independent radial, donut-shaped, spiral, frame-shaped, lattice-shaped, or branch-shaped electrodes may be evenly distributed on the light emitting surface. Forming the first electrode dispersedly over the surface of the semiconductor layer means that the electrodes are arranged evenly on the element surface 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 depending on the type of metal to be used as the electrode and the type of semiconductor crystal to be joined and the area of the first electrode 15. It is preferable that the contact resistance with the contact 13 be about 50Ω or less. First
If the area of the electrode 15 is too small, the contact resistance increases and the forward voltage (Vf) of the light emitting element increases. Therefore, the entire 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, 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 is reduced. Therefore, it is desirable that the area of the first electrode 15 be 30% or less of the area of the light emitting surface. The material of the first electrode 15 includes the first electrode 1
5 is made of AuZn alloy or AuBe alloy if the outermost surface layer of the semiconductor layer 13 is a p-type layer, and Au is used if the outermost layer is an n-type layer.
Known techniques such as GeNi alloy and AuSi alloy can be applied. The thickness of the first electrode 15 is suitably about 0.2 to 1.0 μm. The first electrode 15 is formed by forming a metal thin film by a vapor deposition method or a sputtering method and then patterning it into a predetermined shape.

In order to supply the input power from the external electric circuit to the distributed first electrodes 15, the entire surface of the semiconductor layer 13 including the first electrodes 15 is subjected to current diffusion so as to connect the first electrodes 15. Cover with layer 14. As the current spreading 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, a metal electrode for further connecting a wiring on the current diffusion layer is used. Need to be formed. From this point, it is most desirable to use a current spreading layer made of a metal thin film whose structure and forming method are simple. The formation region of the current diffusion layer 14 may be partially formed if it covers the first electrode 15 because it functions as a connection between the electrodes. However, the formation region of the current diffusion layer 14 is advantageous in increasing the luminance because a light reflection effect described later can be used. It is preferable to form the entire surface of the semiconductor layer 13.

In the semiconductor light emitting device 10 having the above structure,
First ohmic contact with a part of the surface of the semiconductor layer 13
Of the first electrode 1 (distribution electrode) is compared with the electric resistance between the current diffusion layer 14 and the semiconductor layer 13.
5 and the semiconductor layer 13, the driving current supplied from the current spreading layer 14 is mostly the current spreading layer 14 → the first electrode 15 → Semiconductor layer 13 (→ light emitting portion 12) → second electrode 1
It flows through path 6. Therefore, light emission from the light emitting unit 12 can be performed immediately below the first electrode 15. First
Since the electrodes 15 are 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.

Further, the metal thin film used as the current diffusion layer also has a function as a light reflection film. The region other than the first electrode 15 reflects light from the light emitting unit 12 by the current diffusion layer 14 made of a metal thin film to form the transparent semiconductor layer 13.
5, the light is emitted from the surface via the transparent semiconductor layer 135, so that the luminous efficiency can be greatly improved. When the current diffusion layer 14 and the first electrode 15 are used, light on the light extraction surface of the semiconductor layer 13 can be made uniform.

The metals used as the current diffusion layer 14 include gold (Au), silver (Ag), aluminum (Al), nickel (Ni), zinc (Zn), chromium (Cr), and platinum (Pt). ), Or a metal such as titanium (Ti), tantalum (Ta), or an alloy of these metals that reflects light well and has good electrical conductivity.
Among the metals, gold or a gold alloy which is hard to corrode and a metal having good adhesion to a semiconductor, that is, a high melting point metal is desirable, and for example, chromium, platinum or titanium is particularly desirable. 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 be used as the current diffusion layer.

The thickness of the current spreading layer 14 is 0.5 μm to 3 μm.
About μm is appropriate. This is because electric resistance is low and light is sufficiently reflected. When the thickness of the current diffusion layer 14 is 0.5 μm
If the thickness is smaller than m, the electric resistance is high, and the spread of the current becomes insufficient. On the other hand, even if the thickness of the current diffusion layer 14 is too large, the effect is not improved even though it takes time to form the film.

Next, the second electrode 16 will be described.
The second electrode 16 is formed of the second conductive type transparent semiconductor layer 1.
35, or the transparent semiconductor layer 13 of the semiconductor layer 13
5 is formed on the surface of the layer of the second conductivity type in contact with 5. The second electrode 16 also forms an ohmic junction with these second conductivity type semiconductor layers. For example, when the semiconductor layer has a light emitting portion 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.
The material used for the second electrode 16 includes the second electrode 1
When the semiconductor layer forming 6 is a p-type layer, an AuZn alloy or an AuBe alloy is used. When the semiconductor layer is an n-type layer, an AuGeNi alloy is used.
Alternatively, a known technique such as an AuSi alloy can be applied. Since the second electrode 16 serves as one electrode for supplying power from the outside, it is sufficient to secure an area having a contact resistance of about 50Ω or less in a part of the transparent semiconductor layer 135. For example, as shown in FIG. 1, the device is provided in a sector shape at a corner portion of the element so that the area of the light emitting section region is as large as possible.

The thickness of the second electrode 16 is usually from 0.2 to
Although an electric contact can be formed if the thickness is 1.0 μm, in the present invention, the first electrode 15 and the second electrode 1 are formed on the same surface of the support substrate.
6 are formed to be slightly thicker. Considering the case where the semiconductor light emitting element is mounted on another electronic component, the surfaces of the first electrode 15 and the second electrode 16 need to be close to the same level. The length is about 2 to 6 μm. Therefore, a metal film is formed to be slightly thicker by using an evaporation method or the like, and is patterned into a predetermined shape to form a second electrode.

The first electrode 15 is formed on one surface of the semiconductor layer 13 and has a thickness of at most 2 to 5 μm.
It is. 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, the second
The height (h2) of the surface of the electrode 16 of the transparent semiconductor layer 13
If it is set at a position of about 6 μm from the surface of No. 5, the surfaces of both electrodes are almost at the same level, which is extremely convenient for mounting. If the level difference (d) between the first electrode 15 and the second electrode 16 becomes large, it causes a connection failure at the time of mounting.

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 failure rate at the time of assembly such as disconnection due to a height difference between the first and second electrodes and contact failure 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 forming the semiconductor layer 13. However, in terms of controlling the thickness, the liquid phase epitaxial growth method uses a thin film of 4 μm or less. It is difficult to control the thickness. On the other hand, vapor phase epitaxy (VPE) can control even a thin film having a 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. Point of film thickness control and AlI of DH structure
The MOCVD method is most suitable as a method for forming a light emitting portion having a high luminous efficiency such as nGaP.

On the other hand, in order to form the second electrode 16 with a large thickness, it is suitable to use a vacuum deposition method. According to the vacuum vapor deposition method, film formation on the order of μm can be performed relatively easily. Of course, means for adjusting both the position of the surface of the first electrode 15 and the position of the surface of the second electrode 16 may be used together. By making full use of these means and keeping the level difference (d) between the surface of the first electrode 15 and the surface of the second electrode 16 at 4 μm or less, it is possible to reduce the product defect rate in the mounting process. .

The semiconductor light-emitting device completed in this manner has a light-emitting portion and one electrode on one surface of a thick semiconductor layer transparent to the emission wavelength, and has the other electrode on the surface of the light-emitting portion. Therefore, at the time of mounting work, connection wiring can be performed without using wire bonding simply by placing the light emitting element at a predetermined position. Further, since the electrodes provided in the light emitting portion are composed of an electrode forming an ohmic junction with the light emitting layer and a current diffusion layer connecting these ohmic electrodes, the input power is spread over the entire light emitting portion, and the light emitting region area is increased. , A high luminance can be obtained. Furthermore, since the current diffusion layer also has a light reflection function, light emitted to the current diffusion layer side is also reflected and returns to the transparent semiconductor layer side, and most of the light excited by the light emitting unit is transmitted to the transparent semiconductor layer. Since the light is radiated to the outside from the layer side, a semiconductor light emitting device with still higher luminance can be obtained.

Next, the structure of the light emitting diode lamp will be described. FIG. 5 is a plan view showing a light emitting diode lamp according to the present invention, and FIG. 6 is a view showing a cross sectional structure taken along line BB ′ of FIG. Light emitting diode lamp 4 of the present invention
0 is a flip-chip type semiconductor light emitting device 1 according to the present invention.
Using 0, it is manufactured as follows. First, a base material 45 on which a first electrode terminal 43 and a second electrode terminal 44 are formed at a predetermined position on the front and back surfaces of a synthetic resin plate or the like using, for example, a conductive paste or copper foil. 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 rear 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 a diagonal line of the square semiconductor light emitting device 10. Further, the second electrode terminal 44 is formed to have the width of the fan-shaped second electrode 16 of the semiconductor light emitting device 10.

On the first electrode terminal 43 and the second electrode terminal 44 formed on the base material 45, bumps made of gold, solder, or the like, which are usually used in flip-chip type assembly, are used. 46 is formed. Then, one of the semiconductor light emitting devices 10 according to the present invention is overlaid on the base material 45, and the current diffusion layer 14 and the second electrode 16 of the semiconductor light emitting device 10 are brought into contact with the bumps 46 by pressure bonding to be connected. . Finally, the periphery of the semiconductor light emitting element 10 is sealed with a sealing material 41 such as a transparent epoxy resin or a silicon resin, and the light emitting diode lamp 40 shown in FIG. 6 is obtained.

When the light emitting diode lamp 40 is configured as described above, the light emitting diode lamp 40 can be used in other electronic devices.
In the case of manufacturing a display device by mounting the first electrode terminal 43 and the second electrode terminal 44 formed on the back side of the base material 45, Since the mounting operation can be performed, the efficiency of the mounting operation can be increased, and a display device that is inexpensive and has few failures can be manufactured.

[0045]

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 same were manufactured. The semiconductor light emitting device (LED) manufactured in this example is undoped (Al _0.2 Ga
_0.8 ) a light emitting layer composed of _0.5 In _0.5 P and having a wavelength of about 6
It is an LED that emits 20 nm red light.

First, the laminated structure of the semiconductor epitaxial wafer 20 will be described with reference to FIG. FIG. 7 is a detailed cross-sectional view showing a stacked structure of the semiconductor epitaxial wafer 20 used for the semiconductor light emitting device of the present invention. On a semiconductor substrate 11 made of a GaAs single crystal having a Si-doped n-type (001) plane, a Si-doped n-type Ga
As buffer layer 130 made of As, n-type A doped with Si
a contact layer 131 made of lGaAs, a lower cladding layer 132 made of n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P doped with Si, and an undoped (Al _0.2 Ga _0.8 )
_0.5 In _0.5 emitting layer 133 composed of P, Zn-doped p-type _{(Al 0.7 Ga 0.3) 0.5 In} 0.5 the upper cladding layer 134 composed of P, and the transparent semiconductor layer 135 composed of Zn-doped p-type GaP sequentially The epitaxial wafers 20 are formed by being stacked. The light emitting portion 12 of the epitaxial wafer is provided with a lower cladding layer 13.
2, a double heterojunction structure composed of a light emitting layer 133 and an upper cladding layer 134. Therefore, the semiconductor crystal of the light emitting section 12 is composed of AlGaInP quaternary mixed crystal.

(Manufacturing Process of Epitaxial Wafer) A method of manufacturing the epitaxial wafer will be described. In this embodiment, first, trimethylaluminum ((CH ₃ ) ₃
Al), trimethylgallium ((CH ₃ ) ₃ Ga) and trimethyl indium ((CH ₃ ) ₃ In) are used as raw materials for group III constituent elements, and phosphine (PH ₃ ) or arsine ( Using AsH ₃ ), each of the semiconductor layers 130 to 134 is formed of GaAs by metal organic chemical vapor deposition (MOCVD) under reduced pressure.
Then, a transparent semiconductor layer 135 made of GaP was grown thereon by a vapor phase epitaxial growth method (VPE method) to form an epitaxial wafer 20. Diethyl zinc ((C ₂ H ₅ ) ₂ Zn) was used as a Zn doping material. Si
Disilane (Si ₂ H ₆ ) was used as a doping raw material. MO of each layer constituting the epitaxial wafer 20
The lamination temperature in the CVD method and the VPE method was unified to 700 ° C.

The carrier concentration of the buffer layer 130 made of GaAs was about 5 × 10 ¹⁸ cm ⁻³ , and the layer thickness was about 0.2 μm. The contact layer 131 is made of A having an Al mixed crystal ratio of 0.4.
An lGaAs thin film is laminated, and the carrier concentration is about 3 × 10 ¹⁸
cm ⁻³ and a layer thickness of about 0.8 μm. The carrier concentration of the lower cladding layer 132 made of AlInGaP is about 1 × 1
0 ¹⁸ cm ⁻³ , and the layer thickness was about 1 μm. AlInGa
The layer thickness of the light emitting layer 133 made of P was about 0.5 μm, and the carrier concentration was about 5 × 10 ¹⁶ cm ⁻³ . Further AlI
The carrier concentration of the upper cladding layer 134 made of nGaP was about 2 × 10 ¹⁷ cm ⁻³ , and the layer thickness was 1.5 μm.
As a result, the total thickness of the epitaxially grown semiconductor layer 13 was about 4 μm. Semiconductor substrate 11 made of GaAs
The GaP transparent semiconductor layer 135 serving as a support in place of the above has a layer thickness of 70 μm and a carrier concentration of about 8 × 10
¹⁷ cm ^-3 .

(Substrate Removal Step) Next, the semiconductor substrate 11 made of GaAs opaque to the emission wavelength and the GaAs
Was completely removed by chemical etching. Further, a part of the contact layer 131 in the remaining semiconductor layer 13 was also selectively removed by etching as shown by a chain line XX ′ in FIG.

(Electrode Forming Step) 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 to a thickness of 0.3 μm. It was formed by a vacuum evaporation method so as to be as follows. Patterning is performed using a general photolithography means, and a circular first electrode 1 having a diameter of 30 μm is formed.
5 were dispersed and 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, 0.1 μm of Cr and about 1 μm of gold are deposited by vacuum evaporation.
The current diffusion layer 14 was formed to a thickness of m. Next, patterning is performed to remove the current diffusion layer 14 and the semiconductor layer 13 in the region indicated by the dashed line YY ′ in FIG. 7, so that a side of 130 μm is formed at the corner of the transparent semiconductor layer 135 so that the second electrode can be formed. Exposed the fan-shaped area of

Next, in order to form the second electrode 16,
First, a gold / zinc alloy film having a thickness of 0.5 μm and a film thickness of 2
A gold thin film having a thickness of μm was applied to the entire surface including the transparent semiconductor layer 135 and the resist surface of the patterning by a general vacuum deposition method. Subsequently, the resist is removed by a known lift-off method, and the radius is 125 μm as shown in FIG.
A second electrode 16 having a fan shape of m was formed. Next, after the first and second electrodes are formed, an alloying heat treatment is performed at 420 ° C. for 15 minutes in a stream of argon (Ar), so that the first and second electrodes and each semiconductor layer are separated. Ohmic contact was formed.

(LED Manufacturing Process) As described above,
The epitaxial wafer on which the first electrode 15, the second electrode 16, and the current diffusion layer 14 formed of a metal multilayer film were formed was cut into element shapes by a normal scribing method, and individually divided into semiconductor light-emitting elements. The flip-chip type semiconductor light emitting device thus obtained was a square having a side of 300 μm and a thickness of 74 μm as viewed in plan, as shown in FIG.

(Light emitting diode lamp assembling process)
The light emitting diode lamp shown in FIGS. 5 and 6 was assembled using the semiconductor light emitting device 10. First, a base material 45 having a first electrode terminal 43 and a second electrode terminal 44 formed at predetermined positions on the front and back surfaces of a synthetic resin plate using a conductive paste.
Was prepared. First electrode terminal 43 and second electrode terminal 44
Are electrically isolated from each other and 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 a diagonal line of the square semiconductor light emitting device 10. Also, the second electrode terminal 44
Was formed to have the width of the sector-shaped second electrode 16 of the semiconductor light emitting device 10. A bump 46 made of gold is formed on the first electrode terminal 43 and the second electrode terminal 44 formed on the base material 45.
Was formed. One of the semiconductor light emitting devices 10 is superimposed on the substrate 45, and the current diffusion layer 1 of the semiconductor light emitting device 10 is
4 and the second electrode 16 were brought into contact with the bumps 46 and pressed and connected. 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.

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 manufactured as described above, the wavelength was reduced by about 6 from the light-emitting layer.
A red light of 20 nm was emitted. Part of the light emission was reflected by the current diffusion layer 14 made of a metal film, and emitted 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 _f : 20) when a current of 20 mA flows in the forward direction
(per mA) was about 2.0 V. The light emission intensity at this time achieved an ultra-high luminance of 150 mcd, reflecting that the light emission efficiency of the light emitting portion was high and the efficiency of taking out to the outside was also devised.

(Comparative Example 1) In the flip-chip type semiconductor light emitting device according to Comparative Example 1, compared to the above-described embodiment, the first electrode is formed one size larger and the metal current diffusion layer is formed. The point that is not used is a structural difference. Therefore, the point using the epitaxial wafer shown in FIG.
This is the same as the embodiment. The size of the semiconductor light emitting device of Comparative Example 1 was a square having a side of 300 μm and a thickness of 74 μm.
Semiconductor light-emitting device. 8 and 9 show the structure of the semiconductor light emitting device manufactured in Comparative Example 1. FIG. FIG. 8 is a plan view of the semiconductor light emitting device manufactured in Comparative Example 1, and FIG.
It is sectional drawing which followed C '. 8 and 9,
The portions indicated by 25, 26, and 235 correspond to the portions indicated by reference numerals 12, 15, 16, and 135 in FIGS.

In Comparative Example 1, the shape of the first electrode 25 formed on the contact layer 131 was different from that of the above-described embodiment. That is, in Comparative Example 1, the first electrode 2 was used to obtain the necessary area for connection with the gold bump.
5 was made into a circle having a diameter of 130 μm, and only one was formed. As the first electrode 25, an n-type ohmic electrode made of an Au.Ge alloy is formed so as to have a thickness of 0.3 μm.
Further, a gold thin film having a thickness of 1 μm was formed thereon by a vacuum evaporation method. Patterning is performed using general photolithography means, and the diameter is set to 130 as shown in FIG.
A circular first electrode 25 having a thickness of μm was formed. The area ratio of the first electrode to the area of the light emitting surface is about 33%.

Thereafter, a light emitting diode lamp was manufactured in the same manner as in the embodiment, and a current was applied between the first electrode terminal and the second electrode terminal of the light emitting diode lamp in a forward direction. Red light with a wavelength of about 620 nm was emitted through the side. A forward voltage (V _f : per 20 mA) when a current of 20 mA (mA) flows in the forward direction is about 2.1 volts (V).
And was equivalent to the example. The emission intensity at this time is 90
mcd. The emission intensity was about 60% of that of the example of the present invention. This is because there is no current diffusion layer, the current flowing to the light emitting section is uneven, the luminous efficiency of the entire light emitting section is reduced, and light is lost because there is no reflection of light from the current diffusion layer. Since the electrode area of the first electrode 25 was large and light absorption at the interface between the electrode and the semiconductor layer was increased,
This is due to a decrease in the efficiency of taking out to the outside.

Comparative Example 2 In Comparative Example 2, a semiconductor light emitting device having the same light emitting area 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 33
5 is a p-type high-resistance GaP layer. The carrier concentration of the transparent semiconductor layer 335 was about 8 × 10 ¹⁵ cm ⁻³ , and the layer thickness was 70 μm. The total thickness of the semiconductor layer 33 is about 4 μm.

The manufacturing method of the semiconductor light emitting device manufactured in Comparative Example 2 is different from that of the embodiment, and the semiconductor layer 33 is removed by etching to the upper cladding layer 334 along the line YY ′ in FIG. A second electrode was formed on the surface of the cladding layer 334. Other structures are the same as FIG.
The structure shown in FIG. Therefore, in FIG.
The parts indicated by 2, 33, 330, 331, 332, 333, 334 are the reference numerals 11, 12, 13, 130,
These correspond to the parts indicated by 131, 132, 133 and 134. In Comparative Example 2, the transparent semiconductor layer 335 was made of p-type GaP having low conductivity and high resistance, which was different from that of 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 were formed was cut into individual element shapes by a normal scribing method and individually divided into small pieces. The LED was assembled in the same manner.

When a forward current was passed between the first and second electrode terminals in the same manner as in the example, the forward voltage when 20 mA was supplied was 3.5 V. The forward voltage is higher than in the embodiment. This is because the resistance of the transparent semiconductor layer 335 is high and most of the current flows through the upper clad layer 334 having a small thickness.
This causes the resistance to increase. The light emission intensity of the LED of Comparative Example 2 was 105 mcd, and the light emission state in the device was uneven. 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
This is because the power consumption is large and the efficiency of the light emitting unit is reduced.

[0061]

As described above, in the flip-chip type semiconductor light emitting device of the present invention, since the wire bonding is not used, the assembly of the light emitting device is easy, the wire is not broken, and the reliability is improved. Further, by providing an ohmic electrode and a current diffusion layer on a part of the back surface of the light emitting portion of the semiconductor layer, a current can be uniformly supplied to the light emitting portion, the efficiency of the light emitting portion as a whole increases, and the light emission intensity increases.

Further, the current diffusion layer reflects light from the light-emitting portion to increase the efficiency of extracting light to the outside, and also has a large connectable area when assembling the light-emitting element, thereby facilitating the assembly.
There is also a productivity improvement effect. In addition, the transparent semiconductor layer on the light emitting element surface side is transparent to light emission, and by imparting conductivity,
This has the effect of reducing the power consumption by improving the emission intensity and reducing the forward voltage. The thickness of a semiconductor element greatly affects productivity and product yield, and a low-cost element can be obtained by selecting an appropriate range.

In this embodiment, the LED is manufactured using the n-type semiconductor substrate. However, the effects of the present invention can be obtained with the LED manufactured using the p-type semiconductor substrate. The semiconductor material of the light emitting portion of the LED of the embodiment is AlGaInP4.
Although the original mixed crystal was used, the material and composition of the semiconductor crystal of the light emitting part,
The effect of the present invention can be obtained even if a known technique is used for a laminated structure or a dopant such as Mg, Te, S, or Se.

In particular, the thickness of the semiconductor layer on which the semiconductor layer is laminated by the MOCVD method is small.
The effect of the present invention is particularly large in a semiconductor light emitting device made of an nGaP-based, AlGaInN-based, AlGaAs-based semiconductor, or the like. Ga as a conductive transparent semiconductor layer
Although P is used, high luminance can be achieved even with AlGaAs, but when Al is contained in a large amount, its use is limited because of poor moisture resistance. In the embodiment, a general flip-chip type light emitting diode lamp is shown. However, a similar effect can be obtained by a so-called shell type having a different shape or a light emitting diode lamp incorporating a plurality of light emitting elements having different emission wavelengths. . Further, a display device which is inexpensive and has few failures can be manufactured by using these light emitting diode lamps.

In order to increase the brightness of the semiconductor light emitting device, a technique for improving the efficiency of extracting light to the outside by surface roughening treatment, or a window having a smaller refractive index than the semiconductor used in the light emitting portion. If a technique used in a conventional light-emitting element, such as forming a layer and improving the light extraction efficiency to the outside, is added, the light-emitting 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 AA ′ of FIG. 1;

FIG. 3 is a diagram illustrating a relationship between a thickness of a semiconductor light emitting element and a defective 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 of the present invention.

FIG. 6 is a diagram showing a cross section taken along line BB ′ of FIG. 5;

FIG. 7 is a diagram showing a cross section of an epitaxial wafer used for the semiconductor light emitting device of the present invention.

FIG. 8 is a plan view of a semiconductor light emitting device according to Comparative Example 1.

FIG. 9 is a diagram showing a cross section taken along line CC ′ of FIG. 8;

FIG. 10 is a view showing a cross section of an epitaxial wafer according to Comparative Example 2.

[Explanation of symbols]

 10, semiconductor light-emitting elements 11, 31, semiconductor substrate 12, 22, light-emitting section 13, 33, semiconductor layer 14, current diffusion layer 15, 25 first electrode 16, 26 second electrode 40 light-emitting diode lamp 41 encapsulant 43 first electrode Terminal 44 Second electrode terminal 45 Base 46 Bump 130, 330 Buffer layer 131, 331 Contact layer 132, 332 Lower part Cladding layers 133, 333 Light emitting layers 134, 334 Upper cladding layers 135, 235, 335 Transparent semiconductor layers

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F041 CA13 CA34 CA37 CA82 CA92 CA93 CB15 DA04 DA09 DA19 DA35 DA43

Claims (31)

[Claims] 1. A transparent semiconductor layer having a second conductivity type and transparent to light emitted from a light emitting unit, and a second conductivity type semiconductor layer sequentially laminated on one surface of the transparent semiconductor layer. A first conductive type semiconductor layer comprising a light emitting portion having a pn junction structure and a first conductive type semiconductor layer opposite to the transparent semiconductor layer; A first electrode in ohmic contact with the conductive semiconductor layer, and formed on the surface of the first conductive semiconductor layer on which the first electrode is formed, covering the first conductive semiconductor layer and the first electrode; The current diffusion layer formed on a part of the surface of the transparent semiconductor layer or the second conductivity type semiconductor layer on the side where the first conductivity type semiconductor layer is located, and is electrically separated from the current diffusion layer and transparent. A second electrode in ohmic contact with the semiconductor layer or the second conductivity type semiconductor layer. Characteristic flip-chip type semiconductor light emitting device. 2. The device according to claim 1, wherein the current diffusion layer forms a reflection layer that reflects light emitted from a light emitting unit.
4. The flip-chip type semiconductor light emitting device according to claim 1. 3. 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. 4. 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 high melting point metal. 5. The flip-chip type semiconductor light emitting device according to claim 4, wherein the refractory metal is one of chromium, platinum, and titanium or an alloy thereof. 6. The current diffusion layer according to claim 1, wherein the current diffusion layer comprises a multilayer film of two or more kinds of metals.
The flip-chip type semiconductor light emitting device according to any one of the above. 7. The current diffusion layer has a thickness of 0.5 μm or less.
The flip-chip type semiconductor light emitting device according to claim 1, wherein the thickness is 3 μm. 8. The flip-chip type semiconductor light emitting device according to claim 1, wherein a plurality of the first electrodes are arranged on a surface of the first conductive type semiconductor layer. element. 9. The semiconductor device according to claim 1, wherein a total area of the first electrodes is 2% or more and 30% or less of a surface area of the first conductivity type semiconductor layer. Flip-chip type semiconductor light emitting device. 10. The semiconductor device according to claim 1, wherein a contact resistance between said first electrode and said first conductivity type semiconductor layer is smaller than a contact resistance between said current diffusion layer and said first conductivity type semiconductor layer. The flip-chip type semiconductor light emitting device according to claim 1. 11. The semiconductor light emitting device according to claim 1, wherein a contact resistance between the first electrode and the first conductivity type semiconductor layer is 50Ω or less. 12. The flip-chip type semiconductor according to claim 1, wherein a level difference between the first electrode surface and the second electrode surface is within 4 μm. Light emitting element. 13. The carrier concentration of the transparent semiconductor layer is as follows:
2. The structure according to claim 1, wherein the size is 2 × 10 ¹⁶ cm ⁻³ or more.
The flip-chip type semiconductor light emitting device according to any one of claims 1 to 12. 14. The transparent semiconductor layer has a specific resistance of 1 Ωc.
m is equal to or less than m.
The flip-chip type semiconductor light emitting device according to any one of the above. 15. The flip-chip type semiconductor light emitting device according to claim 1, wherein said transparent semiconductor layer is made of GaP. 16. The flip-chip type semiconductor light emitting device according to claim 1, wherein said light emitting portion is made of AlGaInP. 17. The flip-chip type semiconductor light emitting device according to claim 1, wherein the first conductivity type is an n-type and the second conductivity type is a p-type. . 18. The flip-chip type semiconductor light emitting device according to claim 1, wherein a total thickness of the semiconductor light emitting device is 50 μm or more and 100 μm or less. 19. A semiconductor layer including a light emitting portion and a transparent semiconductor layer are sequentially laminated on a semiconductor substrate, and then the semiconductor substrate is removed. Then, a first layer is formed on the surface of the semiconductor layer on the side where the semiconductor substrate is removed. 19. The flip chip according to claim 1, wherein an electrode and a current diffusion layer are formed, and a second electrode is formed on a surface of the transparent semiconductor layer or the second conductivity type semiconductor layer. Of manufacturing a semiconductor light emitting device. 20. The method according to claim 19, wherein the semiconductor substrate is a semiconductor that functions as an absorption layer for light emitted from a light emitting section. 21. The method according to claim 19, wherein the semiconductor substrate is made of GaAs, and the light emitting part is made of AlGaInP. 22. The method of manufacturing a flip-chip type semiconductor light emitting device according to claim 19, wherein said semiconductor layers are stacked by metal organic chemical vapor deposition (MOCVD). . 23. The method of manufacturing a flip-chip type semiconductor light emitting device according to claim 19, wherein said transparent semiconductor layer is laminated by a vapor phase epitaxial growth method (VPE method). 24. A base material, first and second electrode terminals formed on the base material so as to be electrically isolated from each other, and a current diffusion layer and a second electrode terminal formed on the first and second electrode terminals, respectively. 19. A light-emitting diode lamp comprising: the flip-chip type semiconductor light-emitting device according to claim 1, wherein the electrodes are electrically connected to each other; and a sealing material for sealing the semiconductor light-emitting device. 25. The semiconductor device according to claim 25, wherein said first and second electrode terminals are formed on the same plane on the surface of said base material, and said semiconductor light-emitting device is mounted on said plane of said base material. 25. The light emitting diode lamp according to 24. 26. An electric connection between said first and second electrode terminals and said current diffusion layer and said second electrode by means of a bump made of gold or solder.
26. A light emitting diode lamp according to claim 25. 27. A display device using the light-emitting diode lamp according to claim 24. 28. A first electrode which is formed on a part of the surface of a semiconductor layer having a light emitting portion and is in ohmic contact with the semiconductor layer, and the first electrode is provided on the surface of the semiconductor layer. An electrode for a flip-chip type semiconductor light emitting device, comprising: a first electrode; and a current diffusion layer formed so as to cover the first electrode. 29. The electrode for a flip-chip type semiconductor light emitting device according to claim 28, wherein said current diffusion layer is a layer for reflecting light emitted from a light emitting portion. 30. The flip-chip type semiconductor light emitting device electrode according to claim 28, wherein a plurality of said first electrodes are arranged on a surface of a semiconductor layer. 31. The semiconductor device according to claim 28, wherein a contact resistance between the first electrode and the semiconductor layer is smaller than a contact resistance between the current diffusion layer and the semiconductor layer. The electrode for a flip-chip type semiconductor light emitting device according to the above.