JP2001339100A - Light emitting element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element excellent in convenience wherein light leading-out efficiency from an element is superior and terminal leading-out structure of the element is simple. SOLUTION: A metal layer 3, a light emitting layer 4 and a first electrode 5 are formed in this order on the first main surface 7 side of a conductive substrate 2. A current is applied to the light emitting layer 4 through the first electrode 5 and the conductive substrate 2. By using reflection of the metal layer 3, superior light leading-out efficiency can be realized, and further electrodes or terminals can be formed on both sides of the light emitting element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light emitting device and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a result of years of progress in materials and device structures used for light emitting devices such as light emitting diodes and semiconductor lasers, photoelectric conversion efficiency inside the device is gradually approaching a theoretical limit. Therefore, when an element with higher luminance is to be obtained, the light extraction efficiency from the element is extremely important. As a method for improving the light extraction efficiency, a method has been proposed in which a light-transmitting semiconductor substrate is joined to the light-emitting layer so that light traveling from the light-emitting layer toward the substrate can also contribute to light emission. However, when an attempt is made to directly join a light-transmitting semiconductor substrate to a light-emitting layer portion, the process generally tends to be complicated, and the light-emitting layer portion is liable to be deteriorated because a high-temperature bonding process is required. There is.

Next, a light emitting device having a light emitting layer portion formed of an AlGaInP mixed crystal has a thin AlGaInP (or GaInP) active layer, an n-type AlGaInP cladding layer having a larger band gap and a p-type AlGaI.
By employing a double hetero structure sandwiched between the nP cladding layer and the nP cladding layer, a high-luminance element can be realized. Such an AlGaInP double heterostructure can be formed by epitaxially growing each layer made of an AlGaInP mixed crystal on a GaAs single crystal substrate, utilizing the fact that the AlGaInP mixed crystal lattice-matches with GaAs. When this is used as a light emitting element, a GaAs single crystal substrate is often used as it is as an element substrate. However, the AlGaInP mixed crystal constituting the light emitting layer has a band gap larger than that of GaAs, so that the emitted light is absorbed by the GaAs substrate, and it is difficult to obtain sufficient light extraction efficiency. In order to solve this problem, a method of inserting a reflective layer composed of a semiconductor multilayer film between a substrate and a light emitting element (for example, Japanese Patent Application Laid-Open No.
No. 66455) has been proposed, but since the difference in the refractive index of the stacked semiconductor layers is used, only light incident at a limited angle is reflected, and a great improvement in light extraction efficiency cannot be achieved in principle. Can't expect.

On the other hand, recent literature (Applied Physics Lett)
ers, 75 (1999) 3054), as shown in FIG.
It has been proposed to insert a metal layer mainly composed of Au between a light emitting layer portion having a GaInP double heterostructure and a silicon single crystal substrate. Specifically, the light emitting element 100 shown in FIG. 14 has an AuBe layer 103 on an SiO ₂ layer 102 formed by oxidizing an n-type silicon single crystal substrate 101.
And an Au layer 104 as a metal layer 110, a p-type GaAs cap layer 105, a p-type AlGaInP cladding layer 106 having a double heterostructure, and an AlGaI
nP active layer 107 and n-type AlGaInP cladding layer 1
08 and an electrode 10 comprising an AuGeNi / Au layer
9 are formed. Light generated in the active layer 107 is reflected by the Au layer 104 as shown in FIG.

According to this structure, since the metal layer 110 functions as a reflecting mirror, a high reflectance independent of the incident angle is realized, and the light extraction efficiency can be greatly increased.
However, in this case, since it is impossible to grow the AlGaInP mixed crystal layer directly on the metal layer, the following method is employed. First, a silicon single crystal substrate 101 on which a metal layer 110 is formed by vapor deposition, and AlGaInP
A light emitting layer portion having the double heterostructures 106, 107 and 108 and a GaAs single crystal substrate on which the GaAs cap layer 105 is epitaxially grown are separately prepared. Next, after bonding both substrates between the metal layer 110 and the cap layer 105, the GaAs single crystal substrate is removed, and necessary electrodes are formed to form a device.

[0006]

In the device disclosed in the above document, a thick insulating film 1 made of SiO _{2 is used} as the silicon single crystal substrate 101 on which the metal layer 110 is formed.
02 is used, and as shown in FIG. 14, the cap layer 105 and the light emitting layer portions 106 to
The energization of the cap layer 1 in the Au layer 104
The Au layer 104 and the electrode 109 are used as electrodes, and the portions exposed outside the light emitting layer portions 106 to 108 are used as electrodes.
And without using the insulating film 102. Therefore, this structure has a drawback that the structure for taking out the terminals of the element must be complicated, which leads to an increase in the number of manufacturing steps and an increase in the price of the element.

An object of the present invention is to provide a light-emitting element which has good light extraction efficiency from the element, has a simple terminal extraction structure for the element, and is excellent in convenience, and a method of manufacturing the same.

[0008]

Means for Solving the Problems and Functions / Effects In order to solve the above problems, the light emitting device of the present invention comprises a metal layer, a light emitting layer portion and a first electrode on a first main surface side of a conductive substrate. It is formed in this order, and it is possible to conduct electricity to the light emitting layer portion through the first electrode and the conductive substrate.

According to the above structure, in a light emitting device in which a metal layer is inserted between a substrate and a light emitting layer portion, good light extraction efficiency can be realized by utilizing reflection on the metal layer. Electrodes or terminals can be formed on both sides. That is, unlike the light-emitting element of the above-mentioned document (FIG. 14), it is not necessary to form a terminal extraction portion by exposing the metal layer to the side of the light-emitting layer portion. Therefore, the structure for taking out the terminals of the element is greatly simplified, the chip size can be reduced, and a light-emitting element excellent in convenience is realized.

As shown in FIG. 1, the direction of energization of the laminate 9 including the conductive substrate 2, the metal layer 3, and the light emitting layer 4 is as follows.
As shown in (a), even if the polarity of the first electrode is negative,
Further, as shown in (b), any polarity is possible with the first electrode side being positive. In this case, the stacking order of the hetero junction structure in the light emitting layer unit 4 is reversed between (a) and (b).

The conductive substrate 2 can be made of a semiconductor such as silicon single crystal or a metal such as Al. When the conductive substrate 2 is a semiconductor, as shown in FIG. 1, the second electrode 6 is formed on the second main surface side of the conductive substrate 2, and the second terminal 12 is further formed on the second electrode 6. I do.
In this case, current is applied between the first electrode 5 and the second electrode 6. On the other hand, when the conductive substrate 2 is made of metal, the second terminal 12 can be formed directly on the conductive substrate 2, so that the second electrode 6 can be omitted. When a semiconductor is used as the conductive substrate 2, the conductive substrate 2
The structure in which the conductive substrate 2 and the metal layer 3 are in direct contact with each other is adopted from two viewpoints, namely, that current is passed through the metal layer 3 without any trouble and that the bonding strength between the metal layer 3 and the conductive substrate 2 is increased. It is desirable.

The first electrode 5 can be formed so as to cover only a part of the surface of the light emitting layer 4. In this case, of the light 13 and 14 generated in the active layer of the light emitting layer portion 4, at least a part of the light 14 directed toward the metal layer 3 is reflected by the metal layer 3, and the reflected light 15 is emitted. It can be leaked from a region of the layer portion surface that is not covered by the first electrode 5. As a result, more excellent light extraction efficiency can be realized.

The light-emitting element 1 as described above includes a conductive substrate 2
It can be manufactured by overlapping the light emitting layer portion 4 with the surface to be joined via the metal layer 3 and performing a joining process.

Specifically, it can be produced by the production method of the present invention described below. That is, in the manufacturing method of the present invention, the step of epitaxially growing the light emitting layer 4 on the semiconductor single crystal substrate and the step of forming the first main surface of the conductive substrate 2 and the first main surface of the light emitting layer 4 only by the metal layer 3 And a step of separating or removing the semiconductor single crystal substrate in this order. The joining process can be, for example, a joining process by heating.

In the above method, the conductive substrate 2 and the light emitting layer 4 are joined only via the metal layer 3. The conductive substrate 2 and the light emitting layer 4 are made of SiO ₂ unlike the above-mentioned document.
By bonding only with the metal layer 3 without the intermediary of an insulating film such as the one described above, not only the bonding strength can be increased, but also the electrical conduction between the conductive substrate 2 and the metal layer 3 can be ensured well. be able to. In particular, when the conductive substrate 2 is a silicon single crystal, a compound semiconductor single crystal, or a mixed crystal, the bonding strength is further improved by bonding the substrate and a part of the metal layer in a form of alloying. be able to.

[0016]

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1A is a conceptual diagram showing a light emitting device 1 according to one embodiment of the present invention. In the light emitting element 1, a metal layer 3, a light emitting layer part 4, and a first electrode 5 are formed in this order on the first main surface 7 side of the conductive substrate 2. The first electrode 5 is formed so as to cover only a part of the surface of the light emitting layer unit 4. A second electrode 6 is formed on the second main surface 8 side of the conductive substrate 2, and the first electrode 5 and the second electrode 6 are interposed between the light emitting layer 4 and the metal layer 3. (That is, through the first electrode 5 and the conductive substrate 2)
Electric current is supplied to the light emitting layer unit 4.

FIG. 2 shows a more specific configuration of the light emitting element 1. The conductive substrate 2 is n-type Si (silicon)
A single crystal substrate, the metal layer 3 includes a first metal layer 31 formed in contact with the Si single crystal substrate 2, an intermediate metal layer 32 in contact with the first metal layer 31 on the light emitting layer unit 4 side, A second metal layer formed in contact with the layer portion. Si
The single crystal substrate 2 is unlikely to be deformed by thermal stress or the like even when performing the heat bonding described later, and is easily alloyed with some specific metals (for example, Au). There are easy advantages. In this case, the first metal layer 31 is formed mainly of a metal component that is more easily alloyed with Si than the metal component that is the main component of the intermediate metal layer 32, so that the metal layer 3 and the Si single crystal substrate 2 are formed. Alloying mainly with the first metal layer 31, and can be prevented from reaching the intermediate metal layer 32. Thereby, the area ratio of the metal phase at the bonding interface between the metal layer 3 and the light emitting layer portion 4 is increased, and the flatness of the bonding interface can be kept good. Either of these contributes to the improvement of the reflectance at the bonding interface.

In this case, the first metal layer 31 can be formed mainly of a metal component having a lower eutectic temperature with Si than the metal component serving as the main component of the intermediate metal layer 32. By using a component that forms a eutectic at a relatively low temperature with silicon having a high melting point as a main component of the first metal layer 31, the heat bonding temperature can be lowered, and thus the light emitting layer portion 4 can be formed. Can be made less likely to occur. As a specific example, the first metal layer 31 is formed of an Au layer or an AuGe alloy (for example, a layer having a Ge content of about 12% by weight) such as an Au layer.
u as a main component, and the intermediate metal layer 32
It can be composed mainly of Al, such as an l layer or an Al alloy layer. The eutectic temperature of Au and Si is about 363 ° C., and the eutectic temperature of Al and Si is about 577 ° C. The intermediate metal layer 32 may be mainly composed of a metal that does not form a eutectic having a low melting point with Au as a main component, so that the influence of alloying between the intermediate metal layer 32 and the Si single crystal substrate 2 may be reduced. It is desirable from the viewpoint of making it difficult to reach the layer 32. A
l is desirable as a main component of the intermediate metal layer 32 from this viewpoint. In addition, other than Al, Ag, C
Components such as u, Ni, Pd or Pt can also be employed.

The Si single crystal substrate 2 has a heavily doped layer 2a formed on the first main surface and the second main surface thereof in order to enhance ohmic contact with the metal layer 3 and the second electrode 6. It is desirable to use a wafer that has been diffused (for example, a double-sided diffusion wafer in which a high-concentration dopant is thermally diffused). Alternatively, as the Si single crystal substrate 2, for example, a substrate doped with high concentration of As or B can be used. In this embodiment, an n-type S having n ⁺ doped layers 2a formed on both surfaces is used.
An i single crystal substrate 2 is used.

Next, in the present embodiment, the n-type AlGaInP cladding layer 4 is provided between the intermediate metal layer 32 and the light emitting layer section 4.
1 and a second metal layer 33 that reflects light from the light emitting layer section 4 is formed.

As the material of the second metal layer 33, for example, a material mainly composed of Au can be exemplified.
In this embodiment, the second metal layer 3 is made of an Au—Ge alloy.
3 is formed. The Ge content in the used Au-Ge alloy is preferably set to 1 to 3% by mass. Further, the second metal layer 33 may be an Au layer.

Next, the light emitting layer portion 4 includes a first conductive type clad layer 43 located on the first electrode 5 side, a second conductive type clad layer 41 located on the metal layer 3 side, and a first conductive type clad layer. It may have a double heterostructure layer composed of an active layer 42 formed between 43 and the second conductivity type cladding layer 41. By adopting such a structure, holes and electrons injected from the cladding layers 43 and 41 are efficiently recombined in a form confined in the narrow space of the active layer 42. realizable. In order to enhance the light extraction efficiency by reflection, the second conductivity type cladding layer 41 and the metal layer 3 are preferably formed in direct contact. However, it is also possible to insert a highly doped thin film between the second conductivity type cladding layer 41 and the metal layer 3 in order to lower the operating voltage.

The double hetero structure layer is specifically made of AlG
It can be composed of aInP mixed crystal. In particular,
The active layer 42 made of an AlGaInP mixed crystal or a GaInP mixed crystal can be configured to be sandwiched between a p-type AlGaInP cladding layer 43 and an n-type AlGaInP cladding layer 41. AlGaInP is a direct transition type semiconductor having a large band gap, and injected holes and electrons are narrow due to an energy barrier caused by a band gap difference between the cladding layers 43 and 41 formed on both sides of the active layer 42. Since they are confined in the active layer 42 and efficiently recombined, very high luminous efficiency can be realized.
Further, by adjusting the composition of the active layer 42, a wide range of emission wavelengths from the green to the red region can be realized.
In the light emitting device 1 of FIG. 2, the p-type AlGaI
The nP cladding layer 43 is provided, and the polarity of the current supply is positive on the first electrode 5 side.

Next, a current diffusion layer 44 of the same conductivity type as the first conductivity type clad layer 43 is formed between the first electrode 5 and the first conductivity type clad layer 43. First electrode 5
Is formed so as to cover only a part of the surface of the light-emitting layer portion 4. Therefore, by forming the current diffusion layer 44, the double heterostructure layers 41, 42, and 43 are uniformly formed in the in-plane direction. It is possible to spread the current so that the first electrode 5
A high-luminance light emitting state can be obtained even in a region that is not covered with the light. As a result, not only the direct light in the region but also the intensity of the reflected light from the metal layer 3 is increased, and the light can be efficiently extracted without being hindered by the first electrode 5. Can be increased.

The current diffusion layer 44 can be made of an AlGaAs mixed crystal or an AlGaAsP mixed crystal. AlG
The aAs mixed crystal or AlGaAsP mixed crystal has a small lattice constant difference from GaAs, and has high lattice matching with a GaAs single crystal substrate. Therefore, even if AlGaInP mixed crystal is further epitaxially grown thereon, good matching is maintained. There are easy advantages. In the embodiment of FIG. 2, the current diffusion layer 44 is formed of p ⁺ -type AlGaAsP mixed crystal doped with impurities at a high concentration.

In the light emitting device 1 of FIG. 2, the following numerical values can be exemplified as examples of the thickness of each layer: the first metal layer 31 = 200 nm, the intermediate metal layer 32 = 100n.
m, second metal layer 33 = 200 nm, n-type AlGaInP
Cladding layer 41 = 1000 nm, AlGaInP active layer 42 = 600 nm, p-type AlGaInP cladding layer 41
= 1000 nm, p ⁺ -type AlGaAsP current spreading layer 44
= 1000 nm. Further, for example, the first electrode 5 can be composed of an Au layer and an AuBe layer, and the second electrode 6 can be composed of a Ni layer, and each can have a thickness of about 1000 nm.

Hereinafter, a method for manufacturing the light emitting device 1 of FIG. 1 will be described. First, as shown in FIG. 3A, a first main surface 8 of a GaAs single crystal substrate 61 which is a semiconductor single crystal substrate.
1, as the light emitting layer portion 4, a p ⁺ -type AlGaAsP current diffusion layer 44, a p-type AlGaInP cladding layer 43, an AlG
The aInP active layer 42 and the n-type AlGaInP cladding layer 41 are epitaxially grown in this order. The epitaxial growth of each of these layers is performed by metalorganic vapor phase epitaxy (MOVP).
E) can be performed.

Next, as shown in FIG. 3B, a metal layer 3 is formed on the n-type AlGaInP cladding layer 41 of the light emitting layer section 4.
An AuGe layer (second metal layer) 33, an Al layer (intermediate metal layer) 32, and an Au layer (first metal layer) 31 are formed in this order. The formation of each layer can be performed by a known physical vapor deposition method such as a vacuum vapor deposition method or a sputtering method. Then, the side of the metal layer 3 of the multilayer substrate 63 on which the metal layer 3 is formed as described above is superimposed on the first main surface 7 of the Si single crystal substrate 2 (FIG. 3C).
The joining process is performed by heating to ° C. The heating is performed, for example, in a nitrogen atmosphere. Thereby, Au layer 31 is bonded to main surface 7 of Si single crystal substrate 2. The bonding process is performed, for example, immediately above the Au-Si eutectic temperature (for example, 370 ° C).
To about 400 ° C.).

At the above bonding temperature, the Au layer 31
During the bonding, a part or the whole of the metal forms a eutectic reaction with Si of the Si single crystal substrate 2 to form an Au—Si alloy layer. Au formed
The composition of the -Si alloy layer is, for example, Au-2 to 6 mass% Si.
It is. On the other hand, Al constituting the Al layer 32 generates intermetallic compounds having various compositions with Au, and each of these intermetallic compounds has a joining temperature of 300 ° C. to 500 ° C.
Since a liquid phase is not generated by the eutectic reaction at ℃, alloying with Al is relatively unlikely to occur. As a result, the effect of the alloying of the Au layer 31 and Si during the bonding process is less likely to reach the Au-Ge layer 33 forming the second metal layer, and the Au-Ge
The light reflectivity of the layer 33 can be increased.

When the bonding process is completed, as shown in FIG. 3D, the GaAs single crystal substrate 61 is removed to obtain a light emitting element substrate 1a having a multilayer structure. GaAs
The removal of the single crystal substrate 61 can be performed by, for example, chemical etching. On the other hand, as shown in FIG. 5A, a separation growth layer 62 is formed in advance between the light emitting layer portion 4 and a GaAs single crystal substrate 61 as a semiconductor single crystal substrate.
After bonding the light emitting layer portion 4 to the Si single crystal substrate 2 which is a conductive substrate via the metal layer 3 as shown in FIG.
The light emitting layer section 4 and the GaAs single crystal substrate 61 may be separated by selectively removing the separation growth layer 62 as shown in FIG. In this case, the separation growth layer 62
Is preferably made of a material that can be epitaxially grown on the GaAs single crystal substrate 61 and has higher solubility in a specific etching solution than the light emitting layer portion 4.

For example, when the current diffusion layer 44 is made of an AlGaAs mixed crystal, the separation growth layer 62 can be made of an AlAs single crystal layer. In this case, sulfuric acid / hydrogen peroxide solution (H ₂ SO ₄ / H ₂ O ₂
/ H ₂ O). This etchant has little corrosiveness to the AlGaAs mixed crystal forming the current diffusion layer 44 or the AlGaInP mixed crystal forming the double heterostructure layers 41, 42, and 43, but remarkable corrosiveness to the AlAs single crystal layer. Having. Therefore, the separation growth layer 6
2 is immersed in the etching solution, the separation growth layer 62 is selectively dissolved and removed, and the GaAs single crystal substrate 61 can be easily separated.

The light emitting element substrate 1 a from which the GaAs single crystal substrate 61 has been removed or separated has the first electrode 5 on the current diffusion layer 44 side and the second electrode 6 on the second main surface 8 side of the Si single crystal substrate 2. After forming and dicing, the semiconductor chip is fixed to a support, and the lead wire is wire-bonded and resin-sealed to form a light emitting device 1 shown in FIG.
Is obtained.

In the embodiment shown in FIG. 3, the bonding is performed by bonding the metal layer 3 formed in contact with the first main surface side of the light emitting layer portion 4 to the first main surface 7 of the conductive substrate 2. It was done in On the other hand, in the bonding process, as shown in FIG. 4A, the metal layer 3 formed in contact with the first main surface 7 of the conductive substrate 2 is bonded to the first main surface 82 of the light emitting layer portion 4. It may be performed in the form. In this embodiment, the Au layer 3 is formed on the first main surface 7 of the Si single crystal substrate 2 as the metal layer 3.
1. An Al layer 32 and an AuGe layer 33 are laminated in this order, and the metal layer 3 is brought into direct contact with the first main surface 82 of the light emitting layer portion 4 and heated to perform the bonding process. ing.

Further, as shown in FIG. 4B, the metal layer 32, 33 formed in contact with the first main surface 82 of the light emitting layer portion 4 is replaced with a single crystal Si as a conductive substrate. It can also be carried out in such a manner that it is joined to the metal layer 31 formed in contact with the first main surface 7 of the substrate 2. In the illustrated embodiment, an Al layer 32 serving as an intermediate layer and an Au layer serving as a first metal layer are provided.
A bonding interface is formed with the layer 31.
For example, at the bonding processing temperature, Au of the Au layer 31 is converted to Si.
Reacting with the Si of the single crystal substrate 2 to generate a eutectic melt,
By bringing the eutectic melt into wet contact with the Al layer 32, a good bonding state can be obtained.

As shown in FIGS. 6 and 7, the configuration of the metal layer 3 can be variously modified. In the light emitting device 200 of FIG. 6, the metal layer 3 is formed only of the Au layer 33. However, at least a part of the Au layer 33 is an Au—Si alloy. Further, the light emitting element 210 of FIG. 7 is an example in which the metal layer 3 is formed by two layers of the AuGe alloy layer 33 located on the light emitting layer part 4 side and the Au layer 31 located on the Si single crystal substrate 2 side. is there. In any case, it is desirable to perform the joining process in such a manner that the processing temperature is set to a temperature near or slightly lower than the eutectic temperature of Si-Au.

The light emitting devices 1 and 2 shown in FIGS.
200 and 210 show an example in which both the first conductivity type cladding layer and the current diffusion layer are p-type. However, as shown in FIG.
A configuration with a mold is also possible. In this light emitting element 230,
An Au layer (first metal layer) 31, an Al layer (intermediate metal layer) as a metal layer 3 'on the first main surface 7 of the Si single crystal substrate 2.
32 and an AuBe layer (second metal layer) 33 'are formed in this order. Further, as the light emitting layer portion 4 ′, the p-type AlGaInP clad layer 43 and the AlG
aInP active layer 42, n-type AlGaInP cladding layer 4
1 and n ⁺ -type AlGaAs current diffusion layers 44 ′ are formed. The stacking order of the layers 41, 42, and 43 of the light emitting element 230 is completely opposite to that of the light emitting element 1 of FIG. 1, and the current supply polarity is negative on the first electrode 5 side.

The advantages of adopting this structure are as follows. That is, as shown in FIG.
When the light emitting layer portion 4 is epitaxially grown on the single crystal substrate 61 and bonded to the Si single crystal substrate 2 via the metal layer 3 and then the GaAs single crystal substrate 61 is removed, FIG.
As shown in (b), the obtained light emitting element substrate may be warped. The cause of this warpage is as follows. That is, as shown in FIG. 10, AlGaAs epitaxially grown on a GaAs single crystal substrate 61 is used.
An elastic matching strain for lattice matching with the GaAs single crystal substrate 61 is generated in the s current diffusion layer 44. More specifically, since the lattice constant of AlAs is slightly larger than the lattice constant of GaAs, elastic strain in the in-plane compression direction is generated on the AlGaAs current diffusion layer 44 side. And
When the GaAs single crystal substrate 61 is removed, the elastic strain of the AlGaAs current diffusion layer 44 is released in a form extending in the in-plane direction. As a result, as shown in FIG.
The light emitting element substrate is warped such that the current diffusion layer 44 side is convex. When such a warp occurs,
Cracks may be introduced into the light emitting layer, which is not preferable.

In general, the current diffusion layer 44 has a sufficient current diffusion effect with a smaller thickness in the n-type, in which majority carriers are electrons, than in the p-type, in which holes having a large effective mass are majority carriers. Can be Therefore, GaA
AlGa epitaxially grown on s single crystal substrate 61
As shown in FIG. 10B, the n-type (44 ') As-current diffusion layer is a p-type (4
It can be thinner than 4). When the thickness of the AlGaAs current diffusion layer is reduced, the elastic strain energy released when the GaAs single crystal substrate 61 is removed is also reduced, and the warpage of the substrate that appears as work performed by the released energy can be reduced. . That is, as shown in FIG. 11, by employing a structure in which the first conductivity type cladding layer and the current diffusion layer are n-type, warpage generated in the light emitting element substrate can be reduced.

It should be noted that n ⁺ -type AlG highly doped
The thickness of the current diffusion layer 44 'made of aAs mixed crystal or AlGaAsP mixed crystal is preferably 10 nm to 1000 nm. The thickness of each of the other layers can be the same as that of the light emitting element 1 in FIG.

By appropriately selecting the composition of the current spreading layer 44 and increasing the band discontinuity with the cladding layer in contact with the current spreading layer 44, the current at the heterojunction interface in the light emitting layer section 4 is increased. The diffusion effect can be enhanced. In this case, the thickness of the current diffusion layer 44 can be reduced, which is effective in preventing the resulting light emitting element substrate from warping.

Next, as shown in FIG. 8, the conductive substrate is S
It is also possible to use a metal instead of a semiconductor such as an i single crystal. In the light emitting element 220 shown in FIG.
Al substrate 21 is used. As the metal layer 3, the Au layer 31 is provided on the Al substrate 21 side, and the Au layer 31 is provided on the light emitting layer section 4 side.
It has a two-layer structure in which the u-Ge alloy layer 33 is arranged. By using metal for the conductive substrate 2, the second electrode can be omitted. In addition, as a material of the metal used as the conductive substrate 2, Sn can be used in addition to Al.

In the embodiments shown in FIGS. 4 to 11, the current diffusion layer is formed of an AlGaAs mixed crystal, but may be formed of an AlGaAsP mixed crystal as in FIG.

In the embodiment described above, the conductive substrate 2 is made of a material having substantially no translucency, such as Si single crystal or metal, but the light emitting device shown in FIG. It is also possible to form with a material having a light-transmitting property like 240. In this case, the light passing portion 141 can be formed in the metal layer 3. With this configuration, the light extraction efficiency can be increased by the contribution of both the reflected light from the metal layer 3 and the transmitted light that has entered the light-transmitting conductive substrate 22 via the light transmitting portion 141. Become like In this case, if the second main surface 8 of the translucent conductive substrate 22 is covered with the metal second electrode 6, the second electrode 6
It can also be expected that the reflected light on the surface contributes to improving the light extraction efficiency. As the translucent conductive substrate 22, for example, G
An aP substrate can be used. The laminated structure of the light emitting layer portion 4 and the metal layer 3 can be the same as that shown in FIGS. 2, 7, and 11 except that the light transmitting portion 141 is formed in the metal layer 3.

In order to form the light transmitting portion 141 in the metal layer 3, a method of patterning the metal layer 3 by masking or the like at the time of forming the layer can be adopted. For example, FIG.
As shown in (1), the metal layer 3 can be patterned in a linear shape, and the light passing portions 141 can be formed in a slit shape between adjacent linear metal layer regions. In addition, as shown in FIG. 13B, the metal layer 3 can be patterned in a net shape, and the mesh can be used as the light transmitting portion 141. Further, FIG.
As shown in (c), if the metal layer 3 is patterned in the form of scattered dots or islands, the background portions of the individual metal layer regions can be used as the light passing portions 141.

[Brief description of the drawings]

FIG. 1 is a schematic view showing some examples of a schematic structure of a light emitting element of the present invention.

FIG. 2 is a schematic diagram showing an example of a specific stacked structure of the light emitting element in FIG.

FIG. 3 is an explanatory view showing a first example of a manufacturing process of the light emitting device of FIG. 2;

FIG. 4 is an explanatory view showing a second example.

FIG. 5 is an explanatory diagram showing a third example.

FIG. 6 is a schematic view showing a first modification of a metal layer in the light emitting device of FIG. 2;

FIG. 7 is a schematic view showing a second modified example.

FIG. 8 is a schematic view illustrating an example of a light-emitting element using a metal substrate.

FIG. 9 is a diagram illustrating a state in which a semiconductor light emitting element substrate is warped by removing a semiconductor single crystal substrate after bonding.

FIG. 10 is a view for explaining a difference in layer thickness between a case where the conductivity type of the current diffusion layer is p-type and a case where the conductivity type is n-type.

FIG. 11 shows that the cladding layer and the current diffusion layer on the first electrode side are n
FIG. 4 is a schematic view showing an example of a light emitting element having a shape.

FIG. 12 is a schematic view showing an example of a light-emitting element in which a light-transmitting portion is formed in a metal layer using a light-transmitting conductive substrate and its operation.

FIG. 13 is a schematic view showing various patterns of a light passing portion formed on a metal layer.

FIG. 14 is a schematic view illustrating a structure of a conventional light-emitting element.

FIG. 15 is a schematic diagram showing a light reflection path of the light emitting element of FIG.

[Explanation of symbols]

1, 100, 200, 210, 220, 240 Light-emitting element 2 Conductive substrate 3 Metal layer 4 Light-emitting layer part 5 First electrode 6 Second electrode 21 Metal substrate (conductive substrate) 31 First metal layer 32 Intermediate metal layer 33 Second metal layer 41 n-type AlGaInP cladding layer 42 AlGaInP active layer 43 p-type AlGaInP cladding layer 44 current diffusion layer 61 semiconductor single crystal substrate 141 light passage section

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Nobuhiko Noto, Inventor 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Semiconductor Co., Ltd. F-term in Semiconductor Isobe Laboratory (reference) 5F041 AA03 CA04 CA33 CA34 CA35 CA74 CA77 CA85 CA91 CA92 CA98 CA99 CB15

Claims (20)

[Claims] 1. A metal layer, a light emitting layer portion, and a first electrode are formed in this order on a first main surface side of a conductive substrate, and the metal layer, the light emitting layer portion, and the first electrode are formed on the light emitting layer portion through the first electrode and the conductive substrate. A light-emitting element, which can be energized. 2. The light emitting device according to claim 1, wherein said conductive substrate is a silicon single crystal substrate, and a second electrode is formed on a second main surface side of said silicon single crystal substrate. 3. The light emitting device according to claim 2, wherein the metal layer is formed directly in contact with the silicon single crystal substrate. 4. The light emitting device according to claim 3, wherein said metal layer is formed mainly of Au. 5. The light emitting device according to claim 3, wherein the metal layer includes a first metal layer in contact with the silicon single crystal substrate and a second metal layer in contact with the light emitting layer. 6. The metal layer further includes an intermediate metal layer between the first metal layer and the second metal layer, the intermediate metal layer being in contact with the first metal layer. The light emitting device according to claim 5, wherein a metal component which is more easily alloyed with silicon than a metal component which is a main component of the layer is formed as a main component. 7. The method according to claim 1, wherein the first metal layer is mainly formed of a metal component having a lower eutectic temperature with silicon than a metal component which is a main component of the intermediate metal layer. 7. The light emitting device according to item 6. 8. The light emitting device according to claim 7, wherein said first metal layer is formed mainly of Au, and said intermediate metal layer is formed mainly of Al. 9. The light emitting device according to claim 5, wherein the second metal layer is mainly composed of Au. 10. The light emitting device according to claim 1, wherein the conductive substrate is formed of a material having a light transmitting property, and a light transmitting portion is formed in the metal layer. 11. The light emitting device according to claim 10, wherein the light-transmitting conductive substrate is a GaP substrate. 12. The light emitting layer section, wherein the first conductive type clad layer located on the first electrode side, the second conductive type clad layer located on the metal layer side, and the first conductive type clad layer and Having a double heterostructure layer consisting of an active layer formed between the second conductive type clad layer and a first conductive layer formed between the first electrode and the first conductive type clad layer. 2. The semiconductor device according to claim 1, further comprising: a current diffusion layer.
The light-emitting device according to item 1. 13. The light emitting device according to claim 12, wherein the first conductivity type cladding layer and the current diffusion layer are p-type. 14. The double heterostructure layer is made of AlGaI.
nP mixed crystal, and the current diffusion layer is made of AlGaAs.
The light emitting device according to claim 12, wherein the light emitting device is made of a mixed crystal or an AlGaAsP mixed crystal. 15. A step of epitaxially growing a light emitting layer on a semiconductor single crystal substrate, and a bonding process for bonding a first main surface of the conductive substrate and a first main surface of the light emitting layer only via a metal layer. And a step of separating or removing the semiconductor single crystal substrate in this order. 16. A separation growth layer is previously formed between the light emitting layer section and the semiconductor single crystal substrate, and the light emitting layer section is
16. The semiconductor single crystal substrate is separated from the light emitting layer portion by selectively removing the separation growth layer after bonding to the conductive substrate via the metal layer. A method for manufacturing a light emitting device. 17. The method according to claim 15, wherein the bonding is performed by heating. 18. The bonding process according to claim 17, wherein the metal layer formed in contact with the first main surface of the conductive substrate is bonded to the first main surface of the light emitting layer portion. A method for manufacturing a light emitting device. 19. The bonding process according to claim 17, wherein the metal layer formed in contact with the first main surface of the light emitting layer portion is bonded to the first main surface of the conductive substrate. A method for manufacturing a light emitting device. 20. The bonding process, wherein a metal layer formed in contact with the first main surface of the light emitting layer portion is bonded to a metal layer formed in contact with the first main surface of the conductive substrate. The method for manufacturing a light emitting device according to claim 17, wherein: