JP4110524B2 - Light emitting device and method for manufacturing light emitting device - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a light emitting device and a method for manufacturing the same.
[0002]
[Prior art]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-66455 [Patent Document 2]
Japanese Patent Laid-Open No. 2001-339100
As a result of many years of progress in materials and element structures used in light-emitting elements such as light-emitting diodes and semiconductor lasers, the photoelectric conversion efficiency inside the elements is gradually approaching the theoretical limit. Therefore, when an element with higher luminance is to be obtained, the light extraction efficiency from the element is extremely important. For example, in a light emitting device having a light emitting layer portion formed of AlGaInP mixed crystal, a thin AlGaInP (or GaInP) active layer is sandwiched between an n-type AlGaInP cladding layer and a p-type AlGaInP cladding layer having a larger band gap. By adopting a sandwiched double hetero structure, a high-luminance element can be realized. Such an AlGaInP double heterostructure can be formed by epitaxially growing each layer of an AlGaInP mixed crystal on a GaAs single crystal substrate by utilizing the lattice matching of the AlGaInP mixed crystal with GaAs. When this is used as a light emitting element, a GaAs single crystal substrate is usually used as an element substrate as it is. However, since the AlGaInP mixed crystal constituting the light emitting layer has a larger band gap than GaAs, 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 (for example, Patent Document 1) in which a reflective layer made of a semiconductor multilayer film is inserted between a substrate and a light emitting layer portion has also been proposed. Since the difference is used, only light incident at a limited angle is reflected, and a significant improvement in light extraction efficiency cannot be expected in principle.
[0004]
Therefore, in various publications including Patent Document 2, a GaAs substrate for growth is peeled off, while a conductive element substrate for reinforcement (made of a semiconductor or metal) is used as a reflective Au substrate. A technique for bonding to a release surface through a layer is disclosed. This Au layer has an advantage that the reflectivity is high and the dependency of the reflectivity on the incident angle is small.
[0005]
[Problems to be solved by the invention]
However, in the above method, problems such as peeling and a decrease in reflectance tend to occur in the Au layer that forms the reflective layer during bonding. In particular, when the element substrate is made of a semiconductor, a metallurgical reaction such as a eutectic is likely to occur between the element substrate component such as Si and the Au layer component during the bonding heat treatment, which causes the above-mentioned problem. Becomes even more prominent.
[0006]
An object of the present invention is to effectively prevent a metallurgical reaction between an element substrate and a metal layer during a bonding heat treatment in a light emitting element having a structure in which a light emitting layer portion and an element substrate are bonded via a metal layer. It is possible to provide a light-emitting element having a structure in which defects due to bonding strength and reflectance due to the reaction are less likely to occur, and a method for manufacturing the light-emitting element.
[0007]
[Means for solving the problems and functions / effects of the invention]
In order to solve the above-described problems, the light-emitting element of the present invention includes:
The first main surface of the compound semiconductor layer having the light emitting layer portion is used as a light extraction surface, and the second main surface side of the compound semiconductor layer is a reflecting surface that reflects light from the light emitting layer portion to the light extraction surface side. A light emitting device in which an element substrate is bonded through a main metal layer having
The element substrate is entirely composed of the conductive material, and at least a portion including the main surface on the main metal layer side of the element substrate is composed of a conductive material mainly composed of an inorganic conductive phase made of carbon. is Rutotomoni, the light emitting layer portion is characterized by being formed by AlGaInP mixed crystal.
In the present specification, “main body” means a component having the highest mass content, and “phase” means a uniform part of a material system that is distinguished from others by physical boundaries. Further, in this specification, the “main metal layer” is a metal layer located between the compound semiconductor layer and the element substrate, and forms a reflective surface and also serves to bond the compound semiconductor layer and the element substrate. The metal layer that bears Therefore, the bonding metal layer described later does not belong to the main metal layer.
[0008]
According to the light emitting element of the present invention, since the element substrate is the contact surface between the main metal layer is composed of a conductive material mainly composed of inorganic conductive phase consisting of carbon (C), carbon in the molecule Due to the strong covalent bond, the metallurgical reaction with the main metal layer hardly occurs. Therefore, it is possible to prevent a decrease in reflectance on the reflecting surface.
[0009]
Further, in order to obtain light emission intensity in the light emitting element, it is desirable to flow as much current as possible through the light emitting layer portion. Therefore, the element substrate is required to have conductivity that can withstand the element substrate, and further, thermal conductivity (role as a heat sink) that can sufficiently dissipate heat generated by a large current is also required. Since carbon or silicon carbide is excellent in conductivity and thermal conductivity, such an element substrate can be realized by configuring the entire element substrate with the conductive material. In general, carbon and silicon carbide have conductivity and thermal conductivity close to metals. Note that the conductivity of silicon carbide is slightly inferior to carbon and is classified as a semiconductor.
[0010]
The conductive material may be a composite material of an inorganic conductive phase and a metal. Such a composite material has better conductivity and thermal conductivity than the inorganic conductive phase (carbon or silicon carbide) alone. Further, the strength and workability are excellent, and it can be suitably used as an element substrate.
[0011]
In addition, the composite material can have a structure in which a metal is dispersed in a substrate made of an inorganic conductive phase. By using such a structure, elements having uniform characteristics such as conductivity and thermal conductivity can be obtained. A substrate can be obtained. Specifically, the composite material is characterized in that a porous substrate made of an inorganic conductive phase is impregnated with a metal. This can be obtained, for example, by impregnating a molten substrate made of an inorganic conductive phase (carbon or silicon carbide) with a molten metal by a known melt forging method. In addition, by using a porous substrate, a strong metal layer can be obtained by an anchor effect when the metal layer is formed on the surface of the composite material by means such as sputtering or vacuum deposition.
[0012]
Regarding the metal contained in the composite material, specifically, when the inorganic conductive phase is carbon, one or more metals selected from Al, Cu and Mg can be the main component, and the inorganic conductive phase When the phase is silicon carbide, the main component can be one or more metals selected from Al and Cu. As described above, a light-emitting element having an element substrate that is excellent in conductivity and thermal conductivity and further excellent in strength and workability can be obtained.
[0013]
Next, in the light emitting device of the present invention, the main metal layer may have an Au-based bonding layer containing Au as a main component. With such a configuration, the bond strength between the compound semiconductor layer and the element substrate can be increased. Details will be described later.
[0014]
Further, in the light emitting element having the Au-based coupling layer, the reflecting surface can be formed by the Au-based coupling layer. Since the Au-based bonding layer is chemically stable and does not easily cause reflectance deterioration due to oxidation or the like, it is suitable as a material for forming the reflecting surface. In the present invention, the element substrate is made of a conductive material mainly composed of an inorganic conductive phase made of carbon or silicon carbide, so that the metallurgical reaction between the element substrate and the Au-based bonding layer is extremely effectively performed. Since it can be suppressed, a reflective surface with good reflectance can be formed by the Au-based coupling layer.
[0015]
When a reflective surface is formed by an Au-based bonding layer, a bonding metal layer containing Au as a main component is disposed between the Au-based bonding layer and the compound semiconductor layer so as to be dispersed on the main surface of the Au-based bonding layer. can do. The Au-based coupling layer forms a part of the energization path to the light emitting layer portion. However, when the Au-based bonding layer is directly bonded to the light emitting layer portion made of a compound semiconductor, the contact resistance increases, the series resistance increases, and the light emission efficiency may decrease. Contact resistance can be reduced by bonding the Au-based bonding layer to the light emitting layer portion via the Au-based bonding metal layer. However, the Au-based bonding metal layer needs to contain a relatively large amount of alloy components necessary for securing a contact, and the reflectance is slightly inferior. Therefore, if the bonding metal layer is dispersedly formed on the main surface of the Au-based bonding layer, a high reflectance by the Au-based bonding layer can be ensured in the region where the bonding metal layer is not formed.
[0016]
As the bonding metal layer, a compound semiconductor layer in contact with the n-type III-V group compound semiconductor (for example, (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, In the case of 0 ≦ y ≦ 1)), the effect of reducing the contact resistance is particularly enhanced by adopting the AuGeNi bonded metal layer. In this case, an AuGeNi bonding metal layer can be formed on the bonded main surface of the compound semiconductor layer, and an Au-based bonding layer (the first Au-based layer) can be formed so as to cover the AuGeNi bonding metal layer. In this case, the alloying heat treatment of the AuGeNi bonding metal layer and the compound semiconductor layer is performed at, for example, 350 ° C. or more and 500 ° C. or less, thereby enhancing the contact resistance reduction effect.
[0017]
In order to sufficiently enhance the light extraction effect, the formation area ratio of the bonding metal layer to the Au-based bonding layer (the value obtained by dividing the formation area of the bonding metal layer by the total area of the Au-based bonding layer) is 1 % Or more and 25% or less is desirable. If the formation area ratio of the bonding metal layer is less than 1%, the effect of reducing the contact resistance is not sufficient, and if it exceeds 25%, the reflection intensity decreases. In addition, the Au-based bonding layer can further increase the reflectance of the Au-based bonding layer in the non-formed region of the bonding metal layer by setting the Au content higher than that of the bonding metal layer.
[0018]
On the other hand, in the light emitting element having the Au-based bonding layer, the reflective surface may be formed of an Ag-based layer mainly composed of Ag interposed between the Au-based bonding layer and the compound semiconductor layer. The Ag-based layer is less expensive than the Au-based bonding layer and exhibits a good reflectance over almost the entire wavelength range of visible light (350 nm to 700 nm), and therefore the wavelength dependency of the reflectance is small. As a result, high light extraction efficiency can be realized regardless of the emission wavelength of the element. Further, compared to a metal such as Al, the reflectance is less likely to decrease due to the formation of an oxide film or the like.
[0019]
FIG. 6 shows the reflectivity of various mirror-polished metal surfaces. The plot point “■” indicates the reflectivity of Ag, the plot point “Δ” indicates the reflectivity of Au, and the plot point “♦” indicates the reflectivity. It is the reflectance (comparative example) of Al. The plotted point “×” is for the AgPdCu alloy. The reflectance of Ag is particularly good at a reflectance of 350 nm to 700 nm (and an infrared region longer than that), particularly 380 nm to 700 nm.
[0020]
On the other hand, Au is a colored metal, and as is apparent from the reflectance shown in FIG. 6, absorption is in the visible light region with a wavelength of 570 nm or less (particularly 550 nm or less), and the peak emission wavelength of the light emitting layer portion is 570 nm or less. If present, reflectivity is reduced. As a result, the emission intensity is likely to decrease, and the extracted light spectrum is different from the original emission spectrum due to absorption, and the emission color tone is likely to change. However, Ag has a very good reflectance even in a visible light region having a wavelength of 570 nm or less. That is, when the peak emission wavelength of the light emitting layer portion is 570 nm or less (particularly 550 nm or less, and further 500 nm or less), the reflection surface of the Ag-based layer can realize higher light extraction efficiency than the Au-based metal.
[0021]
On the other hand, as shown in FIG. 6, Al does not cause an absorption peak in the reflectance, but does not occur, but the reflectance in the visible light region is somewhat low (for example, 85) because of a decrease in reflectance due to oxide film formation. -92%). However, since Ag-based metal is difficult to form an oxide film, a higher reflectance than Al can be secured in the visible light region. Specifically, it can be seen that the reflectance is better than that of Al at a wavelength of 400 nm or more (especially 450 nm or more).
[0022]
The reflectivity of Al in FIG. 6 was measured on a mirror-finished Al surface with the formation of a surface oxide film suppressed by mechanical polishing and chemical polishing, and in actuality, a thick oxide film was formed. As a result, there is a possibility that the reflectance is further lowered than the data shown in FIG. In the case of Ag, in FIG. 6, the reflectance is inferior to Al in a short wavelength region of 350 nm or more and 400 nm or less, but an oxide film is much less likely to be formed than Al. Therefore, when it is actually formed as a reflective metal layer on the light emitting element, it is possible to achieve a reflectance higher than that of Al even in this wavelength region by adopting an Ag-based layer. Even in this wavelength region, the reflectance of Ag is higher than that of Au.
[0023]
In summary, the Ag-based layer has a light extraction efficiency of a light emitting layer portion having a peak emission wavelength in a wavelength region of 350 nm to 700 nm (preferably 400 nm to 570 nm, more preferably 450 nm to 550 nm). It can be said that the improvement effect becomes particularly remarkable. The light emitting layer portion having the above peak emission wavelength is, for example, (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1) or In _x Ga _y Al _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1), a double layer in which the first conductive type cladding layer, the active layer, and the second conductive type cladding layer are stacked in this order. It can be configured as having a heterostructure.
[0024]
In the case of using an Ag-based layer for reflection surface formation, an Ag-based bonding metal layer mainly composed of Ag is disposed between the Ag-based layer and the compound semiconductor layer so as to be dispersed on the main surface of the Ag-based layer. be able to. In the Ag-based junction metal layer, the compound semiconductor layer in contact with the n-type III-V group compound semiconductor (for example, (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1 , 0 ≦ y ≦ 1)), the effect of reducing the contact resistance is particularly high by adopting the AgGeNi bonded metal layer. The formation area ratio of the Ag-based bonding metal layer to the Ag-based layer is desirably 1% or more and 25% or less, like the Au-based bonding metal layer described above.
[0025]
Next, the manufacturing method of the light emitting device of the present invention having the Au-based bonding layer is as follows.
The main surface opposite to the light extraction surface of the compound semiconductor layer is the main surface of the bonding side, and the first Au to be the Au-based bonding layer, which is mainly composed of Au, on the main surface of the bonding side Place the system layer,
The main surface of the element substrate that is scheduled to be located on the light emitting layer side is used as a bonding-side main surface. On the bonding-side main surface, the Au-based coupling layer that is mainly composed of Au is formed. Two Au-based layers are arranged,
The first Au-based layer and the second Au-based layer are adhered and bonded together.
[0026]
When the element substrate and the compound semiconductor layer are bonded together, the element substrate and the compound semiconductor layer are preferably overlapped with each other through an Au-based bonding layer and bonded and heat-treated in that state.
[0027]
According to these production methods of the present invention, the first and second Au-based bonding layers are formed separately on the compound semiconductor layer side and the element substrate side, and these are adhered to each other and bonded together. Since the Au-based bonding layers are easily integrated even at a relatively low temperature, a sufficient bonding strength can be obtained even if the heat treatment temperature for the bonding is low.
[0028]
In the present invention, as a specific method for forming the metal layer, in addition to a vapor deposition method such as vacuum deposition or sputtering, an electrochemical deposition method such as electroless plating or electrolytic plating may be employed. it can.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram showing a light emitting device 100 according to an embodiment of the present invention. The light emitting element 100 has a structure in which the light emitting layer portion 24 is bonded to the first main surface of the metal-impregnated carbon substrate 7 constituting the element substrate via the main metal layer 10.
[0030]
The light emitting layer portion 24 includes the active layer 5 made of a non-doped (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 0.55, 0.45 ≦ y ≦ 0.55) mixed crystal. , the first-conductivity-type cladding layer, in this embodiment the p-type cladding layer 6 made of p-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1), wherein the first conductivity type the second-conductivity-type cladding layer different from the clad layer, in this embodiment interposed by an n-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1) n-type cladding layer 4 made of According to the composition of the active layer 5, the emission wavelength can be adjusted in the green to red region (the emission wavelength (peak emission wavelength) is 550 nm or more and 670 nm or less). In the light emitting device 100, the p-type AlGaInP cladding layer 6 is disposed on the metal electrode 9 side, and the n-type AlGaInP cladding layer 4 is disposed on the main metal layer 10 side. Therefore, the conduction polarity is positive on the metal electrode 9 side. The term “non-dope” as used herein means “does not actively add dopant”, and contains a dopant component inevitably mixed in a normal manufacturing process (for example, 10 ¹³ to 10 ¹⁶ / cm 3). It is not excluded that the upper limit is about ³ ).
[0031]
A current diffusion layer 20 made of AlGaAs is formed on the main surface of the light emitting layer 24 opposite to the surface facing the substrate 7, and the light emitting layer 24 emits light at substantially the center of the main surface. A metal electrode (for example, Au electrode) 9 for applying a driving voltage is formed so as to cover a part of the main surface. A region around the metal electrode 9 on the main surface of the current diffusion layer 20 forms a light extraction region from the light emitting layer portion 24. Further, a metal electrode (back electrode: for example, an Au electrode) 15 is formed on the back surface of the metal-impregnated carbon substrate 7 so as to cover the entire surface.
[0032]
The metal-impregnated carbon substrate 7 is manufactured by impregnating porous carbon (C) with a molten metal (for example, Al) by a known molten metal forging method, and the thickness thereof is, for example, 100 μm or more and 500 μm or less. . Instead of the metal-impregnated carbon substrate 7, a metal-impregnated silicon carbide substrate manufactured by a method similar to the above using porous silicon carbide (SiC) can be used as an element substrate.
[0033]
The metal-impregnated carbon substrate 7 is bonded to the light emitting layer portion 24 with the main metal layer 10 interposed therebetween. The main metal layer 10 is entirely configured as an Au-based bonding layer. In this embodiment, the Au-based bonding layer is made of pure Au or an Au alloy having an Au content of 95% by mass or more.
[0034]
An AuGeNi bonding metal layer 32 (for example, Ge: 15% by mass, Ni: 10% by mass) is formed as a bonding metal layer between the light emitting layer portion 24 and the main metal layer 10 to reduce the series resistance of the element. Contributing. The AuGeNi bonding metal layer 32 is formed in a dispersed manner on the main surface of the main metal layer 10, and the formation area ratio thereof is 1% or more and 25% or less.
[0035]
The light from the light emitting layer portion 24 is extracted in a form in which the light reflected directly from the main metal layer 10 is superimposed on the light emitted directly to the light extraction surface side. The thickness of the main metal layer 10 is desirably 80 nm or more in order to ensure a sufficient reflection effect. Moreover, although there is no restriction | limiting in particular in the upper limit of thickness, since a reflection effect is saturated, it determines suitably (for example, 1 micrometer or less) by balance with cost.
[0036]
Hereinafter, a method for manufacturing the light emitting device 100 of FIG. 1 will be described.
First, as shown in Step 1 of FIG. 2, a p-type GaAs buffer layer 2 is made of, for example, 0.5 μm and AlAs on the main surface of a GaAs single crystal substrate 1 which is a semiconductor single crystal substrate forming a light emitting layer growth substrate. The peeling layer 3 is epitaxially grown in this order, for example, 0.5 μm, and the current diffusion layer 20 made of p-type AlGaAs is, for example, 5 μm. Thereafter, a 1 μm p-type AlGaInP cladding layer 6, a 0.6 μm AlGaInP active layer (non-doped) 5, and a 1 μm n-type AlGaInP cladding layer 4 are epitaxially grown in this order as the light emitting layer portion 24.
[0037]
Next, as shown in step 2, the AuGeNi bonding metal layer 32 is dispersedly formed on the main surface of the light emitting layer portion 24. After the AuGeNi bonding metal layer 32 is formed, an alloying heat treatment is then performed in a temperature range of 350 ° C. or more and 500 ° C. or less. Thereafter, the first Au-based layer 10 a is formed so as to cover the AuGeNi bonding metal layer 32. An alloying layer is formed between the light emitting layer portion 24 and the AuGeNi bonding metal layer 32 by the alloying heat treatment, and the series resistance is greatly reduced. On the other hand, as shown in Step 3, a separately prepared metal-impregnated carbon substrate 7 is formed with a second Au-based layer 10b on one main surface, and a back electrode layer 15 (for example, an Au-based material) on the other main surface. Made of metal). In the above steps, each metal layer can be formed by sputtering or vacuum deposition.
[0038]
Then, as shown in step 4, the second Au-based layer 10b on the metal-impregnated carbon substrate 7 side is superposed on the first Au-based layer 10a formed on the light emitting layer portion 24 and pressed, for example, at 200 ° C. The substrate bonded body 50 is made by performing a heat treatment for bonding at. The metal-impregnated carbon substrate 7 is bonded to the light emitting layer portion 24 via the first Au-based layer 10a and the second Au-based layer 10b. Further, the first Au-based layer 10a and the second Au-based layer 10b are integrated by the bonding heat treatment to become the main metal layer 10. Since both the first Au-based layer 10a and the second Au-based layer 10b are mainly composed of Au that is difficult to oxidize, the bonding heat treatment can be performed without any problem even in the atmosphere, for example.
[0039]
In the present embodiment, since the element substrate is constituted by the metal-impregnated carbon substrate 7 mainly composed of carbon having a strong covalent bond, the metal-impregnated carbon substrate 7 and the main metal layer 10 (Au-based bonding layer) that are in contact with each other. There is no metallurgical reaction between the two. Therefore, the reflective surface of the main metal layer 10 (Au-based coupling layer) finally obtained can realize a good reflectance.
[0040]
Next, proceeding to step 5, the substrate bonded body 50 is immersed in an etching solution made of, for example, a 10% hydrofluoric acid aqueous solution, and the AlAs release layer 3 formed between the buffer layer 2 and the light emitting layer portion 24 is selected. By etching, the GaAs single crystal substrate 1 (which is opaque to the light from the light emitting layer portion 24) is removed from the stacked body 50a of the light emitting layer portion 24 and the metal-impregnated carbon substrate 7 bonded thereto. . It should be noted that an etch stop layer made of AlInP is formed in place of the AlAs release layer 3, and a GaAs single crystal is used by using a first etching solution (for example, ammonia / hydrogen peroxide mixed solution) having selective etching properties with respect to GaAs. Etch and remove the substrate 1 together with the GaAs buffer layer 2 and then etch stop using a second etchant that has selective etching properties with respect to AlInP (for example, hydrochloric acid: hydrofluoric acid may be added to remove the Al oxide layer) A step of etching away the layer can also be employed.
[0041]
Then, as shown in step 6, a wire bonding electrode 9 (bonding pad: FIG. 1) is formed so as to cover a part of the main surface of the current diffusion layer 20 exposed by removing the GaAs single crystal substrate 1. . Thereafter, the semiconductor chip is diced by an ordinary method, and this is fixed to a support and wire bonding of a lead wire is performed, followed by resin sealing to obtain a final light emitting element.
[0042]
In the above embodiment, the first Au-based layer 10a forms a reflective surface, but the Ag-based layer 10c is interposed between the first Au-based layer 10a and the light-emitting layer portion 24 as in the light-emitting element 200 of FIG. Can also be inserted. In this case, the bonding metal layer is formed by dispersing an Ag-based bonding metal layer 132 made of AgGeNi (for example, Ge: 15 mass%, Ni: 10 mass%) instead of the Au-based bonding metal layer. Other parts are the same as those of the light emitting device 100 of FIG. FIG. 4 shows an example of the manufacturing process. The difference from the manufacturing process of FIG. 2 is that the Ag-based bonding metal layer 132 is dispersedly formed in Step 2 instead of the Au-based bonding metal layer 32, and alloying heat treatment is performed in a temperature range of 350 ° C. or higher and 660 ° C. or lower. Thereafter, the Ag-based layer 10c and the first Au-based layer 10a are formed in this order. The rest is basically the same as FIG.
[0043]
In addition, when the Ag-type layer 10c may be corroded by the etching solution when the light emitting layer growth substrate is removed by etching, the following method is preferable. That is, as shown in step 3, the first Au-based layer 10a in contact with the Ag-based layer 10c is arranged such that the outer peripheral edge of the Ag-based layer 10c is located on the inner side than the outer peripheral edge of the first Au-based layer 10a. It is formed in a larger area than the Ag-based layer 10c. As a result, the Ag-based layer 10c is wrapped in the first Au-based layer 10a, and the outer peripheral surface of the Ag-based layer 10c is protected by the outer peripheral edge portion 10e of the first Au-based layer 10a having high corrosion resistance. In FIG. 5, even if the light emitting layer growth substrate (GaAs single crystal substrate 1) is etched, the influence is less likely to affect the Ag-based layer 10c. When the GaAs single crystal substrate 1 is used as a light emitting layer growth substrate and dissolved / removed using an ammonia / hydrogen peroxide mixed solution as an etching solution, Ag is particularly easily corroded by the etching solution. Can be used to dissolve and remove the GaAs single crystal substrate 1 without problems.
[0044]
Moreover, each layer of the light emitting layer part 24 can also be formed by AlGaInN mixed crystal. For example, a sapphire substrate (insulator) or a SiC single crystal substrate is used as the light emitting layer growth substrate for growing the light emitting layer portion 24 instead of the GaAs single crystal substrate. In the above embodiment, each layer of the light emitting layer portion 24 is in the order of the n-type cladding layer 4, the active layer 5, and the p-type cladding layer 6 from the substrate side. The clad, the active layer, and the n-type clad layer may be formed in this order.
[0045]
Further, as shown in FIG. 5 (Step 3), the main metal layer 10 is formed on either side of the metal-impregnated carbon substrate (element substrate) 7 and the light emitting layer portion (compound semiconductor layer) 24 (in FIG. 5, the light emitting layer). It may be formed and bonded only on the part 24 side). In this case, the bonding heat treatment temperature (step 4) must be set to 200 ° C. or more and 700 ° C. or less, which is slightly higher than that in FIG.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a first embodiment of a light emitting device to which the present invention is applied, in a laminated structure.
2 is an explanatory diagram showing an example of a manufacturing process of the light-emitting element shown in FIG.
FIG. 3 is a schematic diagram showing a second embodiment of a light-emitting element to which the present invention is applied, in a laminated structure.
4 is an explanatory diagram showing an example of a manufacturing process of the light-emitting element shown in FIG. 3;
5 is an explanatory diagram showing another example of the manufacturing process of the light-emitting element shown in FIG. 1. FIG.
FIG. 6 is a diagram showing the reflectance of various metals.
[Explanation of symbols]
1 GaAs single crystal substrate (light emitting layer growth substrate)
4 n-type cladding layer (second conductivity type cladding layer)
5 active layer 6 p-type cladding layer (first conductivity type cladding layer)
7 Metal-impregnated carbon substrate (element substrate)
9 Metal electrode 10 Main metal layer 10a First Au-based layer 10b Second Au-based layer 10c Ag-based layer 24 Light emitting layer portion 32 AuGeNi bonded metal layer 132 AgGeNi bonded metal layer 100, 200 Light emitting element

Claims (6)

The first main surface of the compound semiconductor layer having the light emitting layer portion is used as a light extraction surface, and the second main surface side of the compound semiconductor layer is a reflecting surface that reflects light from the light emitting layer portion to the light extraction surface side. A light emitting device in which an element substrate is bonded through a main metal layer having
The element substrate is entirely composed of the conductive material, and at least a portion including the main surface on the main metal layer side of the element substrate is composed of a conductive material mainly composed of an inorganic conductive phase made of carbon. is Rutotomoni,
The light emitting element is characterized in that the light emitting layer portion is formed of AlGaInP mixed crystal . The light emitting device according to claim 1 , wherein the main metal layer has an Au-based coupling layer containing Au as a main component. The light-emitting element according to claim 2 , wherein the Au-based coupling layer is formed with the reflective surface. The light emitting device according to claim 2 , wherein an Ag-based layer mainly composed of Ag interposed between the Au-based bonding layer and the compound semiconductor layer forms the reflective surface. A method for manufacturing a light emitting device according to any one of claims 2 to 4 ,
The main surface opposite to the light extraction surface of the compound semiconductor layer is used as a bonding-side main surface, and the Au-based bonding layer that is mainly composed of Au is formed on the bonding-side main surface. One Au-based layer,
The main surface of the element substrate that is scheduled to be located on the light emitting layer portion side is used as a bonding-side main surface, and the Au-based coupling layer mainly composed of Au is formed on the bonding-side main surface; Arrange the second Au-based layer to be
A method for manufacturing a light emitting device, wherein the first Au-based layer and the second Au-based layer are adhered and bonded together. The element substrate and the compound semiconductor layer are bonded to each other by superimposing the element substrate and the compound semiconductor layer through the Au-based bonding layer and performing a bonding heat treatment in that state. Item 6. A method for manufacturing a light-emitting element according to Item 5 .

Images