JP4062111B2 - Method for manufacturing light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a light emitting device.
[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. A light emitting device in which a light emitting layer portion is formed of a III-V compound semiconductor, for example, an AlGaInP mixed crystal, includes a thin AlGaInP (or GaInP) active layer, an n-type AlGaInP cladding layer having a larger band gap, and a p-type AlGaInP. By adopting a double hetero structure sandwiched between clad layers, 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 element has also been proposed. Therefore, 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 growth GaAs substrate is peeled off, while a reinforcing element substrate (having conductivity) is placed on a peeling surface through a reflective Au layer. A technique for pasting 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, it is difficult to secure the bonding strength when the Au layer forming the reflective layer is bonded to the light emitting layer portion, leading to defects such as peeling, and a good bonding state cannot be obtained. It was difficult to avoid a decrease in reflectivity. Further, when the heat treatment temperature for bonding is increased to increase the bonding strength, the metallurgical reaction between the light emitting layer or the conductive substrate (particularly the Si substrate) and the Au layer becomes remarkable, and the state of the obtained reflecting surface is improved. There is a problem that the deterioration of the reflectance is more likely to be caused.
[0006]
An object of the present invention is to produce a light emitting device having a structure in which a light emitting layer portion and an element substrate are bonded together through a metal layer having an Au layer , and sufficient bonding even when the heat treatment temperature of the bonding is low. An object of the present invention is to provide a method for manufacturing a light emitting element and a light emitting element that can obtain strength and can maintain a favorable state of a reflecting surface.
[0007]
[Means for solving the problems and actions / effects]
In order to solve the above problems, a method for manufacturing a light-emitting element of the present invention includes:
One main surface of a compound semiconductor layer made of a III-V compound semiconductor is used as a light extraction surface, and the other main surface side of the compound semiconductor layer is a reflection surface that reflects light from the light emitting layer portion to the light extraction surface side. An Au layer made of pure Au (which may contain inevitable impurities as long as it is within 1% by mass) , wherein the element substrate is bonded through a metal layer having a metal layer, and the reflective surface of the metal layer includes a reflective surface; In order to manufacture a light emitting device,
The main surface opposite to the light extraction surface of the compound semiconductor layer having the light emitting layer portion is used as a bonding-side main surface, and the bonding semiconductor layer is made of pure Au and forms a reflective surface on the bonding-side main surface . Arrange the first Au layer ,
Further, a light-emitting layer side bonding layer mainly composed of Au is disposed between the first Au layer and the compound semiconductor layer so as to be dispersed on the main surface of the first Au layer. The region where the light emitting layer side bonding layer is not formed is a reflective surface,
The main surface of the element substrate, which is scheduled to be located on the light emitting layer portion side, is used as a bonding-side main surface, and a second Au layer made of pure Au is disposed on the bonding-side main surface,
The first Au layer and the second Au layer are brought into close contact with each other and bonded together by heat treatment at a temperature higher than 180 ° C. and 250 ° C. or lower . In the present specification, “main component” refers to a component having the highest mass content.
[0008]
According to the method of the present invention, the first and second Au layers are formed separately on the compound semiconductor layer side and the element substrate side, and these are adhered and bonded together. Since the Au layers are easily integrated even at a relatively low temperature, sufficient bonding strength can be obtained even when the heat treatment temperature for bonding is low, and the reflective surface of the metal reflective layer including the Au layer is also in a good state Can be easily formed. Since the reflective surface itself is composed of a highly corrosion-resistant Au layer , the light emitting layer growth substrate peeling process and the light emitting layer surface roughening process (so-called frost process) described later are performed during the manufacturing process of the light emitting element. Even when chemical treatment using highly corrosive liquids is applied to the compound semiconductor layer, there is no concern that corrosion will permeate the reflective surface, so the manufacturing process can be simplified and the state of the reflective surface Hard to be damaged.
[0009]
The light emitting layer portion preferably emits visible light having a peak wavelength of 550 nm or more. FIG. 3 is a graph showing the wavelength dependence of the reflectance of the Au layer. It can be seen that there is strong absorption in the visible light region with a wavelength of less than 550 nm. Therefore, when the peak wavelength of the light emitting layer portion is set to 550 nm or more, a decrease in reflectance can be effectively suppressed and the light emission intensity can be improved. In addition, the extracted light spectrum is unlikely to be different from the original emission spectrum due to absorption, and the problem that the emission color tone changes is less likely to occur. From this point of view, desirable color tone and peak wavelength range of light emission of the light emitting layer portion are as follows:
Yellowish green: 550 nm to less than 580 nm Yellow: 580 nm to less than 595 nm Amber: 595 nm to less than 610 nm Orange: 610 nm to less than 630 nm Red: 630 nm to less than 780 nm
As is apparent from FIG. 3, when the peak wavelength of the light emitting layer portion is desirably 580 nm or more, more desirably 600 nm or more, the reflectance is further improved and the emission intensity can be increased. From this point of view, when the light emitting layer portion is yellow, amber, orange or red, the reflectance by the Au layer can be particularly increased, and the effect of improving the light emission intensity becomes remarkable.
[0011]
Specifically, the manufacturing method of the light-emitting element of the present invention includes:
A light emitting layer portion is epitaxially grown on a light emitting layer growth substrate made of a compound semiconductor,
In a state where the substrate for light emitting layer growth is integrated, a first Au layer is formed on the main surface of the light emitting layer bonded side,
On the other hand, a second Au layer is formed on the bonding substrate main surface of the element substrate,
Adhering the first Au layer and the second Au layer in close contact,
After the bonding, a step of peeling the light emitting layer growth substrate from the light emitting layer portion by chemical etching can be employed.
[0012]
According to this step, in a state where the substrate for growing the light emitting layer is integrated, the first Au layer is pasted on the main surface of the light emitting layer bonded side and the second Au layer is pasted on the main surface of the element substrate bonded side. Therefore, the light emitting layer portion formed as a thin layer can be handled for bonding in a form accompanied by mechanical reinforcement by the light emitting layer growth substrate. As a result, for example, compared with the case where a process of peeling the light emitting layer part before bonding is employed, the probability of occurrence of a problem that the light emitting layer part is cracked or chipped is greatly reduced, and the process can be simplified dramatically. . In this case, after bonding, the light emitting layer growth substrate is peeled off from the light emitting layer portion by chemical etching. However, since the portion forming the reflective surface is formed of the Au layer , the influence of chemical etching is affected by the reflective surface. In this way, there is no problem such as peeling of the light emitting layer during etching.
[0013]
For example, when the light emitting layer portion is made of (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1) and the light emitting layer growth substrate is made of a GaAs substrate, Chemical etching can be performed by dissolving the GaAs substrate using an ammonia / hydrogen peroxide mixture. The ammonia / hydrogen peroxide mixture is excellent in selective corrosion of the GaAs substrate with respect to (Al _x Ga _1-x ) _y In _1-y P, and only the GaAs substrate is rapidly and simply immersed in the solution. Peeling and removal can be ensured. Further, there is no concern about corrosion of the Au layer forming the reflective surface. In the present invention, removing all of the light emitting layer growth substrate by etching also belongs to the concept of “peeling”.
[0014]
On the other hand, a GaAs substrate in which a light emitting layer portion made of (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1) forms a growth substrate through an AlAs release layer It can also be grown and chemical etching can be performed in the form of dissolving the AlAs release layer using a solution containing hydrofluoric acid. If the AlAs release layer is dissolved with a solution containing hydrofluoric acid, the GaAs substrate can be easily released from the light emitting layer portion. Further, there is no concern about corrosion of the Au layer forming the reflective surface. In this case, since the GaAs substrate is not dissolved, it can be reused for the growth of the next light emitting layer.
[0015]
Then, when the light emitting layer portion is made of a Group III-V compound semiconductor, a first Au layer and the second Au layer both the Au content as the Au-based metal over 95 wt%, and their first Au layer The second Au layer can be adhered to each other, and in this state, bonding can be performed by performing a bonding heat treatment at a temperature higher than 180 ° C. and 360 ° C. or less. According to this method, the first and second Au layers are formed separately on the compound semiconductor layer side and the element substrate side made of a III-V group compound semiconductor, and these are adhered and bonded together. The first Au layer and the second Au layer are easily bonded by performing a heat treatment of bonding at a temperature higher than 180 ° C. and 360 ° C. or lower because the Au content is 95% by mass or more. Therefore, sufficient bonding strength can easily be obtained, and, at the time of bonding heat treatment, the Au layer diffusion and effects of the reaction is Oyobi difficult from the substrate side or a compound semiconductor layer side with respect to, the metal reflective layer containing Au layer A reflective surface having a good state can be easily formed.
[0016]
[0017]
As described above, the upper limit of the bonding heat treatment temperature is set to 250 ° C. in order to suppress the influence of diffusion and reaction from the substrate side or the compound semiconductor layer side on the Au layer . For example, a Si substrate can be used as the element substrate. The Si substrate can easily ensure sufficient conductivity as a light emitting element by doping, and is inexpensive. However, Si easily diffuses into Au and tends to cause a eutectic reaction at a relatively low temperature (the eutectic temperature of the Au—Si binary system is 363 ° C.). Therefore, if the heat treatment temperature for the bonding becomes too high even a little, Si forming the element substrate diffuses into the Au layer in the metal reflection layer or causes a eutectic reaction, resulting in a significant decrease in reflectivity. Cheap. However, as in the present invention, by setting the heat treatment temperature to 250 ° C. or less by bonding the Au layers together, it is possible to perform the bonding heat treatment at a temperature sufficiently lower than the eutectic temperature, and good reflection The rate and the bonding strength can be ensured.
[0018]
When the compound semiconductor layer on which the first Au layer is formed is composed of a III-V group compound semiconductor, the first Au layer and the second Au layer are brought into close contact with each other and subjected to bonding heat treatment with an external heat source. Heat is transferred to the first Au layer through the compound semiconductor layer, but the III-V group compound semiconductor generally has a lower thermal conductivity than other semiconductors such as Si. For this reason, when the bonding heat treatment temperature is excessively lowered, heat transfer to the first Au layer is inhibited by the III-V group compound semiconductor layer, and a strong bonding state with the second Au layer cannot be obtained. Therefore, in the present invention, by setting the bonding heat treatment temperature higher than 180 ° C., the first Au layer and the second Au layer are formed even though the thermal conductivity of the III-V compound semiconductor layer is not so high. The layers can be bonded with sufficient strength. In particular, when the compound semiconductor layer is composed of at least one group III element selected from Al, Ga and In and the group V element is composed of one or more selected from P and As, the effect is particularly remarkable. .
[0019]
When a Si substrate is used as the element substrate, a substrate side bonding layer is formed on the bonded main surface of the element substrate, a second Au layer is formed so as to cover the substrate side bonding layer, and the substrate side bonding layer and Si Alloying heat treatment with the substrate can be performed. When an n-type Si substrate is used, the substrate-side bonding layer can be composed of an AuSb alloy or an AuSn alloy. In this case, the effect of reducing contact resistance is enhanced by performing the alloying heat treatment between the substrate-side bonding layer and the Si substrate at, for example, 250 ° C. or more and 500 ° C. or less.
[0020]
In the present invention, the reflective surface can be formed by the first Au layer . Since the Au 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 particular, when using a Si substrate, when eutectic reaction between Au of the first Au layer forming the reflective surface and Si forming the Si substrate proceeds, a decrease in reflectance is particularly likely to occur. As a result of suppressing such a defect extremely effectively, a reflective surface having a good reflectance can be formed without any problem by the Au layer .
[0021]
In the method of manufacturing the light emitting device of the present invention, when forming the reflecting surface by Au layer, between the Au layer and the compound semiconductor layer, a light-emitting layer side bonding layer mainly composed of Au, Lord Au layer It can be arranged in a distributed manner on the surface. The Au layer forms a part of a current path to the light emitting layer portion. However, when the Au 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 layer to the light emitting layer portion via an Au-based bonding layer. However, the Au-based bonding layer needs to contain a relatively large amount of alloy components necessary for securing the contact, and the reflectance is slightly inferior. Therefore, the light emitting layer portion side bonding layer if dispersed formed on the main surface of the Au layer can secure a high reflectance by the Au layer in the non-formation region of the light emitting layer side bonding layer.
[0022]
As the light emitting layer portion-side bonding layer, the compound semiconductor layer in contact with the n-type III-V group compound semiconductor (the aforementioned (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 enhanced by adopting the AuGeNi bonding layer. In this case, an AuGeNi bonding layer can be formed on the bonded main surface of the compound semiconductor layer, and the first Au layer can be formed so as to cover the AuGeNi bonding layer. The alloying heat treatment between the AuGeNi bonding 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.
[0023]
In order to increase the light extraction effect sufficiently, the area for forming the light emitting layer side bonding layer in the total area of the formation area ratio of the light emitting layer side bonding layer (Au layer to the Au layer (the first Au layer) divided Is preferably 1% or more and 25% or less. If the formation area ratio of the light emitting layer side bonding layer is less than 1%, the effect of reducing the contact resistance is not sufficient, and if it exceeds 25%, the reflection intensity decreases.
[0024]
By setting the Au content of the Au layer higher than that of the light emitting layer portion side bonding layer, the reflectance of the Au layer can be further increased in the non-formation region of the light emitting layer portion side bonding layer.
[0025]
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.
[0026]
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 a light emitting layer portion 24 is bonded to one main surface of a Si substrate 7 made of n-type Si (silicon) single crystal, which is a conductive substrate constituting an element substrate, with a metal layer 10 interposed therebetween. Have.
[0027]
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 metal layer 10 side. Therefore, the conduction polarity is positive on the metal electrode 9 side. The term “non-doped” as used herein means “does not actively add a 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 ).
[0028]
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 Si single crystal substrate 7 so as to cover the entire surface. When the metal electrode 15 is an Au electrode, an AuSb bonding layer 16 is interposed between the metal electrode 15 and the Si single crystal substrate 7 as a substrate-side bonding layer. Note that an AuSn bonding layer may be used as the substrate-side bonding layer instead of the AuSb bonding layer 16.
[0029]
The Si single crystal substrate 7 is manufactured by slicing and polishing a Si single crystal ingot, and the thickness thereof is, for example, 100 μm or more and 500 μm or less. Then, the light emitting layer portion 24 is bonded with the metal layer 10 interposed therebetween. The metal layer 10 is entirely configured as an Au layer made of pure Au, and the first Au layer 10a in contact with the light emitting layer portion 24 (compound semiconductor layer) and the second Au layer 10b in contact with the Si substrate 7 are bonded together by heat treatment. It is what was pasted together.
[0030]
An AuGeNi bonding layer 32 (for example, Ge: 15% by mass, Ni: 10% by mass) is formed between the light emitting layer part 24 and the first Au layer 10a as the light emitting layer part side bonding layer, and the series of elements. Contributes to resistance reduction. The AuGeNi bonding layer 32 is dispersedly formed on the main surface of the first Au layer 10a, and the formation area ratio thereof is 1% or more and 25% or less. Further, an AuSb bonding layer 31 (for example, Sb: 5% by mass) is interposed between the Si single crystal substrate 7 and the second Au layer 10b as a substrate-side bonding layer. Note that an AuSn bonding layer may be used instead of the AuSb bonding layer 31. The first Au layer 10a, the second Au layer 10b, the AuSb bonding layer 31, and the AuGeNi bonding layer 32 constitute the metal layer 10, which is disposed in contact with both the light emitting layer portion 24 and the Si substrate 7. Yes .
[0031]
The light from the light emitting layer part 24 is extracted in a form in which the light reflected directly from the light extraction surface is superimposed on the light reflected by the metal layer 10. The thickness of the metal layer 10 is preferably 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 reflective effect is saturated, it determines suitably (for example, about 1 micrometer) by balance with cost.
[0032]
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.
[0033]
Next, as shown in step 2, the AuGeNi bonding layer 32 is dispersedly formed on the main surface of the light emitting layer portion 24. After forming the AuGeNi bonding layer 32, an alloying heat treatment is performed in a temperature range of 350 ° C. or more and 500 ° C. or less, and then the first Au layer 10a is formed so as to cover the AuGeNi bonding layer 32. An alloying layer is formed between the light emitting layer portion 24 and the AuGeNi bonding layer 32 by the alloying heat treatment, and the series resistance is greatly reduced. On the other hand, as shown in Step 3, AuSb bonding layers 31 and 16 (which may be AuSn bonding layers as described above) serving as substrate-side bonding layers are formed on both main surfaces of a separately prepared Si single crystal substrate 7 (n-type). Then, an alloying heat treatment is performed in a temperature range of 250 ° C. or more and 359 ° C. or less. Then, the second Au layer 10b is formed on the AuSb bonding layer 31, and the back electrode layer 15 (for example, made of Au-based metal) is formed on the AuSb bonding layer 16. In the above steps, each metal layer can be formed by sputtering or vacuum deposition.
[0034]
Then, as shown in step 4, the second Au layer 10 b on the Si single crystal substrate 7 side is superposed on the first Au layer 10 a formed on the light emitting layer portion 24 and pressed to be higher than 180 ° C. and 250 ° C. or less, for example, by combined thermal treatment bonded at 250 ° C., creating a substrate bonding body 50. The Si single crystal substrate 7 is bonded to the light emitting layer portion 24 via the first Au layer 10a and the second Au layer 10b. Further, the first Au layer 10a and the second Au layer 10b are bonded with sufficient strength by adopting the bonding heat treatment, and become the metal layer 10 together with the AuSb bonding layer 31 and the AuGeNi bonding layer 32. Since both the first Au layer 10a and the second Au layer 10b are mainly composed of Au that is not easily oxidized, the bonding heat treatment can be performed without any problem even in the atmosphere, for example.
[0035]
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 peeled from the stacked body 50a of the light emitting layer portion 24 and the Si single crystal 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.
[0036]
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 peeling off the GaAs single crystal substrate 1. . Thereafter, the semiconductor chip is diced by a normal 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.
[0037]
In addition to using the Si substrate as the element substrate, another conductive substrate, for example, a metal substrate such as Al (including an alloy) can be used.
[0038]
Furthermore, each layer of the light emitting layer portion 24 can also be formed of an 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.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a first embodiment of a light emitting device to which the present invention is applied in a laminated structure.
FIG. 2 is an explanatory view showing an example of a manufacturing process of the light-emitting element of FIG.
FIG. 3 is a graph showing the wavelength dependence of the reflectance of the Au layer.
[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 Si single crystal substrate (element substrate)
9 Metal electrode 10 Au layer 10a First Au layer 10b Second Au layer 24 Light-emitting layer part 31 AuSb layer (substrate-side bonding layer)
32 AuGeNi bonding layer 31 (light emitting layer side bonding layer)
100 light emitting device

Claims (8)

One main surface of the compound semiconductor layer made of a group III-V compound semiconductor is used as a light extraction surface, and the light from the light emitting layer portion is reflected to the light extraction surface side on the other main surface side of the compound semiconductor layer. In order to manufacture a light emitting device in which an element substrate is bonded through a metal layer having a reflective surface, and a portion including the reflective surface of the metal layer is an Au layer made of pure Au .
Bonding made of pure Au that forms the reflecting surface on the bonding-side main surface, with the main surface opposite to the light extraction surface of the compound semiconductor layer having the light-emitting layer portion as the bonding-side main surface For the first Au layer ,
Further, a light emitting layer side bonding layer mainly composed of Au is disposed between the first Au layer and the compound semiconductor layer so as to be dispersed on the main surface of the first Au layer. The region where the light emitting layer part side bonding layer of one Au layer is not formed is the reflective surface,
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 a second Au layer made of pure Au is disposed on the bonding-side main surface,
A method for manufacturing a light emitting element, comprising : bonding the first Au layer and the second Au layer in close contact with each other by performing a bonding heat treatment at a temperature higher than 180 ° C. and 250 ° C. or lower .   The method for manufacturing a light-emitting element according to claim 1, wherein the light-emitting layer portion emits visible light having a peak wavelength of 550 nm or more. The light emitting layer portion is epitaxially grown on a light emitting layer growth substrate made of a compound semiconductor,
In the state where the light emitting layer growth substrate is integrated, the first Au layer is formed on the bonded main surface of the light emitting layer portion,
On the other hand, the second Au layer is formed on the bonding side main surface of the element substrate,
Adhering the first Au layer and the second Au layer together,
3. The method for manufacturing a light emitting element according to claim 1, wherein after the bonding, the substrate for growing a light emitting layer is peeled off from the light emitting layer portion by chemical etching. The light emitting layer portion is made of (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1), and the light emitting layer growth substrate is made of a GaAs substrate,
4. The method for manufacturing a light-emitting element according to claim 3, wherein the chemical etching is performed by dissolving the GaAs substrate using an ammonia / hydrogen peroxide mixture. The light emitting layer portion made of (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1) forms the light emitting layer growth substrate via the AlAs release layer. Grown on a GaAs substrate,
4. The method for manufacturing a light-emitting element according to claim 3, wherein the chemical etching is performed in such a manner that the AlAs release layer is dissolved using a solution containing hydrofluoric acid. 2. The compound semiconductor layer according to claim 1, wherein the group III element is composed of one or more selected from Al, Ga and In, and the group V element is composed of one or more selected from P and As. 6. The method for producing a light-emitting element according to any one of 5 above . The manufacturing method of the light emitting element of any one of Claim 1 thru | or 6 which comprises the said element substrate by Si substrate . A substrate-side bonding layer is formed on the bonded main surface of the element substrate made of an Si substrate, the second Au layer is formed so as to cover the substrate-side bonding layer, and the substrate-side bonding layer and The method for manufacturing a light-emitting element according to claim 1, wherein alloying heat treatment with the Si substrate is performed .

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