JP2011023703A - Epitaxial substrate, light-emitting element, light-emitting device, and method for producing epitaxial substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epitaxial substrate which is capable of providing a light-emitting element which enables a current to uniformly flow by application of a voltage and is capable of obtaining a large uniform light emission output, to provide the light emitting element using the epitaxial substrate, to provide a light emitting device including the light emitting element, and to provide a method for producing the epitaxial substrate. <P>SOLUTION: The light-emitting element 200 includes a transparent supporting substrate 1, an adhesive layer 2 that is arranged on one main surface of the transparent supporting substrate 1, a transparent conductive layer 3 that is arranged on the main surface of the adhesive layer 2, the main surface being on the reverse side of another main surface that faces the transparent supporting substrate 1, and an epitaxial layer 4 that is arranged on the main surface of the transparent conductive layer 3, the main surface being on the reverse side of another main surface that faces the adhesive layer 2. A part of the second main surface of the transparent conductive layer 3 is exposed, the second main surface being on the reverse side of the first main surface that faces the adhesive layer 2. The light-emitting element 200 is additionally provided with electrodes 9, 10 which are formed on the exposed second main surface and the main surface of the epitaxial layer 4 respectively, the main surface being on the reverse side of another main surface that faces the transparent conductive layer 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an epitaxial substrate, a light emitting element, a light emitting device, and a method for manufacturing an epitaxial substrate.

  A semiconductor light emitting device (LED) that takes out energy released as light by recombination of holes supplied by a p-type semiconductor layer constituting a semiconductor layer and electrons supplied by an n-type semiconductor layer in a light emitting layer It is used in a wide range of applications such as optical displays and traffic lights. In order to improve the efficiency of outputting light emitted from the semiconductor light emitting element and increase the intensity of the output light, various devices have been conventionally made.

  For example, in the following Japanese Patent Application Laid-Open No. 2002-134785 (Patent Document 1), a semiconductor layer that emits light formed on one main surface of a semiconductor substrate and transparency to the light emitted by the semiconductor layer are disclosed. And a transparent substrate having a heat-bonding technique. Here, the main surface means a main surface having the largest area among the surfaces.

  A method for manufacturing a semiconductor light-emitting element that can improve the efficiency of outputting light to be emitted using the substrate thus formed is disclosed. In the manufacturing method disclosed herein, after the semiconductor layer and the transparent substrate are joined, the semiconductor substrate used to form the semiconductor layer is removed. For this reason, it can suppress that the said semiconductor substrate absorbs the light which a semiconductor layer light-emits, and can raise the output intensity of light.

  In the following Japanese Patent Application Laid-Open No. 2002-246640 (Patent Document 2), the following is disclosed as a semiconductor substrate for forming a semiconductor light emitting element. That is, a semiconductor layer that emits light formed on one main surface of the semiconductor substrate and a transparent substrate that is transparent to the light emitted from the semiconductor layer are bonded using a resin. Specifically, the resin is a transparent adhesive material such as BCB resin or epoxy resin. A substrate bonded using such a resin material is strong due to the effect of the resin material having excellent elasticity even if the surface roughness of the main surface of the semiconductor layer to be bonded is large (that is, the main surface is rough). To be joined.

  Furthermore, in the following Japanese Patent Application Laid-Open No. 2003-086836 (Patent Document 3), the following is disclosed as a semiconductor substrate for forming a semiconductor light emitting element. That is, a light emitting semiconductor layer formed on one main surface of the semiconductor substrate and a transparent substrate transparent to the light emitted from the semiconductor layer are bonded using a transparent adhesive layer. At this time, an ohmic contact layer that is in ohmic contact with the semiconductor layer is formed on the main surface of the semiconductor layer to be bonded using the transparent adhesive layer, and then the transparent substrate and the semiconductor layer are bonded. Since the transparent substrate does not have conductivity, the light emitting element formed over the substrate has two electrodes on the main surface of the semiconductor layer. Therefore, a part of the semiconductor layer is removed by etching, and a first metal electrode is formed on the exposed main surface of the semiconductor epitaxial layer. Then, a second metal electrode is formed on the main surface of the semiconductor epitaxial layer that has not been removed by the etching process. In order to electrically connect these metal electrodes, for example, the first metal electrode and the ohmic contact layer are electrically connected by an electrode connection channel. In this manner, light emitted from the semiconductor layer when the first metal electrode and the second metal electrode are conducted is output at a high rate through the transparent substrate that does not absorb the light.

JP 2002-134785 A JP 2002-246640 A JP 2003-086836 A

  Each of the semiconductor light emitting devices disclosed in the above-mentioned patent documents has a configuration in which a semiconductor layer and a transparent substrate are joined. In the semiconductor light emitting device, two electrodes are both present on the main surface of the semiconductor layer. The semiconductor layer is, for example, an active layer that is a region where electrons and holes as carriers for light emission are combined, an n-type cladding layer that is arranged so as to sandwich the active layer, and provides electrons to the active layer, active It consists of a p-type cladding layer that provides holes to the layer. Therefore, two electrodes are arranged on the main surface of the n-type cladding layer and on the main surface of the p-type cladding layer, and a voltage is applied between the n-type cladding layer and the p-type cladding layer. . Therefore, by applying a voltage to the semiconductor light emitting element described above, a current flows, for example, in the n-type cladding layer or the p-type cladding layer in a direction along the main surface of the semiconductor light emitting element.

  However, the above-described semiconductor light emitting device may have the following problems. Here, since both of the two electrodes are disposed on the main surface of the semiconductor layer, for example, an n-type cladding layer is disposed on the outermost surface of the semiconductor layer, and the p-type cladding layer is disposed inside the semiconductor layer, that is, the semiconductor layer. Consider the case of an epitaxial layer including a main surface to which a transparent substrate is bonded. At this time, in order to dispose the electrode on the main surface of the p-type cladding layer, the active layer or the n-type cladding laminated on the main surface of the p-type cladding layer is used to expose the main surface of the p-type cladding layer. Part of the layer is removed, for example, by etching.

  In this way, with respect to the main surface of the semiconductor layer, an electrode is disposed on the main surface of the p-type cladding layer in the exposed region of the p-type cladding layer, and an n-type is formed in the region where the n-type cladding layer is disposed. An electrode is disposed on the main surface of the cladding layer. Therefore, the size of each electrode is smaller than the size of the main surface of the semiconductor layer originally stacked. Since the size of each electrode is small, when a current is passed from one of the two electrodes to the other, an epitaxial layer such as a p-type cladding layer is used as a current diffusion layer, and a current flows in a wide region on the main surface of the epitaxial layer. It is necessary to make the current flow almost uniformly over a wide area by diffusing.

  However, an epitaxial layer such as an n-type cladding layer or a p-type cladding layer has a very thin thickness in a direction intersecting the main surface. Moreover, since these are semiconductor layers, their conductivity is inferior to that of a layer made of a conductor. For this reason, it is difficult for current to diffuse uniformly in the epitaxial layer (that is, to pass current uniformly through the epitaxial layer). In addition, in order to improve the conductivity, it is expensive to form the n-type cladding layer and the p-type cladding layer so thick that the current can be sufficiently diffused by using an epitaxial growth method. Therefore, the current flowing in the epitaxial layer has a non-uniform current distribution in the direction along the main surface. As a result, for example, in some regions in the direction along the main surface of the epitaxial layer, the current density may increase due to current concentration compared to other regions, and the voltage may increase. Thus, the electrical characteristics of the semiconductor light emitting element may become unstable. If the electrical characteristics of the semiconductor light emitting element become unstable as described above, the state of light emission in the active layer may become non-uniform. For this reason, the quality of the semiconductor light emitting element is deteriorated.

  Further, for example, as in the semiconductor light emitting device disclosed in Patent Document 3 described above, when an ohmic contact layer or the like is disposed in order to diffuse the current flowing between the electrodes almost uniformly in a wide region of the semiconductor light emitting device, It is necessary to form an electrode connection channel for electrically connecting the epitaxial layer and the ohmic contact layer. For this reason, the process for forming the said semiconductor light emitting element becomes complicated. Since the process becomes complicated, the yield of the formed semiconductor light emitting device may be lowered.

  Furthermore, when the ohmic contact layer is opaque to the light emitted from the semiconductor light emitting element, the presence of the ohmic contact layer prevents the emitted light from being output. Therefore, when the ohmic contact layer is disposed, the light output of the semiconductor light emitting element may be reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a light-emitting element capable of flowing a current uniformly by applying a voltage and obtaining a uniform and large light emission output. It is to provide an epitaxial substrate that can be used. Moreover, it is providing the light emitting element using the said epitaxial substrate, a light-emitting device provided with a light emitting element, and the manufacturing method of the said epitaxial substrate.

  The light-emitting element according to the present invention is disposed on a support substrate, an adhesive layer disposed on one main surface of the support substrate, and a main surface of the adhesive layer opposite to the main surface facing the support substrate. A transparent conductive layer; and an epitaxial layer disposed on the main surface of the transparent conductive layer opposite to the main surface facing the adhesive layer. A part of the second main surface of the transparent conductive layer opposite to the first main surface facing the adhesive layer is exposed. The light emitting element includes electrodes formed on the exposed second main surface of the transparent conductive layer and on the main surface opposite to the main surface of the epitaxial layer facing the transparent conductive layer.

  In this case, a current is generated when a voltage is applied between the two electrodes. As described above, the epitaxial layer is formed on the transparent conductive layer, and the transparent conductive layer is disposed adjacent to the epitaxial layer. As the transparent conductive layer, it is preferable to use a material having high conductivity and excellent current diffusibility. In this case, since the transparent conductive layer functions as a current diffusion layer, the current flows uniformly so as to diffuse widely in the transparent conductive layer. Therefore, in the light emitting element, a uniform current can be passed in the direction along the main surface of the epitaxial layer. For this reason, uniform light can be output from the light emitted from the light emitting element.

  Further, since the transparent conductive layer is transparent, light emitted from the light emitting element can be transmitted. Here, the term “transparent” means that light having a wavelength emitted by the light emitting element is transmitted with a high transmittance of 80% or more. Conversely, when the transmittance is less than 80%, it is defined as opaque. For this reason, the light emitted from the light emitting element can pass through the transparent conductive layer. For this reason, the said light can be output to a desired direction.

  The epitaxial substrate according to the present invention is disposed on the main surface of the support substrate, the adhesive layer disposed on one main surface of the support substrate, and the main surface of the adhesive layer opposite to the main surface facing the support substrate. A transparent conductive layer; and an epitaxial layer disposed on the main surface of the transparent conductive layer opposite to the main surface facing the adhesive layer.

  The epitaxial substrate includes a support substrate and an epitaxial layer that is a region that emits light when a light emitting element is formed using the epitaxial substrate, for example. An epitaxial layer is a thin film formed, for example, by epitaxially growing a semiconductor material.

  The above-described epitaxial substrate can be used for manufacturing a light emitting element, for example. Here, consider a case where a light emitting element is formed by forming electrodes on the main surfaces of an epitaxial layer, for example, an n-type cladding layer and a p-type cladding layer. At this time, a current is generated by applying a voltage between the electrodes. As described above, the epitaxial substrate includes a transparent conductive layer, and the transparent conductive layer is disposed on one main surface of the epitaxial layer. As the transparent conductive layer, a material having high conductivity and excellent current diffusibility is used. In this case, since the transparent conductive layer functions as a current diffusion layer, the current flows uniformly so as to diffuse widely in the transparent conductive layer. Therefore, in the light emitting element, a uniform current can flow in the direction along the main surface of the epitaxial substrate. For this reason, when a light emitting element is formed using the epitaxial substrate according to the present invention, for example, uniform light can be output from the light emitting element.

  Further, since the transparent conductive layer is transparent, light emitted from the light emitting element can be transmitted. For this reason, the light emitted from the light emitting element formed using the epitaxial substrate can pass through the transparent conductive layer. For this reason, the said light can be output to a desired direction.

The epitaxial layer in the light-emitting element or the epitaxial substrate described above preferably has a structure in which a plurality of Al _x In _y Ga _1-xy As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) are stacked.

For example, an n-type clad layer, an active layer, and a p-type clad layer constituting the epitaxial layer are composed of the above-described Al _x In _y Ga _1-xy As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1). The values of x and y are set appropriately. Here, it is preferable to set the values of x and y so that the band gap energy of the active layer is smaller than the band gap energy of the n-type (p-type) cladding layer. In this way, light can be generated from the active layer sandwiched between n-type (p-type) cladding layers. Furthermore, if the values of x and y are appropriately set, a light emitting element formed using the epitaxial substrate can emit infrared light. In addition, if the values of x and y are appropriately selected, the n-type cladding layer and the p-type cladding layer can be made transparent to the light emitted from the light emitting element. Therefore, by providing a transparent conductive layer on the epitaxial substrate as described above, a light emitting element capable of emitting uniform infrared light can be formed.

  In the above-described light emitting device or epitaxial substrate, the transparent conductive layer is preferably ITO (Indium Tin Oxide).

  ITO has high transparency while having conductivity. For example, the supporting substrate in the epitaxial substrate is a transparent substrate having no conductivity, and electrodes are arranged in a part of the main surface of the n-type cladding layer and the transparent conductive layer that constitute the epitaxial layer, for example. Consider a light emitting device to be formed. Then, the light emitted from the light-emitting element can pass through the (transparent) epitaxial layer and the transparent conductive layer ITO, and can pass through the inside of the transparent support substrate. Thus, when ITO is used as the transparent conductive layer, the light emitted from the light-emitting element formed using the epitaxial substrate can be favorably output from a desired direction.

If ITO is used, a good ohmic junction is formed with an epitaxial layer made of, for example, Al _x In _y Ga _1-xy As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) to be bonded to ITO. can do.

  In the above-described light-emitting element or epitaxial substrate, the adhesive layer preferably includes any one selected from the group consisting of BCB resin, polyimide resin, epoxy resin, and silicone resin.

  These resin materials have high elasticity in addition to adhesiveness. For this reason, for example, even when the surface roughness of the main surface of the support substrate or the transparent conductive layer bonded by the adhesive layer is high (the surface is rough), the main surface of the support substrate or the main surface of the transparent conductive layer And can be joined well. Therefore, if these resin materials are used as an adhesive layer, the yield of the formed epitaxial substrate can be improved.

  Further, these resin materials have high transparency with respect to light emitted from the light emitting element formed on the epitaxial substrate. Therefore, for example, when the support substrate is a transparent material, the light emitted from the epitaxial layer of the light-emitting element formed using the epitaxial substrate can be transmitted through the adhesive layer satisfactorily.

  In the above-described light emitting device or epitaxial substrate, the support substrate is preferably a transparent support substrate that is transparent to light emitted from the epitaxial layer.

  Here, light emitted from the epitaxial layer refers to light emitted from a light emitting element formed using the epitaxial substrate. When the support substrate is a transparent support substrate, a light-emitting element formed using such an epitaxial substrate can output emitted light to the outside through the inside of the transparent support substrate. Accordingly, the degree of freedom in the traveling direction of the emitted light can be improved, and the light emitted at a higher rate (highly efficient) can be advanced in a desired direction.

  In the light-emitting element or the epitaxial substrate described above, the transparent support substrate preferably contains any one selected from the group consisting of sapphire, glass, silicon carbide, gallium phosphide, quartz, and spinel. If these materials are used, the light emitted from the light-emitting element formed using the epitaxial substrate as described above can travel inside the transparent support substrate with high efficiency.

  Moreover, if the above-described material is used for the transparent support substrate, sufficient strength is secured as a base for supporting the epitaxial layer constituting the epitaxial substrate, the light emitting element formed using the epitaxial substrate, and the like from below. be able to.

  In the light-emitting element or the epitaxial substrate described above, it is preferable that one main surface of the transparent conductive layer and the other main surface facing the one main surface are roughened.

  Here, the roughening treatment is a treatment for increasing the surface roughness of the surface, that is, for roughening the surface. If the surface roughness of one or the other main surface of the transparent conductive layer is increased by performing the surface roughening treatment, the light emitted from the epitaxial layer of the light emitting element formed on the epitaxial substrate is, for example, transparent conductive It is possible to suppress total reflection on the main surface of the layer.

  If light causes total reflection on the main surface of the transparent conductive layer, the light does not pass the direction that should travel originally (for example, the direction passing through the inside of the adhesive layer or the support substrate) in order to output to the outside. For this reason, the intensity at which the light is output to the outside may be weakened. Therefore, by suppressing the total reflection as described above, it is possible to output the emitted light at a high rate (high efficiency) in a desired direction.

  In the light emitting device or the epitaxial substrate described above, any one of the transparent conductive layer on the main surface opposite to the main surface facing the epitaxial layer and the main surface on the opposite side of the epitaxial layer of the support substrate It is preferable that the region further includes a reflective layer that reflects light emitted from the epitaxial layer.

  A light-emitting element formed using an epitaxial substrate having such a reflective layer reflects light that has traveled in a direction opposite to the direction in which it is desired to be output, by reflecting the reflected light on the reflective layer. The direction of travel can be changed to travel in the direction. For example, when it is desired to output the light to the epitaxial layer from the main surface existing in the direction opposite to the direction in which the support substrate exists, the light is reflected by the reflective layer. In this way, the progress of the light can be turned. Therefore, for example, even if a support substrate made of a material that is opaque to the light is used, the emitted light can be output from any direction, for example, from the main surface on which the electrode is disposed.

  In the light emitting device using the epitaxial substrate described above, a part of the second main surface of the transparent conductive layer opposite to the first main surface facing the adhesive layer is exposed, and the exposed first It is preferable to provide an electrode on the main surface of 2 and on the main surface opposite to the main surface facing the transparent conductive layer of the epitaxial layer.

  In the light emitting device having the above-described configuration, the two electrodes are arranged on the same side with respect to the main surface of the support substrate, that is, on the side where the epitaxial layer exists (for example, on the main surface of the epitaxial layer). This is because the transparent conductive layer is partially exposed by etching a part of the region related to the main surface of the epitaxial layer, and one electrode is formed on the main surface of the exposed transparent conductive layer. Is. With such a configuration, the current flowing when a voltage is applied between the electrodes can be diffused substantially uniformly over a wide range in the transparent conductive layer. Therefore, the emitted light also has little variation between regions and can be output almost uniformly.

  The epitaxial substrate may further include a buried electrode made of a conductive material that is directly connected to the transparent conductive layer and is different from the transparent conductive layer. In this case, when the electrode that is electrically connected to the transparent conductive layer is formed by partially removing the epitaxial layer that overlaps the buried electrode, the buried electrode is used as an etching stopper in the etching process of the epitaxial layer. Can do.

  The light-emitting element according to the present invention is disposed on the support substrate, the adhesive layer disposed on one main surface of the support substrate, and the main surface of the adhesive layer opposite to the main surface facing the support substrate. Transparent conductive layer, an epitaxial layer disposed on the main surface opposite to the main surface opposite to the adhesive layer of the transparent conductive layer, and a conductive material directly connected to the transparent conductive layer and different in conductivity from the transparent conductive layer And an embedded electrode made of a material. An opening is formed by removing at least part of the epitaxial layer so that part of the buried electrode is exposed. The light emitting device further includes an electrode formed on a part of the exposed buried electrode and on the main surface opposite to the main surface of the epitaxial layer facing the transparent conductive layer.

  In this case, when a voltage is applied between the electrodes, a current can be made to flow almost uniformly from the electrode to the wide range inside the transparent conductive layer via the embedded electrode. Therefore, the emitted light also has little variation between regions, and light can be output almost uniformly.

  In the light emitting device or the epitaxial substrate, the embedded electrode may be disposed on the surface of the transparent conductive layer facing the adhesive layer. In this case, after forming the transparent conductive layer, a buried electrode can be formed subsequently. In addition, in the case where the embedded electrode is formed without particularly performing the formation of the opening portion with respect to the transparent conductive layer, it is not necessary to perform the step of forming the opening portion, so that the manufacturing process is not complicated. it can.

  In the light emitting element or the epitaxial substrate, a recess may be formed in a portion where the embedded electrode is disposed on the surface of the transparent conductive layer. The embedded electrode may include a protrusion that fills the inside of the recess. In this case, the contact area between the embedded electrode and the transparent conductive layer can be made wider than when the concave portion is not formed. For this reason, the adhesive strength between the transparent conductive layer and the embedded electrode can be further increased. In addition, when current is supplied to the transparent conductive layer through the embedded electrode, the contact area between the embedded electrode and the transparent conductive layer is widened, so that current can be supplied to the transparent conductive layer more stably. For this reason, since the uniformization of the current in the transparent conductive layer can be further promoted, the light output of the light emitting element formed using the epitaxial substrate can be improved as a result.

  In the light emitting element or the epitaxial substrate, a through hole that reaches from the surface facing the adhesive layer to the surface facing the epitaxial layer may be formed in the transparent conductive layer. The embedded electrode may be arranged so as to fill the inside of the through hole. In this case, the contact area between the buried electrode and the transparent conductive layer can be made wider than when the through hole is not formed. For this reason, the adhesive strength between the transparent conductive layer and the embedded electrode can be further increased. Further, the buried electrode is in contact with the epitaxial layer at one end of the through hole (the end of the through hole on the surface side facing the epitaxial layer in the transparent conductive layer). Therefore, the buried electrode can be easily used as an etching stopper in etching the epitaxial layer.

  In addition, when the current is supplied to the transparent conductive layer through the buried electrode, the contact area between the buried electrode and the transparent conductive layer is wider than when the through-hole is not formed, so that the current is more stably supplied to the transparent conductive layer. Can supply. For this reason, since the uniformization of the current in the transparent conductive layer can be further promoted, the light output of the light emitting element formed using the epitaxial substrate can be improved as a result.

  In the light-emitting element or the epitaxial substrate, the embedded electrode may include an extending portion that extends on the main surface of the transparent conductive layer facing the adhesive layer and is in direct contact with the transparent conductive layer. In this case, the contact area between the embedded electrode and the transparent conductive layer is further widened by the extended portion. Therefore, when current is supplied to the transparent conductive layer through the embedded electrode, the current is more stably supplied to the transparent conductive layer. Can supply. As a result, the light output of the light emitting element formed using the epitaxial substrate can be improved as a result. In addition, since the contact area is increased, the adhesive strength between the transparent conductive layer and the embedded electrode can be further increased.

  In the light emitting device or the epitaxial substrate, the embedded electrode may have a multilayer structure in which a plurality of different types of conductor layers are stacked. In this case, the degree of freedom in selecting the material of the embedded electrode can be increased.

  In the light-emitting element or the epitaxial substrate, in the embedded electrode, the plurality of conductor layers constituting the multilayer structure may include a first conductor layer and a second conductor layer. The first conductor layer may be in contact with the transparent conductive layer and the epitaxial layer. The 2nd conductor layer may be formed so that the surface located in the opposite side to the surface which contacts a transparent conductive layer in the 1st conductor layer may be formed. The first conductor layer preferably has relatively higher adhesion to the transparent conductor layer and the epitaxial layer than the second conductor layer. The second conductor layer preferably has a higher selectivity to the etchant that etches the epitaxial layer than the first conductor layer. In this case, the embedded electrode can be reliably connected and fixed to the transparent conductive layer and the epitaxial layer by the first conductor layer, and the embedded electrode can reliably function as an etching stopper by the second conductor layer.

In the light-emitting element or the epitaxial substrate, the first conductor layer may be made of at least one of chromium and titanium. In this case, the epitaxial layer has a structure in which a plurality of Al _x In _y Ga _1-xy As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) are stacked, and the transparent conductive layer is made of ITO. Also good. In this case, the first conductor layer can be reliably fixed to the transparent conductive layer and the epitaxial layer.

In the light emitting device or the epitaxial substrate, the second conductor layer may be made of at least one selected from the group consisting of gold (Au), platinum (Pt), and palladium (Pd). In this case, the epitaxial layer may have a structure in which a plurality of Al _x In _y Ga _1-xy As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) are stacked. In this case, since the second conductor layer is made of a material having a high selectivity with respect to the epitaxial layer, the buried electrode can be used as an etching stopper in etching the epitaxial layer.

  A light-emitting element according to the present invention is a light-emitting element using the above-described epitaxial substrate, and an opening is formed by removing at least a part of the epitaxial layer so that a part of the embedded electrode is exposed. An electrode is provided on a part of the exposed buried electrode and on the main surface opposite to the main surface facing the transparent conductive layer of the epitaxial layer. With such a configuration, when a voltage is applied between the electrodes, a current can flow almost uniformly from the electrodes through the embedded electrode to a wide range inside the transparent conductive layer. Therefore, the emitted light also has little variation between regions, and light can be output almost uniformly.

  A light-emitting device according to the present invention is disposed on a main surface of a first lead frame of the pair of lead frames, and a pair of lead frames that input and output an electric signal between the light-emitting element and the outside. The light emitting element, an electrode of the light emitting element, and a wire connecting each of the first lead frame and the second lead frame. A light-emitting device using the above-described light-emitting element can output emitted light with high efficiency.

  An epitaxial substrate manufacturing method according to the present invention includes a step of preparing a substrate, a step of forming an epitaxial layer on one main surface of the substrate, and a main surface of the epitaxial layer opposite to the main surface facing the substrate. A step of forming a transparent conductive layer thereon, and a step of bonding a support substrate on the main surface of the transparent conductive layer opposite to the main surface facing the epitaxial layer. In this way, the epitaxial substrate according to the present invention can be easily obtained.

  The method for manufacturing the epitaxial substrate may further include a step of forming a buried electrode made of a conductive material that is directly connected to the transparent conductive layer and is different from the transparent conductive layer. In this case, an epitaxial substrate having a buried electrode that can be used as an etching stopper or the like in etching the epitaxial layer can be obtained.

  The method for manufacturing an epitaxial substrate may further include a step of forming an opening in the transparent conductive layer. In the step of forming the embedded electrode, the embedded electrode may be formed so as to fill the inside of the opening. In this case, an epitaxial substrate with improved connection strength between the buried electrode filling the opening and the transparent conductive layer can be obtained.

  The substrate described above is made of a compound semiconductor material such as gallium arsenide that can form, for example, an epitaxial layer of a semiconductor material on the main surface. That is, the substrate does not constitute a light emitting element using the epitaxial substrate. Therefore, the substrate described above may be removed when forming the light emitting element. If the substrate is removed, when the light emitting element is formed, it is possible to suppress the occurrence of problems such as the fact that light emitted from the epitaxial layer is absorbed by the substrate described above.

  As described above, the epitaxial substrate includes a transparent conductive layer. Therefore, the light emitting element formed using the epitaxial substrate can uniformly diffuse the current generated by the voltage applied between the two electrodes in the transparent conductive layer. Therefore, light can be output uniformly and efficiently. The support substrate of the epitaxial substrate may be transparent or opaque with respect to light emitted by a light emitting element formed using the epitaxial substrate.

  The method for manufacturing a light emitting device according to the present invention includes a step of preparing a substrate, a step of forming an epitaxial layer on one main surface of the substrate, and a main surface of the epitaxial layer opposite to the main surface facing the substrate. After the step of forming the transparent conductive layer on the surface, the step of bonding the support substrate on the main surface of the transparent conductive layer opposite to the main surface facing the epitaxial layer, and the step of bonding the support substrate, Removing the substrate from the layer, exposing a part of the transparent conductive layer by removing a part of the epitaxial layer, forming an electrode on the exposed transparent conductive layer and the epitaxial layer, and Is provided.

  The method for manufacturing a light emitting device according to the present invention includes a step of preparing a substrate, a step of forming an epitaxial layer on one main surface of the substrate, and a main surface of the epitaxial layer opposite to the main surface facing the substrate. A step of forming a transparent conductive layer on the surface; a step of forming a buried electrode made of a conductive material that is directly connected to the transparent conductive layer and different from the transparent conductive layer; and a main layer of the transparent conductive layer facing the epitaxial layer. After the step of bonding the support substrate on the main surface opposite to the surface, the step of bonding the support substrate, the step of removing the substrate from the epitaxial layer, and removing a part of the epitaxial layer, A step of exposing a part, and a step of forming an electrode on the exposed buried electrode and the epitaxial layer. In this way, the light emitting element according to the present invention can be easily obtained.

  The manufacturing method of the said light emitting element may further be equipped with the process of forming an opening part in a transparent conductive layer. In the step of forming the embedded electrode, the embedded electrode may be formed so as to fill the inside of the opening.

  According to the present invention, there is provided an epitaxial substrate for forming a light emitting element capable of uniformly and efficiently outputting light, the light emitting element, a light emitting device using the light emitting element, and a method for manufacturing the epitaxial substrate. Can be provided.

1 is a schematic cross-sectional view showing a laminated structure of an epitaxial substrate according to a first embodiment. It is a schematic sectional drawing which shows the structure of the epitaxial layer of FIG. 1 in detail. It is a schematic sectional drawing which shows the structure of the light emitting element formed using the epitaxial substrate of FIG. 4 is a flowchart showing manufacturing steps of the epitaxial substrate according to the first embodiment and a light emitting device using the epitaxial substrate. It is a schematic sectional drawing which shows the aspect in the process (S20) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S30) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S40) of FIG. 6 is a schematic cross-sectional view showing a laminated structure of an epitaxial substrate according to a second embodiment. FIG. 6 is a schematic cross-sectional view showing a laminated structure of an epitaxial substrate according to a third embodiment. FIG. It is a schematic sectional drawing which shows the structure of the light emitting element formed using the epitaxial substrate of FIG. It is a schematic sectional drawing which shows the laminated structure of the epitaxial substrate which concerns on this Embodiment 4. It is a schematic plan view which shows the structure of the light emitting element formed using the epitaxial substrate of FIG. It is a schematic sectional drawing in line segment XIII-XIII of FIG. It is a flowchart which shows the manufacturing process of the epitaxial substrate which concerns on this Embodiment 4, and the light emitting element using the said epitaxial substrate. It is a flowchart which shows the detail of the process of forming the metal layer shown in FIG. It is a schematic sectional drawing which shows the aspect in the process (S91) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S91) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S92) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S92) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S92) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S40) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S71) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S60) of FIG. It is a schematic sectional drawing which shows the aspect in the process (S72) of FIG. It is a schematic sectional drawing which shows the laminated structure of the modification of the epitaxial substrate which concerns on this Embodiment 4. FIG. It is a schematic sectional drawing which shows the structure of the light emitting element formed using the epitaxial substrate of FIG. FIG. 10 is a schematic cross-sectional view showing a laminated structure of an epitaxial substrate according to a fifth embodiment. It is a schematic sectional drawing which shows the structure of the light emitting element formed using the epitaxial substrate of FIG. It is a schematic sectional drawing for demonstrating the manufacturing process of the epitaxial substrate which concerns on this Embodiment 5, and the light emitting element using the said epitaxial substrate. It is a schematic sectional drawing for demonstrating the manufacturing process of the epitaxial substrate which concerns on this Embodiment 5, and the light emitting element using the said epitaxial substrate. It is a schematic sectional drawing for demonstrating the manufacturing process of the epitaxial substrate which concerns on this Embodiment 5, and the light emitting element using the said epitaxial substrate. It is a schematic sectional drawing which shows the laminated structure of the modification of the epitaxial substrate which concerns on this Embodiment 5. FIG. It is a schematic sectional drawing which shows the structure of the light emitting element formed using the epitaxial substrate of FIG. It is a schematic sectional drawing which shows the laminated structure of the epitaxial substrate which concerns on this Embodiment 6. FIG. It is a schematic sectional drawing which shows the structure of the light emitting element formed using the epitaxial substrate of FIG. It is a schematic sectional drawing for demonstrating the manufacturing process of the epitaxial substrate which concerns on this Embodiment 6, and the light emitting element using the said epitaxial substrate. It is a schematic sectional drawing for demonstrating the manufacturing process of the epitaxial substrate which concerns on this Embodiment 6, and the light emitting element using the said epitaxial substrate. It is a schematic sectional drawing which shows the laminated structure of the modification of the epitaxial substrate which concerns on this Embodiment 6. FIG. It is a schematic sectional drawing which shows the structure of the light emitting element formed using the epitaxial substrate of FIG. It is the schematic which shows the structure of the light-emitting device using the light emitting element which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each embodiment, elements having the same function are denoted by the same reference numerals, and the description thereof will not be repeated unless particularly necessary.

(Embodiment 1)
As shown in FIG. 1, an epitaxial substrate 100 according to the first embodiment includes a transparent support substrate 1 and an adhesive layer 2 disposed on one main surface (upper side in FIG. 1) of the transparent support substrate 1. Prepare. A transparent conductive layer 3 is provided on the main surface of the adhesive layer 2 opposite to the main surface facing the transparent support substrate 1 (upper side in FIG. 1). An epitaxial layer 4 is provided on the main surface of the transparent conductive layer 3 opposite to the main surface facing the adhesive layer 2 (upper side in FIG. 1).

  The transparent support substrate 1 is a support substrate that is formed using the epitaxial substrate 100 and is made of a material that is transparent to light emitted from a light emitting element described later. Specifically, for example, the transparent support substrate 1 is preferably made of sapphire, glass, silicon carbide (SiC), gallium phosphide (GaP), quartz, spinel, or the like. The transparent support substrate 1 has a role as a base that suppresses the destruction of the epitaxial layer 4 and the like by supporting the epitaxial layer 4 and the like constituting the epitaxial substrate 100 from the lower side. Further, the light emitted from the light emitting element formed using the epitaxial substrate 100 can be transmitted in a desired direction at a high rate (highly efficient) by transmitting through the transparent support substrate 1.

  Specifically, as shown in FIG. 2, the epitaxial layer 4 includes a first cladding layer 5, an active layer 6 disposed on one main surface (upper side in FIG. 2) of the first cladding layer 5, and an active layer And a second cladding layer 7 disposed on one main surface of layer 6 (upper side in FIG. 2).

Epitaxial substrate 100 is a substrate used to form a light emitting element such as an LED. The epitaxial layer 4 constituting the epitaxial substrate 100 has a configuration in which a plurality of semiconductor layers formed by epitaxial growth are stacked. For example, when a light emitting element that emits infrared rays is formed using the epitaxial substrate 100, the first cladding layer 5, the active layer 6, and the second cladding layer 7 constituting the epitaxial layer 4 are all Al _x In _y Ga _{1-x. -Y} As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) is preferable. In addition, infrared rays here mean the infrared rays which have a wavelength of 850 nm or more and 950 nm or less.

Further, when the first cladding layer 5 is made of, for example, an n-type semiconductor (Al _x In _y Ga _1-xy As described above), the second cladding layer 7 is preferably made of a p-type semiconductor. Conversely, when the first cladding layer 5 is made of a p-type semiconductor, the second cladding layer 7 is preferably made of an n-type semiconductor.

  The transparent conductive layer 3 is a region arranged to allow a current to be output to flow uniformly inside the light emitting device when a voltage is applied between the two electrodes of the light emitting device formed using the epitaxial substrate 100. is there. When the light emitting element includes two electrodes on or inside the main surface on the upper side of the epitaxial layer 4 in FIG. 1, for example, if a voltage is applied between the two electrodes, a current flows based on a potential difference. This current is diffused so as to flow uniformly over a wide area with respect to the horizontal direction of the transparent conductive layer 3 in FIG. 1 and the direction perpendicular to the paper surface in FIG. 1 (depth direction). Thus, the transparent conductive layer 3 is disposed in order to smoothly diffuse the current.

  As the transparent conductive layer 3, for example, ITO (Indium Tin Oxide) is preferably used. ITO has high transparency while having conductivity. Therefore, if ITO is used as the transparent conductive layer 3, the light emitted from the light-emitting element formed using the epitaxial substrate 100 is propagated through the transparent conductive layer 3 at a high rate (highly efficient) in a desired direction. Can proceed to.

Further ITO constitutes the epitaxial layer 4 is disposed on the upper major surface of the transparent conductive layer 3 (the transparent conductive layer main surface 3b), n-type _{Al x In y Ga 1-x} -y As and p-type Al _x In _y Ga _1-xy As and a good ohmic junction can be obtained. The adhesive layer 2 preferably includes any one selected from the group consisting of BCB resin, polyimide resin, epoxy resin, and silicone resin. These resin materials have high adhesiveness. For this reason, for example, by arranging (coating) the adhesive layer 2 on the upper main surface in FIG. 1 of the transparent support substrate 1 or on the lower main surface (transparent conductive layer main surface 3a) of the transparent conductive layer 3. As shown in FIG. 1, if the transparent support substrate 1 and the transparent conductive layer 3 are bonded, both can be firmly bonded. Moreover, each resin material mentioned above has high elasticity. Therefore, for example, even when the surface roughness of the transparent support substrate main surface 3a or the transparent conductive layer main surface 3a to be bonded via the adhesive layer 2 is high, the adhesive layer 2 tries to bond due to the elasticity. It is possible to flexibly and firmly adhere to the uneven shape in a rough region on the surface. The adhesive layer 2 is a flexible material at the time of joining the transparent conductive layer 3 and the transparent support substrate 1, for example, but is firmly fixed in the state after the light emitting element 200 is formed, for example. It becomes.

  Further, any material constituting the adhesive layer 2 is transparent to light emitted from the light emitting element 200 formed using the epitaxial substrate 100. For this reason, the light emitted from the light emitting element formed using the epitaxial substrate 100 can be transmitted in a desired direction at a high rate (highly efficient) by transmitting the adhesive layer 2.

  The light emitting element 200 shown in FIG. 3 can be formed using the epitaxial substrate 100 having the above properties. In the light emitting element 200, a part of the main surface of the epitaxial layer 4 constituting the epitaxial substrate 100 of FIG. 1 (the right region in FIG. 3) is removed. In a region where the epitaxial layer 4 is not removed (the left region in FIG. 3), an electrode 9 is disposed on the main surface on the upper side of the second cladding layer 7 which is the uppermost layer of the epitaxial layer 4. Further, in the region where the epitaxial layer 4 is removed, the upper main surface (transparent conductive layer main surface 3b) of the transparent conductive layer 3 is exposed. Electrode 10 is arranged on this exposed transparent conductive layer main surface 3b.

  Furthermore, the light reflecting layer 8 is disposed on the main surface (the lower main surface in FIG. 3) of the transparent support substrate 1 on the side not facing the adhesive layer 2. Of the light generated in the active layer 6, the light traveling in the upward direction in FIG. 3 is, for example, the main surface on the upper side of the second cladding layer 7 on which the electrode 9 is disposed, or the electrode 10 is disposed. It can output from the transparent conductive layer main surface 3b. Further, of the light generated in the active layer 6, the light traveling in the downward direction in FIG. 3 passes through the inside of the transparent support substrate 1 and the main surface of the light reflecting layer 8 facing the transparent support substrate 1. Reach up. Then, the light is reflected on the main surface of the light reflecting layer 8 facing the transparent support substrate 1 and turned in the direction from the lower side to the upper side in FIG. For this reason, the said light can be output from the main surface above the 2nd cladding layer 7 in which the electrode 9 is arrange | positioned, and the transparent conductive layer main surface 3b in which the electrode 10 is arrange | positioned, for example. If the light is reflected at a high rate in the light reflection layer 8, the proportion of the light transmitted through the transparent support substrate 1 and output from the lower main surface of the transparent support substrate 1 to the outside decreases. Therefore, the light can be output in a desired direction at a high rate (with high efficiency).

  Here, the operation of the light emitting element 200 formed using the epitaxial substrate 100 will be described. A voltage is applied between the electrode 9 and the electrode 10. Then, for example, electrons flow from the electrode 10 to the electrode 9 due to the potential difference between the electrode 9 and the electrode 10. This electron flow is output as a current that flows in the opposite direction of the electron flow.

  This current flows, for example, from the electrode 9 through the epitaxial layer 4 from the upper side to the lower side in FIG. 3 and flows into the electrode 10 through the inside of the transparent conductive layer 3. The transparent conductive layer 3 is formed of, for example, ITO as described above. For this reason, a current can be passed through the transparent conductive layer 3 by a voltage applied between the electrode 9 and the electrode 10. Further, the current flowing into the transparent conductive layer 3 from the electrode 9 diffuses in the transparent conductive layer 3 over a wide area with respect to the cross section intersecting in the left-right direction shown in FIG. Therefore, the current flows from the left side to the right side in FIG. 3 uniformly in the transparent conductive layer 3. Therefore, current flows almost uniformly from the transparent conductive layer 3 over a wide area on the main surface of the first cladding layer 5. That is, with respect to the direction along the main surface of the first cladding layer 5 and the second cladding layer 7, a current flows almost uniformly in any region on the main surface (almost uniformly, electrons flow in the first cladding layer 7). 5 flows to the second cladding layer 7). Note that the adhesive layer 2 and the transparent support substrate 1 disposed below the transparent conductive layer 3 in FIG. 3 have no conductivity. For this reason, the electric current which flows through the inside of the transparent conductive layer 3 as described above hardly flows into, for example, the adhesive layer 2 or the transparent support substrate 1.

  In this way, a current for causing the light emitting element 200 to emit light is caused to flow inside the transparent conductive layer 3. In this way, for example, it is possible to reduce the possibility that a large current flows intensively in a partial region inside the transparent conductive layer 3 and the current flowing locally decreases.

  In addition, since the current flows by diffusing inside the transparent conductive layer 3, for example, the current hardly flows from the left side to the right side in FIG. Therefore, it is not necessary to form the epitaxial layer 4 thick in order to pass a current through the epitaxial layer 4. From this, the cost of forming the epitaxial layer 4 can be reduced.

  Further, in the light emitting element 200, the current flows uniformly and stably inside the transparent conductive layer 3. For this reason, for example, a region such as an ohmic contact layer for supplying a current for forming a semiconductor light emitting element is formed as in the semiconductor substrate disclosed in Patent Document 3 described above, and the electrode and the electrode are connected to each other. There is no need to perform complicated processes such as connecting by channels. From this, it can be said that the cost of forming the epitaxial layer 4 can be reduced.

  In addition, since the said electric current flows uniformly from the left side of FIG. 3 to the right side in the transparent conductive layer 3, an electron flows the inside of the transparent conductive layer 3 uniformly from the right side to the left side of FIG. And since the said electron goes to the electrode 9, the flow direction is turned to the direction which goes to the upper side from the lower side of FIG. Since the redirected electrons are in ohmic contact with the transparent conductive layer 3 and the first cladding layer 5 at the interface (transparent conductive layer main surface 3b) between the transparent conductive layer 3 and the first cladding layer 5, the electrons are smoothly transferred. It can flow toward the first cladding layer 5.

  Here, assuming that the first cladding layer 5 is made of, for example, an n-type semiconductor material and the second cladding layer 7 is made of, for example, a p-type semiconductor material, a positive voltage is applied to the electrode 9 and a negative voltage is applied to the electrode 10. Consider the case where is applied. At this time, electrons flow from the first cladding layer 5 into the active layer 6. On the other hand, holes flow from the second cladding layer 7 into the active layer 6. Inside the active layer 6, electrons and holes as carriers flowing from each cladding layer recombine. The energy released during this recombination is emitted as light energy. Therefore, when a voltage is applied almost uniformly to a wide region in the direction along the main surfaces of the first cladding layer 5 and the second cladding layer 7 and the above-described current flows, the active layer 6 is used as a carrier from the first cladding layer 5. The entering electrons also uniformly enter a wide region with respect to the direction along the main surface of the first cladding layer 5. Similarly, the holes that enter the active layer 6 as carriers from the second cladding layer 7 enter substantially uniformly in a wide region with respect to the direction along the main surface of the second cladding layer 7. For this reason, the above-described light-emitting element 200 by recombination can emit light substantially uniformly to a desired region. Specifically, for example, the light emitting element 200 can emit light substantially uniformly in the direction along the main surface of the active layer 6 (the left-right direction of the active layer 6 in FIG. 3 and the depth direction perpendicular to the paper surface). .

  The light emitted from the active layer 6 passes through, for example, the first cladding layer 5, the transparent conductive layer 3, the adhesive layer 2, and the transparent support substrate 1, and is reflected at the interface between the transparent support substrate 1 and the light reflection layer 8. . Then, the transparent support substrate 1, the adhesive layer 2, the transparent conductive layer 3 and the like are transmitted in the reverse direction, and the main surface on the upper side of the second cladding layer 7 on which the electrode 9 is disposed, and the transparent conductive layer main on which the electrode 10 is disposed. It can output from the surface 3b. However, the light may be output from, for example, the left and right side surfaces of the transparent support substrate 1 in FIG. 3, or may be output from the main surface below the transparent support substrate 1 without the light reflecting layer 8 being disposed. May be. That is, the light can be output from any direction.

  As described above, the emitted light is transmitted through the first cladding layer 5, the transparent conductive layer 3, the adhesive layer 2, and the transparent support substrate 1, and reflected from, for example, the light reflecting layer 8 and then output from a desired direction. Then, it is possible to suppress, for example, a high rate of absorption inside the substrate during the period until the emitted light is output. This is because, as described above, the transparent conductive layer 3, the adhesive layer 2, and the transparent support substrate 1 are all formed of a material that is transparent to the light. Furthermore, the light can be output from a wide area on the main surface of the transparent support substrate 1. As described above, the light emitting element 200 can output light at a high rate (with high efficiency) with respect to the voltage applied between the electrode 9 and the electrode 10.

  Here, a method for manufacturing the epitaxial substrate 100 will be described. As shown in the flowchart of FIG. 4, a step (S10) of preparing an epi substrate is first performed. Specifically, this is a step of preparing the epitaxial substrate 11 shown in FIG.

The epitaxial substrate 11 is a substrate used as a base for forming the epitaxial layer 4 of FIG. 2 in a later process. Therefore, as the epitaxial substrate 11, a substrate made of gallium arsenide (GaAs) capable of forming a laminated structure of Al _x In _y Ga _1-xy As constituting the epitaxial layer 4 by epitaxial growth is used. preferable.

  Next, a step (S20) of forming an epitaxial layer is performed. Specifically, as shown in FIG. 5, the epitaxial layer 4 is formed on one main surface of the epitaxial substrate 11.

  As shown in FIG. 2 described above, the epitaxial layer 4 has a laminated structure of the first cladding layer 5, the active layer 6, and the second cladding layer 7. In addition, a semiconductor layer may be formed as necessary.

Here, as an example, the epitaxial layer 4 of the epitaxial substrate 100 of FIG. 1 is formed in order from the lower side as shown in FIG. 2, that is, the first cladding layer 5 on the transparent conductive layer main surface 3 b. Let us consider a case where the active layer 6 is disposed on top and the second cladding layer 7 is disposed on the active layer 6. In this case, in order to form a laminated structure of Al _x In _y Ga _1-xy As as the epitaxial layer 4, the second cladding layer 7 is formed on the main surface of the epitaxial substrate 11 using an epitaxial growth method. The active layer 6 and the first cladding layer 5 are formed in this order.

In particular, for the first clad layer 5 and the second clad layer 7, Al _x In _y Ga _{1-x −} depends on the wavelength of light emitted from the light emitting element 200 formed using the epitaxial substrate 100. It is preferable to change the values of x and y in _y As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1). For example, when the active layer 6 is formed, the ratio of gallium (Ga) is preferably increased, and a compound composed only of indium and gallium may be used depending on the situation. Moreover, it is preferable to select the values of x and y so that the first cladding layer 5 and the second cladding layer 7 can transmit light generated in the active layer 6 at a high rate.

  Then, the process (S30) of forming ITO is implemented. Specifically, as shown in FIG. 6, a process of forming an ITO thin film as the transparent conductive layer 3 on the main surface of the epitaxial layer 4 (first cladding layer 5) formed in the step (S20). It is. As a method for forming the ITO thin film, for example, an electron beam evaporation (EB evaporation) method is preferably used. Specifically, the alloy is partially heated and evaporated by irradiating an electron beam to an alloy of indium (In) or tin (Sn) while supplying oxygen gas under high vacuum. The evaporated reaction material of the alloy and oxygen is condensed and deposited (deposited) on the main surface of the desired epitaxial layer 4 (first cladding layer 5). This attached thin film is a thin film of ITO as the transparent conductive layer 3. By the above method, an ITO thin film can be formed.

Incidentally, if the wavelength of light emitted from the active layer lambda, the refractive index of ITO and eta _ITO, thickness _{t ITO} ([mu] m) of a thin film of ITO is, T = λ / (4 × η ITO) × (2 × m-1) is preferably 0.9T ≦ t _ITO ≦ 1.1T. Here, m is a natural number. The t _ITO (μm) is preferably 1 μm or less, and preferably about 0.2 μm. Among these, it is particularly preferable that the t _ITO (μm) is 0.12 μm or more and 0.16 μm or less, or 0.36 μm or more and 0.44 μm or less.

  When the transparent conductive layer 3 is formed as shown in FIG. 6, a step (S40) of bonding the support substrate is performed as shown in FIG. Specifically, this is a step of joining the transparent conductive layer main surface 3a of the transparent conductive layer 3 shown in FIG. 6 to one main surface of the transparent support substrate 1 shown in FIG.

  For example, FIG. 7 shows one main surface of the transparent support substrate 1 made of one or more selected from the group consisting of sapphire, glass, silicon carbide (SiC), gallium phosphide (GaP), quartz and spinel. For example, the adhesive layer 2 made of BCB resin or the like is disposed. Here, the thickness of the adhesive layer 2 is preferably 0.1 μm or more and 10 μm or less. Then, as shown in FIG. 7, the adhesive layer 2 and the transparent conductive layer main surface 3a are bonded together. That is, in FIG. 7, the laminated structure shown in FIG. 6 is turned upside down and bonded to the transparent support substrate 1 using the adhesive layer 2.

  As shown in FIG. 7, the bonded substrates are heated to, for example, 120 ° C. or more and 600 ° C. or less and from the main surface side (upper side) of the epitaxial substrate 11 not facing the epitaxial layer 4, for example, 0.2 MPa or more and 4 MPa. Apply the following pressure: In this way, the transparent conductive layer 3 and the transparent support substrate 1 can be firmly bonded via the adhesive layer 2.

  Then, a step of removing the epitaxial substrate (S50) is performed. Specifically, this is a step of removing the epitaxial substrate 11 from the laminated structure shown in FIG. 7 formed in the step (S40). As described above, the epitaxial substrate 11 is a substrate used to form the epitaxial layer 4 and is opaque to light emitted from the light emitting element 200 formed using the epitaxial substrate 100 such as gallium arsenide. Made of material. Therefore, if the light emitting element is formed using the substrate with the epitaxial substrate 11 left, the light emitted from the light emitting element is absorbed inside the epitaxial substrate 11 and the efficiency of outputting the emitted light is lowered. there's a possibility that. For this reason, in the epitaxial substrate 100 for forming the light emitting element 200, it is preferable that the epitaxial substrate 11 is removed.

Specifically, the removal of the epitaxial substrate 11 made of gallium arsenide is performed, for example, in a solution in which the mass ratio of ammonia water (NH ₄ OH) to hydrogen peroxide water (H ₂ O ₂ ) is 1.7: 1. The laminated structure shown in FIG. 7 including the epitaxial substrate 11 is immersed. In this way, the epitaxial substrate 11 is removed by wet etching, and the epitaxial substrate 100 having the laminated structure shown in FIG. 1 can be formed.

  Thus, the epitaxial substrate 100 for forming the light emitting element 200 is formed. In order to form the light emitting element 200 using the epitaxial substrate 100, the following steps shown in FIG. 4 are further performed. First, a step of etching the epitaxial layer (S60) is performed. Specifically, the epitaxial layer 4 is partially removed in order to form the light emitting element 200 shown in FIG. 3 using the epitaxial substrate 100 shown in FIG.

  In the step (S60), it is preferable to remove all of the first cladding layer 5, the active layer 6, and the second cladding layer 7 constituting the epitaxial layer 4. In other words, in the region where the epitaxial layer 4 is removed, it is preferable to perform the treatment so that the transparent conductive layer main surface 3b of the transparent conductive layer 3 is exposed.

In order to perform the above treatment, for example, a wet etching treatment using a solution having a mass ratio of 1.7: 1 ammonia water (NH ₄ OH) to hydrogen peroxide water (H ₂ O ₂ ) is desired. It is preferable to carry out with respect to the region. Alternatively, the epitaxial layer 4 may be partially etched in the same manner by a dry etching process using a chlorine-based etching gas.

  And the process (S70) of forming an electrode is performed. Specifically, as shown in FIG. 3, the epitaxial layer 4 has a main surface that does not oppose the transparent conductive layer 3 (on the main surface that does not oppose the active layer 6 of the second cladding layer 7), and adhesion of the transparent conductive layer 3. In this step, the electrode 9 and the electrode 10 are formed on the main surface opposite to the layer 2. In addition, after performing the process of forming the electrode 9 first, you may make it implement the process (S60) of etching the epitaxial layer demonstrated previously, and the process of forming the electrode 10 after that.

As shown in FIG. 3, both the electrode 9 and the electrode 10 exist on the same side (upper side) with respect to the main surface of the transparent support substrate 1. As a material of the electrode 9, it is preferable to use a material that is in ohmic contact with Al _x In _y Ga _1-xy As. In the case where the second cladding layer 7 serving as the base of the electrode 9 is a p-type semiconductor material, the electrode 9 is preferably an alloy of gold (Au) and Zn (zinc). When the second cladding layer 7 is an n-type semiconductor material, the electrode 9 is preferably made of an alloy of gold (Au), germanium (Ge), and nickel (Ni).

  As the material of the electrode 10, it is preferable to use a material that has sufficient adhesion to ITO and that makes ohmic contact with ITO. Specifically, for example, it is preferable to use a laminated structure of titanium (Ti) and gold (Au) or a laminated structure of chromium (Cr) and gold (Au). The electrodes 9 and 10 can be formed using a generally known method such as a resistance heating vapor deposition method, an ion beam vapor deposition method, or a sputtering method.

  Finally, as another step (S80), for example, when the light to be emitted is reflected once and then output to the outside, the light reflecting layer 8 shown in FIG. 3 is formed as necessary. As the light reflecting layer 8, it is preferable to use, for example, a material capable of reflecting light emitted from the epitaxial layer 4 (for example, infrared rays having a wavelength of 850 nm or more and 950 nm or less) at a high rate. Specifically, for example, aluminum (Al) is used. It is preferable to use silver (Ag). For example, as shown in FIG. 3, when the light reflecting layer 8 is disposed on the main surface of the transparent support substrate 1 that does not face the adhesive layer 2, generally known methods such as resistance heating vapor deposition, ion beam vapor deposition, and sputtering are generally used. It is preferable to form the film so as to have a thickness of 0.05 μm or more and 1 μm or less.

(Embodiment 2)
As shown in FIG. 8, the epitaxial substrate 300 according to the second embodiment has basically the same mode as the epitaxial substrate 100 according to the first embodiment. However, in the epitaxial substrate 300, each main surface of the transparent conductive layer 3 (transparent conductive layer main surfaces 3a, 3b) is roughened. That is, the transparent conductive layer main surfaces 3a and 3b of the epitaxial substrate 300 have a higher surface roughness (rough surface) than the transparent conductive layer main surfaces 3a and 3b of the epitaxial substrate 100. Since the transparent conductive layer main surfaces 3a and 3b of the epitaxial substrate 300 have high surface roughness, there are many disordered uneven shapes on the main surfaces. In order to show this, in FIG. 8, the transparent conductive layer main surfaces 3a and 3b are depicted in a saw blade shape.

  Consider a case where a light-emitting element similar to the above-described light-emitting element 200 is formed using the epitaxial substrate 300 having such an aspect, for example. In the light emitting element, light emitted from the epitaxial layer travels toward the transparent conductive layer 3. At this time, if the surface roughness of the transparent conductive layer main surfaces 3a and 3b is high and the shape of the transparent conductive layer main surfaces 3a and 3b has a large number of irregular shapes, the transparent conductive layer main surfaces 3a and 3b In this case, it is possible to reduce the possibility that the light undergoes total reflection.

  If the surface roughness of the transparent conductive layer main surfaces 3a and 3b is small, the light incident on the transparent conductive layer 3 from the epitaxial layer 4 is transparent depending on the angle at which light emitted from the epitaxial layer 4 is incident on the transparent conductive layer 3. There is a possibility of total reflection on the conductive layer main surface 3b. If the light undergoes total reflection at the transparent conductive layer main surface 3b, it is less likely that the light will be confined inside the light emitting element and taken out to the outside. For this reason, the output of the said light in a desired location becomes weak. In order to suppress such a phenomenon, it is preferable to increase the surface roughness of the transparent conductive layer main surfaces 3a and 3b. On the main surface with many irregularities, light is transmitted or diffusely reflected without causing total reflection. For this reason, generation | occurrence | production of the phenomenon that light does not come out of the light emitting element by total reflection can be suppressed.

  Even when the transparent conductive layer main surfaces 3a and 3b having a large number of irregularities are used, if the adhesive layer 2 having high elasticity is used as in the epitaxial substrate 100 of the first embodiment, the transparent conductive layer The bonding strength between the layer 3 and the transparent support substrate 1 can be improved. For this reason, the yield of the epitaxial substrate 300 can be improved.

  In order to increase the surface roughness of the transparent conductive layer main surface 3b of the transparent conductive layer 3 made of ITO, for example, facing the epitaxial layer 4, the following treatment is preferably performed. That is, after the epitaxial layer 4 (first cladding layer 5) is formed in the step (S20) described above, the main surface of the first cladding layer 5 on which the transparent conductive layer 3 is formed is wet-etched using a nitric acid-based solution. Thus, it is preferable to roughen the desired main surface of the first cladding layer 5. Or you may form many fine uneven | corrugated shapes of a micron order with respect to the main surface which forms the transparent conductive layer 3 of the 1st clad layer 5 using a photolithographic technique.

  In order to increase the surface roughness of the transparent conductive layer main surface 3a of the transparent conductive layer 3, the following treatment is preferably performed. That is, after the transparent conductive layer 3 is formed in the step (S30) described above, the transparent conductive layer main surface 3a is roughened by wet etching on the transparent conductive layer main surface 3a using a hydrofluoric acid (HF) -based solution. It is preferable to face. Or you may form many fine uneven | corrugated shapes of a micron order with respect to the transparent conductive layer main surface 3a main surface using a photolithographic technique.

  The surface roughness of the transparent conductive layer main surfaces 3a and 3b after the roughening treatment is preferably Ra of 0.05 μm or more and 5 μm or less.

  The second embodiment is different from the first embodiment only in each point described above. In other words, the configuration, conditions, procedures, effects, and the like not described above for the second embodiment are all in accordance with the first embodiment.

(Embodiment 3)
Epitaxial substrate 400 according to the third embodiment has basically the same aspect as epitaxial substrate 100 according to the first embodiment. However, as shown in FIG. 9, the epitaxial substrate 400 uses the opaque support substrate 12 as a support substrate. A light reflecting layer 8 is provided between the transparent conductive layer 3 and the adhesive layer 2.

  As the opaque support substrate 12, for example, gallium arsenide, which is formed using the epitaxial substrate 400 and has a low ratio of transmitting light emitted from a light emitting element 500 (see FIG. 20) described later, can be used. As the adhesive layer 2, an adhesive layer made of a transparent BCB resin or the like may be used similarly to the above-described epitaxial substrate 100 or the like, but an adhesive layer made of a material opaque to the light emitted from the light emitting element 500. May be used.

  In the light emitting device formed using the epitaxial substrates 100 and 300 described above, the support substrate is the transparent support substrate 1, and the light emitted from the epitaxial layer 4 is transmitted through the transparent conductive layer 3, the adhesive layer 2, and the transparent support substrate 1. For example, it has the structure which outputs from the lower main surface of the transparent support substrate 1. FIG. However, the support substrate of the epitaxial substrate 400 is the opaque support substrate 12. Here, for example, consider the light emitting device 500 of FIG. 10 formed using the epitaxial substrate 400 of FIG. The light emitting element 500 cannot transmit the light emitted from the epitaxial layer 4 through the opaque support substrate 12 and output it from, for example, the main surface below the opaque support substrate 12. For this reason, in the epitaxial substrate 400, the light reflecting layer 8 is disposed on the transparent conductive layer main surface 3 a of the transparent conductive layer 3.

  In the light reflection layer 8, for example, light is emitted from the epitaxial layer 4, and light going to the opaque support substrate 12 is reflected. The reflected light is turned upward, for example, in FIG. For this reason, the said light can be output from the main surface above the 2nd cladding layer 7 in which the electrode 9 is arrange | positioned, and the transparent conductive layer main surface 3b in which the electrode 10 is arrange | positioned, for example. If the light is reflected at a high rate by the light reflecting layer 8 disposed at the position of FIG. 10, the distance through the inside of the laminated structure is short by the amount that the light does not enter the inside of the opaque support substrate 12. For this reason, the proportion absorbed in the laminated structure is reduced. Therefore, the light can be output to the outside at a higher rate.

  If it does in this way, you may use a transparent material with respect to the light emitted like the light emitting element 200 as a support substrate of the light emitting element which can diffuse an electric current using the transparent conductive layer 3, for example, For example, an opaque material such as the light emitting element 500 may be used.

  After the step (S30) of FIG. 4, the light reflecting layer 8 of the epitaxial substrate 400 is formed on the transparent conductive layer main surface 3a by using a generally known method such as a vacuum deposition method, an ion beam deposition method, or an ion sputtering method. The thickness is preferably 0.05 μm or more and 1 μm or less. For this reason, in the manufacturing process of the epitaxial substrate 400, the other process (S80) shown in FIG. 4 can be omitted.

  The third embodiment is different from the first embodiment only in each point described above. That is, the configuration, conditions, procedures, effects, and the like that have not been described above for the third embodiment are all in accordance with the first embodiment.

(Embodiment 4)
Epitaxial substrate 600 according to the fourth embodiment has basically the same mode as epitaxial substrate 100 according to the first embodiment. However, as shown in FIG. 11, the epitaxial substrate 600 is different from the epitaxial substrate 100 shown in FIG. 1 in that the embedded substrate 21 is in contact with the transparent conductive layer 3. Specifically, the epitaxial substrate 600 further includes a buried electrode 21 that is directly connected to the transparent conductive layer 3 and made of a conductive material different from that of the transparent conductive layer 3. The transparent conductive layer 3 has an opening 22 as a through hole that reaches from the surface facing the adhesive layer 2 to the surface facing the epitaxial layer 4. The embedded electrode 21 is disposed so as to fill the inside of the opening 22.

  The planar shape of the opening 22 is a quadrangular shape as shown in FIG. 12, but may be any other shape (for example, a triangular shape, a polygonal shape of pentagon or more, a circular shape, an elliptical shape, etc.). . Further, the planar shape of the embedded electrode 21 (the outer peripheral portion 24 of the embedded electrode 21 in FIG. 12) is also a quadrangular shape as shown in FIG. 12, but may be any other shape as described above. However, the planar shape of the embedded electrode 21 may be similar to the planar shape of the opening 22. Further, the planar shape of the embedded electrode 21 may be larger than the planar shape of the opening 22. In this case, since a part (extending portion) of the embedded electrode 21 extends from the inside of the opening 22 to the surface of the transparent conductive layer 3, the contact area between the embedded electrode 21 and the transparent conductive layer 3. Can be further increased.

  A plurality of embedded electrodes 21 may be formed on the epitaxial substrate 600 at a predetermined interval. As will be described later, one embedded electrode 21 is preferably formed for each element (light emitting element) formed using the epitaxial substrate 600. Therefore, for example, the embedded electrodes 21 may be arranged in a matrix in the epitaxial substrate 600, or may be arranged so as to form a triangular lattice or a square lattice with a predetermined interval.

  In the epitaxial substrate 600 shown in FIG. 11, in addition to the effects obtained by the epitaxial substrate 100 according to the first embodiment described above, as shown in FIGS. When forming the electrode 10 electrically connected to the transparent conductive layer 3 by partially removing the epitaxial layer 4, the embedded electrode 21 can be used as an etching stopper in the etching process of the epitaxial layer 4.

  In addition, the contact area between the buried electrode 21 and the transparent conductive layer 3 can be made wider than when the opening 22 is not formed. For this reason, the adhesive strength between the transparent conductive layer 3 and the embedded electrode 21 can be further increased. Further, the buried electrode 21 is in contact with the epitaxial layer 4 at one end of the opening 22 (the end of the opening 22 on the surface side facing the epitaxial layer 4 in the transparent conductive layer 3). Therefore, the buried electrode can be reliably used as an etching stopper in etching the epitaxial layer 4.

  In addition, when current is supplied to the transparent conductive layer 3 through the embedded electrode 21, the contact area between the embedded electrode 21 and the transparent conductive layer 3 forms the opening 22, so that the opening 22 exists. Since it becomes wider than the case where it does not, it can supply an electric current to the transparent conductive layer 3 more stably. For this reason, the current equalization in the transparent conductive layer 3 can be further promoted. Therefore, as a result, the light output of the light-emitting element 700 shown in FIGS. 12 and 13 formed using the epitaxial substrate 600 can be improved.

  Further, in the epitaxial substrate 600, the embedded electrode 21 may include an extended portion (flange portion) that extends on the main surface of the transparent conductive layer 3 facing the adhesive layer 2 and is in direct contact with the transparent conductive layer 3. Good. In this case, the contact area between the embedded electrode 21 and the transparent conductive layer 3 is further widened by the extending portion. Therefore, when current is supplied to the transparent conductive layer 3 through the embedded electrode 21, the transparent conductive layer can be more stably transferred. Current can be supplied to layer 3. Further, since the contact area is increased, the adhesive strength between the transparent conductive layer 3 and the embedded electrode 21 can be further increased.

  A light emitting element 700 shown in FIGS. 12 and 13 is a light emitting element formed using the epitaxial substrate 600 shown in FIG. The light-emitting element 700 basically has the same configuration as that of the light-emitting element 200 shown in FIG. 3, but the structure around the electrode 10 is the light-emitting element shown in FIG. It is different from 200. Specifically, in the light emitting device 700 shown in FIGS. 12 and 13, the opening 23 is formed by removing at least a part of the epitaxial layer 4 so that a part of the embedded electrode 21 is exposed. . The planar shape of the opening 23 is a square shape, but the shape of the opening 23 can be any other shape (triangular shape, polygonal shape of pentagon or higher, circular shape, elliptical shape, etc.). However, the planar shape of the opening 23 is preferably smaller than the planar shape of the opening 22 formed in the transparent conductive layer 3 (that is, the planar shape of the upper surface of the embedded electrode 21). Electrodes 9 and 10 are provided on a part of the exposed embedded electrode 21 and on the main surface opposite to the main surface of the epitaxial layer 4 facing the transparent conductive layer 3. The planar shape of the electrode 10 is a quadrangular shape, but may be any other shape (triangular shape, pentagonal or higher polygonal shape, circular shape, elliptical shape, etc.). The planar shape of the electrode 10 is preferably similar to the planar shape of the opening 23. The planar shape of the electrode 9 is substantially circular, and a linear extension electrode portion extending from the electrode 9 on the surface of the epitaxial layer 4 is formed. This extended electrode portion is formed in order to supply current to the epitaxial layer 4 as uniformly as possible.

  With this configuration, when a voltage is applied between the electrodes 9 and 10, a current can flow almost uniformly from the electrode 10 to the wide area inside the transparent conductive layer 3 through the embedded electrode 21. . Therefore, the emitted light also has little variation between regions, and light can be output almost uniformly.

  Next, a method for manufacturing the epitaxial substrate 600 will be described. As shown in the flowchart of FIG. 14, first, a step of preparing an epitaxial substrate (S10) is performed. Specifically, as in the first embodiment, an epitaxial substrate 11 shown in FIG. 5 is prepared.

  Next, similarly to the first embodiment, an epitaxial layer forming step (S20) is performed. Specifically, as shown in FIG. 5, the epitaxial layer 4 is formed on one main surface of the epitaxial substrate 11.

  Next, similarly to the first embodiment, a step of forming ITO (S30) is performed. Specifically, as shown in FIG. 6, this is a step of forming an ITO thin film as the transparent conductive layer 3 on the main surface of the epitaxial layer 4 formed in the step (S20).

  Next, as shown in FIG. 14, a step of forming a metal layer (S90) is performed. Specifically, first, the step of etching the ITO shown in FIG. 15 to form an opening (S91) is performed. In the step (S91) as the step of forming the opening, as shown in FIG. 16, a resist film 25 having a predetermined opening pattern 26 is formed on the transparent conductive layer 3. The opening pattern 26 has the same planar shape as the planar shape of the opening 22 formed in the transparent conductive layer 3.

  Next, the transparent conductive layer 3 is partially removed by etching using the resist film 25 as a mask. As a result, an opening 22 is formed in the transparent conductive layer 3 as shown in FIG. Thereafter, the resist film 25 is removed.

  Next, a step of forming a metal film in the opening (S92) as a step of forming the embedded electrode shown in FIG. 15 is performed. Specifically, a resist film 27 having a predetermined opening pattern is first formed on the transparent conductive layer 3 as shown in FIG. The opening pattern overlaps the opening 22 previously formed in the transparent conductive layer 3 and has the same planar shape as the planar shape of the embedded electrode 21 to be formed.

  Next, as shown in FIG. 19, a conductor film 28 is formed inside the opening pattern and on the upper surface of the resist film 27. The conductor film 28 is a conductor to be the embedded electrode 21 and can be made of any material as long as it has conductivity. However, the conductor film 28 has a different etching rate from the epitaxial layer 4 and / or the transparent conductive layer 3. It is preferable that the material is a conductive material. As a method of forming the conductor 28, any conventionally known method can be used. Then, the resist film 27 is removed using a chemical solution or the like. At this time, the conductor film 28 formed on the upper surface of the resist film 27 is also removed (lift-off) at the same time. As a result, as shown in FIG. 20, it is possible to form the embedded electrode 21 that fills the inside of the opening 22 and has an extending portion that partially extends to the upper surface of the transparent conductive layer 3. .

  When the embedded electrode 21 is formed as shown in FIG. 20, a step (S40) of bonding the support substrate is performed as shown in FIG. Specifically, as in the first embodiment, the surface on which the transparent conductive layer 3 and the embedded electrode 21 shown in FIG. 20 are formed is connected to one main surface of the transparent support substrate 1 shown in FIG. To join. In FIG. 21, the laminated structure shown in FIG. 20 is turned upside down and bonded to the transparent support substrate 1 using the adhesive layer 2.

  Next, as in the first embodiment, the bonded substrates as shown in FIG. 21 are heated to, for example, 120 ° C. or higher and 600 ° C. or lower, and the main surface of the epitaxial substrate 11 that does not face the epitaxial layer 4 For example, a pressure of 0.2 MPa or more and 4 MPa or less may be applied from the side (upper side). In this way, the transparent conductive layer 3 and the transparent support substrate 1 can be firmly bonded via the adhesive layer 2.

  Next, as shown in FIG. 14, a step (S50) of removing the epitaxial substrate is performed. Specifically, similarly to the first embodiment, the epitaxial substrate 11 is removed from the laminated structure shown in FIG. 21 formed in the step (S40). As a method for removing the epitaxial substrate 11, any conventionally known method can be used so as to match the material of the epitaxial substrate 11.

  Thus, the epitaxial substrate 600 for forming the light emitting element 700 is formed. And in order to form the light emitting element 700 using the said epitaxial substrate 600, each following process shown in FIG. 14 is further performed. First, a step of forming a first electrode (S71) is performed. Specifically, as shown in FIG. 22, on the upper surface of the epitaxial layer 4, from a different viewpoint, on the main surface not facing the transparent conductive layer 3 of the epitaxial layer 4 (the active layer 6 of the second cladding layer 7 and An electrode 9 is formed on the non-opposing main surface). As a method for forming the electrode 9, any conventionally known method can be used.

  Next, as shown in FIG. 14, a step of etching the epitaxial layer (S60) is performed. Specifically, as shown in FIG. 23, the epitaxial layer 4 is partially removed to form the opening 23. In this step (S60), an opening 23 is formed at a position overlapping the embedded electrode 21 so that the upper surface of the embedded electrode 21 is exposed. Any method can be used for forming the opening 23. For example, a resist film having a predetermined opening pattern is formed on the epitaxial layer 4, and the epitaxial layer 4 is formed by etching using the resist film as a mask. A method such as partial removal can be used. At this time, if the embedded electrode 21 is made of, for example, metal, the embedded electrode 21 acts as an etching stopper.

  Next, a step of forming a second electrode (S72) is performed. Specifically, as shown in FIG. 24, the electrode 10 is formed on the upper surface of the embedded electrode 21 exposed at the bottom of the opening 23. As a method for forming the electrode 10, a conventionally known method such as a lift-off method can be used.

  As the material of the electrode 10, it is preferable to use a material that has sufficient adhesion to the embedded electrode 21 and that makes ohmic contact with the embedded electrode 21. Specifically, for example, it is preferable to use a laminated structure of titanium (Ti) and gold (Au), or a single-layer structure or a laminated structure of any metal.

  Next, as shown in FIG. 14, other steps (S80) may be performed. As the step (S80), as in the first embodiment, for example, when the emitted light is reflected once and then output to the outside, the light reflecting layer 8 shown in FIG. 13 is formed as necessary. . In this manner, the light emitting element 700 shown in FIGS. 12 and 13 can be obtained.

  Next, a modification of the epitaxial substrate 600 shown in FIG. 11 will be described with reference to FIG. The epitaxial substrate 600 shown in FIG. 25 basically has the same configuration as the epitaxial substrate 600 shown in FIG. 11, but the configuration of the buried electrode 21 is different from that of the epitaxial substrate 600 shown in FIG. Specifically, in the epitaxial substrate 600 shown in FIG. 25, the embedded electrode 21 has a laminated structure composed of two layers of a first conductor layer 31 and a second conductor layer 32. It should be noted that a laminated structure of three or more layers may be adopted as the structure of the embedded electrode 21.

  In the epitaxial substrate 600 shown in FIG. 25, the first conductor layer 31 includes a lower surface of the epitaxial layer 4, a side wall of the opening 22 of the transparent conductive layer 3, and a portion adjacent to the opening 22 of the transparent conductive layer main surface 3a. In contact. The second conductor layer 32 is in contact with the surface of the first conductor layer 31 opposite to the surface in contact with the epitaxial layer 4.

  That is, in the epitaxial substrate 600, the embedded electrode 21 has a multilayer structure in which the first conductor layer 31 and the second conductor layer 32 which are a plurality of different kinds of conductor layers are stacked. In this case, the same effect as that of the epitaxial substrate 600 shown in FIG. 11 can be obtained, and the degree of freedom in selecting the material of the embedded electrode 21 can be increased.

  In the epitaxial substrate 600, in the embedded electrode 21, the plurality of conductor layers constituting the multilayer structure include the first conductor layer 31 and the second conductor layer 32. The first conductor layer 31 is in contact with the transparent conductive layer 3 and the epitaxial layer 4. The second conductor layer 32 is formed so as to be in contact with the surface of the first conductor layer 31 that is located on the opposite side of the surface that is in contact with the transparent conductive layer 3. The first conductor layer 31 preferably has higher adhesion to the transparent conductive layer 3 and the epitaxial layer 4 than the second conductor layer 32. The second conductor layer 32 may have a higher selectivity to the etchant that etches the epitaxial layer 4 than the first conductor layer 31. In this case, the embedded electrode 21 can be reliably connected and fixed to the transparent conductive layer 3 and the epitaxial layer 4 by the first conductor layer 31, and the embedded electrode 21 is opened in the epitaxial layer 4 by the second conductor layer 32. In the etching for forming the portion 23, the function as an etching stopper can be surely exhibited.

In the epitaxial substrate 600, the first conductor layer 31 may be made of at least one of chromium (Cr) and titanium (Ti). In this case, the epitaxial layer 4 has a structure in which a plurality of Al _x In _y Ga _1-xy As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) are laminated, and the transparent conductive layer 3 is made of ITO. May be. In this case, the first conductor layer 31 can be reliably fixed to the transparent conductive layer 3 and the epitaxial layer 4.

  In the epitaxial substrate 600, the second conductor layer 32 may be made of at least one selected from the group consisting of gold (Au), platinum (Pt), and palladium (Pd). In this case, since the second conductor layer 32 is made of a material having a high selectivity with respect to the epitaxial layer 4, the embedded electrode 21 can be reliably used as an etching stopper in etching the epitaxial layer 4.

  A light emitting device 700 shown in FIG. 26 is a light emitting device 700 using the epitaxial substrate 600 shown in FIG. 25, and basically has the same configuration as the light emitting device 700 shown in FIGS. As described above, the embedded electrode 21 has a laminated structure, which is different from the light emitting element 700 shown in FIGS. In the light emitting element 700 shown in FIG. 26, the electrode 10 is formed on the surface of the first conductor layer 31 of the embedded electrode 21. In this case, in addition to the effect similar to the effect obtained by the light emitting element 700 shown in FIGS. 12 and 13, the embedded electrode 21 can be used as an etching stopper when the opening 23 is formed as described above. . In addition, when a current is passed from the electrode 10 to the transparent conductive layer 3 through the embedded electrode 21, the current is supplied to the transparent conductive layer 3 by increasing the contact area between the embedded electrode 21 and the transparent conductive layer 3. It can be performed more uniformly. Note that the laminated structure of the embedded electrode 21 described above can be applied to the fifth and sixth embodiments of the present invention described later.

(Embodiment 5)
Epitaxial substrate 600 according to the fifth embodiment has basically the same mode as epitaxial substrate 600 according to the fourth embodiment shown in FIG. However, as shown in FIG. 27, the epitaxial substrate 600 is different from the epitaxial substrate 600 shown in FIG. 11 in that the opening 22 formed in the transparent conductive layer 3 does not penetrate the transparent conductive layer 3.

  That is, in the epitaxial substrate 600, the embedded electrode 21 is disposed on the surface of the transparent conductive layer 3 that faces the adhesive layer 2. On the surface of the transparent conductive layer 3, an opening 22 as a recess is formed in a portion where the embedded electrode 21 is disposed. The embedded electrode 21 includes a protrusion that fills the inside of the opening 22.

  In this case, the contact area between the embedded electrode 21 and the transparent conductive layer 3 can be made larger than when the opening 22 is not formed. For this reason, the adhesive strength between the transparent conductive layer 3 and the embedded electrode 21 can be increased. Further, when the current is supplied to the transparent conductive layer 3 via the embedded electrode 21, the contact area between the embedded electrode 21 and the transparent conductive layer 3 is widened, so that the current is supplied to the transparent conductive layer 3 more stably. Can supply. For this reason, since the current uniformity in the transparent conductive layer 3 can be further promoted, as a result, the light output of the light emitting element 700 as shown in FIG. 28 formed using the epitaxial substrate 600 can be improved.

  A light emitting element 700 shown in FIG. 28 is a light emitting element formed using the epitaxial substrate 600 shown in FIG. The light-emitting element 700 basically has the same configuration as the light-emitting element 700 shown in FIGS. 12 and 13, but the electrode 22 is formed so as not to penetrate the transparent conductive layer 3. 10 is different from the light emitting element 700 shown in FIGS. 12 and 13. Specifically, in the light emitting element 700 shown in FIG. 28, a part of the transparent conductive layer 3 is removed in addition to the epitaxial layer 4 so that a part of the embedded electrode 21 is exposed, whereby the opening 23 is formed. Has been. That is, the side wall of the opening 23 is constituted by the end surfaces of the epitaxial layer 4 and the transparent conductive layer 3. Even with such a configuration, the same effect as that of the light-emitting element 700 illustrated in FIGS. 12 and 13 can be obtained.

  Next, a method for manufacturing the epitaxial substrate 600 will be described. As shown in the flowchart of FIG. 14 in the fourth embodiment, a process of preparing an epi substrate (S10) to a process of forming ITO (S30) are performed. And the process (S90) of forming a metal layer is implemented. Specifically, the step (S91) of forming an opening by etching the ITO shown in FIG. However, in this step (S91), as shown in FIG. 29, the opening 22 formed in the transparent conductive layer 3 does not penetrate the transparent conductive layer 3. That is, the side wall and the bottom wall of the opening 22 are all constituted by the surface of the transparent conductive layer 3.

  After removing the resist film 25 from the state shown in FIG. 29, a step (S92) of forming a metal layer in the opening shown in FIG. 15 is performed. The specific process of this process (S92) is basically the same as the process (S92) in the fourth embodiment. As a result, as shown in FIG. 30, the embedded electrode 21 is formed so as to fill the inside of the opening 22 and cover a part of the upper surface of the transparent conductive layer 3.

  Next, a step (S40) for bonding the support substrate and a step (S50) for removing the epitaxial substrate shown in FIG. 14 are performed. As a result, an epitaxial substrate 600 shown in FIG. 27 can be obtained.

  Next, in order to form the light emitting element 700 shown in FIG. 28 using the epitaxial substrate 600, a step of forming a first electrode (S71) is performed in the same manner as in the fourth embodiment. Then, the process (S60) of etching an epitaxial layer is implemented. Specifically, as shown in FIG. 31, a part of the epitaxial layer 4 and the transparent conductive layer 3 located on the embedded electrode 21 is removed by etching. As a result, a structure as shown in FIG. 31 is obtained.

  Thereafter, the step of forming the second electrode shown in FIG. 14 (S72) and the other step (S80) are performed, whereby the light emitting device 700 shown in FIG. 28 can be obtained.

  Next, a modification of epitaxial substrate 600 shown in FIG. 27 will be described with reference to FIG. The epitaxial substrate 600 shown in FIG. 32 basically has the same configuration as that of the epitaxial substrate 600 shown in FIG. 27, but the configuration of the buried electrode 21 is different from that of the epitaxial substrate 600 shown in FIG. Specifically, in the epitaxial substrate 600 shown in FIG. 32, the embedded electrode 21 is composed of two layers, a first conductor layer 31 and a second conductor layer 32, as in the epitaxial substrate 600 shown in FIG. It has a laminated structure. It should be noted that a laminated structure of three or more layers may be adopted as the structure of the embedded electrode 21. The embedded electrode 21 shown in FIG. 32 can basically adopt the same configuration (for example, material or laminated structure) as the embedded electrode 21 shown in FIG.

  In epitaxial substrate 600 shown in FIG. 25, first conductive layer 31 is in contact with the side wall and bottom wall of opening 22 of transparent conductive layer 3 and the portion adjacent to opening 22 of transparent conductive layer main surface 3a. . The second conductor layer 31 is in contact with the surface of the first conductor layer 31 opposite to the surface in contact with the epitaxial layer 4. With such a configuration, in addition to the effect of the epitaxial substrate 600 shown in FIG. 27, the effect of the epitaxial substrate 600 shown in FIG. 25 is obtained.

  A light emitting device 700 shown in FIG. 33 is a light emitting device 700 using the epitaxial substrate 600 shown in FIG. 32, and basically has the same configuration as the light emitting device 700 shown in FIG. Thus, the point that the embedded electrode 21 has a laminated structure is different from the light emitting element 700 shown in FIG. In the light emitting element 700 shown in FIG. 33, the electrode 10 is formed on the surface of the first conductor layer 31 of the embedded electrode 21. In this case, the same effect as that obtained by the light emitting element 700 shown in FIG. 28 can be obtained. Further, when a current is passed from the electrode 10 to the transparent conductive layer 3 through the embedded electrode 21, the planar shape of the opening 23 is made smaller than the planar shape of the opening 22, so that the embedded electrode 21 and the transparent conductive layer 3 are made. The contact area with can be increased. For this reason, current can be supplied to the transparent conductive layer 3 more uniformly.

(Embodiment 6)
Epitaxial substrate 600 according to the sixth embodiment has basically the same mode as epitaxial substrate 600 according to the fourth embodiment shown in FIG. However, as shown in FIG. 34, the epitaxial substrate 600 is different from the epitaxial substrate 600 shown in FIG. 11 in that the opening 22 is not formed in the transparent conductive layer 3.

  That is, in the epitaxial substrate 600, the embedded electrode 21 is disposed on the surface of the transparent conductive layer 3 that faces the adhesive layer 2. In this case, after the transparent conductive layer 3 is formed, the embedded electrode 21 can be formed subsequently. Further, since the embedded electrode 21 can be formed on the transparent conductive layer 3 without particularly forming the opening 22, it is not necessary to carry out the process of forming the opening 22, thereby avoiding complicated manufacturing processes. be able to.

  A light-emitting element 700 illustrated in FIG. 35 is a light-emitting element formed using the epitaxial substrate 600 illustrated in FIG. The light emitting element 700 basically has the same configuration as the light emitting element 700 shown in FIGS. 12 and 13, but the opening 22 as shown in FIGS. 12 and 13 is formed in the transparent conductive layer 3. Therefore, the configuration around the electrode 10 is different from the light emitting element 700 shown in FIGS. Specifically, in the light emitting device 700 shown in FIG. 35, an opening 23 is formed so as to penetrate the transparent conductive layer 3 in addition to the epitaxial layer 4 so that a part of the embedded electrode 21 is exposed. That is, the side wall of the opening 23 is constituted by the end surfaces of the epitaxial layer 4 and the transparent conductive layer 3. Even with such a configuration, the same effect as that of the light-emitting element 700 illustrated in FIGS. 12 and 13 can be obtained.

  Next, a method for manufacturing the epitaxial substrate 600 will be described. As shown in the flowchart of FIG. 14 in the fourth embodiment, a process of preparing an epi substrate (S10) to a process of forming ITO (S30) are performed. And the process (S90) of forming a metal layer is implemented. Specifically, the step of forming the metal layer is performed without performing the step of forming the opening by etching the ITO shown in FIG. 15 (S91). A specific method for forming the metal layer is the same as the step (S92) of forming the metal layer in the opening shown in FIG. As a result, as shown in FIG. 36, a plurality of embedded electrodes 21 are formed so as to cover a part of the upper surface of the transparent conductive layer 3. As shown in FIG. 36, the embedded electrode 21 is formed on the flat surface of the transparent conductive layer 3.

  Next, a step (S40) for bonding the support substrate and a step (S50) for removing the epitaxial substrate shown in FIG. 14 are performed. As a result, an epitaxial substrate 600 shown in FIG. 34 can be obtained.

  Next, in order to form the light emitting element 700 shown in FIG. 35 using the epitaxial substrate 600, the step of forming the first electrode (S71) is performed in the same manner as in the fourth embodiment. Then, the process (S60) of etching an epitaxial layer is implemented. Specifically, as shown in FIG. 37, the epitaxial layer 4 and the transparent conductive layer 3 located on the buried electrode 21 are removed by etching. As a result, a structure as shown in FIG. 37 is obtained.

  Thereafter, the step of forming the second electrode shown in FIG. 14 (S72) and the other step (S80) are performed, whereby the light emitting element 700 shown in FIG. 35 can be obtained.

  Next, a modification of epitaxial substrate 600 shown in FIG. 34 will be described with reference to FIG. The epitaxial substrate 600 shown in FIG. 38 basically has the same configuration as that of the epitaxial substrate 600 shown in FIG. 34, but the configuration of the buried electrode 21 is different from that of the epitaxial substrate 600 shown in FIG. Specifically, in the epitaxial substrate 600 shown in FIG. 38, the embedded electrode 21 is composed of two layers, a first conductor layer 31 and a second conductor layer 32, as in the epitaxial substrate 600 shown in FIG. It has a laminated structure. It should be noted that a laminated structure of three or more layers may be adopted as the structure of the embedded electrode 21. The embedded electrode 21 shown in FIG. 38 can basically adopt the same configuration (for example, material or laminated structure) as the embedded electrode 21 shown in FIG.

  In the epitaxial substrate 600 shown in FIG. 38, the first conductor layer 31 is in contact with the flat surface of the transparent conductive layer 3. The second conductor layer 31 is in contact with the surface of the first conductor layer 31 opposite to the surface in contact with the epitaxial layer 4. With such a configuration, the effect of the epitaxial substrate 600 shown in FIG. 25 is obtained in addition to the effect of the epitaxial substrate 600 shown in FIG.

  A light emitting element 700 shown in FIG. 39 is a light emitting element 700 using the epitaxial substrate 600 shown in FIG. 38, and basically has the same configuration as the light emitting element 700 shown in FIG. Thus, the point that the embedded electrode 21 has a laminated structure is different from the light emitting element 700 shown in FIG. In the light emitting element 700 shown in FIG. 39, the electrode 10 is formed on the surface of the first conductor layer 31 of the embedded electrode 21. In this case, the same effect as that obtained by the light emitting element 700 shown in FIG. 35 can be obtained. Further, when a current is passed from the electrode 10 to the transparent conductive layer 3 through the embedded electrode 21, the planar shape of the opening 23 is made smaller than the planar shape of the opening 22, whereby the light emitting element 700 shown in FIG. Similarly, the contact area between the buried electrode 21 and the transparent conductive layer 3 can be increased. For this reason, current can be supplied to the transparent conductive layer 3 more uniformly.

  For example, the light emitting elements 200 and 500 according to the above-described embodiments of the present invention are used in a bullet lamp 800 shown in FIG. The light emitting element chip 61 is disposed on one lead frame 62 of the pair of lead frames 62 constituting the bullet-type lamp 800. The light emitting element chip 61 is formed from the above-described light emitting elements 200, 500, 700, or a chip in which a plurality of them are integrated.

  For example, the light emitting element chip 61 is a light emitting element 200 shown in FIG. At this time, the pair of electrodes 9 and 10 of the light emitting element 200 are connected to the pair of lead frames 62 of the bullet-type lamp 600 by the bonding wires 63, respectively. Each pair of lead frames 62 is connected to a terminal such as a desired power source. A resin 64 is disposed so as to embed the upper part of the lead frame 62, the light emitting element chip 61, and the banding wire 63.

  In this manner, the voltage applied between the pair of electrodes 9 and 10 of the light emitting element 200 can be caused to emit light by the voltage applied between the pair of lead frames 62. In the case of this example, as shown in FIG. 40, the light emitting element 200 is installed on the left lead frame 62 such that the lowermost main surface of the light emitting element 200 of FIG. Therefore, the light emitting element 200 is preferably provided with the light reflecting layer 8 as shown in FIG. 3 and configured to output light from the upper side of the light emitting element 200 (the side on which the electrodes 9 and 10 are disposed). Even when the light-emitting element chip 61 is an element that does not include the light reflecting layer 8, a similar reflection effect can be obtained by mounting the element on a lead frame using a silver paste or the like. .

  As described above, the embodiments and examples of the present invention have been described. However, the embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. It is. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  INDUSTRIAL APPLICABILITY The present invention is particularly excellent as a technique for providing an epitaxial substrate that can provide a light-emitting element that can uniformly supply a current by applying a voltage and can obtain a uniform and large light emission output.

  DESCRIPTION OF SYMBOLS 1 Transparent support substrate, 2 Adhesive layer, 3 Transparent conductive layer, 3a, 3b The transparent conductive layer main surface, 4 Epitaxial layer, 5 1st cladding layer, 6 Active layer, 7 2nd cladding layer, 8 Light reflection layer, 9, DESCRIPTION OF SYMBOLS 10 Electrode, 11 Epi board | substrate, 12 Opaque support substrate, 21 Embedded electrode, 22, 23 Opening part, 24 Peripheral part of embedded electrode, 25, 27 Resist film, 26 Opening pattern, 28 Conductor film, 31 1st conductor Layer, 32 second conductor layer, 61 light emitting element chip, 62 lead frame, 63 bonding wire, 64 resin, 100,300,400,600 epitaxial substrate, 200,500,700 light emitting element, 800 shell-type lamp.

Claims (38)

A support substrate;
An adhesive layer disposed on one main surface of the support substrate;
A transparent conductive layer disposed on the main surface of the adhesive layer opposite to the main surface facing the support substrate;
An epitaxial layer disposed on the main surface of the transparent conductive layer opposite to the main surface facing the adhesive layer;
A part of the second main surface opposite to the first main surface facing the adhesive layer of the transparent conductive layer is exposed, on the exposed second main surface, and the epitaxial layer A light emitting device comprising: an electrode formed on a main surface opposite to the main surface facing the transparent conductive layer. 2. The light emitting device according to claim 1, wherein the epitaxial layer has a configuration in which a plurality of Al _x In _y Ga _1-xy As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) are stacked.   The light emitting device according to claim 1, wherein the transparent conductive layer is ITO.   The light-emitting element according to claim 1, wherein the adhesive layer includes any one selected from the group consisting of a BCB resin, a polyimide resin, an epoxy resin, and a silicone resin.   The light emitting device according to claim 1, wherein the support substrate is a transparent support substrate that is transparent to light emitted from the epitaxial layer.   The light-emitting element according to claim 5, wherein the transparent support substrate includes any one selected from the group consisting of sapphire, glass, silicon carbide, gallium phosphide, quartz, and spinel.   The light emitting element of any one of Claims 1-6 by which the one main surface of the said transparent conductive layer and the other main surface facing the said one main surface are roughened.   In any region between the main surface of the transparent conductive layer opposite to the main surface facing the epitaxial layer and the main surface of the support substrate opposite to the epitaxial layer, The light emitting element of any one of Claims 1-7 further provided with the reflection layer which reflects the light light-emitted in a layer. A support substrate;
An adhesive layer disposed on one main surface of the support substrate;
A transparent conductive layer disposed on the main surface of the adhesive layer opposite to the main surface facing the support substrate;
An epitaxial layer disposed on the main surface of the transparent conductive layer opposite to the main surface facing the adhesive layer;
A buried electrode made of a conductive material directly connected to the transparent conductive layer and different from the transparent conductive layer;
An opening is formed by removing at least a portion of the epitaxial layer so that a portion of the embedded electrode is exposed,
A light emitting device further comprising an electrode formed on a part of the exposed embedded electrode and on a main surface opposite to the main surface of the epitaxial layer facing the transparent conductive layer.   The light-emitting element according to claim 9, wherein the embedded electrode is disposed on a surface of the transparent conductive layer that faces the adhesive layer. In the surface of the transparent conductive layer, a recess is formed in a portion where the embedded electrode is disposed,
The light emitting device according to claim 10, wherein the embedded electrode includes a protrusion that fills the inside of the recess. The transparent conductive layer is formed with a through hole reaching from the surface facing the adhesive layer to the surface facing the epitaxial layer,
The light emitting device according to claim 9, wherein the embedded electrode is disposed so as to fill the inside of the through hole.   The light-emitting element according to claim 12, wherein the embedded electrode includes an extending portion that extends on the main surface facing the adhesive layer in the transparent conductive layer and directly contacts the transparent conductive layer.   The light-emitting element according to claim 9, wherein the embedded electrode has a multilayer structure in which a plurality of different types of conductor layers are stacked. In the embedded electrode, the plurality of conductor layers constituting the multilayer structure are:
A first conductor layer in contact with the transparent conductive layer and the epitaxial layer;
A second conductor layer formed in contact with a surface located on the opposite side of the surface in contact with the transparent conductive layer in the first conductor layer;
The first conductor layer has a relatively high adhesion to the transparent conductive layer and the epitaxial layer relative to the second conductor layer,
The light emitting device according to claim 14, wherein the second conductor layer has a higher selectivity to the etchant for etching the epitaxial layer than the first conductor layer.   The light emitting device according to claim 15, wherein the first conductor layer is made of at least one of chromium and titanium.   The light emitting device according to claim 15 or 16, wherein the second conductor layer is made of at least one selected from the group consisting of gold, platinum, and palladium. A pair of lead frames for inputting and outputting electrical signals between the light emitting device according to claim 1 and the outside;
The light emitting element disposed on the main surface of the first lead frame of the pair of lead frames;
A light-emitting device comprising: an electrode of the light-emitting element; and a wire connecting each of the first lead frame and the second lead frame. A support substrate;
An adhesive layer disposed on one main surface of the support substrate;
A transparent conductive layer disposed on the main surface of the adhesive layer opposite to the main surface facing the support substrate;
An epitaxial substrate provided with the epitaxial layer arrange | positioned on the main surface on the opposite side to the main surface facing the said contact bonding layer of the said transparent conductive layer. The epitaxial substrate according to claim 19, wherein the epitaxial layer has a structure in which a plurality of Al _x In _y Ga _1-xy As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) are stacked.   The epitaxial substrate according to claim 19 or 20, wherein the transparent conductive layer is ITO.   The epitaxial substrate according to any one of claims 19 to 21, wherein the adhesive layer includes any one selected from the group consisting of a BCB resin, a polyimide resin, an epoxy resin, and a silicone resin.   The epitaxial substrate according to any one of claims 19 to 22, wherein the support substrate is a transparent support substrate that is transparent to light emitted from the epitaxial layer.   24. The epitaxial substrate according to claim 23, wherein the transparent support substrate includes any one selected from the group consisting of sapphire, glass, silicon carbide, gallium phosphide, quartz, and spinel.   The epitaxial substrate according to claim 19, wherein one main surface of the transparent conductive layer and the other main surface opposite to the one main surface are roughened.   In any region between the main surface of the transparent conductive layer opposite to the main surface facing the epitaxial layer and the main surface of the support substrate opposite to the epitaxial layer, The epitaxial substrate according to claim 19, further comprising a reflective layer that reflects light emitted from the layer.   The epitaxial substrate according to any one of claims 19 to 26, further comprising a buried electrode that is directly connected to the transparent conductive layer and made of a conductive material different from the transparent conductive layer.   28. The epitaxial substrate according to claim 27, wherein the embedded electrode is disposed on a surface of the transparent conductive layer that faces the adhesive layer. In the surface of the transparent conductive layer, a recess is formed in a portion where the embedded electrode is disposed,
29. The epitaxial substrate according to claim 28, wherein the embedded electrode includes a protrusion that fills the inside of the recess. The transparent conductive layer is formed with a through hole reaching from the surface facing the adhesive layer to the surface facing the epitaxial layer,
28. The epitaxial substrate according to claim 27, wherein the embedded electrode is disposed so as to fill the inside of the through hole.   31. The epitaxial substrate according to claim 30, wherein the embedded electrode includes an extending portion that extends on the main surface facing the adhesive layer in the transparent conductive layer and is in direct contact with the transparent conductive layer.   The epitaxial substrate according to any one of claims 27 to 31, wherein the embedded electrode has a multilayer structure in which a plurality of different types of conductor layers are stacked. In the embedded electrode, the plurality of conductor layers constituting the multilayer structure are:
A first conductor layer in contact with the transparent conductive layer and the epitaxial layer;
A second conductor layer formed in contact with a surface located on the opposite side of the surface in contact with the transparent conductive layer in the first conductor layer;
The first conductor layer has a relatively high adhesion to the transparent conductive layer and the epitaxial layer relative to the second conductor layer,
The epitaxial substrate according to claim 32, wherein the second conductor layer has a higher selectivity to the etchant that etches the epitaxial layer than the first conductor layer.   The epitaxial substrate according to claim 33, wherein the first conductor layer is made of at least one of chromium and titanium.   35. The epitaxial substrate according to claim 33 or 34, wherein the second conductor layer is made of at least one selected from the group consisting of gold, platinum, and palladium. Preparing a substrate;
Forming an epitaxial layer on one main surface of the substrate;
Forming a transparent conductive layer on the main surface of the epitaxial layer opposite to the main surface facing the substrate;
And a step of bonding a support substrate on a main surface of the transparent conductive layer opposite to the main surface facing the epitaxial layer.   The method for manufacturing an epitaxial substrate according to claim 36, further comprising a step of forming a buried electrode made of a conductive material that is directly connected to the transparent conductive layer and is different from the transparent conductive layer. Further comprising the step of forming an opening in the transparent conductive layer,
38. The method of manufacturing an epitaxial substrate according to claim 37, wherein in the step of forming the buried electrode, the buried electrode is formed so as to fill the inside of the opening.

Images