JP2008141015A - Light emitting diode device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting diode device which has a metal reflection film having a rugged face as a reflection face, wherein it is difficult to cause a space between the device and the mounting target member when an outer surface of the metal reflection film is bonded to a surface of a mounting target member to fix the device to the mounting target member,. <P>SOLUTION: The light emitting diode device 10 has: a translucent plate-shaped body 11 containing a semiconductor layer 11B provided with a light-emitting device structure; and a metal reflection film 12 formed on a surface of the plate-shaped body 11. It is structured that at least part of a light generating in the semiconductor layer 11B is reflected by the metal reflection film 12 and exited outside of the plate-shaped body 11. The surface of the plate-shaped body 11 covered with the metal reflection film 12 is a rugged face and an outer surface of the metal reflection film 12 is flattened to form a mirror face. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a light-emitting diode element (hereinafter also referred to as “LED element”), and in particular, a translucent plate-like body including a semiconductor layer having a light-emitting element structure and a metal formed on the surface of the plate-like body. The present invention relates to a light emitting diode element that includes a reflective film, and is configured so that at least part of light generated inside the semiconductor layer is reflected by the metal reflective film and is emitted to the outside of the plate-like body.

FIG. 7 is a cross-sectional view of the LED element disclosed in Patent Document 1. A conventional LED element 100 shown in FIG. 7 includes a translucent substrate 110A made of sapphire, a translucent semiconductor layer 110B made of a group III nitride compound semiconductor (hereinafter also referred to as “nitride semiconductor”), ITO, and the like. A translucent electrode 110C made of (indium tin oxide) has a translucent plate 110 that is laminated in this order. The back surface of the light transmissive substrate 110A (the surface on which the light transmissive semiconductor layer 110B is not formed), which is one surface of the plate-like body 110, is made uneven by etching or mechanical processing, Covered with a reflective film 120. A buffer layer (not shown) is interposed between the translucent substrate 110A and the translucent semiconductor layer 110B. The translucent semiconductor layer 110B includes an n-type layer 110B-1 and a p-type layer 110B-2 that form a pn junction type light emitting element structure, and preferably an active layer is provided at the pn junction. . A negative electrode 130 is formed on the surface of the n-type layer 110B-1 partially exposed by etching. A positive electrode 140 is formed on a part of the upper surface of the translucent electrode layer 110C.

Here, the nitride semiconductor is a compound semiconductor represented by a general formula Al _a In _b Ga _1-ab N (0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ a + b ≦ 1). GaN, InGaN, AlGaN, AlInGaN, AlN, InN and the like having any composition are included. In the above chemical formula, a part of the group 3 element is substituted with B (boron), Tl (thallium), etc., and a part of N (nitrogen) is P (phosphorus), As (arsenic), Sb (antimony) Those substituted with Bi (bismuth) or the like are also included in the nitride semiconductor.

In the LED element 100 shown in FIG. 7, since the reflective surface of the metal reflective film 120 is an uneven surface, the light generated inside the translucent semiconductor layer 110B and transmitted through the translucent substrate 110A is reflected by the metal reflection. Reflected by the film 120 in various directions. Therefore, in addition to suppressing multiple reflections inside the plate 110, the light reflected by the metal reflection film 120 is also emitted from the side of the translucent substrate 110A to the outside of the element, so that the LED element 100 is high. Indicates the light output.
Japanese Patent Laid-Open No. 10-270754 Japanese Journal of Applied Physics, Vol. 45, No. 39, 2006, pp. L1045-L1047 (Japan Journal of Applied Physics, Vol. 45, No. 39, 2006, pp. L1045-L1047)

When an LED lamp is manufactured by fixing the LED element 100 shown in FIG. 7 to a placement destination member (lead frame, stem, printed circuit board, etc.), the outer surface of the metal reflective film 120 and the surface of the placement destination member Glue. At this time, since the outer surface of the metal reflective film 120 is not flat, a space is generated between the LED element 100 and the placement destination member. When such a space arises, the problem that the dissipation of the heat which generate | occur | produces in the LED element 100 is inhibited generate | occur | produces. Further, when this space is formed as bubbles, the pressure in the bubbles fluctuates with changes in temperature, so that the adhesive is stressed. This stress accelerates the deterioration of the adhesive, causing a problem that the reliability and life of the LED lamp are reduced.

The present invention has been made in view of such circumstances, and the main object of the present invention is to provide a metal reflecting film whose reflecting surface is an uneven surface, but the outer surface of the metal reflecting film is the surface of the mounting member. It is an object of the present invention to provide a light-emitting diode element in which a space is hardly generated between the element and the placement destination member when the element is fixed to the placement destination member by bonding to the substrate.

In order to achieve the above object, a light emitting diode device having the following characteristics is provided.
(1) A translucent plate-like body including a semiconductor layer having a light-emitting element structure, and a metal reflecting film formed on the surface of the plate-like body, and at least light generated inside the semiconductor layer A light-emitting diode element configured to be partially reflected by the metal reflection film and emitted to the outside of the plate-like body, and the surface of the plate-like body covered with the metal reflection film is uneven A light-emitting diode element having a surface, the outer surface of the metal reflective film being flattened to be a mirror surface.
(2) The light-emitting diode element according to (1), wherein the plate-like body includes a light-transmitting substrate, and a surface of the light-transmitting substrate forms at least a part of the uneven surface.
(3) The plate-like body includes a translucent electrode layer made of a transparent conductive film material, and the surface of the translucent electrode layer constitutes at least a part of the uneven surface. The light emitting diode element as described in.
(4) The light-emitting diode element according to (1), wherein a surface of the semiconductor layer constitutes at least a part of the uneven surface.
(5) The light-emitting diode element according to any one of (1) to (4), wherein the semiconductor layer is made of a group III nitride compound semiconductor.
(6) A translucent plate-like body including a semiconductor layer having a light-emitting element structure, and a metal reflective film formed on the surface of the plate-like body, and at least light generated inside the semiconductor layer A method of manufacturing a light-emitting diode element, a part of which is reflected by the metal reflecting film and emitted to the outside of the plate-like body, the step of preparing the plate-like body, and the metal A step of processing the surface of the plate-like body to be covered with a reflective film to form an uneven surface; a step of forming a metal film constituting the metal reflective film so as to cover the uneven surface; and an outer surface of the metal film Flattening by polishing to make a mirror surface.

According to the present invention, the element is fixed to the placement destination member by adhering the outer surface of the metal reflection film to the surface of the placement destination member, even though the metal reflection film has a concave and convex reflection surface. In doing so, it is possible to obtain a light-emitting diode element in which a space is hardly generated between the element and the mounting member.

(Embodiment 1)
FIG. 1 is a cross-sectional view illustrating the structure of an LED element according to Embodiment 1. The LED element 10 includes a translucent substrate 11A made of sapphire, a translucent semiconductor layer 11B made of a nitride semiconductor, and a translucent electrode layer 11C made of ITO, which are laminated in this order. A plate-like body 11 having the property is provided. The back surface of the translucent substrate 11 </ b> A, which is one main surface of the plate-like body 11, is an uneven surface and is covered with the metal reflective film 12. A buffer layer (not shown) is interposed between the translucent substrate 11A and the translucent semiconductor layer 11B. The translucent semiconductor layer 11B includes an n-type layer 11B-1 and a p-type layer 11B-2 that constitute a pn junction type light emitting element structure, and preferably an active layer is provided at the pn junction. . A negative electrode 13 is formed on the surface of the n-type layer 11B-1 partially exposed by etching. A positive electrode 14 is formed on a part of the upper surface of the translucent electrode layer 11C.

In the LED element 10 shown in FIG. 1, since the reflective surface of the metal reflective film 12 is an uneven surface, the light generated inside the translucent semiconductor layer 11B and transmitted through the translucent substrate 11A The light is reflected in various directions by the reflective film 12. Therefore, in addition to suppressing the multiple reflection inside the plate-like body 11, the light reflected by the metal reflecting film 12 is also emitted from the side of the translucent substrate 11A to the outside of the element, so that the light emission output of the element is Get higher.

Furthermore, the LED element 10 shown in FIG. 1 has a mirror surface by flattening the outer surface of the metal reflection film 12. Therefore, when the LED element 10 is fixed to the placement destination member and the LED lamp is manufactured, there is no space between the element 10 and the placement destination member. Therefore, the heat generated in the LED element 10 is efficiently dissipated through the placement member. In addition, since bubbles do not enter the adhesive used for bonding, the deterioration of the adhesive due to the pressure change in the bubbles does not occur, the reliability of the LED lamp decreases due to the deterioration of the adhesive, The problem of shortening the service life does not occur.

The LED element 10 shown in FIG. 1 can be manufactured as follows.
First, a known vapor phase epitaxial growth method such as an organic metal compound vapor phase growth (MOVPE) method, a hydride vapor phase growth (HVPE) method, or a molecular beam epitaxy (MBE) method is used on a light-transmitting substrate 11A made of sapphire. Then, a buffer layer (not shown) made of a nitride semiconductor, an n-type layer 11B-1 made of a nitride semiconductor, and a p-type layer 11B-2 made of a nitride semiconductor are sequentially grown and laminated to form a light-transmitting property. The semiconductor layer 11B is formed. The buffer layer is a low-temperature buffer layer made of, for example, GaN, AlGaN, AlN, or the like. Preferably, a single crystal high temperature buffer layer made of undoped GaN is stacked on the low temperature buffer layer. The n-type layer 11B-1 is, for example, a Si-doped GaN layer. For example, the p-type layer 11B-2 has a two-layer structure in which an Mg-doped AlGaN cladding layer and an Mg-doped GaN contact layer are stacked. For example, an active layer having a multiple quantum well structure including an InGaN well layer is provided at the junction between the n-type layer 11B-1 and the p-type layer 11B-2. An annealing process and an electron beam irradiation process for activating the p-type impurity added to the p-type layer 11B-2 can be appropriately performed.

After forming the translucent semiconductor layer 11, next, the translucent electrode layer 11C made of ITO is formed on the surface of the p-type layer 11B-2. As the formation method, CVD method (thermal CVD, plasma CVD, MOCVD, optical CVD), spray method, sputtering method, vacuum deposition method, cluster beam deposition method, pulse laser deposition method, ion plating method, sol-gel method, laser An ablation method and other methods for forming a known ITO thin film can be arbitrarily used. Between the p-type layer 11B-2 and the translucent electrode layer 11C made of ITO, a layer for reducing contact resistance, Au, Ni / A translucent metal thin film made of Au or the like may be interposed. The translucent electrode layer 11C is formed using a transparent conductive film material other than ITO, such as indium oxide, tin oxide, zinc oxide, IZO (indium zinc oxide), FTO (fluorine-doped tin oxide), and titanium nitride. You can also. After the formation of the translucent electrode layer 11C, the positive electrode 14 is formed on a part of the upper surface using Ti, Au, Al, Cu or the like. The positive electrode 14 is a bonding pad for wire bonding.

In the LED element 10, instead of the translucent electrode layer 11C, a translucent thin film metal electrode or an aperture metal electrode provided with an opening through which light generated inside the translucent semiconductor layer 11B can pass. Can also be formed. These electrodes are formed of a simple substance or an alloy such as Au, Ni, Co, or platinum group metals (Platinum Group Metals) at least at a portion in contact with the p-type layer so as to form an ohmic contact with the p-type layer 11B-2. To do.

After the positive electrode 14 is formed, the n-type layer 11B is then etched using a reactive ion etching method to a depth reaching the n-type layer 11B-1 from the surface side of the p-type layer 11B-2. -1 surface is partially exposed. Then, the negative electrode 13 is formed on the exposed surface of the n-type layer 11B-1. The negative electrode 13 is formed of a single substance or an alloy such as Al, Ti, W, Ni, Cr, and V at least at a portion in contact with the n-type layer so as to form an ohmic contact with the n-type layer 11B-1. Note that when a conductive substrate (semiconductor substrate) such as a SiC substrate, a GaN substrate, or a ZnO substrate is used as the translucent substrate instead of an insulating substrate such as a sapphire substrate, the negative electrode is the surface of the n-type layer. It is also possible to form it on the back surface of the light-transmitting substrate without forming it. After forming the negative electrode 13, it is preferable to form an insulating protective film on the surface of the element excluding the surface of the electrode.

After the negative electrode 13 is formed, the back surface of the translucent substrate 11A is processed to form an uneven surface. As one method, fine particles having a particle size of micron order or submicron order made of polymer, metal, etc. are deposited on the back surface of the light transmissive substrate, and this is used as a mask (random etching mask). The back surface is etched to form a recess. In another method, a photoresist film formed on the back surface of a light-transmitting substrate and an opening pattern formed on the photoresist film using a photolithography technique can be used as an etching mask. This method has the advantage that the machining area can be controlled. For example, on the back surface of the translucent substrate 11A, the region through which the dividing line passes when the wafer is divided into chips in a later step is left flat, and the other regions are processed to form an uneven surface. By not forming the metal reflection film 12 in the region through which the dividing line passes, the degree of freedom in selecting a method for dividing the wafer can be increased. There is no limitation on the etching method for forming the concave portion on the back surface of the light-transmitting substrate, and any of dry etching methods such as plasma etching and reactive ion etching and wet etching methods using an etching solution can be employed.

In order to process the back surface of the translucent substrate 11A to form an uneven surface, a mechanical processing method can be used as a method other than etching. For example, the back surface of the translucent substrate can be formed into an uneven surface by grinding or polishing using relatively coarse abrasive particles. Or the back surface of a translucent board | substrate can also be made into an uneven surface by the cutting process using a dicing blade etc. FIG.

In order to make the back surface of the translucent substrate 11A an uneven surface, not only the subtractive processing method as described above but also an additive processing method can be used. That is, it is a method of adding a protruding portion that becomes a protruding portion on the uneven surface on the back surface of the translucent substrate. The material of such a protrusion is not particularly limited as long as it has translucency, and is preferably formed of a translucent material having a small refractive index difference from the translucent substrate. For example, when the translucent substrate is a sapphire substrate, preferable materials for the protruding portion include aluminum oxide, spinel, ITO, and the like. As a method for forming the protrusion, a vapor deposition method such as vapor deposition, sputtering, or CVD is preferably exemplified. In the case of using a gas phase volume method capable of forming a film at a low temperature, the protruding portion can be formed in a desired pattern by a lift-off method using a photolithography technique.

The structure of the concavo-convex surface when the back surface of the translucent substrate 11A is an concavo-convex surface is not particularly limited, and is a structure composed of continuous convex portions and isolated concave portions (for example, hemispherical, circular in some places on a flat surface) Columnar, prismatic, conical, frustoconical, pyramidal, pyramidal, etc.), a structure consisting of continuous concave parts and isolated convex parts (for example, on flat surfaces, Hemispherical, cylindrical, prismatic, conical, frustoconical, pyramidal, pyramidal, etc.), ridge-shaped convex and groove-shaped concave (The triangular and trapezoidal shapes, and the like as the cross-sectional shape of the convex part and the concave part are included, and the convex part and the concave part are linearly extended or curvedly extended, Examples are those in which the convex part or the concave part has a branch, etc.), this There a mixed structure may be a variety of structures. The shape (upper surface shape, cross-sectional shape) and arrangement of the protrusions and recesses on the uneven surface may be regular or irregular. Preferably, when the side wall surface of the convex portion or the concave portion is an inclined surface having an inclination angle of 30 degrees to 60 degrees, when the light is reflected by the reflecting surface of the metal reflecting film formed on the uneven surface, Since the degree of change in the light propagation direction increases, the output improvement effect of the LED element increases.

The depth of the concave portion when the concave portion is formed by etching on the back surface of the translucent substrate 11A and the height of the convex portion when the convex portion is formed by the gas phase volume method are preferably the minimum value, preferably 0.8. It is set to 5 μm or more, more preferably 1 μm or more, and particularly preferably 5 μm or more. When the uneven surface is formed by mechanical processing, the surface roughness (arithmetic average roughness Ra) of the uneven surface is preferably 0.1 μm or more, and more preferably 0.2 μm or more. There is no particular upper limit to the height difference between the concave and convex portions on the concave and convex surfaces, but considering the time and energy required for processing the substrate, and the time and energy required to bury the concave and convex portions with the metal reflection film in the next step The maximum height difference is preferably 50 μm or less, and more preferably 25 μm or less.

After processing the back surface of the translucent substrate 11A to form an uneven surface, a metal reflection film 12 covering the uneven surface is formed. In order to form the metal reflection film 12, first, a metal film constituting the metal reflection film 12 is formed so as to cover the uneven surface and fill the concave portion of the uneven surface. As a method for forming the metal film in this manner, a vapor deposition method such as CVD, sputtering, or vapor deposition, or electrolytic plating that is a wet method can be given. If the concave / convex surface of the concave / convex surface is hole-shaped or groove-shaped and the ratio of the depth to the width of the opening is large, a seed layer is formed on the surface of the concave / convex surface by vapor deposition, and then the seed layer is formed by electrolytic plating. By depositing a plating layer thereon, the recess can be filled with metal. Next, the outer surface of the formed metal film is polished and flattened to have a mirror surface. The polishing is preferably CMP (Chemical Mechanical Polishing). The metal reflection film 12 may have an outer surface finished by polishing, or may be further mirror-finished on the surface of the polished metal film by a vapor deposition method or a wet method. A metal film deposited may be used. The surface roughness (arithmetic average roughness Ra) of the metal reflective film 12 as a mirror surface is preferably 0.02 μm or less, more preferably 0.01 μm or less.

The metal reflective film 12 is preferably formed of at least a portion functioning as a reflective surface (a portion in contact with the translucent substrate 11A) with Ag, Al, or Rh having good reflectivity. The metal reflection film 12 may have a laminated structure. For example, after sequentially depositing and laminating a reflective layer made of Ag, Al or Rh and a seed layer made of Cr, Pt, Ni, Ti, Au or the like by a vapor phase method on a portion in contact with the translucent substrate 11A, A plating layer made of Au, Ni, Cu, Ag or the like can be laminated on the seed layer by electrolytic plating. A solder layer or a eutectic alloy layer that can be used as an adhesive can also be formed on the outer surface portion of the metal reflective film 12. When the translucent substrate 11A is a conductive substrate (semiconductor substrate), the metal reflective film 12 can have a function as a negative electrode. In that case, at least a part of the metal reflective film in contact with the translucent substrate is formed of a metal that forms ohmic contact with the translucent substrate.

Finally, the LED elements formed on the wafer are separated into chips by using well-known methods in this field such as dicing, scribing, laser cutting, and the like. The LED element 10 also has an advantage that in this step, when the surface of the wafer on the metal reflective film 12 side is attached to a dicing tape, a chip obtained by dividing the wafer is not easily dropped from the dicing tape. On the other hand, in the conventional LED element 100 shown in FIG. 7, since the outer surface of the metal reflective film 120 is an uneven surface, the adhesion between this surface and the adhesive surface of the dicing tape is weak, There was a problem that the chips obtained by the division easily fall off from the dicing tape.

(Embodiment 2)
FIG. 2 is a cross-sectional view showing the structure of the LED element according to the second embodiment. This LED element 20 is formed by laminating a conductive translucent substrate 21A made of GaN, a translucent semiconductor layer 21B made of a nitride semiconductor, and a translucent electrode layer 21C made of ITO in this order. And a translucent plate-like body 21. A buffer layer (not shown) is preferably interposed between the translucent substrate 21A and the translucent semiconductor layer 21B. The translucent semiconductor layer 21B has an n-type layer 21B-1 and a p-type layer 21B-2 that constitute a pn junction type light emitting element structure, and preferably an active layer is provided at the pn junction. . The surface of the translucent electrode layer 21 </ b> C, which is one main surface of the plate-like body 21, is an uneven surface and is covered with a metal reflection film 22 that also serves as a positive electrode. The metal reflection film 22 is formed so as to fill the concave portion on the surface of the translucent electrode layer 21C having an uneven surface, and the outer surface thereof is flattened to be a mirror surface. A negative electrode 24 is formed on a part of the outer surface of the translucent substrate 21A. The LED element 21 is junction-down mounted with the surface of the metal reflection film 22 facing the surface of the mounting member.

(Embodiment 3)
FIG. 3 is a cross-sectional view illustrating the structure of the LED element according to the third embodiment. This LED element 30 is formed by laminating a conductive translucent substrate 31A made of GaN, a translucent semiconductor layer 31B made of a nitride semiconductor, and a translucent electrode layer 31C made of ITO in this order. And a translucent plate-like body 31. The translucent semiconductor layer 31B has an n-type layer 31B-1 and a p-type layer 31B-2 that constitute a pn junction type light emitting element structure, and preferably an active layer is provided at the pn junction. . The translucent electrode layer 31C is dispersed in the form of dots on the surface of the translucent semiconductor layer 31, and each dot has a truncated cone shape. Thereby, one main surface of the plate-like body 31 is an uneven surface constituted by the surface of the translucent semiconductor layer 31B and the surface of the translucent electrode layer 31C. A metal reflection film 32 that also serves as a positive electrode is formed so as to cover the uneven surface. The metal reflection film 32 is formed so as to fill the concave portion of the uneven surface, and the outer surface thereof is flattened to be a mirror surface. A negative electrode 34 is formed on a part of the outer surface of the translucent substrate 31A. The LED element 31 is junction-down mounted with the surface of the metal reflection film 32 facing the surface of the mounting member.

(Embodiment 4)
FIG. 4 is a cross-sectional view illustrating the structure of the LED device according to the fourth embodiment. The LED element 40 is formed by laminating a conductive translucent substrate 41A made of GaN, a translucent semiconductor layer 41B made of a nitride semiconductor, and a translucent electrode layer 41C made of ITO in this order. And a translucent plate-like body 41. The translucent semiconductor layer 41B has an n-type layer 41B-1 and a p-type layer 41B-2 that constitute a pn-junction light-emitting element structure, and preferably an active layer is provided at the pn junction. . An opening is formed in the translucent electrode layer 41C, and a recess having a V-shaped cross section is formed in the translucent semiconductor layer 41B by etching at the position of the opening. The recess has a depth reaching the n-type layer 41B-1. The recess may be hole-shaped (conical hole or pyramid hole) or groove-shaped (V-groove). The surface of the nitride semiconductor exposed in the recess is covered with a translucent insulating protective film (not shown). Examples of the material for the insulating protective film include silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, spinel, zirconium oxide, magnesium oxide, titanium oxide, magnesium fluoride, and lithium fluoride. Thus, one main surface of the plate-like body 41 is an uneven surface composed of the surface of the translucent insulating protective film and the surface of the translucent electrode layer 41C. A metal reflection film 42 that also serves as a positive electrode is formed so as to cover the uneven surface. The metal reflection film 42 is formed so as to fill the concave portion of the uneven surface, and the outer surface thereof is flattened to be a mirror surface. A negative electrode 44 is formed on a part of the outer surface of the translucent substrate 41A. The LED element 41 is mounted junction-down with the surface of the metal reflection film 42 facing the surface of the placement destination member.

In the fourth embodiment, the cross-sectional shape of the recess formed at the position of the opening of the translucent semiconductor layer 41C is an arbitrary shape such as a trapezoidal shape, a rectangular shape, a semicircular shape, a U shape, etc. in addition to a V shape. can do. The concave portion can be formed in a hole shape or a groove shape when any cross-sectional shape is adopted. In the fourth embodiment, the translucent electrode 41C can be replaced with a translucent or non-translucent electrode made of a metal film.

(Embodiment 5)
FIG. 5 is a cross-sectional view illustrating the structure of the LED element according to the fifth embodiment. The LED element 50 includes a light-transmitting semiconductor layer 51B made of a nitride semiconductor and a conductive light-transmitting substrate 51D made of ZnO bonded to the light-transmitting semiconductor layer 51B as a support substrate. A translucent plate-like body 51. The translucent semiconductor layer 51B has an n-type layer 51B-1 and a p-type layer 51B-2 that constitute a pn junction type light emitting element structure, and preferably an active layer is provided at the pn junction. . The surface of the translucent substrate 51 </ b> D, which is one main surface of the plate-like body 51, is an uneven surface and is covered with a metal reflection film 52 that also serves as a positive electrode. The metal reflection film 52 is formed so as to fill a concave portion on the surface of the translucent substrate 51D having an uneven surface, and the outer surface thereof is flattened to be a mirror surface. A negative electrode 54 is formed on a part of the outer surface of the n-type layer 51B-1.

To manufacture the LED element 50 shown in FIG. 5, first, an n-type layer 51B-1 and a p-type layer 51B-2 are sequentially vapor-deposited on a sapphire substrate via a buffer layer. Next, a translucent substrate 51D made of ZnO is bonded to the surface of the p-type layer 51B-2 by wafer bonding. For details of the joining method, Non-Patent Document 1 can be referred to. After the bonding, the surface of the translucent substrate 51D is processed to form an uneven surface, and a metal reflection film 52 that covers the uneven surface is formed. Further, the sapphire substrate and the buffer layer are removed using a method such as laser lift-off, polishing, and etching to expose the n-type layer 51B-1, and a negative electrode 54 is formed on the exposed surface of the n-type layer 51B-1. To do.

(Embodiment 6)
FIG. 6 is a cross-sectional view showing the structure of the LED element according to the sixth embodiment. The LED element 60 is bonded as a support substrate to the first conductive translucent substrate 61A made of GaN, the translucent semiconductor layer 61B made of a nitride semiconductor, and the translucent semiconductor layer 61B. , And a conductive second light-transmitting substrate 61D made of ZnO. The outer surface of the first translucent substrate 61A, which is one main surface of the plate-like body 61, is processed to be an uneven surface having a plurality of convex portions having a trapezoidal cross section. This convex part may be a frustum shape (conical frustum, truncated pyramid), or may be a ridge shape having a flat top surface. A negative electrode 64 is formed on the top surface of each convex portion. A buffer layer (not shown) is preferably interposed between the first translucent substrate 61A and the translucent semiconductor layer 61B. The translucent semiconductor layer 61B includes an n-type layer 61B-1 and a p-type layer 61B-2 that constitute a pn junction type light emitting element structure, and preferably an active layer is provided at the pn junction. . The surface of the second light-transmitting substrate 61D, which is the other main surface of the plate-like body 61, is an uneven surface and is covered with a metal reflection film 62 that also serves as a positive electrode. The metal reflection film 62 is formed so as to fill a concave portion on the surface of the translucent substrate 61D having an uneven surface, and the outer surface thereof is flattened to be a mirror surface.

In the sixth embodiment, the height of the convex portion (the height from the bottom of the concave portion to the top of the convex portion) formed on the surface of the first translucent substrate 61A is the first translucent substrate before processing. The thickness can be as large as 61A. Therefore, although the height of this convex part is based also on the thickness of the 1st translucent board | substrate 61A before a process, it can be 50 micrometers or more. As the height of the convex portion is increased, the probability that light is extracted from the side surface of the convex portion to the outside of the device is increased, and the light emission efficiency of the device is improved. The cross-sectional shape of the convex portion can be any shape such as a trapezoidal shape, a rectangular shape, a semicircular shape, and a triangular shape. By forming electrodes on the respective surfaces of the convex portions provided on the surface of the first light transmissive substrate 61A, current can be uniformly injected into the light transmissive semiconductor layer 61B. However, it is not essential to form the electrode in this way. For example, the electrode formed on the surface of the first translucent substrate 61A may be formed only on one surface of the plurality of convex portions. Or you may form in the surface of the recessed part of an uneven surface.

To manufacture the LED element 60 shown in FIG. 6, first, an n-type layer 61B-1 and a p-type layer 61B-2 are formed on a GaN substrate serving as the first light-transmissive substrate 61A via a buffer layer. The layers are sequentially grown by vapor phase growth. Next, a second translucent substrate 61D made of ZnO is bonded to the surface of the p-type layer 61B-2 by wafer bonding. For details of the joining method, Non-Patent Document 1 can be referred to. After the bonding, the surface of the second translucent substrate 61D is processed to form an uneven surface, and a metal reflective film 62 that covers the uneven surface is formed. Further, the surface of the first translucent substrate 61A is processed by etching or a mechanical method to form an uneven surface. And the negative electrode 64 is formed in the top face of the convex part of 61 A of 1st translucent board | substrates used as the uneven surface.

In the LED element 60 shown in FIG. 6, since the refractive index difference between the first transparent substrate 61A made of GaN and the transparent semiconductor layer 61B made of a nitride semiconductor is small (or there is no refractive index difference), Light traveling from the inside of the translucent semiconductor layer 61B toward the first translucent substrate 61A is hardly reflected at the interface between the translucent semiconductor layer 61B and the first translucent substrate 61A. . The same applies to the case where a substrate (for example, a SiC substrate) having a higher refractive index than the light-transmitting semiconductor layer 61B made of a nitride semiconductor is used as the first light-transmitting substrate 61A. On the other hand, since the second light-transmitting substrate 61D made of ZnO has a lower refractive index than the light-transmitting semiconductor layer 61B made of a nitride semiconductor, the light-transmitting semiconductor layer 61B and the second light-transmitting substrate 61D. The light incident from the side of the translucent semiconductor layer 61B with respect to the interface is reflected by the difference in refractive index at this interface. Therefore, in the LED element 60, the probability that light generated inside the translucent semiconductor layer 61B is extracted out of the element from the surface on the first translucent substrate 61A side is increased.

The present invention is not limited to the embodiment explicitly shown above, and various modifications can be made without departing from the spirit of the invention.

It is sectional drawing which shows the structure of the light emitting diode element which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the light emitting diode element which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the light emitting diode element which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the light emitting diode element which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the light emitting diode element which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the light emitting diode element which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the conventional light emitting diode element.

Explanation of symbols

10, 20, 30, 40, 50, 60 Light-emitting diode elements 11, 21, 31, 41, 51, 61 Translucent plates 11A, 21A, 31A, 41A, 51A, 61A Translucent substrates 11B, 21B , 31B, 41B, 51B, 61B Translucent semiconductor layer 11C, 21C, 31C, 41C Translucent electrode layer 51D, 61D Translucent substrate 12, 22, 32, 42, 52, 62 Metal reflective film 13 Negative electrode 14 24, 34, 44, 54, 64 Positive electrode

Claims (6)

A translucent plate-like body including a semiconductor layer having a light-emitting element structure, and a metal reflective film formed on the surface of the plate-like body,
A light-emitting diode element configured such that at least a part of light generated inside the semiconductor layer is reflected by the metal reflecting film and is emitted to the outside of the plate-like body;
The surface of the plate-like body covered with the metal reflective film is an uneven surface,
The outer surface of the metal reflective film is flattened to become a mirror surface,
Light emitting diode element. The light emitting diode element according to claim 1, wherein the plate-like body includes a translucent substrate, and a surface of the translucent substrate constitutes at least a part of the uneven surface. The light emission according to claim 1, wherein the plate-like body includes a translucent electrode layer made of a transparent conductive film material, and a surface of the translucent electrode layer constitutes at least a part of the uneven surface. Diode element. The light emitting diode element according to claim 1, wherein a surface of the semiconductor layer constitutes at least a part of the uneven surface. The light emitting diode element in any one of Claims 1-4 with which the said semiconductor layer consists of a group 3 nitride type compound semiconductor. A translucent plate-like body including a semiconductor layer having a light-emitting element structure, and a metal reflective film formed on the surface of the plate-like body,
A method for manufacturing a light-emitting diode element, wherein at least part of light generated inside the semiconductor layer is reflected by the metal reflecting film and is emitted to the outside of the plate-like body,
Preparing the plate-like body;
Processing the surface of the plate-like body to be covered with the metal reflective film to form an uneven surface;
Forming a metal film constituting the metal reflective film so as to cover the uneven surface;
Flattening the outer surface of the metal film by polishing to a mirror surface;
A manufacturing method comprising:

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