JP4992311B2 - Light emitting diode mounting substrate, light emitting diode backlight, light emitting diode illumination device, light emitting diode display, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting mounting board which can be intended to maximize an extraction efficiency of a light. <P>SOLUTION: An end 14 inclining to a lower face of an n-type GaN layer 11 is formed in the n-type GaN layer 11, an active layer 12, and a p-type GaN layer 13 which form a GaN based light emitting diode 1. A p-side electrode 15 is formed on the p-type GaN layer 13. A transparent resin 16 is formed so as to cover an upper face of the p-type GaN layer 13 in a portion around the end 14 and the p-side electrode 15, and a reflective film 17 is formed so as to coat the entire of the transparent resin 16 and the p-side electrode 15. An n side electrode 18 is formed on the lower face of the n-type GaN layer 11. The side of the n-type GaN layer 11 of this GaN based light emitting diode 1 is mounted on a transparent substrate 2 through a transparent medium layer of a low refractive index 3 such as an air gap or the like. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a light emitting diode mounting substrate, a light emitting diode backlight, a light emitting diode illumination device, a light emitting diode display, and an electronic apparatus.

  Conventionally, a GaN-based light emitting diode as shown in FIG. 18 is known. As shown in FIG. 18, in this GaN-based light emitting diode, an n-type GaN layer 102, an active layer 103, and a p-type GaN layer 104 are sequentially stacked on a sapphire substrate 101 to form a light emitting diode structure. In this case, the upper layer portion of the n-type GaN layer 102, the active layer 103, and the p-type GaN layer 104 are patterned into a columnar shape having an end surface perpendicular to the substrate surface by etching. A p-side electrode 105 is formed on the p-type GaN layer 104, and an n-side electrode 106 is formed on the n-type GaN layer 102 outside the columnar portion. In this GaN-based light emitting diode, light generated from the active layer 103 during operation repeats total reflection inside the columnar portion, and finally passes through the sapphire substrate 101 and is extracted outside.

In a semiconductor light-emitting diode having a conductive substrate, a semiconductor light-emitting layer epitaxially grown thereon, and a metal electrode provided on the semiconductor light-emitting layer on the opposite side of the conductive substrate, light generated from the semiconductor light-emitting layer Has been proposed to arrange the metal electrode so that the light reflected by the metal electrode is directed to the outside, for example, the metal electrode surface is inclined 45 degrees with respect to the semiconductor light emitting layer. (See, for example, Patent Document 1), a light emitting diode having a reflector outside the end face of a semiconductor layer forming a light emitting diode structure is mounted on a transparent substrate through an air gap or a layer made of a low refractive index material. There is no disclosure or suggestion about this.
JP 2002-50792 A

In the conventional GaN-based light emitting diode shown in FIG. 18 described above, since the end face of the columnar portion composed of the n-type GaN layer 102, the active layer 103, and the p-type GaN layer 104 is vertical, it is generated from the active layer 103 during operation. The light to be emitted repeats total reflection inside the columnar portion, and as a result, the light is absorbed, so that the light extraction efficiency is low. Furthermore, this GaN-based light emitting diode has a drawback that the diameter of the columnar portion composed of the n-type GaN layer 102, the active layer 103 and the p-type GaN layer 104 is generally as large as about 300 μm, and the size is large.
On the other hand, in a light emitting diode backlight, a light emitting diode display, and the like, it is general to use a light emitting diode mounting substrate on which a plurality of minute light emitting diodes are mounted on a transparent substrate, and to extract light to the outside through the transparent substrate.

Therefore, the problem to be solved by the present invention is to use a light emitting diode that can greatly improve the light extraction efficiency and can be easily miniaturized, and to mount this light emitting diode on a transparent substrate. It is an object of the present invention to provide a light emitting diode mounting substrate capable of optimizing the structure and maximizing extraction efficiency when light from the light emitting diode is extracted outside through a transparent substrate.
Another problem to be solved by the present invention is to provide a light emitting diode backlight, a light emitting diode illuminating device, a light emitting diode display, and an electronic device using the high performance light emitting diode mounting substrate as described above.

The inventors of the present invention have intensively studied to solve the above-described problems of the prior art. The outline will be described as follows.
The present inventors considered a GaN-based light emitting diode as shown in FIG. 19 having a structure suitable for miniaturization and capable of securing a certain degree of light extraction efficiency, and studied this. As shown in FIG. 19, in this GaN-based light emitting diode, the n-type GaN layer 201, the active layer 202, and the p-type GaN layer 203 forming the light emitting diode structure are dry-etched, so that the main surfaces of these layers are formed. For example, an end face 204 inclined by about 45 degrees is formed, and a p-side electrode 205 is formed on the upper surface of the p-type GaN layer 203 and an n-side electrode 206 is formed on the lower surface of the n-type GaN layer 201, for example, indium-tin oxide (ITO). A transparent electrode made of, etc. is formed. In this case, light extraction efficiency is improved by totally reflecting the light generated from the active layer 202 by the end face 204 and directing it toward the lower surface of the n-type GaN layer 201, that is, the emission surface.

  However, as a result of investigation, in this GaN-based light emitting diode, a lot of light actually leaked from the end face 204, and particularly when this GaN-based light emitting diode was sealed with resin, it was generated from the active layer 202. There was a problem that about 60% of the light propagated through the resin, resulting in a loss. For this reason, even if the reflectance of the p-side electrode 205 is increased and the inclination angle of the end face 204 is optimized, the light extraction efficiency is only about 20%. FIG. 20 shows an example of the ratio of the amount of light in each direction. FIG. 20 schematically shows the above-described GaN-based light emitting diode sealed with resin.

  Therefore, as a result of further examination, a reflector (external mirror) is provided outside the end face 204 to direct the light emitted from the end face 204 toward the light extraction surface (or to be turned back to the light extraction surface). Focusing on the fact that this is effective, a detailed study was conducted based on this, and the light extraction efficiency was greatly improved. In this case, the n-side electrode 206 is not limited to a transparent electrode, and a metal electrode capable of making a better ohmic contact with the n-type GaN layer 201 can be used. It may be formed only partially.

  On the other hand, the semiconductor layer forming the light emitting diode structure as described above has an end face inclined with respect to its main surface, and the light emitting diode having a reflector outside the end face is used as the light extraction surface of this semiconductor layer. If the semiconductor layer side is directly fixed on the transparent substrate, the difference between the refractive index of the semiconductor layer and the refractive index of the transparent substrate is small, and the thickness of the transparent substrate is If it is large, the light from the light-emitting diode is likely to pass directly to the transparent substrate, and thus the light entering the transparent substrate is guided through the transparent substrate, so that the effect of the above reflector is sufficiently exhibited. I can't. This is shown in FIG. In FIG. 21, reference numeral 301 is a transparent substrate, 302 is a light emitting diode, 303 is a semiconductor layer forming a light emitting diode structure, 304 is a p-side electrode, 305 is a reflector, 306 is a transparent resin, and 307 is a sealing resin. Show. In FIG. 21, the illustration of the n-side electrode is omitted. Therefore, as a result of intensive studies to make it possible to fully exhibit the effect of the reflector, the semiconductor layer 303 side is not directly fixed on the transparent substrate 301 but is transparent to the semiconductor layer 303. A layer made of a medium having a refractive index smaller than that of the semiconductor layer 303 and the transparent substrate 301 between the substrate 301, for example, an air gap or a layer made of a material having a refractive index smaller than that of the semiconductor layer 303 and the transparent substrate 301. It came to the conclusion that it is effective to pinch, and came to devise this invention.

That is, in order to solve the above problem, the first invention of the present invention is:
The semiconductor layer forming the light emitting diode structure has an end face inclined with respect to the main surface, and at least one light emitting diode having a reflector outside the end face is formed on the transparent substrate with the light of the semiconductor layer. A light-emitting diode mounting substrate, which is mounted through a layer made of a transparent medium having a refractive index lower than that of the semiconductor layer and the transparent substrate with a take-out surface facing the transparent substrate.

At least one light emitting diode of the light emitting diode mounting substrate is preferably a light emitting diode having a semiconductor layer forming a light emitting diode structure having an end surface inclined at an angle θ _{1 with} respect to the main surface. A reflector that includes at least a portion that is opposed to the end face and is inclined at an angle θ ₂ smaller than the angle θ _{1 with} respect to the main surface.

The layer made of a transparent medium having a refractive index lower than that of the semiconductor layer and the transparent substrate is, for example, an air gap (air layer), a layer made of a transparent material having a refractive index lower than that of the semiconductor layer and the transparent substrate, or an air gap. And a layer composed of a transparent material having a refractive index lower than that of the semiconductor layer and the transparent substrate. As a material used for a layer made of a transparent material having a refractive index lower than that of the semiconductor layer and the transparent substrate, basically any material may be used as long as it is transparent to light having an emission wavelength. Specifically, for example, a transparent resin, especially a transparent fluororesin can be used.
As a material for the transparent substrate, basically any material may be used as long as it is transparent to light of the emission wavelength. Specifically, for example, glass, quartz glass, sapphire, plastic, etc. Can be used.

The semiconductor layer forming the light emitting diode structure generally includes a first semiconductor layer of a first conductivity type, an active layer, and a second semiconductor layer of a second conductivity type. The planar shape of the semiconductor layer is typically a circle, but if necessary, other shapes such as an ellipse or the like may be formed by regularly or irregularly deforming all or part of the circle. Further, it may be an n-gon (n is an integer of 3 or more) or a shape obtained by regularly or irregularly deforming all or part of this n-gon. The cross-sectional shape of the semiconductor layer is typically a trapezoid, a rectangle, or an inverted trapezoid, but may be a shape obtained by deforming this. In addition, the inclination angle θ ₁ of the end face of the semiconductor layer is typically constant, but it is not always necessary, and may be changed within the end face.

From the viewpoint of improving the light extraction efficiency, a transparent resin having a refractive index lower than the refractive index of the semiconductor layer (higher than the refractive index of air) is preferably formed between the end face of the semiconductor layer and the reflector. Various materials can be used as the transparent resin, and the material is selected as necessary. Similarly, the thickness of the semiconductor layer is preferably 0.3 μm or more and 10 μm or less, and the ratio of the thickness of the semiconductor layer to the maximum diameter of the semiconductor layer is 0.001 or more and 2 or less. The maximum diameter of the semiconductor layer can be determined as necessary, but is generally 50 μm or less, typically 30 μm or less, and more typically 25 μm or less. Preferably, when the semiconductor layer has the first electrode and the second electrode on the light extraction surface and the surface opposite to the light extraction surface, respectively, the reflector is brought into ohmic contact with the second electrode. A part of the second electrode or a part of the wiring of the second electrode is also used. Preferably, the reflector has a direction perpendicular to the end face when at least 30 degrees ≦ θ ₁ ≦ 90 degrees, and a direction perpendicular to the end face when 90 degrees <θ ₁ ≦ 150 degrees. Is formed so as to include a region projected on the surface on which the reflector is formed in a direction folded at the light extraction surface of the semiconductor layer. Preferably, the reflector is formed to extend on the surface of the semiconductor layer opposite to the light extraction surface. Preferably, when the refractive index of the transparent resin is n ₂ and the refractive index of a medium (for example, air) outside the transparent resin is n ₃ , 30 degrees ≦ θ ₁ ≦ 150 degrees and 30 degrees ≦ when theta ₁ ≦ 90 ° ^{_{θ 2 ≧ (θ 1 -sin -1}} (n 3 / n 2)) / 2 cutlet θ ₂ ≦ θ ₁ / 2,90 degrees <theta ₁ ≦ 0.99 degree when theta ₂ ≧ ((Θ ₁ −90) −sin ⁻¹ (n ₃ / n ₂ )) / 2 and θ ₂ ≦ (θ ₁ −90) / 2. In addition to the case where the reflecting surface facing the end surface of the semiconductor layer is a flat surface, the reflecting surface may have a curved surface. Preferably, the semiconductor layer has a first electrode and a second electrode on a light extraction surface and a surface opposite to the light extraction surface, respectively, and the first electrode has the end surface facing the light of the semiconductor layer. It is formed avoiding the area projected in the direction perpendicular to the extraction surface.

  The transparent resin can be formed by various methods. Specifically, this transparent resin is formed by, for example, a spin coating method, formed by curing and shrinking a resin formed so as to cover at least the end face, or by a photolithography technique using a photosensitive resin. Formed, formed by press molding of resin using a mold, formed by thermal imprinting, formed by ultraviolet (UV) imprint molding, or pressed in an elastically deformable release layer It can be formed by curing.

As a material of the semiconductor layer forming the light emitting diode structure, specifically, the first semiconductor layer, the active layer, and the second semiconductor layer, basically any semiconductor may be used, an inorganic semiconductor, Although it may be any of organic semiconductors, for example, a semiconductor having a wurtzite crystal structure or a cubic structure can be used. Semiconductors having a wurtzite crystal structure include nitride III-V compound semiconductors, II-VI group compound semiconductors such as BeMgZnCdS compound semiconductors and BeMgZnCdO compound semiconductors, and oxides such as ZnO. A semiconductor etc. are mentioned. Nitride III-V compound semiconductor is most _{generally, Al X B y Ga 1-} xyz In z As u N 1-uv P v ( however, 0 ≦ x ≦ 1,0 ≦ y ≦ 1, 0 ≦ z ≦ 1,0 ≦ u ≦ 1,0 ≦ v ≦ 1,0 ≦ x + y + z <1,0 ≦ u + v consists <1), more _{specifically, Al X B y Ga 1-} xyz in z N (However, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, 0 ≦ x + y + z <1), typically Al _X Ga _1-xz In _z N (where 0 ≦ x ≦ 1, 0 ≦ z ≦ 1). Specific examples of the nitride III-V compound semiconductor include GaN, InN, AlN, AlGaN, InGaN, and AlGaInN. Examples of the semiconductor having a cubic structure include an AlGaInP semiconductor and an AlGaAs semiconductor. The first conductivity type may be n-type or p-type, and the second conductivity type is p-type or n-type accordingly.

As a growth method of the first semiconductor layer, the active layer, and the second semiconductor layer, for example, metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxial growth or halide vapor phase epitaxial growth (HVPE), molecular beam epitaxy (MBE) However, the present invention is not limited to this. The substrate used for this growth is basically made of any material as long as the first semiconductor layer, the active layer, and the second semiconductor layer can be grown with good crystallinity. May be. Specifically, for example, when the first semiconductor layer, the active layer, and the second semiconductor layer are made of a nitride-based III-V group compound semiconductor, sapphire (Al ₂ O ₃ ) (C plane, A plane, Including R-plane and the like, and planes off from these planes), SiC (including 6H, 4H, 3C), nitride III-V compound semiconductors (GaN, InAlGaN, AlN, etc.), Si, A substrate made of ZnS, ZnO, LiMgO, GaAs, MgAl ₂ O ₄ or the like can be used. Further, when the first semiconductor layer, the active layer, and the second semiconductor layer are made of, for example, an AlGaInP semiconductor or an AlGaAs semiconductor, a GaAs substrate can be typically used.

  The use of the light-emitting diode mounting substrate is not limited, but can be used for, for example, a light-emitting diode backlight, a light-emitting diode illumination device, a light-emitting diode display, and an electronic device as described below.

The second invention is
In a light emitting diode backlight having a light emitting diode mounting substrate in which a plurality of red light emitting diodes, green light emitting diodes and blue light emitting diodes are respectively mounted on a transparent substrate,
At least one of the red light emitting diode, the green light emitting diode, and the blue light emitting diode has an end surface on which a semiconductor layer forming a light emitting diode structure is inclined with respect to a main surface thereof A light emitting diode having a reflector outside the end surface, and the light emitting diode is disposed on the transparent substrate with the light extraction surface of the semiconductor layer facing the transparent substrate. It is mounted via a layer made of a transparent medium having a refractive index lower than that of the transparent substrate.

The third invention is
In a light emitting diode lighting device having a light emitting diode mounting substrate in which a plurality of red light emitting diodes, green light emitting diodes and blue light emitting diodes are mounted on a transparent substrate, respectively.
At least one of the red light emitting diode, the green light emitting diode, and the blue light emitting diode has an end surface on which a semiconductor layer forming a light emitting diode structure is inclined with respect to a main surface thereof A light emitting diode having a reflector outside the end surface, and the light emitting diode is disposed on the transparent substrate with the light extraction surface of the semiconductor layer facing the transparent substrate. It is mounted via a layer made of a transparent medium having a refractive index lower than that of the transparent substrate.

The fourth invention is:
In a light emitting diode display having a light emitting diode mounting substrate in which a plurality of red light emitting diodes, green light emitting diodes and blue light emitting diodes are respectively mounted on a transparent substrate,
At least one of the red light emitting diode, the green light emitting diode, and the blue light emitting diode has an end surface on which a semiconductor layer forming a light emitting diode structure is inclined with respect to a main surface thereof A light emitting diode having a reflector outside the end surface, and the light emitting diode is disposed on the transparent substrate with the light extraction surface of the semiconductor layer facing the transparent substrate. It is mounted via a layer made of a transparent medium having a refractive index lower than that of the transparent substrate.

  In the second to fourth inventions, as the red light emitting diode, the green light emitting diode, and the blue light emitting diode, for example, a light emitting diode using a nitride III-V compound semiconductor can be used. . As the red light emitting diode, for example, a diode using an AlGaInP-based semiconductor can be used.

The fifth invention is:
In an electronic device having a light emitting diode mounting substrate in which one or a plurality of light emitting diodes are mounted on a transparent substrate,
At least one of the light emitting diodes is a light emitting diode in which a semiconductor layer forming a light emitting diode structure has an end surface inclined with respect to the main surface, and a reflector is provided outside the end surface. The semiconductor layer is mounted on the transparent substrate with a light extraction surface of the semiconductor layer facing the transparent substrate side through a layer made of a transparent medium having a refractive index lower than that of the semiconductor layer and the transparent substrate. It is characterized by.

This electronic device may be basically any device as long as it has at least one light emitting diode for the purpose of backlighting, display, illumination and other purposes of a liquid crystal display. Specific examples include mobile phones, mobile devices, robots, personal computers, in-vehicle devices, and various household electrical appliances.
In the second to fifth inventions, what has been described in relation to the first invention holds true for matters other than those described above, unless they are contrary to the nature thereof.

  In the present invention configured as described above, the semiconductor layer forming the light emitting diode structure has an end face inclined with respect to the main surface, and the light emitting diode having a reflector outside the end face is a transparent substrate. Since these semiconductor layers and a layer made of a transparent medium having a refractive index lower than that of the transparent substrate are mounted on the semiconductor layer, the refractive index of the semiconductor layer with respect to the refractive index of the semiconductor layer forming the light emitting diode structure The refractive index of the outer medium becomes smaller, and the critical angle for light traveling from the semiconductor layer toward the light extraction surface becomes smaller. For this reason, a transparent substrate is produced as a result that more light out of the light generated in the semiconductor layer (active layer or light emitting layer) during operation and traveling toward the light extraction surface of the semiconductor layer is totally reflected by the light extraction surface. The light exiting to the side is greatly reduced. The light totally reflected by the light extraction surface is emitted from the end surface of the semiconductor layer, reflected by the reflector provided outside the end surface to the light extraction surface side, and from the refractive index of the semiconductor layer and the transparent substrate. The light enters the transparent substrate through a layer made of a transparent medium having a small refractive index, passes through the transparent substrate, and is finally taken out. Thus, the effect of the reflector provided outside the end face of the semiconductor layer can be sufficiently exerted, and the proportion of light that can be finally extracted outside can be increased.

  According to the present invention, the light extraction efficiency of the light emitting diode can be greatly improved, and the extraction efficiency when the light from the light emitting diode is extracted to the outside through the transparent substrate can be maximized. It is possible to obtain a light emitting diode mounting substrate with extremely high light extraction efficiency. A high-performance light-emitting diode backlight, a light-emitting diode illuminating device, a light-emitting diode display, various electronic devices, and the like can be realized using the light-emitting diode mounting substrate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the embodiments, the same or corresponding parts are denoted by the same reference numerals.
First, a first embodiment of the present invention will be described.
FIG. 1 shows a light emitting diode mounting substrate according to the first embodiment, and FIG. 2 shows a GaN light emitting diode mounted on the light emitting diode mounting substrate.
As shown in FIG. 1, in this light-emitting diode mounting substrate, a plurality of GaN-based light-emitting diodes 1 have a light extraction surface of a semiconductor layer forming a light-emitting diode structure facing the transparent substrate 2 on the transparent substrate 2. The semiconductor layer and the transparent substrate 2 are mounted via a low refractive index transparent medium layer 3 having a refractive index lower than that of the transparent substrate 2. These GaN-based light emitting diodes 1 are sealed with a resin 4. Further, necessary electrodes are applied to the electrodes of the GaN-based light emitting diode 1 by a conventionally known method, if necessary. The GaN-based light emitting diode 1 is sealed with a resin 4. As the transparent substrate 2, for example, a glass substrate, a quartz glass substrate, a plastic substrate, or the like is used. The refractive index of the low refractive index transparent medium layer 3 is preferably 0.2 or more, more preferably 0.3 or more, and even more preferably 0 than the refractive index of the semiconductor layer forming the light emitting diode structure and the transparent substrate 2. .Lower by 4 or more. As this low refractive index transparent medium layer 3, an air gap (refractive index is about 1), a low refractive index transparent material layer, or a laminated structure thereof can be used. As a material of the low refractive index transparent material layer, for example, a transparent fluororesin is used. The thickness of the transparent substrate 2 and the low refractive index transparent medium layer 3 is selected according to need and is not particularly limited. The thickness of the transparent substrate 2 is, for example, 100 to 500 μm, and the thickness of the low refractive index transparent medium layer 3 is Is, for example, 1 to 10 μm. When an air gap is used as the low refractive index transparent medium layer 3, for example, a spacer (not shown) is provided with a predetermined shape, size and arrangement between the transparent substrate 2 and the GaN-based light emitting diode 1, The spacer defines the thickness of the air gap, but is not limited to this.

As shown in FIG. 2, the GaN-based light emitting diode 1 has a light emitting diode structure composed of an n-type GaN layer 11, an active layer 12 thereon, and a p-type GaN layer 13 thereon. The n-type GaN layer 11, the active layer 12 and the p-type GaN layer 13 as a whole have, for example, a circular planar shape, and an end face (side face) 14 is inclined at an angle θ _{1 with} respect to the lower face of the n-type GaN layer 11. is doing. These n-type GaN layer 11, active layer 12 and p-type GaN layer 13 have a trapezoidal shape (θ ₁ <90 °), a rectangular shape (θ ₁ = 90 °), or an inverted trapezoidal shape (θ ₁ > 90 °). For example, a circular p-side electrode 15 is formed on the p-type GaN layer 13. A transparent resin 16 is formed so as to cover the upper surface of the p-type GaN layer 13 around the end face 14 and the p-side electrode 15. A reflective film 17 is formed so as to cover the transparent resin 16 and the entire p-side electrode 15. On the lower surface of the n-type GaN layer 11, for example, a circular n-side electrode 18 is formed.

The structure of the GaN-based light emitting diode 1 is optimized as follows in order to maximize the light extraction efficiency.
(1) The inclined surface 16 a of the transparent resin 16 is inclined at an angle θ _{2 with} respect to the lower surface of the n-type GaN layer 11, and thus the reflective film 17 is also inclined at an angle θ _{2 with} respect to the lower surface of the n-type GaN layer 11. . Here, θ ₂ <θ ₁ . As a result, the light generated from the active layer 12 and emitted from the end face 14 is reflected by the reflective film 17 and travels downward to be easily extracted outside.
(2) when n-type GaN layer 11, an average refractive index of the entire active layer 12 and the p-type GaN layer 13 was set to n _1, the refractive index n ₂ is the refractive index of air of the transparent resin 16 <n ₂ <n ₁ It has become. As a result, light generated from the active layer 12 and incident on the end face 14 is more easily emitted from the end face 14 than when the medium outside the end face 14 is air, and is finally extracted to the outside. It becomes easy to be.
(3) When the maximum diameter of the light-emitting diode structure, that is, the diameter of the lower surface of the n-type GaN layer 11 is a and the total thickness (height) is b, the aspect ratio b / a is 0.001-2, b Is in the range of 0.3 to 10 μm.
(4) As the material of the reflective film 17, a material having as high a reflectance as possible with respect to light of the emission wavelength, for example, Ag or a metal containing Ag as a main component is used. As a result, the light emitted to the outside from the end face 14 and the upper surface of the p-type GaN layer 13 can be efficiently reflected by the reflective film 17 and finally easily extracted to the outside. The reflective film 17 is in ohmic contact with the p-side electrode 15 and also serves as a part of the p-side electrode 15 or a part of the wiring connected to the p-side electrode 15. Thereby, the resistance of the p-side electrode 15 can be reduced, and the operating voltage can be reduced.
(5) As shown in FIG. 3, the reflection film 17 has the end face 14 in the direction perpendicular to the angle when 30 degrees ≦ θ ₁ ≦ 90 degrees, and the end face 14 when the angle is 90 degrees <θ ₁ ≦ 150 degrees. It is formed so as to include at least a region projected on the inclined surface 16 a of the transparent resin 16 in a direction in which the vertical direction is turned back at the light extraction surface, that is, the lower surface of the n-type GaN layer 11. As a result, most of the light generated from the active layer 12 and emitted from the end face 14 is reflected by the reflective film 17 and travels downward to be easily extracted to the outside.
(6) The reflective film 17 is formed not only on the transparent resin 16 on the end face 14 but also on the transparent resin 16 and the p-side electrode 15 on the upper surface of the p-type GaN layer 13. As a result, not only the light emitted from the active layer 12 and emitted from the end face 14 but also the light emitted from the upper surface of the p-type GaN layer 13 is reflected by the reflective film 17 and travels downward to be easily extracted outside. Become.
(7) When θ ₁ and θ ₂ are 30 degrees ≦ θ ₁ ≦ 150 degrees and 30 degrees ≦ θ ₁ ≦ 90 degrees, θ ₂ ≧ (θ ₁ −sin ⁻¹ (n ₃ / n ₂ )) / 2 And when θ ₂ ≦ θ _1/2 and 90 degrees <θ ₁ ≦ 150 degrees, θ ₂ ≧ ((θ ₁ −90) −sin ⁻¹ (n ₃ / n ₂ )) / 2 and θ ₂ ≦ (θ ₁ -90) / 2. Here, n ₃ is the refractive index of an external medium in contact with the lower surface of the transparent resin 16. When θ ₁ > 90 degrees, the light totally reflected by the light extraction surface is incident on the reflection film 17. As shown in FIG. 4, the above θ ₂ ≧ (θ ₁ −sin ⁻¹ (n ₃ / n ₂ )) / 2 or θ ₂ ≧ ((θ ₁ −90) −sin ⁻¹ (n ₃ / n _2). )) / 2 is a condition in which light emitted from the end face 14 in a direction perpendicular thereto is not totally reflected at the interface between the transparent resin 16 and the external medium. Further, θ ₂ ≦ θ _1/2 or _{θ 2 ≦ (θ 1 -90)} / 2 is the condition where light is not incident from the transparent resin 16 side to the end face 14.
(8) The n-side electrode 18 is formed in a region obtained by projecting the upper surface of the p-type GaN layer 13 onto the lower surface of the n-type GaN layer 11 in a direction perpendicular thereto. As a result, the following advantages can be obtained. That is, in this GaN-based light emitting diode 1, most of the light generated from the active layer 12, reflected by the end face 14 and directed downward, and extracted outside is projected onto the lower surface of the n-type GaN layer 11. Is concentrated in the area. When the n-side electrode 18 is formed in this region, the light extracted to the outside is blocked by the n-side electrode 18 and a light amount is lost. Therefore, the n-side electrode 18 avoids this region, in other words, p Preferably, the upper surface of the type GaN layer 13 is formed in a region projected onto the lower surface of the n-type GaN layer 11 in a direction perpendicular to the upper surface. You may form all.

Specific examples of the dimensions and materials of the respective parts of the GaN-based light emitting diode 1 are as follows. The thickness of the n-type GaN layer 11 is, for example, 2600 nm, the thickness of the active layer 12 is, for example, 200 nm, and the thickness of the p-type GaN layer 13 is, for example, 200 nm. The active layer 12 has, for example, a multiple quantum well (MQW) structure composed of an InGaN well layer and a GaN barrier layer, and the In composition of the InGaN well layer is, for example, 0 when the GaN-based light emitting diode emits blue light. .17, for example, 0.25 for green light emission. The maximum diameter a of the light emitting diode structure is, for example, 20 μm. As described above, when the thickness of the n-type GaN layer 11 is 2600 nm and the thicknesses of the active layer 12 and the p-type GaN layer 13 are 200 nm, the total thickness of the light emitting diode structure is 2600 + 200 + 200 = 3000 nm = 3 μm. is there. In this case, the aspect ratio of the light emitting diode structure is b / a = 3/20 = 0.15. θ ₁ is, for example, 50 degrees. The refractive index n ₂ of the transparent resin 16 is, for example, 1.6, for example, the transparent resin 16 is applied by a spin coating method, the thickness at the time of application is equivalent to 1 μm at a flat portion, and the thickness is reduced to 70% by curing shrinkage. When it decreases, θ ₂ is, for example, 20 degrees. The p-side electrode 15 is made of, for example, a metal multilayer film having an Ag / Pt / Au structure. The thickness of the Ag film is, for example, 50 nm, the thickness of the Pt film is, for example, 50 nm, and the thickness of the Au film is, for example, 2000 nm. The p-side electrode 15 may be composed of a single layer film of Ag or a single layer film of Ni. The reflection film 17 is made of, for example, a metal multilayer film having an Ag / Au structure, and the thicknesses of the Ag film and the Au film are each 50 nm, for example. The reflective film 17 may be made of a single layer film of Ag. The n-side electrode 18 is made of, for example, a Ti / Pt / Au laminated metal film, and the thickness of the Ti film and the Pt film is, for example, 50 nm, and the thickness of the Au film is, for example, 2000 nm.

  As shown in FIG. 1, in this light emitting diode mounting substrate, light generated from the active layer 12 during operation of the GaN-based light emitting diode 1 and directed directly to the lower surface of the n-type GaN layer 11 or generated from the active layer 12 Light that is reflected by the side electrode 15 or the like and then travels toward the lower surface of the n-type GaN layer 11 is reflected by this lower surface, and then exits from the end surface 14 and is reflected by the reflective film 17 toward the light extraction surface side. The light enters the transparent substrate 2 through the medium layer 3, passes through the transparent substrate 2, and is finally taken out. In this case, in addition to the fact that the light extraction efficiency of the GaN-based light-emitting diode 1 is extremely high because each part of the GaN-based light-emitting diode 1 is optimized from the viewpoint of maximizing the light extraction efficiency as described above, Of the light generated from the active layer 12 of the GaN-based light-emitting diode 1 and traveling toward the lower surface of the n-type GaN layer 11, the light that escapes to the transparent substrate 2 side is greatly reduced, so that the light finally passes from the transparent substrate 2 to the outside. The amount of light that can be extracted is extremely large.

Next, a method for manufacturing the GaN-based light emitting diode 1 will be described.
As shown in FIG. 5A, first, for example, a sapphire substrate 19 having a main surface of C + surface and a thickness of 430 μm is prepared, and the surface is cleaned by performing thermal cleaning or the like. For example, by using a metal organic chemical vapor deposition (MOCVD) method, first, for example, a GaN buffer layer 20 having a thickness of, for example, 1000 nm is grown at a low temperature of about 500 ° C., and then heated to about 1000 ° C. for crystallization. An n-type GaN layer 11 doped with, for example, Si as an n-type impurity, an active layer 12 and a p-type GaN layer 13 doped with, for example, Mg as a p-type impurity are sequentially grown thereon. Here, the n-type GaN layer 11 is grown at a temperature of about 1000 ° C., the active layer 12 is grown at a temperature of about 750 ° C., and the p-type GaN layer 13 is grown at a temperature of about 900 ° C., for example. The n-type GaN layer 11 is grown in, for example, a hydrogen gas atmosphere, the active layer 12 is grown in, for example, a nitrogen gas atmosphere, and the p-type GaN layer 13 is grown in, for example, a hydrogen gas atmosphere.

For example, trimethylgallium ((CH ₃ ) ₃ Ga, TMG) is used as a raw material for Ga, and trimethylaluminum ((CH ₃ ) ₃ Al, TMA) is used as a raw material for Al. As a raw material, trimethylindium ((CH ₃ ) ₃ In, TMI) is used, and as a raw material of N, ammonia (NH ₃ ) is used. As for the dopant, for example, silane (SiH ₄ ) is used as the n-type dopant, and bis (methylcyclopentadienyl) magnesium ((CH ₃ C ₅ H ₄ ) ₂ Mg) or bis (cyclopentadi) is used as the p-type dopant. Enyl) magnesium ((C ₅ H ₅ ) ₂ Mg) is used.

Next, the sapphire substrate 19 on which the GaN-based semiconductor layer is grown as described above is taken out from the MOCVD apparatus.
Next, a predetermined circular resist pattern is formed on the surface of the substrate by lithography, and an Ag film, a Pt film, and an Au film are sequentially formed on the entire surface of the substrate by, for example, sputtering, and then the resist pattern is formed thereon. It is removed together with the Ag film, Pt film and Au film (lift-off). As a result, as shown in FIG. 5B, a circular p-side electrode 15 having an Ag / Pt / Au structure is formed on the p-type GaN layer 13.

Next, as shown in FIG. 5C, a circular resist pattern 21 that covers the surface of a predetermined region of the p-type GaN layer 13 including the p-side electrode 15 is formed.
Next, using the resist pattern 21 as a mask, for example, by a reactive ion etching (RIE) method using a chlorine-based gas as an etching gas, to a depth in the middle of the thickness of the n-type GaN layer 11 under the condition that taper etching is performed. After the etching, the resist pattern 21 is removed. Thus, as shown in FIG. 6A, the end face 14 having the inclination angle θ ₁ is formed.

Next, as shown in FIG. 6B, a transparent resin 16 is formed. Examples of the method for forming the transparent resin 16 include the following methods. In the first method, the slope 16a is automatically set to an angle of θ ₂ by applying the transparent resin 16 over the entire surface by spin coating. In the second method, the transparent resin 16 was coated by a spin coating method, to set the slope 16a by curing shrinkage of the transparent resin 16 into theta ₂ angles. In the third method, the transparent resin 16 is formed by a photolithography technique. Specifically, a resist (photosensitive resin) is used as the transparent resin 16, and the slope 16a is set to an angle θ ₂ by applying, exposing and developing the resist. In the fourth method, the slope 16a is set to an angle of θ ₂ by press-molding the transparent resin 16 using a predetermined mold. In the fifth method, the slope 16a is set to an angle of θ ₂ by thermal imprinting the transparent resin 16. In the sixth method, to set the slope 16a to the theta ₂ of the angle by UV imprint molding a transparent resin 16. In the seventh method, after applying the transparent resin 16 by a spin coating method or the like, the transparent resin 16 is cured in a state where the transparent resin 16 is pressed against a release layer that can be elastically deformed, so that the inclined surface 16a is θ _2. Set the angle to.

  Next, an Ag film and an Au film are sequentially formed on the entire surface of the substrate by sputtering, for example, and a predetermined circular resist pattern is formed thereon by lithography, and then the Ag film and Au film are etched using the resist pattern as a mask. To do. As a result, as shown in FIG. 6C, a circular reflecting film 17 having an Ag / Au structure is formed on the transparent resin 16 and the p-side electrode 15.

  Next, after the reflective film 17 side is bonded to a separately prepared sapphire substrate (not shown) with a resin or the like, a laser beam such as an excimer laser is irradiated from the back side of the sapphire substrate 19 to form the sapphire substrate 19 By ablating the interface with the n-type GaN layer 11, the upper part from the n-type GaN layer 11 is peeled off from the sapphire substrate 19. Next, by polishing, for example, by a chemical mechanical polishing (CMP) method, the GaN buffer layer 20 on the peeled surface is removed, and the n-type GaN layer 11 is thinned until it reaches the inclined surface 14. At this point, the GaN light emitting diodes are separated.

  Next, a predetermined circular resist pattern is formed on the surface of the n-type GaN layer 11 by lithography, and a Ti film, a Pt film, and an Au film are sequentially formed on the entire surface by, eg, sputtering, and then the resist pattern is applied to the n-type GaN layer 11. The Ti film, Pt film, and Au film formed thereon are removed (lift-off). Thereby, a circular n-side electrode 18 having a Ti / Pt / Au structure is formed on the n-type GaN layer 11.

Thereafter, the sapphire substrate to which the reflective film 17 side is bonded is removed to separate the GaN-based light emitting diodes.
As described above, the target GaN-based light emitting diode 1 is completed as shown in FIG.
FIG. 7 shows an example in which a transparent wiring 22 made of ITO or the like is formed on the back surface of the n-type GaN layer 11 so as to cover the n-side electrode 18 in addition to the n-side electrode 18.
FIG. 8 shows a GaN-based light emitting diode 1 in which the n-type GaN layer 11, the active layer 12, and the p-type GaN layer 13 have a rectangular cross-sectional shape (θ ₁ = 90 degrees). In this case, the p-side electrode 15 is formed on the entire upper surface of the p-type GaN layer 13, and the n-side electrode 18 is formed on the entire back surface of the n-type GaN layer 11. The diameters of the n-type GaN layer 11, the active layer 12, and the p-type GaN layer 13 are, for example, 10 μm or less, typically 5 μm or less. On the other hand, if the diameter is too small, it is difficult to obtain sufficient emission intensity. Although it is 2-3 micrometers or more, it is not limited to this. In this GaN-based light emitting diode, even if the diameters of the n-type GaN layer 11, the active layer 12, and the p-type GaN layer 13 are so small, the p-side electrode 15 is formed on the entire upper surface of the p-type GaN layer 13, Since the n-side electrode 18 is also formed on the entire back surface of the n-type GaN layer 11, the current density can be reduced, luminance saturation can be prevented, and the p-side electrode 15 and the n-side electrode 18 can be prevented. The contact resistance can be reduced, and the operating voltage can be reduced. Further, unlike the conventional GaN-based light emitting diode shown in FIG. 18, light generated from the active layer 12 is absorbed by repeating total reflection inside the n-type GaN layer 11, the active layer 12 and the p-type GaN layer 13. Without taking out. An example of the optical path of the light generated from the active layer 12 and finally extracted outside the GaN-based light emitting diode 1 is shown in FIG.

FIG. 9 shows a GaN-based light emitting diode 1 in which the n-type GaN layer 11, the active layer 12, and the p-type GaN layer 13 have an inverted trapezoidal shape (θ ₁ > 90 degrees). In this case, the diameter of the p-type GaN layer 13 can be made larger than when the n-type GaN layer 11, the active layer 12 and the p-type GaN layer 13 have a trapezoidal shape (θ ₁ <90 degrees). As a result, the diameter of the p-side electrode 15 can be increased. Therefore, the current density can be reduced, luminance saturation can be prevented, the contact resistance of the p-side electrode 15 can be reduced, and the operating voltage can be reduced. An example of an optical path of light generated from the active layer 12 and finally extracted outside the GaN-based light emitting diode 1 is shown in FIG.

As described above, according to the first embodiment, the light extraction efficiency can be maximized by optimizing the structure of the GaN-based light-emitting diode 1, and the GaN-based light-emitting diode 1 can be reduced to a low refractive index transparent medium. By mounting on the transparent substrate 2 via the layer 3, the light extraction efficiency of the light-emitting diode mounting substrate from the transparent substrate 2 to the outside can be maximized.
Regarding the light extraction efficiency of the GaN-based light emitting diode 1, for example, as shown in FIG. 10, about 61.7% of the light generated from the active layer 12 can be extracted from the lower surface of the n-type GaN layer 11. This is a remarkably high value compared to the light extraction efficiency of the GaN-based light emitting diode shown in FIG. Further, the GaN-based light emitting diode 1 has a structure suitable for miniaturization, and an ultra-small one having a size of, for example, several tens of μm or less can be easily obtained.

FIG. 11 shows the measurement result of the light emission intensity-current characteristic of the example of the GaN-based light emitting diode 1. However, as the p-side electrode 15 and the reflective film 17, an Ag single layer film was used. The maximum diameter a of the light emitting diode structure is 20 μm, the thickness of the n-type GaN layer 11 is 2600 nm, the thickness of the active layer 12 and the p-type GaN layer 13 is 200 nm, θ ₁ = 50 degrees, θ ₂ = 20 degrees, respectively. It is. For comparison, FIG. 11 shows light emission of a GaN-based light-emitting diode having a structure similar to that of the GaN-based light-emitting diode except that a Ni single-layer film is used as the p-side electrode 15 and the reflective film 17 is not formed. The measurement results of strength-current characteristics are also shown. As is apparent from FIG. 11, the GaN-based light emitting diode 1 with the reflective film 17 formed has a light emission as compared with a GaN-based light emitting diode that uses a Ni single-layer film as the p-side electrode 15 and does not have the reflective film 17 formed. The strength is about 3 times larger.

  The light extraction efficiency of the light emitting diode mounting substrate according to the first embodiment having the low refractive index transparent medium layer 3 and the light emitting diode mounting substrate not having the low refractive index transparent medium layer 3 were measured. The results are shown in Table 1.

  Here, in Example 1, an air gap having a refractive index N = 1.0 and a thickness of 3 μm as the low refractive index transparent medium layer 3, and a sapphire substrate having a refractive index N = 1.76 and a thickness of 400 μm as the transparent substrate 2. Using. In Example 2, a low refractive index transparent material layer having a refractive index N = 1.37 and a thickness of 3 μm formed by Cytop (registered trademark), which is a transparent fluororesin manufactured by Asahi Glass Co., Ltd., as the low refractive index transparent medium layer 3. As the transparent substrate 2, a sapphire substrate having a refractive index N = 1.76 and a thickness of 400 μm was used. In the comparative example, the low refractive index transparent medium layer 3 was not used, and a sapphire substrate having a refractive index N = 1.76 and a thickness of 400 μm was used as the transparent substrate 2 (structure shown in FIG. 21). In Reference Example 1, a low-refractive-index transparent material layer having a refractive index N = 1.48 and a thickness of 3 μm formed of ITO ink is used as the low-refractive-index transparent medium layer 3, and there is no transparent substrate 2. In Reference Example 2, a low refractive index transparent material having a refractive index N = 1.37 and a thickness of 3 μm formed by Cytop (registered trademark), which is a transparent fluororesin manufactured by Asahi Glass Co., Ltd., as the low refractive index transparent medium layer 3. A layered structure of a layer and a low refractive index transparent material layer having a refractive index N = 1.48 and a thickness of 3 μm formed by ITO ink is used, and there is no transparent substrate 2. However, in each of Examples 1, 2 and Comparative Examples and Reference Examples 1 and 2, a single-layer Ag film was used as the reflective film 17, and a Ni electrode or an Ag electrode was used as the p-side electrode 15.

  As shown in Table 1, Example 1 using an air gap having a thickness of 3 μm as the low refractive index transparent medium layer 3, and a refractive index N = 1 formed by Cytop (registered trademark) as the low refractive index transparent medium layer 3. In Example 2 using the low-refractive-index transparent material layer of 37, the light extraction efficiency is dramatically increased as compared with the comparative example not using the low-refractive-index transparent medium layer 3. When an Ag electrode is used as the p-side electrode 15, an extremely high light extraction efficiency of 55.0% is obtained.

  The GaN-based light-emitting diode 1 can obtain blue light-emitting, green light-emitting or red light-emitting diode, and a high-performance light-emitting diode display, light-emitting diode backlight using the light-emitting diode mounting substrate on which the GaN-based light emitting diode 1 is mounted. In addition, a light emitting diode illumination device or the like can be easily realized. The GaN-based light emitting diode 1 can also be used for display and illumination in various electronic devices such as mobile phones. The GaN-based light emitting diode 1 may be used as a blue light emitting or green light emitting diode, and a red light emitting AlGaInP light emitting diode described later may be used as a red light emitting diode.

Next explained is a light emitting diode mounting board according to a second embodiment of the invention.
This second embodiment is the same as the first embodiment except that the GaN-based light emitting diode 1 shown in FIG. 12 is used.
As shown in FIG. 12, in the GaN-based light emitting diode 1, the slope 16a of the transparent resin 16 is not a flat surface, and a concave portion is formed in the middle of the slope 16a, and a reflective film is formed on the concave slope 16a. Except that 17 is formed, it has the same structure as the GaN-based light emitting diode 1 according to the first embodiment.
According to the second embodiment, the same advantages as those of the first embodiment can be obtained.

Next explained is a light emitting diode mounting board according to a third embodiment of the invention.
The third embodiment is the same as the first embodiment except that the GaN-based light emitting diode 1 shown in FIG. 13 is used.
As shown in FIG. 13, in the GaN-based light emitting diode 1, the inclined surface 16a of the transparent resin 16 is not a flat surface, but is a convex surface protruding partway along the inclined surface 16a, and a reflective film is formed on the convex surface 16a. Except that 17 is formed, it has the same structure as the GaN-based light emitting diode 1 according to the first embodiment.
According to the third embodiment, the same advantages as those of the first embodiment can be obtained.

Next explained is a light emitting diode mounting board according to the fourth embodiment of the invention.
The fourth embodiment is the same as the first embodiment except that an AlGaInP light emitting diode 5 shown in FIG. 14 is mounted on the transparent substrate 2.
As shown in FIG. 14, the AlGaInP light emitting diode 5 includes an n-type GaAs layer 51, an n-type AlGaInP layer 52, an active layer 53, a p-type AlGaInP layer 54, and a p-type GaAs layer 55 thereon. A light emitting diode structure is formed. The n-type GaAs layer 51 is formed only at the center of the n-type AlGaInP layer 52. Further, the p-type GaAs layer 55 is formed only in the central portion of the p-type AlGaInP layer 54. The n-type AlGaInP layer 52, the active layer 53, and the p-type AlGaInP layer 54 as a whole have, for example, a circular planar shape, and the diametrical cross-sectional shape thereof is trapezoidal, rectangular, or inverted trapezoidal, and the end face 14 is in relation to the main surface. It is the angle theta ₁ inclined Te. On the p-type GaAs layer 55, for example, a circular p-side electrode 15 is formed. A transparent resin 16 is formed so as to cover the end surface 14 of this light emitting diode structure and the upper surface of the p-type GaAs layer 55 around the p-side electrode 15. A reflective film 17 is formed so as to cover the transparent resin 16 and the entire p-side electrode 15. For example, a circular n-side electrode 18 is formed on the lower surface of the n-type GaAs layer 51.
This AlGaInP light emitting diode 5 has the same features (1) to (8) as the GaN light emitting diode 1 according to the first embodiment.

Specific examples of dimensions and materials of the respective parts of the AlGaInP light emitting diode 5 are as follows. The thickness of the n-type GaAs layer 51 is, for example, 50 nm, the thickness of the n-type AlGaInP layer 52 is, for example, 1000 nm, the thickness of the active layer 53 is, for example, 900 nm, and the thickness of the p-type AlGaInP layer 54 is, for example, 1000 nm. The thickness of 55 is, for example, 50 nm. The composition of the n-type AlGaInP layer 52 and the p-type AlGaInP layer 54 is, for example, Al = 0 to 0.7 when Al + Ga = 1 when the sum of the composition of Al and Ga is substantially equal to the composition of In. . The active layer 53 has, for example, an MQW structure composed of a Ga _0.5 In _0.5 P well layer and an (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P barrier layer. The maximum diameter a of the light emitting diode structure is, for example, 20 μm. As described above, the thickness of the n-type GaAs layer 51 is 50 nm, the thickness of the n-type AlGaInP layer 52 is 1000 nm, the thickness of the active layer 53 is 900 nm, the thickness of the p-type AlGaInP layer 54 is 1000 nm, and the p-type GaAs layer When the thickness of 55 is 50 nm, the total thickness of this light emitting diode structure is 50 + 1000 + 900 + 1000 + 50 = 3000 nm = 3 μm. In this case, the aspect ratio of the light emitting diode structure is b / a = 3/20 = 0.15. θ ₁ is, for example, 45 degrees. When the refractive index of the transparent resin 16 is 1.6, the applied thickness is 1 μm at the flat portion, and the thickness is reduced to 70% due to curing shrinkage, θ ₂ is 20 degrees, for example. The p-side electrode 18 is made of, for example, a metal multilayer film having an Au / Pt / Au structure. The Au film has a thickness of 50 nm, the Pt film has a thickness of 50 nm, and the Au film has a thickness of 2000 nm, for example. The reflective film 17 is made of, for example, an Au single layer film, and has a thickness of, for example, 100 nm. The n-side electrode 18 is made of, for example, a metal laminated film having a Pd / AuGe / Au structure. The thickness of the Pd film is, for example, 10 nm, the thickness of the AuGe film is, for example, 90 nm, and the thickness of the Au film is, for example, 2000 nm.

Next, a method for manufacturing the AlGaInP light emitting diode 5 will be described.
As shown in FIG. 15A, first, for example, MOCVD is performed on an n-type GaAs substrate 56 having a thickness of 350 μm, for example, the main surface being off by about 10 degrees in the [100] direction from the (001) plane or (001) plane. For example, an n-type AlGaInP etching stop layer 57 having a thickness of, for example, 500 nm is grown at a temperature of, for example, about 800 ° C., and an n-type GaAs layer 51, an n-type AlGaInP layer 52, an active layer 53, and a p-type AlGaInP are formed thereon. Layer 54 and p-type GaAs layer 55 are grown sequentially.

For example, trimethylgallium ((CH ₃ ) ₃ Ga, TMG) is used as a Ga source, and trimethylaluminum ((CH ₃ ) ₃ Al, TMA) is used as an Al source. As a raw material, trimethylindium ((CH ₃ ) ₃ In, TMI) is used, and as a raw material of P, phosphine (PH ₃ ) is used. As for the dopant, for example, hydrogen selenide (H ₂ Se) is used as the n-type dopant, and dimethyl zinc ((CH ₃ ) ₂ Zn, DMZn) is used as the p-type dopant.

Next, the n-type GaAs substrate 56 on which the AlGaInP-based semiconductor layer has been grown as described above is taken out from the MOCVD apparatus.
Next, as shown in FIG. 15B, a circular resist pattern 21 is formed on the p-type GaAs layer 55.
Next, using the resist pattern 21 as a mask, etching is performed up to the n-type GaAs layer 51 by tape etching, for example, by RIE, and then the resist pattern 21 is removed. Thus, as shown in FIG. 15C, the end face 14 having the inclination angle θ ₁ is formed. In this etching, the etching is stopped when the n-type AlGaInP etching stop layer 57 is exposed.

  Next, a predetermined circular resist pattern is formed on the surface of the substrate by lithography, and an Au film, a Pt film, and an Au film are sequentially formed on the entire surface of the substrate by sputtering, for example, and then the resist pattern is formed thereon. It is removed together with the Au film, Pt film and Au film (lift-off). As a result, as shown in FIG. 16A, a circular p-side electrode 15 having an Au / Pt / Au structure is formed on the p-type GaAs layer 55. Next, the p-type GaAs layer 55 other than the p-side electrode 15 is removed by etching.

Next, as shown in FIG. 16B, a transparent resin 16 is formed. As a method for forming the transparent resin 16, for example, a method similar to that of the first embodiment can be used.
Next, an Au film is formed on the entire surface of the substrate by sputtering, for example, and a circular resist pattern is formed thereon by lithography, and then the Au film is etched using this resist pattern as a mask. As a result, as shown in FIG. 16C, a circular reflective film 17 made of a single layer film of Au is formed on the transparent resin 16 and the p-side electrode 15.

  Next, after the reflective film 17 side is bonded to a separately prepared sapphire substrate (not shown) with a resin or the like, the n-type GaAs substrate 56 is etched away from the back side by, for example, wet etching, and subsequently n-type. The AlGaInP etching stop layer 57 is also removed by etching. At this point, the AlGaInP light emitting diodes are separated.

  Next, a predetermined circular resist pattern is formed on the surface of the n-type GaAs layer 51 by lithography, and a Pd film, an AuGe film, and an Au film are sequentially formed on the entire surface by sputtering, for example, and then the resist pattern is formed thereon. The Pd film, the AuGe film, and the Au film formed on the first layer are removed (lift-off). Thus, a circular n-side electrode 18 having a Pd / AuGe / Au structure is formed on the n-type GaAs layer 51. Thereafter, the n-type GaAs layer 51 other than the n-side electrode 18 is removed by etching.

Thereafter, the sapphire substrate to which the reflective film 17 side is bonded is removed to separate each AlGaInP light emitting diode.
Thus, as shown in FIG. 14, the target AlGaInP light emitting diode 5 is completed.
FIG. 17 shows an example in which a transparent wiring 22 made of ITO or the like is formed on the back surface of the n-type AlGaInP layer 52 so as to cover the n-side electrode 18.
According to the fourth embodiment, the same advantages as those of the first embodiment can be obtained.

As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, The various deformation | transformation based on the technical idea of this invention is possible.
For example, the numerical values, materials, structures, shapes, substrates, raw materials, processes, and the like given in the first to fourth embodiments are merely examples, and if necessary, numerical values, materials, structures, Shapes, substrates, raw materials, processes, etc. may be used.

It is sectional drawing which shows the light emitting diode mounting substrate by 1st Embodiment of this invention. It is sectional drawing which shows the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is sectional drawing for demonstrating the characteristic of the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is sectional drawing for demonstrating the characteristic of the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is sectional drawing which shows what formed the transparent wiring in the n side electrode side of the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is sectional drawing which shows the case where (theta) ₁ = 90 degree | times in the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is sectional drawing which shows the case where (theta) ₁ > 90 degree | times in the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is a basic diagram for demonstrating extraction of the light from the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is a basic diagram which shows the example of the measurement result of the light emission intensity-current characteristic of the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 1st Embodiment of this invention. It is sectional drawing which shows the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 2nd Embodiment of this invention. It is sectional drawing which shows the GaN-type light emitting diode mounted in the light emitting diode mounting substrate by 3rd Embodiment of this invention. It is sectional drawing which shows the AlGaInP type light emitting diode mounted in the light emitting diode mounting substrate by 4th Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the AlGaInP type | system | group light emitting diode mounted in the light emitting diode mounting substrate by 4th Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the AlGaInP type | system | group light emitting diode mounted in the light emitting diode mounting substrate by 4th Embodiment of this invention. It is sectional drawing which shows what formed the transparent wiring in the n side electrode side of the AlGaInP type light emitting diode mounted in the light emitting diode mounting substrate by 4th Embodiment of this invention. It is sectional drawing which shows the conventional GaN-type light emitting diode. It is sectional drawing which shows the GaN-type light emitting diode which the present inventors examined. It is a basic diagram for demonstrating extraction of the light from the GaN-type light emitting diode which the present inventors examined. It is a basic diagram for demonstrating extraction of the light from the light emitting diode mounting board | substrate which the present inventors examined.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... GaN type light emitting diode, 2 ... Transparent substrate, 3 ... Low refractive index transparent medium layer, 4 ... Resin, 5 ... AlGaInP type light emitting diode, 11 ... n-type GaN layer, 12 ... Active layer, 13 ... p-type GaN layer , 14 ... end face, 15 ... p-side electrode, 16 ... transparent resin, 16a ... slope, 17 ... reflective film, 18 ... n-side electrode, 19 ... sapphire substrate, 22 ... transparent wiring, 23 ... irregularities, 51 ... n-type GaAs Layer 52... N-type AlGaInP layer 53... Active layer 54... P-type AlGaInP layer 55... P-type GaAs layer 56.

Claims (17)

The semiconductor layer forming the light emitting diode structure has an end face inclined with respect to the main surface, and at least one light emitting diode having a reflector outside the end face is formed on the transparent substrate with the light of the semiconductor layer. With the take-out surface facing the transparent substrate side, the semiconductor layer and the transparent substrate are mounted via a layer made of a transparent medium having a refractive index smaller than that of the transparent substrate ,
A light-emitting diode mounting substrate in which a transparent resin having a refractive index smaller than that of the semiconductor layer is formed between the end face and the reflector . The semiconductor layer and the layer made of a transparent medium having a refractive index smaller than the refractive index of the transparent substrate are the air gap, the layer made of a transparent material having a refractive index smaller than the refractive index of the semiconductor layer and the transparent substrate, or the air gap and the semiconductor layer and the light-emitting diode mounting substrate of the composite layer der of Ru請 Motomeko 1 wherein a layer made of a transparent material having a refractive index lower than the refractive index of the transparent substrate. The light emitting diode is
The semiconductor layer is a light emitting diode having an end face inclined at an angle θ _{1 with} respect to the main surface,
Outside of the end surface, opposed to the end surface, and Ru der those having the reflector at least partially including a part that the angle theta ₁ is less than the angle theta ₂ inclined with respect to the main surface invoiced Item 4. The light-emitting diode mounting substrate according to Item 1. 2. The light emitting diode mounting substrate according to claim 1, wherein the thickness of the semiconductor layer is 0.3 μm or more and 10 μm or less, and the ratio of the thickness of the semiconductor layer to the maximum diameter of the semiconductor layer is 0.001 or more and 2 or less. . The semiconductor layer has a first electrode and a second electrode on a light extraction surface and a surface opposite to the light extraction surface, respectively, and the reflector is in ohmic contact with the second electrode, 2. The light emitting diode mounting substrate according to claim 1, wherein a part of said electrode or a part of said second electrode wiring is also used. The reflector has at least 30 degrees ≦ θ ₁ When ≦ 90 degrees, the end face is in a direction perpendicular to the end face, 90 degrees <θ ₁ 4. When ≦ 150 degrees, the end face is formed so as to include a region projected on the surface on which the reflector is formed in a direction perpendicular to the end face at the light extraction surface of the semiconductor layer. The light emitting diode mounting substrate described. The light emitting diode mounting substrate according to claim 1, wherein the reflector is formed to extend on a surface opposite to the light extraction surface of the semiconductor layer. The refractive index of the transparent resin is n ₂ , The refractive index of the medium outside the transparent resin is n _Three Where 30 degrees ≦ θ ₁ ≦ 150 degrees and 30 degrees ≦ θ ₁ ≦ 90 degrees when θ ₂ ≧ (θ ₁ -Sin ^-1 (N _Three / N ₂ )) / 2 and θ ₂ ≦ θ ₁ / 2, 90 degrees <θ ₁ ≤150 degrees when θ ₂ ≧ ((θ ₁ -90) -sin ^-1 (N _Three / N ₂ )) / 2 and θ ₂ ≤ (θ ₁ The light emitting diode mounting substrate according to claim 3, which is −90) / 2. The semiconductor layer has a first electrode and a second electrode on a light extraction surface and a surface opposite to the light extraction surface, respectively, and the first electrode has the end surface perpendicular to the light extraction surface of the semiconductor layer. The light emitting diode mounting substrate according to claim 1, wherein the light emitting diode mounting substrate is formed so as to avoid a region projected in a direction. A light emitting diode mounting substrate in which a plurality of red light emitting diodes, green light emitting diodes and blue light emitting diodes are respectively mounted on a transparent substrate;
At least one of the red light emitting diode, the green light emitting diode, and the blue light emitting diode has an end surface on which a semiconductor layer forming a light emitting diode structure is inclined with respect to a main surface thereof A light emitting diode having a reflector outside the end surface, and the light emitting diode is disposed on the transparent substrate with the light extraction surface of the semiconductor layer facing the transparent substrate. It is mounted via a layer made of a transparent medium having a refractive index smaller than that of the transparent substrate,
A light emitting diode backlight in which a transparent resin having a refractive index smaller than that of the semiconductor layer is formed between the end face and the reflector. The at least one light emitting diode is:
The semiconductor layer has an angle θ with respect to its main surface. ₁ A light emitting diode having an inclined end face,
Outside the end face, facing the end face, and the angle θ with respect to the main face ₁ Smaller angle θ ₂ The light-emitting diode backlight according to claim 10, wherein the light-emitting diode backlight includes the reflector including at least a part that is inclined. A light emitting diode mounting substrate in which a plurality of red light emitting diodes, green light emitting diodes and blue light emitting diodes are respectively mounted on a transparent substrate;
At least one of the red light emitting diode, the green light emitting diode, and the blue light emitting diode has an end surface on which a semiconductor layer forming a light emitting diode structure is inclined with respect to a main surface thereof A light emitting diode having a reflector outside the end surface, and the light emitting diode is disposed on the transparent substrate with the light extraction surface of the semiconductor layer facing the transparent substrate. It is mounted via a layer made of a transparent medium having a refractive index smaller than that of the transparent substrate,
A light-emitting diode illuminating device, wherein a transparent resin having a refractive index smaller than that of the semiconductor layer is formed between the end face and the reflector. The at least one light emitting diode is:
The semiconductor layer has an angle θ with respect to its main surface. ₁ A light emitting diode having an inclined end face,
Outside the end face, facing the end face, and the angle θ with respect to the main face ₁ Smaller angle θ ₂ The light-emitting diode illuminating device according to claim 12, wherein the light-emitting diode illuminating device includes the reflector including at least a portion that is inclined. A light emitting diode mounting substrate in which a plurality of red light emitting diodes, green light emitting diodes and blue light emitting diodes are respectively mounted on a transparent substrate;
At least one of the red light emitting diode, the green light emitting diode, and the blue light emitting diode has an end surface on which a semiconductor layer forming a light emitting diode structure is inclined with respect to a main surface thereof A light emitting diode having a reflector outside the end surface, and the light emitting diode is disposed on the transparent substrate with the light extraction surface of the semiconductor layer facing the transparent substrate. It is mounted via a layer made of a transparent medium having a refractive index smaller than that of the transparent substrate,
A light emitting diode display in which a transparent resin having a refractive index smaller than that of the semiconductor layer is formed between the end face and the reflector. The at least one light emitting diode is:
The semiconductor layer has an angle θ with respect to its main surface. ₁ A light emitting diode having an inclined end face,
Outside the end face, facing the end face, and the angle θ with respect to the main face ₁ Smaller angle θ ₂ The light emitting diode display according to claim 14, wherein the light emitting diode display includes the reflector including at least a portion that is inclined. Having a light emitting diode mounting substrate in which one or a plurality of light emitting diodes are mounted on a transparent substrate;
At least one of the light emitting diodes is a light emitting diode in which a semiconductor layer forming a light emitting diode structure has an end surface inclined with respect to the main surface, and a reflector is provided outside the end surface. Mounted on the transparent substrate through a layer made of a transparent medium having a refractive index smaller than that of the semiconductor layer and the transparent substrate, with the light extraction surface of the semiconductor layer facing the transparent substrate.
An electronic device in which a transparent resin having a refractive index smaller than that of the semiconductor layer is formed between the end face and the reflector. The at least one light emitting diode is:
The semiconductor layer has an angle θ with respect to its main surface. ₁ A light emitting diode having an inclined end face,
Outside the end face, facing the end face, and the angle θ with respect to the main face ₁ Smaller angle θ ₂ The electronic device according to claim 16, comprising the reflector including at least a portion that is inclined.

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