JP2008193006A - GaN LED chip - Google Patents

Abstract

To provide a GaN-based LED chip excellent in light emission output, which can be suitably used for applications such as illumination.
A GaN-based LED chip includes a translucent plate-like body including a conductive substrate and a plurality of GaN-based semiconductor layers stacked thereon. One or more bottom-side pad electrodes are formed on the bottom surface of the plate-like body, and one or more top-side pad electrodes are formed on the top surface of the plate-like body, and the bottom surface with respect to the area of the plate-like body The first area ratio, which is the ratio of the total area of the side pad electrodes, and the second area ratio, which is the ratio of the total area of the upper surface side pad electrode to the area of the plate-like body, are both less than 50%. .
[Selection] Figure 1

Description

The present invention provides a translucent light source including a conductive substrate and a plurality of GaN-based semiconductor layers including a first conductive type layer, a light emitting layer, and a second conductive type layer stacked on one surface of the conductive substrate. The present invention relates to a GaN-based LED chip having a conductive plate-like body.

A GaN-based semiconductor is a compound semiconductor represented by the chemical formula Al _a In _b Ga _1-ab N (0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ a + b ≦ 1), and is a group III nitride semiconductor Also called a nitride-based semiconductor. 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 GaN-based semiconductor. A GaN-based LED in which a light-emitting element structure such as a pn junction structure, a double hetero structure, or a quantum well structure is formed of a GaN-based semiconductor can generate green to near-ultraviolet light. It has been put to practical use in such applications.

In a GaN-based LED having a translucent electrode formed using a conductive oxide such as indium tin oxide (ITO), light absorption by the pad electrode formed on the light extraction surface side of the plate-like LED chip is It has been pointed out as one of the factors hindering the high output of LED chips (Patent Document 1). The pad electrode is an electrode to which a material used for connection to an external electrode such as a bonding wire, a conductive paste, or a brazing material (solder, eutectic) is bonded.
JP 2005-317931 A

However, it has a light-transmitting plate-like body formed by forming a light-emitting element structure made of a GaN-based semiconductor on a light-transmitting conductive substrate, and has a bottom surface (mounting surface) and a top surface (light emission observation surface). In a GaN LED chip having a so-called vertical structure type element structure in which each electrode is formed, the influence of light absorption by the electrode on the mounting surface side on the output of the LED chip has not been considered so far. On the contrary, in such GaN-based LED chips, it seems that it is even considered preferable to form a metal reflective film having a large area so as to cover the entire bottom surface of the plate-like body.

This invention is made | formed in view of this situation, The main objective is to provide the GaN-type LED chip excellent in the light emission output which can be used suitably for uses, such as an illumination use.

In order to achieve the above object, the present invention provides a GaN-based LED chip having the following characteristics.
(1) Translucent including a conductive substrate and a plurality of GaN-based semiconductor layers including a first conductive type layer, a light emitting layer, and a second conductive type layer stacked on one surface of the conductive substrate In the GaN-based LED chip having the bottom surface and the top surface, and the light emission observation surface on the top surface side of the plate body, one or more on the bottom surface of the plate body The bottom surface side pad electrode is formed, and one or more top surface side pad electrodes are formed on the upper surface of the plate-like body, and the ratio of the total area of the bottom surface side pad electrode to the area of the plate-like body is 1 area ratio and the 2nd area ratio which is a ratio of the total area of the said upper surface side pad electrode with respect to the area of the said plate-shaped object, both are less than 50%, The GaN-type LED chip characterized by the above-mentioned.
(2) The GaN-based LED chip according to (1), wherein each of the first area ratio and the second area ratio is 30% or less.
(3) The GaN-based LED chip according to (1) or (2), wherein each of the first area ratio and the second area ratio is 20% or less.
(4) The GaN-based LED chip according to any one of (1) to (3), wherein at least the second area ratio is 10% or less.
(5) The GaN-based LED chip according to any one of (1) to (4), wherein each of the first area ratio and the second area ratio is 10% or less.
(6) The GaN-based LED chip according to any one of (1) to (5), wherein at least the second area ratio is 5% or less.
(7) The GaN-based LED chip according to any one of (1) to (5), wherein at least the second area ratio is 3% or less.
(8) The GaN-based LED chip according to any one of (1) to (7), wherein the number of the bottom surface side pad electrodes is 3 to 10.

Since the GaN-based LED chip according to the embodiment of the present invention has excellent light emission output, the GaN-based LED chip can be suitably used in applications that require high output such as illumination.

A GaN-based LED chip according to a preferred embodiment of the present invention includes a conductive substrate and a first conductive type layer, a light emitting layer, and a second conductive type layer stacked on one surface of the conductive substrate. A GaN-based LED chip having a translucent plate-like body including a plurality of GaN-based semiconductor layers, the plate-like body having a bottom surface and an upper surface, and the upper surface side of the plate-like body being a light emission observation surface. One or more bottom-side pad electrodes are formed on the bottom surface of the plate-like body, and one or more top-side pad electrodes are formed on the top surface of the plate-like body. The first area ratio, which is the ratio of the total area of the bottom surface side pad electrode to the area, and the second area ratio, which is the ratio of the total area of the upper surface side pad electrode to the area of the plate-like body, are both 50%. It has a characteristic configuration of less than. A sectional view of this GaN-based LED chip is shown in FIG.

A GaN-based LED chip 100 shown in FIG. 1 includes a first conductive type layer 101-2, a light emitting layer 101-3, and a second conductive type layer 101-4 made of a GaN-based semiconductor on a conductive substrate 101-1. It has the plate-like body 101 formed by lamination. The conductive substrate 101-1 has a light-transmitting property. For this reason, the plate-like body 101 has a light-transmitting property as a whole. The translucency here means the property of transmitting light having the same wavelength as the light emitted from the light emitting layer 101-3 when the GaN-based LED chip 100 is energized. Translucency does not mean that the transmittance is 100%, nor does it mean that it is transparent without being clouded.

A substrate-side pad electrode 102 is formed on the surface A of the plate-like body 101 on the conductive substrate 101-1 side. On the other hand, the light emitting layer side pad electrode 103 is formed on the surface B on the side where a plurality of GaN-based semiconductor layers including the light emitting layer 101-3 are laminated. Here, when mounting the GaN-based LED chip 100, the surface that becomes the mounting surface is called the bottom surface of the plate-like body 101, and the surface that becomes the light emission observation surface is called the upper surface of the plate-like body 101. Any one of the surface A and the surface B of the plate-like body 101 can be a bottom surface, and any one can be a top surface. Therefore, the substrate side pad electrode 102 can be a bottom surface side pad electrode or a top surface side pad electrode. Naturally, when the substrate side pad electrode 102 is a bottom surface side pad electrode, the light emitting layer side pad electrode 103 is a top surface side pad electrode, and when the substrate side pad electrode 102 is a top surface side pad electrode, The light emitting layer side pad electrode 103 becomes the bottom surface side pad electrode.

The most characteristic configurations of the GaN-based LED chip 100 are the ratio of the total area of the substrate-side pad electrode 102 to the area of the plate-like body 101 (referred to as “area ratio a”) and the total area of the light-emitting layer-side pad electrode 103. The ratio (referred to as “area ratio b”) is less than 50%. Here, the area of the plate-like body 101 is a cross-sectional area when the plate-like body 101 is cut by a plane orthogonal to the thickness direction so that the thickness of the plate-like body 101 is halved. By limiting the area ratio a and the area ratio b in this way, light absorption by the metal pad electrodes 102 and 103 is suppressed, so that the GaN-based LED chip 100 has excellent light emission output. Since the light absorption by the pad electrodes 102 and 103 can be suppressed as the area ratio a and the area ratio b are reduced, in the preferred embodiment, the area ratio a and the area b are both 30% or less. Then, both the area ratio a and the area ratio b are 20% or less, and in a more preferred embodiment, both the area ratio a and the area ratio b are 10% or less. In particular, since the number of upper surface side pad electrodes may be only one, the ratio of the total area of the upper surface side pad electrodes to the area of the plate-like body 101 is preferably 10% or less, more preferably. Is 5% or less, more preferably 3% or less. It is preferable that the number of the bottom-side pad electrodes is three or more so that the posture of the LED chip after mounting or after mounting becomes stable. The stability of the posture of the LED chip is the highest when the number of bottom surface side pad electrodes is three. On the other hand, increasing the number of bottom-side pad electrodes can firmly fix the LED chip to a mounting substrate such as a substrate or a lead frame. However, if the number of the bottom surface side pad electrodes is excessively increased, a problem that the time required for the mounting becomes longer occurs. Therefore, the number of the bottom surface side pad electrodes is preferably 10 or less, and preferably 5 or less. More preferred. Further, in the GaN-based LED chip 100, except for the substrate-side pad electrode 102 and the light emitting layer-side pad electrode 103, no metal member is provided on the surface or inside thereof. This is because the metal member is not limited to the pad electrode, but acts as a light absorber, and works in the direction of reducing the light emission efficiency of the LED. In addition to the metal member, the LED chip 100 is preferably not provided with a dielectric multilayer film type reflection film on the surface or inside thereof. In particular, it is not preferable to provide such a reflective film so that light emitted from the light emitting layer is reflected again toward the light emitting layer, because this light is easily reabsorbed by the light emitting layer.

The conductive substrate 101-1 that can be used for the GaN-based LED chip 100 is not particularly limited as long as it has translucency, and specifically, a GaN-based semiconductor such as GaN or AlGaN, an oxidation substrate, or the like. A crystal substrate (single crystal substrate, template) made of a semiconductor material such as gallium, gallium phosphide, silicon carbide, or zinc oxide can be preferably selected. The first conductive type layer 101-2, the light emitting layer 101-3, and the second conductive type layer 101-4 made of a GaN-based semiconductor can be formed by vapor phase epitaxial growth on the conductive substrate 101-1. In that case, it is preferable to interpose a buffer layer between the conductive substrate 101-1 and the first conductivity type layer 101-2. As a typical buffer layer, a low temperature buffer layer or a high temperature buffer layer formed of a GaN-based semiconductor is exemplified. In order to generate lateral growth of the GaN-based semiconductor crystal during epitaxial growth, a mask made of silicon oxide or the like is partially formed on the surface of the conductive substrate 101-1, or the surface of the conductive substrate 101-1 is uneven. Processing into a shape can also be performed arbitrarily. As another method for stacking a GaN-based semiconductor on the conductive substrate 101-1, a sapphire substrate or the like is prepared as a growth substrate, and the first conductivity type layer 101-2 is formed on the growth substrate by epitaxial growth. The light emitting layer 101-3 and the second conductivity type layer 101-4 are grown to form a laminate, and the conductive substrate 101-1 is directly bonded to the obtained laminate by a method such as direct wafer bonding. It is also possible to obtain the plate-like body 101 by bonding and removing the growth substrate.

Any one of the first conductivity type layer 101-2 and the second conductivity type layer 101-4 may be an n-type layer and the other may be a p-type layer. When these layers are formed by epitaxial growth on the conductive substrate 101-1, the first conductivity type layer 101-2 is an n-type layer and the second conductivity type layer 101-4 is a p-type layer. Is preferred. In order to form a GaN-based semiconductor in the n-type, it is preferable to add impurities such as Si and Ge. In order to form a GaN-based semiconductor in the p-type, it is preferable to add impurities such as Mg and Zn. The light emitting layer 101-3 is not limited by its conductivity type, and may be, for example, a layer with no added impurities, or a layer imparted with n-type or p-type conductivity by the addition of impurities. Alternatively, a laminated body in which an n-type layer and a p-type layer are mixed may be used. The composition of the GaN-based semiconductor constituting the first conductivity type layer 101-2, the light emitting layer 101-3, and the second conductivity type layer 101-4 is not limited, and has any composition such as GaN, AlGaN, InGaN, AlInGaN, etc. A GaN-based semiconductor can be used. Preferably, the composition of the GaN-based semiconductor constituting the light emitting layer and the layers sandwiching the light emitting layer is selected so that a double heterostructure is formed. The light emitting layer 101-3 preferably has a quantum well structure, and particularly preferably has a multiple quantum well structure in which barrier layers and well layers are alternately stacked. Each of the first conductivity type layer 101-2, the light emitting layer 101-3, and the second conductivity type layer 101-4 does not have to be uniform in the thickness direction, and the impurity concentration, crystal composition, etc. are within each layer. It may change continuously or discontinuously in the thickness direction. Moreover, an additional layer can also be provided between each layer.

The material of the substrate-side pad electrode 102 formed on the conductive substrate 101-1 is selected according to the material and conductivity type of the conductive substrate 101-1 so that the contact resistance with the conductive substrate 101-1 is low. To do. For example, when the conductive substrate 101-1 is an n-type GaN substrate, the portion of the substrate-side pad electrode 102 in contact with the conductive substrate 101-1 is Ti (titanium), Al (aluminum), W (tungsten), V It is preferable to use a simple substance such as (vanadium) or an alloy containing one or more metals selected from these. In order to facilitate connection with the external electrode, the substrate-side pad electrode 102 has a surface layer of Ag (silver), Au (gold), Sn (tin), In (indium), Bi (bismuth), Cu ( It is preferable to provide a layer made of copper), Zn (zinc), or the like. In order to reduce the contact resistance between the substrate-side pad electrode 102 and the conductive substrate 101-1, a light-transmitting conductive oxide film is formed on the conductive substrate 101-1, and the conductive oxide The substrate side electrode 102 can also be formed on the film. In that case, the light-transmitting conductive oxide film is treated as a part of the light-transmitting plate-like body 101. The light-transmitting conductive oxide film can be formed using ITO, tin oxide, indium oxide, zinc oxide, or the like. The substrate-side electrode 102 formed on the conductive oxide film has a portion in contact with the conductive oxide film in the platinum group (Rh, Pt, Pd, Ir, Ru, Os), Ni (nickel), Ti (titanium). , W (tungsten), Ag (silver), Al (aluminum) and the like are preferable.

The material of the light emitting layer side pad electrode 103 formed on the second conductivity type layer 101-4 has a low contact resistance to the second conductivity type layer 101-4 according to the conductivity type of the second conductivity type layer 101-4. Choose to be. When the second conductivity type layer 101-4 is an n-type GaN-based semiconductor layer, the light emitting layer side pad electrode 103 has a portion in contact with the second conductivity type layer 101-4 as Ti (titanium), Al (aluminum), W (Tungsten), V (vanadium) or the like, or an alloy containing one or more metals selected from these is preferably used. When the second conductivity type layer 101-4 is a p-type GaN-based semiconductor layer, a transparent electrode as a diffusion electrode for diffusing current in the plane direction of the plate-like body 101 is provided on substantially the entire surface of the second conductivity type layer. A light conductive conductive oxide film is formed, and a light emitting layer side electrode 103 is formed thereon. Such a conductive oxide film functioning as a diffusion electrode can be provided even when the second conductivity type layer 101-4 is an n-type layer. The translucent conductive oxide film provided on the second conductivity type layer is handled as constituting part of the translucent plate-like body 101. This conductive oxide film can be formed of ITO, tin oxide, indium oxide, zinc oxide, or the like. The light emitting layer side electrode 103 formed on the conductive oxide film has a portion in contact with the conductive oxide film in the platinum group (Rh, Pt, Pd, Ir, Ru, Os), Ni (nickel), Ti (titanium). ), W (tungsten), Ag (silver), Al (aluminum), or the like. The light emitting layer side pad electrode 103 has a surface layer of Ag (silver), Au (gold), Sn (tin), In (indium), Bi (bismuth), Cu so as to be easily connected to the external electrode. It is preferable to provide a layer made of (copper), Zn (zinc), or the like.

The planar shape of the pad electrodes 102 and 103 is not particularly limited as long as it can be connected to the external electrode, and specifically, a regular polygon such as a regular triangle, a square, a regular pentagon, and a regular hexagon. A preferable shape includes a circular shape and a shape deformed based on these shapes. If the pad electrode has a size and shape that includes a circle having a diameter of 60 μm when viewed in plan, wire bonding and connection with an external electrode using a conductive adhesive or brazing material is possible (however, the bonding device Yield varies depending on performance.)

There is no limitation on the size of the GaN-based LED chip 100, that is, the size of the plate-like body 101.

In a preferred embodiment, a portion of the surface of the plate-like body 101 that is not covered with the pad electrodes 102 and 103 is processed into a concavo-convex shape, thereby promoting light escape from the inside of the plate-like body 101 to the outside. be able to. On the other hand, the surface of the plate-like body 101 in contact with the pad electrodes 102 and 103 has smoothness so that the effective area of the surface of the pad electrode serving as the light absorption surface (the surface facing the plate-like body 101 side) becomes small. Higher is preferred. For this reason, in a preferred embodiment, the pad electrodes 102 and 103 are formed after the surface of the plate-like body 101 is smoothed by polishing (preferably CMP). Specifically, for example, the surface of the plate-like body 101 is smoothed until the arithmetic average roughness Ra becomes 0.02 μm or less, more preferably 0.01 μm or less, and then the pad electrodes 102 and 103 are formed. Therefore, in a preferable manufacturing method, the surface of the plate-like body 101 is first smoothed, the pad electrodes 102 and 103 are formed, and then the processing for making the surface of the plate-like body 101 not covered with the pad electrode into an uneven surface. I do.

In addition, although not shown in FIG. 1, a light-transmissive insulating protective film is formed on the GaN-based LED chip 100 to protect the chip surface except on the surfaces of the pad electrodes 102 and 103. Is desirable. Such an insulating protective film can be formed using a metal oxide such as silicon oxide, aluminum oxide, spinel or zirconium oxide, or a metal nitride such as silicon nitride. In a preferred embodiment, in order to improve the light extraction efficiency of the LED, the surface of the insulating protective film is processed to be an uneven surface.

The GaN-based LED chip 100 can be used for various light emitting devices such as an SMD (surface mount) type LED package, a bullet type lamp, and a chip on board (COB) type unit in which the LED chip is directly mounted on a unit substrate. The GaN-based LED chip 100 may be directly fixed on a mounting substrate such as a substrate, a slag, a lead frame, or a unit substrate, or may be fixed via a submount. In any case, the entire surface of the GaN-based LED chip 100 is covered with a resin or glass as a sealing material so that light is effectively extracted from the inside of the plate-like body 101 to the outside. desired. For example, it is desirable that the narrow material formed between the surface of the bottom surface side of the plate-like body 101 of the GaN-based LED chip 100 and the surface of the mounting substrate is filled with the sealing material. .

Next, a manufacturing example of the GaN-based LED chip 200 shown in FIG. 2 will be described. 2A is a plan view of the GaN-based LED chip 200 as viewed from the conductive substrate side, and FIG. 2B is a cross-sectional view at the position of the XY line in FIG. 2A.

As shown in the cross-sectional view of FIG. 2B, the GaN-based LED chip 200 is formed of Si-doped GaN on an n-type GaN substrate 201-1 via a low-temperature GaN buffer layer (not shown). 5 μm n-type GaN clad layer 201-2, light emitting layer 201-3 with MQW structure in which 10 layers of InGaN well layers and GaN barrier layers are alternately stacked, p-type clad with a thickness of 100 nm made of Mg-doped AlGaN A light-transmitting plate-shaped layer formed by laminating a layer 201-4a, a p-type contact layer 201-4b made of Mg-doped GaN with a thickness of 200 nm, and an ITO film 201-5 with a thickness of about 300 nm as a diffusion electrode in this order. It has a body 201. As shown in FIG. 2A, a TiW layer having a film thickness of 0.05 μm is formed on the surface of the plate-like body 201 on the n-type GaN substrate 201-1 side, that is, on the back surface of the n-type GaN substrate 201-1. Three substrate-side pad electrodes 202 formed by laminating an Au layer having a thickness of 1 μm are formed thereon. The substrate-side pad electrode 202 has a circular planar shape and a diameter of 70 μm. The three substrate-side pad electrodes 202 are arranged at positions corresponding to the three apexes of the equilateral triangle on the back surface of the n-type GaN substrate 201-1. On the other surface of the plate-like body 201, that is, on the ITO film 201-5, a light emitting layer side pad electrode 203 formed by laminating a 1 μm thick Au layer on a 0.05 μm thick TiW layer is formed. Has been. The planar shape of the light emitting layer side pad electrode 203 is circular, and its diameter is 70 μm. Only one light emitting layer side pad electrode 203 is arranged at the center of the ITO film 201-5 having a square planar shape. The planar shape of the plate-like body 201 is a square, and the length of one side thereof is 350 μm. The ratio of the total area of the substrate side pad electrode 202 to the area of the plate-like body 201 is about 9%, and the ratio of the total area of the light emitting layer side pad electrode 203 is about 3%.

The GaN-based LED chip 200 can be manufactured as follows.
First, an n-type GaN substrate 201-1 is prepared, and a low-temperature GaN buffer layer, an n-type cladding layer 201-2, and a light emitting layer 201 are formed thereon using a normal MOVPE method (organic metal compound vapor phase epitaxy). −3, a p-type cladding layer 201-4a and a p-type contact layer 201-4b are sequentially grown and laminated. In place of the MOVPE method, an MBE method (molecular beam epitaxy method), an HVPE method (hydride vapor phase epitaxy method), or the like can be used. After the lamination, the wafer is taken out from the MOVPE apparatus, and the wafer is annealed in a heat treatment furnace to activate Mg added as an impurity to the p-type layer.

An ITO film 201-5 is formed on the entire surface of the wafer on the p-type contact layer 201-4b by using an electron beam evaporation method. Instead of electron beam evaporation, sputtering, reactive sputtering, ion beam assisted evaporation, ion plating, laser ablation, CVD, spraying, spin coating, dipping, etc. may be used. Is possible. Subsequently, a predetermined mask pattern is formed on the ITO film 201-5 by using a photolithography technique, the ITO film is partially removed by wet etching or dry etching, and an element isolation groove is formed in the next process. The surface of the p-type contact layer 201-4b is exposed in the region. Before the patterning, it is desirable to smooth the surface of the ITO film 201-5 by polishing (preferably CMP). After patterning the ITO film, a predetermined mask pattern is further formed on the wafer surface on the ITO film side, and the n-type contact layer 201-2 is formed from the surface of the p-type contact layer 201-4b by RIE (reactive ion etching). An element isolation trench reaching to is formed.

After the element isolation trench is formed, a TiW film and an Au film are stacked on the back surface of the n-type GaN substrate 201-1 by a sputtering method to form a substrate-side pad electrode 202. Further, the light emitting layer side pad electrode 203 is formed on the ITO film 201-5 by the same method. The patterning of the substrate side pad electrode 202 and the light emitting layer side pad electrode 203 can be performed by a lift-off method using a photoresist. Next, an insulating protective film made of silicon oxide is formed by plasma CVD so as to cover a region on the wafer surface on the GaN substrate 201-1 side excluding the surface of the substrate-side pad electrode 202. Further, in the same manner, an insulating protective film made of silicon oxide is formed so as to cover a region on the wafer surface on the side where the light emitting layer side pad electrode 203 is formed, excluding the surface of the light emitting layer side pad electrode 203. .

Finally, a scribe line is formed on the bottom surface of the element isolation groove with a diamond pen, and the wafer is divided by braking to obtain the GaN-based LED chip 200.

The present invention is not limited to the embodiments explicitly described in the present specification, and various modifications can be made without departing from the spirit of the invention.

It is sectional drawing which shows the structure of the GaN-type LED chip which concerns on embodiment of this invention. It is a figure which shows the structure of the GaN-type LED chip concerning embodiment of this invention, FIG.2 (a) is the top view seen from the electroconductive board | substrate side, FIG.2 (b) is XY of FIG.2 (a). It is sectional drawing in the position of a line.

Explanation of symbols

100, 200 GaN LED chip 101, 201 Translucent plate-like body 102, 202 Substrate side pad electrode 103, 203 Light emitting layer side pad electrode

Claims (8)

A translucent plate-like structure including a conductive substrate and a plurality of GaN-based semiconductor layers including a first conductive type layer, a light emitting layer, and a second conductive type layer stacked on one surface of the conductive substrate Equipped with a body,
The plate-like body has a bottom surface and a top surface,
In the GaN-based LED chip having the light emission observation surface on the upper surface side of the plate-like body,
One or more bottom surface side pad electrodes are formed on the bottom surface of the plate-shaped body,
One or more upper surface side pad electrodes are formed on the upper surface of the plate-shaped body,
A first area ratio that is a ratio of the total area of the bottom surface side pad electrode to the area of the plate-like body and a second area ratio that is a ratio of the total area of the upper surface side pad electrode to the area of the plate-like body. , Both are less than 50%,
A GaN-based LED chip characterized by that. The GaN-based LED chip according to claim 1, wherein both the first area ratio and the second area ratio are 30% or less. The GaN-based LED chip according to claim 1 or 2, wherein both the first area ratio and the second area ratio are 20% or less. The GaN-based LED chip according to claim 1, wherein at least the second area ratio is 10% or less. The GaN-based LED chip according to claim 1, wherein each of the first area ratio and the second area ratio is 10% or less. The GaN-based LED chip according to any one of claims 1 to 5, wherein at least the second area ratio is 5% or less. The GaN-based LED chip according to any one of claims 1 to 5, wherein at least the second area ratio is 3% or less. The GaN-based LED chip according to any one of claims 1 to 7, wherein the number of the bottom surface side pad electrodes is 3 to 10.

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