JP4604488B2 - Nitride semiconductor light emitting device and manufacturing method thereof - Google Patents

Description

The present invention relates to a nitride semiconductor device formed by using a semiconductor layer in which nitride semiconductors made of Al _x In _y Ga _1-xy N (0 ≦ x, 0 ≦ y, 0 ≦ x + y <1) are stacked, and its manufacture Regarding the method.

  A light-emitting element using a nitride-based semiconductor such as gallium nitride can emit ultraviolet light, blue light, green light, and the like, has high efficiency and low power consumption, and can be miniaturized and mechanically oscillated. In addition, it has advantages such as long life and high reliability. In particular, light-emitting elements have been widely used in large displays, traffic lights, and backlight light sources for mobile phones.

In a light-emitting element using a nitride-based semiconductor, it is important to increase the light extraction efficiency so that light generated in the active layer can be extracted and used effectively. From such a viewpoint, a light-transmitting conductive film is required as an electrode, and for example, ITO (a composite oxide of In and Sn), SnO ₂ , ZnO, or the like is used (Patent Document 1). Among them, ITO is an oxide conductive material containing tin in indium oxide, and is suitable for a transparent electrode and the like because it has low resistance and high transparency.

  An example of an LED using such a transparent electrode is shown in FIG. The LED has a configuration in which an n-type GaN layer 2, an InGaN light-emitting layer 3, and a p-type GaN layer 4 are sequentially epitaxially grown on a sapphire substrate 1 via a buffer layer. Further, a part of the InGaN light emitting layer 3 and the p-type GaN layer 4 is selectively removed by etching, so that the n-type GaN layer 2 is exposed. An ITO layer is formed as a p-side transparent electrode 5 on the p-type GaN layer 3, and a bonding pad for the p-side electrode 7 is further laminated. An n-side electrode 8 is formed on the n-type GaN layer 2. These electrodes are formed into a film by depositing a metal such as Al. In such a structure, the current injected through the p-side electrode 7 is uniformly diffused by the ITO layer, which is the p-side transparent electrode 5 having good conductivity, without being concentrated at the lower part of the electrode, and p-type GaN. A current is injected from the layer 3 into the n-type GaN layer 2 to emit light. The emitted light is not blocked by the p-side electrode 7 but is transmitted outside the chip through the ITO layer.

  However, forming a metal electrode such as an Al film on such an ITO layer has caused the following problems. That is, when the interface between the ITO layer and the Al film is heated, diffusion occurs and there is a risk of peeling, and stability is difficult to obtain. In addition, it is difficult to form an ohmic junction at the interface between the ITO layer and the Al film, and an electrical barrier is generated, so that the contact resistance is increased, the operating voltage of the element is increased, and the power consumption and the heat generation amount are increased. Arise. The cause of this is not clear, but it is thought that a part of Al is oxidized by the heat of the interface to form aluminum oxide.

Furthermore, the light extraction efficiency is also reduced. This is because the critical angle is as small as 21.9 degrees because the refractive index of GaN is as large as about 2.67. That is, when viewed from the normal line of the main light extraction surface, light incident at an angle larger than the critical angle is trapped without being extracted from the LED chip. For this reason, it is difficult to improve the external quantum efficiency and obtain a larger light emission power.
Japanese Utility Model Publication No. 6-38265 JP 2003-224297 A JP 2003-124517 A JP-A-8-250769 International Publication No. 98/442030 JP-A-10-256602

  The present invention has been made to solve such problems. A main object of the present invention is to provide a nitride semiconductor light emitting device having improved quality by reducing deterioration of an interface between a metal electrode layer and a translucent conductive layer, and a method for manufacturing the same.

In order to achieve the above object, a nitride semiconductor light emitting device according to the present invention includes a first conductivity type nitride semiconductor layer and a second conductivity type provided on the first conductivity type nitride semiconductor layer. A nitride semiconductor light emitting device comprising a nitride semiconductor layer, wherein a translucent conductive layer is provided on the second conductive nitride semiconductor layer, and a part of the translucent conductive layer Is provided with a reflective layer having a reflective film and a translucent film that insulates the reflective film and the translucent conductive layer, and a metal electrode layer is provided on the reflective layer, the metal electrode layer, wherein to contact the direct and the transparent conductive layer in a region not provided the reflective layer, the reflective film comprises Al or Ag, the metal electrode layer, Au, Pt, Pd, Any metal of Rh, Ni, W, Mo, Cr is included .
The transparent conductive layer, zinc, indium, an oxide containing at least one element selected from the group consisting of tin can including.
The translucent conductive layer preferably contains ITO.
Furthermore, it is preferable that the metal electrode layer is provided on substantially the entire surface of the second conductive nitride semiconductor layer.
Furthermore, it is also preferable to provide a plurality of conduction paths by using a region where the reflective layer is not provided as a current conduction path.
On the other hand, a nitride semiconductor light emitting device includes a substrate having a pair of opposing main surfaces, a first conductive nitride semiconductor layer stacked on one main surface of the substrate, and the first conductive nitride. A second conductive nitride semiconductor layer stacked on the oxide semiconductor layer; an active layer formed between the first conductive nitride semiconductor layer and the second conductive nitride semiconductor layer; A metal electrode layer electrically connected to the second conductive nitride semiconductor layer; and a translucent conductive layer formed between the second conductive nitride semiconductor layer and the metal electrode layer. Prepare. In this nitride semiconductor light emitting device, a reflective layer is formed at least partially between the translucent conductive layer and the metal electrode layer.

  In the nitride semiconductor light emitting device, the reflective layer has a multilayer structure having at least an insulating film.

  Further, in the nitride semiconductor light emitting device, the reflective layer includes a metal containing at least one element selected from the group consisting of at least Al, Zn, Ni, Ti, Zr, Hf, Nb, Ta, Si, In, and Sn. It is a multilayer structure having a layer containing an alloy or an oxide thereof or a nitride thereof.

  Furthermore, in the nitride semiconductor light-emitting element, the reflective layer has a reflective film and a translucent film in contact with the reflective film in a multilayer structure, and the translucent film is formed of the translucent conductive layer. Touching.

  Furthermore, in the nitride semiconductor light emitting device, the reflective film is made of a metal film containing Al or Ag, or at least one oxide selected from the group consisting of Si, Ti, Zr, Nb, Ta, and Al, or The dielectric multilayer film is formed by repeatedly laminating at least two selected from nitrides.

  Furthermore, in the nitride semiconductor light emitting device, the translucent film is a translucent insulating film having an insulating property.

  Furthermore, in the nitride semiconductor light emitting device, the translucent film of the reflective layer is made of an oxide containing at least one element selected from the group consisting of Si, Al, Zr, Hf, Ti, Ta, Nb, and Zn. Become.

  Furthermore, in the nitride semiconductor light emitting device, the reflective film is in contact with the metal electrode layer.

  Furthermore, the nitride semiconductor light-emitting element is formed with a pad electrode in contact with the reflective layer and the translucent conductive layer.

  Furthermore, in the nitride semiconductor light emitting device, the translucent conductive layer is formed in contact with the p-type contact layer.

  Furthermore, in the nitride semiconductor light emitting device, the pattern of the reflective layer is a predetermined pattern and is in a block shape.

  Furthermore, in the nitride semiconductor light emitting device, the translucent conductive layer is made of ITO.

  Furthermore, in the nitride semiconductor light emitting device, the film thickness of the translucent conductive layer is 1 μm or less.

  Furthermore, in the nitride semiconductor light emitting device, the metal electrode layer includes a metal of Au, Pt, Pd, Rh, Ni, W, Mo, Cr, or an alloy thereof.

  Furthermore, in the nitride semiconductor light emitting device, the thickness of the reflective layer is 10 angstroms or more.

  Furthermore, in the nitride semiconductor light emitting device, the refractive index of the second conductive nitride semiconductor layer is larger than the refractive index of the translucent conductive layer, and the refractive index of the translucent conductive layer is Greater than the refractive index of the layer.

  Furthermore, the nitride semiconductor light emitting device includes a substrate having a pair of opposing main surfaces, a first conductive nitride semiconductor layer stacked on one main surface of the substrate, and the first conductive nitride. A second conductive nitride semiconductor layer stacked on the oxide semiconductor layer; an active layer formed between the first conductive nitride semiconductor layer and the second conductive nitride semiconductor layer; A metal electrode layer electrically connected to the second conductivity type nitride semiconductor layer. The nitride semiconductor light-emitting element is a nitride semiconductor light-emitting element that can be mounted on a wiring board with the other main surface of the substrate as a main light extraction surface, and the metal electrode layer and the second conductivity type nitride semiconductor layer A translucent conductive layer is formed between the translucent conductive layer and the metal electrode layer, and a reflective layer having at least a reflective film for reflecting light is formed at least partially between the translucent conductive layer and the metal electrode layer. ing.

  The method for manufacturing a nitride semiconductor light emitting device includes a substrate having a pair of opposing main surfaces, a first conductivity type nitride semiconductor layer stacked on one main surface of the substrate, and the first A second conductive type nitride semiconductor layer stacked on the conductive type nitride semiconductor layer; and an activity formed between the first conductive type nitride semiconductor layer and the second conductive type nitride semiconductor layer. Nitride semiconductor light-emitting device comprising a layer and a metal electrode layer electrically connected to the second conductivity type nitride semiconductor layer, and capable of being mounted on a wiring board with the other main surface of the substrate as a main light extraction surface It is a manufacturing method of an element. The method includes: laminating a first conductive nitride semiconductor layer, an active layer, and a second conductive nitride semiconductor layer on a substrate; and on the second conductive nitride semiconductor layer. Forming a translucent conductive layer; forming a reflective layer having at least a reflective film for reflecting light covering at least a part of the translucent conductive layer; on the reflective layer and reflecting Forming a metal electrode layer on a region where the light-transmitting conductive layer not provided with the layer is exposed.

  According to the nitride semiconductor light emitting device and the manufacturing method thereof of the present invention, it is possible to obtain a high quality nitride semiconductor light emitting device by reducing the deterioration of the interface between the metal electrode layer and the translucent conductive layer. This is because in the present invention, the reflective layer is partially formed in a predetermined pattern between the translucent conductive layer and the electrode layer. By interposing the reflective layer, it is difficult for the metal electrode layer to be altered, and it is possible to improve the reliability and electrical characteristics of the semiconductor light emitting element by suppressing the occurrence of peeling and electrical barrier. Also, by providing a reflective layer, the critical angle at the interface between the reflective layer and the translucent conductive layer is reduced, and the reflected light is increased to improve the light extraction efficiency, particularly in flip chip mounting. Can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a nitride semiconductor light emitting device and a manufacturing method thereof for embodying the technical idea of the present invention, and the present invention is a nitride semiconductor light emitting device and a manufacturing method thereof. Is not specified as below.

  Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely explanations. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.

  FIG. 2 is a schematic cross-sectional view of an LED on which a nitride semiconductor light emitting element is mounted. In this figure, an LED chip 9 which is a nitride semiconductor light emitting element is flip-chip mounted on a submount 10 which is one of wiring boards. The flip chip is a mounting method in which the main light extraction surface is the substrate 11 side facing the electrode formation surface, unlike face-up mounting in which the electrode formation surface of the nitride semiconductor layer is the main light extraction surface. Also called.

  In the LED chip 9 of FIG. 2, a buffer layer 12, an n-type nitride semiconductor layer 13, an active layer 14, and a p-type nitride semiconductor layer 15 are sequentially epitaxially grown on a substrate 11, and a light-transmitting conductive layer 17 and a metal electrode are further grown. Layer 40 is laminated. As the crystal growth method, for example, metal-organic chemical vapor deposition (MOCVD), hydride vapor deposition (HVPE), hydride CVD, MBE (molecular beam epitaxy) and the like can be used. Further, examples of the laminated structure of the semiconductor layers include a homo structure having a MIS junction, a PIN junction, and a PN junction, a hetero structure, and a double hetero structure. In addition, each layer may have a superlattice structure, or a single quantum well structure or a multiple quantum well structure in which the active layer 14 is formed in a thin film that produces a quantum effect. In FIG. 2, the reflection layer 31 provided on the translucent conductive layer 17 is not shown.

  Although not shown in detail in FIG. 2, a part of the active layer 14 and the p-type nitride semiconductor layer 15 is selectively removed by etching to expose a part of the n-type nitride semiconductor layer 15. Side pad electrodes are formed. A p-side pad electrode is formed on the p-type nitride semiconductor layer 15 on the same surface side as the n-side electrode. On the pad electrode, a metallized layer (bump 20) for connection with an external electrode or the like is formed. The metallized layer is made of a material such as Ag, Au, Sn, In, Bi, Cu, or Zn. The electrode forming surface side of the LED chip 9 is opposed to a pair of positive and negative external electrodes provided on the submount 10, and each electrode is joined by a bump 20. Further, a wire 21 or the like is wired to the submount 10. On the other hand, the main surface side of the substrate 11 of the LED chip 9 mounted face down is a main light extraction surface.

  In the present specification, the term “upper” as used on a layer or the like is not necessarily limited to the case where the upper surface is formed in contact with the upper surface, but includes the case where the upper surface is formed apart from the upper surface. It is used in the meaning including the case where an intervening layer is present.

  FIG. 3 is a schematic cross-sectional view of the nitride semiconductor light emitting device according to the first embodiment of the present invention. The nitride semiconductor light emitting device shown in the figure is displayed upside down to indicate that it is flip chip mounting. In an actual manufacturing process, each layer is formed on the upper surface of the substrate 11, and the obtained nitride semiconductor light emitting element is mounted upside down as shown in FIG.

[Substrate 11]
The substrate 11 is a translucent substrate on which a nitride semiconductor can be epitaxially grown, and the size and thickness of the substrate are not particularly limited. As this substrate, an insulating substrate such as sapphire or spinel (MgA1 ₂ O ₄ ) whose main surface is any one of C-plane, R-plane, and A-plane, silicon carbide (6H, 4H, 3C), silicon , ZnS, ZnO, Si, GaAs, diamond, and oxide substrates such as lithium niobate and neodymium gallate that are lattice-bonded to a nitride semiconductor. In addition, a nitride semiconductor substrate such as GaN or AlN can be used as long as it is thick enough to allow device processing (several tens of μm or more). The heterogeneous substrate may be off-angle, and when using the sapphire C-plane, the range is 0.01 ° to 3.0 °, preferably 0.05 ° to 0.5 °.

[Nitride semiconductor layer]
As the nitride semiconductor, the general formula _{In x Al y Ga 1-xy} N (0 ≦ x, 0 ≦ y, x + y ≦ 1) A, B and P, may be mixed with As. Further, the n-type nitride semiconductor layer 13 and the p-type nitride semiconductor layer 15 are not particularly limited to a single layer or a multilayer. In addition, the nitride semiconductor layer appropriately contains n-type impurities and p-type impurities. As the n-type impurity, a group IV or group VI element such as Si, Ge, Sn, S, O, Ti, or Zr can be used, preferably Si, Ge, or Sn, and most preferably Si. The p-type impurity is not particularly limited, and examples thereof include Be, Zn, Mn, Cr, Mg, and Ca, and Mg is preferably used. Thereby, each conductivity type nitride semiconductor can be formed. The nitride semiconductor layer has an active layer 14, and the active layer 14 has a single (SQW) or multiple quantum well structure (MQW). Details of the nitride semiconductor are shown below.

The nitride semiconductor grown on the substrate 11 is grown via a buffer layer (not shown in FIG. 3). The buffer layer is a nitride semiconductor represented by the general formula Al _a Ga _1-a N (0 ≦ a ≦ 0.8), more preferably Al _a Ga _1-a N (0 ≦ a ≦ 0.5). The nitride semiconductor shown in FIG. The thickness of the buffer layer is preferably 0.002 to 0.5 μm, more preferably 0.005 to 0.2 μm, and still more preferably 0.01 to 0.02 μm. The growth temperature of the buffer layer is preferably 200 to 900 ° C, more preferably 400 to 800 ° C. Thereby, dislocations and pits on the nitride semiconductor layer can be reduced. Furthermore, an Al _x Ga _1-x N (0 ≦ X ≦ 1) layer may be grown on the above-described dissimilar substrate by an ELO (Epitaxial Lateral Overgrowth) method. The ELO (Epitaxial Lateral Overgrowth) method is to reduce dislocations by bending and converging threading dislocations by laterally growing a nitride semiconductor. The buffer layer may have a multilayer structure, and a low-temperature growth buffer layer and a high-temperature growth layer may be formed thereon. As the high temperature growth layer, undoped GaN or GaN doped with n-type impurities can be used. The film thickness of the high temperature growth layer is 1 μm or more, more preferably 3 μm or more. The growth temperature of the high-temperature growth layer is 900 to 1100 ° C., preferably 1050 ° C. or higher.

Next, the n-type nitride semiconductor layer 13 is grown. First, an n-type contact layer (not shown) is grown. The n-type contact layer has a composition that is larger than the band gap energy of the active layer 14, and is preferably Al _j Ga _1-j N (0 ≦ j <0.3). The thickness of the n-type contact layer is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more. Next, an n-type cladding layer is grown. The n-type cladding layer contains Al, and the n-type impurity concentration is not particularly limited, but is preferably 1 × 10 ¹⁷ to 1 × 10 ²⁰ / cm ³ , more preferably 1 × 10 ¹⁸ to 1. × 10 ¹⁹ / cm ³ Further, the n-type impurity concentration may be inclined. Further, by providing an Al composition gradient, it also functions as a cladding layer for confining carriers.

The active layer 14 functions as a light emitting layer, and includes a well layer made of at least Al _a In _b Ga _1-ab N (0 ≦ a ≦ 1, 0 ≦ b ≦ 1, a + b ≦ 1), Al _c In _d Ga ₁₋ having a quantum well structure including a barrier layer made of _{cd N (0 ≦ c ≦ 1,0} ≦ d ≦ 1, c + d ≦ 1). The nitride semiconductor used for the active layer 14 may be any of non-doped, n-type impurity doped, and p-type impurity doped. Preferably, by using a non-doped or n-type impurity doped nitride semiconductor, the output of the light emitting element can be increased. More preferably, when the well layer is undoped and the barrier layer is n-type impurity doped, the output and the light emission efficiency of the light emitting element can be increased. In addition, by including Al in the well layer used in the light emitting element, a wavelength range that is difficult for a conventional InGaN well layer, specifically, a wavelength near 365 nm, which is the band gap energy of GaN, or a wavelength shorter than that is obtained. be able to. The wavelength of light emitted from the active layer 14 is set to a wavelength of about 360 nm to 650 nm, preferably 380 nm to 560 nm, depending on the purpose and application of the light emitting element.

The thickness of the well layer is preferably 1 nm to 30 nm, more preferably 2 nm to 20 nm, and still more preferably 2 nm to 20 nm. This is because if it is smaller than 1 nm, it does not function well as a well layer, and if it is larger than 30 nm, the crystallinity of the quaternary mixed crystal of InAlGaN deteriorates and the device characteristics deteriorate. In addition, when the thickness is 2 nm or more, there is no significant unevenness in the film thickness, and a relatively uniform film quality layer is obtained. When the thickness is 20 nm or less, the generation of crystal defects is suppressed and crystal growth is possible. Furthermore, the output can be improved by setting the film thickness to 3.5 nm or more. This is because, by increasing the thickness of the well layer, light emission recombination is achieved by high light emission efficiency and internal quantum efficiency for a large number of carrier injections, such as an LD driven by a large current. It has an effect in a quantum well structure. In the single quantum well structure, the effect of improving the output can be obtained by setting the film thickness to 5 nm or more in the same manner as described above. Further, the number of well layers is not particularly limited, but when the number is 4 or more, it is preferable to keep the thickness of the active layer 14 low by setting the thickness of the well layer to 10 nm or less. This is because if the thickness of each layer constituting the active layer 14 is increased, the thickness of the entire active layer 14 is increased, causing an increase in V _f . In the case of a multiple quantum well structure, it is preferable to have at least one well layer having a thickness in the range of 10 nm or less among the plurality of wells, more preferably, all the well layers have a thickness of 10 nm or less. It is.

The barrier layer is preferably doped or undoped with a p-type impurity or an n-type impurity, more preferably doped or undoped with an n-type impurity, as in the case of the well layer. It is. For example, when an n-type impurity is doped in the barrier layer, the concentration needs to be at least 5 × 10 ¹⁶ / cm ³ or more. For example, the LED, preferably 5 × 10 ¹⁶ / cm ³ or more 2 × 10 ¹⁸ / cm ³ or less. In the case of a high-power LED or LD, it is 5 × 10 ¹⁷ / cm ³ or more and 1 × 10 ²⁰ / cm ³ or less, more preferably 1 × 10 ¹⁸ / cm ³ or more and 5 × 10 ¹⁹ / cm ³ or less. In this case, the well layer preferably does not substantially contain n-type impurities or is grown undoped. In addition, when the n-type impurity is doped in the barrier layer, all the barrier layers in the active layer may be doped, or a part may be doped and a part may be undoped. Here, when doping some barrier layers with n-type impurities, it is preferable to dope the barrier layers arranged on the n-type layer side in the active layer. For example, by doping the n- _th barrier layer B _n (n is a positive integer) counting from the n-type layer side, electrons are efficiently injected into the active layer, resulting in excellent luminous efficiency and internal quantum efficiency. A light emitting element having the following can be obtained. The well layer can also be doped into the mth well layer W _m (m is a positive integer) counted from the n-type layer side to obtain the same effect as that of the barrier layer. The same effect can be obtained by doping both the barrier layer and the well layer.

Next, the following plural layers (not shown) are formed as the p-type nitride semiconductor layer 15 on the active layer 14. First, the p-type cladding layer is not particularly limited as long as it has a composition larger than the band gap energy of the active layer 14 and can confine carriers in the active layer 14. For example, Al _k Ga _1-k N (0 ≦ k <1) is used, and Al _k Ga _1-k N (0 <k <0.4) is particularly preferable. The film thickness of the p-type cladding layer is not particularly limited, but is preferably 0.01 to 0.3 μm, more preferably 0.04 to 0.2 μm. The p-type impurity concentration of the p-type cladding layer is 1 × 10 ¹⁸ to 1 × 10 ²¹ / cm ³ , preferably 1 × 10 ^{19 to} 5 × 10 ²⁰ cm ³ . When the p-type impurity concentration is in the above range, the bulk resistance can be reduced without reducing the crystallinity. The p-type cladding layer may be a single layer or a multilayer layer (superlattice structure). In the case of a multilayer film layer, it may be a multilayer film layer composed of the above Al _k Ga _1-k N and a nitride semiconductor layer having a smaller band gap energy. For example, as a layer having a small band gap energy, as in the case of the n-type cladding layer, In _l Ga _1-l N (0 ≦ l <1), Al _m Ga _1-m N (0 ≦ m <1, m > L). In the case of a superlattice structure, the thickness of each layer forming the multilayer layer is preferably 100 mm or less, more preferably 70 mm or less, and further preferably 10 to 40 mm. In addition, when the p-type cladding layer is a multilayer film composed of a layer having a large band gap energy and a layer having a small band gap energy, at least one of the layer having a large band gap energy and the layer having a small band gap energy is doped with a p-type impurity. You may let them. In addition, when doping both a layer having a large band gap energy and a layer having a small band gap energy, the doping amount may be the same or different.

Next, a p-type contact layer is formed on the p-type cladding layer. Al _f Ga _1-f N (0 ≦ f <1) is used for the p-type contact layer, and in particular, an ohmic electrode can be formed by forming Al _f Ga _1-f N (0 ≦ f <0.3). It is possible to make a good ohmic contact with the p electrode. The p-type impurity concentration is preferably 1 × 10 ¹⁷ / cm ³ or more. The p-type contact layer preferably has a high p-type impurity concentration on the conductive substrate side. In this case, the composition gradient may change the composition continuously or may change the composition stepwise in a discontinuous manner. For example, a p-type contact layer is in contact with an ohmic electrode, a first p-type contact layer having a high p-type impurity concentration and a low Al composition ratio, and a second p-type contact having a low p-type impurity concentration and a high Al composition ratio. It can also consist of layers. Good ohmic contact can be obtained by the first p-type contact layer, and self-absorption can be prevented by the second p-type contact layer.

  After the nitride semiconductor is grown on the substrate 11 as described above, the wafer is taken out of the reaction apparatus, and then heat-treated at 450 ° C. or higher in an atmosphere containing oxygen and / or nitrogen. As a result, hydrogen bonded to the p-type layer is removed, and the p-type nitride semiconductor layer 15 exhibiting p-type conductivity is formed.

As the nitride semiconductor layer formed on the substrate, for example, a stacked structure as shown in the following (1) to (4) can be used.
(1) A buffer layer made of GaN having a thickness of 200 mm, an n-type contact layer made of Si-doped n-type GaN having a thickness of 4 μm, and a single quantum well structure made of non-doped In _0.2 Ga _0.8 N having a thickness of 30 mm. A laminated structure comprising an active layer, a p-type cladding layer made of Mg-doped p-type Al _0.1 Ga _0.9 N having a thickness of 0.2 μm, and a p-type contact layer made of Mg-doped p-type GaN having a thickness of 0.5 μm.

(2) A buffer layer made of AlGaN having a thickness of about 100 Å, an undoped GaN layer having a thickness of 1 μm, an n-side contact layer made of GaN containing 4.5 × 10 ¹⁸ / cm ³ of Si having a thickness of 5 μm, An n-side first multilayer film composed of three layers: a lower layer made of undoped GaN, an intermediate layer made of GaN containing 4.5 × 10 ¹⁸ / cm ^{3 of} 300 Å Si, and an upper layer made of 50 Å undoped GaN (total Nitride semiconductor layer made of undoped GaN having a thickness of 3350 mm), 40 mm of nitride semiconductor layer made of undoped GaN and 20 mm of nitride semiconductor layers made of undoped In _0.1 Ga _0.9 N are alternately stacked one by one. N-side second multilayer film layer (total film thickness: 640 mm) having a superlattice structure formed with a film thickness of 40 mm, undoped Ga having a film thickness of 250 mm From consisting barrier layer and the film thickness is more thickness is laminated by six layers alternately an In _0.3 Ga _0.7 consisting of N well layer and the repetition of 30Å has a multiple quantum well structure barrier composed of undoped GaN is formed of 250Å Active layer (total film thickness 1930 mm), nitride semiconductor layer made of Al _0.15 Ga _0.85 N containing 5 × 10 ¹⁹ / cm ³ Mg, and In _0.03 Ga _0.97 N containing Mg 5 × 10 ¹⁹ / cm ³ Nitride semiconductor layers of 25 繰 り 返 し are repeatedly stacked in layers of 5 layers, and a nitride semiconductor layer made of Al _0.15 Ga _0.85 N containing 5 × 10 ¹⁹ / cm ^{3 of} Mg is formed to a thickness of 40 超. A laminated structure comprising a p-side multilayer film layer having a lattice structure (total film thickness 365 mm) and a p-side contact layer made of GaN containing 1 × 10 ²⁰ / cm ³ of Mg having a film thickness of 1200 mm.

(3) Buffer layer, undoped GaN layer, n-side contact layer made of GaN containing 6.0 × 10 ¹⁸ / cm ^{3 of} Si, undoped GaN layer (the above is an n-type nitride semiconductor layer having a total film thickness of 6 nm), Si the 2.0 × 10 ¹⁸ / cm ³ comprising GaN barrier layer and the active layer of the InGaN well layer and a multiple quantum well which is repeated alternately stacked five layers of, 5.0 × the Mg having a thickness of 1300 Å 10 ¹⁸ / A laminated structure made of a p-type nitride semiconductor layer made of GaN containing cm ³ . Further, an InGaN layer may be formed with a thickness of 50 mm between the translucent conductive layer and the p-type nitride semiconductor layer.

(4) Buffer layer, undoped GaN layer, n-side contact layer made of GaN containing 1.3 × 10 ¹⁹ / cm ^{3 of} Si, undoped GaN layer (the above is an n-type nitride semiconductor layer with a total film thickness of 6 nm), Si Active layer (total film thickness of 800 mm) in which 7 layers of GaN barrier layers and InGaN well layers containing 3.0 × 10 ¹⁸ / cm ³ are alternately stacked, and Mg with a film thickness of 1300 mm 2 A laminated structure made of a p-type nitride semiconductor layer made of GaN containing 0.5 × 10 ²⁰ / cm ³ . Further, an InGaN layer may be formed with a thickness of 50 mm between the translucent conductive layer and the p-type nitride semiconductor layer.

[Translucent conductive layer 17]
A translucent conductive layer 17 is formed on the p-type nitride semiconductor layer 15 thus grown. Note that translucency means that the light emission wavelength of the light emitting element can be transmitted, and does not necessarily mean colorless and transparent. The translucent conductive layer 17 preferably contains oxygen in order to obtain ohmic contact. There are various types of translucent conductive layers 17 containing oxygen, and preferably an oxide containing at least one element selected from the group consisting of zinc (Zn), indium (In), and tin (Sn) To do. Specifically, it is desirable to form the translucent conductive layer 17 containing an oxide of Zn, In, Sn, such as ITO, ZnO, In ₂ O ₃ , SnO ₂ , and preferably ITO is used. Alternatively, a metal film formed by sputtering a metal such as Ni with a film thickness of 30 mm or the like to make it transparent may be used. As described above, the conductive layer is formed on almost the entire surface of the exposed p-type semiconductor layer, whereby the current can be uniformly spread over the entire p-type semiconductor layer. Moreover, by providing translucency, the electrode side can be used as a light emission observation surface. In the following example, an example in which an ITO translucent electrode is used as the translucent conductive layer 17 will be described.

  In order to include oxygen atoms in the light-transmitting conductive layer 17, a layer containing oxygen atoms may be formed and then heat-treated in an atmosphere containing oxygen. Alternatively, oxygen atoms can be contained in each layer by reactive sputtering, ion beam assisted vapor deposition, or the like, but heat treatment is most excellent from the standpoint of process ease.

  The thickness of the translucent conductive layer 17 is such that an uneven surface can be formed, and is preferably 1 μm or less, more preferably 100 to 5000 mm. When the film thickness is 1000 mm, ohmic properties are confirmed, and when the film thickness is increased, the annealing temperature tends to increase. Further, it is preferable that the wavelength is approximately an integral multiple of λ / 4 with respect to the wavelength λ of the light emitted from the active layer 14 because the light extraction efficiency is increased.

  An ohmic contact can be made at the interface with the nitride semiconductor layer by interposing the light-transmitting conductive layer 17 without bringing the metal film into contact with the nitride semiconductor layer. In particular, since the p-type nitride semiconductor layer 15 tends to have a high resistance, it is important to reduce the contact resistance with this interface. Furthermore, the light extraction efficiency can be increased by forming a reflective film on the translucent conductive layer 17, and the formation of the reflective layer 31 suppresses deterioration at the interface between the translucent conductive layer and the metal electrode. Therefore, delamination and deterioration of electrical characteristics are suppressed.

[Reflection layer 31]
A reflective layer 31 is partially formed on the surface of the translucent conductive layer 17. Preferably, it is partially formed with a predetermined pattern. The reflective layer 31 has a multilayer structure, and a layer in contact with ITO which is the light-transmitting conductive layer 17 is a light-transmitting film 311.

[Translucent film 311]
The translucent film 311 is an insulating layer, and insulates the reflective film 312 formed on the upper surface of the translucent film 311 and the translucent conductive layer 17. In addition, a region where the reflective layer 31 is not provided is used as a conduction path 32 to efficiently energize the ITO to achieve current diffusion and low resistance. The translucent film 311 alone or in the whole layer has a preferable ohmic connection with ITO, and diffuses the current input to the ITO to the semiconductor layer side. The translucent film 311 has high translucency so that light from the semiconductor light emitting element can be extracted efficiently. Therefore, the light-transmitting film 311 preferably contains oxygen, more preferably an oxide, and further preferably an oxide of at least one element selected from the group consisting of silicon (Si) and Al. Specifically, SiO ₂ , Al ₂ O ₃ or the like is used, and preferably SiO ₂ is used.

  The thickness of the translucent film 311 is not particularly limited, and can be formed with a thickness of several angstroms to several micrometers. In particular, the thickness of the translucent film 311 when provided together with the metal film formed on the upper surface of the translucent film 311 is preferably 100 to 5000 mm.

[Metal film]
A metal film is formed as the reflective film 312 on the upper surface of the translucent film 311. The metal film is at least Al, Ag, W, Pt, Zn, Ni, Pd, Rh, Ru, Os, Ir, Ti, Zr, Hf, V, Nb, Ta, Co, Fe, Mn, Mo, Cr, La A multilayer structure having a layer containing a metal or alloy containing at least one element selected from the group consisting of Cu, Y, or an oxide thereof. In particular, the metal film formed on the upper surface of the translucent film 311 preferably uses Al or Ag. The translucent film 311 is formed integrally with a metal film formed on the upper surface thereof. The reflective layer 31 is, for example SiO ₂ / Al / W, and a laminated structure of SiO ₂ / Al / W / Pt or consists of W only like.

[Dielectric multilayer film]
A dielectric multilayer film may be formed on the upper surface of the translucent film 311 instead of the metal film as the reflective film 312. The dielectric multilayer film is a dielectric multilayer film in which at least two selected from at least one oxide or nitride selected from the group consisting of Si, Ti, Zr, Nb, Ta, and Al are repeatedly stacked. In this case, the reflective layer 31 is composed of, for example, a laminated structure of (SiO ₂ / TiO ₂ ) _n (where n is a natural number).

[Pad electrode]
After the reflective layer 31 is formed on the translucent conductive layer, a pad electrode is formed as the metal electrode layer 40 thereon. As for the pad electrode, a conductive wire is wire-bonded to the surface, and electrical connection between the light emitting element and the external electrode can be achieved. Alternatively, a conductive member such as an Au bump can be disposed on the surface of the pad electrode, and an electrical connection between the electrode of the light-emitting element and the external electrode opposed via the conductive member can be achieved. In addition, the pad electrode is partly in direct contact with the translucent conductive layer, so that a current can flow uniformly through the translucent conductive film. An existing configuration can be appropriately employed for the pad electrode. For example, it is made of any metal of Au, Pt, Pd, Rh, Ni, W, Mo, Cr, an alloy thereof, or a combination thereof. In the example of FIG. 3, the pad electrode has a laminated structure of W / Pt / Au, Rh / Pt / Au, W / Pt / Au / Ni, or Pt / Au from the bottom surface.

  In the present embodiment, the pad electrode includes the translucent conductive layer 17 provided on one nitride semiconductor layer side and the other on the p-type nitride semiconductor layer 15 side and the n-type nitride semiconductor layer 13 side. It is formed for the nitride semiconductor layer. In addition, a part of the pad electrode in another embodiment according to the present invention extends directly into the through-hole provided in the translucent conductive layer 17 and is provided directly on the nitride semiconductor layer, or the translucent conductive layer. The outer peripheral edge 17 may be provided directly on the nitride semiconductor layer. In this manner, part of the pad electrode is directly provided on the nitride semiconductor layer, whereby peeling of the pad electrode can be prevented.

  A conductive member such as an Au bump can be arranged on the surface of the pad electrode, and an electrical connection between the electrode of the light emitting element and the external electrode opposed via the conductive member can be achieved.

  The pad electrodes formed on the p-type nitride semiconductor layer 15 side and the n-type nitride semiconductor layer 13 side preferably have the same type of metal and film thickness. By adopting the same configuration as described above, the pad electrode can be formed simultaneously on the p-type nitride semiconductor layer 15 side and the n-type nitride semiconductor layer 13 side. Compared with the case of separately forming the type nitride semiconductor layer 13 side, the process of forming the pad electrode can be simplified. As a pad electrode in the present embodiment, for example, a W / Pt / Au electrode in which W, Pt, and Au are sequentially laminated from the p-type nitride semiconductor layer 15 or the n-type nitride semiconductor layer 13 side by sputtering (there are As the film thickness, for example, 20/200 nm / 500 nm, respectively, or W / Pt / Au / Ni in which Ni is further laminated, or Ti / Rh / Pt in which Ti, Rh, Pt, and Au are sequentially laminated by sputtering. / Au electrode or the like can be used. By making the uppermost layer of the pad electrode Au, the pad electrode can be satisfactorily connected to a conductive wire mainly composed of Au. Also, by stacking Pt between Rh and Au, diffusion of Au or Rh can be prevented. Rh is excellent in light reflectivity and barrier properties, and can be suitably used because light extraction efficiency is improved.

[Formation pattern of the reflective layer 31]
Any pattern can be used as the pattern for forming the reflective layer 31. These patterns are formed on the resist pattern by a method such as RlE (reactive ion etching), ion milling or lift-off. A preferable pattern is a dot shape as shown in the plan view of FIG. 4 or a block shape as shown in FIG. In the translucent conductive layer shown in FIG. 4, the reflective layer 31 is patterned in a dot shape. On the other hand, in the example shown in FIG. 5, the reflective layer 31 is patterned in a block shape. Moreover, the area | region shown with a broken line in these figures has shown the opening parts 51 and 52 of the insulating protective film 50 shown in FIG. Reference numeral 51 denotes an opening of the n-type electrode portion, and 52 denotes an opening of the p-type electrode portion. In this way, the reflective film 312 is not provided on the entire surface of the ITO, and the ITO is partially exposed to be in contact with the pad electrode, so that this region becomes the conduction path 32 as shown in FIG. Thus, the current flows while avoiding the high electrical barrier region, so that the contact resistance can be substantially reduced and the forward voltage can be lowered. The formation pattern of the reflective layer 31 is not limited to the examples of FIGS. 4 and 5 described above. For example, the dot shape may be a circle, an ellipse, a rectangle, a polygon, or the like. It may be changed, or may be a triangular shape, a circular shape, a semi-circular shape, a polygonal shape as well as a rectangular shape, or a staggered shape. Moreover, it is not restricted to the example arrange | positioned uniformly to the whole, A magnitude | size and a density can be changed suitably for every area | region, or said pattern can also be combined.

In addition, by providing the reflective layer on the translucent conductive layer, it is possible to reduce the critical angle at the interface, increase the total reflection region, and improve the light extraction efficiency. This will be described with reference to FIG. FIG. 7 illustrates the total reflection region at the interface between the ITO layer and the semiconductor layer and between the ITO layer and the insulating layer. As shown in FIG. 7A, at the interface between the GaN layer and the ITO layer, assuming that the refractive index n = 2.5 of the GaN layer and the refractive index n = 2.0 of the ITO layer, the critical angle is obtained from Snell's law. On the other hand, θ = 53 °. On the other hand, as shown in FIG. 7B, at the interface between the ITO layer and the SiO ₂ layer, the refractive index n = 2.0 of the ITO layer and the refractive index of the SiO ₂ layer. If n = 1.48, the critical angle θ = 48 °, and the critical angle can be reduced. As described above, when the reflective layer is formed on the translucent conductive layer, the total reflection region at the interface becomes wide, and more light can be extracted.

  There is also a problem that light extraction efficiency deteriorates due to light absorption at the interface. As shown in FIG. 8A, when the nitride semiconductor layer 23 such as GaN and the reflective film of the metal film 24 are directly joined without passing through the translucent conductive layer 17, light is transmitted at the interface 25 with the metal film. Absorption occurs and light that can be extracted effectively is lost. Although the absorption rate varies depending on the material, it is about 10% in the case of Al and GaN. On the other hand, as shown in FIG. 8B, by interposing a translucent conductive layer 17 such as ITO, light absorption is suppressed at the interface 26 with the nitride semiconductor, and the reflective film of the metal film 24 The absorption of light at the interface 27 can also be suppressed, and the light that can be effectively used can be increased to improve the light extraction efficiency and the external quantum efficiency to increase the light emission output. In addition to this, for example, by making the interface an uneven surface, more light can be extracted to the outside, and the output is further improved.

[Reflection film 312]
In the case of producing a nitride semiconductor light emitting device for flip chip mounting, a reflective layer 31 is partially formed on the translucent conductive layer 17 formed as described above, as shown in FIG. The reflective layer 31 is configured by stacking a translucent film 311 and a reflective film 312. The translucent film 311 is an insulating layer as described above. The reflective film 312 can be formed of a metal film, for example. The metal film is preferably partially oxidized in order to satisfactorily connect to the translucent conductive layer 17 containing oxygen. Thus, by connecting the reflective film 312 of the metal film to the nitride semiconductor layer through the light-transmitting conductive layer 17, the light-transmitting conductive layer 17 can make a good ohmic connection with the semiconductor layer.

  In addition, when a metal film and a nitride semiconductor are directly bonded, the yield is reduced due to the problem that impurities are diffused from the metal film into the nitride semiconductor layer and contaminated, or the bonding property at the interface is poor and peeling occurs. There are things to do. When an oxide film is interposed therebetween, the oxide film serves as a protective film to prevent diffusion.

  The metal film is made of a material capable of forming a thin film having high reflectivity and serving as an electrode of a p-type nitride semiconductor. Especially aluminum (Al), silver (Ag), zinc (Zn), nickel (Ni), platinum (Pt) palladium (Pd), rhodium (Rh), ruthenium (Ru), osmium (Os), iridium (Ir) titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), cobalt (Co), iron (Fe), manganese (Mn), molybdenum (Mo), chromium A metal or alloy containing at least one element selected from the group consisting of (Cr), tungsten (W), lanthanum (La), copper (Cu), and yttrium (Y) is preferable. In particular, Al and Ag are preferable from the viewpoint of reflectance and life characteristics. Al can have a reflectance of 90% or more. As a result, the light-emitting element made of a nitride semiconductor has little absorption at a wavelength of about 360 nm to 650 nm, preferably 380 nm to 560 nm. Further, the metal film layer may have a metal laminated structure listed above. In the case of a laminated structure, the electrode may be processed later by thermal annealing so that the electrode material is naturally integrated in the metal film and alloyed.

  The translucent conductive layer 17 and the reflective film 312 may have a multilayer structure. For example, extraction of light from the light-emitting element can be improved by making the refractive index of the second layer located on the semiconductor layer side in a multilayer structure stepwise smaller than the refractive index of the first layer. The reflective film 312 can also be made of a dielectric. The dielectric is preferably a laminated structure of oxides. Since oxides are chemically more stable than metals, they can be used more reliably than metal film reflective films. Further, the reflectance can be set to a value close to 100%, and the loss due to light absorption in the reflective film can be extremely reduced.

  In the nitride semiconductor light emitting device in the present embodiment, translucent conductive layer 17 and reflective layer 31 are provided for the p-type layer, but in other embodiments, the translucent conductive layer is provided for the n-type layer. Needless to say, the layer 17 or the like may be provided. For example, the light may be mainly extracted from the n-type layer side, and an uneven surface may be formed on the n-layer pad electrode, and a reflective film may be provided.

  When an LED or a laser is produced as a light emitting element, it is generally formed by growing each semiconductor layer on a specific substrate. At that time, an insulating substrate such as sapphire is used as the substrate, and the insulating substrate is used. When not finally removed, both the p-electrode and the n-electrode are usually formed on the same surface side on the semiconductor layer. As a result, flip-chip mounting is realized in which the insulating substrate side is disposed on the viewing side and the emitted light is extracted from the substrate side. Of course, it is also possible to perform flip-chip mounting after finally removing the substrate. Thus, the light extraction efficiency can be improved, the external quantum efficiency can be improved, and a larger light emission power can be obtained.

  In the above example, the example of flip chip mounting has been described. However, the present invention can also be used face up. In the case of mounting face up, the output light is emitted from the electrode forming surface instead of the substrate side, so that no reflection film is required.

Examples according to the present invention will be described in detail below. An LED is produced as a semiconductor light emitting device having the configuration shown in FIG. First, using a MOVPE reactor, on a 2 inch φ sapphire substrate 11, a buffer layer made of GaN is 200 Å, an n-type contact layer made of Si-doped n-type GaN is 4 μm, and a single layer made of non-doped In _0.2 Ga _0.8 N is used. The active layer 14 having a single quantum well structure is 30 Å, the p-type cladding layer made of Mg-doped p-type Al _0.1 Ga _0.9 N is 0.2 μm, and the p-type contact layer made of Mg-doped p-type GaN is 0.5 μm. Grow in order.

  Further, the p-type nitride semiconductor layer 15 is further reduced in resistance by annealing the wafer in a reaction vessel in a nitrogen atmosphere at a temperature of 600 ° C. After annealing, the wafer is taken out of the reaction vessel, a mask having a predetermined shape is formed on the surface of the uppermost p-type GaN, and etching is performed from above the mask with an etching apparatus. As shown in FIG. Expose part.

  Next, the mask on the p-type nitride semiconductor layer 15 is removed, and ITO is sputtered as a light-transmissive conductive layer 17 to a thickness of 4000 mm on almost the entire surface of the uppermost p-type GaN. The light-transmitting conductive layer 17 after sputtering was clearly light-transmitting and could be observed through the sapphire substrate 11. As described above, the light-transmitting conductive layer 17 is formed on almost the entire surface of the exposed p-type nitride semiconductor layer 15, so that the current can be uniformly spread over the entire p-type nitride semiconductor layer 15. ITO is sputtered at 300 ° C., but when sputtered at room temperature, it may be annealed after the formation.

Further, a SiO ₂ film having a thickness of 100 mm is formed thereon as a light-transmitting insulating film of the reflective layer 31 by sputtering. Subsequently, Al is formed as a metal film with a film thickness of 2000 mm, and subsequently, W is formed with a film thickness of 2000 angstroms. The laminated structure of SiO ₂ / Al / W was patterned into dots as shown in FIG.

  After the reflective layer 31 is formed by patterning, a pad electrode having a laminated structure of W / Pt / Au is formed with a film thickness of 7000 mm on almost the entire surface of the p-type semiconductor layer. This pad electrode is not translucent.

  After forming the pad electrode, an n-electrode containing W / Pt / Au is formed on the exposed n-type semiconductor layer with a film thickness of 7000 mm, and finally heat-treated at 400 ° C. or higher with an annealing apparatus to alloy the electrode Let

  The wafer having the electrodes formed on the n-type contact layer and the p-type contact layer as described above is cut into a 350 μm square chip and flip-chip mounted on the submount 10 as shown in FIG.

  As described above, by forming a nitride semiconductor light emitting element on a mounting substrate by flip chip, a plurality of nitride semiconductor light emitting elements can be mounted at the same potential, and the nitride semiconductor light emitting device can be mounted rather than mounted face up. Can be miniaturized. In particular, in the face-up mounting, the light emitting area is reduced because it is necessary to provide a pad electrode, but in the flip chip mounting, the entire back surface side of the substrate 11 can be a light emitting surface, and light can be emitted in a wide area. Further, by using a eutectic alloy for bonding, a relatively large light emitting area can be obtained even if the size is reduced. In addition, by adjusting the film thickness of the light-transmitting conductive layer 17 and the reflective film 312, the light emitting surface of the element can be easily made horizontal or inclined from the horizontal.

  The nitride semiconductor light emitting device of the present invention is a light emitting diode (LED), a laser diode (LD) or the like, for example, a full color LED display, an LED traffic light, an LED device such as a road information display board, or a light receiving device such as a solar cell or an optical sensor. As an image scanner, etc., or as an electronic device (transistor such as a FET or power device), a light source for an optical disk using these, a medium such as a DVD for storing a large amount of information, a light source for communication, printing It can be suitably used for devices, light sources for illumination, and the like.

It is a schematic sectional drawing which shows an example of LED using the conventional transparent electrode. It is a schematic sectional drawing which shows LED which carried out the flip chip mounting of the nitride semiconductor light-emitting device. 1 is a schematic cross-sectional view showing a nitride semiconductor light emitting device according to a first embodiment of the present invention. It is a schematic plan view which shows an example which provided the reflection layer in the upper surface of the translucent conductive layer. It is a schematic plan view which shows the other example which provided the reflection layer in the upper surface of the translucent conductive layer. It is explanatory drawing which shows the path | route through which an electric current flows from a pad electrode. It is explanatory drawing which shows the total reflection area | region in the interface of an ITO layer and a semiconductor layer, and an ITO layer and an insulating layer. It is explanatory drawing which shows the change of the light absorption by interposing a translucent conductive layer between the nitride semiconductor layer and the reflective film of a metal film.

DESCRIPTION OF SYMBOLS 1 ... Sapphire substrate 2 ... n-type GaN layer 3 ... InGaN light emitting layer 4 ... p-type GaN layer 5 ... p-side transparent electrode 7 ... p-side electrode 8 ... n-side electrode 9 ... LED chip 10 ... submount 11 ... substrate 12 ... Buffer layer 13 ... n-type nitride semiconductor layer 14 ... active layer 15 ... p-type nitride semiconductor layer 17 ... translucent conductive layer 20 ... bump 21 ... wire 23 ... nitride semiconductor layer 24 ... metal film 25 ... nitride semiconductor Interface between layer and metal film 26 ... Interface between nitride semiconductor layer and translucent conductive layer 27 ... Interface between translucent conductive layer and metal film 31 ... Reflective layer 311 ... Translucent film 312 ... Reflective film 32 ... Conduction path 35 ... P-type contact layer 40 ... Metal electrode layer 50 ... Insulating protective film 51, 52 ... Protective film opening

Claims (5)

A first conductivity type nitride semiconductor layer;
A second conductive nitride semiconductor layer provided on the first conductive nitride semiconductor layer;
A nitride semiconductor light emitting device comprising:
A translucent conductive layer (17) is provided on the second conductive nitride semiconductor layer,
In part on the translucent conductive layer (17),
A reflective film (312),
A translucent film (311) for insulating the reflective film (312) and the translucent conductive layer (17);
A reflective layer (31) having
On the reflective layer (31), a metal electrode layer (40) is provided,
The metal electrode layer (40) to contact the direct and the transparent conductive layer in a region not provided the reflective layer (31) (17),
The reflective film (312) contains Al or Ag,
The nitride semiconductor light emitting device, wherein the metal electrode layer (40) includes any one of Au, Pt, Pd, Rh, Ni, W, Mo, and Cr . The translucent conductive layer (17), zinc, indium, nitride semiconductor light emitting device according to claim 1, an oxide containing at least one element selected from the group consisting of tin, characterized in including that .   The nitride semiconductor light emitting element according to claim 2, wherein the translucent conductive layer (17) contains ITO.   4. The nitride semiconductor light emitting device according to claim 1, wherein the metal electrode layer is provided on substantially the entire surface of the second conductive nitride semiconductor layer. 5. .   The region where the reflective layer (31) is not provided is defined as a current conduction path (32), and a plurality of the conduction paths (32) are provided. Nitride semiconductor light emitting device.

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