JP4899825B2 - Semiconductor light emitting device, light emitting device - Google Patents

Description

The present invention relates to a semiconductor light emitting device, the semiconductor light-emitting device having a particularly pad electrode, relates to a light-emitting device.

  Nitride-based compound semiconductor light-emitting elements emit light of a bright color that is small and power efficient. In addition, a light emitting element which is a semiconductor element does not have a concern about a broken ball. Further, it has excellent initial driving characteristics and is strong against vibration and repeated on / off lighting. Because of such excellent characteristics, semiconductor light emitting devices such as light emitting diodes (LEDs) and laser diodes (LDs) are used as various light sources. In particular, in recent years, as a light source for illumination replacing a fluorescent lamp, attention has been attracted as next-generation illumination with lower power consumption and longer life, and further improvement in light emission output and improvement in light emission efficiency are required.

  The semiconductor light emitting device has a pad electrode for electrically connecting to an external electrode, such as a wire for wire bonding or a bump for flip chip. An example of a conventional GaN-based compound semiconductor light emitting device having such a pad electrode is shown in the cross-sectional view of FIG. A GaN-based compound semiconductor element 70 shown in this figure includes an n-type semiconductor layer 72 grown on a sapphire substrate 71, a light emitting layer 73, a p-type semiconductor layer 74, a transparent electrode 75, a p-side pad electrode 76, N-side pad electrode 77. Since the n-side pad electrode 77 is connected to the lower side of the pn junction, the n-type semiconductor layer 72 is exposed by cutting out a part of the light emitting surface. The surface is covered with a protective film 78. Further, bonding wires (not shown) are connected on the pad electrodes 76 and 77.

  In this GaN-based compound semiconductor element 70, current flows well under the p-side pad electrode 76 due to its structure, so that current is injected from this portion to the light emitting layer 73 side, and becomes a portion that emits light best. However, there is a problem in that light emitted from the lower surface, that is, the light emitting layer 73 is absorbed by the metal constituting the transparent electrode 75 located immediately below the p-side pad electrode 76. For this reason, the current injected into the lower surface of the p-side pad electrode 76 does not contribute to light emission, but from the viewpoint of light emission efficiency, the current injection under the p-side pad electrode 76 is suppressed to suppress light emission. It has been adopted.

For example, in the GaN-based compound semiconductor device 80 shown in FIG. 12 and FIG. 13, an insulating film 82 made of SiO ₂ is provided under the p-side pad electrode 81 to prevent energization in this portion, thereby providing a non-light emitting surface ( Patent Document 1). With this configuration, the current of the p-side pad electrode 81 is circulated so as to flow outside the electrode, not directly under the electrode, the current flowing directly under the p-side pad electrode 81 is eliminated, and this region is made non-light emitting. As a result, the light extraction efficiency as a whole is improved.
JP-A-8-250769 JP 2003-124517 A JP 2005-197289 A

  However, in the above configuration, since current is applied so as to be unevenly distributed around the p-side pad electrode, there is a problem in that local degradation occurs and, consequently, the life of the element is adversely affected. On the other hand, further improvement of light extraction efficiency as light source for illumination, higher output, and higher efficiency are required.

The present invention has been made in view of such a situation. One object of the present invention is to efficiently extract light absorbed at the interface between a semiconductor layer and a light-transmitting conductive layer or a pad electrode to the outside, thereby providing a semiconductor light emitting device with high efficiency and high light extraction efficiency, The object is to provide a light emitting device.

Means for Solving the Problems and Effects of the Invention

In order to achieve the above object, a first semiconductor light emitting element is formed on a light emitting layer, a light emitting layer formed on at least part of the first conductive semiconductor layer, and a light emitting layer. A second conductive type semiconductor layer formed thereon, a translucent insulating layer formed on at least a part of the second conductive type semiconductor layer, and a second conductive formed on at least a part of the translucent insulating layer. A semiconductor light emitting device comprising a mold pad electrode, and further, an intervening region interposed at an interface between the light transmissive insulating layer and the second conductive type semiconductor layer, and a light transmissive property on the second conductive type semiconductor layer A light-transmitting conductive layer having a covering region that covers a region excluding a portion provided with an insulating layer, the layer thickness of the intervening region is configured to be thinner than the layer thickness of the covering region , The refractive index is lower than that of the second conductivity type semiconductor layer, and between the second conductivity type semiconductor layer and the translucent insulating layer. The thickness of the light-transmitting conductive layer is approximately (λ / 4n) or less with respect to the wavelength λ of light of the light-emitting element and the refractive index n of the light-transmitting conductive layer, and is on the second conductive type semiconductor layer. The thickness of the light-transmitting conductive layer in the covering region covering the region excluding the light-transmitting insulating layer is (λ / 4n) with respect to the wavelength λ of light of the light-emitting element and the refractive index n of the light-transmitting conductive layer. The light-transmitting conductive layer on the lower surface of the light-transmitting insulating layer can be a current injection region . Thereby, the sheet resistance can be reduced by making the cross-sectional area in the covering region of the translucent conductive layer larger than the intervening region, the light emission around the second conductivity type pad electrode can be increased, and the light emission directly under the pad electrode can be performed. In addition, since the covering regions are connected without being divided by the intervening region, the current can be uniformly distributed to improve the light extraction efficiency.

The second semiconductor light emitting element includes a first conductive type semiconductor layer, a light emitting layer formed on at least a part of the first conductive type semiconductor layer, and a second conductive type semiconductor formed on the light emitting layer. A light-transmitting insulating layer formed on at least part of the second conductive semiconductor layer, a second conductive pad electrode formed on at least part of the light-transmitting insulating layer, and second conductive A covering region covering substantially the entire surface of the type semiconductor layer, a first intervening region partially interposed between the second conductive type semiconductor layer and the light-transmitting insulating layer continuously with the covering region, and a light-transmitting property and a transparent conductive layer that have a second intermediate region interposed at the interface between the second conductivity-type pad electrode by covering the upper surface from the surrounding insulating layer, the layer thickness of the first intermediate region, covering It is configured thinner than the thickness of the region, a low refractive index of the translucent insulating layer than the second conductive type semiconductor layer, and the second conductivity type The thickness of the light-transmitting conductive layer interposed between the conductor layer and the light-transmitting insulating layer is approximately (λ / 4n) with respect to the light wavelength λ of the light-emitting element and the refractive index n of the light-transmitting conductive layer. ), And the thickness of the light-transmitting conductive layer in the covering region covering the region excluding the light-transmitting insulating layer on the second conductive type semiconductor layer is the light wavelength λ of the light-emitting element, the light-transmitting conductivity The light-transmitting conductive layer on the lower surface of the light-transmitting insulating layer, which is larger than (λ / 4n) with respect to the refractive index n of the layer, can be used as the current injection region . As a result, the layer thickness of the translucent electrode in the region other than the translucent insulating layer is made thicker than the thickness of the translucent conductive layer immediately below the translucent insulating layer, and the resistivity is relatively lowered. The light emission efficiency can be improved by passing a current efficiently around the light-transmitting insulating layer.

A semiconductor light emitting device according to an embodiment includes a first conductive type semiconductor layer, a light emitting layer formed on at least a part of the first conductive type semiconductor layer, and a second conductive type formed on the light emitting layer. A type semiconductor layer, a translucent insulating layer formed on at least a part of the second conductive type semiconductor layer, a second conductive type pad electrode formed on at least a part of the translucent insulating layer, A first light-transmitting conductive layer that covers a substantially entire surface of the second conductivity-type semiconductor layer and includes a first intervening region partially interposed between the second conductivity-type semiconductor layer and the light-transmitting insulating layer; A second covering region covering a region excluding the light-transmitting insulating layer on the first light-transmitting conductive layer; and covering the upper surface from the periphery of the light-transmitting insulating layer continuously with the second covering region. And a second translucent conductive layer having a second intervening region interposed at the interface with the second conductivity type pad electrode. As a result, the layer thickness of the translucent electrode in the region other than the translucent insulating layer is made thicker than the thickness of the translucent conductive layer immediately below the translucent insulating layer, and the resistivity is relatively lowered. The light emission efficiency can be improved by passing a current efficiently around the light-transmitting insulating layer.

The semiconductor light-emitting device according to one embodiment has a light-transmitting insulating layer having a refractive index lower than that of the second conductive semiconductor layer and interposed between the second conductive semiconductor layer and the light-transmitting insulating layer. The layer thickness of the photoconductive layer can be approximately (λ / 4n) or less with respect to the wavelength λ of light of the light emitting element and the refractive index n of the first translucent conductive layer. As a result, the layer thickness of the first intervening region is set to a layer thickness that does not allow light to be felt, and the interface between the first intervening region and the second conductive semiconductor layer is substantially set between the translucent insulating layer and the second conductive type. The total reflection angle due to the difference in refractive index as the interface with the semiconductor layer can be made wider, total reflection can be easily generated, light absorption by the p-side pad electrode positioned above can be reduced, and light extraction efficiency can be improved. On the other hand, in the region excluding the light-transmitting insulating layer, the light-transmitting conductive layer is formed with a thicker film than the intervening region, and suitable light extraction can be performed in this region.

In the semiconductor light-emitting device according to one embodiment , the thickness of the light-transmitting conductive layer in the covering region covering the region excluding the light-transmitting insulating layer on the second conductive type semiconductor layer is the wavelength of light of the light-emitting device. λ can be larger than (λ / 4n) with respect to the refractive index n of the first translucent conductive layer. Thereby, in the area other than the pad, the light emission of the element can be efficiently extracted outside. In particular, when the refractive index n of the first translucent conductive layer is n ₂ , the refractive index of the second conductive semiconductor layer is n ₁ , and the refractive index of the translucent insulating layer is n ₃ , n ₂ ≧ n _1, or _{| n 1 -n 2 | <|} n 1 -n 3 | when the is effective. Further, from the second conductive type semiconductor layer, a low refractive index light-transmitting insulating layer is located close to the intervening region with the pad, and a low refractive index sealing member and the atmosphere are arranged far away from the other region than the pad. Thus, it is possible to efficiently realize reflection at the interface between the insulating layer and the semiconductor layer in the pad region, and light extraction to the outside of the element in the region other than the pad.

In the semiconductor light emitting device according to one embodiment, the light-transmitting conductive layer on the lower surface of the light-transmitting insulating layer can be used as a current injection region. This allows current to flow evenly by injecting current into the bottom surface of the second conductivity type pad electrode, which was previously non-light-emitting, and avoids local concentration of current to reduce deterioration and improve reliability. it can. Further, it is possible to increase the light emission amount and contribute to the improvement of the light emission output and the extraction efficiency as a whole. In the element structure in which the second conductivity type electrode is reflective and the semiconductor layer side is the light extraction side, the output can be improved by making the region under the pad electrode a light emitting region.

In the third semiconductor light emitting device, the contact resistance at the interface between the second conductive semiconductor layer and the translucent conductive layer covers the surface of the second conductive semiconductor layer from the region where the translucent insulating layer is formed. The area can be lowered. Accordingly, current injection at this interface is inhibited, and the current from the second conductivity type pad electrode can be efficiently flowed around the translucent insulating layer to improve the light emission efficiency as a whole.

In the semiconductor light-emitting element according to one embodiment , the total thickness of the first light-transmitting conductive layer and the second light-transmitting conductive layer can be 100 nm or less. Thereby, loss of light propagating through the translucent conductive layer can be reduced, and light extraction efficiency can be increased.

In the fourth semiconductor light emitting device, the second conductivity type layer is a nitride semiconductor layer, and the refractive index of the translucent insulating layer can be 2.46 or less. Thereby, a suitable light reflection interface can be formed between the nitride semiconductor layer and the translucent insulating layer.

In the semiconductor light-emitting element according to one embodiment , the first light-transmitting conductive layer and the second light-transmitting conductive layer can be formed using an oxide material containing In and Sn. As a result, an interface between the nitride semiconductor layer, the translucent conductive layer having a small refractive index difference, and the semiconductor layer can be formed, and an effect of improving light extraction in a region other than the pad electrode can be obtained.

The fifth semiconductor light emitting device can be configured such that the second conductivity type pad electrode enters the translucent insulating layer when viewed from above. Accordingly, since the pad electrode is not extended outside the translucent insulating layer within the electrode formation surface, there is no light absorption at the interface between the electrode and the semiconductor by the extended portion, and light loss can be suppressed.

A semiconductor light emitting device according to an embodiment is formed on a substrate, an n-type semiconductor layer formed on the substrate so as to be partially exposed, and at least a portion on the n-type semiconductor layer. A light-emitting layer, a p-type semiconductor layer formed on the light-emitting layer, a light-transmitting insulating layer formed on the p-type semiconductor layer, and a p-side formed on at least a part of the light-transmitting insulating layer A first translucent conductive layer that includes a pad electrode and a first intervening region that covers substantially the entire surface of the p-type semiconductor layer and a portion of which is interposed between the p-type semiconductor layer and the translucent insulating layer; A second covering region covering a region excluding the light-transmitting insulating layer on the first light-transmitting conductive layer; and covering the upper surface from the periphery of the light-transmitting insulating layer continuously with the second covering region. and a second translucent conductive layer having a second intervening region interposed at the interface with the p-type semiconductor layer. As a result, the layer thickness of the translucent electrode in the region other than the translucent insulating layer is made thicker than the thickness of the translucent conductive layer immediately below the translucent insulating layer, and the resistivity is relatively lowered. The current can be efficiently passed around the translucent insulating layer to suppress the light emission directly under the p-side pad electrode, and the overall light emission efficiency can be improved.

The sixth light-emitting device is a light-emitting device including a semiconductor light-emitting element and a wavelength conversion member that converts the wavelength of light emitted from the semiconductor light-emitting element, and the semiconductor light-emitting element can be configured as described above.

A method for manufacturing a semiconductor light emitting device according to an embodiment includes a substrate, an n-type semiconductor layer formed on the substrate and partially exposed, and at least a portion on the n-type semiconductor layer. A light-emitting layer formed on the light-emitting layer, a p-type semiconductor layer formed on the light-emitting layer, a light-transmitting insulating layer formed on the p-type semiconductor layer, and at least part of the light-transmitting insulating layer A method for manufacturing a semiconductor light emitting device having a p-side pad electrode, comprising: sequentially stacking an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer on a substrate; Etching step so as to be exposed, forming a first light-transmitting conductive layer on substantially the entire surface in contact with the p-type semiconductor layer, and p-side pad electrode on the first light-transmitting conductive layer Forming a translucent insulating layer at a position where the first translucent conductive layer and the translucent insulating layer are formed. Forming a second light-transmitting conductive layer on the surface and performing a heat treatment to obtain ohmic contact; and p having a substantially equal area on the upper surface of the second light-transmitting conductive layer on the light-transmitting insulating layer. Forming a side pad electrode. As a result, a light-transmitting conductive layer thicker than the bottom surface of the light-transmitting insulating layer can be formed in a portion other than the p-side pad electrode by a relatively easy manufacturing process, and the current is dispersed to form a p-type semiconductor. The layer can be injected and uniform light emission can be obtained.

The method for manufacturing a semiconductor light emitting device according to an embodiment further includes a step of performing a heat treatment for obtaining ohmic contact after the formation of the first light-transmitting conductive layer, and the p-side pad electrode forming region is formed by the heat treatment step. In this case, the contact resistance at the interface between the second conductive type semiconductor layer and the translucent conductive layer can be lowered to make that region a current injection region. As a result, ohmic contact can be obtained even immediately below the p-side pad electrode, and light can be emitted, and the light emission output and light extraction efficiency can be further increased. In particular, by changing the layer thickness of the translucent conductive layer between the lower surface of the p-side pad electrode and the surrounding area, the light emission of the light emitting layer is totally reflected on the lower surface and the light is propagated in the lateral direction. The thick layer thickness reduces the sheet resistance to increase the amount of light emission, and it is possible to extract light from this region to the outside.

The method for manufacturing a semiconductor light emitting device according to an embodiment further includes a step of performing a heat treatment to obtain ohmic contact after forming the light transmissive insulating layer on the first light transmissive conductive layer, The contact resistance at the interface between the second conductive type semiconductor layer and the translucent conductive layer can be made lower in the region covering the surface of the second conductive type semiconductor layer than in the region where the translucent insulating layer is formed. As a result, a current is selectively and selectively injected outside the pad region, so that a light-emitting region having a higher output than the pad region can be obtained, and a suitable light-emitting structure can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below, the semiconductor light emitting device for embodying the technical idea of the present invention, intended to illustrate the light emitting device, the present invention is a specific semiconductor light emitting device, a light emitting device in the following do not do. Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the embodiments are indicated in the scope of claims and “Means for Solving the Problems”. It is added to the members. However, the members shown in the claims are not limited to the members in 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.
(Embodiment 1)

FIG. 1 shows an LED 100 as a semiconductor light emitting element according to Embodiment 1 of the present invention. The LED 100 shown in this figure is formed on a growth substrate 10, an n-type semiconductor layer 12 that is a first conductivity type semiconductor layer formed on the growth substrate 10, and a part on the n-type semiconductor layer 12. A light-emitting layer 14, a p-type semiconductor layer 16 that is a second-conductivity-type semiconductor layer formed on the light-emitting layer 14, and a first light-transmitting conductive layer 20a formed on the p-type semiconductor layer 16. The translucent insulating layer 18 formed on a part of the first translucent conductive layer 20a and the first translucent conductive layer 20a and the periphery and the upper surface of the translucent insulating layer 18 are covered. The second translucent conductive layer 20b formed in this manner, the p-side pad electrode 30 which is the second conductive type pad electrode formed on the upper surface of the second translucent conductive layer 20b, and the n-type semiconductor layer 12 is exposed, and the n-side pad electrode 32 which is a first conductivity type pad electrode formed in this portion. Equipped with a. Furthermore, only the surfaces of the n-side pad electrode 32 and the p-side pad electrode 30 are exposed and covered with a protective film 34 so as to cover other portions.
(Semiconductor layer)

  The LED has a semiconductor layer in which an n-type semiconductor layer 12 made of a nitride semiconductor, a light-emitting layer 14 that is an active layer, and a p-type semiconductor layer 16 are sequentially stacked on a sapphire substrate that is a growth substrate 10. . An n-side pad electrode 32 is formed on the n-type semiconductor layer 12 which is separated from each other and exposed on the line, while the p-type semiconductor layer 16 is provided with a p-side ohmic electrode (not shown) as a contact layer. Thus, the p-side pad electrode 30 is formed.

  Specifically, a semiconductor light emitting device in which a semiconductor layer is epitaxially grown on the growth substrate 10 can be suitably used as the light emitting device. Examples of the growth substrate 10 include sapphire, but are not limited thereto, and known members such as spinel, SiC, GaN, and GaAs can be used. In addition, by using a conductive substrate such as SiC, GaN, or GaAs instead of an insulating substrate such as sapphire, the p electrode and the n electrode can be arranged to face each other. The growth substrate 10 can also be removed after the semiconductor layers are stacked. Further, a substrate having a large number of irregularities on the surface can be used as the growth substrate. As a result, the semiconductor layer and the substrate interface are roughened, and effects such as improved light extraction efficiency can be obtained by scattering and diffraction.

  Specifically, as shown in the modified example of FIG. 7 and FIG. 8 (FIG. 7 is a plan view of the LED chip according to the modified example, FIG. 8 is a sectional view taken along line VIII-VIII of FIG. 7) As shown, an uneven structure is provided between different materials, such as an interface between the substrate 10 and the semiconductor layer, and materials having different refractive indexes, and the light extraction efficiency is improved at the uneven interface between the material interfaces. it can. The planar shape of such irregularities, protrusions, protrusions or recesses is a desired shape in consideration of high-density arrangement and mass productivity. Specific shapes include elliptical shapes, square / rectangular shapes. Further, it may be a polygonal shape or a complex shape thereof. In addition, as for the planar arrangement, a square / rectangular shape, a parallelogram shape, a triangular shape, a hexagonal shape (honeycomb shape), and the like are appropriately selected according to these shapes, and a high-density arrangement is made. The plane size of these structures (protrusions, recesses and grooves) is larger than λ / 4n, preferably more than λ / 2n, and specific dimensions considering mass productivity are 0.5 to It can manufacture suitably that it is 5 micrometers, Preferably it is 1-3 micrometers. Similarly, the cross-sectional shape may be a square shape, a rectangular shape, a trapezoidal shape, a circular shape such as an arc or a semicircle, and the like, and the dimensions may be the same as the planar shape.

  The unevenness of the substrate shown in the figure is provided on the surface facing the translucent electrode structure with the semiconductor layer in between, so that the first and second translucent conductive layers, in particular, the pad region A is a light emitting region, a non-illuminating region. Depending on the light emitting area, the effect tends to change. Specifically, the region A is a non-light emitting region, and the light extraction efficiency is improved, and the light emission output and power efficiency are improved more effectively than the light emitting region, that is, the intervening region B1 is a current injection part. Tend to be. For this reason, it is preferable to provide the concavo-convex structure 10 </ b> C with the region A as a non-light emitting region and a weak light emitting region as compared with the covering region B.

  The concavo-convex structure provided at the interface between the materials is provided on the n-electrode formation surface by a plurality of hole structures provided in the semiconductor layer, a concavo-convex structure on the light emitting layer, and a separation groove provided in the semiconductor layer. An optical structure such as a protruding structure can be provided on the semiconductor layer. In addition, a concavo-convex structure can be provided on a light-transmitting film that covers the semiconductor layer, for example, the light-transmitting conductive layer 20 and the protective film 34. , An optically functional structure can be provided. The above structure can be manufactured by using a processing technique for semiconductors and other materials, etching, laser processing, embossing, and the like.

The light emitting element includes various materials such as BN, SiC, ZnSe, GaN, InGaN, InAlGaN, AlGaN, BAlGaN, and BInAlGaN. Similarly, these elements can contain Si, Zn, or the like as an impurity element to serve as a light emission center. The material of the light emitting layer 14 is a nitride semiconductor (for example, a nitride semiconductor containing Al or Ga, or a nitride semiconductor containing In or Ga, In _X Al _Y Ga _1-XY N (0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, X + Y ≦ 1) etc. Further, as the semiconductor structure, a homostructure having a MIS junction, a PIN junction, a PN junction, etc., a heterostructure, or a double hetero configuration is preferably exemplified. The emission wavelength can be selected in various ways depending on the material of the semiconductor layer and the mixed crystal ratio, and the semiconductor active layer can be a single quantum well structure or a multiple quantum well structure formed in a thin film that produces a quantum effect. In addition, the light emitting element can emit light from the ultraviolet region to the visible light region, particularly having a light emission peak wavelength in the vicinity of 350 nm to 550 nm. It is preferable to use a light emitting layer 14 that can emit light having a light emission wavelength that can efficiently excite a fluorescent substance using a light emitting element, in which a nitride semiconductor light emitting element, particularly blue light emission (wavelength 455 nm) is taken as an example. However, the present invention is not limited to this.
(N-side pad electrode 32)

The n-side pad electrode 32 is formed so as to be close to at least one side of the semiconductor light emitting element. For example, although not shown in the drawing, a notch part in which the n-type contact layer is exposed by removing a part of the p-type semiconductor layer and the active layer by etching is provided at the center part of one side, and the n-side pad is provided in the notch part. An electrode is formed. As a material for the n-side pad electrode 32, metals such as Ti, Rh, Pt, Au, or alloys thereof can be used. In this embodiment, Ti / Rh / Au is used.
(P-side pad electrode 30)

  The p-side pad electrode 30 has a narrow extending conductive portion 31 extending in a protruding shape. FIG. 2 shows an example of a plan view of the LED chip. In the example of this figure, the n-side pad electrode 32 is provided at one corner of the LED chip 100B so as to be close to two sides, and the p-side pad electrode 30 is diagonally opposite the corner at which the n-side pad electrode 32 is adjacent. It is provided in the other corner part which makes. The p-side pad electrode 30 preferably has one or more extended conductive portions 31 as auxiliary electrodes extended from the circular p-side pad electrode 30 as shown in FIG. Each of the stretched conductive portions 31 is preferably formed in an arc shape so as to be equidistant from the n-side pad electrode 32, thereby further diffusing the current input to the semiconductor light emitting element throughout the translucent electrode. High luminance and more uniform light emission can be obtained. As the material of the stretched conductive portion 31, for example, Rh / Pt / Au can be formed with each layer thickness being 100 nm / 200 nm / 500 nm. In addition, the extending | stretching electroconductive part 31 can also be made into three or more, for example, in the LED chip 100C which concerns on the modification of FIG. 3, the nine extending | stretching electroconductive parts 31 are provided.

The stretched conductive portion may be eliminated, or may be provided on the n-side electrode and on both electrodes depending on the structure and area of the light emitting element, and is different from the pad electrode and the metal layer on the translucent conductive layer. It may be formed by a structure or a process, and is preferably formed integrally with a pad electrode.
(Protective film 34)

After the pad electrodes 30 and 32 are formed, an insulating protective film 34 is formed almost on the front surface of the semiconductor light emitting device except for the region where wire bonding is performed. The protective film 34 is _{SiO 2, TiO 2, Al 2} O 3, available polyimide and the like.
(Translucent insulating layer 18)
The translucent insulating layer 18 is a layer having a high resistance or insulating property. With this, in the p-side pad electrode formation region, the translucent conductive layer 20 is interposed between the first intervening region B1 on the lower layer side. Insulating the second intermediate region B2 on the upper layer side. In addition, by using a region where the light-transmitting insulating layer 18 is not provided as a conduction path, the light-transmitting conductive layer 20 is efficiently energized to achieve current diffusion and low resistance. The translucent insulating layer 18 has high translucency so that light from the semiconductor light emitting element can be extracted efficiently. Therefore, the translucent insulating layer 18 preferably contains oxygen, more preferably an oxide, and further preferably an oxide of at least one element selected from the group consisting of 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 insulating layer 18 is not particularly limited, and can be formed with a thickness of several angstroms to several μm. In particular, the thickness of the translucent insulating layer 18 when provided together with the metal layer of the p-side pad electrode 30 formed on the upper surface of the translucent insulating layer 18 is λ / 4n ₃ (λ is the emission wavelength, n ₃ Is larger than the refractive index of the insulating layer). As a specific example, it is preferable that the refractive index is 78 nm to 1 μm. The translucent insulating layer 18 is provided corresponding to the electrode and metal layer provided on the light emitting layer. In the example of the electrode, at least one of the pad electrode 30 and the extended conductive portion 31 of the electrode, preferably the conductive portion. It is provided at least on a pad electrode having a larger area or a wider cross section than the metal layer, and most preferably provided for both. Such a structure can be similarly applied to other embodiments and examples thereof. In other words, the stretched conductive portion may be directly provided on the translucent conductive layer without the translucent insulating layer 18, but in this case, light absorption and loss by the stretched conductive portion occurs. Therefore, since the tendency increases as the cross-sectional width and total area of the stretched conductive portion increase, the pad electrode and the stretched conductive portion are preferably provided via the translucent insulating layer 18. As a specific example thereof, as shown in the plan view of the LED chip 100D according to the modification of FIG. 7, the extended conductive portion 31 has a structure provided through the light-transmitting insulating layer 18.
(Translucent conductive layer 20)

A translucent conductive layer 20 is formed on the p-type semiconductor layer 16. By forming the conductive layer on almost the entire surface of the exposed p-type semiconductor layer 16, the current can be uniformly spread over the entire p-type semiconductor layer 16. Moreover, by providing translucency, the electrode side can be used as a light emission observation surface. Note that translucency means that the light emission wavelength of the semiconductor light emitting element can be transmitted, and does not necessarily mean colorless and transparent. The translucent conductive layer 20 preferably contains oxygen in order to obtain ohmic contact. There are various types of the light-transmitting conductive layer 20 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 20 containing an oxide of Zn, In, Sn, such as ITO, ZnO, In ₂ O ₃ , SnO ₂ or the like. In particular, ITO is an oxide conductive material containing tin in indium oxide, and is suitable as a transparent electrode because it has low resistance and high transparency. Alternatively, a metal layer formed by sputtering a metal such as Ni with a layer thickness of 3 nm or the like to make it transparent may be used. Heat treatment is performed at the interface between the conductive oxide layer and the semiconductor layer so as to obtain good ohmic characteristics. Since ITO is also excellent in ohmic connection with the nitride semiconductor layer, it is practical as a nitride semiconductor light emitting device to reduce the contact resistance at the interface with the p-type nitride semiconductor layer and to lower the forward voltage Vf. A nitride semiconductor light emitting device can be realized.

  The translucent conductive layer 20 shown in FIG. 1 includes a covering region A that covers almost the entire surface of the p-type semiconductor layer 16, and a p-type semiconductor layer 16 and a translucent insulating layer 18 that are partially continuous with the covering region A. And a second intervening region B2 that covers the upper surface from the periphery of the translucent insulating layer 18 and intervenes at the interface with the p-side pad electrode 30. Here, by configuring the layer thickness d1 of the first intervening region B1 to be thinner than the layer thickness d2 of the covering region A, the resistivity immediately below the translucent insulating layer 18 is relatively increased, and Reduce resistivity. As a result, the current from the p-side pad electrode 30 is allowed to flow efficiently around the translucent insulating layer 18 to increase the amount of light emission except at the portion where the p-side pad electrode 30 is provided. Further, by utilizing total reflection of the translucent insulating layer 18 provided on the lower surface of the p-side pad electrode 30, light guided through the lower surface of the p-side pad electrode 30 is transmitted by total reflection, and the p-side pad electrode is provided. Extraction of light from the covered area A or the end face, which is a non-existing area, is intended.

Furthermore, the layer thickness of the first intervening region B1 is approximately (λ / 4n ₂ ) or less with respect to the wavelength λ of light (n ₂ is the refractive index of the translucent conductive layer). This makes it difficult for light to feel the layer thickness of the first intervening region B1, and the interface between the first intervening region B1 and the p-type semiconductor layer 16 substantially becomes the translucent insulating layer 18 and the p-type semiconductor layer 16. And the interface. Since the refractive index difference is small at the interface between ITO (refractive index 2.00) as the first intervening region B1 and GaN (refractive index 2.46) as the p-type semiconductor layer 16, the total reflection angle becomes narrow and large. As a result of the transmission of part of the light, light is absorbed by the metal of the p-side pad electrode 30 located above, and the light extraction efficiency is reduced. On the other hand, since the refractive index difference is large at the interface between SiO ₂ (refractive index 1.46) as the translucent insulating layer 18 and the GaN layer as the p-type semiconductor layer 16, the total reflection angle increases, resulting in total reflection. The rate at which light is generated increases, the rate at which light in the first intervening region B1 is propagated to the coating region A by total reflection increases, and light is emitted from the end face to the outside, thereby increasing light extraction efficiency. In addition, since the layer thickness is relatively large in the covering region A, the difference in the refractive index in this portion is reduced. As a result, the ratio of light transmission is increased, but there is no metal that absorbs light in this region. Therefore, it is taken out as it is. Thus, by making the layer thickness of the translucent conductive layer 20 below the p-side pad electrode 30 thinner than its surroundings, the total reflection angle due to the difference in refractive index is made wider and total reflection is more likely to occur. While the light absorption by the p-side pad electrode 30 located in the region can be reduced, the light extraction efficiency to the side and upward can be greatly improved. The layer thickness of the first intervening region B1 is preferably 57 nm or less in this example (GaN layer, ITO, SiO ₂ , emission wavelength 455 nm). In particular, the refractive index n ₂ of the translucent conductive layer is n ₂ ≧ n ₁ or | n ₁ −n ₂ | <| n ₁ −n ₃ | (where n ₁ and n ₃ are In the case of the two-conductivity-type semiconductor layer and the refractive index of the light-transmitting insulating layer), the light extraction efficiency can be further improved when the latter is satisfied, more preferably when both are satisfied. .

In the LED having the above structure, the first intervening region B1 and the semiconductor layer 16 are electrically connected, and the lower surface of the p-side pad electrode 30 also emits light. Conventionally, the idea of suppressing the current injected into this part and reducing the components that do not contribute to light emission to increase the light emission efficiency by relatively increasing the current components that contribute to light emission has been common. On the other hand, in the LED according to the first embodiment, on the contrary, the entire surface including the lower surface of the p-side pad electrode 30 emits light, and the current flowing through the p-side pad electrode 30 is made uniform, thereby eliminating the uneven distribution of current. As a result, the deterioration of the p-side pad electrode 30 is suppressed, and as a result, the reliability of the LED element itself is improved. The LED having this structure causes the lower surface of the p-side pad electrode 30 to emit light, and light guided through the lower surface of the p-side pad electrode 30 is propagated from the lower surface of the p-side pad electrode 30 to the position of the side surface by total reflection. Take out to the outside.
(Embodiment 2)

  In the above configuration, the thickness of one translucent conductive layer 20 is changed below and around the p-side pad electrode 30, but the translucent conductive layer 20 may be changed to a multilayer configuration. it can. An LED chip 200 having such a configuration is shown in FIG. In this figure, the same members as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. In FIG. 4, first, a first light-transmitting conductive layer 20c having a uniform thickness is formed on almost the entire top surface of the p-type semiconductor layer 16, and a light-transmitting insulating layer 18 is formed. The second light-transmissive conductive layer 20d having a sufficient thickness is formed. Thereby, the layer thickness d1 of the translucent conductive layer in the first intervening region B1 between the translucent insulating layer 18 and the p-type semiconductor layer 16 becomes the layer thickness of the first translucent conductive layer 20c. The layer thickness d2 in the covering region A is the sum of the layer thicknesses of the first light-transmitting conductive layer 20c and the second light-transmitting conductive layer 20d, and a difference in the layer thickness can be provided in these regions. In this configuration, since the light-transmitting conductive layer having a uniform layer thickness can be formed stepwise, the manufacturing process for forming the layer thickness difference can be simplified. Here, the film thicknesses of the first translucent conductive layer 20c and the second translucent conductive layer 20d may be substantially the same as or different from each other as in this example. If the conductive layer 20c is made smaller, the distance d1 to the insulating layer 18 can be made smaller to provide better light reflectivity, and the sheet resistance of the second translucent conductive layer 20d can be made smaller to increase current diffusibility. preferable.

In the above example, the configuration in which the lower surface of the p-side pad electrode 30 emits light has been described. However, the lower surface of the p-side pad electrode 30 may be configured not to emit light. The presence or absence of light emission makes the interface between the translucent conductive layer 20 and the p-type semiconductor layer 16 on the lower surface of the p-side pad electrode 30 larger or smaller than the contact resistance of the interface in the covered region of the other translucent conductive layer. It is preferably divided according to whether it is ohmic contact or non-ohmic contact. Specifically, ohmic contact can be obtained by performing the same heat treatment as the region other than the pad electrode and the insulating layer on the translucent conductive layer 20 on the lower surface of the p-side pad electrode 30, and no heat treatment is performed. Non-ohmic contact can be achieved by covering and protecting with an insulating layer, an electrode, and a metal layer provided thereon, followed by heat treatment. At this time, the heat treatment temperature can be about 300 to 600 ° C. When an LED according to an example in which the lower surface of the pad electrode 30 is made non-light-emitting is prototyped and the light emission output is compared with the LED according to the first embodiment, substantially the same output can be obtained. This is probably because the light extraction efficiency in the region other than the p-side pad electrode 30 is improved.
(Embodiment 3)

In the above example, the light-transmitting conductive layer 20 is made of two ITO layers, and the layer thickness of the intervening region is made thinner than the layer thickness of the covering region A. However, the present invention is not limited to this configuration. For example, two or more layers of ITO can be stacked to form a similar layer thickness difference. Alternatively, it is possible to form a layer thickness difference by etching or the like with one layer of ITO. Furthermore, the layer thickness of the translucent conductive layer 20 on the lower surface of the translucent insulating layer 18 can be partially reduced. FIG. 5 illustrates an LED chip 300 in which the layer thickness of the light-transmitting conductive layer 20B made of ITO is partially changed as a third embodiment. In this figure, members similar to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. In this example, once the ITO film is formed, the region where SiO ₂ is formed is removed by etching, and the film thickness is partially reduced. Thereafter, SiO ₂ is formed on the etched region. Further, the translucent conductive layer forming the second intervening region B2 is extended to the lower translucent conductive layer 20B so as to cover the periphery of the SiO ₂ , and is partially connected on the layer 20B. The p-side pad electrode 30 is formed thereon. In this configuration, the thickness of the lower ITO layer is changed, and the distance d1 is controlled by the etching process. The accuracy tends to be low.

Further, in this example, as a modification, the upper layer side light-transmitting conductive layer B2 is eliminated and the pad electrode is formed in the same shape as that, but the upper layer side ITO film forming process can be simplified. There is a problem that the etching process is required and the accuracy of the distance d1 is lowered. In this modification, since that would be present region in the region where the film thickness of the ITO at the edge of the SiO ₂ is thick pad electrode without interposing the SiO ₂ in contact with the ITO, as shown in FIG. 5, this The portion emits light strongly, and there is also absorption of light by the pad electrode at the edge portion, so that the light extraction efficiency is slightly lowered. As described above, when the pad electrode 30 and the metal layer are extended outside the insulating layer 18, there is light absorption and loss. Therefore, the pad electrode 30 is preferably provided inside the insulating layer 18. The same applies to each example.

Each of the above embodiments and examples has a structure in which the covering region A of the translucent conductive layer 20 and the pad electrode 30 region or the translucent insulating layer 18 region B are respectively disposed on the light emitting layer. is doing. Further, the thickness d2 of the translucent conductive layer 20 in the covering region B has a structure larger than the thickness d1 of the translucent conductive layer in the pad electrode / insulating layer region A. In the pad electrode / insulating layer region A, the light can be efficiently reflected and the light extraction efficiency is improved. At this time, the above effects can be enhanced by setting the film thickness d1 to less than λ / 4n ₂ and the film thickness d2 to λ / 4n ₂ or more, preferably λ / 2n ₂ or more.

In addition, as described above, each of these embodiments and each example thereof is preferably used for a light emitting element having an electrode side on the light emitting layer as an emission side, and the opposite semiconductor layer side and the substrate side as a mounting side. The light emitting device can be bonded to the mounting portion of the light emitting device. On the other hand, as shown in Embodiment Mode 4 below, a light emitting element in which the electrode side is a reflection side, the semiconductor layer side, and the substrate side is an emission side can be provided. In addition, although the example in which each electrode of the semiconductor layer is provided on the same surface side of the semiconductor layer is shown, a structure in which electrodes of each conductive type semiconductor layer are provided to face each other with the semiconductor layer interposed therebetween may be employed. it can. In this case, the electrode structure on the side of at least one conductive type semiconductor layer is the structure having the insulating layer described above, and can be applied to the electrode structure on the side of both conductive type semiconductor layers.
(Embodiment 4)

  Further, a light emitting device according to Embodiment 4 in which the present invention is applied to a flip-chip type LED is shown in a sectional view of FIG. In this figure, an LED chip 400 which is a nitride semiconductor light emitting element is flip-chip mounted on a submount 40 which is one of wiring boards. The flip chip is a mounting method in which the main light extraction surface is the growth substrate 10B 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 etc.

  In the LED chip 400 of FIG. 6, the buffer layer 11, the n-type semiconductor layer 12B, the light-emitting layer 14B, and the p-type semiconductor layer 16B are epitaxially grown in this order on the growth substrate 10B, and the transparent conductive layer 20 and the reflective layer 42 are further laminated. is doing. Although not shown in detail in FIG. 6, a part of the light emitting layer 14B and the p-type semiconductor layer 16B is selectively removed by etching to expose a part of the n-type semiconductor layer 12B, and an n-side pad electrode is formed. Forming. A p-side pad electrode 30 is formed on the p-type semiconductor layer 16B on the same surface side as the n-side electrode. On the pad electrode, a metallized layer (bump 44) 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 400 is opposed to a pair of positive and negative external electrodes provided on the submount 40, and each electrode is joined by a bump 44. Further, a wire 46 and the like are wired to the submount 40. On the other hand, the main surface side of the growth substrate 10B of the LED chip 400 mounted face down is a main light extraction surface. In such flip chip mounting, a plurality of pad electrodes can be provided in consideration of ease of mounting and the like. Also in this case, for each p-side pad electrode 30B, the layer thickness of the intervening region is made thinner than the layer thickness of the covering region in the same manner as face-up mounting, so that the current of the pad electrode is made uniform and element degradation is effectively performed. Can be prevented.

As described above, according to the present embodiment, the translucent conductive layer 20 on the lower surface of the pad electrode is caused to emit light, so that a current is uniformly supplied over a wide area from the pad electrode, thereby preventing local deterioration. The reliability of the light emitting element can be improved. Further, conventionally, light absorbed at the interface between the semiconductor layer and the translucent conductive layer or the interface between the semiconductor layer and the pad electrode can be effectively taken out and used, and the light emission efficiency can be improved. In particular, the light component that has been absorbed by the p-GaN layer and the pad electrode in the past is totally reflected by inserting a film having a lower refractive index than the GaN layer under the light-transmitting conductive film. It can be propagated to the outside and taken out to the outside.
(Embodiment 5)

  Next, as a light-emitting device according to Embodiment 5, a bullet-type light-emitting device is shown in FIG. The light emitting device 500 is in a concave cup 54 formed by a lead frame 52 made of a conductive member. The light emitting device 500b is placed on the lead frame 52, and is emitted from the light emitting element 500b. The phosphor 56 is provided as a wavelength conversion member that converts the wavelength of at least a part of the light. The positive and negative electrodes formed on the light emitting element 500 b are electrically connected to the lead frame 52 through the conductive bonding wires 58. Further, the light emitting element 500b, the lead frame 52, and the bonding wire 58 are covered with a shell-shaped mold 59 so that the lead frame electrode 52a which is a part of the lead frame 52 protrudes. The resin 60 used for the mold member or the like is preferably a silicone resin composition because of light resistance, but an insulating resin composition having translucency such as an epoxy resin composition and an acrylic resin composition can also be used. . When the lead frame electrode 52a protruding from the resin 60 is electrically connected to a power source (not shown), light is emitted from the light emitting layer 14b contained in the layer of the light emitting element 500b. The emission peak wavelength output from the light emitting layer 14b has an emission spectrum near 500 nm or less in the ultraviolet to blue region. A part of the emitted light excites the phosphor 56, and light having a wavelength different from the wavelength of the main light source from the light emitting layer 14b is obtained.

  In the light emitting device 500 of FIG. 9, a resin 60 including a phosphor 56 is filled in a concave cup 54 formed by the lead frame 52. The phosphor 56 is not contained in the resin 60 b filled in the outside of the cup 54 in the mold 59. The resin containing phosphor 56 and the type of resin not containing are preferably the same, but they may be different. In the case of different types of resins, the softness can be changed using the difference in temperature required for each resin to cure.

As described above, a mold member containing a phosphor may be provided in a part of the periphery of the mounting portion of the light emitting element 500b, or may be contained in a base material of the light emitting device, for example, the mold 59. It is also possible to cover the surface with a cap made of a light-transmitting resin in which a phosphor is dispersed. Specific materials for the cap resin include transparent resins, silica gel, glass, inorganic binders, and the like that are excellent in temperature characteristics and weather resistance, such as epoxy resins, urea resins, and silicone resins.
(Embodiment 6)

  Further, as a light-emitting device according to Embodiment 6, a surface-mounted light-emitting device 600 is illustrated in FIG. FIG. 10A is a plan view, and FIG. 10B is a cross-sectional view. The light-emitting element 600b can be an ultraviolet light-excited nitride semiconductor light-emitting element. The light-emitting element 600b may be a blue-excited nitride semiconductor light-emitting element. Here, the light-emitting element 600b excited by ultraviolet light will be described as an example. The light emitting element 600b uses a nitride semiconductor light emitting element having an InGaN semiconductor layer having an emission peak wavelength of about 370 nm as the light emitting layer. In the light emitting element 600b, a p-type semiconductor layer and an n-type semiconductor layer are formed (not shown), and a conductive wire 66 connected to the lead electrode 64 is connected to the p-type semiconductor layer and the n-type semiconductor layer. Is formed. An insulating sealing material 65 is formed so as to cover the outer periphery of the lead electrode 64 to prevent a short circuit. A light-transmitting window 67 extending from a Kovar lid 63 at the top of the package 61 is provided above the light emitting element 600b. A uniform mixture of the phosphors 56 and 56a and the coating member 68 is applied to the entire inner surface of the translucent window 67.

The respective electrodes of the die-bonded light emitting device 600b and the respective lead electrodes 64 exposed from the bottom of the package recess are electrically connected by a conductive wire 66 such as an Ag wire. After sufficiently removing moisture in the recess of the package, sealing is performed with a Kovar lid 63 having a glass window 67 at the center, and seam welding is performed. In the glass window portion, oxynitride phosphors 56 and 56a which are wavelength conversion members are previously contained in a slurry composed of 90 wt% of nitrocellulose and 10 wt% of γ-alumina, and the translucent window portion 67 of the lid 63 is contained. The color conversion member is configured by applying to the back surface of the film and curing by heating at 220 ° C. for 30 minutes. The light output from the light emitting element 600b of the light emitting device 600 thus formed excites the phosphors 56 and 56a, so that a light emitting device capable of emitting a desired color with high luminance can be obtained. As a result, it is possible to obtain a light emitting device that is extremely easy to adjust the chromaticity and has excellent mass productivity and reliability.
(Manufacturing method of semiconductor light emitting device)

Next, a method for manufacturing a semiconductor light emitting element will be described. This semiconductor layer is a gallium nitride-based compound semiconductor, and a nitride semiconductor element having an InAlGaN semiconductor with an emission wavelength of 460 nm in which the emission peak from the emission layer 14 including the active layer is in the ultraviolet region is used. More specifically, by flowing TMG (trimethylgallium) gas, TMI (trimethylindium) gas, nitrogen gas and dopant gas together with a carrier gas on a cleaned sapphire substrate, a nitride semiconductor is formed by MOCVD. Can be formed. A layer to be an n-type nitride semiconductor or a p-type nitride semiconductor is formed by switching between SiH ₄ and Cp ₂ Mg as the dopant gas.

  As the structure of the semiconductor element, an n-type GaN layer which is an undoped nitride semiconductor on a sapphire substrate, a GaN layer where an Si-doped n-type electrode is formed to become an n-type contact layer, and an n-type which is an undoped nitride semiconductor A set of a GaN layer, an AlGaN layer containing Si serving as an n-type cladding layer, an AlInGaN layer constituting a well layer as the light emitting layer 14, and an AlInGaN layer serving as a barrier layer having a higher Al content than the well layer It is a multi-quantum well structure in which five sets are stacked. On the light emitting layer 14, an AlGaN layer as a p-type cladding layer doped with Mg, a GaN layer for increasing electrostatic withstand voltage, and a GaN layer as a p-type contact layer doped with Mg are sequentially laminated. (Note that a GaN layer is formed on the sapphire substrate at a low temperature to serve as a buffer layer. In addition, the p-type semiconductor is annealed at 400 ° C. or higher after film formation).

More specifically, after a buffer layer made of GaN is grown at a temperature of 20 nm on a sapphire substrate having a main surface of 2 inches φ and a (0001) C plane, the temperature is set to 1050 ° C. An undoped GaN layer is grown to a thickness of 5 μm. Note that the film thickness to be grown is not limited to 5 μm, and it is desirable to grow the film thicker than the buffer layer and adjust the film thickness to 10 μm or less.
(N-type semiconductor layer 12)

Next, an n-type contact layer and an n-type gallium nitride compound semiconductor layer are formed. First, an n-type contact layer made of GaN doped with Si of 4.5 × 10 ¹⁸ / cm ³ is grown at a thickness of 2.25 μm at 1050 ° C. using silane gas as the source gas TMG, ammonia gas, and impurity gas. Let Next, only the silane gas is stopped, TMG and ammonia gas are used at 1050 ° C., and an undoped GaN layer is grown to a thickness of 7.5 nm. Subsequently, silane gas is added at the same temperature, and Si is added to 4.5 × 10. ^{A 18} / cm ³ -doped GaN layer is grown to a thickness of 2.5 nm. In this way, a pair consisting of an A layer made of 7.5 nm undoped GaN and a 2.5 nm B layer having an Si doped GaN layer is grown. Then, 25 pairs are stacked to a thickness of 250 nm, and an n-type gallium nitride compound semiconductor layer made of a multilayer film having a superlattice structure is grown.
(Active layer)

Next, a barrier layer made of undoped GaN is grown to a thickness of 25 nm, and then the temperature is raised to 800 ° C., and a well layer made of undoped InGaN is grown to a thickness of 3 nm using TMG, TMI, and ammonia. . Then, seven barrier layers and six well layers are alternately stacked in the order of barrier + well + barrier + well + ... + barrier to grow an active layer having a multiple quantum well structure with a total film thickness of 193 nm. Let
(P-type semiconductor layer 16)

Next, a p-type semiconductor layer 16 composed of a p-side multilayer clad layer and a p-type contact layer is formed. First, a third nitride made of p-type Al _0.2 Ga _0.8 N doped with Mg at 1 × 10 ²⁰ / cm ³ using TMG, TMA, ammonia, Cp ₂ Mg (cyclopentadienyl magnesium) at a temperature of 1050 ° C. The semiconductor layer is grown to a film thickness of 4 nm, and subsequently made of In _0.03 Ga _0.97 N doped with 1 × 10 ²⁰ / cm ^{3 of} Mg using TMG, TMI, ammonia, Cp ₂ Mg at a temperature of 800 ° C. A fourth nitride semiconductor layer is grown to a thickness of 2.5 nm. Then, these operations are repeated, and 5 layers are alternately laminated in the order of 3 + 4, and finally the p-side made of a multilayer film having a superlattice structure in which a third nitride semiconductor layer is grown to a thickness of 4 nm. A multilayer clad layer is grown to a thickness of 36.5 nm. Subsequently, at 1050 ° C., a p-side contact layer made of p-type GaN doped with 1 × 10 ²⁰ / cm ^{3 of} Mg is grown to a thickness of 70 nm using TMG, ammonia, and Cp ₂ Mg. After the completion of the reaction, the temperature is lowered to room temperature, and the wafer is annealed at 700 ° C. in a reaction vessel in a nitrogen atmosphere to further reduce the resistance of the p-type semiconductor layer 16.

Next, the surface of each pn contact layer is exposed on the same side as the nitride semiconductor on the sapphire substrate by etching. Specifically, the wafer is taken out of the reaction vessel, a mask having a predetermined shape is formed on the surface, and etching is performed from the p-type gallium nitride compound semiconductor layer side with an RIE (reactive ion etching) apparatus, and the second corner portion The surface of the n-type contact layer was exposed.
(First translucent conductive layer 20a)

Next, the mask on the p-type nitride semiconductor layer is removed, the wafer is placed in a sputtering apparatus, and sputtering is performed, so that a translucent electrode made of ITO is formed on the entire surface of the p-type contact layer of the wafer by 10 nm. The film thickness was formed. The obtained translucent electrode had good translucency and could be observed through the sapphire substrate. As described above, the first light-transmissive conductive layer 20a 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. Subsequently, the electrode is annealed by heat treatment at 300 ° C. or higher. Thus, in order to improve the ohmic property of an electrode, you may perform an electrode annealing process. When light is not emitted under the p-side pad electrode 30, the insulating layer and the pad electrode are heat-treated protective film by performing electrode annealing after forming the translucent insulating layer and / or after forming the pad electrode. As a different annealing condition from the coating region of the light-transmitting conductive layer without the protective film, the contact resistance of each region can be made different. In general, the electrode annealing process makes the region covered with the insulating layer and pad electrode have a higher contact resistance with the semiconductor layer than the light-transmitting conductive layer covered region, and current injection is preferentially and selectively applied to the covered region. Is emitted. At this time, it is preferable that at least a step of annealing is performed after the formation of the light-transmitting insulating layer, and further, the contact resistance in the region of the insulating layer and the pad electrode is increased, resulting in non-ohmic contact. Thus, it is preferable to selectively inject current into the covered region of the translucent conductive layer.
(Translucent insulating layer 18)

Further, a SiO ₂ film having a thickness of 10 nm is formed thereon as a light-transmitting insulating layer 18 by sputtering.
(Second translucent conductive layer 20b)

Next, ITO is formed as a light-transmitting p-side light-transmitting conductive layer having a thickness of 11 nm so as to cover almost the entire surface of the p-type semiconductor layer 16. At this time, an n-side translucent conductive layer is also formed at the same time. Thus, each electrode can be formed with a small number of steps using the same material, but may be formed in a separate step when the materials are different. After forming the translucent conductive layer, heat treatment is performed at 300 ° C. or higher as an electrode annealing treatment. As a result, the second layer of ITO is blended with the first layer, and the ohmic contact with the p-type semiconductor layer 16 is improved.
(P-side pad electrode 30, n-side pad electrode 32)

  A p-side pad electrode 30 (Ti / Rh / Au = 15/2000/6000) is formed with a film thickness of about 800 nm on the insulating layer. In addition, an n-pad electrode having the same structure as that of the p-side pad electrode 30 is also formed on the n-side translucent conductive layer on the surface of the contact layer made of the n-type semiconductor layer 12. The number of steps can be reduced by using the same material. However, there is no problem even if different materials are used. After the formation of the pad electrode, the growth substrate 10 is polished to about 80 μm. By making the growth substrate 10 thin by polishing in this way, it becomes easy to divide. A scribe line is drawn on the completed semiconductor wafer and then divided by an external force to obtain a semiconductor light emitting device. The obtained semiconductor light emitting device has Vf of 3.1 V, light emission output of 30 mW, and power conversion efficiency at a current value of 20 mA is about 48.3%.

As specific examples of the dimensions of the structures shown in the above examples, the thickness of the substrate 10 is about 50 to 200 μm (about 80 μm in the above example). The thickness of the base layer is about 1 to 2 μm, the thickness of the n-type semiconductor layer 12 is about 1 to 2 μm, the thickness of the active layer / light emitting layer 14 is about 50 to 150 nm, and the thickness of the p-type semiconductor layer 16 is 100 ˜300 nm, height from the exposed surface of the n-type layer to the surface of the semiconductor layer is about 1 to 3 μm (about 1.2 μm in the above example), the exposed width of the n-type layer at the outer edge of the device is 5 to 50 μm, The thickness of the part is about 0.3 to 1.5 μm, the width and diameter of the external connection part (window part of the protective film 34) and the pad electrode are 50 to 150 μm, and the conductive when the stretched conductive part side is the light extraction side The width of the part is 3-20μm, the pad electrode and the stretched conductive part are insulated If provided in the 18 end distance between the conductive portion and the insulating layer (the illustrated example) is about 3 to 10 [mu] m. The external dimensions of the examples of the light emitting elements 100B to 100D shown in FIGS. 2, 3, and 7A are □ 320 μm (320 × 320 μm). However, the present invention is not limited to this, and the present invention can be applied to those of various dimensions.
(Example)

  A semiconductor light emitting device shown in FIG. 1 that emits light on the lower surface of the p-side pad electrode 30 by the annealing process was manufactured as Example 1. Further, a semiconductor light emitting device that does not emit light on the lower surface of the p-side pad electrode 30 by performing an annealing process after forming the second light-transmitting conductive layer without performing the annealing process after forming the first light-transmitting conductive layer. Was made as Example 2. As a pattern of these p-side pad electrodes 30, a pattern having nine extended conductive portions 31 shown in FIG. 3A was used. On the other hand, for comparison, a semiconductor light-emitting element in which the light-transmitting insulating layer 18 was provided below the p-side pad electrode 30 and the light-transmitting conductive layer 20 was not provided was fabricated as Comparative Example 1. Table 1 shows the specifications and light emission characteristics of these semiconductor light emitting devices. Table 1 shows the ITO film thickness, the number of stretched conductive portions of the p-side pad electrode, the forward voltage Vf, the integrating sphere result φe at If = 20 mA, the main wavelength λd, and the peak wavelength λp as the luminous flux.

  Thus, it was confirmed that a high light emission output can be obtained by the configuration of the present invention in which the layer thickness of the translucent conductive layer 20 is changed. In addition, according to the other test result which changed the number of extending | stretching electroconductive parts, when the extending | stretching electroconductive part is four (FIG. 3B), a higher light emission output is obtained. As a specific example, as shown in Table 2 below, the same applies to Example 1 except that the stretched conductive portions 31 are two (FIG. 2), nine (FIG. 3A), and four (FIG. 7). The electrical characteristics and output characteristics obtained in each example are shown in Table 2 below as Examples 3 to 5, respectively. (The symbols in the table are the same as those in Table 1, but the item of power conversion efficiency is added in Table 2 below)

  Further, in Example 3, the cross section of the substrate convex portion as shown in FIG. 8 is trapezoidal, the plane is circular, and each convex portion is arranged in a honeycomb shape. A light emitting element in which the pad region A emits light and does not emit light is prepared using a substrate having a concavo-convex structure 10C that is RIE etched to several μm. Comparing the light emission characteristics, the output of the non-light emitting type light emitting element is higher than that of the light emitting type light emitting element, and the output of the non light emitting type is similar to that of Example 3 even when the substrate is flat. There is a tendency to decrease. Furthermore, for the light-emitting and non-light-emitting light-emitting elements having this concavo-convex structure 10C substrate, each having a highly reflective Ag layer in the lowermost metal layer of the pad electrode / stretched conductive part is compared and prepared. Non-light emitting light emitting elements tend to recover to the same light emitting output. Therefore, when the optical structure portion is provided on the semiconductor layer surface side facing the surface provided with the electrode structure having the regions A and B, the electrode structure is preferably a non-light emitting type rather than a light emitting type. I understand that. This is considered to be due to the scattering effect of the concavo-convex structure, the reflection at the interface between the translucent insulating layer and the semiconductor layer is decreased, the reflection on the lower surface of the pad electrode is increased, and the tendency is more pronounced than the non-light emission in the light emitting type.

  From the above, a light-emitting element having a reflective layer on a light-transmitting conductive layer and having a semiconductor layer surface opposite to the formation surface side of the electrode structure having regions A and B, for example, the light-emitting element 400 in FIG. Then, it is considered that a light emitting type light emitting element functions suitably.

As described above, the translucent insulating layer 18 having a refractive index lower than that of the p-type semiconductor layer 16 is disposed on the upper surface of the p-type semiconductor layer 16 and the thickness of the translucent conductive layer 20 interposed therebetween is reduced. , Preferably λ / 4n or less, so that the interface between the light-transmitting insulating layer 18 and the p-type semiconductor layer 16 causes the light absorbed by the semiconductor layer and the pad electrode to be totally reflected and effectively Light can be extracted outside. Here, the light-emitting wavelength of the semiconductor light-emitting element is set to 460 nm, and the light-transmitting insulating layer 18 having a refractive index lower than the refractive index n = 2.46 of the GaN layer, which is a semiconductor layer, is used. Total reflection occurs between 18. When the light-transmitting conductive film is made of a material containing In and O, good ohmic connection and low resistance can be achieved. Further, since the translucent insulating layer 18 is made of SiO ₂ having a low refractive index, the ratio of the total reflected light can be increased, and the light can be efficiently taken out to improve the efficiency.

  In addition, the structure having the conductive layer B1 interposed between the insulating layer 18 and the semiconductor layer complicates the pad electrode and the extended conductive portion, and makes it possible to achieve uniform light emission without increasing the area of the light emitting element. The light extraction efficiency and power efficiency can be improved. In addition, regarding the difference in the types of elements having the electrode structure side and the opposite side as the emission side, suitable light emission characteristics can be obtained by applying the non-light emitting and light emitting type light emitting elements corresponding to each.

The semiconductor light-emitting device of the present invention, the light emitting device, a display can be suitably used from the optimum ultraviolet light as a light source for optical communications and OA equipment emitting diode or a display using the same that emits red light, the lighting and the like.

It is sectional drawing which shows the semiconductor light-emitting device concerning Embodiment 1 of this invention. It is a top view which shows a LED chip. It is a top view of the LED chip which concerns on a modification. FIG. 6 is a cross-sectional view showing a semiconductor light emitting element according to Embodiment 2. FIG. 6 is a cross-sectional view showing a semiconductor light emitting element according to a third embodiment. 6 is a schematic cross-sectional view showing an LED mounted with a nitride semiconductor light emitting element according to Embodiment 4. FIG. It is a top view of the LED chip which concerns on a modification. It is the VIII-VIII sectional view taken on the line of FIG. 10 is a cross-sectional view showing a bullet-type light emitting device according to Embodiment 5. FIG. (A) is a top view which shows the surface mount type light-emitting device based on Embodiment 6, (b) is sectional drawing which shows the light-emitting device of (a). It is sectional drawing which shows the conventional GaN-type compound semiconductor light-emitting device. It is a perspective view which shows the other conventional GaN-type compound semiconductor light-emitting device. It is sectional drawing which shows the GaN-type compound semiconductor light-emitting device of FIG.

100 ... LED
100B, 100C, 100D, 200, 300, 400 ... LED chip 500, 600 ... Light emitting device 500b, 600b ... Light emitting element 10, 10B ... Growth substrate; 10C ... Concavity and convexity 11 ... Buffer layer; 12, 12B ... n-type semiconductor layer 14, 14B, 14b ... Light-emitting layer 16, 16B ... p-type semiconductor layer 18 ... Translucent insulating layer 20, 20B ... Translucent conductive layer 20a, 20c ... First translucent conductive layer 20b, 20d ... Second translucent Photoconductive layer 30, 30B ... p-side pad electrode 31 ... extended conductive portion 32 ... n-side pad electrode 34 ... protective layer 40 ... submount 42 ... reflective layer 44 ... bump 46 ... wire 52 ... lead frame 52a ... lead frame electrode 54 ... Cup 56 ... Phosphor 58 ... Bonding wire 59 ... Mold 60, 60b ... Resin 61 ... Package 62 ... Cap DESCRIPTION OF SYMBOLS 3 ... Lid 64 ... Lead electrode 65 ... Insulation sealing material 66 ... Conductive wire 67 ... Window part 68 ... Coating member 70 ... GaN-type compound semiconductor element 71 ... Sapphire substrate 72 ... N-type semiconductor layer 73 ... Light emitting layer 74 ... p Type semiconductor layer 75 ... transparent electrode 76 ... p-side pad electrode 77 ... n-side pad electrode 78 ... protective film 80 ... GaN-based compound semiconductor element 81 ... p-side pad electrode 82 ... insulating film 83 ... transparent electrode A ... covering region; B ... Covering area; B1 ... First intervening area; B2 ... Second interposing area

Claims (6)

A first conductivity type semiconductor layer;
A light emitting layer formed on at least a part of the first conductive semiconductor layer;
A second conductive type semiconductor layer formed on the light emitting layer;
A translucent insulating layer formed on at least a part of the second conductive type semiconductor layer;
A second conductivity type pad electrode formed on at least a part of the light-transmitting insulating layer;
A semiconductor light emitting device comprising:
An intervening region interposed at an interface between the translucent insulating layer and the second conductive semiconductor layer;
A covering region covering a region on the second conductive type semiconductor layer excluding a portion provided with the light-transmissive insulating layer;
A translucent conductive layer having
The thickness of the intervening region is configured to be thinner than the layer thickness of the covering region ,
A refractive index of the translucent insulating layer is lower than that of the second conductive semiconductor layer, and
The thickness of the translucent conductive layer interposed between the second conductive type semiconductor layer and the translucent insulating layer is such that the light wavelength λ of the light emitting element and the refractive index n of the translucent conductive layer. On the other hand, it is approximately (λ / 4n) or less,
The layer thickness of the light-transmitting conductive layer in the covering region covering the region excluding the light-transmitting insulating layer on the second conductive type semiconductor layer is the light wavelength λ of the light-emitting element, the light-transmitting conductive layer For refractive index n, greater than (λ / 4n),
The semiconductor light emitting device characterized to Rukoto and current injection region transmitting conductive layer on the lower surface the transparent insulating layer. A first conductivity type semiconductor layer;
A light emitting layer formed on at least a part of the first conductive semiconductor layer;
A second conductive type semiconductor layer formed on the light emitting layer;
A translucent insulating layer formed on at least a part of the second conductive type semiconductor layer;
A second conductivity type pad electrode formed on at least a part of the light-transmitting insulating layer;
A covering region covering substantially the entire surface of the second conductive type semiconductor layer, and a first intervening region partially interposed between the second conductive type semiconductor layer and the translucent insulating layer continuously to the covering region When a transparent conductive layer that have a second intermediate region interposed at the interface between the second conductivity-type pad electrode by covering the upper surface from the periphery of the translucent insulating layer,
With
The layer thickness of the first intervening region is configured to be thinner than the layer thickness of the covering region ,
A refractive index of the translucent insulating layer is lower than that of the second conductive semiconductor layer, and
The thickness of the translucent conductive layer interposed between the second conductive type semiconductor layer and the translucent insulating layer is such that the light wavelength λ of the light emitting element and the refractive index n of the translucent conductive layer. On the other hand, it is approximately (λ / 4n) or less,
The layer thickness of the light-transmitting conductive layer in the covering region covering the region excluding the light-transmitting insulating layer on the second conductive type semiconductor layer is the light wavelength λ of the light-emitting element, the light-transmitting conductive layer For refractive index n, greater than (λ / 4n),
The semiconductor light emitting device characterized to Rukoto and current injection region transmitting conductive layer on the lower surface the transparent insulating layer. The semiconductor light-emitting device according to claim 1 or 2 ,
The contact resistance at the interface between the second conductive type semiconductor layer and the translucent conductive layer is such that the region covering the surface of the second conductive type semiconductor layer is lower than the region where the translucent insulating layer is formed. A semiconductor light emitting device characterized. A semiconductor light emitting device as claimed in any one of 3,
The second conductivity type layer is a nitride semiconductor layer;
The semiconductor light-emitting device, wherein the light-transmitting insulating layer has a refractive index of 2.46 or less. A semiconductor light emitting device as claimed in any one of 4,
The semiconductor light emitting device, wherein the second conductivity type pad electrode is inside the translucent insulating layer as viewed from above. A semiconductor light emitting device;
A wavelength conversion member that converts the wavelength of light emitted from the semiconductor light emitting element;
A light emitting device comprising:
The light emitting device which is a semiconductor light-emitting device according semiconductor light emitting element in any one of claims 1-5.

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