JP5045001B2 - Semiconductor light emitting device - Google Patents

Description

  The present invention relates to a semiconductor light emitting device such as a light emitting diode or a semiconductor laser, and more particularly to a nitride semiconductor device formed using a semiconductor layer in which nitride semiconductors are stacked.

Conventionally, as a semiconductor light emitting device, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are stacked on a substrate such as sapphire, and an electrode that is electrically connected to each of the n-type and p-type semiconductor layers is formed. The structure is known. For example, when each electrode is provided on the same surface side, the p-side electrode is disposed on the p-type semiconductor layer, and part of the p-type semiconductor layer, the active layer, and the n-type semiconductor layer is removed and exposed. A configuration in which an n-side electrode is disposed on an n-type semiconductor layer is known.
These semiconductor light emitting devices are usually configured to extract emitted light mainly in the vertical direction (direction in which the n-type semiconductor layer and the p-type semiconductor layer are stacked). In order to improve the light emission output of such a semiconductor light emitting device, various types of semiconductor light emitting devices have been proposed. For example, in Patent Document 1, a groove reaching the light emitting layer from the light emission observation surface side of the semiconductor stacked portion is formed in the semiconductor stacked portion including the light emitting layer, and light emitted laterally from the opening of the groove is emitted. It is disclosed that the light emission output is improved by adopting a configuration in which the light is reflected by the side surface of the groove.
JP 2002-26386 A

However, since the semiconductor light emitting element as described above emits a lot of light not only in the vertical direction but also in the horizontal direction, it is difficult to effectively use the emitted light. In Patent Document 1, the area of the light emitting layer is reduced by forming a groove in the semiconductor stacked portion.
In addition, the conventional semiconductor light emitting device as described above generates a tensile strain or a compressive strain based on a difference in lattice constant and thermal expansion coefficient between the substrate and the semiconductor inside the sapphire substrate or the semiconductor layer, and the semiconductor including the substrate. Layer warpage or the like may occur, and the characteristics of the element may be deteriorated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor light emitting device that can improve the light emission output emitted from the active layer and can be manufactured with high yield.

In order to achieve the above object, a semiconductor light emitting device according to the present invention includes an n-type semiconductor layer, a p-type semiconductor layer, and a p-side electrode connected to at least a part of the p-type semiconductor layer on a substrate. A semiconductor light emitting device comprising a first region having a second region having an n-type semiconductor layer and an n-side electrode connected to at least part of the n-type semiconductor layer, and a third region,
The third region is characterized in that the substrate is exposed and has a plurality of convex portions made of a semiconductor.
The semiconductor light emitting element preferably has a polygonal outer periphery when viewed from the electrode side, and the third region is located between the first region and the second region and at least one side of the outer periphery.
The first region and the second region are preferably surrounded by the third region.
Moreover, it is preferable that at least a part of the second region is adjacent to the third region.
The second region is preferably surrounded by the first region.
Moreover, it is preferable to have at least one convex part of the third region on an arbitrary straight line in a direction parallel to the surface having the semiconductor of the substrate.
Moreover, it is preferable that the convex part of a 3rd area | region has a metal film on the surface.
Further, the second region preferably has a plurality of convex portions made of a semiconductor in a region where the n-type semiconductor layer is exposed.
Moreover, it is preferable that the convex part of a 2nd area | region has a metal film on the surface.
Moreover, it is preferable that this convex part is tapered from the substrate side to the electrode side.

  As described above, the semiconductor light emitting device according to the present invention includes a first region having an n-type semiconductor layer, a p-type semiconductor layer, and a p-side electrode connected to the p-type semiconductor layer on a substrate, and n A semiconductor light emitting device comprising a second region having a n-type electrode connected to the n-type semiconductor layer and an n-type semiconductor layer, and a third region, wherein the third region has a substrate exposed; Since it has a plurality of convex portions made of a semiconductor, the light emission output is improved. In addition, since the warpage of the element can be reduced, the device can be manufactured with high yield.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a semiconductor light emitting device for embodying the technical idea of the present invention, and the present invention is not limited to the following.

FIG. 1 is a schematic plan view of a semiconductor light emitting device according to an embodiment of the present invention as viewed from the electrode arrangement surface side. FIG. 2 is a diagram schematically showing a partial cross section taken along line II ′ of FIG. As shown in FIG. 1, the semiconductor light emitting device of the present invention has an n-side electrode 7 and a p-side electrode 6 provided on the same surface side, and the electrode side is a light emission observation surface side.
As shown in FIG. 2, the semiconductor light-emitting device of the present invention includes an n-type semiconductor layer 2 and an active layer 3 on a substrate 1 through one or more layers (not shown) such as a buffer layer. The p-type semiconductor layer 4 is stacked in this order, the n-side electrode is connected to the n-type semiconductor layer 2, and the p-side electrode is connected to the p-type semiconductor layer 4.
The p-side electrode 6 is an electrode formed for connection to an external circuit. When the substrate side is mounted on a mounting substrate, the p-side electrode is connected to the external circuit by wire bonding or the like. Further, when the electrode arrangement surface side is mounted on the mounting substrate, the p-side electrode is connected to the electrode of the external circuit via the eutectic layer (bump: Ag, Au, Sn, In, Bi, Cu, Zn, etc.). The
In the semiconductor light emitting device of the present invention, for example, the surface of the n-type semiconductor layer is exposed by removing a part of the p-type semiconductor layer and the active layer, and optionally the depth direction of the n-type semiconductor layer. ing. An n-side electrode 7 is formed on the exposed surface of the n-type semiconductor layer.

The semiconductor light-emitting device of the present invention may have a p-side current diffusion portion 5 between the p-side electrode 6 and the p-type semiconductor layer 4 as shown in FIG. The p-side current spreading part 5 is preferably a material having high conductivity. Further, the p-side current diffusion portion 5 has a small contact resistance or ohmic contact with the p-type semiconductor layer 4.
The p-side current diffusion unit 5 can be made of a material having high light transmittance in visible light (visible region). It is preferable that the p-side current diffusion portion 5 is made of such a material because light traveling through the semiconductor layer can be efficiently transmitted to the electrode arrangement surface side through the p-side current diffusion portion. The element can be preferably used, for example, when the substrate side is mounted on a mounting substrate. Examples of such a material include a metal thin film and a conductive oxide film. Examples of the metal thin film include a metal thin film in which Ni and Au are laminated in order from the p-type semiconductor layer 4 side, and a thin film of an alloy of Ni and Au. The conductive oxide film includes an oxide film containing at least one element selected from the group consisting of zinc (Zn), indium (In), tin (Sn), gallium (Ga), and magnesium (Mg). Is mentioned. Specifically, ITO (Sn doped In ₂ O ₃ ), In ₂ O ₃ , IFO (F doped In ₂ O ₃ ), SnO ₂ , ATO (Sb doped SnO ₂ ), FTO (F doped SnO ₂ ), CTO (Cd-doped SnO ₂ ), AZO (Al-doped ZnO), IZO (In-doped ZnO), GZO (Ga-doped ZnO) and the like can be mentioned, and ITO (indium tin oxide) can be preferably used.
The p-side current diffusion unit 5 can be made of a material having a high reflectance with respect to light emitted from the semiconductor light emitting element. It is preferable that the p-side current diffusion portion 5 is made of such a material because light traveling in the semiconductor layer can be reflected by the p-side current diffusion portion. It can be preferably used when mounted on a mounting board. Specific examples of the material include a metal or alloy containing at least one selected from rhodium (Rh), aluminum (Al), and silver (Ag).
Note that the p-side current diffusion portion 5 described above is preferably formed so as to cover substantially the entire surface of at least the p-type semiconductor layer of the first region in the semiconductor light emitting device.

In the present invention, a semiconductor light emitting device is usually obtained by dividing a wafer obtained by forming a semiconductor layer, an electrode and the like on a substrate into a desired size.
Here, in the semiconductor light emitting device of the present invention, as viewed from the electrode arrangement surface side, the p-side electrode connected to at least a part of the n-type semiconductor layer, the p-type semiconductor layer, and the p-type semiconductor layer on the substrate. And a second region having an n-type semiconductor layer and an n-side electrode connected to at least a part of the n-type semiconductor layer, a substrate is exposed, and a plurality of semiconductors are formed. And a third region having a convex portion.
As shown in FIG. 2, among the semiconductor stacked structure including the n-type semiconductor layer and the p-type semiconductor layer on which the electrodes are formed, a region having a stacked structure including the n-type semiconductor layer to the p-type semiconductor layer is formed. A region 11 having a stacked structure including the exposed n-type semiconductor layer and the n-side electrode is referred to as a second region 12. Furthermore, the semiconductor light emitting device of the present invention has a third region 13 where the substrate is exposed, and a plurality of convex portions made of a semiconductor are provided in the third region.
With such a structure, the light emission output of the semiconductor light emitting device can be improved and the warpage of the device can be alleviated. Therefore, the process of dividing the wafer is facilitated and can be manufactured with high yield. .
One or more of the following (1) to (3) can be considered as the reason why the light emission output is improved by providing the convex portion in the third region. (1) The light emitted laterally outward from the semiconductor layer end faces of the first region and the second region is reflected or scattered by the plurality of convex portions of the third region, and the light is extracted to the emission observation surface side. ) Light guided in the substrate is taken into the convex portion of the third region from the substrate, light is extracted from the top of the convex portion or its side surface to the observation surface side, and (3) Guided in the substrate This is because light is diffusely reflected at the base of the convex portion (the connection portion between the substrate and the convex portion), and the light is extracted to the emission observation surface side.
Further, the reason why the warpage of the element can be alleviated is that the substrate is exposed in the third region 13, and in this region, tensile strain or compression due to the difference in lattice constant and thermal expansion coefficient between the substrate and the semiconductor. This is because the strain is reduced, and the bonding surface between the substrate and the semiconductor is cut off by the exposed region.

  Further, in general, the semiconductor light emitting element is formed so that the outer periphery of the element is a polygon as viewed from the light emission observation surface side, more preferably a rectangle, but the outer periphery of the element is thus a polygon. In this case, it is preferable that the third region 13 is located between the semiconductor layer provided in the first region 11 and the second region 12 and at least one side of the outer periphery. This is preferable because warpage can be alleviated as a whole in the vicinity of the outer periphery in the direction having the third region of the semiconductor light emitting device. In addition, by having the third region between the first region and the second region and the outer periphery of the element in this way, the one having the third region of the above element from the first region and the second region. Since the light emitted in the lateral direction toward one side of the outer periphery can be reflected and scattered by the convex portion of the third region, the light emitted in the vertical direction can be increased. As a result, the amount of light traveling toward the light emission observation surface increases, so that the light emission output is improved.

  Further, when the first region and the second region are arranged so as to be separated from the outer periphery of the element, and the third region is provided between the first region and the second region and the outer periphery of the element, all Since the light emitted in the outer peripheral direction from the first region and the second region of the semiconductor light emitting element hits the convex portion in the third region, the light emitted in the vertical direction can be increased. Further, the warpage can be alleviated uniformly in the vicinity of the entire outer periphery of the semiconductor light emitting device.

  When the first region and the second region are surrounded by the third region, the convex portion of the third region is preferably formed so as to surround the first region and the second region. By surrounding the first region and the second region with the convex portion of the third region, all the light emitted in the lateral direction from the first region and the second region of the semiconductor light emitting element in the outer circumferential direction is projected. Therefore, the light emitted in the vertical direction can be further increased.

In the semiconductor light emitting device of the present invention, it is preferable that at least one convex portion is arranged on an arbitrary straight line in a direction parallel to the surface of the substrate having the semiconductor. In other words, at least one of the convex portions is present on any straight line when the semiconductor light emitting element is viewed from the light emission observation surface side. Thereby, since the light from the first region and the second region hits the convex portion, the above-described effect of improving the light emission output becomes more remarkable. Furthermore, it is more preferable that two or more, preferably three or more convex portions are arranged on the above-described arbitrary straight line.
For example, as shown in FIG. 8, the width A of each convex portion is larger than the interval B between adjacent convex portions, and each convex portion is a substantially equilateral triangle like the convex portions 21a, 21b, and 21c. By arranging so as to be at the apex of the light, it is possible to efficiently reflect and scatter light.

  The convex section may have any shape such as a circle, rhombus, triangle, hexagon, etc., and the longitudinal section may have any shape such as a triangle, a rectangle, a trapezoid, a semicircle, etc. The convex part itself is preferably tapered from the substrate toward the electrode. In this case, the inclination angle of the convex portion (the angle formed between the side surface of the convex portion and the semiconductor layer lamination surface of the substrate) is, for example, 30 ° to 80 °, preferably 40 ° to 70 °, as shown in FIG. More preferably, it can be 45 ° to 50 °. As a result, the amount of light extracted from the region provided with the convex portion increases, so that more uniform light extraction can be achieved as a whole. Moreover, since the surface area of a convex part side surface increases, it is thought that light emission output improves. Furthermore, since the convex part gradually becomes thin, even when the upper surface of the convex part exists, the upper side of the convex part, that is, the surface area of the top part becomes narrow, so that it is taken into the convex part and totally reflected at the top part. It is thought that the reduction of the light that contributes to the improvement of the light emission output.

When viewed from the emission observation surface side, the convex portion in the third region has a surface area on the side surface of the convex portion that can change the traveling direction of light when the area of the interface between one convex portion and the substrate is reduced to provide a high density. Therefore, it is considered that the light in the vertical direction can be increased efficiently and the light emission output is improved. Note that the ratio of the area occupied by the area of the protrusions in the third region (specifically, the ratio of the area of the interface between the protrusions and the substrate in the third area) as viewed from the emission observation surface side is 20%. More preferably, it can be 30% or more, and more preferably 40% or more. The area of the interface between one convex portion and the substrate can be 3 to 300 μm ² , preferably 6 to 80 μm ² , and more preferably 12 to 50 μm ² .

The height of the convex portion provided in the third region may be at least enough to reflect light. Thereby, the light emission output is improved.
The top of the convex portion is preferably higher than the n-type semiconductor layer, and more preferably substantially the same height as the p-type semiconductor layer (see FIG. 1). In the case where an active layer is provided between the n-type semiconductor layer and the p-type semiconductor layer, the active layer is higher than the interface between the active layer and the n-type semiconductor layer adjacent to the active layer, and the apex portion is closer to the p-type semiconductor layer than the active layer. More preferably, it is positioned or substantially the same height as the p-type semiconductor layer. In this way, the surface area of the convex side surface increases, so that light emitted from the semiconductor layer in the lateral direction is likely to hit the convex side surface. Thereby, the light emitted from the semiconductor layer in the lateral direction is reflected or scattered by the convex portion, and the light traveling direction can be changed to the light emission observation surface side, so that the light emission output is improved.

Further, when the p-side current diffusion portion is provided between the p-side electrode and the p-type semiconductor layer, the convex portion of the third region can be substantially the same height as the p-side current diffusion portion. In this case, it is preferable that the convex part top part has the same material as the p-side current diffusion part. When the p-side current diffusion portion is a material that allows light to easily pass through, it becomes easy to extract light taken into the convex portion from the top of the convex portion to the outside. Further, when the p-side current diffusion portion is a material having a high reflectance with respect to the emitted light, the light is easily reflected at the top of the convex portion.
In such a case, the convex part top part and the p-side current diffusion part can be formed in the same process.

The protrusions in the third region may be subjected to a special process for forming the protrusions by growing a semiconductor layer on the exposed substrate. In order to divide the film, it is preferable to use a process of thinning a predetermined region. Specifically, for example, a resist film is applied to the surface of the semiconductor layer and exposed to a desired pattern, and the remaining resist film is used as a mask, and the convex portions of the first region, the second region, and the third region are formed. The part other than the region to be formed (a part of the third region) is removed by etching or the like until the substrate is exposed. As a result, it is possible to reduce the thickness of a predetermined region and to form the convex portion at the same time to divide the wafer, thereby simplifying the process. When removing by etching as described above, a mask having an opening of a predetermined shape such as a circle, a triangle, or a rectangle is formed on the surface of the semiconductor layer, and RIE (reactive ion etching) is performed using this mask. A convex part may be formed by, or a mask covering a predetermined shape may be formed, and the convex part may be formed using this mask.
The material of the mask is not particularly limited, and is not particularly limited to organic materials other than the resists described above, metals, oxides, and the like, but resists can be used because deterioration of the electrical characteristics of the element can be prevented. preferable.

  Thus, the convex part of the 3rd field formed using the process divided into each element is provided with the same lamination structure as the semiconductor lamination structure in the 1st field. However, the active layer included in the first region functions as a light emitting layer, but the active layer included in the convex portion of the third region does not function as a light emitting layer. This is because the convex portion of the third region is electrically insulated from the first region having the p-side electrode. The top of the convex portion in the third region may have the same material layer as the p-side electrode, but the convex portion in the third region is not electrically connected to an external circuit.

  The protrusions formed as described above have the same stacked structure as the semiconductor stacked structure in the first region. In other words, the protrusions are composed of a plurality of layers made of different materials. If the material of each layer is different, the refractive index of each layer is inevitably different, so that the direction of travel is changed by refracting light at the interface without being reflected by the protrusion, resulting in light emission. This is thought to contribute to the improvement of the light emission output to the observation surface.

  Further, a film made of a metal having a thickness that can reflect light emitted from the semiconductor light emitting element may be provided on the surface of the convex portion. Here, the surface of a convex part means the surface where the semiconductor of the convex part was exposed. Thereby, the light which goes to a convex part can be reflected with the metal of a convex part surface. As the metal material provided on the surface of the convex portion, it is preferable to use rhodium (Rh), aluminum (Al), silver (Ag), or the like, which has high reflectivity with respect to light emitted from the semiconductor light emitting element. In addition, when the metal and the p-side electrode and / or the n-side electrode provided on the surface of the convex portion are made of the same material, the reflectance can be improved in these electrodes and the electrode can be formed in the same process. The process can be simplified.

  In the semiconductor light emitting device of the present invention, as described above, a plurality of convex portions may be formed on a part of the surface of the second region, which is the exposed surface of the n-type semiconductor layer. The convex portion provided in the second region may be formed immediately below the n-side electrode, but is suitably formed in a region other than the region in which the n-side electrode is disposed in the second region. Thereby, since the light radiate | emitted to a vertical direction can be increased, the light emission output to the light emission observation surface side can be improved as a result. In particular, the protrusion provided in the second region is preferably formed between the n-side electrode of the semiconductor light emitting element and the first region, as shown in FIGS. In particular, since the end face of the first region facing the n-side electrode 7 is relatively strong in light emission, by providing a convex portion between the n-side electrode 7 and the first region, the light emitted from this end face can be reduced. Since the projection can be taken out to the light emission observation surface side, the light emission output can be further improved. Further, light absorption at the n-side electrode in the second region can be prevented. In addition, by providing the above-described protrusions in the second region, the end surface of the semiconductor layer in the first region is no longer perpendicular to the end surface of the semiconductor layer in the first region, as shown in FIGS. In the case where one exists, it is possible to prevent light emitted in the lateral direction from the end face of the semiconductor layer in the first region from being taken into the semiconductor layer in the first region again. In particular, as shown in FIG. 6, when the second region is surrounded by the first region, the above effect becomes more remarkable.

In the semiconductor light emitting device of the present invention, when a plurality of convex portions are formed in the second region, a part of the first region is removed to the same height as the n-type semiconductor layer exposed in the second region, for example. Then, a plurality of convex portions may be provided on the surface of the n-type semiconductor layer that is exposed by the removal.
In the semiconductor light emitting device shown in FIG. 5, the semiconductor multilayer structure provided in the first region located between the n-side electrode and the p-side electrode is on an extension line II-II ′ connecting the n-side electrode and the p-side electrode. In FIG. 2, a constricted portion is provided from the n-side electrode side, and a plurality of convex portions are provided in the constricted portion where the surface of the n-type semiconductor layer is exposed as the second region. Usually, the current mainly flows through the extension line II-II ′. In this semiconductor light emitting device, a part of the extension line II-II ′ in the first region is intentionally removed and the n-type semiconductor in the removal region is removed. By providing a plurality of convex portions on the layer, as a result, light emission output and light directivity control can be effectively improved. By removing a part on the straight line II-II ′, the current can be spread over a wider region of the semiconductor multilayer structure, and the active layer in the region removed from the extended line of II-II ′ It is considered that relatively strong light emitted from the end surface of the semiconductor multilayer structure including can be effectively extracted to the observation surface side.

  The following (1) to (3) can be considered as the reason why the light emission output to the light emission observation surface side is improved by providing the convex portion in the second region. That is, (1) light guided in an n-type semiconductor layer (for example, n-side contact layer) is taken into the convex portion from the n-side contact layer, and light is emitted from the top portion of the convex portion or in the middle thereof (2) The light emitted from the end face of the active layer to the outside of the side surface is reflected or scattered by a plurality of convex portions, and the light is extracted to the emission observation surface side. (3) In the n-side contact layer This is because the guided light is irregularly reflected at the root of the convex portion (the connection portion between the n-side contact layer and the convex portion), and the light is extracted to the emission observation surface side.

  The shape, size, and the like of the convex portions provided in the second region are not particularly limited, but can be the same as the convex portions provided in the third region.

  Hereinafter, other configurations of the semiconductor light emitting device 10 of the present invention will be described in detail.

(Substrate 1)
As a substrate for forming the semiconductor light emitting device of the present invention, for example, a known insulating substrate or conductive substrate such as sapphire, spinel, SiC, GaN, GaAs or the like can be used. Of these, a sapphire substrate is preferable.

(N-type semiconductor layer 2, p-type semiconductor layer 4)
The n-type semiconductor layer 2 and the p-type semiconductor layer 4 are not particularly limited. For example, gallium nitride-based compound semiconductors such as InXAlYGa1-X-YN (0 ≦ X, 0 ≦ Y, X + Y ≦ 1) Are preferably used. Each of these semiconductor layers may have a single layer structure, but may have a laminated structure of layers having different compositions and film thicknesses, a superlattice structure, or the like. Further, the active layer 3 may be provided between the n-type semiconductor layer 2 and the p-type semiconductor layer 4. The active layer is preferably a single quantum well or multiple quantum well structure in which thin films that produce quantum effects are stacked.

  In general, such a semiconductor layer may be configured as a homostructure, a heterostructure, a double heterostructure having a MIS junction, a PIN junction, or a PN junction. The semiconductor layer can be formed by a known technique such as MOVPE, metal organic chemical vapor deposition (MOCVD), hydride vapor deposition (HVPE), molecular beam epitaxy (MBE), or the like. Further, the thickness of the semiconductor layer is not particularly limited, and various thicknesses can be applied.

  As the laminated structure of the semiconductor layer, for example, a buffer layer made of AlGaN, an undoped GaN layer, an n-side contact layer made of Si-doped n-type GaN, a superlattice layer in which GaN layers and InGaN layers are alternately laminated, An active layer having a multiple quantum well structure in which GaN layers and InGaN layers are alternately stacked, a superlattice layer in which Mg-doped AlGaN layers and Mg-doped InGaN layers are alternately stacked, a p-side contact layer made of Mg-doped GaN, Etc.

(P-side electrode 6)
The p-side electrode 6 is preferably arranged so that a part of the surface of the p-type semiconductor layer 4 is exposed.
The shape of the p-side electrode 6 is not particularly limited, and may be various shapes such as a polygon such as a circle, a triangle, and a rectangle. The size of the p-side electrode 6 is not particularly limited, but is set to a size that enables mounting such as wire bonding, bumping, or eutectic bonding.
The kind and form of the material constituting the p-side electrode 6 are not particularly limited, and any material can be used as long as it is normally used as an electrode. For example, 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 (Cr), tungsten (W ), Lanthanum (La), copper (Cu), silver (Ag), gold (Au), yttrium (Y), and other metals, alloy single layer films or laminated films. Among them, those having low resistance are preferable, and specific examples include single layer films or laminated films of W, Rh, Ag, Pt, Pd, Al, and the like. Further, an ITO film having good adhesion to the p-type semiconductor layer 4 or the p-side current diffusion portion 5, for example, an ITO film as the p-side current diffusion portion 5 is provided between the p-side electrode 6 and the p-type semiconductor layer 4. In this case, specifically, a single layer film or a laminated film of W, Rh, and Pt is preferable. Moreover, the thing with favorable reflective characteristics, specifically, the single layer film or laminated film of Ag and Rh is preferable.

(N-side electrode 7)
As the n-side electrode 7, various types can be used in the same manner as the p-side electrode 6. The n-side electrode 7 may be made of the same material as the p-side electrode 6. In a structure in which the p-side electrode and the n-side electrode are on the same surface side as in the semiconductor light emitting device of the present invention, if the p-side electrode and the n-side electrode are made of the same material, the p-side electrode and the n-side electrode are processed in the same process. Can be formed. When the p-side electrode and the n-side electrode are formed in the same manufacturing process as described above, the manufacturing process is simplified, and an inexpensive and highly reliable semiconductor light emitting device can be obtained.

Example 1
The semiconductor light emitting device of this example will be described with reference to FIGS. FIG. 1 is a plan view of the semiconductor light emitting device of this embodiment as viewed from the electrode side. FIG. 2 is a partial cross-sectional view taken along line II ′ of FIG.
In the semiconductor light emitting device 10 of this example, a third region is provided between the first region and the second region and the outer periphery of the device, and the first region and the second region are surrounded by the third region. And in this 3rd field, a plurality of convex parts are formed. A part of the second region is adjacent to the third region.

  In this semiconductor light emitting device 10, a buffer layer (not shown) made of AlGaN and a non-doped GaN layer (not shown) are stacked on a sapphire substrate 1, and an n-type semiconductor layer 2 is formed thereon with Si doping. An n-type contact layer made of GaN, a superlattice n-type clad layer in which GaN layers and InGaN layers are alternately laminated are laminated, and further, a barrier layer made of undoped GaN and then made of InGaN. As the active layer 3 and the p-type semiconductor layer 4 having a multiple quantum well structure formed by repeatedly laminating the second barrier layer made of undoped GaN with the first barrier layer made of InGaN with the well layer, Mg A superlattice p-type cladding layer in which doped AlGaN layers and Mg-doped InGaN layers are alternately stacked, and a p-type contact layer made of Mg-doped GaN are in this order. Which are stacked.

In a part of the n-type semiconductor layer 2, the active layer 3 and the p-type semiconductor layer 4 stacked thereon are removed, and a part of the n-type semiconductor layer 2 itself in the thickness direction is removed. An n-side electrode 7 is formed on the exposed n-type semiconductor layer 2.
On the p-type semiconductor layer 3, a p-side current diffusion portion 5 made of ITO and a p-side electrode 6 are formed. The p-side current diffusion portion 5 is formed on almost the entire surface of the p-type semiconductor layer 4, and the p-side electrode 6 is formed on a part of the p-side current diffusion portion 5.

The semiconductor light emitting device of Example 1 was manufactured by the following manufacturing method.
<Formation of semiconductor layer>
Using a MOVPE reactor on a 2-inch φ sapphire substrate 1, a buffer layer made of Al _0.1 Ga _0.9 N is 100 mm, a non-doped GaN layer is 1.5 μm, and an n-type semiconductor layer 2 is Si-doped. An n-type contact layer made of GaN is 2.165 μm, a superlattice n-type cladding layer in which a GaN layer (40 cm) and an InGaN layer (20 cm) are alternately stacked 10 times is 640 mm, and the undoped first has a film thickness of 250 mm. A barrier layer made of GaN, followed by a well layer made of In _0.3 Ga _0.7 N having a thickness of 30 と, and a first barrier layer and film made of In _0.02 Ga _0.98 N having a thickness of 100 Å An active layer 3 having a multi-quantum well structure (total film thickness of 1930 mm) formed by alternately stacking six second barrier layers made of undoped GaN having a thickness of 150 mm, a p-type nitride half As the body layer 4, Mg-doped _{the Al} 0.1 _{Ga 0.9} N _layer, (40 Å) and Mg-doped InGaN layer (20 Å) and 0.2μm superlattice p-type cladding layer formed by laminating 10 times alternately, Mg A p-type contact layer made of doped GaN is grown in this order with a film thickness of 0.5 μm to produce a wafer.
The obtained wafer is annealed in a reaction vessel at 600 ° C. in a nitrogen atmosphere to further reduce the resistance of the p-type cladding layer and the p-type contact layer.

<Etching>
After annealing, the wafer is removed from the reaction vessel, a mask having a predetermined shape is formed on the surface of the uppermost p-type contact layer, and etching is performed from above the mask with an etching apparatus to expose a part of the n-type contact layer.

<Formation of p-side current diffusion portion 5>
After removing the mask, a wafer was placed in the sputtering apparatus, and an oxide target made of a sintered body of In ₂ O ₃ and SnO ₂ was placed in the sputtering apparatus. An ITO film having a thickness of 1800 mm is formed as the p-side current diffusion portion 5 on almost the entire surface of the p-type contact layer 8 of the wafer by a sputtering apparatus.

<Formation of p-side electrode 6 and n-side electrode 7>
A mask having a predetermined pattern is formed on the p-side current diffusion portion 5 and the n-type contact layer, and Ti, Rh, and Au are laminated in this order on the p-side current diffusion portion 5 and the n-type contact layer. A p-side electrode 6 and an n-side electrode 7 each having a thickness of about 7000 mm are formed.

Next, using the resist film as a mask, etching is performed from above the mask with an etching apparatus, and etching is performed until the substrate is exposed except for the first region, the second region, and the region for forming the convex portion (a part of the third region). A plurality of protrusions are formed in the third region by removing at.
The semiconductor light emitting element 10 is obtained by dividing the obtained wafer at predetermined locations.

  The semiconductor light-emitting device of Example 1 formed as described above has improved light output as compared with the semiconductor light-emitting device not provided with the above-described convex portion, and can reduce the warpage of the device, thereby improving the yield. To do.

Example 2
The semiconductor light emitting device of this embodiment will be described with reference to FIGS. FIG. 3 is a plan view of the semiconductor light emitting device of this example as viewed from the electrode side. 4 is a partial cross-sectional view taken along the line II-II ′ of FIG.
The semiconductor light emitting device of this example is configured in the same manner as in Example 1 except that the semiconductor light emitting device of Example 1 includes a plurality of convex portions in the second region.

In the semiconductor light emitting device of this example, a plurality of convex portions are formed in a region other than the region where the n-side electrode 7 is disposed in the second region where the n-type semiconductor layer is exposed.
In this embodiment, the step of forming the convex portion of the second region can be performed simultaneously with the etching step for exposing a part of the n-type semiconductor layer of the first embodiment.

This semiconductor light emitting device effectively emits relatively strong light emitted from the end surface of the semiconductor multilayer structure including the active layer of the first region to the second region at the boundary between the first region and the second region toward the observation surface. It can be taken out. In addition, by providing a convex portion between the first region and the n-side electrode, the light emitted from the end face toward the n-side electrode can be reflected and scattered by the convex portion. Absorption of light at the electrode can be prevented.
Such a semiconductor light emitting device has a light emission output improved as compared with the semiconductor light emitting device of Example 1.

Example 3
The semiconductor light emitting device of this example will be described with reference to FIG. FIG. 5 is a plan view of the semiconductor light emitting device of this example as viewed from the electrode side.
The semiconductor light emitting device of this example is the same as the semiconductor light emitting device of Example 2 except that the shapes of the semiconductor layers in the first region and the second region are different.

In the semiconductor light emitting device of this example, as viewed from the electrode side, the semiconductor laminated structure provided in the first region located between the n-side electrode and the p-side electrode connects the n-side electrode and the p-side electrode. On the extension line II ′, there is a constricted portion from the n-side electrode side, and the second region is provided in the constricted portion where the surface of the n-type semiconductor layer is exposed as the second region. And the some convex part is provided in the surface of the n-type semiconductor layer exposed to the constriction part.
In this embodiment, the step of forming the constricted portion and the convex portion of the second region can be performed simultaneously with the etching step for exposing a part of the n-type semiconductor layer of the first embodiment.

  This semiconductor light emitting device can spread the current over a wider region of the semiconductor multilayer structure, and emits relatively from the end surface of the semiconductor multilayer structure including the active layer in the region removed from the extension line II-II ′. Since strong light can be effectively extracted to the observation surface side, the light emission output is further improved as compared with the semiconductor light emitting device of Example 1.

  The semiconductor light-emitting elements shown in Examples 1 to 3 have a configuration in which the outer shape is rectangular when viewed from the electrode side, and an n-side electrode and a p-side electrode are arranged at substantially the center of both ends in the longitudinal direction. However, the present invention is not limited to this. For example, an n-side electrode and a p-side electrode may be arranged on a rectangular diagonal.

Example 4
The semiconductor light emitting device of this example will be described with reference to FIGS. FIG. 6 is a plan view of the semiconductor light emitting device of this example as viewed from the electrode side. FIG. 7 is a partial cross-sectional view taken along line III-III ′ of FIG.
The semiconductor light emitting device of this example is the same as that of Example 2 except that the outer shape of the device is different from that of the semiconductor light emitting device of Example 2.
As shown in FIG. 6, the p-side electrode 6 in the first region and the n-side electrode 7 in the second region are provided with extending portions extending from respective parts. Thereby, current can be efficiently injected into the entire semiconductor layer in the first region, and light can be emitted efficiently.

In the semiconductor light emitting device of the present invention, the second region is surrounded by the first region when viewed from the electrode side. Further, the first area is surrounded by the third area.
In this semiconductor light emitting device, light emitted laterally from the semiconductor side surface of the first region to the second region, light traveling laterally from the semiconductor layer of the first region into the n-type semiconductor layer of the second region, The light can be reflected by the convex portion of the second region and taken out to the emission observation surface side. Further, light emitted in the lateral direction from the side surface of the semiconductor layer in the first region to the third region can be reflected by the convex portion in the third region and extracted to the light emission observation surface side.
Also in this semiconductor light emitting device, the light emission output is improved and the warpage of the device can be reduced, so that the yield is improved.

It is a top view which shows typically one Embodiment of the semiconductor light-emitting device in this invention. FIG. 2 is a partial cross-sectional view taken along line I-I ′ of FIG. 1. It is a top view which shows typically other embodiment of the semiconductor light-emitting device in this invention. FIG. 4 is a partial cross-sectional view taken along line II-II ′ in FIG. 3. It is a top view which shows typically other embodiment of the semiconductor light-emitting device in this invention. It is a top view which shows typically other embodiment of the semiconductor light-emitting device in this invention. FIG. 7 is a partial cross-sectional view taken along line III-III ′ in FIG. 6. It is a top view which shows the example of arrangement | positioning of the some convex part provided in a 3rd area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sapphire substrate 2 n-type semiconductor layer 3 active layer 4 p-type semiconductor layer 5 p-side current diffusion part 6 p-side electrode 7 n-side electrode 10 semiconductor light emitting device 11 first region 12 second region 13 third region 21, 22 convex Part

Claims (9)

A first region having an n-type semiconductor layer, a p-type semiconductor layer, and a p-side electrode connected to the p-type semiconductor layer in order on the substrate, and the n-type exposed by removing the p-type semiconductor layer a second region having a semiconductor layer and the n-type semiconductor layer n-side electrode connected onto the exposed surface of, and a third region as viewed from the electrode arrangement surface surrounding the first region and the second region A semiconductor light emitting device comprising:
The third region, together with the substrate is exposed, have a plurality of protrusions made of a semiconductor,
The second region has a plurality of semiconductor convex portions on the exposed surface of the n-type semiconductor layer, and the convex portions are located between the n-side electrode and the first region when viewed from the electrode placement surface side. A semiconductor light emitting element characterized by being positioned . The semiconductor light emitting element has a polygonal outer periphery when viewed from the electrode arrangement surface side, and the third region is located between the first region and the second region and at least one side of the outer periphery. The semiconductor light emitting device according to claim 1. The second region, the semiconductor light emitting device according to claim 1 or 2, characterized in that at least part of which is adjacent to the third region. The second region, the semiconductor light emitting device according to any one of claims 1 to 3, characterized in that it is surrounded by the first region. The arbitrary straight line on a semiconductor surface in a direction parallel with the said substrate, the semiconductor light-emitting device according to any one of claims 1 to 4, characterized in that it has at least one convex portion of the third region. The convex portion of the third region, the semiconductor light emitting device according to any one of claims 1 to 5, wherein a metal film on the surface. The convex portion of the second region, the semiconductor light emitting device according to any one of claims 1 to 6, wherein a metal film on the surface. The convex portion is a semiconductor light emitting device according to any one of claims 1 to 7, characterized in that is tapered toward the substrate side toward the electrode. 9. The semiconductor light emitting device according to claim 1, further comprising a p-side current diffusion portion between the p-side electrode and the p-type semiconductor layer.

Images