JP2006173533A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device that can efficiently takes out light from a face-up mounted semiconductor light emitting element. <P>SOLUTION: The light emitting device is provided with the semiconductor light emitting element 100 in which a p-layer and an n-layer are laminated upon another and a p-electrode electrically connected to the p-layer and an n-electrode electrically connected to the n-layer are formed on the same surface. The light emitting element 100 is mounted on a mounting member having circuits respectively electrically connected to the p- and n-electrodes with the electrodes on the upside. The p- and n-electrodes are connected to the circuits of the mounting member through conductive wires. The light emitting element 100 has a slope from the p-layer to the n-layer and the surface of the slope is constituted in a recessed and projecting structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting element used in a light emitting device. In particular, the present invention relates to a light emitting device that improves light extraction from a light emitting element face-up mounted on a mount member to the observation surface side.

  A light-emitting diode including a nitride semiconductor in a layer structure is widely used as a high-luminance pure green light-emitting LED or blue light-emitting LED in various fields such as a full-color LED display, a traffic signal lamp, and a backlight.

These LEDs generally have a structure in which an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer are sequentially stacked on a substrate such as sapphire. Furthermore, a p-side electrode is disposed on the p-type nitride semiconductor layer, and an n-side electrode is disposed on the n-type nitride semiconductor layer. For example, when the p-side electrode and the n-side electrode are provided on the same surface side, the p-side electrode is disposed on the p-type nitride semiconductor layer, and the p-type nitride semiconductor layer, the active layer, and the n-type nitridation are provided. A part of the physical semiconductor layer is removed by etching or the like, and the n-side electrode is arranged on the exposed n-type nitride semiconductor layer. Further, various LED structures have been proposed for the purpose of improving light extraction (for example, Patent Documents 1 and 2).
JP20046662 JP2004-221529

  However, the conventional structure has a problem in that light reaching the side surface of the light-emitting element mounted face-up cannot be extracted efficiently.

  Accordingly, an object of the present invention is to provide a light emitting device capable of efficiently extracting light from a semiconductor light emitting element mounted face up.

  In order to achieve the above object, a light-emitting device according to the present invention includes a p-layer and an n-layer stacked and electrically connected to a p-electrode and the n-layer electrically connected to the p-layer. A semiconductor light emitting device having n electrodes formed on the same surface, and the semiconductor light emitting device mounted on a mounting member having a circuit electrically connected to each of the p electrode and the n electrode, The p electrode and the n electrode are connected to the circuit of the mount member via a conductive wire, and the semiconductor light emitting element has a slope from the p layer to the n layer, and the slope has a surface uneven structure. It is characterized by comprising.

  The light emitting device according to the present invention can efficiently extract light reaching the side surface of the light emitting element mounted face up.

Various nitride semiconductors can be used as each semiconductor layer constituting the light emitting element disposed in the light emitting device according to the present invention. Specifically, In _X Al _Y Ga _1- XYN (0 ≦ X, 0 ≦ Y, X + Y ≦) is formed on the substrate by metal organic vapor phase epitaxy (MOCVD), hydride vapor phase epitaxy (HVPE), or the like. A semiconductor in which a plurality of semiconductors such as 1) are formed is preferably used. In addition, the layer structure includes a homo structure having a MIS junction, a PIN junction or a PN junction, a hetero structure, or a double hetero structure. Each layer may have a superlattice structure, or may have a single quantum well structure or a multiple quantum well structure in which an active layer is formed in a thin film in which a quantum effect is generated.

  The light-emitting element is generally formed by growing each semiconductor layer on a specific substrate. At this time, an insulating substrate such as sapphire is used as the substrate. In this case, usually, both the p-side electrode and the n-side electrode are formed on the same surface side on the semiconductor layer. Of course, it is possible to mount the circuit board after finally removing the board. The substrate is not limited to sapphire, and a known member such as spinel, SiC, GaN, or GaAs can be used.

  Embodiments according to the present invention will be described below with reference to the drawings for nitride semiconductor light emitting devices. However, the embodiment described below exemplifies a light emitting device for embodying the technical idea of the present invention, and the present invention does not specify the light emitting device as follows.

(Embodiment 1)
FIG. 1 is a schematic plan view of a group III nitride compound semiconductor device 100 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view thereof. FIG. 3 is a cross-sectional view of a light emitting device using the group III nitride compound semiconductor element 100.

  The group III nitride compound semiconductor device 100 is a light emitting device having the following configuration. As shown in FIG. 1, each side has a width of 300 μm, a groove 150 having a zigzag shape around the light emitting element, an n-electrode 140 is formed in a part of the groove 150, and A transparent translucent electrode 110 is disposed on almost the entire surface of an island-like portion having a zigzag shape in the center, and a thick film p-electrode 120 for bonding a gold wire is disposed on a part of the translucent electrode 110.

Next, as shown in FIG. 2, an AlN buffer layer 102 made of aluminum nitride (AlN) and having a thickness of about 15 nm is formed on a sapphire substrate 101 having a thickness of about 300 μm. A non-doped GaN layer 103 is formed, and an n-type contact layer 104 (high carrier concentration n ⁺ layer) having a film thickness of about 5 μm made of GaN doped with silicon (Si) at 1 × 10 ¹⁸ / cm ³ is formed thereon. Has been.

On the n-type contact layer 104, an n-type cladding layer 105 having a thickness of about 25 nm made of Al _0.15 Ga _0.85 N doped with silicon (Si) at 1 × 10 ¹⁸ / cm ³ is formed. . Further thereon, three pairs of a well layer made of non-doped In _0.2 Ga _0.8 N having a thickness of about 3 nm and a barrier layer made of non-doped GaN having a thickness of about 20 nm are stacked to form a light emitting layer 106 having a multiple quantum well structure. Has been.

Further, a p-type cladding layer (first p layer) 107 made of p-type Al _0.15 Ga _0.85 N having a film thickness of about 25 nm doped with 2 × 10 ¹⁹ / cm ^{3 of} Mg is formed on the light emitting layer 106. Has been. On the p-type cladding layer 107, a p-type contact layer (second p layer) 108 made of p-type GaN having a thickness of about 100 nm doped with 8 × 10 ¹⁹ / cm ^{3 of} Mg is formed.

  A translucent electrode 110 formed by metal deposition is formed on the p-type contact layer (second p layer) 108, and an n-electrode 140 is formed on the n-type contact layer 104. The translucent electrode 110 includes a first layer made of cobalt (Co) having a thickness of about 5 nm and a second layer made of gold (Au) having a thickness of about 10 nm bonded to the cobalt film.

  The thick p-electrode 120 is formed by sequentially forming a first layer 123 made of gold (Au) with a thickness of about 1500 nm and a second layer 124 made of aluminum (Al) with a thickness of about 10 nm on the translucent electrode 110. It is configured by stacking.

  The n-electrode 140 having a multilayer structure is composed of a first layer made of vanadium (V) with a thickness of about 20 nm and aluminum (Al) with a thickness of about 100 nm from above a part of the n-type contact layer 104 that is partially exposed. It is configured by laminating the second layer.

Further, a protective film made of a SiO ₂ film may be formed on the uppermost portion except for the upper portions of the n-electrode 140 and the p-electrode 120 if necessary. A reflective metal layer made of aluminum (Al) with a film thickness of about 500 nm may be formed on the lowermost part on the outer side corresponding to the bottom surface of the sapphire substrate 101 by metal deposition. The reflective metal layer may be a metal such as Rh, Ti, or W, or a nitride such as TiN or HfN.

The group III nitride compound semiconductor device 100 having the above-described configuration was manufactured as follows. Group III nitride compound semiconductor device 100 was manufactured by metal organic vapor phase epitaxy (hereinafter abbreviated as “MOVPE”). The gases used were ammonia (NH ₃ ), carrier gas (H ₂ and N ₂ ), trimethylgallium (Ga (CH ₃ ) ₃ ) (hereinafter referred to as “TMG”), trimethylaluminum (Al (CH ₃ ) ₃ (Hereinafter referred to as “TMA”), trimethylindium (In (CH ₃ ) ₃ ) (hereinafter referred to as “TMI”), silane (SiH ₄ ) and cyclopentadienyl magnesium (Mg (C ₅ H ₅ ) ₂ ) (Hereinafter referred to as “CP ₂ Mg”).

First, a single crystal sapphire substrate 101 whose main surface is an A surface cleaned by organic cleaning and heat treatment is mounted on a susceptor mounted in a reaction chamber of an MOVPE apparatus. Next, the sapphire substrate 101 was baked at a temperature of 1100 ° C. while flowing H ₂ into the reaction chamber at normal pressure.

Next, the temperature of the sapphire substrate 101 was lowered to 400 ° C., and H ₂ , NH ₃ and TMA were supplied to form the AlN buffer layer 102 with a thickness of about 15 nm.

Next, the temperature of the sapphire substrate 101 was maintained at 1150 ° C., H ₂ , NH ₃ , and TMG were supplied, and the non-doped GaN layer 103 was formed thereon. Next, H ₂ , NH ₃ , TMG and silane are supplied, and n-type contact layer 104 (high carrier) having a film thickness of about 5 μm made of GaN doped with silicon (Si) at 1 × 10 ¹⁸ / cm ³ thereon. Density n ⁺ layer).

Thereafter, the supply amount of H ₂ , NH ₃ , TMG, TMA, and silane is controlled, and an n _0.15 Ga _0.85 N film made of Al _0.15 Ga _0.85 N doped with silicon (Si) at 1 × 10 ¹⁸ / cm ³ is formed. A mold cladding layer 105 was formed.

Next, the temperature of the sapphire substrate 101 is lowered to 825 ° C., and the supply amount of N ₂ or H ₂ , NH ₃ , TMG, and TMI is controlled to comprise about 3 nm of non-doped In _0.2 Ga _0.8 N. A light emitting layer 106 having a multiple quantum well structure was formed by laminating three pairs of well layers and barrier layers made of non-doped GaN having a thickness of about 20 nm.

Next, the temperature of the sapphire substrate 101 is maintained at 1050 ° C., and N ₂ or H ₂ , NH ₃ , TMG, TMA and CP ₂ Mg are supplied while being controlled, and Mg is doped 2 × 10 ¹⁹ / cm ³ . A p-type cladding layer (first p layer) 107 made of p-type Al _0.15 Ga _0.85 N having a thickness of about 25 nm was formed. Next, N ₂ or H ₂ , NH ₃ , TMG and CP ₂ Mg are supplied while being controlled, and a p-type contact layer made of p-type GaN having a thickness of about 100 nm doped with 8 × 10 ¹⁹ Mg (the second type) p layer) 108 was formed.

  With respect to the sapphire substrate (hereinafter referred to as a wafer) that has undergone the above crystal growth process, a photoresist is applied to the entire surface of the wafer, and the outermost periphery of the group III nitride compound semiconductor device 100 is formed in a zigzag shape by photolithography. The photoresist was removed to form a window, and at the same time, the portion of the photoresist where the n-electrode 140 was to be formed was removed to form a window.

  Subsequently, the group III nitride compound semiconductor p-type contact layer (second p layer) 108, the p-type cladding layer 107, the active layer 106, the n-type cladding layer 105, and the window portion not covered with the photoresist, A part of the n-type contact layer 104 is etched by ion etching so as to form an uneven side surface 160 having an angle of α = 60 degrees, and the outermost peripheral portion of the group III nitride compound semiconductor device 100 is zigzag. The n-type contact layer 104 was exposed so as to have a shape, and at the same time, the portion of the n-type contact layer 104 where the n-electrode 140 was formed was exposed.

  Next, cobalt (Co) having a film thickness of about 5 nm and gold (Au) having a film thickness of about 10 nm were sequentially deposited on the entire surface of the wafer. Subsequently, a photoresist was applied to the entire surface of the wafer, and a photoresist was formed on a portion where the translucent electrode 110 was formed by photolithography. Thereafter, the exposed laminated film of cobalt (Co) and gold (Au) is removed by etching, and cobalt (Co) and gold are formed on the p-type contact layer (second p layer) 108 as the translucent electrode 110. A (Au) laminated film was formed.

  Next, a photoresist was applied to the entire surface of the wafer, a portion of the photoresist where the thick p-electrode 120 was to be formed was removed by photolithography, a window was formed, and the translucent electrode 110 was exposed. Subsequently, gold (Au) having a thickness of about 1500 nm and aluminum (Al) having a thickness of about 10 nm were deposited in this order. Thereafter, the gold (Au) / aluminum (Al) multilayer film on the photoresist is removed together with the photoresist, and a gold (Au) / aluminum (Al) multilayer film is formed as the thick p-electrode 120 on the translucent electrode 110. Formed.

Next, a photoresist was applied to the entire surface of the wafer, a portion of the photoresist where the n-electrode 140 was to be formed was removed by photolithography to form a window, and the n-type contact layer 104 was exposed. Subsequently, vanadium (V) with a thickness of about 20 nm and aluminum (Al) with a thickness of about 100 nm were deposited in this order. Thereafter, the laminated film of vanadium (V) and aluminum (Al) on the photoresist is removed together with the photoresist, and a vanadium (V) / aluminum (Al) laminated film is formed as an n electrode 140 on the n-type contact layer 104. did.
Next, the wafer is heat-treated in an O 2 atmosphere at 500 ° C. for about 5 minutes, and the n-type contact layer 104 and the n-electrode 140, and the p-type contact layer 108 and the translucent electrode 110 are alloyed to ensure ohmic connection. did.

Next, a 150 nm SiO2 film was formed on the entire wafer surface. Subsequently, a photoresist was applied to the entire surface of the wafer, and the photoresist was removed from the thick p-electrode 120 and n-electrode 140 portions by photolithography to form windows and to expose the SiO2 film. Thereafter, the portion of the SiO2 film not covered with the photoresist was removed by wet etching to expose the thick p-electrode 120 and the n-electrode 140, and an SiO2 film was formed as the protective film 130 of the translucent electrode 110.

  Thereafter, the individual light emitting element portions are separated by dicing.

  As described above, the face-up type III-nitride compound semiconductor device 100 for extracting light from the semiconductor layer side was manufactured.

  Next, FIG. 3 shows a light emitting device 200 using the semiconductor element 100 manufactured as described above. The group III nitride compound semiconductor element 100 is fixed to the center of the recess of the resin case 210 having the reflector portion 220 with a silver paste 240, and the p-side electrode 211 formed on the resin case 210 and the group III nitride compound semiconductor element 100 p-electrodes 120, n-side electrode 212 formed on the resin case, and n-electrode 140 of group III nitride compound semiconductor device 100 were electrically connected and fixed by gold wires 250, respectively. And the sealing material 230, such as a silicone resin which is a transparent material, was filled in the recessed part of the resin case, and the light-emitting device 200 which protected the group III nitride compound semiconductor element 100 and the gold wire 250 was manufactured.

  According to the light emitting device 200 according to the first embodiment of the present invention, light is diffused on the side surface 160 in order to form the zigzag unevenness that is the side surface 160 of the groove 150 of the group III nitride compound semiconductor element 100. In addition, since the angle α of the side surface 160 is 60 degrees, the light reaching the side surface 160 is not totally reflected and is extracted outside the light emitting element. And since the uneven surface which becomes a zigzag which becomes a reflective surface exists also on the opposite side of the groove | channel 150, it becomes possible to extract light to the light emission observation surface side efficiently.

Note that the shape of the group III nitride compound semiconductor device 100 shown in the embodiment is not particularly limited. For example, the zigzag of the groove 150 provided in the light emitting element 100 can be replaced with a wave shape. The angle α of the side surface 160 is not limited to 60 degrees, but is preferably 55 degrees or more and less than 90 degrees, and more preferably 55 degrees or more and 70 degrees. This is because if the angle is smaller than 55 degrees, the light is totally reflected on the side surface and the light cannot be extracted, and if it exceeds 70 degrees, the extracted light may be taken into the light emitting element again.
(Embodiment 2)
FIG. 4 shows a schematic plan view of a group III nitride compound semiconductor device 300 according to the second embodiment of the present invention.

  The group III nitride compound semiconductor device 300 is manufactured in the same manner as the group III nitride compound semiconductor device 100 except that a connecting portion 330 that connects the surrounding residual portion 320 and the central island portion 310 is formed. .

  According to the group III nitride compound semiconductor device 200 according to the second embodiment of the present invention, since the connecting portion 330 is formed, until the p-layer side of many light emitting devices formed on the same substrate is separated. Since they are electrically connected, they are not charged at the portions that become individual light emitting elements, and the pn interface is less likely to be electrostatically destroyed.

FIG. 1 is a plan view of a semiconductor light emitting element according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the semiconductor light emitting element according to the first embodiment of the present invention. FIG. 3 is a sectional view of the light emitting device according to the first embodiment of the present invention. FIG. 4 is a plan view of a semiconductor light emitting element according to the second embodiment of the present invention.

Explanation of symbols

100, 300 Light-emitting element 120 p-electrode 140 n-electrode 150 groove 200 light-emitting device

Claims (4)

In the light emitting device,
a semiconductor light emitting element in which a p layer and an n layer are stacked, and a p electrode electrically connected to the p layer and an n electrode electrically connected to the n layer are formed on the same surface;
The semiconductor light emitting device is mounted on a mount member having a circuit electrically connected to each of the p electrode and the n electrode with the electrode as an upper surface, and the p electrode and the n electrode are mounted on the circuit of the mount member. Connected through conductive wires,
The semiconductor light emitting device has a slope from the p layer to the n layer, and the slope has a surface uneven structure.
A light emitting device characterized by that.   The light emitting device according to claim 1, wherein the slope of the semiconductor light emitting element is formed in a groove shape.   The light emitting device according to claim 1, wherein the concavo-convex structure has a sawtooth shape extending in a front and back direction.   4. The light emitting device according to claim 1, wherein the inclined surface of the semiconductor light emitting element has an angle of 55 degrees or more and 70 degrees or less.

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