CN102217101A - Group-iii nitride semiconductor light emitting device - Google Patents

Abstract

The present invention relates to a group III nitride semiconductor light emitting device, more specifically to the following group III nitride semiconductor light emitting device: it includes a substrate; a plurality of group III nitride semiconductor layers, including a group III nitride semiconductor layer formed on the substrate a first nitride semiconductor layer having a first conductivity type on it, a second nitride semiconductor layer having a second conductivity type different from the first conductivity type formed on the first nitride semiconductor layer, and an active layer that is located between the first and second nitride semiconductor layers and that generates light by recombination of electrons and holes; and is formed from the substrate to the plurality of group III nitride semiconductor layers and has a first openings of the first and second scattering surfaces. The first scattering surface scatters light generated in the active layer, and the second scattering surface has a different inclination from the first scattering surface.

Description

Group III Nitride Semiconductor Light-Emitting Devices

technical field

The present invention mainly relates to a group III nitride semiconductor light emitting device, and more specifically, to a group III nitride semiconductor light emitting device including a substrate in which a scattering region is formed to improve light extraction efficiency. efficiency). The III-nitride semiconductor light-emitting device refers to a device made of Al(x)Ga(y)In(1-x-y)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) Light-emitting devices such as light-emitting diodes composed of compound semiconductor layers, the Group III nitride semiconductor light-emitting devices may also include materials composed of other group elements (such as SiC, SiN, SiCN and CN), and semiconductors made of these materials layer.

Background technique

This section provides background information related to the present disclosure which is not necessarily prior art.

FIG. 1 is a view of one example of a conventional group III nitride semiconductor light emitting device. The III-nitride semiconductor light-emitting device includes a substrate 100, a buffer layer 200 grown on the substrate 100, an n-type III-nitride semiconductor layer 300 grown on the buffer layer 200, and an n-type III-nitride semiconductor layer grown on the n-type III-nitride semiconductor layer. The active layer 400 on the layer 300, the p-type group III nitride semiconductor layer 500 grown on the active layer 400, the p-side electrode 600 formed on the p-type group III nitride semiconductor layer 500, the p-side electrode 600 formed on the p-side electrode The p-side pad 700 on 600, the n-side electrode 800 formed on the n-type group III nitride semiconductor layer 300 exposed by mesa etching the p-type group III nitride semiconductor layer 500 and the active layer 400, and the Selected protective film 900.

As for the substrate 100, a GaN substrate can be used as a homogeneous substrate. A sapphire substrate, SiC substrate, or Si substrate can be used as the heterogeneous substrate. However, any type of substrate on which a nitride semiconductor layer can be grown may be used. In the case of using a SiC substrate, n-side electrode 800 may be formed on the surface of the SiC substrate.

The nitride semiconductor layer epitaxially grown on the substrate 100 is generally grown using metal organic chemical vapor deposition (MOCVD).

的AlN缓冲层的技术。另外，美国专利第5,290,393号描述了一种于200℃～900℃下在蓝宝石衬底上生长厚度为

的Al(x)Ga(1-x)N(0≤x＜1)缓冲层的技术。此外，美国专利申请公开第2006/154454号描述了一种在600℃～990℃下生长SiC缓冲层(晶种层)，以及在其上生长In(x)Ga(1-x)N(0＜x≤1)的技术。优选地，在生长n型III族氮化物半导体层300之前应生长未掺杂的GaN层。可以将其看作缓冲层200或n型III族氮化物半导体层300的一部分。The buffer layer 200 serves to overcome differences in lattice constant and thermal expansion coefficient between the heterogeneous substrate 100 and the nitride semiconductor layer. US Patent No. 5,122,845 describes a sapphire substrate grown at 380°C to 800°C with a thickness of

AlN buffer layer technology. In addition, U.S. Patent No. 5,290,393 describes a method of growing on a sapphire substrate at 200°C to 900°C with a thickness of

Al(x)Ga(1-x)N(0≤x<1) buffer layer technology. In addition, US Patent Application Publication No. 2006/154454 describes a method of growing a SiC buffer layer (seed layer) at 600°C to 990°C, and growing an In(x)Ga(1-x)N(0 <x≤1) technology. Preferably, an undoped GaN layer should be grown before growing the n-type group III nitride semiconductor layer 300 . It can be regarded as a part of the buffer layer 200 or the n-type group III nitride semiconductor layer 300 .

In the n-type nitride semiconductor layer 300, at least the n-side electrode 800 formation region (n-type contact layer) is doped with a dopant. In some embodiments, the n-type contact layer is made of GaN doped with Si. US Patent No. 5,733,796 describes a technique of doping an n-type contact layer at a target doping concentration by adjusting a mixing ratio of Si and other source materials.

The active layer 400 generates photons by recombination of electrons and holes. For example, the active layer 400 contains In(x)Ga(1-x)N (0<x≦1) and has a single quantum well layer or multiple quantum well layers.

The p-type nitride semiconductor layer 500 is doped with a suitable dopant such as Mg, and has p-type conductivity through an activation process. US Patent No. 5,247,533 describes a technique for activating a p-type nitride semiconductor layer by electron beam irradiation. Furthermore, US Patent No. 5,306,662 describes a technique of activating a p-type nitride semiconductor layer by annealing at higher than 400°C. U.S. Patent Application Publication No. 2006/157714 describes growing a p-type nitride semiconductor layer by using ammonia and hydrazine-based source materials together as nitrogen precursors, thereby making the p-type nitride semiconductor layer have p type conductivity technology.

The p-side electrode 600 is provided to facilitate current supply to the p-type nitride semiconductor layer 500 . U.S. Patent No. 5,563,422 describes a technology related to a light-transmitting electrode composed of Ni and Au, formed on almost the entire surface of a p-type nitride semiconductor layer 500, and connected to a p-type nitride semiconductor layer 500. The nitride semiconductor layer is in 500-ohm contact. In addition, US Patent No. 6,515,306 describes a technique of forming an n-type superlattice layer on a p-type nitride semiconductor layer, and forming a light-transmitting electrode made of indium tin oxide (ITO) thereon.

The p-side electrode 600 may be formed so thick that it does not transmit light to reflect light toward the substrate 100 . This technology is called flip-chip technology. U.S. Patent No. 6,194,743 describes a technique related to an electrode structure comprising an Ag layer with a thickness exceeding 20 nm, a diffusion barrier layer covering the Ag layer, and a diffusion barrier layer containing Au and Al covering the diffusion barrier layer. the bonding layer.

A p-side pad 700 and an n-side electrode 800 are provided for current supply and external wire bonding. US Patent No. 5,563,422 describes a technique of forming an n-side electrode using Ti and Al.

The optional protective film 900 can be made of SiO ₂ .

The n-type nitride semiconductor layer 300 or the p-type nitride semiconductor layer 500 may be configured as a single layer or multiple layers. A vertical light emitting device is introduced by separating the substrate 100 from the nitride semiconductor layer using laser technology or wet etching.

2 and 3 are views of an example of a light emitting device described in US Patent Application Publication No. 2006/0192247. 2 shows a state where the light generated inside the light emitting device A disappears without being emitted to the outside of the light emitting device, and FIG. 3 shows that an inclined surface 120 is formed on the surface of the light emitting device so that the light generated inside the light emitting device A can be emitted to The state of the exterior of the light emitting device.

Fig. 4 is a view of an example of a light emitting device described in Japanese Patent Laid-Open No. 2001-24222. The light emitting device includes a trench 920 formed between the p-side electrode 600 and the n-type nitride semiconductor layer 300 . Thus, light generated inside the light emitting device can be easily emitted to the outside of the light emitting device.

However, the conventional light emitting device as described above has a disadvantage that light generated inside A of the light emitting device or active layer 400 and incident on the substrate 100 is reflected, and thus is not extracted to the outside of the light emitting device.

Contents of the invention

Technical solutions

This section provides a general summary of the invention, rather than a comprehensive disclosure of its full scope or all of its features.

According to one aspect of the present invention, there is provided a group III nitride semiconductor light emitting device, the group III nitride semiconductor light emitting device comprising: a substrate; a plurality of group III nitride semiconductor layers, the plurality of group III nitride semiconductor layers The semiconductor layer includes a first nitride semiconductor layer formed on the substrate and having a first conductivity type, and a second conductivity type different from the first conductivity type formed on the first nitride semiconductor layer. a second nitride semiconductor layer, and an active layer disposed between the first nitride semiconductor layer and the second nitride semiconductor layer and generating light by recombination of electrons and holes; An opening formed along the plurality of group III nitride semiconductor layers, the opening including a first scattering surface for scattering light generated in the active layer and a first scattering surface having a different inclination from the first scattering surface. Second scattering surface.

Beneficial effect

According to the group III nitride semiconductor light emitting device of the present invention, the light extraction efficiency of the light emitting device can be improved.

In one embodiment, according to the III-nitride semiconductor light emitting device of the present invention, extraction efficiency of light incident on a light emitting device substrate can be improved.

In another embodiment, according to the group III nitride semiconductor light emitting device of the present invention, the light extraction efficiency of the nitride semiconductor layer of the group III nitride semiconductor light emitting device can be improved.

Description of drawings

FIG. 1 is a view of one example of a conventional group III nitride semiconductor light emitting device.

FIG. 2 is a view of one example of a light emitting device described in US Patent Application Publication No. 2006/0192247.

FIG. 3 is a view of another example of the light emitting device described in US Patent Application Publication No. 2006/0192247.

Fig. 4 is a view of an example of a light emitting device described in Japanese Patent Laid-Open Publication No. 2001/24222.

Fig. 5 is a view of one embodiment of a group III nitride semiconductor light emitting device of the present invention.

Fig. 6 is a view of another embodiment of the group III nitride semiconductor light emitting device of the present invention.

FIG. 7 is a view of one embodiment of a method for manufacturing a group III nitride semiconductor light emitting device of the present invention.

Figure 8 is a view of a pattern of various shapes of the present invention.

Fig. 9 is an image of one example of openings formed in the group III nitride semiconductor light emitting device of the present invention.

Fig. 10 is an image of an embodiment of a Group III nitride semiconductor light emitting device of the present invention.

FIG. 11 is an enlarged image of the light emitting device of FIG. 10 .

Detailed ways

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Fig. 5 is a view of one embodiment of a group III nitride semiconductor light emitting device of the present invention. The group III nitride semiconductor light emitting device comprises a substrate 10, a buffer layer 20 formed on the substrate 10, an n-type nitride semiconductor layer 30 grown on the buffer layer 20, grown on the n-type nitride semiconductor layer 30 and The active layer 40 that generates light by recombination of electrons and holes, the p-type nitride semiconductor layer 50 grown on the active layer 40 , and the opening 90 .

The opening 90 is formed from the substrate 10 along the buffer layer 20 , the n-type nitride semiconductor layer 30 , the active layer 40 and the p-type nitride semiconductor layer 50 . Opening 90 includes scattering surface 92 and scattering surface 94 . The scattering surface 92 is formed on the substrate 10 . Scattering surface 94 is formed along buffer layer 20 , n-type nitride semiconductor layer 30 , active layer 40 , and p-type nitride semiconductor layer 50 .

The scattering surface 92 is generally in the shape of a pad when the substrate 10 is slightly depressed and may scatter light generated in the active layer 40 and incident on the substrate 10 . Scattering surface 94 narrows from substrate 10 along buffer layer 20 , n-type nitride semiconductor layer 30 , active layer 40 , and p-type nitride semiconductor layer 50 , and can scatter light generated in active layer 40 . Opening 90 may include scattering surfaces 92 and 94 joined together or spaced apart. However, when the opening 90 includes the scattering surfaces 92 and 94 connected together, the light generated in the active layer 40 will be emitted to the outside of the light emitting device (hereinafter referred to as "light extraction efficiency").

In some embodiments, the light emitting device includes a plurality of openings 90 to improve light extraction efficiency.

Fig. 6 is a view of another embodiment of the group III nitride semiconductor light emitting device of the present invention. The group III nitride semiconductor light emitting device includes a scattering surface 96 and a scattering surface 98 formed on the surface thereof.

Scattering surface 96 is formed on substrate 10 , and scattering surface 98 is formed along buffer layer 20 , n-type nitride semiconductor layer 30 , active layer 40 , and p-type nitride semiconductor layer 50 . Scattering surface 96 and scattering surface 98 are generally wedge-shaped. The light emitting device may comprise scattering surfaces 96 and 98 simultaneously or separately. In some embodiments, the light emitting device includes both scattering surfaces 96 and 98 to improve light extraction efficiency.

Next, a method for manufacturing the Group III nitride semiconductor light emitting device of the present invention will be described in detail. FIG. 7 is a view of one embodiment of a method for manufacturing a group III nitride semiconductor light emitting device of the present invention.

Substrate 10 is prepared, and nitride semiconductor layers 20 , 30 , 40 , and 50 are then grown on substrate 10 . Next, a protective film 77 is formed on the nitride semiconductor layers 20 , 30 , 40 and 50 . The protective film 77 can be made of SiO ₂ or the like (refer to FIG. 7( a )). According to the present invention, the substrate 10 may be a sapphire substrate.

A pattern 78 is formed on the protective film 77 (refer to FIG. 7(b)). Figure 8 shows a variety of shaped patterns 78, such as circles or hexagons, that may be used in the present invention.

The substrate 10 on which the pattern 78 is formed is immersed in an oxide etchant (BOE) buffer solution to etch and remove the protective film 77 according to the pattern 78 (refer to FIG. 7( c )).

The nitride semiconductor layers 20 , 30 , 40 and 50 are dry etched according to the pattern 78 until the substrate 10 is exposed. At this point the opening 90 will be formed. The dry etching may be performed using inductively coupled plasma (ICP) or the like (refer to FIG. 7( d )).

The substrate 10 and nitride semiconductor layers 20, 30, 40, and 50 are divided into individual light emitting devices. The division can be performed using a laser scribing method. In some embodiments, the depth D of the cutting surface formed by laser scribing method from the surface of the substrate 10 is 0.5 μm˜30 μm. Therefore, the entire light emitting device can be easily divided into individual light emitting devices by physical force. If the depth D of the cut face is lower than 0.5 μm, cracks may be generated on and in the light emitting device or electrical characteristics may be deteriorated when the entire light emitting device is physically divided into individual light emitting devices. If the depth D of the cut face exceeds 30 μm, it may be easily damaged when manufacturing a single light emitting device, resulting in lower yield (refer to FIG. 7( e )).

Wet etching is performed on the light emitting device. For example, when the substrate 10 is a planar substrate, the light emitting device may be immersed in a mixture of H ₂ SO ₄ and H ₃ PO ₄ (3:1) at 280° C. for 13 minutes. During this process, due to the differences in the etch rates between the substrate 10 and the buffer layer 20, n-type nitride semiconductor layer 30, active layer 40, and p-type nitride semiconductor layer 50, scattering will be formed on the opening 90. Surfaces 92 and 94 and will form scattering surfaces 96 and 98 on the sides of the light emitting device. In some embodiments, the roughness of scattering surfaces 92, 94, 96, and 98 is kept below tens of nanometers. If the roughness thereof exceeds several tens of nanometers, the scattering surfaces 92, 94, 96, and 98 may reduce the light extraction efficiency of the light emitting device by acting as residual impurities (refer to FIG. 7(f)).

FIG. 9 is an image of one example of the opening 90 formed in the group III nitride semiconductor light emitting device of the present invention. Scattering surface 92 is formed on substrate 10 , and scattering surface 94 is formed along nitride semiconductor layers 20 , 30 , 40 , and 50 .

FIG. 10 is an image of an embodiment of a Group III nitride semiconductor light emitting device of the present invention, and FIG. 11 is an enlarged image of the light emitting device of FIG. 10 . An opening 90 is formed in the III-nitride semiconductor light emitting device. In order to form the openings 90 , a hexagonal pattern with a side length of 4 μm was formed at an interval of 12 μm.

In the following, various examples of the present invention will be described.

(1) The group III nitride semiconductor light emitting device, wherein the first scattering surface is formed on the substrate.

(2) The group III nitride semiconductor light emitting device, wherein the first scattering surface is formed when the substrate is depressed.

(3) The group III nitride semiconductor light emitting device, wherein the second scattering surface is formed along the plurality of group III nitride semiconductor layers.

(4) The group III nitride semiconductor light emitting device, wherein the second scattering surface has an opening that narrows from the substrate along the plurality of group III nitride semiconductor layers.

(5) The group III nitride semiconductor light-emitting device, wherein the opening is formed in plural.

(6) The Group III nitride semiconductor light emitting device, wherein the first scattering surface and the second scattering surface are formed by wet etching.

(7) The group III nitride semiconductor light emitting device, wherein the first scattering surface is formed when the substrate is sunken, and the second scattering surface is formed along the plurality of group III nitride semiconductors from the substrate layer narrows.

(8) The Group III nitride semiconductor light-emitting device including a wedge-shaped scattering surface on its surface.

Claims (7)

1. A group III nitride semiconductor light emitting device, the group III nitride semiconductor light emitting device comprising: Substrate; a plurality of group III nitride semiconductor layers, the plurality of group III nitride semiconductor layers including a first nitride semiconductor layer formed on the substrate and having a first conductivity type, formed on the first nitride semiconductor layer a second nitride semiconductor layer on the semiconductor layer and having a second conductivity type different from the first conductivity type, and arranged between the first nitride semiconductor layer and the second nitride semiconductor layer through an active layer where the recombination of electrons and holes produces light; and An opening formed from the substrate along the plurality of group III nitride semiconductor layers, the opening including a first scattering surface for scattering light generated in the active layer and Second scattering surface with different inclination. 2. The Ill-nitride semiconductor light emitting device of claim 1, wherein the first scattering surface is formed on the substrate. 3. The Ill-nitride semiconductor light emitting device according to claim 2, wherein the first scattering surface is formed as a recessed portion of the substrate. 4. The Ill-nitride semiconductor light emitting device of claim 1, wherein the second scattering surface is formed along the plurality of Ill-nitride semiconductor layers. 5. The group III nitride semiconductor light emitting device according to claim 4, wherein the second scattering surface has an opening narrowed from the substrate along the plurality of group III nitride semiconductor layers. 6. The III-nitride semiconductor light emitting device according to claim 1, wherein the first scattering surface is formed when the substrate is sunken, and the second scattering surface is formed from the substrate along the Multiple group III nitride semiconductor layers are narrowed. 7. The group III nitride semiconductor light emitting device according to claim 6, comprising a wedge-shaped scattering surface on a surface thereof.

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