KR100975527B1 - Group III nitride semiconductor light emitting device - Google Patents

Abstract

The present disclosure relates to a group III nitride semiconductor light emitting device, and more particularly, to a group III nitride semiconductor layer having a first conductivity and a group III nitride semiconductor layer having a second conductivity different from the first conductivity. A plurality of Group III nitrides comprising a Group II nitride semiconductor layer and an active layer positioned between the Group III nitride semiconductor layer and the Group III nitride nitride semiconductor layer to generate first light by recombination of electrons and holes. A semiconductor layer; A first bonding pad electrically connected to the second group III nitride semiconductor layer; And a fluorescent film having a fluorescent material excited by the first light and emitting a second light different from the first light, wherein the fluorescent film is cured and positioned on the plurality of group III nitride semiconductor layers to expose the first bonding pads. It provides a Group III nitride semiconductor light-emitting device comprising a; fluorescent film provided with a lens on the top having a first cutout.

Group III nitride, semiconductor, light emitting device, LED, phosphor, fluorescent film, light extraction efficiency

Description

Group III nitride semiconductor light emitting device {III-NITRIDE SEMICONDUCTOR LIGHT EMITTING DEVICE}

The present disclosure generally relates to a group III nitride semiconductor light emitting device, and more particularly, to a group III nitride semiconductor light emitting device including a fluorescent film capable of improving light extraction efficiency.

Here, the semiconductor light emitting device refers to a semiconductor optical device that generates light through recombination of electrons and holes, for example, a group III nitride semiconductor light emitting device. The group III nitride semiconductor consists of a compound of Al (x) Ga (y) In (1-x-y) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). In addition, GaAs type semiconductor light emitting elements used for red light emission, etc. are mentioned.

This section provides backgound informaton related to the present disclosure which is not necessarily prior art.

1 is a view illustrating an example of a conventional Group III nitride semiconductor light emitting device, wherein the Group III nitride semiconductor light emitting device is grown on the substrate 100, the buffer layer 200 grown on the substrate 100, and the buffer layer 200. n-type group III nitride semiconductor layer 300, an active layer 400 grown on the n-type group III nitride semiconductor layer 300, p-type group III nitride semiconductor layer 500, p-type 3 grown on the active layer 400 The p-side electrode 600 formed on the group nitride semiconductor layer 500, the p-side bonding pad 700 formed on the p-side electrode 600, the p-type group III nitride semiconductor layer 500 and the active layer 400 are formed. The n-side electrode 800 and the passivation layer 900 are formed on the n-type group III nitride semiconductor layer 300 exposed by mesa etching.

As the substrate 100, a GaN-based substrate is used as the homogeneous substrate, and a sapphire substrate, a SiC substrate, or a Si substrate is used as the heterogeneous substrate. Any substrate may be used as long as the group III nitride semiconductor layer can be grown. When a SiC substrate is used, the n-side electrode 800 may be formed on the SiC substrate side.

Group III nitride semiconductor layers grown on the substrate 100 are mainly grown by MOCVD (organic metal vapor growth method).

The buffer layer 200 is intended to overcome the difference in lattice constant and thermal expansion coefficient between the dissimilar substrate 100 and the group III nitride semiconductor, and US Pat. A technique for growing an AlN buffer layer having a thickness of US Pat. No. 5,290,393 describes Al (x) Ga (1-x) N having a thickness of 10 kPa to 5000 kPa at a temperature of 200 to 900 C on a sapphire substrate. (0 ≦ x <1) A technique for growing a buffer layer is described, and US Patent Publication No. 2006/154454 discloses growing a SiC buffer layer (seed layer) at a temperature of 600 ° C. to 990 ° C., followed by In (x Techniques for growing a Ga (1-x) N (0 <x≤1) layer are described. Preferably, the undoped GaN layer is grown prior to the growth of the n-type group III nitride semiconductor layer 300, which may be viewed as part of the buffer layer 200 or as part of the n-type group III nitride semiconductor layer 300. good.

In the n-type group III nitride semiconductor layer 300, at least a region (n-type contact layer) in which the n-side electrode 800 is formed is doped with impurities, and the n-type contact layer is preferably made of GaN and doped with Si. . U. S. Patent No. 5,733, 796 describes a technique for doping an n-type contact layer to a desired doping concentration by controlling the mixing ratio of Si and other source materials.

The active layer 400 is a layer that generates photons (light) through recombination of electrons and holes, and is mainly composed of In (x) Ga (1-x) N (0 <x≤1), and one quantum well layer (single quantum wells) or multiple quantum wells.

The p-type III-nitride semiconductor layer 500 is doped with an appropriate impurity such as Mg, and has an p-type conductivity through an activation process. U.S. Patent No. 5,247,533 describes a technique for activating a p-type group III nitride semiconductor layer by electron beam irradiation, and U.S. Patent No. 5,306,662 annealing at a temperature of 400 DEG C or higher to provide a p-type group III nitride semiconductor layer. A technique for activating is described, and US Patent Publication No. 2006/157714 discloses a p-type III-nitride semiconductor layer without an activation process by using ammonia and a hydrazine-based source material together as a nitrogen precursor for growing the p-type III-nitride semiconductor layer. Techniques for having this p-type conductivity have been described.

The p-side electrode 600 is provided to provide a good current to the entire p-type group III nitride semiconductor layer 500. US Patent No. 5,563,422 is formed over almost the entire surface of the p-type group III nitride semiconductor layer. And a light-transmitting electrode made of Ni and Au in ohmic contact with the p-type III-nitride semiconductor layer 500 and described in US Patent No. 6,515,306 on the p-type III-nitride semiconductor layer. A technique has been described in which an n-type superlattice layer is formed and then a translucent electrode made of indium tin oxide (ITO) is formed thereon.

On the other hand, the p-side electrode 600 may be formed to have a thick thickness so as not to transmit light, that is, to reflect the light toward the substrate side, this technique is referred to as flip chip (flip chip) technology. U. S. Patent No. 6,194, 743 describes a technique relating to an electrode structure including an Ag layer having a thickness of 20 nm or more, a diffusion barrier layer covering the Ag layer, and a bonding layer made of Au and Al covering the diffusion barrier layer.

The p-side bonding pad 700 and the n-side electrode 800 are for supplying current and wire bonding to the outside, and US Patent No. 5,563,422 describes a technique in which the n-side electrode is composed of Ti and Al.

The passivation layer 900 is formed of a material such as silicon dioxide and may be omitted.

Meanwhile, the n-type III-nitride semiconductor layer 300 or the p-type III-nitride semiconductor layer 500 may be composed of a single layer or a plurality of layers, and recently, the substrate 100 may be formed by laser or wet etching. A technique for manufacturing a vertical light emitting device by separating from group III nitride semiconductor layers has been introduced.

FIG. 2 is a diagram illustrating an example of a semiconductor light emitting device (LED) package described in Korean Patent Publication No. 10-0818518. The heat sink 111, the light emitting device 211 placed on the heat sink 111, and a light emitting device. A first lead frame 311 coupled to the heat sink 111 and a second wire electrically connected to the light emitting element 211 through the bonding wires 411 to be electrically connected to the heat sinks 111 and 211. Only around the molded frame 611 and the light emitting element 211 that fix the lead frame 511, the heat sink 111, the first lead frame 311 and the second lead frame 511 to form a body of the package. A package is provided that includes an applied phosphor layer 711, a light transmissive encapsulant 811 covering the phosphor layer 711, and a lens 911 overlying the light transmissive encapsulant 811. Here, the light emitting device 211 may be an example of the group III nitride semiconductor light emitting device described with reference to FIG. 1.

U.S. Patent Nos. 5,998,925 and 6,069,440 are fluorescent materials that may be provided in the phosphor layer 711 and include at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, Al, Ga and A light emitting device including at least one element selected from the group consisting of In and emitting white light through a garnet-based (YAG: Ce) material activated by Ce is described, and US Patent No. 6,504,179 describes the fluorescent material. As a technique, there is described a light emitting device that emits white light through a garnet-based (TAG: Ce) -activated Ce material selected from the group consisting of Tb, Y, Gd, Lu and / or La.

A conventional group III nitride semiconductor light emitting device and a package including the same include an n-side electrode 800 provided in the frame 611 so that the light emitting device 211 is in contact with the heat sink 111 and provided in the light emitting device 211. After bonding the wire 411 to connect the first lead frame 311 and the p-side bonding pad 700 and the second lead frame 511, the phosphor layer 711 around the light emitting device 211. Is applied, and a process of completing the package through the light-transmissive encapsulant 811 and the lens 911.

However, as light generated in the light emitting device 211 passes through the phosphor layer 711 and is emitted to the outside, there is a problem that loss of light may occur in the process of passing through the phosphor layer 711.

In addition, the phosphor layer 711 is applied to the light emitting device 211 around the light emitting device 211 to surround the light emitting device 211 as well as the upper side of the light emitting device 211, and then cured to form the phosphor layer by precipitation of the fluorescent material during the curing process. 711, there is a problem that the distribution of the fluorescent material from the top to the bottom may be non-uniform, there is a problem that the color deviation may occur, the color may change. In addition, there is a problem that it is difficult to control the thickness of the phosphor layer 711 and the mixing ratio of the fluorescent material.

On the other hand, the light emission characteristics of the light emitting element 211 is measured before applying the phosphor layer 711, and the light emission characteristics of the package is measured after applying the phosphor layer 711, the light emission characteristics of the light emitting element 211 and the package There is a problem that can be different.

This will be described later in the Specification for Implementation of the Invention.

SUMMARY OF THE INVENTION Herein, a general summary of the present disclosure is provided, which should not be construed as limiting the scope of the present disclosure. of its features).

According to one aspect of the present disclosure, a second conductivity is formed on a first group III nitride semiconductor layer having a first conductivity and a first group III nitride semiconductor layer, the second conductivity being different from the first conductivity. A third group III nitride semiconductor layer having an active layer and an active layer positioned between the first group III nitride semiconductor layer and the second group III nitride semiconductor layer to generate first light by recombination of electrons and holes; A group nitride semiconductor layer; A first bonding pad electrically connected to the second group III nitride semiconductor layer; And a fluorescent film having a fluorescent material excited by the first light and emitting a second light different from the first light, wherein the fluorescent film is cured and positioned on the plurality of group III nitride semiconductor layers to expose the first bonding pads. It provides a Group III nitride semiconductor light-emitting device comprising a; fluorescent film provided with a lens on the top having a first cutout.

This will be described later in the Specification for Implementation of the Invention.

The present disclosure will now be described in detail with reference to the accompanying drawing (s).

3 is a diagram illustrating an example of a group III nitride semiconductor light emitting device according to the present disclosure, in which the group III nitride semiconductor light emitting device is disposed on a substrate 10, a buffer layer 20, and a buffer layer 20 grown on the substrate 10. Grown on the grown n-type Group III nitride semiconductor layer 30 and the n-type Group III nitride semiconductor layer 30 and grown on the active layer 40 and the active layer 40 which generate first light by recombination of electrons and holes. The p-type group III nitride semiconductor layer 50 to be formed, the p-side electrode 60 formed on the p-type Group III nitride semiconductor layer 50, the p-side bonding pad 70 to be formed on the p-side electrode 60, and p An n-side electrode 80, an adhesive layer 65, a fluorescent film 90 formed on the n-type Group III nitride semiconductor layer 30 where the type-III group nitride semiconductor layer 50 and the active layer 40 are etched and exposed; And a lens 95. The n-side electrode 80 not only contacts the n-type group III nitride semiconductor layer 30 for supplying current, but also serves as a bonding pad for wire bonding.

The p-side electrode 60 is formed of a light-transmitting electrode, and may be formed over the entire p-type group III nitride semiconductor layer 50, or may be formed in part.

The adhesive layer 65 is formed on the p-side electrode 60 to improve the binding force between the p-side electrode 60 and the fluorescent film 90. The adhesive layer 65 may be formed by applying an adhesive material on the p-side electrode 60. After the doping of the adhesive material on the p-side electrode 60, the adhesive layer 65 may be formed by being pressed and pressed. It may be.

The fluorescent film 90 is cured and positioned on the p-side electrode 60 and includes a fluorescent material that is excited by the first light and emits a second light different from the first light. The fluorescent material may be made of a yttrium-aluminum-garnet (YAG) system, a terbium-aluminum-garnet (TAG) system, or the like.

In addition, the fluorescent film 90 has cutouts 92 and 94.

The notch 92 is formed on the p-side bonding pad 70 side, and the notch 94 is formed on the n-side electrode 80 side. The shape of the cutout 92 may vary depending on the size or position of the p-side bonding pad 70. The perimeter of the cutout 92 may be clogged, and a portion of the perimeter of the cutout 92 may be opened. On the other hand, the cutout 92 is at least the size of the p-side bonding pad 70 in order to facilitate wire bonding to the p-side bonding pad 70 with the fluorescent film 90 placed on the p-side electrode 60. It is preferably formed. The cutout 94 exposes the n-side electrode 80 for wire bonding to the n-side electrode 80, and fits the phosphor film in the light emitting device. It is preferable to follow the shape of the p-type group III nitride semiconductor layer 50 and the active layer 40 etched to form the n-side electrode 80 so that the () can be improved. ) Is in shape.

The thickness of the fluorescent film 90 may be adjusted, may be formed of one fluorescent film 90, or may be formed of a plurality of fluorescent films 90B. Accordingly, the fluorescent films 90B different in the fluorescent material may be used in combination, and the fluorescent films 90B different in the distribution of the fluorescent material may be used in combination. Through this, the distribution of the fluorescent material may be uniform, color deviation may be reduced, and color may be easily adjusted.

The lens 95 is formed on the fluorescent film 90 or the fluorescent films 90B. The lens 95 has an advantageous function in that the first light and the second light exit the outside of the light emitting device. One lens 95 may be formed on the fluorescent film 90, or a plurality of lenses 95 may be formed.

4 is a view illustrating another example of the group III nitride semiconductor light emitting device according to the present disclosure, wherein the group III nitride semiconductor light emitting device is disposed on the substrate 10, the buffer layer 20, and the buffer layer 20 grown on the substrate 10. Grown on the grown n-type Group III nitride semiconductor layer 30 and the n-type Group III nitride semiconductor layer 30 and grown on the active layer 40 and the active layer 40 which generate first light by recombination of electrons and holes. P-type group III nitride semiconductor layer 50 to be formed, p-side electrode 60 formed on p-type Group III nitride semiconductor layer 50, p-side bonding pad 70 to be formed on p-side electrode 60, fluorescent The film 90 and the lens 95.

This is a so-called vertical light emitting device in which the substrate 10 is made of a conductive substrate and the n-type group III nitride semiconductor layer 30 can be electrically connected to the outside of the light emitting device through the substrate 10. Another application example of the fluorescent film 90 is shown.

In the examples of the Group III nitride semiconductor light emitting device according to FIGS. 3 and 4, a protective film (not shown) may be disposed between the p-side electrode 60 and the fluorescent film 90.

Hereinafter, a method of manufacturing a group III nitride semiconductor light emitting device according to the present disclosure will be described in detail.

FIG. 5 is a view illustrating an example of a method of manufacturing the fluorescent film 90 included in the group III nitride semiconductor light emitting device according to the present disclosure. First, a mold in which the intaglio portions 90b and the protrusions 92b and 94b are formed ( 99) (see FIG. 5A).

Next, the fluorescent liquid 98 is filled with the squeeze 88 or the like in the intaglio portion 90b formed in the mold 99 (see FIG. 5B).

Next, the fluorescent solution 98 is cured on the mold 99 to obtain a fluorescent film 90 (see FIG. 5C).

Next, the fluorescent film 90 is transferred from the frame 99 onto the p-side electrode 60 (see FIG. 5D). For example, the transfer of the fluorescent film 90 primarily moves the fluorescent film 90 from the mold 99 to the viscous sheet, and then moves the fluorescent film 90 onto the p-side electrode 60 from the sheet. This can be done by going secondary.

 Here, the fluorescent liquid 98 comprises a fluorescent material (for example, in the form of a powder) and is made of a light transmitting material that can be cured in the mold 99. The fluorescent liquid 98 can be widely used as long as it can be cured by external conditions. For example, the phosphor 98 may be made of silicone, epoxy, silicone including silica, and sealing agent including silica in a binder form. On the other hand, the curing of the fluorescent solution 98 may be achieved by gradually raising and lowering the temperature from about 100 ° C to about 180 ° C for about 6 hours when silicon is used as the fluorescent solution 98.

The fluorescent film 90 is preferably attached by an adhesive material to secure the adhesion between the fluorescent film 90 and the p-side electrode 60. For example, as the adhesive material, silicone, epoxy, silicone including silica, encapsulating agent including silica in binder form, and the like may be used.

FIG. 6 is a view showing an example of a mold 99 used in the method of manufacturing the fluorescent film 90 included in the group III nitride semiconductor light emitting device according to the present disclosure, and the intaglio portion 90b is the fluorescent film 90. The protrusions 92b and 94b are formed to have a depth of thickness, and the protrusions 92b and 94b are formed in the recess 90b at a height greater than or equal to the thickness of the cutouts 92 and 94 (shown in FIG. 3) to form the recess 90b. And the protrusions 92b and 94b are formed in a reverse shape of the fluorescent film 90 as a whole. For example, the depth of the intaglio portion 90b may be 200 μm to 300 μm, and a fluorescent film 90 having a thickness of 200 μm to 300 μm may be manufactured. Here, the mold 99 may be manufactured by wet etching, photolithography, transfer mold, or the like.

FIG. 7 is a view showing another example of the method of manufacturing the fluorescent film 90 included in the group III nitride semiconductor light emitting device according to the present disclosure, and the intaglio portion 90b is used to more effectively manufacture the fluorescent film 90. A plurality is formed in the mold 99. In this case, the plurality of intaglio portions 90b are positioned to correspond to a plurality of light emitting elements (here, the light emitting elements mean a state before the fluorescent film 90 is provided). Can be transferred to two light emitting elements.

8 is a view illustrating an example of a method of manufacturing the lens 95 included in the group III nitride semiconductor light emitting device according to the present disclosure. First, a mask 97 having a pattern 97b for forming the lens 95 is provided. Is prepared on the fluorescent film 90 (see Fig. 8A). Next, the light transmissive material 95b is filled into the pattern 97b formed in the mask 97 (see FIG. 8B). The light transmissive material 95b is preferably made of a thixotropic material, and may be made of, for example, silicone or epoxy series having a thixotropy of 2.0 to 6.0 indices. Manufacturing of the plurality of lenses 95 may be performed by placing the mask 97 on which the plurality of patterns 97b are formed, on the plurality of fluorescent films 90. Next, the light transmissive material 95b is cured (see FIG. 8C). A convex lens 95 is formed in the process of curing the light-transmitting material 95b (see FIG. 8D). For example, curing of the light transmissive material 95b may be performed by gradually raising and lowering the temperature from about 30 ° C. to about 200 ° C. for about 6 hours. The lens 95 may be cured and then mounted on the fluorescent film 90.

Various embodiments of the present disclosure will be described below.

(1) A group III nitride semiconductor light emitting device comprising a cured fluorescent film. As a result, color deviation can be reduced and color can be easily adjusted.

(2) A group III nitride semiconductor light emitting element comprising a fluorescent film having a cutout portion for wire bonding. As a result, the light emission characteristics of the light emitting device by the fluorescent material can be measured even before the package.

(3) A group III nitride semiconductor light emitting element comprising a lens on a fluorescent film. As a result, the light extraction efficiency of the light emitting device can be improved.

(4) A group III nitride semiconductor light emitting element comprising an adhesive layer. Thereby, the adhesiveness of a fluorescent film can be improved and the unity of a light emitting element can be improved.

According to one group III nitride semiconductor light emitting device according to the present disclosure, the light extraction efficiency in the fluorescent film can be improved.

According to another group III nitride semiconductor light emitting device according to the present disclosure, it is possible to improve the occurrence of color deviation due to the fluorescent material.

According to another group III nitride semiconductor light emitting device according to the present disclosure, it is possible to improve the color change according to the fluorescent material and to easily control the color change.

According to another group III nitride semiconductor light emitting device according to the present disclosure, it is possible to easily adjust the compounding ratio of the fluorescent material, and to easily adjust the thickness of the fluorescent film.

According to another group III nitride semiconductor light emitting device according to the present disclosure, it is possible to improve that the light emission characteristics before and after wire bonding are changed.

1 is a view showing an example of a conventional group III nitride semiconductor light emitting device,

2 is a view showing an example of a semiconductor light emitting device (LED) package described in Korean Patent Publication No. 10-0818518;

3 is a view showing an example of a group III nitride semiconductor light emitting device according to the present disclosure;

4 is a view showing another example of the group III nitride semiconductor light emitting device according to the present disclosure;

5 is a view showing an example of a method of manufacturing a fluorescent film provided in a group III nitride semiconductor light emitting device according to the present disclosure;

6 is a view showing an example of a frame used in a method of manufacturing a fluorescent film provided in a group III nitride semiconductor light emitting device according to the present disclosure;

7 is a view showing another example of a method of manufacturing a fluorescent film provided in a group III nitride semiconductor light emitting device according to the present disclosure;

8 is a view showing an example of a method of manufacturing a lens provided in a group III nitride semiconductor light emitting device according to the present disclosure.

Claims (9)

A first group III nitride semiconductor layer having a first conductivity, a second group III nitride semiconductor layer formed on the first group III nitride semiconductor layer, and having a second conductivity different from the first conductivity, and a first group III nitride semiconductor layer; A plurality of group III nitride semiconductor layers positioned between the second group III nitride semiconductor layers and having an active layer that generates first light by recombination of electrons and holes; A first bonding pad electrically connected to the second group III nitride semiconductor layer; And, A fluorescent film comprising a fluorescent material excited by the first light and emitting a second light different from the first light, wherein the fluorescent film is cured and positioned on the plurality of group III nitride semiconductor layers and is formed to expose the first bonding pads. A group III nitride semiconductor light emitting device comprising: a fluorescent film having a cutout and having a lens thereon. In claim 1, A group III nitride semiconductor light emitting device, characterized in that the lens is made of a thixotropic material. In claim 1, A group III nitride semiconductor light emitting device comprising a; adhesive layer attaching a fluorescent film to a plurality of group III nitride semiconductor layers. In claim 3, Group 3 nitride semiconductor light emitting device, characterized in that the adhesive layer is made of the same material as the fluorescent film. In claim 1, And a second bonding pad electrically connected to the first group III nitride semiconductor layer to which the second group III nitride semiconductor layer and the active layer are etched and exposed. The fluorescent film has a second cutout portion formed to expose the second bonding pads, the group III nitride semiconductor light emitting device. In claim 5, The group III nitride semiconductor light emitting device of claim 2, wherein the second cutout portion is open at one side. In claim 1, A group III nitride semiconductor light emitting device comprising a fluorescent film comprising a plurality of layers. In claim 1, The fluorescent film is a group III nitride semiconductor light emitting device, characterized in that located in the upper surface of the plurality of group III nitride semiconductor layers. In claim 1, A second bonding pad electrically connected to the first group III nitride semiconductor layer to which the second group III nitride semiconductor layer and the active layer are etched and exposed; And, It includes; the adhesive layer for bonding the fluorescent film and the plurality of group III nitride semiconductor layer, The fluorescent film has a second cutout portion formed to expose the second bonding pads, the group III nitride semiconductor light emitting device.

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