KR20130075815A

KR20130075815A - Light emitting device

Info

Publication number: KR20130075815A
Application number: KR1020110144064A
Authority: KR
Inventors: 김두성; 김극
Original assignee: 일진엘이디(주)
Priority date: 2011-12-28
Filing date: 2011-12-28
Publication date: 2013-07-08

Abstract

PURPOSE: A light emitting device is provided to improve adhesion by using a first and a second electrode which have recessed pattern structures. CONSTITUTION: A first semiconductor layer, an active layer (130), and a second semiconductor layer are laminated. A first electrode (160) is formed on a preset region on the first semiconductor layer. A second electrode (170) is formed on a preset region on the second semiconductor layer. At least one area of the first and the second electrode is a recessed structure. The recessed structure exposes a part of the first semiconductor layer or the second semiconductor layer.

Description

[0001]

The present invention relates to a light emitting device, and more particularly, to a light emitting device using nitride.

In general, nitrides such as GaN, AlN, InN, and the like have excellent thermal stability and have a direct transition type energy band structure, which has recently attracted much attention as a material for optoelectronic devices. In particular, GaN can be used in high temperature high power devices because the energy bandgap is very large at 3.4 eV at room temperature.

Light emitting devices using GaN semiconductors generally include an N-type GaN layer, an active layer, a P-type GaN layer formed on a substrate, and an N-type electrode connected to the N-type GaN layer and the P-type GaN layer, respectively. It consists of a P-type electrode. At this time, the N-type electrode and the P-type electrode are formed to have a flat surface. In the light emitting device, when a predetermined current is applied to the N-type electrode and the P-type electrode, electrons provided from the N-type GaN layer and holes provided from the P-type GaN layer are recombined in the active layer so that light having a wavelength corresponding to the energy gap is generated. Will be released.

In addition, the light emitting device is packaged by bonding the N-type electrode and the P-type electrode to the lead frame using a wire and molding the light emitting device after being bonded on the housing provided with the lead frame. At this time, the bonding force between the electrode and the wire having the flat surface becomes larger as the bonding area becomes larger, and the bonding area is determined according to the width of the wire. However, since the width of the wire is narrow, the bonding area is narrowed and the bonding force between the wire and the electrode is weakened. Therefore, a problem may occur in that the electrode and the wire are broken, and accordingly, the light emitting device may not operate and reliability may be degraded.

The present invention provides a light emitting device capable of improving the bonding force between the electrode and the wire.

The present invention provides a light emitting device capable of improving the bonding force between the electrode and the wire by increasing the bonding area of the electrode and the wire.

A light emitting device according to embodiments of the present invention may include a first semiconductor layer, an active layer, and a second semiconductor layer that are stacked; And first and second electrodes formed in predetermined regions on the first and second semiconductor layers, respectively, wherein the first and second electrodes have at least one region having an uneven structure.

The first and second electrodes are formed in an integrated line shape or a plurality of line shapes spaced apart from each other by a predetermined interval.

The uneven structure is formed such that at least one region exposes at least a portion of the first semiconductor layer or the second semiconductor layer, respectively.

The uneven structure is formed such that at least one region has a step between an upper portion and a lower portion of each of the first and second electrodes.

It further comprises a wire bonded to the first and second electrodes, respectively.

The wire is joined to the inside of the uneven structure of the first and second electrodes.

A package body on which the light emitting device is mounted; And a lead frame provided on the package body, wherein the wire connects the lead frame with the first and second electrodes of the light emitting device.

The lead frame has at least one region connected to the wire to have an uneven structure.

A submount substrate having third and fourth electrodes respectively corresponding to the first and second electrodes, respectively; And first and second solders respectively formed on the third and fourth electrodes and bonded to the first and second electrodes, respectively.

Embodiments of the present invention form the first and second electrodes formed on the first and second semiconductor layers in a concave-convex structure of a predetermined pattern. That is, the first and second electrodes are formed in a predetermined pattern having a thickness difference.

When the first and second electrodes are formed in a concave-convex structure having a predetermined pattern, and the wires are bonded to the first and second electrodes, the wires are formed not only on the upper surfaces of the first and second electrodes but also inside the concave-convex structure. Therefore, the bonding area of the wire and the electrode can be increased without increasing the width of the wire, thereby improving the bonding force, thereby preventing the inoperation of the light emitting device due to the breakage of the electrode and the wire, thereby providing a reliable light emitting device. Can be implemented.

1 is a cross-sectional view of a light emitting device according to an embodiment of the present invention.
2 is a cross-sectional view of a light emitting device according to an embodiment of the present invention.
3 is a plan view illustrating various forms of electrodes of a light emitting device according to embodiments of the present disclosure;
4 is a cross-sectional view of a light emitting device package according to an embodiment of the present invention.
5 is a detailed cross-sectional view of the electrode and the wire of the light emitting device package according to an embodiment of the present invention.
6 is a cross-sectional view of a light emitting device package according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention and to those skilled in the art. It is provided for complete information. In the drawings, the thickness is enlarged to clearly illustrate the various layers and regions, and the same reference numerals denote the same elements in the drawings.

1 is a plan view of a light emitting device according to an embodiment of the present invention, Figure 2 is a cross-sectional view. 3 is a plan view of various types of electrodes of a light emitting device.

1 and 2, a light emitting device according to an exemplary embodiment may include a first semiconductor layer 120, an active layer 130, and a second semiconductor layer 140 sequentially stacked on a substrate 110. And the first electrode 160 formed on the transparent semiconductor layer 150, the second semiconductor layer 140, and the active layer 130 are removed to expose the first semiconductor layer 130, and the upper portion of the transparent electrode 150. It includes a second electrode 170 formed in a predetermined region. In addition, the semiconductor device may further include a buffer layer (not shown) formed between the substrate 110 and the first semiconductor layer 120.

The substrate 110 refers to a conventional wafer for fabricating a light emitting device, and preferably, a material suitable for growing a nitride semiconductor single crystal may be used. For example, the substrate 110 may use any one of Al ₂ O ₃ , SiC, ZnO, Si, GaAs, GaP, LiAl ₂ O ₃ , BN, AlN, and GaN.

The first semiconductor layer 120 may be an N-type semiconductor doped with N-type impurities, thereby supplying electrons to the active layer 130. For example, the first semiconductor layer 120 may use a GaN layer doped with N-type impurities, for example, Si. However, the present invention is not limited thereto, and various semiconductor materials are possible. That is, a compound in which nitrides such as GaN, InN, AlN (Group III-V), and such nitrides are mixed at a constant ratio may be used. For example, AlGaN may be used. In addition, the first semiconductor layer 120 may be formed of a multilayer film.

The active layer 130 has a predetermined band gap and is a region where quantum wells are made to recombine electrons and holes. The active layer 130 may be formed of a single quantum well structure (SQW) or a multi quantum well structure (MQW). The multi quantum well structure may be formed by repeatedly stacking a plurality of quantum well layers and barrier layers. For example, the active layer 130 of the multi-quantum well structure may be formed by repeatedly stacking InGaN and GaN, or may be formed by repeatedly stacking AlGaN and GaN. In this case, since the emission wavelength generated by the combination of electrons and holes is changed according to the type of material constituting the active layer 130, it is preferable to adjust the semiconductor material included in the active layer 130 according to the target wavelength. Meanwhile, the active layer 130 is formed by removing a region where the first electrode 160 is to be formed.

The second semiconductor layer 140 may be a semiconductor layer doped with P-type impurities, thereby supplying holes to the active layer 130. For example, the second semiconductor layer 140 may use a GaN layer doped with P-type impurities, for example, Mg. However, the present invention is not limited thereto, and various semiconductor materials are possible. That is, a compound in which nitrides such as GaN, InN, AlN (Group III-V), and such nitrides are mixed at a predetermined ratio may be used. For example, various semiconductor materials including AlGaN and AlInGaN may be used. In addition, the second semiconductor layer 140 may be formed in multiple layers. Meanwhile, the second semiconductor layer 140 is formed by removing a region where the first electrode 160 is to be formed.

The transparent electrode 150 is formed on the second semiconductor layer 140 so that power applied through the second electrode 170 is evenly supplied to the second semiconductor layer 140. In addition, the transparent electrode 150 may be formed of a transparent conductive material so that light generated in the active layer 130 may be transmitted through. For example, the transparent electrode 150 may be formed using ITO, IZO, ZnO, RuOx, TiOx, IrOx, or the like.

The first and second electrodes 160 and 170 may be formed using a conductive material. For example, the first and second electrodes 160 and 170 may be formed using a metal material such as Ti, Cr, Au, Al, Ni, Ag, or an alloy thereof. have. In addition, the first and second electrodes 160 and 170 may be formed in a single layer or multiple layers. The first electrode 160 is formed on the exposed first semiconductor layer 120 by removing predetermined regions of the second semiconductor layer 140 and the active layer 130 to supply power to the first semiconductor layer 120. . In addition, the second electrode 170 is formed in a predetermined region above the transparent electrode 150 to supply power to the second semiconductor layer 140 through the transparent electrode 150. In this case, the first electrode 160 is formed near one corner of, for example, a rectangular light emitting device, and the second electrode 170 is formed at the center in contact with a surface opposite to the surface on which the first electrode 160 is formed. Can be. However, the formation positions of the first and second electrodes 160 and 170 may be variously changed. In addition, some regions of the first and second electrodes 160 and 170 according to the present invention may be removed to form a concave-convex structure having a predetermined pattern. For example, a portion of the first electrode 160 may be removed to expose the lower first semiconductor layer 120, and a portion of the second electrode 170 may be removed to lower the transparent electrode 150. Can be exposed. However, the first and second electrodes 160 and 170 are stepped between the upper and lower portions of the first and second electrodes 160 and 170 without exposing the first semiconductor layer 120 and the transparent electrode 150, respectively. May be formed. That is, the first and second electrodes 160 and 170 are formed in a line shape having a predetermined pattern, and have an uneven structure having a step between an area where no line is formed and an area where a line is formed, that is, between a lower part and an upper part. Can be formed. Here, the first and second electrodes 160 and 170 may be formed in the same pattern or in different patterns. The first and second electrodes 160 and 170 may be formed in various shapes, and may be formed in symmetrical shapes with each other, as shown in FIG. 1. Also, as shown in FIG. 3, a spiral pattern (FIG. 3 (a)) may be formed to be bent up or down in a plane (FIG. 3 (b)) so as to be connected from one side to the other side, and at least a portion thereof. It may be formed without being connected (FIG. 3 (c)), or may be formed in a pattern in which one region is removed (FIG. 3 (d)). That is, the first and second electrodes 160 and 170 may be formed in an integrated line shape, or may be formed in a plurality of line shapes spaced apart from each other by a predetermined interval. In this case, even when at least some of the first and second electrodes 160 and 170 are spaced apart from each other, the conductivity is not degraded because the first semiconductor layer 120 or the transparent electrode 150 is electrically connected. On the other hand, if the line width of the pattern is too narrow and the spacing between the patterns is too wide, the first and second electrodes 160 and 170 may collapse. In addition, if the spacing between the patterns is too narrow, the amount of wires introduced between the patterns may be reduced, thereby decreasing the bonding force between the wires and the electrodes. Therefore, in order to maintain the shape of the pattern and improve the bonding force, each of the first and second electrodes 160 and 170 may be formed at a ratio of 4: 1 to 1: 4 between the line width of the pattern and the pattern. Meanwhile, in order to form the first and second electrodes 160 and 170 in a concave-convex structure of a predetermined pattern, a metal material may be deposited and then a photo and etching process may be performed, or a photosensitive film may be formed on the entire upper portion, and then patterned and patterned. After depositing a metal material in the region, it may be formed by lifting off the photoresist. In this case, when the lift-off is used, the amount of the electrode material, that is, the metal material may be reduced, thereby reducing the cost.

As described above, the light emitting device 100 according to the exemplary embodiments of the present invention is packaged and the first and second electrodes 160 and 170 are wire-bonded to allow power to be applied from the outside. An embodiment of such a light emitting device package is illustrated in FIG. 4.

4 is a cross-sectional view of a light emitting device package according to an exemplary embodiment of the present invention, and FIG. 5 is an enlarged cross-sectional view illustrating a bonding state of one electrode and a wire of the light emitting device.

4 and 5, a light emitting device package according to an exemplary embodiment of the present invention includes a light emitting device 100 for emitting light, a package body 200 on which the light emitting device 100 is seated, and a package body. The lead frame 300 exposed from the inside of the 200 and protruded outward, the wire 400 for electrically connecting the light emitting device 100 to the lead frame 300, and the light emitting device 100 are encapsulated. The molding part 500 and the phosphor 600 provided in the molding part 500 are included. Here, the light emitting device 100 may use a body including a slug, a substrate, and a mold cup in addition to the package main body 200. Hereinafter, the package main body 200 will be described as an example.

The light emitting chip 100 is a compound semiconductor stacked structure having a P-N junction structure, and utilizes a phenomenon in which light is emitted by recombination of minority carriers (electrons or holes). As described with reference to FIG. 1, in the light emitting chip 100, a first semiconductor layer 120, an active layer 130, a second semiconductor layer 140, and a transparent electrode 150 are stacked on a substrate 110. . In addition, the first electrode 160 is formed on the exposed first semiconductor layer 120 by partially removing the transparent electrode 150, the second semiconductor layer 140, and the active layer 130, and the transparent electrode 150. The second electrode 170 is formed in a predetermined region of the image. In this case, the first and second electrodes 160 and 170 are formed in a concave-convex structure of a predetermined pattern. The light emitting device 100 may be attached onto the package body 200 using a paste (not shown), may be mounted on the housing 210 of the package body 200, and the lead frame 300. It may also be mounted on the top. As the paste, non-conductive materials such as epoxy resins and silicone resins can be used.

The package body 200 supports the lead frame 300 and has a housing 210 in which the light emitting device 100 is seated, and an opening formed on the housing 210 and emitting light generated from the light emitting device 100. It includes a reflector 220 to form. The package body 200 may be manufactured by a transfer molding method using an epoxy mold compound (EMC) in which a white pigment is added to a thermosetting resin, for example, an epoxy resin. Therefore, the housing 210 and the reflector 220 may be manufactured integrally. The reflector 220 includes a reflective surface protruding upward from the upper surface of the housing 210. In this case, the height of the reflective surface of at least one region of the reflector 220 may be adjusted. In this case, the emission range of the light generated by the light emitting device 100 may be adjusted. In addition, the reflective surface may be formed to be inclined at an angle. On the other hand, the shape of the reflector 220 may be changed in various ways to adjust the emission range of the light emitted from the light emitting device 100 according to the purpose, as well as circular, rectangular.

The lead frames 300 (310, 320) are for applying power to the light emitting device 100 from the outside, and include first and second lead frames (310, 320) formed on one side and the other side, respectively. The lead frame 300 is supported on the housing 210 and spaced apart from each other between the housing 210 and the reflector 220. That is, the first and second lead frames 310 and 320 are spaced apart from each other and extend from the housing 210 to one side and the other side of the package body 200. In addition, the first and second lead frames 310 and 320 may be bent to be in contact with the outer and bottom surfaces of the housing 210, or may be formed in contact with the outer surfaces of the housing 210 and may be formed in contact with the housing 210. It may be formed to be bent outward. On the other hand, at least one region of the lead frame 300 may have a predetermined uneven structure. That is, at least one region of the lead frame 300 connected to the wire 400 may have a concave-convex structure to improve the coupling force between the wire 400 and the lead frame 300. At this time, the uneven structure of the lead frame 300 is formed so that one region of the lead frame 300 has a step between the top and the bottom without exposing the package body 200. This is because the uneven structure of the lead frame 300 may lower the conductivity of the lead frame 300 when the package body 200 is exposed.

The wires 400 (410, 420) electrically connect the light emitting device 100 to the lead frame 300. The first wire 410 electrically connects the second electrode 170 of the light emitting device 100 and the first lead frame 310, and the second wire 420 of the first electrode of the light emitting device 100 ( 160 and the second lead frame 320 may be electrically connected. The wire 400 may be formed of gold (Au) or aluminum (Al). Ultrasonic bonding is used to bond the wire 400 to the first and second electrodes 160 and 170 of the light emitting device 100. For example, if one end of the wire 400 is contacted on the first and second electrodes 160 and 170 and then ultrasonic waves of 20 kHz or more are applied, the first and second electrodes 160 may be caused by ultrasonic vibration in the horizontal direction. , A friction force is generated between the 170 and the wire 400, thereby joining. At this time, constant heat and pressure may be applied simultaneously. The ultrasonic waves are generated by the ultrasonic wave generator, and the amplitude and energy are amplified or reduced through the booster and the horn to finally have the desired waveform and energy. The thus transmitted ultrasonic energy shakes the atoms constituting the first and second electrodes 160 and 170 and the wire 400 horizontally, and the atoms diffuse together to form a junction due to the temperature and pressure applied together. . Meanwhile, the wire 400 and the lead frame 300 may also be joined by ultrasonic waves. In this case, since the first and second electrodes 160 and 170 have a concave-convex structure, the wire 400 flows in between the patterns of the first and second electrodes 160 and 170 as shown in FIG. 5. Therefore, the contact area between the wire 400 and the first and second electrodes 160 and 170 is increased, thereby improving the bonding force. On the other hand, the applied ultrasound may be applied at a frequency of 20 kHz to 100 kHz, and may proceed at a temperature of 20 ℃ to 100 ℃. In addition, in order to increase the bonding efficiency, in addition to the ultrasonic wave in the horizontal direction, a vertical load or thermal compression may be applied simultaneously.

The molding part 500 encapsulates the light emitting device 100 and fixes the wire 400 connected to the light emitting device 100. In addition, the molding part 500 may also serve as a lens for collecting light generated from the light emitting device 100. Since the molding part 500 must transmit the light generated by the light emitting device 100 to the outside, the molding part 500 is formed of a transparent resin such as an epoxy resin or a silicone resin. In addition, the molding part 500 may further include a refractive index regulator (not shown). The sapphire powder may be used as the refractive index regulator. On the other hand, in addition to the refractive index adjuster, a diffuser (not shown) may be further added to uniformly emit light by further diffusing the light emitted from the light emitting device 100 by scattering. BaTiO ₃ , TiO ₂ , Al ₂ O ₃ , SiO _2, or the like may be used as the diffusion agent. In addition, the phosphor 600 may be added to the molding part 500. The phosphor 600 absorbs a part of the light generated from the light emitting device 100 and emits light having a wavelength different from that of the absorbed light. The phosphor 600 is composed of active ions in which impurities are mixed at appropriate positions of the host crystal. The active ions determine the emission color by determining the energy level involved in the light emission process, and the emission color is determined by the energy gap between the ground state and the excited state of the active ions in the crystal structure.

As described above, in the present invention, the first electrode 160 connected to the first semiconductor layer 120 and the second electrode 170 connected to the second semiconductor layer 140 are formed in a predetermined concave-convex structure, The first and second electrodes 160 and 170 are connected to the wire 400. In this case, since the first and second electrodes 160 and 170 have a concave-convex structure and thus have a wide cross-sectional area, the contact area with the wire 400 may increase, thereby improving the bonding force. That is, since the wire 400 is in contact with the side surfaces as well as the upper surfaces of the first and second electrodes 160 and 170, the wire 400 may be more firmly coupled to the first and second electrodes 160 and 170. Can be. Therefore, it is possible to prevent the wire 400 from falling from the first and second electrodes 160 and 170, thereby improving the operating reliability of the light emitting device.

On the other hand, the embodiment has been described with respect to the package of the wire bonding method in which the light emitting device 100 having the first and second electrodes 160, 170 having the uneven structure is bonded by the wire 400, but the light emitting device ( 100 may be packaged in various ways, such as the flip chip package illustrated in FIG. 6, in addition to wire bonding.

Referring to FIG. 6, the first semiconductor layer 120, the active layer 130, and the second semiconductor layer 140 are stacked on the substrate 110, and the second semiconductor layer 140 and the active layer 130 are removed. The first electrode 160 having an uneven structure is formed on the exposed first semiconductor layer 120, and the second electrode 170 having an uneven structure is formed in a predetermined region of the second semiconductor layer 140 to emit light. 100 is produced. At this time, since the light generated from the light emitting device 100 is emitted to the substrate 110 side, the substrate 110 may be made of a light transmitting material, for example, sapphire. In addition, a separate submount substrate 700 is prepared, and the third and fourth electrodes 710 and 720 are spaced apart from each other on the submount substrate 700. In this case, the third and fourth electrodes 710 and 720 of the sub-mount substrate 700 are formed at positions corresponding to the first and second electrodes 160 and 170 of the light emitting device 100. In addition, a first solder 730 is formed on the fourth electrode 710, and a second solder 740 is formed on the fourth electrode 720. In addition, the submount substrate 700 may contact the first and second solders 730 and 740 of the submount substrate 700 such that the first and second electrodes 160 and 170 of the light emitting device 100 correspond to each other. The light emitting element 100 is provided on the top. For example, the first and second solders 730 and 740 are bonded to the first and second electrodes 160 and 170 of the light emitting device 100 by ultrasonic bonding. In this case, the first and second solders 730 and 740 are formed up to the inside of the pattern of the first and second electrodes 160 and 170. Accordingly, a flip chip package light emitting device in which the sub-mount substrate 700 and the light emitting device 100 are firmly bonded to each other is manufactured.

Although the technical idea of the present invention has been specifically described according to the above embodiments, it should be noted that the above embodiments are for explanation purposes only and not for the purpose of limitation. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

110 substrate 120 first semiconductor layer
130: active layer 140: second semiconductor layer
150 transparent electrode 160 first electrode
170: second electrode

Claims

A stacked first semiconductor layer, active layer and second semiconductor layer;
First and second electrodes formed in predetermined regions on the first semiconductor layer and the second semiconductor layer, respectively;
At least one region of the first and second electrodes is a light emitting device having a concave-convex structure.

The light emitting device of claim 1, wherein the first and second electrodes are formed in an integrated line shape or a plurality of line shapes spaced apart from each other by a predetermined interval.

The light emitting device of claim 1, wherein the uneven structure is formed such that at least one region exposes at least a portion of the first semiconductor layer or the second semiconductor layer, respectively.

The light emitting device of claim 1, wherein the uneven structure is formed such that at least one region has a step between an upper portion and a lower portion of each of the first and second electrodes.

The light emitting device according to any one of claims 1 to 4, further comprising a wire bonded to the first and second electrodes, respectively.

The light emitting device of claim 5, wherein the wire is joined to the inside of the uneven structure of the first and second electrodes.

The package device of claim 6, further comprising: a package body on which the light emitting device is mounted; And
Further comprising a lead frame provided on the package body,
The wire connects the lead frame with the first and second electrodes of the light emitting device.

The light emitting device of claim 7, wherein at least one region of the lead frame connected to the wire has an uneven structure.

The apparatus of claim 1, further comprising: a submount substrate having third and fourth electrodes respectively corresponding to the first and second electrodes;
The light emitting device further comprises first and second solders respectively formed on the third and fourth electrodes and bonded to the first and second electrodes, respectively.