KR20070097619A - Light emitting device having zenor diode therein and method of fabricating the same - Google Patents

Abstract

A light emitting device having a zener diode and a manufacturing method thereof are provided to achieve a high output power by employing a silicon substrate with good heat dissipation performance. A P-type silicon substrate(21) has a zener diode region(A) and a light emitting diode region(B). A first N-type compound semiconductor layer(23a) is jointed to the zener diode region of the P-type silicon substrate to exhibit characteristics of a zener diode. A second N-type compound semiconductor layer(23b) is positioned on the light emitting diode region of the P-type silicon substrate, and is spaced apart from the first N-type compound semiconductor layer. A P-type compound semiconductor layer(27) is positioned on the second N-type compound semiconductor layer. An active layer(25) is interposed between the second N-type compound semiconductor layer and the P-type compound semiconductor layer. A transparent ZnO electrode layer(29) is formed on the P-type compound semiconductor layer.

Description

LIGHT EMITTING DEVICE HAVING ZENOR DIODE THEREIN AND METHOD OF FABRICATING THE SAME

1 is a cross-sectional view illustrating a light emitting device according to an embodiment of the present invention.

2 is a cross-sectional view showing an example of a light emitting diode package equipped with a light emitting device according to an embodiment of the present invention.

3 is an equivalent circuit diagram of the LED package of FIG. 2.

4 to 6 are cross-sectional views illustrating a method of manufacturing a light emitting device according to an embodiment of the present invention.

The present invention relates to a light emitting device and a method of manufacturing the same, and more particularly to a light emitting device having a zener diode and a method of manufacturing the same.

A light emitting diode is an electroluminescence device that emits light by a forward current. Compound semiconductors, such as indium phosphorus (InP), gallium arsenide (GaAs), and gallium phosphorus (GaP), have been used as materials for light emitting diodes emitting red or green light, and gallium nitride (GaN) series compound semiconductors have been used. It has been developed and used as a material of a light emitting diode that emits ultraviolet light and blue light.

Light emitting diodes are widely used in various display devices, backlight sources, and the like. Recently, a technology for emitting white light by using three light emitting diode chips emitting red, green, and blue light, or converting wavelengths using phosphors has been developed. Therefore, the lighting device is also expanding its application range.

In general, GaN-based compound semiconductors are epitaxially grown on sapphire substrates with similar crystal structures and lattice constants to reduce the occurrence of crystal defects. Since sapphire is an insulating material, electrode pads of the light emitting diode are formed on the growth surface of the epi layer. However, when using a substrate made of an insulating material such as sapphire, it is difficult to prevent electrostatic discharge due to static electricity introduced from the outside, and thus damage of the diode is likely to be caused, thereby reducing the reliability of the device. Therefore, when packaging a light emitting diode, a separate zener diode is used together with the light emitting diode to prevent electrostatic discharge. However, Zener diodes are expensive and the addition of processes to mount Zener diodes increases the number of LED package processes and manufacturing costs.

In addition, sapphire has a low thermal conductivity, and thus does not easily release heat generated from the light emitting diodes to the outside. This low heat dissipation performance makes it difficult to apply light emitting diodes in applications requiring high power.

Meanwhile, a transparent electrode layer is formed to supply a current to the light emitting diode. Generally, Ni / Au transparent electrode layers and ITO transparent electrode layers are used. However, the thickness of the Ni / Au transparent electrode layer and the ITO transparent electrode layer are limited to about 0.005˜0.2 μm due to the limitation of light transmission characteristics. This thickness limitation makes it difficult to design various shapes of the transparent electrode layer, and as a result, it is difficult to obtain a uniform light distribution.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a light emitting device including a light emitting diode and a zener diode in a single chip, and a method of manufacturing the same.

Another object of the present invention is to provide a light emitting device capable of achieving high output using a substrate having excellent heat dissipation performance and a method of manufacturing the same.

Another object of the present invention is to provide a light emitting device employing a transparent electrode layer capable of various shape designs and a method of manufacturing the same.

In order to achieve the above technical problem, the present invention discloses a light emitting device having a zener diode and a method of manufacturing the same. A light emitting device according to an aspect of the present invention includes a P-type silicon substrate having a zener diode region and a light emitting diode region. A first N-type compound semiconductor layer is bonded to the zener diode region of the P-type silicon substrate to exhibit zener diode characteristics with the P-type silicon substrate. In addition, a second N-type compound semiconductor layer is positioned on the light emitting diode region of the P-type silicon substrate. The second N-type compound semiconductor layer is spaced apart from the first N-type compound semiconductor layer. On the other hand, a P-type compound semiconductor layer is located above the second N-type compound semiconductor layer, and an active layer is interposed between the second N-type compound semiconductor layer and the P-type compound semiconductor layer. In addition, a ZnO transparent electrode layer is formed on the P-type compound semiconductor layer. Accordingly, a light emitting device having a zener diode including the P-type silicon substrate and the first N-type compound semiconductor layer, and a light emitting diode including the second N-type compound semiconductor layer, the active layer, and the P-type compound semiconductor layer in a single chip. It can be provided to prevent the electrostatic discharge damage of the light emitting diode. In addition, it is possible to provide a light emitting device having excellent heat dissipation performance by adopting a silicon substrate, and the transparent electrode layer can be formed thick by adopting a ZnO transparent electrode layer.

Meanwhile, the first and second N-type compound semiconductor layers may be formed from the same N-type compound semiconductor layer grown on the P-type silicon substrate. Therefore, the first N-type compound semiconductor layer and the second N-type compound semiconductor layer can be formed using the same process, and the process can be prevented from becoming complicated.

The P-type compound semiconductor layer may be positioned on one region of the second N-type compound semiconductor layer, and another region of the second N-type compound semiconductor layer may be exposed. Accordingly, the electrode pads may be variously formed.

The ZnO transparent electrode layer is positioned on the P-type compound semiconductor layer. In addition, electrode pads may be formed on the first and second N-type compound semiconductor layers and the transparent electrode layer, respectively.

A light emitting device manufacturing method according to another aspect of the present invention includes growing an N-type compound semiconductor layer, an active layer, a P-type compound semiconductor layer and a ZnO transparent electrode layer on a P-type silicon substrate having a zener diode region and a light emitting diode region. . The ZnO transparent electrode layer, the P-type compound semiconductor layer, the active layer, and the N-type compound semiconductor layer are patterned using photolithography and etching processes. By the patterning process, a first N-type compound semiconductor layer having an upper surface exposed on the zener diode region is formed, and a light emitting diode is formed on the light emitting diode region. In addition, a ZnO transparent electrode layer defined on the light emitting diode is formed. The P-type silicon substrate and the first N-type compound semiconductor layer have zener diode characteristics, and the light emitting diode has a second N-type compound semiconductor layer spaced apart from the first N-type compound semiconductor layer, and the second N-type compound And an active layer interposed between the P-type compound semiconductor layer and the second N-type compound semiconductor layer positioned on the semiconductor layer. Accordingly, a light emitting device in which a zener diode and a light emitting diode are formed in a single chip is manufactured, and thus processes for manufacturing or mounting a separate zener diode to prevent electrostatic discharge can be omitted.

Meanwhile, the ZnO transparent electrode layer defined on the light emitting diode may be formed in various shapes, for example, the side surfaces thereof may be formed to be inclined at a predetermined angle with respect to a surface perpendicular to the P-type compound semiconductor layer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to ensure that the spirit of the present invention can be fully conveyed to those skilled in the art. Therefore, the present invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

1 is a cross-sectional view illustrating a light emitting device 20 according to an embodiment of the present invention.

Referring to FIG. 1, the P-type silicon substrate 21 has a zener diode region A and a light emitting diode region B. As shown in FIG. The first N-type compound semiconductor layer 23a is positioned on the zener diode region A. FIG. The first N-type compound semiconductor layer 23a and the P-type silicon substrate 21 are p-n bonded to form a zener diode 22.

Meanwhile, the second N-type compound semiconductor layer 23b is positioned on the light emitting diode region B of the P-type silicon substrate 21. The second N-type compound semiconductor layer 23b is spaced apart from the first N-type compound semiconductor layer 23a. The first and second N-type compound semiconductor layers 23a and 23b may be formed from the same N-type compound semiconductor layer grown on the P-type silicon substrate 21. That is, the first and second N-type compound semiconductor layers 23a and 23b may be formed by separating the N-type compound semiconductor layer grown on the P-type silicon substrate 21.

The P-type silicon substrate 21 is generally used in a semiconductor manufacturing process, can be provided in a larger size than the sapphire substrate, and is inexpensive. In addition, the P-type impurities may be further doped into the P-type silicon substrate 21 using an ion implantation technique such as implantation. Meanwhile, the first and second N-type compound semiconductor layers 23 may be formed of (Al, In, Ga) N compound semiconductors.

Meanwhile, a P-type compound semiconductor layer 27 is positioned on the second N-type compound semiconductor layer 23b and an active layer is interposed between the second N-type compound semiconductor layer 23b and the P-type compound semiconductor layer 27. do. The active layer 25 may be a single quantum well formed of a single layer or a multi-quantum well of a stacked structure. The active layer 25 and the P-type compound semiconductor layer 27 may be formed of a semiconductor layer of (Al, Ga, In) N, respectively. As illustrated, the P-type compound semiconductor layer 27 may be located above one region of the second N-type compound semiconductor layer 23b, and the other region of the second N-type compound semiconductor layer 23b may be exposed. Can be.

The N-type compound semiconductor layer 23b, the active layer 25, and the P-type compound semiconductor layer 27 constitute a light emitting diode 26.

A ZnO transparent electrode layer 29 is formed on the P-type compound semiconductor layer 27. The ZnO transparent electrode layer 29 may be formed using a molecular beam growth method, a metal organic chemical vapor deposition method, or the like. The ZnO transparent electrode layer 29 is ohmic contacted to the P-type compound semiconductor layer 27, and conventional technical means such as a highly doped tunnel layer (not shown) may be adopted for this purpose.

ZnO is a metal oxide that is excellent in etching and excellent in light transmittance and electrical properties. Therefore, the ZnO transparent electrode layer 29 may be formed relatively thicker than Ni / Au and indium tin oxide (ITO), and thus may be formed in various shapes to improve light emission characteristics. For example, as shown in FIG. 1, the ZnO transparent electrode layer 29 has a cross-sectional shape that gradually narrows along the emission direction of light, that is, a side surface thereof is perpendicular to the P-type compound semiconductor layer 27. It may be formed to be inclined at an angle. The shape of the transparent electrode layer 29 prevents light loss due to total internal reflection or concentration of light near the upper edge of the light emitting diode 26. As a result, the light emitting efficiency of the light emitting diode 26 is improved, and the light emitting diode 26 exhibits a uniform light distribution.

In addition, N-type electrode pads 31a and 31b are formed on the first and second N-type compound semiconductor layers 23a and 23b, and P-type electrode pads are formed on the ZnO transparent electrode layer 29. 33) is formed. The electrode pads 31a, 31b, 33 are used as contact pads for electrically connecting the zener diode 22 and the light emitting diode 26 to an external circuit. In addition, the electrode pad 35 may be formed on the lower surface of the P-type silicon substrate 21.

According to this embodiment, by forming the light emitting diodes 26 on the P-type silicon substrate 21, heat generated in the light emitting diodes 26 can be easily released. In addition, since the light emitting device according to the present embodiment includes the zener diode 22 therein, damage caused by electrostatic discharge can be prevented. Therefore, in the related art, a zener diode mounted with a light emitting element can be omitted, thereby reducing the number of package processes and the cost of package manufacture. In addition, by adopting the ZnO transparent electrode layer 29, it is possible to provide a light emitting device having a uniform light distribution and improved luminous efficiency.

2 is a cross-sectional view illustrating an example of a light emitting diode package equipped with a light emitting device 20 according to an exemplary embodiment of the present invention, and FIG. 3 is an equivalent circuit diagram of the light emitting diode package of FIG. 2.

Referring to FIG. 2, the LED package includes leads 37a and 37b for electrically connecting the light emitting device 20 to an external power source. The light emitting device 20 is die-bonded on the lead 37a, and thus the silicon substrate 21 is electrically connected to the lead 37a.

Meanwhile, the N-type electrode pad 31a on the zener diode 22 and the P-type electrode pad 33 on the light emitting diode 26 are electrically connected to the lead 37b through the bonding wires, and the light emitting diode 26 is disposed on the light emitting diode 26. The N-type electrode pad 31b is electrically connected to the lead 37a through a bonding wire. Accordingly, the light emitting diodes 26 and the zener diodes 22 are connected in anti-parallel as in the circuit shown in FIG.

When a forward voltage is applied by connecting power to the leads 37a and 37b, the forward voltage is applied to the light emitting diodes 26 to emit light. Meanwhile, the zener diode 22 prevents the forward voltage of the light emitting diode 26 from excessively increasing, thereby preventing the light emitting diode 26 from being damaged by the overvoltage. The breakdown voltage of the zener diode 22 may be controlled by adjusting the doping concentration of the P-type silicon substrate 21 and / or the doping concentration of the first N-type compound semiconductor layer 23a.

4 to 6 are cross-sectional views illustrating a method of manufacturing a light emitting device according to an embodiment of the present invention.

Referring to FIG. 4, an N-type compound semiconductor layer 23, an active layer 25, and a P-type compound semiconductor layer 27 are grown on a P-type silicon substrate 21 having a zener diode region and a light emitting diode region. The N-type compound semiconductor layer 23, the active layer 25, and the P-type compound semiconductor layer 27 may be formed using metal organic chemical vapor deposition (MOCVD), hydride vapor phase growth (HVPE), or molecular beam growth (MBE) technology. It can be grown on the P-type silicon substrate 21.

Before growing the N-type compound semiconductor layer 23, at least the zener diode region A of the P-type silicon substrate 21 may be further doped with P-type impurities using an ion implantation technique such as implantation. .

Meanwhile, a ZnO transparent electrode layer 29 is formed on the P-type compound semiconductor layer 27. The ZnO transparent electrode layer 29 may be formed using molecular beam growth or metal organic chemical vapor deposition techniques. Since the ZnO transparent electrode layer 29 has an energy band gap similar to that of the gallium nitride-based compound semiconductor layer, the ZnO transparent electrode layer 29 has excellent light transmittance. Therefore, the ZnO transparent electrode layer 29 may be formed to a thicker thickness than the conventional transparent electrode layer such as Ni / Au or ITO, and may be formed to a thickness of, for example, several tens of microns.

Referring to FIG. 5, the ZnO transparent electrode layer 29, the P-type compound semiconductor layer 27, the active layer 25, and the N-type compound semiconductor layer 23 are patterned using a photolithography and etching process to form the layers 23. , 25, 27, 29). Accordingly, the first N-type compound semiconductor layer 23a on the zener diode region A and the second N-type compound semiconductor layer 23b on the light emitting diode region B are spaced apart from each other.

Referring to FIG. 6, the layers 23, 25, 27, and 29 are again patterned to form the ZnO transparent electrode layer 29, the P-type compound semiconductor layer 27, and the active layer 25 on the light emitting diode region B. Remove some. As a result, the ZnO transparent electrode layer 29, the P-type compound semiconductor layer 27, and the active layer 25 remain on one region of the first N-type compound semiconductor layer 23b on the light emitting diode region B. The first N-type compound semiconductor layer 23b in the region is exposed.

Meanwhile, the ZnO transparent electrode layer 29, the P-type compound semiconductor layer 27, and the active layer 25 on the zener diode region A are removed. The ZnO transparent electrode layer 29, the P-type compound semiconductor layer 27 and the active layer 25 on the zener diode region A are the ZnO transparent electrode layer 29 and the P-type compound semiconductor layer 27 on the light emitting diode region B. ) And portions of the active layer 25 may be removed together.

Subsequently, the ZnO transparent electrode layer 29 may be patterned again so that its cross section has a desired shape. That is, as shown, the sides may be formed to be inclined. In contrast, the ZnO transparent electrode layer 29 is formed while removing a portion of the ZnO transparent electrode layer 29, the P-type compound semiconductor layer 27 and the active layer to expose the second N-type compound semiconductor layer 23. It may be patterned to have a predetermined shape.

Subsequently, N-type electrode pads 31a and 31b of FIG. 1 are formed on the exposed first and second N-type compound semiconductor layers 23a and 23b, and P-type is formed on the ZnO transparent metal layer 29. The electrode pad 33 is formed. In addition, the electrode pad 35 may be formed on the lower surface of the P-type silicon substrate 21. Thus, the light emitting device 20 of FIG. 1 is completed.

In the present embodiment, after separating the first and second N-type compound semiconductor layers 23a and 23b, the ZnO transparent electrode layer 29, the P-type compound semiconductor layer 27, and the light emitting diode region B Although the ZnO transparent electrode layer 29, the P-type compound semiconductor layer 27 and the active layer on the part of the active layer and the zener diode region A are described as being removed, the ZnO transparent electrode layer 29 and the P-type compound semiconductor layer 27 are described. And patterning the active layer 25 first, and then separating the first and second N-type compound semiconductor layers 23a and 23b.

According to the present embodiments, a light emitting device having a zener diode 22 and a light emitting diode 26 in a single chip can be manufactured, and the shape of the light emitting surface can be easily controlled by adopting the ZnO transparent electrode layer 29. Can be.

According to embodiments of the present invention, it is possible to provide a light emitting device having a light emitting diode and a zener diode in a single chip, and to provide a light emitting device capable of achieving high output by adopting a silicon substrate having excellent heat emission performance. have. Further, by adopting the ZnO transparent electrode layer, the transparent electrode layer can be formed thicker than conventional Ni / Au and ITO, so that various shapes of the light emitting surface can be designed. Therefore, it is possible to reduce light loss due to total internal reflection, and to provide a light emitting device exhibiting uniform light distribution.

Claims (6)

A P-type silicon substrate having a zener diode region and a light emitting diode region; A first N-type compound semiconductor layer bonded to the zener diode region of the P-type silicon substrate and exhibiting zener diode characteristics together with the P-type silicon substrate; A second N-type compound semiconductor layer on the light emitting diode region of the P-type silicon substrate and spaced apart from the first N-type compound semiconductor layer; A P-type compound semiconductor layer positioned on the second N-type compound semiconductor layer; An active layer interposed between the second N-type compound semiconductor layer and the P-type compound semiconductor layer: And A light emitting device comprising a ZnO transparent electrode layer formed on the P-type compound semiconductor layer. The light emitting device of claim 1, wherein the first and second N-type compound semiconductor layers are formed from the same N-type compound semiconductor layer grown on the P-type silicon substrate. The light emitting device of claim 1, wherein the P-type compound semiconductor layer is positioned on one region of the second N-type compound semiconductor layer, and another region of the second N-type compound semiconductor layer is exposed. The method according to claim 3, The light emitting device further comprises electrode pads formed on the first and second N-type compound semiconductor layers and the ZnO transparent electrode layer. Growing an N-type compound semiconductor layer, an active layer and a P-type compound semiconductor layer on a P-type silicon substrate having a zener diode region and a light emitting diode region, Forming a ZnO transparent electrode layer on the P-type compound semiconductor layer, The ZnO transparent electrode layer, the P-type compound semiconductor layer, the active layer, and the N-type compound semiconductor layer are patterned by using a photolithography and etching process to form a first N-type compound semiconductor layer having an upper surface exposed on the zener diode region. And forming a light emitting diode and a ZnO transparent electrode layer defined on the light emitting diode on the light emitting diode region. The P-type silicon substrate and the first N-type compound semiconductor layer have zener diode characteristics, The light emitting diode may include a second N-type compound semiconductor layer spaced apart from the first N-type compound semiconductor layer, a P-type compound semiconductor layer disposed on the second N-type compound semiconductor layer, the P-type compound semiconductor layer, and the first 2. A method of manufacturing a light emitting device comprising an active layer interposed between an N-type compound semiconductor layer. The method according to claim 5, Side surfaces of the ZnO transparent electrode layer defined on the light emitting diode are inclined at a predetermined angle with respect to the surface perpendicular to the P-type compound semiconductor layer.

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