KR101239856B1 - Light-emitting diode and Method of manufacturing the same - Google Patents

Abstract

The present invention includes a substrate, an N-type semiconductor layer formed on the substrate, and a P-type semiconductor layer formed on the N-type semiconductor layer, wherein the N-type semiconductor layer includes an N-type compound layer doped with N-type impurities at a predetermined concentration; The present invention provides a light emitting diode and a method for manufacturing the same, comprising a stacked structure in which an N-type compound layer doped over a predetermined concentration is alternately repeatedly formed.

The present invention forms an N-type semiconductor layer having a structure in which an N-type compound layer having a predetermined concentration and an N-type compound layer overdoped with a concentration higher than the predetermined concentration are formed, thereby improving current spreading characteristics of the light emitting diode to achieve uniform luminance characteristics. Can be secured and the luminous efficiency can be improved. In addition, it is possible to prevent the damage of the light emitting diode due to the electrostatic discharge to improve the reliability, it is expected to improve the life of the light emitting diode.

Light Emitting Diode, LED, Gallium Nitride, GaN, Si, Doping

Description

Light emitting diode and method of manufacturing the same

1 is a schematic cross-sectional view showing a conventional light emitting diode.

2 is a schematic cross-sectional view for explaining a light emitting diode according to the present invention;

3A to 3D are cross-sectional views illustrating a method of manufacturing an embodiment of a light emitting diode according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10, 100: substrate 20, 110: buffer layer

50, 150: N-type semiconductor layer 60, 160: active layer

70 and 170: P-type semiconductor layer

The present invention relates to a light emitting diode and a method of manufacturing the same, and more particularly, to improve the current diffusion characteristics in the nitride-based semiconductor light emitting diode to improve the luminous efficiency and to ensure the reliability of electrostatic discharge and its manufacture It is about a method.

A light emitting diode (LED) refers to a device that makes a small number of carriers (electrons or holes) injected using a pn junction structure of a semiconductor and emits a predetermined light by recombination thereof. GaAs, AlGaAs, GaN Various colors may be realized by configuring a light emitting source by changing a compound semiconductor material such as InGaN, AlGaInP, or the like.

The light emitting diode has a smaller power consumption and a longer lifespan than a conventional light bulb or a fluorescent lamp, and can be installed in a narrow space and is strong in vibration. Such light emitting diodes are used as display devices and backlights because they have excellent characteristics in terms of power consumption and durability, and active research is being conducted to apply them to general lighting applications.

Among the compound semiconductors, nitride-based semiconductor materials exhibit excellent luminescent properties for visible and UV regions, and are also used in high power, high frequency electronic devices. In particular, gallium nitride (GaN) has a direct transition bandgap of 3.4 eV at room temperature and is combined with materials such as indium nitride (InN) and aluminum nitride (AlN) at 1.9 eV (InN) to 3.4 eV (GaN). It has a direct energy bandgap of up to 6.2eV (AlN), which is a material with great potential for application of optical devices due to the wide wavelength range from visible light to ultraviolet light.

1 is a schematic cross-sectional view showing a conventional light emitting diode.

Referring to FIG. 1, a light emitting diode includes a substrate 1, a buffer layer 2 formed on the substrate 1, an N-type semiconductor layer 3, and an active layer 4 sequentially formed on the buffer layer 2. ) And the P-type semiconductor layer 5.

P-type and N-type semiconductor layers 5 and 3 formed on the upper and lower portions of the active layer 4 respectively supply current to the active layer 4 to emit light. In general, in a gallium nitride-based semiconductor light emitting diode, a GaN semiconductor compound doped with magnesium (Mg) is used as the P-type semiconductor layer 5, and silicon (Si) is used as the N-type semiconductor layer 3. Doped GaN semiconductor compounds are used.

However, such a conventional light emitting diode has a poor current spreading property, leading to a decrease in luminous efficiency, and has a disadvantage in that luminance is not uniform. In addition, the light emitting diode may be damaged by the electrostatic discharge (ESD), which may shorten the lifespan of the light emitting diode.

The present invention has been made to solve the above problems, and includes an N-type semiconductor layer having a structure in which an N-type compound layer doped with an N-type impurity of a predetermined concentration and an N-type compound layer overdoped with a concentration higher than the predetermined concentration are repeatedly stacked. Accordingly, an object of the present invention is to provide a light emitting diode and a method of manufacturing the same, which may improve current spreading characteristics of the light emitting diode to secure uniform luminance characteristics, prevent damage of the light emitting diode due to electrostatic discharge, and improve reliability.

The present invention includes a substrate, an N-type semiconductor layer formed on the substrate and a P-type semiconductor layer formed on the N-type semiconductor layer in order to achieve the above object, wherein the N-type semiconductor layer has a predetermined concentration of N-type impurities The present invention provides a light emitting diode comprising a stacked structure in which an N-type compound layer doped with and an N-type compound layer overdoped with a concentration higher than the predetermined concentration are alternately formed.

The N-type or P-type semiconductor layer may be gallium nitride (GaN), and the N-type impurity may be silicon (Si). The N-type compound layer and the over-doped N-type compound layer may be formed of a laminated structure of 10 to 50 layers.

The predetermined concentration may be 1 × 10 ¹⁹ to 1 × 10 ²² / cm ³ , and the over-doped N-type compound layer may be doped at a concentration 10 to 100 times higher than the predetermined concentration.

A buffer layer of GaN, InN or AlN may be further included between the substrate and the N-type semiconductor layer.

The present invention provides a method of forming an N-type semiconductor layer by alternately repeatedly growing an N-type compound layer doped with N-type impurities at a predetermined concentration and an N-type compound layer doped with a concentration higher than the predetermined concentration on a substrate, and the N-type semiconductor layer. It provides a light emitting diode manufacturing method comprising the step of forming a P-type semiconductor layer on the semiconductor layer.

The N-type or P-type semiconductor layer may be gallium nitride (GaN), and the N-type impurity may be silicon (Si).

The forming of the N-type semiconductor layer may include growing a N-type compound layer doped with N-type impurities to a predetermined concentration by using a source gas of Ga, N, and Si simultaneously, and stopping using the Ga source gas and using N And growing the over-doped N-type compound layer to a concentration higher than the predetermined concentration on the N-type compound layer using a source gas of Si.

The N-type compound layer or the over-doped N-type compound layer may be grown to tens to hundreds of microseconds. The predetermined concentration may be 1 × 10 ¹⁹ to 1 × 10 ²² / cm ³ , and the over-doped N-type compound layer may be doped at a concentration 10 to 100 times higher than the predetermined concentration.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. Wherein like reference numerals refer to like elements throughout.

2 is a schematic cross-sectional view illustrating a light emitting diode according to the present invention.

Referring to FIG. 2, the light emitting diode includes a buffer layer 20 sequentially formed on the substrate 10, an undoped semiconductor layer 30, a first N-type semiconductor layer 40, and a second N-type formed in a stacked structure. The semiconductor layer 50, the third N-type semiconductor layer 60, the active layer 80, and the P-type semiconductor layer 90 are included. The second N-type semiconductor layer 50 is laminated by alternately repeating the N-type compound layer 50a doped at a predetermined concentration and the N-type compound layer 50b overdoped at a concentration 10 to 100 times higher than the predetermined concentration. It is formed into a structure.

As the substrate 10, sapphire (Al ₂ O ₃ ), silicon carbide (SiC), silicon (Si), or the like is used.

The buffer layer 20 is formed to reduce lattice mismatch between the substrate and subsequent layers during crystal growth, and is formed including gallium nitride (GaN), indium nitride (InN), or aluminum nitride (AlN), which are semiconductor materials.

The undoped semiconductor layer 30 is to improve the crystallinity of the semiconductor thin film grown on the upper surface, it is preferably formed using the same material.

The first, second and third N-type semiconductor layers 40, 50, and 60 are electron-generated layers, and preferably, gallium nitride (GaN) implanted with N-type impurities is not limited thereto. Layers of material of various semiconductor properties are possible.

The first, second, and third N-type semiconductor layers 40, 50, and 60 are formed by doping N-type impurities, and the second N-type semiconductor layer 50 is N doped to a predetermined concentration. The type compound layer 50a and the N-type compound layer 50b overdoped at a concentration 10 to 100 times higher than the predetermined concentration are alternately and repeatedly stacked. The N-type compound layer 50a and the over-doped N-type compound layer 50b of the second N-type semiconductor layer 50 are formed by stacking 10 to 50 layers. Due to the second N-type semiconductor layer 50 formed in such a laminated structure, in particular, due to the over-doped N-type compound layer 50b it can be obtained excellent current diffusion characteristics.

The active layer 80 has a predetermined band gap and is a region in which quantum wells are made to recombine electrons and holes, and may include InGaN. According to the kind of material constituting the active layer 80, the emission wavelength generated by the combination of electrons and holes is changed. Therefore, it is preferable to adjust the semiconductor material contained in the active layer 80 according to the target wavelength.

In addition, the P-type semiconductor layer 90 is a layer in which holes are generated, and preferably, gallium nitride (GaN) doped with P-type impurities is not limited thereto. A material layer having various semiconductor properties may be used.

The light emitting diode of the present invention is not limited to the above description, and the material layer may be omitted or changed, or various material layers may be added according to the characteristics of the device and the convenience of the process. For example, to increase light efficiency, a P-type cladding layer such as AlGaN having a larger energy band gap may be further configured between the active layer 80 and the P-type semiconductor layer 90.

The light emitting diode of the present invention includes an N-type semiconductor layer having a structure in which an N-type compound layer having a predetermined concentration and an N-type compound layer overdoped with a concentration higher than the predetermined concentration are repeatedly stacked, thereby reducing electrical resistance of the semiconductor material. It can improve the current spreading characteristics. Therefore, it is possible to obtain a uniform luminance characteristic, there is an advantage that can improve the luminous efficiency. In addition, the present invention is due to the N-type semiconductor layer including the N-type compound layer and the doped N-type compound layer repeatedly stacked, there is an effect that can prevent damage due to electrostatic discharge.

3A to 3D are cross-sectional views illustrating a method of manufacturing an embodiment of a light emitting diode according to the present invention.

As the deposition and growth method of semiconductor, metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), molecular beam growth method Various methods including (MBE; Molecular Beam Epitaxy) and Hydride Vapor Phase Epitaxy (HVPE) can be used. In this embodiment, organometallic chemical vapor deposition (MOCVD) is used.

Referring to FIG. 3A, a buffer layer 120, an undoped GaN layer 130 and an undoped GaN layer 130 and a first N-type GaN layer 140 are sequentially formed on the substrate 110.

In general, gallium nitride (GaN) semiconductors do not have a lattice matched substrate, and a large difference in lattice constant and thermal expansion coefficient makes it difficult to grow a high quality gallium nitride (GaN) semiconductor thin film. Therefore, after a buffer layer is grown on a heterogeneous substrate having a mismatched lattice constant, a gallium nitride (GaN) semiconductor crystal thin film is grown. The defects of high concentration resulting from the mismatch of lattice constants are generated in the buffer layer region of the semiconductor thus grown, but the crystal defects are reduced in the thin film layer deposited on the buffer layer to be finally grown by being substantially continuous.

The substrate 110 refers to a conventional wafer for fabricating a light emitting diode and includes at least one of Al ₂ O ₃ , SiC, ZnO, Si, GaAs, GaP, LiAl ₂ O ₃ , BN, AlN, and GaN. The substrate 110 is used. In this embodiment, a crystal growth substrate 110 made of sapphire (Al ₂ O ₃ ) is used.

As described above, a buffer layer 120 is formed on the substrate 110 to reduce lattice mismatch between the substrate 110 and subsequent layers during crystal growth. The buffer layer 120 may include GaN, InN, or AlN, which is a semiconductor material.

In addition, an undoped GaN layer 130 is formed on the buffer layer 120. This is preferable in order to improve the crystallinity of the GaN semiconductor thin film grown on its upper surface.

The first N-type semiconductor layer 140 is formed on the undoped GaN layer 130. Its growth thickness is 0.5 to 5 μm, and is formed by doping N-type impurities at a concentration of 1 × 10 ¹⁸ to 1 × 10 ²⁰ / cm ³ .

Referring to FIG. 3B, a second N-type semiconductor layer 150 is formed on the first N-type semiconductor layer 140. The N-type compound layer 150a doped with N-type impurities at a predetermined concentration on the first N-type semiconductor layer 140 and the N-type compound layer 150b over-doped at a concentration 10 to 100 times higher than the predetermined concentration. The N-type compound layer 150a and the over-doped N-type compound layer 150b are grown in a stacked structure of 10 to 50 layers. Each layer is grown to a thickness of tens to hundreds of millimeters.

In this embodiment, a GaN layer doped with Si is formed as the second N-type semiconductor layer 150. In this case, trimethylgallium (TMGa) or triethylgallium (TEGa) may be used as a source gas for Ga, and ammonia (NH ₃ ), monomethylhydrazine (MMHy), and dimethylhydrazine (DMHy) may be used as a source gas for N. In addition, silane (SiH ₄ ), disilane (Si ₂ H ₆ ) or tetraethoxysilane (Si (OEt) ₄ ) may be used as a source gas for Si. This will be described in detail below.

First, source gases for Ga, N, and Si are simultaneously injected to form an N-type compound layer 150a doped with Si at a predetermined concentration on the first N-type semiconductor layer 140. In this case, the predetermined concentration is 1 × 10 ¹⁹ to 1 × 10 ²² / cm ³ , and the doping concentration of the N-type compound layer 150a formed on the first N-type semiconductor layer 140 is the first N-type. It is preferable that the doping concentration is 50 to 100 times higher than the doping concentration of the semiconductor layer 140.

After the N-type compound layer 150a is grown to a thickness of several tens to several hundred microseconds, the doped N-type compound layer 150b is grown to be 10 to 100 times higher than the N-type compound layer 150a. To this end, when the injection of the source gas for Ga is stopped and only the source gas for N and Si is injected, the overdoped N-type compound layer 150b grows on the N-type compound layer 150a. After the overdoped N-type compound layer 150b is grown to a thickness of several tens to several hundred microns, the same process is repeated by simultaneously injecting a source gas for Ga again.

The second N-type semiconductor layer 150 in which 10 to 50 layers of the N-type compound layer 150a and the doped N-type compound layer 150b are repeatedly stacked on the first N-type semiconductor layer 140 through the above method. ).

Referring to FIG. 3C, a third N-type semiconductor layer 160, an active layer 180, and a P-type semiconductor layer 190 are formed on the second N-type semiconductor layer 150.

The third N-type semiconductor layer 160 is formed on the second N-type semiconductor layer 150. Its growth thickness may be the same as the first N-type semiconductor layer 140, or may be smaller than the first N-type semiconductor layer 140, N-type at a concentration of 1 × 10 ¹⁸ to 1 × 10 ²⁰ / cm ³ It is formed by doping with impurities.

The active material 180 is formed on the N-type semiconductor layer 170 by adjusting a semiconductor material according to a target wavelength. This embodiment grows InGaN / GaN, which is possible from green light emission of 390 to 550 nm to UV light emission. In addition, in order to manufacture the UV light emitting device, AlN doped with N-type impurities may be used as the N-type semiconductor layer 170, and AlGaN / AlGaN may be used as the active layer 180. At this time, the manufacturing process of the N-type semiconductor layer 170 is the same as described above, trimethyl aluminum (TMAl), triethyl aluminum (TEAl), trimethylamine aluminum (TMAAl), dimethylethyl as a source gas for the Al It may be formed using amine aluminum (DMEAAl).

A P-type semiconductor layer 190 doped with P-type impurities is formed on the active layer 180. In this embodiment, a GaN layer doped with magnesium (Mg) atoms is formed in the P-type semiconductor layer 190.

Referring to FIG. 3D, a portion of the N-type semiconductor layer 170 is exposed by removing a portion of the P-type semiconductor layer 190 and the active layer 180 through a predetermined etching process, and then a P-type semiconductor layer ( The P-type electrode 200 and the N-type electrode 210 are formed on the 190 and exposed N-type semiconductor layers 170.

To this end, an etch mask pattern is formed on the P-type semiconductor layer 190, and then the N-type semiconductor layer 170 is removed by performing a dry or wet etching process to remove the P-type semiconductor layer 190 and the active layer 180. Expose Thereafter, the etch mask pattern is removed, and the P-type electrode 200 and the N-type electrode 210 are formed on the P-type semiconductor layer 190 and the exposed N-type semiconductor layer 170. In the drawing, the N-type electrode 210 is formed on the upper surface of the third N-type semiconductor layer 160 through an etching process. However, the present invention is not limited thereto, and the third N-type semiconductor layer 160 is etched to form the N-type electrode 210. The N-type electrode 210 may be formed on the upper surfaces of the first or second N-type semiconductor layers 140 and 150.

A transparent electrode layer may be further formed between the P-type semiconductor layer 190 and the P-type electrode 200 to reduce the resistance of the P-type semiconductor layer 190 and improve light transmittance. As the transparent electrode layer, indium tin oxide (ITO), ZnO, or a transparent metal having conductivity may be used. In addition, a separate ohmic metal layer for smoothly supplying current to the P-type semiconductor layer 190 or the exposed N-type semiconductor layer 170 before forming the P-type electrode 200 and the N-type electrode 210. May be further formed. Cr and Au may be used as the ohmic metal layer.

As a result, a light emitting diode including an N-type compound layer and an N-type semiconductor layer having a structure in which an N-type compound layer overdoped with a higher doping level than the N-type compound layer is repeatedly stacked may be manufactured.

The method of manufacturing the light emitting diode of the present invention described above is not limited thereto, and various processes and manufacturing methods may be changed or added according to the characteristics of the device and the convenience of the process.

As described above, the present invention forms an N-type semiconductor layer having a structure in which an N-type compound layer having a predetermined concentration and an N-type compound layer overdoped at a concentration higher than the predetermined concentration are formed, thereby reducing the electrical resistance of the semiconductor material and spreading current. Properties can be improved. Therefore, it is possible to obtain a uniform luminance characteristic, there is an advantage that can improve the luminous efficiency. In addition, the present invention is due to the N-type semiconductor layer including the N-type compound layer and the doped N-type compound layer repeatedly stacked, there is an effect that can prevent damage due to electrostatic discharge.

The present embodiment describes an example applied to the manufacture of a horizontal light emitting diode, but the technical gist of the present invention is not limited to the above-described embodiment, and various modifications and variations are possible, and may be applied to light emitting diodes having various structures. Can be. For example, a buffer layer, an N-type semiconductor layer, an active layer, and a P-type semiconductor layer are formed on the substrate through the above-described process for manufacturing a vertical light emitting diode, and then a conductive host substrate is formed on the P-type semiconductor layer. Bond Next, the lower buffer layer and the base substrate are removed, and the N-type electrode and the P-type electrode are formed on the lower surface of the exposed N-type semiconductor layer and the upper surface of the P-type semiconductor layer. In this manufacturing process, by forming the N-type semiconductor layer including a structure in which the N-type compound layer and the doped N-type compound layer is repeatedly stacked, the effect according to the present invention can of course be obtained.

As mentioned above, although this invention was demonstrated in detail using the preferable Example, the scope of the present invention is not limited to a specific Example and should be interpreted by the attached Claim. In addition, those skilled in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

The present invention forms an N-type semiconductor layer having a structure in which an N-type compound layer having a predetermined concentration and an N-type compound layer overdoped with a concentration higher than the predetermined concentration are formed, thereby improving current spreading characteristics of the light emitting diode to achieve uniform luminance characteristics. Can be secured and the luminous efficiency can be improved. In addition, it is possible to prevent the damage of the light emitting diode due to the electrostatic discharge to improve the reliability, it is expected to improve the life of the light emitting diode.

Claims (10)

Board; An N-type semiconductor layer formed on the substrate; And P-type semiconductor layer formed on the N-type semiconductor layer, The N-type semiconductor layer includes a stacked structure in which an N-type compound layer doped with N-type impurities at a predetermined concentration and an N-type compound layer over-doped with a concentration higher than the predetermined concentration are alternately repeated. The predetermined concentration is greater than 1 × 10 ¹⁹ and less than or equal to 1 × 10 ²² / cm ³ , wherein the overdoped N-type compound layer is doped at a concentration 10 to 100 times higher than the predetermined concentration. The method according to claim 1, Wherein the N-type or P-type semiconductor layer is gallium nitride (GaN), and the N-type impurity is silicon (Si). The method according to claim 1 or 2, The N-type compound layer and the over-doped N-type compound layer is a light emitting diode, characterized in that formed in a laminated structure of 10 to 50 layers. The method according to claim 1 or 2, The N-type semiconductor layer further comprises a first N-type semiconductor layer formed under the laminated structure and a third N-type semiconductor layer formed on the laminated structure. The method according to claim 1 or 2, A light emitting diode further comprising a buffer layer of GaN, InN or AlN between the substrate and the N-type semiconductor layer. Forming an N-type semiconductor layer by alternately growing an N-type compound layer doped with N-type impurities at a predetermined concentration on the substrate and an N-type compound layer over-doped with a concentration higher than the predetermined concentration; And Forming a P-type semiconductor layer on the N-type semiconductor layer, Forming the N-type semiconductor layer, Growing an N-type compound layer doped with N-type impurities to a predetermined concentration by simultaneously using Ga, N, and N-type impurity source gases; And Discontinuing use of the Ga source gas and growing an overdoped N-type compound layer on the N-type compound layer to a concentration higher than the predetermined concentration by using an N, N-type impurity source gas. Method of manufacturing a diode. The method of claim 6, Wherein the N-type or P-type semiconductor layer is gallium nitride (GaN), and the N-type impurity is silicon (Si). delete The method according to claim 6 or 7, The N-type compound layer or the over-doped N-type compound layer is a method of manufacturing a light emitting diode, characterized in that for growing to tens to hundreds of microwatts. The method according to claim 6 or 7, The predetermined concentration is greater than 1 × 10 ¹⁹ and less than 1 × 10 ²² / cm ³ , and the overdoped N-type compound layer is doped at a concentration 10 to 100 times higher than the predetermined concentration. .

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