KR101023135B1 - Lihgt Emitting Diode with double concave-convex pattern on its substrate and manufacturing method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting diode and a method of manufacturing the same, wherein a nano-scale double unevenness is formed on an sapphire substrate to increase the external extraction efficiency of light, thereby increasing the efficiency of semiconductor light emission. An element and a method of manufacturing the same are provided.

More specifically, the present invention provides a sapphire substrate: an n-type semiconductor layer formed on the sapphire substrate; An active layer formed on the n-type semiconductor layer; A p-type semiconductor layer formed on the active layer; A transparent electrode layer formed on the p-type semiconductor layer; A first electrode formed on the transparent electrode layer; And a second electrode formed by etching the transparent electrode layer, the p-type semiconductor layer, and the active layer to form an n-type semiconductor layer, wherein the sapphire substrate is nano-sized patterned to form conical irregularities. It is composed of a semiconductor light-emitting device characterized in that the etching mask material on the upper surface of the concave-convex shape to have a double concave-convex shape.

Semiconductor light emitting device, nano size patterning, double unevenness, horizontal growth method

Description

Semiconductor light emitting device having a substrate having a double concave-convex structure, and a method of manufacturing the same {Lihgt Emitting Diode with double concave-convex pattern on its substrate and manufacturing method}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a semiconductor light emitting diode (LED) for increasing light extraction efficiency and a method of manufacturing the same, and to forming a nano-scale double unevenness on an sapphire substrate. The present invention relates to a structure of a semiconductor light emitting device having high efficiency by increasing external extraction efficiency and a method of manufacturing the same.

Recently, lighting fixtures composed of LEDs (Light Emitting Diodes) have exploded in demand due to advantages such as longer lifespan, relatively low power consumption and no pollutants in the manufacturing process compared to conventional incandescent or fluorescent lamps. Increasingly, LEDs are applied to a variety of applications such as display devices using light emission, as well as backlight devices of lighting devices and LCD displays. In particular, LED has the advantage of low heat generation and long life due to high energy efficiency while being able to drive at a relatively low voltage, and most of the currently used technologies have been developed to provide high brightness of white light, which was difficult to implement in the past. It is expected to replace the light source device.

LEDs are a type of solid state device that converts electrical energy into light and generally include an active layer of semiconductor material sandwiched between two opposing doped layers. When a bias is applied across the two doped layers, holes and electrons are injected into the active layer and then recombined therein to generate light, which is emitted in all directions to be emitted out of the semiconductor chip through all exposed surfaces. do.

In such a conventional LED structure, in particular, a nitride-based LED structure, approaches to maximize the internal quantum efficiency of the active layer and approaches to extract the light generated in the active layer to the outside of the LED chip as much as possible are the main means for increasing the light extraction efficiency.

Two factors can be used to determine the efficiency of light extraction in LED devices: i) first, optical loss due to the degree of transmission in the current diffusion layer, and ii) second, due to total reflection at the interface where light is emitted. Light loss.

i) In relation to the first factor, a current diffusion layer of a conventional LED device is mainly a Ni / Au alloy layer having a thickness of several nm and several tens of nm, and has a thickness of 60-80 for an emission wavelength depending on the thickness and alloy conditions. It has a transmittance of about%. In order to overcome this problem, an approach using an electrode material with high permeability such as ITO has been recently made, but due to the high contact resistance with the p-type GaN layer, it has a difficulty in commercialization, such as np tunnel junction or InGaN / GaN superlattice. The technique which employ | adopts a structure is applied.

ii) Light loss due to total reflection associated with the second factor is the interface at which light is emitted from the top of the LED device to the outside, i.e., p-type GaN and resin or p-type GaN and air or other contact with p-type GaN. The difference in refractive index between adjacent materials occurs at the interface between materials or at the interface between the buffer layer and the sapphire substrate in the lower region of the LED device.

Since the semiconductor constituting the general semiconductor light emitting device has a higher refractive index than the external environment such as a substrate, an epoxy layer or an air layer, the majority of photons generated by the combination of electrons and holes stays inside the device. Branches are affected by the structural shape and the optical properties of the materials constituting the device.

In particular, the refractive index of the material constituting the nitride semiconductor light emitting device is greater than that of the material surrounding the outside of the device (for example, air, resin, or substrate), so that photons generated inside the device do not escape to the outside. There is a problem in that it is absorbed inward and has a low external quantum efficiency.

In order to change the incident angle or the emission angle at the interface in a conventional approach to reduce the light loss due to the total reflection, patterning of regular or irregular irregularities is performed in the p-type GaN layer region by using an etching process. Method and the like.

However, especially in the case of nitride semiconductor optical devices, when the surface is roughened by a dry or wet method due to a relatively thin P-type semiconductor layer, defects may occur in the active layer directly below the P-type semiconductor. This change causes a problem that the contact resistance can be turned on.

Therefore, in the case of nitride semiconductors, the method of roughening the surface after thin film growth has a limitation. Therefore, the method of roughening the surface may be adopted in the thin film deposition process.

It grows evenly from the substrate to the last thin film, and changes the growth conditions such as group V / III ratio, temperature, and deposition rate at the time of the last thin film growth to form high-pitched pit on the surface to increase luminance This is how you increase brightness.

However, this method has a problem that the process of forming a high-density hole is difficult.

Therefore, there is a need for a light emitting device that improves light extraction efficiency by forming irregularities on the surface of a substrate formed of sapphire or the like, and in particular, semiconductor light emission forming a double uneven structure to further increase light extraction efficiency. The device and its manufacturing method are required.

The present invention has been made to solve the above problems of the prior art, by fabricating a semiconductor light emitting device (Light Emitting Diode) using a substrate having a nano-scale microstructure formed by the defect reduction of the device In addition to obtaining reliability, the purpose of the present invention is to provide an effect of improving brightness due to increased scattering of light.

In addition, the present invention is to increase the light scattering effect by forming a double concave-convex structure to leave a mask material having a refractive index different from the substrate material to improve the light extraction efficiency and to use as a growth mask when growing the nitride film The purpose is to provide growth of semiconductor layers such as high quality nitride films by promoting growth.

The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical subjects which are not mentioned can be clearly understood by those skilled in the art from the description of the present invention .

In order to achieve the above object, the present invention provides a sapphire substrate: an n-type semiconductor layer formed on the sapphire substrate; An active layer formed on the n-type semiconductor layer; A p-type semiconductor layer formed on the active layer; A transparent electrode layer formed on the p-type semiconductor layer; A first electrode formed on the transparent electrode layer; And a second electrode formed by etching the transparent electrode layer, the p-type semiconductor layer, and the active layer to form an n-type semiconductor layer, wherein the sapphire substrate is nanoscale patterned to form conical irregularities. It includes a semiconductor light emitting device characterized in that having an etch mask material on the top of the concave-convex concave-convex shape to have a double concave-convex shape.

The present invention includes a sapphire substrate having a nano-sized pattern to form conical irregularities, and having a double uneven shape leaving an etch mask material on top of the conical irregularities.

In the present invention, in order to form a plurality of conical irregularities on the sapphire substrate, a pattern mask having a concave-convex pattern may be used. The pattern mask may use a metal mask such as chromium (Cr), and in some cases, a photo Resist PR can be used.

In the case of using a photoresist as a pattern mask, the uneven pattern may be photo-lithography, e-beam lithography, ion-beam lithography, extreme ultra-violet lithography, or near x-ray. It may be formed using a method such as lithography (Proximity X-ray Lithography) or nano imprint lithography. In addition, this process may use dry etching or wet etching.

In the case of using a chromium (Cr) mask as the pattern mask, in order to form a pattern on chromium, a polymer layer is formed on chromium, and after the pattern is formed using nanoimprinting on the polymer, the chrome mask is etched to form a pattern. A mask can be formed, and nano imprint lithography pre-fabricates a mold required on a surface of a relatively strong material and forms a pattern by painting it on a substrate as if it is painted. After the mold is manufactured, a pattern is formed by applying a polymer material into the mold.

The etching of the chromium mask may be a dry etching method, RIE, ICP-RIE may be used, wherein the gas used may be at least one of Cl₂ and O₂, such dry etching method and wet etching method. Alternatively, one-sided etching is possible and suitable for forming such holes. That is, the wet etching method is an isotropic etching, the etching is performed in all directions, but the dry etching method can be etched only in the depth direction to form a pattern, the desired size and spacing, etc. It can be formed in a pattern.

To sum up the above process, Cr is deposited on the sapphire substrate and PR is deposited thereon, and then patterned into a predetermined shape by using laser interference or E-beam, and the like. After the etching, the chromium is etched using a mixed gas of Cl₂ and O₂, and then the sapphire substrate is etched to the same line width to a predetermined depth by using the patterned Cr as a mask, and the chromium etching solution is used as an etchant. The chromium may be removed, and the etched and patterned sapphire substrate may be cleaned with a surface treating agent to form a concave-convex pattern.

Here, in order to form the double unevenness, the step of etching Cr must be partially etched so that the mask material remains on top of the conical unevenness.

In the present invention, SiO 2 or Si ₃ N ₄ may be used in addition to Cr as an etching mask material, and an etching mask layer made of Si 2 O may be deposited as a SiO 2 thin film using, for example, plasma enhanced chemical vapor deposition (PECVD). Can be. That is, SiH₄, N₂O, and N₂ gas are injected to form a SiO₂ thin film, and then a plasma is ignited under certain conditions to form a Si reactive species and an O reactive species. The two reactive species combine with each other to deposit a Si₂O thin film. In addition, the etching mask layer may be deposited with a silicon oxide (SiO₂) or silicon nitride (Si₃N₄) to a thickness of 100 ~ 2000nm using plasma chemical vapor deposition.

Even when the etching mask is formed by using SiO 2 or Si ₃ N ₄ , the etching mask must be partially etched so that the etching mask material remains on top of the uneven pattern to form a double uneven structure.

In the present invention, the height of the concave-convex irregularities includes a semiconductor light emitting device, characterized in that 0.1um.

In the present invention, the lower width of the concave-convex concave-convex includes a semiconductor light emitting device, characterized in that 0.2um.

In the present invention, the distance between the concave-convex concave-convex on the sapphire substrate includes 0.05um, characterized in that.

In the present invention, a nano-scale micro-convex structure is formed, and the micro-convex structure may affect photons, that is, light generated in the active layer is scattered to the outside by forming various critical angles. It can be said to have a structure that has a minimum size and a high density integration.

The size of the concave-convex pattern is sufficiently determined while taking into consideration the optical aspect while increasing the surface area sufficiently. Preferably, in the present embodiment, the uneven pattern preferably has a lower width of 0.2 μm and a height h of 0.1 μm, and the gap of the uneven pattern preferably has an interval of 0.05 μm to sufficiently increase the surface area. It is not limited to this.

In the present invention, the etching mask material includes a semiconductor light emitting device, characterized in that formed of at least one material selected from Cr, SiO 2 or Si ₃ N ₄ .

The present invention has a double uneven structure on the sapphire substrate, the surface area of the substrate is increased by the conical irregularities formed on the sapphire substrate to increase the light extraction efficiency. In addition, a mask material having a difference in refractive index with a sapphire substrate should be formed on the top of the conical irregularities to increase the refractive and scattering effects of light. Therefore, chromium (Cr), silicon oxide (SiO₂) or When silicon nitride (Si₃N₄) is used as a mask material, light extraction efficiency is improved.

In the present invention, the n-type semiconductor layer, the active layer and the p-type semiconductor layer includes a semiconductor light emitting device, characterized in that the growth by the epitaxial lateral over-growth (Epitaxial Lateral Over Growth) method.

The epitaxial lateral overgrowth method is a technology capable of guaranteeing the formation of a high quality epitaxial layer having a low dislocation density. The epitaxial lateral overgrowth method grows a semiconductor material in parallel to transfer defects formed at an interface between the sapphire substrate and the semiconductor layer to an upper layer. It is a way to suppress that. In the present invention, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer may be grown by epitaxial lateral overgrowth using MOCVD (Metal Organic Chemical Vapor Deposition) or HVPE (Hydride or Hallide Vapor Phas Epitaxy).

In addition, even when the buffer layer is formed, the buffer layer can be grown by using the epitaxial lateral overgrowth method.

In the present invention, the etching mask material remaining on the top of the conical irregularities formed on the sapphire substrate further promotes horizontal growth during the growth of the LED semiconductor layer, so that a semiconductor layer such as a high quality nitride film can be expected.

The epitaxial lateral overgrowth method can reduce the generation of strain due to the lattice constant difference and thermal expansion coefficient difference between the sapphire and the n-type semiconductor layer, in the case of a semiconductor substrate for a light emitting device manufactured by the above method In addition, dislocation defects generated due to lattice constant mismatch between the sapphire substrate and the n-type semiconductor layer can be reduced, thereby improving the crystallinity of the semiconductor substrate. Accordingly, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer may be formed on a semiconductor substrate to manufacture a light emitting device that emits uniform light in general.

The present invention includes an n-type semiconductor layer formed on the sapphire substrate, an active layer formed on the n-type semiconductor layer, a p-type semiconductor layer formed on the active layer and a transparent electrode formed on the p-type semiconductor layer.

The present invention includes a semiconductor light emitting device, further comprising a buffer layer between the sapphire substrate and the n-type semiconductor layer.

In the present invention, a buffer layer, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are sequentially formed on a sapphire substrate on which nano-scale double irregularities are formed, and after the transparent electrode is formed on the p-type semiconductor layer, Partial etching from the transparent electrode to the n-type semiconductor layer exposes the n-type semiconductor layer to the outside, a first electrode is formed on the transparent electrode, and a second electrode is formed on the exposed n-type semiconductor layer.

When the semiconductor light emitting device is completed as described above, when voltage is applied through the first electrode and the second electrode, photons are emitted by recombination of electrons and holes in the active layer. That is, as a voltage is applied to the p-n junction in the forward direction, electrons of the n-type semiconductor layer and holes of the p-type semiconductor layer are injected to the p side and the n side, respectively, so that photons recombined in the active layer are emitted to the outside of the device.

At this time, the photons generated in the active layer and directed toward the substrate collide with the nano-sized duplexes formed on the surface of the substrate and are extracted to the outside while being refracted and scattered. The external emission efficiency of light incident on the substrate is increased.

In the present invention, a gallium nitride (GaN) -based semiconductor may be used as the semiconductor layer. Hereinafter, a method of forming an LED structure using a gallium nitride-based semiconductor will be described in detail.

A gallium nitride (GaN) -based nitride semiconductor light emitting device has a buffer layer formed on a sapphire substrate, an n-type gallium nitride layer (n-GaN) layer, an active layer formed of a multi-quantum well structure to emit light, and a p-type It may comprise a gallium nitride layer (p-GaN) layer and a transparent electrode.

The buffer layer is used to reduce the lattice constant difference between the substrate and the semiconductor layer, and may be selected from an AlInN structure, an InGaN / GaN superlattice structure, an InGaN / GaN stacked structure, and an AlInGaN / InGaN / GaN stacked structure.

An n-type semiconductor layer is formed on the buffer layer. The n-type semiconductor layer may be formed of an n-type gallium nitride layer (n-GaN) layer, and silicon may be doped.

When the n-type gallium nitride layer is grown, an active layer is grown on the n-type gallium nitride layer. The active layer may be a semiconductor layer to which a light emitting material made of indium gallium nitride (InGaN) is added as a light emitting region, and materials such as AlGaN and AlInGaN may also be used as the active layer, wherein the active layer is an InGaN / GaN quantum well. QW) structure, and the active layer may have a plurality of quantum well structures described above in order to improve luminance, thereby forming a multiquantum well (MQW) structure.

After the active layer is formed, a p-type gallium nitride layer is formed on the active layer. The p-type semiconductor layer may be grown to a thickness of several hundred to several thousand micrometers as a p-GaN layer.

The transparent electrode layer is formed on the p-type gallium nitride layer. The transparent electrode layer may be formed of at least one of ITO, ZnO, RuOx, TiOx, and IrOx as a transparent oxide film.

In order to form an electrode pad, a second electrode is formed on the n-type gallium nitride layer, which is partially etched from the transparent electrode layer to the n-type gallium nitride layer, and a first electrode is formed on the transparent electrode layer. In this case, the transparent electrode layer may be partially etched, and the first electrode may be formed on the p-type gallium nitride layer which is etched and opened.

The present invention comprises the steps of: patterning a surface of a sapphire substrate with a biconcave-convex pattern having an etch mask material remaining thereon; Forming an n-type semiconductor layer on the sapphire substrate; Forming an active layer on the n-type semiconductor layer; Forming a p-type semiconductor layer on the active layer; Forming a transparent electrode layer on the p-type semiconductor layer; Forming a first electrode on the transparent electrode layer; Etching predetermined regions of the transparent electrode layer, the active layer, and the p-type semiconductor layer; And etching the transparent electrode layer, the active layer, and the p-type semiconductor layer to form a second electrode in a region where the n-type semiconductor layer is exposed. It includes a method of manufacturing a semiconductor light emitting device comprising a.

The method may further include forming a buffer layer on the sapphire substrate after patterning the surface of the sapphire substrate into a double uneven pattern in which an etch mask material remains. It includes.

In the present invention, the step of patterning the surface of the sapphire substrate with a double concave-convex pattern in which the etching mask material is left, the step of depositing an etching mask on the sapphire substrate; Nanoscale patterning on the sapphire substrate; Etching the etch mask partially so that an etch mask material remains on top of the conical irregularities formed by the nano-size patterning; Etching the sapphire substrate; And a cleaning step.

In the present invention, the forming of the n-type semiconductor layer, the active layer and the p-type semiconductor layer on the sapphire substrate, the semiconductor light emitting device characterized in that the growth by the epitaxial lateral over growth (Epitaxial Lateral Over Growth) method It includes a method.

In the present invention, the n-type semiconductor layer, the active layer and the p-type semiconductor layer includes a method of manufacturing a semiconductor light emitting device, characterized in that deposited by metal organic chemical vapor deposition (MOCVD).

The etching mask in the present invention includes a method for manufacturing a semiconductor light emitting device, characterized in that made of at least one material selected from chromium (Cr), silicon oxide (SiO₂) or silicon nitride (Si₃N₄).

In the present invention, the etching mask etching step includes a method of manufacturing a semiconductor light emitting device, characterized in that the wet etching or dry etching.

According to the present invention, unlike the prior art by fabricating a semiconductor light emitting device using a substrate having a nano-sized concave-convex structure by reducing the defects of the semiconductor light emitting device, increasing the area of the light emitting layer, the light scattering effect is increased This has the effect of improving the brightness.

In addition, according to the present invention, a double uneven structure is formed by leaving a mask material having a refractive index different from that of the substrate material in order to improve light extraction efficiency, thereby using a high quality nitride film due to horizontal growth promotion by using it as a growth mask during growth of a nitride film or the like. Etc. There is an effect of growth of the semiconductor layer.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only one of the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 is a configuration diagram of a semiconductor light emitting device having a substrate having a double uneven structure according to an embodiment of the present invention.

After the nano-sized patterning process is performed on the sapphire substrate to form conical irregularities 120, the sapphire substrate and the etching mask material are partially etched so that the etching mask material remains on the conical irregularities 120 during the etching process. To form a double uneven shape.

A buffer layer 140, an n-type semiconductor layer 150, an active layer 160, and a p-type semiconductor layer 170 are sequentially stacked on the sapphire substrate having the double uneven shape, wherein the metal organic chemical vapor deposition method is used. (MOCVD) can be used. Thereafter, the transparent electrode 180 is formed on the p-type semiconductor layer 170.

In order to form the second electrode 192, the n-type semiconductor layer 150, the active layer 160, the p-type semiconductor layer 170 and the transparent electrode 180 are sequentially stacked on the sapphire substrate, and then the n-type semiconductor layer Predetermined regions of the transparent electrode 180, the p-type semiconductor layer 170, and the active layer 160 are etched to expose 150. In this case, a wet etching method or a dry etching method may be used.

Thereafter, the first electrode 191 is formed on the transparent electrode 180, and predetermined regions of the transparent electrode 180, the p-type semiconductor layer 170, and the active layer 160 are etched and exposed. The second electrode 192 may be formed on the layer.

When the semiconductor light emitting device is completed as described above, when voltage is applied through the first electrode 191 and the second electrode 192, photons are emitted by recombination of electrons and holes in the active layer 160. That is, as the voltage is applied to the pn junction in the forward direction, the electrons of the n-type semiconductor layer 150 and the holes of the p-type semiconductor layer 170 are injected to the p side and the n side, respectively, so that photons recombined in the active layer 160 Emitted out of the device.

At this time, photons generated in the active layer 160 toward the substrate are extracted to the outside while being refracted and scattered while colliding with the nanoscale double unevenness formed on the surface of the substrate, and the flat portion is formed by a nano-sized double uneven pattern on the surface of the sapphire substrate. Since there is almost no such thing, the external emission efficiency of light incident on the substrate is increased.

Figure 2 is an exemplary view showing a substrate of a double uneven structure according to an embodiment of the present invention.

In order to form a double uneven structure on the sapphire substrate, a nanoscale patterning process and a texturing process should be performed.

First, an etching mask material is coated on the sapphire substrate 210, and a pattern of nanoscale may be formed. The pattern may be formed using an E-beam, a scanner, a stepper, laser holography, or the like.

Subsequently, a mask etching step is performed. The etching process is performed to partially etch only the mask material of the portion where the pattern is not formed so that the upper etching mask material 230 having the pattern is formed thereon, and then the sapphire substrate is etched. After the step, the etching mask material 230 remains on the conical concave-convex 220 to form a double concave-convex structure.

3 is an exemplary view showing an SEM image of a double uneven structure substrate according to an embodiment of the present invention.

Referring to this image, it can be seen that the concave-convex structure 320 and the etching mask material 330 on the surface of the sapphire substrate 310 has a double concave-convex structure.

Due to the double uneven structure on the top of the sapphire substrate, the surface area of the substrate is increased to increase the light extraction efficiency. In addition, a mask material having a difference in refractive index with a sapphire substrate should be formed on the upper part of the concave-convex concave and convex to increase the refractive and scattering effects of the light. Therefore, chromium (Cr), silicon oxide (SiO₂) or When silicon nitride (Si₃N₄) is used as a mask material, light extraction efficiency is improved.

4 is a plan view of a substrate on which conical irregularities are formed in accordance with an embodiment of the present invention.

5 is a side view of a substrate on which conical irregularities are formed in accordance with an embodiment of the present invention.

As described above, the lower width 410 of the concave-convex concave and convex concave and convex concave and convex concave and convex concave and convex concave and convex concave and convex concave and convex concave and convex concave and convex concave and convex concave and concave convex concave and convex concave and concave convex concave and convex concave and concave concave and concave convex concave and concave concave and concave concave and concave convex concave and concave concave convex concave and concave Chinese convex concave and concave convex concave and concave Chinese convex concave and concave Chinese convex concave and concave Chinese convex concave and concave Chinese convex concave and concave Chinese

6 is a flowchart illustrating a method of manufacturing a semiconductor light emitting device having a double uneven structure substrate according to an embodiment of the present invention.

First, prior to the manufacturing process of the present invention, the sapphire substrate may be washed, which may be referred to as a process of removing impurities by thermally cleaning the sapphire substrate at a growth temperature of GaN at 1100 to 1200 ° C. .

After the cleaning process, ammonia (NH 3) may be injected into the surface of the sapphire substrate and subjected to nitriding, in order to facilitate the growth of GaN nitride compounds.

When the sapphire cleaning process is performed, the sapphire substrate is patterned into a double uneven pattern. (s610)

Uneven patterns include photo-lithography, e-beam lithography, ion-beam lithography, extreme ultraviolet lithography, and proximity x-ray lithography. ) Or nano imprint lithography.

In the mask etching process, the etching process is performed so that the etching mask material on the upper part of the concave-convex pattern is left. After the etching step of the sapphire substrate, the etching mask material remains on the conical concave-convex part. It is possible to form an uneven structure.

After the nano-sized patterning step, the buffer layer may be selectively formed. The buffer layer may contribute to securing device stability by alleviating the difference in lattice constant between the sapphire substrate and the semiconductor layer. The buffer layer may be selected from an AlInN structure, an InGaN / GaN superlattice structure, an InGaN / GaN stacked structure, and an AlInGaN / InGaN / GaN stacked structure. The buffer layer forming process is performed at a low temperature of about 400 ~ 600 ˚C and is finished by heat-treating the surface at the cladding layer growth temperature for the single crystal growth of the grown GaN layer.

After the formation of the buffer layer, the step of forming an n-type semiconductor layer (s620). The n-type semiconductor layer may be formed of an n-type gallium nitride layer (n-GaN) layer, and may be doped using silicon (Si) as a dopant. It proceeds at high temperature and can combine ammonia (NH₃) as a carrier gas and Ga, N, Si as a compound.

After the n-type semiconductor layer is formed, an active layer is formed (s630), and may be a semiconductor layer to which a light emitting material made of indium gallium nitride (InGaN) is added. In addition, materials such as AlGaN and AlInGaN may also be used as the active layer. In this case, the active layer may form an InGaN / GaN quantum well (QW) structure, and in the active layer, a plurality of quantum well structures may be formed to improve luminance, thereby forming a multi-quantum well (MQW) structure.

After the active layer is formed, a p-type semiconductor layer is formed on the active layer (s640). The p-type semiconductor layer may be formed of a gallium nitride layer (p-GaN layer), and magnesium (Mg) may be used as a dopant. have. This process is also carried out at a high temperature and can combine Ga, N, Mg as a compound with an ammonia (NH₃) carrier gas.

For example, the active layer may supply NH 3, TMGa, and trimethylindium (TMIn) using nitrogen as a carrier gas at a growth temperature of 780 ° C. to grow an active layer made of InGaN / GaN to a thickness of 120 kV to 1200 kV.

A transparent electrode layer is then formed on the p-type semiconductor layer (s650). The transparent electrode layer may be formed of at least one of ITO, ZnO, RuOx, TiOx, and IrOx as a transparent oxide film.

In order to form an electrode pad, a partial etching process is performed from the transparent electrode layer to the n-type semiconductor layer (s660). When the nitride-based semiconductor layer is formed, wet etching is difficult due to the chemical property of the nitride-based compound. It is desirable to.

After the above process, a first electrode is formed on the transparent electrode layer (s670), and a second electrode is formed on the exposed n-type semiconductor layer by partially etching from the transparent electrode layer to the n-type semiconductor layer (s680). At this time, the electrode may be subjected to an oxidation process for forming metallization and protecting the device.

7 is a flowchart illustrating a process of patterning a sapphire substrate according to an embodiment of the present invention with a double uneven pattern.

The present invention can form irregularities using a lithography process, a typical lithography process is as follows.

First, a mask (reticle) is produced. A pattern for forming conical irregularities is drawn on an etch mask material by using an E-beam facility to make a mask (reticle) and deposited on a sapphire substrate.

After that, if necessary, an oxidation process may be added, and a process of developing a thin and uniform silicon oxide film (SiO₂) may be added.

Second, photoresist (PR) is applied. PR, a light-sensitive material, is evenly applied to the wafer surface.

Third, an exposure process is performed. The light is passed through a pattern drawn on the mask using a stepper to take a pattern of irregularities on the wafer on which the PR film is formed.

Fourth, the film of the lighted part on the wafer surface is developed.

Fifth, an etching process is performed to selectively remove unnecessary portions by using chemicals or reactive gases to form uneven patterns. This pattern formation process can be repeated continuously for each pattern layer.

In addition, in the present invention, a photosensitive material such as a photoresist (PR) may be coated and exposed and etched to be patterned into a concave-convex shape. In order to form a fine pattern, DUV (Deep Ultraviolet) or a shorter wavelength may be formed. You can use a stepper that uses Extreme Ultraviolet (EUV) wavelengths or a laser with a shorter wavelength.

Referring to the drawings, the step of depositing an etching mask on the sapphire substrate (s710), the etching mask material in the present invention may be made of any one or more materials selected from Cr, SiO2 or Si₃N₄. The etch mask material forms upper unevenness in the double unevenness pattern, and the light extraction efficiency is improved because the light refraction and scattering effects are large when a material having a difference between the sapphire substrate and the regulation rate is used.

After the deposition of the etching mask, the nano-sized patterning step is performed, (s720)

Conical uneven patterns include photo-lithography, e-beam lithography, ion-beam lithography, extreme ultraviolet lithography, and proximity x-ray lithography. ) Or nano imprint lithography. Using the above method, it is possible to form irregularities of the nano scale (Nano Scale).

In addition, a portion of the sapphire substrate that should not be etched through the mask process is nano-sized, and finally, the surface of the substrate is partially cut or etched from the top down method of nanotechnology with respect to the substrate surface. It is also possible to form nanostructures of concave-convex structures.

Thereafter, the etching mask is etched (s730). At this time, in order to form the double unevenness, the etching of the etch mask material must be partially etched so that the mask material remains on the top of the conical unevenness.

Thereafter, the sapphire substrate is etched (S740). When etching to a predetermined depth and width of the sapphire substrate using an etching solution, convex irregularities of a more perfect shape are generated.

After the cleaning step (s750), the cleaning step may be performed using an organic solvent such as acetone, alcohol or DI water.

The present invention has been described above in connection with specific embodiments of the present invention, but this is only an example and the present invention is not limited thereto. Those skilled in the art can change or modify the described embodiments without departing from the scope of the present invention, and within the equivalent scope of the technical spirit of the present invention and the claims to be described below. Various modifications and variations are possible.

1 is a block diagram of a semiconductor light emitting device having a substrate having a double uneven structure according to an embodiment of the present invention.

Figure 2 is an exemplary view showing a substrate of a double concave-convex structure according to an embodiment of the present invention.

Figure 3 is an exemplary view showing an SEM image of a double uneven structure substrate according to an embodiment of the present invention.

4 is a plan view of a substrate on which conical irregularities are formed in accordance with an embodiment of the present invention.

5 is a side view of a substrate on which conical irregularities are formed according to an embodiment of the present invention.

6 is a flowchart illustrating a method of manufacturing a semiconductor light emitting device having a substrate having a double uneven structure according to an embodiment of the present invention.

7 is a flowchart illustrating a process of patterning a sapphire substrate according to an embodiment of the present invention with a double uneven pattern.

{Description of major symbols in the drawing}

110, 210, 310: Sapphire substrate

120, 220, 320: Conical irregularities

130, 230, 330: etching mask material

140: buffer layer

150: n-type semiconductor layer

160: active layer

170: p-type semiconductor layer

180: transparent electrode

191: first electrode

192: second electrode

410: lower width of the conical irregularities

420: conical irregularities are high

430: distance between concave and convex irregularities

Claims (14)

Sapphire Substrate: An n-type semiconductor layer formed on the sapphire substrate; An active layer formed on the n-type semiconductor layer; A p-type semiconductor layer formed on the active layer; A transparent electrode layer formed on the p-type semiconductor layer; A first electrode formed on the transparent electrode layer; And A second electrode formed by etching the transparent electrode layer, the p-type semiconductor layer, and the active layer to an n-type semiconductor layer; The sapphire substrate is nano-sized patterned to form conical irregularities, the semiconductor light emitting diode (Light Emitting Diode) characterized in that the concave-shaped concave-convex shape leaving a etch mask material on the top of the double concave-convex. The method of claim 1, And a buffer layer between the sapphire substrate and the n-type semiconductor layer. The method of claim 1, The cone-shaped unevenness is a semiconductor light emitting device, characterized in that 0.1um. The method of claim 1, The lower portion of the concave-convex concave-convex semiconductor is 0.2um. The method of claim 1, The distance between the concave-convex irregularities on the sapphire substrate is 0.05um. The method of claim 1, The etching mask material is a semiconductor light emitting device, characterized in that formed of at least one material selected from chromium (Cr), silicon oxide (SiO₂) or silicon nitride (Si₃N₄). The method of claim 1, And said n-type semiconductor layer, active layer and p-type semiconductor layer are grown by epitaxial lateral overgrowth. Patterning the sapphire substrate surface into a biconcave-convex pattern in which an etch mask material remains on top; Forming an n-type semiconductor layer on the sapphire substrate; Forming an active layer on the n-type semiconductor layer; Forming a p-type semiconductor layer on the active layer; Forming a transparent electrode layer on the p-type semiconductor layer; Etching predetermined regions of the transparent electrode layer, the active layer, and the p-type semiconductor layer; Forming a first electrode on the transparent electrode layer; Etching the transparent electrode layer, the active layer, and the p-type semiconductor layer to form a second electrode in a region where the n-type semiconductor layer is exposed; Method for manufacturing a semiconductor light emitting device comprising a. The method of claim 8, after the step of patterning the surface of the sapphire substrate with a double concave-convex pattern with an etch mask material remaining on the top, Forming a buffer layer on the sapphire substrate; Method for manufacturing a semiconductor light emitting device, characterized in that it further comprises. The method of claim 8, wherein the patterning of the sapphire substrate surface with a double uneven pattern having an etch mask material remaining thereon is performed. Depositing an etching mask on the sapphire substrate; Nanoscale patterning on the sapphire substrate; Etching the etch mask partially so that an etch mask material remains on top of the conical irregularities formed by the nano-size patterning; Etching the sapphire substrate; And A cleaning step; Method of manufacturing a semiconductor light emitting device comprising a. The method of claim 8, wherein the forming of the n-type semiconductor layer, the active layer and the p-type semiconductor layer on the sapphire substrate, A method of manufacturing a semiconductor light emitting device, characterized by growing by epitaxial lateral overgrowth. The method of claim 8, And the n-type semiconductor layer, the active layer and the p-type semiconductor layer are deposited by metal organic chemical vapor deposition (MOCVD). The method of claim 10, The etching mask is a method of manufacturing a semiconductor light emitting device, characterized in that made of at least one material selected from chromium (Cr), silicon oxide (SiO₂) or silicon nitride (Si₃N₄). The method of claim 10, The etching mask etching step is a method of manufacturing a semiconductor light emitting device, characterized in that consisting of wet etching (Wet etching) or dry etching (dry etching).

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