KR101136521B1 - Light emitting diode and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A light emitting diode and manufacturing method thereof are provided to form an uneven structure on an upper semiconductor layer to reduce the total reflection in a light emitting diode, thereby increasing the light emitting efficiency of the light emitting diode. CONSTITUTION: A first conductive lower semiconductor layer(120), an active layer(130), and a second conductive upper semiconductor layer(140) are formed on a substrate(110). A porous alumina layer(210) including a hole is formed on the upper semiconductor layer. Parts of the upper semiconductor layer, the active layer, and the lower semiconductor layer are etched to form an etching unit(260). The etching process is performed using an alumina layer as a mask.

Description

LIGHT EMITTING DIODE AND MANUFACTURING METHOD THEREOF

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to semiconductor light emitting devices, and more particularly, to high efficiency and high brightness semiconductor light emitting diodes and a method of manufacturing the same.

A light-emitting diode (LED) is a semiconductor device that emits light when a voltage is applied, and has a feature of obtaining desired light energy with relatively low power consumption, and is used in various electronic fields such as lighting devices and display devices. The amount of light energy obtained through the light emitting diode is determined by the luminous efficiency and luminance characteristics of the light emitting diode. In order for a light emitting diode to have improved characteristics (ie, high efficiency and high brightness), the external quantum efficiency of the light emitting diode must be high. Since the external quantum efficiency is determined by the product of the internal quantum efficiency and the light extraction efficiency, the internal quantum efficiency and the light extraction efficiency must be increased to improve the characteristics of the light emitting diode.

As a method for increasing the internal quantum efficiency of a light emitting diode, a technique using a quantum fountain structure rather than a general bulk structure is known. However, there is a difficulty in manufacturing a light emitting diode having a good quantum dot.

On the other hand, to improve the light extraction efficiency of the light emitting diode, a technique for making the device structure in the form of pyramid or inverted pyramid, a surface roughening technique (surface roughening), a pattern forming irregularities on the substrate (patterned sapphire substrate) : PSS) and the like are known. The technique of making the device structure in the form of pyramids or inverted pyramids increases the light extraction efficiency by reducing the incident angle of light, reducing the amount of light in which total internal reflection occurs and increasing the amount of light having an incident angle within the critical angle. However, as the area of the device becomes larger, the increase in light extraction efficiency is slower, and therefore, it is effectively used only when the size of the device is small. As a technique for forming irregularities on the surface, a method of lowering the temperature during thin film growth, or forming a pattern on the surface through optical lithography or holographic lithography and forming irregularities on the surface of the device through etching is used. However, when the temperature is lowered, there is a problem that the thin film grown at a low temperature is not preferable, and there is a problem in that the size of the unevenness that can be reduced in the case of optical lithography, and the area in which the unevenness is formed in the holographic lithography There is a problem that is difficult to enlarge. Lastly, the technique of forming irregularities on the substrate improves light extraction efficiency by changing the angle of reflection of light reflected between the substrate and the thin film by forming a hemispherical surface in the form of a lens on the substrate through optical lithography and etching. will be. However, this method has a problem that it is difficult to grow a high quality thin film in the process of preparing a substrate and growing a thin film.

The present invention is to provide a method of manufacturing a light emitting diode having high efficiency and high brightness.

According to one aspect of the invention, there is provided a light emitting diode manufacturing method comprising the steps of: preparing a substrate; Stacking a plurality of layers including a lower semiconductor layer of a first conductivity type, an active layer, and an upper semiconductor layer of a second conductivity type on the substrate; Forming a nanometer-sized structure on the upper semiconductor layer; And etching at least a portion of the stacked plurality of layers by using the nanometer-sized structure as a mask.

According to an embodiment of the present invention, the forming of the nanometer-sized structure on the upper semiconductor layer may include depositing an aluminum layer on the upper semiconductor layer; And applying an anodizing process to the aluminum layer to form a porous alumina layer having a nanometer sized hole.

Additionally, forming a nanometer-sized structure over the upper semiconductor layer comprises depositing a metal into the nanometer-sized holes in the porous alumina layer and removing the porous alumina layer to nanometer over the upper semiconductor layer. The method may further include forming a metal disk of the size.

According to another embodiment of the present invention, etching at least a portion of the stacked plurality of layers by using the nanometer-sized structure as a mask may include etching a portion of the upper semiconductor layer. have.

According to an exemplary embodiment of the present disclosure, etching the portion of the stacked plurality of layers by using the nanometer-sized structure as a mask may include forming a portion of the upper semiconductor layer, the active layer, and the lower semiconductor layer. Etching may be included.

The method of manufacturing a light emitting diode according to the present invention may further include removing the mask.

According to another aspect of the invention, a plurality of layers comprising a substrate and a plurality of layers comprising a lower semiconductor layer of a first conductivity type, an active layer and an upper semiconductor layer of a second conductivity type stacked on the substrate, At least a portion of the layer of is provided with a light emitting diode comprising a portion etched into the structure of the nanometer size.

According to embodiments of the present invention, a light emitting diode having high efficiency and high brightness may be provided.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, when it is determined that there is a risk of unnecessarily obscuring the gist of the present invention, a detailed description of already known functions and configurations will be omitted. In addition, it should be understood that the following description relates to one embodiment of the present invention, but the present invention is not limited thereto.

1A-1E illustrate a process of manufacturing a light emitting diode 100 according to an exemplary embodiment of the present invention. Referring to FIG. 1A, the lower semiconductor layer 120, the active layer 130, and the upper semiconductor layer 140 are sequentially stacked on the substrate 110. In an embodiment, the substrate 110 may be a silicon substrate having GaN, SiC formed on a surface thereof, a single crystal SiC substrate, a sapphire substrate, a GaN substrate, or the like. The active layer 130 is an area in which carriers, which are electrons and holes, are recombined and include InGaN, AlGaN, GaN, AlInGaN, and the like. The active layer 130 may be a multilayer film in which quantum well layers and barrier layers are repeatedly formed. The barrier layer and the well layer may be a Group III or Group V compound semiconductor layer, which is represented by the formula _{In x Al y Ga 1 -x- y} N (0≤x, 0≤y, x + y≤1). The barrier layer and the well layer may be formed by doping silicon (Si) or magnesium (Mg). The emission wavelength of light emitted from the light emitting diode device is determined according to the type of material constituting the quantum well layer of the active layer 130.

The lower semiconductor layer 120 and the upper semiconductor layer 140 have opposite conductivity types. When the lower semiconductor layer 120 is n-type, the upper semiconductor layer 140 is p-type, and when the lower semiconductor layer 120 is p-type, the upper semiconductor layer 140 is n-type. In one embodiment, the n-type semiconductor layer comprises a nitride based semiconductor (Group III-V semiconductor), and the N-type In _x Al _y Ga _{1 -x- y} N (0 ≦ x, 0 ≦ y, x + y ≦ 1). The p-type semiconductor layer includes a nitride based semiconductor (Group III-V semiconductor), and the p-type In _x Al _y Ga _{1- x- y} N (0 ≦ x, 0 ≦ y, x + y ≦ 1).

Subsequently, referring to FIG. 1B, an aluminum layer 200 is deposited over the upper semiconductor layer 140. Known deposition methods, including thermal evaporation, e-beam evaporation, sputtering, and the like, can be used to deposit the aluminum layer 200. Anodization is performed on the deposited aluminum layer 200. The anodic oxidation process is a technique of electrochemically oxidizing a metal (eg, aluminum) to a metal oxide (eg, alumina), through which nanometer-sized nanostructures can be formed. In one embodiment, the aluminum layer 200 is deposited in an acidic solution during the anodic oxidation process. Acidic solutions include phosphoric acid, oxalic acid, sulfuric acid solutions, and the like. The aluminum layer 200 deposited in the acidic solution forms a hole from the surface toward the upper semiconductor layer 140 as it is oxidized by an electrochemical reaction. In one embodiment, the anodic oxidation process may be repeated several times.

1C illustrates a cross-sectional view of a light emitting diode 100 after an anodization process is performed in accordance with one embodiment of the present invention. As illustrated, an alumina layer (Al ₂ O ₃ ) 210 and a hole 220 are formed in the light emitting diode 100. In one embodiment, the hole 220 may have a diameter of several hundreds of nanometers. In one embodiment, the diameter of the hole 220 may be 500 nm or less. The size of the hole 220 may vary depending on the voltage applied during the anodic oxidation process, the type of acidic solution used, and the application time. For example, the longer the time for which the aluminum layer 200 is immersed in the acidic solution, the larger the size of the hole 220 will be.

1D is a cross-sectional view of a light emitting diode 100 obtained after performing an etching process on a portion of an upper semiconductor layer in accordance with an embodiment of the present invention. The etching process is performed by etching the surface of the upper semiconductor layer 140 to a predetermined depth by using the alumina layer 210 having the holes 220 as a shadow mask. According to one embodiment, dry etching or wet etching may be performed. As the etching process proceeds, a hole 230 having a size corresponding to that of the hole 220 is formed in the upper semiconductor layer 140. As shown in FIG. 1E, the alumina layer 210 may be selectively removed to reduce electrical contact resistance. Thus, in the light emitting diode 100 manufactured according to the present embodiment, the upper semiconductor layer 140 has an uneven structure. The uneven structure reduces the total reflection inside the light emitting diode so that the light reaching the surface from the active layer can effectively escape to the outside, thereby improving the luminous efficiency and luminance characteristics of the light emitting diode.

2A and 2D are views for explaining a process of manufacturing the light emitting diodes 200 according to another embodiment of the present invention.

Referring to FIG. 2A, a porous alumina layer in which a substrate 110, a lower semiconductor layer 120, an active layer 130, and an upper semiconductor layer 140 are stacked and a hole 220 is formed on the upper semiconductor layer 140 ( 210 is ready. In FIG. 2B, the metal disk 240 is formed on the upper semiconductor layer 140 by filling a metal material into the hole 220 formed in the alumina layer 210. The metal disk 240 has a size corresponding to the hole 220, and in one embodiment, the diameter of the metal disk 240 may be several to several hundred nanometers. In order to fill the hole 220 with a metal material, a known deposition method such as chemical vapor deposition (CVD), evaporation, and sputtering may be used. In one embodiment, the metal material includes Al, Cu, Mg, and the like, and is not etched during the etching process. In FIG. 2C, an etching process is performed using the metal disk 240 as a mask. A portion of the upper semiconductor layer 140 is etched through the etching process, and a protrusion 250 having a size corresponding to the metal mask 240 is formed in the upper semiconductor layer 140. Thereafter, referring to FIG. 2D, the metal disk 240 is removed to increase light emission efficiency. As such, the upper semiconductor layer 140 also has a concave-convex structure in the light emitting diode 200 manufactured according to the present embodiment. Therefore, the characteristics of the light emitting diode are improved according to the uneven structure of the upper semiconductor layer 140.

3A and 3B are diagrams for describing a process of manufacturing the light emitting diode 300 according to another embodiment of the present invention.

Referring to FIG. 3A, a porous alumina layer in which a substrate 110, a lower semiconductor layer 120, an active layer 130, and an upper semiconductor layer 140 are stacked and a hole 220 is formed on the upper semiconductor layer 140 is provided. 210 is prepared. As shown in FIG. 3B, a portion of each of the upper semiconductor layer 140, the active layer 130, and the lower semiconductor layer 120 is etched to form an etched portion 260. The etching process is performed using the alumina layer 210 as a mask. In one embodiment, the etch 260 has a size of several to several hundred nanometers. Although not shown, the etching unit 260 may be filled with an insulating material including SiO ₂ , SiC, SiN, and the like.

The active layer 130 remaining in the light emitting diode 300 manufactured according to the present embodiment is surrounded by a hole 260 having a nanometer size, and in this case, the energy structure of the active layer 130 is a quantum fountain due to the quantum effect. It has the characteristics of quantum dots. Therefore, the internal quantum efficiency of the light emitting diode 300 is increased. In addition, since the remaining lower semiconductor layer 120, the active layer 130, and the upper semiconductor layer 140 form a predetermined pattern at intervals of several hundreds of nanometers, charges passing therethrough transmit a collision without collision due to a restraining effect. Ballistic transport. Therefore, it is possible to bring about effects such as heat generation reduction and power consumption reduction. In addition, since the wavelength of the light emitted from the active layer 130 is larger than the diameter of the etched portion 260 surrounding the active layer 130, light is not easily constrained and rather easy to emit, thereby improving luminous efficiency. . That is, the light emitting diode 300 manufactured according to the present embodiment has the effect of light due to the quantum confinement effect of the charge, the ballistic transfer effect of the charge by the formation of the nanometer-sized pattern, the disturbance effect of the light by the nanometer-sized structure, etc. Emission efficiency is improved.

4A and 4D are views for explaining a process of manufacturing the light emitting diode 400 according to another embodiment of the present invention.

Referring to FIG. 4A, a porous alumina layer in which a substrate 110, a lower semiconductor layer 120, an active layer 130, and an upper semiconductor layer 140 are stacked and a hole 220 is formed on the upper semiconductor layer 140 is illustrated. 210 is prepared. Subsequently, as shown in FIG. 4B, a metal material is filled in the hole 220 formed in the alumina layer 210 to form the metal disk 240. The metal disk forming method and the materials constituting the metal disk have already been described. In FIG. 4C, the alumina layer 210 is removed. Subsequently, in FIG. 4D, a portion of each of the upper semiconductor layer 140, the active layer 130, and the lower semiconductor layer 120 is etched using the metal disk 240 as a mask to form the pillar part 270. In one embodiment pillar portion 270 has a size of several to several hundred nanometers.

In the present embodiment, since the remaining active layer 130 forms a nanometer-sized pillar portion 270, the energy structure of the active layer 130 has the characteristics of quantum dots due to the quantum effect. In addition, since the remaining lower semiconductor layer 120, the active layer 130, and the upper semiconductor layer 140 form nanometer-sized patterns, effects such as heat generation and power consumption may be reduced. In addition, since the wavelength of the light emitted from the active layer 130 is larger than the diameter of the pillar portion 270, the light is not easily constrained and the emission is easy, so that the luminous efficiency may be improved.

Although various functions and features of the present invention have been described in various embodiments, it is not intended to limit the present invention. Rather, one skilled in the art will understand that various modifications, reconfigurations and substitutions can be made without departing from the spirit and scope of the invention. Accordingly, all modifications and changes that fall within the spirit and scope of the present invention are intended to be covered by the following claims.

1A-1E illustrate a process of manufacturing a light emitting diode according to an embodiment of the present invention.

2A-2D illustrate a process of manufacturing a light emitting diode according to another embodiment of the present invention.

3A and 3B are views for explaining a process of manufacturing a light emitting diode according to another embodiment of the present invention.

4A-4D illustrate a process of manufacturing a light emitting diode according to another embodiment of the present invention.

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

110: substrate

120: lower semiconductor layer

130: active layer

140: upper semiconductor layer

200: aluminum layer

210: alumina layer

220: hall

230: hall

240: metal disk

250: protrusion

260: etching portion

270: pillar

Claims (11)

As a light emitting diode manufacturing method, Preparing a substrate; Stacking a plurality of layers including a lower semiconductor layer of a first conductivity type, an active layer, and an upper semiconductor layer of a second conductivity type on the substrate; Depositing an aluminum layer over the upper semiconductor layer; Applying an anodization process to the aluminum layer to form a porous alumina layer having holes of nanometer size; And Using the porous alumina layer as a mask, etching a portion of the upper semiconductor layer to form an etched portion. As a light emitting diode manufacturing method, Preparing a substrate; Stacking a plurality of layers including a lower semiconductor layer of a first conductivity type, an active layer, and an upper semiconductor layer of a second conductivity type on the substrate; Depositing an aluminum layer over the upper semiconductor layer; Applying an anodization process to the aluminum layer to form a porous alumina layer having holes of nanometer size; And And etching a portion of the upper semiconductor layer, the active layer, and the lower semiconductor layer by using the porous alumina layer as a mask to form an etched portion. 3. The method of claim 2, The method of manufacturing a light emitting diode further comprising the step of filling the etching material with an insulating material. As a light emitting diode manufacturing method, Preparing a substrate; Stacking a plurality of layers including a lower semiconductor layer of a first conductivity type, an active layer, and an upper semiconductor layer of a second conductivity type on the substrate; Depositing an aluminum layer over the upper semiconductor layer; Applying an anodization process to the aluminum layer to form a porous alumina layer having holes of nanometer size; Depositing a metal in the nanometer sized hole formed in the porous alumina layer; Removing the porous alumina layer to form a nanometer sized metal disk on the upper semiconductor layer; And Using the nanometer-sized metal disk as a mask to etch a portion of the upper semiconductor layer to form an etched portion. As a light emitting diode manufacturing method, Preparing a substrate; Stacking a plurality of layers including a lower semiconductor layer of a first conductivity type, an active layer, and an upper semiconductor layer of a second conductivity type on the substrate; Depositing an aluminum layer over the upper semiconductor layer; Applying an anodization process to the aluminum layer to form a porous alumina layer having holes of nanometer size; Depositing a metal in the nanometer sized hole formed in the porous alumina layer; Removing the porous alumina layer to form a nanometer sized metal disk on the upper semiconductor layer; And And etching a portion of the upper semiconductor layer, the active layer, and the lower semiconductor layer using the nanometer-sized metal disk as a mask to form an etched portion. The method of claim 5, The method of manufacturing a light emitting diode further comprising the step of filling the etching material with an insulating material. delete delete delete delete delete

Images