KR101097878B1

KR101097878B1 - Method for manufacturing gan-based semiconductor light emitting diode

Info

Publication number: KR101097878B1
Application number: KR1020090011231A
Authority: KR
Inventors: 홍창희; 강지혜; 김형구
Original assignee: 전북대학교산학협력단
Priority date: 2009-02-11
Filing date: 2009-02-11
Publication date: 2011-12-23
Also published as: KR20100091856A

Abstract

The present invention provides a method of manufacturing a nitride-based semiconductor light emitting device that can improve the light extraction efficiency of the nitride-based light emitting diode (GaN-based semiconductor light emitting diode), through the wet etching of the polycrystalline oxide film on the surface of the nitride-based light emitting diode Nanoscale spheres are formed and surface patterning using them improves the light extraction efficiency of the light emitting device. In addition, the nano-scale sphere may be used as a dry etching mask for forming protrusions on the surface of the nitride-based semiconductor layer, and the pattern may be formed on the transparent electrode layer using a nano-scale sphere using the same polycrystalline oxide film as the transparent electrode layer. This is possible. In this case, a pattern can be formed through selective deposition using a photoresist as a mask on the surface of the nitride-based semiconductor layer of the polycrystalline oxide film, and nanoscale spheres are formed on or below the transparent electrode layer to form different patterns. The pattern of the transparent electrode layer can be formed. In addition, it is possible to easily form a uniform nanoscale sphere by removing the concentration of the acid solution.

Description

Manufacturing method of nitride-based semiconductor light emitting device {METHOD FOR MANUFACTURING GAN-BASED SEMICONDUCTOR LIGHT EMITTING DIODE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fabricating a nitride semiconductor device, wherein the surface of an electrode is formed by forming a nanoscale ITO sphere through wet etching, and using it as an etching mask for forming a nanoscale pattern on the surface of the nitride semiconductor device. The present invention relates to a method of manufacturing a nitride-based semiconductor light emitting device having excellent external luminous efficiency by allowing nanoscale patterns to be scattered at the interface of an nitride semiconductor or an electrode.

The nitride-based light emitting device can control the wavelength according to the type and constituent material of the semiconductor material used, such as gallium nitride (GaN), aluminum nitride (AlN) and indium nitride (InN). Such a light emitting device has a long life, low power consumption, high response speed and impact resistance, small size, and light weight, compared to other light emitting devices. For example, high-brightness LEDs are currently widely used in industrial fields such as keypads for mobile communication terminals, light sources for LCD backlights, automobiles, message signs, and traffic indicators.

Conventional nitride-based semiconductor light emitting devices have a critical angle of light extraction at 23 ° at the interface with air due to a large refractive index of 2.5, so that the amount of light trapped in the nitride-based semiconductor devices due to total internal reflection of the chip increases the light toward the air. The amount of this released is extremely small.

FIG. 1A is a diagram illustrating an incident angle of light emitted to the outside from a nitride based semiconductor.

Referring to FIG. 1A, the light extraction efficiency of the nitride-based semiconductor device is very low, about 5 to 10%, due to loss in the device due to a small critical angle at the interface between the nitride-based semiconductor and air. However, by forming a pattern on the surface of the nitride-based semiconductor and the surface of the electrode as shown in FIG. 1B, the amount of light emitted from the nitride-based semiconductor to the air or the amount of light emitted from the p-type ohmic electrode to the air is increased. The light extraction efficiency of the device can be improved.

As a conventional technique, there is a 'III-nitride-based semiconductor light emitting device' of Patent No. 10-0568830 relating to a nitride-based semiconductor device in which a metal particle lump using a metal thin film is formed to form a pattern on a surface of a nitride-based semiconductor.

The prior art is a technique for increasing the external quantum efficiency of the light emitting device by forming a projection on the surface exposed by the etching including the region for cutting the n-layer light emitting device to change the metal oxide film of 20 ~ 100Å by granulation through heat treatment Was used as an etching mask. At this time, there is a problem that the uniformity of the grains is poor and the size of the grains is not easy to control, and that the granules need high temperature to form grains and are difficult to remove.

In addition, Patent No. 10-0650996, "Nitride-based semiconductor light-emitting diode comprising a surface portion formed with a fine projection and a method of manufacturing thereof '' is a fine projection on the upper surface of the nitride-based semiconductor layer in contact with the outside without forming an ohmic electrode The present invention relates to a nitride-based semiconductor device having increased light extraction efficiency by forming a fine irregularity through wet etching in a polycrystalline oxide film and using the same as an etching pattern. In this case, since the fine irregularities formed on the polycrystalline oxide film are not uniform, the pattern formed on the nitride-based semiconductor surface is also not uniform.

In addition, a conventional method for a nitride semiconductor device in which a pattern is formed on a surface of a conventional ohmic electrode is a method of manufacturing a nitride-based light emitting device of Patent 10-0755591. The wet etching process of the ITO layer, which is an ohmic electrode layer of the nitride semiconductor light emitting device, with an acid solution having a pH of 6 to 6.5 to form a plurality of protrusions having a diameter of 250 to 1000 nm on the surface to improve external light emitting efficiency. to be. However, this has a problem that the size of the protrusion formed during etching is not uniform.

The prior arts have a problem in that the size of the grains and the unevenness is not easy to control due to the non-uniform structure of the pattern formed by heat treatment or etching, and the application is limited.

An object of the present invention is to use a uniform nanoscale sphere formed through the wet etching of the polycrystalline oxide film as an etching mask for forming a pattern on the surface of the nitride-based semiconductor, or to pattern the transparent electrode layer (or ohmic electrode layer) The light emitting amount is increased by scattering at the interface between the nitride semiconductor and the air or at the interface between the transparent electrode layer and the air, thereby providing a method of manufacturing a nitride semiconductor light emitting device having excellent light extraction efficiency.

The present invention provides a method for manufacturing a nitride-based semiconductor light emitting device as follows to solve the above problems.

The method of manufacturing the nitride semiconductor light emitting device includes a step of exposing an n-type layer of the nitride semiconductor by growing a plurality of nitride semiconductors on a substrate;

Depositing a polycrystalline oxide film on the entire surface of the nitride semiconductor and forming a nanoscale sphere through wet etching using an acidic solution;

C) dry etching the nitride semiconductor using the nanoscale sphere as an etching pattern;

Forming a transparent electrode layer on the nanoscale sphere formed on the nitride semiconductor;

As the unevenness of the pattern of the surface of the nitride-based semiconductor formed in step c and the unevenness according to the diameter of the nanoscale sphere overlap, the formation of the pattern on the transparent electrode layer is completed as the formation of the transparent electrode layer in step d proceeds. step; And

And forming an n-type electrode pad 50 and a p-type electrode pad 60 in the nitride semiconductor.

Here, it is preferable that the structure having a broad wavelength according to the composition of the nitride-based semiconductor, including an n-type nitride-based semiconductor layer, an active layer, a p-type nitride-based semiconductor layer.

In addition, the polycrystalline oxide film 40 for forming the nano-scale sphere is SnO_x, In_xO_y,Al_xO_y, ZnO, ZrO_x, HfO_x, TiO_x, Ta_xO_y, Ga_xIt is preferable that it is an oxide film which consists of one or two or more, such as O.

In addition, the etching of the oxide film is performed by wet etching, the acid solution is hydrochloric acid (HCl), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), oxalic acid (oxalic acid), sulfuric acid (H ₂ SO ₄ ), It is preferable to include one or more such as hydrofluoric acid (HF).

In addition, it is preferable that the acidity (pH) of the acidic solution may be 0.1 to 1.

In addition, the oxide film may form a nanoscale sphere by active etching at a grain boundary having a weak bonding force and an interface having a weak bonding force between the oxide film and the nitride semiconductor in a polycrystalline state that has not undergone heat treatment.

In addition, the thickness of the polycrystalline oxide film may be 50nm to 600nm, it is preferable to adjust the average size of the nano-scale spheres generated by adjusting the thickness of the oxide film.

In addition, it is preferable to use a nano-scale sphere through wet etching of the oxide film as a mask for dry etching for forming protrusions on the surface of the nitride semiconductor.

In addition, it is preferable to include a heat treatment for hardening a nano-scale sphere used as a mask for dry etching for forming protrusions on the surface of the nitride-based semiconductor.

In addition, the nano-scale sphere through wet etching of the oxide film is preferably formed on the upper or lower portion of the transparent electrode layer to form a pattern of the transparent electrode layer of the nitride-based semiconductor.

In addition, the nanoscale sphere for forming the pattern of the transparent electrode layer preferably comprises changing the shape of the sphere through ICP treatment.

The present invention regarding a method for manufacturing a nitride-based semiconductor light emitting device can be embodied as follows.

The method of manufacturing the nitride semiconductor light emitting device may include forming a plurality of nitride semiconductor layers on a substrate;

Forming a polycrystalline oxide film on an upper surface of the stacked nitride based semiconductors;

And applying a wet etching process using an acidic solution to the polycrystalline oxide layer to form nanoscale spheres.

In the method of manufacturing the nitride semiconductor light emitting device, the method may further include dry etching the upper surface of the nitride semiconductor using the nanoscale sphere as an etching pattern.

In the method of manufacturing the nitride semiconductor light emitting device, the method may further include removing the nanoscale spheres formed on the upper surface of the nitride semiconductor.

In addition, in the method of manufacturing the nitride-based semiconductor light emitting device, it is preferable to further include forming a transparent electrode layer.

In addition, the method of manufacturing the nitride-based semiconductor light emitting device, further comprising the step of forming a transparent electrode layer, it is preferable that the pattern of the transparent electrode layer is formed simultaneously by transferring the pattern of the nanoscale sphere.

In the method of manufacturing the nitride-based semiconductor light emitting device, the method may further include forming a transparent electrode layer, wherein the lower pattern of the transparent electrode layer is transferred to simultaneously form a pattern of the transparent electrode layer.

In addition, in the method of manufacturing the nitride-based semiconductor light emitting device, it is preferable to further include forming an electrode pad.

In addition, in the method of manufacturing the nitride semiconductor light emitting device, it is preferable to form a plurality of nitride semiconductor layers on the substrate to expose a portion of the n-type layer by mesa etching.

In the method of manufacturing the nitride semiconductor light emitting device, the method may further include dry etching the upper surface of the nitride based semiconductor, the slope of the mesa etched surface, and a part of the exposed n-type layer by using the nanoscale sphere as an etching pattern. It is preferable to include.

In the method of manufacturing the nitride semiconductor light emitting device, it is preferable to further include forming a transparent electrode layer on an upper surface of the nitride semiconductor.

In the method of manufacturing the nitride semiconductor light emitting device, the method may further include forming an n-type electrode pad and a p-type electrode pad on the transparent electrode layer forming surface on a part of the exposed n-type layer of the nitride-based semiconductor. Do.

Further, in the method of manufacturing the nitride semiconductor light emitting device, the nitride semiconductor layer is a structure having a wide range of wavelengths according to each composition, and includes an n-type nitride-based semiconductor layer, an active layer, and a p-type nitride semiconductor layer. It is preferable to include.

In the method of manufacturing the nitride-based semiconductor light emitting device, the polycrystalline oxide film 40 for forming the nanoscale sphere is SnO _x , In _x O _y _, Al _x O _y , ZnO, ZrO _x , HfO _x , It is preferable to consist of one or two or more of TiO _x , Ta _x O _y , Ga _x O and the like.

In the method of manufacturing the nitride semiconductor light emitting device, the polycrystalline oxide is etched by wet etching, and the acidic solution is hydrochloric acid (HCl), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), oxalic acid. It is preferable to include at least one of (oxalic acid), sulfuric acid (H ₂ SO ₄ ), hydrofluoric acid (HF).

In addition, in the method of manufacturing the nitride semiconductor light emitting device, the acidity (pH) of the acidic solution is preferably 0.1 to 1.

In addition, in the method of manufacturing the nitride semiconductor light emitting device, the polycrystalline oxide film is active at a grain boundary where the bonding strength is weak in an uncrystallized polycrystalline state and at an interface where the bonding strength between the polycrystalline oxide film and the nitride semiconductor is weak. It is desirable to form nanoscale spheres by etching.

In addition, in the method of manufacturing the nitride-based semiconductor light emitting device, when the thickness of the polycrystalline oxide film is 50nm to 600nm, it is preferable to control the average size of the nano-scale spheres generated by adjusting the thickness of the polycrystalline oxide film.

In the method of manufacturing the nitride semiconductor light emitting device, it is preferable to use a nano-scale sphere through wet etching of the polycrystalline oxide film as a dry etching mask for forming protrusions on the surface of the nitride semiconductor.

In addition, in the method of manufacturing the nitride semiconductor light emitting device, it is preferable to include a heat treatment for hardening a nano-scale sphere used as a dry etching mask for forming protrusions on the surface of the nitride semiconductor.

In the method of manufacturing the nitride semiconductor light emitting device, a nano-scale sphere is formed on the upper or lower portion of the transparent electrode layer to form a pattern of the transparent electrode layer of the nitride semiconductor by wet etching the polycrystalline oxide film. It is preferable.

In addition, in the method for manufacturing the nitride-based semiconductor light emitting device, it is preferable that the nanoscale sphere for forming the pattern of the transparent electrode layer comprises changing the shape of the sphere through the ICP treatment.

In the method of manufacturing the nitride semiconductor light emitting device, the material of the polycrystalline oxide film and the transparent electrode layer is preferably the same.

As described above, in the method of manufacturing the nitride-based semiconductor light emitting device of the present invention, the polycrystalline oxide film is manufactured into nano-scale spheres by wet etching, and used as an etching mask to form pattern of the surface of the nitride-based semiconductor and Spheres can be formed on the upper or lower portion of the transparent electrode layer to form patterns on the surface of the electrode, so that light extraction efficiency can be improved by scattering from the nitride-based semiconductor surface and the electrode surface generated in the nitride-based light emitting device. . At this time, the nano-scale sphere using the polycrystalline oxide film has an effect that can be easily formed and easily removed by adjusting the acidity of the acid solution.

Hereinafter, a method of manufacturing the nitride-based semiconductor light emitting device of the present invention will be described with reference to the accompanying drawings.

1A and 1B are diagrams exemplarily illustrating an incident angle of light appearing on the surface of a nitride semiconductor light emitting device when a pattern is formed on the surface of the nitride semiconductor according to the present invention. 2A to 2D are diagrams sequentially illustrating a manufacturing method using a nanoscale sphere formed by wet etching a polycrystalline oxide film according to the present invention as a dry etching mask for forming a pattern on a surface of a nitride semiconductor. 3A to 3D are diagrams sequentially illustrating a manufacturing method using a nanoscale sphere formed by wet etching a polycrystalline oxide film according to the present invention for forming a pattern on the surface of a transparent electrode layer. 4A to 4D are flowcharts of fabricating nanosphere nanospheres by wet etching an indium tin oxide (ITO) polycrystalline oxide film and photographs observed with a scanning electron microscope. 5 is a photograph of a pattern formed on a gallium nitride (GaN) surface using an ITO nanoscale sphere as an etching mask and observed with a scanning electron microscope. FIG. 6 is a photograph taken by scanning electron microscope to form a pattern on the transparent electrode layer by depositing an ITO thin film on the ITO nanoscale sphere. 7A and 7B are curves showing optical characteristics of the nitride-based semiconductor LED of the present invention.

2A to 2B, in the method of manufacturing the nitride-based semiconductor light emitting device of the present invention, the nitride-based semiconductors 21, 22, 23, 24, and 25 are grown on the base substrate 10 to form the nitride-based semiconductors. Step a exposing the n-type layer 22 of the semiconductors 21, 22, 23, 24, 25, and depositing a polycrystalline oxide film on the entire surface of the nitride based semiconductors 21, 22, 23, 24, 25 and acidic Step b of forming nanoscale spheres 41 by wet etching using a solution, and nanoscale spheres 41 formed of ITO formed nitride nitride semiconductors 21, 22, 23, 24, and 25. Using the etching pattern 31 as a dry etching step c, and the pattern 31 on the surface of the nitride-based semiconductor (21, 22, 23, 24, 25) using the c step to form a transparent electrode 42 The step d and the step e of forming the n-type electrode pad 50 and the p-type electrode pad 60 in the nitride-based semiconductor (21, 22, 23, 24, 25).

Each step will be described sequentially.

Referring to FIG. 2A, nitride-based semiconductors 21, 22, 23, 24, and 25 are grown on the base substrate 10 using metal organic chemical vapor deposition (MOCVD) in step a. The substrate 10 may be one of sapphire (Al ₂ O ₃ ), gallium nitride (GaN), silicon carbide (SiC), silicon (Si), and gallium arsenide (GaAs). The buffer layer 21 is formed on the substrate 10.

In addition, the n-type semiconductor layer 22 is formed on the buffer layer 21.

Herein, the n-type semiconductor layer 22 may be formed of gallium nitride (GaN) in one of IV-VI-group materials, such as silicon (Si), germanium (Ge), selium (Se), and tellium (Te). May be used as a dopant for the n-type semiconductor layer.

The p-type semiconductor layer 24 is formed on the n-type semiconductor layer 22. The p-type semiconductor layer 24 may include one of II-group materials such as magnesium (Mg), zinc (Zn), calcium (Ca), and strontium (Sr). dopant).

In addition, an active layer 23 in which light is formed in the device is interposed between the n-type semiconductor layer 22 and the p-type semiconductor layer 24. Here, the active layer 23 may be either a single layer or a multilayer quantum well layer using an indium gallium nitride / gallium nitride (InGaN / GaN) layer or an aluminum gallium nitride / gallium nitride (AlGaN / GaN) layer. Can be formed.

In addition, the present invention may manufacture a device having a wide wavelength range according to the composition of the nitride-based semiconductors 21, 22, 23, 24, and 25, respectively.

Further, in the case where ITO is used as the transparent electrode 42 in the device, a layer having a higher concentration of p-type or n-type or nickel (Ni), silver (Ag) and zinc on the p-type semiconductor layer 24 It is preferred that a layer 25 comprising at least one of (Zn) be added. Here, the layer 25 may be a high concentration p-type semiconductor layer.

2B, in step b, a polycrystalline oxide film 40 (see FIGS. 4A to 4D) is deposited on the entire surface of the nitride based semiconductors 21, 22, 23, 24, and 25, and an acidic solution is deposited. The wet etching is used to form nanoscale spheres (41).

Here, the polycrystalline oxide film 40 for forming the nanoscale sphere 41 in step b is, for example, SnO _x , In _x O _y _, Al _x O _y , ZnO, ZrO _x , HfO _x , TiO _x Or one or more oxide films such as Ta _x O _y and Ga _x O.

In addition, the acid solution is at least one of hydrochloric acid (HCl), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), oxalic acid (oxalic acid), sulfuric acid (H ₂ SO ₄ ), hydrofluoric acid (HF) and the like. It may be to include.

4A to 4B, an oxide film in a polycrystalline state that is not subjected to heat treatment is formed on the high concentration p-type semiconductor layer (FIG. 4A). In this state, etching occurs through a grain boundary with a weak binding force using the acidic solution as described above (FIG. 4B). When the interface between the polycrystalline oxide film and the nitride semiconductor is exposed as the etching progresses, etching occurs actively to the side by the weak bonding force at the interface (FIG. 4C). Subsequently, as illustrated in FIG. 4D, nanoscale spheres may be formed. Here, the etching time may be 5 seconds to 60 seconds. The etching conditions may have various conditions according to the etching equipment used for the process and the type of gas used for etching.

In addition, the thickness of the polycrystalline oxide film 40 may be 50 nm to 600 nm, wherein the thickness of the polycrystalline oxide film 40 and the size of the resulting nanoscale sphere 41 may coincide with each other. The size at this time may be an average size.

In addition, the etching rate of the polycrystalline oxide layer 40 may vary according to the concentration of the acidic solution. Therefore, the concentration of the acidic solution may be determined according to a suitable etching rate according to the thickness of the polycrystalline oxide film 40. Here, the acidity (pH) of the acidic solution may be 0.1 to 1.

In addition, the heat treatment temperature used to cure the nano-scale sphere 41 formed by the wet etching may be 300 ℃ to 700 ℃.

Referring to FIG. 2C, in step c, dry etching is performed using the nanoscale spheres 41 having the nitride-based semiconductors 21, 22, 23, 24, and 25 formed of ITO as an etching pattern.

Here, the dry etching may use plasma etching, and the gas forming the plasma may use a chlorine-based gas. Here, the chlorine-based gas may be used by mixing one or two or more of Cl ₂ , BCl ₃ , CCl ₄ , HCl.

In addition, the etching conditions may have various conditions depending on the type of gas used for etching equipment and etching used in the process.

In addition, referring to FIG. 2C, the pattern 31 may be formed on a desired portion of the upper surface of the nitride based semiconductors 21, 22, 23, 24, and 25 by varying the region in which the polycrystalline oxide film 40 is deposited. . In addition, when the polycrystalline oxide film 40 is deposited on the entire surface of the nitride based semiconductors 21, 22, 23, 24, and 25 as shown in FIG. 5, the pattern 31 may also be formed on the side surface 30 of the etched mesa surface. Can be formed. Here, the size of the formed pattern 31 is preferably matched to the shape of the nano-scale sphere 41 used as an etching mask.

Here, the depth etched between the patterns 31 may vary according to the dry etching condition.

In addition, the nano-scale sphere 41 used as an etching mask for dry etching can be easily removed according to the concentration of the acidic solution.

In addition, the nano-scale sphere 41 used as an etching mask used for dry etching may be made of a material that can withstand the dry etching for a predetermined time.

2D, the pattern 31 is formed on the surfaces of the nitride semiconductors 21, 22, 23, 24, and 25 used in the step c to form the transparent electrode 42.

In the d step, the transparent electrode layer 42 is formed of indium tin oxide (ITO), zinc oxide (ZnO), and iridium oxide (IrO ₂ ) or tin (Sn), gallium (Ga), manganese (Mn), or zinc in the transparent electrode layer. It may be any one selected from the group containing one or more materials of (Zn) and nickel (Ni).

In addition, in order to pattern the transparent electrode layer 42 using the nanoscale sphere 41, the polycrystalline oxide film forming the nanoscale sphere 41 may be formed of the same material as the polycrystalline oxide layer forming the transparent electrode layer 42. It is preferable to use.

On the other hand, it is preferable to form the nano-scale sphere 41 on the nitride semiconductors 21, 22, 23, 24, 25 in the same region as the transparent electrode layer 42.

In addition, as shown in FIG. 6, the nano-scale sphere 41 may be formed under the transparent electrode layer 42 or on the transparent electrode layer 42 to form different patterns. In consideration of the transmittance, it is desirable to vary the overall thickness of the transparent electrode layer 42.

The transparent electrode layer 42 and the polycrystalline oxide film 40 may be stacked by electron-beam deposition, sputtering, thermal deposition, and the like.

In addition, the heat treatment temperature for smooth ohmic contact of the transparent electrode layer 42 is a condition that satisfies the electrical and optical characteristics of each film, and may vary depending on the equipment or the atmosphere.

Meanwhile, referring to FIGS. 3A to 3B, in the present invention, a plurality of nitride semiconductors 21, 22, 23, 24, and 25 are grown on a base substrate 10 to form the nitride semiconductors 21, 22, and 23. A, exposing the n-type semiconductor layer 22 of (24, 25), and transparent using a photo-lithography process on the surface of the nitride-based semiconductor (21, 22, 23, 24, 25) B) depositing a polycrystalline oxide film 40 (not shown) on the surface on which the electrode layer is to be formed, and forming nanospheres 41 by wet etching using an acidic solution, and the nanoscale spheres 41. C to form a pattern by depositing a transparent electrode layer 42 thereon, and n-type electrode pads 50 and p-type electrode pads 60 to the nitride-based semiconductors 21, 22, 23, 24, and 25. Forming step d may include.

As described above with reference to FIG. 2, the nanoscale spheres 41 formed by wet etching the polycrystalline oxide film 40 (not shown) may be formed by performing the process of FIG. 3. Except for the process used for forming a pattern on the surface of 24, 25), the remaining processes are substantially the same.

In addition, in step b, a region in which the polycrystalline oxide film 40 is deposited may be separated through a photolithography process (or an exposure process), and thus a pattern may be formed only on the transparent electrode layer 42.

In addition, the step c of FIG. 2 and the step c of FIG. 3 may be simultaneously performed to form a pattern on the nitride based semiconductors 21, 22, 23, 24, and 25, and a pattern may be formed on the transparent electrode layer 42. have.

Hereinafter, examples and test examples of the present invention will be described. However, the present invention is not limited by the examples or the test examples. In addition, the following reference numerals will use the symbols specified in the drawings.

&Lt; Example 1 >

2A to 2D, the substrate 10 is made of sapphire (Al ₂ O ₃ ) and the buffer layer 21 is formed of gallium nitride (GaN) by metal organic chemical vapor deposition (MOCVD). And an n-type semiconductor layer 22 made of silicon (Si) as a dopant, an active layer 23 composed of indium gallium nitride / gallium nitride (InGaN / GaN), and p with magnesium (Mg) as a dopant. Nitride-based semiconductors 21, 22, 23, 24, and 25 in which the semiconductor layer 24 and the high concentration p-type semiconductor layer 25 are sequentially stacked are prepared.

Next, a mesa is formed to a height of 600 nm to 1 μm through dry etching, and 200 nm thick indium tin oxide (ITO) is deposited on the entire surface of the nitride semiconductors 21, 22, 23, 24, and 25 using an electron beam deposition method. Wet etching with HCl of pH 0.7 0.1 for 10 seconds to form nanoscale spheres 41 with an average diameter of 200 nm. Here, the nanoscale sphere 41 is formed over the entire area of the nitride based semiconductors 21, 22, 23, 24, and .25 by dry etching for 20 seconds using the nanoscale sphere 41 as an etching mask. Form a protrusion of the same pattern as the shape of.

Next, the nano-scale sphere 41 used as a mask for dry etching is immersed in HCl of pH 0.10 for 5 minutes and removed from the surfaces of the nitride semiconductors 21, 22, 23, 24, and 25. Next, the nitride-based light emitting device is manufactured after washing.

A 100 nm indium tin oxide (ITO) film 40 (not shown), which is an oxide film, is deposited on the p-type semiconductor layer 24 of the nitride semiconductors 21, 22, 23, 24, and 25 using a transparent electrode pattern. According to the wet etching method, a nanoscale sphere 41 is formed, and 200 nm of indium tin oxide (ITO) is deposited thereon to form a transparent electrode layer 42 having a pattern formed in a hemispherical shape. Here, when the heat treatment in 600 ℃ oxygen atmosphere improves the transmittance and electrical properties of the transparent electrode layer 42. Therefore, nitride electrodes can be manufactured by forming the electrodes 50 and 60, respectively.

The following describes a test example according to the above embodiments.

Nitride Semiconductor layer Check pattern formation of surface

The surface state of the nitride-based light emitting device prepared in Example 1 is photographed with a scanning election micrograph (SEM).

FIG. 5 is a photograph of an n-type semiconductor layer, a p-type semiconductor layer, and an etched mesa surface of the nitride-based light emitting device according to Example 1, observed with a scanning electron microscope (SEM).

As shown in FIG. 5, the pattern 31 is formed on the surfaces of the nitride-based semiconductors 21, 22, 23, 24, and 25 in the same shape as that of the nanoscale sphere 41 used as a mask for dry etching. It can be confirmed that it is formed.

The formation of protrusions having a size of 50 nm to 200 nm increases the scattering of light at the interface between the nitride semiconductors 21, 22, 23, 24 and 25 and the air or the transparent electrode layer 42, resulting in increased light extraction efficiency. Can be improved.

Transparent electrode layer Surface Patterning Confirm

The surface state of the transparent electrode layer 42 of the nitride-based light emitting device manufactured in Example 2 was photographed with a scanning electron microscope (SEM). 6 is a photograph of the surface of the transparent electrode layer of the nitride-based light emitting device prepared in Example 2 observed with a scanning electron microscope (SEM). By depositing 200 nm of indium tin oxide (ITO) on a nano-scale sphere 41 having an average size of 100 nm and then heat-treating, the transparent electrode layer 42 bonded to one film is nano-scaled on a dense spherical surface. A thin film thicker than the diameter of the sphere 41 was deposited to obtain a hemispherical surface. By having a uniform hemispherical transparent electrode surface, scattering at the interface between the transparent electrode and the air can be increased to improve light extraction efficiency.

Check the electrical properties of the nitride-based light emitting device

When the electrical characteristics of the nitride-based light emitting devices manufactured by Examples 1 and 2 were applied by changing the voltage from -10V to + 10V using a probe station, the current characteristics according to the above-described Examples 1 and 2 were measured. The operating voltage in Example 2 is substantially the same as that of the nitride-based light emitting device manufactured by the general method, and the leakage current is reduced due to the reduction of foreign matter and defects on the nitride-based semiconductor surface by HCl used for etching in the manufacturing process.

Confirmation of optical properties of the nitride-based light emitting device

7A and 7B, light output characteristics of the nitride-based light emitting devices manufactured according to Examples 1 and 2 were evaluated. FIG. 7A illustrates a case in which a pattern is formed on the surfaces of the nitride based semiconductors 21, 22, 23, 24, and 25 using the nanoscale sphere 41 as a dry etching mask. 41) is a case of forming a pattern on the surface of the transparent electrode layer 42, referring to this, the light output of the nitride-based light emitting device of the present invention shows an improved result than the general device. In FIG. 7B, in which the pattern is formed only on the transparent electrode layer 42, the disadvantage of an increase in the operating voltage due to plasma damage during dry etching may be eliminated.

1A and 1B are views exemplarily comparing the escape of light appearing on the surface of the nitride semiconductor light emitting device when a pattern is formed on the surface of the nitride semiconductor according to the present invention.

2A to 2D are diagrams sequentially illustrating a manufacturing method using a nanoscale sphere formed by wet etching a polycrystalline oxide film according to the present invention as a dry etching mask for forming a pattern on a surface of a nitride semiconductor.

3A to 3D are diagrams sequentially illustrating a manufacturing method using a nanoscale sphere formed by wet etching a polycrystalline oxide film according to the present invention for forming a pattern on the surface of a transparent electrode layer.

4A to 4D are flowcharts of fabricating nanosphere nanospheres by wet etching an indium tin oxide (ITO) polycrystalline oxide film and photographs observed with a scanning electron microscope.

5 is a photograph of a pattern formed on a gallium nitride (GaN) surface using an ITO nanoscale sphere as an etching mask and observed with a scanning electron microscope.

FIG. 6 is a photograph taken by scanning electron microscope to form a pattern on the transparent electrode layer by depositing an ITO thin film on the ITO nanoscale sphere.

7A and 7B are curves showing optical characteristics of the nitride-based semiconductor LED of the present invention.

* Description of main parts *

10: substrate

21: buffer layer

22: n-type semiconductor layer

23: active layer

24: p-type semiconductor layer

25: high concentration p-type semiconductor layer

30: mesa side

31: Patterned Gallium Nitride (GaN) Surface

40 polycrystalline oxide film

41: indium tin oxide (ITO) nanoscale sphere (nanosphere)

42: transparent electrode layer

50: p-type electrode pad

60: n-type electrode pad

Claims

Forming a plurality of nitride based semiconductor layers on the substrate;

Forming a nanoscale sphere by applying wet etching using an acidic solution to the polycrystalline oxide film;

And dry etching the upper surface of the nitride based semiconductor using the nanoscale sphere as an etching pattern.

delete

The method of claim 1,

And removing the nanoscale spheres formed on the upper surface of the nitride semiconductor.

The method of claim 3,

A method of manufacturing a nitride-based semiconductor light emitting device, characterized in that it further comprises forming a transparent electrode layer.

The method of claim 1,

And forming a transparent electrode layer, wherein the pattern of the nanoscale sphere is transferred to simultaneously form a pattern of the transparent electrode layer.

The method of claim 1,

And forming a transparent electrode layer, wherein the lower pattern of the transparent electrode layer is transferred to simultaneously form a pattern of the transparent electrode layer.

The method according to any one of claims 4 to 6,

A method of manufacturing a nitride-based light emitting device further comprising the step of forming an electrode pad.

The method of claim 1,

Forming a plurality of nitride-based semiconductor layers on the substrate to expose a portion of the n-type layer by mesa etching.

The method of claim 8,

Dry etching the upper surface and the mesa-etched inclined surface, a part of the exposed n-type layer of the nitride-based semiconductor using the nano-scale sphere as an etching pattern, the method of manufacturing a nitride-based semiconductor light emitting device .

10. The method of claim 9,

The method of claim 10,

And forming a transparent electrode layer on the upper surface of the nitride semiconductor.

The method of claim 11,

And forming a p-type electrode pad on an n-type electrode pad and a transparent electrode layer forming surface on a part of the exposed n-type layer of the nitride-based semiconductor.

The method of claim 8,

A step of growing a plurality of nitride-based semiconductors on an underlying substrate to expose an n-type layer of the nitride-based semiconductor;

And forming an n-type electrode pad (60) and a p-type electrode pad (50) on the nitride semiconductor.

The method according to claim 1 or 14, wherein

The nitride-based semiconductor layer manufacturing method of the nitride-based semiconductor light emitting device, characterized in that it comprises an n-type nitride-based semiconductor layer, an active layer, a p-type nitride-based semiconductor layer.

The method according to claim 1 or 14, wherein

Polycrystalline oxide film for forming the nano-scale sphere is one or two such as SnO _x , In _x O _y _, Al _x O _y , ZnO, ZrO _x , HfO _x , TiO _x , Ta _x O _y , Ga _x O It is a polycrystal oxide film which consists of the above, The manufacturing method of the nitride type semiconductor light emitting element characterized by the above-mentioned.

The method according to claim 1 or 14, wherein

The polycrystalline oxide is etched by wet etching, and the acidic solution is hydrochloric acid (HCl), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), oxalic acid, sulfuric acid (H ₂ SO ₄ ), hydrofluoric acid A method for producing a nitride-based semiconductor light-emitting device comprising at least one of (HF) and the like.

The method of claim 17,

The acidity (pH) of the acidic solution is a method of manufacturing a nitride-based semiconductor light emitting device, characterized in that 0.1 to 1.

The method according to claim 1 or 14, wherein

The polycrystalline oxide film is characterized by forming a nano-scale sphere by active etching at the boundary of the grain boundary and the weak bonding force between the polycrystalline oxide film and the nitride-based semiconductor in a polycrystalline state not subjected to heat treatment Is a method of manufacturing a nitride-based semiconductor light emitting device.

The method according to claim 1 or 14, wherein

When the thickness of the polycrystalline oxide film is 50nm to 600nm, the method of manufacturing a nitride-based semiconductor light emitting device, characterized in that for controlling the average size of the nano-scale spheres produced by adjusting the thickness of the polycrystalline oxide film.

The method according to claim 1 or 14, wherein

A method of manufacturing a nitride-based semiconductor light emitting device, characterized in that the nanoscale sphere through wet etching of the polycrystalline oxide film is used as a dry etching mask for forming protrusions on the surface of the nitride semiconductor.

The method of claim 21,

And a heat treatment for hardening a nanoscale sphere used as a dry etching mask for forming protrusions on the surface of the nitride semiconductor.

The method according to claim 5 or 14,

And forming a nano-scale sphere through wet etching of the polycrystalline oxide layer on or below the transparent electrode layer in order to form a pattern of the transparent electrode layer of the nitride-based semiconductor.

24. The method of claim 23,

The method of manufacturing a nitride-based semiconductor light-emitting device comprising the step of changing the shape of the sphere through the ICP treatment of the nano-scale sphere for forming the pattern of the transparent electrode layer.

The method according to any one of claims 4 to 6, 11, or 14,

The method of manufacturing a nitride-based semiconductor light emitting device, characterized in that the material of the polycrystalline oxide film and the transparent electrode layer is the same.

The method according to claim 1 or 14, wherein

The polycrystalline oxide film is a method of manufacturing a nitride-based semiconductor light emitting device, characterized in that the region left along the pattern by the photolithography process is selective.