KR100697829B1 - Manufacturing method of light emitting element and light emitting element manufactured by this method - Google Patents

Abstract

Disclosed are a method of manufacturing a light emitting device having a structure for increasing the extraction efficiency of light, and a light emitting device manufactured thereby. The back surface of the base substrate on which the gallium nitride based semiconductor element is formed is polished to a predetermined thickness. Subsequently, in order to increase the extraction efficiency of light generated by activation of the semiconductor element and extracted through the back surface of the base substrate, a constant roughness is applied to the back surface of the base substrate. As a result, the back surface of the base substrate on which the semiconductor element is formed is thinned to a predetermined thickness, and then, by providing a constant surface roughness to the back surface of the base substrate, the light extraction efficiency can be improved.

Light emitting element, gallium nitride, light extraction, sand blast, spray

Description

A manufacturing method of a light emitting element and a light emitting element manufactured by the same TECHNICAL FIELD

1 is a schematic diagram illustrating Snell's law.

2 is a perspective view schematically illustrating a structure of a general gallium nitride based light emitting diode.

3A and 3B are cross-sectional views illustrating a bonding method of the light emitting diode chip illustrated in FIG. 2.

4 is a cross-sectional view of a light emitting diode according to an embodiment of the present invention. In particular, it is sectional drawing of the light emitting diode manufactured by the sand blast process.

FIG. 5 is a conceptual diagram illustrating extraction characteristics of light of the light emitting diode shown in FIG. 4.

6A to 6H are cross-sectional views illustrating a method of manufacturing the light emitting diode shown in FIG. 4.

7 is a graph illustrating a change in roughness depending on the size of the sprayed particles.

8 is a graph illustrating a change in roughness depending on the injection pressure of the injection particles.

9 is a graph illustrating the sapphire substrate thickness reduction according to the injection pressure of the injection particles.

FIG. 10 is a graph illustrating extraction efficiency of light according to roughness of a base substrate back surface in the light emitting diode structure of the present invention. FIG.

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

10, 110: base substrate 11, 120: n-type gallium nitride layer

12, 130: active layer 13, 140: p-type gallium nitride layer

22, 150: p-type transparent electrode 21, 160: p-electrode

20, 170: n-electrode

The present invention relates to a method for manufacturing a light emitting device and a light emitting device manufactured thereby, and more particularly, to a method for manufacturing a light emitting device having a structure for increasing the extraction efficiency of light, and a light emitting device manufactured thereby.

In general, a light emitting diode, which is a light emitting device, is spotlighted as a next-generation lighting that replaces an incandescent bulb or a fluorescent lamp. In particular, demand is expected to increase further as it is used for lighting of large area LCDs with long lifespan.

However, most of the light generated by total reflection due to the difference in refractive index between the materials constituting the light emitting diode (sapphire substrate, epi, epoxy, etc.) is trapped. The total reflection occurs when light travels from a material having a relatively high refractive index to a material having a low refractive index at an interface having a different refractive index. The total reflection is determined by Snell'law.

1 is a schematic diagram illustrating Snell's law. Where n1 and n2 are the refractive indices of the first and second media, respectively, and θ1 and θ2 are the incident angle and the exit angle, respectively. Wherein the refractive index of the second medium is greater than the refractive index of the first medium.

Referring to FIG. 1, when light is transmitted from the second medium having a relatively large refractive index to the first medium having a relatively small refractive index, the exit angle θ2 of the transmitted light has an angle greater than the incident angle θ1.

In particular, the sapphire substrate and the gallium nitride (GaN) layer employed in the gallium nitride-based light emitting diode widely used as a blue light source has a refractive index of 1.8 and 2.5, respectively, and thus there is a significant difference from the air layer having a refractive index of 1. This large difference in refractive index causes a large portion of the light generated by the light emitting diode to be trapped inside. For example, the critical angle of the interface between the gallium nitride (GaN) layer and the sapphire substrate is about 46 degrees. Therefore, light having an angle of incidence greater than 46 degrees is trapped inside the gallium nitride (GaN) layer.

In the same manner, the critical angle between the sapphire substrate and the air interface is 33.5 degrees, and the critical angle between the gallium nitride (GaN) layer and the air layer is about 23.6 degrees. Therefore, light having an angle of incidence greater than 33.5 degrees is trapped inside the sapphire substrate, and light having an angle of incidence greater than 23.6 degrees is trapped inside the gallium (GaN) layer.

As such, since a large amount of light generated in the light emitting diode is not extracted due to total reflection of the interface, there is a problem that reduces the external quantum efficiency of the entire light emitting diode, thereby reducing the light output of the light emitting diode.

Accordingly, the technical problem of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a method for manufacturing a gallium nitride-based light emitting device that can increase the extraction efficiency of light by the sand blaster to implement a high brightness light emitting diode. To provide.

Another object of the present invention is to provide a gallium nitride-based light emitting device manufactured by the method for producing a light emitting device.

According to one or more exemplary embodiments, a method of manufacturing a light emitting device includes: (a) polishing a rear surface of a substrate on which a gallium nitride based semiconductor device is formed on a front surface; And (b) applying a predetermined roughness to the back surface of the substrate in order to increase the extraction efficiency of light generated by activation of the semiconductor device and extracted through the rear surface of the substrate.

According to another aspect of the present invention, there is provided a method of manufacturing a light emitting device, the method comprising: (a) sequentially growing an n-type gallium nitride layer, an active layer, and a p-type gallium nitride layer on a front surface of a substrate; Making a step; (b) depositing a p-contact layer in ohmic contact with said p-type gallium nitride layer and having a high reflective layer; (c) mesa etching a portion to be an n-contact; (d) Define a p-electrode by depositing a first metal layer at a relatively high edge region of the p-contact layer, and define a n-electrode by depositing a second metal layer on a relatively low mesa etched n-type gallium nitride layer. Making; And (e) imparting a certain roughness to the rear surface of the substrate using a sand blaster.

In order to realize the above object of the present invention, a light emitting device according to an embodiment includes a substrate and a gallium nitride based semiconductor device formed on a front surface of the substrate, and a rear surface of the substrate In order to increase the extraction efficiency of the light generated by the activation of the semiconductor device, it is characterized in that a given surface roughness.

In accordance with another aspect of the present invention, a light emitting device includes a substrate, an n-type gallium nitride layer formed on a front surface of the substrate, an active layer formed on the n-type gallium nitride layer, A p-type gallium nitride layer formed on the active layer, a p-contact layer deposited with a high reflective layer in ohmic contact with the p-type gallium nitride layer, and a p-electrode layer deposited in a relatively high edge region of the p-contact layer. And an n-electrode layer deposited on a relatively low mesa etched n-type gallium nitride layer, and a rear surface of the substrate is provided with a constant surface roughness to increase extraction efficiency of generated light. It is done.

According to such a light emitting device manufacturing method and a light emitting device manufactured thereby, the extraction efficiency of light can be improved by thinning the back surface of the substrate on which the semiconductor element is formed to a predetermined thickness and then giving a constant surface roughness to the back surface of the substrate. .

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the scope of the invention to those skilled in the art will fully convey. In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. As described in the drawing, when it is described from an observer's point of view, when a part such as a layer, a film, an area, or a plate is "on" another part, it is not only when another part is "directly" but also another part in between. It also includes the case. On the contrary, when a part is "just above" another part, it means that there is no other part in the middle.

2 is a perspective view schematically illustrating a structure of a general gallium nitride based light emitting diode.

Referring to FIG. 2, a typical gallium nitride based light emitting diode includes a base substrate 10, an n-type gallium nitride layer 11, an active layer 12, a p-type gallium nitride layer 13, and an n-electrode ( 20), a p-electrode 21, and a p-type transparent electrode 22. In operation, when current flows through the n-electrode 20 and the p-electrode 21, light is extracted while electron-hole recombination occurs in the active layer 12.

In order to grow the gallium nitride layer 11 on the base substrate 10, a metal organic chemical vapor deposition (MOCVD) device is usually used. The base substrate 10 is a sapphire substrate or a silicon carbide substrate.

First, a buffer layer (not shown) is formed on the base substrate 10 to assist the growth of the gallium nitride layer 11, and the n-type gallium nitride layer 11 and the active layer ( 12) and the p-type gallium nitride layer 13 are grown in sequence.

In general, a diode forms an electrode on top of a p-type gallium nitride layer and a base substrate connected to an n-type gallium nitride layer to flow current through a p-n junction. However, since the sapphire used as the substrate of the gallium nitride-based light emitting diode is an insulator, an electrode cannot be formed on the sapphire substrate 10. Therefore, an electrode must be directly formed on the n-type gallium nitride layer 11.

To this end, partial regions of the p-type gallium nitride layer 13, the active layer 12, and the n-type gallium nitride layer 11 in which the electrode is to be formed are removed, and the n-type gallium nitride layer 11 is exposed on the n-type gallium nitride layer 11. An electrode 20 is formed. Since the light is emitted from the p-n junction surface, the p-electrode 21 is formed at the corner of the p-type transparent electrode 22 so that the light is not obscured by the electrode.

As such, when both the p-electrode 21 and the n-electrode 20 are positioned at the top, the current is higher than that of a general diode structure in which the p-electrode 21 and the n-electrode 20 are located in parallel with each other. The distribution is not uniform.

In addition, the p-type gallium nitride layer 13 has a larger resistance than the n-type gallium nitride layer 11, and thus, it is more difficult for a current to flow uniformly through the p-type gallium nitride layer 13. In order to prevent this, a thin transparent electrode is formed on the entire upper surface of the p-type gallium nitride layer 13 so that current can be transferred to the entire surface of the p-type gallium nitride layer 13.

However, the transparent electrode is formed of a very thin metal layer of about 10 nanometers thick in order to allow light to be transmitted, so the resistance is high. There is a limit to uniform current transfer to the entire surface of the p-type gallium nitride layer using the high resistance transparent electrode.

In addition, the contact resistance with the p-type gallium nitride layer 13 is also high, the diode characteristics are deteriorated and may cause heat generation. The thickness of the transparent electrode can be increased to lower the resistance, but in this case, the absorption and reflectance of the light by the electrode are increased, so that light is hardly extracted.

In order to reduce such drawbacks, a method of increasing light emission efficiency of a light emitting diode using a flip chip bonding method has been proposed. That is, a thick electrode may be formed on the entire surface of the p-type gallium nitride layer, the LED chip may be inverted, and then mounted in a package by flip chip bonding.

3A and 3B are cross-sectional views illustrating a bonding method of the light emitting diode chip illustrated in FIG. 2. In particular, FIG. 3A is a cross-sectional view showing a gallium nitride-based LED chip assembled by wire bonding, and FIG. 3B is a cross-sectional view showing a gallium nitride-based LED chip assembled by flip chip bonding.

As shown in FIG. 3A, a package containing a light emitting diode chip is provided with a lead frame for supplying current. A light emitting diode chip is attached on the lead frame, and the lead frame and the n-electrode 20 and the p-electrode 21 of the light emitting diode chip are electrically connected with thin metal wires 30a and 30b. In this case, a thin transparent electrode is formed so that light can be emitted through the p-type gallium nitride layer.

On the other hand, as shown in Figure 3b, the flip-chip bonding method is provided with another substrate 40 connected to the lead frame, the solder bump ( solder bumps 31b are formed. The light emitting diode is turned upside down to attach a light emitting diode chip such that the electrodes of the light emitting diode and the solder bumps 31b are connected to each other.

Meanwhile, in order to reduce light loss due to total reflection of light generated from gallium nitride-based light emitting diodes, a method of texturing the exit surface is used. This is a method of scattering the light generated by the light emitting diode, thereby changing the propagation path of the light in various directions to increase the probability of the light escape from the inside of the light emitting diode.

The texturing method is divided into a method of texturing a surface of a gallium nitride (GaN) layer, a method of texturing a surface of a sapphire substrate, and a method of texturing a surface of a current diffusion layer (or window layer).

However, in the method of texturing the surface of the gallium nitride (GaN) layer, the surface of the gallium nitride (GaN) layer is rough, which adversely affects the p-electrode formation process, thereby deteriorating the electrical characteristics of the light emitting diode as a whole.

In addition, the method of texturing the surface of the sapphire substrate is not easy to etch the sapphire substrate itself is not easy manufacturing process. In addition, since the surface of the etched sapphire substrate is rough, there is a big problem in epitaxial growth.

In addition, the current diffusion layer used in the method of texturing the surface of the current diffusion layer is mainly a transparent oxide electrode such as indium tin oxide (ITO), antimony tin oxide (ATO). Since the p-type gallium nitride layer and the ITO are difficult to make ohmic contact with each other, a tunnel junction is actually formed by introducing a thin super lattice structure (SLS) on the p-type gallium nitride layer. However, the ITO electrode material is not only easy to etch, but also gives surface roughness to the electrode itself, so that surface scattering occurs when the current is injected, resulting in inferior electrical properties.

4 is a cross-sectional view of a light emitting diode according to an embodiment of the present invention. In particular, it is sectional drawing of the light emitting diode manufactured by the sand blast process. FIG. 5 is a conceptual diagram illustrating extraction characteristics of light of the light emitting diode shown in FIG. 4.

4 and 5, the gallium nitride based light emitting diode 100 according to the embodiment of the present invention includes a base substrate 110, an n-type gallium nitride layer 120, an active layer 130, and p. The gallium nitride layer 140, a current spreading layer 150, a p-electrode 160, and an n-electrode 170 are included. The back surface of the base substrate 110 has a rough shape with a certain roughness.

When a constant current flows between the p-electrode 160 and the n-electrode 170, electron-hole recombination occurs in the active layer 130, and light is extracted through the back surface of the base substrate 110.

In order to grow a gallium nitride layer on the base substrate 110, a MOCVD (Metal Organic Chemical Vapor Deposition) device is usually used. The base substrate 110 is a sapphire substrate or a silicon carbide substrate.

The n-type gallium nitride layer 120, the active layer 130, and the p-type gallium nitride layer 140 are sequentially grown on the base substrate 110. A buffer layer may be further formed on the base substrate 110 to assist the growth of the n-type gallium nitride layer 120.

In a typical diode, an electrode is formed on an upper portion of a p-type gallium nitride layer and a lower portion of a base substrate 110 connected to an n-type gallium nitride layer to flow current through a p-n junction. However, the gallium nitride-based light emitting diode uses sapphire as a base substrate, and since the sapphire is an insulator, electrodes cannot be formed on the base substrate 110. Thus, an electrode is formed on the n-type gallium nitride layer 120.

To this end, partial regions of the p-type gallium nitride layer 140, the active layer 130, and the n-type gallium nitride layer 120 of the portion where the electrode is to be formed are removed, and the n-type gallium nitride layer 120 is exposed on the n-type gallium nitride layer 120. An electrode 170 is formed. Accordingly, the n-type gallium nitride layer 120 is formed at a first height in the first region of the base substrate 110 and is formed at a second height smaller than the first height in the second region. In FIG. 4, the p-electrode 160 is formed at the edge of the current diffusion layer 150, but the p-electrode 160 may be formed on the entire surface of the current diffusion layer 150.

If the p-electrode 160 and the n-electrode 170 are both formed on the upper side, the current is compared with a general diode structure in which the p-electrode 160 and the n-electrode 170 are positioned in parallel with each other. The distribution is not uniform.

In addition, in general, the p-type gallium nitride layer 140 has a larger resistance than the n-type gallium nitride layer 120, and thus, it is more difficult for a current to flow uniformly through the p-type gallium nitride layer 140. In order to prevent this, the current diffusion layer 180, which is a thin transparent electrode, is formed on the entire upper surface of the p-type gallium nitride layer 140 to transmit current to the entire surface of the p-type gallium nitride layer 140.

On the other hand, the efficiency of light generated from the light emitting diode is divided into internal quantum efficiency and external quantum efficiency. The internal quantum efficiency is determined according to the design or quality of the active layer, and the external quantum efficiency is determined by the degree of light emitted from the active layer to the outside of the light emitting diode, and in particular, the refractive index and the critical angle.

In the case of external quantum efficiency, in the case of gallium nitride (GaN) material or sapphire having a constant refractive index, light must be crossed a critical angle in order to emit light into the air having a refractive index of 1.

If the light generated at an angle below the critical angle with respect to the emission surface is returned to the inside of the light emitting diode, the light is trapped inside the light emitting diode, and the light is absorbed from the epi layer or the sapphire substrate so that the external quantum efficiency is reduced. Drops sharply

However, as shown in Figure 5, according to the present invention, the emission surface given a constant roughness has a high probability that the angle formed by the light generated from the lower than the predetermined critical angle. Accordingly, the extraction efficiency of light to be emitted from the light emitting diode is increased, and the amount of light to be returned to the inside of the light emitting diode is relatively reduced, thereby increasing the external quantum efficiency.

6A to 6H are cross-sectional views illustrating a method of manufacturing the light emitting diode shown in FIG. 4.

Referring to FIG. 6A, a base substrate 109 having a predetermined thickness is prepared. The base substrate 109 is a sapphire substrate or a silicon carbide substrate. The thickness of the base substrate has a value exceeding 100 μm in consideration of being polished through a lapping / polishing process in the future.

Referring to FIG. 6B, an n-type gallium nitride layer 120 and an active layer 130 (eg, MQW; multi quantum well) are formed on the sapphire substrate 109 by using a metal organic CVD (MOCVD) method. And the p-type gallium nitride layer 140 are sequentially grown. The gallium nitride buffer layer may be further formed before the n-type gallium nitride layer 120 is grown.

Subsequently, a p-contact layer 150 having ohmic contact with the p-type gallium nitride layer 140 and having a high reflective layer is deposited. The p-contact layer 150 is made of Ni / Ag, Ni / Al, Pt / Ag, and the like, and is deposited by evaporation or sputtering.

6C and 6D, mesa etching is performed on a portion to be n-contact in the future by using a mask MA or a reticle. Accordingly, the n-type gallium nitride layer 120 formed at the first height in the first region of the base substrate 110 is formed at a second height smaller than the first height in the second region of the base substrate 110. do.

Referring to FIG. 6E, the p-electrode 160 is defined by depositing Cr / Ni / Au in a relatively high region of the region on the resultant of FIG. 6D, that is, an edge region of the p-contact layer 150. The n-electrode 170 is defined by depositing Ti / Al / Ti / Au or Cr / Ni / Au on a relatively low region, that is, mesa-etched gallium nitride layer 120.

Referring to FIG. 6F, the base substrate 109 may have a thickness of about 100 μm by lapping / polishing the back surface of the base substrate 109 having a predetermined thickness using a polishing roller ROL. Until polished.

Referring to FIG. 6G, a constant roughness treatment process is performed on the back surface of the base substrate 109 on which the lapping / polishing process is completed in order to increase the extraction efficiency of light of the light emitting diode. In the present invention, sand blaster is used to impart a certain roughness to the sapphire back surface. As described above, the back surface of the sapphire substrate on which the semiconductor element is formed is thinned to a predetermined thickness, and then a constant surface roughness is applied to the back surface of the sapphire substrate by using a sand blaster process, thereby improving light extraction efficiency. It can increase.

As the spray particles used in the general sand blaster process, silicon carbide (SiC) is frequently used. Since the base substrate, particularly the sapphire substrate, according to the present invention has a high hardness of MOS hardness of 9, it is preferable to use a material having a hardness higher than that of silicon carbide. For example, the material of the spray particles is preferably boron carbide (B4C) or aluminum oxide (Al2O3).

The size of the spray particles according to the present invention is preferably 120 ~ 250㎛, the spray time of the spray particles is preferably 5 minutes or less, the spray pressure of the spray particles is preferably 2kg / ㎠ to 5kg / ㎠.

In the sand blaster processing step, the thickness of the sapphire substrate is preferably reduced to within 20 μm in consideration of the stress applied to the substrate and excessively decreasing the sapphire substrate thickness, and the surface roughness of the back surface of the substrate takes into account uniformity. It is preferable that the processed to be 1000Å or more.

7 is a graph illustrating a change in roughness depending on the size of the sprayed particles.

Referring to FIG. 7, when the diameter of the sprayed particles is 50 μm, the surface roughness Ra is close to zero, while when the diameter of the sprayed particles is 150, the surface roughness Ra is close to 1400 μs. When the diameter is 200, the surface roughness Ra is about 3000 kPa, and when the diameter of the sprayed particle is 250, the surface roughness Ra is nearly 4000 kPa. Here, the surface roughness is a center line average roughness, which is the value divided by the measurement length by adding the areas of the upper and lower portions of the center line of the cross-sectional curve.

As such, it can be seen that the larger the diameter of the spray particles, the rougher the surface appears.

8 is a graph illustrating a change in roughness depending on the injection pressure of the injection particles.

Referring to FIG. 8, when the spraying pressure of the spray particles is 2Kg / cm 2, the surface roughness Ra approaches 1000 μm, and when the spraying pressure of the spray particles is 3Kg / cm 2, the surface roughness is 2000. When the spraying pressure of the spray particles is 4Kg / cm 2, the surface roughness is close to 3300 µm. In addition, when the injection pressure of the injection particles is 5Kg / cm 2, the surface roughness is around 4000 μm, and when the injection pressure of the injection particles is 6Kg / cm 2, the surface roughness is close to 4500 μm.

As such, it can be seen that the surface roughness increases as the spraying pressure of the spraying particles increases.

However, when the injection pressure of the injection particles exceeds 5Kg / ㎠, since the thickness of the sapphire substrate is excessively reduced, the stress of the sapphire substrate due to the injection pressure increases and there is a risk of breakage of the sapphire substrate in the subsequent process is preferable. Not. Therefore, the injection pressure of the injection particles is preferably 5 Kg / cm 2 or less.

9 is a graph illustrating the thickness reduction of the sapphire substrate according to the spray pressure of the spray particles.

Referring to Figure 9, while spraying 250um diameter spray particles for 5 minutes, the injection pressure is increased to 2Kg / ㎠, 3, Kg / ㎠, 4Kg / ㎠, 5Kg / ㎠, 6Kg / ㎠ and 7Kg / ㎠ As the sapphire substrate is applied, it can be seen that the depth deepens to 5 μm, 9 μm, 15 μm, 20 μm, 33 μm, and 43 μm.

However, when the injection pressure of the injection particles exceeds 5Kg / ㎠, it can be seen that because the wave to the depth of 33㎛, the thickness of the sapphire substrate is excessively reduced. The injection pressure of the spray particles is preferably 5 Kg / cm 2 or less.

In order to see the light extraction efficiency of the light emitting diode according to the present invention, the chip size was fixed to 300 × 300 × 100 μm using a Ray Tracing simulator.

In the comparative example, the light emitting diode having the flat back surface of the sapphire substrate was arranged in a flip chip structure, and in the embodiment of the present invention, the light emitting diode having the constant roughness of the back surface of the sapphire substrate was arranged in the flip chip structure and compared with each other. Here, since the surface having a certain roughness is random and the roughness is different from each other, it is impossible to simulate the actual situation. Therefore, the simulation was performed assuming the rough surface as a pyramid shape and the RMS roughness value as the height of the pyramid. .

FIG. 10 is a graph illustrating extraction efficiency of light according to roughness of a base substrate back surface in the light emitting diode structure of the present invention. FIG.

Referring to FIG. 10, the light extraction efficiency of the light emitting diode according to the comparative example was observed to be 34%.

However, when the average roughness of 500 kW was applied to the back surface of the sapphire substrate, the extraction efficiency of 42% of light was measured. When the average roughness of 1,000 to 12,000 kW was applied, the extraction efficiency of light of 47 to 49% was measured. Accordingly, it can be seen that the extraction efficiency of light is improved by up to 14% compared to the light emitting diode which does not give the roughness by providing a constant roughness on the back surface of the sapphire substrate.

When the average roughness Ra of the sapphire substrate is 500 kW, the reason why the efficiency of light extraction is lower than that of 1000 kW or more is that Ra is so small that the uniformity of the surface roughness falls.

According to the above results, in the case of flip chips, the back surface of the sapphire substrate is roughened to increase the light extraction efficiency, and when the roughness of the back surface of the sapphire substrate is 1,000 k 이면 or more, the light extraction efficiency is almost unaffected. Can be.

As described above, the total reflection of light generated in the active layer can be reduced, so that a light emitting diode having high light extraction efficiency can be manufactured. The manufacturing process of roughening the back surface of the sapphire substrate is performed by using a sand blaster method, unlike the conventional masking and patterning, and then texturing using a dry etching process. Mass production can be increased, and there is an advantage that can reduce the process cost.

The stability of the process can be obtained by showing the extraction efficiency of light almost constant regardless of the degree of roughness on the back surface of the sapphire substrate.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (23)

(a) polishing a rear surface of a substrate on which a gallium nitride based semiconductor device is formed on a front surface thereof to a predetermined thickness; And (b) imparting a certain roughness to the back surface of the substrate to increase the extraction efficiency of light generated by activation of the semiconductor device and extracted through the rear surface of the substrate; . The method of claim 1, wherein step (a) (a-1) sequentially growing an n-type gallium nitride layer, an active layer and a p-type gallium nitride layer on the entire surface of the substrate; (a-2) depositing a p-contact layer in ohmic contact with the p-type gallium nitride layer and having a high reflective layer; (a-3) mesa etching a portion to be an n-contact; And (a-4) Defining a p-electrode by depositing a first metal layer at a relatively high edge region of the p-contact layer, and depositing a second metal layer on a relatively low mesa etched n-type gallium nitride layer. Method of manufacturing a light emitting device comprising the step of defining. The method of claim 1, wherein step (a) (a-1) sequentially growing a p-type gallium nitride layer, an active layer and an n-type gallium nitride layer on the entire surface of the substrate; (a-2) depositing an n-contact layer in ohmic contact with the n-type gallium nitride layer and having a high reflective layer; (a-3) mesa etching a portion to be a p-contact; And (a-4) Deposition of the first metal layer at the edge region of the relatively high n-contact layer to define the n-electrode, and deposition of the second metal layer on the relatively low mesa etched p-type gallium nitride layer to form the p-electrode Method of manufacturing a light emitting device comprising the step of defining. The method of manufacturing a light emitting device according to claim 1, wherein the predetermined roughness is formed by a sand blaster. (a) sequentially growing an n-type gallium nitride layer, an active layer and a p-type gallium nitride layer on the front surface of the substrate; (b) depositing a p-contact layer in ohmic contact with said p-type gallium nitride layer and having a high reflective layer; (c) mesa etching a portion to be an n-contact; (d) Defining a p-electrode by depositing a first metal layer at a relatively high edge region of the p-contact layer, and defining a n-electrode by depositing a second metal layer on a relatively low mesa etched gallium nitride layer. Doing; And (e) applying a constant roughness to a rear surface of the substrate using a sand blaster. The method of claim 5, wherein the step (d) further comprises polishing a rear surface of the substrate on which the p-electrode and the n-electrode are formed to a predetermined thickness. The method of claim 6, wherein the substrate has a thickness of about 100 μm. The method of manufacturing a light emitting device according to claim 5, wherein the step (e) imparts a roughness to a depth of 20 µm or less on the rear surface of the substrate. The method of manufacturing a light emitting device according to claim 5, wherein the step (e) imparts a surface roughness of 1000 kPa or more to the rear surface of the substrate. delete The method of claim 5, wherein the hardness of the particles injected from the sand blaster is greater than the hardness of the substrate. The method of claim 5, wherein the particles sprayed from the sand blaster include boron carbide (B 4 C) or aluminum oxide (Al 2 O 3). The method of manufacturing a light emitting device according to claim 5, wherein the size of the particles sprayed from the sand blaster is 120 to 250 µm. The method of manufacturing a light emitting device according to claim 5, wherein the injection time of the particles by the sand blaster is 1 minute to 5 minutes. The method of claim 5, wherein the injection pressure of the particles injected from the sand blaster is from 2 kg / cm 2 to 5 kg / cm 2. Board; And A gallium nitride based semiconductor element formed on a front surface of the substrate, And a predetermined surface roughness is given to a rear surface of the substrate in order to increase the extraction efficiency of light generated by activation of the semiconductor device. The light emitting device according to claim 16, wherein the back surface of the substrate is provided with a surface roughness of 1000 GPa or more. The light emitting device according to claim 16, wherein the back surface of the substrate is provided with a roughness to a depth of 20 µm or less. The method of claim 16, wherein the semiconductor device, An n-type gallium nitride layer formed on the front surface of the substrate; An active layer formed on the n-type gallium nitride layer; A p-type gallium nitride layer formed on the active layer; A p-contact layer deposited in ohmic contact with the p-type gallium nitride layer and having a high reflective layer; A p-electrode layer deposited in the edge region of the relatively high p-contact layer; And And a n-electrode layer deposited over a relatively low mesa etched n-type gallium nitride layer. The method of claim 16, wherein the semiconductor device, A p-type gallium nitride layer formed on the front surface of the substrate; An active layer formed on the p-type gallium nitride layer; An n-type gallium nitride layer formed on the active layer; An n-contact layer deposited in ohmic contact with the n-type gallium nitride layer and having a high reflective layer; An n-electrode layer deposited in the edge region of the relatively high n-contact layer; And And a p-electrode layer deposited over a relatively low mesa etched p-type gallium nitride layer. Board; An n-type gallium nitride layer formed on the front surface of the substrate; An active layer formed on the n-type gallium nitride layer; A p-type gallium nitride layer formed on the active layer; A p-contact layer deposited in ohmic contact with the p-type gallium nitride layer and having a high reflective layer; A p-electrode layer deposited in the edge region of the relatively high p-contact layer; And A n-electrode layer deposited over a relatively low mesa etched n-type gallium nitride layer, A light emitting element according to claim 1, wherein a surface roughness is given to a rear surface of the substrate in order to increase extraction efficiency of generated light. The light emitting device according to claim 21, wherein the back surface of the substrate has a surface roughness of not less than 1000 GPa. The light emitting device according to claim 21, wherein the rear surface of the substrate is provided with a roughness with a depth of 20 µm or less.

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