KR100700529B1 - Light emitting diode with current spreading layer and manufacturing method thereof - Google Patents

Abstract

An LED and its manufacturing method are provided to reduce a driving voltage and to improve the brightness by improving remarkably lateral current spreading characteristics using a current spreading layer. A first N type contact layer(130) made of a nitride semiconductor layer is formed on a substrate(110) via a buffer layer(120). A current spreading pattern(140) is formed on the first N type contact layer or in the first N type contact layer. A second N type contact layer(150) is formed on the resultant structure. An active layer(160) and a P type contact layer(180) are sequentially formed on the second N type contact layer.

Description

LIGHT EMITTING DIODE WITH CURRENT SPREADING LAYER AND MANUFACTURING METHOD THEREOF

1 is a cross-sectional view showing the structure of a conventional light emitting diode.

Figure 2a to 2e is a cross-sectional view showing a conventional light emitting diode manufacturing process.

Figure 3 is a cross-sectional view showing the structure of an embodiment of the present invention.

Figure 4 is a cross-sectional view showing the structure of another embodiment of the present invention.

Figure 5 is a cross-sectional view showing the structure of another embodiment of the present invention.

6a to 6d is a cross-sectional view showing a process of manufacturing the structure of FIG.

7A to 7D are cross-sectional views illustrating a process of manufacturing the structure of FIG. 4.

8a to 8d is a cross-sectional view showing a process of manufacturing the structure of FIG.

9 is a plan view showing examples of patterns of the current diffusion layer applicable to the present invention.

Top view showing the nano-rod shape of other embodiments.

* Description of the symbols for the main parts of the drawings *

110: substrate 120: buffer layer

130: first n-GaN layer 135: first interface layer

140 and 141: metal current diffusion pattern 142: oxide conductive layer

145: second interface layer 150: second n-GaN layer

151: low temperature n-GaN layer 152: high temperature n-GaN layer

153: second n-GaN layer 160: active layer

170: p-cladding layer 180: p-GaN layer

190: p electrode 200: n electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode having a current spreading layer and a method of manufacturing the same, and particularly to a side current injection type light emitting diode using a III-V nitride semiconductor, which helps to spread current inside an n contact layer having poor side current characteristics. The present invention relates to a light emitting diode having a current spreading layer which is formed to form a current spreading layer pattern to increase efficiency and tolerate static electricity, and a method of manufacturing the same.

The III-V nitride semiconductors have been applied to optical devices including blue / green light emitting diodes (LEDs) and electronic devices that are high-speed switching and high-output devices such as MOSFETs and HEMTs. In particular, the light emitting device using the group III nitride semiconductor has a direct transition band gap corresponding to the region from visible light to ultraviolet light, and high efficiency light emission can be realized. Therefore, the semiconductor is mainly used as an LED or a laser diode (LD), and researches for obtaining an easier manufacturing process and higher light efficiency have been continued.

Among the III-V nitride semiconductors, gallium nitride (GaN) is typically used, which is grown on a substrate by a crystal growth method, and is activated in a p-type or n-type according to a doped material to be composed of a PN junction diode. . However, sapphire (Al ₂ O ₃ ) single crystals or silicon carbide (SiC) single crystals cannot be manufactured in a large amount because a single crystal substrate having a lattice structure that is large enough to directly grow the nitride semiconductor (GaN) can be manufactured by the present technology. Substrates made of heterogeneous materials such as are mainly used.

Large lattice mismatch appears between the dissimilar substrate and the III-V nitride semiconductor crystal epitaxially grown on the substrate. For example, a lattice mismatch of 16% appears between sapphire (Al ₂ O ₃ ) and gallium nitride (GaN), and a lattice mismatch of 6% appears between silicon carbide (SiC) and gallium nitride. When such a large lattice mismatch occurs, it is difficult to epitaxially grow nitride semiconductor crystals on the substrate, and even though it can be grown, the formation is not good and it is not useful. Therefore, when epitaxially growing a group III nitride semiconductor on a substrate of sapphire single crystal or SiC single crystal by metal-organic chemical vapor deposition (MOCVD) method, a low temperature buffer layer made of (Al) GaN is formed. Deposition is first carried out on the substrate, followed by epitaxial growth of group III nitride semiconductor crystals thereon at high temperature.

FIG. 1 is a cross-sectional view illustrating a structure of a light emitting diode using a group III-V nitride semiconductor, and in the case of FIG. 1, a side current injection type light emitting diode in which all electrodes are applied in a front direction.

Briefly describing the structure, first, there is a GaN buffer layer 20 formed at low temperature without doping to solve the lattice mismatch on the sapphire substrate 10, and the first and second grown with n-type impurities thereon n-GaN layers 30 and 40 are located. Then, there is an active layer 50 made of one of various configurations (single active layer, quantum well structure, multiple quantum well structure, etc.) on the top, and the p-GaN layer 70 grown by including p-type impurities on the top Located. In the illustrated case, the p-clad layer 60 is further formed between the p-GaN layer 70 and the active layer 50 to increase the luminous efficiency, and the active layer 50 and the n-GaN layer 40 are formed. An n-clad layer (not shown) may be further formed therebetween.

The n-electrode 45 is positioned on the first n-GaN layer 30, and the p-electrode 80 is positioned on the p-GaN layer 70. For even current distribution, a transparent electrode (not shown) may be further formed on the entire surface of the p-GaN layer 70. The n-GaN layer 30 may be referred to as an n-contact layer and the p-GaN layer 70 may be referred to as a p-contact layer.

The process of manufacturing the above-described structure will be described through the procedure cross-sectional view shown in FIGS. 2A to 2E.

First, as shown in FIG. 2A, a GaN buffer layer 20 is formed at low temperature without doping to eliminate lattice mismatch on the sapphire substrate 10, and an n-GaN layer is formed by including Si, which is an n-type impurity, on the upper portion thereof. (30, 40) is formed by growing at high temperature.

The sapphire substrate 10 is heated to a high temperature of 1,000 to 1,200 ° C. in a growing apparatus to remove an oxide film or the like from its surface. The temperature of the growth device is then lowered to a temperature of approximately 400-600 ° C. to form the GaN low temperature buffer layer 20.

The low temperature buffer layer 20 is grown using MOCVD, and is epitaxially grown at a V / III ratio of 3,000 to 10,000 by simultaneously supplying an organic metal raw material and a nitrogen source. The V / III ratio refers to the ratio of the number of moles of molecules containing Group III elements and the number of moles of Group V elements when the Group III-V compound semiconductor crystal is grown by MOCVD. it means.

In addition to the growth method using the above-described low temperature buffer layer, a method of growing an aluminum nitride (AlN) layer on a substrate at a high growth temperature of approximately 900 to 1200 ° C. and then growing gallium nitride thereon is also known. In the case of using a sapphire substrate, gallium nitride is epitaxially grown using the low temperature buffer layer 20 in most cases.

Then, the process of forming the n-type GaN layers 30, 40 located on the low temperature buffer layer 20 is grown using MOCVD method similarly to the low temperature buffer layer 20, but the growth process is 900 ℃ or more It is carried out at high temperatures. This is because ammonia (NH ₃ ) is used as a precursor of nitrogen, and H ₂ is used as a carrier gas. Since the ammonia is very thermally stable, only a few percent of ammonia is pyrolyzed even at 900 ° C. or higher. Contributes to GaN growth as a source. Of course, growth is possible even below that temperature. Therefore, high temperature growth is inevitable in order to increase pyrolysis efficiency, and a V / III fraction of 4,000 to 10,000 is generally used for good crystallinity of GaN growth. At this time, impurities such as Si are included in the grown GaN to operate as the n-GaN layers 30 and 40.

As shown in FIG. 2B, an active layer 50 is formed on the formed n-GaN layers 30 and 40, which is a single quantum well structure in which a single active layer structure, a quantum well structure, and a plurality of quantum well structures are stacked. It may be formed into a structure. The quantum well structure is such that the active layer (InGaN layer) is positioned between two charge restraint layers ((Al) GaN layer) to adjust the wavelength of light and improve quantum efficiency. Multiple quantum well structures such as are commonly used. N-type and p-type superlattices may be inserted in the upper and lower portions of the active layer 50 to increase carrier confinement.

As shown in FIG. 2C, a p-cladding layer 60 is formed on the formed active layer 50, and a p-GaN layer 70 is formed thereon. The p-cladding layer 60 is not essential, but is added between the active layer 50 and the p-GaN layer 70 activated in p-type using Mg as an impurity to increase the carrier concentration. The p-cladding layer 60 should be thick because it should protect Mg of the p-GaN layer 70 from entering the active layer 50, and facilitate recombination of electrons and holes in the active layer 50. It should be thin enough to help to maximize the photon emission from the active layer 50. Therefore, the thickness should be appropriately set in consideration of the above characteristics. In general, Al _x Ga _{1 - x} N is mainly used.

The p-GaN layer 70 is grown at a similar gas atmosphere and temperature as the n-GaN layers 30 and 40 described above, and injects Mg to become p-GaN during GaN growth. However, as is known, injected Mg combined with hydrogen provided by ammonia, which is used as a nitrogen precursor, forms Mg-H. Thus, the deactivated p-type GaN thin film immediately after growth is a heat treatment process such as low energy electron beam irradiation (LEEBI) or high temperature. It must be activated through annealing (Rapid Temperature Annealing, Furnace Annealing, etc.) to obtain p-type characteristics.

After the p-GaN layer 70 is formed, a transparent electrode or the like may be further formed thereon to improve current spreading characteristics.

And, as shown in Figure 2d to form the electrode to use the formed structure as a front emission type element, a vertical structure for forming the electrodes on the upper and lower portions of the structure, respectively, as shown to remove a portion of the structure n The horizontal structure (side current injection method) which exposes -GaN layer 30 to form an electrode is typical. In the illustrated case, the p-GaN layer 70, the p-cladding layer 60, the active layer 50, and the second n-GaN layer of the partial region of the device are exposed so that the n-GaN layer 30 is exposed. 40 is removed to expose the first n-GaN layer 30.

As shown in FIG. 2E, n-electrodes 45 and p-electrodes 80 are formed in portions of the first n-GaN layer 30 and the p-GaN layer 70, respectively.

However, the general side-side light emitting diode structure shown in the drawing has low luminous efficiency because current mainly flows along the side of the mesa structure, which is the shortest distance from the p-electrode 80 to the n-electrode 45. Although a transparent electrode may be formed on the p-GaN layer 70, which is a p-contact, the problem is that the current diffusion in the n-GaN layer 30, which is an n-contact, is difficult to solve, thereby improving efficiency. Incomplete

In addition, such poor current spreading lowers the resistance of electro-static discharge (ESD), which has a close effect on reliability, making the device vulnerable to reverse voltage application or static electricity. Therefore, in the case of expensive LED devices, if the ESD characteristics of the devices themselves are not good, additional configurations such as incorporating a zener diode in a package may be required. However, since the addition of the zener diode causes problems such as lower brightness, increased cost, and increased number of processes, studies to increase the ESD resistance of the device itself have been continuously conducted.

As described above, the conventional general side current injection type light emitting diode has low luminous efficiency because the current flow by the applied voltage is uniformly distributed and is not provided to the entire device, but is concentrated only in a specific region, and the concentration of the current is reverse voltage. There is a problem in that the reliability of the device is lowered by lowering the resistance by static electricity or the like. In order to solve this problem, there is a method of connecting a separate zener diode, but there is a problem in that the process and cost are greatly increased and the light quantity of the device is reduced.

In view of the above problems, the present invention provides a high conductivity material to improve the lateral current spreading characteristics of the n-contact layer, which is a main factor preventing uniform current spreading in the lateral current injection type light emitting diode. The present invention provides a light emitting diode having a current spreading layer and a method of manufacturing the same, which can be formed inside, which can concentrate light in a specific direction, lower driving voltage, and increase ESD resistance while significantly improving side current spreading characteristics. There is this.

In order to achieve the above object, the present invention comprises a first n-contact layer formed of a nitride semiconductor; A current spreading pattern formed on the first n-contact layer or buried in a surface thereof; A second n-contact layer formed on the structure; And an active layer and a p-contact layer sequentially formed on the second n-contact layer.

The current spreading pattern is made of a metal material having a melting point of 900 ℃ or more.

In the above, the current spreading pattern is characterized in that consisting of one of W, Cr, Ti.

The current spreading pattern may be made of one of highly reflective metals including Ag.

The current diffusion pattern has an energy band gap higher than that of metal, and is an oxide conductive layer having a higher melting point than that of metal.

In the above, the oxide conductive layer is characterized in that one of ITO, RuO _x .

In the above, the interface layer for reducing the contact resistance is further formed between the current diffusion layer consisting of the oxide conductive layer and the n-contact layer located below or above.

In addition, the present invention comprises the steps of forming a current diffusion layer pattern on or inside the first n-contact layer; In the forming of the current spreading layer pattern, the method may further include forming a metal having a melting point of 900 ° C. or more after forming a pattern.

In the forming of the current spreading layer pattern, forming a plurality of grooves on a portion of the surface of the first n-contact layer and then selectively embedding Ag or a metal having similar reflectivity and conductivity into the grooves. It is characterized by including.

The forming of the current spreading layer pattern may include forming the current spreading layer pattern by depositing and patterning a conductive oxide having an energy bandgap higher than that of a metal and having a melting point higher than that of the metal.

When described in detail with reference to the accompanying drawings, the present invention as follows.

3 to 5 are cross-sectional views of embodiments of the present invention, in which a current spreading layer is further formed to facilitate lateral current spreading inside an n-contact layer of the side current injection type light emitting diode. Various III-V semiconductors may be used, but the configuration and manufacturing methods will be described using light-emitting diodes formed of nitride semiconductors, in particular, gallium nitride (GaN).

First, FIG. 3 is a diagram illustrating a current spreading pattern of a metal for lateral current diffusion between n-GaN layers 130 and 150 formed on a low temperature buffer layer 120 formed on a substrate 110. 140) is formed further. In addition, the diffusion layer 160, the p-cladding layer 170, and the p-GaN layer 180 are sequentially formed on the n-GaN layer 150 in the same manner as a general LED structure. 190 is positioned, and the n electrode 200 is located on the exposed n-GaN layer 130.

In general, when a voltage is applied to the LED of the side current injection type structure, current is concentrated in the side of the mesa structure formed by removing part of the device mainly by the low side current conductivity of the n-GaN layer. In this case, since the current diffusion pattern 140 is formed in the n-GaN layers 130 and 150 to reinforce the side current conductivity, current flows evenly through the device. Therefore, in this case, the luminance efficiency increases with respect to the voltage applied to the device, and the ESD resistance is also increased because the entire voltage of the device is dissipated and dissipated by reverse voltage or static electricity. And it is a factor that can greatly improve reliability.

3 shows the most basic current spreading pattern structure of the present invention, and also the first n-GaN layer 130 and the second n-GaN layer ( A metal pattern is further formed between the layers 150 and used as the current diffusion pattern 140.

However, any metal may not be used as the current spreading pattern 140 because the n-GaN layer 140 formed on the current spreading pattern 140 must be grown at a high temperature of 900 ° C. or higher. The current spreading pattern 140 applicable to the structure shown in FIG. 3 should have a metal material having a melting point of 900 ° C. or higher. Such a material having high melting point and high conductivity to improve the side conductivity is typically W, Cr, Ti and the like, it is preferable to use one of these.

4 is a cross-sectional view of another embodiment of the present invention, in which the characteristics and materials of the metal used as the current diffusion pattern 140 are different from those shown in FIG. 3. That is, since the current diffusion pattern applied in the manner shown in FIG. 3 can absorb the generated light although the process is simple, the material of the current diffusion pattern 141 used in the structure shown in FIG. Like this, a metal with high reflectivity and high current conductivity is used. When Ag is applied to the current diffusion pattern 141 because of high reflectivity, the Ag may reflect additional light generated from the active layer formed on the upper surface thereof, thereby increasing an additional brightness of the front direction. However, metals having high reflectivity and high conductivity, such as Ag, are deposited directly on the first n-GaN layer 130 because the melting point (961.9 ° C.) is lower than 1000 ° C., which is generally the temperature used when forming a GaN layer. It is difficult to apply by the post-patterning method. Accordingly, as illustrated, the current spreading pattern 141 is formed in the manner of being embedded in the surface of the first n-GaN layer 130. In addition, the second n-GaN layers 151 and 152 formed on the upper portion thereof may grow or vaporize when the metal material used as the current spreading pattern 141 is also grown at a high temperature of 1000 ° C. or higher. The low temperature portion 151 formed at a temperature and the upper portion is formed of the remaining portion 152 formed at a general high temperature.

FIG. 5 is a cross-sectional view of another embodiment of the present invention. In the case where the light emitted to the rear surface is different from the case illustrated in FIG. 3 or 4, the current is reduced to reduce the light loss caused by the current diffusion pattern 142. The diffusion pattern 142 is formed of an oxide conductive layer having a low light absorption rate. The oxide conductive layer has a larger energy band gap than metal and uses ITO or RuO _x having a high melting point to withstand high temperatures of 900 ° C. or more. However, the current diffusion pattern 142 made of the oxide conductive layer is not good in ohmic characteristics with the GaN layers, it is preferable that the interface layer 135, 145 is further formed on the lower and upper portions, respectively. At this time, each of the interfacial layer has a composition of InxGa (1-x) N (0 ≦ x <1) to reduce contact resistance between GaN on one side and the oxide conductive layer on the other side.

By varying the structure of the n-contact layer in the basic side current injection type light emitting diode structure as described above, the current spreading characteristics of the weak n-contact layer can be greatly improved. The structures and manufacturing methods are different according to the materials and characteristics of the respective current diffusion patterns described above. Hereinafter, specific manufacturing processes and features of the respective embodiments will be described with reference to the accompanying drawings.

First, FIGS. 6A to 6D are procedure cross-sectional views for explaining important parts of processes for fabricating the structure of the exemplary embodiment of the present invention shown in FIG. 3, and are shown on the first n-GaN layer 130 as shown. A method of forming the direct current spreading pattern 140 is shown.

As shown in FIG. 6A, the buffer layer 120 is formed at a low temperature (400 ° C. to 600 ° C.) without doping to eliminate lattice mismatch on a substrate 110 such as silicon or sapphire, and Si, an n-type impurity, is formed thereon. And the like to form the first n-GaN layer 130 by growing at a high temperature (900 ° C. or higher, generally 1000 ° C. or higher). As the manufacturing method of the low temperature buffer layer 120 or the first n-GaN layer 130, a low temperature / high temperature growth method by MOCVD method is conventionally used. Recently, in order to solve the side effects of the formation of the buffer layer 120 due to lattice mismatch, GaN may be manufactured and applied directly in the form of a substrate, and the low temperature buffer layer 120 has also been tested with various kinds of materials. However, in the present invention, the kind of the low temperature buffer layer 120 or the kind of the substrate 100 is irrelevant to the characteristics of the present invention, and only all kinds of growing the first n-contact layer 130 by the epitaxial growth method. It can be applied to all of the light emitting diode manufacturing method. The first n-GaN layer 130 is preferably formed to a thickness of 1 ~ 10㎛.

As shown in FIG. 6B, a metal film is formed and patterned to form a metal current diffusion pattern 140 on the first n-GaN layer 130. The thickness of the metal current spreading pattern 140 is about 10 to 10,000 Å. Since the metal film should be exposed to the growth temperature of the subsequent n-GaN layer, the metal film should be a metal having a high melting point that does not melt even at a temperature of 900 ° C. or higher, and should be easy to form and pattern through a thin film process. The metal current diffusion pattern 140 may be formed by depositing the metal on the first n-GaN layer 130 by sputtering or e-beam deposition, and patterning the same by using a photo process. Can be.

At this time, the pattern shape of the formed metal current diffusion pattern 140 may vary greatly, but the subsequent growth of the second n-GaN layer may be exposed because the pattern 140 is not formed. Since the pattern is implemented based on (130), the pattern is roughly defined such that each side has a length of 0.1 to 10 μm in the case of a rectangle, and a diameter of 0.1 to 10 μm in the case of a circle, and a polygon. The longest width is preferably defined to have a length of the same region, and the exposure width of the first n-GaN layer 130 exposed between the respective patterns is also preferably 0.1 to 10 μm.

As shown in FIG. 6C, a second n-GaN layer 150 is grown on the formed metal current diffusion pattern 140 and the exposed first n-GaN layer 130. The second n-GaN layer 150 is also grown on the first n-GaN layer 130 at a high temperature (900 ° C. or more) by MOCVD and grows laterally by controlling process conditions. The second n-GaN layer 150 is also formed in the upper region of the metal current spreading pattern 140. Specifically, the second n-GaN layer 150 may be formed of a GaN, In _x Ga _(1-x) N (x> 0) or AlGa _(1-y) N (y <1) layer. As for thickness, about 0.1-10 micrometers is suitable.

As shown in FIG. 6D, the active layer 160, the p-cladding layer 170, and the p-GaN layer 180 are sequentially formed on the second n-GaN layer 150 formed according to a general light emitting diode manufacturing method. ). Specific structures, formation methods, and compositions of the respective layers are the same as those of various conventional methods of manufacturing light emitting diodes, and the processes after the formation of the active layer 160 are not directly related to the present invention, and thus will be omitted for clarity.

Since the current diffusion pattern 140 of the exemplary embodiment of the present invention described above is formed using a metal material having a high melting point, the process is relatively simple, as can be seen through the manufacturing process described above. However, the structure improves current spreading characteristics and shows higher light efficiency than the conventional art. However, since the metal used as the current spreading pattern 140 is a metal having a high melting point, the photon emitted from the active layer 160 has a low reflectivity. Can absorb some.

Therefore, in the structure in which the highly reflective metal is applied to the current spreading pattern as shown in FIG. 4, the parts to be noted and the features to be described will be explained through the procedure cross-sectional views shown in FIGS. 7A to 7D. .

First, the structure shown in FIG. 7A is formed through the same process as FIG. 6A described above. That is, the buffer film 120 is formed at a low temperature, and the first n-GaN layer 130 is grown to a thickness of 1 to 10 μm at a high temperature thereon.

As shown in FIG. 7B, a portion of the surface of the formed first n-GaN layer 130 is etched to form grooves having a groove shape in the region where the current diffusion pattern 141 is to be formed, and the grooves The metal current diffusion pattern 141 is embedded in the first n-GaN layer 130 by filling and blading a metal having high reflectivity even though the melting point is low, such as Ag. This is to prevent the pattern shape from being changed by melting the metal having a melting point of less than 1000 ° C., such as Ag, in the subsequent formation of the second n-GaN layer at a high temperature. Therefore, the metal that can be used as the current diffusion pattern 141 should be a metal having high reflectivity and conductivity even though the melting point is low, and the boiling point should be higher than the GaN layer growth temperature. In this case, the metal current diffusion pattern 141 may vary greatly, but the subsequent growth of the second n-GaN layer is based on the first n-GaN layer 130 exposed between the patterns 141. In general, the pattern is defined to have a length of 0.1 ~ 10㎛ each side in the case of a rectangle, a diameter is defined to have a length of 0.1 ~ 10㎛ in the case of a circle, the longest width in the case of a polygon It is preferable to define the length of the same region, and the exposure width of the first n-GaN layer 130 exposed between the respective patterns is also preferably 0.1 to 10 μm.

As shown in FIG. 7C, second n-GaN layers 151 and 152 are grown on the formed metal current diffusion pattern 141 and the exposed first n-GaN layer 130. In this case, as shown in the drawing, the second n-GaN layers 151 and 152 are preferably formed to be divided into two layers, and the second n-GaN layer 151 formed at a lower portion thereof is 800 ° C. or less. Growth at low temperature prevents vaporization of the formed low melting point metal current spreading pattern 141 while protecting the metal current spreading pattern 141 from subsequent high temperature processes. The second n-GaN layer 152 formed thereon is formed by growing in a general high temperature process of 900 ° C or more. Since the second n-GaN layer 151 also grows laterally by adjusting process conditions, the second n-GaN layer 151 is also formed in the upper region of the formed metal current diffusion pattern 141. In detail, the second n-GaN layers 151 and 152 may be formed of GaN, In _x Ga _(1-x) N (x> 0), or AlGa _(1-y) N (y <1) layers. As for the thickness, about 0.1-10 micrometers is suitable. Among them, the thickness of the second n-GaN layer 151 formed at low temperature is in the range of 0.01 to 10 μm.

Of course, if the metal material used has high reflectivity and a high vaporization point, a low temperature protective GaN layer such as the second n-GaN layer 151 is omitted and n grown in a high temperature process such as the second n-GaN layer 152. A -GaN layer can also be applied directly.

As shown in FIG. 7D, the active layer 160, the p-cladding layer 170, and the p-GaN layer are sequentially formed on the formed second n-GaN layers 151 and 152 according to a general light emitting diode manufacturing method. Form 180.

Since the current diffusion pattern 141 of another embodiment of the present invention described above is formed by using a metal material having a relatively low melting point but high reflectivity, the process of FIG. 3 described above may be manufactured as described above. 6a to 6d, the current diffusion pattern 141 has a high reflectivity, thereby reflecting the front surface of the active layer 160 without absorbing the photons emitted from the active layer 160, thereby increasing the front luminance. . That is, by improving current spreading characteristics, the amount of emitted light with respect to the applied voltage is increased, and the light is concentrated on the entire surface by the current spreading pattern 141, thereby increasing luminance in a target direction.

3 and 4 are suitable for a structure for using light emitted to the front surface where the electrode is formed, but when using the light emitted to the back surface where the sapphire is formed, the current diffusion pattern is located in the light emission path. Therefore, application becomes difficult. In particular, in the case of configuring a recently applied flip chip bonding type light emitting diode, since the light efficiency is improved by using light emitted in a direction in which no electrode is formed, the current diffusion pattern absorbs light to apply in this case. It must not be reflected or reflected. That is, a transparent current spreading pattern is required, which means that the structure of FIG. 5, which is another embodiment of the present invention, is required.

8A to 8D are cross-sectional views for manufacturing the structure shown in FIG. 5 and show a manufacturing method in the case of using the oxide conductive layer in a transparent current diffusion pattern that does not absorb or reflect light as shown.

First, as shown in FIG. 8A, the method of growing up to the first n-GaN layer 130 is basically the same as described with reference to FIGS. 6A and 7A.

In addition, as shown in FIG. 8B, in order to reduce contact resistance by improving an ohmic characteristic between the current diffusion pattern following the first n-GaN layer 130 formed above and the first n-GaN layer 130. In _x Ga _(1-x) N (0 ≦ x <1) is formed in the first interface layer 135 to a thickness of 10 μm to 10 μm. This is not essential but is preferably applied to maintain the device's properties.

As shown in FIG. 8C, a conductive oxide is deposited on the first interface layer 135 by sputtering or two-beam deposition, and patterned to form a current diffusion pattern 142. In _x Ga _(1-x) N (0 ≦ x <1) was formed in the second interface layer 145 to have a thickness of 10 μm to 10 μm in order to reduce contact resistance with the n-GaN layer, and then the second layer was formed thereon. The n-GaN layer 153 is grown and formed. Again, although the second interface layer 145 is not essential, application is desirable to maintain device characteristics. In order to prevent the second n-GaN layer 153 from melting the current diffusion pattern 142 made of the conductive oxide, the growth temperature may be controlled in a range of 600 to 1200 ° C., and GaN, In _x Ga _{(1-x )} N, Al _y Ga _(1-y) N (0 <x, y <1) layer is formed by growing about 0.1 ~ 10㎛.

Since the conductive oxide used as the current spreading pattern 142 must transmit light without absorbing light, the energy band gap must be larger than that of the metal and must be higher than the metal. In general, since the conductive oxide has a higher melting point than a general metal, the second n-GaN layer 153 may be grown at a high temperature. ITO, RuO _x and the like can be applied as a suitable material as such a conductive oxide, the height is formed to be 10 ~ 10000Å thickness. In this case, the oxide current diffusion pattern 142 may vary greatly, but subsequent growth of the second n-GaN layer 153 or the second interface layer 145 may be exposed between the patterns 142. Since the pattern is implemented based on the first n-GaN layer 130 or the first interfacial layer 135, the pattern is defined to have a length of 0.1 to 10 μm in the case of a rectangle, and a diameter of 0.1 to a circle. It is defined to have a length of ˜10 μm, and in the case of polygons, the longest width is preferably defined to have the length of the same region, and the first n-GaN layer 130 exposed between the respective patterns or The exposure width of the first interfacial layer 135 is also preferably 0.1 to 10 μm.

As shown in FIG. 8D, the active layer 160, the p-cladding layer 170, and the p-GaN layer 180 are sequentially formed on the second n-GaN layer 153 formed according to a general light emitting diode manufacturing method. ).

In addition to the above-described three embodiments, more various manufacturing processes and structures may be applied. However, the present invention is directed to lateral current spreading inside an n-contact layer having poor side current spreading characteristics among side current injection type LED structures. Note that it encompasses both a structure that further includes a helpful current spreading pattern and the processes for making it.

The current spreading patterns may have various pattern shapes, some of which are illustrated in FIG. 9. The above embodiment shows patterns that can be applied to the structure of FIG. 3 and may be equally applied to the structure of FIGS. 4 to 5.

FIG. 9A illustrates a case in which a current diffusion pattern 140 having a stripe shape is formed on the first n-GaN layer 130. The stripe pattern has a width of 0.1 to 10 μm, and is exposed between the stripe patterns. It is preferable that the width of the first n-GaN layer 130 is also 0.1 to 10 μm.

FIG. 9B shows a rectangular current spreading pattern, FIG. 9C shows a polygonal current spreading pattern, and FIG. 9D shows a circular current spreading pattern. In this case, the width of each pattern is 0.1 to 10 μm as described above, and the width of the first n-GaN layer 130 exposed between the patterns is also 0.1 to 10 μm.

Therefore, it is noted that the present invention is not limited to the structure and shape of the specific current spreading patterns because various structures of the current spreading patterns may be interpreted as a concept encompassed by the present invention.

As described above, the light emitting diode of the present invention and a method of manufacturing the same have a high conductivity material so as to improve the lateral current spreading characteristics of the n-contact layer, which is a main factor preventing the uniform current spreading in the lateral current injection type light emitting diodes. By forming the inside of the contact layer, the side current diffusion characteristics can be improved, and the high conductivity material can also serve to enhance light efficiency, such as focusing or transmitting light in a specific direction, thereby increasing the driving voltage. It has an excellent effect of lowering and increasing ESD immunity and brightness. In particular, increased ESD immunity has the effect of significantly increasing device lifetime and reliability.

Claims (34)

A first n-contact layer formed of a nitride semiconductor; A current diffusion pattern formed on or above the first n-contact layer; A second n-contact layer formed on the structure; A light emitting diode having a current diffusion layer, characterized in that it comprises an active layer and a p-contact layer formed in turn on the second n-contact layer. The current diffusion layer of claim 1, wherein the first n-contact layer and the second n-contact layer are GaN containing silicon as an impurity, and the p-contact layer is GaN containing magnesium as an impurity. A light emitting diode having a. The light emitting diode of claim 1, wherein the first n-contact layer is 1 to 10 μm thick. The light emitting diode of claim 1, wherein the current diffusion pattern is made of a metal material having a melting point of 900 ° C or higher. 5. The light emitting diode of claim 4, wherein the current spreading pattern comprises one of W, Cr, and Ti. The light emitting diode of claim 1, wherein the current diffusion pattern is made of one of highly reflective metals including Ag. 7. The light emitting diode of claim 6, wherein the second n-contact layer comprises a portion grown at a low temperature of 800 ° C or lower and a portion grown at a temperature of 800 ° C or higher. The light emitting device of claim 7, wherein the second n-contact layer has a thickness of 0.1 to 10 μm, and the portion grown at a low temperature has a thickness of 0.01 to 10 μm. diode. The light emitting diode of claim 1, wherein the current diffusion pattern is an oxide conductive layer having a higher energy band gap than a metal and having a higher melting point than the metal. 10. The light emitting diode of claim 9, wherein the oxide conductive layer is one of ITO and RuO _x . 10. The light emitting diode of claim 9, wherein an interface layer for reducing contact resistance is further formed between the current spreading layer made of the oxide conductive layer and the n-contact layer disposed below or at the top thereof. 12. The light emitting diode having a current spreading layer according to claim 11, wherein the interface layer is formed of In _x Ga _(1-x) N (0≤x <1) in a thickness of 10 m to 10 m. The light emitting diode having a current spreading layer according to claim 1, wherein the current spreading pattern has a thickness of 10 to 10000 mA. The light emitting diode of claim 1, wherein the current spreading pattern has a stripe, a circular shape, or a polygonal shape when viewed from the top. The light emitting diode of claim 1, wherein the current spreading pattern has a width of 0.1 to 10 μm, and a width of the separation region between the current spreading patterns is 0.1 to 10 μm. The method of claim 1, wherein the second n-contact layer is formed of a GaN, In _x Ga _(1-x) N (x> 0) or AlGa _(1-y) N (y <1) layer. A light emitting diode having a current spreading layer. The light emitting diode of claim 1, wherein the second n-contact layer has a thickness of 0.1 to 10 μm. Growing a first n-contact layer on a substrate having a buffer layer or a substrate having a homogeneous lattice structure; Forming a current spreading layer pattern over or within the first n-contact layer; Growing a second n-contact layer over the structure; And forming an active layer and a p-contact layer on top of the second n-contact layer in sequence. The method of claim 18, wherein the first n-contact layer and the second n-contact layer are formed by including Si as an impurity while growing a GaN-based nitride semiconductor by a MOVCD method, and the p-contact layer is formed of GaN by MOCVD. A method of manufacturing a light emitting diode having a current spreading layer, wherein the nitride semiconductor is grown and formed by including Mg as an impurity. 19. The method of claim 18, wherein the first n-contact layer is grown to a thickness of 1 to 10 mu m. 19. The method of claim 18, wherein the forming of the current spreading layer pattern further comprises: forming a metal having a melting point of 900 DEG C or higher and then patterning the metal to form the current spreading layer pattern. The method of claim 21, wherein the current spreading layer pattern comprises forming one of W, Cr, and Ti. The method of claim 18, wherein in the forming of the current diffusion layer pattern, after forming a plurality of grooves on a portion of the surface of the first n-contact layer, Ag or a metal having a similar reflectivity and conductivity to the grooves is formed. A method of manufacturing a light emitting diode having a current spreading layer comprising the step of selectively buried. 24. The method of claim 23, wherein the metal forming the current spreading layer pattern is a metal which is not vaporized at 800 ° C or lower. The method of claim 23, wherein the forming of the second n-contact layer comprises: growing a portion of the second n-contact layer at a low temperature of 800 ° C. or lower on the exposed first n-contact layer, Growing a remaining portion of the second n-contact layer at a high temperature of 800 ° C. or higher. 26. The method of claim 25, wherein the thickness of the second n-contact layer is formed to a thickness of 0.1 ~ 10㎛, the current diffusion layer, characterized in that the thickness of a portion formed at a portion of the low temperature is 0.01 ~ 10㎛ Light emitting diode manufacturing method provided. The method of claim 18, wherein the forming of the current spreading layer pattern comprises forming a current spreading layer pattern by depositing and patterning a conductive oxide having a higher energy band gap than a metal and having a higher melting point than the metal. A light emitting diode manufacturing method having a current diffusion layer. 28. The method of claim 27, wherein forming the conductive oxide comprises forming one of ITO and RuO _x using sputtering or two-beam deposition. 28. The method of claim 27, further comprising forming an interface layer for reducing contact resistance before or after the current diffusion layer pattern is formed. One light emitting diode manufacturing method. 30. The method of claim 29, wherein In _x Ga _(1-x) N (0≤x <1) is formed to have a thickness of 10 Å to 10 탆 to form a film with the interfacial layer. . 19. The method of claim 18, wherein in the forming of the current spreading pattern, the current spreading pattern is formed by depositing a thickness of 10 to 10000 mA. 19. The light emitting device of claim 18, wherein in the forming of the current spreading pattern, the current spreading pattern comprises patterning the stripe to have a stripe, a circular shape or a polygonal shape when viewed from the top. Diode manufacturing method. The method of claim 18, wherein in the forming of the current spreading pattern, the current spreading pattern has a width of about 0.1 μm to about 10 μm, and a width of a spaced area between the current spreading patterns is about 0.1 μm to about 10 μm. The light emitting diode manufacturing method provided with the current spreading layer characterized by the above-mentioned. 19. The method of claim 18, wherein in the growing of the second n-contact layer, the second n-contact layer is formed of GaN, In _x Ga _(1-x) N (x> 0) or AlGa using MOCVD. _{(1-y) A} method of manufacturing a light emitting diode having a current diffusion layer, comprising growing N (y <1) to a temperature of 600 to 1200 ° C. at a thickness of 0.1 to 10 μm.

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