KR20120126496A - Light emitting diode and method for fabricating the same - Google Patents

Abstract

PURPOSE: A light emitting diode and a manufacturing method thereof are provided to enhance recombination efficiency of an electron and an electric hole by forming an electric broking layer between an active layer and a second conductive semiconductor layer. CONSTITUTION: A semiconductor structure layer(120) is formed on one surface of a growth substrate(110). The semiconductor structure layer comprises a conductive semiconductor layer, an active layer, and a second conductive semiconductor layer(126). A first reflective structure pattern(140) is formed on the second conductive semiconductor layer. A contact layer(150) contacts the second conductive semiconductor layer through a first open area of the first reflective structure pattern. A second reflective structure pattern(160) comprises a second open area which exposes the surface of the contact layer.

Description

LIGHT EMITTING DIODE AND METHOD FOR FABRICATING THE SAME

The present invention relates to a light emitting diode and a method of manufacturing the same.

The light emitting diode is basically a PN junction diode which is a junction between a P-type semiconductor and an N-type semiconductor.

When the light emitting diode is bonded to the P-type semiconductor and the N-type semiconductor, and a current is applied by applying a voltage to the P-type semiconductor and the N-type semiconductor, holes of the P-type semiconductor move toward the N-type semiconductor, and On the contrary, electrons of the N-type semiconductor move toward the P-type semiconductor, and the electrons and holes move to the PN junction.

The electrons moved to the PN junction are combined with holes as they fall from the conduction band to the valence band. At this time, the energy difference corresponding to the height difference, that is, the energy difference of the conduction band and the home appliance, is emitted, the energy is emitted in the form of light.

Such a light emitting diode is a semiconductor device that emits light and is characterized by eco-friendliness, low voltage, long lifespan, and low cost. In the past, light emitting diodes have been applied to simple information display such as display lamps and numbers. In particular, with the development of information display technology and semiconductor technology, it has been used in various fields such as display fields, automobile headlamps and projectors.

In addition, the light emitting diode is expected to be applied to a lighting device in place of a white light source such as a fluorescent lamp because it can implement a white light having a high color rendering.

The light emitting diode forms a plurality of semiconductor layers including an N-type semiconductor layer, an active layer, and a P-type semiconductor layer on a growth substrate, and performs mesa etching to expose a portion of the N-type semiconductor layer. The contact layer, the reflective layer, and the P-side pad may be formed on the layer, and the N-type pad of the N-type semiconductor layer may be formed to manufacture a flip chip type light emitting diode.

However, conventional light emitting diodes, in particular flip chip type light emitting diodes, transmit light smoothly when the light generated from the active layer proceeds to the growth substrate, while light traveling toward the P-type semiconductor layer is reflected by the reflective layer. By passing through the plurality of layers to advance to the growth substrate side, some light is absorbed or the amount of light extracted by being absorbed through total reflection is lowered.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting diode and a method of manufacturing the same, which minimize the light disappearing by absorption or total reflection of light traveling toward the P-type semiconductor layer.

In order to achieve the above object, according to an aspect of the present invention, a semiconductor structure layer comprising a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer; A first reflective structure pattern provided on the second conductive semiconductor layer and having a plurality of first open regions exposing a surface of the second conductive semiconductor layer; A contact layer provided on the second conductive semiconductor layer provided with the first reflective structure pattern and in contact with the second conductive semiconductor layer through the first open region; And a plurality of second open regions provided on the contact layer and exposing a surface of the contact layer, the second reflecting patterns covering at least the first open regions.

The size of the second reflective structure pattern may be equal to or larger than the size of the first open region so that light passing through the first open region is reflected by the second reflective structure pattern.

The first reflective structure pattern or the second reflective structure pattern may include a distributed bragg reflector (DBR).

Each of the first reflective structure pattern or the second reflective structure pattern is repeatedly stacked at least once with at least two layers having different refractive indices, and each layer is λ / 4n (where λ is a wavelength of light and n is a medium). It may be a thickness that is an integer multiple of the refractive index of).

Each of the first reflective structure pattern or the second reflective structure pattern has a low refractive index layer and a high refractive index layer repeatedly stacked at least once, and the low refractive index layer is an SiO ₂ layer or an Al ₂ O ₃ layer, and the high refractive index The layer may be an HfO ₂ layer, a TiO ₂ layer, an Nb ₂ O ₅ layer or a Si ₃ N ₄ layer.

The light emitting diode includes a growth substrate, and the semiconductor structure layer is provided on one surface of the growth substrate, wherein the second conductive semiconductor layer and the active layer are mesa-etched to expose a portion of the first conductive semiconductor layer. Can be provided.

The light emitting diode may include a first electrode pad provided on an exposed portion of the first conductive semiconductor layer; And a second electrode pad in electrical contact with the contact layer exposed through the second open region.

The display device may further include a reflective layer provided between the second reflective structure pattern and the second electrode pad, wherein the reflective layer may contact the contact layer exposed through the second open area.

The other surface of the growth substrate may include a patterned sapphire substrate (PSS) pattern.

The light emitting diode may further include a conductive substrate, and the conductive substrate may be provided on the second reflective structure pattern.

The light emitting diode may further include an adhesive layer provided between the conductive substrate and the second reflective structure pattern, and the conductive substrate and the second reflective structure pattern may be coupled by the adhesive layer.

The light emitting diode may include a first electrode pad provided on the first conductive semiconductor layer; And a second electrode pad provided on the conductive substrate.

The light emitting diode may further include irregularities provided on a surface of the first conductive semiconductor layer on which the first electrode pad is not formed.

The first open area has a larger area of the open area than the first open area where the first open area is located far from the first electrode pad on a plane compared to the first open area located close to the first electrode pad. Can be large.

In order to achieve the above object, according to another aspect of the invention, preparing a growth substrate; Forming a semiconductor structure layer including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer, a portion of which is exposed on one surface of the growth substrate; Forming a first reflective structure pattern having a plurality of first open regions on the second conductive semiconductor layer; Forming a contact layer on the first reflective structure pattern, the contact layer being in contact with the second conductive semiconductor layer through the first open region; And forming a second reflective structure pattern formed on the contact layer, wherein the second open region exposes a surface of the contact layer and covers at least the first open regions. A method is provided.

The light emitting diode manufacturing method includes: forming a first electrode pad on the first conductive semiconductor layer, and forming a first electrode pad on the second reflective structure pattern to electrically contact the contact layer through the second open regions. The method may further include forming an electrode pad.

Prior to forming the first electrode pad and the second electrode pad, the method may further include forming a reflective layer on the second reflective structure pattern.

After forming the first electrode pad and the second electrode pad, the method may further include forming a PSS pattern on the other surface of the growth substrate.

The light emitting diode manufacturing method comprises the steps of preparing a conductive substrate; Forming an adhesive layer on the second reflective structure pattern; Bonding the conductive substrate and the growth substrate using the adhesive layer; And separating the growth substrate from the first conductive semiconductor layer.

Prior to forming the adhesive layer, the method may further include forming a reflective layer on the second reflective structure pattern.

The method may further include forming a first electrode pad on the first conductive semiconductor layer and forming a second electrode pad on the conductive substrate.

Before or after forming the first electrode pad on the first conductive semiconductor layer, the step of forming irregularities on the other surface except for the surface of the first conductive semiconductor layer provided with the first electrode pad It may include.

According to the present invention, there is an effect of providing a light emitting diode having a high luminous efficiency and a method of manufacturing the same by minimizing light extinguished by absorption or total reflection of light traveling toward the P-type semiconductor layer.

1 is a cross-sectional view showing a light emitting diode according to an embodiment of the present invention.
2 is a cross-sectional view showing a light emitting diode according to another embodiment of the present invention.
3 to 6 are cross-sectional views illustrating a method of manufacturing a light emitting diode according to an embodiment of the present invention.
7 to 9 are cross-sectional views illustrating a method of manufacturing a light emitting diode according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a light emitting diode according to an embodiment of the present invention.

Referring to FIG. 1, a light emitting diode 100 according to an embodiment of the present invention includes a growth substrate 110, a semiconductor structure layer 120, a first electrode pad 130, and a first reflective structure pattern 140. ), A contact layer 150, a second reflective structure pattern 160, a second electrode pad 170, and reflective layers 182 and 184.

The growth substrate 110 may be any substrate capable of growing semiconductor layers. The growth substrate 110 may be a sapphire substrate, a SiC substrate, a spinel substrate, or the like, and preferably, a sapphire substrate.

The growth substrate 110 may include the semiconductor structure layer 120 on one surface thereof, and a PSS pattern 112 on the other surface thereof.

The PSS pattern 112 is light that is totally reflected inside the growth substrate 110 and lost when the light generated by the semiconductor structure layer 120 is emitted to the outside through the other surface of the growth substrate 110. It serves to reduce. That is, the PSS pattern 112 has a boundary surface when the light passes between two media having different refractive indices, that is, when the light passes from the growth substrate 110 to the outside (ie, in the air). That is, reflection and transmission occur at the growth substrate 110 and the external interface), and the reflection is minimized to increase the amount of light emitted to the outside through the growth substrate 110 to increase luminous efficiency.

The PSS pattern 112 may be formed of hemispherical protrusions on one surface of the growth substrate 110 as shown in FIG. 1, but the shape of the PSS pattern 112 is not limited thereto. It may be provided in a polygonal pyramid shape and the like.

The light emitting diode 100 may further include a buffer layer 114 between the growth substrate 110 and the semiconductor structure layer 120. That is, the buffer layer 114 may be provided on one surface of the growth substrate 110.

The buffer layer 114 may be provided to mitigate lattice mismatch between the growth substrate 110 and the first conductive semiconductor layer 122 of the semiconductor structure layer 120. In addition, the buffer layer 114 may be formed of a single layer or a plurality of layers, and when formed of a plurality of layers, the buffer layer 114 may be formed of a low temperature buffer layer and a high temperature buffer layer.

The semiconductor structure layer 120 may be provided on one surface of the growth substrate 110, preferably on the buffer layer 140. The semiconductor structure layer 120 may include a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126. In addition, the semiconductor structure layer 120 may further include a superlattice layer (not shown) or an electron breaking layer (not shown). In this case, the semiconductor structure layer 120 may be omitted except for the active layer 124.

The semiconductor structure layer 120 may include a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126 stacked on at least one surface of the growth substrate 110. At least a portion of the second conductive semiconductor layer 126 and the active layer 124 may be mesa-etched to expose a portion of the first conductive semiconductor layer 122.

The first conductive semiconductor layer 122 may be a III-N-based compound semiconductor doped with a first conductive impurity, for example, an N-type impurity, such as an (Al, Ga, In) N-based Group III nitride semiconductor layer. have. The first conductive semiconductor layer 122 may be a GaN layer doped with N-type impurities, that is, an N-GaN layer. In addition, when the first conductive semiconductor layer 122 is formed of a single layer or multiple layers, for example, the first conductive semiconductor layer 122 is formed of multiple layers, the first conductive semiconductor layer 122 may have a superlattice structure.

The active layer 124 may be formed of a III-N based compound semiconductor, for example, an (Al, Ga, In) N semiconductor layer, and the active layer 124 may be formed of a single layer or a plurality of layers. In addition, the active layer 124 may have a single quantum well structure including one well layer (not shown), or a multi quantum well having a structure in which a well layer (not shown) and a barrier layer (not shown) are alternately stacked. It may be provided in a structure. In this case, the well layer (not shown) or the barrier layer (not shown) may be formed of a superlattice structure, respectively or both.

The second conductive semiconductor layer 126 may be a III-N-based compound semiconductor doped with a second conductive impurity, such as a P-type impurity, such as (Al, In, Ga) N-based Group III nitride semiconductor. The second conductive semiconductor layer 126 may be a GaN layer doped with P-type impurities, that is, a P-GaN layer. In addition, the second conductive semiconductor layer 126 may be formed of a single layer or multiple layers. For example, the second conductive semiconductor layer 126 may have a superlattice structure.

The superlattice layer (not shown) may be provided between the first conductive semiconductor layer 122 and the active layer 124, and may be a III-N-based compound semiconductor, for example, an (Al, Ga, In) N semiconductor layer. The plurality of layers, for example, an InN layer and an InGaN layer, may be repeatedly stacked, and the superlattice layer (not shown) may be provided at a position formed before the active layer 124, thereby providing the active layer ( 124 to prevent the transfer of dislocations or defects, etc., to mitigate the formation of dislocations or defects of the active layer 124 and to serve to improve the crystallinity of the active layer 124. can do.

The electron breaking layer (not shown) may be provided between the active layer 124 and the second conductive semiconductor layer 126, and may be provided to increase recombination efficiency of electrons and holes, and have a relatively wide band gap. It may be provided with a material having. The electron breaking layer (not shown) may be formed of a (Al, In, Ga) N-based group III nitride semiconductor, and may be formed of a P-AlGaN layer doped with Mg.

The first electrode pad 130 may be provided on the exposed first conductive semiconductor layer 122. The first electrode pad 130 may be formed of a single layer or a plurality of layers, and the layers may include Ni, Cr, Ti, Al, Ag, Au, or a compound thereof. The first reflection layer 182 may be provided between the first electrode pad 130 and the first conductive semiconductor layer 122. The first reflective layer 182 between the first electrode pad 130 and the first conductive semiconductor layer 122 may be omitted.

The first reflective structure pattern 140 may be provided on the semiconductor structure layer 120, preferably on the second conductive semiconductor 126. The first reflective structure pattern 140 may include a plurality of first open regions 142 exposing a surface of the second conductive semiconductor layer 126 of the semiconductor structure layer 120.

As shown in FIG. 1, the first reflective structure pattern 140 has the light propagated toward the second conductive semiconductor layer 126 among the light generated by the active layer 124 of the semiconductor structure layer 120. Reflect the light toward the growth substrate 110 to increase the amount of light 190 extracted toward the growth substrate 110, that is, to increase the light emitting efficiency of the light emitting diode 100.

Although not shown in detail in FIG. 1, the first reflective structure pattern 140 may have a structure in which at least two layers having different refractive indices are repeatedly stacked at least once. That is, the first reflective structure pattern 140 may include a distributed bragg reflector (DBR).

The first reflective structure pattern 140 may have a structure in which a low refractive index layer and a high refractive index layer are repeatedly stacked a plurality of times. In this case, the low refractive index layer and the high refractive index layer is relative to the absolute refractive index, not divided into a numerical value, the low refractive index layer means a layer made of a material having a relatively low refractive index than the high refractive index layer, The refractive index layer refers to a layer made of a material having a higher refractive index than the low refractive index layer. In this case, the low refractive index layer may be composed of SiO ₂ layer or Al ₂ O ₃ layer, the high refractive index layer is HfO ₂ layer, TiO ₂ layer, Nb ₂ O ₅ layer, Ta ₂ O ₃ or Si ₃ N ₄ layer Can be made.

Each of the layers constituting the first reflective structure pattern 140 may have a thickness that is an integer multiple of λ / 4n (where λ is a wavelength of light and n is a refractive index of a medium). For example, when any one of the layers constituting the first reflective structure pattern 140 is made of SiO ₂ having a refractive index of 1.4 and the wavelength of light to be reflected is 560 nm, the thickness is 560 nm / (4 * 1.4). That is, an integer multiple of 100 nm, that is, 100 nm, 200 nm, may be provided with a thickness of 300 nm, etc., the first reflective structure pattern 140 may be provided with a total thickness of 3000 Å to 10,000 Å thickness. Therefore, the first reflective structure pattern 140 reflects the desired light by controlling the thickness of the layer constituting the first reflective structure pattern 140 or made of a material having a different refractive index according to the wavelength of light to be reflected. Can be. In addition, the first reflective structure pattern 140 may reflect light of a wide range of wavelengths by varying the thickness of the layer constituting the first reflective structure pattern 140 or the refractive index of the material constituting the layer.

As described above, the first reflective structure pattern 140 includes a low refractive index layer and a high refractive index layer, and these two layers are HfO ₂ / SiO ₂ , Ta ₂ O ₅ / SiO ₂ , and TiO ₂ / SiO, respectively. _{In the case of 2} or Nb ₂ O ₅ / SiO ₂ , as shown in Table 1, the first reflective structure pattern 140 may reflect light of different wavelength bands according to the material of the low refractive index layer and the high refractive index layer. It can be seen that the reflectance is also different. In this case, 'number of layers' in Table 1 means the number of repeated layers of the low refractive index layer and the high refractive index layer, 'thickness' means the total thickness, and 'number of layers' and 'thickness' are the first The material constituting the reflective structure pattern 140 refers to the number and thickness of layers capable of most efficiently reflecting light of a desired wavelength band.

Low Refractive Index Layer / High Refractive Index Layer Wavelength reflectivity Number of floors thickness HfO ₂ / SiO ₂ 260 ~ 300nm 100% 20 to 30 6000 to 7000 yen Ta ₂ O ₅ / SiO ₂ 340 ~ 420nm 99% or more 20 to 30 6000 to 7000 yen TiO ₂ / SiO ₂ 400 to 550 nm 99% or more 35 to 45 6000 to 8000 Å Nb ₂ O ₅ / SiO ₂ 420 ~ 700nm 99% or more 20 to 30 6000 to 7000 yen

The first reflective structure pattern 140 is composed of a low refractive index layer and a high refractive index layer, these two layers are respectively HfO ₂ / SiO ₂ , Ta ₂ O ₅ / SiO ₂ , TiO ₂ / SiO ₂ or Nb ₂ O ₅ / SiO ₂ reflects light at 100%, at least 99%, at least 99%, or at least 99%, respectively, at wavelengths of 260-300 nm, 340-420 nm, 400-550 nm or 420-700 nm, respectively. The low refractive index layer and the high refractive index layer is provided with the number of layers of 20 ~ 30, 20 ~ 30, 35 ~ 45 or 20 ~ 30, respectively, 6000 ~ 7000Å, 6000 ~ 7000Å, 6000 ~ 8000Å or 6000 ~ 7000Å It is preferable to be provided with the thickness of.

The first open regions 142 may be formed by varying an area of the open region. That is, although not shown in detail in the drawing, where the separation distance from the first electrode pad 130 to be described later, if accurately expressed, the first electrode pad 130 and the first open area 142 is the same. Assuming it is located on a plane, compared to the open area of the first open area 142 (for example, the open area on the right side in FIG. 1) located close to the first electrode pad 130 when viewed in plan view. The open area of the first open area 142 (eg, the open area on the left side of FIG. 1) located far from the second electrode pad 130 may be formed to be larger. This is because a relatively large amount of current flows through the first open area 142 located close to the first electrode pad 130, compared to the first open area 142 close to the first electrode pad 130. This is to make the entire current distribution of the light emitting device uniform by increasing the open area of the first open region 142 located far from the first electrode pad 130.

As described above, the first reflective structure pattern 140 reflects light traveling in the direction of the second conductive semiconductor layer 126 to increase the luminous efficiency of the light emitting diode 100. The first open regions 142 pass through the light traveling toward the second conductive semiconductor layer 126 to lower the light emitting efficiency of the light emitting diode 100, thereby minimizing the total open area. It is desirable to minimize the open areas 142. However, since the first open regions 142 play a role in determining a contact area between the contact layer 150 and the second conductive semiconductor layer 126 which will be described later, the open area of the first open regions 142 may be increased. In a small case, the possibility of the light traveling toward the second conductive semiconductor layer 126 is increased, while the contact area between the contact layer 150 and the second conductive semiconductor layer 126 is reduced to reduce the contact area. In order to supply power to the second conductive semiconductor layer 126, problems such as an increase in contact resistance are caused. Therefore, it is preferable to appropriately adjust the total open area, the number, and the size of the first open region 142. .

The contact layer 150 may be provided on the growth substrate 110 provided with the first reflective structure pattern 140. The contact layer 150 may contact the surface of the second conductive semiconductor layer 126 of the semiconductor structure layer 120 through the open regions 142 of the first reflective structure pattern 140.

Generally, P-type semiconductors do not have good ohmic contact with a metal. When the second conductive semiconductor layer 126 of the semiconductor structure layer 120 is made of P-type semiconductor, The second conductive semiconductor layer 126 of the semiconductor structure layer 120 may be formed of a material that can make an ohmic contact well. The contact layer 150 may be formed of a transparent contact layer including a transparent conductive oxide such as ITO. The contact layer 150 may have a thickness of 500 to 3000 kPa, preferably 1000 kPa.

The second reflective structure pattern 160 may be provided on the contact layer 150 and may cover the first open area 142 of the first reflective structure pattern 140. In this case, the second reflective structure pattern 160 is provided to cover the first open area 142, as shown in FIG. 1, and the second reflective structure pattern 160 is formed of the first reflective structure pattern ( 140 is provided on the open area without the light, and the light generated in the active layer 124 is not reflected by the first reflective structure pattern 140 and passes through the first open area 142. The second reflective structure pattern 160 may be provided at least as large as or slightly larger than the size (ie, width and width) of the first open area 142 so that the reflective structure pattern 160 can be reflected. It means that there is. Of course, the second reflective structure pattern 160 may be provided to cover a portion of the first reflective structure pattern 140 as well as the first open region 142.

The second reflective structure pattern 160 may include a plurality of second open regions 162 exposing the surface of the contact layer 150. The second open region 162 electrically connects the contact layer 150 and the second reflective layer 184 or the second electrode pad 170 to be described later.

As described above, the second reflective structure pattern 160 may be applied to the first reflective structure pattern 140 of the light generated in the active layer 124 and traveling toward the second conductive semiconductor layer 126. It is not reflected but serves to reflect the light traveling to the first open area 142.

The second reflective structure pattern 160 has a structure in which at least two layers having different refractive indices are repeatedly stacked at least once in the same manner as the first reflective structure pattern 140, for example, a plurality of low refractive index layers and high refractive index layers are provided. It may be provided including a stacked structure repeatedly, that is, a distributed bragg reflector (DBR). In this case, the low refractive index layer may be composed of SiO ₂ layer or Al ₂ O ₃ layer, the high refractive index layer is HfO ₂ layer, TiO ₂ layer, Nb ₂ O ₅ layer, Ta ₂ O ₃ or Si ₃ N ₄ layer Can be made. In addition, each of the layers constituting the second reflective structure pattern 160 may have a thickness that is an integer multiple of λ / 4n, wherein λ is a wavelength of light and n is a refractive index of a medium. The second reflective structure pattern 160 may have a total thickness of about 3000 mm to about 10,000 mm. In addition, the second reflective structure pattern 160 may be formed of the materials shown in Table 1 like the first reflective structure pattern 140.

Conventionally, the light traveling in the direction of the second conductive semiconductor layer 126 among the light generated by the active layer 124 is absorbed by the contact layer or disappears through total reflection in the reflective layer or the electrode pad and is extracted to the outside direction. In the present invention, the first reflective structure pattern 140, the contact layer 150, and the second reflective structure pattern 160 are provided to advance to the second conductive semiconductor layer 126. By reflecting the light to the first reflective structure pattern 140 having a high reflectance in a wide wavelength range, not only increases the amount of light extracted to the outside, but also minimizes the light propagation layer to provide a light emitting diode 100 having high luminous efficiency. can do. At the same time, the present invention includes the first open region 142 and the second open region 162 and the second conductive semiconductor layer 126 and the second reflective layer 184 to be described later through the contact layer 150. ) Or the ohmic contact with the second electrode pad 170 can be smoothly provided to provide a light emitting diode 100 having high luminous efficiency. In addition, according to the present invention, the second conductive structure pattern 160 reflects the light directed toward the second reflective layer 184 or the second electrode pad 170 through the first open region 142. Most of the light traveling to the semiconductor layer 126 may be reflected by the first reflection structure pattern 140 or the second reflection structure pattern 160 having a high reflection efficiency to provide a light emitting diode 100 having high luminous efficiency. have.

The second reflective layer 184 may be provided on the second reflective structure pattern 160. The second reflective layer 184 may be electrically connected to the contact layer 150 through the second open region 162 of the second reflective structure pattern 160. In this case, the second reflection layer 184 may serve to reflect light traveling toward the second conductive semiconductor layer 126, but may reflect light traveling toward the second conductive semiconductor layer 126. Since the first reflection structure pattern 140 or the second reflection structure pattern 160 is formed in the second reflection layer 184 may be omitted.

The second electrode pad 170 may be provided on the second reflective layer 184. When the second reflection layer 184 is omitted, the second reflection layer 184 may be provided on the second reflection structure pattern 160 and may be electrically connected to the contact layer 150 through the second open area 162. Can be. The second electrode pad 170 may be formed of a single layer or a plurality of layers, and the layers may include Ni, Cr, Ti, Al, Ag, Au, or a compound thereof.

2 is a cross-sectional view showing a light emitting diode according to another embodiment of the present invention.

Referring to FIG. 2, a light emitting diode 200 according to another embodiment of the present invention may include a semiconductor structure layer 220, a first electrode pad 230, a first reflective structure pattern 240, and a contact layer 250. ), A second reflective structure pattern 260, a second electrode pad 270, and a conductive substrate 280.

The semiconductor structure layer 220 may include a first conductive semiconductor layer 222, an active layer 224, and a second conductive semiconductor layer 226. In addition, the semiconductor structure layer 220 may further include a superlattice layer (not shown) or an electron breaking layer (not shown). In this case, the semiconductor structure layer 220 may be omitted except for the active layer 224.

In this case, the active layer 224, the second conductive semiconductor layer 226, the superlattice layer (not shown), or the electron breaking layer (not shown) may be a light emitting diode according to an exemplary embodiment of the present invention described with reference to FIG. 1. The same is true except that mesa etching is not performed in comparison with the active layer 124, the second conductive semiconductor layer 126, the superlattice layer (not shown), or the electron blocking layer (not shown) of (100). Therefore, detailed description is omitted.

In addition, in the first conductive semiconductor layer 222, one surface of the first conductive semiconductor layer 222 is exposed to the outside as compared with the first conductive semiconductor layer 122, and the first conductive type is exposed. The first electrode pad 230, which will be described later, is provided on a predetermined position of one surface of the semiconductor layer 222, and the unevenness 222a is formed in another region of the one surface on which the first electrode pad 230 is not provided. The difference is the same in that it is provided, so the detailed description is omitted.

The unevenness 222a is the first conductive semiconductor layer 222 when light generated in the active layer 224 of the semiconductor structure layer 220 is emitted to the outside through the first conductive semiconductor layer 222. The total internal reflection at the interface of the ()) serves to reduce the light 290 is lost. The unevenness 222a is a boundary surface when the light passes between two media having different refractive indices, that is, when the light passes from the first conductive semiconductor layer 222 to the outside (ie, in the air). In other words, reflection and transmission occur at the interface between the first conductive semiconductor layer 222 and the outside, thereby minimizing the reflection to increase the amount of light emitted to the outside through the first conductive semiconductor layer 222. It increases the luminous efficiency.

The first electrode pad 230 may be provided on a surface of one surface of the first conductive semiconductor layer 222 and a lower surface of the first conductive semiconductor layer 222 as shown in FIG. 2. Can be. Compared to the first electrode pad 130 of the light emitting diode 100 according to an embodiment of the present invention, the first electrode pad 230 has only the same location but different materials and functions. Omit.

The first reflective structure pattern 240, the contact layer 250, and the second reflective structure pattern 260 may be provided on the second conductive semiconductor layer 226. The first reflective structure pattern 240 may include a plurality of first open regions exposing a predetermined region of the second conductive semiconductor layer 226, and the second reflective structure pattern 260 may include the contact. A plurality of second open regions exposing a predetermined region of the layer 250 may be provided. In this case, the first reflective structure pattern 240, the first open region 242, the contact layer 250, the second reflective structure pattern 260, and the second open region 262 are according to an embodiment of the present disclosure. The first reflective structure pattern 140, the first open region 142, the contact layer 150, the second reflective structure pattern 160, and the second open region 162 of the light emitting diode 100 and the structure thereof. Since the forming materials or functions are the same, detailed description thereof will be omitted.

In this case, the first reflective structure pattern 240 is similar to the first reflective structure pattern 140 of the light emitting sugar diode 100 according to an embodiment of the present invention, as shown in FIG. Of the light generated in the active layer 224 of the 220, the light traveling toward the second conductive semiconductor layer 226 is reflected in the direction of the first conductive semiconductor layer 226, and the light is extracted to the outside ( It serves to increase the amount of light 190, that is, to increase the luminous efficiency of the light emitting diode (200).

In this case, the first open region 242 is not shown in detail like the first open region 142 of the light emitting diode 100 according to the exemplary embodiment of the present invention. Can be formed. That is, assuming that the first electrode pad 230 is far from the distance, that is, the first electrode pad 230 and the first open region 242 are located on the same plane, when viewed in plan view, Compared to the open area of the first open area 242 (for example, the open area located in the center of FIG. 2) located close to the first electrode pad 230, far away from the second electrode pad 230. The open area of the located first open area 242 (for example, open areas located at both edges on the right or left side in FIG. 1) may be formed to be larger. As described above, this is because the open area of the first open area 242 located far from the first electrode pad 230 is widened to make the overall current distribution of the light emitting device uniform.

The conductive substrate 280 may be provided on the second reflective structure pattern 260. The conductive substrate 280 may be made of a conductive metal material.

A reflective layer 282 and an adhesive layer 284 may be further included between the conductive substrate 280 and the second reflective structure pattern 260. Since the reflective layer 282 is the same as the second reflective layer 184, a detailed description thereof will be omitted.

The adhesive layer 284 serves to bond the reflective layer 282 or the second reflective structure pattern 260 with the conductive substrate 280. The adhesive layer 284, the reflective layer 282, or the second reflective structure pattern 260 may further include a diffusion barrier layer (not shown), and the diffusion barrier layer (not shown) may be a material forming the adhesive layer 284. The diffusion layer 282 is prevented from being diffused to prevent the reflective layer 282 from being contaminated by the material forming the adhesive layer 284.

The second electrode pad 270 may be provided on a surface opposite to the surface of the conductive substrate 280 that adheres to the reflective layer 282 or the second reflective structure pattern 260. In this case, the second electrode pad 270 and the reflective layer 282 may be included, and layers interposed therebetween, for example, the adhesive layer 284 may be made of an electrically conductive material.

Compared to the second electrode pad 170 of the light emitting diode 100 according to an embodiment of the present invention, the second electrode pad 270 differs only in its location, and other functions or materials forming the same are the same. Therefore, detailed description is omitted.

3 to 6 are cross-sectional views illustrating a method of manufacturing a light emitting diode according to an embodiment of the present invention.

Referring to FIG. 3, first, a growth substrate 110 is prepared. The growth substrate 110 may be any substrate capable of growing semiconductor layers, and may not be particularly limited, such as a sapphire substrate, a SiC substrate, a spinel substrate, and preferably a sapphire substrate.

In this case, although not shown in FIG. 3, the growth substrate 110 may be a substrate in which the PSS pattern 112 is previously provided on the other surface thereof.

Subsequently, a plurality of semiconductor layers including a buffer layer 114, a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126 are formed on one surface of the growth substrate 110. Can be formed. At this time, a super lattice layer (not shown) between the first conductive semiconductor layer 122 and the active layer 124, and an electron blocking layer (not shown) between the active layer 124 and the second conductive semiconductor layer 126. ) May be further included.

The semiconductor layers may be grown by epitaxial growth, and may be continuously grown using a chemical vapor deposition apparatus such as plasma enhanced chemical vapor deposition (PECVD) or metal organic chemical vapor deposition (MOCVD).

Subsequently, at least a portion of the second conductive semiconductor layer 126 and the active layer 124 is etched to perform a mesa etching process to expose a portion of the first conductive semiconductor layer 122. The semiconductor structure layer 120 including the first conductive semiconductor layer 122, the active layer 124, and the second conductive semiconductor layer 126 exposing the surface thereof may be formed. In this case, a portion of the first conductive semiconductor layer 122 may also be etched during the mesa etching.

At this time, in an embodiment of the present invention, after forming the semiconductor layers on the growth substrate 110, a mesa etching process is first performed to form the semiconductor structure layer 120, and then the process is shown. After the semiconductor layers are formed, the first reflective structure pattern 140, the contact layer 150, and the second reflective structure pattern 160 will be described later without performing the mesa etching process. After forming on the semiconductor layers, the first reflective structure pattern 140, the contact layer 150, and the first conductive structure pattern 140, the contact layer 150, and the second conductive semiconductor layer 126 and the active layer 124 may be etched in a mesa etching process. Note that a part of the two reflection structure patterns 160 may also proceed to the etching process at the same time.

Referring to FIG. 4, a first reflective structure pattern 140 is formed on the second conductive semiconductor layer 126.

The first reflective structure pattern 140 alternately stacks a low refractive index layer (not shown) and a high refractive index layer (not shown) on the second conductive semiconductor layer 126 at least once, and then, The patterning process of forming one open region 142 may be performed.

In this case, the low refractive index layer may be composed of SiO ₂ layer or Al ₂ O ₃ layer, the high refractive index layer is HfO ₂ layer, TiO ₂ layer, Nb ₂ O ₅ layer, Ta ₂ O ₃ or Si ₃ N ₄ layer Can be made.

The low refractive index layer and the high refractive index layer may be formed of an appropriate material or thickness according to the wavelength of light to be reflected by the first reflective structure pattern 140. In addition, when the first reflective structure pattern 140 intends to reflect light in a wide range of wavelength bands, the low refractive index layer and the high refractive index layer are repeatedly stacked a plurality of times, but varying the thickness or the material of each layer is a wide range. It may be formed to reflect light of the wavelength band of.

Referring to FIG. 5, the contact layer 150 is formed on the growth substrate 110 on which the first reflective structure pattern 140 is formed. The contact layer 150 may be made of a transparent conductive oxide such as ITO. In this case, the contact layer 150 contacts the surface of the second conductive semiconductor layer 126 through the first open region 142 of the first reflective structure pattern 140.

Subsequently, a second reflective structure pattern 160 is formed on the contact layer 150. The second reflective structure pattern 160 may be formed by alternately stacking a low refractive index layer (not shown) and a high refractive index layer (not shown) on the contact layer 150 at least one or more times. The patterning process of forming 162 may be performed.

In this case, the patterning process for forming the second reflective structure pattern 160 is performed in consideration of the position and size of the first open region 142 of the first reflective structure pattern 140. That is, the second reflective structure pattern 160 is formed so as to cover at least the first open area 142, that is, the second open area 162 and the first open area 142 do not overlap each other. do.

In this case, the low refractive index layer may be composed of SiO ₂ layer or Al ₂ O ₃ layer, the high refractive index layer is HfO ₂ layer, TiO ₂ layer, Nb ₂ O ₅ layer, Ta ₂ O ₃ or Si ₃ N ₄ layer Can be made.

The low refractive index layer and the high refractive index layer may be formed of an appropriate material or thickness according to the wavelength of light to be reflected by the second reflective structure pattern 160. In addition, when the second reflective structure pattern 160 is intended to reflect light in a wide range of wavelength range, the low refractive index layer and the high refractive index layer are repeatedly stacked a plurality of times, but varying the thickness or material of each layer in a wide range It may be formed to reflect light of the wavelength band of.

Referring to FIG. 6, a first reflective layer 182 and a first electrode pad 130 are formed on the first conductive semiconductor layer 122, and a second reflective structure pattern 160 is formed on the first reflective semiconductor layer 122. The second reflection layer 184 and the second electrode pad 170 may be formed.

The reflective layers 182 and 184 and the electrode pads 130 and 170 may be formed by sequentially stacking and patterning a material forming the reflective layers 182 and 184 and the electrode pads 130 and 170 on the growth substrate 110. The electrode pads 130 and 170 may be formed by first forming the reflective layers 130 and 170 and then forming stud bumps on the reflective layers 182 and 184. In this case, the reflective layers 182 and 184 may be omitted.

Subsequently, a process of forming a PSS pattern 112 by performing a PSS process on the other surface of the growth substrate 110 may be performed to form a light emitting diode 100 according to an exemplary embodiment. In the PSS process, one surface of the growth substrate 110 is protected by forming a protective film, and a metal layer is formed on the other surface of the growth substrate 110 to perform heat treatment to form a plurality of metal nano-isles ( metal nano-island) and partially etch the other surface of the growth substrate using the metal nanoisles as shadow masks.

7 to 9 are cross-sectional views illustrating a method of manufacturing a light emitting diode according to another embodiment of the present invention.

Referring to FIG. 7, first, a growth substrate 210 is prepared.

Subsequently, a semiconductor structure layer 220 including a buffer layer 214, a first type semiconductor layer 222, an active layer 224, and a second type semiconductor layer 226 is formed on the growth substrate 210. First reflective pattern 240 with regions 242, contact layer 250, second reflective pattern 260 with second open region 262, reflective layer 282, and adhesive layer 284. To form sequentially.

In this case, the semiconductor structure layer 220 including the buffer layer 214, the first type semiconductor layer 222, the active layer 224, and the second type semiconductor layer 226 may be provided. The method of forming the first reflective structure pattern 240, the contact layer 250, the second reflective structure pattern 260 having the second open area 262 and the reflective layer 282 is an embodiment of the present invention. A semiconductor including the buffer layer 114, the first type semiconductor layer 122, the active layer 124, and the second type semiconductor layer 126 described with reference to FIGS. The first reflective structure pattern 140 having the structure layer 120, the first open regions 142, the second reflective structure pattern 160 having the contact layer 150, the second open region 162, and Since the semiconductor structure layer 220 is formed in comparison with the method of forming the second reflective layer 184, the mesa etching is not performed, and thus the detailed description is omitted. All.

The process of forming the adhesive layer 284 may include attaching the adhesive layer 284 in the form of a film on the second reflective structure pattern 160 or the second reflective layer 184, or the second reflective structure pattern 160 or the second reflective structure pattern 160. It can be formed by forming an adhesive material on the two reflection layer 184.

Referring to FIG. 8, a conductive substrate 280 is prepared separately from a process of forming a plurality of layers including the semiconductor structure layer 220 on the growth substrate 210.

Subsequently, the conductive substrate 280 and the growth substrate 210 are bonded to each other, preferably the conductive substrate 280 and the adhesive layer 284 are bonded to the conductive substrate 280 and the growth substrate 210.

Referring to FIG. 9, the growth substrate 210 is lifted off, preferably a laser lift off, in a state in which the conductive substrate 280 and the growth substrate 210 are coupled to each other. -off) to separate them.

In this case, when the growth substrate 210 is separated or after the buffer layer 214 remains on the surface of the first conductive semiconductor layer 222, it may be removed. Of course, although not shown in the figure, the buffer layer 214 may be left without removing it.

Subsequently, a first electrode pad 230 is formed on a predetermined region of the first conductive semiconductor layer 222, and on the surface of the conductive substrate 280 that does not adhere to the adhesive layer 284. A process of forming the second electrode pad 270 may be performed.

Subsequently, a process of forming the unevenness 222a on the surface of the first conductive semiconductor layer 222, and preferably on the surface of the region where the first electrode pad 230 is not formed may be performed. In this case, the process of forming the unevenness 222a may be a process using a photoelecrochemical (PEC) etching method or a sand blast method on the surface of the first conductive semiconductor layer 222. In this case, although the first electrode pad 230 is first formed on the surface of the first conductive semiconductor layer 222 and the unevenness 222a is described, the unevenness 222a is formed first. Afterwards, the second electrode pad 230 may be formed.

The present invention has been described above with reference to the above embodiments, but the present invention is not limited thereto. Those skilled in the art will appreciate that modifications and variations can be made without departing from the spirit and scope of the present invention and that such modifications and variations also fall within the present invention.

110, 210: growth substrate 120, 220: semiconductor structure layer
130 and 230: first electrode pad 140 and 240: first reflective structure pattern
142 and 242: first open area 150 and 250: contact layer
160, 260: second reflective structure pattern 162, 262: second open area
170 and 270: second electrode pad 280: conductive substrate

Claims (22)

A semiconductor structure layer including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer;
A first reflective structure pattern provided on the second conductive semiconductor layer and having a plurality of first open regions exposing a surface of the second conductive semiconductor layer;
A contact layer provided on the second conductive semiconductor layer provided with the first reflective structure pattern and in contact with the second conductive semiconductor layer through the first open region; And
And a second reflective structure pattern provided on the contact layer, the plurality of second open regions exposing the surface of the contact layer and covering at least the first open regions.
The light emitting diode of claim 1, wherein a size of the second reflective structure pattern is equal to or larger than a size of the first open region so that light passing through the first open region is reflected by the second reflective structure pattern.
The light emitting diode of claim 1, wherein the first reflective structure pattern or the second reflective structure pattern comprises a distributed bragg reflector (DBR).
The method of claim 1, wherein each of the first reflective structure pattern or the second reflective structure pattern is at least one layer of at least two layers having different refractive indices are repeatedly stacked at least once, and each layer is lambda / 4n (wherein lambda is a wavelength of light N is the refractive index of the medium.
The method of claim 4, wherein each of the first reflective structure pattern or the second reflective structure pattern is a low refractive index layer and a high refractive index layer is laminated at least once, the low refractive index layer is a SiO ₂ layer or Al ₂ O ₃ layer Wherein the high refractive index layer is an HfO ₂ layer, a TiO ₂ layer, an Nb ₂ O ₅ layer, a Ta ₂ O _3, or a Si ₃ N ₄ layer.
The method of claim 1, wherein the light emitting diode has a growth substrate,
The semiconductor structure layer is provided on one surface of the growth substrate, the second conductive semiconductor layer and the active layer is mesa-etched light emitting diode provided with a portion of the first conductive semiconductor layer exposed.
The method of claim 6, wherein the light emitting diode
A first electrode pad provided on an exposed portion of the first conductive semiconductor layer; And
And a second electrode pad in electrical contact with the contact layer exposed through the second open region.
The light emitting diode of claim 7, further comprising a reflective layer provided between the second reflective structure pattern and the second electrode pad, wherein the reflective layer contacts the contact layer exposed through the second open area.
The light emitting diode of claim 6, wherein the other surface of the growth substrate has a patterned sapphire substrate (PSS) pattern.
The method of claim 1, wherein the light emitting diode further comprises a conductive substrate,
The conductive substrate is a light emitting diode provided on the second reflective structure pattern.
The light emitting diode of claim 10, wherein the light emitting diode further comprises an adhesive layer provided between the conductive substrate and the second reflective structure pattern, wherein the conductive substrate and the second reflective structure pattern are combined by the adhesive layer.
The method of claim 10, wherein the light emitting diode
A first electrode pad provided on the first conductive semiconductor layer; And
The light emitting diode further comprises a second electrode pad provided on the conductive substrate.
The method of claim 10, wherein the light emitting diode
The light emitting diode of claim 1, further comprising irregularities provided on a surface of the first conductive semiconductor layer on which the first electrode pad is not formed.
The method according to claim 6 or 10,
The first open area has a larger area of the open area than the first open area where the first open area is located far from the first electrode pad on a plane compared to the first open area located close to the first electrode pad. Large light emitting diode.
Preparing a growth substrate;
Forming a semiconductor structure layer including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer, a portion of which is exposed on one surface of the growth substrate;
Forming a first reflective structure pattern having a plurality of first open regions on the second conductive semiconductor layer;
Forming a contact layer on the first reflective structure pattern, the contact layer being in contact with the second conductive semiconductor layer through the first open region; And
Forming a second reflective structure pattern on the contact layer, the second opening having a plurality of second open regions exposing the surface of the contact layer, and covering at least the first open regions; .
The method of claim 15, wherein the light emitting diode manufacturing method
Forming a first electrode pad on the first conductive semiconductor layer and forming a second electrode pad on the second reflective structure pattern, the second electrode pad being in electrical contact with the contact layer through the second open regions; Light emitting diode manufacturing method further comprising.
The method of claim 16, further comprising forming a reflective layer on the second reflective structure pattern before forming the first electrode pad and the second electrode pad.
The method of claim 16, further comprising forming a PSS pattern on the other surface of the growth substrate after forming the first electrode pad and the second electrode pad.
The method of claim 15, wherein the light emitting diode manufacturing method
Preparing a conductive substrate;
Forming an adhesive layer on the second reflective structure pattern;
Bonding the conductive substrate and the growth substrate using the adhesive layer; And
And separating the growth substrate from the first conductive semiconductor layer.
The method of claim 19, further comprising forming a reflective layer on the second reflective structure pattern before forming the adhesive layer.
The method of claim 19, further comprising forming a first electrode pad on the first conductive semiconductor layer, and forming a second electrode pad on the conductive substrate.
The method of claim 21, wherein before or after forming the first electrode pad on the first conductive semiconductor layer, irregularities are formed on a surface other than the surface of the first conductive semiconductor layer provided with the first electrode pad. The method of manufacturing a light emitting diode further comprising the step of forming.

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