KR101138977B1 - Light emitting device and method of fabricating the same - Google Patents

Abstract

A light emitting device and a method of manufacturing the same are disclosed. The light emitting device includes a substrate, a semiconductor stack disposed on the substrate, the semiconductor stack including an upper semiconductor layer of a first conductivity type, an active layer, and a lower semiconductor layer of a second conductivity type, and separation grooves separating the semiconductor stack into a plurality of regions. And a connecting portion positioned between the substrate and the semiconductor stack and electrically connecting the plurality of regions to each other, and a distributed Bragg reflector having a multilayer structure positioned between the semiconductor stack and the connecting portions. The connections are electrically connected to the semiconductor stack through the distributed Bragg reflective layer, and a portion of the Distributed Bragg reflective layer is located between the separation grooves and the connections. The distribution Bragg reflective layer may improve reflectance and prevent generation of metal etching by-products during the manufacturing process, and may reduce light loss by filling the connection parts inside the light emitting device.

Description

LIGHT EMITTING DEVICE AND METHOD OF FABRICATING THE SAME}

The present invention relates to a light emitting device and a method of manufacturing the same, and more particularly, to a light emitting device to which a substrate separation process is applied and a method of manufacturing the same.

A light emitting diode is a semiconductor device having a structure in which an N-type semiconductor and a P-type semiconductor are bonded to each other, and emit light by recombination of electrons and holes. Such light emitting diodes are widely used as display devices and backlights. In addition, the light emitting diode consumes less power and has a longer lifespan than existing light bulbs or fluorescent lamps, thereby replacing its incandescent lamps and fluorescent lamps, thereby expanding its use area for general lighting.

Recently, AC light emitting diodes that emit light continuously by directly connecting the light emitting diodes to AC power have been commercialized. Light emitting diodes that can be used directly in connection with high voltage alternating current power supplies are described, for example, in Published International Publication No. WO 2004/023568 (Al), which are referred to as "light-emitting elements having light-emitting components". The title is disclosed by SAKAI et al.

According to WO 2004/023568 (Al), series LED arrays are formed in which two LED elements (light emitting cells) are connected two-dimensionally on an insulating substrate such as a sapphire substrate. These LED arrays are connected in antiparallel on the sapphire substrate. As a result, a single chip light emitting device that can be driven by an AC power supply is provided.

Since the AC-LED forms light emitting cells on a substrate used as a growth substrate, for example, a sapphire substrate, there is a limitation in the structure of the light emitting cells and there is a limit in improving light extraction efficiency. In order to solve this problem, a method of manufacturing an AC-LED by applying a substrate separation process has been disclosed in Korean Patent Publication No. 10-0599012 entitled "Light Emitting Diode Having a Thermally Conductive Substrate and a Method of Manufacturing The Same".

1 to 4 are cross-sectional views illustrating a method of manufacturing a light emitting device according to the prior art.

Referring to FIG. 1, semiconductor layers including a buffer layer 23, an N-type semiconductor layer 25, an active layer 27, and a P-type semiconductor layer 29 are formed on a sacrificial substrate 21. The first metal layer 31 is formed on the field, and the second metal layer 53 is formed on the substrate 51 separate from the sacrificial substrate 21. The first metal layer 31 may include a reflective metal layer. The second metal layer 53 is bonded to the first metal layer 31 so that the substrate 51 is bonded over the semiconductor layers.

Referring to FIG. 2, after the substrate 51 is bonded, the sacrificial substrate 21 is separated by using a laser lift-off process. In addition, after the sacrificial substrate 21 is separated, the remaining buffer layer 23 is removed, and the surface of the N-type semiconductor layer 25 is exposed.

Referring to FIG. 3, the semiconductor layers 25, 27, 29 and the metal layers 31, 53 are patterned and spaced apart from each other by using a photo and etching technique, and the metal patterns 40. Light emitting cells 30 are formed on a partial region of the substrate. The light emitting cells 30 include a patterned P-type semiconductor layer 29a, an active layer 27a, and an N-type semiconductor layer 25a.

Referring to FIG. 4, metal wires 57 are formed to electrically connect the upper surfaces of the light emitting cells 30 and the metal patterns 40 adjacent thereto. The metal wires 57 connect the light emitting cells 30 to form a series array of light emitting cells. In order to connect the metal wires 57, an electrode pad 55 may be formed on the N-type semiconductor layer 25a, and an electrode pad may also be formed on the metal patterns 40. Two or more such arrays may be formed, and there is provided a light emitting diode in which these arrays are connected in parallel and driven under an AC power source.

According to the related art, the substrate 51 may be variously selected, thereby improving heat dissipation performance of the light emitting device, and treating the surface of the N-type semiconductor layer 25a to improve light extraction efficiency. In addition, since the first metal layer 31a reflects the light traveling from the light emitting cells 30 to the substrate 51 side including the reflective metal layer, the luminous efficiency may be further improved.

However, according to the related art, during the patterning of the semiconductor layers 25, 27, 29 and the metal layers 31, 53, an etch by-product of a metal material adheres to the sidewall of the light emitting cell 30, thereby forming an N-type semiconductor layer ( An electrical short may be caused between 25a) and the P-type semiconductor layer 29a. In addition, the surface of the first metal layer 31a exposed during the etching of the semiconductor layers 25, 27, and 29 may be easily damaged by plasma. This etching damage is further exacerbated when the first metal layer 31a includes a reflective metal layer such as Ag or Al. Damage to the surface of the metal layer 31a by the plasma degrades the adhesion of the wirings 57 or the electrode pads formed thereon, resulting in device defects.

Meanwhile, according to the related art, the first metal layer 31 may include a reflective metal layer, and thus reflects light traveling from the light emitting cells 30 toward the substrate. However, it is difficult to expect the reflection of light by etching damage or oxidation of the reflective metal layer in the space between the light emitting cells 30. Moreover, the reflectance of the reflective metal layer is limited to improvement of up to about 90%. Further, since the substrate 51 is exposed in the region between the metal patterns 40, light may be absorbed and lost by the substrate 51.

Further, since the wirings 57 are connected on the upper surface of the N-type semiconductor layer 25a, that is, on the light emitting surface, the light generated in the active layer 25a is transferred to the wirings 57 and / or on the light emitting surface. Light loss may occur due to absorption of the electrode pads 55.

International Publication No. WO 2004/023568 (Al) Korean Registered Publication No. 10-0599012

It is an object of the present invention to provide an AC light emitting device and a method of manufacturing the same, which can prevent an electrical short circuit in a light emitting cell caused by metal etching by-products.

Another object of the present invention is to provide a light emitting device and a method of manufacturing the same, which can reduce the loss of light propagating toward the substrate in the space between the light emitting cells.

Another object of the present invention is to provide a light emitting device capable of improving the light extraction efficiency by increasing the reflectance of light traveling toward the substrate, and a method of manufacturing the same.

Another object of the present invention is to provide a light emitting device capable of improving the light emitting efficiency by reducing the loss of light emitted from the light emitting surface and a method of manufacturing the same.

Another object of the present invention is to provide a light emitting device capable of preventing deformation of the reflective layer by etching or oxidation and a method of manufacturing the same.

A light emitting device according to one aspect of the present invention, a substrate; A semiconductor stack disposed on the substrate, the semiconductor stack including an upper semiconductor layer of a first conductivity type, an active layer, and a lower semiconductor layer of a second conductivity type; Isolation trenches for separating the semiconductor stack into a plurality of regions; Connectors disposed between the substrate and the semiconductor stack and electrically connecting the plurality of regions to each other; And a distributed Bragg reflective layer having a multilayer structure positioned between the semiconductor stack and the connection portions. Meanwhile, the connecting portions are electrically connected to the semiconductor stack through the distributed Bragg reflective layer, and a portion of the distributed Bragg reflective layer is located between the separation grooves and the connecting portions.

Since the connection portions are positioned between the semiconductor stack and the substrate, it is possible to prevent the light emitted from the light emitting surface of the light emitting cell from being lost by the connection portions. In addition, the connection Bragg reflection layer may be prevented from being exposed to the outside, it is possible to prevent the short circuit of the light emitting cell generated by the etching by-products during the formation of the separation grooves.

In some embodiments, at least some of the separation grooves penetrate the upper semiconductor layer of the first conductivity type, the active layer, and the lower semiconductor layer of the second conductivity type. In some embodiments, the isolation grooves may penetrate the upper semiconductor layer of the first conductivity type, the active layer, and the lower semiconductor layer of the second conductivity type.

At least one of the plurality of regions may have a single light emitting cell. In addition, the connection parts may be connected to the first conductivity type upper semiconductor layer and the second conductivity type lower semiconductor layer of the single light emitting cell, respectively. In some embodiments, a connection portion connected to the first conductivity type upper semiconductor layer is connected to the second conductivity type lower semiconductor layer in another region of the plurality of regions, and is connected to the second conductivity type lower semiconductor layer. The connected portion may be connected to the first conductivity type upper semiconductor layer in another region.

Meanwhile, at least one of the plurality of regions may have a common light emitting cell sharing the first conductivity type upper semiconductor layer. In some embodiments, the connection portion is connected to the first conductive upper semiconductor layer shared by the common light emitting cell, and the connection portions are respectively connected to the second conductive lower semiconductor layers of the common light emitting cell. Can be. Furthermore, a connection portion connected to the first conductivity type upper semiconductor layer is connected to the second conductivity type lower semiconductor layer in another region, and at least one of the connection portions connected to the second conductivity type lower semiconductor layers is adjacent to the common layer. It may be connected to the second conductive lower semiconductor layer of the light emitting cell.

The light emitting device may further include a bonding metal positioned between the substrate and the semiconductor stack and a separation insulating layer that separates the connecting portions from the bonding metal.

The light emitting device may further include an ohmic contact layer connected to the second conductive lower semiconductor layer through the distributed Bragg reflective layer, and the connection portions may be connected to the second conductive lower semiconductor of the semiconductor stack through the ohmic contact layer. It can be electrically connected to the layer. The ohmic contact layer may be formed of a reflective layer such as Ag or Al, or a transparent conductive layer such as Ni / Au, ITO, ZnO, or CTO. The distributed Bragg reflective layer may be patterned to expose the second conductive semiconductor layer so that the ohmic contact layer may be connected to the second conductive lower semiconductor layer.

The light emitting device may further include a protective insulating layer on the semiconductor stack to cover the semiconductor stack. The protective insulating layer may fill the separation grooves.

In addition, the light emitting device may further include electrode pads. The electrode pads are formed on one of the plurality of regions, respectively, and are connected to the first conductive upper semiconductor layer. Here, the electrode pads are pads for supplying power to the light emitting device from an external power source, for example, wires may be bonded.

The region in which the electrode pad is formed may have holes penetrating through the second conductive lower semiconductor layer and the active layer. The connection part may be electrically connected to the first conductivity type upper semiconductor layer through the holes.

The light emitting device may include a series array of at least one light emitting cells formed by the connecting parts. In addition, two series arrays may be connected in anti-parallel between the electrode pads. Accordingly, an AC light emitting device that can be driven by being connected to an AC power source can be provided.

According to another aspect of the present invention, a light emitting device manufacturing method is provided. The method includes forming a semiconductor stack on the sacrificial substrate, the semiconductor stack comprising a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer; Patterning the semiconductor stack to form connection trenches exposing the first conductivity type semiconductor layer, the connection grooves being separated from each other; Forming a multilayer Bragg reflective layer on the semiconductor stack, the distribution Bragg reflecting layer openings exposing the second conductive semiconductor layer and openings exposing the first conductive semiconductor layer exposed to the connection grooves; Have; Forming connecting portions electrically connecting the plurality of regions to each other; Forming a separation insulating layer covering the connection portions; Bonding a substrate on the isolation insulating layer; Removing the sacrificial substrate to expose the first conductivity type semiconductor layer; Patterning the semiconductor stack until the distribution Bragg reflective layer is exposed to form separation grooves separating the plurality of regions from each other.

According to the present invention, the connection portions may be buried between the semiconductor stack and the substrate by forming the connection grooves in advance before removing the sacrificial substrate. In addition, the connection portions may be prevented from being exposed by the distribution Bragg reflective layer during the formation of the separation grooves.

Meanwhile, the connection parts are electrically connected to the first conductivity type semiconductor layers exposed by the connection grooves and the second conductivity type semiconductor layers on the plurality of regions to electrically connect the plurality of regions.

Before forming the connection portions, an ohmic contact layer may be formed to contact the second conductive semiconductor layers in the plurality of regions. The ohmic contact layer is connected to the second conductivity type semiconductor layers through a distributed Bragg reflective layer. The ohmic contact layer may be formed as a reflective layer or a transparent conductive layer.

Meanwhile, electrode pads may be formed in the first conductive semiconductor layer exposed by removing the sacrificial substrate. The electrode pads may be formed on one of the plurality of regions separated by the separation grooves, respectively. A plurality of connection grooves (holes) may be formed in regions where the electrode pads are formed.

According to the present invention, it is possible to provide a light emitting device capable of preventing an electrical short circuit in a light emitting cell by preventing the generation of metal etching by-products and a method of manufacturing the same. Further, by adopting the distributed Bragg reflective layer, the reflectance of the light directed toward the substrate side can be improved as compared with the metal reflective layer. Further, since the distributed Bragg reflective layer is formed by alternately stacking insulating layers having different refractive indices such as SiO 2 / TiO 2 or SiO 2 / Nb 2 O 5, deformation by oxidation, such as a metal reflective layer, is prevented. In addition, by filling the connection parts inside the light emitting device, it is possible to prevent the light emitted from the light emitting surface from being lost by the connection parts.

1 to 4 are cross-sectional views illustrating a method of manufacturing an AC light emitting device according to the prior art.
5 is a plan view illustrating a light emitting device according to an embodiment of the present invention.
5A and 5B are cross-sectional views taken along the cut lines AA and BB of FIG. 5, respectively.
5C is an equivalent circuit diagram of FIG. 5.
6 to 12 are cross-sectional views illustrating a method of manufacturing a light emitting device according to an embodiment of the present invention. In each of the figures (a) and (b) correspond to the cross-sectional views taken along the cut lines AA and BB of FIG. 5.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to ensure that the spirit of the present invention to those skilled in the art will fully convey. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

5 is a schematic plan view illustrating a light emitting device according to an embodiment of the present invention. 5A and 5B are cross-sectional views taken along the cutting lines A-A and B-B of FIG. 5, respectively, to illustrate a light emitting device according to an embodiment of the present invention, and FIG. 5C is an equivalent circuit diagram of FIG. In the present embodiment, a light emitting device having a mirror symmetric structure will be described as an example, but the present invention is not limited thereto.

5, 5A, 5B, and 5C, the light emitting device includes a substrate 151, a semiconductor stack 130, isolation trenches 161, connecting parts 135, 135a, and 135b, and a distributed Bragg reflecting layer ( 131, 131a). In addition, the light emitting device may include an ohmic contact layer 133, a separation insulating layer 137, an adhesive layer 139, a bonding metal 141, a protective insulating layer 163, and electrode pads 165. .

The substrate 151 is separated from a growth substrate for growing the compound semiconductor layers and is a substrate attached to the compound semiconductor layers that have already been grown. The substrate 151 may be a sapphire substrate, but is not limited thereto, and may be another kind of insulating or conductive substrate. In particular, when using a sapphire substrate as a growth substrate of the semiconductor layers, the substrate 151 may be a sapphire substrate. Since the substrate 151 has the same coefficient of thermal expansion as the growth substrate, it is advantageous in the bonding process of the substrate 151 and the separation of the growth substrate.

The semiconductor stack 130 is separated into a plurality of regions S1, S2, S3, and P by the separation grooves 161. The semiconductor stack 130 includes an upper semiconductor layer 125 of a first conductivity type, an active layer 127, and a lower semiconductor layer 129 of a second conductivity type. The active layer 127 is interposed between the upper and lower semiconductor layers 125 and 129. Meanwhile, in each of the regions S1, S2, and S3, the active layer 127 and the lower semiconductor layer 129 are positioned to expose some regions of the upper semiconductor layer 125 downward. That is, the upper semiconductor layer 125a has a wider width than the active layer 127 and the lower semiconductor layer 129.

The active layer 127 and the upper and lower semiconductor layers 125 and 129 may be formed of a III-N-based compound semiconductor, such as (Al, Ga, In) N semiconductor. The upper and lower semiconductor layers 125 and 129 may be a single layer or multiple layers, respectively. For example, the upper and / or lower semiconductor layers 125 and 129 may include a contact layer and a cladding layer, and may also include a superlattice layer. In addition, the active layer 127 may have a single quantum well structure or a multiple quantum well structure. Preferably, the first conductivity type is n-type, and the second conductivity type is p-type. Since the upper semiconductor layers 125 may be formed of an n-type semiconductor layer having a relatively low resistance, the upper semiconductor layers 125 may have a relatively thick thickness. Therefore, it is easy to form the rough surface R on the upper surface of the upper semiconductor layer 125, the rough surface (R) improves the extraction efficiency of the light generated in the active layer 127.

Meanwhile, in the present embodiment, the regions S1 have a common light emitting cell. In the present specification, "common light emitting cell" means that a plurality of light emitting cells share a first conductivity type semiconductor layer or a second conductivity type semiconductor layer. Here, the regions S1 have a common light emitting cell sharing the first conductivity type upper semiconductor layer, as shown in FIG. 5A. Meanwhile, the regions S2 and S3 each have a single light emitting cell. In other embodiments, the regions S1, S2, and S3 may all have a single light emitting cell.

Regions P are also separated by separation grooves. Electrode pads 165 are formed on the regions P. Referring to FIG. The electrode pads 165 are pads for connecting to an external power source to receive power from an external power source. In general, wires may be bonded to the electrode pads 165. However, the regions P may be connected to the regions S2, respectively. That is, the regions P and the regions S2 may share at least one of the semiconductor layers, in particular, the first conductivity type upper semiconductor layer 125. The regions P have connection grooves (or holes 130b) passing through the second conductivity type lower semiconductor layer 129 and the active layer 127.

The separation grooves 161 pass through the semiconductor stack 130 to separate the semiconductor stack 130 into a plurality of regions S1, S2, S3, and P. In some embodiments, some of the isolation grooves 161 may not penetrate the active layer 127 and the lower semiconductor layer 129. Accordingly, side surfaces of the active layer 127 and the lower semiconductor layer 129 may not be exposed to some of the inner walls of the separation grooves 161. Alternatively, all of the separation grooves 161 may be formed through the upper semiconductor layer 125, the active layer 127, and the lower semiconductor layer 129. Accordingly, an inner wall of the isolation grooves 161 is formed as the semiconductor stack 130 including the upper semiconductor layer 125, the active layer 127, and the lower semiconductor layer 129. In this case, since the separation grooves 161 may be formed to have the same depth, it is possible to stabilize the etching process for forming the separation grooves 161.

Meanwhile, the connection parts 135 electrically connect the regions S1, S2, S3, and P separated by the separation grooves 161. Since the connection parts 135 are positioned between the semiconductor stack 130 and the substrate 151, the light emitted from the light emitting surface is not lost by the connection parts 135. The connections 135 may be electrically connected to the second conductive lower semiconductor layers 129 of the semiconductor stack 130 and the first conductive upper semiconductor of the semiconductor stack 130. It has connections 135b connected to the layers 125.

For example, as shown in FIG. 5A, regions S1 having common light emitting cells are connected to the second conductive lower semiconductor layers 129 and the first conductive upper semiconductors 135a, respectively. It has a connection 135b connected to the layer 125. In addition, as shown in FIG. 5B, regions S2 and S3 having a single light emitting cell may be connected to the second conductive lower semiconductor layers 129 and the first conductive upper semiconductor 135, respectively. It has a connection 135b connected to the layer 125. In addition, each of the pad regions P has connection portions 135a connected to the second conductivity type lower semiconductor layer 129. However, the connection portion 135a of the pad region P is electrically connected to the first conductivity type upper semiconductor layer 125 through the holes 130b.

On the other hand, in the first row, the connecting portions 135a in the regions S1 other than the regions S1 located on both sides are connected to the connecting portions 135a of the region S1 neighboring it. On the other hand, the connection part 135a adjacent to the pad area P is connected to the connection part 135a of the pad area P. As shown in FIG.

The connecting portion 135a of the right end region S1 of the first row is connected to the connecting portion 135b connected to the first conductive upper semiconductor layer 125 of the region S2 of the right end region of the third row. Further, the connecting portions 135b connected to the regions S1 in the third row are respectively connected to the connecting portions 135a of the regions S1 in the first row.

On the other hand, the connecting portions 135a of the regions S3 of the second row are connected to the connecting portions 135b of the first row, and the connecting portions 135b of the regions S3 of the second row are each It is connected to two connections 135a in three rows.

The connection parts 135 may provide a light emitting device having an equivalent circuit diagram as shown in FIG. 5C.

Referring to FIG. 5C, serial arrays of light emitting cells are formed by the connecting parts 135. These series arrays are connected in anti-parallel between electrode pads 165. Therefore, the light emitting device may be driven by connecting AC power to the electrode pads 165. Here, the light emitting cells in the regions S1 and S2 are applied with a forward voltage over a half cycle of an AC power supply, and a reverse voltage is applied for the remaining half cycles. In contrast, the light emitting cells in the regions S3 are applied with a forward voltage over the entire period of the AC power source. Therefore, it is possible to increase the light emitting area by the propagation light emitting cells that can emit light during the entire period of the phase change of the AC power source. Further, according to the present invention, the reverse voltage applied to one light emitting cell has the same value as the forward voltage applied to the two light emitting cells.

Referring again to FIGS. 5A and 5B, a distributed Bragg reflective layer 131 and 131a is interposed between the connecting portions 135 and the semiconductor stack 130. The distributed Bragg reflective layers 131 and 131a reflect light generated in the active layer 127 and traveling toward the substrate 151 to improve light efficiency of the light emitting device. The distributed Bragg reflective layer 131 is positioned under the second conductive lower semiconductor layer 129 in the regions S1, S2, and S3, and the distributed Bragg reflective layer 131a is the second conductive lower semiconductor layer 129. And a side surface of the active layer 127. The distribution Bragg reflective layer 131a particularly covers the side surfaces of the active layer 127 and the second conductivity type lower semiconductor layer 129 so that the upper semiconductor layer 125 and the lower semiconductor layer 129 are formed by the connecting portions 135. Prevent short circuits. On the other hand, the distribution Bragg reflective layer 131 is also located at the bottom of the separation groove 161. The distribution Bragg reflective layer 131 is positioned between the connecting portions 135 and the separating grooves 161 to prevent the connecting portions 135 from being exposed to the outside while forming the separating grooves 161.

The distributed Bragg reflective layers 131 and 131a may be formed by alternately stacking two layers having different refractive indices. For example, SiO 2 / TiO 2 or SiO 2 / Nb 2 O 5 may be alternately stacked to form a distributed Bragg reflective layer 131a. The distribution Bragg reflective layers 131 and 131a have openings exposing the second conductive lower semiconductor layer 129 and openings exposing the first conductive upper semiconductor layer 125.

On the other hand, the connecting portions 135, in particular the connecting portions 135a are electrically connected to the second conductive lower semiconductor layer 129 through the distributed Bragg reflective layer 131, that is, through the openings of the Distributed Bragg reflective layer 131. In addition, the openings of the distribution Bragg reflective layer 131a may be electrically connected to the first conductivity type upper semiconductor layer 125. In addition, the ohmic contact layer 133 contacts the second conductive lower semiconductor layer 129 through the distributed Bragg reflective layer 131, and the connecting portions 135, that is, the connecting portions 135a, are connected to the ohmic contact layer 133. ) Can be connected. The ohmic contact layer 133 may be formed of a reflective layer such as Ag or Al, or may be formed of a transparent conductive layer such as Ni / Au, ITO, ZnO, or TCO. When the ohmic contact layer 133 is formed of a metal reflective layer such as Ag or Al, the connection parts 135a may surround and protect the ohmic contact layer 133.

Meanwhile, a bonding metal 141 may be interposed between the semiconductor stack 130 and the substrate 151. The bonding metal 141 may be formed of Au / Sn as a metal material for bonding the substrate 151 on the semiconductor stack 130. In addition, a separation insulating layer 137 may be interposed between the semiconductor stack 130 and the bonding metal 141 to separate the connection portions 135 from the bonding metal 141.

Meanwhile, an adhesion layer 139 such as Cr / Au may be formed under the isolation insulating layer 137 to improve the adhesion of the bonding metal 141.

Meanwhile, the first conductivity type upper semiconductor layer 125 may have a roughened surface (R). In addition, the protective insulating layer 163 covers the semiconductor stack 130 to protect the light emitting cells. The protective insulating layer 163 may fill the separation grooves 161.

6 to 12 are cross-sectional views illustrating a method of manufacturing a light emitting device according to an embodiment of the present invention. In each of the figures, (a) and (b) show cross-sectional views taken along the cut lines A-A and B-B of Fig. 5, respectively.

Referring to FIG. 6, a semiconductor stack 130 of compound semiconductor layers is formed on the sacrificial substrate 121. The sacrificial substrate 121 may be a sapphire substrate, but is not limited thereto, and may be another hetero substrate. Meanwhile, the compound semiconductor layers include the first conductive semiconductor layer 125 and the second conductive semiconductor layer 129 and an active layer 129 interposed therebetween. The first conductivity type semiconductor layer 125 is located close to the sacrificial substrate 121. The first and second conductivity-type semiconductor layers 125 and 129 may be formed in a single layer or multiple layers, respectively. In addition, the active layer 127 may be formed in a single quantum well structure or a multiple quantum well structure.

The compound semiconductor layers may be formed of a III-N-based compound semiconductor, and may be grown on the sacrificial substrate 121 by a process such as metal organic chemical vapor deposition (MOCVD) or molecular beam deposition (MBE). Can be.

Meanwhile, before forming the compound semiconductor layers, a buffer layer (not shown) may be formed. The buffer layer is adopted to mitigate lattice mismatch between the sacrificial substrate 121 and the compound semiconductor layers, and may be a gallium nitride-based material layer such as gallium nitride or aluminum nitride.

Connection trenches 130a and 130b are formed to pattern the semiconductor stack 130 to expose the first conductive semiconductor layer 125. The connection grooves 130a are formed to expose the first conductivity type semiconductor layer 125 to which the connection portions 135 of FIGS. 5A and 5B are connected. The connection grooves 130a expose the first conductivity-type semiconductor layer 125 in the regions S1, S2, and S3 of FIG. 5. Side surfaces of the active layer 127 and the second conductivity-type semiconductor layer 129 are exposed on sidewalls of the connection grooves 130a.

The compound semiconductor layers may be patterned using photolithography and etching processes to form the interconnection grooves 130a and 130b, which is generally similar to mesa etching. However, in the mesa etching process, the connection grooves are connected to each other, but in the present invention, the connection grooves 130a are separated from each other. Accordingly, the area of the connection grooves 130a can be reduced, and thus, it is advantageous to planarize the separation insulating layer and the bonding metal in the future, and as a result, the substrate can be attached stably.

Meanwhile, the connection grooves (holes) 130b are formed in a region where electrode pads are to be formed, and a plurality of connection grooves 130b are formed in each region.

Referring to FIG. 7, distributed Bragg reflective layers 131 and 131a are formed on the semiconductor stack 130. The distributed Bragg reflective layers 131 and 131a have openings exposing the second conductivity type semiconductor layer 129 and openings exposing the first conductivity type semiconductor layer 125. The distributed Bragg reflective layers 131 and 131a are formed by using a lift-off process or alternately stack two layers having different refractive indices, and then the second conductivity-type semiconductor layer 129 and the first conductivity-type semiconductor layer in the connection grooves. And may be formed by patterning to expose 127.

The distributed Bragg reflective layer 131 is formed on the second conductivity type semiconductor layer 129 and is also formed in the region where the separation grooves 161 of FIGS. 5A and 5B are to be formed. The distributed Bragg reflective layer 131a covers side surfaces of the active layer 127 and the second conductivity-type semiconductor layer 129 exposed to the connection grooves 130a. The distributed Bragg reflective layer 131a is formed to prevent the first conductive semiconductor layer and the second conductive semiconductor layer from being shorted by the connecting portions.

The distributed Bragg reflective layer 131 may be formed by alternately stacking two layers having different refractive indices, for example, SiO 2 and TiO 2 or SiO 2 and Nb 2 O 5. In this case, by forming the first and last layers of the distributed Bragg reflective layer 131 as SiO 2, cracks may be prevented from being formed in the Distributed Bragg reflective layers 131 and 131a and the distributed Bragg reflective layer 131 may be protected.

Referring to FIG. 8, an ohmic contact layer 133 is formed on the distributed Bragg reflective layer 131. The ohmic contact layer 133 covers the openings in the distributed Bragg reflective layer 131 and is connected to the second conductive semiconductor layer 129. The ohmic contact layer 133 may be formed of a reflective layer such as Ag or Al, or a transparent conductive layer such as Ni / Au, ITO, ZnO, or TCO. When the ohmic contact layer 133 includes a reflective layer, light may be reflected together with the distributed Bragg reflective layer 131. In addition, when the ohmic contact layer 133 is formed of a transparent conductive oxide film, stable contact resistance characteristics may be exhibited.

Referring to FIG. 9, the connecting portions 135a covering the ohmic contact layer 133 and the connecting portions 135b connected to the first conductive semiconductor layers 125 are formed. These connection parts are connected to each other to form a connection part 135 connecting the light emitting cells to each other. The connection parts 135 may electrically connect the second conductive semiconductor layers 129 or electrically connect the first conductive semiconductor layer 125 and the second conductive semiconductor layer 129. The connection parts 135a may surround the ohmic contact layer 133.

Referring to FIG. 10, a separation insulating layer 137 is formed on almost the entire surface of the sacrificial substrate 121 on which the connecting portions 135 are formed. The isolation insulating layer 137 covers the connection portions 135 and the semiconductor stack 130. The isolation insulating layer 137 may be formed of a silicon oxide film or a silicon nitride film. An adhesive layer 139 may be formed on the separation insulating layer 137, a bonding metal 141 may be formed on the adhesive layer 139, and the substrate 151 may be bonded. The bonding metal 147 may be formed of, for example, AuSn (80 / 20wt%). The substrate 151 is not particularly limited, but may be a substrate having the same thermal expansion coefficient as the sacrificial substrate 121.

Referring to FIG. 11, the sacrificial substrate 121 is subsequently removed and the first conductivity type semiconductor layer 125 is exposed. The sacrificial substrate 121 may be separated by laser lift off (LLO) technology or other mechanical or chemical methods. At this time, the buffer layer is also removed to expose the first conductivity-type semiconductor layer 125.

Referring to FIG. 12, separation grooves 161 are formed to separate the exposed first conductive semiconductor layer 125 into a plurality of regions S1, S2, S3, and P. The separation grooves 161 separate the semiconductor stack 130 into a light emitting cell region or a common light emitting cell region. The separation grooves 161 are formed by etching the semiconductor stack 130 until the distribution Bragg reflective layer 131 or 131a is exposed. In this case, the distribution Bragg reflective layer 131 prevents the connection portions 135 from being exposed. Sidewalls of the isolation grooves 161 may include the semiconductor stack 130, and side surfaces of the first conductive semiconductor layer 125, the active layer 127, and the second conductive semiconductor layer 129 may be exposed in the isolation grooves. . Meanwhile, a roughened surface R may be formed on the first conductive semiconductor layer 125 by PEC (photoelectric chemistry) etching.

Although the distribution Bragg reflective layer 131 or 131a is described as exposing the separation grooves 161, an insulation pattern other than the distribution Bragg reflection layer may be formed in the region where the separation grooves 161 are to be formed. have.

Meanwhile, a light emitting device including a protective insulating layer 163 and electrode pads 165 formed on the first conductive semiconductor layer 125 and including the plurality of regions S1, S2, S3, and P. The substrate 151 is separated into units to form a single chip light emitting device.

Although the embodiments of the present invention have been described above by way of example, the present invention is not limited to the above-described embodiments and may be variously modified and changed by those skilled in the art without departing from the spirit of the present invention. . Such modifications and variations are included in the scope of the present invention as defined in the following claims.

Claims (21)

Board;
A semiconductor stack disposed on the substrate, the semiconductor stack including an upper semiconductor layer of a first conductivity type, an active layer, and a lower semiconductor layer of a second conductivity type;
Isolation trenches for separating the semiconductor stack into a plurality of regions;
Connectors disposed between the substrate and the semiconductor stack and electrically connecting the plurality of regions to each other; And
A distributed Bragg reflective layer having a multilayer structure positioned between the semiconductor stack and the connecting portions,
The connections are electrically connected to the semiconductor stack through the distributed Bragg reflective layer,
A portion of the distribution Bragg reflective layer is positioned between the separation grooves and the connection portion. The method according to claim 1,
At least some of the separation grooves penetrate the upper semiconductor layer of the first conductivity type, the active layer and the lower semiconductor layer of the second conductivity type. The method according to claim 1,
The separation grooves penetrate the upper semiconductor layer of the first conductivity type, the active layer and the lower semiconductor layer of the second conductivity type. The method according to claim 1,
At least one of the plurality of regions has a single light emitting cell,
A light emitting device in which the connecting portions are respectively connected to the first conductive upper semiconductor layer and the second conductive lower semiconductor layer of the single light emitting cell. The method of claim 4,
A connecting portion connected to the first conductive upper semiconductor layer is connected to the second conductive lower semiconductor layer in another region;
And a connection part connected to the second conductive lower semiconductor layer is connected to the first conductive upper semiconductor layer in another region. The method according to claim 1,
At least one of the plurality of regions has a common light emitting cell sharing the first conductive upper semiconductor layer,
The connection part is connected to the first conductivity type upper semiconductor layer shared by the common light emitting cell,
A light emitting device in which the connecting portions are respectively connected to the second conductive lower semiconductor layers of the common light emitting cell; The method of claim 6,
A connecting portion connected to the first conductive upper semiconductor layer is connected to the second conductive lower semiconductor layer in another region;
At least one of the connection parts connected to the second conductive lower semiconductor layers is connected to a second conductive lower semiconductor layer of an adjacent common light emitting cell. Claim 1
A bonding metal located between the substrate and the semiconductor stack; And
And a separation insulating layer separating the connecting portions from the bonding metal. The method according to claim 1,
And an ohmic contact layer connected to the second conductive lower semiconductor layer through the distributed Bragg reflective layer, wherein the connecting portions are electrically connected to the second conductive lower semiconductor layer of the semiconductor stack through the ohmic contact layer. Light emitting element. The method according to claim 9,
The ohmic contact layer is a light emitting device formed of a reflective layer or a transparent conductive layer. The method according to claim 1,
And a protective insulating layer on the semiconductor stack and covering the semiconductor stack. The method according to claim 1,
Further comprising electrode pads,
And the electrode pads are respectively formed on one of the plurality of regions and connected to the first conductive upper semiconductor layer. The method of claim 12,
The region in which the electrode pad is formed has holes penetrating through the second conductivity type lower semiconductor layer and the active layer,
And a connection part electrically connected to the first conductivity type upper semiconductor layer through the holes. The method according to claim 1,
And a series array of at least one light emitting cells formed by the connections. Forming a semiconductor stack on the sacrificial substrate, the semiconductor stack comprising a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer,
Patterning the semiconductor stack to form a plurality of connection trenches exposing the first conductivity type semiconductor layer,
Forming a multilayer Bragg reflective layer on the semiconductor stack, the distribution Bragg reflecting layer openings exposing the second conductive semiconductor layer and openings exposing the first conductive semiconductor layer exposed to the connection grooves; Openings exposing the first conductivity type semiconductor layer are located in the connection grooves,
Connecting portions electrically connecting the plurality of regions of the semiconductor stack to each other,
Forming a separation insulating layer covering the connecting portions,
Bonding a substrate on the separation insulating layer,
Removing the sacrificial substrate to expose the first conductivity type semiconductor layer,
And patterning the semiconductor stack until the distribution Bragg reflective layer is exposed to form separation grooves separating the plurality of regions from each other. The method according to claim 15,
The plurality of regions each including the connection grooves,
The connection parts are electrically connected to the first conductivity type semiconductor layers exposed by the connection grooves and the second conductivity type semiconductor layers on the plurality of regions to electrically connect the plurality of regions. . The method according to claim 15,
And forming an ohmic contact layer contacting second conductive semiconductor layers in the plurality of regions before forming the connection portions. 18. The method of claim 17,
The ohmic contact layer is a light emitting device manufacturing method formed of a reflective layer or a transparent conductive layer. The method according to claim 15,
And forming a roughened surface on the exposed first conductive semiconductor layer by removing the sacrificial substrate. The method of claim 19,
And forming a protective insulating layer covering the first conductive semiconductor layer, wherein the protective insulating layer fills the separation grooves. The method according to claim 15,
The method may further include forming electrode pads on the exposed first conductive semiconductor layer by removing the sacrificial substrate.
The electrode pads are each formed on one of the plurality of regions separated by the separation grooves,
And a plurality of connection grooves formed in regions where the electrode pads are formed.

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