Patent Publication Number: US-11641006-B2

Title: Semiconductor device

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a U.S. National Stage Application under 35 U.S.C. § 371 of PCT Application No. PCT/KR2019/003348, filed Mar. 22, 2019, which claims priority to Korean Patent Application No. 10-2018-0039195, filed Apr. 4, 2018, whose entire disclosures are hereby incorporated by reference. 
     TECHNICAL FIELD 
     Embodiments relate to a semiconductor device. 
     BACKGROUND ART 
     A semiconductor device including a compound, such as GaN and AlGaN, has many advantages, such as wide and adjustable band-gap energy, and thus may be diversely used for light-emitting devices, light-receiving devices, various diodes, and the like. 
     In particular, a light-emitting device, such as a light-emitting diode or laser diode, using a III-V group or II-VI group compound semiconductor material can realize various colors, such as red, green, blue, or ultraviolet light due to the development of thin-film growth technology and device materials. Also, the light-emitting device can realize efficient white light by using a fluorescent material or combining colors and has the advantages of low power consumption, semi-permanent lifetime, fast response time, safety, and environmental friendliness as compared to existing light sources such as fluorescent lamps and incandescent lamps. 
     Moreover, due to the development of device materials, when a light-receiving device, such as a photodetector or a solar cell, is fabricated using a III-V group or II-VI group compound semiconductor material, the light-receiving device generates a photocurrent by absorbing light in various wavelength regions, and thus it is possible to use light in various wavelength regions from a gamma-ray region to a radio-wave region. In addition, the light-receiving device has the advantages of fast response time, safety, environmental friendliness, and ease of adjustment of device materials and thus may be easily used for power control or ultra-high frequency circuits or communication modules. 
     Accordingly, the applications of semiconductor devices are being expanded to transmission modules of optical communication means, light-emitting diode backlights which replace cold cathode fluorescent lamps (CCFLs) constituting the backlights of liquid crystal display (LCD) devices, white light-emitting diode lighting devices which may replace fluorescent lamps or incandescent lamps, vehicle headlights, traffic lights, sensors for sensing gas or fire, and the like. In addition, the applications of semiconductor devices may be expanded to high-frequency application circuits, other power control devices, and communication modules. 
     In particular, light-emitting devices that emit light in an ultraviolet wavelength range can be used for curing, medical, and sterilization purposes by curing or sterilizing. 
     Recently, research on ultraviolet light-emitting devices has been actively conducted, but there are problems in that the ultraviolet light-emitting devices are still difficult to realize in a vertical form and are peeled off in the process of separating a substrate and oxidized by moisture such that optical output power is lowered. 
     SUMMARY 
     An embodiment is directed to providing a vertical-type semiconductor device. 
     An embodiment is also directed to providing a semiconductor device with excellent light extraction efficiency. 
     An embodiment is also directed to providing a semiconductor device with an excellent current spreading effect. 
     Objectives to be solved by the embodiment are not limited to the above-described objective and will include objectives and effectiveness which may be identified by solutions for the objectives and the embodiments described below. 
     A semiconductor device according to an embodiment includes a semiconductor structure including a first conductive type semiconductor layer, a second conductive type semiconductor layer, and an active layer disposed between the first conductive type semiconductor layer and the second conductive type semiconductor layer, a first electrode electrically connected to the first conductive type semiconductor layer, a second electrode electrically connected to the second conductive type semiconductor layer, and a reflective layer disposed below the second electrode, wherein the second conductive type semiconductor layer includes a first sub-layer and a second sub-layer that is disposed between the first sub-layer and the active layer and has an aluminum (Al) composition higher than an Al composition of the first sub-layer, the reflective layer is in contact with a bottom surface of the second sub-layer, and the second electrode is in contact with the first sub-layer. 
     Each of the first sub-layer and the second sub-layer may include aluminum (Al) and gallium (Ga), and in a system containing Al and Ga, the Al composition of the first sub-layer may be in a range of 30% to 50%, and the Al composition of the second sub-layer may be in a range of 50% to 80%. 
     The Al composition of each of the first sub-layer and the second sub-layer may gradually increase in a direction toward the first conductive type semiconductor layer from the second electrode. 
     A ratio of the Al composition of the second sub-layer and the Al composition of the first sub-layer may be in a range of 1:0.375 to 1:1. 
     The semiconductor structure may further include a recess disposed to a partial region of the first conductive type semiconductor layer through the second conductive type semiconductor layer and the active layer, the first electrode may be disposed in the recess, and the reflective layer and the second electrode may be disposed to surround the recess. 
     The first sub-layer may be disposed on a portion of the bottom surface of the second sub-layer, a side surface of the first sub-layer may be in contact with the bottom surface of the second sub-layer, the second electrode may be disposed below the first sub-layer, and the reflective layer may be disposed to be in contact with a side surface and a bottom surface of the second electrode. 
     A ratio of an area of the first sub-layer and an area of the second sub-layer may be in a range of 1:1.01 to 1:1.5, a ratio of an area of the first electrode and an area of the second electrode may be in a range of 1:3.88 to 1:5.8, and a ratio of an area of the reflective layer and the area of the second electrode may be in a range of 1:2.4 to 1:3.6. 
     The semiconductor device may further include a first insulating layer disposed below the semiconductor structure and the reflective layer, a first conductive layer electrically connected to the first electrode, a second conductive layer disposed above the first conductive layer and electrically connected to the reflective layer, a second insulating layer disposed between the first conductive layer and the second conductive layer, a bonding layer disposed below the second conductive layer, and a substrate disposed below the bonding layer. 
     The reflective layer may extend toward the bottom surface of the second sub-layer from a bottom surface of the first sub-layer. 
     The reflective layer may be in contact with a side surface of the first sub-layer and may surround the first sub-layer. 
     Advantageous Effects 
     According to embodiments, a semiconductor device can be implemented as a vertical type. 
     Further, a light-emitting device with excellent light extraction efficiency can be manufactured. 
     Various advantages and effects of the present invention are not limited to the above description and can be more easily understood through the description of specific exemplary embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cross-sectional view of a semiconductor device according to one embodiment. 
         FIG.  2    is an enlarged view of portion K in  FIG.  1   . 
         FIG.  3    is a conceptual diagram illustrating a process in which light is reflected by a reflective layer. 
         FIG.  4 A  is a graph illustrating an aluminum (Al) composition of a second conductive type semiconductor layer. 
         FIG.  4 B  is a view illustrating a modified example of  FIG.  4 A . 
         FIG.  5    is a plan view of the semiconductor device according to the embodiment. 
         FIG.  6    is an enlarged view of portion L in  FIG.  5   . 
         FIG.  7    is a plan view of a semiconductor device according to another embodiment. 
         FIG.  8    is a cross-sectional view taken along line AA′ in  FIG.  7   . 
         FIG.  9    is a conceptual diagram of a package of the semiconductor device according to one embodiment of the present invention. 
         FIG.  10    is a plan view of the package of the semiconductor device according to one embodiment of the present invention. 
         FIGS.  11 A to  11 L  are sequence diagrams for describing a method of manufacturing a semiconductor device according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     While the present invention is susceptible to various modifications and alternative forms, particular embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the present invention to the particular forms disclosed, but on the contrary, the present invention is to cover particular modifications, equivalents, and alternatives falling within the spirit and scope of the present invention. 
     It will be understood that, although the terms “first,” “second,” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and a second element could similarly be termed a first element without departing from the scope of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the another element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     The terms used herein are for the purpose of describing particular exemplary embodiments only and are not intended to be limiting to the present invention. As used herein, singular forms are intended to include plural forms as well, unless the context clearly indicates otherwise. In the present application, it will be further understood that the terms “comprise,” “comprising,” “include,” and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups thereof but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. 
     Unless otherwise defined, all terms used herein including technical or scientific terms have the same meanings as those generally understood by one of ordinary skill in the art. It should be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and are not to be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Regardless of reference numerals, like numbers refer to like elements throughout the description of the figures, and the description of the same elements will be not reiterated. 
     A light-emitting structure (identical to a semiconductor structure to be described below) according to an embodiment of the present invention may output light in an ultraviolet wavelength range. As an example, the light-emitting structure may output light in a near-ultraviolet wavelength range (UV-A), light in a far-ultraviolet wavelength range (UV-B), or light in a deep ultraviolet wavelength range (UV-C). The wavelength range may be determined by an aluminum (Al) composition ratio of a light-emitting structure. 
     As an example, the UV-A may have a peak wavelength in a range of 320 nm to 420 nm, the UV-B may have a peak wavelength in a range of 280 nm to 320 nm, and the UV-C may have a peak wavelength in a range of 100 nm to 280 nm. 
       FIG.  1    is a conceptual diagram of a semiconductor device according to one embodiment,  FIG.  2    is an enlarged view of portion K in  FIG.  1   , and  FIG.  3    is a conceptual diagram illustrating a process in which light is reflected by a reflective layer. 
     First, referring to  FIG.  1   , a semiconductor device  10  according to one embodiment may include a semiconductor structure  120  including a first conductive type semiconductor layer  124 , an active layer  126 , and a second conductive type semiconductor layer  127 , a first electrode  142  electrically connected to the first conductive type semiconductor layer  124 , a second electrode  146  electrically connected to the second conductive type semiconductor layer  127 , and a reflective layer  147  disposed below the second electrode  146 . 
     First, the semiconductor structure  120  may include the first conductive type semiconductor layer  124 , the active layer  126 , and the second conductive type semiconductor layer  127  and may further include a recess  128  that passes through the second conductive type semiconductor layer  127  and the active layer  126  and exposes to a partial region of the first conductive type semiconductor layer  124 . 
     The first conductive type semiconductor layer  124  may be implemented with a compound semiconductor including a III-V group element, a II-VI group element, or the like and may be doped with a first dopant. The first conductive type semiconductor layer  124  may be made of semiconductor materials having a composition formula of Inx1Aly1Ga1-x1-y1N (0≤x1&lt;=1, 0&lt;=y1&lt;=1, and 0&lt;=x1+y1&lt;=1), for example, semiconductor materials selected from among GaN, AlGaN, InGaN, InAlGaN, and the like. In addition, the first dopant may be an n-type dopant such as silicon (Si), germanium (Ge), tin (Sn), selenium (Se), or tellurium (Te). When the first dopant is an n-type dopant, the first conductive type semiconductor layer  124  doped with the first dopant may be an n-type semiconductor layer. 
     The active layer  126  is disposed between the first conductive type semiconductor layer  124  and the second conductive type semiconductor layer  127 . The active layer  126  is a layer at which electrons (or holes) injected through the first conductive type semiconductor layer  124  and holes (or electrons) injected through the second conductive type semiconductor layer  127  meet. The active layer  126  may transition to a low energy level due to the recombination of electrons and holes and emit light having an ultraviolet wavelength. 
     The active layer  126  may have one structure among a single well structure, a multi-well structure, a single quantum well structure, a multi-quantum well (MQW) structure, a quantum dot structure, and a quantum wire structure, but the structure of the active layer  126  is not limited thereto. 
     For example, the active layer  126  may include a plurality of well layers and a plurality of barrier layers. Each of the well layers and the barrier layers may have a composition formula of Inx2Aly2Ga1-x2-y2N (0≤x2&lt;=1, 0&lt;y2&lt;=1, and 0&lt;=x2+y2&lt;=1). An Al composition of the well layer may vary according to a wavelength of emitted light. 
     The second conductive type semiconductor layer  127  may be formed on the active layer  126  and implemented with a compound semiconductor including a III-V group element, a II-VI group element, or the like, and the second conductive type semiconductor layer  127  may be doped with a second dopant. The second conductive type semiconductor layer  127  may be made of semiconductor materials having a composition formula of Inx5Aly2Ga1-x5-y2N (0≤x5&lt;=1, 0&lt;=y2&lt;=1, and 0&lt;=x5+y2&lt;=1) or materials selected from among AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. When the second dopant is a p-type dopant such as magnesium (Mg), zinc (Zn), calcium (Ca), strontium (Sr), barium (Ba), or the like, the second conductive type semiconductor layer  127  doped with the second dopant may be a p-type semiconductor layer. 
     The second conductive type semiconductor layer  127  may include a plurality of layers, for example, a first sub-layer  127   a  and a second sub-layer  127   b . In addition, an Al composition of the first sub-layer  127   a  may be lower than an Al composition of the second sub-layer  127   b . Detailed descriptions of the first sub-layer  127   a  and the second sub-layer  127   b  will be given below. 
     An electron blocking layer (not shown) may be disposed between the active layer  126  and the second conductive type semiconductor layer  127 . The electron blocking layer (not shown) may block electrons supplied from the first conductive type semiconductor layer  124  from flowing out to the second conductive type semiconductor layer  127 , thereby increasing the probability that electrons and holes are recombined with each other in the active layer  126 . An energy band gap of the electron blocking layer (not shown) may be greater than an energy band gap of the active layer  126  and/or the second conductive type semiconductor layer  127 . 
     The electron blocking layer (not shown) may be selected from semiconductor materials having a composition formula of Inx1Aly1Ga1-x1-y1N (0≤x1&lt;=1, 0&lt;=y1&lt;=1, and 0&lt;=x1+y1&lt;=1), for example, semiconductor materials selected from among AlGaN, InGaN, InAlGaN, and the like, but the present invention is not limited thereto. In the electron blocking layer (not shown), a layer having a high Al composition and a layer having a low Al composition may be alternately disposed. 
     A plurality of recesses  128  may be formed in the semiconductor device  10 , and the number of recesses  128  may be adjusted to adjust optical output power of the semiconductor device  10 . 
     The first electrode  142  may be disposed in the recess  128  and may be electrically connected to the first conductive type semiconductor layer  124 . 
     The first electrode  142  may be an ohmic electrode and may include at least one among indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), indium gallium tin oxide (IGTO), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), IZO nitride (IZON), Al—Ga ZnO (AGZO), In—Ga ZnO (IGZO), ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au, Ni/IrOx/Au/ITO, silver (Ag), nickel (Ni), chromium (Cr), titanium (Ti), aluminum (Al), rhodium (Rh), palladium (Pd), iridium (Ir), tin (Sn), indium (In), ruthenium (Ru), magnesium (Mg), zinc (Zn), platinum (Pt), gold (Au), and hafnium (Hf), but the present invention is not limited to such materials. 
     The second electrode  146  may be disposed below the second conductive type semiconductor layer  127  and electrically connected to the second conductive type semiconductor layer  127 . Specifically, the second electrode  146  may be disposed below the first sub-layer  127   a  of the second conductive type semiconductor layer  127  so that the first sub-layer  127   a  may be disposed between the second sub-layer  127   b  and the second electrode  146 . 
     The second electrode  146  may be an ohmic electrode and may include at least one among ITO, IZO, IZTO, IAZO, IGZO, IGTO, AZO, ATO, GZO, IZON, AGZO, In—Ga ZnO (IGZO), ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au, Ni/IrOx/Au/ITO, ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au, Ni/IrOx/Au/ITO, Ag, Ni, Cr, Ti, Al, Rh, Pd, Ir, Sn, In, Ru, Mg, Zn, Pt, Au, and Hf, but the present invention is not limited to such materials. 
     The reflective layer  147  may be disposed below the second electrode  146  and may be electrically connected to the second electrode  146 . In addition, the reflective layer  147  may reflect light, which is emitted toward the reflective layer  147  from the active layer  122 , to an upper portion of the semiconductor structure  120 . 
     The reflective layer  147  may include a material having conductivity and a reflective function and may include, for example, one of Ag and Rh, but the present invention is not limited to such materials. In addition, the reflective layer  147  may include aluminum, but in this case, step coverage is relatively low such that only a portion of the second electrode  146  may be covered. However, the present invention is not limited to such a material. 
     Further, the semiconductor device  10  according to the embodiment may further include a first insulating layer  131  disposed below the semiconductor structure  120 , a second conductive layer  150  disposed below the reflective layer  147 , a second insulating layer  132  disposed below the second conductive layer  150 , a first conductive layer  165  electrically connected to the first electrode  142 , a bonding layer  160  disposed below the first conductive layer  165 , and a substrate  170  disposed below the bonding layer  160 . 
     First, the first insulating layer  131  may be disposed between the semiconductor structure  120  and the substrate  170  or may be disposed inside the recess  128 . Specifically, the first insulating layer  131  may electrically insulate the first conductive type semiconductor layer  121  exposed by the recess  128 , the second conductive type semiconductor layer  123 , and the active layer  122  from each other. In addition, the first insulating layer  131  may electrically insulate the first electrode  142  from the active layer  122  and the second conductive type semiconductor layer  123 . 
     In addition, the first insulating layer  131  may be made of a dielectric or an insulator. For example, the first insulating layer  131  may be made of an oxide and/or a nitride and may optionally include, for example, at least one selected from the group consisting of SiO2, SixOy, Si3N4, SixNy, SiOxNy, Al2O3, TiO2, AlN, and the like, but the present invention is not limited to such materials. 
     In addition, the first insulating layer  131  may be formed as a single-layer or a multi-layer. The first insulating layer  131  may be formed as the multi-layer, and thus, an interface between adjacent layers may be formed. 
     When the first insulating layer  131  is formed as the single-layer, a path, through which external moisture or contaminants may permeate, may be exposed due to internal defects. On the other hand, when the first insulating layer  131  is formed as the multi-layer, internal defects may be prevented from being exposed to the outside, thereby reducing external moisture and contaminants permeating into the semiconductor structure  120  through the first insulating layer  131 . However, the present invention is not limited thereto, and when the internal defects of the first insulating layer  131  exposed to the outside are small, the first insulating layer  131  may be formed as the single-layer. 
     Further, the first insulating layer  131  may be a distributed Bragg reflector (DBR) having a multi-layer structure that includes Si oxide or a Ti compound. However, the present invention is not limited to the structure, and the first insulating layer  131  may have various reflective structures. Thus, the first insulating layer  131  may improve light extraction efficiency. 
     The second conductive layer  150  may be disposed below the reflective layer  147  and the first insulating layer  131  to partially cover the reflective layer  147  and the first insulating layer  131 . Accordingly, an electrode pad  166 , the second conductive layer  150 , the reflective layer  147 , and the second electrode  146  may provide one electrical channel. 
     The second conductive layer  150  may be disposed to surround the reflective layer  147  and may be disposed below the reflective layer  147 , the second electrode  146 , and the first insulating layer  131 . The second conductive layer  150  may include a material having high adhesion with the first insulating layer  131  and may be made, for example, of at least one material selected from the group consisting of materials such as Cr, Ti, Ni, and Au, or an alloy thereof, and may be formed of a single-layer or a plurality of layers. However, the present invention is not limited to such materials and structures. 
     The second conductive layer  150  may be disposed between the first insulating layer  131  and the second insulating layer  132  and may be protected from permeation of external moisture or contaminants by the first insulating layer  131  and the second insulating layer  132 . In addition, the second conductive layer  150  may be disposed inside the semiconductor device  10  and may be surrounded by the second insulating layer  132  so as not to be exposed at an outermost side surface of the semiconductor device  10 . 
     The second insulating layer  132  may electrically insulate the second electrode  146 , the reflective layer  147 , and the second conductive layer  150  from the first conductive layer  165 . 
     The second insulating layer  132  and the first insulating layer  131  may be made of the same material and may be made of at least one selected from the group consisting of SiO2, SixOy, Si3N4, SixNy, SiOxNy, Al2O3, TiO2, and AlN. However, the present invention is not limited to such materials, and the second insulating layer  132  may be made of a different material from the first insulating layer  131 . 
     Further, according to the embodiment, since the second insulating layer  132  is disposed on the first insulating layer  131  between the first electrode  142  and the second electrode  146 , when defects are generated in the second insulating layer  132 , the first insulating layer  131  may secondarily prevent permeation of external moisture and/or other contaminants. As an example, when the first insulating layer  131  and the second insulating layer  132  are formed as one layer, cracks, internal defects, and the like may be easily propagated in a vertical direction. Accordingly, external moisture or contaminants may permeate into the semiconductor structure  120  through defects exposed to the outside. 
     Further, the second insulating layer  132  and the first insulating layer  131  may be formed integrally so that a boundary between the first insulating layer  131  and the second insulating layer  132  may not be present. 
     However, according to the embodiment, since the second insulating layer  132  is separately disposed on the first insulating layer  131 , the defects generated in the first insulating layer  131  are difficult to propagate to the second insulating layer  132 . Thus, the first insulating layer  131  and the second insulating layer  132  may block the propagation of defects occurring at the interface. 
     The first conductive layer  165  may be disposed below the second insulating layer  132  and the first reflective layer  147 . The first conductive layer  165  may pass through the second insulating layer  132  to be electrically connected to the first electrode  142  and may also be electrically connected to the substrate  170  therebelow. Accordingly, the first conductive layer  165  may have an electrical channel with the first electrode  142  and the substrate  170 . The first conductive layer  165  may be made of at least one material selected from the group consisting of materials such as Cr, Ti, Ni, and Au, or an alloy thereof and may be formed of a single-layer or a plurality of layers. In addition, the first conductive layer  165  may be entirely disposed within the semiconductor device  10 . 
     As described above, the electrode pad  166  may pass through the first insulating layer  131  to be disposed on the second conductive layer  150  and may be electrically connected to the second conductive type semiconductor layer  123  so as to have an electrical channel with the second conductive layer  150 , the reflective layer  147 , and the second electrode  146 . 
     The electrode pad  166  may have a single-layer or multi-layered structure and may include Ti, Ni, Ag, and Au. As an example, the electrode pad  166  may have a structure of Ti/Ni/Ti/Ni/Ti/Au. 
     The bonding layer  160  may include a conductive material. As an example, the bonding layer  160  may include a material selected from the group consisting of gold, tin, indium, aluminum, silicon, silver, nickel, and copper, or an alloy thereof. 
     The substrate  170  may be disposed below the bonding layer  160  and may be made of a conductive material. As an example, the substrate  170  may include a metal or a semiconductor material. The substrate  170  may include a metal having high electrical conductivity and/or thermal conductivity. In this case, the substrate  170  may rapidly discharge heat, which is generated when the semiconductor device  10  operates, to the outside. In addition, when the substrate  170  is made of a conductive material, the first electrode  142  may be supplied with a current from the outside through the substrate  170 . 
     A passivation layer  180  may be disposed to surround an outer surface of the semiconductor device  10 . Specifically, the passivation layer  180  may be disposed on top surfaces of the semiconductor structure  120 , the first insulating layer  131 , and the electrode pad  166  and may be disposed to expose a portion of the electrode pad  166 . Accordingly, the electrode pad  166  may be electrically connected to the outside through wire bonding or the like. 
     The top surface of the semiconductor structure  120  may be formed in an uneven shape. For example, a top surface of the first conductive type semiconductor layer  124  may have an uneven structure, and the uneven structure enables the extraction efficiency of light emitted from the semiconductor structure  120  to be improved. The uneven structure may have different average heights based on an ultraviolet wavelength and may have various heights based on the peak wavelength of light emitted to the semiconductor structure  120 . Accordingly, the light extraction efficiency of the semiconductor device  10  may be improved. 
     Referring to  FIGS.  2  and  3   , as described above, in the second conductive type semiconductor layer  127 , the Al composition of the first sub-layer  127   a  may be lower than the Al composition of the second sub-layer  127   b . In addition, each of the first sub-layer  127   a  and the second sub-layer  127   b  may be composed of a system containing Al and gallium (Ga). For example, the first sub-layer  127   a  and the second sub-layer  127   b  may each include AlGaN and InAlGaN, but the present invention is not limited thereto. 
     Specifically, the Al composition of the second sub-layer  127   b  may be in a range of 50% to 80%. In addition, when the Al composition of the second sub-layer  127   b  is greater than or equal to 50%, the problem of absorbing light may be reduced, and when the Al composition of the second sub-layer  127   b  is less than or equal to 80%, the problem of degrading current injection efficiency may be reduced. As an example, when the Al composition of the well layer is 40%, the Al composition of the second sub-layer  127   b  may be 50%. 
     The Al composition of the first sub-layer  127   a  may be lower than the Al composition of the well layer. When the Al composition of the first sub-layer  127   a  is higher than the Al composition of the well layer, the first sub-layer  127   a  may not be sufficiently ohmic with the second electrode  146  due to an increase in resistance therebetween, and current injection efficiency may be reduced. 
     The Al composition of the first sub-layer  127   a  may be greater than or equal to 30% and less than or equal to 50%. When the Al composition is less than or equal to 50%, it is possible to lower the resistance with the second electrode. When the Al composition is greater than or equal to 30%, the problem of absorbing light in the first sub-layer  127   a  may be reduced. 
     In the semiconductor device according to the embodiment, a ratio of the Al composition of the second sub-layer and the Al composition of the first sub-layer may be in a range of 1:0.375 to 1:1. When the Al composition ratio is less than 1:0.375, the light absorbed by the first sub-layer  127   a  increases and thus the light extraction may be degraded, and when the Al composition ratio is greater than 1:1, the first sub-layer  127   a  may not be sufficiently ohmic with the second electrode due to an increase in resistance therebetween and thus electrical characteristics may be degraded. 
     A thickness T 2  of the first sub-layer  127   a  may be in a range of 1 nm to 30 nm. The first sub-layer  127   a  may absorb ultraviolet light so that optical output power may be improved by controlling the thickness of the first sub-layer  127   a  to be as thin as possible. 
     In addition, when the thickness of the first sub-layer  127   a  is greater than or equal to 1 nm, it is possible to decrease resistance of the first sub-layer  127   a  and thus improve electrical characteristics of the semiconductor device. Also, when the thickness is less than or equal to 30 nm, it is possible to improve optical output power efficiency by decreasing the amount of light absorbed by the first sub-layer  127   a.    
     In addition, a thickness T 3  of the second sub-layer  127   b  may be greater than 10 nm and less than 50 nm. As an example, the thickness of the second sub-layer  127   b  may be 25 nm. When the thickness of the second sub-layer  127   b  is greater than or equal to 10 nm, it is possible to secure current-spreading characteristics of the second sub-layer  127   b . In addition, when the thickness is less than or equal to 50 nm, it is possible to secure injection efficiency for second carriers injected into the active layer  126  and lower an absorption rate of light emitted from the active layer  126  in the second sub-layer  127   b.    
     In addition, the thickness T 2  of the first sub-layer  127   a  may be different from the thickness T 3  of the second sub-layer  127   b . As an embodiment, the thickness T 2  of the first sub-layer  127   a  may be less than the thickness T 3  of the second sub-layer  127   b . A ratio of the thickness of the first sub-layer  127   a  and the thickness of the second sub-layer  127   b  may be in a range of 1:1.5 to 1:20. When the thickness ratio is greater than 1:1.5, the thickness of the second sub-layer  127   b  increases, and thus it is possible to improve current injection efficiency. In addition, when the thickness ratio is less than 1:20, the thickness of the first sub-layer  127   a  increases, and thus the problem of degrading crystallinity may be reduced. When the first sub-layer  127   a  is too thin, it is necessary to rapidly change the Al composition in the range of the thickness, and thus the crystallinity may be degraded. 
     In addition, the Al composition of the first sub-layer  127   a  may decrease in a direction away from the active layer  126 . The first sub-layer  127   a  may have a lower Al composition than the well layer in order to achieve low contact resistance with the second electrode  146 . Accordingly, the first sub-layer  127   a  may absorb a portion of the light emitted from the active layer  126  as described above. 
     In addition, a ratio of the thickness T 2  of the first sub-layer  127   a  and a total thickness T 1  of the second conductive type semiconductor layer  127  may be 1:3 to 1:70. When the thickness ratio is greater than 1:3, the first sub-layer  127   a  may secure electrical characteristics (e.g., an operating voltage) of the semiconductor device. When the thickness ratio is less than 1:70, the first sub-layer  127   a  may secure optical characteristics (e.g., optical output power) of the semiconductor device. 
     Further, the Al composition of each of the first sub-layer  127   a  and the second sub-layer  127   b  may gradually increase in a direction toward the first conductive type semiconductor layer  124  from the second electrode  146 . Here, the vertical direction refers to a second direction (a y-axis direction), a first direction (an x-axis direction) is a direction perpendicular to the second direction (the y-axis direction), and a third direction (a z-axis direction) is a direction perpendicular to both the first direction (the x-axis direction) and the second direction (the y-axis direction). For example, the vertical direction may be the same as a direction in which each layer is stacked in the semiconductor structure  120 . In addition, the first sub-layer  127   a  and the second sub-layer  127   b  may be reduced in width differently. For example, a decreasing rate of aluminum in the first sub-layer  127   a  may be less than a decreasing rate of aluminum in the second sub-layer  127   b.    
     Further, the first sub-layer  127   a  may be disposed on a portion of a bottom surface of the second sub-layer  127   b . A side surface  127   a - 1  of the first sub-layer  127   a  may be in contact with a bottom surface  128   b - 2  of the second sub-layer  128   b . For example, the first sub-layer  127   a  may include the side surface  127   a - 1  and a bottom surface  127   a - 2 , and the second sub-layer  127   b  may include the side surface  127   a - 1  and the bottom surface  127   a - 2 . 
     In this case, the side surface  127   a - 1  of the first sub-layer  127   a  may be in contact with the bottom surface  128   b - 2  of the second sub-layer  127   b , and the bottom surface  127   a - 2  of the first sub-layer  127   a  may be in contact with a top surface of the second electrode  146 . Accordingly, the second conductive type semiconductor layer  127  may have a step portion through which a portion of the bottom surface of the second sub-layer  127   b  is exposed. A ratio of an area of the first sub-layer  127   a  and an area of the second sub-layer  127   b  may be in a range of 1:1.01 to 1:1.5. When the area ratio is less than 1:1.01, a problem exists in that a process is difficult and light is absorbed in the first sub-layer  127   a , and when the area ratio is greater than 1:1.5, the area of the second sub-layer  127   b  becomes great such that reliability is degraded due to the step portion between the second sub-layer  127   b  and the first sub-layer  127   a.    
     Accordingly, since the area of the first sub-layer  127   a  and the area of the second sub-layer  127   b  have the above-described area ratio, electrical characteristics may be improved through low resistance between the first sub-layer  127   a  and the second electrode  146  while minimizing the amount of light absorbed by the first sub-layer  127   a . With such a configuration, in the semiconductor device according to the embodiment, electrical characteristics (e.g., an operating voltage) may be secured and optical output power may be improved. 
     In addition, the reflective layer  147  may be disposed below the second conductive type semiconductor layer  127  and the second electrode  146 . Specifically, the reflective layer  147  may be disposed to be in contact with each of the side surface  127   a - 1  of the first sub-layer  127   a  and a bottom surface  127   b - 2  of the second sub-layer  127   b . That is, the reflective layer  147  may be disposed along the side surface  127   a - 1  of the first sub-layer  127   a  to have a stepped structure. In addition, the reflective layer  147  may be disposed to extend toward the bottom surface  127   b - 2  of the second sub-layer  127   b  from the side surface  127   a - 1  of the first sub-layer  127   a . In other words, the reflective layer  147  may be disposed to overlap the first sub-layer  127   a  and the second sub-layer  127   b  in the vertical direction, but, in a partial region, to overlap only the second sub-layer  127   b  in the vertical direction. Further, the reflective layer  147  may partially overlap the first sub-layer  147   a  in the first direction (in the x-axis direction) or in the third direction (the z-axis direction), and, at the lower side of the second electrode  146 , the reflective layer  147  may not overlap the first sub-layer  147   a  in the first direction (in the x-axis direction) or in the third direction (the z-axis direction). Thus, since the reflective layer  147  is in contact with the bottom surface  127   b - 2  of the second sub-layer  127   b , light generated in the active layer  126  may be maximally prevented from being absorbed by the first sub-layer  127   a . In addition, even when light L 1  is emitted toward the substrate  170  through the second sub-layer  127   b , the light L 1  may be reflected toward an upper portion of the semiconductor device by the reflective layer  147  so that optical characteristics (e.g., light extraction efficiency) may be improved. 
     Further, since the reflective layer  147  is disposed to be in contact with the side surface  127   a - 1  of the first sub-layer  127   a , the reflective layer  147  may reflect light L 2 , which is emitted downward through the side surface  127   a - 1  of the first sub-layer  127   a , toward the upper portion of the semiconductor device. 
     Accordingly, in the semiconductor device according to the embodiment, the reflective layer  147  is disposed to surround the second electrode  146  therebelow and the side surface  127   a - 1  of the first sub-layer  127   a  and to be in contact with the bottom surface  127   b - 2  of the second sub-layer  127   b , thereby improving both electrical and optical characteristics. 
       FIG.  4 A  is a graph illustrating an Al composition of the second conductive type semiconductor layer, and  FIG.  4 B  is a view illustrating a modified example of  FIG.  4 A . 
     In  FIGS.  4 A and  4 B , the Al composition of the second conductive type semiconductor layer may vary in a direction in which a thickness thereof increases. The Al composition of the second conductive type semiconductor layer  127  may decrease toward a bottom surface thereof. 
     The Al composition of the second conductive type semiconductor layer  127  may be maintained from a top surface (a point where the thickness is zero, that is, a top surface of the second sub-layer  127   b ) to the bottom surface of the second sub-layer  127   b . In addition, the Al composition may be reduced from the top surface of the first sub-layer  127   a  to the bottom surface of the first sub-layer  127   a . For example, as shown in  FIG.  4 A , the Al composition of the first sub-layer  127   a  may be linearly reduced, and as shown in  FIG.  4 B , the Al composition of the first sub-layer  127   a  may be reduced for each step. For example, the Al composition of the first sub-layer  127   a  may be varied to have a flat region f and an inclined region d. The flat region f is a region in which the Al composition is maintained, and the inclined region d is a region in which the Al composition increases or decreases. 
       FIG.  5    is a plan view of the semiconductor device according to the embodiment, and  FIG.  6    is an enlarged view of portion L in  FIG.  5   . 
     Referring to  FIGS.  5  and  6   , the semiconductor device may include a plurality of first regions  136  separated according to the first electrode  142  in a plan view. The plurality of first regions  136  may be disposed to be spaced apart from each other and may have various shapes. As an example, the first region  136  may have a polygonal shape, such as a hexagonal, octagonal, or triangular shape, or a circular shape. 
     In addition, the reflective layer  147  may be disposed in the first region  136  and, specifically, may be disposed to surround the recess  128  and the first electrode  142  in a plan view (an XZ plane). Accordingly, a current may be injected through the first electrode  142 , and the first electrode  142  and the reflective layer  147  may be disposed in a region having a current density of 30% to 40% based on 100% of a current density of the first electrode  142  so that light generated in a region around the first electrode  142  may be reflected upward. 
     For example, the reflective layer  147  may be disposed to surround the first electrode  142  to reflect the light emitted downward through the second sub-layer toward the upper portion of the semiconductor device, thereby improving light extraction efficiency. 
     In addition, in the semiconductor device, a ratio of an area  51  of the first electrode  142  and an area S 2  of the second electrode  146  may be in a range of 1:3.88 to 1:5.8. When the area ratio is less than 1:3.88, an area for ohmic contact is reduced as the area of the second electrode decreases, and thus there is a problem of increasing resistance. In addition, when the area ratio is greater than 1:5.8, light is absorbed by the second sub-layer in ohmic contact with the second electrode, and thus there is a problem of degrading light extraction. 
     In addition, in the semiconductor device, a ratio of an area S 3  of the reflective layer  147  and the area S 2  of the second electrode  146  may be in a range of 1:2.4 to 1:3.6. When the area ratio is less than 1:2.4, light is absorbed by the second electrode  146  and the first sub-layer, and thus there is a problem of degrading light extraction efficiency. When the area ratio is greater than 1:3.6, there is a problem in that an area of the ohmic contact through the second electrode  146  is reduced. 
     In addition, a minimum width W 1  of the second electrode  146  may be less than a minimum width W 3  of the reflective layer  147 . In addition, a ratio of the minimum width W 1  of the second electrode  146  and the minimum width W 3  of the reflective layer  147  may be in a range of 1:2.5 to 1:3.5. When the width ratio is less than 1:2.5, the reflective layer  147  may not surround the second electrode  146  and the first sub-layer  127   a , and thus there is a problem in that light extraction efficiency is degraded due to the light reflection. When the width ratio is greater than 1:3.5, the area of the ohmic contact may be reduced, and thus there is a problem in that electrical characteristics are degraded. 
     In addition, the minimum width W 3  of the reflective layer  147  may be different from a minimum width of the first sub-layer  127   a . As an embodiment, the minimum width W 3  of the reflective layer  147  may be greater than the minimum width of the first sub-layer  127   a . In addition, the minimum width of the first sub-layer  127   a  may be greater than or equal to the minimum width of the second electrode  146 . 
     Further, a ratio of the minimum width W 1  of the second electrode  146  and a distance W 2  between the adjacent recesses may be in a range of 1:3 to 1:10. When the length ratio is less than 1:3, the area of the active layer is reduced compared to the increased area of the recess  128 , and thus there is a limit in that light extraction efficiency is degraded. When the length ratio is greater than 1:10, current spreading through the first electrode  142  of the recess may be reduced, and thus optical characteristics may be deteriorated. 
       FIG.  7    is a plan view of a semiconductor device according to another embodiment, and  FIG.  8    is a cross-sectional view taken along line AA′ in  FIG.  7   . 
     Referring to  FIGS.  7  and  8   , a semiconductor device  10 ′ according to another embodiment may include a semiconductor structure  120  including a first conductive type semiconductor layer  124 , an active layer  126 , and a second conductive type semiconductor layer  127 , a first electrode  142  electrically connected to the first conductive type semiconductor layer  124 , and a second electrode  146  electrically connected to the second conductive type semiconductor layer  127 . 
     As described above, the semiconductor structure  120  may include the first conductive type semiconductor layer  124 , the active layer  126 , and the second conductive type semiconductor layer  127  and may include a recess  128  that passes through the second conductive type semiconductor layer  127  and the active layer  126  and exposes a partial region of the first conductive type semiconductor layer  124 . In addition, the contents of the first electrode  142 , the second electrode  146 , and the passivation layer  180  may also be equally applied. 
     Further, as described above, the second conductive type semiconductor layer  127  may include a first sub-layer  127   a  and a second sub-layer  127   b , and the second sub-layer  127   b  may be disposed between the first sub-layer  127   a  and the active layer  126 . 
     In addition, the second electrode  146  may be disposed on the first sub-layer  127   a , and a reflective layer  147  may be disposed to surround a side surface of the first sub-layer  127   a  so that light extracted through the second sub-layer  127   b  may be reflected toward the side surface of the first sub-layer  127   a  or a lower portion of the semiconductor device. 
     As in the aforementioned description, an Al composition of the first sub-layer  127   a  may be less than an Al composition of the second sub-layer  127   b . In addition, the Al composition of the second sub-layer  127   b  may be in a range of 50% to 80%. In addition, when the Al composition of the second sub-layer  127   b  is greater than or equal to 50%, the problem of absorbing light may be reduced, and when the Al composition of the second sub-layer  127   b  is less than or equal to 80%, the problem of degrading current injection efficiency may be reduced. As an example, when an Al composition of a well layer is 40%, the Al composition of the second sub-layer  127   b  may be 50%. 
     The Al composition of the first sub-layer  127   a  may be lower than the Al composition of the well layer. When the Al composition of the first sub-layer  127   a  is higher than the Al composition of the well layer, the first sub-layer  127   a  may not be sufficiently ohmic with the second electrode  146  due to an increase in resistance therebetween, and current injection efficiency may be reduced. 
     In addition, each of the first sub-layer  127   a  and the second sub-layer  127   b  may be composed of a system containing Al and Ga. For example, the first sub-layer  127   a  and the second sub-layer  127   b  may each include AlGaN and InAlGaN, but the present invention is not limited thereto. The Al composition of the first sub-layer  127   a  may be greater than or equal to 30% and less than or equal to 50%. When the Al composition is less than or equal to 50%, it is possible to lower the resistance with the second electrode. When the Al composition is greater than or equal to 30%, the problem of absorbing light in the first sub-layer  127   a  may be reduced. 
     In addition, a thickness of the first sub-layer  127   a  may be less than a thickness of the second sub-layer  127   b . A ratio of the thickness of the first sub-layer  127   a  and the thickness of the second sub-layer  127   b  may be in a range of 1:1.5 to 1:20. When the thickness ratio is greater than 1:1.5, the thickness of the second sub-layer  127   b  increases, and thus it is possible to improve current injection efficiency. Also, when the thickness ratio is less than 1:20, the thickness of the first sub-layer  127   a  increases, and thus the problem of degrading crystallinity may be reduced. When the first sub-layer  127   a  is too thin, it is necessary to rapidly change the Al composition in the range of the thickness, and thus the crystallinity may be degraded. 
       FIG.  9    is a conceptual diagram of a package of the semiconductor device according to one embodiment of the present invention, and  FIG.  10    is a plan view of the package of the semiconductor device according to one embodiment of the present invention. 
     Referring to  FIG.  9   , a package of the semiconductor device  10  may include a body  2  including a groove  3  (opening), the semiconductor device  10  disposed in the body  2 , and a pair of lead frames  5   a  and  5   b  disposed in the body  2  and electrically connected to the semiconductor device  10 . The semiconductor device  10  may include all of the above-described components. 
     The body  2  may include a material or a coating layer that reflects ultraviolet light. The body  2  may be formed by stacking a plurality of layers  2   a ,  2   b ,  2   c ,  2   d , and  2   e . The plurality of layers  2   a ,  2   b ,  2   c ,  2   d , and  2   e  may include the same material or different materials. As an example, the plurality of layers  2   a ,  2   b ,  2   c ,  2   d , and  2   e  may include an aluminum material. 
     The groove  3  may be formed to be wider as a distance from the semiconductor device  10  is increased, and a step portion  3   a  may be present on an inclined surface thereof. 
     A light-transmitting layer  4  may cover the groove  3 . The light-transmitting layer  4  may be made of a glass material, but the present invention is not necessarily limited thereto. A material for the light-transmitting layer  4  is not specifically limited as long as the material is capable of effectively transmitting ultraviolet light. The inside of the groove  3  may be an empty space. 
     Referring to  FIG.  10   , the semiconductor device  10  may be disposed on a first lead frame  5   a  and may be connected to a second lead frame  5   b  using a wire  20 . In this case, the second lead frame  5   b  may be disposed to surround a side surface of the first lead frame. 
       FIGS.  11 A to  11 E  are sequence diagrams for describing a method of manufacturing a semiconductor device according to one embodiment. 
     The method of manufacturing a semiconductor device according to the embodiment may include growing a semiconductor structure  120 , forming a recess  128 , disposing a first electrode  142  and a second electrode  146 , disposing a first insulating layer  131 , a second reflective layer  145 , and a second conductive layer  150 , disposing a second insulating layer  132 , disposing a second conductive layer  150 , disposing a bonding layer  160 , disposing a first conductive layer  165 , and disposing passivation and an electrode pad  166 . 
     First, referring to  FIG.  11 A , the semiconductor structure  120  may be grown. The semiconductor structure  120  may be grown on a first temporary substrate T. For example, a first conductive type semiconductor layer  121 , an active layer  122 , and a second conductive type semiconductor layer  123  may be grown on the first temporary substrate T. 
     The first temporary substrate T may be a growth substrate  170 . For example, the first temporary substrate T may be made of at least one selected from among sapphire (Al2O3), SiC, GaAs, GaN, ZnO, Si, GaP, InP, and Ge, but the present invention is not limited to such a material. 
     Further, the semiconductor structure  120  may be formed using, for example, a metal-organic chemical vapor deposition (MOCVD) method, a chemical vapor deposition (CVD) method, a plasma-enhanced chemical vapor deposition (PECVD) method, a molecular beam epitaxy (MBE) method, a hydride vapor phase epitaxy (HVPE) method, or the like, but the present invention is not limited thereto. 
     Descriptions of the first conductive type semiconductor layer  121 , the active layer  122 , and the second conductive type semiconductor layer  123  may be the same as described above. That is, the second conductive type semiconductor layer  127  may include a first sub-layer  127   a  and a second sub-layer  127   b.    
     Referring to  FIG.  11 B , the semiconductor device may include the recess  128 . The recess  128  may be positioned to pass through the second conductive type semiconductor layer  123  and the active layer  122  such that a partial region of the first conductive type semiconductor layer  121  is exposed. For example, the recess  128  may include an outer side surface of the second conductive type semiconductor layer  123 , an outer side surface of the active layer  122 , and an exposed bottom surface of the first conductive type semiconductor layer  121 . 
     Specifically, when a process margin for removing only the second conductive type semiconductor layer  123  and the active layer  122  is possible, the recess  128  may be composed of the outer side surface of the second conductive type semiconductor layer  123 , the outer side surface of the active layer  122 , and the bottom surface of the first conductive type semiconductor layer  121 . That is, the bottom surface of the first conductive type semiconductor layer  121  may be a surface that is in contact with a top surface of the active layer  122 . 
     However, when a process margin for disposing the recess  128  is taken into account, the recess  128  may further include not only the exposed bottom surface of the first conductive type semiconductor layer  121  but also an inclined surface of the first conductive type semiconductor layer  121 . 
     Referring to  FIG.  11 C , the first electrode  142  and the second electrode  146  may be disposed on the semiconductor structure  120 . 
     The first electrode  142  may be disposed in the recess  128  to be in contact with the exposed first conductive type semiconductor layer  124 . In addition, the second electrode  146  may be disposed on the first sub-layer  127   a  of the second conductive type semiconductor layer  127 . Here, the first electrode  142  and the second electrode  146  may be disposed regardless of the order. 
     Referring to  FIG.  11 D , partial regions of the second electrode  146  and the first sub-layer  127   a  may be etched. Accordingly, a structure in which the first sub-layer  127   a  and the second electrode  146  are stacked on the second sub-layer  127   b  may be formed. In addition, a reflective layer  147  may be disposed on the second electrode  146  and the second sub-layer  127   b . That is, the reflective layer  147  may be disposed on a top surface of the second sub-layer  147   b , a side surface of the first sub-layer  147   a , and on a top surface of the second electrode  146  so as to surround the first sub-layer  147   a  and the second electrode  146 . As a result, the reflective layer  147  reflects light received through the second sub-layer  147   b  to improve optical characteristics and also causes the area of the first sub-layer  147   a  to be reduced to improve electrical properties due to a decrease in ohmic resistance. 
     Referring to  FIG.  11 E , a first insulating layer  131  may be disposed on the reflective layer  147  and the semiconductor structure  120 . In addition, the first insulating layer  131  may be partially removed by etching, and due to the etching, the reflective layer  147  may have a partially exposed surface. 
     Referring to  FIG.  11 F , the second conductive layer  150  may be disposed on the exposed surface of the reflective layer  147  such that the reflective layer  147  may be electrically connected to the second conductive layer  150 . In addition, since the second conductive layer  150  is disposed on the first insulating layer  131 , the second conductive layer  150  may be electrically insulated from the first conductive type semiconductor layer  121  by the first insulating layer  131 . In addition, the second conductive layer  150  may be electrically connected to the second electrode  146  to form an electrical channel therebetween and may be etched so as not to be exposed to an outer side surface of the semiconductor device. 
     Referring to  FIG.  11 G , the second insulating layer  132  may be disposed on the semiconductor structure  120 . The second insulating layer  132  may be positioned on the second conductive layer  150 , the first insulating layer  131 , the second electrode  146 , and the first electrode  142  and may be disposed to surround the second conductive layer  150 , the first insulating layer  131 , the second electrode  146 , and the first electrode  142 . In addition, the second insulating layer  132  may be disposed on the first insulating layer  131 . Thus, even when cracks are generated in the first insulating layer  131 , the second insulating layer  132  may secondarily protect the semiconductor structure  120 . The second insulating layer  132  may be disposed to expose a portion of a top surface of the first electrode  142 . For example, the second insulating layer  132  may pass through a portion of the top surface of the first electrode  142 . The second insulating layer  132  may electrically insulate the second electrode  146  from the first conductive layer  165 . 
     Referring to  FIG.  11 H , the first conductive layer  165  may be disposed on the exposed top surface of the first electrode  142 . As a result, the first conductive layer  165  may be electrically connected to the first reflective layer  147  so that the first conductive layer  165 , the first electrode  142 , and the first reflective layer  147  may have an electrical channel. In addition, a first bonding layer  160   a  may be disposed on the first conductive layer  165 . 
     Referring to  FIGS.  11 I and  11 J , the first bonding layer (not shown) may be disposed on the first conductive layer  165 , and a second bonding layer (not shown) may be disposed below the substrate  170 . In addition, the first bonding layer (not shown) and the second bonding layer (not shown) may be combined with each other to provide the bonding layer described above. Here, the first bonding layer and the second bonding layer may be combined under a predetermined temperature and pressure. 
     Further, the bonding layer  160  may include a conductive material. As an example, the bonding layer  160  may include a material selected from the group consisting of gold, tin, indium, aluminum, silicon, silver, nickel, and copper, or an alloy thereof. 
     Further, the substrate  170  may be disposed on the second bonding layer (not shown). The bonding layer  160  may be formed by combining the first bonding layer and the second bonding layer in the state in which the substrate  170  is disposed on the second bonding layer. However, the present invention is not limited thereto. 
     In addition, as described with reference to  FIG.  1   , the substrate  170  may be made of a conductive material. As an example, the substrate  170  may include a metal or a semiconductor material. The substrate  170  may include a metal having high electrical conductivity and/or thermal conductivity. In this case, heat generated when the semiconductor device  10  operates may be rapidly discharged to the outside. In addition, when the substrate  170  is made of a conductive material, the first electrode  142  may be supplied with a current from the outside through the substrate  170 . 
     The substrate  170  may include a material selected from the group consisting of silicon, molybdenum, tungsten, copper, and aluminum or an alloy thereof. 
     In addition, referring to  FIG.  11 K , the first temporary substrate T may be separated from the semiconductor structure  120 . For example, the first temporary substrate T may be separated from the semiconductor structure  120  by emitting laser light onto the first temporary substrate T. However, the present invention is not limited to such a manner. 
     Referring to  FIG.  11 L , patterns may be present by etching the first conductive type semiconductor layer  121  in some regions of the semiconductor structure  120 . In addition, the first insulating layer  131  may be etched such that the second conductive layer  150  is exposed in the etched region. In addition, the electrode pad  166  may be disposed in a hole. 
     Further, the passivation layer  180  may be disposed on top and side surfaces of the semiconductor structure  120 . As described above, the passivation layer  180  may have a thickness of 200 nm to 500 nm. When the thickness is greater than or equal to 200 nm, a device may be protected from external moisture or foreign substances, thereby improving electrical and optical reliability of the device. When the thickness is less than or equal to 500 nm, it is possible to reduce stress applied to the semiconductor device  10 , to prevent a decrease in optical and electrical reliability of the semiconductor device  10 , and to reduce costs of the semiconductor device  10 , which are increased by an increase in a processing time of the semiconductor device  10 . However, the present invention is not limited to such a configuration. 
     Further, before the passivation layer  180  is disposed, uneven portions may be formed on the top surface of the semiconductor structure  120 . The uneven portions enable extraction efficiency of light emitted from the semiconductor structure  120  to be improved. Heights of the uneven portions may be differently adjusted according to a wavelength of light generated in the semiconductor structure  120 . 
     In addition, as described above with reference to  FIG.  9   , the semiconductor structure may be disposed on the lead frame of the package of the semiconductor device, or a circuit pattern of a circuit board. The semiconductor device may be applied to various types of light source devices. As an example, the light source devices may be concepts including a sterilizing device, a curing device, a lighting device, a display device, a vehicle lamp, and the like. That is, the semiconductor device may be disposed in a case and applied to various electronic devices configured to provide light. 
     The sterilizing device may include the semiconductor device according to the embodiment to sterilize a desired region. The sterilizing device may be applied to household appliances such as a water purifier, an air conditioner, and a refrigerator, but the present invention is not necessarily limited thereto. That is, the sterilizing device may be applied to all of various products (e.g., medical instruments) that need to be sterilized. 
     As an example, the water purifier may include a sterilizing device according to the embodiment to sterilize circulating water. The sterilizing device may be disposed at a nozzle or a discharge port through which water circulates so as to irradiate water with ultraviolet light. Here, the sterilizing device may include a waterproof structure. 
     The curing device may include the semiconductor device according to the embodiment to cure various types of liquid. A liquid may be the broadest concept including various materials which are cured when irradiated with ultraviolet light. As an example, the curing device may cure various types of resins. Alternatively, the curing device may be applied to cure a cosmetic product such as a manicure. 
     The lighting device may include a light source module including the substrate and the semiconductor device according to the embodiment, a heat dissipation part configured to radiate heat of the light source module, and a power supply configured to process or convert an electrical signal received from the outside and supply the signal to the light source module. In addition, the lighting device may include a lamp, a head lamp, a street light, or the like. 
     The display device may include a bottom cover, a reflective plate, a light-emitting module, a light guide plate, an optical sheet, a display panel, an image signal output circuit, and a color filter. The bottom cover, the reflective plate, the light-emitting module, the light guide plate, and the optical sheet may constitute a backlight unit. 
     The reflective plate may be placed on the bottom cover, and the light-emitting module may emit light. The light guide plate may be placed in front of the reflective plate to guide light emitted by the light-emitting module forward, and the optical sheet may include a prism sheet or the like and may be placed in front of the light guide plate. The display panel may be placed in front of the optical sheet, the image signal output circuit may supply an image signal to the display panel, and the color filter may be placed in front of the display panel. 
     When the semiconductor device is used as a backlight unit of a display device, the semiconductor device may be used as an edge-type backlight unit or a direct-type backlight unit. 
     The semiconductor device may be a laser diode in addition to the above-described light-emitting diode. 
     Like the light-emitting device, the laser diode may include a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer that have the above-described structures. In addition, the laser diode may utilize an electroluminescence phenomenon in which light is emitted when current flows after bonding a p-type first conductive type semiconductor and an n-type second conductive type semiconductor but has a difference in the directionality and phase of the emitted light. That is, the laser diode uses stimulated emission and constructive interference phenomena so that light having a specific single wavelength (monochromatic beam) may be emitted at the same phase and in the same direction. Due to these characteristics, the laser diode may be used for optical communication or medical equipment, semiconductor processing equipment, or the like. 
     A light-receiving device may include, for example, a photodetector, which is a kind of transducer configured to detect light and convert the intensity of the light into an electric signal. Such a photodetector includes a photocell (silicon or selenium), a photoconductor element (cadmium sulfide or cadmium selenide), a photodiode (PD) (for example, a PD having a peak wavelength in a visible blind spectral region or a true blind spectral region), a phototransistor, a photomultiplier tube, a phototube (vacuum or gas-filled), an infra-red (IR) detector, and the like, but the embodiment is not limited thereto. 
     In addition, the semiconductor device such as the photodetector may generally be manufactured using a direct bandgap semiconductor having a high photoconversion efficiency. Alternatively, the photodetector has various structures and the most common structure may include a pin-type photodetector using a p-n junction, a Schottky-type photodetector using a Schottky junction, a metal-semiconductor-metal (MSM)-type photodetector, or the like. 
     Like the light-emitting device, the photodiode may include a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer that have the above-described structures and may be formed as a p-n junction or a pin structure. The photodiode operates when a reverse bias or a zero bias is applied, and when light is incident on the photodiode, electrons and holes are generated such that current flows. In this case, the magnitude of current may be approximately proportional to the intensity of light incident on the photodiode. 
     A photocell or solar cell, which is a kind of photodiode, may convert light into current. Like the light-emitting device, the solar cell may include a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer that have the above-described structures. 
     Further, the solar cell may be used as a rectifier of an electronic circuit through the rectification characteristics of a general diode using a p-n junction and may be applied to an ultra-high frequency circuit and then may be applied to an oscillation circuit or the like. 
     Further, the above-described semiconductor device is not necessarily implemented only with semiconductors, and may further include a metal material in some cases. For example, the semiconductor device such as a light-receiving device may be implemented using at least one of Ag, Al, Au, In, Ga, N, Zn, Se, P, and As and may be implemented using an intrinsic semiconductor material or a semiconductor material doped with a p-type dopant or an n-type dopant. 
     While the embodiments have been mainly described, they are only examples and do not limit the present invention, and it may be known to those skilled in the art that various modifications and applications, which have not been described above, may be made without departing from the essential properties of the embodiments. For example, the specific components described in the embodiments may be implemented while being modified. In addition, it will be interpreted that differences related to the modifications and applications fall within the scope of the present invention defined by the appended claims.