TWI382566B - And a light-emitting diode chip having an adhesive layer of reflectionable light - Google Patents

Description

Light-emitting diode chip with an adhesive layer capable of reflecting light

The present invention relates to a solid state light emitting wafer, and more particularly to a light emitting diode wafer.

Referring to FIG. 1, a light emitting diode chip includes a substrate 11 , an epitaxial film 12 which is epitaxially grown upward from the substrate 11 , a transparent conductive layer 13 formed on the epitaxial film 12 , and a set of The electric field is supplied to the electrode unit 14 of the n-type electrode 141 and the p-type electrode 142 of the epitaxial film 12.

The substrate 11 is easy to be epitaxially grown by a gallium nitride series semiconductor material, and sapphire and gallium nitride are currently commonly used.

The epitaxial film 12 of the layer is mainly formed by epitaxial growth of the gallium nitride semiconductor material from the substrate 11 and has a first cladding layer which is connected to the substrate 11 and is doped n-type (n-type). a layer 121, an active layer 122 formed on the first cladding layer 121, and a second cladding layer formed on the active layer 122 and doped with a p-type 123. The first and second cladding layers 121 and 123 form a carrier energy barrier with respect to the active layer 122, and can be combined by electron-holes when the epitaxial film 12 is supplied with electric energy, thereby releasing energy and converting into light energy.

The transparent conductive layer 13 is made of a material that is transparent and electrically conductive with respect to the light generated by the epitaxial film 12, such as indium tin oxide (ITO), for guiding current to spread laterally along the top surface of the epitaxial film 12. The downward diffusion through the epitaxial film 12 causes the epitaxial film 12 to generate photons, thereby increasing the internal quantum efficiency of the epitaxial film 12.

The n-type electrode 141 and the p-type electrode 142 of the electrode unit 14 are made of a metal such as gold, nickel, platinum, silver or aluminum, and/or an alloy thereof, wherein the n-type electrode 141 is provided on the epitaxial film 12 The first cladding layer 121 is formed in ohmic contact with the first cladding layer 121; the P-type electrode 142 is disposed on the top surface of the second cladding layer 123 and is in ohmic contact with the second cladding layer 123, and the epitaxial layer can be matched Membrane 12 provides electrical energy.

When electric energy is applied from the n-type electrode 141 and the p-type electrode 142, a current dispersion flow passes through the epitaxial film 12, so that the epitaxial film 12 is recombined by electron-holes, releasing energy to convert into photons, and emitting light outward. .

In such a light-emitting diode wafer, since the epitaxial film 12 is directly epitaxially grown from the substrate 11, and the epitaxial film 12 has a good crystal structure, the substrate 11 must have a considerable degree with the epitaxial film. The lattice matching degree, therefore, the choice of the substrate is limited to substrate types such as sapphire, gallium nitride, etc., and generally, the heat transfer coefficient of such materials is poor, thus affecting the heat dissipation of the epitaxial film 12 when it is activated. Thereby, the internal quantum efficiency of the epitaxial film 12 is lowered.

Referring to FIG. 2, the current LED wafer is first made of a metal or alloy to form a heat conductive substrate 15, and then the epitaxial film 12 is bonded to the heat conductive substrate 15 by the adhesive material 16, or The wafer bonding technology directly attaches the epitaxial film to the heat conductive substrate, thereby replacing the substrate 11 having poor thermal conductivity, thereby improving the heat dissipation efficiency of the epitaxial film 12 during actuation. The epitaxial film 12 is allowed to operate stably.

Thus, although the heat dissipation efficiency when the epitaxial film 12 is activated can be improved by replacing the thermally conductive substrate 15, the epitaxial film 12 is generated and directed toward the thermally conductive substrate. The photon traveling in the direction of the material 15 is absorbed by the rubber material 16, the heat conductive substrate 15 and the like, and the heat transfer capability of the rubber material 16 is still greatly improved, so the thermal conduction is separated from the epitaxial crystal. The substantial effect of the membrane 12 is limited and the goal of solving the thermal buildup problem is not achieved.

Therefore, the current LED chip still needs to be developed and improved to improve the light extraction efficiency, thereby improving the brightness of the light.

Accordingly, it is an object of the present invention to provide a light-emitting diode wafer having an adhesive layer capable of reflecting light, which can improve the resolution of light extraction and overall luminance and uniformity.

Thus, the present invention has a light-emitting diode wafer having an adhesive layer capable of reflecting light, comprising a substrate, an epitaxial film, an adhesive layer, and an electrode unit.

The epitaxial film of the layer generates light by a photoelectric effect and has an opposite bottom surface and a top surface, and the bottom surface and the top surface are roughened to have a roughness of 100 nm or more.

The adhesive layer is disposed between the substrate and the bottom surface of the epitaxial film for connecting the substrate and the epitaxial film, the adhesive layer has a plurality of particles that can reflect light generated by the epitaxial film, and a connection a substrate, an epitaxial film and a colloidal material of the particles, wherein the particles have a particle diameter in the range of 100 nm to 1000 nm, and the refractive index of the particles is greater than that of the air and the rubber, and the refractive index of the rubber is greater than air but less than the epitaxial membrane.

The electrode unit is in ohmic contact with the epitaxial film to supply electrical energy to the epitaxial film. The effect of the invention lies in: utilizing a specific refractive index, heat transfer The adhesion layer composed of the particles and the adhesive material is combined with the top surface and the bottom surface of the epitaxial film to have a roughness of 100 nm or more, and the light generated by the epitaxial film can be effectively reflected and then taken out from the top surface. The light extraction efficiency and the overall luminance of the component are effectively improved, and the problem of thermal deposition of the epitaxial film is simultaneously solved.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Before the present invention is described in detail, it is noted that in the following description, similar elements are denoted by the same reference numerals.

Referring to FIG. 3, a preferred embodiment of a light-emitting diode wafer having a light-reflecting adhesive layer comprises a substrate 21, an epitaxial film 22, a layer connecting the substrate 21 and the epitaxial layer. The adhesive layer 23 of the film 22, and a set of electrode units 24.

The layer substrate 21 includes a bottom layer 211, and a mirror layer 212 formed on the bottom layer 211 and connected to the adhesive layer 23. The bottom layer 211 is selected from materials such as germanium, high heat dissipation ceramic materials, or metals. The structure is configured to rapidly conduct heat and support the mirror layer 212 and the epitaxial film 22, the adhesive layer 23, the electrode unit 24, etc., and the mirror layer 212 may be, for example, aluminum, silver, gold, platinum, palladium, rhodium, or The combination of these metals is formed of a material to reflect light.

The epitaxial film 22 is formed by epitaxial formation of a gallium nitride semiconductor material on an epitaxial substrate (not shown), and then the adhesive layer 23 and the base. The material 21 is bonded to the body, and the epitaxial film 22 has a first cladding layer 221 connected to the adhesive layer 23 and doped with an n-type, and an active layer connected to the first cladding layer 221. 222, and a second cladding layer 223 connected to the active layer 222 and doped with a p-type, the first and second cladding layers 221, 223 form a carrier barrier with respect to the active layer 222 to be electronic/ The hole is combined to generate light, and the bottom surface 225 of the epitaxial film 22 (ie, the lower surface of the first cladding layer 221 connected to the adhesive layer 23) and the top surface 224 (ie, the upper surface of the second cladding layer 223) are respectively For example, epitaxial growth, wet etching, inductively coupled plasma etching, or a rough discontinuous surface deliberately roughened by photo-assisted electrochemical etching, and having a roughness of 100 nm or more, thereby increasing the amount of light emitted from the epitaxial film 22.

The adhesive layer 23 has a thickness of not less than 20 μm, and has a plurality of particles 231 which can reflect the light generated by the epitaxial film 22, and a glue 232 which connects the substrate 21, the epitaxial film 22 and the particles 231, and the like. The particles 231 are spherical and have a particle diameter in the range of 100 nm to 1000 nm and must be larger than the wavelength at which the epitaxial film 22 generates light, and have a refractive index greater than that of the air and the adhesive 232. Meanwhile, the heat dissipation power of the particles 231 must be 10 W. Preferably, the particles 231 may be selected from the group consisting of alumina powder, cerium oxide powder, titanium oxide powder, diamond powder, ceramic powder, or a combination of such powders; the rubber 232 is opposite to the epitaxial film 22 The generated light is transparent and has a heat dissipation power of 0.2 W/mK or more. At the same time, the refractive index is greater than that of the air and the epitaxial film 22. Preferably, the refractive index of the adhesive material 232 is between 1 and 2, which is a polymer material. Or composed of dielectric materials.

The set of electrode units 24 has, for example, gold, nickel, platinum, silver, aluminum, etc. The metal and/or its alloy is an n-type electrode 241 and a p-type electrode 242. The n-type electrode 241 is disposed on the first cladding layer 221 of the epitaxial film 22 and is ohmic with the first cladding layer 221. In contact, the p-type electrode 242 is disposed on the second cladding layer 223 of the epitaxial film 22 and is in ohmic contact with it, and cooperates to supply electric power to the epitaxial film 22 to generate light.

When electric energy is applied from the n-type electrode 241 and the p-type electrode 242 of the electrode unit, a current flows through the epitaxial film 22 to cause the epitaxial film 22 to be combined by electron/hole recombination, wherein the upward traveling light is worn. When the top surface 224 of the epitaxial film 22 (ie, the upper surface of the second cladding layer 223) has a roughness of 100 nm or more because the top surface 224 is roughened, there are various methods for traveling with respect to light. The angle of the wire can effectively improve the limit of light travel and greatly increase the amount of light entering the outside world, and the angle of travel of the light entering the outside is more diverse, and the light is more uniform.

At the same time, light traveling downward (in the direction of the substrate 21) similarly passes through the bottom surface 225 of the epitaxial film 22 (ie, the lower surface of the first cladding layer 221) because the bottom surface 225 is also roughened to have 100 Roughness above nm, so there are various normal angles with respect to the travel of light, and can effectively improve the limitation of light travel and greatly increase the probability of light passing through and continuing to travel in the adhesive layer 23; Since the adhesive layer 23 has a refractive index greater than that of the air but smaller than the epitaxial layer 22 (preferably between 1 and 2), and the rubber material 23 is uniformly spherical, reflective, and refractive index. The particles 231 are larger than the air and the rubber 232, so that the adhesion layer 23 is not only interposed between the epitaxial film 22 and the mirror layer 212 of the substrate 21, but also produces a multi-azimuth angle. Scattering, while also being particles in progress 231 is reflected so that part of the light can be directly reflected first and opposite to the direction of the substrate 21 from the top surface 224 of the epitaxial film 22 to the outside; part of the light passing through the adhesive layer 23 is again reflected by the mirror layer 212 of the substrate 21. After reflection, the adhesive layer 23 and the epitaxial film 22 are inserted into the outside, thereby effectively improving the luminance of the entire component.

In addition, the angle of travel becomes more during the process from the epitaxial film 22 entering the adhesive layer 23 being reflected and entering the adhesive layer 23 and being reflected by the mirror layer 212 of the substrate 21 through the adhesive layer 23. The element is disordered, that is to say, the light is emitted outward through the top surface 224 of the epitaxial film 22 at a different angle, so that the light output of the element is more uniform and soft.

In addition, since the glue 232 and the particles 231 themselves have high heat conduction power, the conduction path of the current is the electrode unit 24 and the epitaxial film 22 for the light-emitting diode wafer having the adhesive layer capable of reflecting light of the present invention. The internal waste heat generated by the operation of the epitaxial film 22 is guided by the adhesive 232, the fine particles 231, and the substrate 21 of the adhesive layer 23, and is separated from the epitaxial film 22, so that heat and electricity are different. The path is conducted to avoid the internal waste heat from being discharged, which causes the resistance of the material itself to increase, and affects the stability of the current supply conduction, so as to maintain the stability of the component actuation, thereby extending the working life of the component.

It should be particularly noted that the above-mentioned particles 231 are transparent or white in light generated by the epitaxial film, and when the crystal structure of the particles has a color, it can be combined with the epitaxial film. The wavelength of light produces the effect of mixing light, which in turn causes the component to emit light of a predetermined color.

Referring to FIG. 4, additionally, the mirror layer 212 of the substrate 21 is illustrated. Dielectric materials having relatively high and relatively low refractive indices, respectively, may be alternately stacked to form a plurality of dielectric films 3 to reflect light.

Referring to FIG. 5, in addition, the top surface of the epitaxial film 22 may be transparent and electrically conductive with respect to the light emitted from the epitaxial film 22, such as indium tin oxide, to form a transparent conductive layer 4 for guiding the current first. The top surface 224 is uniformly diffused laterally and then flows through the epitaxial film 22, thereby improving the internal quantum efficiency of the epitaxial film 22, thereby achieving the purpose of improving the overall luminance of the element.

Referring to FIG. 6, in addition, when the selected material of the substrate 21 further has conductive characteristics, and the adhesive 232 also has conductive characteristics, the electrode unit 24' can be changed to be only a single electrode, and the second of the epitaxial film 22 The cladding layer 223 is connected and ohmically contacted, and the substrate 21 is used as another electrode to form a vertical-conducting light-emitting diode wafer; such a vertical-conducting light-emitting diode wafer loses the thermoelectricity described in the above example. The advantages of splitting, but in the overall brightness and uniformity of the light, there is still a significant increase due to the presence of an adhesive layer.

In summary, the present invention has a light-emitting diode wafer capable of reflecting light, using an adhesive layer having a specific refractive index and an adhesive layer having a specific refractive index and reflecting light, and an epitaxial film top. The surface and the bottom surface are roughened to have a roughness of 100 nm or more, and the light generated by the epitaxial film can be effectively raised and emitted from the top surface to the outside at a wider angle and more disorderly, thereby effectively improving light extraction. The efficiency and the overall brightness of the component, while also making the component's illumination more uniform and soft; in addition, through the rubber, the particles have a predetermined heat dissipation power, and can make electricity and heat travel in different paths, not only solve the heat accumulation Problem, you can also keep the component active The stability of the device and the actual working life of the elongating member do achieve the object of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

21‧‧‧Substrate

211‧‧‧ bottom layer

212‧‧‧Mirror layer

22‧‧‧Elevation film

221‧‧‧First coating

222‧‧‧Active layer

223‧‧‧Second coating

224‧‧‧ top surface

225‧‧‧ bottom

23‧‧‧Adhesive layer

231‧‧‧ particles

232‧‧‧Stained materials

24‧‧‧Electrode unit

241‧‧‧n type electrode

242‧‧‧p-type electrode

3‧‧‧ dielectric film

4‧‧‧Transparent conductive layer

1 is a cross-sectional view showing a conventional light-emitting diode wafer; FIG. 2 is a cross-sectional view showing another conventional light-emitting diode wafer; FIG. 3 is a cross-sectional view showing the present invention having light-reflecting adhesion A preferred embodiment of a layered light-emitting diode wafer; and FIG. 4 is a cross-sectional view showing the light-emitting diode chip of the present invention having a light-reflecting adhesive layer, the mirror layers of the substrate being relatively high respectively The dielectric film 3 is formed of a dielectric material having a relatively low refractive index; FIG. 5 is a cross-sectional view showing the light-emitting diode chip of the present invention having an adhesive layer capable of reflecting light, and the top surface of the epitaxial film further has a A transparent conductive layer; and FIG. 6 is a cross-sectional view showing a vertical conductive light-emitting diode wafer in which a light-emitting diode wafer having a light-reflecting adhesive layer of the present invention is slightly changed.

21‧‧‧Substrate

211‧‧‧ bottom layer

212‧‧‧Mirror layer

22‧‧‧Elevation film

221‧‧‧First coating

222‧‧‧Active layer

223‧‧‧Second coating

224‧‧‧ top surface

225‧‧‧ bottom

23‧‧‧Adhesive layer

231‧‧‧ particles

232‧‧‧Stained materials

24‧‧‧Electrode unit

241‧‧‧n type electrode

242‧‧‧p-type electrode

Claims (7)

A light-emitting diode chip having an adhesive layer capable of reflecting light, comprising: a substrate; an epitaxial film, which generates light by photoelectric effect and has an opposite bottom surface and a top surface, and the bottom surface and the top surface are thickened And having an roughness of 100 nm or more; an adhesive layer disposed between the substrate and the bottom surface of the epitaxial film for bonding the substrate and the epitaxial film, the adhesive layer having a plurality of reflective epitaxial films generated Particles of light, and a glue material connecting the substrate, the epitaxial film and the particles, the particle diameter of the particles is in the range of 100 nm to 1000 nm, and the refractive index of the particles is greater than that of the air and the rubber, the glue The refractive index is greater than air but smaller than the epitaxial film; and an electrode unit is in ohmic contact with the epitaxial film to supply electrical energy to the epitaxial film. The light-emitting diode chip having an adhesive layer capable of reflecting light according to claim 1, wherein the thickness of the adhesive layer is not more than 20 μm, and the particles are spherical, and the particle diameter of the particles is larger than that of the beam. The wavelength of light produced by the crystal film. A light-emitting diode chip having a light-reflecting adhesive layer according to claim 2, wherein the adhesive material is selected from the group consisting of heat dissipation power of 0.2 W/mK or more and a refractive index of between 1 and 2 The polymer material or the dielectric material is composed of a material selected from the group consisting of materials having a heat dissipation power of 10 W/mK or more. Having an adhesive layer capable of reflecting light according to item 3 of the patent application scope A light-emitting diode wafer, wherein the particles are selected from the group consisting of alumina powder, cerium oxide powder, titanium oxide powder, diamond powder, ceramic powder, and combinations thereof. A light-emitting diode chip having a light-reflecting adhesive layer according to claim 1, wherein the substrate comprises a bottom layer, and a layer is formed on the bottom layer and coupled to the adhesive layer and reflects the epitaxial layer a mirror layer produced by the film, the constituent material of the bottom layer is selected from the group consisting of germanium, a heat dissipating ceramic material, a metal, or a combination thereof, and the constituent material of the mirror layer is selected from the group consisting of aluminum, silver, gold, platinum, and palladium. , 铷, or a combination of these. A light-emitting diode chip having a light-reflecting adhesive layer according to claim 1, wherein the substrate comprises a bottom layer, and a layer is formed on the bottom layer and coupled to the adhesive layer and reflects the epitaxial layer a film-generating mirror layer, the underlying constituent material being selected from the group consisting of tantalum, a heat dissipating ceramic material, a metal, or a combination thereof, the mirror layer comprising a plurality of dielectrics having relatively high and relatively low refractive indices, respectively. The dielectric films are stacked alternately. A light-emitting diode wafer having a light-reflecting adhesive layer according to claim 1, further comprising a transparent conductive layer formed on the top surface and capable of uniformly diffusing current.