JP2009010060A - Light emitting diode and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting diode for enhancing the light emitting efficiency, and to provide a method of manufacturing the same. <P>SOLUTION: A buffer layer, a first type epitaxy layer, a light emitting layer, and a second type epitaxy layer are provided on the substrate of the light emitting diode based on the order. The surface of the second type epitaxy layer is subjected to roughening treatment to form a roughened surface. The roughening treatment covers the surface of the second type epitaxy layer with spheres having equivalent particle size and then removes the spheres by dry etching. A plurality of periodically arranged recesses are formed in that second type epitaxy layer, and the light beam which is totally reflected and can not exit it is further reflected by the recesses. The light beam is emitted outside the light emitting diode after totally reflected once or several times because of the irregularly changing light beam running direction, so that the best light beam emitting efficiency can be obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a light emitting diode and a method for manufacturing the same, and more particularly, to provide a light emitting diode that increases luminous efficiency and a method for manufacturing the same.

Compared with light-emitting diodes and traditional light bulbs, emitting diodes maintain absolute dominance, such as small volume, long life, low voltage / current drive, hard to burst, inconspicuous when emitting light, mercury It does not contain (no contamination problem), has a good luminous efficiency (electricity saving), etc., and the light emitting diodes in recent years have continued to improve their luminous efficiency, so the light emitting diode Have gradually been replaced by sunlight and incandescent bulbs in certain areas. For example, a light source for a scanner that requires a high-speed reaction, a backlight source or a front light source for a liquid crystal display, an automobile speedometer board illumination, a traffic light, and a general illumination device.

Moreover, since the III-V group compound containing nitrogen is a material having a wide band gap, it can be said that the emission wavelength includes all red light from ultraviolet light, and almost all visible light wavelengths are included. . Therefore, for example, light emitting diode components such as gallium nitride (GaN), aluminum gallium nitride (GaAlN), and indium gallium nitride (GaInN) using compound semiconductors containing gallium nitride are widely applied in various light emitting modules. ing.

The upper layer surface of the known light emitting diode is planar, and the corresponding substrate bottom surfaces are parallel to each other. Therefore, when the light emitting layer located in the center sandwiching layer emits light, some light rays are emitted to the outside of the component, but most other light rays are completely reflected, so the light emission effect is good. No results. This is because the semiconductor material is a highly refractive material with respect to the outside air, and therefore, when the light emission angle is larger than one critical angle, total reflection occurs. Since the totally reflected light is a plane where both sides of the light-emitting diode are symmetrical, the light is not emitted forever, and the light emission efficiency is not only poor, but also the total reflected light is emitted. Since heat energy is generated inside the diode, the temperature of the entire light emitting diode rises, which is disadvantageous for the reliability requirement of the product.

FIG. 1 shows a structural sketch of a known light-emitting diode 1. A buffer layer 12, a first type epitaxy layer 13, a light emitting layer 14, and a second type epitaxy layer 15 are provided on the substrate 11 based on the order, and an electrode 16 is provided on the surface of the second type epitaxy layer 15. The bottom surface of the substrate 11 hits the electrode 17, and the surfaces of the substrate 11 and the second-type epitaxy layer 15 are both planar and parallel to each other. The light emitting layer 14 emits light entirely, and the light source of such a light emitting surface is composed of an infinitely large number of point light sources P.

2 and 3 illustrate a single point light source P as an example, where the point light source P emits light rays P1 and P2 to the outside of the component, and the emitted light rays P1 such as the emitted light rays P3 and P4. , Rays other than P2 are not emitted outside the component due to the total reflection. Therefore, the effective light emission range of the point light source P on the surface of the upper part of the component is the range indicated by 141 in the figure. This light emission range 141 is only a local area on the surface of the upper layer, and the light emission of the entire product. Efficiency will not give good results.

In view of the above problems, the present invention further reflects a light beam that is totally reflected and cannot be emitted, and the light beam is emitted after being reflected once or several times depending on the light traveling direction that changes irregularly. Since it emits to the outside of the diode, it is a light emitting diode that can obtain the best light emission efficiency.

In order to achieve the above object, a buffer layer, a first type epitaxy layer, a light emitting layer, and a second type epitaxy layer are provided on the substrate of the light emitting diode according to the present invention based on the order. The surface of the type epitaxy layer is subjected to a roughening treatment to form a roughened surface. The roughening treatment is performed by laying spheres having the same particle size on the surface of the second type epitaxy layer and then performing dry etching. In the second type epitaxy layer, a concave tank having a plurality of periodic arrays is formed in the second type epitaxy layer, and the concave tank further reflects light rays that are totally reflected and cannot be emitted. , Improve luminous efficiency.

As described above, the light emitting diode of the present invention and the method for manufacturing the same further reflect the light that cannot be emitted after being totally reflected, and the light can be emitted once or several times depending on the light traveling direction that changes irregularly. Since the light is emitted from the light emitting diode after being totally reflected, the best light emission efficiency can be obtained.

The “light emitting diode and manufacturing method thereof” of the present invention are as shown in FIG. The manufacturing method of the light emitting diode 2 includes at least one substrate, a buffer layer is formed on the substrate, and a first type epitaxy layer, a light emitting layer, and a second layer are formed above the buffer layer based on the order. A type epitaxy layer is provided. A roughening process is performed on the second type epitaxy layer to form a roughened surface.

Further, the structure of the light emitting diode to be manufactured is as shown in FIG. 5, which is one substrate 21, one buffer layer 22, one first type epitaxy layer 23, one light emitting layer 24, one second layer. A type epitaxy layer 25 is included. A buffer layer 22 is provided on the base material 21, the buffer layer 22 is provided on the base material 21, a first type epitaxy layer 23 is provided above the buffer layer 22, and the light emitting layer 24 is a first type epitaxy layer 23. The second type epitaxy layer 25 is provided above the light emitting layer 24. The material of the first type epitaxy layer 23, the light emitting layer 24, and the second type epitaxy layer 25 is a group III-V compound semiconductor material such as gallium nitride (GaN), gallium phosphide (GaP), or gallium arsenide. The first-type epitaxy layer 23 and the second-type epitaxy layer 25 are in conflict with each other. For example, if the first-type epitaxy layer 23 is an n-type epitaxy layer, the second-type epitaxy The layer 25 is a p-type epitaxy layer, and when the first-type epitaxy layer 23 is a p-type epitaxy layer, the second-type epitaxy layer 25 becomes an n-type epitaxy layer. A roughened surface 26 is provided on the surface of the second type epitaxy layer 25 among them.

The two electrodes 231 and 251 are provided on the surfaces of the first type epitaxy layer 23 and the second type epitaxy layer 25, respectively.

Among them, the roughening process is as shown in FIG. 6 and includes the following steps.

The spheres having the same particle size are used, and the particle size of the spheres is adjusted depending on the material of the second type epitaxy layer.

A view in which the sphere 31 is laid on the surface of the second type epitaxy layer 25 is as shown in FIG. The spheres 31 are arranged on the surface of the second-type epitaxy layer 25 with periodicity, and the two spheres 31 have an equal interval.

  The surface of the second-type epitaxy layer 25 is dry-etched (or plasma-etched), as shown in FIG. 7B. A concave tank 252 is formed between the spheres 31 by etching. The depth of is less than 5 μm. Naturally, the depth of the concave tank is adjusted depending on the material of the second-type epitaxy layer, and as shown in the figure, each concave tank 252 is arc-shaped, and the wave interval between the two concave tanks 252 is 1 μm to 2 μm. Between.

  As shown in FIG. 7C, the sphere 31 on the surface of the second type epitaxy layer 25 is removed, and the sphere 31 on the surface of the second type epitaxy layer 25 is removed by washing.

Finally, as shown in FIG. 7C, the roughened surface 26 is completed. The roughened surface 26 is provided with a concave tank 252 having a dent in the surface of the second type epitaxy layer 25 in an array having periodicity.

Further, FIG. 10 shows a photograph in which a plurality of spheres are arranged on the surface of the second type epitaxy layer, and FIG. 11 is a partially enlarged photograph. The size of each sphere is about 1.5-2. um, arranged on the surface of the second-type epitaxy layer with periodicity, and etched within about 2 minutes to form a plurality of recessed tanks with a depth of about 1-3 um, which are shown in FIGS. It is shown.

A specific actual example is shown in FIG. This is explained by taking a single point light source P as an example, but it is that the light rays P1 and P2 of the point light source P reach the outside of the part, and in the light rays other than the light rays P1 and P2, originally, The emitted light rays P3 and P4 that have been totally reflected are directly emitted in this drawing, and as shown in the figure, the reflected light rays P5 that have undergone total reflection are subjected to four total reflections and then to the outside of the light emitting diode. Therefore, the light emission effect is clearly improved. In the light emitting diode of the present invention, the totally reflected light beam is emitted to the outside of the light emitting diode after being subjected to several total reflections. Therefore, regarding the upper layer surface of the light emitting diode, as shown in FIG. The emission range 241 in which light is effective is expanded to the entire surface of the upper layer of the light emitting diode, and as a whole, the light emission efficiency of the light emitting diode is clearly increased.

As described above, the present invention provides a light-emitting diode that can be satisfactorily implemented and a method for manufacturing the same, and an invention patent is filed based on the law. However, what has been shown in the above description of the embodiments and the drawings is a preferred embodiment of the present invention and does not limit the present invention. Accordingly, all approximate or equivalent structures, devices, features, etc. of the present invention shall be included in the patent application purpose and patent application scope of the present invention.

Side view of known light emitting diode structure Known luminescent layer and light emission effect diagram Three-dimensional view of the known light emission effect The flowchart regarding the step of the light emitting diode manufacturing method of this invention. Sectional drawing regarding the structure of the light-emitting diode of the present invention The flowchart regarding the step of the roughening process of this invention Sketch of roughening structure of the present invention Sketch of roughening structure of the present invention Sketch of roughening structure of the present invention Light emitting layer and light emission effect diagram of the present invention Three-dimensional view of the light emission effect of the present invention Photograph when the sphere of the present invention is laid on the surface of the second type epitaxy layer Photograph when the sphere of the present invention is laid on the surface of the second type epitaxy layer Photograph of concave tank formed after etching of the present invention Photograph of concave tank formed after etching of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting diode 11 Base material 12 Buffer layer 13 1st type epitaxy layer 14 Light emitting layer 141 Light emission range 15 2nd type epitaxy layer 16 Electrode 17 Electrode 2 Light emitting diode 21 Base material 22 Buffer layer 23 1st type epitaxy layer 231 Electrode 24 Light emitting layer 241 Emission range 25 Second type epitaxy layer 251 Electrode 252 Concave tank 26 Roughened surface 31 Sphere

Claims (6)

The light emitting diode includes one base material, one buffer layer provided on the base material, one first type epitaxy layer provided above the buffer layer, and one light emission provided above the first type epitaxy layer. A light emitting diode comprising at least a layer and a second type epitaxy layer provided above the light emitting layer and having a roughened surface. The roughened surface is arranged with periodicity and includes a concave tank in which the surface of the second type epitaxy layer is recessed, the depth of the concave tank is smaller than 5 μm, and the wave interval between the two concave tanks is The light emitting diode according to claim 1, wherein the light emitting diode is between 1 μm and 2 μm. The roughened surface is formed by performing a roughening treatment. For the roughening treatment, spheres having the same particle size are used, the spheres are arranged on the surface of the second type epitaxy layer, and dry etching is performed. The light emitting diode according to claim 1, further comprising the step of removing spheres on the surface of the second type epitaxy layer to complete a roughened surface. In a method for manufacturing a light emitting diode, a single substrate is used, a buffer layer is formed on the substrate, a first type epitaxy layer is formed on the buffer layer, and a light emitting layer is formed on the first type epitaxy layer. A second type epitaxy layer is formed on the light emitting layer, and a roughened surface is formed on the second type epitaxy layer by a roughening process. Is a step of using spheres of the same particle size and laying the spheres side by side on the surface of the second type epitaxy layer, performing dry etching, removing the spheres on the surface of the second type epitaxy layer, and completing the roughened surface. The manufacturing method of the light emitting diode characterized by the above-mentioned. 5. The method of manufacturing a light emitting diode according to claim 4, wherein the sphere is removed from the surface of the second type epitaxy layer by cleaning. 5. The method of manufacturing a light emitting diode according to claim 4, wherein the particle size of the sphere is adjusted according to a difference in material of the second type epitaxy layer.