KR101158572B1 - Method for forming light output improvement structure on the surface of light emitting device - Google Patents

Abstract

The present invention relates to a method of forming a structure for improving light output in a light emitting device, wherein agglomerated agglomerates are formed on a light emitting surface of a light emitting device to form a structure for improving light output on the light emitting surface of the light emitting device. Without performing the lithography process, the light extraction efficiency of the device can be increased, the manufacturing process can be simplified, and the manufacturing cost can be lowered.

Total reflection, luminescence, extrusion, efficiency, cohesion, heat

Description

Method for forming light output improvement structure on the surface of light emitting device}             

1 is a conceptual diagram illustrating Snell's law of light between two general media

2 is a conceptual diagram illustrating a phenomenon in which light emitted from a light emitting diode according to the related art is totally reflected.

3 is a schematic partial cross-sectional view of a light emitting device having a structure for improving light output according to the present invention;

4 is a schematic cross-sectional view for explaining a method of forming a structure for improving light output in a light emitting device according to a first embodiment of the present invention.

5A and 5B are schematic cross-sectional views for explaining a method of forming a structure for improving light output in a light emitting device according to a second embodiment of the present invention.

6 is a schematic cross-sectional view for explaining a method of forming a light emitting device having a structure for improving light output according to a third embodiment of the present invention;

<Description of the symbols for the main parts of the drawings>

100: substrate 110: N-type semiconductor layer

120: active layer 130: P-type semiconductor layer

130a: minute protrusion 150: emitting surface

300 light emitting element 311 aggregated mass

350: insulating film

The present invention relates to a method of forming a structure for improving light output in a light emitting device, and more particularly, a structure capable of improving light output on a light emitting surface of a light emitting device by forming an aggregated mass on the light emitting surface of the light emitting device. By forming the light emitting device, a light emitting device can be formed without increasing the photolithography process, thereby increasing the light extraction efficiency of the device, simplifying the manufacturing process, and lowering the manufacturing cost. It is about a method.

In general, light emitting diodes are single wavelength light sources that can be applied to a variety of light sources and displays.

For most light emitting diodes, light external efficiency is mostly limited by internal reflections at interfaces such as semiconductors and air.

FIG. 1 is a conceptual diagram illustrating Snell's law of light between two general media. In an environment in which two media having different refractive indices (n1, n2) exist, the light is generated in the first media (n1). When incident on two media n2, it is reflected and transmitted by the difference in refractive index between the two media, according to Snell's law.

In other words, Snell's law is n1 * sin Q1 = n2 * sin Q2, so that light incident below the critical angle at the interface between the two media passes through the second medium, and light incident above the critical angle passes to the first medium. Total reflection.

2 is a conceptual diagram illustrating a phenomenon in which light emitted from a light emitting diode according to the prior art is totally reflected, and the light emitting diode includes an N-type semiconductor layer 11, an active layer 12, and a P-type semiconductor on the sapphire substrate 10. The layers 13 are sequentially stacked, mesa-etched from the P-type semiconductor layer 13 to a portion of the N-type semiconductor layer 11, and a P electrode (on the P-type semiconductor layer 13). 14 is formed, and an N electrode 15 is formed on the mesa-etched N-type semiconductor layer 11.

In the light emitting diode, light generated in the active layer 12 passes through the P-type semiconductor layer 13 and is emitted to the outside of the device, but the interface between the P-type semiconductor layer 13 and air and the N-type semiconductor layer 11 and Light propagating at an angle greater than or equal to the critical angle at the interface between the substrates is trapped inside the device, resulting in a problem that the light extraction efficiency is lowered.

On the other hand, there are various methods for improving the light extraction efficiency of the light emitting diode.

First, there is a method of increasing the probability that light is incident on the chip surface in the vertical direction by modifying the shape of the LED chip, and the hemispherical shape is known to be the best in theory, but it is difficult and expensive to manufacture. There is this.

Second, there is a method of encapsulating a light emitting diode chip using a hemispherical epoxy dome. A third method is to use a transparent substrate to absorb an existing substrate that absorbs light in the light emitting diode structure. You can also change to a substrate.

In addition, there is a method of manufacturing a light emitting diode having a microcavity or resonant cavity structure, a very sophisticated growth control is required, and the emission wavelength of the light emitting diode is to be effectively extracted from the semiconductor to air There is a difficulty in exactly matching the above cavity mode.

This method has a problem in that the light output is drastically reduced due to the change in emission wavelength when temperature or current increases.

Recently, surface texturing techniques for forming a structural shape on the light emitting surface of the light emitting diode chip have been reported. This technique is a technique for improving the light extraction efficiency on the light emitting diode chip. Technology, epoxy encapsulation and substrate changes can improve light extraction efficiency.

Current surface texturing techniques use photolithography to pattern and shape the surface.

Since this technique uses a very sophisticated lithography technique, there is a problem that the manufacturing process is difficult, high cost, and poor mass production.

Therefore, there is a need for a surface texturing technique that is easy to process and has high mass productivity.

In order to solve the above problems, the present invention performs a photolithography process by forming a structure on the light emitting surface of the light emitting device to form a structure that can improve the light output on the light emitting surface of the light emitting device. It is an object of the present invention to provide a method for forming a structure in a light emitting device that can improve the light extraction efficiency of the device, simplify the manufacturing process, and improve the light output, which can lower the manufacturing cost.

A preferred aspect for achieving the above object of the present invention comprises the steps of forming a plurality of fine aggregated masses spaced apart from each other on the light emitting surface of the light emitting device;

Etching the light emitting surface of the light emitting device by using the plurality of fine aggregated clumps remaining on the light emitting surface of the light emitting device as a mask;

There is provided a method of forming a structure in the light emitting device to improve the light output, comprising the step of removing the plurality of fine aggregates to form a plurality of fine protrusions on the light emitting surface of the light emitting device.

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

3 is a schematic partial cross-sectional view of a light emitting device having a structure for improving light output according to the present invention. The light emitting device basically includes a light emitting structure in which an N type semiconductor layer, an active layer, and a P type semiconductor layer are sequentially stacked. It must be included.

Therefore, as shown in FIG. 4, the light emitting device includes a light emitting structure in which an N type semiconductor layer 110, an active layer 120, and a P type semiconductor layer 130 are sequentially stacked on the substrate 100.

In this case, when light is emitted from the P-type semiconductor layer 130 of the light emitting device to the outside of the device, the upper surface of the P-type semiconductor layer 130 in contact with the air may be defined as a light emitting surface.

Accordingly, the present invention is to perform a process as shown in Figure 3 on the light emitting surface to form a plurality of fine protrusions.

When the plurality of minute protrusions are formed on the light emitting surface of the light emitting device, the light emitted from the active layer of the light emitting device is emitted to the outside at an angle smaller than the critical angle by the minute protrusions.

Therefore, the fine protrusions formed on the light emitting surface can be defined as a structure that improves the light output.

4 is a schematic cross-sectional view illustrating a method of forming a light emitting device having a structure for improving light output according to a first embodiment of the present invention. After the light emitting device 300 is heated, the light emitting device 300 is formed. When the metal-type thin film is formed on the P-type semiconductor layer 130, which is a light emitting surface of the light emitting device, the metal series is spaced apart from each other on the P-type semiconductor layer 130, which is the light emitting surface of the light emitting device 300. Fine aggregated masses 311 are formed.

The micro protrusions are formed on the light emitting surface of the light emitting device 300 by masking the plurality of fine agglomerated masses 311 of the metal series thus formed.

Here, the fine protrusions have a structure for improving light output as described above.

5A and 5B are schematic cross-sectional views illustrating a method of forming a structure for improving light output in a light emitting device according to a second exemplary embodiment of the present invention. First, a P-type semiconductor which is a light emitting surface of the light emitting device 300 is illustrated. A metal thin film 310 is formed on the layer 130 (FIG. 5A).

Afterwards, the P-type semiconductor layer 130, which is a light emitting surface of the light emitting device 300, is formed by performing a heat treatment process so that the metal-based thin film 310 is aggregated so that the plurality of fine agglomerated masses 311 are spaced apart from each other. Form on the top.

Subsequently, the light emitting surface 150 of the light emitting device 300 is etched using the plurality of fine aggregated agglomerates 311 remaining on the light emitting surface 150 of the light emitting device 300 as a mask (FIG. 5C).

Finally, the plurality of micro aggregates 311 are removed to form a plurality of minute protrusions 130a on the light emitting surface 150 of the light emitting device 300 (FIG. 5D).

6 is a schematic cross-sectional view illustrating a method of forming a light emitting device having a structure for improving light output according to a third exemplary embodiment of the present invention, wherein the P-type semiconductor layer 130 is a light emitting surface of the light emitting device 300. When the insulating film 350 is formed on the upper portion, the light emitting device 300 is heated, and a metal-based thin film is formed on the insulating film 350, the insulating film 350 is spaced apart from each other on the insulating film 350. Metal-based fine aggregated clumps 311 are formed.

A portion of the P-type semiconductor layer 130 is etched from the insulating layer 350 by masking the plurality of finely aggregated agglomerates 311 of the metal series formed as described above, thereby forming fine protrusions on the light emitting surface of the light emitting device 300. do.

The particle diameter of the fine protrusions as described above is preferably 100 ~ 10000nm.

As described above, the present invention forms the aggregated mass on the light emitting surface of the light emitting device to form a structure that can improve the light output on the light emitting surface of the light emitting device, thereby performing a device without performing a photolithography process. The light extraction efficiency of the can be increased, the manufacturing process can be simplified, and the manufacturing cost can be lowered.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (6)

Forming an insulating film on the light emitting surface of the light emitting device, heating the light emitting device, and then forming a metal thin film on the insulating film, thereby forming fine agglomerated masses of the metal series spaced apart from each other on the insulating film. Forming them; Etching the insulating film and the light emitting surface of the light emitting device using a plurality of fine aggregated clumps remaining in the insulating film as a mask; And removing the insulating film and the plurality of fine aggregated masses to form a plurality of fine protrusions on the light emitting surface of the light emitting device. delete delete delete delete The method of claim 1, The particle size of the fine protrusions is 100 ~ 10000nm, the method of forming a structure for improving the light output to the light emitting device.

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