TWI513030B - Light-emitting diode and method for manufacturing the same - Google Patents

Description

Light-emitting diode and manufacturing method thereof

The present invention relates to a light emitting diode, and more particularly to a method of manufacturing a light emitting diode.

In recent years, with the deepening of research on semiconductor luminescent materials and the continuous improvement of the manufacturing process of light-emitting diodes (LEDs), the luminous efficiency and color of light-emitting diodes have made considerable breakthroughs, making the light-emitting diodes It is possible to cross the field of high-efficiency lighting sources in the field of application. However, the light generated by the light-emitting diode can be emitted to the outside only when it is less than the critical angle. Otherwise, due to internal reflection and the like, a large amount of light will be lost inside the light-emitting diode and cannot be emitted to the outside world, resulting in the light-emitting two. The polar body has a low light extraction rate and low brightness. Therefore, it is necessary to find a manufacturing method capable of effectively improving the light-emitting rate of the light-emitting diode and the high-brightness light-emitting diode obtained thereby.

In view of the above, it is necessary to provide a high-intensity light-emitting diode and a method of manufacturing the same.

A light-emitting diode includes a substrate, a light-emitting structure on the substrate, and an electrode disposed on the light-emitting structure, wherein an outer surface of the light-emitting structure is a light-emitting surface of the light-emitting diode, and the light-emitting surface is opposite to the electrode The connected portion is a smooth surface, and at least a portion of the portion of the light-emitting surface located at the periphery of the electrode is a rough surface.

A method for manufacturing a light-emitting diode, comprising the steps of: providing a wafer comprising a substrate and a light-emitting structure formed on the substrate; forming an electrode on the light-emitting structure; coating a photoresist on an outer surface of the light-emitting structure and the electrode Etching to remove the photoresist to roughen the outer surface of the light emitting structure and the outer surface of the electrode.

Compared with the prior art, the present invention improves the brightness of the light-emitting diode by roughening the light-emitting surface of the light-emitting diode, changing the geometry of the interface with the external environment, and improving the light-emitting diode.

10, 710‧‧‧ substrate

100‧‧‧ wafer

20‧‧‧N type semiconductor layer

200‧‧‧Light resistance

22, 52, 62, 72‧ ‧ upper surface

24‧‧‧Diffuse surface

30‧‧‧Lighting layer

40‧‧‧P type semiconductor layer

400, 500, 600, 700‧‧‧Lighting diodes

422, 452, 462, 472, 590‧‧‧ rough surface

50‧‧‧current diffusion layer

60, 70‧‧‧ electrodes

90‧‧‧Lighting structure

1 is a flow chart of a method of manufacturing a light-emitting diode according to a preferred embodiment of the present invention.

2 is a schematic view showing the structure of a wafer for fabricating the light-emitting diode of the present invention.

FIG. 3 is a schematic view of the wafer shown in FIG. 2 after photoresist is applied.

4 is a schematic structural view of a light-emitting diode formed after etching of the wafer shown in FIG. 3.

Fig. 5 is a schematic view showing the structure of another light-emitting diode formed by the manufacturing method of the present invention.

Fig. 6 is a schematic view showing the structure of still another light-emitting diode formed by the manufacturing method of the present invention.

Fig. 7 is a schematic view showing the structure of still another light-emitting diode formed by the manufacturing method of the present invention.

The present invention will be further described below in conjunction with the embodiments with reference to the accompanying drawings.

1 is a flow chart of a method for fabricating a light-emitting diode according to the present invention. The manufacturing method mainly includes the steps of first providing a wafer including a substrate and forming a base. a light-emitting structure on the board; then forming an electrode on the light-emitting structure; then applying a photoresist on the outer surface of the light-emitting structure and the electrode; and etching to remove the photoresist to roughen the outer surface of the light-emitting structure and the outer surface of the electrode The light energy generated by the wafer is emitted through the roughened light-emitting surface after multiple reflections, thereby increasing the light-emitting rate of the wafer, thereby obtaining a high-brightness light-emitting diode. Hereinafter, a method for producing a light-emitting diode of the present invention and an excellent light-emitting diode obtained by the method for producing a light-emitting diode of the present invention will be described with reference to specific embodiments.

As shown in FIG. 2, the wafer 100 for fabricating the light-emitting diode of the present invention may be a conventional semiconductor wafer including a substrate 10 and a light-emitting structure 90 formed on the substrate 10. In this embodiment, the substrate 10 is sapphire, and the light emitting structure 90 sequentially includes an N-type semiconductor layer 20, a light-emitting layer 30, a P-type semiconductor layer 40, and a current diffusion layer 50, wherein the N-type semiconductor layer 20 and the light-emitting layer 30. The material of the P-type semiconductor layer 40 is aluminum indium gallium nitride (Al _x In _y Ga _1-xy N, where 0≦x≦1; 0≦y≦1; and x+y≦1). In the present embodiment, a P-type electrode 60 is formed on the current diffusion layer 50, and an N-type electrode 70 is formed on the N-type semiconductor layer 20. In other embodiments, the wafer may also be of a vertical structure, that is, its P-type electrode and N-type electrode are respectively disposed on opposite sides of the wafer.

The N-type semiconductor layer 20 is formed by Chemical Vapor Deposition (CVD), such as Metal Organic Chemical Vapor Deposition (MOCVD), or Molecular Beam Epitaxy (MBE). Directly grown on the substrate 10, the light-emitting layer 30 is formed between the N-type semiconductor layer 20 and the P-type semiconductor layer 40, and then a portion of the N-type semiconductor layer 20 is exposed by etching, and then physical deposition methods such as evaporation and sputtering are used. The N-type electrode 70 is disposed over the exposed portion of the N-type semiconductor layer 20.

The current diffusion layer 50 is a transparent structure formed on the P-type semiconductor layer 40 to improve The distribution of current enhances the luminous efficiency of the wafer 100. The material of the current diffusion layer 50 may be Ni-Au Alloy, Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), Indium Tungsten Oxide (Indium Tungsten Oxide, IWO), Indium Gallium Oxide (IGO), and the like. Similarly, the P-type electrode 60 may be formed on the current diffusion layer 50 by a physical deposition method such as evaporation or sputtering.

Then, a photoresist 200 is coated on the outer surface of the wafer 100. The photoresist 200 may be a material such as Propylene Glycol Mono-methyl Ether Acetate (PGMEA) or Polymethylmethacrylate (PMMA). As shown in FIG. 3, in the present embodiment, the photoresist 200 is applied on the light-emitting surface of the wafer 100, that is, applied to the upper surface 52 of the current diffusion layer 50 (as shown in FIG. 2) and exposed to the N-type semiconductor layer 20. A portion of the upper surface 22 (shown in FIG. 2) and completely covers the P-type electrode 60 and the N-type electrode 70. Preferably, the thickness of the photoresist 200 is about 0.4 microns.

Then, the wafer 100 with the photoresist 200 can be placed in an Inductively Coupled Plasma Etcher (ICP Etcher) for etching. Since the main component of the photoresist 200 is an organic compound, it is placed at a high power. If carbonization and aggregation occur at 300w, an irregular pattern can be obtained, so that by the inductively coupled plasma etching, when the photoresist 200 disappears, the outer surface of the wafer 100 coated with the photoresist 200 is roughened and changed. The shape of the interface between the wafer 100 and the outside is such that the light energy generated by the wafer 100 is emitted after a plurality of reflections through a suitable position on the roughened outer surface, thereby improving the light extraction rate and obtaining a high-luminance light-emitting diode.

4 is a schematic structural view of the light-emitting diode 400 formed after the wafer 100 is etched in FIG. 3, since the photoresist 200 is applied to the upper surface 52 and the N of the current diffusion layer 50. The upper surface 22 (shown in FIG. 2) of the exposed portion of the semiconductor layer 20 is completely covered with the P-type electrode 60 and the N-type electrode 70, and after etching, the upper surface 52 of the transparent current diffusion layer 50 (as shown in FIG. 2) The rough surface 452 is formed, the upper surface 22 of the exposed portion of the N-type semiconductor layer 20 forms a rough surface 422, and the upper surface 62 of the P-type electrode 60 (shown in FIG. 2) forms a rough surface 462, the upper surface of the N-type electrode 70. 72 (shown in FIG. 2) forms a rough surface 472 having a height ranging from 0.1 to 1 micrometer and a size of 0.1 to 10 micrometers.

Since the P-type electrode 60 and the N-type electrode 70 are formed before etching, the position where the P-type semiconductor layer 40 is connected to the P-type electrode 60 and the position where the N-type semiconductor layer 20 is connected to the N-type electrode 70 after the etching is completed It is not roughened, and is still a smooth surface, and the electrical contact between the P-type electrode 60 and the N-type electrode 70 and the P-type semiconductor layer 40 and the N-type semiconductor layer 20 is maintained, thereby effectively preventing the electrode from being directly formed on the rough surface. Problems such as leakage or voltage rise. The portion of the light-emitting surface located at the periphery of the P-type electrode 60 and the N-type electrode 70, that is, the rough surface 452 on the current diffusion layer 50 and the rough surface 422 on the N-type semiconductor layer 20 change the interface shape of the light-emitting diode 400 and the outside. The incident angle of the light to the light-emitting surface is changed, so that the light generated by the light-emitting layer 30 is more easily emitted to the outside through the rough surfaces 452 and 422, thereby improving the brightness of the light-emitting diode 400.

By testing more than 1000 LEDs 400, the average voltage of the non-roughened LED is 3.92V, the average wavelength is 398.26nm, and the average brightness is 137.487mW under the condition of 350mA current. The average voltage of the light-emitting diode 400 after roughening is 3.94V, the average wavelength is 398.84nm, and the average brightness is 164.551mW. The data are shown in Table 1 and Table 2: Table 1 is not roughened. Light-emitting diode

It is thus verified that the method for manufacturing the light-emitting diode of the present invention comprises the following advantages: (1) greatly improving the luminous efficiency of the light-emitting diode (the difference in brightness before and after the light-emitting diode is about 30 mW); (2) not affecting The electrical properties of the light-emitting diode (the average voltage before and after the light-emitting diode is not significantly different); and (3) the structure of the light-emitting diode is not destroyed (the wavelength before and after the light-emitting diode is not significant) Displacement).

In fact, the position where the photoresist 200 is coated on the wafer 100 determines the position of the outer surface of the wafer 100 which is roughened after etching, as shown in FIG. 5 is the structure of another light-emitting diode 500 obtained by the manufacturing method of the present invention. Schematic, as a further improvement of the present invention, the photoresist 200 is applied to the entire outer surface of the light emitting structure 90 at the time of manufacture, The light-emitting surface and the side surface of the top of the light-emitting structure 90 are included, so that not only the rough surface 452, 422 is formed on the current diffusion layer 50 and the N-type semiconductor layer 20 after the etching, but also the side surface of the light-emitting structure 90 is roughened to form a rough surface 590. Therefore, the light generated by the light-emitting layer 30 can be emitted not only by the light-emitting surface of the top of the light-emitting diode 500, that is, the rough surfaces 452 and 422, but also by the rough surface 590 of the side surface, and the light-emitting rate of the light-emitting diode 500 can be further improved.

FIG. 6 is a schematic view showing the structure of another light-emitting diode 600 obtained by the manufacturing method of the present invention, which is different in that a coating of the P-type electrode 60 and the N-type electrode 70 is performed before the photoresist 200 is applied. The protective layer is such that the upper surfaces 62, 72 of the P-type electrode 60 and the N-type electrode 70 are not roughened due to the presence of the protective layer during etching, and are still smooth surfaces. The material of the protective layer may be Silicon Dioxide (SiO ₂ ), Silicon Nitride (Si ₃ N ₄ ) or the like. After the etching is completed, the protective layer may be immersed in the chemical solution to accelerate the chemical reaction between the protective layer and the chemical solution to remove the protective layer by ultrasonic vibration plus ultraviolet (UV) irradiation to increase the temperature of the solution. The temperature of the chemical solution is about up to about 150 ° C. For the protective layer of cerium oxide and tantalum nitride, the chemical solution may be selected from Buffer Oxide Etcher (BOE).

FIG. 7 is a schematic structural view of a further light-emitting diode 700 obtained by the manufacturing method of the present invention, wherein the surface of the substrate 710 in contact with the light-emitting structure 90 is roughened to form a diffuse reflection surface 24, thereby being effective. The light that is emitted from the light-emitting layer 30 toward the substrate 710 is reflected toward the light-emitting surface, that is, the rough surfaces 452, 422. The diffuse reflection surface 24 is formed before the growth of the light-emitting structure 90, similar to the roughening of the light-emitting surface, and the photoresist 200 may be coated on the substrate 710 and placed in an inductively coupled plasma etching machine to be etched on the substrate 710. Forming a rough diffuse reflecting surface 24, and then growing on the diffuse reflecting surface 24 The light structure 90 and the light-emitting surface of the light-emitting structure 90 are roughened to form a light-emitting diode 700. The light portion generated by the light-emitting layer 30 is directed toward the substrate 710, diffusely reflected at the diffuse reflection surface 24, and is incident on the roughened light-emitting surface of the light-emitting diode 700 at different angles to improve the inside of the light-emitting diode 700. The opportunity for light to be emitted to the outside increases the light extraction rate of the light-emitting diode 700.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims.

10‧‧‧Substrate

20‧‧‧N type semiconductor layer

30‧‧‧Lighting layer

40‧‧‧P type semiconductor layer

400‧‧‧Lighting diode

422, 452, 462, 472‧‧‧ rough surface

50‧‧‧current diffusion layer

60, 70‧‧‧ electrodes

Claims (7)

A light-emitting diode includes a substrate, a light-emitting structure on the substrate, and an electrode disposed on the light-emitting structure. The improvement is that the entire outer surface of the light-emitting structure except the substrate is a light-emitting surface of the light-emitting diode. The portion where the light-emitting surface is connected to the electrode is a smooth surface, the outer surface of the electrode is a rough surface, and at least a portion of the portion of the light-emitting surface outside the electrode is a rough surface. The light-emitting diode according to claim 1, wherein the surface of the substrate connected to the light-emitting structure is a rough surface for diffusing and reflecting light incident on the substrate toward the light-emitting surface. The light-emitting diode according to any one of claims 1 to 2, wherein the roughened surface has a height ranging from 0.1 to 1 μm and a roughening size of 0.1 to 10 μm. A method for manufacturing a light-emitting diode, comprising the steps of: providing a wafer comprising a substrate and a light-emitting structure formed on the substrate; forming an electrode on the light-emitting structure; coating a photoresist on an outer surface of the light-emitting structure and the electrode At the same time, the photoresist is coated on the side of the light-emitting structure away from the substrate to roughen the side surface; etching is performed to remove the photoresist, and the outer surface of the light-emitting structure and the outer surface of the electrode are roughened. The method for producing a light-emitting diode according to claim 4, wherein before the photoresist coating, further comprising coating a protective layer on the electrode. The method for manufacturing a light-emitting diode according to claim 4, wherein the light-emitting structure is grown on a substrate, and before the light-emitting structure is grown, further comprising etching to roughen the substrate, wherein the light-emitting structure is thickened by the substrate One side grows. The method of manufacturing a light-emitting diode according to claim 4, wherein the etching is an inductively coupled plasma etching.