TW201414004A - Manufacturing method of LED - Google Patents

Abstract

A manufacturing method of LED (light emitting diode) includes the steps of providing an epitaxial substrate, the epitaxial substrate has a first surface and a second surface, the first surface and the second surface are located at opposite sides of the epitaxial substrate respectively; forming an epitaxial structure on the first surface of the epitaxial substrate, the epitaxial structure has a first semiconductor layer and a second semiconductor layer; forming a trench on the epitaxial structure, the trench exposes the first semiconductor layer; providing a fixed substrate disposing on the epitaxial structure and the first semiconductor layer; providing a energy entering to the epitaxial substrate from the second surface of the epitaxial substrate and focusing between the first surface and the second surface; forming a reflective layer on the second surface of the epitaxial substrate; and removing the fixed substrate and processing the chip breaking, so as to form a plurality of LED chips.

Description

Light-emitting diode manufacturing method

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

A light emitting diode (LED) is a light-emitting element made of a semiconductor material, which has the advantages of low power consumption, long component life, fast reaction speed, and the like, and is small in size and easy to be made into a small or array. The characteristics of the components, so in recent years, with the continuous advancement of technology, its application range has even expanded from the indicator light, backlight to the field of lighting.

In the development of high-power light-emitting diodes, the increase in the horizontal structure area of the conventional horizontal-conducting light-emitting diode makes the heat generated by the operation of the element more easily accumulated on the light-emitting diode wafer, causing the temperature of the element. The rise affects its luminous efficiency and product reliability. Therefore, in improving the light extraction capability of the light-emitting diode, the heat dissipation capability is also a loop that cannot be ignored. In addition, there are many methods for improving the output brightness of the LED and improving its luminous efficiency. One possible method is to plate a high-reflectivity metal mirror on the back surface of the LED, which is not only Improve the output brightness of the LED, and help the LED to dissipate heat. Therefore, the arrangement of the metal mirror is the best choice for the conventional horizontal high power light-emitting diode.

Please refer to FIG. 1A to FIG. 1E respectively, which are schematic diagrams showing a manufacturing process of a conventional light-emitting diode.

First, as shown in FIG. 1A, an epitaxial structure 12 having an n-GaN layer 121, a multiple quantum well layer 122, and a p-GaN layer 123 is formed on an epitaxial substrate 11. Next, as shown in FIG. 1B, a trench T is formed on the epitaxial structure 12 to expose the n-GaN layer 121, respectively. Further, a first electrode P1 and a second electrode P2 are formed on each of the p-GaN layer 123 and each of the n-GaN layers 121, respectively. Next, as shown in FIG. 1C, the n-GaN layer 121 is cut in a laser precut manner to form a plurality of slits C. Thereafter, as shown in FIG. 1D, a reflective layer 13 is plated on the lower surface of the epitaxial substrate 11. Finally, as shown in FIG. 1E, grain splitting is performed to form a plurality of light-emitting diode crystal grains having the reflective layer 13.

In the above steps, when the laser cutting is performed in a laser pre-cut manner, black slag is left on the wafer, and the slag must be removed by using a chemical to avoid affecting the luminance of the light-emitting diode after the finished product. However, when the black slag is removed by the chemical agent, the slag cannot be removed, and the luminance of the light-emitting diode is attenuated to affect the luminous efficiency. Therefore, how to provide a method for fabricating a light-emitting diode can improve its luminous efficiency, which is a goal that the industry has been striving for.

In view of the above problems, an object of the present invention is to provide a method for fabricating a light-emitting diode. The method of the present invention does not have black slag remaining by laser cutting, and thus does not cause a decrease in luminance of the light-emitting diode. And affect its luminous efficiency.

In order to achieve the above object, the present invention provides a light emitting diode manufacturing The method includes providing an epitaxial substrate having a first surface and a second surface, wherein the first surface and the second surface are respectively located on opposite sides of the epitaxial substrate; forming an epitaxial structure on the epitaxial substrate a surface, wherein the epitaxial structure has a first semiconductor layer and a second semiconductor layer; forming a trench on the epitaxial structure, the trench exposing the first semiconductor layer; providing a fixed substrate disposed on the epitaxial structure and Providing an energy from the second surface of the epitaxial substrate into the epitaxial substrate and focusing between the first surface and the second surface; forming a reflective layer on the second surface of the epitaxial substrate; The fixed substrate is removed and grain splitting is performed to form a plurality of light emitting diode crystal grains.

In a preferred embodiment of the present invention, the epitaxial structure further has an active layer sandwiched between the first semiconductor layer and the second semiconductor layer.

In a preferred embodiment of the invention, the substrate comprises a tape, a wax, a photoresist or a rigid substrate, or a combination thereof.

In a preferred embodiment of the invention, a single luminescent diode die is defined by a trench.

In a preferred embodiment of the invention, the energy is generated by illumination of a laser.

In a preferred embodiment of the invention, the illumination position of the energy corresponds to the groove.

In a preferred embodiment of the invention, the energy destroys the internal structure of the epitaxial substrate.

In a preferred embodiment of the invention, the reflective layer is subjected to an evaporation or sputtering process to form a second surface of the epitaxial substrate.

In a preferred embodiment of the invention, the reflective layer is a single layer structure or a multilayer structure.

In a preferred embodiment of the invention, the material of the reflective layer comprises silver, aluminum, gold, titanium, chromium, nickel, indium tin oxide, or a combination thereof.

In a preferred embodiment of the present invention, the fabrication method further includes forming a current blocking layer on the second semiconductor layer of the epitaxial structure.

In a preferred embodiment of the invention, the method further includes forming a first electrode over the epitaxial structure and forming a second electrode over the first semiconductor layer.

In a preferred embodiment of the invention, the fabrication method further includes forming a protective layer on the epitaxial structure, wherein the protective layer exposes the first electrode and the second electrode.

In a preferred embodiment of the invention, the fabrication method further comprises thinning the epitaxial substrate.

As described above, the method for fabricating a light-emitting diode according to the present invention includes providing an epitaxial substrate having a first surface and a second surface, wherein the first surface and the second surface are respectively located on the epitaxial layer An opposite side of the substrate; forming an epitaxial structure on the first surface of the epitaxial substrate, wherein the epitaxial structure has a first semiconductor layer and a second semiconductor layer; forming a trench on the epitaxial structure, the trench is exposed a first semiconductor layer is disposed; a fixed substrate is disposed on the epitaxial structure and the first semiconductor layer; and an energy is supplied from the second surface of the epitaxial substrate into the epitaxial substrate, and is focused between the first surface and the second surface Forming a reflective layer on the second surface of the epitaxial substrate; and removing the fixed substrate and performing grain splitting to form a plurality of light emitting diodes Grain. Therefore, compared with the conventional one, the light-emitting diode of the present invention does not use the conventional laser pre-cutting method for grain cutting, so that there is no black slag remaining in the laser cutting, so there is no melting. The slag cannot be cleaned and the luminance of the light-emitting diode is attenuated to affect its luminous efficiency.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method of fabricating a light-emitting diode according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings, wherein the same elements will be described with the same reference numerals.

2, FIG. 3A to FIG. 3H, FIG. 2 is a flow chart of a method for fabricating a light-emitting diode according to a preferred embodiment of the present invention, and FIGS. 3A to 3H are respectively a light-emitting diode of the present invention. Schematic diagram of the production process of the polar body.

The manufacturing method of the light-emitting diode of the present invention includes steps S01 to S07.

First, in step S01, as shown in FIG. 3A, an epitaxial substrate 21 is provided. The epitaxial substrate 21 has a first surface 211 and a second surface 212, wherein the first surface 212 and the second surface 212 are respectively located. The opposite side of the epitaxial substrate 21. Here, the first surface 211 is the upper surface of the epitaxial substrate 21, and the second surface 212 is the lower surface of the epitaxial substrate 21.

In addition, in step S02, an epitaxial structure 22 is formed on the first surface 211 of the epitaxial substrate 21, wherein the epitaxial structure 22 has a first semiconductor layer 221 and a second semiconductor layer 223. The epitaxial substrate 21 of this embodiment is exemplified by a sapphire substrate (Sapphire). Of course, the epitaxial substrate 21 can also be tantalum carbide, aluminum oxide, gallium nitride, glass, quartz, gallium phosphide or gallium arsenide substrates, and the like. Among them, the main epitaxial methods for forming the epitaxial structure 22 include liquid phase epitaxy (LPE), Vapor Phase Epitaxy (VPE), and organometallic vapor phase epitaxy (Metal-organic). Chemical Vapor Deposition, MOCVD), without limitation.

In addition, the epitaxial structure 22 is in the material gap, and the commonly used group III-V elements are composed up to four types: GaP/GaAsP series, AlGaAs series, AlGaInP series, and GaN series. Here, the epitaxial structure 22 has a first semiconductor layer 221, an active layer 222, and a second semiconductor layer 223 as an example. The first semiconductor layer 221, the active layer 222, and the second semiconductor layer 223 are sequentially adjacent to the epitaxial substrate 21 and away from the epitaxial substrate 21. The first semiconductor layer 221 and the second semiconductor layer 223 have different electrical properties. For example, when the first semiconductor layer 221 is P-type, the second electrical semiconductor layer 223 is N-type; and when the first semiconductor 221 layer is N-type; The second semiconductor layer 223 is of a P type. Here, the first semiconductor layer 221 is N-type gallium nitride (GaN), the active layer 222 is a multiple quantum-well (MQW) structure, and the second semiconductor layer 223 is a P-type gallium nitride. For example.

In addition, in step S03, as shown in FIG. 3B, a trench T is formed on the epitaxial structure 22, wherein the trench T exposes the first semiconductor layer 221 of the epitaxial structure 22. In more detail, a yellow light lithography process can be used to form a mask layer (not shown) with a photoresist material as an etch mask, and then an etching process is used to remove a portion of the epitaxial structure covered by the mask layer. Until The first semiconductor layer 221 is exposed to be formed after the trench T of the subsequently defineable light-emitting diode die, and then the mask layer is removed. Here, the etching technique may be inductively coupled plasma ion etching. A single light-emitting diode crystal grain can be defined by the formation of the trench T. In this embodiment, two trenches T are formed as an example to define three light-emitting diode crystal grains. Wherein, in the direction of the first surface 211 of the vertical epitaxial substrate 21, the trench T removes a portion of the epitaxial structure 22 until the portion of the first semiconductor layer 221 is exposed. In other embodiments, in order to determine that the trench T may expose a portion of the first semiconductor layer 221, the etching process may also be controlled until a portion of the first semiconductor layer 221 is removed to ensure that the trench T may expose the first semiconductor layer. 221.

In addition, in other implementations, the fabrication method may further include forming a current blocking layer (not shown) on the second semiconductor layer 223 of the epitaxial structure 22. The current blocking layer can avoid a large amount of current directly flowing into the light emitting diode to cause current congestion, and can improve the luminous efficiency of the light emitting diode. Among them, the current barrier layer can be formed by a lithography, vapor deposition and floating process, and the material thereof can be an insulating transparent film of cerium oxide (SiO _x ) or tantalum nitride (SiN _x ). The fabrication method may further include forming a transparent conductive layer (not shown) on the second semiconductor layer 223 of the epitaxial structure 22 and forming a ohmic contact on the current blocking layer (not shown). The transparent conductive layer may be formed by a lithography, vapor deposition and floating or etching process, and the material thereof may be a transparent conductive film of indium tin oxide (ITO).

Furthermore, as shown in FIG. 3C, after the trench T is formed and before the next step S04 is performed, the fabrication method may further include: forming a first electrode P1 over the epitaxial structure 22 and forming a second electrode P2. Above the first semiconductor layer 221. More specifically, the first electrode P1 and the second electrode P2 are respectively disposed on the second semiconductor layer 223 and the first semiconductor layer 221 of the epitaxial structure 22 . The first electrode P1 and the second electrode P2 may be formed by a lithography, vapor deposition, and floating or etching process, and the first electrode P1 and the second electrode P2 may be a composite metal layer, and the material thereof may be titanium, for example. / Platinum / Gold or Chromium / Platinum / Gold. In addition, before the step S04 is performed, the manufacturing method may further include forming a protective layer (not shown) on the epitaxial structure 22, the protective layer not covering the first electrode P1 and the second electrode P2, so that the first electrode P1 And the second electrode P2 can be exposed, and the power source is externally connected. Wherein, the protective layer can be formed by lithography, evaporation and floating or etching processes, and the material thereof can be an insulating transparent film of cerium oxide (SiO _x ) or tantalum nitride (SiN _x ). In addition, as shown in FIG. 3D, before the step S04 is performed, the manufacturing method may further include thinning the epitaxial substrate 21. In this embodiment, the thickness of the epitaxial substrate 21 is reduced by processes such as polishing and polishing. The thickness of the original epitaxial substrate 21 is about 440 μm, and the epitaxial substrate 21 can be first polished to 50 to 100 μm, and finally the epitaxial substrate 21 is thinned to 20 to 40 μm by a polishing process. Here, the lower surface of the epitaxial substrate 21 after thinning is still referred to as the second surface of the epitaxial substrate 21, and is denoted by 212a below.

Next, in step S04, as shown in FIG. 3E, a fixed substrate F is provided on the epitaxial structure 22 and the first semiconductor layer 221. For example, the fixed substrate F may be adhered to the epitaxial structure 22 and the first semiconductor layer 221 by a flexible adhesive tape; or the epitaxial structure 22 and the first semiconductor may be coated with a wax or a photoresist. The layer 221 is used as a fixed substrate F; or a rigid substrate can be used as a fixed base with an adhesive The F, wherein the adhesive can be, for example, glue or any adhesive object that can be used to bond the rigid substrate with the epitaxial structure 22 and the first semiconductor layer 221 to bond the rigid substrate to the epitaxial structure 22 and the first semiconductor layer Above 221.

Next, step S05 is performed. As shown in FIG. 3F, an energy E is supplied from the second surface 212a of the epitaxial substrate 21 into the epitaxial substrate 21, and is focused between the first surface 211 and the second surface 212a. In the present embodiment, the inside of the epitaxial substrate 21 is irradiated with the laser beam from the second surface 212a of the epitaxial substrate 21 (from the lower surface upward) to provide a stealth laser cutting mode. The laser light is focused on the inside of the epitaxial substrate 21, and the irradiation position of the energy E corresponds to the position of the original trench T. Since the energy E of the laser light is focused on the inside of the epitaxial substrate 21, the internal structure of the partial epitaxial substrate 21 is dissociated and destroyed, but the second surface 212a or the first surface 211 of the epitaxial substrate 21 is not caused. Damage (no actual cuts). In addition, in order to prevent the energy E of the laser light from damaging the epitaxial structure 22 and affecting the process yield, the laser light enters the epitaxial substrate 21 from the second surface 212a and is focused on the inside of the epitaxial substrate 21. In addition, since the epitaxial structure 22 and the epitaxial substrate 21 have been fixed on the fixed substrate F, the epitaxial substrate 21 and the epitaxial structure 22 after the stealth laser cutting are not broken by the influence of stress, nor are they broken. There will be warping.

In addition, in step S06, as shown in FIG. 3G, a reflective layer 23 is formed on the second surface 212a of the epitaxial substrate 21. In this embodiment, a high reflectivity reflective layer 23 is disposed on the second surface 212a of the epitaxial substrate 21 via an electron gun (E-Gun) evaporation or sputtering process. Reflecting light. Here, it is an example of upward illumination. In addition, the reflective layer 23 of the embodiment may be a single layer of high reflectivity metal layer or a plurality of high reflectivity metal layers, and the material thereof may include, for example, silver, aluminum, gold, titanium, chromium, nickel, indium tin oxide. The substance, or a combination thereof, may be, for example, a single layer of silver, a double layer of nickel/silver, or a double layer of indium tin oxide/silver or the like. The use of the high reflectivity reflective layer 23 can improve the narrow reflection bandwidth of the conventional multilayer film Bragg mirror to provide a full-band reflection spectrum, which not only improves the luminous efficiency of the light-emitting diode, but also helps the light-emitting diode The pole body dissipates heat.

Finally, step S07 is performed, as shown in FIG. 3H, the fixed substrate F is removed, and grain splitting is performed to form a plurality of light-emitting diode crystal grains. Here, the light emitting diode system is a horizontal conductive light emitting diode.

In summary, the present invention includes providing an epitaxial substrate having a first surface and a second surface, wherein the first surface and the second surface are respectively located on opposite sides of the epitaxial substrate; forming an epitaxial structure on the surface a first surface of the crystal substrate, wherein the epitaxial structure has a first semiconductor layer and a second semiconductor layer; forming a trench on the epitaxial structure, the trench exposing the first semiconductor layer; providing a fixed substrate disposed on An epitaxial structure and the first semiconductor layer; providing an energy from the second surface of the epitaxial substrate into the epitaxial substrate and focusing between the first surface and the second surface; forming a reflective layer on the epitaxial substrate Surface; and removing the fixed substrate and performing grain splitting to form a plurality of light-emitting diode crystal grains. Therefore, compared with the conventional one, the light-emitting diode of the present invention does not use the conventional laser pre-cutting method for grain cutting, so that there is no black slag remaining in the laser cutting, so there is no melting. The slag cannot be cleaned, causing the luminance of the light-emitting diode to decay and affecting its development. Light efficiency.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of this creation shall be included in the scope of the appended patent application.

11, 21‧‧‧ epitaxial substrate

12, 22‧‧‧ epitaxial structure

121‧‧‧n-GaN layer

122‧‧‧Multiple Quantum Wells

123‧‧‧p-GaN layer

13, 23‧‧‧reflective layer

211‧‧‧ first surface

212, 212a‧‧‧ second surface

221‧‧‧First semiconductor layer

222‧‧‧ active layer

223‧‧‧Second semiconductor layer

C‧‧‧ cuts

E‧‧‧Energy

F‧‧‧Fixed substrate

P1‧‧‧first electrode

P2‧‧‧second electrode

S01~S07‧‧‧Steps

T‧‧‧ trench

1A to FIG. 1E are schematic diagrams showing a manufacturing process of a conventional light-emitting diode; FIG. 2 is a flow chart of a method for fabricating a light-emitting diode according to a preferred embodiment of the present invention; and FIG. 3A to FIG. Schematic diagram of the manufacturing process of the light-emitting diode.

S01~S07‧‧‧Steps

Claims (14)

A method for fabricating a light emitting diode includes: providing an epitaxial substrate having a first surface and a second surface, wherein the first surface and the second surface are respectively located opposite to the epitaxial substrate Forming an epitaxial structure on the first surface of the epitaxial substrate, wherein the epitaxial structure has a first semiconductor layer and a second semiconductor layer; forming a trench on the epitaxial structure, wherein the The trench exposes the first semiconductor layer; a fixed substrate is disposed on the epitaxial structure and the first semiconductor layer; and an energy is supplied from the second surface of the epitaxial substrate into the epitaxial substrate, and is focused on Between the first surface and the second surface; forming a reflective layer on the second surface of the epitaxial substrate; and removing the fixed substrate and performing grain splitting to form a plurality of light emitting diode crystals grain. The manufacturing method of claim 1, wherein the epitaxial structure further has an active layer sandwiched between the first semiconductor layer and the second semiconductor layer. The manufacturing method of claim 1, wherein the fixed substrate comprises a tape, a wax, a photoresist or a rigid substrate, or a combination thereof. For example, the manufacturing method described in claim 1 is made by The trench defines a single luminescent diode die. The manufacturing method of claim 1, wherein the energy is generated by irradiation of a laser light. The manufacturing method of claim 1, wherein the irradiation position of the energy corresponds to the groove. The manufacturing method of claim 1, wherein the energy destroys an internal structure of the epitaxial substrate. The manufacturing method of claim 1, wherein the reflective layer is subjected to an evaporation or sputtering process to be formed on the second surface of the epitaxial substrate. The manufacturing method of claim 1, wherein the reflective layer is a single layer structure or a multilayer structure. The manufacturing method of claim 1, wherein the material of the reflective layer comprises silver, aluminum, gold, titanium, chromium, nickel, indium tin oxide, or a combination thereof. The manufacturing method of claim 2, further comprising: forming a current blocking layer on the second semiconductor layer of the epitaxial structure. The manufacturing method of claim 1, further comprising: forming a first electrode on the epitaxial structure; and forming a second electrode on the first semiconductor layer. The manufacturing method of claim 12, further comprising: forming a protective layer on the epitaxial structure, wherein the protective layer exposes the first electrode and the second electrode. The manufacturing method of claim 1, further comprising: thinning the epitaxial substrate.