CN106449922B - Manufacturing method of light emitting diode - Google Patents

Abstract

The invention discloses a method for manufacturing a light-emitting diode, which includes the following process steps: providing a substrate, epitaxially growing a light-emitting epitaxial layer, which is formed by stacking an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer, and defining the upper surface of the light-emitting epitaxial layer Divided into P-type area and N-type area; forming a metal film layer on the light-emitting epitaxial layer; adopting rapid thermal annealing treatment to make the metal film layer gather and form metal particles; forming a mask layer on the light-emitting epitaxial layer and metal particles , and pattern the mask layer to expose the N-type region; use metal particles and the mask layer as a mask structure to perform an etching process, so that the N-type region is etched until the N-type semiconductor layer is exposed, and the N-type The upper surface of the semiconductor layer is roughened; the mask layer is removed, and the metal particles on the P-type semiconductor layer are retained for chip manufacturing.

Description

A method of manufacturing a light emitting diode

technical field

The invention relates to the technical field of semiconductors, in particular to a method for manufacturing a light emitting diode.

Background technique

After years of development of light-emitting diodes (LEDs), III-V compounds are currently the mainstream semiconductor materials for making light-emitting diodes, among which gallium nitride-based and aluminum gallium indium phosphide-based materials are the most common. Generally, the external quantum efficiency of gallium nitride-based LEDs depends on its internal quantum efficiency and light extraction efficiency. The internal quantum efficiency of most commercial LEDs is close to 100%, but its light extraction efficiency is only about 3-30%. The most important factor is the loss of photons generated inside the LED due to internal total reflection.

The roughening of the LED interface can effectively improve its light extraction efficiency. One of them is the combination of ICP dry etching and photolithography for roughening the p-GaN surface. However, since the p-GaN layer is relatively thin (80~200nm), roughening the p-GaN surface will easily lead to the loss of LED optoelectronic performance.

Contents of the invention

In order to solve the existing problems of the above-mentioned light-emitting diodes, the present invention provides a method for manufacturing a light-emitting diode, which uses metal particles as a mask for roughening the semiconductor layer, and obtains different roughening ratios through the different etching ratios of the mask and the semiconductor layer. Pattern the surface of the semiconductor layer.

The technical solution provided by the present invention includes: a method for manufacturing a light-emitting diode, including process steps:

(1) Provide a substrate, epitaxially grow a light-emitting epitaxial layer, which is formed by stacking an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer, and define a P-type region and an N-type region on the upper surface of the light-emitting epitaxial layer;

(2) Forming a metal film layer on the light-emitting epitaxial layer;

(3) Rapid thermal annealing treatment is used to cause the metal film layer to spheroidize and form metal particles;

(4) Form a mask layer on the light-emitting epitaxial layer and metal particles, and pattern the mask layer to expose the N-type region;

(5) Using metal particles and mask layer as the mask structure, the etching process is carried out, and the N-type region is etched until the N-type semiconductor layer is exposed through the different etching rate ratios of the metal particles and the semiconductor layer, and the N-type semiconductor layer is exposed. roughening of the upper surface of the layer;

(6) Remove the mask layer and retain the metal particles on the P-type semiconductor layer for chip manufacturing.

Further, the material of the metal film layer in the step (2) is selected from Ag or Pt or a combination of the foregoing.

Further, the thickness of the metal film layer in the step (2) is 2-500Å.

Further, the rapid thermal annealing treatment conditions in the step (3) include: the temperature is 300-1000° C., the time is 10s-10 minutes, and the atmosphere includes nitrogen and argon as inert gases.

Further, the mask layer in the step (4) is made of photoresist or oxide or metal.

Further, the etching process in the step (5) is ICP dry etching.

Further, the different etching rate ratios of the metal particles and the semiconductor layer in the step (5) are realized by adjusting the gas ratio of the ICP dry etching.

Further, the roughened pattern on the upper surface of the N-type semiconductor layer obtained in the step (5) is conical or columnar.

Further, the chip manufacturing process in the step (6) includes manufacturing a current spreading layer on the P-type semiconductor layer.

Further, the current spreading layer is indium tin oxide (ITO) or zinc oxide (ZnO) or cadmium tin oxide (CTO) or indium oxide (InO) or indium (In) doped zinc oxide (ZnO) or aluminum (Al ) doped zinc oxide (ZnO) or gallium (Ga) doped zinc oxide (ZnO) or any combination of the foregoing.

Further, the chip manufacturing process in the step (6) includes making P electrodes and N electrodes.

Compared with the prior art, the present invention at least includes the following technical effects:

(1) On the premise of not damaging the P-type semiconductor layer, at the same time, roughen the pattern on the P and N light-emitting surfaces of the light-emitting diodes to ensure the voltage and breakdown resistance of the light-emitting diodes;

(2) The formation of a current spreading layer (TCL) on the metal particles is conducive to the diffusion of the current, and the current spreading layer will also form a rough pattern due to the introduction of the metal particles, which is conducive to improving the light extraction efficiency of the LED;

(3) P and N electrodes are made on the roughened P and N light-emitting surfaces of the light-emitting diode, and the surfaces of the P and N electrodes are also patterned to enhance the firmness of the bonding wire when the light-emitting diode is packaged, thereby reducing the failure of the LED chip probability.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In addition, the drawing data are descriptive summaries and are not drawn to scale.

FIG. 1 is a schematic flow diagram of a light emitting diode chip implemented according to the present invention.

2-8 are cross-sectional schematic diagrams of the manufacturing process flow of gallium nitride-based light-emitting diodes implemented according to the present invention.

The symbols in the figure indicate: 100: substrate; 200: light-emitting epitaxial layer; 201: N-type semiconductor layer; 202: light-emitting layer; 203: P-type semiconductor layer; 204: roughened pattern; 300: metal film layer; 301: Metal particle; 400: mask layer; 500: current spreading layer; 600: N electrode; 700: P electrode.

Detailed ways

The present invention will be described in more detail below with reference to schematic diagrams, wherein preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as the broad knowledge of those skilled in the art, but not as a limitation of the present invention.

The following lists the embodiments of the LED structure and its manufacturing method to clearly illustrate the content of the present invention. It should be clear that the content of the present invention is not limited to the following examples, other conventional technical means by those of ordinary skill in the art Improvements are also within the scope of the present invention.

Example

This embodiment provides a method for manufacturing a gallium nitride-based light-emitting diode. Please refer to FIG. 1 for the specific process, including the following process steps:

Step S11, providing a substrate, and epitaxially growing a light-emitting epitaxial layer.

Step S12, forming a metal film layer on the light-emitting epitaxial layer.

In step S13 , a rapid thermal annealing treatment is adopted to cause the metal film layer to spheroidize to form metal particles.

Step S14 , forming a mask layer on the light-emitting epitaxial layer and the metal particles, and patterning the mask layer.

In step S15 , using the metal particles and the mask layer as a mask structure, an etching process is performed to expose the N-type semiconductor layer and roughen the upper surface of the N-type semiconductor layer.

In step S16, the mask layer is removed, and the metal particles on the P-type semiconductor layer are retained, and the chip manufacturing process is performed.

It should be noted that the selection of materials for each layer in the light emitting diode structure is known to those skilled in the art, and can be flexibly selected according to needs. Those skilled in the art may also add the following optional steps to further improve the luminous effect of the LED structure as required: forming a buffer layer (Buffer), forming an electron blocking layer (EBL), and so on. This is also a known technology for those skilled in the art, and will not be described in detail herein.

In order to enable those skilled in the art to better understand the manufacturing method of the light emitting diode of the present invention, a specific embodiment is introduced with reference to FIGS. 2 to 7 .

Please refer to FIG. 2, the substrate 100 can be selected from the following group of materials, the group of materials includes: sapphire substrate, silicon carbide substrate, silicon substrate, gallium nitride substrate and zinc oxide substrate, in In this embodiment, the substrate 100 is a patterned sapphire substrate (PSS). The light-emitting epitaxial layer 200 is deposited on the substrate 100 by MOCVD, and the material may include gallium nitride-based materials, gallium phosphide-based materials, gallium nitrogen phosphorus-based materials or zinc oxide-based materials. In this embodiment, the light-emitting epitaxial layer is a gallium nitride-based material, and the epitaxial layer includes an N-type semiconductor layer 201, a light-emitting layer 202, and a P-type semiconductor layer 203 that are sequentially stacked from bottom to top, wherein the N-type semiconductor layer 201 is N-type gallium nitride (GaN) layer structure, the light-emitting layer 202 is an aluminum gallium nitride (AlGaN) multi-quantum well active layer, the P-type semiconductor layer 203 is a P-type AlGaN layer, and the upper surface of the light-emitting epitaxial layer is divided into P Type region and N type region. The light-emitting epitaxial layer structure in this embodiment is not limited to the buffer layer-N-type GaN layer structure-AlGaN multi-quantum well active layer-P-type AlGaN layer, other epitaxial layer structures that can excite light, such as N-type GaN layer-( InGaN)/GaN multi-quantum well active layer-P-type GaN layer is also within the scope of the present invention.

Please refer to FIG. 3, a metal film layer 300 is formed on the light-emitting epitaxial layer 200, the material can be Ag or Pt, the thickness is between 2-500 Å, and the deposition method can be vapor deposition or sputtering or atomic layer deposition or other Coating method, sputtering method is preferred in this embodiment.

Please refer to Fig. 4, the rapid thermal annealing treatment (RTA fusion) is adopted to cause the metal film layer 300 to spheroidize to form metal particles 301. The particle size of the metal particles is 200~5000Å, which can be adjusted by the rapid thermal annealing treatment conditions. , such as the treatment temperature is 300 ~ 1000 ℃, the time is 10s ~ 10min, the atmosphere includes nitrogen, argon inert gas.

Please refer to FIG. 5, a mask layer 400 is formed on the light-emitting epitaxial layer 200 and the metal particles 301, and the mask layer 400 is patterned so that the N-type region is exposed; the mask layer can be made of photoresist or oxide or metal, this embodiment preferably uses photoresist (PR) as the mask layer.

Please refer to FIG. 6, using Ag metal particles 301 and photoresist mask layer 400 as a mask structure to perform ICP dry etching process, by adjusting the proportion of ICP gas (CF ₄ , O ₂ , Cl ₂ , BCl ₃ , etc.) Change its etch rate to the metal particles and the semiconductor layer, by the different etch rate ratios of the metal particles and the semiconductor layer, the N-type region is etched until the N-type semiconductor layer 201 is exposed, and the upper surface of the N-type semiconductor layer 201 is roughened. The roughening pattern 204 may be in the shape of a cone or a column or other shapes.

Please refer to Figure 7, remove the mask layer, and keep the metal particles 301 on the P-type semiconductor layer, and then make a current spreading layer 500 on the P-type semiconductor layer, the current spreading layer (TCL) can choose indium tin oxide (ITO ) or zinc oxide (ZnO) or cadmium tin oxide (CTO) or indium oxide (InO) or indium (In) doped zinc oxide (ZnO) or aluminum (Al) doped zinc oxide (ZnO) or gallium (Ga) doped Zinc oxide (ZnO) or any combination of the foregoing.

Referring to FIG. 8 , the metal electrode layer is fabricated, that is, the N electrode 600 and the P electrode 700 are respectively fabricated on the roughened pattern 204 and the current spreading layer 500 to complete the conventional chip manufacturing process.

The light-emitting diode can be manufactured through the above-mentioned manufacturing process, and the pattern can be roughened on the P and N light-emitting surfaces of the light-emitting diode without damaging the P-type semiconductor layer, so as to ensure the voltage and breakdown resistance of the light-emitting diode; The current spreading layer (TCL) is conducive to the diffusion of current, and the current spreading layer will also form a roughened pattern due to the introduction of metal particles, which is conducive to improving the light extraction efficiency of the LED; it is made on the roughened P and N light-emitting surfaces of the light-emitting diode The P and N electrodes, and the surfaces of the P and N electrodes are also patterned to enhance the firmness of the bonding wires during the packaging of the light-emitting diode, thereby reducing the failure probability of the LED chip.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (10)

1. a kind of production method of light emitting diode, including processing step：

（1）A substrate is provided, epitaxial growth light emitting epitaxial layer is stacked by n type semiconductor layer, luminescent layer and p type semiconductor layer It forms, defines light emitting epitaxial layer upper surface and be divided into p type island region domain and n-type region；

（2）Metallic diaphragm is formed on light emitting epitaxial layer；

（3）Using quick thermal annealing process so that metallic diaphragm occurs ball and gathers, and forms metallic particles；

（4）Mask layer is formed on light emitting epitaxial layer and metallic particles, and mask layer is patterned so that n-type region is naked Expose；

（5）Using metallic particles and mask layer as mask structure, it is etched technique, by metallic particles and semiconductor layer Different etch-rate ratios so that n-type region is etched to n type semiconductor layer and exposes, while by the upper surface of n type semiconductor layer Roughening；

（6）Mask layer is removed, and retains the metallic particles on p type semiconductor layer, carries out chip processing procedure.

2. a kind of production method of light emitting diode according to claim 1, it is characterised in that：The step（2）In The material selection Ag or Pt or aforementioned combinatorial of metallic diaphragm.

3. a kind of production method of light emitting diode according to claim 1, it is characterised in that：The step（2）In The thickness of metallic diaphragm is 2 ~ 500.

4. a kind of production method of light emitting diode according to claim 1, it is characterised in that：The step（3）In Quick thermal annealing process condition includes：Temperature is 300 ~ 1000 DEG C, and the time is 10s ~ 10min, and atmosphere includes nitrogen, argon inert Gas.

5. a kind of production method of light emitting diode according to claim 1, it is characterised in that：The step（4）In Mask layer is made of photoresist or oxide or metal.

6. a kind of production method of light emitting diode according to claim 1, it is characterised in that：The step（5）In Etch process is ICP dry etchings.

7. a kind of production method of light emitting diode according to claim 6, it is characterised in that：The step（5）In Metallic particles etch-rate different from semiconductor layer is than the gas ratio realization by adjusting ICP dry etchings.

8. a kind of production method of light emitting diode according to claim 1, it is characterised in that：The step（5）In The upper surface roughening figure of the n type semiconductor layer arrived is taper or column.

9. a kind of production method of light emitting diode according to claim 1, it is characterised in that：The step（6）In Chip processing procedure includes that current extending is made on p type semiconductor layer.

10. a kind of production method of light emitting diode according to claim 1, it is characterised in that：The step（6）In Chip processing procedure includes making P electrode and N electrode.