CN212783491U

CN212783491U - Patterned substrate and LED chip

Info

Publication number: CN212783491U
Application number: CN202022047990.8U
Authority: CN
Inventors: 翟峰; 唐彪
Original assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Current assignee: Chongqing Kangjia Optoelectronic Technology Co ltd
Priority date: 2020-09-17
Filing date: 2020-09-17
Publication date: 2021-03-23
Anticipated expiration: 2030-09-17

Abstract

The utility model discloses a graphical substrate and LED chip, wherein, including the base plate that is used for growing the epitaxial layer, and set up microstructure on the base plate, the microstructure is located grow on the base plate one side of epitaxial layer is on the surface, the microstructure with the surface that the epitaxial layer contacted is the arc curved surface. The utility model provides a set up the micro-structure that the surface is the arc curved surface on the graphical substrate, make the chip structure when doing laser and peel off, the arc contact surface can change the energy distribution of laser at sapphire substrate base plate interface, improves whole energy utilization who is used for laser to peel off to reach the purpose that reduces laser and peel off the energy, improve whole chip and peel off the yield.

Description

Patterned substrate and LED chip

Technical Field

The utility model relates to a semiconductor substrate technical field especially relates to a graphical substrate and LED chip.

Background

At present, with the development of the process technology in the field of Light-Emitting diodes (LEDs) and the rapid growth of the whole LED industry, research on Patterned Sapphire Substrates (PSS) of GaN (gallium nitride) -based LED devices is also increasing, and manufacturers increasingly adopt the PSS technology to improve the Light extraction efficiency of the LED devices. In order to design a patterned sapphire structure for increasing the light emitting efficiency of an LED, a substrate is patterned first to prepare microstructures with orderly arranged specifications, such as a triangle structure and a pyramid structure, in the technologies of a large LED, a mini LED, a Micro LED and the like.

However, when laser lift-off is performed, laser penetrates through a sapphire substrate, light is diffracted or scattered on a triangular or pyramidal microstructure surface, so that light energy density is reduced, the purpose of separating a chip from the substrate is achieved by increasing the energy of the laser, the effect of corresponding generated thermal effect on an epitaxial layer of the chip is increased, and the damage to the chip is difficult to avoid.

Accordingly, the prior art is yet to be improved and developed.

SUMMERY OF THE UTILITY MODEL

In view of the above-mentioned deficiencies of the prior art, an object of the present invention is to provide a patterned substrate and an LED chip, which aims to solve the problem of chip damage caused by excessive thermal effect generated during laser lift-off.

The technical scheme of the utility model as follows:

the patterned substrate comprises a substrate for growing an epitaxial layer and a microstructure arranged on the substrate, wherein the microstructure is arranged on the surface of one side of the substrate for growing the epitaxial layer, and the surface of the microstructure, which is in contact with the epitaxial layer, is an arc-shaped curved surface.

The patterned substrate is provided with a plurality of microstructures, and the plurality of microstructures are uniformly arrayed on the substrate.

The patterned substrate is characterized in that the distance between every two adjacent microstructures is 1 to 3 times of the cross-sectional diameter of each microstructure.

The patterned substrate, wherein the microstructure is a hemispherical microstructure.

The patterned substrate is characterized in that the diameter of the hemispherical microstructure ranges from 745nm to 1046 nm.

The patterned substrate is characterized in that the substrate is a sapphire substrate.

The patterned substrate is formed by integrally molding the microstructures and the substrate.

The application also discloses an LED chip, wherein the LED chip comprises the patterned substrate and an epitaxial layer grown on the patterned substrate.

The LED chip is characterized in that the epitaxial layer is a gallium nitride epitaxial layer.

The LED chip further comprises an N-type semiconductor layer, a light emitting layer, a P-type semiconductor layer and an electrode layer which are sequentially grown on one side, away from the patterned substrate, of the epitaxial layer.

Compared with the prior art, the embodiment of the utility model provides a have following advantage:

the utility model provides a set up the micro-structure that the surface is the arc curved surface on the graphical substrate, the chip structure is when doing laser and strip, laser pierces through the sapphire substrate, take place diffraction and scattering on the micro-structure surface, energy distribution when curved micro-structure surface makes laser pass is more even, improve whole energy utilization who is used for laser to strip, thereby it can realize peeling off to reach the laser that uses lower energy, reduce the laser and peel off required energy, reduce the damage of the thermal effect that laser produced to the chip structure, reduce the cracked risk of chip structure, improve whole chip and peel off the yield.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a patterned substrate and an LED chip prepared based on the patterned substrate in the prior art;

FIG. 2 is a schematic view of a patterned substrate according to the present invention;

fig. 3 is a schematic diagram of a patterned substrate and an LED chip prepared based on the patterned substrate according to the present invention;

FIG. 4 is a sagittal polar view of scattered light intensity;

FIG. 5 is another sagittal polar view of scattered light intensity.

Wherein, 1, a substrate; 2. a microstructure; 3. an epitaxial layer; 4. an N-type semiconductor layer; 5. a light emitting layer; 6. a P-type semiconductor layer; 7. and an electrode layer.

Detailed Description

In order to make the technical solution of the present invention better understood, the following figures in the embodiments of the present invention are combined to clearly and completely describe the technical solution in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In the prior art, the development of Micro LED technology is more and more mature, and the Micro LED is a new generation of display technology. Compared with the existing liquid crystal display, the flexible display has the advantages of higher photoelectric efficiency, higher brightness, higher contrast ratio and lower power consumption, can be combined with a flexible panel to realize flexible display, and has the same light-emitting principle as the traditional LED. The first key technology in the Micro LED display technology is a laser lift-off technology used for removing a sapphire substrate. Taking the LED of a blue-green plain film as an example, the laser energy penetrates through the double-polished sapphire substrate and is absorbed by the GaN layer to generate a chemical reaction: GaN → Ga + N₂。

Compared with the traditional light source, the GaN-based LED has the advantages of small volume, long service life, high efficiency, energy conservation, environmental protection and the like, and is widely applied to various fields of display, indicator lamps, backlight lamps, solid-state lighting, traffic signal lamps, short-range optical communication, biosensors and the like. Because of the lack of large-sized GaN substrates, GaN thin films are generally grown by heteroepitaxy on sapphire, silicon carbide or silicon substrates. Sapphire is the substrate most commonly used for commercial GaN-based LEDs at present due to its low price, good chemical and thermal stability. In the actual process, the light efficiency of the flat growth epitaxy and the prepared chip is weak, and in the long run, a patterned substrate technology is very necessary to be used for improving the light efficiency of the Micro LED.

However, as shown in fig. 1, in order to design a patterned sapphire structure for increasing the light emitting efficiency of an LED, a substrate 10 of a patterned substrate is first prepared with microstructures 20, which are regularly arranged, such as triangles, quadrangles, pyramids, etc., on a large number of LEDs, mini LEDs, and Micro LEDs, and the patterned substrate is then subjected to laser lift-off, the laser energy distribution is different between the patterned substrate and a flat substrate, and the energy of the patterned substrate is usually higher during laser lift-off, which may accumulate more thermal effects and easily cause chip cracking.

Referring to fig. 2 and 3, the patterned substrate disclosed in the present application includes a substrate 1 for growing an epitaxial layer 3, and a microstructure 2 disposed on the substrate 1, where the microstructure 2 is disposed on a side surface of the substrate 1 where the epitaxial layer 3 grows, and a surface of the microstructure 2 contacting the epitaxial layer 3 is an arc-shaped curved surface.

The utility model provides a set up the micro-structure 2 that the surface is the arc curved surface on the graphical substrate, the chip structure is when doing laser and strip, laser pierces through the sapphire substrate, diffraction and scattering take place on 2 surfaces of micro-structure, energy distribution when 2 surfaces of curved micro-structure make laser pass is more even, improve whole energy utilization who is used for laser to strip, thereby reach and use the laser of lower energy to realize peeling off, reduce the laser and peel off required energy, reduce the thermal effect that laser produced and to the injury of chip structure, reduce the cracked risk of chip structure, improve whole chip and peel off the yield.

Specifically, as shown in fig. 3, as an implementation manner of this embodiment, the plurality of microstructures 2 are provided, and the plurality of microstructures 2 are uniformly arranged on the substrate 1 in an array. Set up a plurality of microstructures 2, make the surface of making the chip structure on the base plate 1 all have microstructure 2 everywhere, when the laser is peeled off, each position can all peel off through lower energy, and then the heat effect that produces everywhere on the base plate 1 is the same, perhaps is close, reduces the heat and concentrates, further reduces the injury to the chip structure.

Specifically, as an implementation manner of this embodiment, the pitch between adjacent microstructures 2 is 1 to 3 times the cross-sectional diameter of the microstructures 2. When the microstructures 2 are manufactured, the adjacent microstructures 2 are not arranged too tightly, so that materials are wasted, the cost is increased, and the manufacturing process is high in requirement due to too close distance and is not easy to realize; and the microstructure 2 is not too loose, and the microstructure 2 has uneven effects on scattering, energy dispersion and the like generated on the substrate 1 in the laser stripping process due to too far interval between the adjacent microstructures 2, so that the laser stripping step is not favorably and smoothly completed. And it is preferable to set the pitch of the adjacent microstructures 2 to be 1 to 3 times the cross-sectional diameter of the microstructures 2. Preferably, the distance between every two adjacent microstructures 2 is equal to the diameter of the cross section of each microstructure 2, so that the number of the microstructures 2 is reasonable, and the overall stripping effect is good.

Specifically, as an implementation manner of this embodiment, the microstructure 2 is a hemispherical microstructure 2. The sections of the hemispherical microstructures 2 perpendicular to the substrate 1 in all directions are semicircular, so that the energy distribution of laser incident in any direction on the interface of the sapphire substrate 1 can be changed, the requirement on the incident direction of the laser is reduced, and the operation is convenient.

The technical scheme mainly aims to realize the purpose of improving the light emitting efficiency of the LED by patterning the sapphire substrate based on the semicircular microstructure 2. As shown in fig. 4, which is a vector diagram of energy distribution under a general condition, when laser passes through a specific surface, a part of laser energy continues to move forward, and a part of energy moves backward, in this case, the energy used for laser lift-off is only a certain proportion of the energy when the laser is emitted, so that the energy density of the laser is easily reduced, the laser lift-off can be smoothly performed by increasing the energy of the laser, and the epitaxial layer of the chip structure is inevitably damaged; and the hemispherical microstructure 2 is arranged, as shown in fig. 5, the striving effect of the energy distribution of the sapphire substrate is that the energy distribution is as shown in the figure, more than 90% of the energy is used for absorption, and the loss part only occupies a very small part. Therefore, the effective utilization rate of the laser is very high, so that the energy of the initial laser can be reduced, and the damage of the redundant loss laser to the chip is avoided.

Specifically, as an implementation manner of this embodiment, the diameter of the hemispherical microstructure 2 ranges from 745nm to 1046 nm. Theoretically, the sapphire refractive index m is equal to about 1.765 according to the equation for Mie scattering: where α is a dimensionless particle size parameter, m is the refractive index (referred to herein as the refractive index of the sapphire), d is the selected semi-circular particle size of the microstructure 2, and λ is the wavelength. The value of alpha corresponding to MIE scattering at a particular particle size can be calculated from the above equation. To achieve the effect shown in fig. 5, corresponding to 5 < α < 7, the required diameter of the hemispherical patterned microstructure 2 in the corresponding formula is 745nm 1046nm for a conventional 266nm laser wavelength.

Further, as an implementation manner of the present embodiment, the substrate 1 is a sapphire substrate 1. The sapphire substrate 1 is made of alumina (A12O3) which is formed by combining three oxygen atoms and two aluminum atoms in a covalent bond mode, the crystal structure is a hexagonal lattice structure, the optical penetration band of the sapphire is very wide, the sapphire has good light transmittance from near ultraviolet light (190nm) to middle infrared rays, and has the characteristics of high sound velocity, high temperature resistance, corrosion resistance, high hardness, high melting point and the like, and the lattice constant mismatch rate between the sapphire and a deposited film is small, so the sapphire substrate 1 can be used as an excellent material in the process of manufacturing an LED chip.

Specifically, as an implementation manner of this embodiment, the microstructure 2 is integrally formed with the substrate 1. The microstructure 2 and the substrate 1 are integrally formed, the joint is seamless, laser can directly pass through the microstructure, and the microstructure is stable in structure and convenient to use repeatedly.

In addition, as another embodiment of the present application, an LED chip is further disclosed, wherein the LED chip includes the patterned substrate as described in any one of the above, and an epitaxial layer 3 grown on the patterned substrate. In this embodiment, the epitaxial layer 3 is a gallium nitride epitaxial layer.

Specifically, as an implementation manner of this embodiment, as shown in fig. 3, the LED chip further includes an N-type semiconductor layer 4, a light emitting layer 5, a P-type semiconductor layer 6, and an electrode layer 7, which are sequentially grown on a side of the epitaxial layer 3 away from the patterned substrate.

It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. The patterned substrate is characterized by comprising a substrate for growing an epitaxial layer and a microstructure arranged on the substrate, wherein the microstructure is arranged on the surface of one side of the substrate for growing the epitaxial layer, and the surface of the microstructure, which is in contact with the epitaxial layer, is an arc-shaped curved surface.

2. The patterned substrate of claim 1, wherein the microstructures are provided in a plurality, and a plurality of the microstructures are uniformly arrayed on the substrate.

3. The patterned substrate of claim 2, wherein the pitch between adjacent microstructures is 1 to 3 times the cross-sectional diameter of the microstructures.

4. The patterned substrate of claim 1, wherein the microstructures are hemispherical microstructures.

5. The patterned substrate of claim 4, wherein the diameter of the hemispherical microstructure ranges from 745nm to 1046 nm.

6. The patterned substrate of claim 1 wherein the substrate is a sapphire substrate.

7. The patterned substrate of claim 1, wherein the microstructures are integrally formed with the base.

8. An LED chip comprising the patterned substrate of any one of claims 1 to 7, and an epitaxial layer grown on the patterned substrate.

9. The LED chip of claim 8, wherein said epitaxial layer is a gallium nitride epitaxial layer.

10. The LED chip of claim 8, further comprising an N-type semiconductor layer, a light emitting layer, a P-type semiconductor layer and an electrode layer sequentially grown on a side of the epitaxial layer facing away from the patterned substrate.