Patterned substrate, method for preparing patterned substrate, and LED chip

Abstract

The present invention provides a patterned substrate, a method for preparing the patterned substrate, and an LED chip. The preparation method includes providing a sapphire substrate, depositing a layer of yellow photoresist on the sapphire substrate, preparing a mask, transferring the pattern on the mask onto the yellow photoresist to obtain a first patterned sapphire substrate, etching and cleaning the first patterned sapphire substrate to obtain a second patterned sapphire substrate, preparing a photoresist layer on the second patterned sapphire substrate, removing the photoresist layer on the outer ring of the second patterned sapphire substrate to obtain a third patterned sapphire substrate, and etching and cleaning the third patterned sapphire substrate to obtain a fourth patterned sapphire substrate. The present invention provides a patterned substrate, a method for preparing the patterned substrate, and an LED chip, aiming to address the problem in the prior art of uneven morphology of the inner and outer rings of patterned sapphire substrates, which ultimately leads to a low yield of the outer ring of the extended crystal.

Description

Technical Field

[0001] The present invention relates to the technical field of LEDs, and in particular to a patterned substrate, a method for preparing the patterned substrate, and an LED chip. Background Art

[0002] Light Emitting Diode (LED) is a semiconductor electronic component that can emit light. Due to its small size, high brightness and low energy consumption, it has attracted the attention of more and more researchers.

[0003] Traditional LED chips are generally made from well-grown epitaxial wafers, and the quality of epitaxial wafer growth is inseparable from the substrate with a high degree of matching of the epitaxial wafer and the epitaxial crystal. Studies have found that the patterned surface structure of the patterned sapphire substrate can enhance the scattering of light between the GaN and substrate interface, reduce the dislocation density of the GaN epitaxial material, reduce the reverse leakage current, and improve the service life of the LED; on the other hand, multiple scattering at the interface between GaN and the sapphire substrate changes the emission angle of the totally reflected light, greatly increasing the probability of the LED light emitting from the sapphire substrate, thereby improving the light extraction efficiency.

[0004] With the continuous improvement of LED chip manufacturing technology, higher requirements are placed on patterned sapphire substrates. For example, to improve the effective matching degree of the extended crystal, in order to solve this problem, it is necessary to improve the yield and utilization rate of the outer ring of the wafer and improve the condition of the outer ring of the wafer, that is, to optimize the appearance of the patterned sapphire substrate. The traditional yellow light process, which is the process flow of coating, exposure, development, etching and cleaning, is limited by the problem of physical aluminum disk blocking in etching, resulting in uneven morphology of the inner and outer rings, which ultimately leads to serious loss of yield of the outer ring of the extended crystal. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a patterned substrate, a method for preparing a patterned substrate and an LED chip, aiming to solve the problem in the prior art that the inner and outer ring morphologies of the patterned sapphire substrate are uneven, which ultimately leads to a low yield of the outer ring of the extended crystal.

[0006] According to an embodiment of the present invention, a method for preparing a patterned substrate comprises:

[0007] Providing a sapphire substrate, and depositing a layer of yellow photoresist on the sapphire substrate, and at the same time, preparing a mask;

[0008] Transferring the pattern on the mask to the yellow photoresist to obtain a first patterned sapphire substrate;

[0009] Etching and cleaning the first patterned sapphire substrate to obtain a second patterned sapphire substrate;

[0010] preparing a photoresist layer on the second patterned sapphire substrate, and removing the photoresist layer on the outer circle of the second patterned sapphire substrate to obtain a third patterned sapphire substrate;

[0011] The third patterned sapphire substrate is etched and cleaned to obtain a fourth patterned sapphire substrate.

[0012] Preferably, the step of providing a sapphire substrate and depositing a layer of yellow photoresist on the sapphire substrate, and preparing a mask specifically includes:

[0013] The soft template solid colloid is prepared by putting the raw materials into a mixer and stirring them. The stirring time is 20 minutes to 60 minutes and the standing time is 4 hours to 8 hours.

[0014] The soft template solid colloid is placed in a soft template production machine to prepare the mask, wherein the preparation temperature is 100° C. to 150° C., the amount of glue is 50 g to 100 g, and the number of degassing is 10 to 50 times.

[0015] Preferably, the step of transferring the pattern on the mask to the yellow photoresist to obtain a first patterned sapphire substrate includes:

[0016] The mask is placed in an imprinting machine, and the yellow photoresist is imprinted to prepare the first patterned sapphire substrate, wherein the conditions are set as a temperature of 40°C to 80°C, a primary pressure of 0.5Kpa to 3Kpa, a secondary pressure of 10Kpa to 20Kpa, a boost position of 30mm to 40mm, an exposure time of 20s to 60s, a speed change position of 10mm to 20mm, and an imprinting time of 30s to 120s.

[0017] Preferably, the etching process is dry etching, wherein the gas pressure is 3mtorr to 10mtorr, the upper electrode power is 1500W to 2800W, the lower electrode power is 400W to 1000W, and the etching time is 2000s to 3000s.

[0018] Preferably, the cleaning process is a wet process, wherein the surface of the patterned sapphire substrate is cleaned using a mixed solvent of sulfuric acid and hydrogen peroxide.

[0019] Preferably, the process for preparing the photoresist layer is a yellow light process.

[0020] Preferably, the step of preparing a photoresist layer on the second patterned sapphire substrate and removing the photoresist layer on the outer circle of the second patterned sapphire substrate to obtain a third patterned sapphire substrate comprises:

[0021] The photoresist layer within a distance of 1 mm to 10 mm from the edge of the second patterned sapphire substrate is removed.

[0022] According to an embodiment of the present invention, a patterned substrate is prepared by the above-mentioned method for preparing a patterned substrate. The patterned substrate includes a sapphire substrate and an outgrowth layer extending outward from the sapphire substrate. The outgrowth layer includes a mask portion and a non-mask portion located outside the mask portion.

[0023] Preferably, the height of the mask portion is higher than that of the non-mask portion, and the width of the mask portion is greater than that of the non-mask portion.

[0024] An LED chip according to an embodiment of the present invention includes the above-mentioned patterned substrate.

[0025] Compared with the existing technology: yellow light coating is deposited on the provided sapphire substrate, and the pattern on the pre-prepared mask is transferred to the yellow light coating to form a first patterned sapphire substrate, and then the first patterned sapphire substrate is etched as a whole and cleaned to obtain a second patterned sapphire substrate with a certain shape, but the outer ring shape of the second patterned sapphire substrate prepared by the above process is uneven. In order to solve this problem, a photoresist layer is prepared on the second patterned sapphire substrate, and the photoresist layer of the outer ring of the second patterned sapphire substrate is removed to obtain a third patterned sapphire substrate, and the third patterned sapphire substrate is etched and cleaned to obtain a fourth patterned sapphire substrate. Since the photoresist layer of the outer ring of the second patterned sapphire substrate is removed, the outer ring of the patterned sapphire substrate undergoes two etchings, so that the morphology of the outer ring is optimized. In the process of preparing the photoresist layer on the second patterned sapphire substrate, the aluminum disk is no longer used, so the etching blocking problem is solved, and then a patterned sapphire substrate with uniform inner and outer ring morphology is prepared, thereby improving the yield of the epitaxial outer ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of the patterned substrate in the first embodiment of the present invention;

[0027] Figure 2 This is a flow chart of a method for preparing a patterned substrate proposed in Example 2 of the present invention. DETAILED DESCRIPTION

[0028] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0029] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] PSS (Patterned Sapphire Substrate) involves growing a dry-etching mask on a sapphire substrate. The mask is then patterned using standard photolithography techniques. The sapphire is then etched using ICP etching, and the mask is removed. GaN material is then grown on top, transforming the vertical epitaxy of the GaN material into a lateral epitaxy. This effectively reduces the dislocation density of the GaN epitaxial material, thereby minimizing non-radiative recombination in the active region, reducing reverse leakage current, and improving the lifespan of the LED. Furthermore, light emitted from the active region is scattered multiple times at the interface between the GaN and sapphire substrate, altering the angle of total internal reflection and increasing the probability of light from the flip-chip LED emitting from the sapphire substrate, thereby improving light extraction efficiency. These two factors combine to significantly enhance the brightness of LEDs grown on PSS compared to conventional LEDs, while also reducing reverse leakage current and extending LED lifespan.

[0032] ICP (Inductively Coupled Plasma) etching refers to a method of removing material using a plasma-activated chemical reaction or high-energy particle beam bombardment. Compared to wet etching, ICP etching is characterized by its anisotropic nature, resulting in steep and angled sidewalls. The ICP etching process involves both chemical and physical processes.

[0033] The chemical process is divided into two parts. The first part is the glow discharge of the etching gas under the action of the inductively coupled high-energy and high-frequency electromagnetic field, that is, active free radicals, metastable particles, atoms and other particles are generated under the action of the magnetic field, plasma is generated, and there is also a certain interaction between the ionized products; the second part is the interaction between these active particles and the solid surface of the substrate, that is, the etching process is a chemical reaction process at the interface between the gas phase and the solid phase. The process can generally be divided into three steps: first, the solid phase surface produces chemical adsorption of these chemically active substances; then the adsorbed active substances further react chemically with the solid phase surface, and the reaction products are volatile; finally, the reaction compounds on the solid phase surface are desorbed.

[0034] The main physical process in the etching process is the bombardment of ions on the substrate surface. The physical bombardment here is not equivalent to the purely physical process in sputtering etching. It has a significant auxiliary effect on the chemical reaction. That is, the electrons with higher kinetic energy can break the chemical bonds and play an etching role. This is similar to the reactive ion etching (RIE) process. It can also bombard the reaction products adsorbed on the surface and hinder further etching, desorbing the surface, promoting chemical reactions on the substrate surface and removing non-volatile residues on the substrate surface.

[0035] Example 1

[0036] See also Figure 1 , shown is a schematic structural diagram of the patterned substrate in Example 1 of the present invention, including a sapphire substrate 1 and an outgrowth crystal layer 4 extending outward from the sapphire substrate 1, the outgrowth crystal layer 4 includes a mask portion 2 and a non-mask portion 3 located outside the mask portion 2.

[0037] Among them, the material of the patterned substrate is Al2O3. In this embodiment, the outer extension crystal layer 4 is composed of a plurality of cones arranged, and can be divided into an outer circle and an inner circle according to the region. This is an example but not a limitation. In some other embodiments, the outer extension crystal layer 4 is composed of other shapes. Specifically, the area 1mm to 10mm away from the edge of the patterned sapphire substrate is the outer circle, and the area outside the outer circle is the inner circle. The plurality of cones in the outer circle are the non-mask part 3, and the plurality of cones in the inner circle are the mask part 2.

[0038] It should be noted that the height of the cone in the non-mask portion 3 is lower than the height of the cone in the mask portion 2, and the width of the cone in the non-mask portion 3 is smaller than the width of the cone in the mask portion 2. The closer the cone in the non-mask portion 3 is to the mask portion 2, the higher its height and the wider its width, presenting a gradual state, while the morphology of the cone in the mask portion 2 is relatively uniform. Specifically, the size of the cone in the mask portion 2 is 2.0um to 2.95um in width and 1.6um to 2.0um in height. Through the gradual patterning of the sapphire substrate, the problem of epitaxial outer ring crystal growth defects can be compensated, thereby improving the yield of the epitaxial outer ring.

[0039] Example 2

[0040] See also Figure 2 , Figure 2 A method for preparing a patterned substrate according to a second embodiment of the present invention is used to prepare the patterned substrate of the first embodiment. The method specifically includes steps S21 to S25, wherein:

[0041] Step S21 , providing a sapphire substrate, and depositing a layer of yellow photoresist on the sapphire substrate, and at the same time, preparing a mask.

[0042] It should be noted that the production of LED chips usually starts with the growth of epitaxial wafers, and the epitaxial layer is generally grown epitaxially on a substrate such as a sapphire substrate. In this embodiment, a mask plate needs to be prepared in advance. The mask plate is used to transfer the pattern on the mask plate to the yellow light coating after a layer of yellow light coating is deposited on the sapphire substrate.

[0043] Specifically, the preparation method of the mask is as follows: first, the colloidal raw material is put into a mixer, and a soft template colloid is produced by stirring the mixer, wherein the stirring time of the mixer is set to 20min~60min. After the stirring is completed, it needs to be left to stand for 4h~8h before it can be put into the next process. Subsequently, 50g~100g of the soft template colloid is taken and put into the mask production machine to prepare a mask with a predetermined pattern, wherein the preparation temperature is 100℃~150℃, and the number of debubbling times is 10 times~50 times.

[0044] In this embodiment, a yellow photoresist with a thickness of 1 μm to 3 μm is coated on the sapphire substrate by a coating machine and baked at a temperature of 50° C. to 150° C. for 60 seconds to 150 seconds. After baking, the excess resist is removed and the substrate is transferred to the next process.

[0045] Step S22: transferring the pattern on the mask to the yellow photoresist to obtain a first patterned sapphire substrate.

[0046] Among them, the process of pattern transfer is a nanoimprint process. Specifically, the mask is placed in the imprint machine, and the yellow photoresist deposited on the sapphire substrate is imprinted to complete the replication of the pattern on the mask. The conditions are set as a temperature of 40℃~80℃, a primary pressure of 0.5Kpa~3Kpa, a secondary pressure of 10Kpa~20Kpa, a boost position of 30mm~40mm, an exposure time of 20s~60s, a speed change position of 10mm~20mm, and an imprint time of 30s~120s. Finally, a columnar pattern with a period of 3μm, a width of 1.5μm~2.5μm, and a height of 2μm~3μm is obtained, that is, the first patterned sapphire substrate is obtained.

[0047] Step S23: etching and cleaning the first patterned sapphire substrate to obtain a second patterned sapphire substrate.

[0048] Specifically, the etching process is ICP etching, which is carried out in an ICP device. The first patterned sapphire substrate is subjected to plasma etching, that is, a regular conical pattern is formed on the first patterned sapphire substrate. Specifically, the first patterned sapphire substrate is placed face up, that is, the side to be processed faces up, and fixed on an aluminum carrier plate. The aluminum carrier plate with the first patterned sapphire substrate fixed is then placed in the reaction chamber of the ICP device. The chamber is evacuated to a chamber pressure of 3mtorr to 10mtorr, and then process gas and auxiliary gas are introduced. The process gas can be a mixture of one or more of chlorine, boron trichloride, trifluoromethane, carbon tetrafluoride and sulfur hexafluoride, and the auxiliary gas can be a mixture of one or more of helium, nitrogen and oxygen. While the gas is introduced, the upper and lower electrode powers of the ICP equipment are turned on, wherein the upper electrode power is 1500W~2800W, the lower electrode power is 400W~1000W, and the etching time is 2000s~3000s. Finally, a conical pattern with a width of 2.0μm~2.95μm and a height of 1.6μm~2.0μm is prepared.

[0049] In addition, cleaning is performed on the basis of the above, and the cleaning process is a wet process, which mainly uses a mixed solvent of sulfuric acid and hydrogen peroxide to clean the surface of the patterned sapphire substrate. Among them, the mixing ratio of sulfuric acid and hydrogen peroxide can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, etc., which mainly cleans the gas remaining on the surface and the reaction products and carbonized substances in the etching process.

[0050] It should be noted that since the first patterned sapphire substrate is limited by the physical aluminum disk obstruction problem during etching, the outer ring morphology of the first patterned sapphire substrate will be uneven. In order to solve this problem, the morphology of the outer ring part needs to be optimized, that is, etching again. However, the traditional imprinting technology faces the problem that the machine parameters cannot be changed autonomously, which makes it difficult to achieve the optimization of the outer ring through traditional technology. Specifically, the traditional exposure machine can freely change the exposure patterns of the inner and outer rings of the film source, which can solve the outer ring morphology problem while effectively maintaining the stability of the imprint size.

[0051] Step S24: preparing a photoresist layer on the second patterned sapphire substrate, and removing the photoresist layer on the outer circle of the second patterned sapphire substrate to obtain a third patterned sapphire substrate.

[0052] It can be understood that the process of preparing the photoresist layer on the second patterned sapphire substrate is a yellow light process, that is, through processes such as coating, exposure, and development, a photoresist layer is deposited on the second patterned sapphire substrate, and then the photoresist layer at a distance of 1mm to 10mm from the edge of the second patterned sapphire substrate is removed to obtain a third patterned sapphire substrate.

[0053] Step S25 , etching and cleaning the third patterned sapphire substrate to obtain a fourth patterned sapphire substrate.

[0054] In this embodiment, after the third patterned sapphire substrate is prepared, the third patterned sapphire substrate is etched for the second time using an ICP device. Since the photoresist layer has a certain protective effect, during the second etching process, the etching is mainly performed on the portion of the third patterned sapphire substrate that is not covered by the photoresist layer, that is, the outer circle area of ​​the third patterned sapphire substrate, and a gradient pattern is etched in the outer circle area, wherein the pattern height of the inner circle area in the third patterned sapphire substrate is higher than the pattern height of the outer circle area, and the width of the inner circle area is greater than the pattern width of the outer circle area.

[0055] In summary, the current blocking layer and the preparation method of the current blocking layer in the embodiments of the present invention deposit yellow light coating on the provided sapphire substrate, and transfer the pattern on the pre-prepared mask plate to the yellow light coating to form a first patterned sapphire substrate. The first patterned sapphire substrate is then etched as a whole and cleaned to obtain a second patterned sapphire substrate with a certain shape. However, the outer ring shape of the second patterned sapphire substrate prepared by the above process is uneven. In order to solve this problem, a photoresist layer is prepared on the second patterned sapphire substrate, and the photoresist layer of the outer ring of the second patterned sapphire substrate is removed to obtain a third patterned sapphire substrate. The third patterned sapphire substrate is etched and cleaned to obtain a fourth patterned sapphire substrate. Since the photoresist layer of the outer ring of the second patterned sapphire substrate is removed, the outer ring of the patterned sapphire substrate undergoes two etchings, so that the outer ring morphology is optimized, and then a patterned sapphire substrate with uniform inner and outer ring morphology is prepared, thereby improving the yield of the epitaxial outer ring.

[0056] Example 3

[0057] A third embodiment of the present invention provides an LED chip, comprising the patterned substrate of the first embodiment. The patterned substrate can be manufactured by the method for preparing the patterned substrate of the second embodiment.

[0058] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a patterned substrate, characterized in that: The preparation method comprises: Providing a sapphire substrate, and depositing a layer of yellow photoresist on the sapphire substrate, and at the same time, preparing a mask; Transferring the pattern on the mask to the yellow photoresist to obtain a first patterned sapphire substrate; Etching and cleaning the first patterned sapphire substrate to obtain a second patterned sapphire substrate; preparing a photoresist layer on the second patterned sapphire substrate, and removing the photoresist layer on the outer circle of the second patterned sapphire substrate to obtain a third patterned sapphire substrate; Etching and cleaning the third patterned sapphire substrate to obtain a fourth patterned sapphire substrate; The finally prepared patterned substrate includes a sapphire substrate and an outgrowth crystal layer extending outward from the sapphire substrate, the outgrowth crystal layer includes a mask portion and a non-mask portion located outside the mask portion, the height of the mask portion is higher than the height of the non-mask portion, the width of the mask portion is greater than the width of the non-mask portion, and the closer the non-mask portion is to the mask portion, the higher its height and the wider its width.

2. The method for preparing a patterned substrate according to claim 1, wherein: The steps of providing a sapphire substrate and depositing a layer of yellow photoresist on the sapphire substrate and preparing a mask specifically include: The soft template solid colloid is prepared by putting the raw materials into a mixer and stirring them. The stirring time is 20min~60min and the standing time is 4h~8h. The soft template solid colloid is placed in a soft template production machine to prepare the mask, wherein the preparation temperature is 100° C. to 150° C., the amount of glue is 50 g to 100 g, and the number of degassing is 10 to 50 times.

3. The method for preparing a patterned substrate according to claim 1, wherein: The step of transferring the pattern on the mask to the yellow photoresist to obtain a first patterned sapphire substrate includes: The mask is placed in an imprint machine, and the yellow photoresist is imprinted to prepare the first patterned sapphire substrate, wherein the conditions are set as a temperature of 40°C to 80°C, a primary pressure of 0.5Kpa to 3Kpa, a secondary pressure of 10Kpa to 20Kpa, a boost position of 30mm to 40mm, an exposure time of 20s to 60s, a speed change position of 10mm to 20mm, and an imprint time of 30s to 120s.

4. The method for preparing a patterned substrate according to claim 1, wherein: In the step of etching and cleaning the first patterned sapphire substrate to obtain the second patterned sapphire substrate, the etching process is dry etching, wherein the gas pressure is 3mtorr~10mtorr, the upper electrode power is 1500W~2800W, the lower electrode power is 400W~1000W, and the etching time is 2000s~3000s.

5. The method for preparing a patterned substrate according to claim 1, wherein: In the step of etching and cleaning the first patterned sapphire substrate to obtain the second patterned sapphire substrate, the cleaning process is a wet process, wherein the surface of the patterned sapphire substrate is cleaned using a mixed solvent of sulfuric acid and hydrogen peroxide.

6. The method for preparing a patterned substrate according to claim 1, wherein: The process for preparing the photoresist layer is a yellow light process.

7. The method for preparing a patterned substrate according to claim 1, wherein: The step of preparing a photoresist layer on the second patterned sapphire substrate and removing the photoresist layer on the outer circle of the second patterned sapphire substrate to obtain a third patterned sapphire substrate includes: The photoresist layer within a distance of 1 mm to 10 mm from the edge of the second patterned sapphire substrate is removed.

8. An LED chip, characterized in that: The invention comprises a patterned substrate prepared by the method for preparing a patterned substrate according to any one of claims 1 to 7.

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