Growth method based on atomic layer etching substrate structure, substrate structure and LED device

Abstract

The invention provides a substrate structure growth method based on atomic layer etching, a substrate structure and an LED device. The substrate structure growth method comprises the following steps: S1, providing a substrate; the surface comprises a defect area and a non-defect area; s2, forming a micro mask in the non-defect area and exposing the defect area; s3, reducing the roughness of the defect area through physical etching; s4, repeatedly and alternately performing S2 and S3 until the surface roughness of the etched substrate reaches the preset roughness; and S5, carrying out epitaxial growth on the etched substrate so as to grow the micro-nano conical structure in the non-defect area. According to the method, the roughness of the surface of the substrate is remarkably reduced through a process of alternately performing chemical etching to form the micro mask and performing physical etching to reduce the roughness of the defect region, so that accurate regulation and control on the micro-nano conical structure can be realized on the basis. The method has the advantages of high controllability, low cost, high substrate quality, convenience in batch processing and the like, and can be applied to the field of preparation of the gallium nitride substrate.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a growth method based on atomic layer etching substrate structure, a substrate structure and an LED device. Background Art

[0002] In the development of semiconductor materials, gallium nitride (GaN) has played an important role in the fields of microelectronics and optoelectronics due to its excellent physical and chemical properties, such as wide bandgap, high electron mobility, high breakdown field strength, etc. In particular, GaN plays an irreplaceable role in the manufacturing of optoelectronic devices such as light-emitting diodes (LEDs) and lasers.

[0003] It is worth noting that the roughness of the GaN material surface has a significant impact on device performance. The rough surface not only increases the series resistance of the device and reduces the electron mobility, but also leads to a decrease in luminous efficiency, which seriously affects the overall performance of the device. Therefore, reducing the surface roughness of GaN and improving device performance have always been the key research directions in this field.

[0004] However, in the existing technology system, polishing technology is usually used to reduce the surface roughness of GaN, such as chemical mechanical polishing (CMP). However, this technology has many disadvantages. Not only is the equipment purchase cost high and the process complicated, but impurities are easily introduced during the polishing process, affecting the purity of the GaN material and device performance. In addition, in the preparation of micro-nano conical structures, commonly used technologies such as electron beam exposure and focused ion beam etching also have problems such as high equipment cost, low production efficiency, and difficulty in large-scale production, which seriously restricts the further development and application of related technologies.

[0005] Therefore, both the CMP technology used to reduce surface roughness and the micro-nano cone structure preparation technology have poor controllability in the device growth process. In actual operation, it is difficult to accurately adjust various parameters to achieve fine control of the device growth process, which makes it difficult to effectively adjust the device quality and performance according to different application requirements during the manufacturing process, greatly hindering the development of GaN-based devices towards higher performance and better quality. Summary of the invention

[0006] To this end, the technical problem to be solved by the present invention is to overcome the problem in the prior art that substrate processing easily affects device performance, and to provide a growth method, substrate structure and LED device based on atomic layer etching substrate structure.

[0007] To solve the above technical problems, in a first aspect, the present invention provides a growth method based on an atomic layer etching substrate structure, which includes:

[0008] Step S1, provide a substrate; wherein, the surface of the substrate includes a defect area and a non-defect area;

[0009] Step S2, chemically etch the substrate with an etching gas to form a micro-mask in the non-defect area and expose the defect area;

[0010] Step S3, physically etch the substrate so that the roughness of the defect area after physical etching is less than the roughness of the defect area before physical etching;

[0011] Step S4, repeat steps S2 and S3 alternately until the surface roughness of the etched substrate reaches a preset roughness; Step S5, perform epitaxial growth on the etched substrate to grow micro-nano conical structures protruding from the surface of the substrate in the non-defect area, obtaining a substrate structure.

[0012] In an embodiment of the present invention, the etching gas is a fluorine-containing gas, and the chemically etching the substrate with the etching gas to form a micro-mask in the non-defect area and expose the defect area includes: under the conditions of an etching temperature of 55-65 °C, an etching pressure of 10-20 mTorr, and an etching power of 600-1200 W, introducing a fluorine-containing gas with a flow rate of 10-80 sccm to chemically etch the substrate for 10-30 s to form the micro-mask in the non-defect area.

[0013] In an embodiment of the present invention, physically etching the substrate includes: under the conditions of an etching temperature of 55-65 °C, an etching pressure of 10-20 mTorr, and an etching power of 1500-2500 W, introducing an inert gas with a flow rate of 50-80 sccm to physically bombard and etch the substrate for 10-30 s;

[0014] Wherein, the inert gas includes nitrogen, argon or helium.

[0015] In an embodiment of the present invention, a chemical vapor deposition method is used to grow the micro-nano conical structures on the etched substrate; wherein, the physical parameters of the micro-nano conical structures are related to the growth parameters; the physical parameters include size or density, and the growth parameters include time, temperature or growth pressure.

[0016] In one embodiment of the present invention, the height of the micro-nano conical structure is 15 - 20 μm; and / or, the bottom diameter of the micro-nano conical structure is 10 - 15 μm; and / or, the density of the micro-nano conical structure is 5000 - 8000 pieces / cm 2 .

[0017] In one embodiment of the present invention, the growth temperature of the micro-nano conical structure is proportional to the size of the micro-nano conical structure; and / or, the growth time of the micro-nano conical structure is proportional to the size of the micro-nano conical structure; and / or, the growth pressure of the micro-nano conical structure is inversely proportional to the size of the micro-nano conical structure.

[0018] In one embodiment of the present invention, the growth temperature of the micro-nano conical structure is proportional to the density of the micro-nano conical structure; and / or, the growth time of the micro-nano conical structure is proportional to the density of the micro-nano conical structure; and / or, the growth pressure of the micro-nano conical structure is proportional to the density of the micro-nano conical structure.

[0019] In one embodiment of the present invention, the preset roughness < 0.1 nm; and / or, the number of cycles of S2 - S3 is 20 - 50 times; and / or, the material of the micro-nano conical structure is the same as that of the substrate; and / or, the etching gas is sulfur hexafluoride gas, and the material of the micro-mask is SiFx.

[0020] In one embodiment of the present invention, epitaxial growth of the micro-nano conical structure on the etched substrate includes: introducing a reaction gas for 10 - 120 min on the etched substrate under the conditions of a growth temperature of 975 - 1080 °C and a growth pressure of 100 - 400 mbar to obtain the micro-nano conical structure; wherein, the reaction gas includes ammonia with a flow rate of 25000 - 35000 sccm and trimethylgallium with a flow rate of 30 - 150 sccm.

[0021] In a second aspect, the present invention further provides a substrate structure, which includes: a substrate, the surface of the substrate includes a defective area and a non-defective area; a micro-mask, the micro-mask covers the non-defective area; a micro-nano conical structure, the micro-nano conical structure is disposed on the non-defective area; wherein, the height of the surface of the micro-nano conical structure away from the substrate exceeds the height of the surface of the micro-mask away from the substrate.

[0022] In a third aspect, the present invention further provides an LED device, which includes a substrate structure and a light-emitting structure disposed on the substrate structure; wherein, the substrate structure is the substrate structure described in claim 9; or, the substrate structure is prepared by using the growth method of the atomic layer etching-based substrate structure described in any one of claims 1 - 8.

[0023] The present invention realizes precise control of the surface roughness of the substrate, and solves the problem that it is difficult to balance surface quality and structure preparation in the traditional process. The alternating etching process effectively eliminates surface defects, and the selective inhibition of the protective layer during the epitaxial growth process promotes the directional formation of the micro-nano conical structure. This integrated process provides a controllable preparation method for the manufacture of high-performance optoelectronic devices. Through the above technical solutions, the present invention solves the problems of carrier scattering and light loss caused by high surface roughness, and reduces the process complexity and cost of preparing the micro-nano conical structure. Through the synergistic effect of alternating etching and epitaxial growth, the active regulation of the substrate surface morphology and microstructure is realized, and the light-emitting efficiency and performance consistency of the LED device are improved. Description of the Drawings

[0024] In order to make the content of the present invention easier to be clearly understood, the present invention will be further described in detail below according to specific embodiments of the present invention in conjunction with the drawings.

[0025] Figure 1 is a flowchart of the growth method of the substrate structure based on atomic layer etching provided by the present invention;

[0026] Figure 2 is Figure 1 a schematic process diagram of the growth method of the substrate structure based on atomic layer etching shown;

[0027] Figure 3 is a schematic structural diagram of the substrate structure provided by the present invention;

[0028] Figure 4 is a three-dimensional structural schematic diagram of the micro-nano conical structure under a microscope provided in Embodiment 1;

[0029] Figure 5 is a top-view structural schematic diagram of the micro-nano conical structure under a microscope provided in Embodiment 1.

[0030] Explanation of the reference numerals in the drawings: 100, substrate; 200, micro-mask; 300, micro-nano conical structure. Detailed Embodiments

[0031] The present invention will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the specific embodiments cited do not limit the present invention.

[0032] In the existing technology, the surface roughness of semiconductor materials such as gallium nitride directly affects the performance of the device, but the traditional polishing technology has the defects of high equipment cost, complex process and easy introduction of impurities. The preparation technology of micro-nano cone structure relies on electron beam exposure or focused ion beam etching, which has the bottleneck of low production efficiency and difficulty in large-scale application. These limitations lead to insufficient control accuracy of device surface roughness, and the controllability of epitaxial growth process is poor, which cannot meet the manufacturing needs of high-performance devices.

[0033] As an emerging technology in the field of micro-nano manufacturing, atomic layer etching (ALE) achieves atomic-level precision material removal capabilities with its unique self-limiting reaction mechanism. This high-precision feature gives it a significant advantage in the field of substrate processing. Compared with dry etching and wet etching, ALE can not only work in a low-temperature environment with almost no damage to the material, and is suitable for processing sensitive systems such as two-dimensional materials and quantum devices, but is also compatible with the uniform etching of complex structures such as three-dimensional nanopillars and high aspect ratio channels, avoiding the etching limitations of traditional methods on non-planar substrates.

[0034] The present invention provides a growth method for substrate structure based on atomic layer etching. By analyzing the selective deposition characteristics of chemical etching, it is found that etching byproducts can form micro-masks in specific areas, and then combined with the directional removal ability of physical etching, layer-by-layer correction of surface defects is achieved. Based on the self-limiting characteristics of atomic layer etching technology, the present invention proposes a synergistic mechanism of alternating etching and epitaxial growth, and realizes precise control of surface morphology through a cyclic process; combined with reference to Figure 1 and Figure 2 The present invention provides a method for growing a substrate structure based on atomic layer etching, which includes:

[0035] Step S1: Figure 2 As shown in (a), a substrate is provided; wherein the surface of the substrate includes a defect area and a non-defect area.

[0036] The defective area and the non-defective area refer to local areas where there is a difference in the crystal integrity of the substrate surface. Among them, the defective area has a large roughness, and the surface of the non-defective area is relatively flat. Based on this, the defective area needs to be flattened in a targeted manner.

[0037] Furthermore, the defective area and the non-defective area can be specifically identified by material defect detection technology, and this division enables subsequent processing to have regional selectivity.

[0038] Step S2: Figure 2 As shown in (b), the substrate is chemically etched using an etching gas to form a micro mask in the non-defective area and expose the defective area.

[0039] Chemical etching to form a micro-mask refers to generating a protective film through the reaction of an etching gas with a substrate material. For example, a fluorine-containing gas reacts with a silicon-based substrate to form a fluorosilicon compound, and this film protects non-defective areas during subsequent physical etching.

[0040] Furthermore, the etching gas is a fluorine-containing gas. The substrate is chemically etched with the etching gas to form a micro-mask in the non-defective area and expose the defective area. Specifically, the atomic arrangement of the amorphous material in the substrate lacks long-range order, the surface atoms have incomplete coordination, there are a large number of dangling bonds, defects, and active sites, resulting in a relatively high surface energy, which makes it easy to adsorb impurities such as Si, O, or C in the surrounding environment. Taking a gallium nitride substrate as an example, there is a certain chemical affinity between N atoms and Si atoms, and the active sites on the N surface are prone to form weak bonds or physical adsorption with Si atoms. Therefore, the fluorine-containing gas will react with the Si atoms on the substrate surface to form a micro-mask. The specific principle is as follows:

[0041] SF→SF x +F * +F-+SF6

[0042] F * +Si→Si4↑

[0043] Among them, SF6 can hardly spontaneously undergo a chemical reaction with silicon at room temperature, so external radio frequency is used to ionize SF6 to obtain F* free radicals. Four F* free radicals combine with Si atoms to form a volatile SiF4 by-product and leave the substrate surface and are discharged.

[0044] Furthermore, taking sulfur hexafluoride gas as an example, it can form a micro-mask with the material of SiF x in the non-defective area of the substrate.

[0045] In a specific embodiment, the process of chemically etching the substrate with the etching gas specifically includes: under the conditions of an etching temperature of 55 - 65 °C, an etching pressure of 10 - 20 mTorr, and an etching power of 600 - 1200 W, a fluorine-containing gas with a flow rate of 10 - 80 sccm is introduced to chemically etch the substrate for 10 - 30 s to form a micro-mask in the non-defective area.

[0046] For example, the etching temperature can be 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C or 65°C, the etching pressure can be 10 mTorr, 11 mTorr, 12 mTorr, 13 mTorr, 14 mTorr, 15 mTorr, 16 mTorr, 17 mTorr, 18 mTorr, 19 mTorr or 20 mTorr, the etching power can be 600 W, 650 W, 700 W, 750 W, 800 W, 850 W, 900 W, 950 W, 1000 W, 1050 W, 1100 W, 1150 W or 1200 W, the flow rate of the fluorine-containing gas can be 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm or 80 sccm, and the time of chemical etching can be 10 s, 12 s, 14 s, 16 s, 18 s, 20 s, 22 s, 24 s, 26 s, 28 s or 30 s.

[0047] Furthermore, at an etching temperature of 55-65°C, the chemical reaction rate between the fluorine-containing gas and the substrate material is effectively controlled, which can not only maintain the sufficient reaction between the fluorine-containing gas and the substrate material, but also avoid the damage of the micro-mask structure caused by too high temperature; an etching pressure of 10-20 mTorr is beneficial to stabilizing the plasma discharge state, and an etching power of 600-1200 W can not only effectively dissociate the fluorine-containing gas to generate active radicals, but also prevent the substrate surface from being damaged by too strong energy; a fluorine-containing gas flow rate of 10-80 sccm can ensure that the reactant concentration and the reaction rate reach the best balance; a chemical etching time of 10-30 s can achieve uniform coverage of the passivation layer on the surface of the non-defect area. Thus, by controlling the total amount of reactant supply, a dense fluoride passivation layer is formed in the non-defect area, while the defect area is more easily selectively etched due to lattice distortion.

[0048] Furthermore, compared with the prior art, traditional chemical etching processes mostly adopt fixed temperature and power parameters, and it is difficult to accurately control the balance relationship between the reaction rate and the passivation layer formation rate. This solution breaks through the problem that the etching rate and the protection effect are incompatible in conventional etching processes by defining the coordinated parameter ranges of temperature, pressure, power, flow rate and time. Compared with the broad parameter setting method, this parameter combination can effectively suppress the phenomenon of lateral etching caused by isotropic etching. Through the above technical solutions, the present invention realizes the uniform and controllable growth of the micro-mask structure in the non-defect area, while ensuring that the defect area is fully exposed. Precise temperature and power ensure the uniform distribution of fluorine radicals on the substrate surface, and the defined time parameter avoids the damage of the micro-mask caused by over-etching. This parameter system significantly improves the etching selectivity and process repeatability through the synergistic effect of multi-dimensional process conditions, providing an ideal surface topography basis for subsequent physical etching processes.

[0049] Step S3: Physically etch the substrate so that the roughness of the defective area after physical etching is less than that of the defective area before physical etching.

[0050] In the present invention, an inert gas such as nitrogen, argon or helium is used to bombard and etch the defective area. Specifically, in the present invention, under the conditions of an etching temperature of 55 - 65 °C, an etching pressure of 10 - 20 mTorr, and an etching power of 1500 - 2500 W, an inert gas with a flow rate of 50 - 80 sccm is introduced to perform physical bombardment etching on the substrate for 10 - 30 s.

[0051] For example, the etching temperature can be 55 °C, 56 °C, 57 °C, 58 °C, 59 °C, 60 °C, 61 °C, 62 °C, 63 °C, 64 °C or 65 °C, the etching pressure can be 10 mTorr, 11 mTorr, 12 mTorr, 13 mTorr, 14 mTorr, 15 mTorr, 16 mTorr, 17 mTorr, 18 mTorr, 19 mTorr or 20 mTorr, the etching power can be 1500 W, 1600 W, 1700 W, 1800 W, 1900 W, 2000 W, 2100 W, 2200 W, 2300 W, 2400 W or 2500 W, the flow rate of the inert gas can be 50 sccm, 52 sccm, 54 sccm, 56 sccm, 58 sccm, 60 sccm, 62 sccm, 64 sccm, 66 sccm, 68 sccm, 70 sccm, 72 sccm, 74 sccm, 76 sccm, 78 sccm or 80 sccm, and the time of physical bombardment etching can be 10 s, 12 s, 14 s, 16 s, 18 s, 20 s, 22 s, 24 s, 26 s, 28 s or 30 s.

[0052] Furthermore, the etching temperature of 55 - 65 °C can maintain the plasma activity while avoiding lattice distortion of the material due to high temperature; the etching pressure of 10 - 20 mTorr and the etching power of 1500 - 2500 W act synergistically to form a stable plasma environment and simultaneously generate a high-energy particle flow with sufficient kinetic energy. The bombardment of the inert gas for 10 - 30 s can prevent excessive removal of the material on the premise of ensuring sufficient etching of the defective area, so that each physical etching can remove about the surface material of a single atomic layer thickness, and the step-by-step planarization of the defective area is realized through multiple cycles.

[0053] Furthermore, based on the limitation of the physical bombardment etching parameters in the present invention, the problem of poor etching uniformity caused by parameter mismatch in the traditional process is effectively solved, and the problem of poor etching uniformity caused by parameter mismatch in the traditional process is significantly reduced, providing a repeatable operation basis for the subsequent alternating cycle of chemical etching - physical etching.

[0054] Step S4: Repeat steps S2 and S3 alternately until the surface roughness of the etched substrate reaches a preset roughness.

[0055] The alternating etching steps refer to the periodic cycle of chemical and physical etching. In each cycle, chemical etching repairs the micro-mask, and physical etching continuously corrects the morphology of the defect area. This cycle mechanism realizes the progressive optimization of the surface roughness.

[0056] Further, the preset roughness is less than 0.1 nm. At present, the general polishing technology is used to process the substrate structure, and its roughness cannot reach the sub-nanometer level. However, the present invention can make the preset roughness less than 0.1 nm by controlling the alternation of chemical etching and physical bombardment etching, thereby making the substrate have better substrate flatness. Specifically, the cycle termination condition can be controlled by an on-line spectroscopic analysis system.

[0057] Further, the number of cycles of chemical etching and physical etching in the present invention is set to 20 to 50 times. In this way, it can not only achieve the layer-by-layer removal of the material in the defect area, but also avoid over-etching damage to the structure in the non-defect area, thereby forming a highly ordered crystal structure.

[0058] Through the above technical solutions, the present invention realizes the atomic-level precise control of the surface morphology, improves the repeatability and controllability of the etching process, effectively solves the problem of lattice mismatch at the heterointerface, and provides a surface quality guarantee for the preparation of high-performance optoelectronic devices.

[0059] Step S5: As shown in (c) of Figure 2 epitaxial growth is performed on the etched substrate to grow micro-nano conical structures protruding from the substrate surface in the non-defect area, obtaining a substrate structure.

[0060] The present invention uses chemical vapor deposition to grow micro-nano conical structures on the etched substrate. Specifically, it can be realized by a metal-organic chemical vapor deposition (MOCVD) device, which can achieve atomic-level control accuracy, and then perform ordered growth on the basis of the surface morphology formed by atomic layer etching.

[0061] Further, the material of the micro-nano conical structure in the present invention is the same as that of the substrate, so molecular beam epitaxy equipment can be used for homoepitaxial growth.

[0062] Furthermore, the physical parameters of the micro-nano conical structure in the present invention are related to the growth parameters; the physical parameters include size or density, and the growth parameters include time, temperature or growth pressure. Based on this, by adjusting the time, temperature or pressure in the process conditions, the crystal nucleation rate, surface mobility and gas-phase transport efficiency can be changed, so as to realize the directional regulation of the geometric characteristics of the micro-nano conical structure.

[0063] The growth temperature of the micro-nano conical structure in the present invention is proportional to the size of the micro-nano conical structure; and / or, the growth time of the micro-nano conical structure is proportional to the size of the micro-nano conical structure; and / or, the growth pressure of the micro-nano conical structure is inversely proportional to the size of the micro-nano conical structure.

[0064] Furthermore, the growth temperature of the micro-nano conical structure is proportional to the density of the micro-nano conical structure; and / or, the growth time of the micro-nano conical structure is proportional to the density of the micro-nano conical structure; and / or, the growth pressure of the micro-nano conical structure is proportional to the density of the micro-nano conical structure.

[0065] Traditional electron beam lithography or ion beam etching techniques rely on complex mask preparation and precise equipment operation, and it is difficult to continuously adjust the structural parameters at the nanoscale. However, in this solution, through the controllable characteristics of nucleation and growth kinetics in the chemical vapor deposition process, directly using the physical correlation between the growth parameters and the structural parameters, without replacing the mask or adjusting the equipment configuration, only by numerically adjusting the process parameters, the lateral size and distribution density of the micro-nano conical structure can be precisely controlled.

[0066] Specifically, in the present invention, increasing the temperature can enhance the diffusion ability of the atoms on the material surface, and promote the preferential aggregation of the deposited atoms in the defect area to form larger-sized micro-nano conical structures. Therefore, the growth temperature of the micro-nano conical structure is proportional to the size of the micro-nano conical structure.

[0067] Correspondingly, when the growth temperature increases, the kinetic energy of the atoms on the material surface increases accordingly, making the diffusion distance of the adsorbed atoms on the substrate surface increase, thus promoting the formation of more nucleation sites and realizing the linear growth of the density of the micro-nano conical structure. Therefore, the growth temperature of the micro-nano conical structure can be proportional to the density of the micro-nano conical structure.

[0068] Furthermore, extending the growth time can increase the total amount of material deposition, and enable the micro-nano conical structure to grow continuously along the longitudinal direction. When the growth time is extended, the continuous deposition process of atoms on the surface of the structure is strengthened, so that the cone height and the base diameter increase synchronously, making the growth time of the micro-nano conical structure proportional to the size of the micro-nano conical structure.

[0069] Correspondingly, a longer growth time allows more reactants to deposit and form a densely distributed nucleation center. Therefore, when the growth time is extended, the deposition process of reactants on the substrate surface continues, and the probability of nucleation growth and coalescence gradually accumulates, ultimately manifested as a stepwise increase in the density of the micro-nano conical structure.

[0070] Furthermore, reducing the growth pressure can reduce the probability of gas-phase nucleation and force the deposition reaction to concentrate on the etched active sites. When the growth pressure increases, the mean free path of the reaction gas molecules shortens, resulting in the suppression of the material deposition rate and further restricting the longitudinal growth trend of the structure.

[0071] In summary, through the respective action mechanisms of the three parameters of temperature, growth temperature, and growth time, a synergistic regulation network is formed, enabling the size of the micro-nano conical structure to be independently or jointly adjusted in different dimensions. Thus, the problem of insufficient parameter adjustment accuracy during the growth process of the micro-nano conical structure is effectively solved, and the linear regulation of the geometric characteristics of the micro-nano conical structure is achieved. Furthermore, it enables the operator to customize the preparation of the micro-nano conical structure by adjusting a single or multiple combinations of growth parameters according to the electrical or optical performance requirements of the target device.

[0072] In one embodiment, the height of the micro-nano conical structure is 15 - 20 μm, for example: 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm; the bottom diameter of the micro-nano conical structure is 10 - 15 μm, for example: 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm; the density of the micro-nano conical structure is 5000 - 8000 pieces / cm 2 , for example: 5000 pieces / cm 2 , 5500 pieces / cm 2 , 6000 pieces / cm 2 , 6500 pieces / cm 2 , 7000 pieces / cm 2 , 7500 pieces / cm 2 or 8000 pieces / cm 2 .

[0073] In one embodiment, the epitaxial growth of the micro-nano conical structure on the etched substrate includes: under the conditions of a growth temperature of 975 - 1080 °C and a growth pressure of 100 - 400 mbar, introducing a reaction gas on the etched substrate for 10 - 120 min to obtain the micro-nano conical structure. Specifically, the reaction gas includes ammonia with a flow rate of 25000 - 35000 sccm and trimethylgallium with a flow rate of 30 - 150 sccm.

[0074] For example, the growth temperature can be 975 °C, 985 °C, 995 °C, 1005 °C, 1015 °C, 1025 °C, 1035 °C, 1045 °C, 1055 °C, 1065 °C, 1075 °C or 1080 °C, the growth pressure can be 100 mbar, 125 mbar, 150 mbar, 175 mbar, 200 mbar, 225 mbar, 250 mbar, 275 mbar, 300 mbar, 325 mbar, 350 mbar, 375 mbar or 400 mbar, the introduction time of the reaction gas can be 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min or 120 min, the flow rate of ammonia can be 25000 sccm, 26000 sccm, 27000 sccm, 28000 sccm, 29000 sccm, 30000 sccm, 31000 sccm, 32000 sccm, 33000 sccm, 34000 sccm or 35000 sccm, and the flow rate of trimethylgallium can be 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, 110 sccm, 120 sccm, 130 sccm, 140 sccm or 150 sccm.

[0075] Furthermore, the growth temperature in the range of 975 - 1080 °C can enable the gallium atoms generated by the decomposition of trimethylgallium to combine with the nitrogen atoms generated by the decomposition of ammonia, and epitaxial growth is carried out on the surface of the substrate with a periodic micro-mask after etching; the growth pressure of 100 - 400 mbar can balance the gas-phase transport rate and the surface adsorption capacity, and promote the directional growth of the micro-nano conical structure.

[0076] Furthermore, a large flow rate of ammonia provides sufficient nitrogen elements to maintain the nitrogen environment required for crystal growth. Traditional epitaxial growth processes mostly adopt fixed temperature and pressure parameters, resulting in random morphology and uneven density of the micro-nano conical structure. In the prior art, the flow rate of ammonia is usually lower than 20000 sccm, and insufficient supply of the nitrogen source is likely to cause crystal defects. The flow rate of trimethylgallium refers to the rate of delivering the gallium source to the reaction chamber. Limiting the flow rate range can accurately control the supply amount of gallium elements and prevent crystal defects caused by excessive deposition.

[0077] Furthermore, through the above technical solutions, the present invention realizes the highly controllable growth of gallium nitride micro-nano conical structures. The coordinated control of the growth temperature and pressure effectively inhibits the generation of crystal defects. The precise ratio of the flow rates of ammonia and trimethylgallium ensures a stable crystal growth rate, and the dynamic adjustment of the reaction time enables the cone height and the surface roughness of the substrate to reach a balance.

[0078] It should be noted that in a GaN crystal, the dangling bond density of the

[0001] plane is about 11.4, the dangling bond density of the [1-100] plane is 12, and the dangling bond density of the [10-11] plane is 16. A low dangling bond density indicates a low surface energy. According to the Gibbs-Wulff law, the linear growth rate of a crystal plane is inversely proportional to the specific surface energy of that plane. Therefore, during the three-dimensional growth of a GaN crystal, a hexagonal prism structure with

[0001] and [1-100] planes will be formed; GaN grows into a pyramid-like micron structure with six [10-11] crystal planes, and they are independent of each other with basically no lateral merging phenomenon. Therefore, the growth rates in the

[0001] and [1-100] crystal directions will be much greater than those in other crystal directions. As time goes by,

[0001] the plane gradually becomes smaller and finally forms a cone-like GaN structure (i.e., a micro-nano cone-like structure) with six uniform [10-11] crystal plane families. In summary, the present invention first determines the defect distribution through surface detection, and then performs chemical etching to form a stable micro-mask in the non-defect area. At this time, the defect area is more easily etched and exposed due to its loose structure. Physical etching bombards the defect area with high-energy particles, breaks the surface protrusions and reduces the micro-roughness. During the alternating etching process, the chemical etching step continuously replenishes the micro-mask, and the physical step directionally trims the defect morphology. The two cooperate to achieve surface flattening at the atomic level. Finally, during epitaxial growth, the protective layer inhibits the deposition in the non-defect area, prompting the material to be directionally deposited in the defect repair area to form a micro-nano cone-like structure, which can effectively enhance the light field regulation ability. Through the above technical solutions, the present invention realizes precise control of the surface roughness of the substrate, and solves the problem that it is difficult for traditional processes to balance surface quality and structure preparation. The alternating etching process effectively eliminates surface defects, and the selective inhibition of the protective layer during the epitaxial growth process promotes the directional formation of the micro-nano cone-like structure. This integrated process provides a controllable preparation method for the manufacture of high-performance optoelectronic devices. Please refer to Figure 3 , Figure 3 which is a schematic structural diagram of the substrate structure provided by the present invention. The substrate structure provided by the present invention includes: a substrate, a micro-mask, and a micro-nano cone-like structure. The surface of the substrate includes a defect area and a non-defect area; the micro-mask covers the non-defect area; the micro-nano cone-like structure is disposed on the non-defect area; wherein, the height of the surface of the micro-nano cone-like structure away from the substrate exceeds the height of the surface of the micro-mask away from the substrate. Among them, the defective area refers to the area on the substrate surface where lattice distortion or impurity aggregation exists, which can be selectively exposed by atomic layer etching and preferentially processed during physical etching; the non-defective area refers to the area with a complete surface structure, which is protected by a micro-mask to avoid etching damage. The micro-mask refers to the protective layer formed in chemical etching, and specifically, a SiF x thin film can be used to achieve this. Its function is to isolate the direct contact between the non-defective area and epitaxial growth, forming a selective growth substrate. The micro-nano conical structure refers to the three-dimensional protrusion formed by the epitaxial process, which can be specifically grown directionally in the area covered by the micro-mask through chemical vapor deposition. Its height exceeds the design of the micro-mask and can break through the limitations of traditional planar structures to form a light scattering interface. Furthermore, through the division of the defective area and the non-defective area on the substrate surface, differential processing is achieved. The roughness of the defective area decreases during physical etching, while the non-defective area maintains its original structure due to the protection of the micro-mask. During the epitaxial growth process, the presence of the micro-mask enables the material to preferentially nucleate only in the non-defective area, ultimately forming a micro-nano conical structure with a height difference. This structural difference enables the formation of an optical path modulation interface at the interface between the epitaxial layer and the substrate. The inclined sidewalls of the micro-nano conical structure can change the reflection path of incident light, and the height difference between the micro-mask and the micro-nano conical structure provides a directional channel for carrier transport, thereby synergistically improving the light extraction efficiency. The present invention also provides an LED device, which includes a substrate structure and a light-emitting structure disposed on the substrate structure; among them, the substrate structure is the above-mentioned substrate structure; alternatively, the substrate structure is prepared by the above-mentioned growth method based on the atomic layer etching substrate structure. The substrate structure includes a substrate, a micro-mask, and a micro-nano conical structure. The surface of the substrate includes a defective area and a non-defective area; the micro-mask covers the non-defective area; the micro-nano conical structure is disposed on the non-defective area; among them, the height of the surface of the micro-nano conical structure away from the substrate exceeds the height of the surface of the micro-mask away from the substrate. The light-emitting structure includes an N-type layer, a quantum well layer, and a P-type layer stacked. The N-type layer is disposed between the substrate structure and the quantum well layer, or the P-type layer is disposed between the substrate structure and the quantum well layer. Furthermore, the LED device can be a red light LED device. For the three-dimensional structure schematic diagram of the micro-nano conical structure, see Figure 4 and Figure 5As shown in the figure, by setting the micro-nano conical structure, on the one hand, by optimizing the stress distribution and carrier recombination path of the quantum well layer, reducing the non-radiative recombination centers, the spontaneous emission transition probability in the red light band is significantly increased, thereby specifically enhancing the red light emission intensity. On the other hand, by shortening the action path of the built-in electric field in the quantum well layer, reducing the accumulation of polarization charges, effectively weakening the band tilt and red shift of the emission wavelength caused by the quantum-confined Stark effect, and avoiding the decrease in emission efficiency and spectral broadening caused by the electric field effect. In addition, it can also reduce the circulating loss of light waves inside the device and at the same time reduce the energy dissipation of surface plasmon polaritons, ultimately achieving a significant increase in the light output power. Through the above technical solutions, the present invention solves the problems of carrier scattering and light loss caused by high surface roughness, and reduces the process complexity and cost of preparing the micro-nano conical structure. Through the synergistic effect of alternating etching and epitaxial growth, the active regulation of the substrate surface topography and microstructure is realized, and the light emission efficiency and performance consistency of the LED device are improved. Example 1: See Figure 1 As shown in the figure, this embodiment provides a growth method based on the structure of the atomic layer etching substrate 100, which includes: Step S1: Provide a substrate 100 made of gallium nitride; wherein, the surface of the substrate 100 includes a defect region and a non-defect region. Step S2: Under the conditions of an etching temperature of 60 °C, an etching pressure of 15 mTorr, and an etching power of 800 W, use sulfur hexafluoride gas to chemically etch the substrate 100 for 20 s to form a micro-mask 200 (denoted as SiF x with the material of SiF x micro-mask 200) in the non-defect region and expose the defect region. In this embodiment, the substrate 100 is chemically etched in an atomic layer etching device, so that it can form a SiF x micro-mask 200 in the non-defect region of the substrate 100. Step S3: Under the conditions of an etching temperature of 60 °C, an etching pressure of 15 mTorr, and an etching power of 2000 W, introduce argon gas with a flow rate of 65 sccm to physically bombard and etch the substrate 100 for 20 s, so that the roughness of the defect region after physical etching is less than the roughness of the defect region before physical etching. Step S4: Repeat steps S2 and S3 alternately 30 times until the surface roughness of the etched substrate 100 is 0.095 nm. Step S5: Place the etched substrate 100 in the MOCVD chamber. Under the conditions of a growth temperature of 1040 °C and a growth pressure of 250 mbar, introduce ammonia with a flow rate of 30000 sccm and trimethylgallium with a flow rate of 90 sccm onto the etched substrate 100 for 60 minutes to grow micro-nano conical structures 300 protruding from the surface of the substrate 100 in the non-defect region, obtaining the substrate 100 structure, as Figure 3 shown in Figure 4 Figure Furthermore, in the substrate 100 structure processed by the above method, the height of the Wiener conical structure is 18 μm, the bottom diameter of the Wiener conical structure is 13 μm, and the density of the Wiener conical structure is 6500 pieces / cm 2 . Through the above technical solution, the present invention realizes the controllable growth of the height of the gallium nitride micro-nano conical structure 300 by adjusting the flatness of the substrate 100, and further enables the surface morphology of the device to be flexibly optimized according to the optoelectronic performance requirements, enhancing the luminescence performance and reliability of the optoelectronic device. Example 2: This embodiment provides another growth method based on the atomic layer etching substrate structure. The main process and principle are the same as those of Example 1, and specifically include: Step S1: Provide a substrate made of gallium nitride; wherein, the surface of the substrate includes a defect region and a non-defect region. Step S2: Under the conditions of an etching temperature of 55 °C, an etching pressure of 10 mTorr, and an etching power of 600 W, use sulfur hexafluoride gas to chemically etch the substrate for 10 s to form a micro-mask made of SiF x in the non-defect region and expose the defect region. In this embodiment, the substrate is chemically etched in an atomic layer etching device, so that it can form a SiF x micro-mask in the non-defect region of the substrate. Step S3: Under the conditions of an etching temperature of 55 °C, an etching pressure of 10 mTorr, and an etching power of 1500 W, introduce nitrogen with a flow rate of 50 sccm to physically bombard and etch the substrate for 10 s, so that the roughness of the defect region after physical etching is less than the roughness of the defect region before physical etching. Step S4: Repeat steps S2 and S3 alternately 30 times until the surface roughness of the etched substrate is 0.097 nm. Step S5: Place the etched substrate in the MOCVD chamber. Under the conditions of a growth temperature of 975 °C and a growth pressure of 100 mbar, introduce ammonia with a flow rate of 30000 sccm and trimethylgallium with a flow rate of 90 sccm onto the etched substrate for 10 minutes to grow micro-nano conical structures protruding from the substrate surface in the non-defective area, obtaining a substrate structure. Further, in the substrate structure processed by the above method, the height of the Wiener conical structure is 15 μm, the bottom diameter of the Wiener conical structure is 10 μm, and the density of the Wiener conical structure is 5000 pieces / cm 2 . Through the above technical solution, in this embodiment, the height-controlled growth of gallium nitride micro-nano conical structures is realized under another condition by parameter adjustment, and devices with high flexibility and high quality are also obtained. Example Three: This embodiment provides another growth method based on an atomic layer etched substrate structure. Its main process and principle are the same as those in Example One, specifically including: Step S1: Provide a substrate made of gallium nitride; wherein, the surface of the substrate includes a defective area and a non-defective area. Step S2: Under the conditions of an etching temperature of 65 °C, an etching pressure of 20 mTorr, and an etching power of 1200 W, use sulfur hexafluoride gas to chemically etch the substrate for 30 s to form a micro-mask made of SiF x in the non-defective area and expose the defective area. In this embodiment, the substrate is chemically etched in an atomic layer etching equipment, so that it can form a SiF x micro-mask in the non-defective area of the substrate. Step S3: Under the conditions of an etching temperature of 65 °C, an etching pressure of 20 mTorr, and an etching power of 2500 W, introduce nitrogen with a flow rate of 80 sccm to physically bombard and etch the substrate for 30 s, so that the roughness of the defective area after physical etching is less than that of the defective area before physical etching. Step S4: Repeat steps S2 and S3 alternately 30 times until the surface roughness of the etched substrate is 0.096 nm. Step S5: Place the etched substrate in the MOCVD chamber. Under the conditions of a growth temperature of 1080 °C and a growth pressure of 400 mbar, introduce ammonia with a flow rate of 30000 sccm and trimethylgallium with a flow rate of 90 sccm onto the etched substrate for 120 minutes to grow micro-nano conical structures protruding from the substrate surface in the non-defective area, obtaining a substrate structure. Further, in the substrate structure processed by the above method, the height of the Wiener cone structure is 20 μm, the bottom diameter of the Wiener cone structure is 15 μm, and the density of the Wiener cone structure is 8,000 per cm 2 . Compared with the prior art, when the traditional method reduces the surface roughness by mechanical polishing, it is impossible to simultaneously form a micro-nano cone structure, and technologies such as electron beam lithography require complex mask preparation. Through the synergistic effect of regional etching and epitaxial growth, this solution directly constructs a three-dimensional structure by using the micro-mask 200 and the epitaxial process while reducing the roughness of the defect area, avoiding the introduction of additional lithography steps. In addition, the physical etching of the defect area and the chemical etching of the non-defect area are alternately carried out, which can achieve atomic-level surface flatness control, and has a higher degree of freedom in parameter adjustment compared with the traditional single etching process, thereby obtaining a highly flat substrate structure that can be applied to more scenarios. Example 4: This example provides an LED device. The preparation method of the LED device includes: S21: Prepare a substrate structure by using the preparation method shown in Example 1. S22: Prepare a light-emitting structure on the substrate structure to obtain an LED device. Through the above technical solution, the present invention solves the process compatibility problem of surface roughness control of gallium nitride materials and the preparation of micro-nano cone structures, and reduces the risk of impurity introduction during the device preparation process. The height difference design between the micro-nano cone structure and the micro-mask enhances the light scattering effect. At the same time, the non-defect area covered by the micro-mask provides a low-defect density transmission path for carriers, thereby significantly improving the device quality. Example 5: This example provides an LED device. The preparation method of the LED device includes: S21: Prepare a substrate structure by using the preparation method shown in Example 2. S22: Prepare a light-emitting structure on the substrate structure to obtain an LED device. Among them, the method and specific process of preparing the light-emitting structure on the substrate structure are as shown in the prior art, and will not be elaborated here. Example 6: This example provides an LED device. The preparation method of the LED device includes: S21: Prepare a substrate structure by using the preparation method shown in Example 3. S22: Prepare a light-emitting structure on the substrate structure to obtain an LED device. Comparative example: S21: Prepare a substrate by using the existing ALE, specifically including: S21: Clean the substrate to remove residual organic pollutants and particulate impurities on the substrate surface. Specifically, it includes organic cleaning and inorganic cleaning. Among them, organic cleaning uses an organic solvent as a cleaning medium to dissolve the adhesion force between the pollutant and the substrate, so that the organic pollutant falls off from the substrate surface and is dispersed in the solution; inorganic cleaning uses an inorganic cleaning solution to remove metal oxide impurities. S22: Optimize the substrate surface by dry etching to remove the contamination on the substrate surface and reduce the substrate roughness. Bombard the substrate surface with oxygen plasma. Oxygen radicals have extremely strong oxidizing properties and can react with organic pollutants and decompose them into small molecule gases. These gases are discharged from the chamber under the action of the vacuum system, thus achieving the complete removal of the contamination on the substrate surface. At the same time, the bombardment of the oxygen plasma can also micro-etch the substrate surface, removing the protruding atoms or tiny particles on the surface through physical sputtering, making the micro-topography of the substrate surface smoother, and thus reducing the surface roughness. S22: Fabricate a light-emitting structure on the substrate to obtain an LED device. Compared with the prior art, the present invention has the following advantages: First, compared with traditional dedicated polishing equipment or complex etching steps, the chemical and mechanical alternating etching technology adopted in the present invention not only further reduces the roughness of the substrate surface, but also can significantly reduce the production and processing costs, while saving processing time and space, making it suitable for large-scale production scenarios. Second, compared with current technologies such as electron beam lithography and focused ion beam etching, on the one hand, the present invention can reduce the possibility of introducing impurities, thus providing conditions for the further development of high-quality devices. On the other hand, it can also significantly reduce the generation of pollutants, not only improving the safety during the processing, but also reducing environmental pollution. Finally, compared with conventional semiconductor devices, the conical gallium nitride nanowire structure in the present invention can precisely adjust the growth process by regulating its growth parameters, thereby making it adaptable to more precise optoelectronic performance requirements, and further expanding the application scenarios and development space of the device. Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A growth method based on an atomic layer etching substrate structure, characterized in that: Including: Step S1: Provide a substrate; wherein, the surface of the substrate includes a defective area and a non-defective area; Step S2: Chemically etch the substrate with an etching gas to form a micro-mask in the non-defective area and expose the defective area; Step S3: Physically etch the substrate so that the roughness of the defective area after physical etching is less than the roughness of the defective area before physical etching; Step S4: Repeat steps S2 and S3 alternately until the surface roughness of the etched substrate reaches a preset roughness; Step S5: Perform epitaxial growth on the etched substrate to grow a micro-nano conical structure protruding from the surface of the substrate in the non-defective area, obtaining a substrate structure.

2. The growth method based on the atomic layer etching substrate structure according to claim 1, characterized in that: The etching gas is a fluorine-containing gas. The chemically etching the substrate with the etching gas to form a micro-mask in the non-defective area and expose the defective area includes: Under the conditions of an etching temperature of 55-65 °C, an etching pressure of 10-20 mTorr, and an etching power of 600-1200 W, introduce a fluorine-containing gas with a flow rate of 10-80 sccm to chemically etch the substrate for 10-30 s to form the micro-mask in the non-defective area.

3. The growth method based on the atomic layer etching substrate structure according to claim 1, characterized in that: Physically etching the substrate includes: Under the conditions of an etching temperature of 55-65 °C, an etching pressure of 10-20 mTorr, and an etching power of 1500-2500 W, introduce an inert gas with a flow rate of 50-80 sccm to physically bombard and etch the substrate for 10-30 s; Wherein, the inert gas includes nitrogen, argon or helium.

4. The growth method of a substrate structure based on atomic layer etching according to claim 1, characterized in that: Grow the micro-nano conical structure on the etched substrate by chemical vapor deposition; wherein, the physical parameters of the micro-nano conical structure are related to the growth parameters; the physical parameters include size or density, and the growth parameters include time, temperature or growth pressure; And / or, the height of the micro-nano conical structure is 15-20 μm; And / or, the bottom diameter of the micro-nano conical structure is 10-15 μm; and / or, the density of the micro-nano conical structure is 5000 - 8000 pieces / cm 2 .

5. The growth method of a substrate structure based on atomic layer etching according to claim 4, characterized in that: The growth temperature of the micro-nano conical structure is proportional to the size of the micro-nano conical structure; And / or, the growth time of the micro-nano conical structure is proportional to the size of the micro-nano conical structure; And / or, the growth pressure of the micro-nano conical structure is inversely proportional to the size of the micro-nano conical structure.

6. The growth method based on the atomic layer etching substrate structure according to claim 4 or 5, characterized in that: The growth temperature of the micro-nano conical structure is proportional to the density of the micro-nano conical structure; And / or, the growth time of the micro-nano conical structure is proportional to the density of the micro-nano conical structure; And / or, the growth pressure of the micro-nano conical structure is proportional to the density of the micro-nano conical structure.

7. The growth method based on the atomic layer etching substrate structure according to claim 1, characterized in that: The preset roughness < 0.1 nm; And / or, the number of cycles of S2-S3 is 20-50 times; And / or, the material of the micro-nano conical structure is the same as the material of the substrate. And / or, the etch gas is sulfur hexafluoride gas, and the material of the micro-mask is SiF x .

8. The growth method based on the atomic layer etching substrate structure according to claim 7, characterized in that: Epitaxially grow micro-nano conical structures on the etched substrate, including: Under the conditions of a growth temperature of 975 - 1080 °C and a growth pressure of 100 - 400 mbar, introduce the reaction gas on the etched substrate for 10 - 120 min to obtain the micro-nano conical structures; Wherein, the reaction gas includes ammonia with a flow rate of 25000 - 35000 sccm and trimethylgallium with a flow rate of 30 - 150 sccm.

9. A substrate structure, characterized in that: The substrate structure includes: A substrate, the surface of the substrate includes a defective area and a non-defective area; A micro-mask, the micro-mask covers the non-defective area; Micro-nano conical structures, the micro-nano conical structures are disposed on the non-defective area; Wherein, the height of the surface of the micro-nano conical structure away from the substrate exceeds the height of the surface of the micro-mask away from the substrate.

10. An LED device, characterized in that: The LED device includes a substrate structure and a light-emitting structure disposed on the substrate structure; Wherein, the substrate structure is the substrate structure described in claim 9; or, the substrate structure is prepared by using the growth method of the substrate structure based on atomic layer etching described in any one of claims 1 - 8.

Images