Preparation method of patterned substrate, patterned substrate and semiconductor device

Abstract

The invention discloses a preparation method of a patterned substrate, a patterned substrate and a semiconductor device. The method comprises the following steps: forming a first microstructure on the surface of the substrate; forming a second microstructure on the surface of the first microstructure, wherein the light refractive index of the second microstructure is greater than that of the first microstructure; wherein at least one of the first microstructure and the second microstructure includes a fractal structure. According to the invention, the reflected light intensity of the patterned substrate can be realized, and the light-emitting rate of the light-emitting device is improved.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor device manufacturing, and more specifically, relates to a method for preparing a patterned substrate, a patterned substrate and a semiconductor device. Background Art

[0002] In the field of light emitting diodes (LEDs), PSS (patterned sapphire substrate) means "patterned sapphire substrate". It is designed and produced on the sapphire substrate by etching (dry etching / wet etching on the C-side of sapphire) to create micron- or nano-scale patterns with specific microstructure rules, thereby controlling the output light form of the LED device (the concave-convex pattern on the sapphire substrate will produce light scattering or refraction effects to increase the light extraction rate). At the same time, the growth of GaN film on the patterned sapphire substrate will produce a lateral epitaxial effect, reducing the dislocation defects between GaN grown on the sapphire substrate, improving the epitaxial quality, and improving the internal quantum efficiency of the LED and increasing the light extraction efficiency. Compared with LEDs based on general sapphire substrates, the brightness of LEDs based on PSS has increased by more than 70%.

[0003] Prior art 1 discloses a patterned composite substrate, which is prepared by first sequentially forming a silicon dioxide heterogeneous layer and a mask layer on a sapphire substrate, patterning the mask layer to form a mask pattern, and using an etching method combining dry etching and wet etching based on the mask pattern. In the patterned composite substrate, the presence of silicon dioxide can promote the bending of dislocations inside the epitaxial layer along the side of the pattern and the closing at the top of the pattern, thereby improving the crystal quality of the GaN material, and the large refractive difference between silicon dioxide and GaN can also improve the light extraction efficiency.

[0004] The surface of the PSS of this solution can only form a light reflection interface between the silicon dioxide heterogeneous layer and the subsequently deposited GaN layer, which has a very limited effect on improving the light output efficiency of the light-emitting device. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a patterned substrate, a patterned substrate and a semiconductor device, so as to increase the intensity of reflected light and improve the light output rate of the light-emitting device.

[0006] To achieve the above object, in a first aspect, the present invention provides a method for preparing a patterned substrate, comprising:

[0007] forming a first microstructure on a surface of a substrate;

[0008] A second microstructure is formed on the surface of the first microstructure, wherein the light refractive index of the second microstructure is greater than the light refractive index of the first microstructure;

[0009] At least one of the first microstructure and the second microstructure includes a fractal structure.

[0010] Optionally, forming a first microstructure on the surface of the substrate includes:

[0011] forming a first optical medium layer on the surface of the substrate;

[0012] The first optical medium layer is etched to form the first microstructure.

[0013] Optionally, forming a second microstructure on the surface of the first microstructure includes:

[0014] forming a second optical medium layer on the surface of the first microstructure, wherein the optical refractive index of the second optical medium layer is greater than the optical refractive index of the first microstructure;

[0015] forming a granular mask layer on the surface of the second optical medium layer;

[0016] Etching the second optical medium layer using the granular mask layer;

[0017] removing the granular mask layer;

[0018] The steps of forming a granular mask layer on the surface of the second optical medium layer and removing the granular mask layer are cyclically performed at least once to form the second microstructure, wherein the second microstructure is a fractal structure.

[0019] Optionally, forming a second microstructure on the surface of the first microstructure includes:

[0020] forming a granular mask layer on the surface of the first microstructure;

[0021] Using the granular mask layer to etch the surface of the first microstructure;

[0022] removing the granular mask layer;

[0023] cyclically performing the steps of forming a granular mask layer on the surface of the first microstructure to removing the granular mask layer at least once, so as to form a first fractal structure on the surface of the first microstructure;

[0024] A second optical medium layer is deposited on the surface of the first fractal structure to form the second microstructure, wherein the optical refractive index of the second optical medium layer is greater than the optical refractive index of the first microstructure.

[0025] Optionally, after forming the second optical medium layer on the surface of the second microstructure, the method further includes:

[0026] forming a granular mask layer on the surface of the second optical medium layer;

[0027] Etching the second optical medium layer using the granular mask layer;

[0028] removing the granular mask layer;

[0029] The steps of forming a granular mask layer on the surface of the second optical medium layer and removing the granular mask layer are cyclically performed at least once until a second fractal structure is formed on the surface of the second optical medium layer.

[0030] Optionally, during the cycle process, as the number of cycles increases, the thickness of the granular mask layer decreases gradually.

[0031] Optionally, the method of forming the granular mask layer includes:

[0032] Forming a metal film;

[0033] The metal film is transformed into nano-metal particles through a rapid thermal annealing process to form the granular mask layer.

[0034] Optionally, the material of the metal film includes nickel.

[0035] Optionally, the second optical medium layer is formed by an atomic layer deposition process;

[0036] The second optical medium layer is etched by using an atomic layer etching process.

[0037] Optionally, the material of the first optical medium layer includes silicon oxide;

[0038] The material of the second optical medium layer includes aluminum oxide.

[0039] Optionally, the thickness of the second optical medium layer is 10%-50% of the thickness of the first optical medium layer.

[0040] Optionally, before forming the first optical medium layer on the surface of the substrate, the method further comprises:

[0041] forming a third microstructure on the surface of the substrate;

[0042] The optical refractive index of the third microstructure is smaller than the optical refractive index of the first optical medium layer; the distribution positions of the first microstructure and the third microstructure overlap, and each of the first microstructures wraps one of the third microstructures.

[0043] Optionally, the material of the third microstructure is a high molecular polymer.

[0044] Optionally, the third microstructure is formed on the surface of the substrate by drop coating the high molecular polymer.

[0045] Optionally, it also includes:

[0046] A third optical medium layer covering the second microstructure is formed on the patterned substrate, and the optical refractive index of the third optical medium layer is greater than the optical refractive index of the second microstructure.

[0047] In a second aspect, the present invention provides a method for manufacturing a semiconductor device, comprising:

[0048] Obtaining a patterned substrate by adopting the method for preparing a patterned substrate as described in any one of the first aspects;

[0049] A light emitting structure is formed on a surface of the patterned substrate facing away from the first microstructure.

[0050] In a third aspect, the present invention proposes a patterned substrate, comprising: a substrate, a first microstructure formed on the surface of the substrate, a second microstructure formed on the surface of the first microstructure, and a light refractive index of the second microstructure is greater than the light refractive index of the first microstructure.

[0051] Optionally, the second microstructure includes a first fractal structure located on a surface of the first microstructure and a second optical medium layer located on a surface of the first fractal structure, and the first fractal structure and the first microstructure are made of the same material.

[0052] Optionally, the second microstructure includes a first fractal structure located on the surface of the first microstructure and a second fractal structure located on the surface of the first fractal structure, the first fractal structure and the first microstructure are made of the same material, and the second fractal structure and the first fractal structure are made of a different material.

[0053] Optionally, the surface of the substrate has a third microstructure, the first microstructure wraps the third microstructure, and the light refractive index of the third microstructure is smaller than the light refractive index of the first microstructure.

[0054] Optionally, a third optical medium layer is further included, wherein the third optical medium layer covers the second microstructure, and the light refractive index of the third optical medium layer is greater than the light refractive index of the second microstructure.

[0055] In a fourth aspect, the present invention provides a semiconductor device, comprising:

[0056] A patterned substrate as described in any one of the third aspects;

[0057] A light emitting structure is formed on a side of the patterned substrate away from the first microstructure.

[0058] The beneficial effects of the present invention are:

[0059] The method for preparing a patterned substrate of the present invention first forms a first microstructure with a relatively small refractive index on a substrate, and then forms a second microstructure with a relatively large refractive index on the surface of the first microstructure. The second microstructure with a smaller size can increase the incident angle range of the total reflected light. At the same time, since the light refractive index of the second microstructure is greater than that of the first microstructure, a plurality of light reflection interfaces can be formed between the second microstructure and the first microstructure, thereby increasing the intensity of the reflected light, increasing the proportion of the reflected light, enhancing the total reflection effect, and effectively increasing the light emission effect of the light-emitting device. Furthermore, at least one of the first microstructure and the second microstructure includes a fractal structure, which can increase the number of light scattering times and change the emission angle of the total reflected light, thereby further improving the light extraction efficiency and increasing the reflection effect.

[0060] The system of the present invention has other characteristics and advantages, which will be apparent from the drawings incorporated herein and the following detailed description, or will be described in detail in the drawings incorporated herein and the following detailed description, which together serve to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which like reference numerals generally represent like components.

[0062] Figure 1 The device structure diagram corresponding to each step in a method for preparing a patterned substrate according to Example 1 of the present invention is shown.

[0063] Figure 2a and Figure 2b A schematic diagram showing the formation of fractal structures at different levels during the process of forming the second microstructure in Example 1 of the present invention is shown.

[0064] Figure 3 The device structure diagram corresponding to each step in a method for preparing a patterned substrate according to Example 2 of the present invention is shown.

[0065] Figure 4 The device structure diagram corresponding to each step in a method for preparing a patterned substrate according to Example 3 of the present invention is shown.

[0066] Figure 5 The device structure diagram corresponding to each step in a method for preparing a patterned substrate according to Example 4 of the present invention is shown.

[0067] Figure 6 A device structure diagram obtained by a method for manufacturing a semiconductor device according to embodiment 5 of the present invention is shown. DETAILED DESCRIPTION

[0068] The method to improve the light output efficiency of GaN-based LED devices is based on total internal reflection in PSS, also known as total internal reflection (TIR). That is, when light enters a medium with a higher refractive index from a medium with a lower refractive index, if the incident angle is greater than a certain critical angle θ c When the refraction angle is 90°, the refracted light will disappear and all incident light will be reflected without entering the medium with a low refractive index. c The law of refraction can be used to give:

[0069] n 1 sinθ i =n 2 sinθ t

[0070] Since the refraction angle θ t is 90°, so sinθ t =1, solving the above equation yields the critical angle θ c :

[0071] θ c =θ i =arc sin(n 2 / n 1 )

[0072] Among them, n 2 is the refractive index of the less dense medium, and n 1 It is the refractive index of the higher density medium. Therefore, when the refractive index of the denser medium is greater than that of the less dense medium, the critical angle is smaller, which means that total reflection is more likely to occur. The refractive index of common materials: gallium nitride has a refractive index of about 2.70, silicon oxide has a refractive index of about 1.46, aluminum oxide has a refractive index of 1.76, silicon has a refractive index of 3.42, and so on.

[0073] The current PSS light reflection structure often has only one reflection interface, and there is still much room for improvement in light reflection capability.

[0074] The present invention provides a method for preparing a patterned substrate and a light-emitting device, which can greatly increase the light reflection capability and thus improve the light extraction efficiency of the light-emitting device.

[0075] The present invention will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0076] Example 1

[0077] like Figure 1 As shown, this embodiment provides a method for preparing a patterned substrate, comprising:

[0078] S1: forming a first microstructure 5 on the surface of the substrate 1;

[0079] This step specifically includes:

[0080] S101: providing a substrate 1. The material of the substrate 1 may be sapphire, silicon, silicon carbide or the like. The substrate 1 in this embodiment is a sapphire substrate.

[0081] S102: forming a first optical medium layer 2 on the surface of the substrate 1;

[0082] The material of the first optical medium layer 2 is a light-sparse medium material with a relatively low refractive index, preferably a refractive index lower than that of the material to be epitaxially grown, for example, GaN. In this embodiment, the material of the first optical medium layer 2 is silicon oxide.

[0083] A layer of silicon oxide can be grown on the sapphire substrate by low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition, high density plasma chemical vapor deposition, electron beam evaporation, magnetron sputtering, etc. The thickness of the first optical medium layer 2 can be selected to be 1 to 5 microns, preferably 1 to 2 microns.

[0084] S103: forming a photoresist layer 3 on the first optical medium layer 2;

[0085] S104 : patterning the photoresist layer 3 to form a photoresist mask 4 .

[0086] Specifically, a photoresist is spin-coated on the wafer with a thickness of 2 to 10 microns, preferably twice the thickness of the silicon oxide in the first step, and the rotation speed is determined according to the thickness value; then, photolithography exposure and development are performed, and the mask template is designed and processed in advance as needed. The exposure time is preferably 6 seconds, with a range of 3 to 20 seconds, the development time is preferably 75 seconds, with a range of 45 to 120 seconds, and the fixing time is preferably 120 seconds, with a range of 60 to 300 seconds, so as to pattern the photoresist and form a mask.

[0087] S105: etching the first optical medium layer 2 to form a first microstructure 5;

[0088] Specifically, based on the photoresist mask, the first optical medium layer 2 is etched using a fluorocarbon gas, wherein the fluorocarbon gas may be one or more of octafluorocyclobutane, hexafluorobutadiene, carbon tetrafluoride, trifluoromethane, difluoromethane, fluoromethane and the like.

[0089] Plasma is preferably used to etch silicon oxide. The etching process parameters include: chamber pressure range 0.5~50mTorr, upper electrode power range 600~3000W, lower electrode power range 50~3000W, chuck temperature range -15~50℃, flow range 10~1000sccm, back helium pressure range 1~20Torr, and process time varies with the silicon oxide thickness in the first step.

[0090] After etching, a periodically distributed first microstructure 5 is formed on the sapphire substrate. In this embodiment, the first microstructure 5 is conical in shape and has a size of micrometer level. In other embodiments, the first microstructure 5 may also be hemispherical, pyramidal, etc.

[0091] S2: forming a second microstructure on the surface of the first microstructure 5, wherein the light refractive index of the second microstructure is greater than the light refractive index of the first microstructure; wherein at least one of the first microstructure 5 and the second microstructure comprises a fractal structure.

[0092] The second microstructure in this step includes a fractal structure 9, and the method of forming the second microstructure specifically includes:

[0093] S201: forming a second optical medium layer 6 on the surface of the first microstructure 5, wherein the optical refractive index of the second optical medium layer 6 is greater than the optical refractive index of the first optical medium layer 2;

[0094] In this embodiment, the material of the second optical medium layer 6 is aluminum oxide, and the optical refractive index of aluminum oxide (1.76) is greater than the optical refractive index of silicon oxide (1.46), so it can form a reflective interface with silicon oxide. Preferably, the second optical medium layer 6 is formed by an atomic layer deposition process, and the thickness of the second optical medium layer 6 is 10%-50% of the thickness of the first optical medium layer 2.

[0095] Specifically, trimethylaluminum, oxygen plasma and argon can be used to perform atomic layer deposition of aluminum oxide. Before performing atomic layer deposition, the surface of the substrate 1 is cleaned with hydrofluoric acid, and the chamber pressure background vacuum is evacuated to 5×10 -4Pa. Then, 20 sccm of argon is used as a carrier gas to introduce trimethylaluminum for 4 seconds. After argon is purged for 5 to 20 seconds, 15 sccm of oxygen is introduced and the pressure is controlled to 5 mTorr under the action of the lower RF power of 100 W and the upper RF power of 500 W, so that it reacts with the trimethylaluminum adsorbed on the surface of the first microstructure 5 for 10 seconds. The argon is purged for 5 to 20 seconds to complete a cycle. The number of cycles is set according to the specific thickness of the second optical medium layer 6, such as 200-300 cycles, to form the second optical medium layer 6 on the surface of the first microstructure 5.

[0096] It should be noted that, in the process of depositing aluminum oxide to form the second optical medium layer 6, the aluminum oxide will cover the surface of the substrate 1 exposed between the first microstructures 5. However, since the material of the substrate 1 is sapphire, its main component is also aluminum oxide as the material of the second optical medium layer 6. Therefore, after the second optical medium layer 6 is formed, there is no need to remove the aluminum oxide deposited on the surface of the substrate 1 separately.

[0097] S202: forming a granular mask layer 8 on the surface of the second optical medium layer 6;

[0098] The method of forming the granular mask layer 8 in this step includes:

[0099] A metal film 7 is formed on the surface of the second optical medium layer 6. The material of the metal film 7 is preferably nickel. A layer of nickel metal film 7 can be formed on the surface of the second optical medium layer 6 by magnetron sputtering. The thickness of the metal film 7 formed for the first time is in the range of 5 to 15 nanometers, preferably 10 nanometers.

[0100] Then, the substrate is subjected to rapid thermal annealing, and the nano-thick nickel metal film 7 is melted and ruptured to form clusters under the action of surface tension to form nano-metal particles, thereby forming a granular mask layer 8 with a nano-scale pattern. The rapid thermal annealing temperature ranges from 700 to 1000 degrees Celsius, preferably 850 degrees Celsius, and the first process time range of the rapid thermal annealing process is: 1 to 5 minutes, preferably 3 minutes.

[0101] S203: etching the second optical medium layer 6 using the granular mask layer 8;

[0102] Specifically, in this step, the second optical medium layer 6 (ie, aluminum oxide) is etched using an atomic layer etching process. The atomic layer etching is performed in cycles, and each cycle includes:

[0103] Metal hydride formation stage: A first process gas with a set flow rate is introduced into the process chamber, and ignition is performed with a set RF power to ionize the first process gas, and the first set temperature is maintained, and the first process gas reacts with the exposed portion of the second optical medium layer 6 to form a metal hydride; wherein the first process gas includes H 2, set the flow rate to 50-500sccm; set the RF power to 100-1000W; the first set temperature to below 100°C. For example, 200sccm of hydrogen is introduced into the process chamber, and the RF power is 200W for ignition, and the temperature is controlled to be below 100 degrees Celsius. After the hydrogen is ionized, hydrogen ions are generated to react with the aluminum oxide exposed by the nickel metal mask layer 8 to form aluminum hydride.

[0104] Heating to sublimate hydride: stop introducing the first process gas into the process chamber, and heat to a second set temperature to sublime the refined metal hydride, for example, heating to 175 degrees Celsius to sublime aluminum hydride.

[0105] Cooling stage: cooling the remaining second optical medium layer 6 to a first set temperature; preferably cooling to below 100 degrees Celsius.

[0106] The above-mentioned metal hydride forming stage - heating to sublimate the hydride stage - cooling stage is repeated until the second optical medium layer 6 is etched to a set depth, thereby completing the etching of the first-level fractal structure 901 in the second microstructure.

[0107] In other embodiments, other process gases may also be used, such as etchant gases containing halogens as well as oxygen, nitrogen, etc. in the first stage of the cycle.

[0108] S204: removing the granular mask layer;

[0109] The metal mask layer 8 is removed by wet etching. The residual metal nickel mask can be removed by heating to 45 degrees Celsius in a mixed solution of iodine: potassium iodide: water = 1:4:20, or by using a nitric acid solution.

[0110] S205: cyclically executing the steps of forming a granular mask layer on the surface of the second optical medium layer 6 to removing the granular mask layer at least once to form a second microstructure.

[0111] Specifically, the above steps S202-S205 are cycled to complete the hierarchical etching of the fractal structure 9 until the second microstructure is formed on the surface of the first optical medium layer 2. During the cycle, according to the refinement of the fractal hierarchy, as the number of cycles increases, the thickness of the metal film 7 decreases gradually. At the same time, as the number of cycles increases, the process time of the rapid thermal annealing process decreases gradually. Since the minimum size of the fractal structure that can be formed is limited by the size of the nanoparticles in the granular mask layer, the number of cycles in this embodiment is preferably 2-3 times. Taking 2 cycles as an example, if Figure 2a As shown, after the first cycle is completed, a first layer of fractal structure 901 is formed on the first microstructure surface, as shown in FIG. Figure 2bAs shown, after the second cycle is completed, a second layer of fractal structure 902 can be formed on the first layer of fractal structure 901, and the fractal structure 9 of the second microstructure finally formed includes the above two levels of fractal structures.

[0112] S3: forming a third optical medium layer 10 covering the second microstructure on the patterned substrate, wherein the optical refractive index of the third optical medium layer 10 is greater than the optical refractive index of the second microstructure.

[0113] Specifically, a third optical medium layer 10 is formed on the substrate 1 , the third optical medium layer 10 covers the second microstructures and fills the gaps between the first microstructures 5 , and the optical refractive index of the third optical medium layer 10 is greater than the optical refractive index of the second optical medium layer 6 .

[0114] In this embodiment, the material of the third optical medium layer 10 is gallium nitride. The light refractive index of gallium nitride (2.70) is greater than the light refractive index of aluminum oxide (1.76), so a light reflection interface is formed between gallium nitride and aluminum oxide.

[0115] The method for forming the third optical medium layer 10 in this step is: growing a layer of gallium nitride on the substrate 1 through an epitaxial process, specifically comprising: introducing trimethyl indium, trimethyl gallium and ammonia into a reaction chamber, raising the temperature to 700°C, controlling the growth rate at 0.05μm / h, and depositing a 5nm thick InGaN nucleation layer on the substrate 1; then, continuing to maintain the introduction of trimethyl indium, trimethyl gallium and ammonia, raising the temperature in the chamber to 800°C, and increasing the growth rate to 0.2μm / h to form an InGaN insertion layer; then, stopping the introduction of trimethyl indium, continuing to introduce trimethyl gallium and ammonia into the reaction chamber, raising the temperature to 1100°C, and continuing to deposit a GaN epitaxial layer thereon.

[0116] The method of this embodiment forms a nanoscale fractal structure on the surface of the micron-scale first microstructure 5 by etching the second optical medium layer 6, thereby realizing a micron-scale and nanoscale graphic combination structure. The multi-level fractal structure constituting the second microstructure causes the light emitted by the GaN material to be scattered multiple times through the interface between GaN and the sapphire substrate, thereby changing the exit angle of the total reflected light, thereby improving the light extraction efficiency and further increasing the reflection effect. Moreover, the patterned substrate prepared by this method can form two reflection interfaces, including a reflection interface formed between the first microstructure 5 and the second microstructure (i.e., silicon oxide and aluminum oxide), and another reflection interface formed between the second microstructure and the third optical medium layer 10 (i.e., aluminum oxide and gallium nitride). The multiple reflection interfaces increase the proportion of reflected light, further enhance the effect of total reflection, and improve the light extraction efficiency of the light-emitting device.

[0117] Example 2

[0118] The difference between this embodiment and embodiment 1 is that the method of forming the second microstructure in this embodiment is different from that in embodiment 1. Specifically, the fractal structure formed in step S2 in this embodiment is not formed in the second optical medium layer 6, but is formed by etching the surface of the first microstructure 5, and then the second optical medium layer 6 is deposited on the surface of the fractal structure to form the second microstructure.

[0119] like Figure 3 As shown, the method for preparing the patterned substrate of this embodiment includes:

[0120] S1: forming a first microstructure on the surface of substrate 1;

[0121] First, according to steps S101 - S105 in Embodiment 1, a first microstructure 5 made of silicon oxide is formed on a substrate 1 .

[0122] S2: forming a second microstructure on the surface of the first microstructure 5, wherein the light refractive index of the second microstructure is greater than the light refractive index of the first microstructure.

[0123] This step includes: S301: forming a granular mask layer 8 on the surface of the first microstructure 5;

[0124] Specifically referring to the method of step S202 in embodiment 1, a nickel metal film 7 is formed on the surface of the first microstructure 5. Then, the metal film 7 is transformed into nano-metal particles by a rapid thermal annealing process to form a granular mask layer 8.

[0125] S302: etching the surface of the first microstructure 5 using the granular mask layer 8;

[0126] In this step, the surface of the first microstructure 5 is etched by an atomic layer etching process using a second process gas; wherein the second process gas includes C 4 F 8 and Ar.

[0127] The method of etching the surface of the first microstructure 5 by an atomic layer etching process includes:

[0128] Under the set chamber pressure, Ar is kept flowing; after the lower electrode power is turned on, the following three steps are cyclically performed until the first fractal structure 11 is formed by etching on the surface of the first microstructure 5:

[0129] (1) A first set time C is introduced into the process chamber. 4 F 8 , etching the exposed first optical medium layer 2;

[0130] (2) turning off the power of the lower electrode and continuing for a second set time;

[0131] (3) Re-enable the power of the lower electrode and continue for the third set time period.

[0132] Preferably, the chamber pressure is set to 1-50 mTorr, the first set time is 1-2 s, the second set time is 5-15 s, and the third set time is 2-40 s.

[0133] The difference between this step and Example 1 is that the material of the atomic layer etching is changed from aluminum oxide to silicon oxide, and the process conditions are changed accordingly to a chamber pressure of 1 to 50 mTorr, preferably 10 mTorr, Ar is introduced from the beginning to the end, and C 4 F 8 The preferred time for introduction is 1.5 s. 4 F 8 After the C is applied, the power to the lower electrode is turned off, and after 10 seconds, the power to the lower electrode is turned on again for 30 seconds, and then the C is applied again. 4 F 8 , and repeat the process to complete the etching of one level of fractals in the first fractal structure 11.

[0134] S303: removing the granular mask layer 8;

[0135] Referring to step S204 in embodiment 1: removing the granular mask layer 8 by wet etching;

[0136] S304: cyclically executing the steps of forming a granular mask layer 8 on the surface of the first microstructure 5 to removing the granular mask layer 8 at least once, so as to form a first fractal structure 11 on the surface of the first microstructure 5;

[0137] Specifically referring to the method of Example 1, the above steps S301-S303 are executed cyclically, preferably 2-3 times, to complete the etching of multiple levels of the first fractal structure 11 until the first fractal structure 11 is formed on the surface of the first microstructure 5. The structural details of the first fractal structure 11 refer to FIG.

[0138] S305 : depositing a second optical medium layer 6 on the surface of the first fractal structure 11 to form a second microstructure, wherein the optical refractive index of the second optical medium layer 6 is greater than the optical refractive index of the first microstructure 5 .

[0139] Specifically, referring to the method of step S201 in Example 1, a layer of aluminum oxide with a large refractive index is deposited on the surface of the first fractal structure 11 through a deposition process to form a second optical medium layer 6, thereby forming a second microstructure. That is, the second microstructure in this embodiment is composed of a first fractal structure 11 of silicon oxide material and a second optical medium layer 6 on its surface.

[0140] S3: forming a third optical medium layer 10 covering the second microstructure on the patterned substrate, wherein the optical refractive index of the third optical medium layer 10 is greater than the optical refractive index of the second microstructure.

[0141] The method of step S3 of embodiment 1 is adopted to form a third optical medium layer 10 covering the second microstructure by epitaxially growing gallium nitride on the substrate 1 .

[0142] The method of this embodiment forms a nanoscale first fractal structure 11 on the surface of the micron-scale first microstructure 5 by etching the surface of the first microstructure 5, and deposits a second optical medium layer 6 on the surface of the first fractal structure 11, thereby realizing another micron-scale and nanoscale graphic combination structure. The second microstructure in this embodiment causes the light emitted by the GaN material to be scattered multiple times through the interface between GaN and the sapphire substrate, thereby changing the exit angle of the total reflected light, thereby improving the light extraction efficiency and further increasing the reflection effect. Moreover, the reflective structure prepared by this method also has two reflective interfaces of silicon oxide-aluminum oxide and aluminum oxide-gallium nitride. The micron-scale and nanoscale graphic combination structure can further increase the total reflection effect and improve the light extraction efficiency of the light-emitting device.

[0143] Example 3

[0144] The preparation method of the patterned substrate of this embodiment is combined with Example 1 on the basis of Example 2, and a first fractal structure 11 made of silicon oxide is formed by etching the surface of the first microstructure 5, and after depositing the second optical medium layer 6, a second fractal structure 12 made of aluminum oxide is formed by etching the second optical medium layer 6, thereby further increasing the reflection effect.

[0145] like Figure 4 As shown, the method for preparing a patterned substrate in this embodiment first performs step S1 of embodiment 1 to form a first microstructure 5 made of silicon oxide on a sapphire substrate.

[0146] Then, the method of steps S301 to S305 in Example 2 is used to etch the surface of the first microstructure 5 to form a first fractal structure 11 composed of silicon oxide, and the method of step S201 in Example 1 is used to deposit aluminum oxide on the first fractal structure to form a second optical medium layer 6.

[0147] Afterwards, the method for etching aluminum oxide in steps S202 to S205 in embodiment 1 is used to etch the second optical medium layer 6 , and the second fractal structure 12 is formed on the first fractal structure 11 .

[0148] Finally, the step S3 of the first embodiment is adopted to form the third optical layer 10 by epitaxially growing gallium nitride on the substrate 1 .

[0149] The method of this embodiment combines Embodiment 1 and Embodiment 2, and can sequentially form a first fractal structure 11 of silicon oxide and a second fractal structure 12 of aluminum oxide on the surface of the first microstructure 5. The double-layer fractal structure of the first fractal structure 11 and the second fractal structure 12 together constitutes the second microstructure, thereby further increasing the reflection effect and improving the light output rate of the light-emitting device.

[0150] Example 4

[0151] The difference between this embodiment and the above-mentioned embodiments 1-3 is that before forming the first microstructure on the surface of the substrate, the present embodiment further comprises:

[0152] S0: forming a third microstructure 13 on the surface of the substrate 1; the optical refractive index of the third microstructure 13 is less than the optical refractive index of the first optical medium layer 2; the distribution positions of the first microstructure 5 and the third microstructure 13 overlap, and each first microstructure 5 wraps a third microstructure 13.

[0153] Specifically, a periodically distributed third microstructure 12 is formed on the surface of the substrate 1, and the light refractive index of the third microstructure 13 is smaller than the light refractive index of the first microstructure 5;

[0154] The distribution positions of the first microstructures 5 and the third microstructures 13 overlap, and each first microstructure 5 wraps a third microstructure 13 .

[0155] Preferably, the material of the third microstructure 13 is a polymer. The polymer may include at least one of polyacrylic acid, polyvinyl chloride, polymethacrylic acid, polymethyl methacrylate, and polyethylene glycol. The third microstructure 13 arranged periodically is formed on the surface of the substrate 1 by drop coating the polymer.

[0156] The subsequent preparation steps may be the same as any of the above embodiments.

[0157] For example, the method of this embodiment is illustrated by taking Example 1 as a basis.

[0158] like Figure 5 As shown, the method of this embodiment includes:

[0159] Execute step S101: provide a substrate 1;

[0160] Execute the above step S0: form polymer beads on the surface of the substrate 1 by drop coating as the second microstructure 13, and the positions of the polymer beads and the positions of the subsequently formed conical first microstructure 5 overlap in the plane of the substrate 1. The material of the polymer beads is a polymer material with a lower refractive index, such as polyacrylic acid (refractive index 1.34), polyvinyl chloride (refractive index 1.39), polymethacrylic acid (refractive index 1.40), polymethyl methacrylate (refractive index 1.42), polyethylene glycol (refractive index 1.46), etc.

[0161] Then, S102 - S105 are performed: forming a first optical medium layer 2 on the substrate 1 , wherein the first optical medium layer 2 covers the second microstructure 13 ;

[0162] The first optical medium layer 2 is etched to form a first microstructure 5 on the surface of the substrate 1, wherein the first microstructure 5 wraps the third microstructure 13;

[0163] Then, steps S201 to S205 are performed: forming a second optical medium layer 6 on the first microstructure 5;

[0164] Then, the second optical medium layer 6 is etched to form a second microstructure;

[0165] Finally, step S3 is performed to epitaxially grow gallium nitride on the substrate 1 to form a third optical medium layer 10 .

[0166] Step S0 in this embodiment can be combined with any of the above embodiments, and an additional reflective interface can be added between the silicon oxide and the polymer inside the first microstructure 5, so as to construct three reflective interfaces in the light reflective structure, thereby further improving the light extraction efficiency of the light-emitting device.

[0167] Example 5

[0168] like Figure 6 As shown, this embodiment provides a method for manufacturing a semiconductor device, comprising:

[0169] Obtaining a patterned substrate by using the method for preparing a patterned substrate described in any one of Examples 1-4;

[0170] A light emitting structure 14 is formed on a surface of the patterned substrate facing away from the first microstructure.

[0171] The method for preparing a patterned substrate in Example 4 is used as an example to illustrate:

[0172] First, a patterned substrate is obtained by using the method for preparing a patterned substrate of Example 4, and then a light-emitting structure is formed on the back of the patterned substrate to obtain a Figure 6 The semiconductor device structure shown is an LED light-emitting panel.

[0173] The semiconductor device obtained by the method of this embodiment can have at least three reflection interfaces, which increases the proportion of reflected light and makes the device more efficient in extracting light. In addition, the light reflection structure can also have at least one layer of fractal structure, so that the light emitted by the GaN material is scattered multiple times through the interface between GaN and the sapphire substrate, changing the exit angle of the total reflected light, thereby improving the light extraction efficiency and enhancing the light extraction rate of the light-emitting device.

[0174] Example 6

[0175] The present embodiment provides a patterned substrate, comprising: a substrate 1, a first microstructure 5 is formed on the surface of the substrate 1, a second microstructure is formed on the surface of the first microstructure 5, the light refractive index of the second microstructure is greater than the light refractive index of the first microstructure 5, wherein at least one of the first microstructure 5 and the second microstructure includes a fractal structure.

[0176] The patterned substrate in this embodiment can be prepared by using any of the preparation methods of the patterned substrate in Embodiments 1-4.

[0177] When the patterned substrate is prepared by the method of Example 1, refer to Figure 1 The second microstructure is a fractal structure 9 , the material of the fractal structure 9 is different from that of the first microstructure, and the light refractive index of the fractal structure is greater than the light refractive index of the first microstructure 5 .

[0178] When the patterned substrate is prepared using the method of Example 2, referring to Figure 2, the second microstructure may also include a first fractal structure 11 located on the surface of the first microstructure 5 and a second optical medium layer 6 located on the surface of the first fractal structure 11. The first fractal structure 11 is made of the same material as the first microstructure 5, and the optical refractive index of the second optical medium layer 6 is greater than the optical refractive index of the first microstructure 5.

[0179] When the patterned substrate is prepared by the method of Example 3, refer to Figure 3 The second microstructure may also include a first fractal structure 11 located on the surface of the first microstructure 5 and a second fractal structure 12 located on the surface of the first fractal structure 11. The first fractal structure 11 is made of the same material as the first microstructure 5, and the second fractal structure 12 is made of a different material from the first fractal structure 11. The light refractive index of the second fractal structure 12 is greater than the light refractive index of the first fractal structure 11.

[0180] When the patterned substrate is prepared by the method of Example 4, refer to Figure 4 On the basis of any of the above structures, the surface of the substrate 1 further has a third microstructure 13 , the first microstructure 5 wraps the third microstructure 13 , and the light refractive index of the third microstructure 13 is less than the light refractive index of the first microstructure 5 .

[0181] In this embodiment, a third optical medium layer 10 may be further included, and the third optical medium layer 10 covers the second microstructure.

[0182] Example 7

[0183] like Figure 6 As shown, this embodiment provides a semiconductor device, including:

[0184] As in any one of the patterned substrates and light-emitting structures in Examples 1-6, the light-emitting structure 14 is formed on a side of the patterned substrate away from the first microstructure 5 .

[0185] The semiconductor device of this embodiment is a GaN-based LED device. Since it has the above-mentioned patterned substrate, the LED device has a higher light extraction efficiency.

[0186] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing a patterned substrate, characterized in that: include: forming a first microstructure on a surface of a substrate; A second microstructure is formed on the surface of the first microstructure, wherein the light refractive index of the second microstructure is greater than the light refractive index of the first microstructure; At least one of the first microstructure and the second microstructure includes a fractal structure.

2. The method for preparing a patterned substrate according to claim 1, characterized in that: The forming of the first microstructure on the surface of the substrate comprises: forming a first optical medium layer on the surface of the substrate; The first optical medium layer is etched to form the first microstructure.

3. The method for preparing a patterned substrate according to claim 2, characterized in that: The forming of the second microstructure on the surface of the first microstructure comprises: forming a second optical medium layer on the surface of the first microstructure, wherein the optical refractive index of the second optical medium layer is greater than the optical refractive index of the first microstructure; forming a granular mask layer on the surface of the second optical medium layer; Etching the second optical medium layer using the granular mask layer; removing the granular mask layer; The steps of forming a granular mask layer on the surface of the second optical medium layer and removing the granular mask layer are cyclically performed at least once to form the second microstructure, wherein the second microstructure is a fractal structure.

4. The method for preparing a patterned substrate according to claim 2, characterized in that: The forming of the second microstructure on the surface of the first microstructure comprises: forming a granular mask layer on the surface of the first microstructure; Using the granular mask layer to etch the surface of the first microstructure; removing the granular mask layer; cyclically performing the steps of forming a granular mask layer on the surface of the first microstructure to removing the granular mask layer at least once, so as to form a first fractal structure on the surface of the first microstructure; A second optical medium layer is deposited on the surface of the first fractal structure to form the second microstructure, wherein the optical refractive index of the second optical medium layer is greater than the optical refractive index of the first microstructure.

5. The method for preparing a patterned substrate according to claim 4, characterized in that: After forming the second optical medium layer on the surface of the second microstructure, the method further includes: forming a granular mask layer on the surface of the second optical medium layer; Etching the second optical medium layer using the granular mask layer; removing the granular mask layer; The steps of forming a granular mask layer on the surface of the second optical medium layer and removing the granular mask layer are cyclically performed at least once until a second fractal structure is formed on the surface of the second optical medium layer.

6. The method for preparing a patterned substrate according to any one of claims 3 to 5, characterized in that: During the cycle process, as the number of cycles increases, the thickness of the granular mask layer decreases gradually.

7. The method for preparing a patterned substrate according to any one of claims 3 to 5, characterized in that: The method of forming the granular mask layer comprises: Forming a metal film; The metal film is transformed into nano-metal particles through a rapid thermal annealing process to form the granular mask layer.

8. The method for preparing a patterned substrate according to claim 7, characterized in that: The material of the metal film includes nickel.

9. The method for preparing a patterned substrate according to claim 3 or 4, characterized in that: forming the second optical medium layer by using an atomic layer deposition process; The second optical medium layer is etched by using an atomic layer etching process.

10. The method for preparing a patterned substrate according to claim 3 or 4, characterized in that: The material of the first optical medium layer includes silicon oxide; The material of the second optical medium layer includes aluminum oxide.

11. The method for preparing a patterned substrate according to claim 3 or 4, characterized in that: The thickness of the second optical medium layer is 10%-50% of the thickness of the first optical medium layer.

12. The method for preparing a patterned substrate according to claim 2, characterized in that: Before forming the first optical medium layer on the surface of the substrate, the method further comprises: forming a third microstructure on the surface of the substrate; The optical refractive index of the third microstructure is smaller than the optical refractive index of the first optical medium layer; the distribution positions of the first microstructure and the third microstructure overlap, and each of the first microstructures wraps one of the third microstructures.

13. The method for preparing a patterned substrate according to claim 12, characterized in that: The material of the third microstructure is a high molecular polymer.

14. The method for preparing a patterned substrate according to claim 13, characterized in that: The third microstructure is formed on the surface of the substrate by drop coating the high molecular polymer.

15. The method for preparing a patterned substrate according to any one of claims 1 to 5 or 12, characterized in that: Also includes: A third optical medium layer covering the second microstructure is formed on the patterned substrate, and the optical refractive index of the third optical medium layer is greater than the optical refractive index of the second microstructure.

16. A method for manufacturing a semiconductor device, characterized in that: include: Obtaining a patterned substrate by using the method for preparing a patterned substrate as described in any one of claims 1 to 15; A light emitting structure is formed on a surface of the patterned substrate facing away from the first microstructure.

17. A patterned substrate, characterized in that: include: A substrate, a first microstructure is formed on the surface of the substrate, a second microstructure is formed on the surface of the first microstructure, and the light refractive index of the second microstructure is greater than the light refractive index of the first microstructure; wherein At least one of the first microstructure and the second microstructure includes a fractal structure.

18. The patterned substrate according to claim 17, characterized in that: The second microstructure includes a first fractal structure located on the surface of the first microstructure and a second optical medium layer located on the surface of the first fractal structure. The first fractal structure and the first microstructure are made of the same material.

19. The patterned substrate according to claim 17, characterized in that: The second microstructure includes a first fractal structure located on the surface of the first microstructure and a second fractal structure located on the surface of the first fractal structure. The first fractal structure is made of the same material as the first microstructure, and the second fractal structure is made of a different material from the first fractal structure.

20. The patterned substrate according to any one of claims 17 to 19, characterized in that: The surface of the substrate has a third microstructure, the first microstructure wraps the third microstructure, and the light refractive index of the third microstructure is smaller than the light refractive index of the first microstructure.

21. The patterned substrate according to claim 20, characterized in that It also includes a third optical medium layer, which covers the second microstructure, and the light refractive index of the third optical medium layer is greater than the light refractive index of the second microstructure.

22. A semiconductor device, characterized in that: include: A patterned substrate as described in any one of claims 17 to 21; A light emitting structure is formed on a side of the patterned substrate away from the first microstructure.

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