Method for improving etching damage of side wall of AlGaInP red light Micro LED

Abstract

The invention discloses a method for improving etching damage of a side wall of an AlGaInP red light Micro LED. The method comprises the following steps of S1, epitaxial cleaning; s2, carrying out graphical photoetching; s3, ICP (inductively coupled plasma) dry etching is carried out; s4, preparing a wet-process repairing liquid medicine; s5, performing wet treatment on the side wall damage; s6, carrying out post-treatment; s7, effect characterization; in order to solve the problems that a 50-100 nm side wall damage layer is generated in ICP dry etching, nonradiative recombination is caused to cause low device efficiency, and the existing ALE / ALD technology is high in cost or incomplete in repair, the invention provides a process of cleaning, graphical photoetching, ICP etching, weak acid and oxidant wet repair, post-processing and characterization. The removal rate of the damaged layer after repairing is greater than or equal to 90%, the photoluminescence peak value is increased by greater than or equal to 25%, special equipment is not needed, the method is compatible with a Micro LED mass production process, the cost is reduced, the method is suitable for AR / VR full-color display scenes and the like, and the luminescence performance of devices is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic device manufacturing technology, specifically to a method for improving sidewall etching damage of AlGaInP red-light Micro LEDs. It is particularly applicable to the manufacturing needs of small-sized (1-200μm) AlGaInP red-light Micro LEDs in scenarios such as AR (Augmented Reality), VR (Virtual Reality) full-color displays, micro-projection, and high-density display panels, and can be directly integrated into existing Micro LED mass production lines to achieve integrated production of damage repair and device performance optimization. Background Technology

[0002] In full-color Micro LED display technology, red Micro LED is the core device for breaking through the bottleneck of "full color". Compared with GaN-based materials commonly used in green and blue Micro LEDs, AlGaInP, as a red epitaxial material, has a direct bandgap structure, faster electron-hole recombination speed, and significantly higher internal quantum efficiency (IQE). Theoretically, it can achieve higher luminous brightness and energy conversion efficiency, thus becoming the preferred epitaxial material for red Micro LEDs.

[0003] However, with the increasing demand for display resolution, the pixel size of Micro LEDs continues to shrink (evolving from the traditional 100-micron level to the 1-50μm level), significantly increasing the exposed area of ​​the epitaxial material's sidewalls. This makes sidewall etching damage increasingly prominent, becoming a key bottleneck restricting the performance of AlGaInP red Micro LEDs. Currently, the industry commonly uses ICP (inductively coupled plasma) dry etching processes to fabricate AlGaInP red Micro LED pixel arrays, which require the use of Cl-based gases (such as...) during the etching process. , ) is used as the main etching agent, supplemented by group B compound gases (such as , To adjust the etching selectivity, inert gases (such as Ar and Ne) are used to ensure etching uniformity. However, when high-energy Cl-based ions bombard the surface of AlGaInP materials, they can destroy the material's crystal structure and form an etching damage layer with a depth of 50-100 nm. This damage layer contains a large number of dangling bonds, vacancy defects, and impurity ions, which become "non-radiative recombination centers" for electron-hole pairs.

[0004] During device operation, electron-hole pairs are prone to Shockley-Read-Hall (SRH) nonradiative recombination at the aforementioned defect centers—that is, charge carriers release energy through the defect centers without being converted into photons. This directly leads to a significant reduction in the external quantum efficiency (EQE) and luminous brightness of AlGaInP red Micro LEDs, as well as a decrease in the energy-to-light conversion efficiency. It also exacerbates device heating and lifespan degradation. Furthermore, the surface recombination rate of AlGaInP material is inherently higher than that of GaN material, and the nonradiative recombination effect caused by sidewall damage is further amplified, making it difficult for existing AlGaInP red Micro LEDs to meet the core requirements of "high brightness, high efficiency, and long lifespan" for full-color displays.

[0005] To address these issues, the industry has proposed two types of repair solutions: one is ALE (Atomic Layer Etching), which removes the damaged layer through dry etching with atomic-level precision. However, this technology requires specialized and expensive equipment, has a slow etching rate, and is difficult to adapt to mass production requirements. The other is ALD (Atomic Layer Deposition), which covers sidewall defects by depositing a passivation layer. However, the passivation layer has poor interfacial adhesion with AlGaInP material, is prone to peeling after long-term use, and cannot completely remove the formed damaged layer, resulting in limited repair effectiveness.

[0006] Therefore, there is an urgent need for a low-cost, highly compatible, and stable repair method for AlGaInP red-light Micro LED sidewall etching damage to overcome existing technological bottlenecks. Summary of the Invention

[0007] The purpose of this invention is to provide a method for improving the sidewall etching damage of AlGaInP red Micro LEDs, so as to solve the problems of "high equipment cost (ALE / ALD), incomplete repair (ALD), poor mass production compatibility (ALE), and low parameter controllability" in the existing AlGaInP red Micro LED sidewall etching damage repair technology.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for improving sidewall etching damage in AlGaInP red-light Micro LEDs includes the following steps: S1, Epitaxial Cleaning: The AlGaInP epitaxial material is sequentially subjected to ultrasonic cleaning with organic reagents, immersion in polar solvents, and rinsing with deionized water, and then spin-dried to obtain a clean epitaxial wafer. S2, Patterning photolithography: Photoresist is coated on a clean AlGaInP epitaxial surface, and a patterned mask is formed by exposure and development; S3, ICP dry etching: The AlGaInP epitaxial wafer with a patterned mask is placed in an ICP etching machine and etched using a mixed gas containing Cl-based gas and inert gas to form a Micro LED pixel array. S4, Preparation of wet repair solution: Mix weak acid with deionized water and heat and stir until completely dissolved. Then add oxidant and stir evenly. Cool to room temperature to obtain wet repair solution. S5, Wet treatment of sidewall damage: The etched AlGaInP epitaxial wafer is immersed in a wet repair solution. The solution is oscillated to make full contact with the pixel sidewall and the etched damage layer is removed by etching. S6, Post-processing: The epitaxial wafer after wet processing is rinsed with deionized water to remove residual chemicals, and then dried with inert gas. S7, Effect Characterization: The sidewall morphology was observed by electron microscopy and the luminescence performance was characterized by photoluminescence testing to verify the damage repair effect.

[0009] In a preferred embodiment, in step S1, the parameters for epitaxial cleaning are as follows: ultrasonic cleaning time with organic reagent is 5-20 min, immersion time with polar solvent is 3-8 min, and rinsing time with deionized water is 3-8 min; the organic reagent is selected from at least one of acetone and ethanol, and the polar solvent is selected from at least one of isopropanol and methanol.

[0010] In a preferred embodiment, the specific operation of patterning photolithography in step S2 includes: applying positive or negative photoresist using a spin coater at a spin coater speed of 2000-6000 r / s and a photoresist thickness of 1.0-2.0 μm; the pixel shape of the patterned mask is cylindrical, square, or polygonal, with a pixel size of 1-200 μm; and the exposure process uses an ultraviolet exposure machine or a deep ultraviolet exposure machine.

[0011] In a preferred embodiment, in step S3, the parameters for ICP dry etching are as follows: upper electrode power 500-900W, lower electrode power 50-150W; in the mixed etching gas, the flow rate of Cl-based gas is 40-60 sccm, the flow rate of auxiliary gas is 5-15 sccm, and the flow rate of inert gas is 5-15 sccm; the etching time is 200-400 s; the Cl-based gas is selected from... , At least one of the following, the auxiliary gas is selected from , At least one of the following, wherein the inert gas is selected from at least one of Ar and Ne.

[0012] In a preferred embodiment, in step S4, the preparation parameters of the wet remediation solution are as follows: the mass ratio of weak acid to deionized water is 0.5:1-15:1, and after mixing, it is heated in a constant temperature water bath at 20-50℃ and stirred with a magnetic stirrer for 3-15 minutes; the volume ratio of the oxidant to the weak acid aqueous solution is 0.8:1-1.2:1, and after adding the oxidant, stirring continues for 3-15 minutes; the weak acid is selected from at least one of citric acid, acetic acid, and oxalic acid, and the oxidant is selected from... At least one of ammonium persulfate, with an oxidant concentration of 1%-5%.

[0013] In a preferred embodiment, in step S5, the conditions for wet treatment of sidewall damage are as follows: the epitaxial sheet is immersed in the solution for 20-150 seconds, and the oscillation frequency is 50-200 times / min; the solution temperature is maintained at 20-30℃ during the immersion process.

[0014] In a preferred embodiment, the post-treatment requirements in step S6 are as follows: the deionized water rinsing time is 40-80 seconds, and flowing deionized water is used during the rinsing process; the inert gas is selected from at least one of nitrogen and argon, with a gas purity ≥99.9% and a drying pressure of 0.1-0.3 MPa.

[0015] In a preferred embodiment, the operation method for characterizing the effect in step S7 is as follows: when observing with an electron microscope, the stage angle is adjusted to 30°-60° and the magnification is 100,000-200,000 times; the photoluminescence test adopts a time-resolved photoluminescence test system, the test wavelength covers the AlGaInP red light band, and the peak intensity of photoluminescence before and after the treatment is compared.

[0016] In a preferred embodiment, after the wet treatment, the sidewall etching damage layer removal rate of the AlGaInP red Micro LED is ≥90%, and the peak photoluminescence intensity is increased by ≥25%.

[0017] In a preferred embodiment, the method is applicable to AlGaInP red Micro LEDs on different substrates and is directly compatible with MicroLED mass production processes.

[0018] Due to the application of the above technical solution, the beneficial effects of this application compared with the prior art are as follows: 1. Stable and efficient repair effect: Through the wet process system of "weak acid + oxidant", the removal rate of etched damage layer can be ≥90%, the peak intensity of photoluminescence can be increased by ≥25%, and the sidewall dangling bonds can be passivated, which inhibits nonradiative recombination from the source. The external quantum efficiency of the device can be improved by 15%-30%. 2. Strong process compatibility: The repair process (S1-S7) can be directly integrated into the existing Micro LED mass production process without the need for new special equipment (such as ALE / ALD equipment). Only conventional cleaning, photolithography, ICP etching and characterization equipment are required, reducing equipment modification costs by more than 60%. 3. Wide range of compatibility: Process parameters (such as pixel size 1-200μm, reagent ratio 0.5:1-15:1, immersion time 20-150s) can be flexibly adjusted to adapt to different substrates (GaAs, Si) and different sizes of AlGaInP red Micro LEDs. It also supports a variety of weak acid and oxidant combinations, reducing dependence on a single reagent. 4. High cost controllability: Wet repair solution (citric acid, ... (etc.) The price is low, and the cost of repairing a single piece is reduced by more than 80% compared with ALE / ALD technology; moreover, the parameter range is wide, it is easy to adjust during the production process, and the yield can be stably maintained at more than 95%; 5. Simple operation and easy mass production: The process steps are not complicated, and each step can be automatically controlled (such as ultrasonic cleaning, coating, ICP etching, and chemical solution preparation). It is suitable for batch production, has a strong single batch processing capacity, and meets the needs of industrial mass production. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a flowchart of a method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to the present invention. Figure 2 This is a comparison image of the pixel sidewall morphology observed by SEM before and after citric acid treatment in Embodiment 2 of the present invention; Figure 3 This is a comparison chart of the intensity of TRPL tests before and after citric acid treatment in Example 2 of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0024] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0025] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] Example 1 Please see Figure 1 This invention provides a method for improving sidewall etching damage in AlGaInP red Micro LEDs. Based on the design concept of "step-by-step collaboration, parameter optimization, and gentle repair," a process route centered on "epitaxy cleaning - patterning photolithography - ICP etching - wet repair - post-processing - effect characterization" is proposed, specifically including the following steps: S1, External Cleaning – Laying the Foundation for Cleanroom Processes A three-stage purification process is performed on AlGaInP epitaxial materials (compatible with different substrate types such as GaAs and Si substrates). The core purpose is to remove organic contaminants, particulate impurities, and oxide layers from the epitaxial surface, preventing impurities from embedding into the etching damage layer during subsequent processes and affecting the repair effect. Organic reagent ultrasonic cleaning: Acetone or ethanol (or a mixture of both) is selected as the organic reagent. The epitaxial wafer is immersed in the reagent and cleaned with an ultrasonic frequency of 20-40kHz for 5-20 minutes. Ultrasonic vibration can destroy the adhesion between organic contaminants (such as photoresist residue and environmental oil) and the epitaxial surface, achieving deep cleaning. Immersion in polar solvents: Transfer the ultrasonically treated epitaxial wafer to isopropanol or methanol (or a mixture of both) and immerse it for 3-8 minutes. Polar solvents can dissolve residual organic reagents and further remove small molecule impurities, thus avoiding organic residues from affecting the quality of subsequent photoresist coating. Rinse and spin dry with deionized water: using water with a resistivity ≥ 18.2. Rinse the epitaxial wafer with ultrapure water for 3-8 minutes to remove residual solvent; then place it in a spin dryer and spin dry at a high speed of 1000-3000 r / min to obtain a clean epitaxial wafer free of moisture and impurities.

[0028] S2, Patterning Lithography – Defining Pixel Structure A precise patterned mask is formed on the clean AlGaInP epitaxial surface using photolithography, providing a selective "protect-etch" basis for subsequent ICP etching, adapting to different pixel size requirements: Photoresist coating: A spin coater is used to coat positive or negative photoresist (selected according to pixel accuracy requirements). The spin coater speed is adjusted to 2000-6000 r / s. Low speed (2000-3000 r / s) is suitable for large-size (100-200μm) pixels, which can obtain a thicker (1.8-2.0μm) photoresist layer and improve etching protection. High speed (4000-6000 r / s) is suitable for small-size (1-50μm) pixels, which can form a thinner (1.0-1.5μm) photoresist layer and ensure image resolution. Exposure and Development: Use a UV lithography machine (wavelength 365-436nm) or a deep UV lithography machine (wavelength 248-193nm, suitable for ≤10μm small pixels) for exposure. The exposure dose is adjusted to 50-200 mg / L depending on the type of photoresist. After exposure, the corresponding developing solution (such as NaOH aqueous solution for positive photoresist and cyclohexanone solution for negative photoresist) is used to develop and remove the photoresist in the unexposed (positive) or exposed (negative) areas, ultimately forming a cylindrical, square or polygonal patterned mask with pixel size covering 1-200μm.

[0029] S3, ICP dry etching – forming a Micro LED pixel array Dry etching of AlGaInP epitaxial wafers with patterned masks was performed using an ICP etching machine, aiming to control the degree of etching damage while ensuring pixel pattern accuracy. Etching parameter settings: Adjust the upper electrode power to 500-900W (to control plasma density; too high a power will easily aggravate damage, while too low a power will slow down the etching rate); adjust the lower electrode power to 50-150W (to control ion bombardment energy and balance etching selectivity and damage). Etching gas configuration: The mixed gas includes Cl-based gases ( The flow rate is 40-60 sccm. As the main etching agent, it reacts chemically with AlGaInP to generate volatile halides. (Assist gas) or (5-15 sccm flow rate to enhance etching selectivity and reduce damage to the substrate) and inert gas (Ar or Ne, 5-15 sccm flow rate to homogenize plasma distribution and improve etching uniformity). Etching execution: The etching time is controlled at 200-400s (adjusted according to the thickness of the epitaxial layer to ensure etching to the preset depth). After etching, an AlGaInP red Micro LED pixel array with a clear sidewall structure is formed. At this time, it can be seen from the initial observation that there is an etching damage layer of 50-100nm on the sidewall of the pixel, which needs to be removed by subsequent wet processing.

[0030] S4, Preparation of Wet Repair Solution – Creating a High-Efficiency Repair System A wet repair solution consisting of a weak acid and an oxidizing agent is prepared. The mild corrosiveness of the weak acid removes the damaged layer, while the oxidizing agent accelerates the reaction and enhances the passivation effect. Preparation of weak acid-water mixture: Citric acid, acetic acid, or oxalic acid (or a mixture thereof) are selected as the weak acid (weak acids can release water slowly). To avoid excessive corrosion of the AlGaInP lattice by strong acid, mix with deionized water at a mass ratio of 0.5:1-15:1 and place in a glass container; place the container in a constant temperature water bath at 20-50℃ and heat (heating can accelerate the dissolution of weak acid; if the temperature is too low, the dissolution will be slow, and if the temperature is too high, the solution will easily evaporate), and at the same time use a magnetic stirrer to stir at a speed of 300-500r / min for 3-15min until the weak acid is completely dissolved and a uniform weak acid aqueous solution is formed; Oxidizing agent mixing: Add oxidizing agent ( ) to the above weak acid aqueous solution. Alternatively, ammonium persulfate (concentration 1%-5%) can be used, and the volume ratio of the oxidant to the weak acid aqueous solution should be controlled at 0.8:1-1.2:1. It can decompose and release O2 and ,accelerate Reacts with oxides in the damaged layer; ammonium persulfate provides a strong oxidizing environment, enhancing the passivation effect on dangling bonds; after adding the oxidant, continue stirring for 3-15 minutes to ensure the solution is mixed evenly, then cool to 20-30℃ for later use (room temperature can avoid excessive activity of the solution leading to uncontrolled corrosion).

[0031] S5, Wet treatment of sidewall damage – precise removal of the damaged layer The etched AlGaInP epitaxial wafer was immersed in a wet repair solution, and the sidewall damage layer was removed by controlled chemical etching, while simultaneously achieving sidewall passivation. Immersion and Vibration: Completely immerse the epitaxial wafer in the chemical solution for 20-150 seconds (20-60 seconds for small pixels to avoid over-etching; 80-150 seconds for large pixels to ensure deep damage removal); during immersion, vibrate the epitaxial wafer up and down at a frequency of 50-200 times / min—vibration can break the diffusion boundary layer formed by the chemical solution on the sidewall surface, ensuring that fresh chemical solution is in continuous contact with the damaged layer and improving the uniformity of etching; Reaction mechanism: in the drug solution With the damaged layer , When the oxides react, soluble salts (such as aluminum citrate and indium acetate) are formed and detached from the sidewall along with the drug solution; simultaneously, weak acid molecules can adsorb onto the sidewall surface, passivating residual dangling bonds; the oxidant reduces impurity ions (such as aluminum citrate and indium acetate) in the damaged layer through oxidation. This further reduces the density of non-radiative recombination centers.

[0032] S6, Post-treatment – ​​to avoid secondary pollution and oxidation The epitaxial wafers after wet processing are rinsed and dried to remove residual chemicals and reaction products and prevent secondary oxidation of the sidewalls. Rinse with deionized water: Use ultrapure water (resistivity ≥ 18.2). Rinse the epitaxial wafer at a flow rate of 5-10 mL / min for 40-80 seconds. Flowing water can efficiently rinse away residual drugs and soluble reaction products adhering to the sidewalls and surfaces, preventing residual drugs from continuously corroding the pixel structure. Drying with inert gas: Use nitrogen or argon (purity ≥ 99.9%), or less in low-purity gases. , (This can easily lead to sidewall oxidation). The surface of the epitaxial wafer is dried in all directions with a pressure of 0.1-0.3MPa (too high a pressure can damage small pixels, while too low a pressure will not dry it thoroughly) to ensure that there is no moisture residue and to obtain a clean and oxidation-free repaired Micro LED pixel array.

[0033] S7, Performance Characterization – Verifying Repair Performance By observing the microstructure and testing the luminescence performance, the sidewall damage repair effect is quantitatively evaluated to ensure that the device performance requirements are met. Electron microscopy observation: SEM (scanning electron microscope) or TEM (transmission electron microscope) is used to observe the sidewall morphology of the pixels. The stage angle is adjusted to 30°-60° (the tilt angle can clearly show the sidewall cross section), and the magnification is adjusted to 100,000-200,000 times. By comparing the images after etching and after repair, the extent of damage layer removal can be intuitively judged. The sidewall after repair should have no obvious defects and the surface roughness should be ≤5nm. Photoluminescence testing: A TRPL (time-resolved photoluminescence) testing system was used, with a 405nm laser as the excitation source (to meet the excitation requirements of AlGaInP materials). The test wavelength covered the red light band of AlGaInP (620-680nm). The peak photoluminescence intensity and decay lifetime before and after treatment were recorded. The peak photoluminescence intensity should increase by ≥25% and the decay lifetime should be extended by ≥20% after repair, indicating that nonradiative recombination was effectively suppressed and the luminescence performance of the device was significantly improved.

[0034] Example 2 Please see Figure 2 and 3 This invention provides a method for improving sidewall etching damage in AlGaInP red-light Micro LEDs, further illustrating the technical solution of this invention. All reagents used in the examples are analytical grade, and the equipment is conventional equipment in the semiconductor manufacturing field. The examples use a 4-inch GaAs substrate AlGaInP epitaxial wafer as the treatment object, employing citric acid + The specific steps to repair 5μm small pixels are as follows: S1, epitaxial cleaning: acetone ultrasonic cleaning for 10 min (ultrasonic frequency 30 kHz) → isopropanol soaking for 5 min → ultrapure water rinsing for 5 min → spin drying at 2000 r / min; S2, Patterning Photolithography: Coating positive photoresist, spin coating speed 5000 r / s (photoresist thickness 1.2 μm) → Deep ultraviolet exposure (wavelength 248 nm, dose 100). → Development forms a cylindrical mask with a diameter of 5μm; S3, ICP etching: Upper electrode power 700W, lower electrode power 100W → gas flow rate 50 sccm 10 sccm, Ar 10 sccm → etching time 300s; SEM observation after etching: sidewall damage layer depth approximately 80nm; S4, Solution preparation: Citric acid to deionized water mass ratio 5:1 → Heating in a 35℃ water bath with magnetic stirring for 8 minutes → Adding an equal volume of 3% Stir for 8 minutes → Cool to 25°C; S5, wet treatment: soaking time 40s, oscillation frequency 100 times / min; S6, Post-treatment: Rinse with ultrapure water for 60 seconds → Dry with nitrogen (pressure 0.2MPa); S7, Characterization: SEM (stage 45°, magnification 150,000x) showed that the sidewall damage layer was completely removed and the surface roughness was 3nm; TRPL test: the peak photoluminescence intensity before repair was 1800 a.u., and after repair it was 2430 a.u., an improvement of 35%.

[0035] Example 3 This invention provides a method for improving sidewall etching damage in AlGaInP red-light Micro LEDs. The technical solution of this invention is further illustrated. All reagents used in the examples are analytical grade, and the equipment is conventional equipment in the semiconductor manufacturing field. The examples use a 4-inch GaAs substrate AlGaInP epitaxial wafer as the treatment object, employing acetic acid + ammonium persulfate to repair 100μm large-size pixels. The specific steps are as follows: S1, epitaxial cleaning: ethanol ultrasonic cleaning for 15 min (ultrasonic frequency 25 kHz) → methanol soaking for 6 min → ultrapure water rinsing for 6 min → spin drying at 2500 r / min; S2, Patterning Photolithography: Coating negative photoresist, spin coating speed 3000 r / s (photoresist thickness 1.8 μm) → UV exposure (wavelength 405 nm, dose 150). → Development forms a square mask with a side length of 100μm; S3, ICP etching: Upper electrode power 800W, lower electrode power 120W → gas flow rate 45sccm 12 sccm, Ne 12 sccm → etching time 350s; SEM observation after etching: sidewall damage layer depth approximately 60nm; S4, Preparation of the solution: Acetic acid to deionized water in a mass ratio of 10:1 → Heating in a 40°C water bath and stirring magnetically for 12 minutes → Adding 5% ammonium persulfate solution in a volume ratio of 1:1 and stirring for 10 minutes → Cooling to 28°C; S5, wet treatment: soaking time 100s, oscillation frequency 150 times / min; S6, Post-processing: Rinse with ultrapure water for 70 seconds → Dry with argon gas (pressure 0.25MPa); S7, Characterization: SEM (stage 50°, magnification 120,000x) showed that the sidewall damage layer removal rate was 95% and the surface roughness was 4nm; TRPL test: the peak photoluminescence intensity before repair was 2200 a.u., and after repair it was 2860 a.u., an improvement of 30%.

[0036] Example 4 This invention provides a method for improving sidewall etching damage in AlGaInP red-light Micro LEDs. The technical solution of this invention is further illustrated. All reagents used in the examples are analytical grade, and the equipment is conventional equipment in the semiconductor manufacturing field. The examples use a 4-inch GaAs substrate AlGaInP epitaxial wafer as the treatment object, employing oxalic acid + The specific steps to repair pixels with a size of 50μm are as follows: S1, epitaxial cleaning: ultrasonic cleaning of acetone-ethanol mixture (volume ratio 1:1) for 8 min → soaking in isopropanol-methanol mixture (volume ratio 1:1) for 4 min → rinsing with ultrapure water for 4 min → spin drying at 1500 r / min; S2, Patterning Photolithography: Coating positive photoresist, spin coating speed 4000 r / s (photoresist thickness 1.5 μm) → UV exposure (wavelength 365 nm, dose 80). → Development forms a hexagonal mask with a diameter of 50μm; S3, ICP etching: Upper electrode power 600W, lower electrode power 80W → gas flow rate 55sccm 8sccm, Ar 8sccm → etching time 250s; SEM observation after etching: sidewall damage layer depth approximately 70nm; S4, Solution preparation: Oxalic acid to deionized water mass ratio 3:1 → Heat in a 30℃ water bath, stir magnetically for 5 minutes → Add 2% oxalic acid solution at a volume ratio of 0.9:1. Stir for 6 minutes → Cool to 22°C; S5, wet treatment: soaking time 70s, oscillation frequency 80 times / min; S6, Post-treatment: Rinse with ultrapure water for 50 seconds → Dry with nitrogen (pressure 0.15MPa); S7, Characterization: SEM (stage 40°, magnification 160,000x) showed a 92% removal rate of the sidewall damage layer and a surface roughness of 3.5nm; TRPL test: the peak photoluminescence intensity before repair was 1900 a.u., and after repair it was 2565 a.u., an improvement of 35%.

[0037] In photoluminescence (PL) testing, au is an abbreviation for "arbitrary unit," which is a relative intensity unit commonly used in scientific research and industrial testing, rather than an absolute physical unit. The role of au is to "eliminate the interference of differences in experimental conditions and clearly present the intensity changes within the same system." As long as the test conditions are consistent, the relative comparison results based on au are accurate and reliable, and can effectively verify the technical effect of "wet repair to improve luminescence performance" in this application.

[0038] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving sidewall etching damage in AlGaInP red-light Micro LEDs, characterized in that, Includes the following steps: S1, Epitaxial Cleaning: The AlGaInP epitaxial material is sequentially subjected to ultrasonic cleaning with organic reagents, immersion in polar solvents, and rinsing with deionized water, and then spin-dried to obtain a clean epitaxial wafer. S2, Patterning photolithography: Photoresist is coated on a clean AlGaInP epitaxial surface, and a patterned mask is formed by exposure and development; S3, ICP dry etching: The AlGaInP epitaxial wafer with a patterned mask is placed in an ICP etching machine and etched using a mixed gas containing Cl-based gas and inert gas to form a Micro LED pixel array. S4, Preparation of wet repair solution: Mix weak acid with deionized water and heat and stir until completely dissolved. Then add oxidant and stir evenly. Cool to room temperature to obtain wet repair solution. S5, Wet treatment of sidewall damage: The etched AlGaInP epitaxial wafer is immersed in a wet repair solution. The solution is oscillated to make full contact with the pixel sidewall and the etched damage layer is removed by etching. S6, Post-processing: The epitaxial wafer after wet processing is rinsed with deionized water to remove residual chemicals, and then dried with inert gas. S7, Effect Characterization: The sidewall morphology was observed by electron microscopy and the luminescence performance was characterized by photoluminescence testing to verify the damage repair effect.

2. The method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to claim 1, characterized in that, In step S1, the parameters for epitaxial cleaning are as follows: ultrasonic cleaning time for organic reagents is 5-20 min, immersion time in polar solvent is 3-8 min, and rinsing time with deionized water is 3-8 min; the organic reagent is selected from at least one of acetone and ethanol, and the polar solvent is selected from at least one of isopropanol and methanol.

3. The method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to claim 1, characterized in that, In step S2, the specific operations of patterned photolithography include: coating positive or negative photoresist using a spin coater at a spin coater speed of 2000-6000 r / s and a photoresist thickness of 1.0-2.0 μm; the pixel shape of the patterned mask is cylindrical, square, or polygonal, and the pixel size is 1-200 μm; the exposure process uses an ultraviolet exposure machine or a deep ultraviolet exposure machine.

4. The method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to claim 1, characterized in that, In step S3, the parameters for ICP dry etching are as follows: upper electrode power 500-900W, lower electrode power 50-150W; in the mixed etching gas, the flow rate of Cl-based gas is 40-60 sccm, the flow rate of auxiliary gas is 5-15 sccm, and the flow rate of inert gas is 5-15 sccm; the etching time is 200-400 s; the Cl-based gas is selected from... , At least one of the following, the auxiliary gas is selected from , At least one of the following, wherein the inert gas is selected from at least one of Ar and Ne.

5. The method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to claim 1, characterized in that, In step S4, the preparation parameters of the wet remediation solution are as follows: the mass ratio of weak acid to deionized water is 0.5:1-15:1, and after mixing, it is heated in a constant temperature water bath at 20-50℃ and stirred with a magnetic stirrer for 3-15 minutes; the volume ratio of the oxidant to the weak acid aqueous solution is 0.8:1-1.2:1, and after adding the oxidant, stirring is continued for 3-15 minutes; the weak acid is selected from at least one of citric acid, acetic acid, and oxalic acid, and the oxidant is selected from... At least one of ammonium persulfate, with an oxidant concentration of 1%-5%.

6. The method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to claim 1, characterized in that, In step S5, the conditions for wet treatment of sidewall damage are as follows: the epitaxial sheet is immersed in the solution for 20-150 seconds, and the oscillation frequency is 50-200 times / min; the solution temperature is maintained at 20-30℃ during the immersion process.

7. The method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to claim 1, characterized in that, In step S6, the specific requirements for post-treatment are as follows: deionized water rinsing time is 40-80s, and flowing deionized water is used during the rinsing process; the inert gas is selected from at least one of nitrogen and argon, with a gas purity ≥99.9% and a drying pressure of 0.1-0.3MPa.

8. The method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to claim 1, characterized in that, In step S7, the operation method for characterizing the effect is as follows: when observing with an electron microscope, the stage angle is adjusted to 30°-60° and the magnification is 100,000-200,000 times; the photoluminescence test uses a time-resolved photoluminescence test system, the test wavelength covers the AlGaInP red light band, and the peak intensity of photoluminescence before and after the treatment is compared.

9. The method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to claim 8, characterized in that, After the wet process, the sidewall etching damage layer removal rate of AlGaInP red Micro LED is ≥90%, and the peak photoluminescence intensity is increased by ≥25%.

10. The method for improving sidewall etching damage in AlGaInP red-light Micro LEDs according to any one of claims 1-9, characterized in that, The method is applicable to AlGaInP red Micro LEDs on different substrates and is directly compatible with Micro LED mass production processes.

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