Method for improving sidewall etching damage of AlGaInP red light Micro LED

Abstract

The application discloses a method for improving AlGaInP red light Micro LED sidewall etching damage, comprising the following steps: S1, epitaxial cleaning; S2, patterned photolithography; S3, ICP dry etching; S4, S4, wet repair liquid preparation; S5, sidewall damage wet treatment; S6, post-treatment; S7, effect characterization; the application aims at the problems of 50-100nm sidewall damage layer caused by ICP dry etching, low device efficiency caused by non-radiative recombination, and high cost or incomplete repair of existing ALE / ALD technology, and proposes a process of cleaning-patterned photolithography-ICP etching-weak acid+oxidizing agent wet repair-post-treatment-characterization; after repair, the damage layer removal rate is greater than or equal to 90%, the photoluminescence peak value is increased by greater than or equal to 25%, no special equipment is needed, the process is compatible with Micro LED mass production process, the cost is reduced, and the method is suitable for AR / VR full-color display scenes and effectively improves the light-emitting performance of the device.

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 the operation of the device, the electron-hole pairs are prone to Shockley-Read-Hall (SRH) non-radiative recombination in the above defect center, that is, the carriers release energy through the defect center without being converted into photons, which directly leads to a substantial reduction in the external quantum efficiency (EQE), luminous brightness and electrical-to-optical energy conversion efficiency of the AlGaInP red Micro LED, and aggravates the device heating and service life decay; in addition, the surface recombination rate of the AlGaInP material is higher than that of the GaN material, and the non-radiative recombination effect caused by the sidewall damage is further amplified, so that the existing AlGaInP red Micro LED cannot meet the core requirements of "high brightness, high efficiency and long service life" for full-color display.

[0005] To solve the above problems, two types of repair schemes have been proposed in the industry: one is ALE (atomic layer etching) technology, which removes the damaged layer through atomic-level precision dry etching, but this technology requires special and expensive equipment and has a slow etching rate, which is difficult to adapt to mass production requirements; the other is ALD (atomic layer deposition) technology, which covers the sidewall defects with a passivation layer, but the interface bonding force between the passivation layer and the AlGaInP material is poor, and peeling may occur during long-term use, and the damaged layer formed cannot be completely removed, so the repair effect is limited.

[0006] Therefore, there is an urgent need for an AlGaInP red Micro LED sidewall etching damage repair method with low cost, high compatibility and stable repair effect to break through the technical bottleneck of the prior art. SUMMARY

[0007] The purpose of the present application is to provide a method for improving the sidewall etching damage of AlGaInP red Micro LED 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 technical problems, the technical solution adopted by the present application is:

[0009] A method for improving the sidewall etching damage of AlGaInP red Micro LED, comprising the following steps:

[0010] S1, epitaxial cleaning: sequentially performing organic reagent ultrasonic cleaning, polar solvent soaking and deionized water rinsing on the AlGaInP epitaxial material, and then performing spin-drying treatment to obtain a clean epitaxial wafer;

[0011] S2, patterned photolithography: coating a photoresist on the clean AlGaInP epitaxial surface, and forming a patterned mask through exposure and development;

[0012] S3, ICP dry etching: placing the AlGaInP epitaxial wafer with a patterned mask in an ICP etching machine, using a mixed gas containing a Cl-based gas and an inert gas for etching to form a Micro LED pixel array;

[0013] S4, wet repair solution preparation: mixing a weak acid with deionized water and heating and stirring until completely dissolved, then adding an oxidizing agent and stirring uniformly, and cooling to room temperature to obtain a wet repair solution;

[0014] S5, wet treatment of sidewall damage: immersing the etched AlGaInP epitaxial wafer in the wet repair solution, and fully contacting the solution with the pixel sidewall by oscillation to remove the etching damage layer by corrosion;

[0015] S6, post-treatment: rinsing the wet-treated epitaxial wafer with deionized water to remove residual solution, and then blowing dry with an inert gas;

[0016] S7, effect characterization: observing the sidewall morphology by electron microscopy and characterizing the luminescent performance by photoluminescence testing to verify the damage repair effect.

[0017] In a preferred scheme, in step S1, the parameter range of epitaxial cleaning is: organic reagent ultrasonic cleaning time 5-20 min, polar solvent soaking time 3-8 min, deionized water rinsing time 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 isopropyl alcohol and methanol.

[0018] In a preferred scheme, in step S2, the specific operation of the patterned photolithography includes: using a spin coater to coat a positive or negative photoresist, spin coater speed 2000-6000 r / s, photoresist thickness 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.

[0019] In a preferred scheme, in step S3, the parameter range of ICP dry etching is: upper electrode power 500-900 W, lower electrode power 50-150 W; in the mixed etching gas, the Cl-based gas flow is 40-60 sccm, the auxiliary gas flow is 5-15 sccm, and the inert gas flow is 5-15 sccm; etching time 200-400 s; the Cl-based gas is selected from at least one of 、 The auxiliary gas is selected from at least one of 、 The inert gas is selected from at least one of Ar and Ne.

[0020] Preferably, in step S4, the configuration parameters of the wet repair solution are as follows: the mass ratio of weak acid to deionized water is 0.5:1-15:1, after mixing, it is placed in a constant temperature water bath at 20-50℃ for heating, and a magnetic stirrer is used for stirring for 3-15min; the volume ratio of the oxidizing agent to the weak acid aqueous solution is 0.8:1-1.2:1, after adding the oxidizing agent, continue to stir for 3-15min; the weak acid is selected from at least one of citric acid, acetic acid and oxalic acid, and the oxidizing agent is selected from at least one of hydrogen peroxide and ammonium persulfate, and the concentration of the oxidizing agent is 1%-5%.

[0021] Preferably, in step S5, the conditions of the wet treatment of the side wall damage are as follows: the epitaxial wafer is soaked in the solution for 20-150s, and the oscillation frequency is 50-200 times / min; during the soaking process, the temperature of the solution is maintained at 20-30℃.

[0022] Preferably, in step S6, the specific requirements of the post-treatment are as follows: the deionized water flushing time is 40-80s, and flowing deionized water is used during the flushing process; the inert gas is selected from at least one of nitrogen and argon, the gas purity is ≥99.9%, and the blow-drying pressure is 0.1-0.3MPa.

[0023] Preferably, in step S7, the operation mode of the effect characterization is as follows: when observed by an electron microscope, the stage angle is adjusted to 30°-60°, and the magnification is 100-200w; the time-resolved photoluminescence test system is used for the photoluminescence test, the test wavelength covers the AlGaInP red light band, and the peak intensity of the photoluminescence before and after the treatment is compared.

[0024] Preferably, after the wet treatment, the removal rate of the side wall etching damage layer of the AlGaInP red light Micro LED is ≥90%, and the peak intensity of the photoluminescence is increased by ≥25%.

[0025] Preferably, the method is suitable for AlGaInP red light Micro LED of different substrates and is directly compatible with the Micro LED mass production process.

[0026] Thanks to the use of the above technical solutions, the beneficial effects of the present application compared with the prior art are as follows:

[0027] 1. Stable and efficient repair effect: through the wet system of "weak acid + oxidizing agent", the etching damage layer removal rate is ≥90%, the photoluminescence peak intensity is increased by ≥25%, the side wall dangling bonds are passivated, the non-radiative recombination is inhibited from the root, and the device external quantum efficiency can be increased by 15%-30%;

[0028] ​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 additional special equipment (such as ALE / ALD equipment), only requiring conventional cleaning, photolithography, ICP etching and characterization equipment, with equipment modification cost reduced by more than 60%;

[0029] 3. Wide adaptation range: Process parameters (such as pixel size 1-200pm, drug liquid ratio 0.5:1-15:1, soaking time 20-150s) can be flexibly adjusted to adapt to different substrates (GaAs, Si) and different sizes of AlGaInP red light Micro LED, while supporting multiple combinations of weak acid and oxidizing agent, reducing the dependence on a single reagent;

[0030] 4. High controllability of cost: Wet repair reagent (citric acid, etc.) is low in price, with single chip repair cost reduced by more than 80% compared with ALE / ALD technology; and the parameter range is wide, which is easy to adjust in production process, and the yield can be stably maintained above 95%;

[0031] 5. Simple operation and easy mass production: The process steps have no complex operation, and each link can be automatically controlled (such as ultrasonic cleaning, glue uniformity, ICP etching, reagent preparation), which is suitable for batch production, has strong single batch processing capacity, and meets the needs of industrial mass production. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0033] Figure 1 A flow chart of a method for improving AlGaInP red light Micro LED sidewall etching damage according to the present application;

[0034] Figure 2 A comparison chart of SEM observation of pixel sidewall morphology before and after citric acid treatment in Example 2 of the present application;

[0035] Figure 3 A comparison chart of TRPL test intensity before and after citric acid treatment in Example 2 of the present application. DETAILED DESCRIPTION

[0036] In order to better understand the present application by those skilled in the art, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0037] It should be noted that the terms "first", "second", and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0038] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not intended to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0039] In addition, in addition to being used to indicate the orientation or positional relationship, the above-mentioned partial terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.

[0040] In addition, the terms "mount", "set", "provided with", "connected", "connected", "sleeved" should be broadly understood. For example, it can be a fixed connection, a detachable connection, or a monolithic structure; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or internal communication between two devices, elements or components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0042] Embodiment one

[0043] Please refer to Figure 1 As a method for improving AlGaInP red light Micro LED sidewall etching damage, the present application proposes a process route with "epitaxial cleaning - patterning lithography - ICP etching - wet repair - post-processing - effect characterization" as the core through the design idea of "step-by-step cooperation, parameter optimization, and gentle repair". The specific steps include the following steps:

[0044] S1, epitaxial cleaning - laying the foundation for clean process

[0045] The AlGaInP epitaxial material (which can be adapted to GaAs substrate, Si substrate and other different substrate types) is subjected to three-stage purification treatment, and the core purpose is to remove organic contaminants, particle impurities and oxide layers on the epitaxial surface, so as to avoid the embedding of impurities in the etching damage layer in the subsequent process and affect the repair effect:

[0046] Ultrasonic cleaning of organic reagent: acetone or ethanol (or a mixture of the two) is selected as the organic reagent, the epitaxial wafer is immersed in the reagent, and ultrasonic frequency of 20-40 kHz is used for cleaning for 5-20 min - ultrasonic vibration can destroy the adhesion of organic contaminants (such as photoresist residue, environmental oil stains) to the epitaxial surface, achieving deep decontamination;

[0047] Polar solvent soaking: after ultrasonic cleaning, the epitaxial wafer is transferred to isopropyl alcohol or methanol (or a mixture of the two) for soaking for 3-8 min - the polar solvent can dissolve the residual organic reagent, and further remove small molecular impurities, avoiding the influence of organic residues on the quality of subsequent photoresist coating;

[0048] Deionized water rinsing and spin-drying: the epitaxial wafer is rinsed with ultrapure water with resistivity ≥18.2 for 3-8 min to rinse off the residual solvent; then it is placed in a spin-drying barrel and spun at a high speed of 1000-3000 r / min to obtain a clean epitaxial wafer free of water and impurities.

[0049] S2, patterning lithography - defining pixel structure

[0050] A precise patterned mask is formed on the clean AlGaInP epitaxial surface through the lithography process, providing a selective basis for "protection-etching" for subsequent ICP etching, and adapting to different size pixel requirements:

[0051] Photoresist coating: A spin coater is used to coat positive or negative photoresist (selected according to pixel precision 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 pattern resolution.

[0052] 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.

[0053] S3, ICP dry etching – forming a Micro LED pixel array

[0054] 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.

[0055] 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).

[0056] 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).

[0057] Etching execution: etching time is controlled for 200-400s (adjust according to the thickness of the epitaxial layer to ensure etching to the preset depth), and an AlGaInP red light Micro LED pixel array with a clear side wall structure is formed after etching - at this time, it can be known through preliminary observation that there is a 50-100nm etching damage layer on the pixel side wall, which needs to be removed by subsequent wet processing.

[0058] S4, wet repair solution configuration - preparation of efficient repair system

[0059] The wet repair solution of "weak acid + oxidizing agent" is configured, and the mild corrosion of the weak acid is used to remove the damage layer, and the oxidizing agent accelerates the reaction and improves the passivation effect:

[0060] Weak acid-water mixture preparation: citric acid, acetic acid or oxalic acid (or mixed acid) is selected as the weak acid (the weak acid can slowly release avoiding excessive corrosion of strong acid to the AlGaInP lattice), and deionized water is mixed in a mass ratio of 0.5:1-15:1 and placed in a glass container; the container is placed in a 20-50°C constant temperature water bath for heating (heating can accelerate the dissolution of the weak acid, and too low temperature will slow down the dissolution, and too high temperature will easily lead to volatilization of the solution), while a magnetic stirrer is used to stir at a speed of 300-500r / min for 3-15min, until the weak acid is completely dissolved, forming a uniform weak acid aqueous solution;

[0061] Oxidizing agent mixing: add an oxidizing agent or ammonium persulfate, concentration 1%-5% to the above weak acid aqueous solution, the volume ratio of oxidizing agent to weak acid aqueous solution is controlled at 0.8:1-1.2:1 can decompose and release O2 , accelerate and the reaction of oxides in the damage layer; ammonium persulfate can provide a strong oxidizing environment and enhance the passivation effect on the dangling bonds; continue to stir for 3-15min after adding the oxidizing agent to ensure uniform mixing of the solution, and then cool to room temperature of 20-30°C for standby (room temperature can avoid excessive corrosion caused by high activity of the solution).

[0062] S5, wet processing of side wall damage - precise removal of damage layer

[0063] Submerge the etched AlGaInP epitaxial wafer in the wet repair solution, remove the side wall damage layer through controllable chemical corrosion, and achieve side wall passivation at the same time:

[0064] Soaking and oscillation: The epitaxial wafer is completely immersed in the chemical solution, and the soaking time is controlled to be 20-150 s (small size pixels are soaked for 20-60 s to avoid excessive corrosion; large size pixels are soaked for 80-150 s to ensure that the deep damage is removed); during the soaking process, the epitaxial wafer is oscillated up and down at a frequency of 50-200 times / min - the oscillation can break the diffusion boundary layer formed by the chemical solution on the side wall surface, ensure that the fresh chemical solution continuously contacts the damage layer, and improve the corrosion uniformity;

[0065] Reaction mechanism: The oxidizing agent in the chemical solution reacts with the oxides in the damage layer, such as , , , to generate soluble salts (such as aluminum citrate and indium acetate), which are removed from the side wall with the chemical solution; at the same time, weak acid molecules can be adsorbed on the side wall surface to passivate the remaining dangling bonds; the oxidizing agent can reduce the impurity ions (such as ) in the damage layer through oxidation, further reducing the density of non-radiative recombination centers.

[0066] S6, post-processing - avoid secondary pollution and oxidation

[0067] The epitaxial wafer after wet processing is rinsed and dried to remove residual chemical solution and reaction products, preventing secondary oxidation of the side wall:

[0068] Deionized water rinse: The epitaxial wafer is rinsed with ultrapure water (resistivity ≥18.2 ) at a flow rate of 5-10 mL / min for 40-80 s - flowing water can efficiently remove residual chemical solution and soluble reaction products attached to the side wall and surface, preventing residual chemical solution from continuously corroding the pixel structure;

[0069] Inert gas drying: Nitrogen or argon (purity ≥99.9%, low-purity gases , can easily cause side wall oxidation) is used to dry the surface of the epitaxial wafer at a pressure of 0.1-0.3 MPa (too high pressure can easily damage small size pixels, and too low pressure can not dry completely) to ensure no water residue, obtaining a clean and non-oxidized repaired Micro LED pixel array.

[0070] S7, effect characterization - verify repair performance

[0071] Through microscopic morphology observation and light emitting performance test, the side wall damage repair effect is quantitatively evaluated to ensure that the device performance requirements are met:

[0072] SEM (scanning electron microscope) or TEM (transmission electron microscope) is used to observe the pixel sidewall morphology, the stage angle is adjusted to 30°-60° (the inclination angle can clearly present the sidewall section), and the magnification is adjusted to 100-200 times - by comparing the images after etching and after repair, the removal of the damaged layer can be directly judged, and the sidewall after repair should have no obvious defects, and the surface roughness is ≤5nm;

[0073] Photoluminescence test: a TRPL (time-resolved photoluminescence) test system is used, the excitation light source is selected to be 405nm laser (adapted to the excitation requirements of AlGaInP material), the test wavelength covers the AlGaInP red light band (620-680nm), and the photoluminescence peak intensity and decay lifetime before and after processing are recorded - the photoluminescence peak intensity after repair should be increased by ≥25%, and the decay lifetime should be extended by ≥20%, indicating that non-radiative recombination is effectively inhibited, and the device light-emitting performance is significantly improved.

[0074] Example two

[0075] See Figure 2 and 3 , a method for improving the etching damage of the sidewall of an AlGaInP red light Micro LED, which further illustrates the technical scheme of the present application, the reagents used in the examples are all of analytical purity, and the equipment is conventional equipment in the semiconductor manufacturing field. The examples take a 4-inch GaAs substrate AlGaInP epitaxial wafer as the processing object, and use citric acid to repair a 5μm small-size pixel, and the specific steps are as follows:

[0076] S1, epitaxial cleaning: acetone ultrasonic cleaning for 10min (ultrasonic frequency 30kHz) → isopropanol soaking for 5min → ultrapure water rinsing for 5min → 2000r / min spin-drying;

[0077] S2, patterned photolithography: coating positive photoresist, uniform coating speed 5000r / s (photoresist thickness 1.2μm) → deep ultraviolet exposure (wavelength 248nm, dose 100 ) → developing to form a cylindrical mask with a diameter of 5μm;

[0078] S3, ICP etching: upper electrode power 700W, lower electrode power 100W → gas flow 50sccm, 10sccm, Ar 10sccm → etching time 300s; SEM observation after etching: the sidewall damage layer depth is about 80nm;

[0079] S4, preparation of liquid medicine: citric acid and deionized water in a mass ratio of 5:1 → 35℃ water bath heating, magnetic stirring for 8min → adding equal volume of 3% H2O2; , stirring 8 min → cooling to 25℃;

[0080] S5, wet treatment: soaking time 40 s, oscillation frequency 100 times / min;

[0081] S6, post-processing: ultrapure water washing 60 s → nitrogen blowing dry (pressure 0.2 MPa);

[0082] S7, characterization: SEM (stage 45°, magnification 150,000 times) shows that the sidewall damage layer is completely removed, and the surface roughness is 3 nm; TRPL test: photoluminescence peak intensity before repair 1800 a.u., after repair 2430 a.u., increase ratio 35%.

[0083] Example Three

[0084] The method for improving AlGaInP red light Micro LED sidewall etching damage of the application further illustrates the technical solutions of the application, the reagents used in the examples are all analytical pure, the equipment is the conventional equipment in the semiconductor manufacturing field, and the 4-inch GaAs substrate AlGaInP epitaxial wafer is taken as the processing object in the example, and the acetate + ammonium persulfate is used to repair 100 mu m large size pixels, and the specific steps are as follows:

[0085] S1, epitaxial cleaning: ethanol ultrasonic cleaning 15 min (ultrasonic frequency 25 kHz) → methanol immersion 6 min → ultrapure water washing 6 min → 2500 r / min spin-drying;

[0086] S2, patterned photolithography: coating negative photoresist, uniform coating rotation speed 3000 r / s (photoresist thickness 1.8 mu m) → ultraviolet exposure (wavelength 405 nm, dose 150 ) → development to form a square mask with a side length of 100 mu m;

[0087] S3, ICP etching: upper electrode power 800 W, lower electrode power 120 W → gas flow 45 sccm, 12 sccm, Ne 12 sccm → etching time 350 s; SEM observation after etching: the sidewall damage layer depth is about 60 nm;

[0088] S4, preparation of liquid medicine: mass ratio of acetic acid to deionized water 10:1 → 40℃ water bath heating, magnetic stirring 12 min → adding 5% ammonium persulfate solution with a volume ratio of 1:1, stirring 10 min → cooling to 28℃;

[0089] S5, wet treatment: soaking time 100 s, oscillation frequency 150 times / min;

[0090] S6, post-processing: ultrapure water washing 70 s → argon blowing dry (pressure 0.25 MPa);

[0091] S7, characterization: SEM (stage 50°, magnification 120000x) shows that the sidewall damage layer removal rate is 95%, and the surface roughness is 4nm; TRPL test: photoluminescence peak intensity before repair is 2200 a.u., and after repair is 2860 a.u., and the increase ratio is 30%.

[0092] Example Four

[0093] The method for improving the sidewall etching damage of AlGaInP red light Micro LED of the application further illustrates the technical solutions of the application, the reagents used in the examples are all of analytical purity, the equipment is a conventional equipment in the semiconductor manufacturing field, and the examples take 4-inch GaAs substrate AlGaInP epitaxial wafer as the processing object, oxalic acid Repair 50μm medium-sized pixels, the specific steps are as follows:

[0094] S1, epitaxial cleaning: acetone-ethanol mixed solution (volume ratio 1:1) ultrasonic cleaning 8min→isopropyl alcohol-methanol mixed solution (volume ratio 1:1) immersion 4min→ultra-pure water washing 4min→1500r / min spin-drying;

[0095] S2, patterned photolithography: coating positive photoresist, uniform coating speed 4000r / s (photoresist thickness 1.5μm)→ultraviolet exposure (wavelength 365nm, dose 80 )→development to form a hexagonal mask with a diameter of 50μm;

[0096] S3, ICP etching: upper electrode power 600W, lower electrode power 80W→gas flow 55sccm、 8sccm, Ar 8sccm→etching time 250s; SEM observation after etching: the sidewall damage layer depth is about 70nm;

[0097] S4, preparation of liquid medicine: oxalic acid and deionized water with a mass ratio of 3:1→30℃ water bath heating, magnetic stirring for 5min→adding 2% with a volume ratio of 0.9:1, stirring for 6min→cooling to 22℃;

[0098] S5, wet treatment: soaking time 70s, oscillation frequency 80 times / min;

[0099] S6, post-processing: ultra-pure water washing 50s→nitrogen blowing (pressure 0.15MPa);

[0100] S7, characterization: SEM (stage 40°, magnification 160000x) showed that the sidewall damage layer removal rate was 92%, and the surface roughness was 3.5 nm; TRPL test: photoluminescence peak intensity before repair 1900 a.u., after repair 2565 a.u., increase ratio 35%.

[0101] In the photoluminescence (PL) test, a.u. is the abbreviation of "arbitrary unit", which is a relative intensity unit commonly used in scientific research and industrial testing, not an absolute physical unit; the role of a.u. is to "eliminate the interference of experimental condition differences and clearly show the intensity change in the same system", as long as the test conditions are consistent, the relative comparison result based on a.u. is accurate and reliable, which can effectively verify the technical effect of "wet repair to improve the luminescence performance" in the present application.

[0102] Finally, it should be pointed out that the above is only the preferred embodiment of the present application and is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacement for some of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for improving sidewall etching damage of AlGaInP red Micro LED, characterized in that, The method comprises the following steps: S1, epitaxial cleaning: sequentially performing ultrasonic cleaning with an organic reagent, soaking in a polar solvent, and rinsing with deionized water on an AlGaInP epitaxial material, and then performing spin-drying treatment to obtain a clean epitaxial wafer; S2, patterned photolithography: coating a photoresist on the clean AlGaInP epitaxial surface, and performing exposure and development to form a patterned mask; S3, ICP dry etching: placing the AlGaInP epitaxial wafer with the patterned mask in an ICP etching machine, and performing etching by using a mixed gas containing a Cl-based gas and an inert gas to form a Micro LED pixel array; S4, wet repair solution preparation: mixing a weak acid and deionized water and heating and stirring until completely dissolved, then adding an oxidizing agent and stirring uniformly, and cooling to room temperature to obtain a wet repair solution; S5, side wall damage wet treatment: immersing the etched AlGaInP epitaxial wafer in the wet repair solution, and fully contacting the solution with the pixel side wall by oscillation to remove the etching damage layer by corrosion; S6, post-treatment: rinsing the epitaxial wafer after wet treatment with deionized water to remove residual solution, and then blowing dry by an inert gas; S7, effect characterization: observing the side wall morphology by an electron microscope, testing the luminescence performance by photoluminescence, and verifying the damage repair effect.

2. The method for improving etching damage of AlGaInP red light Micro LED sidewall according to claim 1, wherein, In step S1, the parameter range of epitaxial cleaning is: ultrasonic cleaning time of the organic reagent is 5-20 min, soaking time in the polar solvent is 3-8 min, and rinsing time with deionized water is 3-8 min; the organic reagent is at least one selected from acetone and ethanol, and the polar solvent is at least one selected from isopropanol and methanol.

3. The method for improving etching damage of AlGaInP red light Micro LED sidewall according to claim 1, wherein, In step S2, the specific operation of patterned photolithography includes: coating a positive or negative photoresist by using a spin coater, spin coater rotation speed is 2000-6000 r / s, and photoresist thickness is 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 etching damage of AlGaInP red light Micro LED sidewall according to claim 1, wherein, In step S3, the parameter range of ICP dry etching is: upper electrode power 500-900 W, lower electrode power 50-150 W; 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 auxiliary gas is selected from at least one of , , and the inert gas is selected from at least one of Ar and Ne.

5. The method for improving etch damage of AlGaInP red Micro LED sidewall according to claim 1, wherein, 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 etch damage of AlGaInP red Micro LED sidewall according to claim 1, wherein In step S5, the conditions of side wall damage wet treatment are: the immersion time of the epitaxial wafer in the solution is 20-150 s, 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 etching damage of AlGaInP red light Micro LED sidewall according to claim 1, wherein, In step S6, the specific requirements of post-treatment are: the rinsing time with deionized water is 40-80 s, and flowing deionized water is used during the rinsing process; the inert gas is at least one selected from nitrogen and argon, the gas purity is ≥99.9%, and the blowing dry pressure is 0.1-0.3 MPa.

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

9. The method for improving etching damage of AlGaInP red light Micro LED sidewall according to claim 8, wherein, After the wet treatment, the removal rate of the side wall etching damage layer of the AlGaInP red Micro LED is ≥90%, and the photoluminescence peak intensity is improved by ≥25%.

10. The method for improving etch damage of AlGaInP red Micro LED sidewall according to any one of claims 1-9, wherein, The method is suitable for AlGaInP red light Micro LED of different substrates and is directly compatible with a Micro LED mass production process.

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