Method for reducing power consumption of red micro-leds

Abstract

The application discloses a method for reducing power consumption of red light Micro LED, comprising: S1, wafer source preparation; S2, pretreatment cleaning; S3, photoetching molding; S4, residual glue removal; S5, oxide layer removal; S6, composite metal deposition; S7, glue removal and adhesion; S8, appearance screening; S9, annealing treatment; and S10, performance verification can be additionally added; the core is that a composite metal film layer containing Au, Ge and Ni is deposited in a metal deposition window by adopting a physical vapor deposition technology, and the Ni layer is located between the Au layer and the Ge layer; rapid annealing under a protective atmosphere is combined to inhibit Ge agglomeration and reduce the contact resistance of the N electrode and the n-type GaAs layer; the application takes into account low contact resistance and N-side light transmittance, is compatible with Si, sapphire and other substrates, has strong process adaptability, reduces power consumption, improves device reliability and batch yield, and is suitable for Mini / Micro LED display and other fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of Micro LED display, in particular to a method for reducing the power consumption of red Micro LED, especially for improving the ohmic contact performance between N electrode and n-type GaAs layer in vertical structure AlGaInP-based red Micro LED, by designing a composite metal film layer containing Ni and adapting the process, solving the problem of Ge agglomeration of traditional electrode, realizing effective reduction of LED power consumption, which can be widely applied in Mini / Micro LED display panel, vehicle-mounted display, wearable equipment and other fields. BACKGROUND

[0002] With the development of display technology towards "high resolution, high brightness, low power consumption", AlGaInP-based red Micro LED has become one of the core devices of Mini / Micro LED full-color display due to its stable emission wavelength (620-660nm), high quantum efficiency, long service life and other advantages; among them, vertical structure AlGaInP-based red Micro LED is considered to be the preferred architecture for high brightness display scenarios due to its large light emitting angle, strong current carrying capacity, excellent heat dissipation performance and other characteristics. Its typical vertical structure contains, from top to bottom: whole layer interconnection transparent electrode, N electrode, n-type GaAs layer, AlGaInP transition layer, quantum well (light emitting layer), p-type AlGaInP transition layer, GaP layer, transparent conductive layer (such as ITO), bonding metal layer and substrate (such as Si, sapphire).

[0003] In the preparation of vertical structure AlGaInP-based red Micro LED, the ohmic contact quality between N electrode and n-type GaAs layer directly determines the electrical performance and power consumption of the device; in the prior art, the industry generally uses Au-Ge binary metal system to prepare N electrode: after depositing AuGe film layer on the surface of n-type GaAs layer by physical vapor deposition (such as electron beam evaporation, magnetron sputtering), high temperature annealing is performed to make AuGe form eutectic liquid, and Ge element diffuses into n-type GaAs layer to improve local doping concentration, while Au and Ga form Au-Ga chemical bond, thereby reducing contact resistance, however, this process has the following difficult-to-solve technical defects:

[0004] 1. Abnormal increase of contact resistance caused by Ge agglomeration: during high temperature annealing process, the alloying reaction of Au and Ge is not complete, and Ge element is prone to agglomeration into balls (such as the attached Figure 1As shown, without Ni, obvious Ge agglomeration spots appear on the wafer surface. Agglomerated Ge particles can destroy the continuity of the electrode and GaAs interface, increase the contact resistance by 15%-30%, directly cause the LED operating voltage to rise by 0.2-0.3V, and ultimately increase the device power consumption by 18%-25%. At the same time, Ge agglomeration can also cause uneven current spreading, leading to local current congestion and increased heat production, further worsening power consumption and device reliability.

[0005] 2. Difficulty in balancing light transmittance and contact resistance: The N side (n-type GaAs layer side) of the AlGaInP-based red Micro LED is the main light emitting surface, and the N electrode metal film layer needs to consider both "low contact resistance" and "high light transmittance". If the existing AuGe electrode is thickened to reduce resistance, it will block more than 30% of the emitted light, resulting in a decrease in light efficiency. If the film layer is thinned to improve light transmittance, the contact resistance will skyrocket due to incomplete AuGe coverage, forming a "resistance-light transmittance" contradiction.

[0006] 3. Limitations of existing improvement technologies: Some related technologies attempt to add metal elements (such as Ni, Co) to the AuGe system to suppress agglomeration, but there are obvious shortcomings: for example, some patents only mention adding Ni but do not specify the specific position of the Ni layer (such as placing the Ni layer at the outermost or innermost layer, which cannot effectively block the Ge agglomeration path); some technologies do not optimize the annealing process parameters (such as annealing temperature lower than 320℃ leading to insufficient AuGe eutectic or higher than 380℃ leading to GaAs layer decomposition); some technologies ignore substrate compatibility, only designing processes for GaAs substrates, which cannot be compatible with mainstream substrates such as Si and sapphire, limiting the range of industrial applications.

[0007] 4. Poor process parameter coordination: In traditional processes, pre-treatment cleaning (such as using only a single solvent for cleaning), residue removal (such as chemical treatment excessively corroding the GaAs surface), and oxide layer removal (such as improper concentration of acidic solution) steps do not match the parameters of metal deposition and annealing processes, which not only cannot solve the Ge agglomeration problem, but also may lead to a decrease in ohmic contact stability, with a device batch yield of less than 70%.

[0008] In summary, the existing N electrode preparation process for AlGaInP-based red Micro LED has problems such as Ge agglomeration, difficulty in balancing resistance and light transmittance, poor process coordination, and low substrate compatibility, which cannot meet the application requirements of low power consumption and high reliability. Therefore, a technical solution that can solve the above problems from the whole process of "film layer design-process optimization-performance verification" is urgently needed. SUMMARY

[0009] The purpose of the present application is to overcome the technical defects existing in the preparation of the existing AlGaInP-based red Micro LED vertical structure, and specifically solve the following problems: after high-temperature annealing of the traditional AuGe electrode, Ge is easy to agglomerate into balls, resulting in increased contact resistance, uneven current expansion, and increased device power consumption; the N electrode metal film layer cannot balance the "low contact resistance" and "high light transmittance on the N side", and there is a performance contradiction; in the existing improvement technology adding Ni, the position of the Ni layer, the metal deposition parameters and the annealing process have poor synergy, and the effect of inhibiting agglomeration is limited; the process compatibility is low, cannot be compatible with multiple substrates such as Si and sapphire, and the pretreatment, residue removal and other steps are easy to damage the n-type GaAs layer, affecting the yield.

[0010] To solve the above technical problems, the technical scheme adopted by the present application is:

[0011] A method for reducing the power consumption of a red Micro LED, applied to an AlGaInP-based red Micro LED vertical structure containing an n-type GaAs layer, the vertical structure at least comprising an n-type GaAs layer, an N electrode in contact with the n-type GaAs layer, and a semiconductor functional layer and a substrate located below the n-type GaAs layer, the method comprising the following steps:

[0012] S1, wafer source preparation, selecting a bonded AlGaInP-based red Micro LED wafer, the top of the wafer being an n-type GaAs layer for forming an ohmic contact of an N electrode;

[0013] S2, pretreatment cleaning, performing a contaminant removal treatment on the surface of the wafer, comprising in sequence: ultrasonic cleaning with an organic solvent, immersion cleaning with a polar solvent, rinsing with deionized water, and finally drying;

[0014] S3, photoetching, coating a positive photoresist on the dried wafer surface and performing a uniform photoresist treatment to form a photoresist film with a predetermined thickness; exposing the photoresist film through a photoetching plate containing an electrode pattern, and then developing with a positive resist developer to form a metal deposition window of the N electrode;

[0015] S4, residue removal, using physical bombardment or chemical treatment to remove the photoresist bottom film remaining in the metal deposition window, to ensure that the subsequent metal film is in direct contact with the n-type GaAs layer;

[0016] S5, oxide layer removal, soaking the wafer in an acidic solution to remove the oxide layer formed on the surface of the n-type GaAs layer due to pretreatment;

[0017] S6, composite metal deposition, a composite metal film layer containing Au, Ge, and Ni is deposited in the metal deposition window by physical vapor deposition technology, and the Ni layer is located between the Au layer and the Ge layer in the composite metal film layer, for inhibiting the agglomeration of Ge in the subsequent annealing process;

[0018] S7, stripping and desorption, the wafer after metal deposition is placed in a stripping solution to strip the photoresist and excess metal in the unexposed area;

[0019] S8, appearance screening, the wafer surface is observed by an optical microscope to screen qualified wafers without residual photoresist and residual gold;

[0020] S9, annealing treatment, the qualified wafer is placed in an annealing device for rapid annealing in a protective atmosphere, so that the composite metal film layer and the n-type GaAs layer form an ohmic contact with low contact resistance.

[0021] In a preferred scheme, in step S2, the organic solvent is at least one selected from acetone, ethanol, and ethyl acetate, the ultrasonic cleaning time is 8-15 min, and the ultrasonic power is 250-400 W; the polar solvent is at least one selected from isopropanol and methanol, the soaking cleaning time is 8-15 min; and the drying method is nitrogen blowing or vacuum drying, and the nitrogen blowing is performed at a purity of ≥99.99%.

[0022] In a preferred scheme, in step S3, the spin coating speed of the positive photoresist is 4000-6500 rpm, the spin coating time is 30-60 s, the formed photoresist film has a thickness of 4-7 μm; the electrode pattern at least contains a circular ring pattern for testing the ohmic contact performance, the exposure time is 15-30 s, the exposure gap is 15-30 μm; and the developing time is 3-6 min, and the wafer is continuously oscillated during the developing process to ensure sufficient developing.

[0023] In a preferred scheme, in step S4, the physical bombardment is plasma bombardment, the power of the plasma bombardment is 80-150 W, the oxygen flow rate is 15-30 sccm, and the processing time is 25-40 s; and the chemical treatment is soaking with an organic amine reagent for 1-5 min.

[0024] In a preferred scheme, in step S5, the acid solution is selected from an HCl solution, , a solution or a mixed solution thereof, the concentration of the acid solution is 25%-45% by volume fraction, the soaking time is 40-80 s, and the soaking environment temperature is 18-35 °C.

[0025] Preferably, in step S6, the physical vapor deposition technique is selected from at least one of electron beam evaporation, magnetron sputtering, and thermal evaporation; the structure of the composite metal film layer is "Au layer-Ge layer-Ni layer-Au layer-Ge layer", "Au layer-Ni layer-Ge layer-Au layer-Ge layer", or "Au layer-Ge layer-Ni layer-Ge layer-Au layer"; the deposition rate of each metal layer is: 0.5-2 Å / s for the Au layer, 2-5 Å / s for the Ge layer, and 2-3.5 Å / s for the Ni layer; and the thickness of each metal layer is: 20-120 Å for the Au layer, 20-120 Å for the Ge layer, and 20-45 Å for the Ni layer.

[0026] Preferably, in step S7, the main component of the stripping solution is N-methyl pyrrolidone, dimethyl sulfoxide, or a mixture thereof, the purity of the stripping solution is ≥98%, the temperature of the stripping solution is 80-100℃, the soaking time is 20-40 min, and the wafer is oscillated up and down every 10-25 s during the soaking process.

[0027] Preferably, in step S9, the protective atmosphere is selected from nitrogen, argon, or a mixture thereof, and the purity of the protective atmosphere is ≥99.99%; the temperature of the rapid annealing is 320-390℃, the heating rate is 8-18℃ / s, the holding time is 4-8 min, and the temperature is cooled to room temperature after annealing.

[0028] Preferably, in step S1, the semiconductor functional layer of the AlGaInP-based red Micro LED vertical structure at least includes an AlGaInP transition layer, a quantum well, a p-type semiconductor layer, and a transparent conductive layer; the substrate is a Si substrate, a sapphire substrate, or a GaAs substrate; the doping concentration of the n-type GaAs layer is .

[0029] Preferably, the method further includes S10: performance verification, which includes: S10-1, IV testing, using a direct current source table, the test voltage range is -15~15V, the limiting current is 0.5~1.5A, and the IV curve is required to be linear; S10-2, microscopic observation, using a 50-200 times optical microscope or a metallographic microscope, and the composite metal film layer surface is required to have no Ge agglomeration phenomenon, and the film uniformity meets the preset standard.

[0030] Thanks to the use of the above technical solutions, the present application has the following beneficial effects compared with the prior art:

[0031] 1. Completely suppresses Ge agglomeration: By placing the Ni layer between the Au layer and the Ge layer, combined with optimized deposition rate and annealing parameters, the Ge agglomeration path can be completely blocked; microscopic observation shows that there are no Ge agglomeration spots on the surface of the composite metal film layer, and the contact resistance is reduced by 25%-40% compared with the traditional AuGe electrode.

[0032] 2. Reduce device power consumption: the reduction of contact resistance makes the LED operating voltage drop 0.15-0.25V, the device power consumption reduces 12%-18%, and the current expansion uniformity improves more than 30%, the local heat production reduces, and the device life extends 20%.

[0033] 3. Consider light transmittance and reliability: the total thickness of the composite metal film layer is controlled at 200-350Å, the N-side light transmittance is maintained above 80%, and the introduction of the Ni layer makes the bonding force between the metal film layer and the GaAs layer improve 15%-25%.

[0034] 4. Strong process compatibility: support electron beam evaporation, magnetron sputtering and other deposition technologies, compatible with Si, sapphire, GaAs and other substrates, the wafer batch yield is improved from 70% to more than 90% with mild pretreatment and residue removal parameters.

[0035] 5. Low industrialization cost: the metals (Au, Ge, Ni) used are common materials in the semiconductor industry, no special equipment needs to be added, and can be directly integrated into the existing Micro LED production line, the unit device preparation cost only increases 5%-8%, and the cost performance advantage is significant. BRIEF DESCRIPTION OF DRAWINGS

[0036] 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.

[0037] Figure 1 is a microscope picture of the wafer surface of the traditional AuGe electrode;

[0038] Figure 2 is a microscope picture of the wafer surface of the composite metal electrode using the technology of the present application;

[0039] Figure 3 is a flow chart of the method for reducing the power consumption of red Micro LED according to the first embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the personnel in the technical field better understand the scheme of the present application, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination 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 the person skilled in the art without creative labor should belong to the scope of protection of the present application.

[0041] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to be used to describe 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 have to be limited to only 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.

[0042] 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 used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0043] Also, in addition to indicating 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 attachment relationship or connection relationship in some cases. For the person skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.

[0044] 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 the person skilled in the art, the specific meaning of the above-mentioned terms in the present application can be understood according to the specific circumstances.

[0045] 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.

[0046] Example 1

[0047] Please see Figure 2 and 3 The present invention provides a method for reducing the power consumption of red Micro LEDs. The core of this method lies in designing an "Au-Ge-Ni" composite metal film (with a Ni layer located between the Au and Ge layers, blocking the Ge agglomeration path) and matching it with a fully optimized process of "pretreatment-photolithography-metal deposition-annealing," while also being compatible with multiple substrate types. The specific technical solution is as follows:

[0048] S1, Source Preparation:

[0049] Select an AlGaInP-based red micro LED wafer that has been bonded. The top of the wafer is an n-type GaAs layer (doping concentration of 0.5%) used to form the N-electrode ohmic contact. High doping can reduce the contact barrier through the tunneling effect); the vertical structure of the wafer from bottom to top is as follows: substrate (Si substrate, sapphire substrate or GaAs substrate), bonding metal layer (such as AuSn, CuSn alloy), transparent conductive layer (such as p-type ITO, thickness 100-200nm), GaP layer (thickness 50-100nm, used for transition between p-type AlGaInP and ITO), p-type AlGaInP transition layer (thickness 200-300nm), quantum well (InGaP / AlGaInP multiple quantum wells, periodic 5-8 layers), n-type AlGaInP transition layer (thickness 200-300nm), n-type GaAs layer (thickness 100-200nm).

[0050] S2, Pre-treatment cleaning:

[0051] A multi-step contaminant removal process is performed on the wafer surface to ensure good adhesion between subsequent metal deposition and the GaAs layer. This includes:

[0052] Organic solvent ultrasonic cleaning: Select at least one of acetone, ethanol or ethyl acetate (acetone has a strong dissolving power for organic contaminants, and ethanol has a good cleaning effect on residual grease). Place the wafer in the solvent and use 250-400W power for ultrasonic cleaning for 8-15 minutes (e.g., acetone ultrasonic power of 300W for 10 minutes can effectively remove photoresist residue and cutting oil stains).

[0053] Polar solvent immersion cleaning: Transfer the ultrasonically cleaned wafer to isopropanol or methanol and immerse it at room temperature for 8-15 minutes (isopropanol can dissolve residual organic solvents while avoiding oxidation of the GaAs layer).

[0054] Rinse and dry with deionized water: rinse the wafer with deionized water with a resistivity of ≥ 18 M for 1-3 min to remove solvent residues; then dry with nitrogen (nitrogen purity ≥ 99.99%, to avoid air oxidation of the GaAs surface) or vacuum drying (vacuum degree ≤ Pa, drying temperature 40-60°C).

[0055] S3, photoetching:

[0056] Form a metal deposition window for the N electrode on the wafer surface, specifically including:

[0057] Coat the wafer surface after drying with a positive photoresist (such as AZ 6130, Shipley 1813, with high resolution and fast developing speed), set the spin coater speed to 4000-6500 rpm for 30-60 s, to form a photoresist film with a thickness of 4-7 μm (a film that is too thin is prone to overdevelopment, and a film that is too thick is prone to residual glue);

[0058] Exposure: place the wafer after coating in an ultraviolet photoetching instrument (such as SUSS MA8, Canon PLA-501F) and align it with a photoetching plate containing an electrode pattern - the electrode pattern at least includes a CTLM ring pattern (inner ring diameter 50-200 μm, outer ring diameter 100-300 μm) for testing ohmic contact performance and an electrode pattern for actual devices, set the exposure time to 15-30 s and the exposure gap to 15-30 μm (an exposure gap that is too small is prone to electrode short circuit, and an exposure gap that is too large is prone to wasting wafer area);

[0059] Development: place the wafer after exposure in a positive photoresist developing solution (such as AZ 300MIF, CD-26) for 3-6 min, and oscillate the wafer at a frequency of 1 time / 4-6 s during the developing time (to ensure that the exposed area of the photoresist is fully dissolved, to form a metal deposition window with a neat edge).

[0060] S4, residual glue removal:

[0061] Remove the residual photoresist bottom film in the metal deposition window (a 10-50 nm thick bottom film is prone to remaining after development, and if not removed, will result in poor adhesion of the metal film and an increased contact resistance), specifically using one of the following two methods:

[0062] Physical bombardment (plasma bombardment): preferably plasma bombardment (the plasma bombardment can react with the carbon and hydrogen components of the photoresist to form , , ​(No residue) Set the power to 80-150W, oxygen flow rate to 15-30sccm, and treatment time to 25-40s (e.g., 100W power, 20sccm flow rate, and 30s time can completely remove the bottom film without damaging the GaAs surface).

[0063] Chemical treatment: Immerse in organic amine reagents (such as tetramethylammonium hydroxide solution, diethylamine) for 1-5 minutes (organic amines can gently dissolve the photoresist substrate and avoid acidic reagents from corroding GaAs).

[0064] S5, Oxide layer removal:

[0065] After the residual adhesive is removed, gallium oxide is easily formed on the surface of the n-type GaAs layer. ), arsenic oxide ( The oxide layer (5-10 nm thick) blocks the electrical contact between the metal and GaAs and needs to be removed by soaking in an acidic solution.

[0066] The acidic solution is selected from HCl solution. Solution Solution or a mixture thereof (HCl to) Strong dissolving power Can inhibit (re-deposition);

[0067] Solution concentrations are defined as 25%-45% by volume (e.g., 36% HCl solution, 30%...). The solution is used for soaking for 40-80 seconds at an ambient temperature of 18-35℃ (too high a temperature can lead to over-etching of the GaAs layer, while too low a temperature will result in incomplete removal of the oxide layer).

[0068] S6, composite metal deposition:

[0069] A composite metal film containing Au, Ge, and Ni was deposited within a metal deposition window using physical vapor deposition (the Ni layer is located between the Au and Ge layers; the high alloying ability of N with Au and Ge and its low surface tension inhibit Ge agglomeration). Specific parameters are as follows:

[0070] Deposition technology: selected from at least one of electron beam evaporation (high film purity, thickness control accuracy ±1Å), magnetron sputtering (strong film adhesion), and thermal evaporation (low cost, suitable for mass production);

[0071] Membrane structure: Options include “Au layer-Ge layer-Ni layer-Au layer-Ge layer”, “Au layer-Ni layer-Ge layer-Au layer-Ge layer” or “Au layer-Ge layer-Ni layer-Ge layer-Au layer” (preferably “Au-Ge-Ni-Au-Ge” structure, where the Ni layer is in the middle and can react with the upper and lower Ge layers simultaneously, maximizing the inhibition of aggregation).

[0072] Deposition rate: Au layer 0.5-2Å / s (too fast will cause the film to be loose, too slow efficiency is low), Ge layer 2-5Å / s, Ni layer 2-3.5Å / s;

[0073] Film thickness: Au layer thickness 20-120Å (lower Au layer 20-40Å, for the combination with GaAs; upper Au layer 80-120Å, for the protection of the film), Ge layer thickness 20-120Å (to ensure that the amount of Ge diffusion is sufficient to reduce the resistance), Ni layer thickness 20-45Å (too thick will block the light, too thin can not inhibit the reunion).

[0074] S7, adhesive detachment:

[0075] Peel off the photoresist and excess metal in the unexposed area, and ensure that only the metal deposition window retains the composite metal film:

[0076] Stripping solution: the main components are N-methyl pyrrolidone (NMP, strong solubility of photoresist), dimethyl sulfoxide (DMSO, which can improve the stripping speed) or their mixture, purity ≥98% (impurities will cause metal film pollution);

[0077] Stripping parameters: stripping solution temperature 80-100℃ (temperature rise can accelerate the dissolution of photoresist), soaking time 20-40min, during which the wafer is oscillated up and down every 10-25s (amplitude 4-6cm, to ensure that the excess metal is completely peeled off).

[0078] S8, appearance screening:

[0079] Observe the wafer surface by optical microscope (magnification 50-200 times) to screen qualified wafers:

[0080] Qualified standard: no residual glue, no residual gold in the metal deposition window (residual glue will cause the electrode to be open, residual gold will cause the electrode to be short-circuited), no scratches, no film peeling off on the composite metal film;

[0081] Unqualified treatment: if there is residual glue / residual gold, return to step S2 for re-cleaning; if the film peels off, return to step S6 for re-deposition.

[0082] S9, annealing treatment:

[0083] Forming ohmic contact with low contact resistance between the composite metal film and the n-type GaAs layer by rapid annealing, while inhibiting Ge reunion:

[0084] Protective atmosphere: selected from nitrogen, argon or their mixture (nitrogen has low cost, argon is more inert), purity ≥99.99% (to avoid metal film oxidation or GaAs layer decomposition);

[0085] Annealing parameters: annealing temperature 320-390℃ (AuGe cannot be fully eutectic below 320℃, GaAs is easy to decompose above 390℃), heating rate 8-18℃ / s (fast heating can shorten the Ge agglomeration time), holding time 4-8min (to ensure that Ge diffuses fully and does not agglomerate);

[0086] Cooling method: naturally cool to room temperature (18-35℃) after annealing, avoid rapid cooling leading to film stress cracking.

[0087] S10, performance verification:

[0088] Test the performance of the annealed wafer to ensure that it meets the low power consumption requirement:

[0089] S10-1: IV test: use a direct current source meter (such as Keithley 2400, Agilent B2902A), connect the positive and negative probes to the inner and outer rings of the CTLM ring respectively, test the voltage range -15~15V, limit the current 0.5~1.5A, require the IV curve to be linear (linearity≥0.99, prove ohmic contact), contact resistance≤0.03 ;

[0090] S10-2: microscopic observation: use a 50-200x optical microscope or metallographic microscope (such as Olympus BX53) to observe the surface of the composite metal film, require no Ge agglomeration (such as the film layer is flat without spots as shown in the attached Figure 2 , film uniformity deviation≤5% (test the thickness of different areas by a film thickness meter, deviation=(maximum thickness-minimum thickness) / average thickness x 100%).

[0091] Example two

[0092] A method for reducing the power consumption of red Micro LED, based on Si substrate AlGaInP-based red Micro LED, comprising the following steps:

[0093] S1, wafer source preparation:

[0094] Select a 4-inch Si substrate AlGaInP-based red Micro LED bonding wafer, the n-type GaAs layer has a doping concentration of , vertical structure (from bottom to top): Si substrate (thickness 500μm)→ AuSn bonding layer (thickness 500nm)→ p-type ITO (thickness 150nm)→ GaP layer (thickness 80nm)→ p-type AlGaInP transition layer (thickness 250nm)→ InGaP / AlGaInP quantum well (6 periods)→ n-type AlGaInP transition layer (thickness 250nm→ n-type GaAs layer (thickness 150nm).

[0095] S2, pre-cleaning:

[0096] Organic solvent: acetone, ultrasonic power 300 W, time 10 min;

[0097] Polar solvent: isopropanol, room temperature soaking 10 min;

[0098] Deionized water rinsing 2 min, nitrogen (purity 99.999%) blowing dry.

[0099] S3, photo-etching:

[0100] Positive photoresist: AZ 6130, spin-coating speed 5000 rpm, time 40 s, film thickness 5 μm;

[0101] Exposure: SUSS MA8 photo-etching instrument, CTLM circle pattern (inner circle 100 μm, outer circle 200 μm), exposure time 20 s, gap 20 μm;

[0102] Developing solution: AZ 300MIF, developing time 4 min, oscillation frequency 1 time / 5 s.

[0103] S4, photoresist removing:

[0104] Plasma bombardment: power 100 W, oxygen flow 20 sccm, time 30 s, vacuum degree Pa.

[0105] S5, oxide layer removing:

[0106] 36% HCl solution (volume fraction), room temperature soaking 60 s.

[0107] S6, composite metal deposition:

[0108] Deposition technique: electron beam evaporation, vacuum degree Pa;

[0109] Film structure: Au layer (30 Å)-Ge layer (30 Å)-Ni layer (30 Å)-Au layer (100 Å)-Ge layer (100 Å);

[0110] Deposition rate: Au layer 1 Å / s, Ge layer 3 Å / s, Ni layer 2.5 Å / s.

[0111] S7, photoresist removing:

[0112] NMP photoresist removing solution (purity 99.5%), temperature 90 °C, soaking 30 min, oscillating every 15 s (amplitude 5 cm).

[0113] S8, appearance screening:

[0114] 00 optical microscope observation, no residual glue, residual gold, no scratch on the film layer.

[0115] S9, annealing treatment:

[0116] Nitrogen protection (purity 99.99%), annealing temperature 350℃, heating rate 11℃ / s, holding for 5min, natural cooling to 25℃.

[0117] S10, performance verification:

[0118] IV test: DC source table Keithley 2400, voltage-10~10V, limiting current 1A, IV curve linearity 0.995, contact resistance 0.022 ;

[0119] Microscopic observation: 200 times metallographic microscope, no Ge agglomeration, film layer uniformity deviation 3.2%.

[0120] Example three

[0121] A method for reducing the power consumption of red Micro LED, AlGaInP-based red Micro LED based on sapphire substrate, comprising the following steps:

[0122] 1, difference parameters (compared with example two)

[0123] S1, the substrate is sapphire substrate (thickness 400μm), n-type GaAs layer doping concentration ;

[0124] S2, the organic solvent is ethanol, the ultrasonic power is 320W, the time is 9min; the polar solvent is methanol, and the soaking time is 11min;

[0125] S6, the deposition technology is magnetron sputtering, the film layer structure is "Au layer (25Å)-Ni layer (25Å)-Ge layer (25Å)-Au layer (90Å)-Ge layer (90Å)", the deposition rate is: Au layer 0.8Å / s, Ge layer 2.5Å / s, Ni layer 2.2Å / s;

[0126] S9, annealing temperature 330℃, heating rate 9℃ / s, holding for 4.5min;

[0127] S10, IV curve linearity 0.993, contact resistance 0.025 , film layer uniformity deviation 4.1%.

[0128] 2, effect

[0129] The sapphire substrate has good compatibility, low contact resistance, no Ge agglomeration, and the LED operating voltage is 2.0V, with power consumption reduced by 14% compared to traditional processes.

[0130] Example 4

[0131] The present invention discloses a method for reducing the power consumption of red Micro LEDs, based on AlGaInP-based red Micro LEDs on GaAs substrates, comprising the following steps:

[0132] 1. Difference parameters (compared to Example 2)

[0133] S1, the substrate is a GaAs substrate (thickness 350μm), and the n-type GaAs layer doping concentration is... ;

[0134] S5, acidic solution is 30%. Soak in a mixture of 36% HCl (volume ratio 1:1) for 50 seconds.

[0135] S6, the film structure is “Au layer (35Å)-Ge layer (35Å)-Ni layer (35Å)-Ge layer (35Å)-Au layer (110Å)”, with a Ni layer thickness of 35Å;

[0136] S9, annealing temperature 370℃, heating rate 13℃ / s, holding time 5.5min;

[0137] S10, IV curve linearity 0.997, contact resistance 0.019 The film uniformity deviation was 2.8%.

[0138] 2. Effects

[0139] The GaAs substrate has the lowest contact resistance, the LED operating voltage is 1.95V, the power consumption is reduced by 18%, and the light transmittance is 85%, making it suitable for high-brightness display scenarios.

[0140] Example effect verification:

[0141] The key performance of the above embodiments was compared with that of the conventional AuGe electrode process (control group), and the results are shown in the table below:

[0142]

[0143] As shown in the table above, the technical solution of the present invention is significantly superior to the traditional process in terms of key indicators such as contact resistance, power consumption, light transmittance, and yield. It is also compatible with different substrates and can meet diverse industrialization needs.

[0144] Finally, it should be noted that the above is only the preferred embodiment of the present application, and is not intended to limit the present application, although the foregoing embodiments of the present application are described in detail, for those skilled in the art, it can still be modified to the technical solutions described in the foregoing embodiments, or part of the technical features are equivalent to replace, as long as within the spirit and principles of the present application, any modification, equivalent replacement, improvement, etc. made, should be included within the scope of the present application.

Claims

1. A method for reducing power consumption of a red Micro LED, characterized in that, The method is applied to an AlGaInP-based red Micro LED vertical structure comprising an n-type GaAs layer, and at least comprises an n-type GaAs layer, an N electrode in contact with the n-type GaAs layer, and a semiconductor functional layer and a substrate below the n-type GaAs layer, and the method comprises the following steps: S1, wafer source preparation, selecting a bonded AlGaInP-based red Micro LED wafer, the top of the wafer is an n-type GaAs layer for forming an N electrode ohmic contact; S2, pretreatment cleaning, the wafer surface is subjected to a contaminant removal treatment, which comprises the following steps in sequence: ultrasonic cleaning with an organic solvent, immersion cleaning with a polar solvent, deionized water rinsing, and finally drying; S3, photoetching, coating a positive photoresist on the dried wafer surface and performing a uniform coating treatment to form a photoresist film with a preset thickness; exposing the photoresist film through a photoetching plate containing an electrode pattern, and then developing the photoresist film with a positive photoresist developer to form a metal deposition window of the N electrode; S4, photoresist removal, removing the residual photoresist film in the metal deposition window by physical bombardment or chemical treatment to ensure that the subsequent metal film is in direct contact with the n-type GaAs layer; S5, oxide layer removal, immersing the wafer in an acidic solution to remove the oxide layer formed on the surface of the n-type GaAs layer during the pretreatment; S6, composite metal deposition, depositing a composite metal film layer containing Au, Ge and Ni in the metal deposition window by physical vapor deposition technology, the Ni layer is between the Au layer and the Ge layer in the composite metal film layer, and is used to inhibit the agglomeration of Ge during the subsequent annealing process; S7, photoresist stripping, placing the wafer after metal deposition in a photoresist stripping solution to strip the photoresist and excess metal in the unexposed area; S8, appearance screening, observing the wafer surface through an optical microscope to screen qualified wafers without residual photoresist and residual metal; S9, annealing treatment, placing the qualified wafer in an annealing device to perform rapid annealing in a protective atmosphere to form an ohmic contact with low contact resistance between the composite metal film layer and the n-type GaAs layer.

2. The method for reducing power consumption of red light Micro LED according to claim 1, wherein, In step S2, the organic solvent is selected from at least one of acetone, ethanol, and ethyl acetate, the ultrasonic cleaning time is 8-15 min, and the ultrasonic power is 250-400 W; the polar solvent is selected from at least one of isopropyl alcohol and methanol, the immersion cleaning time is 8-15 min; the drying method is nitrogen blowing or vacuum drying, and the nitrogen purity is ≥99.99% when nitrogen blowing.

3. The method for reducing power consumption of red light Micro LED according to claim 1, wherein, In step S3, the rotation speed of the positive photoresist during the uniform coating treatment is 4000-6500 rpm, the uniform coating time is 30-60 s, the thickness of the photoresist film formed is 4-7 μm; the electrode pattern at least contains a circular ring pattern for testing the ohmic contact performance, the exposure time is 15-30 s, the exposure gap is 15-30 μm; the developing time is 3-6 min, and the wafer is continuously oscillated during the developing process to ensure sufficient development.

4. The method for reducing power consumption of red light Micro LED according to claim 1, wherein, In step S4, the physical bombardment is plasma bombardment, The power of the plasma bombardment is 80-150 W, the oxygen flow rate is 15-30 sccm, and the processing time is 25-40 s; the chemical treatment is soaking with an organic amine reagent, and the soaking time is 1-5 min.

5. The method for reducing red light Micro LED power consumption according to claim 1, wherein, In step S5, the acidic solution is selected from a HCl solution, , or a mixed solution thereof, the concentration of the acidic solution is 25%-45% by volume fraction, the soaking time is 40-80s, and the soaking environment temperature is 18-35℃.

6. The method for reducing red light Micro LED power consumption according to claim 1, wherein, In step S6, the physical vapor deposition technique is selected from at least one of electron beam evaporation, magnetron sputtering, and thermal evaporation; the structure of the composite metal film layer is "Au layer-Ge layer-Ni layer-Au layer-Ge layer", "Au layer-Ni layer-Ge layer-Au layer-Ge layer", or "Au layer-Ge layer-Ni layer-Ge layer-Au layer"; the deposition rate of each metal layer is: 0.5-2 Å / s for the Au layer, 2-5 Å / s for the Ge layer, and 2-3.5 Å / s for the Ni layer; and the thickness of each metal layer is: 20-120 Å for the Au layer, 20-120 Å for the Ge layer, and 20-45 Å for the Ni layer.

7. The method of claim 1, wherein, In step S7, the main component of the stripping solution is N-methyl pyrrolidone, dimethyl sulfoxide, or a mixture thereof, the purity of the stripping solution is ≥98%, the temperature of the stripping solution is 80-100°C, the soaking time is 20-40 min, and the wafer is oscillated up and down every 10-25 s during the soaking process.

8. The method for reducing red light Micro LED power consumption according to claim 1, wherein, In step S9, the protective atmosphere is selected from nitrogen, argon, or a mixture thereof, and the purity of the protective atmosphere is ≥99.99%; the temperature of the rapid annealing is 320-390°C, the heating rate is 8-18°C / s, the holding time is 4-8 min, and the wafer is cooled to room temperature after annealing.

9. The method of claim 1, wherein, In step S1, the semiconductor functional layer of the AlGaInP-based red Micro LED vertical structure at least includes an AlGaInP transition layer, a quantum well, a p-type semiconductor layer, and a transparent conductive layer; the substrate is a Si substrate, a sapphire substrate, or a GaAs substrate; the doping concentration of the n-type GaAs layer is .

10. The method of claim 1, wherein, S10: performance verification, which includes: S10-1, IV test, using a direct current source table, the test voltage range is -15-15 V, the limiting current is 0.5-1.5 A, and the IV curve is required to be linear; S10-2, microscopic observation, using a 50-200 times optical microscope or a metallographic microscope, and the composite metal film layer surface is required to have no Ge agglomeration phenomenon, and the film layer uniformity meets the preset standard.

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