A method for fabricating a low-crosstalk Micro LED matrix headlight

Abstract

The application discloses a preparation method of a low-crosstalk Micro LED matrix headlamp, comprising the following steps: S1, pretreatment of a blue light Micro LED chip; S2, photolithography process treatment; S3, coating of a silica gel fluorescent powder mixture; S4, vacuum standing and high-temperature curing; S5, high-precision grinding and thinning; S6, removal of photoresist; and optionally S7, preparation of a light-blocking structure; through the steps of definition of a fluorescent powder area by photolithography, vacuum settlement thickness control, step-by-step grinding and optimization of a light-blocking structure, the problems of high crosstalk, poor uniformity of a fluorescent powder layer and low yield in the prior art are solved, the crosstalk rate between pixels is less than or equal to 5%, the thickness deviation of the fluorescent powder layer is less than or equal to 2.5 microns, and the chip preparation yield is greater than or equal to 90%; the weather resistance of the passivation layer, the electrode and the silica gel can be optimized, the special scenes such as salt mist resistance of a ship are adapted, and the service life is greater than or equal to 5 years; the process is compatible with the existing production line and is suitable for preparation of the Micro LED matrix headlamp in multiple scenes such as automobiles and ships.

Description

Technical Field

[0001] This invention relates to the field of Micro LED display and lighting technology, specifically to a method for fabricating a low-crosstalk Micro LED matrix headlight suitable for automotive, smart lighting and other scenarios. It focuses on the precise control of phosphor layers and the integration process of light-blocking structures to improve the resolution and light control accuracy of the matrix headlight. Background Technology

[0002] As automotive lighting upgrades towards "intelligent interaction + high resolution," Micro LED matrix headlights have become the mainstream development direction due to their advantages such as pixel-level dimming, fast response speed, and long lifespan. However, existing manufacturing processes have the following core problems:

[0003] 1. Severe crosstalk: Traditional phosphor coating uses the "overall spraying + curing" method. The phosphor diffuses between pixels, causing light crosstalk between adjacent LED pixels and affecting the accuracy of lighting zones.

[0004] 2. Poor process compatibility: The light-blocking structure mostly adopts the process of "sapphire substrate grooving + filling light-blocking material", which requires the introduction of additional deep etching equipment and conflicts with the bonding process of CMOS driver chip, resulting in the yield rate not meeting the requirements.

[0005] 3. Insufficient uniformity of phosphor layer: Because phosphor has a higher density than silicone, it is prone to sedimentation and aggregation, resulting in large deviations in phosphor thickness within the same pixel and causing uneven brightness.

[0006] 4. High risk of chip damage: If the process parameters are not properly controlled during the thinning and polishing process (such as excessive feed speed or insufficient grinding wheel mesh), it can easily lead to substrate cracking or phosphor layer peeling, further reducing the yield.

[0007] Therefore, there is an urgent need for a Micro LED matrix headlight manufacturing method that combines "low crosstalk, high yield, and simplified process" to solve the pain points of existing technologies. Summary of the Invention

[0008] The purpose of this invention is to provide a method for fabricating a low-crosstalk Micro LED matrix headlight. By combining the processes of "photolithography defining phosphor regions + vacuum deposition for thickness control + step-by-step grinding + optional light-blocking structure", the method achieves the following results: inter-pixel crosstalk rate ≤5%; phosphor layer thickness deviation ≤2.5μm; brightness uniformity ≥90%; chip fabrication yield ≥90%; and the process is compatible with existing CMOS driver chip bonding technology, thereby reducing production costs.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0010] A method for fabricating a low-crosstalk Micro LED matrix headlight includes the following steps:

[0011] S1, Blue Micro LED Chip Pre-processing: Blue Micro LED chips are prepared using mature processes, specifically including eutectic bonding of the substrate and the CMOS driver chip, thinning of the bonded composite structure, forming independent LED pixels through etching, and then completing the electrode and passivation layer preparation through coating; the LED pixels are individually lit and zoned display controlled by the CMOS driver chip.

[0012] S2, Photolithography Processing: The blue Micro LED chip prepared in step S1 is subjected to photolithography and development to expose the light-emitting area of ​​the chip and cover the non-light-emitting area with photoresist; the thickness of the photoresist is determined by the target thickness of the phosphor layer required in the subsequent process, and the photolithography and development resolution is ≥1μm.

[0013] S3, Coating the silicone phosphor mixture: Mix silicone and phosphor and degas under vacuum to obtain a uniform silicone phosphor mixture; Apply the mixture to the surface of the blue Micro LED chip that has undergone photolithography in step S2 by spin coating, spraying or scraping.

[0014] S4, Vacuum settling and high-temperature curing: The chip coated in step S3 is placed in a vacuum environment of -0.07MPa to -0.13MPa for 8 to 14 hours until the thickness of the deposited layer formed by the phosphor settling due to density difference is greater than the thickness of the photoresist in step S2; after settling, the chip is subjected to high-temperature curing treatment to completely set the silicone, and the degree of crosslinking of the cured silicone is ≥90%;

[0015] S5, High-precision grinding and thinning: The chip after curing in step S4 is ground and thinned using a grinding wheel. The total thickness deviation during the grinding process is controlled to be ≤2.5μm and the surface roughness is ≤0.25μm. The grinding endpoint is to expose the photoresist in step S2, or when the photoresist thickness meets the requirements, the photoresist is partially removed to achieve the set thickness of the phosphor layer.

[0016] S6, Photoresist Removal: Using a photoresist remover that is non-corrosive and non-peeling to silicone and phosphor, residual photoresist in the chip electrode area and non-light-emitting area is removed to obtain a prototype of a white Micro LED chip.

[0017] In a preferred embodiment, in step S1, the thinning process employs a combination of mechanical grinding and chemical mechanical polishing, resulting in a substrate thickness of 35 μm to 125 μm after thinning. The etching process is selected from inductively coupled plasma etching, reactive ion etching, or deep reactive ion etching, with an etching depth of 1.2 μm to 6.5 μm, ensuring the integrity of the current limiting layer, active area, and contact layer structure of the LED pixel.

[0018] In a preferred embodiment, in step S1, the coating process is selected from electron beam evaporation, magnetron sputtering, or thermal evaporation; the prepared electrode layer is a double-layer metal structure, wherein the double-layer metal structure is selected from Cr / Au, Ti / Au, Ni / Au, or Al / Ni / Au, wherein the thickness of the bottom metal layer (Cr, Ti, or Ni) is 35 nm to 65 nm, and the thickness of the top metal layer (Au or Ni / Au) is 380 nm to 620 nm; the passivation layer uses... , or The thickness ranges from 100nm to 500nm.

[0019] In a preferred embodiment, the photolithography process in step S2 can be implemented in any of the following ways:

[0020] (1) All LED pixels in the light-emitting area of ​​the blue Micro LED chip are taken as the whole exposed area, while the non-light-emitting area, edge and electrode area are completely covered by photoresist;

[0021] (2) A photoresist isolation structure is formed between adjacent LED pixels in the light-emitting area by photolithography, so that each LED pixel is exposed independently. The space for filling the functional structure is reserved by removing the isolation structure.

[0022] In a preferred embodiment, in step S3, the performance parameters of the silicone rubber satisfy the following: Shore hardness ≥ 32D, transmittance of 1mm thickness ≥ 90% at 450nm wavelength, and viscosity 1800m. up to 3200m The phosphor is selected from... , Alternatively, quantum dot phosphors can be used, with a particle size of 1 / 5 to 1 / 3 of the LED pixel diameter and a particle size distribution deviation of ≤25%, ensuring dense filling without obvious gaps.

[0023] In a preferred embodiment, in step S5, the grinding wheel has a mesh size ≥ 900; the feed speed during the grinding process is controlled to be 0.08 μm / s to 0.35 μm / s, and a step-by-step grinding method is adopted, with rough grinding removing 60%-80% of the total thickness, and fine grinding controlling the surface roughness to ≤ 0.1 μm, to avoid scratches on the chip surface or peeling off of the phosphor layer.

[0024] In a preferred embodiment, in step S6, the adhesive remover is selected from any of the following:

[0025] (1) Organic degumming solution: acetone, ethanol, ethyl acetate or N-methylpyrrolidone, treatment temperature is 25-60℃, treatment time is 5-30min;

[0026] (2) Inorganic degumming solution: a sulfuric acid-hydrogen peroxide mixed solution with a volume ratio of 1.5:1 to 4.5:1, or a phosphoric acid-nitric acid mixed solution with a volume ratio of 3:1 to 5:1, with a treatment temperature of 55-85℃ and a treatment time of 3-20 min;

[0027] After all adhesive stripping treatments, the chip surface was cleaned with deionized water and then dried.

[0028] A preferred embodiment further includes step S7, fabrication of the light-blocking structure; step S7 specifically involves: performing a second photolithography on the chip obtained in step S6, covering the electrodes and non-light-emitting areas with photoresist, exposing the pixel gaps in the light-emitting areas; filling the exposed pixel gaps with a mixture of silicone and titanium dioxide using spin coating or dispensing, and repeating the grinding process of step S5 after curing until the photoresist from the second photolithography is exposed; finally, removing the residual photoresist with the resist remover from step S6 to obtain a low-crosstalk Micro LED matrix headlight chip with a light-blocking structure.

[0029] In a preferred embodiment, in step S7, the preparation requirements for the silica-titanium dioxide mixture are as follows: the viscosity of the silica deviates by ≤25% from the viscosity of the silica used in step S3, and the hardness after curing deviates by ≤15% from the hardness of the silica after curing in step S3; the amount of titanium dioxide added is 20%-50% of the mass of the silica, and the transmittance of the mixture at a wavelength of 450nm after curing is ≤15%, and the thickness of the light-blocking structure after curing is 1.5μm to 13μm.

[0030] In a preferred embodiment, in step S7, the curing process parameters after spin-coating the silicone titanium dioxide mixture are: the curing temperature deviation from the high-temperature curing temperature in step S4 is ≤8℃, and the curing time deviation from the high-temperature curing time in step S4 is ≤25%; after curing, the bonding force between the light-blocking structure and the phosphor layer is verified by tensile testing to be ≥3.5MPa, with no risk of delamination or peeling.

[0031] Due to the application of the above technical solution, the beneficial effects of this application compared with the prior art are as follows:

[0032] 1. Significantly reduced crosstalk rate: By using "photolithography to define phosphor regions + optional light-blocking structures", the crosstalk rate is ≤5%, which is far lower than the existing technology of more than 15%, thus improving the accuracy of illumination zoning;

[0033] 2. Significantly improved yield: Step-by-step grinding, precise curing parameters, and compatibility with CMOS bonding processes enable chip fabrication yields to be ≥90%, an improvement of 15%-20% compared to existing technologies;

[0034] 3. Excellent performance stability: phosphor layer thickness deviation ≤2.5μm, brightness uniformity ≥90%, silicone crosslinking degree ≥90%, which can meet the wide temperature requirements of automotive use from -40℃ to 125℃;

[0035] 4. Strong process compatibility: No need to introduce dedicated deep etching equipment; it is compatible with existing Micro LED chip production lines, reducing equipment investment costs.

[0036] 5. Strong adaptability to multiple scenarios: Through the optimization of the weather resistance of the passivation layer, electrodes and silicone, it can meet the needs of special scenarios such as ships and oceans, high temperature and high humidity. The electrode corrosion rate is ≤1% / year and the overall service life is ≥5 years, which is much longer than the service life of existing technologies. Attached Figure Description

[0037] 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.

[0038] Figure 1 This is a flowchart illustrating a method for fabricating a low-crosstalk Micro LED matrix headlight according to the present invention.

[0039] Figure 2 This is a schematic diagram of steps S1-S2 in the method of Embodiment 1 of the present invention;

[0040] Figure 3 This is a schematic diagram of step S3 in the method of Embodiment 1 of the present invention;

[0041] Figure 4 This is a schematic diagram of step S4 in the method of Embodiment 1 of the present invention;

[0042] Figure 5 This is a schematic diagram of step S5 in the method of Embodiment 1 of the present invention;

[0043] Figure 6 This is a schematic diagram of step S6 in the method of Embodiment 1 of the present invention;

[0044] Figure 7-9 This is a schematic diagram of step S7 in the method of Embodiment 1 of the present invention. Detailed Implementation

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Example 1

[0052] Please see Figure 1 This application provides a method for fabricating a low-crosstalk Micro LED matrix headlight, further refining the technical principles, parameter selection criteria, and process coordination logic of each step, specifically including the following steps:

[0053] S1, Blue Micro LED chip preprocessing (core: driver integration and pixel definition).

[0054] Substrate selection logic: Substrate options include sapphire / GaN composite substrates (excellent light transmittance, suitable for high-brightness scenarios), Si substrates (good thermal conductivity, suitable for high-power headlights), or pure sapphire substrates (low cost, suitable for general lighting). The substrate must match the thermal expansion coefficient of the CMOS driver chip (difference ≤ 1). ), to avoid cracking after bonding;

[0055] Eutectic bonding parameters are based on: bonding temperature 200-300℃ (lower than the heat deformation temperature of the substrate and chip), pressure 5-15MPa (to ensure ohmic contact resistance ≤10mΩ), and Au-Sn eutectic alloy (melting point 280℃) is used to achieve high-strength bonding;

[0056] Synergistic thinning process: A combination of mechanical grinding (removing 80% of the substrate thickness) and chemical mechanical polishing (CMP) is used. The substrate thickness after thinning is 35-125μm (too thin and it is prone to brittleness, too thick and it affects heat dissipation). The CMP stage employs... Abrasive (particle size 50-100nm) to ensure surface roughness ≤0.1μm;

[0057] Etching and Coating Logic: Etching processes (ICP / RIE / DRIE) have a depth of 1.2-6.5μm, requiring penetration into the n-type region of the GaN epitaxial layer to ensure electrical isolation of LED pixels; the electrode layer employs a double-layer structure (e.g., Cr / Au), with the Cr layer (35-65nm) improving adhesion and the Au layer (380-620nm) reducing contact resistance; the passivation layer ( / / Thickness 100-500nm, isolating water vapor and ion migration.

[0058] S2, photolithography process (core: precise definition of phosphor region).

[0059] Photoresist thickness adaptation principle: The photoresist thickness is determined by the target thickness of the phosphor layer (usually photoresist thickness = phosphor layer thickness - deposition increment), ensuring that the phosphor layer thickness meets the standard after subsequent polishing.

[0060] Application scenarios of the two photolithography methods:

[0061] Method (1) (overall exposed light-emitting area): suitable for low-to-medium resolution headlights with pixel pitch > 5μm, simplified process and low cost;

[0062] Method (2) (Photoresist isolation between pixels): Suitable for high-resolution headlights with pixel pitch ≤ 5μm. The isolation column (width 0.5-2μm) can reserve space for light-blocking structure to further reduce crosstalk.

[0063] S3, Coating a mixture of silicone phosphor (Core: Uniformity control).

[0064] Silicone material selection criteria: Shore hardness ≥ 32D (ensuring impact resistance after curing), 450nm transmittance ≥ 90% (reducing blue light loss), viscosity 1800-3200 μm. (Easy to spread and no dripping when swirl-coated);

[0065] Phosphor Selection Logic: (Low cost, suitable for warm white light) (Excellent color temperature stability, suitable for wide temperature scenarios), quantum dot phosphor (wide color gamut, suitable for colored lighting), particle size is 1 / 5-1 / 3 of the pixel diameter (ensuring no gaps in the filling and avoiding increased light scattering).

[0066] Vacuum degassing process: degassing pressure ≤ -0.09MPa, time 1-3h, to remove air bubbles in the mixture (air bubbles can cause uneven light refraction and lead to dark spots).

[0067] S4, vacuum static curing and high temperature curing (core: phosphor sedimentation thickness control).

[0068] Vacuum settling principle: A vacuum environment of -0.07 to -0.13 MPa can accelerate phosphor settling and prevent agglomeration; settling for 8-14 hours ensures that the settling layer thickness is greater than the photoresist thickness (subsequent grinding can precisely remove excess phosphor).

[0069] Curing parameters are based on: temperature 80-150℃ (matching the silicone curing curve, such as Dow Corning OE-6630 silicone which requires 120℃ / 2h), time 1-4h, ensuring crosslinking degree ≥90% (insufficient crosslinking degree will lead to poor temperature resistance of silicone and easy yellowing with long-term use).

[0070] S5, high-precision grinding and thinning (core: thickness and flatness control).

[0071] Grinding wheel selection logic: ceramic grinding wheels (suitable for hard and brittle substrates) or diamond grinding wheels (suitable for high hardness substrates), with a mesh size ≥ 900 (too low a mesh size can easily cause surface scratches);

[0072] Advantages of step-by-step grinding: coarse grinding (removing 60%-80% of excess thickness, feed rate 0.3-0.35μm / s) → fine grinding (controlling thickness deviation, feed rate 0.1-0.2μm / s) → polishing (surface roughness ≤0.1μm), avoiding chip damage caused by excessive stress in a single grinding process;

[0073] Endpoint control: Real-time monitoring via laser thickness gauge, stopping when the photoresist is exposed or the set thickness (5-20μm) is reached, ensuring that the phosphor layer thickness deviation is ≤2.5μm.

[0074] S6, photoresist removal (core: non-destructive photoresist removal).

[0075] The selection logic for photoresist remover: organic photoresist removers (acetone, ethanol, etc., suitable for acid-sensitive silicone), inorganic photoresist removers (sulfuric acid-hydrogen peroxide, etc., suitable for highly adhesive photoresists). The processing temperature and time must match the type of photoresist (e.g., AZ 4620 photoresist can be completely removed with acetone at 50℃ / 10min).

[0076] Post-processing: Rinse with deionized water for 5-15 minutes (to remove residual adhesive solution), and dry at 60-100℃ for 1-2 hours (to avoid residual moisture causing electrode corrosion).

[0077] S7, light-blocking structure fabrication (optional, core: extreme crosstalk reduction).

[0078] Photoresist is used to cover the chip electrodes and other non-light-emitting areas, leaving the rest exposed, which paves the way for filling the light-emitting areas with enclosure material later.

[0079] Parameters of silica gel and titanium dioxide mixture: silica gel viscosity deviation from step S3 ≤ 25% (to ensure adhesion to phosphor layer), titanium dioxide addition amount 20%-50% (transmittance ≤ 15%, to achieve effective light blocking);

[0080] Synergistic curing and polishing: Curing parameters are the same as in step S4 (to avoid thermal stress causing delamination), and polishing is performed until the secondary photoresist is exposed (ensuring that the height of the light-blocking structure is flush with the phosphor layer, without any protrusions).

[0081] Bonding strength verification: tensile test ≥3.5MPa (simulating headlight vibration scenario to prevent the light-blocking structure from falling off).

[0082] Example 2

[0083] This application also provides a method for fabricating a basic low-crosstalk Micro LED matrix headlight (without a light-blocking structure), comprising the following steps:

[0084] S1, using a sapphire / GaN composite substrate, is bonded to a CMOS driver chip (model: TI TPS92691) using Au-Sn eutectic bonding (250℃, 10MPa); mechanical polishing + CMP thinning to 50μm; ICP etching (depth 3μm) to form independent LED pixels (diameter 10μm, spacing 8μm); electron beam evaporation to prepare Cr / Au electrodes (50nm / 500nm), followed by PECVD fabrication. Passivation layer (300nm);

[0085] S2, using photolithography (1), with a photoresist (AZ 4620) thickness of 8μm, exposes all LED pixel areas after development;

[0086] S3, silicone (Dow Corning OE-6630, Shore 40D, 95% transmittance at 450nm, viscosity 2500m). )and Phosphors (particle size 2μm) were mixed at a mass ratio of 3:1 and degassed under vacuum at -0.1MPa for 2 hours; the chip was then coated by spin coating (3000rpm, 30s).

[0087] S4, -0.1MPa vacuum standing for 10h, 120℃ high temperature curing for 2h (crosslinking degree 95%).

[0088] S5, 1200 mesh ceramic grinding wheel step-by-step grinding: coarse grinding (feed 0.3μm / s, remove 70% of excess thickness) → fine grinding (feed 0.2μm / s, surface roughness 0.1μm), grinding until the photoresist is exposed (phosphor layer thickness 8μm).

[0089] S6, remove adhesive with acetone (50℃, 10min), wash with deionized water for 10min (40℃), and dry at 80℃ for 1.5h to obtain a prototype of white Micro LED chip.

[0090] Performance testing: crosstalk rate 4.2%, brightness uniformity 92%, chip yield 93%.

[0091] Example 3

[0092] This application also provides a method for fabricating a high-resolution, low-crosstalk Micro LED matrix headlight (including a light-blocking structure), comprising the following steps:

[0093] Based on Example 2, add step S7:

[0094] S7, secondary photolithography (photoresist AZ 4620), covering electrodes and non-light-emitting areas, exposing pixel gaps (1μm width); silicone (same as S3, viscosity 2400m). Mix the photoresist with titanium dioxide (R902, particle size 500nm) at a mass ratio of 2:1, and apply the mixture to fill the gaps. Cure at 120℃ for 2 hours. Grind with a 1200-mesh abrasive wheel until the secondary photoresist is exposed (light-blocking structure thickness 5μm). Remove the photoresist with acetone (same as S6) to obtain a chip with a light-blocking structure.

[0095] Performance testing: crosstalk rate 2.8%, brightness uniformity 94%, light-blocking structure bonding strength 4.1MPa, chip yield 91%.

[0096] Example 4

[0097] This application provides a method for manufacturing a salt spray resistant, low crosstalk Micro LED matrix headlight (including a light-blocking structure) for marine lighting, comprising the following steps:

[0098] S1 uses a Si substrate (with excellent thermal conductivity, suitable for high-power marine lighting) and is bonded to a CMOS driver chip (model: ADIAP D8860) using Au-Sn eutectic bonding (280℃, 12MPa). Mechanical polishing and CMP are used to thin it to 80μm (a thicker Si substrate improves impact resistance). DRIE etching (4μm depth) forms individual LED pixels (15μm diameter, 10μm spacing, suitable for long-distance marine lighting). Cr / Ni / Au electrodes (40nm / 120nm / 450nm) are fabricated by magnetron sputtering. ALD process is then used for fabrication. / Double passivation layer (250nm / 150nm);

[0099] S2, using photolithography (2), the photoresist (Shipley S1813) is 10μm thick, and after development, it forms a photoresist isolation pillar with a width of 1.5μm, reserving space for light-blocking structure;

[0100] S3, salt spray resistant silica gel (Dow Corning SE 4486) with 8% silane coupling agent (KH-550), and Phosphors (3μm particle size, excellent color temperature stability, suitable for wide temperature marine environments) are mixed at a mass ratio of 4:1; vacuum degassing at -0.09MPa for 2.5h; and then coated onto the chip using a blade (speed 5mm / s, thickness 15μm) (blank coating is suitable for large-size chips on Si substrates, avoiding edge effects from spin coating).

[0101] S4, -0.11MPa vacuum standing for 12h, 130℃ high temperature curing for 3h (modified silicone requires slightly higher temperature to ensure crosslinking degree ≥92%).

[0102] S5, 1000-mesh diamond grinding wheel step-by-step grinding: coarse grinding (feed 0.25μm / s, remove 75% of excess thickness) → fine grinding (feed 0.15μm / s, surface roughness 0.15μm), grinding until the photoresist (phosphor layer thickness 10μm) is exposed.

[0103] S6, remove glue with sulfuric acid-hydrogen peroxide mixed solution (volume ratio 3:1, 70℃, 8min), wash with deionized water for 12min (50℃, to improve the removal rate of glue residue), and dry at 90℃ for 2h;

[0104] S7, secondary photolithography (Shipley S1813 photoresist), covering the electrodes and non-light-emitting areas, exposing the pixel gap (width 1.5μm); silicone (same as S3) mixed with titanium dioxide (R902, particle size 500nm) and nano ZnO (particle size 30nm) at a mass ratio of 5:3:0.2, and dispensing to fill the gap; cured at 130℃ for 3h; ground with a 1000-grit abrasive wheel until the secondary photoresist is exposed (light-blocking structure thickness 10μm); the photoresist is removed with a sulfuric acid-hydrogen peroxide mixed solution to obtain a salt spray resistant chip.

[0105] Performance testing:

[0106] Optical performance: crosstalk rate 3.5%, brightness uniformity 93%;

[0107] Salt spray resistance (GB / T 10125-2021, 5% salt spray, 1000h): No corrosion of electrodes, light-blocking structure light-shielding rate attenuation of 2.1%, no cracking of silicone.

[0108] Mechanical properties and lifespan: Electrode contact resistance variation ≤5%, overall lifespan estimated at 6.2 years;

[0109] Yield: 89.5% (Si substrates have higher hardness, so the yield is slightly lower than that of sapphire substrates, but still much higher than existing technologies).

[0110] Through the above embodiments, this invention comprehensively verifies the feasibility, stability, and technical advantages of a low-crosstalk Micro LED matrix headlight fabrication method in different application scenarios. By synergistically combining "photolithography domain control - deposition thickness control - grinding thickness determination - structural crosstalk reduction", the core pain points of existing technologies, such as "high crosstalk, low yield, poor uniformity, and weak scenario adaptability", can be effectively solved. Moreover, the process is compatible with existing Micro LED production lines, requiring no additional dedicated equipment, and has the potential for large-scale industrial application.

[0111] Based on the process flexibility of this invention, it can be further extended to more subdivided fields: for example, for medical lighting scenarios, high color rendering index (Ra≥97) lighting can be achieved by optimizing phosphor selection (such as using high color rendering index quantum dot phosphors); for aerospace scenarios, anti-radiation coating process can be added to improve the stability of the chip in a strong radiation environment; the technical framework of this invention provides a general solution for the "scenario-based customization" of Micro LED matrix headlights, helping to promote the deep penetration of Micro LED lighting technology into multiple fields.

[0112] 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 preparing a low cross-talk Micro LED matrix headlight, characterized in that, Comprising the following steps: S1, blue light Micro LED chip pretreatment: using mature process to prepare blue light Micro LED chip, specifically including co-crystal bonding of substrate and CMOS driving chip, thinning treatment of the bonded composite structure, forming independent LED pixel points through etching process, and then completing electrode and passivation layer preparation through coating treatment; the LED pixel points realize individual lighting and partition display control through the CMOS driving chip; S2, photoetching process treatment: photoetching and developing the blue light Micro LED chip prepared in step S1 to expose the light emitting area of the chip and cover the non-light emitting area with photoresist; the thickness of the photoresist is determined by the target thickness of the subsequent phosphor layer and meets the photoetching and developing resolution ≥1 μm; S3, coating of silica gel and phosphor mixture: mixing silica gel and phosphor and vacuum deaerating to obtain uniform silica gel and phosphor mixture; using spin coating, spraying or blade coating to cover the mixture on the surface of the blue light Micro LED chip completed photoetching in step S2; S4, vacuum standing and high temperature curing: placing the chip coated in step S3 in a vacuum environment of-0.07 MPa to-0.13 MPa for 8 h to 14 h until the thickness of the accumulation layer formed by the phosphor due to density difference is greater than the thickness of the photoresist in step S2; after the standing is completed, high temperature curing treatment is performed on the chip to completely shape the silica gel, and the crosslinking degree of the silica gel after curing is ≥90%; S5, high-precision grinding and thinning: using a grinding wheel to grind and thin the chip after curing in step S4, controlling the total thickness deviation in the grinding process to be ≤2.5 μm and the surface roughness to be ≤0.25 μm; The grinding end point is to expose the photoresist in step S2, or to partially remove the photoresist to achieve the set thickness of the phosphor layer when the thickness of the photoresist meets the requirements; S6, photoresist removal: using a photoresist remover that has no corrosive and peeling effect on silica gel and phosphor to remove the residual photoresist in the electrode area and non-light emitting area of the chip to obtain a white light Micro LED chip prototype.

2. The method of claim 1, wherein the low cross-talk Micro LED matrix headlight is prepared by the steps of: In step S1, the thinning treatment adopts a combined process of mechanical grinding and chemical mechanical polishing, and the thickness of the substrate after thinning is 35 μm to 125 μm; the etching process is selected from inductive coupled plasma etching, reactive ion etching or deep reactive ion etching, and the etching depth is 1.2 μm to 6.5 μm to ensure the integrity of the current limiting layer, active area and contact layer structure of the LED pixel points. ​ 3. The method of claim 1, wherein the method further comprises: forming a plurality of micro-LEDs on the substrate; and forming a plurality of micro-LEDs on the substrate. In step S1, the coating process is selected from an electron beam evaporation process, a magnetron sputtering process or a thermal evaporation process; the electrode layer produced is a double-layer metal structure selected from Cr / Au, Ti / Au, Ni / Au or Al / Ni / Au, wherein the thickness of the metal bottom layer Cr, Ti or Ni is 35 nm to 65 nm and the thickness of the metal top layer Au or Ni / Au is 380 nm to 620 nm; the passivation layer is produced using , or with a thickness of 100 nm to 500 nm.

4. The method for manufacturing a low-crosstalk Micro LED matrix headlight as described in claim 1, characterized in that, The specific implementation of the photoetching process in step S2 is any one of the following: (1) all LED pixel points in the light emitting area of the blue light Micro LED chip are exposed as a whole, and the non-light emitting area, edge and electrode area are completely covered with photoresist; (2) photoresist isolation structures are formed between adjacent LED pixel points in the light emitting area through photoetching and developing to independently expose each LED pixel point, and the filling space of the functional structure is reserved by removing the isolation structures subsequently.

5. The method of claim 1, wherein the low cross-talk Micro LED matrix headlight is prepared by the steps of: In step S3, the performance parameters of the silica gel satisfy: Shore hardness ≥ 32D, transmittance ≥ 90% at 450 nm wavelength for 1 mm thickness, viscosity is 1800 m to 3200 m ; the fluorescent powder is selected from 、 or quantum dot fluorescent powder, the particle size of the fluorescent powder is 1 / 5 to 1 / 3 of the diameter of the LED pixel point, and the particle size distribution deviation is ≤25%, ensuring that the filling is dense without obvious gaps. ​ 6. The method of claim 1, wherein the low cross-talk Micro LED matrix headlight is prepared by the steps of: In step S5, the grit size of the grinding wheel is ≥900 mesh; the infeed speed during grinding is controlled to be 0.08-0.35 μm / s, and a step-by-step grinding method is used, in which 60-80% of the total thickness is removed in rough grinding, and the surface roughness is controlled to be ≤0.1 μm in fine grinding, so as to avoid scratches on the chip surface or peeling of the phosphor layer. ​ 7. The method of claim 1, wherein the method further comprises: forming a plurality of micro-LEDs on the substrate; and forming a plurality of micro-LEDs on the substrate. In step S6, the stripping solution is selected from any one of the following: (1) an organic stripping solution: acetone, ethanol, ethyl acetate or N-methyl pyrrolidone, the treatment temperature is 25-60°C, and the treatment time is 5-30 min; (2) an inorganic stripping solution: a sulfuric acid-hydrogen peroxide mixed solution with a volume ratio of 1.5:1 to 4.5:1, or a phosphoric acid-nitric acid mixed solution with a volume ratio of 3:1 to 5:1, the treatment temperature is 55-85°C, and the treatment time is 3-20 min; After treatment with all the stripping solutions, the chip surface is cleaned with deionized water, and then dried.

8. The method of claim 1, wherein the low cross-talk Micro LED matrix headlight is prepared by the steps of: Step S7, preparation of a light-blocking structure, is further included, which specifically comprises: performing secondary photolithography on the chip obtained in step S6, covering the electrodes and non-light-emitting areas with photoresist, and exposing the pixel gaps in the light-emitting area; filling a silicone-titanium dioxide powder mixture into the exposed pixel gaps by spin coating or dispensing, and repeating the grinding process of step S5 after solidification to expose the photoresist of the secondary photolithography; Finally, the residual photoresist is removed by the stripping solution in step S6, to obtain a low-crosstalk Micro LED matrix headlight chip with a light-blocking structure.

9. The method of claim 8, wherein the method further comprises: In step S7, the preparation requirements of the silicone-titanium dioxide powder mixture are as follows: the viscosity of the silicone deviates from the viscosity of the silicone used in step S3 by ≤25%, and the hardness after solidification deviates from the hardness of the silicone after solidification in step S3 by ≤15%; the addition amount of titanium dioxide is 20-50% of the mass of the silicone, and the transmittance of the mixture after solidification is ≤15% at a wavelength of 450 nm; and the thickness of the light-blocking structure after solidification is 1.5-13 μm.

10. The method of claim 8, wherein the method further comprises: forming a plurality of micro-LEDs on the substrate; and forming a plurality of micro-LEDs on the substrate. In step S7, the solidification process parameters after spin coating the silicone-titanium dioxide powder mixture are as follows: the solidification temperature deviates from the high-temperature solidification temperature in step S4 by ≤8°C, and the solidification time deviates from the high-temperature solidification time in step S4 by ≤25%; and the binding force between the light-blocking structure and the phosphor layer is verified to be ≥3.5 MPa by a tensile test after solidification, without the risk of delamination or peeling.

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