Low-reflection and high-transmittance coating process

Abstract

The invention belongs to the technical field of glass surface treatment, and particularly relates to a low-reflection high-transmittance coating process which comprises the following steps: pretreating the surface of a glass substrate; a gradient refractive index antireflection layer is deposited on the glass substrate by adopting a plasma enhanced atomic layer deposition process, and the refractive index of the gradient refractive index antireflection layer is gradually reduced from inside to outside; in the process of depositing the gradient refractive index antireflection layer or after the process of depositing the gradient refractive index antireflection layer, at least one time of pulse annealing treatment is carried out on the film layer, and the pulse annealing treatment comprises rapid thermal annealing and traditional thermal annealing which are alternately carried out; and after deposition of the gradient refractive index antireflection layer is completed, in-situ hole sealing treatment is carried out, and fluorosilane steam is introduced to carry out strengthening treatment on the surface of the film layer. According to the low-reflectivity and high-transmittance coating process disclosed by the invention, the gradient refractive index layer is deposited through PEALD, so that extremely low reflectivity and extremely high light transmittance in a wide spectral range are realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of glass surface treatment, and particularly relates to a low-reflection high-transparency coating process. BACKGROUND

[0002] The low-reflection high-transparency coating of the glass substrate is mainly a transparent conductive oxide (TCO) film, especially an indium tin oxide (ITO) film, which is widely used in many fields such as liquid crystal displays, touch screens and solar cells due to its excellent photoelectric performance. However, the high refractive index of ITO material will cause significant interface reflection, reduce the light transmittance of the device, and may cause serious glare problems, affecting the visual experience and device performance. In the related art, in order to reduce reflection and improve light transmittance, the industry usually additionally prepares a layer of anti-reflection film on the ITO layer, but a single anti-reflection film can only achieve zero reflection at a specific wavelength, and the anti-reflection effect follows the quarter wavelength optical principle, which leads to a narrow anti-reflection bandwidth and cannot cover a wide spectrum range from visible light to near infrared, and the overall mechanical reliability and environmental stability are poor. SUMMARY

[0003] Therefore, the application aims to provide a low-reflection high-transparency coating process to at least overcome one of the problems in the background art.

[0004] To achieve the above-mentioned purpose, the technical scheme of the application is as follows: A low-reflection high-transparency coating process, comprising: pretreating the surface of a glass substrate; depositing a gradient refractive index anti-reflection layer on the glass substrate by using a plasma enhanced atomic layer deposition process, the refractive index of the gradient refractive index anti-reflection layer decreasing from inside to outside; performing at least one pulse annealing treatment on the film layer during or after the deposition of the gradient refractive index anti-reflection layer, the pulse annealing treatment comprising alternating rapid thermal annealing and conventional thermal annealing; after completing the deposition of the gradient refractive index anti-reflection layer, performing in-situ hole sealing treatment, and introducing fluorosilane vapor to strengthen the surface of the film layer.

[0005] Further, the gradient refractive index anti-reflection layer comprises a dense SnO2 bottom layer, a refractive index gradient transition layer and a hierarchical porous SnO2 top layer stacked from inside to outside.

[0006] Further, the refractive index gradient transition layer is a composite material of zeolite nanocrystals and SnO2, and the refractive index is gradually changed by adjusting the proportion of different precursors in the plasma enhanced atomic layer deposition process.

[0007] Further, the temperature rising rate of the rapid thermal annealing is 50-150℃ / s, the peak temperature is 450-550℃, and the holding time is 5-15s; the temperature of the traditional thermal annealing is 250-350℃, and the holding time is 20-40 minutes.

[0008] Further, the process conditions of the in-situ hole sealing treatment are as follows: the substrate temperature is 100-150℃, and the fluorosilane vapor treatment time is 10-20 minutes, and the fluorosilane is perfluorooctyltriethoxysilane.

[0009] Further, the reaction temperature of the plasma enhanced atomic layer deposition process is 150-200℃.

[0010] Further, after the surface of the glass substrate is pretreated, the method further comprises: performing a plasma activation treatment on the glass substrate, the treatment gas is a mixed gas of oxygen and nitrogen, the power is 150-250W, and the treatment time is 2-5 minutes.

[0011] Further, after the surface of the glass substrate is pretreated, the method further comprises: depositing an ITO transparent conductive film on the glass substrate, the ITO transparent conductive film is deposited by using a magnetron sputtering process, using a rotating ITO target material, in a mixed gas of argon and oxygen at 140-160℃.

[0012] Further, the sputtering power of the magnetron sputtering process is 1-1.5 kW, the moving speed of the glass substrate is 16±2 mm / s, and the thickness of the ITO transparent conductive film is controlled to be 100-120Å.

[0013] Compared with the prior art, the low-reflection high-transparency coating process has the following advantages: The low-reflection high-transparency coating process realizes extremely low reflectivity and extremely high transmittance in a wide spectral range by depositing a gradient refractive index layer through PEALD; significantly improves the density and mechanical strength of each film layer, especially the porous SiO2 layer at low temperature through pulse annealing treatment, solves the inherent brittleness problem; greatly enhances the hydrophobicity, anti-pollution ability and friction resistance of the film layer surface without sacrificing the internal porosity and optical performance through in-situ hole sealing treatment.

[0014] The low-reflection high-transmittance coating process integrates high-performance ITO conductive film and ultra-high-performance anti-reflection film, adopts low-temperature magnetron sputtering and rotating target material to ensure high uniformity, low resistance and good crystallinity of the ITO film. The gradient anti-reflection layer deposited subsequently not only reduces the reflection of the glass / air interface, but also cleverly compensates and offsets the high reflection of the ITO layer itself, finally realizes the whole device with good conductivity, which is conducive to improving the light transmittance and reflectivity, and meets the extreme requirements of high-end display, touch and other applications on the comprehensive performance of photoelectricity. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and serve as an explanation of the illustrative embodiments of the present application, and are not intended to limit the present application. In the drawings: Figure 1 A flowchart of the low-reflection high-transmittance coating process according to the first embodiment of the present application; Figure 2 A flowchart of the low-reflection high-transmittance coating process according to the second embodiment of the present application. DETAILED DESCRIPTION

[0016] The present application will be further described in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, but not all the structures.

[0017] Figure 1 A flowchart of the low-reflection high-transmittance coating process according to the first embodiment of the present application, see Figure 1 The low-reflection high-transmittance coating process specifically includes the following steps: S1, pretreating the surface of the glass substrate.

[0018] For example, a standard soda-lime glass substrate (size 100mm x 100mm x 1.1mm) is provided, and the glass substrate is sequentially placed in an ultrasonic cleaning machine containing acetone and isopropanol for 5 minutes each.

[0019] S2, plasma activation treatment is performed on the glass substrate, the treatment gas is a mixture of oxygen and nitrogen, the power is 150-250W, and the treatment time is 2-5 minutes.

[0020] For example, after rinsing with deionized water and drying with nitrogen, the glass substrate is placed in a plasma cleaning machine, and a mixture of oxygen and nitrogen (volume ratio 1:1, total flow rate 100sccm) is introduced, and the glass substrate is activated at a power of 200W and a pressure of 5Pa for 3 minutes.

[0021] Optionally, the gas used in the plasma activation treatment is oxygen and nitrogen, the flow rate of each is 50 sccm, the activation power is 200 W, the chamber pressure is 5 Pa, and the treatment time is 3 minutes. The foregoing plasma activation step can be performed in a radio frequency (13.56 MHz) plasma cleaning machine.

[0022] In the foregoing manner, the plasma activation of the mixed gas of oxygen and nitrogen can efficiently and non-pollutingly completely remove the organic residues on the surface of the substrate and generate a large number of dangling bonds and active functional groups on the surface. This provides a large number of nucleation sites for the subsequent PEALD film layer and forms strong chemical bonds, thereby ensuring excellent adhesion between the entire film system and the substrate and fundamentally preventing the peeling risk of the film layer during use.

[0023] S3, a gradient refractive index antireflection layer is formed on the glass substrate by using a plasma enhanced atomic layer deposition process.

[0024] The gradient refractive index antireflection layer includes, from inside to outside, a dense SnO2 bottom layer, a refractive index gradient transition layer, and a hierarchical porous SnO2 top layer. Secondly, the refractive index gradient transition layer is a composite material of zeolite nanocrystals and SnO2, and the refractive index is realized from 1.38-1.50 to 1.28-1.35 by adjusting the ratio of different precursors in the plasma enhanced atomic layer deposition process.

[0025] In the foregoing arrangement, the three-layer gradient structure design of the gradient refractive index antireflection layer maximally eliminates the Fresnel reflection of light at multiple interfaces through the continuous and smooth transition of the refractive index, which is the physical basis for realizing super-wide spectral antireflection and increased transmission. The dense bottom layer ensures strong adhesion to the glass or ITO substrate; the refractive index gradient transition layer effectively connects the high-refractive-index bottom layer and the ultra-low-refractive-index top layer, avoiding reflection peaks caused by refractive index discontinuity; and the hierarchical porous top layer becomes an ideal matching layer for the air interface due to its ultra-low refractive index close to air.

[0026] Optionally, the thickness of the dense SnO2 bottom layer is 50 nm and is formed by a pure PEALD process (without a template agent). The thickness of the refractive index gradient transition layer is 80 nm, and the realization of the refractive index depends on the gradual change of the ratio of zeolite nanocrystals (formed by tetraethyl orthosilicate TEOS or tetrapropylammonium hydroxide TPAOH precursors) in the SnO2 matrix (formed by BTBAS), which is realized by controlling the precursor pulse time. The thickness of the hierarchical porous SnO2 top layer is 100 nm, and the porous structure is formed by co-deposition of the CTAB template agent in the PEALD process and subsequent partial removal by oxygen plasma.

[0027] In practical applications, the processed glass substrate can be transferred into a PEALD reaction chamber (e.g., the Beneq TFS-500 in Finland), and the reaction chamber temperature can be set to 180°C.

[0028] First, a dense SnO2 underlayer was deposited using bis(tert-butylamino)silane (BTBAS) as the silicon precursor and oxygen plasma as the oxygen source. Each ALD cycle consisted of: a 0.1 s BTBAS pulse – a 5 s nitrogen purging – a 0.2 s oxygen plasma pulse (100 W, 5 s) – a 5 s nitrogen purging. This process was repeated 500 times to form a dense SnO2 underlayer with a thickness of approximately 50 nm and a refractive index of 1.46.

[0029] Subsequently, a refractive index-gradient transition layer was deposited. BTBAS and a zeolite precursor (a 10:1 molar mixture of TEOS and TPAOH, vaporized via a vaporizer) were used simultaneously. The pulse times of the two precursors were linearly varied by a control valve: initially, BTBAS pulsed for 0.1 s and the zeolite precursor pulsed for 0.1 s; at the end, BTBAS pulsed for 0.05 s and the zeolite precursor pulsed for 0.5 s. The purging and plasma steps remained constant for each cycle. This process was repeated 800 times to form a transition layer approximately 80 nm thick with a refractive index gradually decreasing from 1.45 to 1.30.

[0030] Finally, a hierarchical porous SnO2 top layer was deposited. During a cycle of BTBAS and oxygen plasma, CTAB (cetyltrimethylammonium bromide) vapor, a pore-templating agent, was introduced with a pulse duration of 0.2 s, and the purging time was extended to 10 s to ensure removal of excess template agent. This process was repeated 1000 times to form a porous top layer with a thickness of approximately 100 nm, a refractive index of 1.23, and a porosity of approximately 65%.

[0031] S4. During or after the deposition of the gradient refractive index antireflection layer, the film is subjected to at least one pulse annealing process, the pulse annealing process comprising alternating rapid thermal annealing and conventional thermal annealing.

[0032] The rapid thermal annealing (RTA) process involves a heating rate of 50-150°C / s, a peak temperature of 450-550°C, and a holding time of 5-15 seconds. The conventional thermal annealing process involves a temperature of 250-350°C and a holding time of 20-40 minutes. For example, RTA is performed in a rapid thermal processor with a heating rate of 100°C / s, a peak temperature of 500°C, a holding time of 10 seconds, and a nitrogen atmosphere. Conventional thermal annealing is performed in a muffle furnace at 300°C for 30 minutes in an air atmosphere. The two annealing modes are alternated, with RTA followed by conventional annealing.

[0033] In practical applications, pulse annealing is required after each film layer is deposited, and this pulse annealing process is performed immediately after each layer is deposited. For example, after each film layer is deposited, the glass substrate must be immediately transferred to an annealing furnace, where it is rapidly heated to 500°C at a rate of 100°C / s in a nitrogen atmosphere, held for 10 seconds, and then annealed in air at 300°C for 30 minutes.

[0034] Using the above setup, rapid thermal annealing (RTA) can provide high energy in a very short time, prompting atomic rearrangement in the film layer to form more stable bonds and microcrystalline structures, thereby significantly improving the cohesive strength and hardness of the film layer. Subsequent conventional thermal annealing provides a thermal relaxation process, helping to release any internal stress that may be introduced by RTA, making the film structure more stable. This alternating pulsed annealing mode, compared to a single annealing method, achieves superior film strengthening effects at lower average temperatures and processing times, balancing the trade-off between the "optical properties of porous structures" and the "mechanical strength of densification."

[0035] S5. After the deposition of the gradient refractive index antireflection layer is completed, in-situ sealing treatment is performed, and fluorosilane vapor is introduced to strengthen the surface of the film.

[0036] Specifically, the in-situ sealing process conditions are a substrate temperature of 100-150°C and a fluorosilane vapor treatment time of 10-20 minutes, wherein the fluorosilane is perfluorooctyltriethoxysilane.

[0037] In practical applications, after the entire gradient layer deposition is completed, the substrate temperature can be lowered to 120°C. Then, perfluorooctyltriethoxysilane (C8H4F) carried by nitrogen gas (50 sccm) is introduced into the PEALD reaction chamber. 13 Si) vapor is applied at a pressure of 0.2 Torr for 15 minutes. After treatment, the reaction chamber is purged with high-purity nitrogen for 10 minutes. Alternatively, the in-situ sealing treatment can also be performed in situ on the deposition equipment. This process only forms a reinforced hydrophobic layer on the outermost surface of the film, without affecting the internal pore structure.

[0038] Using the above-described setup, in-situ vapor sealing technology achieves selective enhancement. Fluorosilane molecules react only with the silanol groups on the outermost surface of the membrane, forming strong chemical bonds and low surface energy perfluoroalkyl chains, allowing for precise control of the penetration depth. This ensures the complete preservation of the valuable nanoporous structure within the membrane, guaranteeing its ultra-low refractive index and optical properties. Simultaneously, the enhanced hydrophobic layer formed on the surface increases the water contact angle, endowing the product with excellent hydrophobicity, antifouling, and moisture resistance, while also increasing surface hardness, significantly enhancing the product's durability.

[0039] In a preferred embodiment of this example, the reaction temperature of the plasma-enhanced atomic layer deposition process is 150-200°C.

[0040] For example, the entire deposition process of the gradient refractive index antireflective layer was completed in a PEALD apparatus, with the reaction chamber temperature constantly controlled at 180°C (within the range of 150-200°C). The precursor sources included BTBAS, a TEOS / TPAOH mixed solution, and CTAB template agent, and the oxygen source was O2 plasma (100W power).

[0041] By employing the aforementioned setup and a low-temperature PEALD process at 150-200℃, damage to the glass substrate, ITO conductive layer, or other heat-sensitive components caused by high-temperature processes is avoided, thus broadening the application range of this technology. Furthermore, the inherent atomic-level deposition precision and excellent step coverage of PEALD technology ensure the accurate realization of complex gradient refractive index structures and high uniformity of film thickness on three-dimensional curved surfaces, which is unmatched by traditional sol-gel or sputtering processes.

[0042] This embodiment provides a low-reflectivity, high-transmittance coating process. By depositing a gradient refractive index layer using PEALD, extremely low reflectivity and extremely high transmittance are achieved over a wide spectral range. Pulse annealing significantly improves the density and mechanical strength of each film layer, especially the porous SiO2 layer, at low temperatures, solving its inherent fragility problem. In-situ sealing treatment greatly enhances the hydrophobicity, anti-fouling ability, and abrasion resistance of the film surface without sacrificing internal porosity and optical performance.

[0043] Figure 2 This is a schematic diagram of the low-reflectivity, high-transmittance coating process described in Embodiment 2 of the present invention. (See attached diagram.) Figure 2 This embodiment is an optimization based on the above embodiment. Specifically, after pretreating the surface of the glass substrate, the method further includes: depositing an ITO transparent conductive film on the glass substrate. The ITO transparent conductive film is deposited using a magnetron sputtering process at 140-160°C in a mixed gas of argon and oxygen using a rotating ITO target. This low-reflection, high-transmittance coating process specifically includes the following steps: S1. Pre-treat the surface of the glass substrate.

[0044] S2. Perform plasma activation treatment on the glass substrate. The treatment gas is a mixture of oxygen and nitrogen, the power is 150-250W, and the treatment time is 2-5 minutes.

[0045] S3. Deposit an ITO transparent conductive film on the glass substrate. The ITO transparent conductive film is deposited by magnetron sputtering at 140-160°C using a rotating ITO target in a mixed gas of argon and oxygen.

[0046] For example, the activated substrate can be transferred into the magnetron sputtering chamber. The chamber is then evacuated to a base vacuum of 5.0 × 10⁻⁶. -4 Argon (200 sccm) and oxygen (2 sccm) were introduced, and the working pressure was adjusted to 0.5 Pa. The substrate temperature was heated and stabilized at 155 °C. The rotating ITO target (In₂O₃:SnO₂ = 90:10 wt%) was started, and a DC power of 1.3 kW was applied for pre-sputtering for 5 minutes. Subsequently, the baffle was opened, and the substrate was moved at a constant speed of 16 mm / s for coating until the ITO film thickness reached 110 Å.

[0047] In practical applications, the above steps can be completed in a DC magnetron sputtering system using a high-density (>99%) rotating cylindrical ITO target. The process gases are high-purity argon (200 sccm) and high-purity oxygen (2 sccm), with oxygen accounting for approximately 1%. The substrate temperature is controlled at 155°C, the sputtering power is 1.3 kW, and the substrate passes uniformly under the target at a speed of 16 mm / s. By controlling the number of passes, the film thickness can be precisely controlled at 110 Å.

[0048] S4. A gradient refractive index antireflection layer is deposited on the glass substrate using a plasma-enhanced atomic layer deposition process, wherein the refractive index of the gradient refractive index antireflection layer decreases from the inside to the outside.

[0049] S5. During or after the deposition of the gradient refractive index antireflection layer, the film is subjected to at least one pulse annealing process, the pulse annealing process comprising alternating rapid thermal annealing and conventional thermal annealing.

[0050] S6. After the deposition of the gradient refractive index antireflection layer is completed, in-situ sealing treatment is performed, and fluorosilane vapor is introduced to strengthen the surface of the film.

[0051] This embodiment describes a low-reflection, high-transmittance coating process that integrates a high-performance ITO conductive film with an ultra-high-performance anti-reflection film. Low-temperature magnetron sputtering and a rotating target ensure the high uniformity, low resistance, and good crystallinity of the ITO film. The subsequently deposited gradient anti-reflection layer not only reduces reflection at the glass / air interface but also cleverly compensates for and counteracts the high reflectivity of the ITO layer itself. Ultimately, this achieves a device that possesses good conductivity while simultaneously improving transmittance and reflectivity, meeting the extreme requirements of high-end display and touch applications for comprehensive optoelectronic performance.

[0052] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A low-reflectivity, high-transmittance coating process, characterized in that, include: Pre-treatment of the glass substrate surface; A gradient refractive index antireflection layer is deposited on the glass substrate using a plasma-enhanced atomic layer deposition process, wherein the refractive index of the gradient refractive index antireflection layer decreases from the inside to the outside. During or after the deposition of the gradient refractive index antireflection layer, the film is subjected to at least one pulse annealing process, which includes alternating rapid thermal annealing and conventional thermal annealing. After the deposition of the gradient refractive index antireflection layer is completed, in-situ sealing is performed, and fluorosilane vapor is introduced to strengthen the surface of the film.

2. The low-reflectivity, high-transmittance coating process according to claim 1, characterized in that: The gradient refractive index antireflection layer comprises, from the inside out, a dense SnO2 bottom layer, a refractive index gradient transition layer, and a hierarchical porous SnO2 top layer.

3. The low-reflectivity, high-transmittance coating process according to claim 2, characterized in that: The refractive index gradient transition layer is a composite material of zeolite nanocrystals and SnO2, and its refractive index is gradually changed by adjusting the proportion of different precursors in the plasma-enhanced atomic layer deposition process.

4. The low-reflectivity, high-transmittance coating process according to claim 1, characterized in that: The rapid thermal annealing has a heating rate of 50-150℃ / second, a peak temperature of 450-550℃, and is held for 5-15 seconds; the conventional thermal annealing has a temperature of 250-350℃ and is held for 20-40 minutes.

5. The low-reflectivity, high-transmittance coating process according to claim 1, characterized in that: The in-situ sealing process conditions are a substrate temperature of 100-150°C and a fluorosilane vapor treatment time of 10-20 minutes, wherein the fluorosilane is perfluorooctyltriethoxysilane.

6. The low-reflectivity, high-transmittance coating process according to claim 1, characterized in that: The reaction temperature of the plasma-enhanced atomic layer deposition process is 150-200℃.

7. The low-reflectivity, high-transmittance coating process according to claim 1, characterized in that: After pretreating the surface of the glass substrate, the method further includes: performing plasma activation treatment on the glass substrate, wherein the treatment gas is a mixture of oxygen and nitrogen, the power is 150-250W, and the treatment time is 2-5 minutes.

8. A low-reflectivity, high-transmittance coating process according to any one of claims 1-7, characterized in that: After pretreating the surface of the glass substrate, the method further includes: depositing an ITO transparent conductive film on the glass substrate, wherein the ITO transparent conductive film is deposited by magnetron sputtering at 140-160°C using a rotating ITO target in a mixed gas of argon and oxygen.

9. The low-reflectivity, high-transmittance coating process according to claim 8, characterized in that: The sputtering power of the magnetron sputtering process is 1-1.5 kW, the glass substrate moving speed is 16±2 mm / s, and the thickness of the ITO transparent conductive film is controlled at 100-120 Å.

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