Ultra-low sheet resistance ito film and method for manufacturing the same

Abstract

The application discloses an ultra-low sheet resistance ITO film and a preparation method thereof. The ultra-low sheet resistance ITO film comprises a substrate layer, wherein an upper coating layer, a primer layer, a silicon-aluminum mixed layer, a first ITO layer and a second ITO layer are sequentially arranged on the substrate layer. The thickness of the first ITO layer is 50-250 nm, and the thickness of the second ITO layer is 50-150 nm. The ultra-low sheet resistance ITO film has low sheet resistance and low warping deformation, and has excellent use performance. When applied to a car color-variable light control film, the ultra-low sheet resistance ITO film has the advantages of low resistance, low energy consumption, energy saving and fast light control reaction speed.

Description

Technical Field

[0001] This invention belongs to the field of ITO film technology, specifically relating to ultra-low sheet resistance ITO films and their preparation methods. Background Technology

[0002] Automotive color-changing film refers to the phenomenon that the optical properties of materials can stably and reversibly change color under the action of an external electric field. This color-changing function plays an important role in improving the driving experience, enhancing the comfort of drivers and passengers, and adjusting the brightness of the interior of the car. It can automatically or manually control the car glass according to the ambient light or user needs, and can dynamically change its optical and thermal properties to achieve the purpose of energy saving and comfortable visual experience.

[0003] The application of indium tin oxide (ITO) films in electrochromic color-changing films is mainly reflected in their use as transparent electrodes. As electrodes, ITO films can control the transparency or reflectivity of the electrochromic color-changing film by changing the voltage or current, thereby achieving dimming functionality. To improve the dimming response speed and reduce energy consumption, a lower sheet resistance of the ITO film is more conducive to changing the voltage or current. However, the sheet resistance of existing ITO films is generally between 12 and 20 Ω. Further reducing the sheet resistance of ITO films presents certain fabrication challenges. Therefore, how to fabricate ITO films with even lower sheet resistance is a problem that needs to be solved.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide an ultra-low sheet resistance ITO film and its preparation method. The ultra-low sheet resistance ITO film has low sheet resistance, low warpage, and excellent performance.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] An ultra-low sheet resistance ITO film includes a substrate layer, on which an upper coating layer, an undercoat layer, a silicon-aluminum hybrid layer, a first ITO layer, and a second ITO layer are sequentially stacked.

[0008] The thickness of the first ITO layer is 50–250 nm, and the thickness of the second ITO layer is 50–150 nm.

[0009] In one or more embodiments of the present invention, the indium-tin molar ratio in the first ITO layer is (80-99):(1-20) in terms of indium-tin atoms.

[0010] In one or more embodiments of the present invention, the indium-tin molar ratio in the second ITO layer is (80-99):(1-20) in terms of indium-tin atoms.

[0011] In one or more embodiments of the present invention, the silicon-aluminum molar ratio in the silicon-aluminum mixed layer is (75-99):(1-25) in terms of silicon-aluminum atoms.

[0012] In one or more embodiments of the present invention, the thickness of the silicon-aluminum hybrid layer is 1 to 30 nm.

[0013] In one or more embodiments of the present invention, the base layer material is selected from SiO2, Ti, TiO2, Si, Al2O3, MgF2, SiO, HfO2, SnO2 and Y2O3.

[0014] In one or more embodiments of the present invention, the thickness of the underlayer is 0.2 to 20 nm.

[0015] In one or more embodiments of the present invention, the substrate layer is a PET layer, a PI layer, a TAC layer, a COP layer, or a PC layer.

[0016] Another specific embodiment of the present invention provides the following technical solution:

[0017] The preparation method of ultra-low sheet resistance ITO film includes the following steps:

[0018] Take a substrate layer, apply an upper coating layer and a lower coating layer to both sides of the substrate layer respectively, and set a high-temperature protective film on the lower coating layer;

[0019] An undercoat layer, a silicon-aluminum hybrid layer, a first ITO layer, and a second ITO layer are sequentially deposited on the upper coating layer.

[0020] A positive protective film is applied to the second ITO layer.

[0021] In one or more embodiments of the present invention, the vacuum degree is 1×10 during plating. -4 Below pa, the water vapor value is 9×10 -5 Below Pa, the reaction gas is a mixture of argon, nitrogen and oxygen, with the flow rate ratio of argon, nitrogen and oxygen being (60-80): (20-35): (5-10).

[0022] Compared with existing technologies, this invention reduces the possibility of affecting the stress release of the coating by depositing the ITO layer in two stages and controlling the thickness of the ITO layer in each deposition. This promotes sufficient aging and crystallization of the coating, ensuring carrier concentration and mobility, thereby achieving low sheet resistance and high conductivity. When the ITO film of this invention is applied to automotive color-changing films, it has the advantages of low resistance, low energy consumption, and energy saving, while also effectively accelerating the dimming response speed. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of an ultra-low sheet resistance ITO film in one embodiment of the present invention.

[0025] Explanation of key figure labels:

[0026] 1. High-temperature protective film; 2. Lower coating layer; 3. Substrate layer; 4. Upper coating layer; 5. Undercoat layer; 6. Silicon-aluminum hybrid layer; 7. First ITO layer; 8. Second ITO layer; 9. Positive protective film. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0028] Generally speaking, the thicker the ITO layer in an ITO film, the lower the resistance of the ITO film. In the preparation process of ITO film, multiple pairs of indium tin targets are usually used for simultaneous deposition. However, the heat generated during deposition is relatively large, which can easily cause severe warping of the film surface, leading to an increase in resistance. Moreover, in order to pursue low resistance, the thickness of the ITO layer is generally relatively thick, such as 300nm or 400nm. The thickness of the layer has a negative impact on the stress release of the deposition layer, which can lead to insufficient crystallization of the ITO layer during the aging and crystallization process, resulting in poor sheet resistance uniformity and thus making it impossible to obtain an ITO film with a low sheet resistance.

[0029] This invention modifies the method of depositing a thick ITO layer in one step to depositing an ITO layer in two steps, with the thickness of the ITO layer in each deposition being less than 300 nm. The resulting ITO film not only has a lower sheet resistance, but also has very low warpage, resulting in a high film formation rate and excellent performance.

[0030] One specific embodiment of the present invention provides an ultra-low sheet resistance ITO film, such as... Figure 1As shown, it includes a substrate layer 3, on which an upper coating layer 4, a base layer 5, a silicon-aluminum hybrid layer 6, a first ITO layer 7, and a second ITO layer 8 are sequentially stacked. The thickness of the first ITO layer 7 is 50-250 nm, and the thickness of the second ITO layer 8 is 50-150 nm.

[0031] Specifically, the ITO layer is deposited in two stages, and the thickness of each ITO layer is controlled to reduce the accumulation of internal stress in the ITO layer, promote the crystal growth of the ITO layer, and allow it to fully crystallize. This reduces the problem of warping caused by deformation of the film layer, and at the same time improves the conductivity of the ITO film, giving it a lower sheet resistance.

[0032] In one specific embodiment, the indium-tin molar ratio in the first ITO layer 7 is (80-99):(1-20) in terms of indium-tin atoms, and the indium-tin molar ratio in the second ITO layer 8 is (80-99):(1-20) in terms of indium-tin atoms.

[0033] Specifically, the main factors affecting the conductivity of the ITO layer are carrier concentration and carrier mobility. By controlling the indium-tin molar ratio, the carrier concentration can be increased, and the microstructure of the ITO layer can be optimized to improve the carrier mobility, thereby reducing the resistivity of the ITO layer and making the ITO film exhibit a lower sheet resistance.

[0034] In one specific embodiment, the silicon-aluminum molar ratio in the silicon-aluminum hybrid layer 6 is (75-99):(1-25) based on silicon-aluminum atoms.

[0035] In one specific embodiment, the thickness of the silicon-aluminum hybrid layer 6 is 1–30 nm.

[0036] Specifically, the silicon-aluminum hybrid layer 6 can reduce color difference and improve the weather resistance of the ITO film. Furthermore, when depositing the silicon-aluminum hybrid layer 6, using a silicon-aluminum hybrid target with a certain silicon-aluminum mixing ratio can improve the stability during sputtering, making the sputtering more uniform, thereby obtaining a silicon-aluminum hybrid layer 6 with a better microstructure, and improving the adhesion and photoelectric properties of the film.

[0037] In one specific embodiment, the material of the bottom layer 5 is selected from SiO2, Ti, TiO2, Si, Al2O3, MgF2, SiO, HfO2, SnO2 and Y2O3.

[0038] In one specific implementation, the thickness of the underlayer 5 is 0.2–20 nm.

[0039] Specifically, choosing the above-mentioned type of primer 5 can increase the adhesion of the film layer, improve the stability of the film layer, and to a certain extent adjust the internal stress of the film layer, reduce the possibility of warping of the film layer, and improve the conductivity.

[0040] In one specific embodiment, the substrate layer 3 is a PET layer, a PI layer, a TAC layer, a COP layer, or a PC layer.

[0041] In one specific embodiment, the thickness of the substrate layer 3 is 5.7–250 μm.

[0042] Specifically, selecting the above-mentioned substrate layer 3 can ensure the mechanical strength of the ITO film and guarantee its superior mechanical stability.

[0043] Another specific embodiment of the present invention provides a method for preparing an ultra-low sheet resistance ITO film, comprising the following steps 1-3.

[0044] Step 1: Take a substrate layer, apply an upper coating layer and a lower coating layer to both sides of the substrate layer respectively, and apply a high-temperature protective film on the lower coating layer.

[0045] Specifically, both the upper and lower coating layers are formed by applying an acrylic resin coating solution, which is a conventional product used to improve the corrosion resistance and weather resistance of the film material. Preferably, the thickness of the upper coating layer is 40–900 nm, and the thickness of the lower coating layer is 20–900 nm. The high-temperature protective film is a PET film with a thickness of 30–188 μm. Applying the high-temperature protective film to the lower coating layer can protect the film surface appearance and improve the coating stability during subsequent magnetron sputtering deposition.

[0046] Step 2: Sequentially deposit the undercoat layer, the silicon-aluminum hybrid layer, the first ITO layer, and the second ITO layer on the upper coating layer.

[0047] Specifically, during the plating process, the vacuum level is 1×10⁻⁶. -4 Below pa, the water vapor value is 9×10 -5 Below Pa, the reaction gas is a mixture of argon, nitrogen, and oxygen, with a flow rate ratio of (60–80):(20–35):(5–10). By controlling the vacuum level, moisture content, and reaction gas, sputtering uniformity can be improved, as can the optical stability of the stacked films.

[0048] Step 3: Apply a positive protective film to the second ITO layer.

[0049] Specifically, the protective film is a PET film.

[0050] The present invention will be further described in detail below with reference to specific embodiments.

[0051] Example 1

[0052] The ultra-low sheet resistance ITO film comprises, from bottom to top, a 30μm PET high-temperature protective film, a 60nm lower coating layer, a 38μm PET substrate layer, a 40nm upper coating layer, a 10nm SiO2 undercoat, a 5nm silicon-aluminum hybrid layer, a 100nm first ITO layer, a 100nm second ITO layer, and a 40μm PET positive protective film. The silicon-aluminum molar ratio in the silicon-aluminum hybrid layer is 75:25 (based on silicon-aluminum atoms), the indium-tin molar ratio in the first ITO layer is 99:1 (based on indium-tin atoms), and the indium-tin molar ratio in the second ITO layer is also 99:1 (based on indium-tin atoms).

[0053] In the preparation process, acrylic resin coating solution is applied to both sides of the PET substrate layer, and after drying, an upper coating layer and a lower coating layer are formed. A PET high-temperature protective film is then laminated onto the lower coating layer. Dry magnetron vacuum deposition sputtering is then used, with the vacuum level controlled at 1×10⁻⁶. -4 Below Pa, the water vapor value is 9×10. -5 Below Pa, a mixture of argon, nitrogen, and oxygen was selected as the reaction gas, with a flow rate ratio of argon, nitrogen, and oxygen of 60:30:10. SiO2 underlayer, silicon-aluminum mixed layer, first ITO layer, and second ITO layer were sequentially deposited on the upper coating layer. After the deposition was completed, the film was placed in an oven and aged and crystallized at 150°C for 5 minutes. Finally, a PET positive protective film was laminated on the second ITO layer to obtain an ultra-low sheet resistance ITO film.

[0054] Example 2

[0055] The ultra-low sheet resistance ITO film comprises, from bottom to top, a 70μm PET high-temperature protective film, a 160nm lower coating layer, an 80μm PET substrate layer, a 200nm upper coating layer, a 15nm SiO2 undercoat layer, a 10nm silicon-aluminum hybrid layer, a 150nm first ITO layer, a 100nm second ITO layer, and a 40μm PET positive protective film. The silicon-aluminum molar ratio in the silicon-aluminum hybrid layer is 99:1 (based on silicon-aluminum atoms), the indium-tin molar ratio in the first ITO layer is 80:20 (based on indium-tin atoms), and the indium-tin molar ratio in the second ITO layer is also 80:20 (based on indium-tin atoms).

[0056] In the preparation process, acrylic resin coating solution is applied to both sides of the PET substrate layer, and after drying, an upper coating layer and a lower coating layer are formed. A PET high-temperature protective film is then laminated onto the lower coating layer. Dry magnetron vacuum deposition sputtering is then used, with the vacuum level controlled at 1×10⁻⁶. -4 Below Pa, the water vapor value is 9×10. -5Below Pa, a mixture of argon, nitrogen, and oxygen was selected as the reaction gas, with a flow rate ratio of argon, nitrogen, and oxygen of 60:30:10. SiO2 underlayer, silicon-aluminum mixed layer, first ITO layer, and second ITO layer were sequentially deposited on the upper coating layer. After the deposition was completed, the film was placed in an oven and aged and crystallized at 150°C for 5 minutes. Finally, a PET positive protective film was laminated on the second ITO layer to obtain an ultra-low sheet resistance ITO film.

[0057] Example 3

[0058] The ultra-low sheet resistance ITO film comprises, from bottom to top, a 160μm PET high-temperature protective film, a 300nm lower coating layer, a 100μm PET substrate layer, a 400nm upper coating layer, a 20nm SiO2 underlayer, a 20nm silicon-aluminum hybrid layer, a 150nm first ITO layer, a 150nm second ITO layer, and a 40μm PET positive protective film. The silicon-aluminum molar ratio in the silicon-aluminum hybrid layer is 75:25 (based on silicon-aluminum atoms), the indium-tin molar ratio in the first ITO layer is 87:13 (based on indium-tin atoms), and the indium-tin molar ratio in the second ITO layer is also 87:13 (based on indium-tin atoms).

[0059] In the preparation process, acrylic resin coating solution is applied to both sides of the PET substrate layer, and after drying, an upper coating layer and a lower coating layer are formed. A PET high-temperature protective film is then laminated onto the lower coating layer. Dry magnetron vacuum deposition sputtering is then used, with the vacuum level controlled at 1×10⁻⁶. -4 Below Pa, the water vapor value is 9×10. -5 Below Pa, a mixture of argon, nitrogen, and oxygen was selected as the reaction gas, with a flow rate ratio of argon, nitrogen, and oxygen of 60:30:10. SiO2 underlayer, silicon-aluminum mixed layer, first ITO layer, and second ITO layer were sequentially deposited on the upper coating layer. After the deposition was completed, the film was placed in an oven and aged and crystallized at 150°C for 5 minutes. Finally, a PET positive protective film was laminated on the second ITO layer to obtain an ultra-low sheet resistance ITO film.

[0060] Example 4

[0061] The ultra-low sheet resistance ITO film comprises, from bottom to top, a 130μm PET high-temperature protective film, a 500nm lower coating layer, a 125μm PET substrate layer, a 600nm upper coating layer, a 20nm SiO2 underlayer, a 30nm silicon-aluminum hybrid layer, a 250nm first ITO layer, a 150nm second ITO layer, and a 40μm PET positive protective film. The silicon-aluminum molar ratio in the silicon-aluminum hybrid layer is 99:1 (based on silicon-aluminum atoms), the indium-tin molar ratio in the first ITO layer is 95:5 (based on indium-tin atoms), and the indium-tin molar ratio in the second ITO layer is also 95:5 (based on indium-tin atoms).

[0062] In the preparation process, acrylic resin coating solution is applied to both sides of the PET substrate layer, and after drying, an upper coating layer and a lower coating layer are formed. A PET high-temperature protective film is then laminated onto the lower coating layer. Dry magnetron vacuum deposition sputtering is then used, with the vacuum level controlled at 1×10⁻⁶. -4 Below Pa, the water vapor value is 9×10. -5 Below Pa, a mixture of argon, nitrogen, and oxygen was selected as the reaction gas, with a flow rate ratio of argon, nitrogen, and oxygen of 60:30:10. SiO2 underlayer, silicon-aluminum mixed layer, first ITO layer, and second ITO layer were sequentially deposited on the upper coating layer. After the deposition was completed, the film was placed in an oven and aged and crystallized at 150°C for 5 minutes. Finally, a PET positive protective film was laminated on the second ITO layer to obtain an ultra-low sheet resistance ITO film.

[0063] Comparative Example 1

[0064] The ultra-low sheet resistance ITO film comprises, from bottom to top, a 30μm PET high-temperature protective film, a 60nm lower coating layer, a 38μm PET substrate layer, a 40nm upper coating layer, a 10nm SiO2 undercoat, a 5nm silicon-aluminum hybrid layer, a 300nm ITO layer, and a 40μm PET positive protective film. The silicon-aluminum molar ratio in the silicon-aluminum hybrid layer is 75:25 (based on silicon-aluminum atoms), and the indium-tin molar ratio in the ITO layer is 99:1 (based on indium-tin atoms).

[0065] In the preparation process, acrylic resin coating solution is applied to both sides of the PET substrate layer, and after drying, an upper coating layer and a lower coating layer are formed. A PET high-temperature protective film is then laminated onto the lower coating layer. Dry magnetron vacuum deposition sputtering is then used, with the vacuum level controlled at 1×10⁻⁶. -4 Below Pa, the water vapor value is 9×10. -5 Below Pa, a mixture of argon, nitrogen, and oxygen was selected as the reaction gas, with a flow rate ratio of argon, nitrogen, and oxygen of 60:30:10. SiO2 underlayer, silicon-aluminum mixed layer, and ITO layer were sequentially deposited on the upper coating layer. After the deposition was completed, the film was placed in an oven and aged and crystallized at 150°C for 5 minutes. Finally, a PET positive protective film was laminated on the ITO layer to obtain an ultra-low sheet resistance ITO film.

[0066] Comparative Example 2

[0067] The ultra-low sheet resistance ITO film comprises, from bottom to top, a 70μm PET high-temperature protective film, a 160nm lower coating layer, an 80μm PET substrate layer, a 200nm upper coating layer, a 15nm SiO2 undercoat, a 10nm silicon-aluminum hybrid layer, a 300nm ITO layer, and a 40μm PET positive protective film. The silicon-aluminum molar ratio in the silicon-aluminum hybrid layer is 99:1 (based on silicon-aluminum atoms), and the indium-tin molar ratio in the ITO layer is 80:20 (based on indium-tin atoms).

[0068] In the preparation process, acrylic resin coating solution is applied to both sides of the PET substrate layer, and after drying, an upper coating layer and a lower coating layer are formed. A PET high-temperature protective film is then laminated onto the lower coating layer. Dry magnetron vacuum deposition sputtering is then used, with the vacuum level controlled at 1×10⁻⁶. -4 Below Pa, the water vapor value is 9×10. -5 Below Pa, a mixture of argon, nitrogen, and oxygen was selected as the reaction gas, with a flow rate ratio of argon, nitrogen, and oxygen of 60:30:10. SiO2 underlayer, silicon-aluminum mixed layer, and ITO layer were sequentially deposited on the upper coating layer. After the deposition was completed, the film was placed in an oven and aged and crystallized at 150°C for 5 minutes. Finally, a PET positive protective film was laminated on the ITO layer to obtain an ultra-low sheet resistance ITO film.

[0069] Comparative Example 3

[0070] The ultra-low sheet resistance ITO film comprises, from bottom to top, a 160μm PET high-temperature protective film, a 300nm lower coating layer, a 100μm PET substrate layer, a 400nm upper coating layer, a 20nm SiO2 underlayer, a 20nm silicon-aluminum hybrid layer, a 300nm ITO layer, and a 40μm PET positive protective film. The silicon-aluminum molar ratio in the silicon-aluminum hybrid layer is 75:25 (based on silicon-aluminum atoms), and the indium-tin molar ratio in the ITO layer is 87:13 (based on indium-tin atoms).

[0071] In the preparation process, acrylic resin coating solution is applied to both sides of the PET substrate layer, and after drying, an upper coating layer and a lower coating layer are formed. A PET high-temperature protective film is then laminated onto the lower coating layer. Dry magnetron vacuum deposition sputtering is then used, with the vacuum level controlled at 1×10⁻⁶. -4 Below Pa, the water vapor value is 9×10. -5 Below Pa, a mixture of argon, nitrogen, and oxygen was selected as the reaction gas, with a flow rate ratio of argon, nitrogen, and oxygen of 60:30:10. SiO2 underlayer, silicon-aluminum mixed layer, and ITO layer were sequentially deposited on the upper coating layer. After the deposition was completed, the film was placed in an oven and aged and crystallized at 150°C for 5 minutes. Finally, a PET positive protective film was laminated on the ITO layer to obtain an ultra-low sheet resistance ITO film.

[0072] Comparative Example 4

[0073] The ultra-low sheet resistance ITO film comprises, from bottom to top, a 130μm PET high-temperature protective film, a 500nm lower coating layer, a 125μm PET substrate layer, a 600nm upper coating layer, a 20nm SiO2 undercoat, a 30nm silicon-aluminum hybrid layer, a 400nm ITO layer, and a 40μm PET positive protective film. The silicon-aluminum molar ratio in the silicon-aluminum hybrid layer is 99:1 (based on silicon-aluminum atoms), and the indium-tin molar ratio in the ITO layer is 95:5 (based on indium-tin atoms).

[0074] In the preparation process, acrylic resin coating solution is applied to both sides of the PET substrate layer, and after drying, an upper coating layer and a lower coating layer are formed. A PET high-temperature protective film is then laminated onto the lower coating layer. Dry magnetron vacuum deposition sputtering is then used, with the vacuum level controlled at 1×10⁻⁶. -4 Below pa, the water vapor value is 9×10. -5 Below Pa, a mixture of argon, nitrogen, and oxygen was selected as the reaction gas, with a flow rate ratio of argon, nitrogen, and oxygen of 60:30:10. SiO2 underlayer, silicon-aluminum mixed layer, and ITO layer were sequentially deposited on the upper coating layer. After the deposition was completed, the film was placed in an oven and aged and crystallized at 150°C for 5 minutes. Finally, a PET positive protective film was laminated on the ITO layer to obtain an ultra-low sheet resistance ITO film.

[0075] The following performance tests were performed on the ultra-low sheet resistance ITO films in each embodiment and comparative example:

[0076] (1) After the coating is completed and the machine is removed, take 10 points on average according to the film width and test the sheet resistance of the 10 points before and after aging and crystallization. The film width is 1200mm. When testing, place the film material face up on the table and use a sheet resistance meter to test the surface sheet resistance. The resistance value after aging and crystallization should reach 8±2Ω. The results are shown in Table 1.

[0077] (2) After the coating is completed and the sample is removed from the machine, cut 3 samples according to the average film width. The sample size is 340*340mm. Bake the sample in a 150℃ oven for 5 minutes. After baking, wait for the temperature to drop below 70℃, take out the sample, place the sample with the film side facing up on the table, and use a ruler to measure the upward warping height of the four corners. Then place the film material on the reverse side and use a ruler to measure the downward warping height of the four corners. The upward warping height should be ≤20mm and the downward warping height should be ≤-10mm. The results are shown in Table 2.

[0078] Table 1. ITO film sheet resistance test results

[0079]

[0080]

[0081] Note: The unit in Table 1 is Ω.

[0082] Table 2. Results of ITO membrane warpage

[0083]

[0084]

[0085] Note: The unit in Table 2 is mm.

[0086] Referring to Table 1, in Comparative Examples 1-4, the average resistance of the films obtained after aging and crystallization using a single ITO layer deposition ranged from a minimum of 9.4Ω to a maximum of 11.5Ω, clearly failing to meet the 8±2Ω requirement. However, the average resistance of the ITO film in the embodiments of this invention after aging and crystallization ranged from a minimum of 8.1Ω to a maximum of 8.2Ω, achieving the target sheet resistance. This demonstrates that the present invention, by depositing an ITO layer of a certain thickness twice, can effectively ensure that the final ITO film has a low sheet resistance.

[0087] Referring to Table 2, the average upward warping height of the ITO films in Comparative Examples 1-4 ranged from a minimum of 35 mm to a maximum of 51 mm, while the average downward warping height ranged from a minimum of -19 mm to a maximum of -31 mm. In contrast, the average upward warping height of the ITO films in this invention ranged from a minimum of 7 mm to a maximum of only 9 mm, and the average downward warping height was -2 mm. This meets the requirements of an upward warping height ≤ 20 mm and a downward warping height ≤ -10 mm, further demonstrating that this invention can effectively reduce the warping problem of the film material by depositing the ITO layer twice and controlling the thickness of the ITO, thus ensuring that the final ITO film has low sheet resistance and low warping.

[0088] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0089] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An ultra-low sheet resistance ITO film, characterized in that, The substrate layer includes an upper coating layer, an undercoat layer, a silicon-aluminum hybrid layer, a first ITO layer, and a second ITO layer, which are sequentially stacked on the substrate layer. The thickness of the first ITO layer is 150 nm, and the thickness of the second ITO layer is 150 nm; The indium-tin molar ratio in the first ITO layer is 87:13, calculated in terms of indium-tin atoms. The indium-tin molar ratio in the second ITO layer is 87:13 in terms of indium-tin atoms; The preparation method of the ultra-low sheet resistance ITO film includes the following steps: Take a substrate layer, coat an upper coating layer and a lower coating layer on both sides of the substrate layer respectively, and set a PET protective film on the lower coating layer; An undercoat layer, a silicon-aluminum hybrid layer, a first ITO layer, and a second ITO layer are sequentially deposited on the upper coating layer. A PET protective film is applied to the second ITO layer; During plating, the vacuum degree is 1×10 -4 Below pa, the water vapor value is 9×10 -5 Below Pa, the reaction gas is a mixture of argon, nitrogen and oxygen, and the flow rate ratio of argon, nitrogen and oxygen is (60~80): (20~35): (5~10).

2. The ultra-low sheet resistance ITO film according to claim 1, characterized in that, The silicon-aluminum molar ratio in the silicon-aluminum hybrid layer is (75-99):(1-25) on a silicon-aluminum atomic basis.

3. The ultra-low sheet resistance ITO film according to claim 1, characterized in that, The thickness of the silicon-aluminum hybrid layer is 1–30 nm.

4. The ultra-low sheet resistance ITO film according to claim 1, characterized in that, The base layer material is selected from SiO2, Ti, TiO2, Si, Al2O3, MgF2, SiO, HfO2, SnO2 and Y2O3.

5. The ultra-low sheet resistance ITO film according to claim 1, characterized in that, The thickness of the substrate layer is 0.2–20 nm.

6. The ultra-low sheet resistance ITO film according to claim 1, characterized in that, The substrate layer is a PET layer, a PI layer, a TAC layer, a COP layer, or a PC layer.

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