Hard optical film and method of making and using same

Abstract

The application relates to a hard optical film and a preparation method and application thereof, the film is an optical film with a nano two-phase structure, the thickness can be regulated, the film has high visible light transmittance and hardness, the film surface is flat and uniform, and the film has a high application prospect. The hard optical film is prepared on the surface of a base material by a magnetron sputtering method, the film has high bonding strength with the base material, the base material has high hardness, high wear resistance and certain corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of thin film materials, and relates to a hard optical thin film, its preparation method and application. Background Technology

[0002] Hard coatings, as protective materials, not only possess excellent wear resistance but also high visible light transmittance, making them widely used in the communications electronics industry. However, with the upgrading of electronic products, the designs widely used in the communications industry are shifting from flat to foldable. The design of foldable screen products relies heavily on materials with high light transmittance and high flexibility. Currently, most products use plastic materials such as PET and PI as foldable screen materials. However, plastic materials are inherently prone to wear and scratches, easily leading to detachment and deformation. Glass materials, due to their poor flexibility and fragility, are difficult to widely apply in foldable screens. Therefore, developing materials with high light transmittance and high flexibility suitable for foldable screens is imperative for their development. Summary of the Invention

[0003] Given the inherent problems with materials used as flexible mobile terminal screens, it is necessary to provide a method for surface reinforcement on a substrate material. This method produces a nanostructured thin film that, in addition to high light transmittance, also possesses high hardness, maintaining excellent scratch and corrosion resistance under various external environments. Based on this idea, this invention proposes a hard optical thin film with multiple properties including high hardness, high light transmittance, scratch resistance, and corrosion resistance. Furthermore, this invention provides a method for preparing the hard optical thin film. This method is simple, can be fully automated, allows for large-scale production, is environmentally friendly, energy-saving, and low-carbon, and has wide applicability. The aforementioned thin film can be applied to next-generation communication terminals, offering advantages such as low cost, high performance, and long warranty period.

[0004] Specifically, the present invention provides the following technical solution:

[0005] A rigid optical thin film, wherein the thin film is an optical thin film having a nano-biphase structure.

[0006] In this invention, "nano-biphase structure" refers to the simultaneous presence of nanocrystalline and amorphous structures in the microstructure of a thin film.

[0007] According to one embodiment of the present invention, the visible light transmittance of the film is 90% or more; specifically, the visible light transmittance can be as high as 100%. Exemplarily, it can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%.

[0008] According to one embodiment of the present invention, the hardness of the film is 10 GPa or higher. Exemplarily, it can be 10 GPa, 10.5 GPa, 11 GPa, 11.5 GPa, 12 GPa, 12.1 GPa, 12.2 GPa, 12.5 GPa or higher.

[0009] According to one embodiment of the present invention, the material constituting the thin film is selected from at least one of oxides or nitrides of metal alloys. Specifically, the metal alloy can form an amorphous structure; exemplaryly, it can be at least one of metal alloys capable of forming amorphous structures, such as MgZnCa alloy, MgCuY alloy, ZrTiFe alloy, and AlNiY alloy.

[0010] According to one embodiment of the present invention, the thickness of the thin film can be from 50 nm to 5000 nm. Exemplarily, it can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 500 nm, 1000 nm, 2000 nm, 3000 nm, 4000 nm or 5000 nm.

[0011] The present invention also provides a composite film comprising a substrate layer and the aforementioned rigid optical thin film located on one side surface of the substrate layer.

[0012] According to one embodiment of the present invention, the substrate layer is selected from 3D printed glass or ceramic, soft substrate (such as a film suitable for mobile phone screens) or flexible ultra-thin glass, etc.

[0013] The present invention also provides the use of the composite film, which can be used as a mobile phone screen, back panel or optical lens, etc.

[0014] The present invention also provides a method for preparing the above-mentioned hard optical thin film, the method comprising the following steps:

[0015] 1) The material that forms the hard optical thin film, referred to as the target material, is loaded into the target material position of the magnetron sputtering coating machine;

[0016] 2) Place the substrate material into the magnetron sputtering coating machine;

[0017] 3) Evacuate the coating machine to a vacuum state, adjust the power, and introduce argon (Ar) gas to perform plasma pretreatment on the substrate material;

[0018] 4) Adjust the power, introduce argon (Ar) and reactive gas, and deposit a film to form the hard optical thin film on the surface of the substrate material after plasma pretreatment.

[0019] This invention employs an economical, environmentally friendly, and efficient magnetron sputtering coating technology to prepare the aforementioned hard optical thin film. Magnetron sputtering, as a thin film preparation method, allows for the dense growth of thin film materials on various substrate materials, including materials with complex shapes or soft, ultra-thin properties such as 3D printed glass or ceramics, soft substrates (e.g., films suitable for mobile phone screens), or flexible ultra-thin glass. Furthermore, it ensures high adhesion between the thin film and the substrate. This invention utilizes automated control of magnetron sputtering to process various substrates, depositing a layer of optical thin film with high light transmittance (visible light transmittance) and excellent mechanical properties, featuring a nano-biphase structure, on the substrate surface. In addition to maintaining the high light transmittance of the substrate, it significantly improves the substrate's hardness and resistance to wear and corrosion.

[0020] Specifically, the thin film prepared by magnetron sputtering in this invention has a band gap in its valence band structure that is greater than the ultraviolet light energy value, allowing it to transmit light waves in the visible light band. By controlling the specific parameters of the reactive sputtering process (i.e., step 4 above), the formation structure of the material, as well as the valence band and defects, can be controlled, thereby obtaining a thin film with at least 90% visible light transmittance as described in this application.

[0021] According to one embodiment of the present invention, in step 1), the target material is selected from a metal alloy. The metal alloy can form an amorphous structure; for example, it can be at least one of the metal alloys that can form an amorphous structure, such as MgZnCa alloy, MgCuY alloy, ZrTiFe alloy, and AlNiY alloy.

[0022] According to one embodiment of the present invention, the target material can be pre-treated before being installed in the target material position of the magnetron sputtering coating machine. Specifically, the pre-treatment includes: grinding, cleaning (specifically, ultrasonic cleaning), and drying. Specifically, the grinding involves using sandpaper to remove the surface layer of the target material. Specifically, the ultrasonic cleaning can be performed in acetone, ethanol, and deionized water, respectively.

[0023] According to one embodiment of the present invention, the target material used in step 1) requires precise calculation of the component ratio to form an optical thin film with a nanoscale dual-phase structure and optimal composition and / or structure. Specifically, taking MgZnCa as an example, the atomic ratio of Mg to the other two metals can be (40-60):(60-40), for example, 40:60, 45:55, 50:50, 55:45 or 60:40; the atomic ratio between Zn and Ca can be (10-5):1, for example, 10:1, 9:1, 8:1, 7:1, 6:1 or 5:1; exemplaryly, the atomic ratio of the three can be 60:35:5, but is not limited to this.

[0024] According to one embodiment of the present invention, in step 3), the plasma pretreatment process requires precise control of the sputtering power and / or the Ar partial pressure within the chamber. Specifically, the power can be controlled between 200 and 800 W, but is not limited thereto, and the Ar partial pressure within the chamber can be controlled between 60% and 80%, but is not limited thereto.

[0025] According to one embodiment of the present invention, in step 3), the flux of Ar can be controlled at 30-50 sccm; for example, it can be 30 sccm, 35 sccm, 40 sccm, 45 sccm or 50 sccm.

[0026] According to one embodiment of the present invention, in step 3), the vacuum degree of the vacuum state is 10. -3 -10 -9 torr.

[0027] According to one embodiment of the present invention, in step 4), depending on the target material, by controlling the partial pressure of Ar, the partial pressure of the reaction gas (such as oxygen O2 or nitrogen N2), the sputtering power, the temperature, and other conditions, the bombardment efficiency of plasma and electrons on the target material can be controlled, so that the substrate material and the thin film are firmly bonded. The microstructure of the thin film (in addition to having a nano-dual-phase structure, it also includes the above-mentioned valence band structure, defects, etc.) can also be controlled to obtain the expected visible light transmittance and mechanical properties.

[0028] Specifically, step 4) includes: adjusting the sputtering power, controlling the temperature, and simultaneously introducing Ar and O2 or N2 for coating, forming the hard optical thin film on the surface of the substrate material after plasma pretreatment. Specifically, the temperature is controlled from room temperature to 1000 degrees Celsius. Specifically, the sputtering power can be controlled between 200 and 800 W, but is not limited to this. Specifically, the partial pressure of Ar in the chamber can be controlled between 60% and 80%, but is not limited to this, and the partial pressure of the reactant gas in the chamber can be controlled between 20% and 40%, but is not limited to this.

[0029] According to one embodiment of the present invention, in step 4), the flux of Ar can be controlled at 30-50 sccm; for example, it can be 30 sccm, 35 sccm, 40 sccm, 45 sccm or 50 sccm.

[0030] According to one embodiment of the present invention, in step 4), the flux of the reaction gas can be controlled at 5-30 sccm; for example, it can be 5 sccm, 10 sccm, 15 sccm, 20 sccm, 25 sccm or 30 sccm.

[0031] The principle of this invention is as follows: A magnetron sputtering coating technique is used to coat the surface of a substrate material. In step 4), by controlling the sputtering power and adjusting the sputtering rate of the target atoms, a high-transparency hard film layer of suitable thickness is formed. Furthermore, by controlling the partial pressure of Ar and the partial pressure of the reactant gas, a thin film with a nanoscale dual-phase structure is formed. This invention forms a high-transparency thin film with a nanoscale dual-phase structure using magnetron sputtering, which not only improves the mechanical properties, wear resistance, and corrosion resistance of the substrate but also exhibits high visible light transmittance. Further, this invention includes a plasma pretreatment step (step 3) of the substrate material before coating. The purpose of this step is to remove surface impurity atoms from the substrate material and improve the adhesion between the substrate material and the thin film.

[0032] The present invention has the following advantages:

[0033] 1. This invention provides a hard optical film with a nano-biphase structure, adjustable thickness, high visible light transmittance and hardness, and a smooth and uniform surface, which has great application potential.

[0034] 2. The present invention uses magnetron sputtering to prepare the hard optical thin film on the surface of a substrate material. The resulting film has a high bonding force with the substrate material, which gives the substrate material high hardness, strong wear resistance, and a certain degree of corrosion resistance.

[0035] 3. The present invention employs magnetron sputtering technology to prepare the hard optical thin film on substrates of different materials, and the thin film has high visible light transmittance, thereby protecting the substrate material while retaining the original optical properties of the substrate material (such as high visible light transmittance).

[0036] 4. The substrate material of the present invention can be a soft substrate, and the composite film prepared therefrom can be bent multiple times while maintaining high visible light transmittance and mechanical protection, making it particularly suitable for mobile phone screens and other fields. Attached Figure Description

[0037] Figure 1 Photographs of the rigid optical film of the present invention deposited on PI material in Embodiment 2 of the present invention after being bent 10,000 times: uncoated PI (left), PI with the film of the present invention deposited (middle), and PI with metal film deposited (right).

[0038] Figure 2 An optical microscope image (without creases) of the hard optical film of the present invention deposited on PI material after 10,000 bending cycles in Embodiment 2 of the present invention.

[0039] Figure 3 The visible light transmittance of the rigid optical thin film in Embodiment 2 of the present invention;

[0040] Figure 4Nanoindentation loading hardness test of hard optical thin film in Embodiment 2 of the present invention;

[0041] Figure 5 Transmission micrograph of the hard optical thin film of the present invention in Embodiment 2 of the present invention. Detailed Implementation

[0042] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0043] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0044] In this invention, the visible light transmittance is measured using a UV-Vis spectrophotometer, and the sample size is 20*20mm. 2 Sample (film) thickness: 200nm~800nm.

[0045] In this invention, the hardness is determined by nanoindentation using a nanoindenter, wherein the indentation depth is at least 1 / 10 of the material thickness. Sample size: 20*20mm 2 Sample (film) thickness: 200nm~800nm.

[0046] Example 1

[0047] (1) Using a MgZnCa alloy (where the atomic ratio of Mg, Zn, and Ca is 60:35:5) as the target material, the target material is pretreated as follows: after sanding off the surface layer with sandpaper, it is ultrasonically cleaned and dried in acetone, ethanol, and deionized water, respectively. The pretreated target material is then loaded into the target position of the magnetron sputtering coating machine.

[0048] (2) The flexible PET substrate (e.g., a plastic sheet with a thickness of 100μm) is placed in ethanol and deionized water and ultrasonically cleaned for 20-30 minutes to remove surface impurities and obtain a clean substrate material, which is then placed in a magnetron sputtering coating machine.

[0049] (3) The coating machine is evacuated to 10°C. -3 -10 -9Under a vacuum state, the power is adjusted, and Ar is introduced to perform plasma pretreatment on the substrate material. The purpose is to remove impurities from the target surface (impurities refer to oil, dust, etc. adhering to the target surface; these are removed through pretreatment to ensure the purity of sputtered atoms) and improve the adhesion between the substrate material and the thin film. Specifically, the power is controlled at 450W, the partial pressure of Ar is 65%, and the Ar flux is 40 sccm.

[0050] (4) After pretreatment, perform coating treatment. Adjust the power and temperature, which can be selected from room temperature to 1000 degrees Celsius, while simultaneously introducing Ar and O2 or N2 for coating. The power is controlled at 320W; the Ar flux is 40 sccm, the O2 (N2) flux is 10 sccm, the partial pressure of Ar is controlled at 65%, and the partial pressure of O2 or N2 is controlled at 35%.

[0051] The thin film prepared by this invention has a nanoscale dual-phase structure, specifically as follows: Figure 5 As shown.

[0052] The film thickness was measured to be 50-5000 nm.

[0053] Tests showed that the average transmittance of the film in the visible light range was over 90%.

[0054] The film was tested and found to have a hardness of 12.2 GPa.

[0055] Example 2

[0056] The difference from Example 1 is that in step (2), a soft material PI film is selected as the substrate material to replace the flexible material PET substrate in Example 1; the rest is the same as in Example 1.

[0057] The film thickness was measured to be 100-5000 nm.

[0058] like Figure 1 The images show photos after 10,000 bends, with uncoated PI (left), PI coated with the rigid optical thin film of the present invention (middle) from Example 2, and PI coated with a metal film (right). As can be seen from the images, the untreated PI film (left) exhibits significant deformation after 10,000 bends and cannot be restored to its original shape; while the coated PI films (middle and right) have higher rigidity. Furthermore, the PI film coated with the rigid optical thin film of the present invention has higher transparency. Specifically... Figure 1 The middle and right images clearly show that the middle image is translucent, displaying the color of the base PI (brown), while the right image shows the silvery-white color characteristic of metal and is opaque.

[0059] like Figure 2An optical microscope image of the rigid optical film of the present invention deposited on PI material in Example 2 after being bent 10,000 times with a bending radius of 1 mm, shows that the film has no creases or cracks.

[0060] like Figure 3 The average visible light transmittance of the hard optical magnesium zinc calcium oxide film of the present invention in Example 2 is above 90%.

[0061] like Figure 4 The hardness of the rigid optical magnesium zinc calcium oxide film of the present invention in Example 2 is 12.2 GPa.

[0062] like Figure 5 The transmission micrograph of the hard optical thin film of the present invention in Example 2 shows that the film has a nanocrystalline (blue area) and an amorphous (orange area) structure, that is, a nano-biphase structure.

[0063] The exemplary embodiments of the present invention have been described above. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite membrane, characterized in that, The composite film includes a substrate layer and a rigid optical thin film located on one side surface of the substrate layer; The substrate layer is selected from a soft substrate or flexible ultrathin glass; The hard optical thin film is an optical thin film with a nano-dual structure; having a nano-dual structure means that the microstructure of the thin film simultaneously contains nanocrystalline and amorphous structures. The material constituting the thin film is selected from at least one of oxides or nitrides of metal alloys, wherein the metal alloy can form an amorphous structure, and the metal alloy is at least one of MgZnCa alloy, MgCuY alloy, ZrTiFe alloy, AlNiY alloy, etc., which are metal alloys capable of forming amorphous structures; The visible light transmittance of the film is over 90%; The film has a hardness of 10 GPa or higher; The composite membrane is prepared by a method comprising the following steps: 1) The target material is loaded into the target material position of the magnetron sputtering coating machine; wherein, the target material is the material for forming the hard optical thin film, and is selected from metal alloys; 2) Place the substrate material into the magnetron sputtering coating machine; 3) Evacuate the coating machine to a vacuum state, adjust the power, and introduce argon (Ar) gas to perform plasma pretreatment on the substrate material; 4) Adjust the sputtering power and control the temperature, while simultaneously introducing Ar and reactive gases O2 or N2 to deposit a film, forming the hard optical thin film on the surface of the substrate material after plasma pretreatment; In step 3), the plasma pretreatment process requires precise control of the sputtering power and the Ar partial pressure within the chamber; the power is controlled between 200 and 800 W, and the Ar partial pressure within the chamber is controlled between 60% and 80%. In step 4), the sputtering power is controlled at 200-800W; the partial pressure of Ar in the chamber is controlled at 60%-80%; the partial pressure of the reaction gas in the chamber is controlled at 20%-40%; the Ar flux is controlled at 30-50 sccm; and the reaction gas flux is controlled at 5-30 sccm.

2. The composite membrane according to claim 1, characterized in that, The film has a hardness of 10.5 GPa, 11 GPa, 11.5 GPa, 12 GPa, 12.1 GPa, 12.2 GPa, 12.5 GPa or higher.

3. The composite membrane according to claim 1, characterized in that, The thickness of the film is 50 nm to 5000 nm.

4. The composite membrane according to claim 1, characterized in that, The soft substrate is a film suitable for mobile phone screens.

5. The composite membrane according to claim 1, characterized in that, The soft substrate is a flexible PET substrate or a soft PI film.

6. The use of the composite membrane according to any one of claims 1-5, characterized in that, The composite film is used as a mobile phone screen, back panel, or optical lens.

7. A method for preparing the composite membrane according to any one of claims 1-5, characterized in that, The method includes the following steps: 1) The target material is loaded into the target material position of the magnetron sputtering coating machine; wherein, the target material is the material for forming the hard optical thin film, and is selected from metal alloys; 2) Place the substrate material into the magnetron sputtering coating machine; 3) Evacuate the coating machine to a vacuum state, adjust the power, and introduce argon (Ar) gas to perform plasma pretreatment on the substrate material; 4) Adjust the sputtering power and control the temperature, while simultaneously introducing Ar and reactive gases O2 or N2 to deposit a film, forming the hard optical thin film on the surface of the substrate material after plasma pretreatment; In step 3), the plasma pretreatment process requires precise control of the sputtering power and the Ar partial pressure within the chamber; the power is controlled between 200 and 800 W, and the Ar partial pressure within the chamber is controlled between 60% and 80%. In step 4), the sputtering power is controlled between 200 and 800 W; In step 4), the partial pressure of Ar in the chamber is controlled at 60% to 80%, and the partial pressure of the reaction gas in the chamber is controlled at 20% to 40%. In step 4), the Ar flux is controlled at 30-50 sccm; the reactant gas flux is controlled at 5-30 sccm.

8. The method according to claim 7, characterized in that, In step 4), the temperature is controlled from room temperature to 1000 degrees Celsius.

9. The method according to claim 7, characterized in that, In step 3), the vacuum level in the vacuum state is 10. -3 -10 -9 torr.

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