A method for preparing a hydrophilic magnesium fluoride film based on magnetron sputtering

Abstract

The application belongs to the field of optical film and surface engineering, and provides a hydrophilic magnesium fluoride film preparation method based on magnetron sputtering, which realizes effective regulation and control of the hydrophilic performance of the magnesium fluoride film surface through sputtering power and maintains good optical transmittance. In the application, first, the substrate is subjected to ultrasonic cleaning treatment, then the substrate is placed in a vacuum chamber of a magnetron sputtering device, magnesium fluoride is used as target material, and the vacuum chamber is vacuumized to a base vacuum degree; then, inert gas is introduced into the vacuum chamber, the sputtering power is adjusted to 20-50 W, and the magnesium fluoride film is deposited on the substrate surface in a radio frequency magnetron sputtering mode; the application realizes continuous regulation and control of the hydrophilic performance of the magnesium fluoride film surface by regulating and controlling the sputtering power; with the increase of the sputtering power, the surface roughness of the film increases, the water contact angle significantly decreases, and the hydrophilicity is enhanced; and the method does not introduce additional materials, has simple process and good repeatability, and the prepared magnesium fluoride film maintains high transmittance in the visible light range.

Description

Technical Field

[0001] This invention belongs to the field of optical thin films and surface engineering, specifically providing a method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering. By controlling the sputtering power, the hydrophilic properties of the magnesium fluoride thin film surface are optimized while maintaining its good optical transmittance. Background Technology

[0002] Magnesium fluoride (MgF2), as an important optical thin film material, possesses advantages such as a wide transmittance range, low refractive index, good mechanical strength, and chemical stability, and is widely used in anti-reflective coatings, optical windows, laser components, and optoelectronic devices. With the development of optoelectronic technology and biomedical detection, higher requirements are being placed on the wetting properties of thin film surfaces. Especially in applications such as microfluidic chips, self-cleaning optical components, and biosensors, hydrophilic surfaces are more conducive to liquid spreading, reduce light scattering, and improve detection sensitivity.

[0003] Currently, the main methods for preparing magnesium fluoride thin films include thermal evaporation, electron beam evaporation, and magnetron sputtering. Among them, magnetron sputtering technology has advantages such as dense film formation, strong adhesion, and good process repeatability, and is widely used in the preparation of high-quality optical thin films. However, magnesium fluoride thin films prepared by traditional magnetron sputtering usually exhibit hydrophobic properties, which limits their application in scenarios with high hydrophilicity requirements.

[0004] To address this issue, existing technologies for improving the hydrophilicity of thin films primarily focus on surface modification, plasma treatment, or doping with other hydrophilic materials. However, these methods are often complex, unstable, or adversely affect the optical properties of the film. Therefore, developing a method for preparing magnesium fluoride thin films with controllable hydrophilicity through process parameter adjustment without altering the material system has significant application value. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering. By adjusting the sputtering power, the hydrophilic properties of the magnesium fluoride thin film surface can be effectively controlled while maintaining good optical transmittance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering, characterized by comprising the following steps:

[0008] Step 1. Perform ultrasonic cleaning on the substrate to remove surface contaminants, dry it with nitrogen gas, and then dry it in a clean environment for later use.

[0009] Step 2. Place the cleaned substrate in the vacuum chamber of the magnetron sputtering equipment, use magnesium fluoride as the target material, and evacuate to the background vacuum level;

[0010] Step 3. Inert gas is introduced into the vacuum chamber, the sputtering power is adjusted, and a magnesium fluoride thin film is deposited on the substrate surface using radio frequency magnetron sputtering.

[0011] Step 4. After deposition, cool and remove the film to obtain a hydrophilic magnesium fluoride film.

[0012] Furthermore, in step 1, the substrate is a transparent optical substrate, including but not limited to glass, quartz, sapphire, polymethyl methacrylate, and polycarbonate.

[0013] Furthermore, in step 1, the cleaning process involves ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water in sequence, followed by drying with nitrogen gas.

[0014] Furthermore, in step 2, the background vacuum level is lower than 5.0 × 10⁻⁶. -5 Pa.

[0015] Furthermore, in step 3, the inert gas is argon, and the gas flow rate is 20~50 sccm.

[0016] Furthermore, in step 3, the sputtering power is 20~50 W, and the sputtering power is negatively correlated with the water contact angle on the surface of the magnesium fluoride film. The higher the sputtering power, the smaller the water contact angle and the stronger the hydrophilicity.

[0017] Furthermore, in step 3, the sputtering pressure is 0.2~1.0 Pa and the sputtering time is 0.5~1h.

[0018] Furthermore, in step 4, the thickness of the magnesium fluoride film is 20~50 nm.

[0019] Furthermore, in step 4, the average transmittance of the magnesium fluoride film in the visible light range is not less than 90%.

[0020] Based on the above technical solution, the beneficial effects of the present invention are as follows:

[0021] This invention provides a method for preparing a hydrophilic magnesium fluoride thin film by magnetron sputtering. By controlling the sputtering power, the hydrophilicity of the magnesium fluoride film surface can be continuously adjusted. As the sputtering power increases, the surface roughness of the film increases, the water contact angle decreases significantly, and the hydrophilicity is enhanced. This method does not introduce additional materials, has a simple process, good repeatability, and the prepared magnesium fluoride film maintains high transmittance in the visible light range. It is suitable for fields such as optical components, microfluidic chips, and biosensors, where both hydrophilicity and light transmittance are required. Attached Figure Description

[0022] Figure 1 This is a graph showing the variation of the water contact angle of the magnesium fluoride thin film under various sputtering powers according to an embodiment of the present invention.

[0023] Figure 2 This is a graph showing the change in water contact angle of the magnesium fluoride thin film prepared by thermal evaporation in the comparative example of this invention.

[0024] Figure 3 The images show the surface morphology of magnesium fluoride thin films under various sputtering powers according to embodiments of the present invention, obtained by atomic force microscopy (AFM).

[0025] Figure 4 The images show the transmission spectra of magnesium fluoride thin films at various sputtering powers according to embodiments of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] Example 1

[0028] This embodiment provides a method for preparing a hydrophilic magnesium fluoride thin film by magnetron sputtering, specifically including the following steps:

[0029] The glass substrate was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 15 min in sequence, dried with clean nitrogen and then placed in the vacuum chamber of the magnetron sputtering equipment.

[0030] Magnesium fluoride with a purity of 99.99% was used as the target material, and the vacuum was evacuated to a background vacuum level of less than 5.0 × 10⁻⁶. -5 Pa; Argon gas was introduced at a flow rate of 30 sccm, sputtering pressure was 0.5 Pa, sputtering power was set to 20 W, 30 W, 40 W and 50 W respectively, magnesium fluoride thin film was deposited by radio frequency magnetron sputtering, and sputtering time was 30 min for each.

[0031] After deposition, the sample was cooled and removed to obtain magnesium fluoride thin film samples with different sputtering powers.

[0032] The beneficial effects of the present invention will be described in detail below with reference to characterization tests. In order to more intuitively demonstrate the beneficial effects of the present invention, a comparative example is also provided: under the same conditions, magnesium fluoride thin films were prepared by thermal evaporation and contact angle tests were performed.

[0033] The water contact angles of the magnesium fluoride films prepared under different sputtering powers were tested, and the results are as follows: Figure 1 As shown, with the sputtering power increasing from 20 W to 50 W, the water contact angle gradually decreased from 33° to 13°, indicating a significant enhancement in the hydrophilicity of the film. Water contact angle tests were performed on magnesium fluoride films prepared by thermal evaporation, and the results are as follows: Figure 2 As shown, its water contact angle is 63°, and its hydrophilicity is significantly lower than that of the film prepared by magnetron sputtering.

[0034] The surface morphology of the thin film was characterized using atomic force microscopy, and the results are as follows: Figure 3 As shown, with the increase of sputtering power, the surface roughness of the film gradually increases, which is beneficial to improving hydrophilicity.

[0035] The transmittance of the thin film in the visible light range was tested using a UV-Vis spectrophotometer, and the results are as follows: Figure 4 As shown, the average transmittance of all samples in the wavelength range of 400~800 nm is not less than 90%, indicating that magnesium fluoride films maintain good optical transmittance under different sputtering powers.

[0036] In summary, this invention achieves effective control of the hydrophilicity of magnesium fluoride thin films by adjusting the magnetron sputtering power without affecting their optical transmittance, making it suitable for various optical and microfluidic applications.

[0037] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering, characterized in that, Includes the following steps: Step 1. Perform ultrasonic cleaning on the substrate to remove surface contaminants, dry it with nitrogen gas, and then dry it in a clean environment for later use. Step 2. Place the cleaned substrate in the vacuum chamber of the magnetron sputtering equipment, use magnesium fluoride as the target material, and evacuate to the background vacuum level; Step 3. Inert gas is introduced into the vacuum chamber, and the sputtering power is adjusted to 20~50 W. A magnesium fluoride thin film is deposited on the substrate surface using radio frequency magnetron sputtering. Step 4. After deposition, cool and remove the film to obtain a hydrophilic magnesium fluoride film.

2. The method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering according to claim 1, characterized in that, In step 1, the substrate is a transparent optical substrate, including: glass, quartz, sapphire, polymethyl methacrylate and polycarbonate.

3. The method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering according to claim 1, characterized in that, In step 1, the cleaning process involves ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water in sequence, followed by drying with nitrogen gas.

4. The method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering according to claim 1, characterized in that, In step 2, the background vacuum level is lower than 5.0 × 10⁻⁶. -5 Pa.

5. The method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering according to claim 1, characterized in that, In step 3, the inert gas is argon, and the gas flow rate is 20~50 sccm.

6. The method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering according to claim 1, characterized in that, In step 3, the sputtering power is negatively correlated with the water contact angle on the surface of the magnesium fluoride film. The higher the sputtering power, the smaller the water contact angle and the stronger the hydrophilicity.

7. The method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering according to claim 1, characterized in that, In step 3, the sputtering pressure is 0.2~1.0 Pa and the sputtering time is 0.5~1h.

8. The method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering according to claim 1, characterized in that, In step 4, the thickness of the magnesium fluoride film is 20~50 nm.

9. The method for preparing hydrophilic magnesium fluoride thin films based on magnetron sputtering according to claim 1, characterized in that, In step 4, the average transmittance of the magnesium fluoride film in the visible light range is not less than 90%.

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