A high-power laser processing dust-proof protective film layer and its preparation method

Abstract

The present invention discloses a high-power laser processing dustproof protective film and its preparation method. The film layer structure is: SUB / k1Hk2Lk3M / A, where SUB represents the JGS1 substrate, A represents air, H represents Ta2O5, L represents SiO2, and M represents diamond film. k1-k3 represents the coefficient of the optical thickness of each layer at one-quarter of the reference wavelength (1064nm), with k1 ranging from 0.3 to 0.4, k2 ranging from 1.2 to 1.4, and k3 ranging from 0.1 to 0.2. The high-power laser processing dustproof protective film of the present invention has a transmittance of over 99.99% in the 1064nm band, low absorption, a roughness of less than 5A, a smooth surface topography, resistance to wipes, high temperatures, metal sputtering, and dust absorption, significantly extending the service life of existing laser processing protective windows.

Description

Technical Field

[0001] The invention relates to a high-power laser processing dust-proof protective film layer and a preparation method thereof, belonging to the technical field of laser processing dust-proof protective films. Background Art

[0002] Laser processing utilizes the energy of light, which is focused by a lens to a high energy density at the focal point, and relies on the photothermal effect to achieve this. Laser processing requires no tools, is fast, and minimizes surface deformation, making it suitable for processing a wide range of materials.

[0003] Burn-in on protective windows is a common problem in high-power laser processing applications. The root cause is that the protective window, as the outermost lens element, is most susceptible to contamination, attracting dirt, which leads to overheating in the contaminated area and burn-in. Therefore, the development of a dust-proof protective window is urgent. To this end, the inventors combined ion-assisted electron beam evaporation and PECVD film deposition technologies to produce a high-power, ultra-smooth dust-proof protective window with low absorption and a roughness of less than 5A. Summary of the Invention

[0004] The present invention provides a high-power laser processing dust-proof protective film layer and a preparation method thereof, which has the advantages of being resistant to wipes, high temperatures, metal sputtering, and dust absorption, and can significantly improve the service life of the current laser processing protection window.

[0005] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] A high-power laser processed dust-proof protective film layer has a film structure of: SUB / k1Hk2Lk3M / A, where SUB represents a JGS1 substrate, A represents air, H represents Ta2O5, L represents SiO2, and M represents a diamond film; k1-k3 represent coefficients of the optical thickness of each layer at a quarter of a reference wavelength (1064 nm), with k1 ranging from 0.3 to 0.4, k2 ranging from 1.2 to 1.4, and k3 ranging from 0.1 to 0.2.

[0007] The selection of materials and thicknesses for each layer of the present application is very important. It must not only meet the requirements of high transmittance and low absorption, but also meet the requirements of being dust-resistant and resistant to wiping. This requires consideration of the mutual influence between the film layer and the substrate, and between the film layers. It is not a simple combination of high and low refractive indices. Although some film materials have excellent performance individually, when paired together, stress mismatch, poor adhesion, and poor wiping resistance will occur. At the same time, the selection of thickness is also very critical. Improper thickness not only directly affects the transmittance and absorptivity, but also affects the degree of bonding between the film layers and wiping resistance. The inventors have found through research that many materials cannot simultaneously take into account low absorption and roughness. For example, when HfO2 does not use an RF source, its weak absorption is very small, but the surface roughness of the film layer will deteriorate compared to the substrate before coating, and the surface morphology will be rough, which is easy to absorb dust. After researching and selecting numerous materials, we discovered that TA2O5, when assisted by an RF source, exhibits absorption similar to that of HfO2. The surface roughness of the film is reduced compared to the substrate before coating, and the surface morphology is smooth. Furthermore, it exhibits a significant promoting effect and strong bonding with SiO2 and diamond films, resulting in a film that simultaneously achieves high transmittance, low absorption, low dust absorption, and abrasion resistance. Therefore, this application selected a specific film combination: SiO2 / TA2O / diamond film. This further reduces contamination from molten metal particles and enhances high-temperature resistance, while also improving the film's abrasion resistance.

[0008] The preferred film structure of the high-power laser processing dust-proof protective film layer is: A / k3Mk2Lk1H / SUB / k1Hk2Lk3M / A.

[0009] In order to take into account mechanical properties, optical properties and dust-proof properties, the physical thickness of the k1H layer is 20-50nm, the physical thickness of the k2L layer is 200-300nm, and the physical thickness of the k3M layer is 10-30nm.

[0010] The above-mentioned high-power laser processing dust-proof protective film layer is prepared by: using a radio frequency ion source assisted electron beam thermal evaporation method, a Ta2O5 layer and a SiO2 layer are sequentially evaporated on a fused quartz substrate in a vacuum chamber, and high-purity oxygen with a purity greater than 99.99% is introduced into the vacuum chamber.

[0011] In order to improve adhesion, the above film forming temperature is 200-300°C.

[0012] In order to take into account both the optical and mechanical properties of the film and improve the flatness of the film, the oxygen flow rate is 30-100 sccm when plating the Ta2O5 layer, and the oxygen flow rate is 5-80 sccm when plating the SiO2 layer.

[0013] The evaporation rate of the above-mentioned Ta2O5 is 0.1-0.4nm / s, and the evaporation rate of SiO2 is 0.1-1.5nm / s.

[0014] When the ion source is assisted, the beam voltage is set to 800-1200 V, the beam current is set to 800-1200 mA, and the acceleration voltage is controlled at 400-800 V.

[0015] The diamond film is prepared by chemical vapor deposition. Before the diamond film is deposited (after the Ta2O5 layer and SiO2 layer are evaporated), it needs to be annealed. The annealing temperature is controlled at 200-700°C and the annealing time is controlled at 1-8 hours.

[0016] The technologies not mentioned in this invention are all referred to the prior art.

[0017] The high-power laser processing dust-proof protective film layer of the present invention has a transmittance of more than 99.99% in the 1064nm band, low film absorption, roughness below 5A, smooth surface morphology, scratch resistance, high temperature resistance up to 3300°C, resistance to metal sputtering, and not easy to absorb dust, which can significantly improve the service life of the current laser processing protection window. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural diagram of the dust-proof protective film layer processed by high-power laser processing of the present invention;

[0019] Figure 2 This is a design drawing of the dust-proof protective film layer processed by high-power laser processing of the present invention;

[0020] Figure 3 This is a spectrum detection diagram of the dust-proof protective film layer processed by high-power laser of the present invention;

[0021] Figure 4 This is the surface roughness test diagram of the JGS1 substrate of the present invention (before plating);

[0022] Figure 5 This is a surface roughness test diagram of the dust-proof protective film layer processed by high-power laser of the present invention (after plating);

[0023] Figure 6 This is a surface morphology detection image of the dust-proof protective film layer processed by high-power laser of the present invention (after plating);

[0024] Figure 7 This is a weak absorption detection image of the JGS1 substrate of the present invention (before plating);

[0025] Figure 8 This is a weak absorption detection diagram of the dust-proof protective film layer processed by high-power laser of the present invention (after plating); DETAILED DESCRIPTION

[0026] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0027] Example 1

[0028] like Figure 1 As shown in the figure, the structure of a high-power laser processed dust-proof protective film layer is: A / k3Mk2Lk1H / SUB / k1Hk2Lk3M / A, where SUB represents the JGS1 substrate, A represents air, H represents TA2O5, L represents SIO2, and M represents diamond film; k1-k3 represent the coefficients of the optical thickness of one-quarter reference wavelength (1064nm) of each layer, which are 0.38 / 1.1 / 0.1 respectively, and the physical thicknesses of k1H, k2L and k3M are 49.55nm, 201.84nm, and 12.65nm respectively.

[0029] The preparation of the above-mentioned high-power laser processing dust-proof protective film layer is as follows:

[0030] 1. Evaporation environment maintenance: This mainly targets the key factors that cause damage in laser thin films (absorption and defects in the film). By adding an isolation baffle between the evaporation source and the substrate, it blocks and absorbs ineffective evaporation materials, thereby reducing contamination near the substrate and the probability of film defect formation.

[0031] 2. Ultrasonic cleaning: removes microscopic particles attached to the surface of the substrate.

[0032] 3. Thin film preparation: The antireflection film is deposited on the fused quartz substrate by using the method of electron beam thermal evaporation assisted by a radio frequency ion source. High-purity oxygen (purity better than 99.99%) is introduced into the vacuum chamber to fully oxidize the deposited material under high vacuum conditions, reducing the absorption of the film, thereby increasing the laser damage threshold. This method not only retains the unique favorable properties of the electron beam thermal evaporation method for preparing laser thin films, but also improves the intrinsic absorption and defect density of the film. It is highly targeted, high-quality, and simple to use. The oxygen flow rate is 50 sccm when plating Ta2O5, and the oxygen flow rate is 0.01 sccm when plating SiO2. The ion source is assisted by a beam voltage of 800 V and a beam current of 800 mA, and the acceleration voltage is controlled at 400-800 V. After the dielectric film is plated, it is annealed at 250 ° C for 2 hours, ultrasonically cleaned, and a thin layer of diamond film is plated using PECVD (plasma assisted chemical vapor deposition) equipment.

[0033] Test results:

[0034] Optical performance test: The double-sided transmittance was tested using a spectrophotometer (model: Belarus PHOTO RT), and the measured T1064 was above 99.99%. Figure 3 .

[0035] Surface roughness test: Atomic force microscope (AFM model FM-Nanoview1000) was used to test the roughness of the sample. The test result of the polished piece was Ra=4.4A, and the test result of the finished product was Ra=4.8A. Figure 4-6 shown.

[0036] Weak absorption test: Use a weak absorption meter (model PCI-1064 / 355-3D50M) to test the sample for weak absorption. The test result of the polished sheet is 0.99ppm, and the result of the finished product is 1.24ppm. Figure 7-8 shown.

[0037] To ensure the reliability of optical components, the following environmental tests were conducted on the broadband antireflection coating sample in accordance with the requirements of GJB2485-95 General Specification for Optical Coatings:

[0038] (1) Abrasion resistance test. Wrap two layers of dry degreased gauze around the rubber friction head and rub the film along the same trajectory under a pressure of 4.9N for 100 times. The film has no scratches or other damage. The film after the above test is tested again using a friction tester (DZ-8103, Dongguan Dazhong Instrument Co., Ltd.). After 5000 times of friction, the film still has no scratches or other damage, which does not affect the transmittance and film performance.

[0039] (2) Adhesion test: Use a 2 cm wide adhesive tape with a peel strength of I > 2.94 N / cm to adhere to the surface of the film layer. After quickly pulling the tape from the edge of the part toward the surface in a direction perpendicular to the surface, the film layer will not fall off or be damaged. Repeat 30 times, and the film layer will not fall off or be damaged.

[0040] (3) Immersion test: The sample is completely immersed in distilled water or deionized water. After 3-36 hours, the film layer does not show new defects such as peeling, delamination, cracks, and blistering.

[0041] Conclusion: This paper adopts ultrasonic-assisted cleaning technology. Through the rational selection and use of film materials, combined with RF source assistance and annealing treatment, the obtained film layer has both good spectral performance and good mechanical stability. The transmittance of the antireflection film in the 1064 band can reach more than 99.99%, weak absorption is 1.24ppm, the roughness is below 5A, it is resistant to wipes and metal sputtering, and is not easy to absorb dust, which can significantly improve the service life of the current laser processing protection window.

[0042] The above-mentioned film layer is resistant to high temperature and metal sputtering. In the actual application process of the laser, molten metal chips are often splashed. The temperature is too high and the conventional film layer is easily burned. This product adds a layer of diamond film on the outermost layer with a melting point of 3300℃, which can effectively prevent the film layer from being damaged.

[0043] Comparative Example 1

[0044] The structure of a high-power laser-processed dust-proof protective film layer is: A / k3Mk2Lk1H / SUB / k1Hk2Lk3M / A, where SUB represents the JGS1 substrate, A represents air, H represents HfO2, L represents SIO2, and M represents the diamond film. k1-k3 represent the coefficients of the optical thickness of each layer at one-quarter the reference wavelength (1064nm), which are 0.35 / 1.3 / 0.15, respectively. When plating HfO2, the oxygen flow rate is 50sccm, the HfO2 evaporation rate is 0.2nm / s, and the rest is the same as in Example 1. That is, the only difference between this example and Example 1 is that TA2O5 is replaced with HfO2. The transmittance is 99.8%, the surface roughness is 11A, the weak absorption is 1.37ppm, and the friction resistance is 25.

[0045] Comparative Example 2

[0046] A high-power laser-processed dust-proof protective film has the following structure: A / k3Mk2Lk1H / SUB / k1Hk2Lk3M / A, where SUB represents the JGS1 substrate, A represents air, H represents TA2O5, L represents SiO2, and M represents the diamond film. k1-k3 represent the coefficients of the optical thickness of each layer at one-quarter the reference wavelength (1064 nm): 1.3 / 0.35 / 0.15, respectively. The preparation was similar to Example 1; the only difference between this example and Example 1 is the reversal of the k1-2 coefficients. The resulting transmittance was 58%, which does not meet application requirements.

[0047] Comparative Example 3

[0048] The difference from Example 1 is that the evaporation rate of Ta2O5 is 0.5 nm / s, and the rest is the same as Example 1. The transmittance is 93.8%.

Claims

1. A high-power laser processing dust-proof protective film layer, characterized by: The film structure is: SUB / k1Hk2Lk3M / A, where SUB represents the JGS1 substrate, A represents air, H represents Ta2O5, L represents SiO2, and M represents diamond film; k1-k3 represent the coefficients of the quarter reference wavelength optical thickness of each layer, with k1 ranging from 0.3 to 0.4, k2 ranging from 1.2 to 1.4, and k3 ranging from 0.1 to 0.2; The physical thickness of the k1H layer is 20-50 nm, the physical thickness of the k2L layer is 200-300 nm, and the physical thickness of the k3M layer is 10-30 nm; the reference wavelength is 1064 nm.

2. The high-power laser processing dust-proof protective film layer according to claim 1, characterized in that: The membrane layer structure is: A / k3Mk2Lk1H / SUB / k1Hk2Lk3M / A.

3. The method for preparing a high-power laser processing dust-proof protective film layer according to claim 1 or 2, characterized in that: Using a radio frequency ion source assisted electron beam thermal evaporation method, Ta2O5 layers and SiO2 layers are sequentially deposited on a fused quartz substrate in a vacuum chamber. High-purity oxygen with a purity greater than 99.99% is introduced into the vacuum chamber. The evaporation rate of Ta2O5 is 0.1-0.4nm / s, and the evaporation rate of SiO2 is 0.1-1.5nm / s.

4. The preparation method according to claim 3, wherein: The film forming temperature is 200-300℃.

5. The preparation method according to claim 3 or 4, characterized in that: When plating the Ta2O5 layer, the oxygen flow rate is 30-100 sccm, and when plating the SiO2 layer, the oxygen flow rate is 5-80 sccm.

6. The preparation method according to claim 3 or 4, characterized in that: When the ion source is assisted, the beam voltage is set to 800-1200 V, the beam current is set to 800-1200 mA, and the acceleration voltage is controlled at 400-800 V.

7. The preparation method according to claim 3 or 4, wherein: After the Ta2O5 layer and the SiO2 layer are evaporated, they are annealed at 200-700°C for 1-8 hours, and then a diamond film is prepared by chemical vapor deposition.

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