Optical coating method for preventing deformation and warping of substrate and optical filter
By alternately depositing stress-counteracting films on the front and back sides of the substrate, the problem of deformation and warping of thin substrates during ultra-multilayer coating is solved, achieving substrate flatness and accurate spectral indicators, and reducing production costs.
Patent Information
- Application Number
- CN202411300012.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-18
- Publication Date
- 2026-03-20
AI Technical Summary
When performing ultra-multilayer film deposition on a large-area thin substrate, the substrate is prone to warping due to stress deformation, which leads to optical path deflection and spectral degradation. Existing methods such as thickening the substrate or cutting small pieces have problems of exceeding size limits or increasing costs.
The target spectrum of the optical filter is decomposed into first and second spectra. First and second films are deposited on the front and back sides of the substrate, respectively, so that the stress of the two films cancels each other out. Films are deposited alternately on the front and back sides of the substrate using an alternating deposition method. The film thickness is monitored using a flipping mechanism and a quartz crystal film thickness gauge.
It effectively prevents substrate deformation and warping, keeps the substrate flat, reduces substrate size and weight, reduces production costs, and at the same time ensures the accuracy and consistency of spectral indicators.
Smart Images
Figure CN121700339A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of optical coating production, in particular to an optical coating method for preventing substrate deformation and warping and an optical filter. BACKGROUND
[0002] In the coating process of the optical filter with super multi-layer optical film, the stress increases with the number of layers and the thickness accumulation, and there is a huge tensile stress in the film layer when the coating is completed. Under the action of the tensile stress, the film layer has a shrinkage trend, which causes the glass substrate closely attached to the film layer to also be deformed and warped, and is no longer an ideal parallel flat plate. In severe cases, even a large area of thin substrate can be broken due to bending beyond the elastic limit of the glass. Figure 1 As shown in the figure, the optical path of the substrate-deformed filter is no longer parallel incidence when used, the incidence angle is no longer 0 degrees, the optical path is deflected, and the spectral index is seriously deteriorated. Especially on a substrate with a large size and area, the total stress is greater, and the amount of substrate deformation caused is also greater.
[0003] In the current production of super multi-layer film products, two methods are generally used to avoid deformation caused by stress: 1. Thicken the substrate, and the thickness of the substrate reaches 1 cm, which has higher substrate strength to resist the stress of the film layer and prevent warping deformation. But the negative effect is that the size and weight of the large-area filter product may exceed the standard, and the thick substrate in the imaging system will also introduce aberration.
[0004] 2. Use small-size filters, cut small pieces after coating the thick substrate, and then thin the processing method to reduce stress and prevent deformation. However, this increases the process and cost, and the small aperture also limits the application of small-size filters in some situations.
[0005] Therefore, overcoming the defects of the prior art is an urgent problem to be solved in the technical field. SUMMARY
[0006] The technical problem to be solved by the present application is the problem of easy deformation of the substrate during the coating of super multi-layer film on a large-area thin substrate.
[0007] The present application adopts the following technical solutions:
[0008] In a first aspect, the present application provides an optical coating method for preventing substrate deformation and warping, comprising:
[0009] decomposing the target spectrum of the optical filter into a first spectrum and a second spectrum;
[0010] designing a first film layer according to the first spectrum and a second film layer according to the second spectrum;
[0011] The first film layer is deposited on the front surface of the substrate, and the second film layer is deposited on the back surface of the substrate, and the stress applied to the substrate by the first film layer and the stress applied to the substrate by the second film layer are counteracted.
[0012] Preferably, the first film layer and the second film layer each include at least one sub-film.
[0013] The first film layer is deposited on the front surface of the substrate, and the second film layer is deposited on the back surface of the substrate, and the stress applied to the substrate by the first film layer and the stress applied to the substrate by the second film layer are counteracted.
[0014] The first film layer is deposited on the front surface of the substrate, and the second film layer is deposited on the back surface of the substrate, and the stress applied to the substrate by the first film layer and the stress applied to the substrate by the second film layer are counteracted.
[0015] When the thickness of the first sub-film of the first film layer reaches the design requirement, the substrate is flipped, and the first sub-film of the second film layer is deposited on the back surface of the substrate.
[0016] When the thickness of the first sub-film of the first film layer reaches the design requirement, the substrate is flipped, and the first sub-film of the second film layer is deposited on the back surface of the substrate.
[0017] Preferably, a film deposition machine with a flipping mechanism is used to deposit films on the substrate, and the flipping mechanism is used to flip the substrate.
[0018] A quartz crystal film thickness meter is used to monitor the thickness of each sub-film.
[0019] Preferably, the difference in thickness between the first film layer and the second film layer is less than a preset thickness difference, and the difference in the number of layers between the first film layer and the second film layer is less than a preset number of layer difference.
[0020] Preferably, the first film layer is a long-wave pass filter film, and the second film layer is a short-wave pass filter film.
[0021] The long-wave pass filter film allows light with a wavelength greater than a set wavelength f0 to pass through, and light with a wavelength less than the set wavelength f0 is cut off.
[0022] The short-wave pass filter film allows light with a wavelength greater than a set wavelength f1 to be cut off, and light with a wavelength less than the set wavelength f1 to pass through.
[0023] The wavelength f1 is greater than the wavelength f0, and the wavelength range that the optical filter can transmit is equal to f1-f0.
[0024] Preferably, evaporation film deposition or sputtering film deposition is used to deposit the corresponding film layer.
[0025] Preferably, the first film layer and the second film layer are each composed of a high-refractive material and a low-refractive material.
[0026] Preferably, the thickness of the substrate is 0.5mm-1mm.
[0027] In a second aspect, the present application provides an optical filter, which comprises a substrate, a first film layer and a second film layer, the first film layer is arranged on the front surface of the substrate, the second film layer is arranged on the back surface of the substrate, and the spectrum of the superposition of the first film layer and the second film layer is the same as the target spectrum of the optical filter.
[0028] The stress applied to the substrate by the first film layer and the stress applied to the substrate by the second film layer are mutually offset.
[0029] Preferably, the optical filter is a band-pass filter.
[0030] Compared with the prior art, the present application has the beneficial effects that the super multi-layer film originally deposited on the same surface of the substrate is divided into the first film layer and the second film layer, the first film layer is deposited on the front surface of the substrate, and the second film layer is deposited on the back surface of the substrate, which reduces the possibility of substrate deformation caused by excessive stress due to the deposition of the super multi-layer film on the same surface of the substrate, and makes the stress applied to the substrate by the first film layer and the stress applied to the substrate by the second film layer close to equal, so as to ensure that the substrate remains flat after the deposition of the first film layer and the second film layer on the front surface and the back surface respectively.
[0031] In the preferred scheme, the method of alternately depositing the sub-films in the first film layer and the second film layer is adopted, which avoids the deformation of the substrate in the film deposition process caused by the deposition of the first film layer before the deposition of the second film layer, and further ensures the flatness of the substrate in the film deposition process. BRIEF DESCRIPTION OF DRAWINGS
[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.
[0033] Figure 1 is a schematic diagram of the deformation of the substrate caused by excessive stress according to the embodiments of the present application;
[0034] Figure 2 is a schematic diagram of the whole process of the optical film coating method for preventing the deformation and warping of the substrate according to the embodiments of the present application;
[0035] Figure 3 is a schematic diagram of the optical filter obtained by the method according to the embodiments of the present application; Figure 2
[0036] Figure 4 is a schematic diagram of the long-wave pass filter film spectrum of the first film layer on the front surface of the substrate of the optical film coating method for preventing substrate deformation and warping provided by the embodiment of the present application; Figure 2 is a schematic diagram of step 3 of the method shown in the figure;
[0037] Figure 5 is a schematic diagram of the long-wave pass filter film spectrum of the first film layer on the front surface of the substrate of the optical film coating method for preventing substrate deformation and warping provided by the embodiment of the present application; Figure 4 is a schematic diagram of the long-wave pass filter film spectrum of the first film layer on the front surface of the substrate of the optical film coating method for preventing substrate deformation and warping provided by the embodiment of the present application;
[0038] Figure 6 is a schematic diagram of the long-wave pass filter film spectrum of the first film layer on the front surface of the substrate of the optical film coating method for preventing substrate deformation and warping provided by the embodiment of the present application;
[0039] Figure 7 is a schematic diagram of the long-wave pass filter film spectrum of the first film layer on the front surface of the substrate of the optical film coating method for preventing substrate deformation and warping provided by the embodiment of the present application;
[0040] Figure 8 is a schematic diagram of the long-wave pass filter film spectrum of the first film layer on the front surface of the substrate of the optical film coating method for preventing substrate deformation and warping provided by the embodiment of the present application; Figure 6 and Figure 7 spectrum superposition schematic diagram;
[0041] Figure 9 is a schematic diagram of the long-wave pass filter film spectrum of the first film layer on the front surface of the substrate of the optical film coating method for preventing substrate deformation and warping provided by the embodiment of the present application; Figure 8 band-pass filter spectrum schematic diagram formed after combination;
[0042] Figure 10 is a schematic diagram of an optical filter produced by the optical film coating method for preventing substrate deformation and warping provided by the embodiment of the present application;
[0043] Figure 11 is a top view of the optical film coating device for preventing substrate deformation and warping provided by the embodiment of the present application;
[0044] Figure 12 is a schematic diagram of the electron beam evaporation assembly of the optical film coating device for preventing substrate deformation and warping provided by the embodiment of the present application;
[0045] Figure 13 is a front view of the optical film coating device for preventing substrate deformation and warping provided by the embodiment of the present application;
[0046] Figure 14 is a schematic diagram of the electron beam evaporation assembly and the reaction magnetron sputtering group of the optical film coating device for preventing substrate deformation and warping provided by the embodiment of the present application. DETAILED DESCRIPTION
[0047] In order to make the objects, technical solutions and advantages of the present application clearer, the following further describes the present application with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present application and not to limit the present application.
[0048] Unless otherwise required by context, the term "comprises" or "comprising" throughout the specification and claims, is to be construed as open-ended terminology i.e. as "including, but not limited to". In describing and claiming the present disclosure, the terms "one embodiment", "some embodiments", "an exemplary embodiment", "an example", "a specific example" or "some examples" are intended to mean that a certain feature, structure, material, or characteristic is included in at least one embodiment or example of the present disclosure, and is used as a term of description, not a term of limitation. The exemplary representations of the above terms are not necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics can be included in any one or more embodiments or examples in any appropriate manner, i.e. although they can be carried by the embodiments or examples of the above terms due to the order of appearance and location, they are not limited to be carried by one embodiment or example in a combined manner.
[0049] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present disclosure and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present disclosure.
[0050] In the description of the present application, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, the meaning of "a plurality of" is two or more. In addition, for example, in the description, the same type of nouns can also be described as two independent individuals by adding "A", "B" at the end, in which case the features limited by "A", "B" are only used for the purpose of distinguishing the same type of individual description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.
[0051] In describing some embodiments, use is made of "coupled," "coupling," and "connected," and variations thereof. For example, the term "connected" is used to mean that two or more components are in direct physical or electrical contact with each other. As another example, the term "coupled" is used to mean that two or more components are in either direct physical or electrical contact with each other, or that two or more components are not in direct contact with each other, but yet still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited in scope to the exemplary descriptions provided herein.
[0052] In the description of the present application, the expression "A and / or B" (wherein A and B represent specific features) is used to represent the following three combinations: A alone, B alone, and a combination of A and B.
[0053] As used herein, "about," "approximately," or "substantially" means an acceptable range of error for a given value or measurement that is understood by one of ordinary skill in the art to which the disclosure pertains, which will vary from context to context, and which can be determined based on the measurement techniques used by those of ordinary skill in the art and the error inherent in the measurement system at hand.
[0054] Furthermore, the technical features involved in each of the embodiments of the present application described below can be combined with each other as long as there is no conflict.
[0055] Embodiment 1:
[0056] Embodiment 1 of the present application provides an optical coating method for preventing deformation and warping of a substrate, as shown in Figure 2 The optical coating method comprises the following steps:
[0057] In step 1, the target spectrum of the optical filter is decomposed into a first spectrum and a second spectrum.
[0058] In step 2, a first film layer is designed according to the first spectrum, and a second film layer is designed according to the second spectrum.
[0059] Specifically, the target spectrum of the target filter is decomposed into the product superposition of two spectra, i.e., the product superposition of the first spectrum and the second spectrum, through computer-aided film system design. Then, the film system is designed according to the decomposed spectra, i.e., a first film layer is designed according to the first spectrum, and a second film layer is designed according to the second spectrum. The number of layers and the thickness of the film system corresponding to each spectrum are approximately designed. The designed film system is simultaneously deposited on both surfaces of the thin substrate glass. The light passes through the surfaces of the first film layer and the second film layer in sequence, and the target spectrum of the target filter is obtained after the superposition of the spectra.
[0060] In step 3, the first film layer is deposited on the front side of the substrate, and the second film layer is deposited on the back side of the substrate. The stress exerted by the first film layer on the substrate and the stress exerted by the second film layer on the substrate cancel each other out.
[0061] Compared with existing technologies, the ultra-multilayer film, which was originally deposited entirely on the same side of the substrate, is decomposed into a first film layer and a second film layer. The first film layer is deposited on the front side of the substrate and the second film layer is deposited on the back side of the substrate, respectively. This reduces the possibility of excessive stress and substrate deformation caused by depositing the entire ultra-multilayer film on the same side of the substrate. At the same time, it makes the stress exerted on the substrate by the first film layer and the second film layer nearly equal, ensuring that the substrate stress is basically balanced and remains flat after the first film layer and the second film layer are deposited alternately on the front and back sides of the substrate.
[0062] For ultra-multilayer optical thin films (typically >100 layers, total thickness >20µm), stress increases cumulatively with the number of layers and thickness during the coating process. Upon completion of the coating, significant stress exists within the film layers (>>10µm). 4 N / cm 2 For the tantalum oxide / silica film combination commonly used in optical filters, the total stress is generally tensile stress. Under huge tensile stress, the film layer tends to shrink, which can cause the glass substrate tightly attached to the film layer to deform and warp, no longer being an ideal parallel plate. In severe cases, it can even cause large areas of thin substrates to crack due to bending exceeding the elastic limit of glass. Figure 1 As shown, when a filter with a deformed substrate is used, the optical path is no longer parallel to the incident light, the incident angle is no longer 0 degrees, the optical path is deflected, and the spectral performance deteriorates severely. Specifically, this manifests as a shift in the center wavelength of the filter, unevenness with surface position, a worse curve shape, and increased optical loss. Especially on substrates with larger areas, the total stress is greater, resulting in greater substrate deformation. Therefore, a first film layer is deposited on the front side of the substrate, and a second film layer is deposited on the back side. The stress exerted on the substrate by the first film layer and the stress exerted on the substrate by the second film layer cancel each other out, as... Figure 3 As shown, the internal shrinkage tensile stress of the film layers deposited simultaneously on both surfaces of the substrate is basically the same, and the forces on both sides of the substrate reach equilibrium, so no more deformation or warping occurs.
[0063] Therefore, in step 3 above, the deposition method of the first film layer and the second film layer can be the following preferred embodiment: both the first film layer and the second film layer include at least one sub-film; the first film layer is deposited on the front side of the substrate, and the second film layer is deposited on the back side of the substrate, such as... Figure 4 As shown, it includes:
[0064] In step 30, a first sub-film of the first film layer is deposited on the front side of the substrate.
[0065] In step 31, when the thickness of the first sub-film of the first film layer is monitored to meet the design requirements, the substrate is flipped over, and the first sub-film of the second film layer is deposited on the back side of the substrate.
[0066] In step 32, when the thickness of the first sub-film of the second film layer is monitored to meet the design requirements, the substrate is flipped over, and the second sub-film of the first film layer is deposited on the front side of the substrate. The corresponding film layers are deposited on the front and back sides of the substrate in sequence by means of alternating film deposition.
[0067] That is, in this embodiment, after each subfilm is deposited on one side of the substrate, the substrate is flipped over and the subfilm is deposited on the other side of the substrate.
[0068] like Figure 5 As shown, the coating process is repeated in alternating cycles using steps 30-32 above to obtain the final first film layer located on the front side of the substrate and the second film layer located on the back side of the substrate.
[0069] By employing an alternating deposition method for sub-films in the first and second film layers, substrate deformation during the deposition process is avoided, which would otherwise result from depositing the first film layer first and then the second film layer. This further ensures the flatness of the substrate during the substrate deposition process.
[0070] In the preferred coating scheme described above, after depositing one sub-film of a first film layer, the substrate needs to be flipped to deposit another sub-film. For each sub-film in the first and second film layers, the corresponding film layer is deposited by evaporation or sputtering. Evaporation and sputtering optical coatings are both physical vapor deposition. The deposited film molecules move directionally from the crucible or target to the substrate surface under vacuum conditions, depositing only on the surface of the substrate currently being deposited and not diffracting to the other side of the substrate. Therefore, a coating machine with a flipping mechanism is used to coat the substrate, with the flipping mechanism driving the substrate to flip; during the deposition of each sub-film layer, a quartz crystal film thickness gauge is used to monitor the thickness of each sub-film. After each sub-film layer is deposited on the front side of the substrate, the substrate is flipped using a flipping mechanism to deposit a sub-film layer on the back side. Once the back side sub-film layer is deposited, the substrate is flipped back to the front side to deposit the next sub-film layer, and so on, until all film layers are deposited on both sides of the substrate. This ensures that the accumulated shrinkage tensile stress on both surfaces of the substrate is essentially the same, resulting in a balanced substrate that will not bend or deform. This eliminates the need for ultra-thick glass substrates to counteract stress, reducing substrate size and weight, and lowering costs. The flipping mechanism is driven by a servo motor.
[0071] In this design, to ensure that the accumulated shrinkage tensile stress on the two surfaces of the substrate is essentially the same, the thickness difference between the first and second film layers is less than a preset thickness difference, and the difference in the number of layers between the first and second film layers is less than a preset number of layers difference. In one embodiment, the thickness difference can be 0-5 μm, and the number of layers can be 0-20 layers.
[0072] To achieve precise spectral control and selective transmission, the first film layer is a long-pass filter, and the second film layer is a short-pass filter. The long-pass filter allows light with wavelengths greater than a set wavelength f0 to pass through, while blocking light with wavelengths less than f0. The short-pass filter allows light with wavelengths greater than a set wavelength f1 to pass through, while blocking light with wavelengths less than f1. Where f1 is greater than f0, the wavelength range that the optical filter can transmit is equal to f1-f0. In one embodiment, the difference between f1 and f0 can be 1–50 nm. Figures 6-9 The diagram shown illustrates the spectral superposition process of the first and second films in one embodiment. Figure 6 The spectrum of the long-pass filter film in the first film layer on the front side of the substrate. Figure 7 The spectrum of the short-pass filter film, the second film layer on the back of the substrate, is shown. Figure 8 To be Figure 6 and Figure 7 A schematic diagram of spectral superposition. Figure 9 for Figure 8 The combined bandpass filter spectrum is as follows: The long-pass filter allows light waves with wavelengths greater than a certain cutoff wavelength to pass through while blocking shorter wavelengths. This characteristic enables the effective filtering of unwanted short-wavelength light in applications requiring specific long-wavelength light, thereby improving the signal strength of the target wavelength band. Conversely, the short-pass filter allows light waves with wavelengths less than a certain cutoff wavelength to pass through while blocking longer wavelengths, thus enhancing the signal of the target wavelength band and reducing background noise. The design of depositing a long-pass filter on the front side of the substrate and a short-pass filter on the back side achieves fine-tuning of the spectrum and selective transmission, filtering out unwanted short-wavelength and long-wavelength light, thereby significantly improving the signal quality of the target wavelength band.
[0073] Both the first and second films are composed of high-refractive-index and low-refractive-index materials. The high-refractive-index materials can be germanium (Ge), titanium dioxide (TiO2), tantalum pentoxide (Ta2O5), etc., while the low-refractive-index materials can be aluminum oxide (Al2O3) and silicon dioxide (SiO2), etc. Compared to existing technologies that use substrates with higher strength, even reaching a thickness of 1 cm, to counteract film stress and prevent substrate warping, the method provided in this invention can reduce the substrate thickness to 0.5–1 mm, thereby significantly reducing the size and weight of the substrate and playing a positive role in reducing production costs.
[0074] Example 2:
[0075] This invention is carried out according to the optical coating method for preventing substrate deformation and warping provided in Example 1, resulting in an optical filter, such as... Figure 10 As shown, the optical filter includes a substrate 1, a first film layer 2, and a second film layer 3. The first film layer 2 is disposed on the front side of the substrate 1, and the second film layer 3 is disposed on the back side of the substrate 1. The spectrum of the first film layer 2 and the second film layer 3 superimposed is the same as the target spectrum of the optical filter. The stress exerted by the first film layer 2 on the substrate 1 and the stress exerted by the second film layer 3 on the substrate 1 cancel each other out. Specifically, the optical filter is a bandpass filter.
[0076] For details on other structures and manufacturing methods of optical filters, please refer to the foregoing embodiments, which will not be repeated here.
[0077] Example 3:
[0078] This invention provides an optical coating apparatus for preventing substrate deformation and warping, applied to an optical coating method for preventing substrate deformation and warping as described in Embodiment 1. Figure 11 , Figure 12 and Figure 13 As shown, the optical coating apparatus for preventing substrate deformation and warping includes: an electron beam evaporation assembly 4, a reactive magnetron sputtering assembly 5, an ion source 6, a heater 7, and a flipping mechanism 8. The ion source 6 provides high-energy plasma clusters and a stable discharge environment to the electron beam evaporation assembly 4 and the reactive magnetron sputtering assembly 5, and the heater 7 heats the equipment cavity. In practical applications, only one of the electron beam evaporation assembly 4 and the reactive magnetron sputtering assembly 5 operates at any given time.
[0079] like Figure 12 As shown, the electron beam evaporation assembly 4 is provided with at least two crucibles 40, and the at least two crucibles 40 are respectively filled with the raw materials required for film deposition; the reactive magnetron sputtering assembly 5 is provided with a target material 50; asFigure 13 As shown in the figure, the substrate 1 is fixed on the turnover mechanism 8, and the turnover mechanism 8 drives the substrate 1 to turn over. The substrate 1 is located above the electron beam evaporation assembly 4 and the reactive magnetron sputtering assembly 5. The turnover mechanism 8 includes a servo motor (not shown in the figure), and the turnover mechanism 8 is driven by the servo motor. The device also includes a quartz crystal film thickness monitor 9 for monitoring the thickness of each sub-film in the first film layer and the second film layer.
[0080] Specifically, as shown in the figure, Figure 12 The electron beam evaporation assembly 4 includes an electron gun emission assembly 41, a crucible bearing plate 42, and a crucible base 43. The crucible bearing plate 42 is arranged on the crucible base 43, at least two crucibles 40 are arranged on the crucible bearing plate 42, and the electron gun emission assembly 41 is arranged on the side of the crucible base 43. The main function of the electron gun emission assembly 41 is to generate, focus, and accelerate hot electrons to provide necessary energy and conditions for the subsequent evaporation process. In the electron gun emission assembly 41, the accelerating electrode in the electron gun applies an electric field to the electron beam, so that the electrons obtain higher energy and speed. When the electron beam enters the crucible 40, its kinetic energy can be more effectively converted into heat energy, so that the material to be evaporated is instantaneously heated to an extremely high temperature.
[0081] As shown in the figure, Figure 14 The reactive magnetron sputtering assembly 5 includes a magnetron sputtering target gun column 51 and an anode cover 52. The magnetron sputtering target gun column 51 is arranged below the anode cover 52, the target material 50 is placed in the anode cover 52, and the anode cover 52 is grounded. The magnetron sputtering target gun column 51 serves as a support structure for the target material 50 to ensure that the target material 50 maintains a stable position and state during sputtering. Secondly, the magnetron sputtering target gun column 51 has a built-in magnetic field that controls the motion of metal particles in the target material 50. The magnetic field causes the metal atoms on the surface of the target material 50 to form a particle stream, i.e., a sputtering beam, and focuses and accelerates these sputtering particles, thereby improving sputtering efficiency.
[0082] In addition to the above structure, as shown in the figure, Figure 14 The electron beam evaporation assembly 4 is sequentially provided with a first quartz crystal film thickness monitor 44, a first correction plate 45, and a first coating baffle 46 from top to bottom. The reactive magnetron sputtering assembly 5 includes a second quartz crystal film thickness monitor 53, a second correction plate 54, and a second coating baffle 55 sequentially arranged from top to bottom.
[0083] The first quartz crystal film thickness monitor 44 is used to monitor the thickness of the sub-film of the first film layer 2 and the second film layer 3, and the first correction plate 45 is used to ensure the uniformity of the thickness of the sub-film of the first film layer 2 and the second film layer 3. Specifically, in the process of electron beam evaporation coating, the main function of the first correction plate 45 is to adjust the spatial distribution of the material generated by the electron beam evaporation. The first correction plate 45 shields and disperses the evaporation material emitted by the evaporation source, mainly shielding the evaporation material directly above the evaporation source, thereby reducing the thickness of the glass film layer of the substrate 1 in this area, so that the evaporation material can form a more uniform distribution when it reaches the substrate 1. In this way, the optical film on the substrate 1 can obtain a more uniform thickness. The design of the correction plate usually needs to be accurately calculated and optimized according to the characteristics of the evaporation source, the size and shape of the substrate 1, and the required film thickness distribution.
[0084] The first coating baffle 46 is used to prevent the film material from moving onto the substrate 1 during pre-melting of the film material. Specifically, before formal coating, the electron beam evaporation assembly 4 will pre-melt the film material. During the pre-melting process, the film material may be sputtered. Therefore, before the electron beam evaporation assembly 4 coats, the first coating baffle 46 blocks the substrate 1 to prevent the film material from being sputtered onto the substrate 1 during pre-melting.
[0085] The second quartz crystal film thickness monitor 53 is used to monitor the thickness of the sub-film of the first film layer 2 and the second film layer 3, and the second correction plate 54 is used to ensure the uniformity of the film thickness of the sub-film of the first film layer 2 and the second film layer 3. Specifically, in reactive magnetron sputtering, the sputtered material particles are deflected under the action of the magnetic field. The second correction plate 54 can further adjust the deposition position of these particles on the substrate 1 to achieve a more uniform distribution. The design of the correction plate needs to consider factors such as the magnetic field distribution, the size and shape of the sputtering source, and the characteristics of the substrate 1. By adjusting the shape, size and position of the correction plate, effective control of the distribution of sputtered material can be achieved, thereby improving the uniformity of the optical film.
[0086] The second coating baffle 55 is used to prevent the film material from moving onto the substrate 1 during pre-melting of the film material. Pre-sputtering is an important step in the process of reactive magnetron sputtering. After the working gas is filled into the vacuum chamber of the device, the ion source 6 is electrified. Instead of directly sputtering onto the substrate 1, the second coating baffle 55 blocks the substrate 1 to perform pre-sputtering. The main purpose is to fully remove the oxides and other impurities on the surface of the target material 50 to ensure the purity of the target material 50 during sputtering, thereby improving the quality of film formation.
[0087] In the coating process, the biggest problem of the reaction magnetron sputtering coating and the electron beam evaporation mixed coating is the electromagnetic interference between the two systems, which mainly occurs in the gap of the two systems alternately coating, and the interference can cause the ion source 6 to stop in the middle of starting, and destroy the balance of the coating system. In order to solve this problem, an electromagnetic shielding system is introduced into the device. As shown in Figure 14 The outer side of the electron beam evaporation assembly 4 is provided with a first electromagnetic shielding cover 47, and the height of the first electromagnetic shielding cover 47 is higher than the height of the film material; the outer side of the reaction magnetron sputtering assembly 5 is provided with a second electromagnetic shielding cover 56, and the height of the second electromagnetic shielding cover 56 is higher than the height of the target material 50. Without the first electromagnetic shielding cover 47 and the second electromagnetic shielding cover 56, the electron conduction is slow, which can affect the normal starting of the ion source 6. The so-called starting of the ion source 6 is that in the working process of the ion source 6, after the ion bombards the surface of the substrate 1, the ion releases electrons from the surface of the substrate 1 to form an electron cloud, and then the electron cloud forms a plasma under the action of an external electric field, thereby completing the process of gas discharge. When the coating starts, the first electromagnetic shielding cover 47 and the second electromagnetic shielding cover 56 are sleeved outside the coating system, and the shielding cover can absorb excess electrons and lead into the ground, so as to maintain the normal operation of the coating. Figure 14 The first electromagnetic shielding cover 47 and the second electromagnetic shielding cover 56 shown in the above are the same in structure and shape, and the difference between them is that the sizes of the two are different due to the different sizes of the electron beam evaporation assembly 4 and the reaction magnetron sputtering assembly 5, which will not be repeated here.
[0088] The above only describes the preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. An optical coating method for preventing substrate deformation and warping, characterized in that, include: The target spectrum of the optical filter is decomposed into a first spectrum and a second spectrum; The first film layer is designed according to the first spectrum, and the second film layer is designed according to the second spectrum. The first film layer is deposited on the front side of the substrate, and the second film layer is deposited on the back side of the substrate, wherein the stress exerted by the first film layer on the substrate and the stress exerted by the second film layer on the substrate cancel each other out.
2. The optical coating method for preventing substrate deformation and warping according to claim 1, characterized in that, Both the first membrane layer and the second membrane layer include at least one sub-membrane; The deposition of the first film layer on the front side of the substrate and the deposition of the second film layer on the back side of the substrate include: A first sub-film of the first film layer is deposited on the front side of the substrate; When the thickness of the first sub-film of the first film layer is detected to meet the design requirements, the substrate is flipped over, and the first sub-film of the second film layer is deposited on the back side of the substrate. When the thickness of the first sub-film of the second film layer is monitored to meet the design requirements, the substrate is flipped over, and the second sub-film of the first film layer is deposited on the front side of the substrate. The corresponding film layers are deposited on the front and back sides of the substrate in sequence by means of alternating film deposition.
3. The optical coating method for preventing substrate deformation and warping according to claim 2, characterized in that, A coating machine with a flipping mechanism is used to coat the substrate, and the flipping mechanism is used to flip the substrate. The thickness of each sub-film was monitored using a quartz crystal film thickness gauge.
4. The optical coating method for preventing substrate deformation and warping according to any one of claims 1-3, characterized in that, The thickness difference between the first film layer and the second film layer is less than a preset thickness difference value, and the difference in the number of layers between the first film layer and the second film layer is less than a preset number of layers difference value.
5. The optical coating method for preventing substrate deformation and warping according to any one of claims 1-3, characterized in that, The first film layer is a long-pass filter film, and the second film layer is a short-pass filter film; The long-pass filter film allows light with a wavelength greater than the set wavelength f0 to pass through, while blocking light with a wavelength less than the set wavelength f0. The short-pass filter film allows light with a wavelength greater than the set wavelength f1 to be blocked, while light with a wavelength less than the set wavelength f1 can pass through. Where wavelength f1 is greater than wavelength f0, the range of wavelengths that the optical filter can transmit is equal to f1-f0.
6. The optical coating method for preventing substrate deformation and warping according to any one of claims 1-3, characterized in that, The corresponding film layer is deposited by evaporation or sputtering.
7. The optical coating method for preventing substrate deformation and warping according to any one of claims 1-3, characterized in that, Both the first film layer and the second film layer are composed of high-refractive-index materials and low-refractive-index materials.
8. The optical coating method for preventing substrate deformation and warping according to any one of claims 1-3, characterized in that, The thickness of the substrate is 0.5 mm to 1 mm.
9. An optical filter, characterized in that, The optical filter includes a substrate, a first film layer, and a second film layer. The first film layer is disposed on the front side of the substrate, and the second film layer is disposed on the back side of the substrate. The spectrum of the first film layer and the second film layer superimposed is the same as the target spectrum of the optical filter. The stress exerted by the first film layer on the substrate and the stress exerted by the second film layer on the substrate cancel each other out.
10. The optical filter according to claim 9, characterized in that, The optical filter is a bandpass filter.