A coating equipment and a linear gradient filter film thickness uniformity correction method

Abstract

The application relates to a coating equipment and a linear gradient filter film thickness uniformity correction method, and solves the problem that the film thickness uniformity of a linear gradient filter prepared by using an existing deposition method of electron beam evaporation cannot be corrected. A revolution correction plate is arranged below a workpiece disc, the revolution correction plate rotates with the workpiece disc around the center of a rotating disc, the workpiece disc has self-rotation motion, the film thickness distribution of Ta2O5 and SiO2 is corrected to the middle linearity by the revolution correction plate, at this time, the film thickness distribution of Ta2O5 and SiO2 after being corrected by the revolution correction plate has not reached the final target, and the difference from the final target is respectively corrected for the second time by a first fixed correction plate and a second fixed correction plate, so that the film thickness distribution of Ta2O5 and SiO2 finally reaches the final target, and the film thickness distribution of Ta2O5 and SiO2 is corrected to the film thickness distribution state required by the linear gradient filter by the combination of the revolution correction plate and the fixed correction plate.

Description

Technical Field

[0001] This invention relates to coating equipment and a method for correcting film thickness uniformity, specifically to a coating equipment and a method for correcting the film thickness uniformity of a linear gradient filter. Background Technology

[0002] Spectral imaging technology, as an application of spectral detection technology, cleverly combines spectral detection and imaging techniques. It is a "spectral-image fusion" technology that can obtain and image the spectral curve of a target, and has a wide range of applications. Spectral imaging technology can be classified in various ways. Based on its different spectral resolution capabilities, it can be divided into multispectral imaging technology, hyperspectral imaging technology, and superspectral imaging technology.

[0003] The light signals transmitted through a spectral imaging system are all polychromatic light. If spectral information detection and analysis are to be performed on each pixel of an image, then the polychromatic light needs to be dispersed. Based on different dispersion methods, spectral imaging techniques can be divided into: dispersive spectral imaging, interferometric spectral imaging, and filter-based spectral imaging. Research on filter-based spectral imaging began in the 1990s. Its main principle relies on thin-film filters as dispersive elements. Different spectral channels can be obtained by changing multiple sets of thin-film filters with different passbands. Compared with dispersive and interferometric spectral imaging techniques, filter-based spectral imaging has a simpler structure and, while maintaining excellent spectral performance, offers advantages in integration and miniaturization.

[0004] To achieve higher spectral resolution, wider operating range, and higher integration in spectral detection technology, researchers have proposed using linear graded filters as spectroscopic elements. A linear graded filter is a highly integrated spectroscopic element in which multiple layers of SiO2 and Ta2O5 films are alternately deposited on one side of a substrate. Different positions of the linear graded filter correspond to different optical properties, and the changes in optical properties are related to the position of the substrate.

[0005] As a beam splitter, a linear graded filter has the ability to convert incident polychromatic light into monochromatic light of different wavelengths. Furthermore, due to its optical properties, it can achieve simple and rapid beam splitting. By coupling it with array detectors, beam splitting detection functions can be integrated and miniaturized. When using a linear graded filter as a beam splitter, the volume can be reduced to one-third of that of a traditional beam splitter while maintaining the same technical specifications. It offers advantages such as small size, high transmittance, and the ability to arbitrarily design the passband position.

[0006] Currently, researchers are using ion beam sputtering deposition to correct the film thickness distribution of Ta₂O₅ and SiO₂ in linear graded filters using two correction plates. This has resulted in linear graded filters with a size of 12 mm and a working range of 520 nm to 1000 nm. However, this technology is costly and not suitable for large-scale production. Another deposition method, electron beam evaporation, is emerging, but further research is needed on methods to correct the film thickness uniformity of linear graded filters prepared using electron beam evaporation. Summary of the Invention

[0007] The purpose of this invention is to solve the technical problem that it is difficult to correct the film thickness uniformity of linear graded filters prepared by existing electron beam evaporation deposition methods, and to provide a coating equipment and a method for correcting the film thickness uniformity of linear graded filters.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] A coating equipment, which is special in that:

[0010] This includes a vacuum coating machine and a revolution correction plate;

[0011] The vacuum coating machine includes a vacuum chamber, a rotating disk, a workpiece disk, a fixed correction plate, and an evaporation source. The rotating disk is rotatably disposed on the inner top surface of the vacuum chamber, and the workpiece disk is rotatably disposed at the bottom of the rotating disk with its rotation center offset from the rotation center of the rotating disk. The workpiece disk is used to place a substrate.

[0012] There are two evaporation sources, including a first evaporation source and a second evaporation source. Both are located at the bottom of the vacuum chamber and are set to correspond to the rotation trajectory of the workpiece disk as it rotates with the rotating disk. The first evaporation source is used to provide Ta2O5, and the second evaporation source is used to provide SiO2.

[0013] There are two fixed correction plates, including a first fixed correction plate and a second fixed correction plate. The first fixed correction plate is located between the first evaporation source and the rotating disk when the rotating disk rotates to above the first evaporation source, and the second fixed correction plate is located between the second evaporation source and the rotating disk when the rotating disk rotates to above the second evaporation source.

[0014] The revolution correction plate is connected to the rotating disk and located below the workpiece disk, and the revolution correction plate is coaxially arranged with the workpiece disk.

[0015] Furthermore, it also includes cylinders and hinge rods. There are two cylinders, which are respectively disposed on the inner side wall of the vacuum chamber. Their fixed ends are hinged to the inner side wall of the vacuum chamber. There are two hinge rods, and one end of each hinge rod is connected to the first fixed correction plate and the second fixed correction plate, respectively. The other end is hinged to the inner side wall of the vacuum chamber. The movable ends of the two cylinders are respectively hinged to the two hinge rods and the ends of the first and second fixed correction plates connected to them.

[0016] Meanwhile, the present invention also provides a method for correcting the uniformity of linear gradient filter film thickness, which uses the above-mentioned coating equipment and is characterized by including the following steps:

[0017] S1. Establish a mathematical model for the film thickness distribution of Ta2O5 and SiO2, calculate the target shading rate of Ta2O5 and SiO2 based on the mathematical model, and obtain the maximum intermediate shading rate of Ta2O5 and SiO2 by averaging the maximum target shading rate of Ta2O5 and SiO2.

[0018] S2. Based on the shading theory and the maximum intermediate shading rates of Ta2O5 and SiO2, calculate the mathematical expression for the shape of the orbit correction plate, and fabricate the orbit correction plate according to the mathematical expression.

[0019] Place the substrate on the workpiece disk, turn on the first evaporation source, the rotating disk and the workpiece disk, and use the revolution correction plate to perform the first correction on the Ta2O5 film thickness distribution on the substrate. After the correction is completed, turn off the first evaporation source, the rotating disk and the workpiece disk to obtain the actual film thickness distribution of Ta2O5 on the substrate after the first correction.

[0020] After replacing the substrate, turn on the second evaporation source, the rotating disk and the workpiece disk, and use the revolution correction plate to perform the first correction on the SiO2 film thickness distribution on the substrate. After the correction is completed, turn off the second evaporation source, the rotating disk and the workpiece disk to obtain the actual film thickness distribution of SiO2 on the substrate after the first correction.

[0021] S3. Based on the film thickness distribution of Ta2O5 and SiO2 after the first correction, and combined with the target film thickness distribution of Ta2O5 and SiO2, calculate the mathematical expressions for the shapes of the first fixed correction plate and the second fixed correction plate respectively, and process the first fixed correction plate and the second fixed correction plate according to the mathematical expressions.

[0022] After replacing the substrate, turn on the rotating disk, workpiece disk and the first evaporation source, and use the first fixed correction plate to perform a second correction on the Ta2O5 film thickness distribution on the substrate. After the correction is completed, turn off the rotating disk, workpiece disk and the first evaporation source to obtain the actual film thickness distribution of Ta2O5 on the substrate after the second correction.

[0023] After replacing the substrate, turn on the rotating disk, workpiece disk and second evaporation source, and use the second fixed correction plate to correct the SiO2 film thickness distribution on the substrate for the second time. After the correction is completed, turn off the rotating disk, workpiece disk and second evaporation source to obtain the actual SiO2 film thickness distribution on the substrate after the second correction.

[0024] S4. Replace the substrate, turn on the rotating disk and workpiece disk, and alternately turn on the first evaporation source and the second evaporation source to prepare the multilayer linear gradient filter and complete the correction of the uniformity of the linear gradient filter film thickness.

[0025] Furthermore, step S1 specifically includes:

[0026] S1.1. Establish a mathematical model for the film thickness distribution of Ta2O5 and SiO2 through software simulation:

[0027]

[0028]

[0029] in, For the thickness of the Ta2O5 film, The thickness of the SiO2 film. These are the position coordinates on the substrate. and The constants obtained from the fitting correspond to the film thickness distributions of Ta2O5 and SiO2, respectively. and The linear factors corresponding to the film thickness distributions of Ta2O5 and SiO2 obtained by fitting are respectively.

[0030] S1.2. Based on the mathematical model of Ta2O5 and SiO2 film thickness distribution, the target occlusion rates of Ta2O5 and SiO2 at various locations on the substrate are obtained:

[0031] ;

[0032] ;

[0033] in, The target occlusion rate for Ta2O5, The target occlusion rate of SiO2, These are the coordinates of the selected point on the substrate. The coordinates are the unobstructed locations on the substrate.

[0034] S1.3, Based on the target occlusion rates of Ta2O5 and SiO2 at various locations on the substrate. and , respectively obtain maximum value and maximum value The maximum intermediate shading rate of Ta2O5 and SiO2 is obtained by averaging the two:

[0035] ;

[0036] in: This represents the maximum intermediate occlusion rate.

[0037] Furthermore, step S2 specifically includes:

[0038] S2.1. Based on the shading theory, combined with the obtained maximum intermediate shading rates of Ta2O5 and SiO2... The mathematical expression for the shape of the orbital correction plate is obtained as follows:

[0039] ;

[0040] in: The radius of motion of the substrate rotating around the center of the correction plate. The length of the substrate, The angle of rotation of the substrate around the center of the revolution correction plate. The radius of the orbital correction plate;

[0041] S2.2. Based on the mathematical expression, process the revolution correction plate, place the substrate on the workpiece disk, set the revolution correction plate below the substrate, and connect the revolution correction plate to the rotating disk. Turn on the first evaporation source, the rotating disk, and the workpiece disk. Use the revolution correction plate to perform the first correction on the Ta2O5 film thickness distribution on the substrate. After the correction is completed, turn off the first evaporation source, the rotating disk, and the workpiece disk to obtain the actual film thickness distribution of Ta2O5 on the substrate after the first correction.

[0042] After replacing the substrate, turn on the second evaporation source, the rotating disk, and the workpiece disk. Use the revolution correction plate to perform the first correction on the SiO2 film thickness distribution on the substrate. After the correction is completed, turn off the second evaporation source, the rotating disk, and the workpiece disk to obtain the actual SiO2 film thickness distribution on the substrate after the first correction.

[0043] Furthermore, step S3 specifically includes:

[0044] S3.1. Based on the film thickness distributions of Ta2O5 and SiO2 after the first correction, and combined with the target film thickness distributions of Ta2O5 and SiO2, calculate the mathematical expressions for the shapes of the first and second fixed correction plates respectively:

[0045] ;

[0046] ;

[0047] in: The angles corresponding to the arcs at various positions of the first fixed correction plate. The angles corresponding to the arcs at various positions of the second fixed correction plate. The target occlusion rate of Ta2O5 at various locations on the substrate is the result of the second correction. The target occlusion rate of SiO2 at various locations on the substrate is corrected for the second time.

[0048] S3.2. Process the first fixed correction plate and the second fixed correction plate according to the corresponding mathematical expression, and install the first fixed correction plate and the second fixed correction plate in the vacuum chamber;

[0049] After replacing the substrate, turn on the rotating disk, workpiece disk and the first evaporation source, and use the first fixed correction plate to perform a second correction on the Ta2O5 film thickness distribution on the substrate. After the correction is completed, turn off the rotating disk, workpiece disk and the first evaporation source to obtain the actual film thickness distribution of Ta2O5 on the substrate after the second correction.

[0050] After replacing the substrate, turn on the rotating disk, workpiece disk, and second evaporation source. Use the second fixed correction plate to perform a second correction on the SiO2 film thickness distribution on the substrate. After the correction is completed, turn off the rotating disk, workpiece disk, and second evaporation source to obtain the actual SiO2 film thickness distribution on the substrate after the second correction.

[0051] Furthermore, step S4 specifically includes:

[0052] Replace with a new substrate and evacuate the base vacuum to 1×10⁻⁶. -3 Pa, baking temperature set to 200℃, evaporation source voltage set to 1400V, current set to 1400mA, Ta2O5 gas filling amount set to 90sccm, SiO2 gas filling amount set to 50sccm, film thickness control using the film thickness corresponding to the position of maximum center wavelength, control method is back reflection light control, before coating, the substrate is cleaned using the first evaporation source and the second evaporation source, cleaning time is 120s, then the rotating disk and workpiece disk are turned on, and the first evaporation source and the second evaporation source are turned on alternately to prepare multilayer linear gradient filter, complete the correction of film thickness uniformity of linear gradient filter.

[0053] Furthermore, in step S2.2, during the first correction, the background vacuum is evacuated to 1×10⁻⁶. -3 Pa, baking temperature set to 200℃, evaporation source voltage set to 1400V, current set to 1400mA, Ta2O5 gas filling rate set to 90sccm, SiO2 gas filling rate set to 50sccm.

[0054] Furthermore, in step S3.2, during the second correction, the background vacuum is evacuated to 1×10⁻⁶. -3 Pa, baking temperature set to 200℃, evaporation source voltage set to 1400V, current set to 1400mA, Ta2O5 gas filling rate set to 90sccm, SiO2 gas filling rate set to 50sccm.

[0055] Furthermore, in steps S2.2 and S3.2, the film thickness distribution of Ta2O5 and SiO2 on the substrate is obtained by ellipsometer measurement;

[0056] The substrate material in steps S2, S3 and S4 is JGS1 glass.

[0057] Compared with the prior art, the beneficial effects of the present invention are:

[0058] (1) The present invention provides a coating equipment including a vacuum coating machine and a revolution correction plate. The vacuum coating machine includes a vacuum chamber, a rotating disk, a workpiece disk, a fixed correction plate and an evaporation source. A first fixed correction plate and a second fixed correction plate are arranged in the vacuum chamber. A revolution correction plate is arranged below the workpiece disk so that it rotates around the center of the rotating disk together with the workpiece disk. The workpiece disk itself also has a rotational motion. The film thickness distribution of Ta2O5 and SiO2 is corrected to the intermediate linearity by the revolution correction plate. At this time, the film thickness distribution of Ta2O5 and SiO2 after being corrected by the revolution correction plate has not yet reached the final target. The difference from the final target is corrected for the second time by the first fixed correction plate and the second fixed correction plate respectively. Finally, the film thickness distribution of Ta2O5 and SiO2 reaches the final target. By combining the revolution correction plate and the fixed correction plate, the film thickness distribution of Ta2O5 and SiO2 is corrected to the film thickness distribution state required by the linear gradient filter. The overall structure is simple and the operation is convenient.

[0059] (2) The coating equipment provided by the present invention also includes a cylinder and a hinge rod. When the first fixed correction plate or the second fixed correction plate needs to be corrected, the cylinder drives the corresponding hinge rod to rotate, thereby driving the first fixed correction plate or the second fixed correction plate to rotate into place. If not needed, the cylinder drives the first fixed correction plate or the second fixed correction plate to rotate to a position close to the inner side wall of the vacuum chamber. The structure is simple.

[0060] (3) The present invention provides a method for correcting the uniformity of film thickness of a linear gradient filter. First, a mathematical model of the film thickness distribution of Ta2O5 and SiO2 is established to calculate the target occlusion rate of Ta2O5 and SiO2. Then, the maximum intermediate occlusion rate of Ta2O5 and SiO2 is calculated. Based on the maximum intermediate occlusion rate and the occlusion theory, the mathematical expression of the shape of the orbital correction plate is calculated. Then, the film thickness distribution of Ta2O5 and SiO2 is corrected for the first time using the orbital correction plate. Based on the film thickness distribution of Ta2O5 and SiO2 after the first correction and the target film thickness distribution of Ta2O5 and SiO2, the mathematical expressions of the shapes of the first fixed correction plate and the second fixed correction plate are calculated. Then, the film thickness distribution of Ta2O5 and SiO2 is corrected for the second time using the first fixed correction plate and the second fixed correction plate, so that the film thickness distribution of Ta2O5 and SiO2 reaches the target film thickness distribution, thereby completing the preparation of the multilayer linear gradient filter. This method can accurately calculate the shapes of the revolution correction plate, the first fixed correction plate, and the second fixed correction plate, and can accurately correct the uniformity of the film thickness distribution of Ta2O5 and SiO2. The calculation method is simple, which can significantly reduce the number of experiments and reduce costs. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of an embodiment of a coating equipment according to the present invention (cylinder not shown);

[0062] Figure 2 In an embodiment of the linear gradient filter film thickness uniformity correction method of the present invention, in step S2, the radius of motion of the substrate rotating around the center of the revolution correction plate is... The angle of rotation of the substrate around the center of the correction plate And a schematic diagram of the substrate length L;

[0063] Figure 3 This is a film thickness distribution diagram of Ta2O5 and SiO2 obtained by software simulation in an embodiment of a linear gradient filter film thickness uniformity correction method of the present invention.

[0064] Figure 4 This is a schematic diagram of the orbital correction plate in step S2 of an embodiment of a linear gradient filter film thickness uniformity correction method of the present invention.

[0065] Figure 5 This is a comparison diagram of the deviation between the actual film thickness distribution and the target film thickness distribution of Ta2O5 after the first correction in an embodiment of the linear gradient filter film thickness uniformity correction method of the present invention.

[0066] Figure 6This is a comparison diagram of the deviation between the actual SiO2 film thickness distribution and the target film thickness distribution after the first correction in an embodiment of the linear gradient filter film thickness uniformity correction method of the present invention.

[0067] Figure 7 This is a schematic diagram of the structure of the first fixed correction plate obtained in step S3 in an embodiment of a linear gradient filter film thickness uniformity correction method of the present invention.

[0068] Figure 8 This is a schematic diagram of the structure of the second fixed correction plate obtained in step S3 in an embodiment of a linear gradient filter film thickness uniformity correction method of the present invention.

[0069] Figure 9 This is a comparison diagram of the deviation between the actual film thickness distribution and the target film thickness distribution of Ta2O5 after the second correction in an embodiment of the linear gradient filter film thickness uniformity correction method of the present invention.

[0070] Figure 10 This is a comparison diagram of the deviation between the actual SiO2 film thickness distribution and the target film thickness distribution after the second correction in an embodiment of the linear gradient filter film thickness uniformity correction method of the present invention.

[0071] Figure 11 This is a spectral curve of each center wavelength in a multilayer linear gradient filter prepared in step S4, as shown in an embodiment of the linear gradient filter film thickness uniformity correction method of the present invention.

[0072] Figure 12 This is a comparison diagram of the deviation between the actual wavelength and the target wavelength of a multilayer linear gradient filter in an embodiment of the linear gradient filter film thickness uniformity correction method of the present invention.

[0073] The annotations in the attached figures are explained as follows:

[0074] 1-Vacuum coating machine; 11-Vacuum chamber; 12-Rotating disk; 13-Workpiece disk; 14-Fixed correction plate; 141-First fixed correction plate; 142-Second fixed correction plate; 15-Evaporation source; 151-First evaporation source; 152-Second evaporation source; 2-Revolution correction plate; 3-Substrate; 4-Hinged rod. Detailed Implementation

[0075] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.

[0076] Reference Figure 1The coating equipment of the present invention includes a vacuum coating machine 1 and a revolution correction plate 2. The vacuum coating machine 1 includes a vacuum chamber 11, a rotating disk 12, a workpiece disk 13, a fixed correction plate 14, and an evaporation source 15. The vacuum chamber 11 provides a vacuum environment for coating. The rotating disk 12 is rotatably disposed on the inner top surface of the vacuum chamber 11, while the workpiece disk 13 is rotatably disposed at the bottom of the rotating disk 12, and the rotation center of the workpiece disk 13 is offset from the rotation center of the rotating disk 12. The bottom surface of the workpiece disk 13 is used to place the substrate 3, so that the workpiece disk 13 can rotate on its own axis while rotating with the rotating disk 12. The revolution correction plate 2 is connected to the rotating disk 12 and located below the workpiece disk 13, and the revolution correction plate 2 and the workpiece disk 13 are coaxially arranged.

[0077] There are two evaporation sources 15, including a first evaporation source 151 and a second evaporation source 152. Both are located at the bottom of the vacuum chamber 11 and are set to correspond to the rotation trajectory of the workpiece disk 13 as it rotates with the rotating disk 12. The first evaporation source 151 is used to provide Ta2O5, and the second evaporation source 152 is used to provide SiO2.

[0078] There are two fixed correction plates 14, namely a first fixed correction plate 141 and a second fixed correction plate 142. The first fixed correction plate 141 is located between the first evaporation source 151 and the rotating disk 12 when the rotating disk 12 rotates to above the first evaporation source 151, and is used to correct the film thickness distribution of Ta2O5. The second fixed correction plate 142 is located between the second evaporation source 152 and the rotating disk 12 when the rotating disk 12 rotates to above the second evaporation source 152, and is used to correct the film thickness distribution of SiO2.

[0079] Two cylinders are installed on the inner wall of the vacuum chamber 11. The fixed ends of the two cylinders are hinged to the inner wall of the vacuum chamber 11. One end of the two hinge rods 4 is connected to the first fixed correction plate 141 and the second fixed correction plate 142 respectively, and the other end is hinged to the inner wall of the vacuum chamber 11. The movable ends of the two cylinders are hinged to the two hinge rods 4 and the ends of the first fixed correction plate 141 and the second fixed correction plate 142 respectively. In this way, the cylinders can control the raising and lowering of the first fixed correction plate 141 and the second fixed correction plate 142. When needed, the corresponding cylinders and hinge rods 4 are used to raise them to below the substrate 3. When not needed, they are lowered to the inner wall of the vacuum chamber 11. In the actual preparation of multilayer films, the first fixed correction plate 141 and the second fixed correction plate 142 are raised and lowered alternately under the action of the cylinders to achieve the purpose of controlling the film thickness distribution of one material respectively.

[0080] The technical specifications of the multilayer linear graded filter prepared in this embodiment are shown in Table 1:

[0081] Table 1

[0082]

[0083] The principle of film thickness uniformity correction is to use a correction plate to block a certain percentage of the film thickness so that the film thickness deposited at different locations on substrate 3 reaches the target state. The percentage of film thickness blocked is determined by the blocking rate of the correction plate.

[0084] Therefore, the present invention also provides a method for correcting the uniformity of linear gradient filter film thickness, comprising the following steps:

[0085] S1. Establish a mathematical model for the film thickness distribution of Ta2O5 and SiO2, calculate the target shading rate of Ta2O5 and SiO2 based on the mathematical model, and obtain the maximum intermediate shading rate of Ta2O5 and SiO2 by averaging the maximum target shading rate of Ta2O5 and SiO2.

[0086] Step S1 is as follows:

[0087] S1.1. Establish a mathematical model for the film thickness distribution of Ta2O5 and SiO2 through software simulation:

[0088]

[0089]

[0090] in, For the thickness of the Ta2O5 film, The thickness of the SiO2 film. These are the position coordinates on substrate 3. and The constants obtained from the fitting correspond to the film thickness distributions of Ta2O5 and SiO2, respectively. and The linear factors corresponding to the film thickness distributions of Ta2O5 and SiO2 obtained by fitting are respectively.

[0091] like Figure 3 The figure shown is a film thickness distribution diagram of Ta2O5 and SiO2 simulated by software based on the technical indicators in Table 1. It can be seen from the figure that the film thickness distribution of the two is approximately a linear function, that is, the mathematical model of the film thickness distribution of Ta2O5 and SiO2 obtained in step S1.1.

[0092] S1.2. Based on the mathematical model of Ta2O5 and SiO2 film thickness distribution, the target occlusion rates of Ta2O5 and SiO2 at various locations on substrate 3 are obtained:

[0093] ;

[0094] ;

[0095] in, The target occlusion rate for Ta2O5, The target occlusion rate of SiO2, These are the coordinates of the selected point on substrate 3. The coordinates are the coordinates of the unobstructed position on substrate 3.

[0096] The derivation of the formulas for calculating the target occlusion rate of Ta2O5 and SiO2 at various locations on the substrate is as follows:

[0097] The formula for calculating the occlusion rate is as follows:

[0098]

[0099] in The complete form is , This refers to the film thickness at the unobstructed location of substrate 3, i.e., the current film thickness. The current film thickness indicates the film thickness at all locations on substrate 3 when it is not obstructed; its thickness is essentially uniform, with the same thickness at all locations. The target film thickness is the film thickness at the selected point on substrate 3. It refers to the film thickness that needs to be achieved after correction, which is thinner than the current film thickness.

[0100] The derivation process is the same as the derivation process described above, and will not be repeated here;

[0101] S1.3, Based on the target occlusion rates of Ta2O5 and SiO2 at various locations on substrate 3 and , respectively obtain maximum value and maximum value The maximum intermediate shading rate of Ta2O5 and SiO2 is obtained by averaging the two:

[0102] ;

[0103] in: This represents the maximum intermediate occlusion rate.

[0104] Ta2O5 and SiO2 need to achieve 0- shading rates respectively in the working region of substrate 3, i.e., along the length of substrate 3. and 0 - Linear variation occurs because the orbital correction plate 2 rotates around the center of the rotating disk 12 along with the substrate 3, and the shape of the orbital correction plate 2 remains unchanged. Therefore, only a single blocking rate can be achieved during the fabrication of the linear graded filter. and Calculate the average value and take the maximum intermediate occlusion rate. .

[0105] S2. Based on the shading theory and the maximum intermediate shading rates of Ta2O5 and SiO2, calculate the mathematical expression for the shape of the orbit correction plate 2, and process the orbit correction plate 2 according to the mathematical expression.

[0106] The substrate 3 is placed on the workpiece disk 13, and the first evaporation source 151, the rotating disk 12 and the workpiece disk 13 are turned on. The revolution correction plate 2 is used to correct the Ta2O5 film thickness distribution on the substrate 3 for the first time. After the correction is completed, the first evaporation source 151, the rotating disk 12 and the workpiece disk 13 are turned off to obtain the actual film thickness distribution of Ta2O5 on the substrate 3 after the first correction.

[0107] After replacing the substrate 3, turn on the second evaporation source 152, the rotating disk 12 and the workpiece disk 13, and use the revolution correction plate 2 to perform the first correction on the SiO2 film thickness distribution on the substrate 3. After the correction is completed, turn off the second evaporation source 152, the rotating disk 12 and the workpiece disk 13 to obtain the actual film thickness distribution of SiO2 on the substrate 3 after the first correction.

[0108] Step S2 is as follows:

[0109] S2.1. Based on the shading theory, combined with the obtained maximum intermediate shading rates of Ta2O5 and SiO2... The mathematical expression for the shape of the orbital correction plate 2 is obtained as follows:

[0110] ;

[0111] in: The radius of motion of substrate 3 rotating around the center of the revolution correction plate 2. The length of substrate 3, The angle of rotation of substrate 3 around the center of the revolution correction plate 2. The radius of the orbital correction plate 2;

[0112] like Figure 2 The figure shows the radius of motion of substrate 3 rotating around the center of the revolution correction plate 2. The angle of rotation of substrate 3 around the center of correction plate 2 The diagram shows the length L of substrate 3. The goal of the film thickness distribution correction is to ensure that the film thickness of the two materials on substrate 3 varies linearly along the radial direction of the orbital correction plate 2, i.e., within the length L of substrate 3, but exhibits a uniform distribution in the circumferential direction. The orbital correction plate 2 is used to initially correct the film thickness distribution of the two materials. During the coating process, substrate 3 moves in a circle with radius r relative to the orbital correction plate 2. By adjusting the radius of the orbital correction plate 2 relative to the center of the circle of motion of substrate 3, the blocking position of the orbital correction plate 2 on substrate 3 can be adjusted. The blocking rate is controlled by the blocking angle of the orbital correction plate 2 on the circumference of the moving circle of substrate 3. The orbital correction plate 2 needs to achieve 0– on substrate 3. If the occlusion rate changes linearly, then the occlusion angle of the orbital correction plate 2 on the substrate 3 must be between 0 and 1. It varies linearly within a certain range. (From...) Figure 2 Given that the length of substrate 3 is L and its radius of motion is r, the effective shading radius of the orbital correction plate 2 on substrate 3 ranges from r to r+L. Therefore, the shading angle of the orbital correction plate 2 varies with the radius within the range of r to r+L, with a range of 0- The occlusion angle is a portion of the circular motion of the substrate 3. Reversing this relationship means that the original occlusion angle changed with the radius, and the occlusion angle corresponded to the angle of rotation of the substrate 3 around the center of the orbital correction plate 2. Here, this is converted to the radius changing with the angle of rotation of the substrate 3 around the center of the orbital correction plate 2. In 0 to Within a certain range, the radius of the orbital correction plate 2 changes from r to r+L. Therefore, the radius R of the orbital correction plate 2 and the rotation angle of the substrate 3 around the center of the orbital correction plate 2 can be obtained. The relationship is the mathematical expression for the shape of the revolution correction plate 2 obtained in step S2.1, and the structure of the obtained revolution correction plate 2 is as follows: Figure 4 As shown;

[0113] S2.2, Reduce the background vacuum to 1×10 -3 Pa, baking temperature set to 200℃, evaporation source voltage set to 1400V, current set to 1400mA, Ta2O5 gas filling rate set to 90sccm, SiO2 gas filling rate set to 50sccm.

[0114] Based on the mathematical expression, the revolution correction plate 2 is processed. The substrate 3 is placed on the workpiece disk 13, the revolution correction plate 2 is set below the substrate 3, and the revolution correction plate 2 is connected to the rotating disk 12. The first evaporation source 151, the rotating disk 12 and the workpiece disk 13 are turned on. The revolution correction plate 2 is used to correct the Ta2O5 film thickness distribution on the substrate 3 for the first time. After the correction is completed, the first evaporation source 151, the rotating disk 12 and the workpiece disk 13 are turned off. The actual film thickness distribution of Ta2O5 on the substrate 3 after the first correction is obtained by ellipsometer test.

[0115] After replacing the substrate 3, turn on the second evaporation source 152, the rotating disk 12 and the workpiece disk 13. Use the revolution correction plate 2 to perform the first correction on the SiO2 film thickness distribution on the substrate 3. After the correction is completed, turn off the second evaporation source 152, the rotating disk 12 and the workpiece disk 13. Use an ellipsometry to test the actual film thickness distribution of SiO2 on the substrate 3 after the first correction.

[0116] After the first correction, the actual film thickness distributions of Ta2O5 and SiO2 on substrate 3 are as follows: Figure 5 and Figure 6 As shown, after the first correction, the film thickness distribution has begun to approach the target film thickness distribution.

[0117] S3. Based on the film thickness distribution of Ta2O5 and SiO2 after the first correction, and combined with the target film thickness distribution of Ta2O5 and SiO2, calculate the mathematical expressions for the shapes of the first fixed correction plate 141 and the second fixed correction plate 142 respectively, and process the first fixed correction plate 141 and the second fixed correction plate 142 according to the mathematical expressions.

[0118] After replacing the substrate 3, turn on the rotating disk 12, the workpiece disk 13 and the first evaporation source 151, and use the first fixed correction plate 141 to perform a second correction on the Ta2O5 film thickness distribution on the substrate 3. After the correction is completed, turn off the rotating disk 12, the workpiece disk 13 and the first evaporation source 151 to obtain the actual film thickness distribution of Ta2O5 on the substrate 3 after the second correction.

[0119] After replacing the substrate 3, turn on the rotating disk 12, the workpiece disk 13 and the second evaporation source 152, and use the second fixed correction plate 142 to correct the SiO2 film thickness distribution on the substrate 3 for the second time. After the correction is completed, turn off the rotating disk 12, the workpiece disk 13 and the second evaporation source 152 to obtain the actual film thickness distribution of SiO2 on the substrate 3 after the second correction.

[0120] Step S3 is as follows:

[0121] S3.1 Based on the film thickness distribution of Ta2O5 and SiO2 after the first correction, and combined with the target film thickness distribution of Ta2O5 and SiO2, calculate the mathematical expressions for the shapes of the first fixed correction plate 141 and the second fixed correction plate 142 respectively:

[0122] ;

[0123] ;

[0124] in: The angles corresponding to the arcs at various positions of the first fixed correction plate 141. The angles corresponding to the arcs at various positions of the second fixed correction plate 142. The target occlusion rate of Ta2O5 at various locations on substrate 3 is the result of the second correction. The target occlusion rate of SiO2 at various positions on substrate 3 is the second correction.

[0125] S3.2, Reduce the background vacuum to 1×10 -3 Pa, baking temperature set to 200℃, evaporation source voltage set to 1400V, current set to 1400mA, Ta2O5 gas filling rate set to 90sccm, SiO2 gas filling rate set to 50sccm.

[0126] The first fixed correction plate 141 and the second fixed correction plate 142 are processed according to the corresponding mathematical expressions, and the first fixed correction plate 141 and the second fixed correction plate 142 are installed in the vacuum chamber 11.

[0127] After replacing the substrate 3, turn on the rotating disk 12, the workpiece disk 13 and the first evaporation source 151, and use the first fixed correction plate 141 to perform a second correction on the Ta2O5 film thickness distribution on the substrate 3. After the correction is completed, turn off the rotating disk 12, the workpiece disk 13 and the first evaporation source 151, and use an ellipsometry to test the actual film thickness distribution of Ta2O5 on the substrate 3 after the second correction.

[0128] After replacing the substrate 3, turn on the rotating disk 12, the workpiece disk 13 and the second evaporation source 152, and use the second fixed correction plate 142 to correct the SiO2 film thickness distribution on the substrate 3 for the second time. After the correction is completed, turn off the rotating disk 12, the workpiece disk 13 and the second evaporation source 152, and use an ellipsometry to test the actual SiO2 film thickness distribution on the substrate 3 after the second correction.

[0129] from Figure 9 and Figure 10 As can be seen from the second correction, the actual film thickness distribution of Ta2O5 and SiO2 on substrate 3 has been corrected to be very close to the target film thickness distribution.

[0130] The mathematical derivation process of the shapes of the first fixed correction plate 141 and the second fixed correction plate 142 in step S3.1 is as follows:

[0131] The formula for calculating the occlusion rate is:

[0132]

[0133] According to the shading theory, the shading rate of the fixed correction plate 14 on the film thickness is equal to the shading angle of the fixed correction plate 14 on the moving circumference of the substrate 3. Therefore, the shading rate can also be equivalent to:

[0134]

[0135] in: To fix the angle of the correction plate 14 blocking the movement circumference of the substrate 3;

[0136] The second correction of the target film thickness distribution of Ta2O5 and SiO2 is the second correction of the target occlusion rate. and Substituting into the above formula and rearranging, we can obtain the mathematical expressions for the shapes of the first fixed correction plate 141 and the second fixed correction plate 142, where... These are also the angles corresponding to the arcs at various positions on the first fixed correction plate 141. The angles corresponding to the arcs at various positions of the second fixed correction plate 141 are also given. The radii corresponding to the arcs of the first fixed correction plate 141 and the second fixed correction plate 142 are the sum of the maximum distance from the zero point of the coordinate on the substrate 3 to the rotation center of the rotating disk 12 and the position coordinates. Based on the calculated arc angles and radii, the arcs at various positions of the first fixed correction plate 141 and the second fixed correction plate 142 are drawn on the drawing software and connected by smooth curves to obtain the shapes of the first fixed correction plate 141 and the second fixed correction plate 142, as shown in the figures below. Figure 7 and Figure 8 As shown.

[0137] S4. Replace with a new substrate 3 and evacuate the base vacuum to 1×10⁻⁶. -3Pa, baking temperature set to 200℃, evaporation source voltage set to 1400V, current set to 1400mA, Ta2O5 gas filling amount set to 90sccm, SiO2 gas filling amount set to 50sccm, film thickness control using the film thickness corresponding to the position of maximum center wavelength, control method is back reflection light control, before coating, the substrate 3 is cleaned using the first evaporation source 151 and the second evaporation source 152, cleaning time is 120s, then the rotating disk 12 and workpiece disk 13 are turned on, and the first evaporation source 151 and the second evaporation source 152 are turned on alternately to prepare multilayer linear gradient filter, complete the correction of film thickness uniformity of linear gradient filter.

[0138] In steps S2, S3 and S4, the substrate 3 is made of JGS1 glass.

[0139] The spectral curves of each center wavelength in the fabricated multilayer linear graded filter are as follows: Figure 11 As shown in the figure, the deviation between the actual wavelength and the target wavelength of the multilayer linear graded filter is compared. Figure 12 As shown, the center wavelength variation rate of the prepared multilayer linear graded filter is 6.4 nm / mm, which is close to the target variation rate of 6 nm / mm, thus achieving the expected goal. The average peak transmittance of the multilayer linear graded filter is 89.59%, the maximum transmittance in the cutoff region is 0.31%, and the passband half-width is less than 3% of the center wavelength.

[0140] The embodiments described above are merely illustrative of specific implementations of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for correcting the uniformity of film thickness in a linear gradient filter, employing a coating apparatus including a vacuum coating machine (1) and a revolving correction plate (2); the vacuum coating machine (1) includes a vacuum chamber (11), a rotating disk (12), a workpiece disk (13), a fixed correction plate (14), and an evaporation source (15). The rotating disk (12) is rotatably disposed on the inner top surface of the vacuum chamber (11), and the workpiece disk (13) is rotatably disposed on the bottom of the rotating disk (12), with the rotation center of the workpiece disk (13) offset from the rotation center of the rotating disk (12). The bottom surface of the workpiece disk (13) is used to place a substrate (3); there are two evaporation sources (15), including a first evaporation source (151) and a second evaporation source (152), both of which are disposed on the bottom of the vacuum chamber (11) and correspond to the workpiece disk (13) as it rotates with the rotating disk. (12) The rotation trajectory is set, the first evaporation source (151) is used to provide Ta2O5, and the second evaporation source (152) is used to provide SiO2; there are two fixed correction plates (14), including a first fixed correction plate (141) and a second fixed correction plate (142), and the first fixed correction plate (141) is located between the first evaporation source (151) and the rotating disk (12) when the rotating disk (12) rotates to above the first evaporation source (151), and the second fixed correction plate (142) is located between the second evaporation source (152) and the rotating disk (12) when the rotating disk (12) rotates to above the second evaporation source (152); the revolution correction plate (2) is connected to the rotating disk (12) and located below the workpiece disk (13), and the revolution correction plate (2) and the workpiece disk (13) are coaxially arranged; characterized in that, Includes the following steps: S1. Establish a mathematical model for the film thickness distribution of Ta2O5 and SiO2, calculate the target shading rate of Ta2O5 and SiO2 based on the mathematical model, and obtain the maximum intermediate shading rate of Ta2O5 and SiO2 by averaging the maximum target shading rate of Ta2O5 and SiO2. Step S1 is as follows: S1.

1. Establish a mathematical model for the film thickness distribution of Ta2O5 and SiO2 through software simulation: ； ； in, For the thickness of the Ta2O5 film, The thickness of the SiO2 film. The position coordinates on the substrate (3) and The constants obtained from the fitting correspond to the film thickness distributions of Ta2O5 and SiO2, respectively. and The linear factors corresponding to the film thickness distributions of Ta2O5 and SiO2 obtained by fitting are respectively. S1.

2. Based on the mathematical model of Ta2O5 and SiO2 film thickness distribution, the target occlusion rates of Ta2O5 and SiO2 at various positions on the substrate (3) are obtained: ； ； in, The target occlusion rate for Ta2O5, The target occlusion rate of SiO2, The coordinates of the selected point on the substrate (3) are given. The coordinates of the unobstructed position on the substrate (3); S1.3, Based on the target occlusion rates of Ta2O5 and SiO2 at various positions on the substrate (3) and , respectively obtain maximum value and maximum value The maximum intermediate shading rate of Ta2O5 and SiO2 is obtained by averaging the two: ； in: This represents the maximum intermediate occlusion rate. S2. Based on the shading theory and the maximum intermediate shading rate of Ta2O5 and SiO2, calculate the mathematical expression of the shape of the orbit correction plate (2), and process the orbit correction plate (2) according to the mathematical expression. Place the substrate (3) on the workpiece disk (13), turn on the first evaporation source (151), the rotating disk (12) and the workpiece disk (13), and use the revolution correction plate (2) to perform the first correction on the Ta2O5 film thickness distribution on the substrate (3). After the correction is completed, turn off the first evaporation source (151), the rotating disk (12) and the workpiece disk (13) to obtain the actual film thickness distribution of Ta2O5 on the substrate (3) after the first correction. After replacing the substrate (3), turn on the second evaporation source (152), the rotating disk (12) and the workpiece disk (13), and use the revolution correction plate (2) to make the first correction on the SiO2 film thickness distribution on the substrate (3). After the correction is completed, turn off the second evaporation source (152), the rotating disk (12) and the workpiece disk (13) to obtain the actual film thickness distribution of SiO2 on the substrate (3) after the first correction. Step S2 is as follows: S2.

1. Based on the shading theory, combined with the obtained maximum intermediate shading rates of Ta2O5 and SiO2... The mathematical expression for the shape of the orbital correction plate (2) is obtained as follows: ； in: The radius of motion of the substrate (3) rotating around the center of the orbital correction plate (2) is given by the following: The length of the substrate (3) The angle of rotation of the substrate (3) around the center of the revolution correction plate (2) Let the radius of the orbital correction plate (2) be denoted by . S2.

2. Based on the mathematical expression, process the revolution correction plate (2), place the substrate (3) on the workpiece disk (13), connect the revolution correction plate (2) to the rotating disk (12) and set it coaxially below the workpiece disk (13), turn on the first evaporation source (151), the rotating disk (12) and the workpiece disk (13), use the revolution correction plate (2) to perform the first correction on the Ta2O5 film thickness distribution on the substrate (3), after the correction is completed, turn off the first evaporation source (151), the rotating disk (12) and the workpiece disk (13) to obtain the actual film thickness distribution of Ta2O5 on the substrate (3) after the first correction; After replacing the substrate (3), turn on the second evaporation source (152), the rotating disk (12) and the workpiece disk (13), and use the revolution correction plate (2) to make the first correction on the SiO2 film thickness distribution on the substrate (3). After the correction is completed, turn off the second evaporation source (152), the rotating disk (12) and the workpiece disk (13) to obtain the actual film thickness distribution of SiO2 on the substrate (3) after the first correction. S3. Based on the film thickness distribution of Ta2O5 and SiO2 after the first correction, and combined with the target film thickness distribution of Ta2O5 and SiO2, calculate the mathematical expressions for the shapes of the first fixed correction plate (141) and the second fixed correction plate (142), and process the first fixed correction plate (141) and the second fixed correction plate (142) according to the mathematical expressions. After replacing the substrate (3), turn on the rotating disk (12), the workpiece disk (13) and the first evaporation source (151), and use the first fixed correction plate (141) to perform a second correction on the Ta2O5 film thickness distribution on the substrate (3). After the correction is completed, turn off the rotating disk (12), the workpiece disk (13) and the first evaporation source (151) to obtain the actual film thickness distribution of Ta2O5 on the substrate (3) after the second correction. After replacing the substrate (3), turn on the rotating disk (12), the workpiece disk (13) and the second evaporation source (152), and use the second fixed correction plate (142) to correct the SiO2 film thickness distribution on the substrate (3) for the second time. After the correction is completed, turn off the rotating disk (12), the workpiece disk (13) and the second evaporation source (152) to obtain the actual film thickness distribution of SiO2 on the substrate (3) after the second correction. S4. Replace the substrate (3), turn on the rotating disk (12) and the workpiece disk (13), and alternately turn on the first evaporation source (151) and the second evaporation source (152) to prepare the multilayer linear gradient filter and complete the correction of the uniformity of the linear gradient filter film thickness.

2. The method for correcting the uniformity of linear gradient filter film thickness according to claim 1, characterized in that, Step S3 is as follows: S3.

1. Based on the film thickness distribution after the first correction of Ta2O5 and SiO2, and combined with the target film thickness distribution of Ta2O5 and SiO2, calculate the mathematical expressions for the shapes of the first fixed correction plate (141) and the second fixed correction plate (142) respectively: ； ； in: The angles corresponding to the arcs at various positions of the first fixed correction plate (141) are... The angles corresponding to the arcs at various positions of the second fixed correction plate (142) are... The target occlusion rate of Ta2O5 at various positions on the substrate (3) is the second correction. The target occlusion rate of SiO2 at various positions on the substrate (3) is the second correction. S3.

2. Process the first fixed correction plate (141) and the second fixed correction plate (142) according to the corresponding mathematical expression, and install the first fixed correction plate (141) and the second fixed correction plate (142) in the vacuum chamber (11); After replacing the substrate (3), turn on the rotating disk (12) and the workpiece disk (13), and simultaneously turn on the first evaporation source (151). Use the first fixed correction plate (141) to perform a second correction on the Ta2O5 film thickness distribution on the substrate (3). After the correction is completed, turn off the rotating disk (12), the workpiece disk (13) and the first evaporation source (151) to obtain the actual film thickness distribution of Ta2O5 on the substrate (3) after the second correction. After replacing the substrate (3), turn on the rotating disk (12) and the workpiece disk (13), turn on the second evaporation source (152), and use the second fixed correction plate (142) to correct the SiO2 film thickness distribution on the substrate (3) for the second time. After the correction is completed, turn off the rotating disk (12), the workpiece disk (13) and the second evaporation source (152) to obtain the actual film thickness distribution of SiO2 on the substrate (3) after the second correction.

3. The method for correcting the uniformity of linear gradient filter film thickness according to claim 2, characterized in that, Step S4 is as follows: Replace with a new substrate (3) and evacuate the background vacuum to 1×10⁻⁶. -3 Pa, baking temperature set to 200℃, evaporation source voltage set to 1400V, current set to 1400mA, Ta2O5 gas filling amount set to 90sccm, SiO2 gas filling amount set to 50sccm, film thickness control is performed using the film thickness corresponding to the position of maximum center wavelength, control method is back reflection light control, before coating, the substrate (3) is cleaned using the first evaporation source (151) and the second evaporation source (152) for 120s, then the rotating disk (12) and workpiece disk (13) are turned on, and the first evaporation source (151) and the second evaporation source (152) are turned on alternately to prepare the multilayer linear gradient filter and complete the correction of the uniformity of the linear gradient filter film thickness.

4. The method for correcting the uniformity of linear gradient filter film thickness according to claim 1, characterized in that: In step S2.2, during the first correction, the background vacuum is evacuated to 1×10⁻⁶. -3 Pa, baking temperature set to 200℃, evaporation source voltage set to 1400V, current set to 1400mA, Ta2O5 gas filling rate set to 90sccm, SiO2 gas filling rate set to 50sccm.

5. The method for correcting the uniformity of linear gradient filter film thickness according to claim 2, characterized in that: In step S3.2, during the second correction, the background vacuum is evacuated to 1×10⁻⁶. -3 Pa, baking temperature set to 200℃, evaporation source voltage set to 1400V, current set to 1400mA, Ta2O5 gas filling rate set to 90sccm, SiO2 gas filling rate set to 50sccm.

6. The method for correcting the uniformity of linear gradient filter film thickness according to claim 2, characterized in that: In steps S2.2 and S3.2, the film thickness distribution of Ta2O5 and SiO2 on the substrate (3) is obtained by ellipsometer measurement; The substrate (3) in steps S2, S3 and S4 is made of JGS1 glass.

7. The method for correcting the uniformity of linear gradient filter film thickness according to claim 1, characterized in that: The coating equipment also includes cylinders and hinge rods (4). There are two cylinders, which are respectively installed on the inner wall of the vacuum chamber (11). Their fixed ends are hinged to the inner wall of the vacuum chamber (11). There are two hinge rods (4). One end of the two hinge rods (4) is connected to the first fixed correction plate (141) and the second fixed correction plate (142) respectively, and the other end is hinged to the inner wall of the vacuum chamber (11). The movable ends of the two cylinders are respectively hinged to the two hinge rods (4) and the ends of the first fixed correction plate (141) and the second fixed correction plate (142) connected to each other.

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