Vacuum coating equipment and coating control method thereof

Abstract

The present application relates to a vacuum coating device and a coating control method thereof, wherein the device comprises: a vacuum chamber, which is equipped with a product turntable, a sputtering system and an ion source connected to a control system; a spectral detection device connected to the control system, for detecting spectral energy data of the coated product during the coating process and reporting the data to the control system; a control system for controlling the operation of the product turntable, the sputtering system and the ion source, collecting spectral energy data detected by the spectral detection device and calculating the real-time transmittance of the coated product, and predicting the actual thickness of the coated film based on the real-time transmittance when the film thickness is close to the target thickness; calculating the layer change judgment stop time according to the actual thickness and outputting a layer change judgment stop instruction to perform the layer change operation until the coating of all film layers is completed; this technical solution greatly improves the layer change judgment stop accuracy, especially in coatings with a large number of layers, avoids the error accumulation caused by the increase in the number of coating layers, and improves the film quality of the coated product.

Description

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 30, 2022, with application number 202211743783.3 and invention name “Vacuum coating equipment and coating control method thereof”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of film coating technology, and in particular to a vacuum film coating device and a film coating control method thereof. Background Art

[0003] In the vacuum coating technology industry, it is often necessary to coat products with multiple layers of film to achieve the desired function. Taking the preparation of optical devices as an example, optical films are composed of multiple layers of high-precision film layers. When the actual thickness of the film layer deviates from the theoretical thickness, it will significantly affect the actual spectral indicators of the optical device. Therefore, during coating, the vacuum coating equipment must accurately control the thickness of each layer of the film, otherwise it will seriously affect the quality of the coated product.

[0004] Existing vacuum coating equipment, taking ion beam sputtering coating equipment as an example, usually uses a wide spectrum scanning method to monitor film thickness and an evaluation function method to monitor transmittance when coating optical devices. Since the evaluation function will delay issuing a stop command only after obtaining the minimum value of the transmittance error, there will inevitably be a delay in making a layer change stop judgment, and the random noise of each pixel of the spectrometer detector will also cause errors. For optical films with a large number of layers, this error will accumulate and become larger and larger, making the actual spectral characteristics of the coated product differ more from the target spectral characteristics. In severe cases, the product will be completely unusable. Therefore, it is necessary to improve the vacuum coating equipment to ensure the film quality of the coated product. Summary of the Invention

[0005] Based on this, it is necessary to provide a vacuum coating equipment and a coating control method thereof to improve the coating quality in response to one of the above-mentioned technical defects.

[0006] A vacuum coating device, comprising:

[0007] A vacuum chamber having a built-in product turntable connected to a control system, a sputtering system, and an ion source, wherein the product turntable is used to mount the coated product, the sputtering system is used to mount the target material and sputter the coating material, and the ion source is used to assist in thin film deposition;

[0008] A spectrum detection device, connected to the control system, for detecting the spectrum energy data of the coated product during the coating process and reporting it to the control system;

[0009] The control system is used to control the operation of the product turntable, sputtering system and ion source, collect the spectral energy data detected by the spectral detection device and calculate the real-time transmittance of the coated product. When the film thickness is close to the target thickness, the actual thickness of the coated film is predicted based on the real-time transmittance; the layer change stop time is calculated according to the actual thickness and the layer change stop instruction is output to perform the layer change operation until the coating of all film layers is completed.

[0010] In one embodiment, the spectrum detection device includes a light source and a spectrometer disposed on both sides of the product turntable; wherein the light source outputs test light of different wavelengths, and the spectrometer is used to detect spectral energy data and report it to the control system;

[0011] The control system includes: a host computer, a motion control board, and an optical control board; wherein the product turntable is driven by a drive motor, the motion control board is connected to the host computer and the spectrometer respectively, and the spectrometer is connected to the host computer via the optical control board;

[0012] The host computer communicates and interacts with the motion control board and the optical control board respectively;

[0013] The optical control board communicates and interacts with the spectrometer;

[0014] The motion control board controls the rotation of the product turntable through the drive motor and triggers the spectrometer to detect spectral energy data.

[0015] In one embodiment, the optical control board is used to collect spectral energy data detected by the spectral detection device from a spectrometer and upload it to a host computer; when the film thickness approaches the target thickness, the transmittance curve is obtained from the host computer and the actual thickness of the deposited film is predicted in real time; and the layer change judgment stop time is calculated based on the actual thickness and uploaded to the host computer;

[0016] The motion control board is used to receive control instructions from the host computer to control the drive motor to rotate or stop the product turntable, monitor the angular position of the product turntable in real time, and trigger the spectrometer to detect spectral energy data at a specified angle;

[0017] The host computer is used to control the operation of the product turntable, sputtering system and ion source, receive the spectral energy data reported by the optical control board and fit the transmittance curve of the coated product, receive the layer change stop time reported by the optical control board and output the layer change stop instruction according to the layer change stop time to perform the layer change operation.

[0018] In one embodiment, the product turntable includes a male turntable and a plurality of workpiece disks evenly distributed on the male turntable; wherein,

[0019] The workpiece plate is used to mount the coated product;

[0020] A through hole is provided on the rotating shaft of the workpiece disk, and the test light output by the light source passes through the through hole and is received by the spectrometer. A monitoring piece is provided at at least one of the through holes, and at least one of the through holes is provided in a transparent state.

[0021] A coating control method for a vacuum coating device is applied to the above-mentioned vacuum coating device, and is characterized by comprising:

[0022] Control the vacuum coating equipment to initialize;

[0023] Control the product turntable to rotate at a constant speed and start the ion source and sputtering system to enter the coating process;

[0024] Coating the current film layer, predicting the actual thickness of the coated film in real time, calculating the layer change stop time and outputting the layer change stop instruction;

[0025] Controlling the vacuum coating equipment to perform a layer-changing operation and coating the next film layer;

[0026] Complete all film layers in the coating process.

[0027] In one embodiment, the controlling the vacuum coating equipment to initialize includes:

[0028] The host computer sends an initialization command to the motion control board, driving the motor to rotate the product turntable back to the origin and stop;

[0029] The host computer sends a coating process file loading instruction to the optical control board, loads the coating process file and saves it;

[0030] The process of controlling the product turntable to rotate at a constant speed and starting the ion source and sputtering system to enter the coating process includes:

[0031] The host computer notifies the motion control board to drive the product turntable to rotate at the set angular velocity;

[0032] After the product turntable's rotation angular velocity stabilizes, the host computer notifies the ion source and sputtering system to start, and after the ion source enters normal working state, it notifies the optical control board to enter the ion beam coating program, select the current number of coating layers and initialize the timer.

[0033] In one embodiment, before controlling the product turntable to rotate at a constant speed and starting the ion source and sputtering system to enter the coating process, the process further includes:

[0034] The host computer sends a circular spectrum curve reporting request to the optical control board and notifies the motion control board to control the product turntable to rotate at a constant speed;

[0035] The motion control board triggers the spectrometer at a set period to measure the spectral energy data corresponding to different wavelengths and report it to the host computer;

[0036] The host computer draws a circular spectrum curve based on the spectral energy data corresponding to different wavelengths, calculates the specified angle position and sends it to the motion control board; wherein, the specified angle position is the angle position corresponding to the lowest spectral energy value, the highest spectral energy value and the real-time spectral energy value on the circular spectrum curve.

[0037] In one embodiment, the real-time prediction of the actual thickness of the deposited film, calculation of the layer change stop time and output of the layer change stop instruction include:

[0038] During the coating process, the motion control board controls the product turntable to rotate at a constant speed. When it rotates to a specified angle, it triggers the spectrometer to detect spectral energy data.

[0039] The optical control board collects the spectral energy data measured by the spectrometer every time the product turntable rotates one circle in real time, calculates the transmittance array of each wavelength point in real time based on the spectral energy data, and uploads it to the host computer;

[0040] The host computer fits the transmittance curve according to the transmittance array;

[0041] The optical control board calculates the estimated thickness of the film at the current moment in real time. When the estimated thickness reaches a set ratio of the target thickness, the estimated thickness is corrected using a random search method to obtain the actual thickness and the layer change stop time is calculated. The layer change stop time is reported to the host computer.

[0042] The upper computer outputs the layer change judgment stop instruction when the layer change judgment stop time is reached.

[0043] In one embodiment, the method of using a random search method to correct the estimated thickness to obtain the actual thickness and calculate the layer change stop time includes:

[0044] Obtain the target thickness from the coating process file and calculate the estimated thickness of the current coating according to the deposition rate of the ion beam sputtering coating;

[0045] Read the transmittance curve from the host computer and calculate the current actual transmittance, calculate the transmittance corresponding to the estimated thickness and the transmittance difference between it and the actual transmittance;

[0046] randomly generating a thickness update value, and using the thickness update value to iteratively search the estimated thickness to obtain the actual thickness;

[0047] Calculate the layer change judgment stop time from the current moment to the layer change point according to the actual thickness. If the layer change judgment stop time is greater than the sampling period of the spectrometer detection, continue to calculate the actual thickness before the next sampling period arrives;

[0048] If the layer-changing judgment stop time is less than or equal to the sampling period, a layer-changing judgment stop instruction is output after the layer-changing judgment stop time is reached.

[0049] In one embodiment, controlling the vacuum coating equipment to perform a layer-changing operation to coat the next film layer includes:

[0050] The host computer notifies the ion source to shut down, sends a layer change stop command to the optical control board to stop the spectrometer, resets the timer, and notifies the motion control board to drive the product turntable to switch the sputtering target and prepare for the next layer of coating.

[0051] The above-mentioned vacuum coating equipment and coating control method thereof detect the spectral energy data of the film product during the coating process through a spectral detection device and report it to the control system. The control system uses the collected spectral energy data to calculate the real-time transmittance of the coated product. When the film thickness is close to the target thickness, the actual thickness of the coated film is predicted based on the real-time transmittance and the layer change judgment stop time is calculated, and then the layer change judgment stop instruction is output to perform the layer change operation until the coating of all film layers is completed. This technical solution uses the real-time transmittance and estimated thickness of the coated product to finally predict the actual thickness during the coating process, so that it can more accurately approach the optimal layer change position, greatly improving the accuracy of the layer change judgment stop, especially in coatings with a large number of layers, avoiding the error accumulation caused by the increase in the number of coating layers, and improving the film quality of the coated product. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a schematic structural diagram of a vacuum coating device according to an embodiment;

[0053] Figure 2 is a schematic structural diagram of a vacuum coating device according to another embodiment;

[0054] Figure 3 This is a schematic diagram of an example product turntable structure;

[0055] Figure 4 is a flow chart of a coating control method for vacuum coating equipment according to an embodiment;

[0056] Figure 5 This is an example of a circular spectrum graph;

[0057] Figure 6 FIG2 is a schematic diagram of a transmittance curve of an example. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0059] The term "comprising" and any variations thereof in the embodiments of the present application are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps is not limited to the listed steps or modules, but may optionally include steps or modules not listed, or may optionally include other steps or modules inherent to the process, method, product, or apparatus.

[0060] refer to Figure 1 As shown, Figure 1 The figure is a schematic structural diagram of a vacuum coating device according to an embodiment, which mainly includes a vacuum chamber 100, a spectrum detection device 20 and a control system 30, wherein:

[0061] The vacuum chamber 100 is equipped with a product turntable 11 connected to a control system 30, a sputtering system 12 and an ion source 13, wherein the product turntable 11 is used to install the coating product, the sputtering system 12 installs the target material and sputters the coating material, and the ion source 13 is used to assist in thin film deposition.

[0062] The spectrum detection device 20 is connected to the control system 30 and is used to detect the spectrum energy data of the coated product during the coating process and report the data to the control system 30 .

[0063] The control system 30 can be used to control the operation of the product turntable 11, the sputtering system 12 and the ion source 13, collect the spectral energy data detected by the spectral detection device 20 and calculate the real-time transmittance of the coated product. When the film thickness is close to the target thickness, the actual thickness of the coated film is predicted based on the real-time transmittance; the layer change stop time is calculated according to the actual thickness and the layer change stop instruction is output to perform the layer change operation until the coating of all film layers is completed.

[0064] In one embodiment, reference Figure 2 As shown, Figure 2 This is a schematic structural diagram of the vacuum coating equipment of another embodiment; as shown in the figure, the spectral detection device 20 includes a light source 21 and a spectrometer 22 arranged on both sides of the product turntable 11, wherein the light source 21 outputs test light of different wavelengths, and the spectrometer 22 is used to detect spectral energy data and report it to the control system 30.

[0065] like Figure 2As shown, the control system 30 may include a host computer 31, a motion control board 32 and an optical control board 33; wherein the product turntable 11 is driven by a drive motor, the drive motor is connected to the motion control board 32 via a serial communication method, the motion control board 32 can be connected to the host computer 31 via a serial communication method and connected to the spectrometer 22 via an I / O interface, the spectrometer 22 can be connected to the optical control board 33 via a network cable, the optical control board 33 can be connected to the host computer 31 via a USB, and the host computer 31 is connected to the ion source 13 via a serial communication method.

[0066] In the coating control, the host computer 31 communicates and interacts with the motion control board 32 and the optical control board 33 respectively, the optical control board 33 communicates and interacts with the spectrometer 22, and the motion control board 32 controls the rotation of the product turntable 11 by driving the motor, and triggers the spectrometer 22 to detect spectral energy data.

[0067] Preferably, the host computer 31, motion control board 32 and optical control board 33 of the vacuum coating equipment of the above embodiment can further implement the following functions:

[0068] The optical control board 33 can be used to collect the spectral energy data detected by the spectral detection device 20 from the spectrometer 22 and upload it to the host computer 31. When the film thickness is close to the target thickness, the transmittance curve can be obtained from the host computer 31 and the actual thickness of the coated film can be predicted in real time. The layer change stop time is calculated based on the actual thickness and uploaded to the host computer 31.

[0069] The motion control board 32 can be used to receive control instructions from the host computer 31 to control the drive motor to rotate or stop the product turntable 11, monitor the angular position of the product turntable 11 in real time, and trigger the spectrometer 22 to detect spectral energy data at a specified angle.

[0070] The host computer 31 can be used to control the operation of the product turntable 11, the sputtering system 12 and the ion source 13, receive the spectral energy data reported by the optical control board 33 and fit the transmittance curve of the coated product, receive the layer change stop time reported by the optical control board 33 and output the layer change stop instruction according to the layer change stop time to perform the layer change operation.

[0071] In one embodiment, the structural design of the product turntable 11 may include a revolving disk and a plurality of workpiece disks evenly distributed on the revolving disk, wherein the workpiece disk is used to mount the coated product, and a through hole is provided on the rotating axis of the workpiece disk. The test light output by the light source 21 passes through the through hole and is received by the spectrometer 22. A monitoring piece is provided at at least one of the through hole positions, and at least one of the through hole positions is provided in a transparent state.

[0072] refer to Figure 3 As shown, Figure 3This is a schematic diagram of the structure of an example product turntable 11, which shows four workpiece disks. A monitoring piece is placed at at least one position in the through-hole of the monitoring piece installation position of the product turntable 11, and at least one position is kept in a transparent state. The through-hole in the black position in the figure is the through-hole for installing the monitoring piece, and the other three through-holes are in a transparent state; in use, the test light output by the light source 21 passes through the through-hole and is received by the spectrometer 22; during the rotation of the product turntable 11, when the through-hole where the monitoring piece is installed passes through the test light, the spectrometer 22 can receive the spectral energy of the test light after penetrating the monitoring piece. When the through-hole in a transparent state passes through the test light, theoretically the spectrometer 22 can receive 100% of the spectral energy of the test light, thereby calculating the transmittance of the monitoring piece; and when other parts pass through the test light, the test light is completely blocked, and at this time the spectral energy detected by the spectrometer 22 is the lowest.

[0073] As in the technical solution of the above embodiment, during the coating process, the real-time transmittance and estimated thickness of the coated product are used to ultimately predict the actual thickness, thereby being able to more accurately approach the optimal layer-changing position, thereby greatly improving the accuracy of layer-changing judgment and stopping, especially in coatings with a large number of layers, thereby avoiding the error accumulation caused by the increase in the number of coating layers and improving the film quality of the coated product.

[0074] Based on the vacuum coating equipment provided by the present application, an embodiment of a coating control method of the vacuum coating equipment is described below.

[0075] refer to Figure 4 As shown, Figure 4 The present invention is a flow chart of a vacuum coating equipment coating control method according to an embodiment, which mainly includes the following steps:

[0076] (1) Control the vacuum coating equipment to initialize.

[0077] In one embodiment, the initialization process may be as follows:

[0078] The host computer 31 sends an initialization instruction to the motion control board 32, driving the motor to rotate the product turntable 11 back to the origin and stop; the host computer 31 sends a coating process file loading instruction to the optical control board 33, loads the coating process file and saves it; after initialization, the product turntable 11 and the sputtering target are both rotated back to the origin, and the ion source 13 is initialized and the timer is reset.

[0079] Specifically, when the coating starts or each time a film layer is coated and the initialization state is entered, the host computer 31 initializes the timer to 0, the motion control board 32 drives the motor to rotate the product turntable 11 back to the origin, and rotates the sputtering target to 0 degrees. Then the host computer 31 sends a coating process file loading instruction to the optical control board 33, and the optical control board 33 loads the coating process file to obtain the substrate optical admittance η0 and the reference wavelength λ. D, coating layer number K, desired physical thickness d k (k = 1, 2, ..., K) and the optical admittance η of the coating material k etc.

[0080] (2) Control the product turntable 11 to rotate at a constant speed and start the ion source 13 and sputtering system 12 to enter the coating process.

[0081] In one embodiment, before entering the coating process, it is necessary to determine the angular position of the monitored coated product so as to accurately trigger the spectrometer 22 to collect spectral energy data in subsequent film thickness monitoring; accordingly, step (2) may further include the following steps:

[0082] S201 , the host computer 31 may also send a circular spectrum curve reporting request to the optical control board 33 and notify the motion control board 32 to control the product turntable 11 to rotate at a constant speed.

[0083] Specifically, the host computer 31 controls the product turntable 11 to rotate at a constant angular velocity of ωrad / s through the motion control board 32, and the spectrometer 22 detects different wavelengths λ every time it rotates 1°. i (i=1,2,…,m)corresponding spectral energy j(λ i ,θ), θ=1°, 2°,…,360°.

[0084] S202 , the motion control board 32 triggers the spectrometer 22 at a set period to measure spectral energy data corresponding to different wavelengths and reports the data to the host computer 31 .

[0085] Specifically, the motion control board 32 samples the spectral energy data detected by the spectrometer 22 every time the product turntable 11 rotates 1°. Therefore, within a 360° rotation, 360 sets of spectral energy data of different wavelengths detected by the spectrometer 22 can be collected.

[0086] S203 , the host computer 31 draws a circular spectrum curve based on the spectrum energy data corresponding to different wavelengths, calculates the lowest spectrum energy value, the highest spectrum energy value and the designated angle position corresponding to the real-time spectrum energy value, and sends them to the motion control board 32 .

[0087] Specifically, the host computer 31 selects a reference wavelength λ D After the product turntable 11 rotates a full circle, 360 sets of sampled spectral energy data are obtained from the optical control board 33, and the reference wavelength λ is fitted on the coordinate system. D Circular spectrum curve as the angle θ changes.

[0088] like Figure 5 As shown, Figure 5 This is an example of a circular spectrum curve, reference wavelength λ DThe spectral energy curve is located at the midpoint of the spectral energy between the highest spectral energy value and the lowest spectral energy value, and the lowest spectral energy value is determined to be energy J. b The maximum value of spectral energy is energy J w The median value of the spectral energy between the highest and lowest spectral energy is energy J t , based on this, the specified angle position θ can be determined according to the circumferential spectrum curve t .

[0089] After determining the specified angle position, step (2) may further include the following steps:

[0090] S204 , the host computer 31 notifies the motion control board 32 to drive the product turntable 11 to rotate at a set angular velocity; specifically, during the entire coating process, the host computer 31 can control the product turntable 11 to rotate at an angular velocity of ωrad / s.

[0091] S205, after the rotation angular velocity of the product turntable 11 is stabilized, the host computer 31 notifies the ion source 13 and the sputtering system 12 to start, and after the ion source 13 enters the normal working state, notifies the optical control board 33 to enter the ion beam coating program, select the current number of coating layers and initialize the timer.

[0092] Specifically, when the ion source 13 enters the normal working state, the optical control board 33 starts to execute the ion beam coating program. Assuming that the current number of coating layers is k=1, the initialization timer is t=0, and after the current film layer is coated, it is judged to stop and switch to the next film layer.

[0093] (3) Coating the current film layer, predicting the actual thickness of the coated film in real time, calculating the layer change stop time and outputting the layer change stop instruction.

[0094] In one embodiment, in order to obtain the real-time transmittance of the coated product, during the coating process, step (3) may include the following steps:

[0095] S301 , during the coating process, the motion control board 32 controls the product turntable 11 to rotate at a constant speed, and triggers the spectrometer 22 to detect spectral energy data when the turntable 11 rotates to a specified angle position.

[0096] Specifically, the motion control board 32 controls the product turntable 11 to rotate at a constant angular velocity of ωrad / s. b 、J w and J t At time t, the motion control board 32 triggers the spectrometer 22 to detect spectral energy data.

[0097] S302 , the optical control board 33 collects in real time the spectral energy data measured by the spectrometer 22 each time the product turntable 11 rotates one circle, calculates in real time the transmittance array of each wavelength point based on the spectral energy data and uploads it to the host computer 31 .

[0098] Specifically, when coating each film layer, the product turntable 11 needs to rotate multiple times. After each rotation of the product turntable 11, the optical control board 33 can collect spectral energy data of multiple wavelength points from the spectrometer 22 and calculate the transmittance array corresponding to the current number of rotations. The calculation formula can be as follows:

[0099]

[0100] Among them, T(λ i ) represents the wavelength λ i The transmittance under b (λ i ) is the wavelength λ i The lowest value of the spectral energy under w (λ i ) is the wavelength λ i The highest value of spectral energy under t (λ i ) is the target product wavelength λ collected by the spectrometer 22 i The spectral energy value below.

[0101] Thus, an array of transmittances at multiple wavelengths corresponding to the number of rotations μ can be formed, and the optical control board 33 reports the transmittance array to the host computer 31 .

[0102] S303 , the host computer 31 fits a transmittance curve according to the transmittance array.

[0103] Specifically, the host computer 31 can fit the transmittance curve using the transmittance array, such as Figure 6 As shown, Figure 6 It is an example transmittance curve diagram. The host computer 31 can fit the wavelength-transmittance curve of the target product circle by circle and keep it updated for the optical control board 33 to call.

[0104] S304: The optical control board 33 calculates the estimated thickness of the deposited film at the current moment in real time.

[0105] Specifically, the optical control board 33 calculates the estimated thickness of the film layer at the current moment using the known coating rate and coating time; for example, when an ion beam sputtering coating machine is used for coating, the film deposition rate v is relatively stable, so the estimated thickness d at the current moment can be calculated. est , the calculation formula is as follows:

[0106] d est=v·t (2)

[0107] As described above, the film deposition rate v and time t can be read in real time from the timer, from which the estimated thickness at the current moment can be calculated.

[0108] S305 , when the estimated thickness reaches a set ratio of the target thickness, a random search method is used to correct the estimated thickness to obtain an actual thickness.

[0109] For example, when d est ≥a·d k , where a is the proportional coefficient, taking a = 99%, and then calculating the real-time transmittance T of the target product based on the spectral energy data collected by the spectrometer 22 real , and then use the random search method to estimate the thickness d est Perform iterative update to get the actual thickness d real .

[0110] In one embodiment, a method for obtaining the actual thickness of the optical control plate 33 using a random search method may include the following steps:

[0111] (a) Use the theoretical transmittance calculation function to calculate the transmittance corresponding to the estimated thickness and the baseline transmittance difference between it and the actual transmittance.

[0112] For example, the estimated thickness d is calculated using the theoretical transmittance calculation function est The corresponding reference transmittance T est 1, and calculate the actual transmittance T according to the spectral energy data detected by the spectrometer 22 real .

[0113] The optical control board 33 can obtain the transmittance curve from the host computer 31, such as Figure 6 In the example, assuming that the host computer 31 has recently fitted a transmittance curve with a turn number μ=3, the optical control board 33 can calculate the actual transmittance at the current moment by calling the transmittance curve.

[0114] For the theoretical transmittance calculation function, its calculation method can be based on the specified wavelength λ i The substrate optical admittance η0 and reference wavelength λ under D , coating layer number K, target thickness d k (k = 1, 2, ..., K) and the optical admittance η of the coating material k To calculate the transmittance T corresponding to the film thickness est , the calculation formula can be as follows:

[0115]

[0116] in:

[0117]

[0118]

[0119] Therefore, the reference transmittance T can be calculated by the above theoretical transmittance calculation function. est 1, then calculate the reference transmittance T est 1 and the actual transmittance T real The reference transmittance difference f1 between them is used as the reference transmittance difference.

[0120] In the case of different wavelengths, the calculation formula for the transmittance difference can be as follows:

[0121]

[0122] Among them, the reference transmittance difference f1 can be calculated by the above formula (4), and the actual transmittance T real It can be calculated in real time using the transmittance curve.

[0123] (b) randomly generating a thickness update value based on the estimated thickness.

[0124] For the method of generating thickness update value, the estimated thickness d est , update the iteration step size Δ step And the random number generated thickness update value d within the set range temp :

[0125] d temp =d est +rand(-1,1)×△ step ×0.1×d est (5)

[0126] Among them, rand(-1,1) represents a random number between -1 and 1, Δ step is the update iteration step size.

[0127] (c) Calculating the transmittance corresponding to the thickness update value and the updated transmittance difference between the transmittance and the actual transmittance using the theoretical transmittance calculation function.

[0128] Specifically, update the value d according to the thickness temp And d temp Replace d est Calculate the updated transmittance T est 2, then according to the actual transmittance T real Calculate and update the transmittance difference f2.

[0129] (d) Using the thickness update value, iteratively search the estimated thickness to obtain the actual thickness.

[0130] As an embodiment, the iterative update may include the following steps:

[0131] ①In the set thickness optimization range d lim , update the iteration step size Δ step Under the iterative conditions of its update coefficient h and the maximum number of iterations N, the updated transmittance difference f2 is compared with the reference transmittance difference f1.

[0132] ② When the updated transmittance difference is less than or equal to the reference transmittance difference, the estimated thickness is updated using the thickness update value, and the reference transmittance difference is updated using the updated transmittance difference.

[0133] Specifically, when f2≤f1 and the thickness is updated, and within the thickness optimization range d lim If the current search direction is correct, use d temp Update d as the base value est , and use f2 to update f1, and then calculate the thickness update value d temp And proceed to the next iterative calculation.

[0134] ③ When the updated transmittance difference is greater than the reference transmittance difference, the estimated thickness is not updated, and the iteration step is reduced according to the iteration step update coefficient.

[0135] Specifically, when f2>f1, it means that the current search direction is incorrect and the reference value d is not updated. est At the same time, reduce the update coefficient h of the iteration step size and update the iteration coefficient h=h+f1 2 and iteration step size Calculate the thickness update value d temp And proceed to the next iteration.

[0136] ④ Repeatedly use the randomly generated thickness update value to iteratively update the estimated thickness until the maximum number of iterations is reached to obtain the actual thickness of the current coating.

[0137] Before reaching the maximum number of iterations N, the iterative search process is repeated, and the new thickness update value d is continuously searched in the judgment process of ①-③. temp , and continuously approaches the actual physical thickness of the current coating layer. When the number of updates reaches the maximum number of iterations N, the currently calculated thickness is updated to the value d temp As the actual thickness d real .

[0138] In the above technical solution, the optical control panel 33 updates and iterates the estimated thickness by combining random search with theoretical transmittance calculation, and accurately calculates the actual thickness that is close to the real physical thickness.

[0139] S306 , calculating the layer change stop time according to the actual thickness and reporting the layer change stop time to the host computer 31 .

[0140] Specifically, the optical control board 33 utilizes the stable deposition rate characteristic of the ion beam sputtering coating machine, calls formula (2) and substitutes the updated actual thickness d real , real-time calculation of the layer change judgment stop time t from the current moment to the optimal layer change position est , the calculation formula is as follows:

[0141]

[0142] Among them, t est is the layer change judgment stop time, d j is the target thickness, i.e. the expected physical thickness of the current coating layer, d real is the actual thickness calculated.

[0143] In order to avoid throwing the coated products on the product turntable 11 away, the rotation speed of the product turntable 11 is generally not set too fast, and the corresponding sampling period of the spectrometer 22 cannot be set too short. The layer change stop time is within the two sampling intervals of the spectrometer 22 to avoid the accumulation of single-layer errors.

[0144] Accordingly, in one embodiment, considering the actual thickness d real It is obtained by sampling the spectrum energy data of the spectrometer for 22 cycles. Therefore, in order to improve the accuracy of outputting the layer change judgment and stop instruction, when the layer change judgment and stop time t est When more than one sampling period is exceeded, the actual thickness d can be calculated in the next sampling period. real and layer change judgment stop time t est , and then perform timing and waiting. Specifically, the technical solution can be as follows:

[0145] ① Calculate the sampling period of the spectrometer 22 detection according to the rotation angular velocity of the product turntable 11 in the ion beam sputtering coating process.

[0146] For example, since the product turntable 11 rotates at an angular velocity of ωrad / s, the spectrometer 22 collects spectral energy data once when the product turntable 11 makes one circle. Therefore, the sampling period of the spectrometer 22 is

[0147] ② If the layer-changing judgment stop time is greater than the sampling period, the estimated thickness is corrected by the random search method to obtain the actual thickness of the current film layer before the next sampling period arrives.

[0148] Specifically, when t est >TS When t is 0, it means that the spectrometer 22 can collect spectral energy data once before changing the layer, so the layer change can be delayed until the next sampling period. At this time, after the spectrometer 22 samples the spectral energy data, the actual thickness of the front film layer is repeatedly corrected until t est <T S Change layers again.

[0149] ③ If the layer-changing judgment stop time is less than or equal to the sampling period, a layer-changing judgment stop instruction is output after the layer-changing judgment stop time is reached.

[0150] Specifically, when t est <T S , indicating that the layer change judgment stop time is within the current sampling period. Therefore, the optical control board 33 sets the layer change judgment stop time t est Report to the host computer 31.

[0151] S307, the host computer 31 outputs a layer change judgment stop instruction when the layer change judgment stop time arrives.

[0152] Specifically, the host computer 31 can calculate the floor change judgment stop time t est After that, the timer is used to count the time. est Then the layer change stop instruction is output to change the layer.

[0153] (4) Controlling the vacuum coating equipment to perform a layer-changing operation and coating the next film layer.

[0154] As an embodiment, for the output layer switching operation, the host computer 31 can notify the ion source 13 to shut down, send a layer switching stop instruction to the optical control board 33 to stop the spectrometer 22, reset the timer, and notify the motion control board 32 to drive the product turntable 11 to switch the sputtering target and prepare for the next layer of coating.

[0155] (5) Complete all film layers in the coating process.

[0156] Specifically, if a multi-layer optical film is being coated, the host computer 31 can also control the timer to reset, turn off the monitoring of the ion source 13 and the spectrometer 22, and prompt to switch the sputtering target, set k=k+1, and prepare for the coating process of the next film layer until all film layers are coated.

[0157] In summary of the above embodiments, the technical solution provided by the present application can improve the accuracy of layer change judgment and stop during the coating process of multi-layer coating, and improve the coating quality. In particular, when applied to the coating of optical equipment based on wide-spectrum film thickness monitoring, it can avoid the delay defect of the layer change judgment and stop point, suppress the error accumulation caused by the increase in the number of coating layers, and ensure the spectral characteristics of the optical thin film product. Moreover, this technical solution can make the repeatability of the coating process fully meet the requirements of industrial production, and has important promotion significance in the vacuum coating industry. In the current application examples, this technical solution has greatly improved the quality of optical thin film products, and various spectral index parameters have been greatly improved compared with conventional technologies. In particular, for optical thin film products with multi-layer coating, the spectral index parameters of each layer are very close to the design index, and the effect is obvious.

[0158] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A vacuum coating device, characterized in that: include: A vacuum chamber having a built-in product turntable connected to a control system, a sputtering system, and an ion source, wherein the product turntable is used to mount the coated product, the sputtering system is used to mount the target material and sputter the coating material, and the ion source is used to assist in thin film deposition; A spectrum detection device, connected to the control system, for detecting the spectrum energy data of the coated product during the coating process and reporting the data to the control system; Control system, including: host computer, motion control board and optical control board; The host computer is used to control the operation of the product turntable, sputtering system and ion source; and receive spectral energy data reported by the optical control board, calculate the real-time transmittance of the coated product and fit the transmittance curve of the coated product; receive the layer change judgment stop time reported by the optical control board and output the layer change judgment stop instruction according to the layer change judgment stop time to perform the layer change operation until the coating of all film layers is completed; The motion control board is used to receive control instructions from the host computer to control the rotation of the product turntable and trigger the spectrum detection device to detect spectrum energy data; The optical control board is used to collect the spectral energy data detected by the spectral detection device and upload it to the host computer; calculate the estimated thickness of the coated film at the current moment in real time, and when the estimated thickness is close to the target thickness, obtain the transmittance curve from the host computer and correct the estimated thickness in real time to predict the actual thickness of the coated film; calculate the layer change stop time based on the actual thickness; wherein, when the estimated thickness reaches a set ratio of the target thickness, the estimated thickness is close to the target thickness.

2. The vacuum coating equipment according to claim 1, characterized in that: The spectrum detection device includes a light source and a spectrometer arranged on both sides of the product turntable; wherein the light source outputs test light of different wavelengths, and the spectrometer is used to detect spectral energy data and report it to the control system; The product turntable is driven by a drive motor, the motion control board is connected to the host computer and the spectrometer respectively, and the spectrometer is connected to the host computer via an optical control board; The host computer communicates and interacts with the motion control board and the optical control board respectively; The optical control board communicates and interacts with the spectrometer; The motion control board controls the rotation of the product turntable through the drive motor.

3. The vacuum coating equipment according to claim 2, characterized in that: The optical control board is used to collect spectral energy data detected by the spectral detection device from the spectrometer and upload it to the host computer, obtain the transmittance curve from the host computer when the estimated thickness is close to the target thickness and predict the actual thickness of the coated film in real time, and calculate the layer change judgment stop time based on the actual thickness and upload it to the host computer; The motion control board is used to receive control instructions from the host computer to control the drive motor to rotate or stop the product turntable, monitor the angular position of the product turntable in real time, and trigger the spectrometer to detect spectral energy data at a specified angle; The host computer is used to control the operation of the product turntable, sputtering system and ion source, receive the spectral energy data reported by the optical control board and fit the transmittance curve of the coated product, receive the layer change stop time reported by the optical control board and output the layer change stop instruction according to the layer change stop time to perform the layer change operation.

4. The vacuum coating equipment according to claim 3, characterized in that: The product turntable includes a public turntable and a plurality of workpiece disks evenly distributed on the public turntable; wherein, The workpiece plate is used to mount the coated product; A through hole is provided on the rotating shaft of the workpiece disk, and the test light output by the light source passes through the through hole and is received by the spectrometer. A monitoring piece is provided at at least one of the through holes, and at least one of the through holes is provided in a transparent state.

5. A coating control method for a vacuum coating device, applied to the vacuum coating device according to any one of claims 1 to 4, characterized in that: include: Control the vacuum coating equipment to initialize; Control the product turntable to rotate at a constant speed and start the ion source and sputtering system to enter the coating process; Coating the current film layer, predicting the actual thickness of the coated film in real time, calculating the layer change stop time and outputting the layer change stop instruction; Controlling the vacuum coating equipment to perform a layer-changing operation and coating the next film layer; Complete all film layers in the coating process.

6. The coating control method of vacuum coating equipment according to claim 5, characterized in that: The controlling of the vacuum coating equipment to perform initialization includes: The host computer sends an initialization command to the motion control board, driving the motor to rotate the product turntable back to the origin and stop; The host computer sends a coating process file loading instruction to the optical control board, loads the coating process file and saves it; The process of controlling the product turntable to rotate at a constant speed and starting the ion source and sputtering system to enter the coating process includes: The host computer notifies the motion control board to drive the product turntable to rotate at the set angular velocity; After the product turntable's rotation angular velocity stabilizes, the host computer notifies the ion source and sputtering system to start, and after the ion source enters normal working state, it notifies the optical control board to enter the ion beam coating program, select the current number of coating layers and initialize the timer.

7. The coating control method of vacuum coating equipment according to claim 6, characterized in that: Before controlling the product turntable to rotate at a constant speed and starting the ion source and sputtering system to enter the coating process, the process also includes: The host computer sends a circular spectrum curve reporting request to the optical control board and notifies the motion control board to control the product turntable to rotate at a constant speed; The motion control board triggers the spectrometer at a set period to measure the spectral energy data corresponding to different wavelengths and report it to the host computer; The host computer draws a circular spectral curve based on the spectral energy data corresponding to different wavelengths, calculates the specified angle position and sends it to the motion control board; wherein, the specified angle position is the angle position corresponding to the lowest spectral energy value, the highest spectral energy value and the real-time spectral energy value on the circular spectral curve.

8. The coating control method of vacuum coating equipment according to claim 6, characterized in that: The method of predicting the actual thickness of the deposited film in real time, calculating the layer change judgment stop time and outputting the layer change judgment stop instruction includes: During the coating process, the motion control board controls the product turntable to rotate at a constant speed. When it rotates to a specified angle, it triggers the spectrometer to detect spectral energy data. The optical control board collects the spectral energy data measured by the spectrometer every time the product turntable rotates one circle in real time, calculates the transmittance array of each wavelength point in real time based on the spectral energy data, and uploads it to the host computer; The host computer fits the transmittance curve according to the transmittance array; The optical control board calculates the estimated thickness of the film at the current moment in real time. When the estimated thickness reaches a set ratio of the target thickness, the estimated thickness is corrected using a random search method to obtain the actual thickness and the layer change stop time is calculated. The layer change stop time is reported to the host computer. The upper computer outputs the layer change judgment stop instruction when the layer change judgment stop time is reached.

9. The coating control method of vacuum coating equipment according to claim 8, characterized in that: The method of using a random search method to correct the estimated thickness to obtain the actual thickness and calculate the layer change stop time includes: Obtain the target thickness from the coating process file and calculate the estimated thickness of the current coating according to the deposition rate of the ion beam sputtering coating; Read the transmittance curve from the host computer and calculate the current actual transmittance, calculate the transmittance corresponding to the estimated thickness and the transmittance difference between it and the actual transmittance; randomly generating a thickness update value, and using the thickness update value to iteratively search the estimated thickness to obtain the actual thickness; Calculate the layer change judgment stop time from the current moment to the layer change point according to the actual thickness. If the layer change judgment stop time is greater than the sampling period of the spectrometer detection, continue to calculate the actual thickness before the next sampling period arrives; If the layer-changing judgment stop time is less than or equal to the sampling period, a layer-changing judgment stop instruction is output after the layer-changing judgment stop time is reached.

10. The coating control method of vacuum coating equipment according to claim 9, characterized in that: The controlling the vacuum coating equipment to perform a layer-changing operation and coating the next film layer includes: The host computer notifies the ion source to shut down, sends a layer change stop command to the optical control board to stop the spectrometer, resets the timer, and notifies the motion control board to drive the product turntable to switch the sputtering target and prepare for the next layer of coating.

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