Vacuum coating online monitoring system

Abstract

The invention provides a vacuum coating on-line monitoring system. The vacuum coating on-line monitoring system comprises a data processing module, a light blocking module, and a laser light source module, a homogenizing and beam expanding light path and a light sensing module which are accommodated in the light blocking module, a light outlet and a light inlet are formed in the light blocking module; the laser light source module is used for emitting laser with at least two different wavelengths; the homogenizing and beam-expanding light path is used for receiving the laser emitted by the laser light source module and emitting the laser through a light outlet after homogenizing and beam-expanding the laser; wherein the emergent laser can irradiate a coated product, and reflected light formed by reflection of the coated product can enter the light blocking module through the light inlet; the light sensing module is used for receiving the reflected light and obtaining light sensing data of the coated surface of the coated product according to the reflected light; and the data processing module is used for obtaining real-time coating parameters of the coating surface of the coating product according to the photosensitive data. According to the invention, real-time accurate and more-dimensional monitoring of the coating condition of the coated product can be realized.

Description

Technical Field

[0001] The present invention relates to the field of vacuum coating, and in particular to an online monitoring system for vacuum coating. Background Art

[0002] With the rapid development of high-tech industries, the requirements for material surface properties are becoming increasingly stringent. Vacuum coating technology, as a highly efficient means of improving material surface properties, is widely used in various fields such as semiconductors, optics, and decoration.

[0003] In vacuum coating, film thickness and color are the two most important parameters. Film thickness is generally measured in microns, typically between 0.1μm and 5μm. Vacuum coating thickness can be measured using a variety of methods, including interferometry, X-ray fluorescence (XRF), step profilers, quartz crystal oscillation, single-wavelength extremum analysis, wide-spectrum scanning, ellipsometry, and white-light interferometry. Ellipsometry offers the highest stability and accuracy, but requires a relatively flat sample surface to minimize the impact of scattering and other non-ideal optical effects on the measurement results, limiting its applicability. Wide-spectrum scanning offers relatively high measurement accuracy, but the equipment cost is high, the optical path is complex, filtering is difficult, and it is susceptible to interference. White-light interferometry, which shares a similar principle, requires strict calibration and parameter adjustment. Performance indicators such as spectral resolution, wavelength range, and light source stability all affect the accuracy and stability of the measurement results, and its measurement capabilities vary significantly for different film materials.

[0004] The color of vacuum-coated films can be accurately measured using a spectrophotometer or monitored online using CCD and CMOS sensors. However, because the deposition process is often accompanied by light radiation (gas glow, arc light, thermal radiation, etc.), stray light can easily interfere with the sensor, resulting in limited accuracy for online color monitoring.

[0005] In summary, existing offline and online detection methods cannot meet the dual requirements of modern production for vacuum coating efficiency and accuracy. Summary of the Invention

[0006] In view of this, an object of the present invention is to provide a vacuum coating online monitoring system to improve the above-mentioned problem.

[0007] An embodiment of the present invention provides an online monitoring system for vacuum coating, which is suitable for installation in the middle or on the wall of a vacuum chamber of a vacuum coating device, and includes: a data processing module, a light shielding module, and a laser light source module, a homogenized beam expansion optical path, and a photosensitive module housed in the light shielding module; wherein: The light blocking module is formed with a light outlet and a light inlet; The laser light source module is fixed in the light blocking module and is used to emit lasers of at least two different wavelengths; The homogenizing and beam expanding optical path is used to receive the laser light emitted by the laser light source module, homogenize and expand the laser light, and then emit it through the light outlet; wherein the emitted laser light can irradiate the coated product, and the reflected light formed by the coating product can enter the light blocking module through the light inlet; a photosensitive module, configured to receive the reflected light inputted through the light inlet, obtain photosensitive data of the coated surface of the coated product according to the reflected light, and send the photosensitive data to the data processing module; The data processing module is used to obtain real-time coating parameters of the coating surface of the coating product based on at least the photosensitive data.

[0008] Preferably, the laser light source module includes a laser light source and a heat sink, and the laser light source is arranged on the heat sink.

[0009] Preferably, the light source module is a multi-mode laser diode or a multi-mode laser diode array, and the wavelengths of the multiple laser beams emitted by it are in the wavelength range of red, green and blue visible light.

[0010] Preferably, the wavelengths of the multiple laser beams are 465 nm, 525 nm, and 643 nm respectively.

[0011] Preferably, along the optical path direction of the laser emitted by the laser light source module, the homogenized beam expansion optical path includes a homogenizing glass piece, a first fly-eye lens, a reflector, a second fly-eye lens, a cylindrical mirror and an aperture arranged in sequence; the light hole of the aperture is aligned with the light outlet of the light blocking module.

[0012] Preferably, the light blocking module is a shell made of a conductive material and is connected to a DC bias power supply.

[0013] Preferably, the photosensitive module includes a filter module and a light sensor; The light filtering module is arranged at the light entrance, and is used to receive the reflected light and send it to the light sensor after filtering; The light sensor is used to receive the filtered emitted light, obtain the light-sensitive data of the coated surface of the coated product, and send the data to the data processing module.

[0014] Preferably, the light sensor includes one or more of a monochrome or color CMOS, a CCD camera, and an infrared thermal imager.

[0015] Preferably, the data processing module is specifically used to: The light sensor collects light data to monitor the intensity of reflected light over time, and deduce the growth rate, thickness, and surface condition of the film during the coating process. By integrating the intensity information of the reflected light of lasers of different wavelengths, the film thickness of each film layer and the light absorption rate of the film at each wavelength in the absence of interference are obtained. The absorption spectrum curve of the film layer is fitted with reference to the chemical composition of each film layer and the light absorption spectrum of the standard sample to obtain the color value of each film layer.

[0016] Preferably, the data processing module is further used for: Acquire real-time working data collected by a data acquisition module of the vacuum coating equipment, and obtain real-time process data based on the real-time working data and the real-time coating parameters of each film layer; The real-time process data is compared and analyzed with the standard process data of the pre-imported standard process, and the coating process parameters are adjusted in real time according to the analysis results.

[0017] In summary, the vacuum coating monitoring system according to this embodiment can realize real-time, accurate, and multi-dimensional monitoring of the coating condition of coated products. Compared with the prior art, this embodiment has at least the following advantages: 1. Using laser light source for detection, the laser line width is much lower than other light sources, which can resist stray light interference and has higher accuracy; 2. Wide monitoring range, real-time detection of surface temperature, thickness, color, deposition rate, film structure, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of a vacuum coating online monitoring system provided by an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the installation of the vacuum coating online monitoring system in the vacuum coating equipment.

[0020] Figure 3 This is a schematic diagram of the vacuum coating online monitoring system installed on the side wall of the vacuum coating equipment.

[0021] Figure 4 This is a schematic diagram of the vacuum coating online monitoring system installed in the middle of the vacuum coating equipment.

[0022] Figure 5 Schematic diagram of the reflection of incident light between the film layer and the substrate.

[0023] Figure 6 This is a graph showing how the total reflectivity changes with film thickness when three films with different absorption coefficients are deposited separately. DETAILED DESCRIPTION

[0024] To further understand the content of the present invention, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only intended to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only the portions relevant to the invention are shown in the accompanying drawings.

[0025] See also Figure 1 The embodiment of the present invention provides a vacuum coating online monitoring system 100, which is suitable for installation on the vacuum chamber wall (such as Figure 2 and Figure 3 as shown) or in the middle (as Figure 4 As shown), and includes: a data processing module, a light blocking module 10, and a laser light source module, a homogenized beam expansion optical path and a photosensitive module accommodated in the light blocking module 10; wherein: The light blocking module 10 is formed with a light exit 11 and a light entrance 12 .

[0026] In this embodiment, the light blocking module 10 has two functions: one is to form a relatively stable space for the installation and fixation of the laser light source module, the homogenized beam expansion optical path and the photosensitive module; the other is to block external light to prevent the glow light source or arc light source of the vacuum chamber from directly shining into the monitoring system 100, thereby interfering with the monitoring results.

[0027] Preferably, the light blocking module 10 can be a housing made of conductive material, such as aluminum, copper or stainless steel, etc. The housing is formed with a light outlet 11 and a light inlet 12 on the surface facing the coating product 300 for light emission and reflected light entry.

[0028] Particularly, the shapes of the light outlet 11 and the light entrance 12 may be rectangular, and of course may be other shapes, such as circular, which are not specifically limited in the present invention.

[0029] In particular, the light outlet 11 and the light entrance 12 can be two independent openings or two parts of one opening, and these solutions are all within the protection scope of the present invention.

[0030] In particular, the light blocking module 10 is also connected to a DC bias power supply, which is used to charge the light blocking module 10 and thereby reduce the positively charged particles entering from the opening to protect the light path. The voltage can be 10~80V.

[0031] The laser light source module is fixed in the light blocking module 10 and is used to emit lasers of at least two different wavelengths.

[0032] In this embodiment, the laser light source module includes a laser light source 21 and a heat sink 22 , and the laser light source 21 is disposed on the heat sink 22 .

[0033] The light source module may be a multi-mode laser diode or a multi-mode laser diode array, and the wavelengths of the multiple laser beams emitted by the light source module are within the wavelength range of red, green and blue visible light.

[0034] Among them, in particular, the number of multiple laser beams is three, and the wavelengths are 465nm, 525nm, and 643nm respectively. Of course, more or fewer laser beams can be set according to actual needs, such as 2, 4, 5, etc. The wavelength of each laser beam can be set according to actual needs, such as setting the wavelength of the laser according to the thin film characteristics of the coated product. These schemes are all within the scope of protection of the present invention.

[0035] The homogenized beam expansion optical path is used to receive the laser emitted by the laser light source module, homogenize and expand the laser beam, and then emit it through the light outlet 11; wherein, the emitted laser beam can irradiate the coated product 300, and the reflected light formed by the reflection of the coated product 300 can enter the light blocking module 10 through the light inlet 12.

[0036] In this embodiment, since the beam width of the laser light is relatively small and the incident intensity is non-uniform (the intensity distribution of the laser light is similar to that of a Gaussian beam, so the intensity is non-uniform), in order to obtain better measurement results, it is necessary to homogenize and expand the beam.

[0037] In this embodiment, in particular, along the optical path direction of the laser emitted by the laser light source module, the homogenized beam expansion optical path includes a homogenizing glass piece 31, a first fly-eye lens 32, a reflector 33, a second fly-eye lens 34, a cylindrical mirror 35 and an aperture 36 arranged in sequence; the light hole of the aperture 36 is aligned with the light outlet 11 of the light blocking module 10.

[0038] The laser light emitted by the laser light source module first passes through the homogenizing glass sheet 31 before being incident on the first fly-eye lens 32. It is then reflected by the reflector 33 to the second fly-eye lens 34, thereby improving the uniformity of the beam. The fly-eye lens is a lens. When a laser beam with uneven incident intensity is incident, the light is incident on each of the multiple convex lenses that make up the fly-eye lens. The light incident on the convex lenses forms an image toward the focal point. Each convex lens generates an image, and these images are superimposed on the output surface. Because the images overlap, the laser beam, which had uneven intensity upon incident, is emitted with uniform intensity.

[0039] In this embodiment, the cylindrical mirror 35 is an aspheric lens, which can effectively reduce spherical aberration and chromatic aberration, and can also play a one-dimensional amplification role on the light beam, that is, play a role of beam expansion.

[0040] In this embodiment, the aperture 36 can play a significant role in shaping the shape of the emitted laser beam through its aperture. For example, if the aperture is rectangular, the cross-section of the emitted laser beam is also rectangular.

[0041] In this embodiment, the laser light emitted from the light hole irradiates the coating surface of the coating product 300 through the light outlet 11 , and returns to the light shielding module 10 through the light inlet 12 after being reflected from the coating surface.

[0042] The photosensitive module is used to receive the reflected light input through the light inlet 12, obtain photosensitive data of the coated surface of the coated product 300 according to the reflected light, and send the photosensitive data to the data processing module.

[0043] In this embodiment, the photosensitive module includes a filter module 41 and a light sensor 42; The light filtering module 41 is used to receive the light reflected by the coated product 300 and send the light to the light sensor 42 after filtering.

[0044] In this embodiment, the filter module 41 is located in front of the light sensor 42, which can be installed at the light entrance 12 and is composed of one or more filters for filtering background stray light or interference light, thereby improving the accuracy of monitoring.

[0045] The light sensor 42 is used to receive the filtered light, obtain the light-sensitive data of the coated surface of the coated product, and send the data to the data processing module.

[0046] The light sensor includes one or more of a monochrome or color CMOS, a CCD camera, and an infrared thermal imager.

[0047] The data processing module is used to obtain real-time coating parameters of the coating surface of the coating product 300 based on at least the photosensitive data.

[0048] In this embodiment, the data processing module can be a computing device with data processing capabilities, such as a laptop computer, desktop computer, PDA, etc., which has processing software installed in it and can obtain the real-time coating parameters of the coating surface of the coating product based on the processing software and the photosensitive data.

[0049] Specifically, the data processing module has the following functions: By monitoring the change in intensity of the reflected light over time using the light sensor 42, the growth rate, growth thickness and surface condition of the film during the coating process can be deduced. By integrating the intensity information of the reflected light of lasers of different wavelengths, the film thickness of each film layer and the light absorption rate of the film at each wavelength in the absence of interference are obtained. The absorption spectrum curve of the film layer is fitted with reference to the chemical composition of each film layer and the light absorption spectrum of the standard sample to obtain the color value of each film layer.

[0050] Specifically, the reflected light of the laser I0 irradiated on the surface of the coated product at each film layer is recorded as I1, I2, I3... n , then the total intensity of the reflected light I≈I1+I2+2(I1I2) 0.5 *cos2πΔλ+I3+…+I n ; In the actual coating process, I1 changes with the surface material, and I2 is related to the film material and thickness.

[0051] The working principle of the present invention will be explained below with a practical example. To simplify the calculation, only air, film layer 1, film layer 2 and substrate are considered. The refractive index n0 of air (vacuum and low-pressure vacuum during the coating process are both considered air) is approximately 1; the refractive index of film layer 1 is: , k1 is the absorption coefficient of film layer 1, the thickness of film layer 1 is d1, and d1 is a variable during coating; The refractive index of film layer 2 is: , k2 is the absorption coefficient of film layer 2, the thickness of film layer 2 is d2, and d2 remains unchanged during coating; The refractive index of the substrate is: ; k3 is the absorption coefficient of the substrate.

[0052] Thus, the total reflectivity is: , The reflection coefficients of air and film layer 1 are: , The equivalent reflection coefficients of film layer 1, film layer 2 and substrate are: , The interface reflection coefficient between film layer 1 and film layer 2 is: , The interface reflection coefficient between film layer 2 and substrate is: , The phase thickness of the jth layer is:

[0053] If the refractive index of film layer 1 and film layer 2 is determined, the curve of the reflectivity of this monochromatic light changing with the film thickness d can be obtained (∆d=∆d1). Figure 6As shown in FIG, it shows a graph showing the total reflectivity changing with film thickness when three different absorption coefficient films 1 are deposited. The principle is that coherent light interferes on the surface of the film, affecting the intensity of the reflected light.

[0054] Specifically, when the film thickness changes, the reflectivity also changes periodically. The oscillation period of light of different wavelengths is also different, representing the thickness = λ / 2n. By monitoring the temporal changes in the intensity of the reflected coherent light using a light sensor, information such as the film's growth rate, thickness, and surface condition can be derived during the process. By integrating the reflected light intensity information of light of different wavelengths and processing the data, the film thickness and the corresponding light absorption rate of the film at each wavelength in the absence of interference can be determined. By referring to the chemical composition of the film and the light absorption spectrum of a standard sample, the absorption spectrum curve of the film can be further fitted to determine the film's color value.

[0055] In this embodiment, further, based on the real-time parameters of the thin film obtained above, the data processing module can also be used to calibrate and optimize the coating process parameters.

[0056] Specifically: First, pre-production calibration is performed using a standard plate, and process data from the standard process is imported.

[0057] Then, the light sensor 42 and the data acquisition module of the vacuum coating equipment are used to collect parameters such as temperature, pressure, reflection intensity of lasers of different wavelengths on the product surface, infrared light emission intensity on the product surface, etc. during the coating process in real time, and quickly process them to obtain real-time data such as the product's real-time surface temperature, color, coating thickness, coating deposition speed, and film structure.

[0058] Next, data analysis and feedback control are carried out: the real-time data is compared and analyzed with the process data of the standard process, and the coating process parameters are adjusted in real time according to the analysis results, so that the real-time data of the light sensor gradually approaches the standard process.

[0059] Finally, there is post-production calibration: high-precision equipment is used to measure and analyze the film structure, thickness, color, etc. of the coated products. Combined with the online measurement data during the coating process, the real-time processing algorithm is calibrated and optimized, and any deviation from the preset standards is identified.

[0060] In summary, the vacuum coating monitoring system according to this embodiment can realize real-time, accurate, and multi-dimensional monitoring of the coating condition of coated products. Compared with the prior art, this embodiment has at least the following advantages: 1. Using laser light source for detection, the laser line width is much lower than other light sources, which can resist stray light interference and has higher accuracy; 2. Wide monitoring range, real-time detection of surface temperature, thickness, color, deposition rate, film structure, etc. 3. Easy calibration, you can use standard plates for pre-production calibration or test tapes for post-production calibration; 4. The data processing algorithm has a large optimization space and a wide range of applications. Independent setting of the algorithm for the film layer of a specific process can increase the measurement accuracy.

[0061] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention.

Claims

1. A vacuum coating online monitoring system, suitable for installation in the middle or cavity wall of a vacuum chamber of a vacuum coating equipment, characterized in that: include: A data processing module, a light blocking module, a laser light source module housed in the light blocking module, a homogenized beam expansion optical path, and a photosensitive module; wherein: The light blocking module is formed with a light outlet and a light inlet; The laser light source module is fixed in the light blocking module and is used to emit lasers of at least two different wavelengths; The homogenizing and beam expanding optical path is used to receive the laser light emitted by the laser light source module, homogenize and expand the laser light, and then emit it through the light outlet; wherein the emitted laser light can irradiate the coated product, and the reflected light formed by the coating product can enter the light blocking module through the light inlet; a photosensitive module, configured to receive the reflected light inputted through the light inlet, obtain photosensitive data of the coated surface of the coated product according to the reflected light, and send the photosensitive data to the data processing module; The data processing module is used to obtain real-time coating parameters of the coating surface of the coating product based on at least the photosensitive data.

2. The vacuum coating online monitoring system according to claim 1, characterized in that: The laser light source module includes a laser light source and a heat sink, and the laser light source is arranged on the heat sink.

3. The vacuum coating online monitoring system according to claim 2, characterized in that: The light source module is a multi-mode laser diode or a multi-mode laser diode array, and the wavelengths of the multiple laser beams emitted by it are in the wavelength range of red, green and blue visible light.

4. The vacuum coating online monitoring system according to claim 3, characterized in that: The wavelengths of the multiple laser beams are 465nm, 525nm, and 643nm respectively.

5. The vacuum coating online monitoring system according to claim 1, characterized in that: Along the optical path direction of the laser emitted by the laser light source module, the homogenized beam expansion optical path includes a homogenized glass sheet, a first fly-eye lens, a reflector, a second fly-eye lens, a cylindrical mirror and an aperture arranged in sequence; the light hole of the aperture is aligned with the light outlet.

6. The vacuum coating online monitoring system according to claim 1, characterized in that: The light blocking module is a shell made of conductive material and is electrically connected to a DC bias power supply.

7. The vacuum coating online monitoring system according to claim 1, characterized in that: The photosensitive module includes a filter module and a light sensor; The light filtering module is arranged at the light entrance, and is used to receive the reflected light and send it to the light sensor after filtering; The light sensor is used to receive the filtered emitted light, obtain the light-sensitive data of the coated surface of the coated product, and send the data to the data processing module.

8. The vacuum coating online monitoring system according to claim 7, characterized in that: The light sensor includes one or more of a monochrome or color CMOS, a CCD camera, and an infrared thermal imager.

9. The vacuum coating online monitoring system according to claim 7, characterized in that: The data processing module is specifically used for: The light sensor collects light data to monitor the intensity of reflected light over time, and deduce the growth rate, thickness, and surface condition of the film during the coating process. By integrating the intensity information of the reflected light of lasers of different wavelengths, the film thickness of each film layer and the light absorption rate of the film at each wavelength in the absence of interference are obtained. The absorption spectrum curve of the film layer is fitted with reference to the chemical composition of each film layer and the light absorption spectrum of the standard sample to obtain the color value of each film layer.

10. The vacuum coating online monitoring system according to claim 9, characterized in that: The data processing module is further configured to: Acquire real-time working data collected by a data acquisition module of the vacuum coating equipment, and obtain real-time process data based on the real-time working data and the real-time coating parameters of each film layer; The real-time process data is compared and analyzed with the standard process data of the pre-imported standard process, and the coating process parameters are adjusted in real time according to the analysis results.

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