An in-situ monitoring and control system and method for thin film growth by chemical bath deposition

Abstract

This invention provides an in-situ monitoring and control system and method for thin film growth via chemical bath deposition. The system includes: a thin film deposition apparatus for depositing a compound thin film on a substrate via chemical bath deposition and controlling the reaction process of the chemical bath deposition; a signal acquisition device for acquiring color signals from the substrate surface during the chemical bath deposition process; and a signal processing device connected to the signal acquisition device, configured to receive the color signals transmitted by the signal acquisition device, perform numerical processing on the color signals to obtain numerical data related to the film thickness, and determine the film thickness and uniformity based on the numerical data. The solution of this invention can correlate the color and thickness of the thin film, and can analyze the film uniformity while analyzing the film thickness.

Description

Technical Field

[0001] This invention relates generally to the field of thin-film solar cell technology, and in particular to an in-situ monitoring and control system and method for thin-film growth by chemical water bath deposition. Background Technology

[0002] Chemical bath deposition (CBD) is a low-cost technique for preparing high-quality thin films. Compared to physical vapor deposition methods such as magnetron sputtering and thermal evaporation, CBD offers advantages such as low damage, good film crystallinity, and highly conformal growth, making it widely used in various semiconductor-related fields. In the photovoltaic field, many solar cells, such as copper indium gallium selenide (CIGS), cadmium telluride (CdTe), perovskite, and copper zinc tin sulfide selenide (CZTSSe) solar cells, incorporate CBD technology into their basic fabrication process. However, the CBD process still faces significant challenges in terms of reproducibility and industrial scale-up.

[0003] First, the chemical bath deposition process involves multiple reaction variables, such as reactant concentration, reaction temperature, buffer type, and film surface roughness and dust, making the actual reaction process difficult to control and leading to unstable film deposition rates. Second, the CBD method struggles to quantitatively measure the uniformity of large-area films during industrial scale-up. To address these issues, developing in-situ monitoring technology for film growth in CBD-prepared films will be an effective solution.

[0004] Currently, widely used in-situ monitoring systems typically employ spectrometers as detection devices, retrieving film thickness information by real-time monitoring of the film's reflectance spectrum, thereby monitoring the film growth process. However, this method has several limitations. First, the in-situ testing involving spectrometers results in high equipment costs. Second, the spectral curves are difficult to correlate with the film's state (especially its color) observed by the naked eye. Finally, this method struggles to characterize the in-plane uniformity of the film. Therefore, there is an urgent need to develop a lower-cost, more intuitive, and uniform in-situ monitoring scheme for film growth. Summary of the Invention

[0005] In view of the above problems, the present invention proposes an in-situ monitoring and control system and method for thin film growth by chemical water bath deposition that overcomes or at least partially solves the above problems.

[0006] One object of the present invention is to provide an in-situ monitoring and control system and method for thin film growth using chemical bath deposition that can correlate the color and thickness of the thin film and analyze the thickness and uniformity of the thin film.

[0007] A further objective of this invention is to use hue values, which are directly related to color, to quantitatively represent the state of the thin film, making the data more intuitive.

[0008] According to one aspect of the present invention, an in-situ monitoring and control system for thin film growth by chemical water bath deposition is provided, comprising:

[0009] A thin film deposition apparatus for depositing compound thin films on a substrate by chemical bath deposition and controlling the reaction process of the chemical bath deposition;

[0010] A signal acquisition device is used to acquire the color signal of the substrate surface during chemical bath deposition; and

[0011] A signal processing device, connected to the signal acquisition device, is configured to receive a color signal transmitted by the signal acquisition device, perform numerical processing on the color signal to obtain numerical data related to the thickness of the film, and determine the thickness and uniformity of the film based on the numerical data.

[0012] Optionally, the color signal is an RGB color signal;

[0013] The signal processing device is further configured to:

[0014] The RGB color signal is transformed from the RGB color space to the HSV color space to obtain the hue value of the substrate surface, and the thickness and uniformity of the film are determined based on the hue value.

[0015] The thickness of the film is determined by finding a pre-defined standard correspondence between the film thickness and the hue value corresponding to the compound film based on the hue value.

[0016] The standard deviation of the hue values ​​is calculated as a characterization of the uniformity of the film.

[0017] Optionally, the RGB color signal is an RGB value matrix of each pixel;

[0018] The signal processing device is further configured to:

[0019] The RGB value matrix of each pixel is normalized using formula (1) to obtain normalized data (r, g, b);

[0020] Using formula (2), the maximum value max and the minimum value min are obtained for the normalized data (r, g, b) of each pixel;

[0021] Using formula (3), coordinate transformation is performed based on the normalized data (r, g, b), maximum value max and minimum value min of each pixel to obtain the HSV matrix of each pixel;

[0022] Extract the hue values ​​from the HSV matrix of all pixels, and use the mean of the hue values ​​of all pixels as the hue value of the substrate surface. The mean is one of the arithmetic mean, weighted mean, and median.

[0023] The formulas (1), (2), and (3) are as follows:

[0024]

[0025]

[0026] Optionally, the standard correspondence between the film thickness and the hue value is obtained by pre-measuring the reflection spectrum of films of different thicknesses, converting the reflection spectrum into RGB color signals, and performing coordinate transformation on the RGB color signals to convert them from the RGB color space to the HSV color space, thereby obtaining the hue value of the film surface.

[0027] Optionally, the signal acquisition device is a camera, which is positioned opposite the surface of the thin film to be deposited on the substrate, and is configured to acquire a surface image of the thin film deposited on the substrate surface, and convert the surface image into an RGB color signal.

[0028] Optionally, the in-situ monitoring and control system for thin film growth via chemical water bath deposition also includes:

[0029] At least one illumination source is provided for illuminating the surface of the thin film to be deposited on the substrate.

[0030] Optionally, the thin film deposition apparatus includes a reaction vessel for holding chemical reagents for thin film deposition. During chemical bath deposition, the substrate is immersed in the chemical reagents. At least a portion of the reaction vessel is transparent, allowing light emitted by the illumination light source to pass through the reaction vessel and illuminate the substrate, and enabling the signal acquisition device to acquire color signals from the substrate surface.

[0031] Optionally, the thin film deposition apparatus further includes a water bath heating unit, which includes a heating container and a heating medium contained in the heating container, wherein the reaction vessel, the irradiation light source and the signal acquisition device are placed in the heating medium.

[0032] Optionally, the thin film deposition apparatus further includes a gripping device for gripping the substrate and immersing the substrate in or removing it from the chemical reagent.

[0033] According to another aspect of the present invention, an in-situ monitoring and control method for thin film growth by chemical bath deposition is also provided, comprising:

[0034] During the deposition of a compound thin film on a substrate via chemical bath deposition, the color signal of the substrate surface is acquired; and

[0035] The color signal is numerically processed to obtain numerical data related to the thickness of the film, and the thickness and uniformity of the film are determined based on the numerical data.

[0036] The present invention provides an in-situ monitoring and control system and method for thin film growth via chemical bath deposition. During the chemical bath deposition process, color signals from the substrate surface are acquired. These color signals are then numerically processed to obtain numerical data related to the film thickness. Based on this numerical data, the film thickness and uniformity are determined. Thus, the present invention can correlate the film's color with its thickness and analyze both the film thickness and uniformity simultaneously.

[0037] Furthermore, the in-situ monitoring and control system and method for thin film growth by chemical water bath deposition provided by the present invention uses a camera to acquire color signals on the substrate surface, eliminating the need for an expensive spectrometer and greatly reducing system costs.

[0038] Furthermore, in the in-situ monitoring and control system and method for thin film growth by chemical bath deposition provided by this invention, the acquired RGB color signal is transformed from the RGB color space to the HSV color space by performing coordinate transformation to obtain the hue value of the substrate surface, and then the thickness and uniformity of the thin film are determined based on the hue value. Since the hue value, which is directly related to color, is used to quantitatively represent the state of the thin film, the data is more intuitive, and quantitative data on the deposition uniformity of the thin film prepared by the CBD method on a two-dimensional plane can be quickly provided.

[0039] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below.

[0040] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0041] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0042] Figure 1 This is a schematic diagram of the structure of an in-situ monitoring and control system for thin film growth by chemical water bath deposition according to an embodiment of the present invention;

[0043] Figure 2 A graph showing the standard correspondence between film thickness and film hue value according to an embodiment of the present invention;

[0044] Figure 3 This is a spatial distribution diagram of the film thickness according to an embodiment of the present invention;

[0045] Figure 4 This is a flowchart illustrating an in-situ monitoring and control method for thin film growth by chemical water bath deposition according to an embodiment of the present invention. Detailed Implementation

[0046] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0047] Based on the aforementioned problems, and addressing the challenges of in-situ monitoring and control in thin film preparation using the CBD method, this invention provides an in-situ monitoring and control system for thin film growth via chemical bath deposition.

[0048] Figure 1 This is a schematic diagram of the structure of an in-situ monitoring and control system 100 for thin film growth via chemical water bath deposition according to an embodiment of the present invention. See also... Figure 1 As shown, in one embodiment, the in-situ monitoring and control system 100 for thin film growth by chemical water bath deposition of the present invention generally includes a thin film deposition apparatus 110, a signal acquisition apparatus 120, and a signal processing apparatus 130.

[0049] Thin film deposition apparatus 110 is used to deposit compound thin films on substrate 150 via chemical bath deposition and to control the reaction process of chemical bath deposition. Signal acquisition device 120 is used to acquire color signals on the surface of substrate 150 during chemical bath deposition.

[0050] The signal processing device 130 is connected to the signal acquisition device 120. Specifically, the signal processing device 130 and the signal acquisition device 120 can be connected via a wired or wireless means, for example, via a signal transmission line 160, so that the signal acquisition device 120 transmits the acquired color signal to the signal processing device 130 through the signal transmission line 160. Furthermore, the signal processing device 130 is configured to receive the color signal transmitted by the signal acquisition device 120, perform numerical processing on the color signal to obtain numerical data related to the thickness of the thin film, and determine the thickness and uniformity of the thin film based on the numerical data.

[0051] The in-situ monitoring and control system 100 for thin film growth via chemical bath deposition provided in this embodiment of the invention acquires color signals from the surface of the substrate 150 during the chemical bath deposition process using a signal acquisition device 120. A signal processing device 130 then performs numerical processing on the color signals to obtain numerical data related to the film thickness. Based on this numerical data, the thickness and uniformity of the film are determined. Thus, the solution of this invention can correlate the color and thickness of the film, and can analyze the film's uniformity while analyzing its thickness.

[0052] In some embodiments, the signal acquisition device 120 can be a camera, positioned opposite the surface of the thin film to be deposited on the substrate 150, configured to acquire a surface image of the thin film deposited on the substrate 150, and convert the surface image into an RGB color signal. This embodiment utilizes a low-cost camera instead of an expensive spectrometer, significantly reducing the cost of the system 100.

[0053] Furthermore, the camera can also function as a video signal exporter. In some embodiments, the surface image of the thin film deposited on the substrate 150 acquired by the camera is a video signal, and the video signal is exported and transmitted to the signal processing device 130.

[0054] In some embodiments, the signal processing device 130 may be a computer device capable of displaying and processing video signals.

[0055] In some embodiments, the color signal acquired by the signal processing device 130 is an RGB color signal. Accordingly, the signal processing device 130 is also configured to perform coordinate transformation on the RGB color signal, converting it from the RGB color space to the HSV color space, to obtain the hue value (H value) of the substrate 150 surface, and to determine the thickness and uniformity of the film based on the hue value.

[0056] Specifically, the signal processing device 130 is configured to determine the thickness of the film by looking up a preset standard correspondence between the film thickness and the hue value corresponding to the compound film. Furthermore, the signal processing device 130 is also configured to calculate the standard deviation of the hue value on the surface of the substrate 150 (i.e., the hue value on the front side of the film) as a characterization of the film's uniformity.

[0057] This embodiment uses hue values, which are directly related to color, to quantitatively represent the state of the thin film, making the data more intuitive and providing quantitative data on the deposition uniformity of the thin film prepared by the CBD method on a two-dimensional plane.

[0058] In some further embodiments, the aforementioned RGB color signal is an RGB value matrix of each pixel.

[0059] Accordingly, the signal processing device 130 is also configured to perform the following data processing operations.

[0060] First, the RGB value matrix of each pixel is normalized using formula (1) to obtain normalized data (r, g, b).

[0061]

[0062] Then, the normalized data (r, g, b) of each pixel is taken to have a maximum value of max and a minimum value of min using formula (2).

[0063]

[0064] Next, using formula (3), coordinate transformation is performed based on the normalized data (r, g, b), maximum value max and minimum value min of each pixel to obtain the HSV matrix of each pixel.

[0065]

[0066] Finally, the hue values ​​of all pixels are extracted from the HSV matrix, and the average of the hue values ​​of all pixels is used as the hue value of the substrate 150 surface. Specifically, the average can be one of the following: arithmetic mean, weighted average, median, etc.

[0067] In some embodiments, the aforementioned pre-defined standard correspondence between film thickness and hue value corresponding to the compound film can be pre-calibrated.

[0068] Specifically, the reflectance spectra of the compound films of different thicknesses are measured in advance, the reflectance spectra are converted into RGB color signals, and the coordinate transformation of the RGB color signals is performed to convert them from the RGB color space to the HSV color space to obtain the hue value of the film surface. Thus, a standard correspondence between the thickness of the compound film and the hue value is established.

[0069] Figure 2 A graph illustrating the standard correspondence between film thickness and film hue value according to an embodiment of the present invention is shown, wherein the film is a CdS film. In practical operation, this curve is used to derive the real-time film thickness during the deposition process through linear fitting.

[0070] In some embodiments, the signal processing device 130 can also be used to display the two-dimensional distribution of the thin film grown on the surface of the substrate 150 in real time, for example... Figure 3 As shown. Figure 3 An exemplary spatial distribution diagram of the film thickness according to an embodiment of the present invention is shown, wherein the horizontal and vertical axes represent the length and width dimensions of the substrate 150 (in pixels), and different gray levels represent the film thickness (in nm). Real-time and visual display of the film thickness greatly facilitates the monitoring of film growth.

[0071] See also Figure 1 In some embodiments, the in-situ monitoring and control system 100 for chemical water bath deposition of thin film growth may further include at least one illumination light source 140 for illuminating the surface of the thin film to be deposited on the substrate 150 so that the image acquisition device can acquire images of the surface of the substrate 150.

[0072] Optionally, the illumination source 140 is an LED light source with strong light intensity. The emission spectrum of the illumination source 140 includes, but is not limited to, cool white light, natural white light, warm white light, and ultra-warm white light. The illuminance of the illumination source 140 is typically 50-150 lumens.

[0073] In one specific embodiment, there are two illumination light sources 140. The two illumination light sources 140 can be located on both sides of the longitudinal center line or the transverse center line of the substrate 150 during the deposition process and are symmetrically arranged relative to the longitudinal center line or the transverse center line. The illumination direction of each light source is tilted toward the side where the other is located, so that the illumination areas of the two illumination light sources 140 completely overlap on the substrate 150, thereby achieving a better illumination effect.

[0074] In some embodiments, the thin film deposition apparatus 110 may include a reaction vessel 111. The reaction vessel 111 is used to hold a chemical reagent 112 for thin film deposition. During chemical bath deposition, the substrate 150 is immersed in the chemical reagent 112.

[0075] Optionally, at least a portion of the reaction vessel 111 is made transparent, such that light emitted from the illumination light source 140 can pass through the reaction vessel 111 to illuminate the substrate 150 and the signal acquisition device 120 can acquire the color signal on the surface of the substrate 150. For example, portions of the reaction vessel 111d located in the optical path between the substrate 150 immersed in the chemical reagent 112 and the illumination light source 140, and in the optical path between the substrate 150 and the signal acquisition device 120, are made transparent.

[0076] Optionally, the transparent portion of the reaction vessel 111 has high light transmittance, and the constituent materials include, but are not limited to, quartz, soda-lime glass, acrylic, etc.

[0077] In one specific embodiment, the reaction vessel 111 is completely transparent to facilitate illumination and image acquisition by the signal acquisition device 120.

[0078] In some embodiments, a stirrer (e.g., a magnetic stirrer) may also be provided in the reaction vessel 111 to fully stir the chemical reagent 112 in the reaction vessel 111 to enhance the uniformity of thin film deposition.

[0079] In one embodiment, the chemical reagent 112 contained in the reaction vessel 111 is used to deposit a CdS thin film. In this case, the chemical reagent 112 is an aqueous solution containing compounds such as cadmium salts, ammonia, buffers, and sulfur sources. Cadmium salts include, but are not limited to, cadmium sulfate (CdSO4), cadmium chloride (CdCl2), and cadmium nitrate (Cd(NO3)2). Buffers include, but are not limited to, ammonium chloride (NH4Cl), ammonium sulfate ((NH4)2SO4), ammonium nitrate (NH4NO3), and sodium citrate (C6H5Na3O7). Sulfur sources include, but are not limited to, thiourea and thioacetamide.

[0080] In one embodiment, the chemical reagent 112 contained in the reaction vessel 111 is used to deposit a Zn(O,S) thin film. In this case, the chemical reagent 112 is an aqueous solution containing compounds such as zinc salts, ammonia, buffers, and sulfur sources. Zinc salts include, but are not limited to, zinc sulfate (ZnSO4), zinc chloride (ZnCl2), and zinc nitrate (Zn(NO3)2). Buffers include, but are not limited to, ammonium chloride (NH4Cl), ammonium sulfate ((NH4)2SO4), ammonium nitrate (NH4NO3), and sodium citrate (C6H5Na3O7). Sulfur sources include, but are not limited to, thiourea and thioacetamide.

[0081] In one embodiment, the chemical reagent 112 contained in the reaction vessel 111 is used to deposit a SnO2 thin film. In this case, the chemical reagent 112 is an aqueous solution containing compounds such as tin salts, hydrochloric acid, buffers, and oxygen sources. Tin salts include, but are not limited to, stannous sulfate (SnSO4), stannous chloride (SnCl2), and stannous nitrate (Sn(NO3)2). Buffers include, but are not limited to, thioglycolic acid (TGA), oxalic acid (OA), and nitric acid triacetic acid. Oxygen sources include, but are not limited to, urea and hydrogen peroxide.

[0082] In one embodiment, the substrate 150 may be made of materials including, but not limited to, glass, metal foil, and polymer. A CZTSSe thin film may be pre-deposited on the front side of the substrate 150. A CdS thin film may be deposited on the surface of the CZTSSe thin film using chemical bath deposition. The CZTSSe and CdS thin films can form a PN junction, creating a built-in electric field that separates and transports photogenerated carriers under illumination.

[0083] In one embodiment, the substrate 150 is made of materials including, but not limited to, glass, metal foil, and polymer. A CZTSSe thin film may be pre-deposited on the front side of the substrate 150. A Zn(O,S) thin film can be deposited on the surface of the CZTSSe thin film using chemical bath deposition. The CZTSSe thin film and the Zn(O,S) thin film can form a PN junction, creating a built-in electric field that separates and transports photogenerated carriers under illumination.

[0084] In one embodiment, the substrate 150 may be made of materials including, but not limited to, glass, metal foil, and polymer. Fluorine-doped tin oxide (FTO) may be pre-deposited on the front side of the substrate 150. A SnO2 film can be deposited on the surface of the FTO film using chemical bath deposition.

[0085] See also Figure 1 In some embodiments, the thin film deposition apparatus 110 may further include a water bath heating unit 113. The water bath heating unit 113 includes a heating container 1131 and a heating medium 1132 contained in the heating container 1131. The reaction container 111 is placed in the heating medium 1132, and the water bath heating unit 113 heats the reaction container 111 and the chemical reagents 112 inside it, thereby providing a stable reaction temperature for the reaction container 111.

[0086] The heating temperature of the water bath heating unit 113 can be set according to actual application requirements. For example, its heating temperature range can be set between 30 and 100°C.

[0087] In one embodiment, the water bath heating unit 113 may also have a magnetic stirring function, which, together with the stirring magnet introduced into the reaction vessel 111, can fully stir the chemical reagent 112 in the reaction vessel 111.

[0088] Optionally, the heating medium 1132 is ultrapure water free of impurities, which can better fix the reaction temperature.

[0089] Of course, the water bath heating unit 113 also includes a heating element, which can be a heating component commonly used in the art, as is known to those skilled in the art, and will not be described in detail here.

[0090] In some embodiments, at least one illumination source 140 may be placed in the heating medium 1132 of the water bath heating unit 113 to provide illumination for in-situ observation. Furthermore, the illumination source 140 may be waterproof and high-temperature resistant, for example, the waterproof rating should reach IP68 and the temperature resistance should be higher than 30°C.

[0091] In some embodiments, the signal acquisition device 120 is placed in the heating medium 1132, facing the substrate 150, to collect color changes on the surface of the substrate 150. Furthermore, the signal acquisition device 120 (such as a camera) and the signal transmission line 160 may be waterproof and heat-resistant; for example, the waterproof rating should reach IP68, and the temperature resistance should be higher than 30°C.

[0092] In some embodiments, the signal acquisition device 120 (such as a camera) should have the function of exporting data to a computer in real time to facilitate subsequent data processing.

[0093] See also Figure 1 The thin film deposition apparatus 110 may further include a gripping device 114 for gripping the substrate 150 and immersing or removing the substrate 150 from the chemical reagent 112. Specifically, the gripping device 114 may be a robotic arm. In practical applications, the gripping device 114 can transport the substrate 150 above the reaction vessel 111, immerse the substrate 150 in the chemical reagent 112 for deposition, and remove the substrate 150 from the chemical reagent 112 when the target film thickness is reached. The material of the part of the gripping device 114 (such as a robotic arm) that contacts the substrate 150 and is immersed in the chemical reagent 112 can be made of acid and alkali resistant materials such as polytetrafluoroethylene (PTFE) to avoid introducing impurities during the thin film deposition process and to allow for long-term use.

[0094] By using the gripping device 114, in conjunction with the in-situ monitoring of the signal acquisition device 120 and the signal processing device 130, precise control of the film growth thickness can be achieved.

[0095] Based on the same technical concept, the present invention also provides a method for in-situ monitoring and control of thin film growth by chemical bath deposition. This method for in-situ monitoring and control of thin film growth by chemical bath deposition can be executed by the aforementioned in-situ monitoring and control system 100 for thin film growth by chemical bath deposition.

[0096] Figure 4 This is a schematic flowchart illustrating an in-situ monitoring and control method for thin film growth via chemical water bath deposition according to an embodiment of the present invention. See also... Figure 4 As shown, the in-situ monitoring and control method for thin film growth by chemical water bath deposition includes at least the following steps S402 to S404.

[0097] Step S402: During the deposition of a compound film on substrate 150 by chemical water bath deposition, the color signal on the surface of substrate 150 is acquired.

[0098] Specifically, the color signal on the surface of the substrate 150 can be acquired through the signal acquisition device 120.

[0099] Step S404: The color signal is numerically processed to obtain numerical data related to the thickness of the film, and the thickness and uniformity of the film are determined based on the numerical data.

[0100] Specifically, step S404 can be executed by the signal processing device 130.

[0101] In some embodiments, the color signal is an RGB color signal.

[0102] Accordingly, step S404 may specifically include: performing coordinate transformation on the RGB color signal to convert it from the RGB color space to the HSV color space to obtain the hue value of the substrate 150 surface, and determining the thickness and uniformity of the film based on the hue value.

[0103] In some embodiments, the step of determining the thickness of the film based on the hue value may include: determining the thickness of the film by looking up a preset standard correspondence between the film thickness and the hue value corresponding to the compound film.

[0104] In some embodiments, the step of determining the uniformity of the film based on the hue value may include: calculating the standard deviation of the hue value as a characterization of the uniformity of the film.

[0105] In some further embodiments, the RGB color signal is an RGB value matrix for each pixel.

[0106] Accordingly, the step of performing coordinate transformation on the RGB color signal to convert it from the RGB color space to the HSV color space to obtain the hue value of the substrate 150 surface may include: normalizing the RGB value matrix of each pixel using the aforementioned formula (1) to obtain normalized data (r,g,b); taking the maximum value max and the minimum value min of the normalized data (r,g,b) of each pixel using the aforementioned formula (2); performing coordinate transformation based on the normalized data (r,g,b), maximum value max and minimum value min of each pixel using the aforementioned formula (3) to obtain the HSV matrix of each pixel; extracting the hue value from the HSV matrix of all pixels, and using the average of the hue values ​​of all pixels as the hue value of the substrate 150 surface.

[0107] Optionally, the mean can be one of the arithmetic mean, weighted mean, or median.

[0108] In some embodiments, the standard correspondence between film thickness and hue value is obtained by pre-measuring the reflection spectrum of films of different thicknesses, converting the reflection spectrum into RGB color signals, and performing coordinate transformation on the RGB color signals to convert them from the RGB color space to the HSV color space, thereby obtaining the hue value of the film surface.

[0109] In some embodiments, steps S402 and S404 are performed in real time. Before step S402, the substrate 150 can be immersed in the chemical reagent 112 of the reaction vessel 111 using the gripping device 114, and thin film deposition can be initiated. When the obtained thin film thickness reaches the target value as monitored in real time through steps S402 and S404, the substrate 150 is removed from the chemical reagent 112 by the gripping device 114 to end the reaction, thereby achieving reaction control of thin film deposition.

[0110] The in-situ monitoring and control method for thin film growth by chemical water bath deposition in this invention creatively introduces an in-situ monitoring device for thin film growth, enabling precise control of the CBD process. The device is simple and inexpensive.

[0111] The technical features in the above embodiments can be combined arbitrarily. For the sake of simplicity, not all possible combinations in the above embodiments are described in detail. However, any combination of these technical features that does not contradict each other should be considered within the scope of this specification.

[0112] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0113] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. An in-situ monitoring and control system for thin film growth via chemical water bath deposition, characterized in that, include: A thin film deposition apparatus for depositing compound thin films on a substrate by chemical bath deposition and controlling the reaction process of the chemical bath deposition; A signal acquisition device is used to acquire the color signal on the surface of the substrate during the chemical water bath deposition process; as well as A signal processing device, connected to the signal acquisition device, is configured to receive a color signal transmitted by the signal acquisition device, perform numerical processing on the color signal to obtain numerical data related to the thickness of the film, and determine the thickness and uniformity of the film based on the numerical data.

2. The in-situ monitoring and control system for thin film growth by chemical water bath deposition according to claim 1, characterized in that, The color signal is an RGB color signal; The signal processing device is further configured to: The RGB color signal is transformed from the RGB color space to the HSV color space to obtain the hue value of the substrate surface, and the thickness and uniformity of the film are determined based on the hue value. The thickness of the film is determined by finding a pre-defined standard correspondence between the film thickness and the hue value corresponding to the compound film based on the hue value. The standard deviation of the hue values ​​is calculated as a characterization of the uniformity of the film.

3. The in-situ monitoring and control system for thin film growth by chemical water bath deposition according to claim 2, characterized in that, The RGB color signal is an RGB value matrix of each pixel; The signal processing device is further configured to: The RGB value matrix of each pixel is normalized using formula (1) to obtain normalized data (r, g, b); Using formula (2), the maximum value max and the minimum value min are obtained for the normalized data (r, g, b) of each pixel; Using formula (3), coordinate transformation is performed based on the normalized data (r, g, b), maximum value max and minimum value min of each pixel to obtain the HSV matrix of each pixel; Extract the hue values ​​from the HSV matrix of all pixels, and use the mean of the hue values ​​of all pixels as the hue value of the substrate surface. The mean is one of the arithmetic mean, weighted mean, and median. The formulas (1), (2), and (3) are as follows:

4. The in-situ monitoring and control system for thin film growth by chemical water bath deposition according to claim 2, characterized in that, The standard correspondence between the film thickness and the hue value is obtained by pre-measuring the reflection spectrum of films of different thicknesses, converting the reflection spectrum into RGB color signals, and performing coordinate transformation on the RGB color signals to convert them from the RGB color space to the HSV color space, thereby obtaining the hue value of the film surface.

5. The in-situ monitoring and control system for thin film growth by chemical water bath deposition according to any one of claims 1-4, characterized in that, The signal acquisition device is a camera, which is positioned opposite the surface of the thin film to be deposited on the substrate. It is configured to acquire a surface image of the thin film deposited on the substrate and convert the surface image into an RGB color signal.

6. The in-situ monitoring and control system for thin film growth by chemical water bath deposition according to claim 1, characterized in that, Also includes: At least one illumination source is provided for illuminating the surface of the thin film to be deposited on the substrate.

7. The in-situ monitoring and control system for thin film growth by chemical water bath deposition according to claim 6, characterized in that, The thin film deposition apparatus includes a reaction vessel for holding chemical reagents for thin film deposition. During chemical bath deposition, the substrate is immersed in the chemical reagents. At least a portion of the reaction vessel is transparent, allowing light emitted by the illumination light source to pass through the reaction vessel and illuminate the substrate, and enabling the signal acquisition device to acquire color signals from the substrate surface.

8. The in-situ monitoring and control system for thin film growth by chemical water bath deposition according to claim 7, characterized in that, The thin film deposition apparatus further includes a water bath heating unit, which includes a heating container and a heating medium contained in the heating container, wherein the reaction container, the irradiation light source and the signal acquisition device are placed in the heating medium.

9. The in-situ monitoring and control system for thin film growth by chemical water bath deposition according to claim 7 or 8, characterized in that, The thin film deposition apparatus further includes a gripping device for gripping the substrate and immersing the substrate in or removing it from the chemical reagent.

10. A method for in-situ monitoring and control of thin film growth by chemical water bath deposition, characterized in that, include: During the deposition of a compound thin film on a substrate via chemical bath deposition, the color signal of the substrate surface is acquired; as well as The color signal is numerically processed to obtain numerical data related to the thickness of the film, and the thickness and uniformity of the film are determined based on the numerical data.

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