CN115597501B - High-precision wide-spectrum optical film thickness online monitoring system - Google Patents
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
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Abstract
The application provides a high-precision wide-spectrum optical film thickness online monitoring system, which comprises: a light source; a collimation light path, which irradiates the light of the light source to the light control sheet after collimation treatment; the narrow linewidth spectrum analysis device is used for extracting Shan Sepu optical signals from the first optical signals reflected by the light control sheet and converting the Shan Sepu optical signals into electric signals; the amplifying and filtering device is used for amplifying and filtering the electric signals so as to obtain characteristic electric signals with specific frequencies; and the upper computer is used for comparing the conversion result with a preset film thickness model by the digital-to-analog conversion characteristic electric signal to generate a stop instruction so as to control whether to terminate the film deposition operation. The on-line monitoring system can realize the direct monitoring of the optical film; by separating Shan Sepu optical signals, the problem of infrared spectrum wavelength positioning is solved; and performing photoelectric conversion on the monochromatic spectrum optical signals extracted on line, filtering and amplifying, and comparing the monochromatic spectrum optical signals with a model to realize on-line precise control of film deposition.
Description
Technical Field
The specification relates to the technical field of optical films, in particular to a high-precision wide-spectrum optical film thickness online monitoring system.
Background
The optical film has increasingly wide application, the film device plays a vital role in various application fields, and the optical film has excellent optical stability and relatively low cost, is always the first choice method for improving the spectral characteristics of an optical system, and is also an essential component of a modern optical system.
In the film deposition production process of the optical film, the requirements on the spectral characteristics, the mechanical characteristics, the environmental resistance and the like of the optical film are more and more severe, so that more challenges are provided for a monitoring instrument for manufacturing the optical film, and the high-precision wide-spectrum optical film thickness monitoring system is a core component of high-precision optical film forming equipment and is an important instrument for monitoring the film thickness. At present, domestic high-precision optical film forming equipment is imported from abroad, and the wavelength range of a monitoring system equipped by imported equipment is limited to 400-2400 nm due to technical limitations of foreign manufacturers, so that an online monitoring system for the thickness of an optical film with high precision, which is applicable to a wide wavelength range, is needed.
Disclosure of Invention
In view of this, the embodiments of the present disclosure provide a high-precision broad spectrum optical film thickness online monitoring system capable of accurately monitoring the thickness of a film deposition in real time during the film deposition production process.
The embodiment of the specification provides the following technical scheme:
an on-line monitoring system for high-precision broad spectrum optical film thickness, comprising:
a light source;
the collimation light path is connected with the light source to collimate the light of the light source and irradiate the light control sheet, wherein the light control sheet is positioned in a film deposition operation area of the optical film;
the narrow-line-width spectrum analysis device is used for extracting Shan Sepu optical signals from the first optical signals reflected by the light control sheet and converting the monochromatic spectrum optical signals into first electric signals;
the amplifying and filtering device is used for amplifying the first electric signal into a second electric signal, extracting a third electric signal with specific frequency from the second electric signal, and carrying out analog-to-digital conversion on the third electric signal to obtain an analog-to-digital conversion result;
and the upper computer is used for comparing the analog-to-digital conversion result with a preset film thickness model to generate a stop instruction, wherein the stop instruction is used for stopping film deposition operation.
According to the high-precision wide-spectrum optical film thickness online monitoring system, shan Sepu optical signals are separated through the narrow-linewidth spectrum analysis device, the spectrum wavelength positioning problem is solved, single-color spectrum optical signals are converted into electric signals, then the electric signals are amplified and filtered, noise is removed, effective signals representing the film thickness are extracted, the effective signals extracted online are continuously compared with a film thickness model, whether the film thickness meets the requirements is judged, and whether film deposition is completed or not is determined, so that online precision control of film deposition operation is achieved.
The application also provides a scheme, wherein the collimation light path comprises a collimation light path formed by an optical fiber coupling aspheric lens.
The application also provides a scheme, and the narrow linewidth spectrum analysis device comprises a monochromator.
The application also provides a scheme, the amplifying and filtering device comprises a transimpedance amplifier and a phase-locked amplifier, and the monochromator, the transimpedance amplifier and the phase-locked amplifier are electrically connected in sequence.
The application also provides a scheme, and the monochromator further comprises a blazed grating.
The application also provides a scheme, wherein the parameter range of the blazed grating comprises any one or combination of the following components:
the wavelength range is 350nm-1000nm, the grating line is 1200g/mm, and the blaze wavelength is 500nm;
the wavelength range is 850nm-2600nm, the grating line is 300g/mm, and the blaze wavelength is 1250nm;
the wavelength range is 2500nm-8000nm, the grating line is 150g/mm, and the blaze wavelength is 4000nm.
The application also provides a scheme, and the detector of the monochromator comprises any one or combination of the following components:
a silicon photodetector with a wavelength ranging from 190nm to 1100nm;
an InGaAs photodetector with a wavelength ranging from 1000nm to 2500nm;
the wavelength range of the indium-arsenic-antimony photoelectric detector is 2500nm-5000nm.
The application also provides a scheme, and the light source further comprises a chopper.
The application further provides a scheme, the film thickness model further comprises a preset first reflected light fitting curve, and the upper computer is further used for generating a second reflected light fitting curve according to the analog-to-digital conversion result and comparing the similarity of the first reflected light fitting curve and the second reflected light fitting curve to generate the stop instruction.
The application further provides a scheme, the first reflected light fitting curve comprises a plurality of first wave crests, the second reflected light fitting curve comprises a plurality of second wave crests, and the upper computer is further used for comparing positions and/or numbers of the first wave crests and the second wave crests to generate the stop instruction.
Compared with the prior art, the beneficial effects that above-mentioned at least one technical scheme that this description embodiment adopted can reach include at least: the light signals emitted by the light source are irradiated on the light control sheet representing the film deposition thickness, and the light signals loaded with the film optical thickness information are reflected into the narrow linewidth spectrum analysis device, so that the direct monitoring of the optical film is realized; the narrow linewidth spectrum analysis device separates out Shan Sepu optical signals, so that the problem of infrared spectrum wavelength positioning is solved; after Shan Sepu optical signals are converted into electric signals, noise is removed through amplification and filtration of an amplification and filtration device, the acquisition precision of the signals is improved, and the optical thickness information of the film layer is restored; and comparing the thickness signal extracted on line with a film thickness model to determine the finishing time of film deposition, thereby realizing on-line precise control of film deposition.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of the structure of an on-line monitoring system for high-precision broad spectrum optical film thickness according to one embodiment;
FIG. 2 is an optical schematic diagram of a collimated optical path of one embodiment;
fig. 3 is a flow chart of a control method of an embodiment.
Detailed Description
Embodiments of the present application will be described in detail below with reference to the accompanying drawings.
Other advantages and effects of the present application will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present application with reference to specific examples. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, apparatus may be implemented and/or methods practiced using any number and aspects set forth herein. In addition, such apparatus may be implemented and/or such method practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present application by way of illustration, and only the components related to the present application are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.
It is to be understood that "connection of component a to component B" means that component a is directly in contact with component B or that component a is indirectly connected to component B via other components. The terms "upper", "lower", "inner", "outer", "side", and the like, as described in the exemplary embodiments of the present specification, are described at the angles shown in the drawings, and should not be construed as limiting the exemplary embodiments of the present specification.
In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.
With the rapid development of modern science and technology, the optical film has increasingly wide application, from aerospace to autopilot, from military development to new epidemic situation resistance, the film device plays a vital role, and the optical film has excellent optical stability and relatively low cost, so that the optical film is always the first choice method for improving the spectral characteristics of an optical system and is also an essential component part of a modern optical system. Meanwhile, the requirements on the spectral characteristics, the mechanical characteristics, the environmental resistance and the like of the optical film are also more and more stringent, further more challenges are presented to an instrument for manufacturing the optical film, the deposition thickness is required to be monitored at any time in the production process of film deposition, and the high-precision wide-spectrum optical film thickness monitoring system is a core component of high-precision optical film forming equipment and is also a neck clamping technology for restricting the advancing of domestic film coating equipment to the high-precision film coating equipment.
According to market research, only an optical film thickness control system with a visible wave band is in China at present, and no near infrared and middle infrared related system exists. The current domestic high-precision optical film forming equipment is imported from the United states, japan and Germany, and the wavelength range of a monitoring system equipped by the current imported equipment is limited to 400-2400 nm, and the imported equipment is limited to foreign countries in a farther wavelength range.
The application provides a high-precision wide-spectrum optical film thickness online monitoring system which can accurately monitor the film deposition thickness online. The line monitoring system comprises a light source, a collimation light path, a narrow linewidth spectrum analysis device, an amplifying and filtering device and an upper computer, wherein the light source is used for outputting high-stability detection light; the collimation light path carries out collimation treatment on the light to obtain collimated light which is used for being irradiated on the light control sheet so as to improve the stability of the irradiated light as much as possible; the narrow linewidth spectrum analysis device acquires light rays reflected from the light control sheet, converts the light signals into electric signals after separating monochromatic spectrum light signals from the light rays, positions spectrum wavelengths, and at the moment, the monochromatic spectrum light signals are loaded with film layer thickness information, but the attenuation of the light signals is large, the intensity is weak, the light signals are noisy, and the light signals are input into the amplifying and filtering device after being converted into the electric signals; the amplifying and filtering device extracts the electric signal with specific frequency from the electric signal after amplifying the electric signal, further reduces the influence of noise and attenuation of the optical signal, and obtains an analog-digital conversion result for comparison after analog-digital conversion of the processed electric signal, and compares the result with a standard thickness model to judge whether the thickness of the thin film deposition meets the process requirements, if the thickness meets the process requirements, a stop instruction is generated to stop the operation, if the thickness does not meet the process requirements, the deposition operation is continued, and the thin film thickness monitoring is continuously carried out until the thickness meets the requirements.
The following describes the technical scheme provided by each embodiment of the present application with reference to the accompanying drawings.
The high-precision broad spectrum optical film thickness on-line monitoring system shown in fig. 1 comprises:
a light source;
the collimation light path is connected with the light source to collimate the light of the light source and irradiate the light control sheet, wherein the light control sheet is positioned in a film deposition operation area of the optical film;
the narrow-line-width spectrum analysis device is used for extracting Shan Sepu optical signals from the first optical signals reflected by the light control sheet and converting the monochromatic spectrum optical signals into first electric signals;
the amplifying and filtering device is used for amplifying the first electric signal into a second electric signal, extracting a third electric signal with specific frequency from the second electric signal, and carrying out analog-to-digital conversion on the third electric signal to obtain an analog-to-digital conversion result;
and the upper computer is used for comparing the analog-to-digital conversion result with a preset film thickness model to generate a stop instruction, wherein the stop instruction is used for stopping film deposition operation.
Specifically, as shown in fig. 1, the light projector is electrically connected to a light projector power supply and is connected to a first optical fiber, and when the light projector is powered on, the light projector emits a continuous stable optical signal and is coupled into the optical fiber of the first optical fiber. And one end of the first optical fiber, which is close to the light control sheet, is provided with a collimation light path, and the light signal is subjected to collimation treatment through the collimation light path to obtain a collimated light signal. The optical signal is reflected after being irradiated on the light control sheet, and is acquired by a second optical fiber connected with the narrow-linewidth spectrum analysis device, wherein the narrow-linewidth spectrum analysis device can adopt a monochromator as shown in the figure, can also adopt other adjustable grating devices so as to extract Shan Sepu optical signals from the optical signals, and is also provided with a photoelectric conversion module for converting the separated monochromatic spectrum optical signals into first electric signals.
It should be noted that the light control sheet is located in the film deposition area of the optical film, and is used to represent the variation of the film deposition thickness in the film deposition operation.
The narrow linewidth spectrum analysis device is electrically connected with the amplifying and filtering device, and first amplifies the first electric signal, for example, a transimpedance amplifier in fig. 1 is used, the transimpedance amplifier is connected with the monochromator through a BNC connecting wire, and the second electric signal is obtained after the first electric signal is gained. Then, the narrow linewidth spectrum analysis device extracts a specific frequency from the second electric signal to obtain a third electric signal, for example, using the phase-locked amplifier in fig. 1, and separating a specific carrier frequency signal from an interference environment by connecting an input end of the phase-locked amplifier with an output end of the transimpedance amplifier through a BNC connection line. The third electric signal is input into an analog-to-digital conversion module to obtain an analog-to-digital conversion result.
It should be noted that, because the optical signal reflected from the light control panel has large attenuation, weak intensity and noise, the Shan Sepu optical signal is first extracted by using a monochromator or other device, and most of the noise is removed by collecting only the optical signal in a certain wavelength range, so that the subsequent optical signal for photoelectric conversion is cleaner, which is beneficial to signal amplification and subsequent noise removal operation. After the optical signal is converted into the first electrical signal, the signal of the first point signal obtained by conversion is also weaker and has noise brought in during conversion because the intensity of the monochromatic spectrum optical signal is weak and still has partial noise, and the first electrical signal cannot directly enter an upper computer for data processing, so that the signal needs to be optimized first. As described above, the optimization of the electrical signal is performed in two steps, firstly, the electrical signal is increased in intensity so that the electrical signal is easy to identify, and then, the electrical signal of a specific frequency in the amplified electrical signal is obtained to eliminate the influence of noise carried by the single-color spectrum optical signal. The narrow-line-width spectrum analyzer and the narrow-line-width spectrum analyzer are used to obtain an electric signal (third electric signal) from which noise is removed and which is easy to be analyzed by a host computer.
The upper computer may adopt an industrial control computer (PC) or other computing devices (desktop computer, mobile computer, server, etc.) as shown in fig. 1, for example, the industrial control computer is electrically connected to the output end of the lock-in amplifier through a GPIB data line, the industrial control computer presets a film thickness model, and determines whether the monitored film deposition thickness meets a preset value (preset process requirement) by comparing the analog-to-digital conversion result with the film thickness model, if so, generates a stop instruction to terminate the operation, if not, continues the deposition operation, and continues to monitor the film thickness until the monitored film deposition thickness meets the preset value.
The scheme adopts the following working principle:
after the light signal emitted by the light source is collimated by the collimating light path, the light signal irradiates on the light control sheet representing the deposition thickness of the optical film, the light signal is reflected on the light control sheet, the reflected light signal is loaded with film thickness information, and the light signal carrying the information (namely the monitoring light signal) enters the narrow-linewidth spectrum analysis device and is analyzed into monochromatic spectrum light with a narrow linewidth. Shan Sepu light is incident to a photoelectric conversion device (signal receiving device) for stable control, and then the optical signal is converted into an electric signal which is convenient for comparison, analysis and comparison, the electric signal is amplified and input into a phase-locked amplifier, digital information of a reaction monitoring optical signal is obtained after comparison measurement is carried out with a modulation signal, the digital information is transmitted into an industrial control computer with high stability through a data interface, and the digital information is compared with a preset model in the computer to judge whether film deposition can be finished or not, so that the precise control of the film deposition thickness is realized.
In the scheme, the direct monitoring of the optical film is realized by collecting the light rays irradiated on the light control panel; separating Shan Sepu optical signals by a narrow linewidth spectrum analysis device to solve the problem of infrared spectrum wavelength positioning; the signal acquisition precision is improved by converting the single-color spectrum optical signal into an electric signal and then amplifying and stripping noise; the upper computer monitors thickness data information obtained by optical signal conversion in real time in an online mode, judges whether film deposition meets the requirements, and realizes online precise control of film deposition operation.
In some embodiments, the software programming of the film thickness model is essentially as follows:
s2, monitoring data are collected in real time, and data are read through a data collection communication interface;
s3, performing simulation restoration processing on the data of the analog-to-digital conversion result by adopting a higher-order function fitting filtering algorithm and an S-G filtering algorithm;
s4, according to a Fresnel formula and a single interface reflectivity calculation method, carrying out high reduction degree simulation calculation by combining the equivalent optical admittance of a dielectric film (deposited film) and a substrate combination to realize data fitting;
s5, carrying out real-time data tracking on the fitting function along a time axis to obtain an extremum generated by the change of the light intensity value of the reflected light along with time (deposition thickness);
s6, collecting data in real time while tracking extremum, forming a film thickness model by the collected data, storing the film thickness model in a TDMS (time domain reflectometer) storage mode as a quick storage mode, and storing the film thickness model in a MySQL (MySQL structured query language) offline data storage mode.
In the above scheme, since the optical monitoring system is required to process the high attenuation weak signal formed by film formation in real time in the monitoring process, the influence factors of various noises on the control precision are obviously increased, so that it is necessary to accurately extract the effective signal from the noises. The high-order function fitting filtering algorithm is combined with the S-G filtering algorithm, so that the noise stripping and the signal essence restoration are realized, and the precise control of film deposition is finally realized.
In some embodiments, when the thin film deposition operation is monitored online using the thin film thickness model, after step S6, the method further includes:
s7, calculating the stop time point of each film layer by using the related data (analog-digital conversion result) obtained in monitoring through the preset film layer light intensity value (which can be calculated and obtained by film design software).
The specific calculation method comprises the following steps: the current coefficient and the reflectivity coefficient are introduced through filtering treatment, the calculation formula of the actual film light intensity value is as follows, and the stop time is judged when the actual film light intensity value is the same as the designed light intensity value.
Wherein: a is a current coefficient, and light is set with parameters of the system; n is n 2 For the refractive index of the currently deposited layer, η 1 The combined admittance of the front film layer and the substrate; η (eta) 2 The combined admittance for all film layers; delta is the function of the deposited thickness and refractive index of the filmThe number is a function of time.
In the scheme, the stopping time point of each film layer is calculated, and a stopping command is output by using an interactive interface of the computer and peripheral equipment, so that effective judging and stopping processing of each film layer is realized. .
In some embodiments, when the thin film deposition operation is monitored online using the thin film thickness model, before step S2, the method further comprises:
s1, initializing a hardware system, and coordinating the transition of hardware to a monitoring state.
The hardware includes at least one of a narrow linewidth spectrum analysis device and an amplification filter device.
In some embodiments, an interactive interface is also provided in a host computer, such as an industrial control computer, for data display and interaction.
In some embodiments, a threshold value is further provided in the film thickness model, and when the analog-to-digital conversion result is compared with the film thickness model, the upper computer can also compare the analog-to-digital conversion result with the threshold value, and when the range of the threshold value is exceeded, alarm information is generated, wherein the alarm information comprises the film deposition thickness corresponding to the analog-to-digital conversion result and an abnormal event.
In the scheme, the alarm information is generated to remind operators of abnormal conditions of film deposition operation.
In some embodiments, a first reflected light fitting curve is preset in the film thickness model, the upper computer is further configured to generate a second reflected light fitting curve according to the analog-to-digital conversion result, and the upper computer compares the similarity between the first reflected light fitting curve and the second reflected light fitting curve, and when the similarity meets a preset range, the upper computer indicates that the film thickness meets the requirement, and generates a stop instruction to stop the film deposition operation.
In the scheme, the accuracy of film thickness judgment is further improved through similarity comparison between curves.
In some embodiments, the first reflected light fitting curve includes a plurality of first peaks, the second reflected light fitting curve includes a plurality of second peaks, the upper computer is further configured to compare positions or numbers of the first peaks and the second peaks or a combination of the first peaks and the second peaks, and determine a similarity between the first reflected light fitting curve and the second reflected light fitting curve according to the positions and/or numbers of the first peaks and the second peaks, so as to determine whether the thickness of the thin film meets a requirement, and generate a stop instruction to stop the thin film deposition operation when the thickness meets the requirement.
In the scheme, the calculated amount is reduced and the judging speed is increased by comparing the positions and/or the number of the first wave crest and the second wave crest.
In some embodiments, the collimated light path is composed of an optical fiber and an aspheric lens coupled thereto, and in particular, as shown in fig. 2, the light path collimation is achieved by combining optical fiber coupling with a free-form surface lens.
More preferably, the high-stability collimation light path is built by combining the fiber optical waveguide with high light transmission efficiency and the collimation lens system.
In some embodiments, a chopper is further disposed in the light source, and the light source is modulated by the chopper to obtain an alternating current light signal with a fixed period change, and the alternating current light signal emits continuous and stable light waves into an optical fiber connected with the light source.
In some embodiments, the light source type includes at least one of a visible near infrared light source, a mid infrared band light source, or a combination. Specifically, the light intensity coupling light source is used as a visible near infrared light source, and the optical fiber coupling infrared tungsten light source is used as a mid-infrared band light source.
In some embodiments, the monochromator further comprises a blazed grating. And a certain level spectrum of a certain specific wave band can be obtained by using blazed light, so that the stability of extracting Shan Sepu optical signals is further ensured.
More preferably, the parameter range of the blazed grating comprises any one of the following, or a combination of any of the following:
the wavelength range of the blazed grating is 350nm-1000nm, the grating line is 1200g/mm, and the blazed wavelength is 500nm;
the wavelength range of the blazed grating is 850nm-2600nm, the grating line is 300g/mm, and the blazed wavelength is 1250nm;
the wavelength range of the blazed grating is 2500nm-8000nm, the grating line is 150g/mm, and the blazed wavelength is 4000nm.
In some embodiments, the detector of the monochromator comprises any one of, or a combination of, any of the following:
a silicon photodetector with a wavelength ranging from 190nm to 1100nm;
an InGaAs photodetector with a wavelength ranging from 1000nm to 2500nm;
the wavelength range of the indium-arsenic-antimony photoelectric detector is 2500nm-5000nm.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment focuses on differences from other embodiments. In particular, for the method embodiments described later, since they correspond to the system, the description is relatively simple, and reference should be made to the description of some of the system embodiments.
The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.
Claims (10)
1. The utility model provides a high-accuracy wide spectrum optical film thickness on-line monitoring system which characterized in that includes:
a light source;
the collimation light path is connected with the light source to collimate the light of the light source and irradiate the light control sheet, wherein the light control sheet is positioned in a film deposition operation area of the optical film;
the narrow-line-width spectrum analysis device is used for extracting Shan Sepu optical signals from the first optical signals reflected by the light control sheet and converting the monochromatic spectrum optical signals into first electric signals;
the amplifying and filtering device is used for amplifying the first electric signal into a second electric signal, extracting a third electric signal with specific frequency from the second electric signal, and carrying out analog-to-digital conversion on the third electric signal to obtain an analog-to-digital conversion result;
the upper computer is used for comparing the analog-to-digital conversion result with a preset film thickness model to generate a stop instruction, wherein the stop instruction is used for terminating film deposition operation;
the method comprises the steps that a preset film thickness model is subjected to filtering treatment, a current coefficient and a reflectivity coefficient are introduced, an actual film light intensity value is calculated, and when the actual film light intensity value is the same as a designed light intensity value, stopping time is judged, wherein the stopping time is used for obtaining a stopping instruction;
wherein the calculation formula of the actual film light intensity value is as follows
Wherein a is a current coefficient, and the parameter setting of the on-line monitoring system is carried out according to the thickness of the high-precision broad-spectrum optical film; η1 is the combined admittance of the front film layer and the substrate; η2 is the combined admittance of all the film layers; delta is a function of the deposited thickness and refractive index of the film, i.e. a function of time.
2. The high-precision broad spectrum optical film thickness on-line monitoring system according to claim 1, wherein the collimating optical path comprises a collimating optical path consisting of an optical fiber coupled aspheric lens.
3. The high-precision broad spectrum optical film thickness on-line monitoring system as claimed in claim 1, wherein said narrow linewidth spectrum analysis device comprises a monochromator.
4. The high-precision broad spectrum optical film thickness on-line monitoring system according to claim 3, wherein the amplifying and filtering device comprises a transimpedance amplifier and a phase-locked amplifier, and the monochromator, the transimpedance amplifier and the phase-locked amplifier are electrically connected in sequence.
5. The high-precision broad spectrum optical film thickness on-line monitoring system as recited in claim 3, wherein said monochromator further comprises a blazed grating.
6. The high-precision broad spectrum optical film thickness on-line monitoring system according to claim 5, wherein the parameter range of the blazed grating comprises any one or combination of the following:
the wavelength range is 350nm-1000nm, the grating line is 1200g/mm, and the blaze wavelength is 500nm;
the wavelength range is 850nm-2600nm, the grating line is 300g/mm, and the blaze wavelength is 1250nm;
the wavelength range is 2500nm-8000nm, the grating line is 150g/mm, and the blaze wavelength is 4000nm.
7. The high-precision broad spectrum optical film thickness on-line monitoring system as claimed in claim 3, wherein the detector of the monochromator comprises any one or combination of the following:
a silicon photodetector with a wavelength ranging from 190nm to 1100nm;
an InGaAs photodetector with a wavelength ranging from 1000nm to 2500nm;
the wavelength range of the indium-arsenic-antimony photoelectric detector is 2500nm-5000nm.
8. The high-precision broad spectrum optical film thickness on-line monitoring system as claimed in claim 1, wherein said light source further comprises a chopper.
9. The high-precision broad spectrum optical film thickness on-line monitoring system according to claim 1, wherein the film thickness model further comprises a preset first reflected light fitting curve, the upper computer is further configured to generate a second reflected light fitting curve according to the analog-to-digital conversion result, and compare similarities of the first reflected light fitting curve and the second reflected light fitting curve to generate the stop command.
10. The high-precision broad spectrum optical film thickness on-line monitoring system according to claim 9, wherein the first reflected light fitting curve comprises a plurality of first peaks, the second reflected light fitting curve comprises a plurality of second peaks, and the upper computer is further configured to compare positions and/or numbers of the first peaks and the second peaks to generate the stop instruction.
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