Film layer measurement method and device

Abstract

The present invention relates to the field of optical detection technologies, and particularly to a film layer measurement method and apparatus. The film layer measurement method includes: irradiating a sample to be measured with a pump light and a probe light, and the probe light forms a probe signal light after being reflected by the sample to be measured. Among them, either the probe light or the pump light is guided by a retroreflector to irradiate the sample to be measured, and the retroreflector moves back and forth in a first direction to perform time delay on the probe light or the pump light; receiving the probe signal light when the retroreflector moves forward in the first direction to generate a forward scanning spectrum, and receiving the probe signal light when the retroreflector moves backward in the first direction to generate a reverse scanning spectrum; integrating the forward scanning spectrum and the reverse scanning spectrum to generate a probe spectrum, and obtaining the film layer properties of the sample to be measured based on the probe spectrum. The present invention is at least beneficial to improving the measurement efficiency of the film layer properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and particularly relates to a film layer measurement method and device. Background Art

[0002] In the photoacoustic film layer measurement technology, the pump light needs to irradiate the sample surface to excite the sample to generate heat, and then generate thermoelastic deformation to form acoustic wave pulses. The generated acoustic wave pulses propagate longitudinally in the thin film and travel back and forth between the two surfaces of the sample. When propagating to the upper surface, it will cause a change in the reflectivity of the upper surface of the film layer and at the same time a slight deformation occurs. The change in the upper surface can be detected by the probe light. One of the pump light and the probe light reaches the sample surface through a time delay line. The time delay line is used to achieve time delay by changing the optical path difference between the pump light and the probe light.

[0003] The time delay line usually drives a retroreflector to move by a linear displacement stage to achieve time delay. In the traditional measurement method, signals are collected when the linear displacement stage moves forward. Since the linear displacement stage requires a certain reset time after moving forward, the improvement of the measurement efficiency is limited. Summary of the Invention

[0004] In view of this, the present invention aims to provide a film layer measurement method and device, which is at least beneficial to improving the measurement efficiency of the film layer properties.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows:

[0006] On the one hand, the present invention provides a film layer measurement method, including: irradiating a sample to be measured with pump light and probe light, and the probe light forms a probe signal light after being reflected by the sample to be measured. Among them, the probe light or the pump light is guided by a retroreflector to irradiate the sample to be measured, and the retroreflector moves back and forth along a first direction to perform time delay on the probe light or the pump light; receiving the probe signal light when the retroreflector moves forward along the first direction to generate a forward scan spectrum, and receiving the probe signal light when the retroreflector moves backward along the first direction to generate a reverse scan spectrum; integrating the forward scan spectrum and the reverse scan spectrum to generate a probe spectrum, and obtaining the film layer properties of the sample to be measured based on the probe spectrum.

[0007] Further, the film layer properties of the sample to be measured include the film layer thickness of the sample to be measured.

[0008] Further, integrating the forward scan spectrum and the reverse scan spectrum to generate a probe spectrum includes: compensating the forward scan spectrum or the reverse scan spectrum to align the time of the forward scan spectrum and the reverse scan spectrum; performing an averaging process on the time-aligned forward scan spectrum and reverse scan spectrum to obtain a probe spectrum.

[0009] Further, compensating the forward-scanning spectrum or the reverse-scanning spectrum includes: pre-acquiring the time offset between the forward-scanning spectrum and the reverse-scanning spectrum under different measurement states to obtain the correspondence between the measurement state and the time offset; based on the correspondence between the measurement state and the time offset, determining the time offset to be compensated according to the actual measurement state, and using the time offset to be compensated to compensate the forward-scanning spectrum or the reverse-scanning spectrum.

[0010] Further, the measurement state includes the operating state of the retroreflector or the film state of the sample to be measured. Among them, the operating state includes the moving speed and acceleration of the retroreflector, and the film state includes the film material and the film thickness.

[0011] Further, pre-acquiring the time offset between the forward-scanning spectrum and the reverse-scanning spectrum under different measurement states includes: for the forward-scanning spectrum and the reverse-scanning spectrum under each measurement state, determining the first time point corresponding to the signal characteristic peak in the forward-scanning spectrum, and determining the second time point corresponding to the corresponding signal characteristic peak in the reverse-scanning spectrum. The difference between the first time point and the second time point is the time offset.

[0012] Further, the signal characteristic peak is a zero-point extreme value signal, a photo-thermal signal peak or an echo signal peak.

[0013] On the other hand, the present invention provides a film measurement device, including: a light source that emits a pump light and a probe light for irradiating the sample to be measured, and the probe light is reflected by the sample to be measured to form a probe signal light; a retroreflector that is located in the transmission optical path of the probe light or in the transmission optical path of the pump light, and the retroreflector moves back and forth along the first direction to perform time delay on the probe light or the pump light; a signal receiver that receives the probe signal light when the retroreflector moves forward along the first direction to generate a forward-scanning spectrum, and receives the probe signal light when the retroreflector moves backward along the first direction to generate a reverse-scanning spectrum; a signal processing module that integrates the forward-scanning spectrum and the reverse-scanning spectrum to generate a detection spectrum, and obtains the film properties of the sample to be measured based on the detection spectrum.

[0014] Further, the signal processing module is at least configured to: compensate the forward-scanning spectrum or the reverse-scanning spectrum to align the time of the forward-scanning spectrum and the reverse-scanning spectrum, and perform an averaging process on the time-aligned forward-scanning spectrum and reverse-scanning spectrum to generate a detection spectrum.

[0015] Further, the signal processing module determines the time offset to be compensated according to the actual measurement state based on the pre-acquired correspondence between the measurement state and the time offset, and uses the time offset to be compensated to compensate the forward-scanning spectrum or the reverse-scanning spectrum.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: In the film layer measurement method provided by the embodiments of the present invention, not only the spectrum when the retroreflector moves forward in the first direction is acquired, but also the spectrum when the retroreflector moves backward in the first direction is acquired. Thus, compared with the traditional measurement method that only acquires the forward moving spectrum, within the same measurement time, the film layer measurement method provided by the present invention can achieve more repeated measurements. It can be understood that the more the number of repeated measurements, the higher the accuracy of the measurement value after averaging the multiple measurement results. Therefore, the film layer measurement method provided by the embodiments of the present invention can improve the measurement accuracy. In the case of the same number of repeated measurements, the film layer measurement method provided by the present invention can complete the measurement in a shorter time. Therefore, the measurement efficiency can be improved.

[0017] In addition, in the film layer measurement method provided by the embodiments of the present invention, the peak search algorithm is used to calculate the signal characteristic peaks corresponding to the forward scan spectrum and the reverse scan spectrum to obtain the time offset between the forward scan spectrum and the reverse scan spectrum, and time compensation is performed on any one of the forward scan spectrum and the reverse scan spectrum, effectively avoiding the problem of reduced measurement accuracy caused by simply aligning the forward scan spectrum and the reverse scan spectrum. By using the compensation method to make the time scales of the forward scan spectrum and the reverse scan spectrum consistent, not only can the measurement signal noise be reduced and the signal-to-noise ratio of the measurement spectrum signal be improved, but also a high measurement accuracy can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0019] Figure 1 It is a schematic structural diagram of a film layer measurement device according to an embodiment of the present invention;

[0020] Figure 2 It is a schematic diagram of the forward scan signal (blue line) and the reverse scan signal (red line) of a 4000 Å tungsten thin film according to an embodiment of the present invention;

[0021] Figure 3 It is a schematic diagram of the forward scan signal (blue line) of a 4000 Å tungsten thin film according to an embodiment of the present invention and the echo signal (red line) directly averaged from the bidirectional scan signals;

[0022] Figure 4 It is an enlarged schematic diagram of a partial curve of the forward scan signal (blue line) and the reverse scan signal (red line) of a 4000 Å tungsten thin film according to an embodiment of the present invention;

[0023] Figure 5Schematic diagram of the forward scan spectral signal (blue line) and reverse scan spectral signal (red line) of the 4000 Å tungsten thin film after compensation alignment according to the embodiments of the present invention;

[0024] Figure 6 Flow chart of a compensation method according to the embodiments of the present invention;

[0025] Figure 7 Flow chart of another compensation method according to the embodiments of the present invention;

[0026] Figure 8 Schematic diagram when there is a time offset between the forward scan signal (blue line) and reverse scan signal (red line) of the 100 Å tungsten thin film according to the embodiments of the present invention;

[0027] Figure 9 Schematic diagram of the compensated forward scan signal (blue line) and reverse scan signal (red line) of the 100 Å tungsten thin film according to the embodiments of the present invention. Detailed implementation manners

[0028] Through analysis, it is found that in the traditional measurement method, each time a signal is collected, the linear displacement stage needs to make a round-trip movement, that is, the signal is collected only when the linear displacement stage moves forward, and the reverse movement of the linear displacement stage is used to reset to the initial position of the forward movement, and no signal is collected during the reverse movement. Moreover, for the measurement of one parameter, the signals during multiple forward movements need to be collected and averaged. Therefore, the measurement efficiency of the traditional measurement method is relatively low.

[0029] In addition, for the method of collecting signals both during forward movement and reverse movement, the following problems may exist. Since there are acceleration sections and deceleration sections when the linear displacement stage makes a round-trip movement, there is a certain return error between the forward movement and the reverse movement. As a result, when collecting bidirectional scan signals, there is a time offset difference (time offset) between the obtained forward scan spectrum and reverse scan spectrum. If the forward scan spectrum and reverse scan spectrum are directly subjected to simple time alignment and smoothing processing, the signal peaks of the finally generated spectral sequence will be broadened, which instead reduces the measurement accuracy of repeated measurements.

[0030] To solve the above problems, the embodiments of the present invention provide a film layer measurement method, which is a measurement method based on two-way scanning of laser pump-probe, effectively solving the influence of the time offset difference caused by the return error of the linear displacement stage's round-trip movement on the measurement result, and collecting signals both during bidirectional movement, avoiding the waste of the reset movement time of the linear displacement stage. On the basis of reducing the measurement signal noise, it has a high measurement efficiency, and at the same time ensures a high measurement accuracy.

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0032] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0033] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0034] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0035] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0036] Reference Figure 1, the film layer measurement method provided by the present invention includes: irradiating a sample to be measured 18 with a pump light and a probe light, and the probe light forms a probe signal light after being reflected by the sample to be measured 18. Among them, the probe light or the pump light is guided by a retroreflector 14 to irradiate the sample to be measured 18, and the retroreflector 14 moves back and forth along the first direction X to perform a time delay on the probe light or the pump light; receiving the probe signal light when the retroreflector 14 moves forward along the first direction X to generate a forward scan spectrum, and receiving the probe signal light when the retroreflector 14 moves backward along the first direction X to generate a backward scan spectrum; integrating the forward scan spectrum and the backward scan spectrum to generate a probe spectrum, and obtaining the film layer properties of the sample to be measured 18 based on the probe spectrum.

[0037] The film layer measurement method provided by the present invention can be implemented based on a film layer measurement device, refer to Figure 1 , the film layer measurement device may include: a light source for emitting a pump light and a probe light for irradiating the sample to be measured 18, and the probe light forms a probe signal light after being reflected by the sample to be measured 18; a retroreflector 14 located in the transmission optical path of the probe light or in the transmission optical path of the pump light, and the retroreflector 14 moves back and forth along the first direction X for performing a time delay on the probe light or the pump light; a signal receiver for receiving the probe signal light when the retroreflector 14 moves forward along the first direction X to generate a forward scan spectrum, and receiving the probe signal light when the retroreflector 14 moves backward along the first direction X to generate a backward scan spectrum; a signal processing module for integrating the forward scan spectrum and the backward scan spectrum to generate a probe spectrum and obtaining the film layer properties of the sample to be measured 18 based on the probe spectrum.

[0038] It should be noted that Figure 1 Taking the retroreflector 14 being arranged in the transmission optical path of the probe light as an example, the film layer measurement method and the film layer measurement device provided by the embodiments of the present invention are described.

[0039] In some embodiments, the retroreflector 14 may include several reflectors, and the retroreflector 14 can move back and forth along the first direction X driven by a linear displacement stage. In some examples, the linear displacement stage can move back and forth along the first direction X driven by a servo motor.

[0040] In some embodiments, the light source may include a first laser and a second laser. Among them, the first laser is used to generate the pump light, and the second laser is used to generate the probe light. In some other embodiments, refer to Figure 1 , the light source includes a laser 10 and a beam splitter 11. Among them, the laser 10 is used to generate a pulsed light beam, and the beam splitter 11 is used to divide the pulsed light beam into two beams, one beam is the pump light, and the other beam is the probe light. In some examples, the pulsed light beam generated by the laser 10 can be an ultrashort pulsed light beam, and the beam splitter 11 may include a polarization beam splitting prism.

[0041] It should be noted that both the pump light and the probe light will ultimately be incident on the same incident position of the sample 18 to be measured. Among them, the pump light is used to form acoustic waves in the sample 18 to be measured. In this way, the reflectivity of the corresponding position of the sample 18 to be measured is changed. Photoacoustic measurement is to obtain the film properties of the sample 18 to be measured by measuring the change in the reflectivity of the sample 18 to be measured.

[0042] In some embodiments, referring to Figure 1 , the film measurement device further includes a modulator 12. The modulator 12 is arranged on the transmission optical path of the pump light and is used to perform amplitude modulation on the pump light to enhance the pump light signal. In some examples, continuing to refer to Figure 1 , the pump light emitted by the modulator 12 can be guided by several mirrors and irradiated on the sample 18 to be measured.

[0043] In some examples, referring to Figure 1 , the probe light emitted by the beam splitter 11 can be guided by several mirrors and injected into the retroreflector 14. The probe light emitted by the retroreflector 14 can be guided by several mirrors and irradiated on the sample 18 to be measured.

[0044] In some embodiments, referring to Figure 1 , the signal receiver may include a detector 13, a lock-in amplifier 16 and a signal processor 17. The film measurement device may further include a function generator 15. In some examples, the detector 13 may be a photodetector for converting an optical signal into an electrical signal. In the technical solution provided by the embodiments of the present invention, the detector 13 acquires the signal light formed by the reflection of the probe light by the sample 18 to be measured at multiple different delay times. Through the photoelectric conversion process of the signal light, the detection information is obtained according to the signal light in the form of an electrical signal. The retroreflector 14 moving along the first direction X continuously adjusts the delay time between the pump light and the probe light. Therefore, the detection information obtained during the continuous acquisition and detection process of the detector 13 also changes with the time delay. In this way, the corresponding film properties can be obtained according to this change situation. The function generator 15 is used to send a first signal to the modulator 12 to modulate the phase of the pump light. The function generator 15 is also used to send a second signal with a preset frequency to the lock-in amplifier 16. The lock-in amplifier 16 is used to demodulate the signal detected by the detector 13 at the preset frequency according to the second signal and output it to the signal processor 17. The signal processor 17 is used to generate a forward scan spectrum and a reverse scan spectrum according to the signal demodulated by the lock-in amplifier 16.

[0045] It should be noted that the film of the sample 18 to be measured can be at least one of a metal film and a dielectric film. The embodiments of the present invention do not make specific limitations on the type of the sample 18 to be measured.

[0046] In some embodiments, the film layer properties of the sample 18 to be measured include the film layer thickness of the sample 18 to be measured.

[0047] As can be seen from the foregoing, due to the error between the forward movement and the reverse movement of the retroreflector 14, there is a time shift between the forward scan spectrum and the reverse scan spectrum, that is, the time shift amount. For example, referring to Figure 2 , for a tungsten thin film with a thickness of 4000 Å, a two-way scan measurement is performed, and there is a time shift between the forward scan spectrum (blue line) and the reverse scan spectrum (red line). If the forward scan spectrum and the reverse scan spectrum are directly subjected to simple time alignment and smoothing processing, the signal peaks of the generated spectrum will be broadened. As shown in Figure 3 , the forward scan signal of the 4000 Å tungsten thin film is shown as the blue line, and the echo signal spectrum after directly simply aligning the signals of the two-way scan measurement is shown as the red line. Compared with the forward scan signal, the signal peak of the echo signal is broadened. In this way, the measurement accuracy of measuring the 4000 Å tungsten thin film by two-way scan measurement will become worse.

[0048] To solve the influence of the time shift amount, the film layer measurement method provided by the embodiments of the present invention integrates the forward scan spectrum and the reverse scan spectrum to generate a detection spectrum with higher measurement accuracy. In some embodiments, integrating the forward scan spectrum and the reverse scan spectrum to generate a detection spectrum includes: compensating the forward scan spectrum or the reverse scan spectrum to align the forward scan spectrum and the reverse scan spectrum in time; averaging the forward scan spectrum and the reverse scan spectrum that are time-aligned to obtain a detection spectrum.

[0049] In some embodiments, compensating the forward scan spectrum or the reverse scan spectrum includes: pre-acquiring the time shift amount between the forward scan spectrum and the reverse scan spectrum under different measurement states to obtain the corresponding relationship between the measurement state and the time shift amount; based on the corresponding relationship between the measurement state and the time shift amount, determining the time shift amount to be compensated according to the actual measurement state, and compensating the forward scan spectrum or the reverse scan spectrum with the time shift amount to be compensated.

[0050] In some embodiments, the measurement state includes the operating state of the retroreflector 14 or the film layer state of the sample 18 to be measured. Among them, the operating state includes the moving speed and acceleration of the retroreflector 14, and the film layer state includes the film layer material and the film layer thickness. It should be noted that there are various combinations of different film layer materials and different film layer thicknesses, and each combination is a film layer state.

[0051] In some embodiments, obtaining the time offset between the forward-scanning spectrum and the backward-scanning spectrum under different measurement states in advance includes: for the forward-scanning spectrum and the backward-scanning spectrum under each measurement state, determining the first time point corresponding to the signal characteristic peak in the forward-scanning spectrum, and determining the second time point corresponding to the corresponding signal characteristic peak in the backward-scanning spectrum, and the difference between the first time point and the second time point is the time offset.

[0052] In some embodiments, referring to Figure 2 and Figure 4 , the signal characteristic peak is a zero-point extreme value signal, a photo-thermal signal peak or an echo signal peak.

[0053] In some embodiments, the signal characteristic peaks of the forward-scanning spectrum and the backward-scanning spectrum can be calculated by a fitting peak-finding algorithm, and the difference is taken to obtain the time offset.

[0054] Figure 5 FIG. is a schematic diagram of the bidirectional scanning spectrum after compensating the forward-scanning spectrum by using the compensation method provided by the embodiment of the present invention when the sample 18 to be measured is a 4000 Å tungsten thin film. Figure 5 In, the backward-scanning spectrum and the compensated forward-scanning spectrum are basically coincident, and the time scale consistency is relatively high.

[0055] The following respectively gives examples of the two compensation methods provided by the above embodiments of the present invention. Referring to Figure 6 , Method 1 is a method of obtaining the time offset between the forward-scanning spectrum and the backward-scanning spectrum of the retroreflector 14 under different operating states in advance and using the time offset for compensation. Referring to Figure 7 , Method 2 is a method of obtaining the time offset between the forward-scanning spectrum and the backward-scanning spectrum under different film layer states in advance and using the time offset for compensation.

[0056] Method 1 is as follows: Since the return error of the retroreflector 14 is different under different operating states, the time offset between the forward-scanning spectrum and the backward-scanning spectrum in different operating states is different. Based on this, it is necessary to measure and establish a relationship table between different operating states and the time offset in advance. During actual measurement, the corresponding time offset can be found according to the actual operating state of the retroreflector 14 for compensation to obtain the forward-scanning spectrum and the backward-scanning spectrum with time alignment.

[0057] Method 2 is as follows: Measure the sample 18 to be measured with different film layer states, establish a relationship table between different film layer states and the time offset. During actual measurement, the corresponding time offset can be found in the relationship table according to the film layer state for compensation to obtain the forward-scanning spectrum and the backward-scanning spectrum with time alignment.

[0058] The tungsten thin film with a thickness of 100 Å is measured by two-way scanning using the film layer measurement method provided by the embodiment of the present invention. The forward scanning spectrum and the reverse scanning spectrum before compensation are as follows Figure 8 shown. There is a time shift between the two. Using the first echo signal of the acoustic wave as the signal characteristic peak for compensation alignment, the forward scanning spectrum and the reverse scanning spectrum with consistent time scale alignment as shown in Figure 9 can be obtained.

[0059] The present invention solves the problem that there is a time error between the forward scanning spectrum and the reverse scanning spectrum caused by the return error of the retroreflector during the round-trip movement, and realizes a film layer measurement technology with two-way movement and fast scanning, which is beneficial to improving the measurement efficiency, reducing the measurement signal noise, enhancing the signal-to-noise ratio of the measurement photoacoustic signal, and ensuring high measurement accuracy.

[0060] On the other hand, the present invention also provides a film layer measurement device, including: a light source, a retroreflector, a signal receiver, and a signal processing module. Specifically, reference can be made to the film layer measurement device provided in the above embodiment, which will not be elaborated here.

[0061] In some embodiments, the signal processing module is at least configured to: compensate the forward scanning spectrum or the reverse scanning spectrum to align the time of the forward scanning spectrum and the reverse scanning spectrum, and perform an averaging process on the time-aligned forward scanning spectrum and reverse scanning spectrum to generate a detection spectrum.

[0062] In some embodiments, the signal processing module determines the time offset to be compensated according to the actual measurement state based on the pre-acquired correspondence between the measurement state and the time offset, and compensates the forward scanning spectrum or the reverse scanning spectrum with the time offset to be compensated.

[0063] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps recorded in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved. There is no limitation here.

[0064] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A film layer measurement method, characterized in that: include: The sample to be tested is irradiated with pump light and detection light, and the detection light is reflected by the sample to be tested to form detection signal light, wherein the detection light or the pump light is guided by a reflector to irradiate the sample to be tested, and the reflector moves back and forth along a first direction to time delay the detection light or the pump light; receiving a detection signal light when the retroreflector moves forward along a first direction to generate a forward scanning spectrum, and receiving a detection signal light when the retroreflector moves backward along the first direction to generate a backward scanning spectrum; Integrating the forward scanning spectrum and the reverse scanning spectrum to generate a detection spectrum, and obtaining the film properties of the sample to be tested based on the detection spectrum; Integrating the forward scanning spectrum and the reverse scanning spectrum to generate a detection spectrum comprises: Compensating the forward scanning spectrum or the reverse scanning spectrum so that the forward scanning spectrum and the reverse scanning spectrum are time-aligned; averaging the time-aligned forward scanning spectrum and the reverse scanning spectrum to obtain the detection spectrum; Compensating the forward scanning spectrum or the reverse scanning spectrum includes: Pre-acquire the time offset between the forward scanning spectrum and the reverse scanning spectrum under different measurement states, and obtain the corresponding relationship between the measurement state and the time offset; Based on the correspondence between the measurement state and the time offset, the time offset to be compensated is determined according to the actual measurement state, and the forward scanning spectrum or the reverse scanning spectrum is compensated by using the time offset to be compensated.

2. The film layer measurement method according to claim 1, characterized in that: The film properties of the sample to be tested include the film thickness of the sample to be tested.

3. The film layer measurement method according to claim 1, characterized in that: The measurement state includes the operating state of the retroreflector or the film state of the sample to be measured, wherein the operating state includes the moving speed and acceleration of the retroreflector, and the film state includes the film material and the film thickness.

4. The film layer measurement method according to claim 1, characterized in that: Pre-acquiring the time offset between the forward scanning spectrum and the reverse scanning spectrum under different measurement states includes: for the forward scanning spectrum and the reverse scanning spectrum under each measurement state, determining a first time point corresponding to a signal characteristic peak in the forward scanning spectrum, and determining a second time point corresponding to a corresponding signal characteristic peak in the reverse scanning spectrum, and the difference between the first time point and the second time point is the time offset.

5. The film layer measurement method according to claim 4, characterized in that: The signal characteristic peak is a zero point extreme value signal, a photothermal signal peak or an echo signal peak.

6. A film layer measuring device, characterized in that: include: A light source, wherein the light source emits pump light and detection light for irradiating the sample to be tested, and the detection light is reflected by the sample to be tested to form detection signal light; A retroreflector, the retroreflector is located in the transmission light path of the probe light, or in the transmission light path of the pump light, and the retroreflector moves back and forth along a first direction to time delay the probe light or the pump light; a signal receiver, the signal receiver receiving the detection signal light when the retroreflector moves forward along the first direction to generate a forward scanning spectrum, and receiving the detection signal light when the retroreflector moves backward along the first direction to generate a backward scanning spectrum; A signal processing module, wherein the signal processing module integrates the forward scanning spectrum and the reverse scanning spectrum to generate a detection spectrum, and obtains the film properties of the sample to be tested based on the detection spectrum; The signal processing module is at least configured to: compensate the forward scanning spectrum or the reverse scanning spectrum to time-align the forward scanning spectrum and the reverse scanning spectrum, and average the time-aligned forward scanning spectrum and reverse scanning spectrum to generate the detection spectrum; The signal processing module determines the time offset to be compensated according to the actual measurement state based on the correspondence between the measurement state and the time offset acquired in advance, and compensates the forward scanning spectrum or the reverse scanning spectrum by using the time offset to be compensated.

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