Film layer measuring method and device

Abstract

The invention relates to the technical field of optical detection, in particular to a film layer measuring method and device.The film layer measuring method comprises the steps that a to-be-measured sample is irradiated with pump light and probe light, the probe light is reflected by the to-be-measured sample to form probe signal light, the probe light or the pump light is guided by a retroreflector to irradiate the to-be-measured sample, and the probe signal light forms probe signal light; the retroreflector moves back and forth in the first direction so as to carry out time delay on the probe light or the pump light. 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; integrating the forward scanning spectrum and the reverse scanning spectrum to generate a detection spectrum, and obtaining the film property of the to-be-detected sample based on the detection spectrum. The invention is at least beneficial to improving the measurement efficiency of the film property.

Description

Technical Field

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

[0002] In the photoacoustic film layer measurement technology, the pump light needs to be irradiated onto the sample surface to stimulate the sample to generate heat, thereby generating thermoelastic deformation and forming an acoustic wave pulse. The generated acoustic wave pulse propagates longitudinally in the film to and from the two surfaces of the sample. When it propagates to the upper surface, it will cause the reflectivity of the upper surface of the film layer to change, and a slight deformation will occur at the same time. The change of the upper surface can be detected by the detection light. One of the pump light and the detection 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 detection light.

[0003] The time delay line is usually driven by a linear translation stage to move the reflector to achieve time delay. The traditional measurement method collects signals when the linear translation stage moves in the forward direction. Since the linear translation stage requires a certain reset time after the forward movement, this limits the improvement of measurement efficiency. Summary of the invention

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

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows: The present invention provides a film measurement method, comprising: irradiating a sample to be measured with pump light and detection light, the detection light is reflected by the sample to be measured to form detection signal light, wherein the detection light or the pump light is guided by a reflector to irradiate the sample to be measured, and the reflector moves back and forth along a first direction to time delay the detection light or the pump light; receiving the detection signal light when the reflector moves forward along the first direction to generate a forward scanning spectrum, and receiving the detection signal light when the reflector moves backward along the first direction to generate a reverse 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 measured based on the detection spectrum.

[0006] Furthermore, the film properties of the sample to be tested include the film thickness of the sample to be tested.

[0007] Furthermore, integrating the forward scanning spectrum and the reverse scanning spectrum to generate the detection spectrum includes: compensating the forward scanning spectrum or the reverse scanning spectrum to time-align the forward scanning spectrum and the reverse scanning spectrum; averaging the time-aligned forward scanning spectrum and reverse scanning spectrum to obtain the detection spectrum.

[0008] Furthermore, 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 corresponding relationship between the measurement state and the time offset; based on the corresponding relationship 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 for the forward scanning spectrum or the reverse scanning spectrum.

[0009] Furthermore, 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.

[0010] Furthermore, 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, and the difference between the first time point and the second time point is the time offset.

[0011] Furthermore, the signal characteristic peak is a zero point extreme value signal, a photothermal signal peak or an echo signal peak.

[0012] Another aspect of the present invention provides a film layer measurement device, comprising: a light source, the light source emits pump light and detection light for irradiating a sample to be measured, the detection light is reflected by the sample to be measured to form a detection signal light; a reflector, the reflector is located in the transmission light path of the detection light, or in the transmission light path of the pump light, the reflector moves back and forth along a first direction to time delay the detection light or the pump light; a signal receiver, the signal receiver receives the detection signal light when the reflector moves forward along the first direction to generate a forward scanning spectrum, and receives the detection signal light when the reflector moves reversely along the first direction to generate a reverse scanning spectrum; a signal processing module, the signal processing module integrates the forward scanning spectrum and the reverse scanning spectrum to generate a detection spectrum, and obtains the film layer properties of the sample to be measured based on the detection spectrum.

[0013] Furthermore, 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 a detection spectrum.

[0014] Furthermore, 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 using the time offset to be compensated.

[0015] Compared with the prior art, the invention can achieve the following beneficial effects: in the film layer measurement method provided in the embodiment of the present invention, not only the spectrum of the reflector when it moves forward along the first direction is obtained, but also the spectrum of the reflector when it moves reversely along the first direction is obtained. In this way, compared with the traditional measurement method of only obtaining 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 times the repeated measurements are performed, the higher the accuracy of the measured value after averaging the multiple measurement results. Therefore, the film layer measurement method provided by the embodiment of the present invention can improve the measurement accuracy. Under the condition 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, thereby improving the measurement efficiency.

[0016] In addition, in the film layer measurement method provided by an embodiment of the present invention, a peak-finding algorithm is used to calculate the signal characteristic peaks corresponding to the forward scanning spectrum and the reverse scanning spectrum to obtain the time offset of the forward scanning spectrum and the reverse scanning spectrum, and time compensation is performed on either the forward scanning spectrum or the reverse scanning spectrum, thereby effectively avoiding the problem of reduced measurement accuracy caused by simply aligning the forward scanning spectrum and the reverse scanning spectrum. The compensation method is used to make the time scales of the forward scanning spectrum and the reverse scanning spectrum consistent, which can not only reduce the measurement signal noise and improve the signal-to-noise ratio of the measurement spectrum signal, but also ensure a high measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 A schematic diagram of the structure of a film layer measuring device according to an embodiment of the present invention; Figure 2 A schematic diagram of a forward scanning signal (blue line) and a reverse scanning signal (red line) of a 4000Å tungsten film according to an embodiment of the present invention; Figure 3 A schematic diagram of a 4000Å tungsten film forward scanning signal (blue line) and an echo signal (red line) directly averaged from a bidirectional scanning signal according to an embodiment of the present invention; Figure 4 It is a schematic diagram of an enlarged portion of the curves of the forward scanning signal (blue line) and the reverse scanning signal (red line) of the 4000Å tungsten film according to the embodiment of the present invention; Figure 5 A schematic diagram of a forward scanning spectral signal (blue line) and a reverse scanning spectral signal (red line) of a 4000Å tungsten film after compensation alignment according to an embodiment of the present invention; Figure 6 A flow chart of a compensation method described in an embodiment of the present invention; Figure 7 A flowchart of another compensation method described in an embodiment of the present invention; Figure 8 A schematic diagram of a 100Å tungsten film forward scanning signal (blue line) and a reverse scanning signal (red line) when there is a time offset according to an embodiment of the present invention; Fig. 9 Schematic diagram of the compensated forward scanning signal (blue line) and reverse scanning signal (red line) of the 100Å tungsten film described in the embodiment of the present invention. DETAILED DESCRIPTION

[0018] After analysis, it was found that in the traditional measurement method, each time a signal is collected, the linear translation stage needs to make a reciprocating motion, that is, the signal is only collected when the linear translation stage moves in the forward direction, and the reverse movement of the linear translation stage is used to reset to the initial position of the forward movement. No signal is collected during the reverse movement, and the measurement of a parameter requires multiple signals during the forward movement to be collected and averaged. Therefore, the traditional measurement method has low measurement efficiency.

[0019] In addition, the following problem may exist in the method of collecting signals during both forward and reverse movement. Since there are acceleration and deceleration sections when the linear translation stage performs reciprocating motion, there is a certain return error between the forward movement and the reverse movement, resulting in a time offset difference (time offset) between the forward scanning spectrum and the reverse scanning spectrum obtained when collecting bidirectional scanning signals. If the forward scanning spectrum and the reverse scanning spectrum are directly simply time aligned and smoothed, the signal peak of the finally generated spectral sequence will be broadened, which in turn reduces the measurement accuracy of repeated measurements.

[0020] To solve the above problems, an embodiment of the present invention provides a film layer measurement method, which is a bidirectional scanning measurement method based on laser pump detection. It effectively solves the influence of the time offset difference caused by the return error of the reciprocating motion of the linear translation stage on the measurement result, and collects signals during bidirectional movement, avoiding the waste of resetting movement time of the linear translation stage. It has higher measurement efficiency while reducing the measurement signal noise, and also ensures higher measurement accuracy.

[0021] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0022] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0023] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the 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, and therefore cannot be understood as a limitation on the 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 indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0024] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0025] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0026] refer to Figure 1 The film measurement method provided by the present invention includes: using pump light and detection light to irradiate the sample to be measured 18, and the detection light is reflected by the sample to be measured 18 to form detection signal light, wherein the detection light or the pump light is guided by the reflector 14 to irradiate the sample to be measured 18, and the reflector 14 moves back and forth along the first direction X to time delay the detection light or the pump light; receiving the detection signal light when the reflector 14 moves forward along the first direction X to generate a forward scanning spectrum, and receiving the detection signal light when the reflector 14 moves backward along the first direction X to generate a reverse 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 measured 18 based on the detection spectrum.

[0027] The film layer measurement method provided by the present invention can be implemented based on the film layer measurement device, referring to Figure 1The film layer measuring device may include: a light source, the light source is used to emit pump light and detection light for irradiating the sample 18 to be measured, and the detection light is reflected by the sample 18 to form a detection signal light; a reflector 14, the reflector 14 is located in the transmission light path of the detection light, or is located in the transmission light path of the pump light, the reflector 14 moves back and forth along the first direction X, and is used to time delay the detection light or the pump light; a signal receiver, the signal receiver receives the detection signal light when the reflector 14 moves forward along the first direction X to generate a forward scanning spectrum, and receives the detection signal light when the reflector 14 moves backward along the first direction X to generate a reverse scanning spectrum; a signal processing module, the signal processing module is used to integrate the forward scanning spectrum and the reverse scanning spectrum to generate a detection spectrum, and obtain the film layer properties of the sample 18 to be measured based on the detection spectrum.

[0028] It should be noted that Figure 1 Taking the case where the reflector 14 is disposed in the transmission optical path of the detection light as an example, the film layer measurement method and the film layer measurement device provided by the embodiment of the present invention are described.

[0029] In some embodiments, the retroreflector 14 may include a plurality of reflective mirrors, and the retroreflector 14 may be driven by a linear translation stage to move back and forth along the first direction X. In some examples, the linear translation stage may be driven by a servo motor to move back and forth along the first direction X.

[0030] In some embodiments, the light source may include a first laser and a second laser, wherein the first laser is used to generate pump light and the second laser is used to generate detection light. Figure 1 The light source includes a laser 10 and a beam splitter 11, wherein the laser 10 is used to generate a pulsed light beam, and the beam splitter 11 is used to split the pulsed light beam into two beams, one of which is a pump light beam and the other is a probe light beam. In some examples, the pulsed light beam generated by the laser 10 may be an ultrashort pulsed light beam, and the beam splitter 11 may include a polarization beam splitter prism.

[0031] It should be noted that the pump light and the probe light will eventually be incident on the same incident position of the sample to be tested 18. The pump light is used to form an acoustic wave in the sample to be tested 18, thereby changing the reflectivity of the corresponding position of the sample to be tested 18. Photoacoustic measurement is to obtain the film properties of the sample to be tested 18 by measuring the change in the reflectivity of the sample to be tested 18.

[0032] In some embodiments, reference Figure 1 The film layer measurement device further includes a modulator 12, which 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. Figure 1The pump light emitted by the modulator 12 can be guided by a number of reflection mirrors to illuminate the sample 18 to be measured.

[0033] In some examples, reference Figure 1 The detection light emitted by the beam splitter 11 can be guided by a plurality of reflectors to enter the retroreflector 14 , and the detection light emitted by the retroreflector 14 can be guided by a plurality of reflectors to irradiate the sample 18 to be tested.

[0034] In some embodiments, reference Figure 1 , the signal receiver may include a detector 13, a phase-locked amplifier 16 and a signal processor 17, and the film layer measurement device may also 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 in the embodiment of the present invention, the detector 13 obtains the signal light formed by the reflection of the detection light by the sample to be measured 18 at multiple different delay times, and obtains the detection information according to the signal light in the form of an electrical signal through the photoelectric conversion processing of the signal light. The reflector 14 moving along the first direction X continuously adjusts the delay time between the pump light and the detection light. Therefore, the detection information obtained in the continuous collection and detection process of the detector 13 also changes with the time delay. In this way, the corresponding film layer properties can be obtained according to this change. 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 of a preset frequency to the phase-locked amplifier 16. The phase-locked amplifier 16 is used to demodulate the signal detected by the detector 13 at a 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 scanning spectrum and a reverse scanning spectrum according to the signal demodulated by the phase-locked amplifier 16.

[0035] It should be noted that the film layer of the sample to be tested 18 may be at least one of a metal film and a dielectric film, and the embodiment of the present invention does not specifically limit the type of the sample to be tested 18 .

[0036] In some embodiments, the film property of the sample 18 to be tested includes the film thickness of the sample 18 to be tested.

[0037] As can be seen from the above, due to the error between the forward movement and the reverse movement of the reflector 14, there is a time offset between the forward scanning spectrum and the reverse scanning spectrum, that is, a time offset. Figure 2 , a bidirectional scanning measurement is performed on a 4000Å thick tungsten film. There is a time offset between the forward scanning spectrum (blue line) and the reverse scanning spectrum (red line). If the forward scanning spectrum and the reverse scanning spectrum are simply time aligned and smoothed, the signal peak of the generated spectrum will be broadened, such as Figure 3As shown, the forward scanning signal of the 4000Å tungsten film is shown as the blue line, and the echo signal spectrum after a simple alignment of the signal measured by the bidirectional scanning is shown as the red line. The signal peak of the echo signal is broadened compared to the forward scanning signal. Therefore, the measurement accuracy of the 4000Å tungsten film measured by bidirectional scanning will deteriorate.

[0038] In order to solve the influence of time offset, the film layer measurement method provided in an embodiment of the present invention integrates the forward scanning spectrum and the reverse scanning spectrum to generate a detection spectrum with higher measurement accuracy. In some embodiments, integrating the forward scanning spectrum and the reverse scanning spectrum to generate the detection spectrum includes: compensating the forward scanning spectrum or the reverse scanning spectrum to time-align the forward scanning spectrum and the reverse scanning spectrum; averaging the time-aligned forward scanning spectrum and reverse scanning spectrum to obtain the detection spectrum.

[0039] In some embodiments, 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 corresponding relationship between the measurement state and the time offset; based on the corresponding relationship 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 for the forward scanning spectrum or the reverse scanning spectrum.

[0040] In some embodiments, the measurement state includes the operating state of the retroreflector 14 or the film state of the sample to be measured 18, wherein the operating state includes the moving speed and acceleration of the retroreflector 14, and the film state includes the film material and the film thickness. It should be noted that there are multiple combinations of different film materials and different film thicknesses, and each combination is a film state.

[0041] In some embodiments, 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 characteristic peak of the signal in the forward scanning spectrum, and determining a second time point corresponding to a corresponding characteristic peak of the signal in the reverse scanning spectrum, wherein the difference between the first time point and the second time point is the time offset.

[0042] In some embodiments, reference Figure 2 and Figure 4 , the signal characteristic peak is the zero point extreme value signal, the photothermal signal peak or the echo signal peak.

[0043] In some embodiments, the signal characteristic peak of the forward scanning spectrum and the signal characteristic peak of the reverse scanning spectrum can be calculated by a fitting peak finding algorithm, and the difference can be taken to obtain the time offset.

[0044] Figure 5When the sample 18 to be tested is a 4000Å tungsten film, a schematic diagram of a bidirectional scanning spectrum after the forward scanning spectrum is compensated by the compensation method provided by an embodiment of the present invention, Figure 5 In the figure, the reverse scanning spectrum and the compensated forward scanning spectrum basically overlap, and the time scale consistency is high.

[0045] The following are examples of the two compensation methods provided in the above embodiments of the present invention. Figure 6 The first method is to obtain in advance the time offset between the forward scanning spectrum and the reverse scanning spectrum of the retroreflector 14 under different operating conditions, and use the time offset to compensate, referring to Figure 7 ,The second method is to pre-acquire the time offset between the forward scanning spectrum and the reverse scanning spectrum under different ,film states, and use the time offset for compensation.

[0046] Method 1 is as follows: Since the return error of the reflector 14 is different in different operating states, the time offset between the forward scanning spectrum and the reverse scanning spectrum in different operating states is different. Based on this, it is necessary to pre-measure and establish a relationship table between different operating states and time offsets. During actual measurement, the corresponding time offset can be found and compensated according to the actual operating state of the reflector 14 to obtain time-aligned forward scanning spectrum and reverse scanning spectrum.

[0047] Method 2 is as follows: measure the sample 18 to be tested with different film layer states, establish a relationship table between different film layer states and time offsets, and during actual measurement, find the corresponding time offset in the relationship table according to the film layer state for compensation to obtain time-aligned forward scanning spectrum and reverse scanning spectrum.

[0048] The film layer measurement method provided in the embodiment of the present invention is used to perform bidirectional scanning measurement on a tungsten film with a thickness of 100Å. The forward scanning spectrum and the reverse scanning spectrum before compensation are as follows: Figure 8 As shown, there is a time offset between the two. By using the primary echo signal of the acoustic wave as the signal characteristic peak for compensation alignment, the following can be obtained: Fig. 9 The time scales shown are aligned for the forward and reverse scan spectra.

[0049] The present invention solves the problem of time error between the forward scanning spectrum and the reverse scanning spectrum caused by the return error of the reciprocating motion of the reflector, and realizes a film layer measurement technology with bidirectional motion and rapid scanning, which is beneficial to improving measurement efficiency, reducing measurement signal noise, improving the signal-to-noise ratio of the measurement photoacoustic signal, and ensuring high measurement accuracy.

[0050] Another aspect of the invention provides a film layer measuring device, comprising: a light source, a retroreflector, a signal receiver and a signal processing module. Specifically, reference may be made to the film layer measuring device provided in the above embodiment, which will not be described in detail here.

[0051] In some embodiments, 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 a detection spectrum.

[0052] In some embodiments, 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 using the time offset to be compensated.

[0053] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0054] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in 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; The forward scanning spectrum and the reverse scanning spectrum are integrated to generate a detection spectrum, and the film properties of the sample to be tested are obtained based on the detection spectrum.

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: 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; The time-aligned forward scan spectrum and reverse scan spectrum are averaged to obtain the detection spectrum.

4. The film layer measurement method according to claim 3, characterized in that: 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.

5. The film layer measurement method according to claim 4, 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.

6. The film layer measurement method according to claim 4, 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.

7. The film layer measurement method according to claim 6, characterized in that: The signal characteristic peak is a zero point extreme value signal, a photothermal signal peak or an echo signal peak.

8. 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 is provided, 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.

9. The film layer measuring device according to claim 8, characterized in that: 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.

10. The film layer measuring device according to claim 9, characterized in that: 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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