Nondestructive testing device and method for multilayer film structure

Abstract

The invention belongs to the technical field of thin film structure detection, and particularly discloses a nondestructive detection device and method for a multi-layer thin film structure. The device comprises a three-dimensional imaging detection module, a beam splitter, and a broadband light source unit, a reference arm, a sample arm and a spectral measurement unit which are arranged around the beam splitter according to a preset light path, the beam splitter divides a linear light beam emitted by the broadband light source unit into two light beams, one light beam scans the multilayer film structure to be measured through the sample arm to form signal light, and the other light beam passes through the reference arm to form reference light; the spectral measurement unit collects reference light and signal light of each sampling point of each layer of structure of the multi-layer thin film structure to be measured in the scanning process of the sample arm, and generates corresponding interference spectral information; and the three-dimensional imaging detection module performs three-dimensional imaging detection on the multi-layer thin film structure to be detected based on the obtained interference spectrum information of all the sampling points. According to the invention, the spatial resolution of multilayer film structure detection can be improved while a nondestructive detection effect is realized.

Description

Technical Field

[0001] The present application belongs to the technical field of thin film structure detection, and more specifically, relates to a non-destructive detection device and method for a multi-layer thin film structure. Background Art

[0002] Multilayer thin film structures are important functional materials in modern industry, and their application scope covers semiconductors, optoelectronics, new energy, biomedicine and other fields. With the continuous development of manufacturing technology, thin film devices are developing towards high performance, miniaturization and multi-function, which puts higher requirements on the quality inspection of thin film structures.

[0003] At present, among the existing multilayer thin film structure detection methods, bright field / dark field microscopy is the most basic surface detection method. Although it is simple to operate, it can only observe the surface morphology of thin film samples and cannot obtain internal hierarchical structure information; although the transmission electron microscope (TEM) can observe the cross-sectional structure of the film, it needs to prepare extremely thin sample slices, which is destructive to the thin film sample; although ultrasonic testing can provide internal information of the sample, it usually requires coupling agents and may also contaminate or damage the thin film sample. In addition, due to the wavelength limitation of the sound wave, its spatial resolution is difficult to reach the micrometer level. The above methods play an important role in the field of thin film detection, but they all have certain limitations, especially in the non-destructive and high-resolution imaging of complex multilayer thin film structures, which still needs to be broken through.

[0004] Therefore, how to better realize the detection of multi-layer thin film structures has become a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to better realize the detection of multi-layer thin film structures, aiming to solve the problems of low spatial resolution and damage to thin film samples in the existing multi-layer thin film structure detection methods.

[0006] To achieve the above objectives, in a first aspect, the present application provides a multi-layer thin film structure nondestructive testing device, comprising:

[0007] A three-dimensional imaging detection module, a beam splitter, and a broadband light source unit, a reference arm, a sample arm and a spectrum measurement unit arranged around the beam splitter according to a preset optical path; the three-dimensional imaging detection module is connected to the spectrum measurement unit; the optical path formed by the broadband light source unit, the reference arm and the sample arm is used to form a detection line beam on the surface of the multilayer thin film structure to be measured and the reference surface in the reference arm;

[0008] The beam splitter is used to split the line beam emitted by the broadband light source unit into two line beams, wherein one line beam passes through the sample arm to scan the multilayer thin film structure to be measured to form signal light at each sampling point on the line beam, and the other line beam passes through the reference arm to form reference light at each sampling point;

[0009] The spectrum measurement unit is used to collect reference light and signal light of each sampling point on the line light beam of each layer of the multilayer thin film structure to be measured during the scanning process of the sample arm, and generate corresponding interference spectrum information;

[0010] The three-dimensional imaging detection module is used to perform three-dimensional imaging detection on the multi-layer thin film structure to be detected based on the interference spectrum information of all the sampling points obtained.

[0011] Optionally, the sample arm includes an objective lens and a displacement lifting platform for fixing the multi-layer film structure to be tested, which are arranged in sequence; the three-dimensional imaging detection module is connected to the displacement lifting platform;

[0012] The objective lens is used to obtain the signal light of the sampling point on the multi-layer thin film structure to be measured;

[0013] The displacement lifting platform is used to adjust the scanning position of the multi-layer thin film structure to be tested under the control of the three-dimensional imaging detection module to form signal light of each sampling point of each layer of the multi-layer thin film structure to be tested.

[0014] Optionally, the spectrum measurement unit comprises a mirror assembly and an imaging spectrometer arranged in sequence;

[0015] The mirror group is used to form a primary imaging optical path with the objective lens, so as to perform primary imaging at the entrance of the imaging spectrometer using the reference light and the signal light of each sampling point;

[0016] The imaging spectrometer is used to obtain interference spectrum information corresponding to the primary imaging information transmitted by the mirror group.

[0017] Optionally, the imaging spectrometer comprises an incident slit, a collimating beam expander, a diffraction grating, a focusing lens group and a two-dimensional array detector which are arranged in sequence;

[0018] The incident slit is used to limit stray light irrelevant to the primary imaging information from entering the imaging spectrometer;

[0019] The collimating beam expander is used to collimate the reference light and the signal light beams after passing through the incident slit in the horizontal direction;

[0020] The diffraction grating is used to diffract and disperse the parallel beam of reference light and the parallel beam of signal light transmitted by the collimating beam expander.

[0021] The focusing lens group is used to focus the light of different wavelengths transmitted by the diffraction grating onto the two-dimensional array detector to form a spectral image, and to compensate for the optical aberration of the spectral image, and to control the size of the spectral image by setting the effective focal length;

[0022] The two-dimensional array detector is used to obtain interference spectrum information of the spectrum image in multiple fields of view.

[0023] Optionally, the focusing lens group includes three bi-epoxy lenses arranged in sequence, and the optical focal lengths of the three bi-epoxy lenses are positive, negative, and positive in sequence.

[0024] Optionally, the reference arm comprises an achromatic lens, an attenuation plate and a reference mirror which are arranged in sequence; the reference mirror is fixed in position;

[0025] The achromatic lens is used to form a focused reference line spot on the reference mirror and compensate for the dispersion of the broadband light source;

[0026] The attenuation plate is used to attenuate the light intensity of the light beam transmitted from the achromatic lens, so as to weaken the light intensity of the reference arm, so that the light intensity of the reference arm and the light intensity of the sample arm can be matched;

[0027] The reference mirror is used to reflect the light beam transmitted from the attenuation plate to form reference light for each sampling point of each layer of the multi-layer thin film structure to be measured.

[0028] Optionally, the broadband light source unit comprises a broadband light source, a fiber collimator and a cylindrical lens which are arranged in sequence;

[0029] Broadband light sources are used to provide light sources in the target spectral range;

[0030] The optical fiber collimator is used to collimate and adjust the light beam transmitted from the broadband light source;

[0031] The cylindrical lens is used to shape the collimated light beam transmitted from the optical fiber collimator to form a line light beam, so as to transmit the line light beam to the beam splitter.

[0032] In a second aspect, the present application provides a detection method applied to any of the aforementioned nondestructive detection devices for multilayer thin film structures, comprising:

[0033] Obtaining interference spectrum information of each sampling point of each layer of the multi-layer thin film structure to be measured;

[0034] Generate three-dimensional tomographic image data with reflection intensity information based on the interference spectrum information of each sampling point;

[0035] Determine the reflection intensity scanning information corresponding to each sampling point based on the three-dimensional tomography image data of each sampling point;

[0036] The reflection intensity scanning information corresponding to each sampling point is used to perform three-dimensional imaging detection on the multi-layer thin film structure to be tested.

[0037] Optionally, the multi-layer thin film structure to be tested is a flexible printed circuit board, and the three-dimensional imaging detection of the multi-layer thin film structure to be tested is performed using the reflection intensity scanning information corresponding to each sampling point, including:

[0038] Based on the reflection intensity scanning information corresponding to each sampling point of each layer structure of the flexible printed circuit board, determining the maximum reflection intensity information and the second maximum reflection intensity information of the reflection intensity scanning information corresponding to each sampling point within the target depth interval;

[0039] Determine the height map data corresponding to each sampling point based on the maximum reflection intensity information and the second maximum reflection intensity information corresponding to each sampling point;

[0040] A three-dimensional point cloud image of the flexible printed circuit board is generated by using the height map data and the spatial plane coordinates corresponding to each sampling point, so as to perform structural defect detection on each layer structure of the flexible printed circuit board.

[0041] Optionally, the multi-layer thin film structure to be tested is a display screen; the three-dimensional imaging detection of the multi-layer thin film structure to be tested is performed using the reflection intensity scanning information corresponding to each sampling point, including:

[0042] Performing Gaussian filtering on the reflection intensity scanning information corresponding to each sampling point of each layer structure of the display screen to obtain each processed reflection intensity scanning information;

[0043] Based on each of the processed reflection intensity scanning information, determining the interface positioning imaging results of each layer structure of the display screen;

[0044] Interface defect detection is performed on each layer structure of the display screen according to the interface positioning imaging result.

[0045] In general, the above technical solutions provided by this application have the following beneficial effects compared with the prior art:

[0046] The present application provides a device and method for nondestructive testing of a multilayer thin film structure. The device includes a three-dimensional imaging detection module, a beam splitter, and a broadband light source unit, a reference arm, a sample arm, and a spectral measurement unit arranged around the beam splitter. By adopting spectral domain optical coherence tomography, the introduced broadband light source, the sample arm, and the reference arm are used to perform linear scanning detection on the multilayer thin film structure to be tested, so that the reference arm can provide linear reference light with a wide spectral range, and the sample arm can scan the multilayer thin film structure to be tested to provide linear signal light with a wide spectral range. In combination with the spectral information of the interference signal of the reference arm reference light and the sample arm signal light captured in real time by the spectral measurement unit, more detailed information about the inside of the multilayer thin film structure to be tested can be quickly captured, and a high-quality three-dimensional image can be generated for detection. The reflection depth in the multilayer thin film structure sample is determined by Fourier transforming the spectral domain interference signal, so that a spatial resolution of micrometer level can be achieved. While achieving a non-contact rapid nondestructive testing effect, the spatial resolution of the multilayer thin film structure detection is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is one of the structural schematic diagrams of the multilayer thin film structure nondestructive testing device provided in the embodiment of the present application;

[0048] Figure 2 This is the second structural schematic diagram of the multilayer thin film structure nondestructive testing device provided in the embodiment of the present application;

[0049] Figure 3 is a schematic diagram of the structure of an imaging spectrometer provided in an embodiment of the present application;

[0050] Figure 4 It is a flow chart of a detection method of a multilayer thin film structure nondestructive detection device provided in an embodiment of the present application;

[0051] Figure 5 (a) is a schematic diagram of the optical path of the device provided in the embodiment of the present application scanning the metal pad on the FPC; (b) is a schematic diagram of the optical path of the device provided in the embodiment of the present application scanning the solder resist layer on the FPC without buried wires; (c) is a schematic diagram of the optical path of the device provided in the embodiment of the present application scanning the solder resist layer on the FPC with buried wires;

[0052] Figure 6 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application.

[0053] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0054] 1 is a three-dimensional imaging detection module; 2 is a beam splitter; 3 is a broadband light source unit; 31 is a broadband light source; 32 is a fiber collimator; 33 is a cylindrical lens; 4 is a reference arm; 41 is an achromatic lens; 42 is an attenuation plate; 43 is a reference mirror; 5 is a sample arm; 51 is an objective lens; 52 is a displacement lifting platform; 521 is a displacement platform; 522 is a lifting platform; 6 is a spectrum measurement unit; 61 is a mirror group; 62 is an imaging spectrometer; 621 is an incident slit; 622 is a collimating beam expander; 623 is a diffraction grating; 624 is a focusing lens group; 625 is a two-dimensional array detector; 6241 is a double-gel lens; 6242 is a double-gel lens; 6243 is a double-gel lens. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0056] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0057] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more than two. For example, multiple processing units refer to two or more processing units, etc.; multiple elements refer to two or more elements, etc.

[0058] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0059] Figure 1 is one of the structural schematic diagrams of the multilayer thin film structure nondestructive testing device provided in the embodiment of the present application, such as Figure 1 As shown, the device comprises:

[0060] A three-dimensional imaging detection module 1, a beam splitter 2, and a broadband light source unit 3, a reference arm 4, a sample arm 5 and a spectrum measurement unit 6 arranged around the beam splitter 2 according to a preset optical path; the three-dimensional imaging detection module 1 is connected to the spectrum measurement unit 6; the optical path formed by the broadband light source unit, the reference arm and the sample arm is used to form a detection line beam on the surface of the multilayer thin film structure to be tested and the reference surface in the reference arm;

[0061] The beam splitter 2 is used to split the line beam emitted by the broadband light source unit 3 into two line beams, wherein one line beam scans the multilayer thin film structure to be measured through the sample arm 5 to form a signal light of each sampling point on the line beam, and the other line beam passes through the reference arm 4 to form a reference light of each sampling point;

[0062] The spectrum measurement unit 6 is used to collect reference light and signal light at each sampling point on the line light beam of each layer of the multilayer thin film structure to be measured during the scanning process of the sample arm 5, and generate corresponding interference spectrum information;

[0063] The three-dimensional imaging detection module 1 is used to perform three-dimensional imaging detection on the multi-layer thin film structure to be detected based on the interference spectrum information of all sampling points obtained.

[0064] Specifically, in an embodiment of the present application, a broadband light source unit can provide a linear light source beam with a wide spectral range. The broadband light source unit, reference arm, sample arm and spectral measurement unit are arranged around the beam splitter according to a pre-designed optical path, so that the light outlet of the broadband light source unit is aligned with one side of the beam splitter, the light inlets of the reference arm and the sample arm are respectively aligned with the light outlets of the two split light beams of the beam splitter, and the light inlet of the spectral measurement unit is aligned with the light outlet on the other side of the beam splitter, so that the multi-wavelength line beam emitted by the broadband light source unit is divided into two line beams after passing through the beam splitter and transmitted to the reference arm and the sample arm respectively.

[0065] Among them, the broadband light source unit, the reference arm and the sample arm all have the function of beam shaping, and the optical path formed by the three can form a detection line beam on the surface of the multilayer thin film structure to be measured and the reference surface in the reference arm.

[0066] Among them, one beam of line light can enter the sample arm, and by controlling the sample arm, the multi-wavelength light beam can penetrate the multi-layer thin film structure to be tested, and a tomographic scan is performed on the multi-layer thin film structure to be tested, and a wide spectral range signal light for each sampling point on the line light beam is formed through scattering of the multi-layer thin film structure to be tested; the other beam of line light can enter the reference arm, and after reflection inside the reference arm, a wide spectral range reference light for each sampling point on the line light beam is formed.

[0067] In the embodiments of the present application, the multilayer film structure to be tested refers to a multilayer film structure sample for structural testing, which can be arranged in a sample arm, and can specifically include various transparent or translucent multilayer film materials, such as a flexible printed circuit board (Flexible Printed Circuit, FPC), a liquid crystal display (Liquid Crystal Display, LCD), and the like.

[0068] Optionally, the reference arm and the sample arm can be structurally symmetrical, which can reduce the phase mismatch problem caused by the dispersion mismatch between the two arms, reduce the broadening of the signal in the spectral domain, and improve the accuracy of depth measurement in subsequent three-dimensional imaging detection of thin film structures.

[0069] Furthermore, the reference light and signal light of each sampling point on the line light beam of the multilayer thin film structure to be tested are collected in real time, and the reference light and signal light of each sampling point on each detection line light beam are coherently superimposed through the internal spectral measurement optical path structure to generate the interference spectrum information corresponding to each sampling point, thereby capturing the detailed information inside the multilayer thin film structure to be tested.

[0070] Furthermore, by connecting with the three-dimensional imaging detection module, the spectral measurement unit can send the interference spectrum information of each sampling point generated in real time to the three-dimensional imaging detection module for processing, and perform three-dimensional imaging analysis and structural detection on each layer of the multi-layer thin film structure to be tested through the three-dimensional imaging detection module.

[0071] It should be noted that, in addition to performing nondestructive tomographic testing on multilayer thin film structures, the device of the embodiment of the present application can also measure the three-dimensional surface morphology of general objects.

[0072] The multilayer thin film structure nondestructive testing device of the embodiment of the present application includes a three-dimensional imaging detection module, a beam splitter, and a broadband light source unit, a reference arm, a sample arm and a spectral measurement unit arranged around the beam splitter. By adopting spectral domain optical coherence tomography, the introduced broadband light source, the sample arm and the reference arm are used to perform linear scanning detection on the multilayer thin film structure to be tested, so that the reference arm can provide linear reference light with a wide spectral range, and the sample arm can scan the multilayer thin film structure to be tested to provide linear signal light with a wide spectral range. In combination with the spectral information of the interference signal between the reference light of the reference arm and the signal light of the sample arm captured in real time by the spectral measurement unit, more detailed information about the inside of the multilayer thin film structure to be tested can be quickly captured, and a high-quality three-dimensional image can be generated for detection. Interference is used to determine the depth of reflection of photons in the multilayer thin film structure sample, and a spatial resolution of micrometer level can be achieved. While achieving a non-contact rapid nondestructive testing effect, the spatial resolution of the multilayer thin film structure detection is improved.

[0073] Figure 2 This is the second structural schematic diagram of the multilayer thin film structure nondestructive testing device provided in the embodiment of the present application, such as Figure 2 As shown, in the embodiment of the present application, the broadband light source unit 3 may include a broadband light source 31, a fiber collimator 32 and a cylindrical lens 33 which are arranged in sequence;

[0074] The broadband light source 31 is used to provide a light source in a target spectral range;

[0075] The optical fiber collimator 32 is used to collimate the light beam transmitted from the broadband light source;

[0076] The cylindrical lens 33 is used to shape the collimated light beam transmitted from the optical fiber collimator to form a linear light beam, so as to transmit the linear light beam to the beam splitter.

[0077] Specifically, in the embodiments of the present application, the broadband light source unit can use a broadband light source, such as a SLED broadband light source and an ultra-broadband light source, which has the characteristics of wide spectrum, weak temporal coherence, high power and high efficiency, and is widely used in the fields of optical sensing, biomedical imaging, etc. Among them, the spectral bandwidth of the SLED broadband light source is usually within the target spectral range of 6nm to 100nm, while the ultra-broadband light source can achieve a continuous spectral output of more than 400nm.

[0078] In the embodiments of the present application, the main function of the fiber collimator is to collimate the light beam emitted by the broadband light source through the optical fiber so that it can be more accurately received and processed by other optical elements.

[0079] In the embodiment of the present application, the cylindrical lens has the characteristics of unidirectional focusing and divergence, and can focus parallel incident light onto a line. Arranging a cylindrical lens behind a broadband light source can shape the collimated light beam transmitted by the fiber collimator to form a line beam to meet the needs of the device for linear beam detection.

[0080] It should be noted that in the embodiments of the present application, the broadband light source unit can provide continuous low-coherence light within a certain wavelength range. Along the direction of the outgoing light beam of the broadband light source unit, in the vertical direction, the light (such as Figure 2 The dotted part of the light (shown in the figure) will be refracted by the lens in the broadband light source unit, thereby changing its propagation direction and focusing the light. In the horizontal direction, the cylindrical lens will not deflect the light, because the refractive power of the cylindrical lens is mainly concentrated in the vertical direction where its curvature radius is located, and there is no refractive power in the horizontal direction. Therefore, the light maintains the original transmission direction.

[0081] The device of the embodiment of the present application constructs a broadband light source unit by utilizing a broadband light source, a fiber collimator and a cylindrical lens, which can improve the light beam signal transmission quality and efficiency of the light source used for thin film scanning detection. At the same time, the shaping of the light source beam is beneficial to improving the quality of subsequent thin film sample scanning imaging.

[0082] It should be noted that if Figure 2 As shown, in the embodiment of the present application, by introducing a reflector, the optical path can be folded, the volume of the system can be compressed, and the miniaturization of the measurement system can be achieved.

[0083] Continue to refer to Figure 2In the embodiment of the present application, the sample arm 5 includes an objective lens 51 arranged in sequence, and a displacement lifting platform 52 for fixing the multi-layer film structure to be tested; the three-dimensional imaging detection module 1 is connected to the displacement lifting platform 52;

[0084] The objective lens 51 is used to obtain the signal light of the sampling point on the multi-layer thin film structure to be measured;

[0085] The displacement lifting platform 52 is used to adjust the scanning position of the multi-layer thin film structure to be tested under the control of the three-dimensional imaging detection module 1 to form signal light of each sampling point of each layer of the multi-layer thin film structure to be tested.

[0086] Specifically, in the embodiment of the present application, the displacement lifting platform 52 may include a displacement platform 521 for moving the multi-layer thin film structure to be tested on an XY plane and a lifting platform 522 for moving the multi-layer thin film structure to be tested on a Z axis.

[0087] In an embodiment of the present application, during the scanning process performed by the sample arm, the objective lens first guides the aforementioned other light beam transmitted by the beam splitter to irradiate the multilayer thin film structure sample to be tested set on the displacement lifting platform, and the signal light is formed by reflection of the light on the sample surface. The objective lens can obtain the signal light of the sampling point on the multilayer thin film structure to be tested.

[0088] Furthermore, in an embodiment of the present application, the displacement lifting platform adjusts the scanning position of the multilayer thin film structure to be tested under the control of the three-dimensional imaging detection module. Specifically, through the control of the three-dimensional imaging detection module, the test area of ​​the multilayer thin film structure to be tested can be moved to the scanning field of view. At the same time, by controlling the Z-axis lifting platform, the position of the outer surface of the multilayer thin film structure sample to be tested is moved to a position with a positive optical path difference near the focal plane of the system, and the autocorrelation signal is avoided. Then, by controlling the displacement platform of the XY plane to move the multilayer thin film structure to be tested in a specific direction, optical scanning of the multilayer thin film structure to be tested is realized, and the signal light of each sampling point of each layer of the multilayer thin film structure to be tested is formed by the scanning signal.

[0089] The device of the embodiment of the present application uses a translation stage to scan a multilayer thin film structure sample, thereby ensuring the accuracy of the depth between different B-Scan signals in the scanning signal.

[0090] Reference Figure 2 In the embodiment of the present application, the reference arm 4 includes an achromatic lens 41, an attenuation plate 42 and a reference mirror 43 which are arranged in sequence; the reference mirror 43 is fixed in position;

[0091] The achromatic lens 41 is used to form a focused reference line spot on the reference mirror 43 and compensate for the dispersion of the broadband light source;

[0092] The attenuation plate 42 is used to attenuate the light intensity of the light beam transmitted from the achromatic lens 41, so as to weaken the light intensity of the reference arm and make the light intensity of the reference arm and the sample arm match;

[0093] The reference mirror 43 is used to reflect the light beam transmitted from the attenuation plate 42 to form reference light for each sampling point of each layer of the multi-layer thin film structure to be measured.

[0094] Specifically, in the embodiment of the present application, a second achromatic lens, an attenuation plate and a reference mirror arranged in sequence can be used to build a reference arm. The achromatic lens is mainly used to form a focused reference line spot on the reference mirror, while compensating for the dispersion of the broadband light source to improve the subsequent imaging quality.

[0095] Furthermore, the attenuation plate is used to attenuate the light intensity of the light beam transmitted from the achromatic lens to weaken the light intensity of the reference arm so that the light intensity of the reference arm and the sample arm can be matched.

[0096] The reference mirror is mainly used to reflect the light in the reference optical path, reflect the light beam transmitted by the attenuation plate, and form a reference light to interfere with the signal light reflected from the multilayer thin film structure sample. The reference mirror provides a reflection optical path with a known path length, so that the device can accurately measure the reflected light at different depths in the sample and generate a high-resolution cross-sectional image based on it. It should be noted that the general spectral domain optical coherence tomography (SD-OCT) system adjusts the optical path difference between the two arms by adjusting the position of the reference mirror.

[0097] Unlike the traditional structure, in the embodiment of the present application, by fixing the position of the reference mirror, the mechanical structure for adjusting the optical path difference between the reference arm and the sample arm is placed on the sample arm, so that the spectrum generated by the reference mirror in the imaging spectrometer remains unchanged. This setting makes the spectral calibration result stable, and light of the same wavelength will always interfere at a fixed position on the image plane without shifting, thereby further improving the subsequent scanning imaging quality.

[0098] Continue to refer to Figure 2 and Figure 3 As shown, in the embodiment of the present application, the spectrum measurement unit 6 may include a mirror group 61 and an imaging spectrometer 62 which are arranged in sequence;

[0099] The lens group 61 is used to form a primary imaging optical path with the objective lens 51, so as to perform primary imaging at the entrance of the imaging spectrometer using the reference light and the signal light of each sampling point;

[0100] The imaging spectrometer 62 is used to obtain interference spectrum information corresponding to the primary imaging information transmitted by the mirror group 61 .

[0101] Specifically, in an embodiment of the present application, the spectral measurement unit may be composed of a mirror group and an imaging spectrometer. Among them, the mirror group is arranged in front of the imaging spectrometer. On the one hand, it can receive the reference light and signal light transmitted from the beam splitter, and sort the two types of light beams through its lens combination to meet the requirements of the spectrometer for light beams; on the other hand, it can image the reference light and signal light beams at the incident slit of the spectrometer, ensuring that the spectrometer can accurately capture the spectral information of the spectral domain signal in the primary imaging information. In this way, the performance of the entire spectral imaging system can be optimized, and the accuracy and reliability of the final measurement can be improved.

[0102] Figure 3 is a schematic diagram of the structure of the imaging spectrometer provided in the embodiment of the present application, such as Figure 3 As shown, the imaging spectrometer 62 includes an incident slit 621, a collimating beam expander 622, a diffraction grating 623, a focusing lens group 624 and a two-dimensional array detector 625 which are arranged in sequence;

[0103] The incident slit 621 is used to limit stray light irrelevant to primary imaging information from entering the imaging spectrometer;

[0104] The collimating beam expander 622 is used to collimate the reference light and the signal light beam adjusted by the incident slit 621 in the horizontal direction;

[0105] The diffraction grating 623 is used to diffract and disperse the parallel beam of reference light and the parallel beam of signal light transmitted from the collimating beam expander 622;

[0106] The focusing lens group 624 is used to focus the light of different wavelengths transmitted by the diffraction grating 623 onto the two-dimensional array detector 625 to form a spectral image, and to compensate for the optical aberration of the spectral image, and to control the size of the spectral image by setting the effective focal length;

[0107] The two-dimensional array detector 625 is used to obtain interference spectrum information of the spectrum image in multiple fields of view.

[0108] Specifically, in an embodiment of the present application, the imaging spectrometer may be composed of an incident slit, a collimating beam expander, a diffraction grating, a focusing lens group, and a two-dimensional array detector arranged in sequence. Among them, through the incident slit, the incident direction and width of the reference light and the signal light transmitted by the lens group can be adjusted to ensure that only light in a specific direction can pass through, thereby reducing the interference of stray light irrelevant to the primary imaging information, and by adjusting the width of the slit, the light flux entering the spectrometer can be controlled, thereby ensuring the resolution of the spectrometer.

[0109] Among them, the main function of the collimating beam expander is to collimate the reference light and signal light beams adjusted by the incident slit in the horizontal direction. Through the collimation process, the measurement accuracy and stability of the spectrometer can be significantly improved.

[0110] Among them, the diffraction grating mainly plays the role of splitting, which is used to disperse the signal light and the reference light into their respective spectral lines. In this way, the parallel beams of reference light and signal light transmitted from the collimator can be diffracted and dispersed. The performance of the diffraction grating will directly affect the spectral resolution and measurement range of the spectrometer.

[0111] The focusing lens group is mainly used to focus the light of different wavelengths transmitted by the diffraction grating onto the two-dimensional array detector to form a clear spectral image, compensate for the optical aberrations such as spherical aberration and vertical axis chromatic aberration in the spectral image, and further improve the imaging quality. And by setting the effective focal length, the size of the spectral image can be controlled;

[0112] Among them, the two-dimensional array detector is used for a two-dimensional array detector, which is a device that can detect and record the intensity of light signals. In an imaging spectrometer, it is used to receive spectral images that have been split by a diffraction grating and corrected by a focusing lens group. The detector converts the received light signal into an electrical signal, and performs data processing and analysis to obtain the interference spectrum information of the spectral image in multiple fields of view.

[0113] The device of the embodiment of the present application adopts parallel spectral domain interferometry technology on the basis of spectral domain OCT. On the one hand, by introducing a focusing lens group to balance and correct optical aberrations such as spherical aberration and vertical axis chromatic aberration in the spectral image, the imaging quality in the detection process can be greatly improved; on the other hand, through the parallel spectral domain interferometry measurement optical path structure, the interference spectrum information of multiple sampling points of the thin film sample in the line field of view can be obtained at the same time, so only one-dimensional scanning is required, which makes it faster to image and can greatly improve the scanning and measurement speed of the system.

[0114] Based on the content of the above embodiment, as an optional embodiment, the focusing lens group 624 may include three bi-gel lenses arranged in sequence, namely bi-gel lens 6241, bi-gel lens 6242 and bi-gel lens 6243, wherein the optical power of the three bi-gel lenses is positive, negative and positive in sequence. By optimizing the curvature radius and interval of the three-face lens and selecting the material, it can meet the imaging size requirements while correcting and compensating for various aberrations existing in the primary image.

[0115] Specifically, in an embodiment of the present application, three achromatic lenses (with optical power in order of positive, negative and positive) are introduced into the imaging spectrometer to replace the commonly used single lens. The added negative lens can simultaneously balance the field curvature in the spectral direction and the field of view direction, thereby further improving the imaging effect during the detection process.

[0116] It should be noted that the imaging spectrometer of the traditional line-field spectral domain OCT system, whether in the optimization of imaging performance or in spectral calibration, only assumes that the ideal point objects in different fields of view are located on the front focal plane of the collimating lens, that is, the imaging spectrometer is optimized as an independent part. However, in the actual system, the front focal plane is not an ideal point object, but a primary image produced by the sample to be tested, which will cause the system optimization results to deviate from the actual situation.

[0117] In the embodiment of the present application, the front telecentric optical path (achromatic lens 41 + lens group 61) and the rear imaging spectrometer are optimized as a complete imaging system. It should also be noted that the single-sided lens in this embodiment can actually represent a lens group, not just a single lens.

[0118] The following is a description of the detection method of the multi-layer thin film structure non-destructive detection device provided by the present application. The detection method described below and the multi-layer thin film structure non-destructive detection device described above can be referenced to each other.

[0119] Figure 4 The flowchart of the detection method of the multi-layer thin film structure non-destructive detection device provided in the embodiment of the present application can be applied to any of the aforementioned multi-layer thin film structure non-destructive detection devices. It can be understood that the execution subject of the method is a three-dimensional imaging detection module, such as Figure 4 As shown, the method includes:

[0120] Step S1, obtaining interference spectrum information of each sampling point of each layer of the multi-layer thin film structure to be measured;

[0121] Step S2, generating three-dimensional tomographic image data with reflection intensity information based on the interference spectrum information of each sampling point;

[0122] Step S3, determining the reflection intensity scanning information corresponding to each sampling point based on the three-dimensional tomography image data of each sampling point;

[0123] Step S4, using the reflection intensity scanning information corresponding to each sampling point, three-dimensional imaging detection is performed on the multi-layer thin film structure to be tested.

[0124] Specifically, in the embodiment of the present application, in step S1, the sample to be tested is fixed on the XY displacement stage, the test area of ​​the multilayer thin film structure to be tested is moved to the scanning field of view, and the sample is moved to a position with a positive optical path difference near the focal plane by controlling the Z-axis lifting stage, and the autocorrelation signal is avoided. The sample arm is used to scan the multilayer thin film structure sample to be tested in the X direction, and each step is taken to record the interference spectrum information of all sampling points in the line field, so that the three-dimensional imaging detection module can obtain the interference spectrum information of each sampling point of each layer of the multilayer thin film structure to be tested.

[0125] Furthermore, in step S2, after the scanning is completed, based on the interference spectrum information of each sampling point, the spectra of all sampling points are interpolated to the uniform wavenumber domain, and then a fast Fourier transform is performed to obtain three-dimensional tomographic image data with reflection intensity information, which can be expressed as T[i,j,γ], where i is the index of A-Scans in each B-Scans in the scanning signal, and j and γ are the indexes of B-Scans and axial depth values, respectively.

[0126] Furthermore, in step S3, the line field intensity is normalized based on the three-dimensional tomographic image data of each sampling point. Specifically, considering the uneven illumination of the line spot, in order to make the intensity threshold valid for different field points, the intensity of the three-dimensional tomographic image data must be normalized. Using the pre-measured light intensity distribution S[i] in the line field direction, find the maximum value S max , then calculate the normalization coefficient C[i] = S max / S[i]. After that, the reflection intensity distribution of the three-dimensional tomographic image data T[i,j,γ] is normalized to obtain the normalized result T n [i,j,γ]=C[i]·T[i,j,γ].

[0127] Then, by traversing all sampling points, the reflection intensity scanning information A-Scan signal corresponding to each sampling point can be determined, which can be expressed as f[z γ ]=T n [i o ,j0,γ].

[0128] Furthermore, in step S4, by using the reflection intensity scanning information A-Scan signal corresponding to each sampling point, a targeted detection strategy is adopted according to the type of the multi-layer thin film structure to be tested, and three-dimensional imaging detection is performed on the multi-layer thin film structure to be tested.

[0129] The nondestructive testing method for the multilayer thin film structure of the embodiment of the present application adopts spectral domain optical coherence tomography, utilizes a broadband light source, a sample arm and a reference arm to perform linear scanning detection on the multilayer thin film structure to be tested, uses the reference arm to provide linear reference light, and the sample arm scans the multilayer thin film structure to be tested to provide linear signal light, and utilizes a spectral measurement unit to capture the spectral information of the interference signal between the reference arm and the sample arm in real time, and can generate a two-dimensional tomographic or three-dimensional image of the inside of the multilayer thin film structure to be tested for detection without axial scanning, and can provide a spatial resolution of micrometer level, thereby achieving a non-contact and high-resolution rapid nondestructive testing effect, and can be applicable to various transparent or translucent multilayer thin film materials.

[0130] Based on the content of the above embodiment, as an optional embodiment, the multi-layer thin film structure to be tested is FPC; using the reflection intensity scanning information corresponding to each sampling point, a three-dimensional imaging detection of the multi-layer thin film structure to be tested is performed, including:

[0131] Based on the reflection intensity scanning information corresponding to each sampling point of each layer structure of the FPC, the maximum reflection intensity information and the second maximum reflection intensity information of the reflection intensity scanning information corresponding to each sampling point within the target depth interval are determined;

[0132] Based on the maximum reflection intensity information and the second maximum reflection intensity information corresponding to each sampling point, determine the height map data corresponding to each sampling point;

[0133] The height map data and spatial plane coordinates corresponding to each sampling point are used to generate a three-dimensional point cloud image of the flexible printed circuit board to detect defects in each layer structure of the FPC.

[0134] It should be noted that FPC is a typical multi-layer film structure sample. For FPC samples that only contain a solder mask layer, a conductor layer, and a base layer, the following algorithm can perform high-resolution imaging of the internal circuit structure of the FPC, which can then be used for detection and analysis, so as to early detect and correct manufacturing or process defects, such as poor welding, material stratification, and abnormal conductive paths, and provide key information for quality monitoring during the FPC manufacturing process.

[0135] Specifically, after completing the acquisition of the volume tomography image data and determining the reflection intensity scanning information A-Scan signal corresponding to each sampling point, for the scenario where the multi-layer thin film structure to be tested is FPC, the following steps are specifically performed:

[0136] Step S101, using each reflection intensity scanning information to find the maximum reflection intensity information and the second maximum reflection intensity information.

[0137] Specifically, traverse all sampling points, for each A-Scan signal: f[z γ ]=Tn [i o ,j0,γ], find the maximum peak and the sub-maximum peak in the peak-finding target depth interval including the solder mask surface and the metal conductor, that is, determine the maximum reflection intensity information f[z α ] and the submaximal reflection intensity information f[z β ].

[0138] Among them, z represents the optical path difference between the sample arm and the reference mirror, that is, the depth coordinate, which is an equally spaced array determined by the sampling rate and sampling interval in the uniform wavenumber domain; α and β are the indexes corresponding to the depth coordinates.

[0139] Step S102, performing peak analysis and height map calculation.

[0140] Specifically, in this embodiment, the surface area of ​​the FPC type is divided into two categories: the first category is the area not covered by the solder mask layer, generally the exposed pad; the second category is the area covered by the solder mask layer. The area covered by the solder mask layer is further divided into two categories according to whether there is a metal conductor underneath.

[0141] Figure 5 (a) is a schematic diagram of the optical path of the device provided in the embodiment of the present application scanning the metal pad on the FPC; (b) is a schematic diagram of the optical path of the device provided in the embodiment of the present application scanning the solder resist layer on the FPC without buried wires; (c) is a schematic diagram of the optical path of the device provided in the embodiment of the present application scanning the solder resist layer on the FPC with buried wires, such as Figure 5 As shown in (a), at the pad, due to the strong reflection of the exposed metal, a single peak with high intensity and high signal-to-noise ratio can be generated; in the remaining areas covered with the solder mask, due to the absorption of the protective layer, the signal-to-noise ratio is weaker than the former.

[0142] like Figure 5 As shown in (c) in the figure, if there is a conductor underneath, the strong reflection of the copper foil makes the A-Scan signal usually have two peaks, corresponding to the interface between the conductor and the solder mask layer and the outer surface of the solder mask layer. Figure 5 As shown in (b), the area without wires can generally only detect the reflection signal of the outer surface of the solder mask layer. According to the above analysis, for each sampling point corresponding to the maximum reflection intensity information f[z α ] and the submaximal reflection intensity information f[z β ], the following four conditions can be used to classify different situations and assign values ​​to the height map:

[0143] (1) If f[z α ]≥τ1, then H trace [i0,j0]=z α ;

[0144] (2) If τ2 <f[z α ]<τ1, then H mask [i0,j0]=z α ;

[0145] (3) If f[z β ]≥τ2,|z α -z β |∈[t min ,t max ], then H mask [i0,j0]=max{z α ,z β}, H trace [i0,j0]=min{z α ,z β};

[0146] (4) If none of the above conditions are met, it is considered an abnormal point and no record is made.

[0147] Among them, H trace and H mask They represent the height maps of the upper surface of the internal circuit of the FPC and the outer surface of the solder mask layer, respectively. η represents the minimum threshold ratio of the two peaks at the same order of magnitude. τ1 represents the minimum reflection intensity threshold of the pad metal. τ2 represents the minimum reflection intensity threshold classified as a reflection peak rather than noise. [t min ,t max ] indicates the range of optical path difference between the solder mask surface and the conductor upper surface. The above parameters can be determined by experimental data.

[0148] Step S103, calculating the sub-pixel height value.

[0149] Specifically, in order to make the height extraction more accurate, the Energy Center of Gravity Method (ECCM) is used to recalculate the sub-pixel height value in the A-Scan signal corresponding to each sampling point on the height map, rather than directly taking the discrete height value. The process can be specifically expressed as:

[0150]

[0151] Among them, the value of d is generally 2.

[0152] Step S104, generating a three-dimensional point cloud image.

[0153] Specifically, according to the known scanning step length and actual lateral resolution of the system, the spatial plane coordinates in the real space, that is, the X and Y coordinate values, are assigned to each sampling data point, combined with the depth information calculated in step S103. A 3D point cloud image of each layer of the FPC structure can be generated. During the process, the point cloud denoising algorithm is used to filter out noise points, and by changing the position of the XY translation stage and repeating the scanning operation, the topographic information between FPC regions can be finally spliced.

[0154] Step S105, performing structural defect detection on each layer structure of the FPC.

[0155] After obtaining the FPC visual internal circuit diagram, we can combine manual screening, traditional image processing, machine learning, or collect a sufficient amount of data sets to use deep learning to perform FPC quality inspection and check whether there are structural defects in the FPC multi-layer structure.

[0156] The method of the embodiment of the present application uses the reflection intensity scanning information corresponding to each sampling point of each layer structure of the FPC to perform reflection intensity peak analysis, and obtains the height map data corresponding to each sampling point to generate a three-dimensional point cloud image of each layer structure of the FPC. This can effectively realize the quality inspection of each layer structure of the FPC, with good imaging quality and high detection efficiency.

[0157] Based on the content of the above embodiment, as an optional embodiment, the multi-layer thin film structure to be tested is a display screen; using the reflection intensity scanning information corresponding to each sampling point, a three-dimensional imaging detection of the multi-layer thin film structure to be tested is performed, including:

[0158] Performing Gaussian filtering on the reflection intensity scanning information corresponding to each sampling point of each layer structure of the display screen to obtain each processed reflection intensity scanning information;

[0159] Based on each processed reflection intensity scanning information, determining the interface positioning imaging results of each layer structure of the display screen;

[0160] Interface defect detection is performed on each layer structure of the display screen based on the interface positioning imaging results.

[0161] Specifically, in the embodiment of the present application, after the acquisition of the volume tomography image data is completed and the reflection intensity scanning information A-Scan signal corresponding to each sampling point is determined, the following steps are specifically performed for the scenario where the multi-layer thin film structure to be measured is a display screen:

[0162] Step S201, performing signal preprocessing.

[0163] Specifically, after acquiring the volume tomography image data, assuming that the i-th A-Scan signal is represented by A i (z), that is, A i(z) = f[z γ ]=T n [i o ,j0,γ].

[0164] Where z represents the coordinate in the depth direction, i = 1, 2, 3, ..., N, where N is the number of sampling points. Gaussian filtering is performed on each A-Scan signal, and each processed reflection intensity scan information S i (z), namely:

[0165] S i (z) = A i (z)*G(z,σ);

[0166] Among them, G(z,σ) is the Gaussian kernel function, which can be expressed as

[0167]

[0168] Step S202, performing interface positioning.

[0169] Specifically, according to the following formula, the preprocessed signal S i (z) Perform peak detection, that is:

[0170]

[0171] Among them, P i is the peak position set detected in the i-th A-Scan signal, and λ represents the threshold coefficient.

[0172] Step S203: performing multi-signal fusion.

[0173] Specifically, the peak positions of different A-Scans are clustered and fused. The process can be expressed as:

[0174] D j,k =|P j -P k |,j,k∈[1,N]

[0175] When D j,k <δ, they are considered to belong to the same interface, where δ is the distance threshold.

[0176] According to the above formula, the interface positioning imaging results of each layer structure of the display screen can be determined.

[0177] Furthermore, in step S204, layer characteristic analysis is performed to determine thickness parameters.

[0178] Specifically, for the layer structure composed of two adjacent interfaces, its thickness T is defined as m :

[0179]

[0180] in, represents the average value of the mth interface depth.

[0181] The smoothness estimation function F of the interface m m It can be expressed as:

[0182]

[0183] The uniformity evaluation function of interface m can be expressed as:

[0184]

[0185] Step S205, performing interface defect detection to determine defects.

[0186] The defect feature vector can be defined as:

[0187] V m =[E m ,U m ,T m ];

[0188] When any of the following conditions is met, it can be determined that the interface m has defects, namely:

[0189] F m >F threshold ;

[0190] U m >U threshold ;

[0191] |T m -T ref |>T threshold ;

[0192] Among them, F threshold , U threshold and T threshold They are respectively expressed as a flatness estimation function threshold, a uniformity evaluation function threshold and a thickness threshold, which can be specifically determined according to the structural parameters of the display screen actually measured.

[0193] The method of the embodiment of the present application performs Gaussian filtering on the reflection intensity scanning information corresponding to each sampling point of each layer structure of the display screen, and performs interface positioning imaging of each layer structure of the display screen according to the processed reflection intensity scanning information, so as to perform quality inspection on each layer structure of the display screen. This can effectively realize quality inspection of each layer structure of the display screen, with good imaging quality and high inspection efficiency.

[0194] Based on the method in the above embodiment, the embodiment of the present application provides an electronic device, such as Figure 6 As shown, the electronic device may include: a processor (Processor) 610, a communication interface (CommunicationsInterface) 620, a memory (Memory) 630 and a communication bus 640, wherein the processor 610, the communication interface 620, and the memory 630 communicate with each other through the communication bus 640. The processor 610 may call the logic instructions in the memory 630 to execute the method in the above embodiment.

[0195] In addition, the logic instructions in the above-mentioned memory 630 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application.

[0196] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0197] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0198] It is understandable that the processor in the embodiment of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0199] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0200] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions may be transmitted from a website site, a computer, a server or a data center to another website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or a data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

[0201] It should be understood that the various numerical numbers involved in the embodiments of the present application are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0202] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0203] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, 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 embodiments of the present application.

[0204] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0205] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A nondestructive testing device for a multilayer thin film structure, characterized in that: include: A three-dimensional imaging detection module, a beam splitter, and a broadband light source unit, a reference arm, a sample arm and a spectrum measurement unit arranged around the beam splitter according to a preset optical path; The three-dimensional imaging detection module is connected to the spectrum measurement unit; the optical path formed by the broadband light source unit, the reference arm and the sample arm is used to form a detection line beam on the surface of the multilayer thin film structure to be measured and the reference surface in the reference arm; The beam splitter is used to split the line beam emitted by the broadband light source unit into two line beams, wherein one line beam passes through the sample arm to scan the multilayer thin film structure to be measured to form signal light at each sampling point on the line beam, and the other line beam passes through the reference arm to form reference light at each sampling point; The spectrum measurement unit is used to collect reference light and signal light of each sampling point on the line light beam of each layer of the multilayer thin film structure to be measured during the scanning process of the sample arm, and generate corresponding interference spectrum information; The three-dimensional imaging detection module is used to perform three-dimensional imaging detection on the multi-layer thin film structure to be detected based on the interference spectrum information of all the sampling points obtained.

2. The nondestructive testing device for multilayer thin film structure according to claim 1, characterized in that: The sample arm includes an objective lens and a displacement lifting platform for fixing the multi-layer film structure to be tested, which are arranged in sequence; the three-dimensional imaging detection module is connected to the displacement lifting platform; The objective lens is used to obtain the signal light of the sampling point on the multi-layer thin film structure to be measured; The displacement lifting platform is used to adjust the scanning position of the multi-layer thin film structure to be tested under the control of the three-dimensional imaging detection module to form signal light of each sampling point of each layer of the multi-layer thin film structure to be tested.

3. The nondestructive testing device for multilayer thin film structure according to claim 2, characterized in that: The spectrum measurement unit includes a mirror group and an imaging spectrometer arranged in sequence; The mirror group is used to form a primary imaging optical path with the objective lens, so as to perform primary imaging at the entrance of the imaging spectrometer using the reference light and the signal light of each sampling point; The imaging spectrometer is used to obtain interference spectrum information corresponding to the primary imaging information transmitted by the mirror group.

4. The nondestructive testing device for multi-layer thin film structure according to claim 3, characterized in that: The imaging spectrometer comprises an incident slit, a collimating beam expander, a diffraction grating, a focusing lens group and a two-dimensional array detector which are arranged in sequence; The incident slit is used to limit stray light irrelevant to the primary imaging information from entering the imaging spectrometer; The collimating beam expander is used to collimate the reference light and the signal light beams after passing through the incident slit in the horizontal direction; The diffraction grating is used to diffract and disperse the parallel beam of reference light and the parallel beam of signal light transmitted by the collimating beam expander. The focusing lens group is used to focus the light of different wavelengths transmitted by the diffraction grating onto the two-dimensional array detector to form a spectral image, and to compensate for the optical aberration of the spectral image, and to control the size of the spectral image by setting the effective focal length; The two-dimensional array detector is used to obtain interference spectrum information of the spectrum image in multiple fields of view.

5. The nondestructive testing device for multi-layer thin film structure according to claim 4, characterized in that: The focusing lens group includes three bi-ply lenses arranged in sequence, and the optical power of the three bi-ply lenses is positive, negative, and positive in sequence.

6. The nondestructive testing device for multi-layer thin film structure according to claim 1, characterized in that: The reference arm comprises an achromatic lens, an attenuation plate and a reference mirror which are arranged in sequence; the reference mirror is fixed in position; The achromatic lens is used to form a focused reference line spot on the reference mirror and compensate for the dispersion of the broadband light source; The attenuation plate is used to attenuate the light intensity of the light beam transmitted from the achromatic lens, so as to weaken the light intensity of the reference arm, so that the light intensity of the reference arm and the light intensity of the sample arm can be matched; The reference mirror is used to reflect the light beam transmitted from the attenuation plate to form reference light for each sampling point of each layer of the multi-layer thin film structure to be measured.

7. The nondestructive testing device for a multilayer thin film structure according to any one of claims 1 to 6, characterized in that: The broadband light source unit comprises a broadband light source, a fiber collimator and a cylindrical lens which are arranged in sequence; Broadband light sources are used to provide light sources in the target spectral range; The optical fiber collimator is used to collimate and adjust the light beam transmitted from the broadband light source; The cylindrical lens is used to shape the collimated light beam transmitted from the optical fiber collimator to form a line light beam, so as to transmit the line light beam to the beam splitter.

8. A detection method applied to the nondestructive testing device for a multilayer thin film structure according to any one of claims 1 to 7, characterized in that: include: Obtaining interference spectrum information of each sampling point of each layer of the multi-layer thin film structure to be measured; Generate three-dimensional tomographic image data with reflection intensity information based on the interference spectrum information of each sampling point; Determine the reflection intensity scanning information corresponding to each sampling point based on the three-dimensional tomography image data of each sampling point; The reflection intensity scanning information corresponding to each sampling point is used to perform three-dimensional imaging detection on the multi-layer thin film structure to be tested.

9. The detection method according to claim 8, characterized in that: The multi-layer thin film structure to be tested is a flexible printed circuit board, and the reflection intensity scanning information corresponding to each sampling point is used to perform three-dimensional imaging detection on the multi-layer thin film structure to be tested, including: Based on the reflection intensity scanning information corresponding to each sampling point of each layer structure of the flexible printed circuit board, determining the maximum reflection intensity information and the second maximum reflection intensity information of the reflection intensity scanning information corresponding to each sampling point within the target depth interval; Determine the height map data corresponding to each sampling point based on the maximum reflection intensity information and the second maximum reflection intensity information corresponding to each sampling point; A three-dimensional point cloud image of the flexible printed circuit board is generated by using the height map data and the spatial plane coordinates corresponding to each sampling point, so as to perform structural defect detection on each layer structure of the flexible printed circuit board.

10. The detection method according to claim 8, characterized in that: The multi-layer thin film structure to be tested is a display screen; the reflection intensity scanning information corresponding to each sampling point is used to perform three-dimensional imaging detection on the multi-layer thin film structure to be tested, including: Performing Gaussian filtering on the reflection intensity scanning information corresponding to each sampling point of each layer structure of the display screen to obtain each processed reflection intensity scanning information; Based on each of the processed reflection intensity scanning information, determining the interface positioning imaging results of each layer structure of the display screen; Interface defect detection is performed on each layer structure of the display screen according to the interface positioning imaging result.

Images