A method and device for measuring three-dimensional information of multi-layer structure

Abstract

The present invention discloses a method and device for measuring three-dimensional information of a multi-layer structure, and the measuring method comprises the following steps: 1) optically scanning the entire top surface of the multi-layer structure to obtain the intensity distribution information of the reflected light; 2) converting the intensity distribution information of the reflected light into three-dimensional point cloud information; obtaining the multi-layer profile by least square fitting the three-dimensional point cloud information; 3) compensating for the refraction tilt of the multi-layer structure; 4) correcting the point cloud coordinates; 5) extracting the characteristic information of the microchannel of the multi-layer structure from the real point cloud information of the multi-layer structure. The present invention realizes the effective detection of the multi-layer channel structure, with accurate detection and high detection efficiency, and is suitable for batch detection.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-layer structure internal feature detection, and in particular to a method and device for measuring three-dimensional information of a multi-layer structure. Background Art

[0002] Including but not limited to wafers and chips, MEMS devices in the semiconductor field; lenses and camera lenses, optical fibers, coating films, filters in the optical field; polymer materials and nanomaterials in the material field; microfluidic chips in the medical field; some multi-layer films with regular structures on the surface (blue light reflective coatings, anti-reflection coatings, photonic crystals, light-emitting diodes) and other multi-layer structures need to be feature tested after production to evaluate whether their performance meets the requirements.

[0003] At present, the manual inspection of multi-layer structure products is usually carried out by visual inspection under a microscope, which is time-consuming and labor-intensive, and can only detect obvious defects such as bubbles and scratches. With the development of computer technology and the popularization of artificial intelligence, defect detection methods such as imaging, infrared, electromagnetic, and ultrasonic methods are also applied to the production inspection of multi-layer structures, but they are limited to the complex structure inside the multi-layer structure and can only detect specific defects such as surface cracks. The much-anticipated image processing method for supervised defect detection can identify various defect characteristics with a high accuracy, but it is only applicable to multi-layer structures with transparent and clear surface structures, and has poor production inspection effects on multi-layer structures with complex structures and multi-layer surfaces. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a method and device for measuring three-dimensional information of a multi-layer structure, which can achieve effective detection of the multi-layer channel structure with accurate detection and high detection efficiency, and is suitable for batch detection.

[0005] The present invention provides a method for measuring three-dimensional information of a multi-layer structure, comprising the following steps:

[0006] 1) transmitting measurement light to the multilayer structure through a line spectrum confocal sensor, optically scanning the entire top surface of the multilayer structure through the measurement light, and obtaining intensity distribution information of the reflected light;

[0007] 2) Convert the intensity distribution information of the reflected light into three-dimensional point cloud information; obtain the multi-layer surface by least squares fitting the three-dimensional point cloud information;

[0008] The multi-layer profile includes [the first profile, the second profile, ..., the nth profile] from top to bottom; the measured thickness between adjacent profiles is recorded as [h 1 、h 2 ,...,h n-1 ];

[0009] 3) Multi-layer structure refraction tilt compensation;

[0010] The true thickness H between adjacent profiles i for:

[0011]

[0012] Where N is the material refractive index of the multilayer structure; θ i To measure the incident angle of light relative to the i-th profile surface;

[0013]

[0014]

[0015] α=f(λ);

[0016] in, is the direction vector opposite to the incident light direction of the measurement light;

[0017] is the normal vector of the i-th layer surface;

[0018] α is the angle between the incident light of the measurement light in the yz plane and the z axis;

[0019] f(λ) is the functional relationship between α and the wavelength λ of the light source;

[0020] 4) Point cloud coordinate correction;

[0021] Based on the point cloud information of the first layer of the profile, the 3D point cloud information of the first layer of the profile to the nth layer of the profile is corrected, that is, all points below the first layer are corrected in the normal vector Move in direction (Δx, Δy, Δz) 1 , obtain the real point cloud information of the second layer surface;

[0022] Similarly, taking the real point cloud information of the i-th layer of the profile as the reference, the 3D point cloud information of the i-th layer of the profile to the n-th layer of the profile is corrected again, that is, after the i-1th correction, all the points below the i-th layer have a normal vector of Move again in the direction (Δx, Δy, Δz) i , obtain the real point cloud information of the i+1th layer of the surface, i=2...n-1;

[0023] After n-1 corrections, the real point cloud information of the multi-layer structure is obtained;

[0024]

[0025] Among them, (H i -h i) is the refractive thickness error between the i-th profile and the i+1-th profile;

[0026] 5) Extract the characteristic information of multi-layer structure microchannels from the real point cloud information of the multi-layer structure.

[0027] Furthermore, in the step 2), the three-dimensional point cloud information is downsampled, statistically filtered, and subjected to coarse point removal processing.

[0028] Furthermore, the characteristic information of the microchannel includes length, width, thickness, diameter and / or surface flatness.

[0029] In addition, the present invention also provides a measuring device for measuring a multilayer structure using the above-mentioned measuring method, comprising:

[0030] Workbench;

[0031] A measuring platform is arranged above the workbench;

[0032] A placement seat, arranged above the measuring platform, for placing the multi-layer structure;

[0033] A line spectrum confocal sensor is arranged above the placement seat;

[0034] A driving module is arranged on the workbench and is respectively connected to the measuring platform and the line spectrum confocal sensor, and is used to drive the measuring platform to move along the X-axis direction and the Y-axis direction, and to drive the line spectrum confocal sensor to move along the Z-axis direction;

[0035] The translation table includes a first base fixedly arranged on the top surface of the measuring platform, a moving base is slidably connected to the top of the first base, a first cylinder for driving the moving base to move along the X-axis direction is fixedly arranged on one side of the first base, a second base is fixedly arranged on the top of the moving base, the bottom of the placement base is slidably connected to the top of the second base, and a second cylinder for driving the placement base to move along the Y-axis direction is fixedly arranged on one side of the second base.

[0036] Further, the driving module includes an X-axis module, a Y-axis module and a Z-axis module;

[0037] The X-axis module is arranged on the top surface of the workbench, the Y-axis module is connected to the top of the X-axis module by transmission, and the measuring platform is connected to the top of the Y-axis module by transmission; a bracket is fixedly arranged on one side of the top surface of the workbench, the Z-axis module is fixedly arranged on one side of the bracket, and the line spectrum confocal sensor is connected to the Z-axis module by transmission.

[0038] Furthermore, support plates are respectively arranged at the four corners of the bottom of the workbench, the top of the support plate is threadedly connected to the workbench through a screw, and universal wheels are arranged on the inner side of each support plate at the bottom of the workbench.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] (1) The present invention uses a line spectrum confocal measurement method to measure multilayer structures, which has high morphological resolution and measurement accuracy. After obtaining the point cloud data after the line spectrum confocal sensor solves the light intensity peak and corrects the material refractive index error, the complex and tortuous multilayer channel three-dimensional morphology under the surface of the multilayer structure is accurately reproduced through operations such as fitting the profile and matching the splicing channel features, and the size or feature information used to evaluate the multilayer structure is extracted. Compared with the traditional image processing measurement method, the accurate measurement of the multilayer structure is achieved.

[0041] (2) The optical measurement of the present invention is not limited by external factors such as propagation medium, temperature field, and measurement material, and there is no need for direct contact between the line spectrum confocal sensor and the multilayer structure to be measured, thus avoiding possible surface damage and contamination, and ensuring the accuracy and stability of the measurement. In addition, the data of reflected light can be collected in real time, and the microchannel characteristics of the multilayer structure can be analyzed in real time, which greatly improves the measurement efficiency and experimental flexibility.

[0042] (3) The measuring device realizes the automatic control of the measuring process, reduces the error of manual operation, improves the consistency and repeatability of the measurement, and is matched with a multi-degree-of-freedom grasping robot and an adaptive detection cycle. The detection efficiency is high and it is suitable for large-scale multi-layer structure product detection.

[0043] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0045] Figure 1 is a schematic diagram of the structure of the measuring device;

[0046] Figure 2 Schematic diagram of the structure of the translation stage.

[0047] Numbers in the figure: 1. workbench; 2. measurement platform; 3. mounting seat; 4. line spectrum confocal sensor; 5. drive module; 6. translation stage; 7. multilayer structure;

[0048] 11. Support plate; 12. Screw rod; 13. Universal wheel;

[0049] 51. X-axis module; 52. Y-axis module; 53. Z-axis module; 54. bracket;

[0050] 61. First base; 62. Moving base; 63. First cylinder; 64. Second base; 65. Second cylinder. DETAILED DESCRIPTION

[0051] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0052] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0053] An embodiment of the present invention provides a method for measuring three-dimensional information of a multi-layer structure, comprising the following steps:

[0054] 1) transmitting measurement light to the multilayer structure through a line spectrum confocal sensor, optically scanning the entire top surface of the multilayer structure through the measurement light, and obtaining intensity distribution information of the reflected light;

[0055] 2) Convert the intensity distribution information of the reflected light into three-dimensional point cloud information; obtain the multi-layer surface by least squares fitting the three-dimensional point cloud information;

[0056] The multi-layer profile includes [the first profile, the second profile, ..., the nth profile] from top to bottom; the measured thickness between adjacent profiles is recorded as [h 1 、h 2 ,...,h n-1 ];

[0057] 3) Multi-layer structure refraction tilt compensation;

[0058] The true thickness H between adjacent profiles i for:

[0059]

[0060] Where N is the material refractive index of the multilayer structure; θ i To measure the incident angle of light relative to the i-th profile surface;

[0061]

[0062]

[0063] α=f(λ);

[0064] in, is the direction vector opposite to the incident light direction of the measurement light;

[0065] is the normal vector of the i-th layer surface;

[0066] α is the angle between the incident light of the measurement light in the yz plane and the z axis;

[0067] f(λ) is the functional relationship between α and the wavelength λ of the light source;

[0068] 4) Point cloud coordinate correction;

[0069] Based on the point cloud information of the first layer of the profile, the 3D point cloud information of the first layer of the profile to the nth layer of the profile is corrected, that is, all points below the first layer are corrected in the normal vector Move in direction (Δx, Δy, Δz) 1 , obtain the real point cloud information of the second layer surface;

[0070] Similarly, taking the real point cloud information of the i-th layer of the profile as the reference, the 3D point cloud information of the i-th layer of the profile to the n-th layer of the profile is corrected again, that is, after the i-1th correction, all the points below the i-th layer have a normal vector of Move again in the direction (Δx, Δy, Δz) i , obtain the real point cloud information of the i+1th layer of the surface, i=2...n-1;

[0071] After n-1 corrections, the real point cloud information of the multi-layer structure is obtained;

[0072]

[0073] Among them, (H i -h i ) is the refractive thickness error between the i-th profile and the i+1-th profile;

[0074] 5) Extract the characteristic information of multi-layer structure microchannels from the real point cloud information of the multi-layer structure.

[0075] In this embodiment, for a microfluidic chip having a film layer on its surface, the first layer of the mold surface is the top surface of the film layer, the second layer of the mold surface is the bottom surface of the film layer, the third layer of the mold surface and the fourth layer of the mold surface are between the top microchannel, the fifth layer of the mold surface and the sixth layer of the mold surface are between the second microchannel, and the subsequent microchannels are analogous in sequence.

[0076] For microfluidic chips without a membrane layer on the surface, the first layer of the surface is the top surface of the microfluidic chip, the uppermost microchannel is between the second and third layers of the surface, the second microchannel is between the fourth and fifth layers of the surface, and the subsequent microchannels are analogous in sequence.

[0077] Due to mechanical errors, the plane of the microfluidic chip is not completely perpendicular to the incident direction of the measurement light. Considering that the materials of the measured microfluidic chips are different, the refractive index of the materials themselves is different. The light source of the line spectrum confocal sensor will refract to different degrees when it is irradiated on the surface of the microfluidic chip. Therefore, the profile of the measured data needs to be compensated and corrected. After obtaining the point cloud data after the line spectrum confocal sensor solves the peak light intensity and corrects the material refractive index error, the complex and tortuous multi-layer channel three-dimensional morphology under the surface of the microfluidic chip is accurately reproduced through operations such as fitting the profile and matching the splicing channel features, and the size or feature information used to evaluate the production quality of the microfluidic chip is extracted. The microfluidic chip is measured using the line spectrum confocal measurement method, which has high morphological resolution and measurement accuracy. Compared with the traditional image processing measurement method, the accurate measurement of the multi-layer structure of the microfluidic chip is achieved.

[0078] The optical measurement of the present application is not limited by external factors such as propagation medium, temperature field, and measurement material, and there is no need for direct contact between the line spectrum confocal sensor and the microfluidic chip to be measured, thus avoiding possible surface damage and contamination, and ensuring the accuracy and stability of the measurement. In addition, the data of reflected light can be collected in real time, and the microchannel characteristics of the microfluidic chip can be analyzed in real time, which greatly improves the measurement efficiency and experimental flexibility.

[0079] The measurement method of the present application can timely correct the refraction error of the sensor caused by the light source and the material during the acquisition process according to the material of the measured multi-layer structure and the inclination of the processed surface. On the basis of ensuring the measurement accuracy, it has stronger versatility for quality inspection of a wide variety of multi-layer structures on the market.

[0080] In a preferred embodiment, in step 2), the three-dimensional point cloud information is downsampled, statistically filtered, and subjected to coarse point removal processing to ensure the accuracy of the measurement data.

[0081] In a preferred embodiment, the characteristic information of the microchannel includes length, width, thickness, diameter and / or surface flatness, and the measurement data is comprehensive.

[0082] Also, see Figure 1-2 The embodiment of the present invention further provides a measuring device for measuring a multilayer structure using the above-mentioned measuring method, comprising:

[0083] Workbench 1;

[0084] The measuring platform 2 is arranged above the working table 1;

[0085] A placement seat 3 is arranged above the measuring platform 2 and is used to place the multi-layer structure 7;

[0086] The line spectrum confocal sensor 4 is arranged above the placement seat 3;

[0087] The driving module 5 is arranged on the workbench 1 and is respectively connected to the measuring platform 2 and the line spectrum confocal sensor 4, and is used to drive the measuring platform 2 to move along the X-axis direction and the Y-axis direction, and to drive the line spectrum confocal sensor 4 to move along the Z-axis direction;

[0088] The translation table 6 includes a first base 61 fixedly arranged on the top surface of the measuring platform 2, a moving base 62 is slidably connected to the top of the first base 61, a first cylinder 63 for driving the moving base 62 to move along the X-axis direction is fixedly arranged on one side of the first base 61, a second base 64 is fixedly arranged on the top of the moving base 62, the bottom of the placement base 3 is slidably connected to the top of the second base 64, and a second cylinder 65 for driving the placement base 3 to move along the Y-axis direction is fixedly arranged on one side of the second base 64.

[0089] In this embodiment, before measuring the multilayer structure 7, the working area on the workbench 1 is cleaned to ensure that the surface is flat. The multilayer structure 7 to be measured is placed on the placement seat 3 to ensure that the surface of the multilayer structure 7 is clean and free of impurities or dirt.

[0090] Then, the line spectrum confocal sensor 4 and the driving module 5 are turned on to move the multilayer structure 7 to the initial position below the line spectrum confocal sensor 4. The positioning seat 3 is then driven by the translation stage 6 to move along the X-axis direction and the Y-axis direction respectively to achieve a comprehensive scan of the multilayer structure 7. The driving accuracy of the translation stage 6 is high, ensuring the scanning accuracy.

[0091] The measuring device realizes the automatic control of the measuring process, reduces the error of manual operation, improves the consistency and repeatability of measurement, and is matched with a multi-degree-of-freedom grasping robot and designed with adaptive detection cycle, with high detection efficiency, which is suitable for large-scale multi-layer structure product detection.

[0092] In a preferred embodiment, if Figure 1 As shown, the driving module 5 includes an X-axis module 51, a Y-axis module 52 and a Z-axis module 53;

[0093] The X-axis module 51 is arranged on the top surface of the workbench 1, the Y-axis module 52 is transmission connected to the top of the X-axis module 51, and the measuring platform 2 is transmission connected to the top of the Y-axis module 52; a bracket 54 is fixedly arranged on one side of the top surface of the workbench 1, the Z-axis module 53 is fixedly arranged on one side of the bracket 54, and the line spectrum confocal sensor 4 is transmission connected to the Z-axis module 53.

[0094] In this embodiment, the measuring platform 2 is driven to move by the X-axis module 51 and the Y-axis module 52, so that the mounting seat 3 is moved to the bottom of the line spectrum confocal sensor 4, thereby achieving a rough adjustment of the position of the mounting seat 3 with good adjustment efficiency. The Z-axis module 53 is used to adjust the distance between the line spectrum confocal sensor 4 and the multilayer structure 7 to ensure effective reception of reflected light.

[0095] In a preferred embodiment, if Figure 1 As shown, support plates 11 are respectively arranged at the four corners of the bottom of the workbench 1, the top of the support plates 11 is threadedly connected to the workbench 1 through screws 12, and universal wheels 13 are arranged on the inner side of each support plate 11 at the bottom of the workbench 1, so as to facilitate the movement and support and fixation of the workbench 1.

[0096] In the description of this specification, the terms "connection", "installation", "fixation" and the like should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0097] In the description of this specification, the description of the terms "one embodiment", "some embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0098] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for measuring three-dimensional information of a multi-layer structure, characterized in that: The steps include: 1) transmitting measurement light to the multilayer structure through a line spectrum confocal sensor, optically scanning the entire top surface of the multilayer structure through the measurement light, and obtaining intensity distribution information of the reflected light; 2) Convert the intensity distribution information of the reflected light into three-dimensional point cloud information; obtain the multi-layer surface by least squares fitting the three-dimensional point cloud information; The multi-layer profile includes [the first layer profile, the second layer profile, ..., the nth layer profile] from top to bottom; the measured thickness between adjacent profiles is recorded as [h1, h2, ..., h n-1 ]; 3) Multi-layer structure refraction tilt compensation; The true thickness H between adjacent profiles i for: Where N is the material refractive index of the multilayer structure; θ i To measure the incident angle of light relative to the i-th profile surface; α=f(λ); in, is the direction vector opposite to the incident light direction of the measurement light; is the normal vector of the i-th layer surface; α is the angle between the incident light of the measurement light in the yz plane and the z axis; f(λ) is the functional relationship between α and the wavelength λ of the light source; 4) Point cloud coordinate correction; Based on the point cloud information of the first layer of the profile, the 3D point cloud information of the first layer of the profile to the nth layer of the profile is corrected, that is, all points below the first layer are corrected in the normal vector Move in the direction (Δx, Δy, Δz) 1 to obtain the real point cloud information of the second layer surface; Similarly, taking the real point cloud information of the i-th layer of the profile as the reference, the 3D point cloud information of the i-th layer of the profile to the n-th layer of the profile is corrected again, that is, after the i-1th correction, all the points below the i-th layer have a normal vector of Move again in the direction (Δx, Δy, Δz) i , obtain the real point cloud information of the i+1th layer of the surface, i=2...n-1; After n-1 corrections, the real point cloud information of the multi-layer structure is obtained; Among them, (H i -h i ) is the refractive thickness error between the i-th profile and the i+1-th profile; 5) Extract the characteristic information of multi-layer structure microchannels from the real point cloud information of the multi-layer structure.

2. The measuring method according to claim 1, characterized in that: In the step 2), the three-dimensional point cloud information is downsampled, statistically filtered and subjected to coarse point removal processing.

3. The measuring method according to claim 1, characterized in that: The characteristic information of the microchannel includes length, width, thickness, diameter and / or surface flatness.

4. A measuring device for measuring a multilayer structure using the measuring method according to any one of claims 1 to 3, characterized in that: include: Workbench; A measuring platform is arranged above the workbench; A placement seat, arranged above the measuring platform, for placing the multi-layer structure; A line spectrum confocal sensor is arranged above the placement seat; A driving module is arranged on the workbench and is respectively connected to the measuring platform and the line spectrum confocal sensor, and is used to drive the measuring platform to move along the X-axis direction and the Y-axis direction, and to drive the line spectrum confocal sensor to move along the Z-axis direction; The translation table includes a first base fixedly arranged on the top surface of the measuring platform, a moving base is slidably connected to the top of the first base, a first cylinder for driving the moving base to move along the X-axis direction is fixedly arranged on one side of the first base, a second base is fixedly arranged on the top of the moving base, the bottom of the placement base is slidably connected to the top of the second base, and a second cylinder for driving the placement base to move along the Y-axis direction is fixedly arranged on one side of the second base.

5. The measuring device according to claim 4, characterized in that The driving module includes an X-axis module, a Y-axis module and a Z-axis module; The X-axis module is arranged on the top surface of the workbench, the Y-axis module is connected to the top of the X-axis module by transmission, and the measuring platform is connected to the top of the Y-axis module by transmission; a bracket is fixedly arranged on one side of the top surface of the workbench, the Z-axis module is fixedly arranged on one side of the bracket, and the line spectrum confocal sensor is connected to the Z-axis module by transmission.

6. The measuring device according to claim 4, characterized in that Support plates are respectively arranged at the four corners of the bottom of the workbench, the top of the support plate is threadedly connected to the workbench through a screw rod, and universal wheels are arranged on the inner side of each support plate at the bottom of the workbench.

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