A multi-channel high-precision overlay error detection system and method

Abstract

The application discloses a kind of multi-channel high-precision overlay error detection systems, for measuring the overlay error of measured chip, comprising: multi-channel light source module, measurement module, objective table module, imaging module and computing module, wherein the measured chip is placed on the objective table module, the multi-channel light source module can be projected by time different channel laser through the measurement module to the measured chip, after reflecting on the measured chip, again through the measurement module and image on the imaging module, the computing module is connected with the imaging module to calculate the overlay error of the measured chip according to the imaging data on the imaging module.The application also discloses a kind of multi-channel high-precision overlay error detection method and a kind of multi-channel high-precision overlay correction method.The application can improve the detection precision of overlay error.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing, and in particular to a multi-channel high-precision overlay error detection system and method. Background Technology

[0002] Alignment measurement equipment is mainly used in the photolithography process of integrated circuit manufacturing. It is an important tool for evaluating the quality and monitoring the yield of photolithography processes. Alignment measurement equipment is a key piece of equipment in integrated circuit manufacturing and is a bottleneck restricting the development of China's integrated circuit manufacturing industry.

[0003] Regarding multi-channel light sources, there are two main technical solutions in traditional optical system design. One approach uses multiple wavelength filters to filter light passing through the lens, allowing only a specific spectral band to pass. The filter array uses either wheel-type or array-type filters, and images of each spectral band are obtained through push-broom scanning. However, this method filters out most of the light, requiring high-performance detectors or increased exposure time to ensure image quality. The other approach is a dispersive spectral imager, which uses prisms or gratings to separate light of different wavelengths. After passing through the optical system, the light of different wavelengths is focused at different positions on the detector. This method also suffers from low received light spot energy.

[0004] In overlay error detection, the installation angle error of the alignment marks and the focusing distance are generally measured by a specialized ranging system, such as a multi-degree-of-freedom high-precision workpiece stage or a laser interferometer. Traditional overlay error measurement systems require additional measuring equipment, resulting in high measurement costs and long measurement times.

[0005] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a multi-channel high-precision overlay error detection system and method, which can improve the detection accuracy of overlay errors.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention discloses a multi-channel high-precision overlay error detection system for measuring the overlay error of a chip under test. The system includes a multi-channel light source module, a measurement module, a stage module, an imaging module, and a calculation module. The chip under test is placed on the stage module. The multi-channel light source module can project lasers from different channels at different times, which pass through the measurement module to the chip under test. After reflection from the chip under test, the laser light passes back through the measurement module and is imaged onto the imaging module. The calculation module is connected to the imaging module to calculate the overlay error of the chip under test based on the imaging data from the imaging module.

[0009] Preferably, the measurement module includes an optical device, an optical collimator, and a lens that have the function of changing the direction of the optical path, and the imaging module includes an optical device, an optical collimator, a converging lens, and a camera that have the function of changing the direction of the optical path.

[0010] Preferably, the multi-channel light source module includes a switch controller and at least two channels of laser light sources. The switch controller is connected to and used to control the laser light sources of each channel to project lasers in a time-division manner, wherein the laser light sources of each channel are used to project lasers of different wavelengths.

[0011] This invention discloses a multi-channel high-precision overlay error detection method, which uses the aforementioned multi-channel high-precision overlay error detection system to measure the overlay error of the chip under test, including:

[0012] A1: The laser light from any channel is projected by the multi-channel light source module, passes through the measurement module to the chip under test, is reflected on the chip under test, passes through the measurement module again, and is imaged on the imaging module;

[0013] A2: The calculation module calculates the overlay error of the chip under test based on the imaging data on the imaging module.

[0014] Preferably, the calculation module uses the following formula to calculate the overlay error of the chip under test based on the imaging data on the imaging module:

[0015]

[0016] In the formula, Δd is the overlay error of the chip under test, f0 is the initial offset between the upper and lower layers, and D1 and D2 are the light intensity difference of ±1 diffraction order corresponding to a pair of measurement patterns in a certain direction on the chip under test.

[0017] Preferably, the method further includes A3: repeating steps A1 and A2 to calculate the average value of the overlay error of the chip under test obtained in multiple steps A2 as the final overlay error of the chip under test, wherein each time step A1 is repeated, the multi-channel light source module transmits laser light of different wavelengths.

[0018] This invention discloses a computer-readable storage medium storing computer-executable instructions. When the computer-executable instructions are invoked and executed by a processor, the computer-executable instructions cause the processor to implement the steps of the above-described multi-channel high-precision overlay error detection method.

[0019] This invention discloses a multi-channel high-precision overlay correction method, which uses the aforementioned multi-channel high-precision overlay error detection system to measure the angle mounting error and focusing distance of the chip under test, including:

[0020] B1: The laser of the first channel is projected by the multi-channel light source module, passes through the measurement module to the chip under test, is reflected on the chip under test, passes through the measurement module again, and is imaged on the imaging module;

[0021] B2: The laser of the second channel is projected by the multi-channel light source module, passes through the measurement module to the chip under test, is reflected on the chip under test, passes through the measurement module again, and is imaged on the imaging module;

[0022] B3: The calculation module calculates the angle installation error and focusing distance of the chip under test based on the imaging data on the imaging module in steps B1 and B2, and corrects the position of the stage module based on the angle installation error and focusing distance of the chip under test.

[0023] Preferably, step B3 specifically includes:

[0024] B31: Based on the imaging data from the imaging module described in step B1, the following formula can be obtained:

[0025]

[0026]

[0027] In the formula, θ1 represents the angle between the laser beam of the first channel of the chip under test and the normal of the chip under test under ideal conditions, θ0 represents the angular installation error of the chip under test, k is the scaling factor, H is the focusing distance of the chip under test, and da1 and dc1 are the distances between the imaging point and the center point on the image plane of the imaging module when the multi-channel light source module projects the laser beam of the first channel, which are symmetrical about the normal of the chip under test.

[0028] B32: Based on the imaging data from the imaging module described in step B2, the following formula can be obtained:

[0029]

[0030]

[0031] In the formula, θ2 represents the angle between the laser beam of the second channel of the chip under test and the normal of the chip under test under ideal conditions, and da2 and dc2 are the distances between the imaging point and the center point on the image plane of the imaging module when the multi-channel light source module projects the laser beam of the second channel and the two beams symmetrical along the normal of the chip under test.

[0032] B33: The calculation module calculates the angle installation error θ0 and focusing distance H of the chip under test according to the formulas in steps B31 and B32, and corrects the position of the stage module according to the angle installation error and focusing distance of the chip under test.

[0033] The present invention discloses a computer-readable storage medium storing computer-executable instructions. When the computer-executable instructions are invoked and executed by a processor, the computer-executable instructions cause the processor to implement the steps of the above-described multi-channel high-precision overlay correction method.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: The multi-channel high-precision overlay error detection system and method proposed in the present invention, for the purpose of studying the multi-channel overlay error measurement system for diverse alignment marks, can actively adjust the projection mode of the measurement light source, explore the multi-channel spectral response law and reliability of the optical system, compensate for the differences in scattering images caused by different spectral characteristics, and improve the detection accuracy of overlay error.

[0035] In a further embodiment, the multi-channel spectral module can select different wavelengths of precision laser light sources through a switch controller to obtain higher energy light spots; at the same time, the structure of the multi-channel light source makes the measurement accuracy of overlay error higher, faster, and more robust.

[0036] In a further embodiment, the multi-channel high-precision overlay error detection system proposed in this invention can also directly measure the angle mounting error and focusing distance of the chip under test. This eliminates the need for additional measurement branches for the mounting angle error of the chip under test or for the focusing distance, thus measuring the mounting error and focusing distance, improving error measurement accuracy, and reducing costs. Attached Figure Description

[0037] Figure 1 This is a block diagram of the multi-channel high-precision overlay error detection system according to a preferred embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the overlay markings in a specific embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of the multi-channel light source module in a specific embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram illustrating the system measurement and imaging principle of a specific embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram of the system measurement module according to a specific embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram of the system imaging module according to a specific embodiment of the present invention. Detailed Implementation

[0043] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0044] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for both fixing and circuit / signal connectivity.

[0045] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0047] This invention, in its preferred embodiment, proposes a novel, faster, more accurate, and more robust multi-channel overlay error detection system and method for the overlay error detection process. This system can quickly and accurately determine the focusing distance without adding an additional distance sensor or ranging system. Furthermore, it eliminates the need for an additional angle mounting error detection system, using a multi-channel light source system to solve for the angular mounting error of the chip under test in the vertical direction, thereby further improving the measurement accuracy of overlay errors. In addition, the multi-channel light source configuration can further reduce errors and improve measurement accuracy.

[0048] In photolithography alignment systems, there are various alignment marks. A preferred embodiment of this invention proposes a novel multi-channel overlay error detection system to address the error detection of these diverse marks. For example... Figure 1 As shown, the system includes a multi-channel light source module 1, a measurement module 2, a chip under test 3, a stage module 4, an imaging module 5, and a calculation module 6 (the embodiment takes the alignment mark on the chip under test as an example). The chip under test 3 is placed on the stage module 4. The multi-channel light source module 1 can project lasers from different channels through the measurement module 2 to the chip under test 3 in a time-division manner. After being reflected on the chip under test 3, the lasers pass through the measurement module 2 again and are imaged on the imaging module 5. The calculation module 6 is connected to the imaging module 5 to calculate the overlay error, angle installation error, and focusing distance of the chip under test 3 based on the imaging data on the imaging module 5.

[0049] like Figure 2 The image shows an example of overlay error marking. The initial offsets between the upper and lower layers in the second and fourth quadrants are f0 and -f0, respectively. There is an overlay error Δd between the upper and lower layers, making the offsets between the upper and lower layers in the second and fourth quadrants f0+Δd and -f0+Δd, respectively. Each pair of focusing units is used for overlay measurement in the grating vector direction; the black grating represents the upper grating, and the group of rectangles formed by dashed lines represents the lower grating.

[0050] For a pair of measurement patterns in a certain direction in the overlay mark, different ±1 order diffraction light intensity differences D1 and D2 can be measured respectively. Based on the approximate linear relationship between overlay accuracy and ±1 order diffraction light intensity difference, the calculation formula (1) for overlay accuracy measurement value can be obtained as follows.

[0051]

[0052] In the formula, f0 is the initial offset between the upper and lower layers in the 2nd and 4th quadrants. As can be seen from formula (1), the overlay error Δd is related to the intensity difference of the ±1st order diffracted light.

[0053] To further illustrate the multi-channel light source module, consider the example shown below. Figure 3As shown, this example uses a 4-channel laser array (channel count ≥ 2), with the laser source being a frequency-stabilized precision light source group. Taking four laser sources—red (R), blue (B), green (G), and yellow (Y)—as an example, there is a strict switching control relationship between the four laser sources (including switches K1, K2, K3, and K4) for time-division multiplexing of the laser projection. When the red laser source R is activated, switch K1 of the red laser path is in the open state, while the switches of the other three light source paths are in the closed state. The same applies when other channels of the light source are activated.

[0054] In a preferred embodiment of this invention, a multi-channel light source module is employed. This module allows for the active adjustment of the projection mode of the measurement light source, enabling the time-division projection of laser light of different wavelengths onto a mark on the chip under test (DUT). The DUT is placed on a precisely movable stage. This system utilizes multiple precise single-wavelength light sources, controlled by strict switching, to select one wavelength at a time for projection onto the DUT. The use of a precise tunable laser to generate monochromatic laser light results in a simple, reliable structure with high detection efficiency. This method is illustrated using four laser sources: red, blue, yellow, and green. The multi-channel light source module is as follows: Figure 3 As shown.

[0055] like Figure 4 As shown, the measurement module 2 mainly consists of optical devices with the function of changing the direction of the light path, optical collimating devices, lenses 21, and other optical components. The imaging module 5 mainly consists of optical devices with the function of changing the direction of the light path, optical collimating devices, converging lenses 51, and other optical components, as well as a camera 52. The optical devices with the function of changing the direction of the light path and the optical collimating devices play a modifying role in the application. Figure 4 It is not shown in the diagram. The calculation module 6 consists of a computer and image processing related algorithms.

[0056] The principle of the effect of the angular installation error of the tested chip 3 in the vertical direction on diffraction imaging is as follows: Figure 4 As shown in the figure, lens 21 is placed at a focal distance H from the chip under test 3, that is, the distance between the horizontal axis 211 of lens 21 and the chip under test 3 is the focal distance H. During actual operation, the focal distance H of the overlay error detection system will change. This embodiment of the invention uses multiple channels of light sources at each position to detect overlay errors on the markings on the chip under test 3, thereby determining the focal distance H, the initial angular mounting error θ0 of the chip under test 3 in the vertical direction, and the high-precision overlay error Δd.

[0057] Combination Figure 4 , Figure 5 and Figure 6 The measurement and imaging process is illustrated using point O on the chip 3 under test as an example.

[0058] Ideally, the chip under test 3 is placed at the first position 31 on the stage module 4, eliminating angular installation errors. The measurement process is as follows: a fixed-wavelength light source illuminates point O of the chip under test at the first position 31 through lens 21. At this point, the normal 71 at point O is perpendicular to the chip under test at the first position 31. The imaging process is as follows: the light ray 64 is reflected back through O, and along the ray 62, it passes through lens 21 and the optical path guiding device (optical components, optical path collimating devices, etc.) to finally image at point b on camera 52; the light ray 62 is reflected back through O, and along the ray 64, it passes through lens 21 and the optical path guiding device (optical components, optical path collimating devices, etc.) to finally image at point d on camera 52. A detailed schematic diagram of the imaging module principle of this system can be found in [link to schematic diagram]. Figure 6 The distance db between bO2 and the distance dd between dO2 are equal.

[0059] In practice, due to the initial angular installation error θ0 of the chip under test 3, the chip under test 21 is placed at the second position 32 on the stage module 4. The measurement process is as follows: a fixed wavelength light source shines through lens 21 onto point O of the chip under test at the second position 32. At this time, the normal 72 at point O is perpendicular to the chip under test at the second position 32. The imaging process is as follows: the light ray 61 is reflected back from O, and along the light ray 63, it passes through lens 21 and the optical path guiding device (optical devices, optical path collimating devices, etc.) and is finally imaged at point c on camera 52; the light ray 63 is reflected back from O, and along the light ray 61, it passes through lens 21 and the optical path guiding device (optical devices, optical path collimating devices, etc.) and is finally imaged at point a on camera 52. A detailed schematic diagram of the imaging module principle of this system can be found in [link to schematic diagram]. Figure 6 The distance da between aO2 and the distance dc between cO2 are not equal.

[0060] For a further detailed description of measurement module 2, see [link to relevant documentation]. Figure 5 For a detailed description of imaging module 5, see [link to documentation]. Figure 6 .

[0061] (1) The coordinates a1, b1, c1, d1 on the object plane of the measurement module correspond one-to-one with the coordinates a, b, c, d on the image plane of the imaging module, and the distances L1, L2, L3, L4 correspond one-to-one with the distance values ​​da, db, dc, dd. Furthermore, they are proportional to each other. Further explanation:

[0062]

[0063] The imaging module can be used to solve for da, db, dc, and dd, where k is the scaling factor.

[0064] (2) In ΔOO1c1, we have:

[0065]

[0066] In the formula, θ1 represents the angle between the light source ray after passing through lens 21 and the normal of the chip (object under test) at the first position 31 when the chip (object under test) is in an ideal state, i.e., the initial angular installation error θ0 is 0. To further explain, θ1 is also the angle between the light ray 62 / 64 and the normal 71. L3 and L1 correspond to the distances from the center point O1 on the horizontal axis 211 of lens 21 to c1 and a1, respectively, when using the channel 1 light source.

[0067] As can be seen from formula (3), there are three unknowns θ1, θ0 and H in a set of two formulas.

[0068] Similarly, when using channel 2 light source:

[0069]

[0070] In the formula, θ2 has the same meaning as θ1, the difference being that the light source of θ2 comes from another channel light source with a different frequency than θ1. Due to the different light source frequencies, the angle between the light from the light source after passing through lens 21 and the normal of the chip under test at the first position 31 is different, that is, θ2≠θ1. L3′ and L1′ correspond to the distances from the center point O1 on the horizontal axis 211 of lens 21 to c1 and a1, respectively, when using channel 2 light source.

[0071] With two sets of light source channels, there are four sets of equations with four unknowns (θ1, θ2, θ0, and H, respectively). The focusing distance H and the initial angular installation error θ0 can be calculated. The value of H helps the measurement system to quickly locate the chip under test, measure the value of θ0 and correct it, thereby correcting the diffraction intensity difference of ±1 order.

[0072] The following further explains the influence of θ0 on the diffraction intensity difference: The occurrence of angular installation error causes the standard normal 71 to tilt towards the normal 72. Due to the divergence of the diffraction angle, the intensity of the light spot returning to the imaging surface via ray 61 is weaker than the intensity of the light spot returning to the imaging surface via ray 63. As can be seen from formula (1), the intensity difference directly affects the overlay measurement error.

[0073] Figure 5 This is a detailed schematic diagram of the measurement module principle of the system. Figure 6 This is a detailed schematic diagram of the imaging module of the system. The image points incident by rays 61, 62, 63, and 64 are a, b, c, and d, respectively. The distances of aO2, bO2, cO2, and dO2 are da, db, dc, and dd, respectively. db and dd represent the distances from the ±1st order diffraction spot to the imaging center under ideal conditions, where db = dd; da and dc represent the distances from the ±1st order diffraction spot to the imaging center under conditions where installation errors exist, where da ≠ dc.

[0074] The multi-channel spectrum of the optical system is analyzed, and the angular installation error of the alignment mark and the vertical distance between the error measurement system and the alignment mark are determined by spectral analysis under multi-channel light sources. Multiple sets of wavelengths can trace the angular installation error of the alignment mark, thereby compensating for the angular error using a precisely movable stage module 4.

[0075] Therefore, the above preferred embodiments not only provide a multi-channel high-precision overlay error detection system, but also a multi-channel high-precision overlay error detection method capable of measuring the overlay error of the chip under test, and a multi-channel high-precision overlay correction method capable of measuring the angular mounting error and focusing distance of the chip under test, and correct the position of the stage module based on the measured angular mounting error and focusing distance of the chip under test. This invention has the following advantages:

[0076] (1) The rapid and accurate measurement and correction of the initial angle installation error θ0 has a significant impact on the experimental results. The light intensity difference of ±1 order diffraction determines the measurement of the overlay error. The angle installation error of the chip under test in the vertical direction affects the light intensity difference of the diffraction order. Therefore, after compensating for this angle, a more accurate diffraction light intensity difference can be obtained, and a more accurate overlay measurement error can be obtained.

[0077] (2) The multi-channel light source can also calculate the focusing distance H at different positions, enabling the overlay measurement system to be positioned quickly and accurately. Through the projection of the light source in the optical channel, that is, the projection of laser light sources of different wavelengths in time division, the distance between the measurement module and the stage in the vertical direction can be obtained in real time. In wafer inspection, this distance value changes constantly and has a direct impact on the final measurement result. By quickly and accurately obtaining this distance value in real time, the detection speed of objects with a large area can be improved.

[0078] (3) Multiple wavelengths can yield multiple sets of measurement results, which can average the measurement error and enhance the robustness of the measurement results. Using multiple channels to obtain more dimensions of surface information for comprehensive evaluation can enhance the accuracy and robustness of the alignment distance calculation.

[0079] The background section of this invention may include background information about the problems or circumstances surrounding the invention, rather than a description of prior art by others. Therefore, the content included in the background section is not an admission of prior art by the applicant.

[0080] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification without contradiction. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope defined by the appended claims.

Claims

1. A multi-channel high-precision overlay error detection system, characterized in that, The device for measuring the overlay error of a chip under test includes: a multi-channel light source module, a measurement module, a stage module, an imaging module, and a calculation module. The chip under test is placed on the stage module. The multi-channel light source module can project lasers of different channels through the measurement module onto the chip under test in a time-division manner. After being reflected on the chip under test, the lasers pass through the measurement module again and are imaged onto the imaging module. The calculation module is connected to the imaging module to calculate the overlay error of the chip under test based on the imaging data on the imaging module. The multi-channel light source module actively adjusts the projection mode of the measurement light source to project lasers of different wavelengths onto the marks on the chip under test in a time-division manner. The multi-channel light source module includes a switch controller and at least two channels of laser light sources. The switch controller is connected to and used to control the laser light sources of each channel to project lasers in a time-division manner, wherein the laser light sources of each channel are used to project lasers of different wavelengths. The calculation module is also used to calculate the angle installation error and focusing distance of the chip under test based on the measurement results of multiple channels, and to correct the position of the stage module based on the angle installation error and the focusing distance. The calculation module calculates the angle installation error using the following formula. And the focusing distance H: In the formula, This represents the angle between the laser beam from the first channel of the chip under test and the normal to the chip under test under ideal conditions. This indicates the angular mounting error of the chip under test, where k is the scaling factor and H is the focusing distance of the chip under test. and The distance between the imaging point and the center point on the image plane of the imaging module when the laser of the first channel is projected by the multi-channel light source module and is symmetrical about the normal of the chip under test. This represents the angle between the laser beam from the second channel of the chip under test and the normal to the chip under test under ideal conditions. and The distance between the imaging point and the center point on the image plane of the imaging module when the second channel laser is projected by the multi-channel light source module is projected.

2. The multi-channel high-precision overlay error detection system according to claim 1, characterized in that, The measurement module includes an optical device, an optical collimator, and a lens that have the function of changing the direction of the optical path. The imaging module includes an optical device, an optical collimator, a converging lens, and a camera that have the function of changing the direction of the optical path.

3. A multi-channel high-precision overlay error detection method, characterized in that, The multi-channel high-precision overlay error detection system according to any one of claims 1 to 2 is used to measure the overlay error of the chip under test. include: A1: The laser light from any channel is projected by the multi-channel light source module, passes through the measurement module to the chip under test, is reflected on the chip under test, passes through the measurement module again, and is imaged on the imaging module; A2: The calculation module calculates the overlay error of the chip under test based on the imaging data on the imaging module.

4. The multi-channel high-precision overlay error detection method according to claim 3, characterized in that, The calculation module uses the following formula to calculate the overlay error of the chip under test based on the imaging data from the imaging module: In the formula, The overlay error of the chip under test. This represents the initial offset between the upper and lower layers. and These are the light intensities of a pair of measurement patterns in a certain direction on the chip under test, corresponding to the diffraction orders.

5. The multi-channel high-precision overlay error detection method according to claim 3 or 4, characterized in that, It also includes A3: repeating steps A1 and A2 to calculate the average value of the overlay error of the chip under test obtained in multiple steps A2 as the final overlay error of the chip under test, wherein each time step A1 is repeated, the multi-channel light source module transmits lasers of different wavelengths.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the steps of the multi-channel high-precision overlay error detection method according to any one of claims 3 to 5.

7. A multi-channel high-precision overlay correction method, characterized in that, The multi-channel high-precision overlay error detection system according to any one of claims 1 to 2 is used to measure the angle mounting error and focusing distance of the chip under test, including: B1: The laser of the first channel is projected by the multi-channel light source module, passes through the measurement module to the chip under test, is reflected on the chip under test, passes through the measurement module again, and is imaged on the imaging module; B2: The laser of the second channel is projected by the multi-channel light source module, passes through the measurement module to the chip under test, is reflected on the chip under test, passes through the measurement module again, and is imaged on the imaging module; B3: The calculation module calculates the angle installation error and focusing distance of the chip under test based on the imaging data on the imaging module in steps B1 and B2, and corrects the position of the stage module based on the angle installation error and focusing distance of the chip under test.

8. The multi-channel high-precision overlay correction method according to claim 7, characterized in that, Step B3 specifically involves: B31: Based on the imaging data from the imaging module described in step B1, the following formula can be obtained: In the formula, This represents the angle between the laser beam from the first channel of the chip under test and the normal to the chip under test under ideal conditions. This indicates the angular mounting error of the chip under test, where k is the scaling factor and H is the focusing distance of the chip under test. and The distance between the imaging point and the center point on the image plane of the imaging module when the laser of the first channel is projected by the multi-channel light source module and is symmetrical about the normal of the chip under test. B32: Based on the imaging data from the imaging module described in step B2, the following formula can be obtained: In the formula, This represents the angle between the laser beam from the second channel of the chip under test and the normal to the chip under test under ideal conditions. and The distance between the imaging point and the center point on the image plane of the imaging module when the second channel laser is projected by the multi-channel light source module; B33: The calculation module calculates the angle installation error of the chip under test based on the formulas in steps B31 and B32. The position of the stage module is corrected based on the angle installation error of the chip under test and the focusing distance H.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the steps of the multi-channel high-precision overlay correction method as described in claim 7 or 8.

Images