Film inspection method, film inspection system, and storage medium

Abstract

The application provides a film detection method, a film detection system and a computer readable storage medium. The film detection method comprises the following steps: obtaining the base elastic modulus, the base Poisson's ratio, the base thickness of a sample to be detected, and a first curvature radius of at least one preset position on the surface of the sample to be detected before film coating; obtaining the film thickness of the sample to be detected and a second curvature radius of the at least one preset position after film coating; and determining the film residual stress of the at least one preset position according to the base elastic modulus, the base Poisson's ratio, the base thickness, the film thickness, the first curvature radius and the second curvature radius. By capturing the local film morphology at a fixed point, the application can detect the local film residual stress at each position of the film, thereby improving the flexibility, reliability and detection accuracy of the film detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the processing technology of semiconductor devices, in particular to a thin film detection method, a thin film detection system, and a computer readable storage medium. BACKGROUND

[0002] The residual stress of thin film is a common phenomenon in the process of preparing thin film of semiconductor devices, which is caused by the thermal expansion coefficient of different thin film and substrate materials during the heating and cooling process of preparing thin film, and by the non-equilibrium of thin film growth process and the specific microstructure of thin film. The residual stress of thin film is closely related to the material of thin film and substrate, the preparation method and process of thin film.

[0003] The residual stress of thin film has a great influence on the structure and performance of thin film, so it is necessary to control and detect the residual stress of thin film during the preparation process of thin film. This is of great significance to control the process parameters of thin film preparation and the yield, and is also an effective means to check the product quality and improve the manufacturing process. However, the existing thin film detection method can only be based on the substrate bending method to make one-dimensional linear sampling on the surface of the center area of thin film and calculate the stress distribution on the center line, but it cannot capture the local topography of the warping of the rest area of thin film, so it is not suitable for the detection of local stress mutation phenomenon.

[0004] In order to overcome the above-mentioned defects existing in the prior art, there is an urgent need in the field for an improved thin film detection method for detecting the local residual stress of thin film at each position by fixed point, so as to improve the flexibility, reliability and detection accuracy of thin film detection. SUMMARY

[0005] The following gives a brief overview of one or more aspects to provide a basic understanding of these aspects. This overview is not an extensive overview of all contemplated aspects, and is not intended to identify key or critical elements of all aspects or to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0006] In order to overcome the above-mentioned defects existing in the prior art, the present application provides a thin film detection method, a thin film detection system and a computer readable storage medium, which can capture the local topography of thin film by fixed point, detect the two-dimensional residual stress of thin film by fixed point, so as to improve the flexibility, reliability and accuracy of thin film detection.

[0007] In particular, the film detection method according to the first aspect of the present application comprises the following steps: obtaining the substrate elastic modulus, the substrate Poisson's ratio, the substrate thickness of the sample to be measured, and the first curvature radius of the X direction and the Y direction of at least one preset position on the surface of the sample to be measured before coating; obtaining the film thickness of the sample to be measured, and the second curvature radius of the X direction and the Y direction of at least one preset position on the surface of the sample to be measured after coating; and determining the residual stress of the film at the at least one preset position according to the substrate elastic modulus, the substrate Poisson's ratio, the substrate thickness, the film thickness, the first curvature radius of the X direction and the Y direction, and the second curvature radius of the X direction and the Y direction.

[0008] Further, in some embodiments of the present application, the step of obtaining the substrate elastic modulus and / or the substrate Poisson's ratio comprises determining the substrate elastic modulus and / or the substrate Poisson's ratio according to the substrate material of the sample to be measured, and / or the step of obtaining the substrate thickness comprises scanning the sample to be measured before coating via an autofocus system to determine the substrate thickness of the sample to be measured, and / or the step of obtaining the film thickness comprises scanning the sample to be measured after coating via an ellipsometry system to determine the film thickness of the surface of the sample to be measured.

[0009] Further, in some embodiments of the present application, the step of scanning the sample to be measured before coating via an autofocus system to determine the substrate thickness of the sample to be measured comprises determining the Z coordinate of at least one preset position on the surface of the sample to be measured before coating via the autofocus system, and determining the substrate thickness of the sample to be measured according to the Z coordinate of the at least one preset position and the original Z coordinate of the sample holder tray on which the sample to be measured is not placed.

[0010] Further, in some embodiments of the present application, the step of scanning the sample to be measured after coating via an ellipsometry system to determine the film thickness of the surface of the sample to be measured comprises providing an incident light with a known polarization state to the surface of the sample to be measured after coating via the ellipsometry system; collecting the reflected light after processing by a polarizer via a detector configured in the ellipsometry system; and fitting and calculating the film thickness of the surface of the sample to be measured according to the measured spectrum of the reflected light collected by the detector, and in combination with the simulated spectrum calculated according to the theoretical model of the sample to be measured and the system parameters of each optical element.

[0011] Furthermore, in some embodiments of the present invention, the step of obtaining the first curvature radius along the X direction and the Y direction and / or the second curvature radius along the X direction and the Y direction includes: collecting the Z coordinate of at least one first position on the surface of the sample to be tested, and the Z coordinates of multiple second positions near each first position; performing quadratic surface fitting based on the Z coordinate of each first position and the Z coordinates of multiple second positions near each first position to respectively determine the local surface equation of each first position; and determining the first-order derivative z′ of the Z coordinate of the corresponding first position along the X direction based on each local surface equation. x and the second-order derivative z″ xx , and the first derivative z′ of the Z coordinate along the Y direction y and the second-order derivative z″ yy According to the first-order derivative z' along the X direction x and the second-order derivative z″ xx , determine the first curvature radius R in the X direction of the coating front at the first position s (i, X) and / or the second radius of curvature R f (i, X); and according to the first-order derivative z′ along the Y direction y and the second-order derivative z″ yy , determine the first curvature radius R of the coating front in the Y direction at the first position s (i, Y) and / or the second radius of curvature R f (i,Y).

[0012] Furthermore, in some embodiments of the present invention, the step of obtaining the first curvature radius along the X direction and the Y direction includes: collecting at least one first position (x i ,y i ) Z coordinate before coating Pre_Z i , and each of the first positions (x i ,y i ) before coating at multiple second positions near According to each of the first positions (x i ,y i ) Z coordinate before coating Pre_Z i , and each of the first positions (x i ,y i ) before coating at multiple second positions near Perform quadratic surface fitting respectively to determine the first position (x i ,y i ) before coating; According to each of the first local surface equations, respectively determine the corresponding first position (x i ,yi ) Z coordinate before coating Pre_Z i First derivative along the X direction and the second-order derivative and the Z coordinate Pre_Z i First derivative along the Y direction and the second-order derivative According to the first-order derivative along the X direction and the second-order derivative Determine the first curvature radius R of the coating front in the X direction at the first position s (i, X); and according to the first-order derivative along the Y direction and the second-order derivative Determine the first curvature radius R of the coating front in the Y direction at the first position s (i,Y).

[0013] Furthermore, in some embodiments of the present invention, the step of obtaining the second curvature radius along the X direction and the Y direction includes: collecting the at least one first position (x i ,y i ) Z coordinate after coating Post_Z i , and each of the first positions (x i ,y i ) after coating at multiple second locations near According to each of the first positions (x i ,y i ) Z coordinate after coating Post_Z i , and each of the first positions (x i ,y i ) after coating at multiple second locations near Perform quadratic surface fitting respectively to determine the first position (x i ,y i ) after coating; According to each of the second local surface equations, the corresponding first position (x i ,y i ) Z coordinate after coating Post_Z i First derivative along the X direction and the second-order derivative And the Z coordinate Post_Z after the coating i First derivative along the Y direction and the second-order derivative According to the first-order derivative along the X direction and the second-order derivative Determine the second curvature radius R along the X direction after coating at the first position f(i, X); and according to the first-order derivative along the Y direction and the second-order derivative Determine the second curvature radius R along the Y direction after coating at the first position f (i,Y).

[0014] Furthermore, in some embodiments of the present invention, the step of determining the film stress at the at least one predetermined position based on the substrate elastic modulus, the substrate Poisson's ratio, the substrate thickness, the film thickness, the first curvature radius along the X direction and the Y direction, and the second curvature radius along the X direction and the Y direction comprises: calculating the inverse of the second curvature radius along the X direction after the film is deposited at the first position; The reciprocal of the first curvature radius in the X direction of the coating front at the first position ; determining the residual stress σ(i, X) of the film along the X direction at the first position according to the elastic modulus of the substrate, the Poisson's ratio of the substrate, the thickness of the substrate, the thickness of the film, and the first difference; calculating the reciprocal of the second radius of curvature along the Y direction after coating the first position The reciprocal of the first curvature radius in the Y direction of the coating front at the first position according to the substrate elastic modulus, the substrate Poisson's ratio, the substrate thickness, the film thickness, and the second difference, determining the first position along the Y direction of the film residual stress σ (i, Y).

[0015] Furthermore, in some embodiments of the present invention, after determining the film residual stress at the at least one preset position, the film detection method further includes the following steps: determining the film residual stress distribution of the sample to be tested after coating based on the film residual stresses at multiple preset positions; and determining the performance of the sample to be tested based on the film residual stress distribution, wherein the performance is selected from at least one of optical performance, electrical performance, magnetic performance, and mechanical performance.

[0016] Furthermore, the thin film inspection system provided according to the second aspect of the present invention includes a memory and a processor. The memory stores computer instructions. The processor is connected to the memory and configured to execute the computer instructions stored in the memory to implement the thin film inspection method provided by the first aspect of the present invention.

[0017] Further, in some embodiments of the present application, the film detection system further comprises a sample carrier and a detector. The processor is connected to the sample carrier and the detector, and is configured to: carry and translate the sample to be detected via the sample carrier; detect at least one third position on the sample to be detected via the detector; and determine the substrate thickness of the sample to be detected, the film thickness of the surface of the sample to be detected, the first curvature radius of at least one preset position on the surface of the sample to be detected before coating, and / or the second curvature radius of the at least one preset position on the surface of the sample to be detected after coating according to the detection data of the at least one third position.

[0018] Further, in some embodiments of the present application, the film detection system further comprises an auto-focusing system and / or an ellipsometry system. The processor is further configured to: determine the substrate thickness of the sample to be detected, the first curvature radius of at least one preset position on the surface of the sample to be detected before coating, and / or the second curvature radius of the at least one preset position on the surface of the sample to be detected after coating according to first detection data collected by a first detector configured in the auto-focusing system; and / or determine the film thickness of the surface of the sample to be detected according to second detection data collected by a second detector configured in the ellipsometry system.

[0019] In addition, the above computer readable storage medium according to the third aspect of the present application has computer instructions stored thereon. When the computer instructions are executed by a processor, the film detection method according to the first aspect of the present application is implemented. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above features and advantages of the present application can be better understood by reading the following detailed description of embodiments of the present application in conjunction with the drawings, in which: In the drawings, components are not necessarily drawn to scale, and components of similar or identical function or structure can be designated with like reference numerals or symbols.

[0021] Figure 1 A structural schematic diagram of a film detection system according to some embodiments of the present application is shown.

[0022] Figure 2 A flowchart of a film detection method according to some embodiments of the present application is shown.

[0023] Figure 3 A film surface scanning point diagram of a sample to be detected according to some embodiments of the present application is shown.

[0024] Figure 4 A surface coordinate distribution diagram of a sample to be detected before coating according to some embodiments of the present application is shown.

[0025] Figure 5A schematic diagram of warping of a sample to be measured is shown according to some embodiments of the present application.

[0026] Figure 6 A surface coordinate distribution diagram of a sample to be measured after coating is shown according to some embodiments of the present application.

[0027] Figure 7 A stress fold line diagram of all scanning points of a sample to be measured along the X direction is shown according to some embodiments of the present application.

[0028] Figure 8 A stress fold line diagram of all scanning points of a sample to be measured along the Y direction is shown according to some embodiments of the present application.

[0029] Figure 9 A stress distribution diagram of a film surface of a sample to be measured along the X direction is shown according to some embodiments of the present application.

[0030] Figure 10 A stress distribution diagram of a film surface of a sample to be measured along the Y direction is shown according to some embodiments of the present application.

[0031] Figure 11 A schematic diagram of two-dimensional stress is shown according to some embodiments of the present application.

[0032] Figure 12 A comparison diagram of one-dimensional stress detection and two-dimensional stress detection is shown according to some embodiments of the present application.

[0033] Figure 13 A comparison diagram of one-dimensional stress detection results and two-dimensional stress detection results is shown according to some embodiments of the present application. DETAILED DESCRIPTION

[0034] Other advantages and effects of the present application can be easily understood by those skilled in the art from the content disclosed in the present specification. Although the present application will be described in conjunction with the preferred embodiments, the features of the present application are not limited to the embodiments. On the contrary, the purpose of introducing the embodiments is to cover other alternatives or modifications based on the claims of the present application. In order to provide a deep understanding of the present application, many specific details will be included in the following description. The present application can also be implemented without using these details. In addition, in order to avoid confusion or obscure the present application, some specific details will be omitted in the description.

[0035] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0036] Furthermore, the terms "upper," "lower," "left," "right," "top," "bottom," "horizontal," and "vertical" used in the following description should be understood to refer to the orientations depicted in that section and the accompanying drawings. These relative terms are used solely for convenience of description and do not necessarily imply that the devices described herein must be manufactured or operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0037] It will be understood that although the terms "first," "second," "third," etc. may be used herein to describe various components, regions, layers, and / or portions, these components, regions, layers, and / or portions should not be limited by these terms, and these terms are merely used to distinguish different components, regions, layers, and / or portions. Thus, a first component, region, layer, and / or portion discussed below may be referred to as a second component, region, layer, and / or portion without departing from some embodiments of the present invention.

[0038] As mentioned above, existing thin film detection methods can only perform one-dimensional linear sampling on the surface of the central area of ​​the film based on the substrate bending method and calculate the stress distribution on the center line, but cannot capture the local morphology of the film warping in the remaining areas. Therefore, it is not suitable for the detection of local stress mutation phenomena.

[0039] In order to overcome the above-mentioned defects of the prior art, the present invention provides a thin film detection method, a thin film detection system and a computer-readable storage medium, which can capture the local morphology of the thin film by fixed point and detect the two-dimensional residual stress at each position of the thin film, thereby improving the flexibility, reliability and detection accuracy of the thin film detection.

[0040] In some non-limiting embodiments, the thin film detection method provided in the first aspect of the present invention can be implemented based on the thin film detection system provided in the second aspect of the present invention. Specifically, the thin film detection system can be configured with a memory and a processor. The memory includes, but is not limited to, the computer-readable storage medium provided in the third aspect of the present invention, which stores computer instructions. The processor is connected to the memory and configured to execute the computer instructions stored in the memory to implement the thin film detection method provided in the first aspect of the present invention.

[0041] Further, refer to Figure 1 . Figure 1 A structural schematic diagram of a thin film detection system according to some embodiments of the present application is shown.

[0042] In Figure 1 In the embodiment shown, the thin film detection system according to the present application further comprises a sample carrier 101 and a detector 102. Here, the sample carrier 101 can be a three-axis high-precision motion platform configured to translate along the X-axis, Y-axis and Z-axis directions, and is configured to carry a sample 103 to be measured and translate the sample 103 along the X-axis, Y-axis and Z-axis directions to cooperate with the detector 102 to collect detection data of the sample 103 to be measured. The detector 102 is configured to collect the detection data of the sample 103 to be measured to determine various measurement parameters of the sample 103 to be measured.

[0043] In some embodiments, the detector 102 can comprise a camera and a four-quadrant detector configured in an auto focus system. The auto focus system can move to any point along the X-axis and Y-axis directions with an error less than 1 micrometer, and after focusing, the measurement accuracy along the Z-axis can reach 0.2 micrometer, so that the local image and Z coordinate of the sample 103 to be measured can be accurately collected to determine the substrate thickness of the sample 103 to be measured, the first curvature radius of at least one preset position on the surface of the sample 103 to be measured along the X-axis and Y-axis directions before coating, and / or the second curvature radius of the at least one preset position along the X-axis and Y-axis directions after coating.

[0044] In addition, in some embodiments, the detector 102 can further comprise a spectrometer configured in an ellipsometry system, and is configured to collect a spectrum signal reflected by the sample 103 to be measured to determine the thin film thickness of the surface of the sample 103 to be measured.

[0045] Therefore, the thin film detection system according to the present application can carry the sample 103 to be measured by the sample carrier 101, and drive the sample 103 to be measured to translate along the X-axis and / or Y-axis directions to move at least one sampling position on the sample 103 to the sampling area of the detector 102, so that the local image and Z coordinate of the at least one position on the sample 103 can be collected by the detector 102. Then, the thin film detection system can determine the substrate thickness of the sample 103 to be measured, the thin film thickness of the surface of the sample 103 to be measured, the first curvature radius of at least one preset position on the surface of the sample 103 to be measured before coating, and / or the second curvature radius of the at least one preset position after coating according to the local image and Z coordinate of the at least one position, and determine the residual stress of the thin film of at least one preset position on the surface of the sample 103 to be measured according to the substrate elastic modulus, the substrate Poisson's ratio, the substrate thickness, the thin film thickness, the first curvature radius along the X-axis and Y-axis directions, and the second curvature radius along the X-axis and Y-axis directions.

[0046] The working principle of the film detection system will be described below in combination with some embodiments of film detection methods. Those skilled in the art can understand that the embodiments of the film detection methods are only some non-limiting embodiments provided by the present application, which are intended to clearly show the main concept of the present application and provide some specific schemes for facilitating the public to implement, but not to limit the overall function or overall working mode of the film detection system. Similarly, the film detection system is also only a non-limiting embodiment provided by the present application, which does not limit the execution subject and execution order of each step in the film detection methods.

[0047] Please refer to Figure 2 , Figure 2 The flowchart of the film detection method provided by some embodiments of the present application is shown.

[0048] As Figure 2 shown, in the process of film detection, the film detection system can first obtain the substrate elastic modulus, substrate Poisson's ratio, substrate thickness of the sample to be tested 103, and the first curvature radius of at least one preset position on the surface of the sample to be tested 103 before film coating.

[0049] Specifically, the substrate elastic modulus and / or the substrate Poisson's ratio can be determined according to the substrate material of the sample to be tested 103. For example, for a substrate made of silicon material, the technician can look up the table to determine that the substrate elastic modulus is 130 GPa and the substrate Poisson's ratio is 0.28.

[0050] In addition, the above-mentioned substrate thickness can be pre-calibrated or measured and determined by the film detection system online. Specifically, in response to not obtaining the pre-calibrated substrate thickness data, the film detection system can perform five-point focusing on the center, front end, rear end, left end, right end and other preset positions of the sample to be tested 103 via the four-quadrant detector configured in the autofocus system, to scan the Z coordinates z j of the above-mentioned preset positions on the surface of the sample to be tested 103 before film coating, and determine the substrate thickness of the sample to be tested 103 according to the difference between the average value z j of the Z coordinates z and the original Z coordinate z0 of the surface of the object tray.

[0051] In addition, please refer to Figure 3 and Figure 4 . Figure 3 The film surface scanning point diagram of the sample to be tested provided by some embodiments of the present application is shown. Figure 4 The surface coordinate distribution diagram of the sample to be tested before film coating provided by some embodiments of the present application is shown.

[0052] As Figure 3 ​As shown, in the process of determining the first curvature radius of the coating front in the X and Y directions at at least one preset position on the surface of the sample 103 to be tested, the thin film inspection system can first scan the at least one preset position 1-81 on the surface of the sample 103 to be tested via a camera configured in the autofocus system to collect Z coordinate data of the at least one preset position 1-81 before coating, and then calculate the first curvature radius of the coating front in the X and Y directions at at least one preset position on the surface of the sample 103 to be tested based on the Z coordinate data of each preset position 1-81 before coating and the Z coordinate data of the remaining positions around it.

[0053] Specifically, Figure 4 Taking the i-th preset position (1≤i≤81) in the example, the film detection system can first collect the first position (x i ,y i ) Z coordinate before coating Pre_Z i , and collect the surface distance of the sample to be tested 103 from the first position (x i ,y i ) of the plane distance of the nearest N (for example: N = 9) second positions (including the first position) before coating

[0054] Afterwards, the film detection system can detect the first position (x i ,y i ) and the Z coordinates of multiple second positions nearby The Levenberg-Marquardt algorithm is used to perform quadratic surface fitting to determine the first position (x i ,y i )’s first local surface equation:

[0055] z1=a1x 2 +b1y 2 +c1x+d1y+e1

[0056] Here, a1, b1, c1, d1, and e1 are the coefficients of the first local surface equation obtained by fitting.

[0057] Then, the film detection system can determine the first position (x i ,y i ) Z coordinate before coating Pre_Z i First derivative along the X direction and the second-order derivative And the Z coordinate Pre_Z before coating i First derivative along the Y direction and the second-order derivative

[0058]

[0059]

[0060] and further calculate the first curvature radius of the first position (x i ,y i ) in the X direction and the Y direction of the film front edge:

[0061]

[0062]

[0063] Similarly, the film detection system can determine the first curvature radius of each preset position 1-81 on the surface of the sample 103 in the X direction and the Y direction of the film front edge, which will not be repeated here.

[0064] After that, please refer to Figure 5 , Figure 5 shows a schematic diagram of the warping phenomenon of the sample to be measured according to some embodiments of the present application.

[0065] As Figure 5 shown, after determining the substrate thickness and the first curvature radius of the sample 103 to be measured, the technician can coat the substrate 501 of the sample 103 to be measured with a film 502 to obtain a sample 500 after coating. At this time, because the thermal expansion coefficients of the film 502 and the substrate 501 are different, the film residual stress is inevitably generated during the heating and cooling process of preparing the film 502, and the non-equilibrium during the film growth and the unique microstructure of the film 502 will also cause the film residual stress, resulting in the warping phenomenon of the sample 500 to be measured.

[0066] In some embodiments, the film thickness on the surface of the sample 500 to be measured can be pre-calibrated or measured and determined online by the film detection system. Specifically, in response to not obtaining the pre-calibrated film thickness data, the film detection system can provide an incident light with a known polarization state to the surface of the sample 500 to be measured via the ellipsometry system, and collect the reflected light processed by the analyzer via the spectrometer configured in the ellipsometry system, and then calculate the film thickness on the surface of the sample 500 to be measured according to the measured spectrum collected by the spectrometer and the simulated spectrum calculated by combining the theoretical model of the sample to be measured and the system parameters of each optical element.

[0067] Specifically, in Figure 5Taking the sample 500 as an example, its base 501 material is silicon, the film 502 material is silicon dioxide, the wafer size is 8 inches, the substrate elastic modulus is 130 GPa, the substrate Poisson's ratio is 0.28, the substrate thickness is 723.872 μm, and the film thickness is 930 nm.

[0068] In addition, please refer to Figure 3 and Figure 6 . Figure 6 Surface coordinate distribution diagrams of the tested samples after coating according to some embodiments of the present invention are shown.

[0069] like Figure 3 As shown, in the process of determining the second curvature radius of at least one preset position on the surface of the sample 500 to be tested along the X and Y directions after coating, the thin film inspection system can again scan the at least one preset position 1-81 on the surface of the sample 500 to be tested via the camera configured in the autofocus system as described above to collect Z coordinate data of the at least one preset position 1-81 after coating, and then calculate the second curvature radius of at least one preset position on the surface of the sample 500 to be tested along the X and Y directions after coating based on the Z coordinate data of each preset position 1-81 after coating and the Z coordinate data of the remaining positions around it.

[0070] Specifically, continue to Figure 6 Taking the i-th preset position (1≤i≤81) in the example, the film detection system can first collect the first position (x i ,y i ) Z coordinate after coating Post_Z i , and collect the distance between the surface of the sample to be tested 500 and the first position (x i ,y i ) of the plane distance of the nearest N (for example: N = 9) second positions (including the first position) after coating

[0071] Afterwards, the film detection system can detect the first position (x i ,y i ) and the Z coordinates of multiple second positions near it after coating The Levenberg-Marquardt algorithm is used to perform quadratic surface fitting to determine the first position (x i ,y i )The second local surface equation after coating:

[0072] z2=a2x 2 +b2y 2 +c2x+d2y+e2

[0073] Here, a2, b2, c2, d2, e2 are the coefficients of the second local surface equation obtained by fitting.

[0074] After that, the thin film detection system can determine the Z coordinate Post_Z i of the first position (x i ,y i ) after coating according to the second local surface equation, and the first order derivative and the second order derivative of the Z coordinate Post_Z i along the X direction and the Y direction.

[0075]

[0076]

[0077] Further, the thin film detection system can calculate the second curvature radius of the first position (x s ,y f ) after coating along the X direction and the Y direction:

[0078]

[0079]

[0080] Please continue to refer to Figure 2 , after determining the substrate elastic modulus, substrate Poisson's ratio, substrate thickness, film thickness, first curvature radius along the X direction and Y direction, and second curvature radius along the X direction and Y direction of the sample to be tested 500, the thin film detection system can substitute them into the two-dimensional expansion of the Stoney formula of the present application to calculate the film residual stress of at least one preset position 1-81 on the sample to be tested 500 along the X direction and the Y direction respectively:

[0081]

[0082]

[0083] Wherein, E is the substrate elastic modulus of the sample to be tested 500, v is the substrate Poisson's ratio of the sample to be tested 500, t is the substrate thickness of the sample to be tested 500, t

[0001] is the film thickness of the sample to be tested 500.

[0084] Please refer to Figures 7 to 10 . Figure 7 The stress broken line graph of all scanning points of the sample to be tested along the X direction provided according to some embodiments of the present application is shown. Figure 8 ​A stress broken line graph of all scanning points of the sample to be measured along the Y direction is shown. Figure 9 A stress distribution graph of the film surface of the sample to be measured along the X direction is shown. Figure 10 A stress distribution graph of the film surface of the sample to be measured along the Y direction is shown.

[0085] As Figures 7 to 10 shown, by adopting the above hardware and software configurations, the film detection method, the film detection system and the computer readable storage medium provided by the present application can capture the local topography of each position of the film through fixed-point detection, thereby detecting the local film residual stress of each position of the film, so as to improve the flexibility, reliability and detection accuracy of the film detection.

[0086] Further, in some embodiments, after determining the film residual stress of at least one preset position, the film detection system provided by the present application can further determine the film residual stress distribution of the sample to be measured after film coating according to the film residual stress of the plurality of preset positions, and determine the optical performance, electrical performance, magnetic performance and / or mechanical performance of the sample to be measured according to the film residual stress distribution.

[0087] For example, in the optical measurement of the film thickness, the spectral information of the film needs to be collected by the ellipsometric measurement system to calculate the film thickness, and the optical performance of the sample to be measured directly affects the collection result of the spectrum. At this time, the film detection system can preferentially determine whether the film residual stress distribution is within the allowable range. If the film residual stress distribution is within the allowable range, the film detection system can determine that the film thickness measurement result is valid. Otherwise, if the film residual stress distribution exceeds the allowable range, the film detection system can determine that the film thickness measurement result is invalid.

[0088] Further, in order to analyze the principle difference and effect difference between the two-dimensional stress detection scheme disclosed by the present application and the conventional one-dimensional stress detection scheme, the present application provides a set of comparative examples of two-dimensional stress detection and one-dimensional stress detection of the same defect.

[0089] Please refer to Figures 11 to 13 . Figure 11 A schematic diagram of two-dimensional stress is shown according to some embodiments of the present application. Figure 12 A comparison diagram of one-dimensional stress detection and two-dimensional stress detection is shown according to some embodiments of the present application. Figure 13 A comparison diagram of one-dimensional stress detection result and two-dimensional stress detection result is shown according to some embodiments of the present application.

[0090] As Figure 11As shown in Figure 1, stress is a directional vector. For any given point on the surface of the sample to be tested, the stress along each direction can be different.

[0091] For example, for a point A on the surface of a sample to be tested, assuming the X and Y directions are chosen (actually, any direction can be chosen), the directions and magnitudes of stress 1 and stress 2 calculated from the curves at point A along the X and Y directions can be different. Therefore, the calculated results of film stress differ significantly between one-dimensional and two-dimensional testing scenarios.

[0092] Specifically, conventional one-dimensional testing in this field involves scanning the surface of the sample to be tested along the diameter direction, followed by curve fitting to calculate the curvature radius of the curve, thereby calculating the stress value of the measured point along the diameter direction.

[0093] Differently, the two-dimensional detection provided by the present invention can scan the heights (i.e., Z coordinates) of multiple measured points within any area of ​​the surface of the sample being tested, followed by two-dimensional surface fitting. Based on the fitted surface, the radius of curvature along any direction is calculated, thereby calculating the stress value in that direction. More specifically, for any given point, the present invention can scan within the vicinity of that point and fit the surface of that point's neighborhood based on the Z coordinates of its neighboring points, thereby calculating the stress value at that point along any direction.

[0094] from Figure 12 It can be seen that for point A on the surface of the sample to be tested, in conventional one-dimensional testing, only the surface curve along the diameter direction can be fitted, and thus only the stress value along the diameter direction can be calculated for that point. In contrast, in the two-dimensional testing solution provided by the present invention, a quadratic surface can be fitted within the neighborhood of point A to calculate the radius of curvature of point A along any direction, thereby calculating the stress value at point A along any direction, thus overcoming the limitations of stress calculation in one-dimensional situations.

[0095] Furthermore, since the surface of the wafer sample to be tested may usually have defects of different shapes such as sharp protrusions, depressions and wrinkles, causing a sudden increase or decrease in stress in the defect area. If conventional one-dimensional stress detection is used, it can only scan through the defect area along the diameter direction and cannot restore the characteristic shape in the defect area. In contrast, in the two-dimensional defect detection solution provided by the present invention, the two-dimensional local morphology of the entire defect area can be fitted by encrypting the scanning points in the defect area, so as to more closely simulate the actual defect situation to deal with extreme stress distribution situations.

[0096] Furthermore, if Figure 13As shown, for a point A in a surface defect region of a single-sided sample, a conventional one-dimensional detection scheme can only scan through the point A along the diameter direction, and obtain the cross-sectional shape of the defect region along the diameter of the point A, and then perform one-dimensional curve fitting and smoothing processing on the scanning result. This scanning method ignores the influence of the region around the point A, and is extremely easy to miss the actual defect peak value due to the deviation of the detection direction from the characteristic direction of the defect shape and the smoothing effect of curve fitting, thus having a large deviation from the actual shape and low defect stress calculation accuracy.

[0097] Conversely, in the above-mentioned two-dimensional detection scheme provided by the present application, the scanning is performed on the entire local region including the point A and a plurality of preset points adjacent to the point A, and the result of the quadratic surface fitting can reflect the shape of the local region, so that the stress calculation result is more accurate.

[0098] In addition, for the actual lowest point B in the figure, the tip has a high stress concentration. If the one-dimensional case does not scan through the point B, the maximum stress error of the calculation will be large. To put it another way, since the stress values of the defect in the point B are different in different directions, even if the one-dimensional detection scheme scans through the point B, it may also cause calculation error of the maximum stress due to the deviation of the diameter direction from the actual characteristic direction. Since the stress range directly affects the judgment of wafer goodness, if the stress value of the point A is less than the allowable stress threshold, and the maximum stress value of the point B is greater than the allowable stress threshold, the conventional one-dimensional detection scheme may cause a false judgment of the sample to be tested, and thus a non-conforming sample to be tested is judged as a conforming sample.

[0099] Conversely, as described above, in the above-mentioned two-dimensional detection scheme provided by the present application, as long as the point B is in the scanning region, the present application can obtain the shape of the entire local region by fitting the Z coordinates of the point A and its adjacent points, so as to accurately calculate the maximum stress value in the entire local region, thereby avoiding false judgment of the defect. Therefore, compared with the conventional one-dimensional detection scheme, the above-mentioned thin film detection method, thin film detection system and computer readable storage medium provided by the present application can detect the two-dimensional residual stress of the thin film by fixed-point detection, capture the local topography of the thin film warping, and thus improve the flexibility, reliability and accuracy of the thin film detection.

[0100] Although the above methods are illustrated and described as a series of acts for simplicity, it should be understood and appreciated that the methods are not limited by the order of acts, as some acts can occur in different orders and / or concurrently with other acts according to one or more embodiments.

[0101] Those skilled in the art will appreciate that information, signals, and data can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0102] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of film detection, characterized by, The method comprises the following steps: obtaining the substrate elastic modulus, the substrate Poisson's ratio, the substrate thickness of the sample to be measured, and the first curvature radius of the sample to be measured in the X direction and the Y direction before coating the film at at least one preset position on the surface of the sample to be measured; obtaining the film thickness of the sample to be measured, and the second curvature radius of the sample to be measured in the X direction and the Y direction after coating the film at the at least one preset position; calculating the first difference value between the reciprocal of the second curvature radius of the sample to be measured in the X direction after coating the film at the at least one first position and the reciprocal of the first curvature radius of the sample to be measured in the X direction before coating the film at the at least one first position; determining a first location of a residual stress in the thin film along the X direction based on the substrate modulus of elasticity, the substrate Poisson's ratio, the substrate thickness, the thin film thickness, and the first difference ; calculating the second difference value between the reciprocal of the second curvature radius of the sample to be measured in the Y direction after coating the film at the at least one first position and the reciprocal of the first curvature radius of the sample to be measured in the Y direction before coating the film at the at least one first position; and The step of obtaining the substrate elastic modulus and / or the substrate Poisson's ratio comprises: determining the substrate elastic modulus and / or the substrate Poisson's ratio according to the substrate material of the sample to be measured, and / or determining a film residual stress in the Y direction at the first location based on the substrate modulus of elasticity, the substrate poisson's ratio, the substrate thickness, the film thickness, and the second difference .

2. The film inspection method of claim 1, wherein The step of obtaining the substrate thickness comprises: scanning the sample to be measured before coating the film via an autofocus system to determine the substrate thickness of the sample to be measured, and / or The step of obtaining the film thickness comprises: scanning the sample to be measured after coating the film via an ellipsometry system to determine the film thickness of the sample to be measured. The step of scanning the sample to be measured before coating the film via an autofocus system to determine the substrate thickness of the sample to be measured comprises:

3. The film inspection method of claim 2, wherein determining the Z coordinates of at least one preset position on the surface of the sample to be measured before coating the film via the autofocus system; and determining the substrate thickness of the sample to be measured according to the Z coordinates of the at least one preset position and the original Z coordinates of a sample holder on which the sample to be measured is not placed. The step of scanning the sample to be measured after coating the film via an ellipsometry system to determine the film thickness of the sample to be measured comprises:

4. The film inspection method of claim 2, wherein providing an incident light with a known polarization state to the surface of the sample to be measured after coating the film via the ellipsometry system; collecting the reflected light after processing by a polarizer via the sample to be measured via a detector configured in the ellipsometry system; and fitting and calculating the film thickness of the sample to be measured according to the measured spectrum of the reflected light collected by the detector and in combination with a simulated spectrum calculated according to a theoretical model of the sample to be measured and system parameters of each optical element. The step of obtaining the first curvature radius in the X direction and the Y direction and / or the second curvature radius in the X direction and the Y direction comprises:

5. The method of claim 1, wherein the film is a film for a liquid crystal display device. collecting the Z coordinates of the at least one first position and the Z coordinates of a plurality of second positions near each of the first positions; respectively performing quadratic surface fitting according to the Z coordinates of each of the first positions and the Z coordinates of the plurality of second positions near each of the first positions to respectively determine the local surface equations of each of the first positions; The step of obtaining the first curvature radius in the X direction and the Y direction comprises: According to each of the local surface equations, a first derivative of a Z coordinate of the corresponding first position along an X direction and a second derivative , and a first derivative of the Z coordinate along a Y direction and a second derivative are determined, respectively. According to the first-order derivative along the X direction and the second-order derivative , determine the first curvature radius of the coating front in the X direction at the first position , and / or the second curvature radius along the X direction after coating at the first position ;as well as According to the first derivative along the Y direction and the second derivative along the Y direction , a first radius of curvature along the Y direction before the first position is plated , and / or a second radius of curvature along the Y direction after the first position is plated .

6. The thin film detection method according to claim 5, wherein: The step of obtaining the second curvature radius in the X direction and the Y direction comprises: Collecting at least one first position on the surface of the sample to be tested Z coordinate before coating And the Z coordinate before coating of a plurality of second positions near each first position And the Z coordinate before coating of a plurality of second positions near each first position ; According to the Z coordinates of the first positions before film coating , and the Z coordinates of a plurality of second positions near the first positions before film coating , quadratic surface fitting is respectively performed to determine the first local surface equations of the first positions before film coating According to each of the first partial surface equations, a corresponding first position is determined Z coordinate before coating First derivative in the X direction and second derivative and the Z coordinate First derivative in the Y direction and second derivative ; According to the first derivative along the X direction and the second derivative , a first radius of curvature of the first position along the X direction before coating is determined ; and According to the first derivative along the Y direction and the second derivative along the Y direction , a first radius of curvature of the first position along the Y direction before coating is determined .

7. The thin film detection method according to claim 5, wherein: After determining the residual stress of the film at the at least one preset position, the film detection method further comprises the following steps: Acquiring the at least one first position Z coordinate after coating , and each of the first positions Z coordinates of multiple nearby second positions after coating ; According to each of the first positions Z coordinate after coating , and each of the first positions Z coordinates of multiple nearby second positions after coating , respectively perform quadratic surface fitting to determine the first positions of each The second local surface equation after coating; According to each of the second partial surface equations, a corresponding first position is determined Z coordinate after coating First derivative in the X direction and second derivative and the Z coordinate after coating First derivative in the Y direction and second derivative ; According to the first derivative along the X direction and the second derivative , a second curvature radius of the first position after coating along the X direction is determined ; and According to the first derivative along the Y direction and the second derivative , a second radius of curvature along the Y direction after the first position is coated is determined .

8. The method of claim 1, wherein the film is a film for a display device. ​ determine a film residual stress distribution of the sample to be measured according to the film residual stress of the plurality of preset positions; and determine a performance of the sample to be measured according to the film residual stress distribution, wherein the performance is at least one of optical performance, electrical performance, magnetic performance, and mechanical performance.

9. A film inspection system characterized by, comprise: a memory having computer instructions stored thereon; and a processor connected to the memory and configured to execute the computer instructions stored on the memory to implement the film detection method according to any one of claims 1-8.

10. The film inspection system of claim 9, wherein, The film detection system further comprises a sample holder and a detector, and the processor is connected to the sample holder and the detector and is configured to: carry and translate the sample to be measured via the sample holder; detect at least one third position on the sample to be measured via the detector; and determine a substrate thickness of the sample to be measured, a film thickness on the surface of the sample to be measured, a first radius of curvature of at least one preset position on the surface of the sample to be measured before film deposition, and / or a second radius of curvature of the at least one preset position after film deposition according to detection data of the at least one third position.

11. The film inspection system of claim 10, wherein, The film detection system further comprises an autofocus system and / or an ellipsometry system, and the processor is further configured to: determine a substrate thickness of the sample to be measured, a first radius of curvature of at least one preset position on the surface of the sample to be measured before film deposition, and / or a second radius of curvature of the at least one preset position after film deposition according to first detection data collected by a first detector configured in the autofocus system; and / or determine a film thickness on the surface of the sample to be measured according to second detection data collected by a second detector configured in the ellipsometry system. The computer instructions are executed by the processor to implement the film detection method according to any one of claims 1-8.

12. A computer readable storage medium having stored thereon computer instructions, wherein, ​

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