Method, device, medium and equipment for fine calibration of azimuth angle of a measuring device

Abstract

In a method, device, medium, and equipment for fine calibration of the azimuth angle of a measurement device provided in this specification, the measurement device includes a measurement optical path unit, a polarizer, a detector, and a Fourier ellipsometry processing unit. Adjust the measurement optical path unit to provide incident light to enter the grating area of the sample to be measured. Adjust the polarizer to convert the incident light into polarized light with the polarization direction of the electric field vector perpendicular to the incident plane and parallel to the surface of the sample to be measured. The detector collects the outgoing optical signal, and the Fourier ellipsometry processing unit provides the Fourier coefficients corresponding to the optical signal. Change the angle of the azimuth angle, record the Fourier coefficients at different azimuth angles, and then determine the angle corresponding to the peak value of the sine term coefficient or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients as the fine calibration angle. Taking the fine calibration angle as the target, calibrate the azimuth angle of the measurement device, thereby improving the accuracy of the azimuth angle and ensuring the accuracy of subsequent measurement of the optical critical dimensions of the sample to be measured.

Description

Technical Field

[0001] This specification relates to the field of semiconductor manufacturing, and particularly to a method, device, medium, and equipment for fine calibration of the azimuth angle of a measurement device. Background Art

[0002] In the field of semiconductor manufacturing, the Optical Critical Dimension (OCD) measurement technology is a non-contact measurement method, that is, the optical principle is used to measure the critical dimensions on the chip. With the progress of semiconductor manufacturing processes, the measurement accuracy requirements for optical critical dimensions are getting higher and higher. Therefore, in order to ensure the accuracy and reliability of the OCD measurement device, it is necessary to calibrate the OCD measurement device before use.

[0003] Currently, a standard wafer marked with a calibration pattern is generally used to calibrate the OCD measurement device. When calibrating with the standard wafer, the azimuth angle of the OCD measurement device is calibrated by adjusting and observing whether the calibration pattern on the standard wafer is aligned with the preset angle. Since the standard wafer and each sample to be measured have the same marked notch at the same position, after calibration, the standard wafer can be replaced with the sample to be measured based on the marked defect to perform the OCD measurement of the sample to be measured. However, the accuracy of calibrating the OCD device based on the standard wafer is poor, which affects the accuracy of the measurement results.

[0004] Based on this, this specification provides a method, device, medium, and equipment for fine calibration of the azimuth angle of a measurement device. Summary of the Invention

[0005] This specification provides a method, device, medium, and equipment for fine calibration of the azimuth angle of a measurement device to partially solve the above problems existing in the prior art.

[0006] This specification adopts the following technical solutions:

[0007] This specification provides a method for fine calibration of the azimuth angle of a measurement device. The measurement device includes a measurement optical path unit, a polarizer, a detector, and a Fourier ellipsometry processing unit, and includes:

[0008] Adjust the measurement optical path unit to provide incident light to enter the grating area on the surface of the sample to be measured. The angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle; adjust the polarizer so that the polarization direction of the electric field vector of the polarized light after the incident light passes through the polarizer is perpendicular to the incident plane and parallel to the surface of the sample to be measured;

[0009] Collect the optical signal exiting from the grating area through the detector, and provide the Fourier coefficients corresponding to the optical signal through the Fourier ellipsometry processing unit;

[0010] Change the angle of the azimuth angle and record the Fourier coefficients corresponding to the optical signal at different azimuth angles;

[0011] According to the recorded Fourier coefficients, determine the angle corresponding to the peak value where the sine term coefficient in the Fourier coefficients is equal to 1 or the valley value where the absolute value of the cosine term coefficient in the Fourier coefficients is equal to 0 as the fine calibration angle;

[0012] Taking the fine calibration angle as the target, calibrate the azimuth angle of the measuring device.

[0013] Optionally, the step of changing the angle of the azimuth angle specifically includes:

[0014] Rotate the sample to be measured according to a preset first step length until the rotation range reaches a preset angle range.

[0015] Optionally, the step of changing the angle of the azimuth angle specifically includes:

[0016] Within a preset angle range, rotate the sample to be measured according to a preset second step length, and the second step length is greater than the first step length;

[0017] Record the Fourier coefficients of the optical signal at each angle during the process of rotating the sample to be measured according to the second step length, and determine the angle corresponding to the peak value of the sine term coefficient in the Fourier coefficients or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients as the rough calibration angle;

[0018] According to the rough calibration angle, determine a fine rotation range, and the fine rotation range is smaller than the angle range;

[0019] Rotate the sample to be measured according to the first step length until the rotation range reaches the fine rotation range.

[0020] Optionally, the step of determining the fine rotation range according to the rough calibration angle specifically includes:

[0021] Determine the angle that differs from the rough calibration angle by the second step length as the boundary value;

[0022] According to the boundary value, determine the fine rotation range.

[0023] Optionally, the step of changing the angle of the azimuth angle specifically includes:

[0024] Determine the adjacent azimuth angles of the current azimuth angle of the incident light;

[0025] Determine the Fourier coefficients respectively corresponding to the optical signal at the current azimuth angle and the adjacent azimuth angles;

[0026] According to the magnitude relationship of each determined Fourier coefficient, determine the direction in which the sine term coefficient in the Fourier coefficient increases or the direction in which the absolute value of the cosine term coefficient in the Fourier coefficient decreases as the rotation direction.

[0027] Rotate the sample to be measured along the rotation direction starting from the current azimuth angle until the azimuth angle of the incident light after rotation reaches any boundary value in the preset angle range.

[0028] Optionally, the step of adjusting the measurement optical path unit specifically includes:

[0029] Determine a standard sheet marked with a calibration pattern.

[0030] Adjust the translation device in the measurement device that carries the standard sheet to place the standard sheet in a preset position.

[0031] According to the calibration pattern, adjust the azimuth angle of the incident light provided by the measurement optical path unit.

[0032] Replace the standard sheet with the sample to be measured according to the notch that is the same between the sample to be measured and the standard sheet.

[0033] Optionally, the method further includes:

[0034] Use the azimuth angle required for measuring the sample to be measured as the target azimuth angle.

[0035] Determine a target step size according to the fine calibration angle and the target azimuth angle.

[0036] Adjust the measurement device according to the target step size, and perform optical critical dimension measurement on the sample to be measured with the adjusted measurement device.

[0037] This specification provides an azimuth fine calibration device for a measurement device, including:

[0038] An optical path adjustment module for adjusting the measurement optical path unit to provide incident light to enter the grating area on the surface of the sample to be measured, where the angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle; adjusting the polarizer so that the polarization direction of the electric field vector of the polarized light after the incident light passes through the polarizer is perpendicular to the incident plane and parallel to the surface of the sample to be measured.

[0039] An acquisition module for acquiring the optical signal exiting from the grating area through the detector and providing the Fourier coefficient corresponding to the optical signal through the Fourier ellipsometry processing unit.

[0040] A rotation module, configured to change the angle of the azimuth angle and record the Fourier coefficients corresponding to the optical signal at different azimuth angles;

[0041] A fine calibration angle module, configured to determine, according to the recorded Fourier coefficients, the angle corresponding to the peak value of the sine term coefficient in the Fourier coefficients or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients as the fine calibration angle;

[0042] A calibration module, configured to calibrate the azimuth angle of the measuring device with the fine calibration angle as the target.

[0043] This specification provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a method for fine calibration of the azimuth angle of a measuring device.

[0044] This specification provides an electronic device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements a method for fine calibration of the azimuth angle of a measuring device.

[0045] The above at least one technical solution adopted in this specification can achieve the following beneficial effects: In a method for fine calibration of the azimuth angle of a measuring device provided in this specification, the measuring device includes a measuring optical path unit, a polarizer, a detector, and a Fourier ellipsometry processing unit. By adjusting the measuring optical path unit, an incident light can be provided to enter the grating area on the surface of the sample to be measured, and the angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle. By adjusting the polarizer, the polarization direction of the electric field vector of the polarized light after the incident light passes through the polarizer is perpendicular to the incident plane and parallel to the surface of the sample to be measured. Then, the detector is used to collect the optical signal exiting from the grating area, and the Fourier ellipsometry processing unit provides the Fourier coefficients corresponding to the optical signal. After that, the angle of the azimuth angle is changed, and the Fourier coefficients corresponding to the optical signal at different azimuth angles are recorded. According to the recorded Fourier coefficients, the angle corresponding to the peak value of the sine term coefficient in the Fourier coefficients or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients is determined as the fine calibration angle. Finally, with the fine calibration angle as the target, the azimuth angle of the measuring device is calibrated.

[0046] As can be seen from the above method, by changing the angle of the azimuth angle and recording the Fourier coefficients corresponding to the optical signal exiting at different azimuth angles, the angle corresponding to the peak value of the sine term coefficient in the Fourier coefficients or the valley value of the absolute value of the cosine term coefficient is used as the fine calibration angle, and with the fine calibration angle as the target, the azimuth angle of the incident light is calibrated, thereby improving the accuracy of the azimuth angle and ensuring the accuracy of subsequent measurement of the optical critical dimensions of the sample to be measured. Description of the Drawings

[0047] The accompanying drawings described herein are used to provide a further understanding of this specification and form a part of this specification. The schematic embodiments of this specification and their descriptions are used to explain this specification and do not constitute an improper limitation to this specification. In the accompanying drawings:

[0048] Figure 1 is a schematic flowchart of a method for fine calibration of the azimuth angle of a measuring device provided in this specification;

[0049] Figure 2 is a schematic diagram of a periodically distributed direction provided in this specification;

[0050] Figure 3 is a schematic diagram of a standard piece in rough calibration provided in this specification;

[0051] Figure 4 is a schematic diagram of the Fourier coefficients varying with the azimuth angle provided in this specification;

[0052] Figure 5 is a schematic diagram of a device for fine calibration of the azimuth angle of a measuring device provided in this specification;

[0053] Figure 6 is a schematic diagram of the structure of an electronic device corresponding to a method for fine calibration of the azimuth angle of a measuring device provided in this specification. Detailed embodiments

[0054] To make the purpose, technical solutions, and advantages of this specification clearer, the technical solutions of this specification will be clearly and completely described below in conjunction with the specific embodiments of this specification and the corresponding accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, rather than all the embodiments. Based on the embodiments in this specification, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this specification.

[0055] In the process of implementing a method for fine calibration of the azimuth angle of a measuring device in this specification, data processing and analysis are involved. Therefore, in the embodiments of this specification, the server can execute the process of the method for fine calibration of the azimuth angle of a measuring device. Of course, this specification does not limit which device executes the process of fine calibration of the azimuth angle of a measuring device. For example, it can be performed by devices such as personal computers and mobile terminals, or in actual production, the machine tool can also execute the process of fine calibration of the azimuth angle. For the convenience of description, the server is used as the execution entity for explanation below.

[0056] The following will detail the technical solutions provided in each embodiment of this specification in conjunction with the accompanying drawings.

[0057] Figure 1A flowchart of a method provided in this specification, including the following steps:

[0058] S100: Adjust the measurement optical path unit to provide incident light to enter the grating area on the surface of the sample to be measured. The angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle; adjust the polarizer so that the polarization direction of the electric field vector of the polarized light after the incident light passes through the polarizer is perpendicular to the incident plane and parallel to the surface of the sample to be measured.

[0059] In one or more embodiments of this specification, in order to collect the optical signal emitted from the grating area on the surface of the sample to be measured by the detector in the subsequent steps, and provide the Fourier coefficients corresponding to the optical signal through the Fourier ellipsometry processing unit to achieve fine calibration of the azimuth angle of the measuring device. In this step, the server needs to adjust the measurement optical path unit and the polarizer to generate a polarized light whose electric field vector has a polarization direction perpendicular to the incident plane and parallel to the surface of the sample to be measured.

[0060] Specifically, the server adjusts the measurement optical path unit in the measuring device to provide incident light to enter the grating area on the surface of the sample to be measured, and needs to adjust the polarizer so that the polarization direction of the electric field vector of the polarized light generated after the incident light passes through the polarizer is perpendicular to the incident plane and parallel to the surface of the sample to be measured. Among them, the angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle, and the measuring device at least includes a measurement optical path unit, a polarizer, a detector, and a Fourier ellipsometry processing unit.

[0061] It should be noted that the azimuth angle refers to the angle between the plane where the incident light is located (incident plane) and a certain reference direction on the surface of the sample to be measured. For a sample to be measured with a periodic structure (grating area), this reference direction is usually the periodic distribution direction of the grating area in the sample to be measured. In the case of a one-dimensional grating, the periodic distribution direction is unique. As Figure 2 shown, it is a schematic diagram of the grating area in the sample to be measured provided in this specification when the grating area is a one-dimensional grating. In this figure, the periodic distribution direction of the grating area in the sample to be measured is the X direction. Therefore, the azimuth angle of the incident light is the angle between the incident plane and the X direction. For the case of a two-dimensional grating, there are two mutually perpendicular periodic distribution directions, so a reference direction needs to be specified to clarify the meaning of the azimuth angle, such as the X direction. Of course, in this specification, the reference direction can be set according to actual needs.

[0062] Meanwhile, a polarizer is an optical element used to adjust the polarization state of light, that is, non-polarized light (where light waves vibrate randomly in all directions) can be converted into polarized light (where light waves vibrate in a specific direction) through the polarizer. In this step, the server adjusts the polarizer to convert the polarization direction of the incident light's electric field vector to be perpendicular to the incident plane and parallel to the surface of the sample to be measured, that is, the analysis angle is zero.

[0063] S102: Collect the optical signal exiting from the grating region through the detector, and the Fourier ellipsometry processing unit provides the Fourier coefficients corresponding to the optical signal.

[0064] In one or more embodiments of this specification, in order to record the Fourier coefficients corresponding to the optical signals exiting at different azimuth angles by adjusting the azimuth angle in subsequent steps. In this step, the server needs to collect the optical signal of the light exiting from this grating region through the detector, and the Fourier ellipsometry processing unit provides the Fourier coefficients corresponding to this optical signal.

[0065] Specifically, the server can collect the optical signal exiting from the grating region through the detector in the measuring device, and the Fourier ellipsometry processing unit in this measuring device provides the Fourier coefficients corresponding to this optical signal.

[0066] It should be noted that the detector is an optical element used to detect reflected light or transmitted light, and the Fourier ellipsometry processing unit is used to process the data collected by the detector and calculate the Fourier coefficients corresponding to the exiting optical signal.

[0067] S104: Change the angle of the azimuth angle and record the Fourier coefficients corresponding to the optical signal at different azimuth angles.

[0068] In one or more embodiments of this specification, in order to determine the fine calibration angle in subsequent steps, in this step, the server needs to change the angle of this azimuth angle and record the Fourier coefficients corresponding to the exiting optical signal at different azimuth angles.

[0069] Specifically, the server needs to change the angle of the azimuth angle and record the Fourier coefficients corresponding to the exiting optical signal at different azimuth angles.

[0070] It should be noted that in this specification, there is no limitation on the specific method of changing the azimuth angle, which can be set according to actual needs. For example, the measuring device includes a carrier for carrying the sample to be measured, and the sample to be measured is placed on the carrier. The server rotates the rotating device under the carrier to change the angle of the azimuth of the incident light. At the same time, in this specification, there is no limitation on the specific method of changing the azimuth angle, which can be set according to actual needs. In one or more embodiments of this specification, the server can rotate the sample to be measured according to a preset first step length, and record the Fourier coefficients corresponding to the emitted optical signals at different azimuth angles during the process of rotating the sample to be measured by the first step length. Among them, the first step length can be set according to the accuracy of actual needs, such as 1°, 0.1°, 0.01°, etc.

[0071] S106: Determine the angle corresponding to the peak value where the sine term coefficient in the Fourier coefficients is equal to 1 or the valley value where the absolute value of the cosine term coefficient in the Fourier coefficients is equal to 0 as the fine calibration angle according to the recorded Fourier coefficients.

[0072] In one or more embodiments of this specification, in order to achieve the fine calibration of the azimuth angle in the subsequent steps, in this step, the server needs to determine the angle corresponding to the peak value of the sine term coefficient or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients based on the recorded Fourier coefficients as the fine calibration angle.

[0073] Specifically, the server can determine the angle corresponding to the peak value of the sine term coefficient or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients based on the recorded Fourier coefficients as the fine calibration angle.

[0074] It should be noted that the Fourier expansion of the emitted optical signal is performed by the Fourier ellipsometry processing unit to obtain the Fourier coefficients of the expanded Fourier signal as follows:

[0075] Among them, represents the light intensity, represents the average light intensity without modulation, and is the sine term coefficient, is the cosine term coefficient, is the analysis angle.

[0076] The Mueller matrix is a 4*4 matrix that describes the change in the polarization state of light. This matrix can represent any linear or non-linear polarization transformation, including the influence of processes such as reflection, refraction, and scattering on the polarization state. M22 is the element in the second row and second column of the Mueller matrix. The Stokes quantity is used to describe the polarization state of light and has four components: represents the total intensity, which is the sum of all polarized light; is the difference between two orthogonal directions (horizontal and vertical) of linear polarization; The difference between the two diagonal directions of linearly polarized light (+45° and -45°); The difference between the left and right circular polarization components of circularly polarized light. The Mueller matrix corresponds to the response of the sample under test to the incident light, as follows:

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] Where, is the Stokes vector of the incident light, is the Stokes vector of the outgoing light, M is the Mueller matrix of the response of the sample under test to the incident light, represents linearly polarized light in the x direction, represents linearly polarized light in the y direction, represents linearly polarized light with a polarization direction along 45°, represents linearly polarized light with a polarization direction along -45°, represents right-handed polarization, represents left-handed polarization.

[0083] That is, by collecting the Stokes vectors of the incident light and the outgoing light, the Mueller matrix of the sample under test can be determined. The Mueller matrix is as follows:

[0084]

[0085] For polarized light, the response of the sample under test to the incident light can be described by the Jones matrix, as follows:

[0086]

[0087] That is, the following formula:

[0088]

[0089] Where, represents the electric field of s polarization, represents the electric field of p polarization, out is the outgoing light identifier, and in is the incident light identifier; The Jones matrix is a 2×2 complex matrix used to describe the change in the electric field of completely polarized light after passing through the sample under test, represents the s polarization component of the incident light on the s polarization component of the outgoing light effect, Represents the p-polarization component of the incident light On the p-polarization component of the outgoing light The influence of Represents the p-polarization component of the incident light On the s-polarization component of the outgoing light The influence of Represents the s-polarization component of the incident light On the p-polarization component of the outgoing light The influence of

[0090] For polarized light, the Stokes quantities are as follows:

[0091]

[0092]

[0093]

[0094]

[0095] Based on the above, the Mueller matrix is as follows:

[0096]

[0097]

[0098]

[0099]

[0100] Where Represents the modulus square of the elements in the Jones matrix, reflecting the intensity of each polarization component Represents the real part product between the elements in the Jones matrix, reflecting the coupling effect (real part) between the polarization components Represents the imaginary part product between the elements in the Jones matrix, reflecting the coupling effect (imaginary part) between the polarization components

[0101] When the azimuth angle of the incident light is 0°, 90°, 180°, or 270°, the sample to be measured decomposes the polarized incident light into s-polarization and p-polarization at this time, and the electromagnetic field propagation of the two polarizations is separated. Therefore, there is That is to say, in the case of azimuth angles of 0°, 90°, 180°, or 270°, the elements with subscripts 3 and 4 in the Mueller matrix degenerate to 0, and the above Mueller matrix can be simplified to:

[0102]

[0103] Through normalization, the final Mueller matrix is:

[0104]

[0105] Based on the above content, it can be concluded that when the azimuth angle is 0°, 90°, 180°, or 270°, is always equal to 1, where the value range of is

[0106]

[0107]

[0108] Among them, when the azimuth angle is 0°, 90°, 180°, or 270°, it can be obtained that is 1, and is 0. That is, in theory, when analyzing that the angle is zero, when α is 1 at a specific angle (0°, 90°, 180°, or 270°), β is 0. However, in actual applications, there may be errors, resulting in the situation where it may not be possible to have both being 1 and being 0 at the same time. Therefore, in this step, the server determines the angle corresponding to the peak value of the sine term coefficient ( is 1) in the Fourier coefficients or the angle corresponding to the absolute value valley value of the cosine term coefficient ( is 0) in the Fourier coefficients as the fine calibration angle. Then, the fine calibration angle can be 0°, 90°, 180°, or 270°. In this specification, there is no limitation on how to determine the specific method of the fine calibration angle based on the angle corresponding to the peak value of the sine term coefficient ( is 1) in the Fourier coefficients and the angle corresponding to the absolute value valley value of the cosine term coefficient ( is 0) in the Fourier coefficients, such as randomly selecting or taking the average, which can be set according to actual needs.

[0109] It should be noted that due to possible errors in actual applications, the sine term coefficient may not be 1. Therefore, the peak value where the sine term coefficient in the above Fourier coefficients is equal to 1 means that the value of the sine term coefficient is not only the peak value but also must be close to 1, and the corresponding angle at this time is the fine calibration angle. Similarly, the peak value where the absolute value of the cosine term coefficient in the Fourier coefficients is equal to 0 means that the absolute value of the cosine term coefficient is not only the valley value but also must be close to 0, and the corresponding angle at this time is the fine calibration angle.

[0110] S108: Using the fine calibration angle as the target, calibrate the azimuth angle of the incident light.

[0111] In one or more embodiments of this specification, the server can calibrate the azimuth angle of the incident light based on the fine calibration angle determined in step S106.

[0112] Specifically, the server takes the fine calibration angle determined in step S106 as the target to calibrate the azimuth angle of the incident light.

[0113] It should be noted that during the actual calibration process, the server can perform a rough calibration on the azimuth angle of the incident light, that is, roughly align it with 0°, 90°, 180°, or 270°. Thus, when adjusting the azimuth angle in step S104, it is only necessary to find the fine calibration angle corresponding to "the peak value of the sine term coefficient or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients" within the preset angle range, thereby reducing the search range to improve the calibration efficiency. And in this specification, the size of the preset angle range is not limited and can be set according to actual needs. At the same time, the above-mentioned "taking the fine calibration angle as the target to calibrate the azimuth angle of the incident light" means that when the azimuth angle is at this fine calibration angle, the azimuth angle should be a certain specific angle (0°, 90°, 180°, or 270°). Therefore, if the actual azimuth angle is other angles, calibration is required to make the azimuth angle at this specific angle.

[0114] In the above method, the server changes the angle of the azimuth angle and records the Fourier coefficients corresponding to the optical signals emitted at different azimuth angles, thereby determining the fine calibration angle corresponding to the peak value of the sine term coefficient in the Fourier coefficients or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients. Finally, taking this fine calibration angle as the target, the azimuth angle of the incident light is calibrated, improving the calibration accuracy of the azimuth angle and ensuring the accuracy of subsequent measurement of the optical critical dimensions of the sample to be measured.

[0115] In addition, in this specification, a process for the server to perform a rough calibration on the azimuth angle of the measurement device before finely calibrating the azimuth angle of the measurement device is provided as follows:

[0116] In one or more embodiments of this specification, the server can adjust the translation device carrying the standard sheet in the measurement device through a standard sheet marked with a calibration pattern, so that the standard sheet is in a preset position, and based on the calibration pattern on the standard sheet, adjust the azimuth angle of the incident light provided by the measurement optical path unit. According to the notch of the sample to be measured that is consistent with the standard sheet, the standard sheet can thus be replaced with the sample to be measured.

[0117] It should be noted that after the rough calibration based on the standard sheet, the azimuth angle of the incident light should theoretically be a specific angle, such as 0°, 90°, 180°, or 270°. However, due to the poor calibration accuracy of the standard sheet, there is a deviation in the calibration of the azimuth angle. Therefore, after the rough calibration, the fine calibration of steps S100 - S108 can be used to improve the calibration accuracy of the azimuth angle.

[0118] As shown Figure 3 in the figure, it is a schematic diagram of the standard wafer provided by this specification. In this figure, the calibration pattern consists of a row of crosses. The server adjusts the translation device that holds the standard wafer in the measuring device so that the first cross is captured within the detection range. After that, by translating a preset distance, the second cross can be captured. If the second cross is not captured after translating the preset distance, it means that there is a deviation in the azimuth angle of the current incident light, and the angle of this azimuth angle should be changed until each cross in the calibration pattern can be captured in sequence according to the translation of the preset distance. Of course, this figure is only a schematic diagram and does not limit the specific form of the calibration pattern and the actual process of rough calibration.

[0119] In addition, this specification provides a specific implementation manner for changing the angle of the azimuth angle, that is, before changing the angle of the azimuth angle according to the first step length required by the calibration accuracy in step S104, the server can rotate the sample to be measured within a preset angle range according to a preset second step length (the second step length is greater than the first step length), so as to determine a fine rotation range smaller than the preset angle range based on the rough calibration angle corresponding to the peak value of the sine term coefficient in the Fourier coefficients or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients, and then rotate the sample to be measured according to the first step length to obtain the fine calibration angle, thereby improving the efficiency by reducing the number of rotations. The specific steps are as follows:

[0120] In one or more embodiments of this specification, first, the server needs to rotate the sample to be measured within a preset angle range according to a preset second step length, and the second step length is greater than the first step length. Furthermore, the server needs to record the Fourier coefficients corresponding to the optical signals emitted at each angle during the process of rotating the sample to be measured according to the second step length, and determine the angle corresponding to the peak value of the sine term coefficient in the Fourier coefficients or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients as the rough calibration angle.

[0121] Secondly, the server can determine a fine rotation range based on the determined rough calibration angle, and the fine rotation range is smaller than the preset angle range. Finally, the server can rotate the sample to be measured according to the first step length until the rotation range reaches the fine rotation range.

[0122] It should be noted that in this specification, the process of determining the fine rotation range based on the rough calibration angle is not limited and can be set according to actual needs. As Figure 4As shown, the figure provided in this specification shows the curves of the sine term coefficient in the Fourier coefficients of the response of a one-dimensional grating to incident light and the curves of the cosine term coefficient in the Fourier coefficients of the response of a one-dimensional grating to incident light changing with the azimuth angle at different wavelengths. In this figure, Si Grating refers to the grating structure fabricated on a silicon (Si) material; AOI refers to the angle of incidence, which is the angle between the incident light and the normal of the surface of the sample to be measured; A refers to the analysis angle; P refers to the polarization angle; and Phi in the horizontal coordinate refers to the azimuth angle. That is, it shows a parabolic trend around specific angles (such as 0°, 90°, 180°, or 270°). Therefore, based on the fact that the second step length is greater than the first step length, there may be a rough calibration angle determined by rotating the sample to be measured based on the second step length, rather than the angle (fine calibration angle) corresponding to the peak of the sine term coefficient or the valley of the absolute value of the cosine term coefficient at the required accuracy (the first step length). Among them, the possible situations are that the fine calibration angle appears between the angle after "subtracting the second step length from the rough calibration angle" and the rough calibration angle, the fine calibration angle is the same as the rough calibration angle, or the fine calibration angle appears between the rough calibration angle and the angle after "adding the second step length to the rough calibration angle". Therefore, in one or more embodiments of this specification, the server can determine the angle that differs from the above-mentioned rough calibration angle by the second step length as the boundary value, and based on the obtained boundary value, determine the fine rotation range.

[0123] In addition, this specification provides a process for changing the angle of the azimuth angle of the incident light after determining the rotation direction, which is as follows:

[0124] In one or more embodiments of this specification, since the absolute values of the sine term coefficient and the cosine term coefficient show a parabolic trend around a specific angle, the server can determine the adjacent azimuth angles of the current azimuth angle of the incident light, and based on the Fourier coefficients corresponding to the outgoing optical signals at the adjacent azimuth angles, determine the direction in which the sine term coefficient increases or the direction in which the absolute value of the cosine term coefficient decreases as the rotation direction.

[0125] Specifically, first, the server can determine the adjacent azimuth angles of the current azimuth angle of the incident light. Among them, the specific method for determining the adjacent azimuth angles is not limited in this specification and can be set according to actual needs. For example, based on the first step length corresponding to the required accuracy, the angle that differs from the current azimuth angle by the first step length can be determined as the adjacent azimuth angle of the current azimuth angle.

[0126] Secondly, the server can determine the Fourier coefficients corresponding to the emitted optical signals at the current azimuth angle and the adjacent azimuth angle, and then determine the direction in which the sine term coefficient in the Fourier coefficients increases or the direction in which the absolute value of the cosine term coefficient in the Fourier coefficients decreases based on the magnitude relationship of the determined Fourier coefficients as the rotation direction. Finally, the server can rotate the sample to be measured starting from the current azimuth angle along the determined rotation direction until the angle of the rotated azimuth angle reaches any boundary value within the preset angle range.

[0127] It should be noted that if the sine term coefficient in the Fourier coefficients corresponding to the emitted optical signal at the current azimuth angle is the peak value 1 or the absolute value of the cosine term coefficient is the valley value 0, it means that the current azimuth angle does not need to be calibrated. Therefore, in one or more embodiments of this specification, the server can determine the adjacent azimuth angle of the current azimuth angle before changing the azimuth angle, and then judge whether the current azimuth angle needs to be calibrated based on the magnitude relationship between the Fourier coefficients at the adjacent azimuth angle and the Fourier coefficients at the current azimuth angle, so as to avoid the process of ineffective calibration.

[0128] In addition, after calibration is provided in this specification, the process of adjusting the azimuth angle to the target azimuth angle required for "performing optical critical dimension measurement on the sample to be measured" is as follows:

[0129] In one or more embodiments of this specification, the server can use the azimuth angle required when measuring the sample to be measured as the target azimuth angle, and then determine the target step size based on the fine calibration angle determined during calibration and the target azimuth angle, adjust the azimuth angle of the incident light in the measuring device based on the target step size, and perform optical critical dimension measurement on the sample to be measured based on the adjusted measuring device.

[0130] The above is a wafer detection method provided in one or more embodiments of this specification. Based on the same idea, this specification also provides a corresponding wafer detection device, as Figure 5 shown.

[0131] Adjust the optical path module 500, adjust the measurement optical path unit, and provide incident light to enter the grating area on the surface of the sample to be measured. The angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle; adjust the polarizer so that the polarization direction of the electric field vector of the polarized light after the incident light passes through the polarizer is perpendicular to the incident plane and parallel to the surface of the sample to be measured;

[0132] The acquisition module 501 acquires the optical signal emitted from the grating area through the detector and provides the Fourier coefficients corresponding to the optical signal through the Fourier ellipsometry processing unit;

[0133] The rotation module 502 changes the angle of the azimuth angle and records the Fourier coefficients corresponding to the optical signal at different azimuth angles.

[0134] The fine calibration angle module 503 determines, according to the recorded Fourier coefficients, the angle corresponding to the peak value of the sine term coefficient in the Fourier coefficients or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients as the fine calibration angle.

[0135] The calibration module is used to calibrate the azimuth angle of the measuring device with the fine calibration angle as the target.

[0136] Optionally, the rotation module 502 is specifically configured to rotate the sample to be measured according to a preset first step length until the rotation range reaches a preset angle range.

[0137] Optionally, the rotation module 502 can also be used to rotate the sample to be measured within the preset angle range according to a preset second step length, where the second step length is greater than the first step length; record the Fourier coefficients of the optical signal at each angle during the process of rotating the sample to be measured according to the second step length, and determine the angle corresponding to the peak value of the sine term coefficient in the Fourier coefficients or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficients as the rough calibration angle; determine a fine rotation range according to the rough calibration angle, where the fine rotation range is smaller than the angle range; rotate the sample to be measured according to the first step length until the rotation range reaches the fine rotation range.

[0138] Optionally, the rotation module 502 can also be used to determine the angle that differs from the rough calibration angle by the second step length as the boundary value; determine the fine rotation range according to the boundary value.

[0139] Optionally, the rotation module 502 can also be used to determine the adjacent azimuth angles of the current azimuth angle of the incident light; determine the Fourier coefficients corresponding to the optical signal at the current azimuth angle and the adjacent azimuth angles respectively; determine the increasing direction of the sine term coefficient in the Fourier coefficients or the decreasing direction of the absolute value of the cosine term coefficient in the Fourier coefficients according to the magnitude relationship of the determined Fourier coefficients as the rotation direction; rotate the sample to be measured along the rotation direction starting from the current azimuth angle until the angle of the azimuth angle of the incident light after rotation reaches any boundary value in the preset angle range.

[0140] Optionally, the optical path adjustment module 500 is specifically configured to determine a standard wafer marked with a calibration pattern; adjust the translation device in the measuring device that holds the standard wafer to place the standard wafer at a preset position; adjust the azimuth angle of the incident light provided by the measuring optical path unit according to the calibration pattern; and replace the standard wafer with the to-be-tested sample according to the notch that is the same between the to-be-tested sample and the standard wafer.

[0141] Optionally, the device further includes a critical dimension module 504, which is specifically configured to use the azimuth angle required when measuring the to-be-tested sample as the target azimuth angle; determine a target step size according to the fine calibration angle and the target azimuth angle; adjust the measuring device according to the target step size, and perform optical critical dimension measurement on the to-be-tested sample by using the adjusted measuring device.

[0142] This specification also provides a computer-readable storage medium that stores a computer program, and the computer program can be used to execute the above Figure 1 A method for fine calibration of the azimuth angle of a measuring device provided.

[0143] This specification also provides Figure 6 A schematic structural diagram of an electronic device corresponding to the method for fine calibration of the azimuth angle of a measuring device shown. As Figure 6 described, at the hardware level, the device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory. Of course, it may also include other hardware required for other services. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to implement the above Figure 1 A method for fine calibration of the azimuth angle of a measuring device described. Of course, in addition to the software implementation manner, this specification does not exclude other implementation manners, such as a logic device or a combination of software and hardware. That is to say, the execution subject of the following processing flow is not limited to each logic unit, and may also be hardware or a logic device.

[0144] In the 1990s, improvements to a technology could be clearly distinguished as either hardware improvements (e.g., improvements to circuit structures such as diodes, transistors, switches, etc.) or software improvements (improvements to method flows). However, with the development of technology, many method flow improvements today can be regarded as direct improvements to hardware circuit structures. Designers almost always obtain the corresponding hardware circuit structure by programming the improved method flow into the hardware circuit. Therefore, it cannot be said that an improvement to a method flow cannot be implemented using a hardware entity module. For example, a Programmable Logic Device (PLD) (such as a Field Programmable Gate Array (FPGA)) is an integrated circuit whose logic function is determined by a user's programming of the device. Designers can program themselves to "integrate" a digital system onto a single PLD, without having to ask a chip manufacturer to design and fabricate a dedicated integrated circuit chip. Moreover, nowadays, instead of manually fabricating integrated circuit chips, this programming is mostly implemented using "logic compiler" software, which is similar to the software compilers used in program development and writing. The original code before compilation also has to be written in a specific programming language, which is called a Hardware Description Language (HDL), and there is not just one type of HDL, but many, such as ABEL (Advanced Boolean Expression Language), AHDL (Altera Hardware Description Language), Confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), Lava, Lola, MyHDL, PALASM, RHDL (Ruby Hardware Description Language), etc. The most commonly used ones currently are VHDL (Very-High-Speed Integrated Circuit Hardware Description Language) and Verilog. Those skilled in the art should also be aware that by simply performing a little logical programming on the method flow using the above-mentioned several hardware description languages and programming it into an integrated circuit, it is easy to obtain the hardware circuit that implements the logical method flow.

[0145] The controller can be implemented in any suitable manner. For example, the controller can take the form of, for example, a microprocessor or a processor and a computer-readable medium storing computer-readable program code (such as software or firmware) executable by the (micro)processor, logic gates, switches, an application specific integrated circuit (ASIC), a programmable logic controller, and an embedded microcontroller. Examples of the controller include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F320. The memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art also know that in addition to implementing the controller in the form of pure computer-readable program code, it is entirely possible to logically program the method steps to enable the controller to be implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. to achieve the same function. Therefore, such a controller can be considered a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as either software modules for implementing the method or structures within the hardware component.

[0146] The systems, devices, modules, or units illustrated in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0147] For the convenience of description, when describing the above devices, they are described separately as various units according to their functions. Of course, when implementing this specification, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0148] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program code.

[0149] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and combinations of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processors of the computer or other programmable data processing device generate means for implementing the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or means for implementing the functions specified in one or more of the blocks.

[0150] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including instruction means that implement the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or means for implementing the functions specified in one or more of the blocks.

[0151] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operational steps are performed on the computer or other programmable device to produce a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or means for implementing the functions specified in one or more of the blocks.

[0152] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and memory.

[0153] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of computer-readable media.

[0154] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0155] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0156] This specification may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. This specification may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0157] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0158] The above are only examples of this specification and are not intended to limit this specification. For those skilled in the art, various modifications and changes can be made to this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this specification shall be included within the scope of the claims of this specification.

Claims

1. A method for finely calibrating the azimuth of a measuring device, characterized in that: The measuring device comprises a measuring optical path unit, a polarizer, a detector and a Fourier ellipsometric processing unit, including: The measuring optical path unit is adjusted to provide incident light to enter the grating area on the surface of the sample to be measured, and the angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle; the polarizer is adjusted to make the polarization direction of the electric field vector of the polarized light after the incident light passes through the polarizer perpendicular to the incident plane and parallel to the surface of the sample to be measured; The detector collects the optical signal emitted from the grating area, and the Fourier ellipsometric processing unit provides the Fourier coefficient corresponding to the optical signal; Changing the azimuth angle, and recording the Fourier coefficients corresponding to the optical signal at different azimuth angles within a preset angle range; According to the recorded Fourier coefficients, determine the angle corresponding to the peak value of the sine term coefficient in the Fourier coefficient equal to 1 or the valley value of the cosine term coefficient in the Fourier coefficient equal to 0 as the fine calibration angle; The azimuth angle of the measuring device is calibrated with the fine calibration angle as a target.

2. The method according to claim 1, characterized in that The step of changing the angle of the azimuth specifically includes: According to the preset first step length, the sample to be tested is rotated until the rotation range reaches the preset angle range.

3. The method according to claim 2, characterized in that The step of changing the angle of the azimuth specifically includes: Rotating the sample to be tested within a preset angle range according to a preset second step length, wherein the second step length is greater than the first step length; Recording the Fourier coefficients of the optical signal at each angle during the process of rotating the sample to be tested with the second step length, and determining the angle corresponding to the peak value of the sine term coefficient in the Fourier coefficient or the valley value of the absolute value of the cosine term coefficient in the Fourier coefficient as a rough calibration angle; Determining a fine rotation range according to the rough calibration angle, the fine rotation range being smaller than the angle range; The sample to be tested is rotated according to the first step until the rotation range reaches the fine rotation range.

4. The method according to claim 3, characterized in that The step of determining the fine rotation range according to the rough calibration angle specifically includes: Determine an angle that differs from the rough calibration angle by the second step length as a boundary value; Based on the boundary value, a fine rotation range is determined.

5. The method according to claim 1, characterized in that The step of changing the angle of the azimuth specifically includes: Determining adjacent azimuth angles of a current azimuth angle of the incident light; Determine the Fourier coefficients corresponding to the optical signal at the current azimuth and the adjacent azimuth; According to the determined magnitude relationship of each Fourier coefficient, determine the direction in which the sine term coefficient in the Fourier coefficient increases or the direction in which the absolute value of the cosine term coefficient in the Fourier coefficient decreases as the rotation direction; The sample to be tested is rotated along the rotation direction starting from the current azimuth angle until the azimuth angle of the incident light after rotation reaches any boundary value in a preset angle range.

6. The method according to claim 1, characterized in that The step of adjusting the measuring optical path unit specifically includes: Determine the standard sheet marked with the calibration pattern; Adjusting the translation device carrying the standard sheet in the measuring device so that the standard sheet is in a preset position; According to the calibration pattern, adjusting the azimuth angle of the incident light provided by the measuring optical path unit; According to the notch where the sample to be tested and the standard sheet are consistent, the standard sheet is replaced by the sample to be tested.

7. The method according to claim 1, characterized in that The method further comprises: The azimuth angle required for measuring the sample to be tested is used as the target azimuth angle; Determining a target step length according to the fine calibration angle and the target azimuth; The measuring device is adjusted according to the target step length, and the optical critical dimension of the sample to be measured is measured by using the adjusted measuring device.

8. A device for finely calibrating the azimuth angle of a measuring device, characterized in that: include: An optical path adjustment module is used to adjust the measurement optical path unit, so that the incident light is incident on the grating area on the surface of the sample to be measured, and the angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle; the polarizer is adjusted so that the polarization direction of the electric field vector of the polarized light after the incident light passes through the polarizer is perpendicular to the incident plane and parallel to the surface of the sample to be measured; A collection module, used for collecting the optical signal emitted from the grating area through a detector, and providing the Fourier coefficient corresponding to the optical signal through a Fourier ellipsometric processing unit; A rotation module, used to change the angle of the azimuth angle and record the Fourier coefficients corresponding to the optical signal at different azimuth angles within a preset angle range; A fine calibration angle module is used to determine, according to each recorded Fourier coefficient, an angle corresponding to a peak value of a sine term coefficient in the Fourier coefficient or a valley value of an absolute value of a cosine term coefficient in the Fourier coefficient as a fine calibration angle; The calibration module is used to calibrate the azimuth angle of the measuring device with the fine calibration angle as a target.

9. A computer-readable storage medium, characterized in that: The storage medium contains a computer program, and when the computer program is executed by a processor, the method described in any one of claims 1 to 7 is implemented.

10. An electronic device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the method according to any one of claims 1 to 7 is implemented when the processor executes the program.

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