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 detector, and a Mueller matrix ellipsometry processing unit. By adjusting the measurement optical path unit, incident light is provided to enter the grating region of the sample to be measured. The angle between the incident plane and the periodic distribution direction of the grating region is the azimuth angle. The spectral information of the outgoing light is collected by the detector, and the corresponding Mueller matrix is provided through the ellipsometry Mueller matrix processing unit. The angle of this azimuth angle is changed, and the corresponding Mueller matrix at different azimuth angles is recorded. Furthermore, the fine calibration angle corresponding to the peak value of M22 in the Mueller matrix can be determined. Taking the fine calibration angle as the target, the azimuth angle is calibrated, that is, by changing the angle of the azimuth angle and recording the corresponding Mueller matrix at different azimuth angles, the fine calibration angle corresponding to the peak value of M22 is determined to calibrate the azimuth angle of the incident light, improve the calibration accuracy, and ensure the accuracy of subsequent measurements.

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 measuring 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, it uses the optical principle 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, thus affecting 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 measuring device. Summary of the Invention

[0005] This specification provides a method, device, medium, and equipment for fine calibration of the azimuth angle of a measuring 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 measuring device, where the measuring device includes a measurement optical path unit, a detector, and a Mueller matrix ellipsometry processing unit, including:

[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, 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;

[0009] Collect the spectral information of the outgoing light from the grating area through the detector, and provide the Mueller matrix corresponding to the spectral information of the outgoing light through the ellipsometric Mueller matrix processing unit;

[0010] Change the angle of the azimuth angle, and record the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles;

[0011] Based on the recorded Mueller matrices, determine the angle corresponding to the peak of M22 in the Mueller matrix as the fine calibration angle;

[0012] Taking the fine calibration angle as the target, calibrate the azimuth angle of the incident light.

[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 Mueller matrices corresponding to the spectral information of the outgoing light 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 of M22 in the Mueller matrix 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 Mueller matrices corresponding to the spectral information of the outgoing light at the current azimuth angle and the adjacent azimuth angles respectively;

[0026] According to the magnitude relationship of M22 in the determined Mueller matrices, determine the direction in which M22 increases 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 within a preset angle range.

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

[0029] Determine a standard wafer marked with a calibration pattern;

[0030] Adjust the translation device in the measurement equipment that holds the standard wafer to place the standard wafer at 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] According to the notch of the sample to be measured that is consistent with the standard wafer, replace the standard wafer with the sample to be measured.

[0033] Optionally, the method further includes:

[0034] Take the azimuth angle required when measuring the sample to be measured as the target azimuth angle;

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

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

[0037] This specification provides an azimuth fine calibration device for a measurement equipment. The measurement equipment includes a measurement optical path unit, a detector, and a Mueller matrix ellipsometry processing unit, and includes:

[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, 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;

[0039] A measurement optical path module for collecting the spectral information of the outgoing light from the grating area through a detector, and providing the Mueller matrix corresponding to the spectral information of the outgoing light through an ellipsometric Mueller matrix processing unit;

[0040] An azimuth adjustment module for changing the angle of the azimuth angle and recording the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles;

[0041] A fine calibration angle module for determining the angle corresponding to the peak value of M22 in the Mueller matrix as the fine calibration angle according to the recorded Mueller matrices;

[0042] A calibration module for calibrating the azimuth angle of the incident light 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 measurement optical path unit, a detector, and a Mueller matrix ellipsometry processing unit. By adjusting the measurement optical path unit, an incident light is provided 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. The detector collects the spectral information of the outgoing light in the grating area, and the Mueller matrix corresponding to the spectral information of the outgoing light is provided through the ellipsometric Mueller matrix processing unit. Then, the angle of the azimuth angle is changed, and the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles is recorded. Finally, based on the recorded Mueller matrices, the angle corresponding to the peak value of M22 in the Mueller matrix is determined as the fine calibration angle, and with this fine calibration angle as the target, the azimuth angle of the incident light is calibrated.

[0046] As can be seen from the above method, by changing the angle of the azimuth angle and recording the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles, the angle corresponding to the peak value of M22 in the Mueller matrix is used as the fine calibration angle, and with this 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0048] Figure 1 It 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 It is a schematic diagram of the periodic distribution direction provided in this specification;

[0050] Figure 3 Schematic diagram of the standard wafer in the rough calibration provided in this specification;

[0051] Figure 4 Schematic diagram of the variation of M22 with the azimuth angle provided in this specification;

[0052] Figure 5 Schematic diagram of the azimuth fine calibration device for a measurement device provided in this specification;

[0053] Figure 6 Schematic diagram of the electronic device structure corresponding to the method for realizing the azimuth fine calibration of a measurement device provided in this specification. Detailed implementation manners

[0054] To make the objectives, 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 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 protection scope of this specification.

[0055] In the process of implementing the method for azimuth fine calibration of a measurement device in this specification, it involves data processing and analysis. Therefore, in the embodiments of this specification, the server can execute the process of the method for azimuth fine calibration of a measurement device. Of course, this specification does not limit which device executes the process of azimuth fine calibration of the measurement 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 azimuth fine calibration. For the convenience of description, the server is used as the execution subject for illustration below.

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

[0057] Figure 1 Schematic diagram of the flow 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, and the included angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle.

[0059] In one or more embodiments of this specification, in order to collect the spectral information of the outgoing light from the grating region on the surface of the sample to be measured by a detector in subsequent steps, and to provide the Mueller matrix corresponding to the spectral information through an ellipsometric Mueller matrix processing unit, so as to achieve fine calibration of the azimuth angle of the measuring device, in this step, the server needs to adjust the measuring optical path unit in the measuring device to provide incident light to enter the grating region on the surface of the sample to be measured.

[0060] Specifically, the server adjusts the measuring optical path unit in the measuring device to provide incident light to enter the grating region on the surface of the sample to be measured. Wherein, the angle between the plane where the incident light is located and the periodic distribution direction of the grating region is the azimuth angle, and the measuring device at least includes a measuring optical path unit, a detector, and an ellipsometric Mueller matrix processing unit.

[0061] It should be noted that the azimuth angle refers to the angle between the plane where the incident light is located (the 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 region), this reference direction is usually the periodic distribution direction of the grating region 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 region in the sample to be measured provided in this specification when the grating region is a one-dimensional grating. In this figure, the periodic distribution direction of the grating region 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] S102: Collect the spectral information of the outgoing light from the grating region through a detector, and provide the Mueller matrix corresponding to the spectral information of the outgoing light through an ellipsometric Mueller matrix processing unit.

[0063] In one or more embodiments of this specification, in order to record the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles by adjusting the angle of the azimuth angle in subsequent steps. In this step, the server needs to collect the spectral information of the outgoing light from the grating region through a detector, and the ellipsometric Mueller matrix processing unit provides the Mueller matrix corresponding to the spectral information of the outgoing light.

[0064] Specifically, the server can collect the spectral information of the outgoing light from the grating region through the detector in the measuring device, and the ellipsometric Mueller matrix processing unit in the measuring device provides the Mueller matrix corresponding to the spectral information of the outgoing light.

[0065] It should be noted that the detector is used to detect the optical elements of reflected light or transmitted light, while the ellipsometric Mueller matrix processing unit is used to process the data collected by the detector and calculate the Mueller matrix corresponding to the spectral information of the outgoing light.

[0066] S104: Change the angle of the azimuth angle and record the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles.

[0067] In one or more embodiments of this specification, in order to determine the fine calibration angle in the subsequent steps, in this step, the server needs to change the angle of the azimuth angle and record the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles.

[0068] Specifically, the server needs to change the angle of the azimuth angle and record the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles.

[0069] It should be noted that in this specification, the specific manner of changing the angle of the azimuth angle is not limited and 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 controls the rotation device under the carrier to rotate, thereby changing the angle of the azimuth angle of the incident light. At the same time, in this specification, the specific manner of changing the angle of the azimuth angle is not limited and 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 thereby record the Mueller matrix corresponding to the spectral information of the outgoing light 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 requirements of actual needs, such as 1°, 0.1°, 0.01°, etc.

[0070] S106: Determine the angle corresponding to the peak value of M22 in the Mueller matrix based on the recorded Mueller matrices as the fine calibration angle.

[0071] 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 M22 in the Mueller matrix based on the recorded Mueller matrices as the fine calibration angle.

[0072] Specifically, the server can determine the angle corresponding to the peak value of M22 in the Mueller matrix based on the recorded Mueller matrices as the fine calibration angle.

[0073] It should be noted that the Mueller matrix is a 4*4 matrix describing the change of 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 parameters are used to describe the polarization state of light and have four components: Represents the total intensity, which is the sum of light of all polarization states; Is the difference between two orthogonal directions (horizontal and vertical) of linear polarization; Is the difference between two diagonal directions (+45° and -45°) of linear polarization; Is the difference between the left- and right-handed components of circular polarization. The Mueller matrix corresponds to the response of the sample under test to the incident light as follows:

[0074]

[0075]

[0076]

[0077]

[0078]

[0079] Where, Is the Stokes quantity of the incident light, Is the Stokes quantity of the outgoing light, M is the Mueller matrix of the response of the sample under test to the incident light, Represents linear polarization in the x direction, Represents linear polarization in the y direction, Represents linear polarization with the polarization direction along 45°, Represents linear polarization with the polarization direction along -45°, Represents right-handed polarization, Represents left-handed polarization.

[0080] That is, by collecting the Stokes quantities 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:

[0081]

[0082] For polarized light, the response of the sample under test to the incident light can be described by the Jones matrix as follows:

[0083]

[0084] That is, the following equation:

[0085]

[0086] Where, Represents the electric field of s polarization, Represents the electric field of p polarization, out is the outgoing light identifier, 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 The influence of 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

[0087] For polarized light, the Stokes parameters are as follows:

[0088]

[0089]

[0090]

[0091]

[0092] Based on the above, the Mueller matrix is as follows:

[0093]

[0094]

[0095]

[0096]

[0097] Among them, Represents the square of the modulus 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

[0098] 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 are 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 - mentioned Mueller matrix can be simplified to:

[0099]

[0100] Through normalization, the final Mueller matrix is obtained as follows:

[0101]

[0102] Based on the above, 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 . Therefore, in this step, the server determines the angle corresponding to the peak value of M22 in the Mueller matrix (M22≈1) based on the recorded Mueller matrices as the fine calibration angle, and then this fine calibration angle can be 0°, 90°, 180°, or 270°.

[0103] S108: Taking the fine calibration angle as the target, calibrate the azimuth angle of the incident light.

[0104] 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.

[0105] Specifically, the server takes the fine calibration angle determined in step S106 as the target to calibrate the azimuth angle of the incident light.

[0106] It should be noted that in 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°. Therefore, in step S104, when adjusting the azimuth angle, it is only necessary to find the fine calibration angle corresponding to the "peak value of M22 in the Mueller matrix" within a preset angle range, so as to reduce the search range and improve the calibration efficiency. 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 "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.

[0107] In the above method, the server changes the azimuth angle and records the Mueller matrices corresponding to the spectral information of the outgoing light at different azimuth angles, thereby determining the fine calibration angle corresponding to the peak value of M22 in the Mueller matrix. Finally, taking this fine calibration angle as the target to calibrate the azimuth angle of the incident light improves the calibration accuracy of the azimuth angle and ensures the accuracy of subsequent measurement of the optical critical dimensions of the sample to be measured.

[0108] In addition, in this specification, a process for the server to perform rough calibration of the azimuth angle of the measurement device before finely calibrating the azimuth angle of the measurement device is provided as follows:

[0109] In one or more embodiments of this specification, the server can adjust the translation device in the measurement device that holds the calibration standard through a calibration standard marked with a calibration pattern, so that the calibration standard is in a preset position, and based on the calibration pattern on the calibration standard, 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 calibration standard, the calibration standard can thus be replaced with the sample to be measured.

[0110] It should be noted that after rough calibration based on the calibration standard, 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 calibration standard, there is a deviation in the calibration of the azimuth angle. Therefore, after rough calibration, the calibration accuracy of the azimuth angle can be improved through the fine calibration of steps S100 to S108.

[0111] As Figure 3 shown, it is a schematic diagram of the calibration standard provided in this specification. In this figure, the calibration pattern consists of a row of crosses. The server adjusts the translation device in the measurement device that holds the calibration standard so that the first cross is captured within the detection range. Then, 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 the 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.

[0112] 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 by 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 M22 peak, 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 process is as follows:

[0113] 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 Mueller matrix corresponding to the spectral information of the outgoing light at each angle during the process of rotating the sample to be measured by the second step length, and determine the angle corresponding to the M22 peak in the Mueller matrix as the rough calibration angle.

[0114] Secondly, the server can determine a fine rotation range based on the determined rough calibration angle, and the fine rotation range is smaller than a preset angle range. Finally, the server can rotate the sample to be measured in the first step length until the rotation range reaches the fine rotation range.

[0115] 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 4 shown, it is a curve of M22 varying with the azimuth angle in the Mueller matrix of the one-dimensional grating's response to incident light at different wavelengths provided in this specification. In this figure, Si Grating refers to the grating structure fabricated on 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 to say, it shows a parabolic trend around specific angles (such as 0°, 90°, 180°, or 270°). Therefore, since the second step length is greater than the first step length, the rough calibration angle determined by rotating the sample to be measured based on the second step length may not be the angle (fine calibration angle) corresponding to the peak value of M22 at the required accuracy (the first step length). The possible situations are that the fine calibration angle appears between the angle after "rough calibration angle minus the second step length" and the rough calibration angle, the rough calibration angle is the fine calibration angle, or the fine calibration angle appears between the angle after "rough calibration angle plus the second step length" and the rough calibration angle. Therefore, in one or more embodiments of this specification, the server can determine the angles that differ from the above-mentioned rough calibration angle by the second step length as boundary values, and determine the fine rotation range based on the obtained boundary values.

[0116] In addition, after determining the rotation direction, this specification provides a process for changing the angle of the azimuth angle of the incident light, which is as follows:

[0117] In one or more embodiments of this specification, since the value of M22 shows 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 determine the direction in which M22 increases as the rotation direction based on the Mueller matrix corresponding to the spectral information of the outgoing light at the adjacent azimuth angles.

[0118] Specifically, first, the server can determine the adjacent azimuth angles of the current azimuth angle of the incident light. In this specification, the specific method of determining the adjacent azimuth angles is not limited 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.

[0119] Secondly, the server can determine the Mueller matrices corresponding to the spectral information of the outgoing light at the current azimuth angle and the adjacent azimuth angle, and then determine the direction in which M22 increases based on the magnitude relationship of M22 in the determined Mueller matrices as the rotation direction. Finally, the server can rotate the sample to be measured 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.

[0120] It should be noted that if the value of M22 in the Mueller matrix corresponding to the spectral information of the outgoing light at the current azimuth angle is the largest, 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 M22 in the Mueller matrix at the adjacent azimuth angle and M22 in the Mueller matrix at the current azimuth angle, so as to avoid the process of invalid calibration.

[0121] In addition, after calibration is provided in this specification, the process of adjusting the azimuth angle to the target azimuth angle required for "optically measuring the critical dimension of the sample to be measured" is as follows:

[0122] 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 optically measuring the critical dimension of the sample to be measured based on the adjusted measuring device.

[0123] The above is a method for fine calibration of the azimuth angle of a measuring device provided in one or more embodiments of this specification. Based on the same idea, this specification also provides a corresponding device for fine calibration of the azimuth angle of a measuring device, as Figure 5 shown.

[0124] Adjust the optical path module 500, adjust the measuring optical path unit, and provide the incident light to enter the grating area on the surface of the sample to be measured. The included angle between the plane where the incident light is located and the periodic distribution direction of the grating area is the azimuth angle;

[0125] The measuring optical path module 501 collects the spectral information of the outgoing light in the grating area through a detector, and provides the Mueller matrix corresponding to the spectral information of the outgoing light through the ellipsometric Mueller matrix processing unit;

[0126] The azimuth angle adjustment module 502 changes the angle of the azimuth angle and records the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles;

[0127] The fine calibration angle module 503 determines the angle corresponding to the peak of M22 in the Mueller matrix according to the recorded Mueller matrices as the fine calibration angle.

[0128] The calibration module 504 calibrates the azimuth angle of the incident light with the fine calibration angle as the target.

[0129] Optionally, the azimuth angle adjustment module 502 is specifically configured to rotate the sample to be measured by a preset first step length until the rotation range reaches a preset angle range.

[0130] Optionally, the azimuth angle adjustment module 502 can also be configured to rotate the sample to be measured within the preset angle range by a preset second step length, where the second step length is greater than the first step length; record the Mueller matrices corresponding to the spectral information of the outgoing light at each angle during the process of rotating the sample to be measured by the second step length, and determine the angle corresponding to the peak of M22 in the Mueller matrix 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 by the first step length until the rotation range reaches the fine rotation range.

[0131] Optionally, the azimuth angle adjustment module 502 can also be configured 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.

[0132] Optionally, the azimuth angle adjustment module 502 can also be configured to determine the adjacent azimuth angles of the current azimuth angle of the incident light; determine the Mueller matrices corresponding to the spectral information of the outgoing light at the current azimuth angle and the adjacent azimuth angles respectively; determine the direction in which M22 increases as the rotation direction according to the magnitude relationship of M22 in the determined Mueller matrices; rotate the sample to be measured from the current azimuth angle along the rotation direction until the azimuth angle of the incident light after rotation reaches any boundary value within the preset angle range.

[0133] Optionally, the device further includes a coarse calibration module 505, which is specifically configured to determine a standard piece marked with a calibration pattern; adjust the translation device in the measuring device that carries the standard piece to make the standard piece in a preset position; adjust the azimuth angle of the incident light provided by the measuring optical path unit according to the calibration pattern; replace the standard piece with the sample to be measured according to the notch where the sample to be measured is consistent with the standard piece.

[0134] Optionally, the device further includes an optical measurement module 506, specifically configured to use the azimuth angle required for measuring the sample to be measured as the target azimuth angle; determine a target step size according to the fine calibration angle and the target azimuth angle; adjust the measurement device according to the target step size, and perform optical critical dimension measurement on the sample to be measured by means of the adjusted measurement device.

[0135] This specification also provides a computer-readable storage medium storing a computer program that can be used to execute the Figure 1 azimuth angle fine calibration method of a measurement device provided above.

[0136] This specification also provides Figure 6 a schematic structural diagram of an electronic device for the azimuth angle fine calibration method of a measurement 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 Figure 1 azimuth angle fine calibration method of a measurement device provided above. Of course, in addition to the software implementation, this specification does not exclude other implementation manners, such as logic devices 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, but may also be hardware or a logic device.

[0137] In the 1990s, improvements to a technology could be clearly distinguished as either hardware improvements (e.g., improvements to the circuit structures of 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. Almost all designers obtain the corresponding hardware circuit structures by programming the improved method flows into the hardware circuits. 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) (e.g., a field programmable gate array (FPGA)) is such 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). 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 some 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.

[0138] 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 implement the same function by logically programming the method steps so that the controller is in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, and embedded microcontrollers. 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 the structures within the hardware component.

[0139] 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 a combination of any of these devices.

[0140] 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.

[0141] 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.

[0142] 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 present application. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of flows and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a means for implementing the functions specified in one or more flows and / or blocks Figure 1 in one or more flows and / or blocks Figure 1 or a means for implementing the functions specified in one or more blocks.

[0143] 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 work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction means, and the instruction means implements the functions specified in one or more flows and / or blocks Figure 1 in one or more flows and / or blocks Figure 1 or a means for implementing the functions specified in one or more blocks.

[0144] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate 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 flows and / or blocks Figure 1 in one or more flows and / or blocks Figure 1 or a means for implementing the functions specified in one or more blocks.

[0145] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and memory.

[0146] 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.

[0147] A computer-readable medium includes permanent and non-permanent, removable and non-removable media and can implement information storage by any method or technology. The 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 technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage, or other magnetic storage devices, or any other non-transitory medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer-readable medium does not include transitory computer-readable media, such as modulated data signals and carrier waves.

[0148] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or apparatus. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising the element.

[0149] This specification can 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 can also be practiced in a distributed computing environment where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0150] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system embodiments, since they are basically similar to method embodiments, they are described relatively simply, and the relevant parts can be referred to the description of the method embodiments.

[0151] The above are only embodiments 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 detector and a Mueller matrix ellipsometric processing unit, including: Adjust the measuring optical path unit to provide incident light to 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 spectral information of the outgoing light of the grating region is collected by a detector, and a Mueller matrix corresponding to the spectral information of the outgoing light is provided by a Mueller matrix ellipsometric processing unit; Changing the azimuth angle, and recording the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles within a preset angle range; According to each recorded Mueller matrix, determine the angle corresponding to the M22 peak in the Mueller matrix as the fine calibration angle; The azimuth angle of the incident light 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 Mueller matrix corresponding to the spectral information of the emitted light 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 M22 peak in the Mueller matrix 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 Mueller matrices corresponding to the spectral information of the outgoing light at the current azimuth and the adjacent azimuth; According to the determined magnitude relationship of M22 in each Mueller matrix, the direction in which M22 increases is determined 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 is consistent with that of the standard sheet, the standard sheet is replaced with 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: The measuring device comprises a measuring optical path unit, a detector and a Mueller matrix ellipsometric processing unit, including: An adjusting optical path module is used to adjust the measuring optical path unit 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; A measuring optical path module, used for collecting spectral information of the outgoing light of the grating area through a detector, and providing a Mueller matrix corresponding to the spectral information of the outgoing light through a Mueller matrix ellipsometric processing unit; An azimuth adjustment module is used to change the azimuth angle and record the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles within a preset angle range; A fine calibration angle module is used to determine the angle corresponding to the M22 peak in the Mueller matrix according to each recorded Mueller matrix as a fine calibration angle; The calibration module is used to calibrate the azimuth angle of the incident light 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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