Azimuth angle fine calibration method and device of measurement equipment, medium and equipment

Abstract

According to the azimuth angle fine calibration method and device of the measurement equipment, the medium and the equipment, the measurement equipment comprises a measurement light path unit, a detector and a Mueller matrix ellipsometry processing unit, the measurement light path unit is adjusted, incident light is provided to be emitted into a grating area of a sample to be measured, and the azimuth angle of the sample to be measured is accurately calibrated. The included angle between the incident plane and the periodic distribution direction of the grating area is an azimuth angle, spectral information of emergent light is collected through the detector, corresponding Mueller matrixes are provided through the ellipsometric Mueller matrix processing unit, the angle of the azimuth angle is changed, and the corresponding Mueller matrixes under different azimuth angles are recorded. The azimuth angle is calibrated by taking the fine calibration angle as a target, that is, the fine calibration angle corresponding to the M22 peak value is determined by changing the angle of the azimuth angle and recording the Mueller matrix corresponding to different azimuth angles, so that the azimuth angle of the incident light is calibrated, the calibration precision is improved, and the calibration accuracy is improved. And the accuracy of subsequent measurement is ensured.

Description

Technical Field

[0001] The present specification relates to the field of semiconductor manufacturing, and in particular 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, Optical Critical Dimension (OCD) measurement technology is a non-contact measurement method that uses optical principles to measure the critical dimensions on the chip. With the advancement of semiconductor manufacturing technology, the measurement accuracy requirements for optical critical dimensions are getting higher and higher. Therefore, in order to ensure the accuracy and reliability of OCD measurement equipment, OCD measurement equipment must be calibrated before use.

[0003] At present, the calibration of OCD measuring equipment is generally achieved by using a standard film marked with a calibration pattern. When using the standard film for calibration, the azimuth of the OCD measuring equipment is calibrated by adjusting and observing whether the calibration pattern on the standard film is aligned with the preset angle. Since the standard film and each sample to be tested have the same marking gap at the same position, after calibration, the standard film can be replaced with the sample to be tested based on the marking defect to perform OCD measurement of the sample to be tested. However, the accuracy of this calibration of OCD equipment based on the standard film 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 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, so as to partially solve the above-mentioned problems existing in the prior art.

[0006] This manual adopts the following technical solutions: This specification provides a method for finely calibrating the azimuth angle of a measuring device, wherein the measuring device comprises a measuring optical path unit, a detector and a Mueller matrix ellipsometry 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 an ellipsometric Mueller matrix processing unit; 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; 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.

[0007] Optionally, the step of changing the angle of the azimuth angle 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.

[0008] Optionally, the step of changing the angle of the azimuth angle 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.

[0009] Optionally, the step of determining a 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.

[0010] Optionally, the step of changing the angle of the azimuth angle 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.

[0011] Optionally, 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.

[0012] Optionally, the method further includes: 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.

[0013] This specification provides an azimuth fine calibration device for a measuring device, wherein the measuring device comprises a measuring optical path unit, a detector and a Mueller matrix ellipsometry 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 an ellipsometric Mueller matrix 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; 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.

[0014] The present specification provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, a method for finely calibrating the azimuth angle of a measuring device is implemented.

[0015] The present specification provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, a method for finely calibrating the azimuth angle of a measuring device is implemented.

[0016] At least one of the above-mentioned technical solutions adopted in the present specification can achieve the following beneficial effects: in a method for fine calibration of the azimuth angle of a measuring device provided in the present specification, the measuring device includes a measuring optical path unit, a detector and a Mueller matrix ellipsometric processing unit. By adjusting the measuring optical path unit, incident light is provided to enter a grating area on the surface of a 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 spectral information of the outgoing light from the grating area is collected by the detector, and the Mueller matrix corresponding to the spectral information of the outgoing light is provided by the ellipsometric Mueller matrix processing unit. The angle of the azimuth angle is then 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 M22 peak in the Mueller matrix is ​​determined as the fine calibration angle. The azimuth angle of the incident light is calibrated with the fine calibration angle as the target.

[0017] It can be seen from the above method that by changing 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 M22 peak in the Mueller matrix is ​​used as the fine calibration angle, and the azimuth angle of the incident light is calibrated with the fine calibration angle as the target, thereby improving the accuracy of the azimuth angle and ensuring the accuracy of the subsequent measurement of the optical key dimensions of the sample to be tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of this specification and constitute a part of this specification. The illustrative embodiments and descriptions of this specification are used to explain this specification and do not constitute an improper limitation on this specification. In the drawings: Figure 1 A schematic diagram of a flow chart of a method for finely calibrating the azimuth angle of a measuring device provided in this specification; Figure 2 A schematic diagram of the periodic distribution direction provided in this specification; Figure 3 A schematic diagram of a standard piece used in a rough calibration provided in this manual; Figure 4 A schematic diagram of the M22 changing with azimuth provided for this specification; Figure 5 A schematic diagram of a device for finely calibrating the azimuth angle of a measuring device provided in this specification; Figure 6 A schematic diagram of the electronic device structure corresponding to a method for finely calibrating the azimuth angle of a measuring device provided in this specification. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of this specification more clear, the technical solutions of this specification will be clearly and completely described below in combination with the specific embodiments of this specification and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of them. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this specification.

[0020] In this specification, the process of executing a method for finely calibrating the azimuth angle of a measuring device involves data processing and analysis. Therefore, in the embodiments of this specification, the process of finely calibrating the azimuth angle of a measuring device can be executed by a server. Of course, this specification does not limit which device executes the process of finely calibrating the azimuth angle of a measuring device, for example, a personal computer, a mobile terminal or other device, or in actual production, the process of finely calibrating the azimuth angle can also be executed by a machine. For the convenience of description, the following description is based on the server as the execution subject.

[0021] The technical solutions provided by the embodiments of this specification are described in detail below in conjunction with the accompanying drawings.

[0022] Figure 1 A schematic diagram of a method provided in this specification includes the following steps: S100: adjusting the measuring optical path unit to provide incident light to enter the grating area 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 area is the azimuth angle.

[0023] In one or more embodiments of the present specification, in order to collect the spectral information of the output light of the grating area on the surface of the sample to be measured through the detector in the subsequent steps, and provide the Mueller matrix corresponding to the spectral information through the ellipsometric Mueller matrix processing unit 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 the grating area on the surface of the sample to be measured.

[0024] Specifically, the server adjusts the measuring 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. 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 the measuring optical path unit, the detector, and the Mueller matrix ellipsometry processing unit.

[0025] 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 reference direction on the surface of the sample to be tested. For the sample to be tested with a periodic structure (grating area), this reference direction is usually the periodic distribution direction of the grating area in the sample to be tested. In the case of a one-dimensional grating, the periodic distribution direction is unique, such as Figure 2 As shown, it is a schematic diagram when the grating area in the sample to be tested provided in this specification is a one-dimensional grating. In this figure, the periodic distribution direction of the grating area in the sample to be tested is the X direction, so the azimuth angle of the incident light is the angle between the incident surface and the X direction. In the case of a two-dimensional grating, there are two mutually perpendicular periodic distribution directions, so a reference direction for clarifying the meaning of the azimuth angle needs to be specified, such as the X direction. Of course, in this specification, the reference direction can be set according to actual needs.

[0026] S102: 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 an ellipsometric Mueller matrix processing unit.

[0027] In one or more embodiments of the present specification, in order to adjust the azimuth angle in the subsequent steps to record the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles. In this step, the server needs to collect the spectral information of the outgoing light of the grating area through the detector, and the ellipsometric Mueller matrix processing unit provides the Mueller matrix corresponding to the spectral information of the outgoing light.

[0028] Specifically, the server may collect the spectral information of the emergent light of the grating region through a detector in the measuring device, and the ellipsometric Mueller matrix processing unit in the measuring device may provide the Mueller matrix corresponding to the spectral information of the emergent light.

[0029] It should be noted that the detector is an optical element used to detect reflected light or transmitted light, and 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 emitted light.

[0030] S104: 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.

[0031] In one or more embodiments of the present 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.

[0032] Specifically, the server needs to change the azimuth angle and record the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles.

[0033] It should be noted that the specific method of changing the azimuth angle is not limited in this specification, and can be set according to actual needs. For example, the measuring device includes a carrier for carrying the sample to be tested, and the sample to be tested is placed on the carrier, and the server controls the rotation of the rotating device under the carrier, thereby changing the azimuth angle of the incident light. At the same time, the specific method of changing the azimuth angle is not limited in this specification, and can be set according to actual needs. In one or more embodiments of this specification, the server can rotate the sample to be tested according to a preset first step length, so that in the process of rotating the sample to be tested with the first step length, the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles is recorded, wherein the first step length can be set according to the accuracy required by the actual needs, such as 1°, 0.1°, 0.01°, etc.

[0034] S106: According to each recorded Mueller matrix, determine the angle corresponding to the M22 peak in the Mueller matrix as a fine calibration angle.

[0035] In one or more embodiments of the present specification, in order to achieve fine calibration of the azimuth angle in subsequent steps, in this step, the server needs to determine the angle corresponding to the M22 peak in the Mueller matrix based on the recorded Mueller matrices as the fine calibration angle.

[0036] Specifically, the server may determine the angle corresponding to the M22 peak in the Mueller matrix according to each recorded Mueller matrix as the fine calibration angle.

[0037] It should be noted that 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 nonlinear polarization transformation, including the effects of reflection, refraction, scattering and other processes 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 polarization states of light; is the difference between the two orthogonal directions (horizontal and vertical) of linear polarization; is the difference between the two diagonal directions of linear polarization (+45° and -45°); is the difference between the left and right components of circular polarization. The Mueller matrix corresponds to the response of the sample to the incident light, as follows:

[0038]

[0039]

[0040]

[0041]

[0042] in, is the Stokes magnitude of the incident light, is the Stokes magnitude of the outgoing light, M is the Mueller matrix of the sample to be tested in response to the incident light, represents the linear polarization in the x direction, represents the linear polarization in the y direction, Indicates that the polarization direction is along the 45° linear polarization, Indicates that the polarization direction is along the -45° linear polarization, represents right-hand polarization, Indicates left-hand polarization.

[0043] That is, by collecting the Stokes values ​​of the incident light and the outgoing light, the Mueller matrix of the sample to be tested can be determined. The Mueller matrix is ​​as follows:

[0044] For polarized light, the Jones matrix can be used to describe the response of the sample to the incident light, as follows:

[0045] That is, the following formula:

[0046] in, represents the electric field with s polarization, Indicates 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 after the fully polarized light passes through the sample to be tested. Represents the s-polarization component of the incident light The s-polarization component of the outgoing light The impact of represents the p-polarization component of the incident light The p-polarization component of the outgoing light The impact of represents the p-polarization component of the incident light The s-polarization component of the outgoing light The impact of Represents the s-polarization component of the incident light The p-polarization component of the outgoing light impact.

[0047] For polarized light, the Stokes quantity is given by:

[0048]

[0049]

[0050]

[0051] Based on the above, the Mueller matrix is ​​as follows:

[0052]

[0053]

[0054]

[0055] in, represents the square of the magnitude of the elements in the Jones matrix, reflecting the intensity of each polarization component, represents the real product between the elements in the Jones matrix, reflecting the coupling effect (real part) between the polarization components, Represents the imaginary product between the elements in the Jones matrix, reflecting the coupling effect (imaginary part) between the polarization components.

[0056] When the azimuth angle of the incident light is 0°, 90°, 180° or 270°, the sample to be tested decomposes the polarized light of the incident light into s polarization and p polarization. The electromagnetic field propagation of the two polarizations is separated. Therefore, there is a Jones matrix. That is to say, when the azimuth angle is 0°, 90°, 180° or 270°, the subscripts 3 and 4 in the Mueller matrix all degenerate to 0, and the above Mueller matrix can be simplified to:

[0057] After normalization, the final Mueller matrix is ​​obtained as follows:

[0058] 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 is Therefore, in this step, the server determines the angle corresponding to the M22 peak (M22≈1) in the Mueller matrix according to the recorded Mueller matrices as the fine calibration angle, and the fine calibration angle can be 0°, 90°, 180° or 270°.

[0059] S108: Calibrate the azimuth angle of the incident light with the fine calibration angle as a target.

[0060] In one or more embodiments of the present specification, the server may calibrate the azimuth angle of the incident light based on the fine calibration angle determined in step S106.

[0061] Specifically, the server calibrates the azimuth angle of the incident light with the goal of determining the fine calibration angle in step S106.

[0062] It should be noted that, in the actual calibration process, the server can roughly calibrate the azimuth of the incident light, that is, roughly align it with 0°, 90°, 180° or 270°, so that in step S104, when adjusting the azimuth angle, it is only necessary to search for the fine calibration angle corresponding to the "M22 peak in the Mueller matrix" within the preset angle range, thereby reducing the search range to improve the calibration efficiency, and the size of the preset angle range is not limited in this specification, and can be set according to actual needs. At the same time, the above "calibrating the azimuth of the incident light with the fine calibration angle as the goal" means that when the azimuth is at the fine calibration angle, the azimuth should be a specific angle (0°, 90°, 180° or 270°), so if the actual azimuth is at other angles, it is necessary to calibrate so that the azimuth is at the specific angle.

[0063] In the above method, the server changes the azimuth angle and records the Mueller matrix corresponding to the spectral information of the outgoing light at different azimuth angles, thereby determining the fine calibration angle corresponding to the M22 peak in the Mueller matrix. Finally, the azimuth angle of the incident light is calibrated with the fine calibration angle as the target, thereby improving the calibration accuracy of the azimuth angle and ensuring the accuracy of subsequent measurements of the optical key dimensions of the sample to be tested.

[0064] In addition, this specification provides a process in which the server performs a rough calibration of the azimuth of the measuring device before finely calibrating the azimuth of the measuring device, as follows: In one or more embodiments of the present specification, the server can adjust the translation device carrying the standard film in the measuring equipment through a standard film marked with a calibration pattern, so that the standard film is in a preset position, and based on the calibration pattern on the standard film, adjust the azimuth angle of the incident light provided by the measuring optical path unit, and according to the gap that is consistent between the sample to be tested and the standard film, the standard film can be replaced with the sample to be tested.

[0065] It should be noted that after the rough calibration based on the standard film, the azimuth angle of the incident light should be a specific angle, such as 0°, 90°, 180° or 270°. However, due to the poor accuracy of the standard film calibration, there is a deviation in the calibration of the azimuth angle. Therefore, after the rough calibration, the calibration accuracy of the azimuth angle can be improved through fine calibration in steps S100~S108.

[0066] like Figure 3As shown, it is a schematic diagram of the standard film provided in this specification. In this figure, the calibration pattern is composed of a row of crosses. The server adjusts the translation device carrying the standard film in the measuring equipment so that the first cross is captured within the detection range. Then, the second cross can be captured by translating the preset interval. If the second cross is not captured after translating the preset interval, 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 the crosses in the calibration pattern can be captured in turn according to the translation of the preset interval. 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.

[0067] In addition, this specification provides a specific implementation method for changing the azimuth angle, that is, before changing the azimuth angle according to the first step length required for calibration accuracy in step S104, the server can rotate the sample to be tested 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 tested according to the first step length to obtain the fine calibration angle, thereby reducing the number of rotations and improving efficiency, as follows: In one or more embodiments of the present specification, first, the server needs to rotate the sample to be tested within a preset angle range according to a preset second step length, and the second step length is greater than the first step length. Then, the server needs to record 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 determine the angle corresponding to the M22 peak in the Mueller matrix as a rough calibration angle.

[0068] Secondly, the server may determine a fine rotation range based on the determined rough calibration angle, the fine rotation range being smaller than the preset angle range. Finally, the server may rotate the sample to be tested according to the first step until the rotation range reaches the fine rotation range.

[0069] It should be noted that the process of determining the fine rotation range based on the rough calibration angle is not limited in this specification and can be set according to actual needs. Figure 4As shown in the figure, the curve of M22 in the Mueller matrix of the one-dimensional grating responding to the incident light changes with the azimuth angle at different wavelengths provided in this specification. In this figure, Si Grating refers to the grating structure manufactured on silicon (Si) material; AOI refers to the angle of incidence, which is the angle between the incident light and the surface normal of the sample to be tested; A refers to the analysis angle; P refers to the deflection angle; Phi in the transverse coordinate refers to the azimuth angle. That is to say, a parabolic trend is presented around a specific angle (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 tested based on the second step length may not be the angle (fine calibration angle) corresponding to the M22 peak under the required accuracy (first step length). In some cases, the fine calibration angle may appear between the angle after "the 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 "the rough calibration angle plus the second step length" and the rough calibration angle. Therefore, in one or more embodiments of the present specification, the server may determine an angle that differs from the rough calibration angle by a second step as a boundary value, and determine a fine rotation range based on the obtained boundary value.

[0070] In addition, this specification provides a process for changing the azimuth angle of the incident light after determining the rotation direction, as follows: In one or more embodiments of the present 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.

[0071] Specifically, first, the server can determine the adjacent azimuth angle of the current azimuth angle of the incident light, wherein the specific method of determining the adjacent azimuth angle is not limited in the present 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.

[0072] Secondly, the server can determine the Mueller matrices corresponding to the spectral information of the emitted light at the current azimuth and the adjacent azimuth, and then determine the direction in which M22 increases based on the magnitude relationship of M22 in each determined Mueller matrix as the rotation direction. Finally, the server can rotate the sample to be tested along the determined rotation direction starting from the current azimuth until the angle of the azimuth after rotation reaches any boundary value in the preset angle range.

[0073] It should be noted that if the value of M22 in the Mueller matrix corresponding to the spectral information of the emitted light is the largest at the current azimuth, it means that the current azimuth does not need to be calibrated. Therefore, in one or more embodiments of the present specification, the server may determine the adjacent azimuths of the current azimuth before changing the azimuth angle, and then determine whether the current azimuth needs to be calibrated based on the size relationship between M22 in the Mueller matrix at the adjacent azimuth and M22 in the Mueller matrix at the current azimuth, so as to avoid an invalid calibration process.

[0074] In addition, this manual provides a process for adjusting the azimuth angle to the target azimuth angle required for "optical critical dimension measurement of the sample to be measured" after calibration, as follows: In one or more embodiments of the present specification, the server may use the azimuth angle required for measuring the sample to be tested as the target azimuth angle, and then determine the target step length 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 length, and perform optical critical dimension measurement on the sample to be tested based on the adjusted measuring device.

[0075] The above is a method for finely calibrating 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 finely calibrating the azimuth angle of a measuring device, such as Figure 5 shown.

[0076] Adjust the optical path module 500, adjust the measuring optical path unit, 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 measuring optical path module 501 collects the spectral information of the outgoing light of the grating area through a detector, and provides a Mueller matrix corresponding to the spectral information of the outgoing light through an ellipsometric Mueller matrix processing unit; An azimuth adjustment module 502 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; A fine calibration angle module 503 determines, according to each recorded Mueller matrix, an angle corresponding to the M22 peak in the Mueller matrix as a fine calibration angle; The calibration module 504 calibrates the azimuth angle of the incident light with the fine calibration angle as a target.

[0077] Optionally, the azimuth adjustment module 502 is specifically configured to rotate the sample to be tested according to a preset first step length until the rotation range reaches a preset angle range.

[0078] Optionally, the azimuth adjustment module 502 can also be used to rotate the sample to be tested within a preset angle range according to a preset second step length, and the second step length is larger than the first step length; record the Mueller matrix corresponding to the spectral information of the emergent light at each angle in the process of rotating the sample to be tested with the second step length, and determine the angle corresponding to the M22 peak in the Mueller matrix as a rough calibration angle; determine a fine rotation range according to the rough calibration angle, and the fine rotation range is smaller than the angle range; rotate the sample to be tested according to the first step length until the rotation range reaches the fine rotation range.

[0079] Optionally, the azimuth adjustment module 502 may be further configured to determine an angle that differs from the rough calibration angle by the second step length as a boundary value; and determine a fine rotation range according to the boundary value.

[0080] Optionally, the azimuth adjustment module 502 can also be used to determine the adjacent azimuths of the current azimuth of the incident light; determine the Mueller matrices corresponding to the spectral information of the outgoing light at the current azimuth and the adjacent azimuths; determine the direction in which M22 increases as the rotation direction based on the size relationship of M22 in each determined Mueller matrix; and rotate the sample to be tested along the rotation direction starting from the current azimuth until the azimuth of the incident light reaches any boundary value in a preset angle range after rotation.

[0081] Optionally, the device also includes a coarse calibration module 505, which is specifically used to determine a standard film marked with a calibration pattern; adjust the translation device carrying the standard film in the measuring device so that the standard film is in 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 film with the sample to be tested according to the notch that is consistent between the sample to be tested and the standard film.

[0082] Optionally, the apparatus further includes an optical measurement module 506, which is specifically used to use the azimuth angle required for measuring the sample to be tested as the target azimuth angle; determine the target step length according to the fine calibration angle and the target azimuth angle; adjust the measuring device according to the target step length, and perform optical critical dimension measurement on the sample to be tested through the adjusted measuring device.

[0083] This specification also provides a computer-readable storage medium, which stores a computer program, which can be used to execute the above Figure 1 A method for finely calibrating the azimuth angle of a measuring device is provided.

[0084] This manual also provides Figure 6The schematic structure diagram of an electronic device for a method for finely calibrating the azimuth angle of a measuring device is shown in FIG. Figure 6 As mentioned above, at the hardware level, the device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory, and may also include other hardware required for the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to achieve the above Figure 1 The method for finely calibrating the azimuth angle of a measuring device. Of course, in addition to the software implementation, this specification does not exclude other implementations, such as logic devices or a combination of software and hardware, etc., that is, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0085] In the 1990s, it was very clear whether the improvement of a technology was hardware improvement (for example, improvement of the circuit structure of diodes, transistors, switches, etc.) or software improvement (improvement of the method flow). However, with the development of technology, many improvements of the method flow today can be regarded as direct improvements of the hardware circuit structure. 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 the improvement of a method flow cannot be implemented with hardware entity modules. For example, a programmable logic device (PLD) (such as a field programmable gate array (FPGA)) is such an integrated circuit whose logical function is determined by the user's programming of the device. Designers can "integrate" a digital system on a PLD by programming it themselves, without having to ask chip manufacturers to design and make dedicated integrated circuit chips. Moreover, nowadays, instead of manually making integrated circuit chips, this kind of programming is mostly implemented by "logic compiler" software, which is similar to the software compiler used when developing and writing programs, and the original code before compilation must also be written in a specific programming language, which is called hardware description language (HDL). There is not only one kind of HDL, but many kinds, 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 are VHDL (Very-High-Speed ​​Integrated Circuit Hardware Description Language) and Verilog. Those skilled in the art should also know that it is only necessary to program the method flow slightly in the above-mentioned hardware description languages ​​and program it into the integrated circuit, and then it is easy to obtain the hardware circuit that implements the logic method flow.

[0086] The controller may be implemented in any suitable manner, for example, the controller may take the form of a microprocessor or processor and a computer-readable medium storing a computer-readable program code (e.g., software or firmware) executable by the (micro)processor, a logic gate, a switch, an application-specific integrated circuit (ASIC), a programmable logic controller, and an embedded microcontroller, examples of which include but are not limited to the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F320, and the memory controller may also be implemented as part of the control logic of the memory. It is also known to those skilled in the art that, in addition to implementing the controller in a purely computer-readable program code manner, the controller may be implemented in the form of a logic gate, a switch, an application-specific integrated circuit, a programmable logic controller, and an embedded microcontroller by logically programming the method steps. Therefore, such a controller may be considered as a hardware component, and the devices for implementing various functions included therein may also be considered as structures within the hardware component. Or even, the devices for implementing various functions may be considered as both software modules for implementing the method and structures within the hardware component.

[0087] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may 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.

[0088] For the convenience of description, the above device is described in 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.

[0089] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0090] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0091] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0092] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0093] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0094] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] The above description is only an embodiment of the present specification and is not intended to limit the present specification. For those skilled in the art, the present specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present specification shall be included in the scope of the claims of the present 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 an ellipsometric Mueller matrix processing unit; 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; 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 an ellipsometric Mueller matrix 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; 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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